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 // SPDX-License-Identifier: GPL-2.0
 /*
  * Performance events core code:
  *
  *  Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
  *  Copyright (C) 2008-2011 Red Hat, Inc., Ingo Molnar
  *  Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra
  *  Copyright  ©  2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
  */
 
 #include <linux/fs.h>
 #include <linux/mm.h>
 #include <linux/cpu.h>
 #include <linux/smp.h>
 #include <linux/idr.h>
 #include <linux/file.h>
 #include <linux/poll.h>
 #include <linux/slab.h>
 #include <linux/hash.h>
 #include <linux/tick.h>
 #include <linux/sysfs.h>
 #include <linux/dcache.h>
 #include <linux/percpu.h>
 #include <linux/ptrace.h>
 #include <linux/reboot.h>
 #include <linux/vmstat.h>
 #include <linux/device.h>
 #include <linux/export.h>
 #include <linux/vmalloc.h>
 #include <linux/hardirq.h>
 #include <linux/hugetlb.h>
 #include <linux/rculist.h>
 #include <linux/uaccess.h>
 #include <linux/syscalls.h>
 #include <linux/anon_inodes.h>
 #include <linux/kernel_stat.h>
 #include <linux/cgroup.h>
 #include <linux/perf_event.h>
 #include <linux/trace_events.h>
 #include <linux/hw_breakpoint.h>
 #include <linux/mm_types.h>
 #include <linux/module.h>
 #include <linux/mman.h>
 #include <linux/compat.h>
 #include <linux/bpf.h>
 #include <linux/filter.h>
 #include <linux/namei.h>
 #include <linux/parser.h>
 #include <linux/sched/clock.h>
 #include <linux/sched/mm.h>
 #include <linux/proc_ns.h>
 #include <linux/mount.h>
 #include <linux/min_heap.h>
 #include <linux/highmem.h>
 #include <linux/pgtable.h>
 #include <linux/buildid.h>
 
 #include "internal.h"
 
 #include <asm/irq_regs.h>
 
 typedef int (*remote_function_f)(void *);
 
 struct remote_function_call {
     struct task_struct  *p;
     remote_function_f   func;
     void            *info;
     int         ret;
 };
 
 static void remote_function(void *data)
 {
     struct remote_function_call *tfc = data;
     struct task_struct *p = tfc->p;
 
     if (p) {
         /* -EAGAIN */
         if (task_cpu(p) != smp_processor_id())
             return;
 
         /*
          * Now that we're on right CPU with IRQs disabled, we can test
          * if we hit the right task without races.
          */
 
         tfc->ret = -ESRCH; /* No such (running) process */
         if (p != current)
             return;
     }
 
     tfc->ret = tfc->func(tfc->info);
 }
 
 /**
  * task_function_call - call a function on the cpu on which a task runs
  * @p:      the task to evaluate
  * @func:   the function to be called
  * @info:   the function call argument
  *
  * Calls the function @func when the task is currently running. This might
  * be on the current CPU, which just calls the function directly.  This will
  * retry due to any failures in smp_call_function_single(), such as if the
  * task_cpu() goes offline concurrently.
  *
  * returns @func return value or -ESRCH or -ENXIO when the process isn't running
  */
 static int
 task_function_call(struct task_struct *p, remote_function_f func, void *info)
 {
     struct remote_function_call data = {
         .p  = p,
         .func   = func,
         .info   = info,
         .ret    = -EAGAIN,
     };
     int ret;
 
     for (;;) {
         ret = smp_call_function_single(task_cpu(p), remote_function,
                            &data, 1);
         if (!ret)
             ret = data.ret;
 
         if (ret != -EAGAIN)
             break;
 
         cond_resched();
     }
 
     return ret;
 }
 
 /**
  * cpu_function_call - call a function on the cpu
  * @cpu:    target cpu to queue this function
  * @func:   the function to be called
  * @info:   the function call argument
  *
  * Calls the function @func on the remote cpu.
  *
  * returns: @func return value or -ENXIO when the cpu is offline
  */
 static int cpu_function_call(int cpu, remote_function_f func, void *info)
 {
     struct remote_function_call data = {
         .p  = NULL,
         .func   = func,
         .info   = info,
         .ret    = -ENXIO, /* No such CPU */
     };
 
     smp_call_function_single(cpu, remote_function, &data, 1);
 
     return data.ret;
 }
 
 static inline struct perf_cpu_context *
 __get_cpu_context(struct perf_event_context *ctx)
 {
     return this_cpu_ptr(ctx->pmu->pmu_cpu_context);
 }
 
 static void perf_ctx_lock(struct perf_cpu_context *cpuctx,
               struct perf_event_context *ctx)
 {
     raw_spin_lock(&cpuctx->ctx.lock);
     if (ctx)
         raw_spin_lock(&ctx->lock);
 }
 
 static void perf_ctx_unlock(struct perf_cpu_context *cpuctx,
                 struct perf_event_context *ctx)
 {
     if (ctx)
         raw_spin_unlock(&ctx->lock);
     raw_spin_unlock(&cpuctx->ctx.lock);
 }
 
 #define TASK_TOMBSTONE ((void *)-1L)
 
 static bool is_kernel_event(struct perf_event *event)
 {
     return READ_ONCE(event->owner) == TASK_TOMBSTONE;
 }
 
 /*
  * On task ctx scheduling...
  *
  * When !ctx->nr_events a task context will not be scheduled. This means
  * we can disable the scheduler hooks (for performance) without leaving
  * pending task ctx state.
  *
  * This however results in two special cases:
  *
  *  - removing the last event from a task ctx; this is relatively straight
  *    forward and is done in __perf_remove_from_context.
  *
  *  - adding the first event to a task ctx; this is tricky because we cannot
  *    rely on ctx->is_active and therefore cannot use event_function_call().
  *    See perf_install_in_context().
  *
  * If ctx->nr_events, then ctx->is_active and cpuctx->task_ctx are set.
  */
 
 typedef void (*event_f)(struct perf_event *, struct perf_cpu_context *,
             struct perf_event_context *, void *);
 
 struct event_function_struct {
     struct perf_event *event;
     event_f func;
     void *data;
 };
 
 static int event_function(void *info)
 {
     struct event_function_struct *efs = info;
     struct perf_event *event = efs->event;
     struct perf_event_context *ctx = event->ctx;
     struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
     struct perf_event_context *task_ctx = cpuctx->task_ctx;
     int ret = 0;
 
     lockdep_assert_irqs_disabled();
 
     perf_ctx_lock(cpuctx, task_ctx);
     /*
      * Since we do the IPI call without holding ctx->lock things can have
      * changed, double check we hit the task we set out to hit.
      */
     if (ctx->task) {
         if (ctx->task != current) {
             ret = -ESRCH;
             goto unlock;
         }
 
         /*
          * We only use event_function_call() on established contexts,
          * and event_function() is only ever called when active (or
          * rather, we'll have bailed in task_function_call() or the
          * above ctx->task != current test), therefore we must have
          * ctx->is_active here.
          */
         WARN_ON_ONCE(!ctx->is_active);
         /*
          * And since we have ctx->is_active, cpuctx->task_ctx must
          * match.
          */
         WARN_ON_ONCE(task_ctx != ctx);
     } else {
         WARN_ON_ONCE(&cpuctx->ctx != ctx);
     }
 
     efs->func(event, cpuctx, ctx, efs->data);
 unlock:
     perf_ctx_unlock(cpuctx, task_ctx);
 
     return ret;
 }
 
 static void event_function_call(struct perf_event *event, event_f func, void *data)
 {
     struct perf_event_context *ctx = event->ctx;
     struct task_struct *task = READ_ONCE(ctx->task); /* verified in event_function */
     struct event_function_struct efs = {
         .event = event,
         .func = func,
         .data = data,
     };
 
     if (!event->parent) {
         /*
          * If this is a !child event, we must hold ctx::mutex to
          * stabilize the event->ctx relation. See
          * perf_event_ctx_lock().
          */
         lockdep_assert_held(&ctx->mutex);
     }
 
     if (!task) {
         cpu_function_call(event->cpu, event_function, &efs);
         return;
     }
 
     if (task == TASK_TOMBSTONE)
         return;
 
 again:
     if (!task_function_call(task, event_function, &efs))
         return;
 
     raw_spin_lock_irq(&ctx->lock);
     /*
      * Reload the task pointer, it might have been changed by
      * a concurrent perf_event_context_sched_out().
      */
     task = ctx->task;
     if (task == TASK_TOMBSTONE) {
         raw_spin_unlock_irq(&ctx->lock);
         return;
     }
     if (ctx->is_active) {
         raw_spin_unlock_irq(&ctx->lock);
         goto again;
     }
     func(event, NULL, ctx, data);
     raw_spin_unlock_irq(&ctx->lock);
 }
 
 /*
  * Similar to event_function_call() + event_function(), but hard assumes IRQs
  * are already disabled and we're on the right CPU.
  */
 static void event_function_local(struct perf_event *event, event_f func, void *data)
 {
     struct perf_event_context *ctx = event->ctx;
     struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
     struct task_struct *task = READ_ONCE(ctx->task);
     struct perf_event_context *task_ctx = NULL;
 
     lockdep_assert_irqs_disabled();
 
     if (task) {
         if (task == TASK_TOMBSTONE)
             return;
 
         task_ctx = ctx;
     }
 
     perf_ctx_lock(cpuctx, task_ctx);
 
     task = ctx->task;
     if (task == TASK_TOMBSTONE)
         goto unlock;
 
     if (task) {
         /*
          * We must be either inactive or active and the right task,
          * otherwise we're screwed, since we cannot IPI to somewhere
          * else.
          */
         if (ctx->is_active) {
             if (WARN_ON_ONCE(task != current))
                 goto unlock;
 
             if (WARN_ON_ONCE(cpuctx->task_ctx != ctx))
                 goto unlock;
         }
     } else {
         WARN_ON_ONCE(&cpuctx->ctx != ctx);
     }
 
     func(event, cpuctx, ctx, data);
 unlock:
     perf_ctx_unlock(cpuctx, task_ctx);
 }
 
 #define PERF_FLAG_ALL (PERF_FLAG_FD_NO_GROUP |\
                PERF_FLAG_FD_OUTPUT  |\
                PERF_FLAG_PID_CGROUP |\
                PERF_FLAG_FD_CLOEXEC)
 
 /*
  * branch priv levels that need permission checks
  */
 #define PERF_SAMPLE_BRANCH_PERM_PLM \
     (PERF_SAMPLE_BRANCH_KERNEL |\
      PERF_SAMPLE_BRANCH_HV)
 
 enum event_type_t {
     EVENT_FLEXIBLE = 0x1,
     EVENT_PINNED = 0x2,
     EVENT_TIME = 0x4,
     /* see ctx_resched() for details */
     EVENT_CPU = 0x8,
     EVENT_ALL = EVENT_FLEXIBLE | EVENT_PINNED,
 };
 
 /*
  * perf_sched_events : >0 events exist
  * perf_cgroup_events: >0 per-cpu cgroup events exist on this cpu
  */
 
 static void perf_sched_delayed(struct work_struct *work);
 DEFINE_STATIC_KEY_FALSE(perf_sched_events);
 static DECLARE_DELAYED_WORK(perf_sched_work, perf_sched_delayed);
 static DEFINE_MUTEX(perf_sched_mutex);
 static atomic_t perf_sched_count;
 
 static DEFINE_PER_CPU(atomic_t, perf_cgroup_events);
 static DEFINE_PER_CPU(int, perf_sched_cb_usages);
 static DEFINE_PER_CPU(struct pmu_event_list, pmu_sb_events);
 
 static atomic_t nr_mmap_events __read_mostly;
 static atomic_t nr_comm_events __read_mostly;
 static atomic_t nr_namespaces_events __read_mostly;
 static atomic_t nr_task_events __read_mostly;
 static atomic_t nr_freq_events __read_mostly;
 static atomic_t nr_switch_events __read_mostly;
 static atomic_t nr_ksymbol_events __read_mostly;
 static atomic_t nr_bpf_events __read_mostly;
 static atomic_t nr_cgroup_events __read_mostly;
 static atomic_t nr_text_poke_events __read_mostly;
 static atomic_t nr_build_id_events __read_mostly;
 
 static LIST_HEAD(pmus);
 static DEFINE_MUTEX(pmus_lock);
 static struct srcu_struct pmus_srcu;
 static cpumask_var_t perf_online_mask;
 static struct kmem_cache *perf_event_cache;
 
 /*
  * perf event paranoia level:
  *  -1 - not paranoid at all
  *   0 - disallow raw tracepoint access for unpriv
  *   1 - disallow cpu events for unpriv
  *   2 - disallow kernel profiling for unpriv
  */
 int sysctl_perf_event_paranoid __read_mostly = 2;
 
 /* Minimum for 512 kiB + 1 user control page */
 int sysctl_perf_event_mlock __read_mostly = 512 + (PAGE_SIZE / 1024); /* 'free' kiB per user */
 
 /*
  * max perf event sample rate
  */
 #define DEFAULT_MAX_SAMPLE_RATE     100000
 #define DEFAULT_SAMPLE_PERIOD_NS    (NSEC_PER_SEC / DEFAULT_MAX_SAMPLE_RATE)
 #define DEFAULT_CPU_TIME_MAX_PERCENT    25
 
 int sysctl_perf_event_sample_rate __read_mostly = DEFAULT_MAX_SAMPLE_RATE;
 
 static int max_samples_per_tick __read_mostly   = DIV_ROUND_UP(DEFAULT_MAX_SAMPLE_RATE, HZ);
 static int perf_sample_period_ns __read_mostly  = DEFAULT_SAMPLE_PERIOD_NS;
 
 static int perf_sample_allowed_ns __read_mostly =
     DEFAULT_SAMPLE_PERIOD_NS * DEFAULT_CPU_TIME_MAX_PERCENT / 100;
 
 static void update_perf_cpu_limits(void)
 {
     u64 tmp = perf_sample_period_ns;
 
     tmp *= sysctl_perf_cpu_time_max_percent;
     tmp = div_u64(tmp, 100);
     if (!tmp)
         tmp = 1;
 
     WRITE_ONCE(perf_sample_allowed_ns, tmp);
 }
 
 static bool perf_rotate_context(struct perf_cpu_context *cpuctx);
 
 int perf_proc_update_handler(struct ctl_table *table, int write,
         void *buffer, size_t *lenp, loff_t *ppos)
 {
     int ret;
     int perf_cpu = sysctl_perf_cpu_time_max_percent;
     /*
      * If throttling is disabled don't allow the write:
      */
     if (write && (perf_cpu == 100 || perf_cpu == 0))
         return -EINVAL;
 
     ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
     if (ret || !write)
         return ret;
 
     max_samples_per_tick = DIV_ROUND_UP(sysctl_perf_event_sample_rate, HZ);
     perf_sample_period_ns = NSEC_PER_SEC / sysctl_perf_event_sample_rate;
     update_perf_cpu_limits();
 
     return 0;
 }
 
 int sysctl_perf_cpu_time_max_percent __read_mostly = DEFAULT_CPU_TIME_MAX_PERCENT;
 
 int perf_cpu_time_max_percent_handler(struct ctl_table *table, int write,
         void *buffer, size_t *lenp, loff_t *ppos)
 {
     int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
 
     if (ret || !write)
         return ret;
 
     if (sysctl_perf_cpu_time_max_percent == 100 ||
         sysctl_perf_cpu_time_max_percent == 0) {
         printk(KERN_WARNING
                "perf: Dynamic interrupt throttling disabled, can hang your system!\n");
         WRITE_ONCE(perf_sample_allowed_ns, 0);
     } else {
         update_perf_cpu_limits();
     }
 
     return 0;
 }
 
 /*
  * perf samples are done in some very critical code paths (NMIs).
  * If they take too much CPU time, the system can lock up and not
  * get any real work done.  This will drop the sample rate when
  * we detect that events are taking too long.
  */
 #define NR_ACCUMULATED_SAMPLES 128
 static DEFINE_PER_CPU(u64, running_sample_length);
 
 static u64 __report_avg;
 static u64 __report_allowed;
 
 static void perf_duration_warn(struct irq_work *w)
 {
     printk_ratelimited(KERN_INFO
         "perf: interrupt took too long (%lld > %lld), lowering "
         "kernel.perf_event_max_sample_rate to %d\n",
         __report_avg, __report_allowed,
         sysctl_perf_event_sample_rate);
 }
 
 static DEFINE_IRQ_WORK(perf_duration_work, perf_duration_warn);
 
 void perf_sample_event_took(u64 sample_len_ns)
 {
     u64 max_len = READ_ONCE(perf_sample_allowed_ns);
     u64 running_len;
     u64 avg_len;
     u32 max;
 
     if (max_len == 0)
         return;
 
     /* Decay the counter by 1 average sample. */
     running_len = __this_cpu_read(running_sample_length);
     running_len -= running_len/NR_ACCUMULATED_SAMPLES;
     running_len += sample_len_ns;
     __this_cpu_write(running_sample_length, running_len);
 
     /*
      * Note: this will be biased artifically low until we have
      * seen NR_ACCUMULATED_SAMPLES. Doing it this way keeps us
      * from having to maintain a count.
      */
     avg_len = running_len/NR_ACCUMULATED_SAMPLES;
     if (avg_len <= max_len)
         return;
 
     __report_avg = avg_len;
     __report_allowed = max_len;
 
     /*
      * Compute a throttle threshold 25% below the current duration.
      */
     avg_len += avg_len / 4;
     max = (TICK_NSEC / 100) * sysctl_perf_cpu_time_max_percent;
     if (avg_len < max)
         max /= (u32)avg_len;
     else
         max = 1;
 
     WRITE_ONCE(perf_sample_allowed_ns, avg_len);
     WRITE_ONCE(max_samples_per_tick, max);
 
     sysctl_perf_event_sample_rate = max * HZ;
     perf_sample_period_ns = NSEC_PER_SEC / sysctl_perf_event_sample_rate;
 
     if (!irq_work_queue(&perf_duration_work)) {
         early_printk("perf: interrupt took too long (%lld > %lld), lowering "
                  "kernel.perf_event_max_sample_rate to %d\n",
                  __report_avg, __report_allowed,
                  sysctl_perf_event_sample_rate);
     }
 }
 
 static atomic64_t perf_event_id;
 
 static void cpu_ctx_sched_out(struct perf_cpu_context *cpuctx,
                   enum event_type_t event_type);
 
 static void cpu_ctx_sched_in(struct perf_cpu_context *cpuctx,
                  enum event_type_t event_type);
 
 static void update_context_time(struct perf_event_context *ctx);
 static u64 perf_event_time(struct perf_event *event);
 
 void __weak perf_event_print_debug(void)    { }
 
 static inline u64 perf_clock(void)
 {
     return local_clock();
 }
 
 static inline u64 perf_event_clock(struct perf_event *event)
 {
     return event->clock();
 }
 
 /*
  * State based event timekeeping...
  *
  * The basic idea is to use event->state to determine which (if any) time
  * fields to increment with the current delta. This means we only need to
  * update timestamps when we change state or when they are explicitly requested
  * (read).
  *
  * Event groups make things a little more complicated, but not terribly so. The
  * rules for a group are that if the group leader is OFF the entire group is
  * OFF, irrespecive of what the group member states are. This results in
  * __perf_effective_state().
  *
  * A futher ramification is that when a group leader flips between OFF and
  * !OFF, we need to update all group member times.
  *
  *
  * NOTE: perf_event_time() is based on the (cgroup) context time, and thus we
  * need to make sure the relevant context time is updated before we try and
  * update our timestamps.
  */
 
 static __always_inline enum perf_event_state
 __perf_effective_state(struct perf_event *event)
 {
     struct perf_event *leader = event->group_leader;
 
     if (leader->state <= PERF_EVENT_STATE_OFF)
         return leader->state;
 
     return event->state;
 }
 
 static __always_inline void
 __perf_update_times(struct perf_event *event, u64 now, u64 *enabled, u64 *running)
 {
     enum perf_event_state state = __perf_effective_state(event);
     u64 delta = now - event->tstamp;
 
     *enabled = event->total_time_enabled;
     if (state >= PERF_EVENT_STATE_INACTIVE)
         *enabled += delta;
 
     *running = event->total_time_running;
     if (state >= PERF_EVENT_STATE_ACTIVE)
         *running += delta;
 }
 
 static void perf_event_update_time(struct perf_event *event)
 {
     u64 now = perf_event_time(event);
 
     __perf_update_times(event, now, &event->total_time_enabled,
                     &event->total_time_running);
     event->tstamp = now;
 }
 
 static void perf_event_update_sibling_time(struct perf_event *leader)
 {
     struct perf_event *sibling;
 
     for_each_sibling_event(sibling, leader)
         perf_event_update_time(sibling);
 }
 
 static void
 perf_event_set_state(struct perf_event *event, enum perf_event_state state)
 {
     if (event->state == state)
         return;
 
     perf_event_update_time(event);
     /*
      * If a group leader gets enabled/disabled all its siblings
      * are affected too.
      */
     if ((event->state < 0) ^ (state < 0))
         perf_event_update_sibling_time(event);
 
     WRITE_ONCE(event->state, state);
 }
 
 /*
  * UP store-release, load-acquire
  */
 
 #define __store_release(ptr, val)                   \
 do {                                    \
     barrier();                          \
     WRITE_ONCE(*(ptr), (val));                  \
 } while (0)
 
 #define __load_acquire(ptr)                     \
 ({                                  \
     __unqual_scalar_typeof(*(ptr)) ___p = READ_ONCE(*(ptr));    \
     barrier();                          \
     ___p;                               \
 })
 
 #ifdef CONFIG_CGROUP_PERF
 
 static inline bool
 perf_cgroup_match(struct perf_event *event)
 {
     struct perf_event_context *ctx = event->ctx;
     struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
 
     /* @event doesn't care about cgroup */
     if (!event->cgrp)
         return true;
 
     /* wants specific cgroup scope but @cpuctx isn't associated with any */
     if (!cpuctx->cgrp)
         return false;
 
     /*
      * Cgroup scoping is recursive.  An event enabled for a cgroup is
      * also enabled for all its descendant cgroups.  If @cpuctx's
      * cgroup is a descendant of @event's (the test covers identity
      * case), it's a match.
      */
     return cgroup_is_descendant(cpuctx->cgrp->css.cgroup,
                     event->cgrp->css.cgroup);
 }
 
 static inline void perf_detach_cgroup(struct perf_event *event)
 {
     css_put(&event->cgrp->css);
     event->cgrp = NULL;
 }
 
 static inline int is_cgroup_event(struct perf_event *event)
 {
     return event->cgrp != NULL;
 }
 
 static inline u64 perf_cgroup_event_time(struct perf_event *event)
 {
     struct perf_cgroup_info *t;
 
     t = per_cpu_ptr(event->cgrp->info, event->cpu);
     return t->time;
 }
 
 static inline u64 perf_cgroup_event_time_now(struct perf_event *event, u64 now)
 {
     struct perf_cgroup_info *t;
 
     t = per_cpu_ptr(event->cgrp->info, event->cpu);
     if (!__load_acquire(&t->active))
         return t->time;
     now += READ_ONCE(t->timeoffset);
     return now;
 }
 
 static inline void __update_cgrp_time(struct perf_cgroup_info *info, u64 now, bool adv)
 {
     if (adv)
         info->time += now - info->timestamp;
     info->timestamp = now;
     /*
      * see update_context_time()
      */
     WRITE_ONCE(info->timeoffset, info->time - info->timestamp);
 }
 
 static inline void update_cgrp_time_from_cpuctx(struct perf_cpu_context *cpuctx, bool final)
 {
     struct perf_cgroup *cgrp = cpuctx->cgrp;
     struct cgroup_subsys_state *css;
     struct perf_cgroup_info *info;
 
     if (cgrp) {
         u64 now = perf_clock();
 
         for (css = &cgrp->css; css; css = css->parent) {
             cgrp = container_of(css, struct perf_cgroup, css);
             info = this_cpu_ptr(cgrp->info);
 
             __update_cgrp_time(info, now, true);
             if (final)
                 __store_release(&info->active, 0);
         }
     }
 }
 
 static inline void update_cgrp_time_from_event(struct perf_event *event)
 {
     struct perf_cgroup_info *info;
 
     /*
      * ensure we access cgroup data only when needed and
      * when we know the cgroup is pinned (css_get)
      */
     if (!is_cgroup_event(event))
         return;
 
     info = this_cpu_ptr(event->cgrp->info);
     /*
      * Do not update time when cgroup is not active
      */
     if (info->active)
         __update_cgrp_time(info, perf_clock(), true);
 }
 
 static inline void
 perf_cgroup_set_timestamp(struct perf_cpu_context *cpuctx)
 {
     struct perf_event_context *ctx = &cpuctx->ctx;
     struct perf_cgroup *cgrp = cpuctx->cgrp;
     struct perf_cgroup_info *info;
     struct cgroup_subsys_state *css;
 
     /*
      * ctx->lock held by caller
      * ensure we do not access cgroup data
      * unless we have the cgroup pinned (css_get)
      */
     if (!cgrp)
         return;
 
     WARN_ON_ONCE(!ctx->nr_cgroups);
 
     for (css = &cgrp->css; css; css = css->parent) {
         cgrp = container_of(css, struct perf_cgroup, css);
         info = this_cpu_ptr(cgrp->info);
         __update_cgrp_time(info, ctx->timestamp, false);
         __store_release(&info->active, 1);
     }
 }
 
 static DEFINE_PER_CPU(struct list_head, cgrp_cpuctx_list);
 
 /*
  * reschedule events based on the cgroup constraint of task.
  */
 static void perf_cgroup_switch(struct task_struct *task)
 {
     struct perf_cgroup *cgrp;
     struct perf_cpu_context *cpuctx, *tmp;
     struct list_head *list;
     unsigned long flags;
 
     /*
      * Disable interrupts and preemption to avoid this CPU's
      * cgrp_cpuctx_entry to change under us.
      */
     local_irq_save(flags);
 
     cgrp = perf_cgroup_from_task(task, NULL);
 
     list = this_cpu_ptr(&cgrp_cpuctx_list);
     list_for_each_entry_safe(cpuctx, tmp, list, cgrp_cpuctx_entry) {
         WARN_ON_ONCE(cpuctx->ctx.nr_cgroups == 0);
         if (READ_ONCE(cpuctx->cgrp) == cgrp)
             continue;
 
         perf_ctx_lock(cpuctx, cpuctx->task_ctx);
         perf_pmu_disable(cpuctx->ctx.pmu);
 
         cpu_ctx_sched_out(cpuctx, EVENT_ALL);
         /*
          * must not be done before ctxswout due
          * to update_cgrp_time_from_cpuctx() in
          * ctx_sched_out()
          */
         cpuctx->cgrp = cgrp;
         /*
          * set cgrp before ctxsw in to allow
          * perf_cgroup_set_timestamp() in ctx_sched_in()
          * to not have to pass task around
          */
         cpu_ctx_sched_in(cpuctx, EVENT_ALL);
 
         perf_pmu_enable(cpuctx->ctx.pmu);
         perf_ctx_unlock(cpuctx, cpuctx->task_ctx);
     }
 
     local_irq_restore(flags);
 }
 
 static int perf_cgroup_ensure_storage(struct perf_event *event,
                 struct cgroup_subsys_state *css)
 {
     struct perf_cpu_context *cpuctx;
     struct perf_event **storage;
     int cpu, heap_size, ret = 0;
 
     /*
      * Allow storage to have sufficent space for an iterator for each
      * possibly nested cgroup plus an iterator for events with no cgroup.
      */
     for (heap_size = 1; css; css = css->parent)
         heap_size++;
 
     for_each_possible_cpu(cpu) {
         cpuctx = per_cpu_ptr(event->pmu->pmu_cpu_context, cpu);
         if (heap_size <= cpuctx->heap_size)
             continue;
 
         storage = kmalloc_node(heap_size * sizeof(struct perf_event *),
                        GFP_KERNEL, cpu_to_node(cpu));
         if (!storage) {
             ret = -ENOMEM;
             break;
         }
 
         raw_spin_lock_irq(&cpuctx->ctx.lock);
         if (cpuctx->heap_size < heap_size) {
             swap(cpuctx->heap, storage);
             if (storage == cpuctx->heap_default)
                 storage = NULL;
             cpuctx->heap_size = heap_size;
         }
         raw_spin_unlock_irq(&cpuctx->ctx.lock);
 
         kfree(storage);
     }
 
     return ret;
 }
 
 static inline int perf_cgroup_connect(int fd, struct perf_event *event,
                       struct perf_event_attr *attr,
                       struct perf_event *group_leader)
 {
     struct perf_cgroup *cgrp;
     struct cgroup_subsys_state *css;
     struct fd f = fdget(fd);
     int ret = 0;
 
     if (!f.file)
         return -EBADF;
 
     css = css_tryget_online_from_dir(f.file->f_path.dentry,
                      &perf_event_cgrp_subsys);
     if (IS_ERR(css)) {
         ret = PTR_ERR(css);
         goto out;
     }
 
     ret = perf_cgroup_ensure_storage(event, css);
     if (ret)
         goto out;
 
     cgrp = container_of(css, struct perf_cgroup, css);
     event->cgrp = cgrp;
 
     /*
      * all events in a group must monitor
      * the same cgroup because a task belongs
      * to only one perf cgroup at a time
      */
     if (group_leader && group_leader->cgrp != cgrp) {
         perf_detach_cgroup(event);
         ret = -EINVAL;
     }
 out:
     fdput(f);
     return ret;
 }
 
 static inline void
 perf_cgroup_event_enable(struct perf_event *event, struct perf_event_context *ctx)
 {
     struct perf_cpu_context *cpuctx;
 
     if (!is_cgroup_event(event))
         return;
 
     /*
      * Because cgroup events are always per-cpu events,
      * @ctx == &cpuctx->ctx.
      */
     cpuctx = container_of(ctx, struct perf_cpu_context, ctx);
 
     if (ctx->nr_cgroups++)
         return;
 
     cpuctx->cgrp = perf_cgroup_from_task(current, ctx);
     list_add(&cpuctx->cgrp_cpuctx_entry,
             per_cpu_ptr(&cgrp_cpuctx_list, event->cpu));
 }
 
 static inline void
 perf_cgroup_event_disable(struct perf_event *event, struct perf_event_context *ctx)
 {
     struct perf_cpu_context *cpuctx;
 
     if (!is_cgroup_event(event))
         return;
 
     /*
      * Because cgroup events are always per-cpu events,
      * @ctx == &cpuctx->ctx.
      */
     cpuctx = container_of(ctx, struct perf_cpu_context, ctx);
 
     if (--ctx->nr_cgroups)
         return;
 
     cpuctx->cgrp = NULL;
     list_del(&cpuctx->cgrp_cpuctx_entry);
 }
 
 #else /* !CONFIG_CGROUP_PERF */
 
 static inline bool
 perf_cgroup_match(struct perf_event *event)
 {
     return true;
 }
 
 static inline void perf_detach_cgroup(struct perf_event *event)
 {}
 
 static inline int is_cgroup_event(struct perf_event *event)
 {
     return 0;
 }
 
 static inline void update_cgrp_time_from_event(struct perf_event *event)
 {
 }
 
 static inline void update_cgrp_time_from_cpuctx(struct perf_cpu_context *cpuctx,
                         bool final)
 {
 }
 
 static inline int perf_cgroup_connect(pid_t pid, struct perf_event *event,
                       struct perf_event_attr *attr,
                       struct perf_event *group_leader)
 {
     return -EINVAL;
 }
 
 static inline void
 perf_cgroup_set_timestamp(struct perf_cpu_context *cpuctx)
 {
 }
 
 static inline u64 perf_cgroup_event_time(struct perf_event *event)
 {
     return 0;
 }
 
 static inline u64 perf_cgroup_event_time_now(struct perf_event *event, u64 now)
 {
     return 0;
 }
 
 static inline void
 perf_cgroup_event_enable(struct perf_event *event, struct perf_event_context *ctx)
 {
 }
 
 static inline void
 perf_cgroup_event_disable(struct perf_event *event, struct perf_event_context *ctx)
 {
 }
 
 static void perf_cgroup_switch(struct task_struct *task)
 {
 }
 #endif
 
 /*
  * set default to be dependent on timer tick just
  * like original code
  */
 #define PERF_CPU_HRTIMER (1000 / HZ)
 /*
  * function must be called with interrupts disabled
  */
 static enum hrtimer_restart perf_mux_hrtimer_handler(struct hrtimer *hr)
 {
     struct perf_cpu_context *cpuctx;
     bool rotations;
 
     lockdep_assert_irqs_disabled();
 
     cpuctx = container_of(hr, struct perf_cpu_context, hrtimer);
     rotations = perf_rotate_context(cpuctx);
 
     raw_spin_lock(&cpuctx->hrtimer_lock);
     if (rotations)
         hrtimer_forward_now(hr, cpuctx->hrtimer_interval);
     else
         cpuctx->hrtimer_active = 0;
     raw_spin_unlock(&cpuctx->hrtimer_lock);
 
     return rotations ? HRTIMER_RESTART : HRTIMER_NORESTART;
 }
 
 static void __perf_mux_hrtimer_init(struct perf_cpu_context *cpuctx, int cpu)
 {
     struct hrtimer *timer = &cpuctx->hrtimer;
     struct pmu *pmu = cpuctx->ctx.pmu;
     u64 interval;
 
     /* no multiplexing needed for SW PMU */
     if (pmu->task_ctx_nr == perf_sw_context)
         return;
 
     /*
      * check default is sane, if not set then force to
      * default interval (1/tick)
      */
     interval = pmu->hrtimer_interval_ms;
     if (interval < 1)
         interval = pmu->hrtimer_interval_ms = PERF_CPU_HRTIMER;
 
     cpuctx->hrtimer_interval = ns_to_ktime(NSEC_PER_MSEC * interval);
 
     raw_spin_lock_init(&cpuctx->hrtimer_lock);
     hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED_HARD);
     timer->function = perf_mux_hrtimer_handler;
 }
 
 static int perf_mux_hrtimer_restart(struct perf_cpu_context *cpuctx)
 {
     struct hrtimer *timer = &cpuctx->hrtimer;
     struct pmu *pmu = cpuctx->ctx.pmu;
     unsigned long flags;
 
     /* not for SW PMU */
     if (pmu->task_ctx_nr == perf_sw_context)
         return 0;
 
     raw_spin_lock_irqsave(&cpuctx->hrtimer_lock, flags);
     if (!cpuctx->hrtimer_active) {
         cpuctx->hrtimer_active = 1;
         hrtimer_forward_now(timer, cpuctx->hrtimer_interval);
         hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED_HARD);
     }
     raw_spin_unlock_irqrestore(&cpuctx->hrtimer_lock, flags);
 
     return 0;
 }
 
 void perf_pmu_disable(struct pmu *pmu)
 {
     int *count = this_cpu_ptr(pmu->pmu_disable_count);
     if (!(*count)++)
         pmu->pmu_disable(pmu);
 }
 
 void perf_pmu_enable(struct pmu *pmu)
 {
     int *count = this_cpu_ptr(pmu->pmu_disable_count);
     if (!--(*count))
         pmu->pmu_enable(pmu);
 }
 
 static DEFINE_PER_CPU(struct list_head, active_ctx_list);
 
 /*
  * perf_event_ctx_activate(), perf_event_ctx_deactivate(), and
  * perf_event_task_tick() are fully serialized because they're strictly cpu
  * affine and perf_event_ctx{activate,deactivate} are called with IRQs
  * disabled, while perf_event_task_tick is called from IRQ context.
  */
 static void perf_event_ctx_activate(struct perf_event_context *ctx)
 {
     struct list_head *head = this_cpu_ptr(&active_ctx_list);
 
     lockdep_assert_irqs_disabled();
 
     WARN_ON(!list_empty(&ctx->active_ctx_list));
 
     list_add(&ctx->active_ctx_list, head);
 }
 
 static void perf_event_ctx_deactivate(struct perf_event_context *ctx)
 {
     lockdep_assert_irqs_disabled();
 
     WARN_ON(list_empty(&ctx->active_ctx_list));
 
     list_del_init(&ctx->active_ctx_list);
 }
 
 static void get_ctx(struct perf_event_context *ctx)
 {
     refcount_inc(&ctx->refcount);
 }
 
 static void *alloc_task_ctx_data(struct pmu *pmu)
 {
     if (pmu->task_ctx_cache)
         return kmem_cache_zalloc(pmu->task_ctx_cache, GFP_KERNEL);
 
     return NULL;
 }
 
 static void free_task_ctx_data(struct pmu *pmu, void *task_ctx_data)
 {
     if (pmu->task_ctx_cache && task_ctx_data)
         kmem_cache_free(pmu->task_ctx_cache, task_ctx_data);
 }
 
 static void free_ctx(struct rcu_head *head)
 {
     struct perf_event_context *ctx;
 
     ctx = container_of(head, struct perf_event_context, rcu_head);
     free_task_ctx_data(ctx->pmu, ctx->task_ctx_data);
     kfree(ctx);
 }
 
 static void put_ctx(struct perf_event_context *ctx)
 {
     if (refcount_dec_and_test(&ctx->refcount)) {
         if (ctx->parent_ctx)
             put_ctx(ctx->parent_ctx);
         if (ctx->task && ctx->task != TASK_TOMBSTONE)
             put_task_struct(ctx->task);
         call_rcu(&ctx->rcu_head, free_ctx);
     }
 }
 
 /*
  * Because of perf_event::ctx migration in sys_perf_event_open::move_group and
  * perf_pmu_migrate_context() we need some magic.
  *
  * Those places that change perf_event::ctx will hold both
  * perf_event_ctx::mutex of the 'old' and 'new' ctx value.
  *
  * Lock ordering is by mutex address. There are two other sites where
  * perf_event_context::mutex nests and those are:
  *
  *  - perf_event_exit_task_context()    [ child , 0 ]
  *      perf_event_exit_event()
  *        put_event()           [ parent, 1 ]
  *
  *  - perf_event_init_context()     [ parent, 0 ]
  *      inherit_task_group()
  *        inherit_group()
  *          inherit_event()
  *            perf_event_alloc()
  *              perf_init_event()
  *                perf_try_init_event() [ child , 1 ]
  *
  * While it appears there is an obvious deadlock here -- the parent and child
  * nesting levels are inverted between the two. This is in fact safe because
  * life-time rules separate them. That is an exiting task cannot fork, and a
  * spawning task cannot (yet) exit.
  *
  * But remember that these are parent<->child context relations, and
  * migration does not affect children, therefore these two orderings should not
  * interact.
  *
  * The change in perf_event::ctx does not affect children (as claimed above)
  * because the sys_perf_event_open() case will install a new event and break
  * the ctx parent<->child relation, and perf_pmu_migrate_context() is only
  * concerned with cpuctx and that doesn't have children.
  *
  * The places that change perf_event::ctx will issue:
  *
  *   perf_remove_from_context();
  *   synchronize_rcu();
  *   perf_install_in_context();
  *
  * to affect the change. The remove_from_context() + synchronize_rcu() should
  * quiesce the event, after which we can install it in the new location. This
  * means that only external vectors (perf_fops, prctl) can perturb the event
  * while in transit. Therefore all such accessors should also acquire
  * perf_event_context::mutex to serialize against this.
  *
  * However; because event->ctx can change while we're waiting to acquire
  * ctx->mutex we must be careful and use the below perf_event_ctx_lock()
  * function.
  *
  * Lock order:
  *    exec_update_lock
  *  task_struct::perf_event_mutex
  *    perf_event_context::mutex
  *      perf_event::child_mutex;
  *        perf_event_context::lock
  *      perf_event::mmap_mutex
  *      mmap_lock
  *        perf_addr_filters_head::lock
  *
  *    cpu_hotplug_lock
  *      pmus_lock
  *    cpuctx->mutex / perf_event_context::mutex
  */
 static struct perf_event_context *
 perf_event_ctx_lock_nested(struct perf_event *event, int nesting)
 {
     struct perf_event_context *ctx;
 
 again:
     rcu_read_lock();
     ctx = READ_ONCE(event->ctx);
     if (!refcount_inc_not_zero(&ctx->refcount)) {
         rcu_read_unlock();
         goto again;
     }
     rcu_read_unlock();
 
     mutex_lock_nested(&ctx->mutex, nesting);
     if (event->ctx != ctx) {
         mutex_unlock(&ctx->mutex);
         put_ctx(ctx);
         goto again;
     }
 
     return ctx;
 }
 
 static inline struct perf_event_context *
 perf_event_ctx_lock(struct perf_event *event)
 {
     return perf_event_ctx_lock_nested(event, 0);
 }
 
 static void perf_event_ctx_unlock(struct perf_event *event,
                   struct perf_event_context *ctx)
 {
     mutex_unlock(&ctx->mutex);
     put_ctx(ctx);
 }
 
 /*
  * This must be done under the ctx->lock, such as to serialize against
  * context_equiv(), therefore we cannot call put_ctx() since that might end up
  * calling scheduler related locks and ctx->lock nests inside those.
  */
 static __must_check struct perf_event_context *
 unclone_ctx(struct perf_event_context *ctx)
 {
     struct perf_event_context *parent_ctx = ctx->parent_ctx;
 
     lockdep_assert_held(&ctx->lock);
 
     if (parent_ctx)
         ctx->parent_ctx = NULL;
     ctx->generation++;
 
     return parent_ctx;
 }
 
 static u32 perf_event_pid_type(struct perf_event *event, struct task_struct *p,
                 enum pid_type type)
 {
     u32 nr;
     /*
      * only top level events have the pid namespace they were created in
      */
     if (event->parent)
         event = event->parent;
 
     nr = __task_pid_nr_ns(p, type, event->ns);
     /* avoid -1 if it is idle thread or runs in another ns */
     if (!nr && !pid_alive(p))
         nr = -1;
     return nr;
 }
 
 static u32 perf_event_pid(struct perf_event *event, struct task_struct *p)
 {
     return perf_event_pid_type(event, p, PIDTYPE_TGID);
 }
 
 static u32 perf_event_tid(struct perf_event *event, struct task_struct *p)
 {
     return perf_event_pid_type(event, p, PIDTYPE_PID);
 }
 
 /*
  * If we inherit events we want to return the parent event id
  * to userspace.
  */
 static u64 primary_event_id(struct perf_event *event)
 {
     u64 id = event->id;
 
     if (event->parent)
         id = event->parent->id;
 
     return id;
 }
 
 /*
  * Get the perf_event_context for a task and lock it.
  *
  * This has to cope with the fact that until it is locked,
  * the context could get moved to another task.
  */
 static struct perf_event_context *
 perf_lock_task_context(struct task_struct *task, int ctxn, unsigned long *flags)
 {
     struct perf_event_context *ctx;
 
 retry:
     /*
      * One of the few rules of preemptible RCU is that one cannot do
      * rcu_read_unlock() while holding a scheduler (or nested) lock when
      * part of the read side critical section was irqs-enabled -- see
      * rcu_read_unlock_special().
      *
      * Since ctx->lock nests under rq->lock we must ensure the entire read
      * side critical section has interrupts disabled.
      */
     local_irq_save(*flags);
     rcu_read_lock();
     ctx = rcu_dereference(task->perf_event_ctxp[ctxn]);
     if (ctx) {
         /*
          * If this context is a clone of another, it might
          * get swapped for another underneath us by
          * perf_event_task_sched_out, though the
          * rcu_read_lock() protects us from any context
          * getting freed.  Lock the context and check if it
          * got swapped before we could get the lock, and retry
          * if so.  If we locked the right context, then it
          * can't get swapped on us any more.
          */
         raw_spin_lock(&ctx->lock);
         if (ctx != rcu_dereference(task->perf_event_ctxp[ctxn])) {
             raw_spin_unlock(&ctx->lock);
             rcu_read_unlock();
             local_irq_restore(*flags);
             goto retry;
         }
 
         if (ctx->task == TASK_TOMBSTONE ||
             !refcount_inc_not_zero(&ctx->refcount)) {
             raw_spin_unlock(&ctx->lock);
             ctx = NULL;
         } else {
             WARN_ON_ONCE(ctx->task != task);
         }
     }
     rcu_read_unlock();
     if (!ctx)
         local_irq_restore(*flags);
     return ctx;
 }
 
 /*
  * Get the context for a task and increment its pin_count so it
  * can't get swapped to another task.  This also increments its
  * reference count so that the context can't get freed.
  */
 static struct perf_event_context *
 perf_pin_task_context(struct task_struct *task, int ctxn)
 {
     struct perf_event_context *ctx;
     unsigned long flags;
 
     ctx = perf_lock_task_context(task, ctxn, &flags);
     if (ctx) {
         ++ctx->pin_count;
         raw_spin_unlock_irqrestore(&ctx->lock, flags);
     }
     return ctx;
 }
 
 static void perf_unpin_context(struct perf_event_context *ctx)
 {
     unsigned long flags;
 
     raw_spin_lock_irqsave(&ctx->lock, flags);
     --ctx->pin_count;
     raw_spin_unlock_irqrestore(&ctx->lock, flags);
 }
 
 /*
  * Update the record of the current time in a context.
  */
 static void __update_context_time(struct perf_event_context *ctx, bool adv)
 {
     u64 now = perf_clock();
 
     if (adv)
         ctx->time += now - ctx->timestamp;
     ctx->timestamp = now;
 
     /*
      * The above: time' = time + (now - timestamp), can be re-arranged
      * into: time` = now + (time - timestamp), which gives a single value
      * offset to compute future time without locks on.
      *
      * See perf_event_time_now(), which can be used from NMI context where
      * it's (obviously) not possible to acquire ctx->lock in order to read
      * both the above values in a consistent manner.
      */
     WRITE_ONCE(ctx->timeoffset, ctx->time - ctx->timestamp);
 }
 
 static void update_context_time(struct perf_event_context *ctx)
 {
     __update_context_time(ctx, true);
 }
 
 static u64 perf_event_time(struct perf_event *event)
 {
     struct perf_event_context *ctx = event->ctx;
 
     if (unlikely(!ctx))
         return 0;
 
     if (is_cgroup_event(event))
         return perf_cgroup_event_time(event);
 
     return ctx->time;
 }
 
 static u64 perf_event_time_now(struct perf_event *event, u64 now)
 {
     struct perf_event_context *ctx = event->ctx;
 
     if (unlikely(!ctx))
         return 0;
 
     if (is_cgroup_event(event))
         return perf_cgroup_event_time_now(event, now);
 
     if (!(__load_acquire(&ctx->is_active) & EVENT_TIME))
         return ctx->time;
 
     now += READ_ONCE(ctx->timeoffset);
     return now;
 }
 
 static enum event_type_t get_event_type(struct perf_event *event)
 {
     struct perf_event_context *ctx = event->ctx;
     enum event_type_t event_type;
 
     lockdep_assert_held(&ctx->lock);
 
     /*
      * It's 'group type', really, because if our group leader is
      * pinned, so are we.
      */
     if (event->group_leader != event)
         event = event->group_leader;
 
     event_type = event->attr.pinned ? EVENT_PINNED : EVENT_FLEXIBLE;
     if (!ctx->task)
         event_type |= EVENT_CPU;
 
     return event_type;
 }
 
 /*
  * Helper function to initialize event group nodes.
  */
 static void init_event_group(struct perf_event *event)
 {
     RB_CLEAR_NODE(&event->group_node);
     event->group_index = 0;
 }
 
 /*
  * Extract pinned or flexible groups from the context
  * based on event attrs bits.
  */
 static struct perf_event_groups *
 get_event_groups(struct perf_event *event, struct perf_event_context *ctx)
 {
     if (event->attr.pinned)
         return &ctx->pinned_groups;
     else
         return &ctx->flexible_groups;
 }
 
 /*
  * Helper function to initializes perf_event_group trees.
  */
 static void perf_event_groups_init(struct perf_event_groups *groups)
 {
     groups->tree = RB_ROOT;
     groups->index = 0;
 }
 
 static inline struct cgroup *event_cgroup(const struct perf_event *event)
 {
     struct cgroup *cgroup = NULL;
 
 #ifdef CONFIG_CGROUP_PERF
     if (event->cgrp)
         cgroup = event->cgrp->css.cgroup;
 #endif
 
     return cgroup;
 }
 
 /*
  * Compare function for event groups;
  *
  * Implements complex key that first sorts by CPU and then by virtual index
  * which provides ordering when rotating groups for the same CPU.
  */
 static __always_inline int
 perf_event_groups_cmp(const int left_cpu, const struct cgroup *left_cgroup,
               const u64 left_group_index, const struct perf_event *right)
 {
     if (left_cpu < right->cpu)
         return -1;
     if (left_cpu > right->cpu)
         return 1;
 
 #ifdef CONFIG_CGROUP_PERF
     {
         const struct cgroup *right_cgroup = event_cgroup(right);
 
         if (left_cgroup != right_cgroup) {
             if (!left_cgroup) {
                 /*
                  * Left has no cgroup but right does, no
                  * cgroups come first.
                  */
                 return -1;
             }
             if (!right_cgroup) {
                 /*
                  * Right has no cgroup but left does, no
                  * cgroups come first.
                  */
                 return 1;
             }
             /* Two dissimilar cgroups, order by id. */
             if (cgroup_id(left_cgroup) < cgroup_id(right_cgroup))
                 return -1;
 
             return 1;
         }
     }
 #endif
 
     if (left_group_index < right->group_index)
         return -1;
     if (left_group_index > right->group_index)
         return 1;
 
     return 0;
 }
 
 #define __node_2_pe(node) \
     rb_entry((node), struct perf_event, group_node)
 
 static inline bool __group_less(struct rb_node *a, const struct rb_node *b)
 {
     struct perf_event *e = __node_2_pe(a);
     return perf_event_groups_cmp(e->cpu, event_cgroup(e), e->group_index,
                      __node_2_pe(b)) < 0;
 }
 
 struct __group_key {
     int cpu;
     struct cgroup *cgroup;
 };
 
 static inline int __group_cmp(const void *key, const struct rb_node *node)
 {
     const struct __group_key *a = key;
     const struct perf_event *b = __node_2_pe(node);
 
     /* partial/subtree match: @cpu, @cgroup; ignore: @group_index */
     return perf_event_groups_cmp(a->cpu, a->cgroup, b->group_index, b);
 }
 
 /*
  * Insert @event into @groups' tree; using {@event->cpu, ++@groups->index} for
  * key (see perf_event_groups_less). This places it last inside the CPU
  * subtree.
  */
 static void
 perf_event_groups_insert(struct perf_event_groups *groups,
              struct perf_event *event)
 {
     event->group_index = ++groups->index;
 
     rb_add(&event->group_node, &groups->tree, __group_less);
 }
 
 /*
  * Helper function to insert event into the pinned or flexible groups.
  */
 static void
 add_event_to_groups(struct perf_event *event, struct perf_event_context *ctx)
 {
     struct perf_event_groups *groups;
 
     groups = get_event_groups(event, ctx);
     perf_event_groups_insert(groups, event);
 }
 
 /*
  * Delete a group from a tree.
  */
 static void
 perf_event_groups_delete(struct perf_event_groups *groups,
              struct perf_event *event)
 {
     WARN_ON_ONCE(RB_EMPTY_NODE(&event->group_node) ||
              RB_EMPTY_ROOT(&groups->tree));
 
     rb_erase(&event->group_node, &groups->tree);
     init_event_group(event);
 }
 
 /*
  * Helper function to delete event from its groups.
  */
 static void
 del_event_from_groups(struct perf_event *event, struct perf_event_context *ctx)
 {
     struct perf_event_groups *groups;
 
     groups = get_event_groups(event, ctx);
     perf_event_groups_delete(groups, event);
 }
 
 /*
  * Get the leftmost event in the cpu/cgroup subtree.
  */
 static struct perf_event *
 perf_event_groups_first(struct perf_event_groups *groups, int cpu,
             struct cgroup *cgrp)
 {
     struct __group_key key = {
         .cpu = cpu,
         .cgroup = cgrp,
     };
     struct rb_node *node;
 
     node = rb_find_first(&key, &groups->tree, __group_cmp);
     if (node)
         return __node_2_pe(node);
 
     return NULL;
 }
 
 /*
  * Like rb_entry_next_safe() for the @cpu subtree.
  */
 static struct perf_event *
 perf_event_groups_next(struct perf_event *event)
 {
     struct __group_key key = {
         .cpu = event->cpu,
         .cgroup = event_cgroup(event),
     };
     struct rb_node *next;
 
     next = rb_next_match(&key, &event->group_node, __group_cmp);
     if (next)
         return __node_2_pe(next);
 
     return NULL;
 }
 
 /*
  * Iterate through the whole groups tree.
  */
 #define perf_event_groups_for_each(event, groups)           \
     for (event = rb_entry_safe(rb_first(&((groups)->tree)),     \
                 typeof(*event), group_node); event; \
         event = rb_entry_safe(rb_next(&event->group_node),  \
                 typeof(*event), group_node))
 
 /*
  * Add an event from the lists for its context.
  * Must be called with ctx->mutex and ctx->lock held.
  */
 static void
 list_add_event(struct perf_event *event, struct perf_event_context *ctx)
 {
     lockdep_assert_held(&ctx->lock);
 
     WARN_ON_ONCE(event->attach_state & PERF_ATTACH_CONTEXT);
     event->attach_state |= PERF_ATTACH_CONTEXT;
 
     event->tstamp = perf_event_time(event);
 
     /*
      * If we're a stand alone event or group leader, we go to the context
      * list, group events are kept attached to the group so that
      * perf_group_detach can, at all times, locate all siblings.
      */
     if (event->group_leader == event) {
         event->group_caps = event->event_caps;
         add_event_to_groups(event, ctx);
     }
 
     list_add_rcu(&event->event_entry, &ctx->event_list);
     ctx->nr_events++;
     if (event->hw.flags & PERF_EVENT_FLAG_USER_READ_CNT)
         ctx->nr_user++;
     if (event->attr.inherit_stat)
         ctx->nr_stat++;
 
     if (event->state > PERF_EVENT_STATE_OFF)
         perf_cgroup_event_enable(event, ctx);
 
     ctx->generation++;
 }
 
 /*
  * Initialize event state based on the perf_event_attr::disabled.
  */
 static inline void perf_event__state_init(struct perf_event *event)
 {
     event->state = event->attr.disabled ? PERF_EVENT_STATE_OFF :
                           PERF_EVENT_STATE_INACTIVE;
 }
 
 static void __perf_event_read_size(struct perf_event *event, int nr_siblings)
 {
     int entry = sizeof(u64); /* value */
     int size = 0;
     int nr = 1;
 
     if (event->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
         size += sizeof(u64);
 
     if (event->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
         size += sizeof(u64);
 
     if (event->attr.read_format & PERF_FORMAT_ID)
         entry += sizeof(u64);
 
     if (event->attr.read_format & PERF_FORMAT_LOST)
         entry += sizeof(u64);
 
     if (event->attr.read_format & PERF_FORMAT_GROUP) {
         nr += nr_siblings;
         size += sizeof(u64);
     }
 
     size += entry * nr;
     event->read_size = size;
 }
 
 static void __perf_event_header_size(struct perf_event *event, u64 sample_type)
 {
     struct perf_sample_data *data;
     u16 size = 0;
 
     if (sample_type & PERF_SAMPLE_IP)
         size += sizeof(data->ip);
 
     if (sample_type & PERF_SAMPLE_ADDR)
         size += sizeof(data->addr);
 
     if (sample_type & PERF_SAMPLE_PERIOD)
         size += sizeof(data->period);
 
     if (sample_type & PERF_SAMPLE_WEIGHT_TYPE)
         size += sizeof(data->weight.full);
 
     if (sample_type & PERF_SAMPLE_READ)
         size += event->read_size;
 
     if (sample_type & PERF_SAMPLE_DATA_SRC)
         size += sizeof(data->data_src.val);
 
     if (sample_type & PERF_SAMPLE_TRANSACTION)
         size += sizeof(data->txn);
 
     if (sample_type & PERF_SAMPLE_PHYS_ADDR)
         size += sizeof(data->phys_addr);
 
     if (sample_type & PERF_SAMPLE_CGROUP)
         size += sizeof(data->cgroup);
 
     if (sample_type & PERF_SAMPLE_DATA_PAGE_SIZE)
         size += sizeof(data->data_page_size);
 
     if (sample_type & PERF_SAMPLE_CODE_PAGE_SIZE)
         size += sizeof(data->code_page_size);
 
     event->header_size = size;
 }
 
 /*
  * Called at perf_event creation and when events are attached/detached from a
  * group.
  */
 static void perf_event__header_size(struct perf_event *event)
 {
     __perf_event_read_size(event,
                    event->group_leader->nr_siblings);
     __perf_event_header_size(event, event->attr.sample_type);
 }
 
 static void perf_event__id_header_size(struct perf_event *event)
 {
     struct perf_sample_data *data;
     u64 sample_type = event->attr.sample_type;
     u16 size = 0;
 
     if (sample_type & PERF_SAMPLE_TID)
         size += sizeof(data->tid_entry);
 
     if (sample_type & PERF_SAMPLE_TIME)
         size += sizeof(data->time);
 
     if (sample_type & PERF_SAMPLE_IDENTIFIER)
         size += sizeof(data->id);
 
     if (sample_type & PERF_SAMPLE_ID)
         size += sizeof(data->id);
 
     if (sample_type & PERF_SAMPLE_STREAM_ID)
         size += sizeof(data->stream_id);
 
     if (sample_type & PERF_SAMPLE_CPU)
         size += sizeof(data->cpu_entry);
 
     event->id_header_size = size;
 }
 
 static bool perf_event_validate_size(struct perf_event *event)
 {
     /*
      * The values computed here will be over-written when we actually
      * attach the event.
      */
     __perf_event_read_size(event, event->group_leader->nr_siblings + 1);
     __perf_event_header_size(event, event->attr.sample_type & ~PERF_SAMPLE_READ);
     perf_event__id_header_size(event);
 
     /*
      * Sum the lot; should not exceed the 64k limit we have on records.
      * Conservative limit to allow for callchains and other variable fields.
      */
     if (event->read_size + event->header_size +
         event->id_header_size + sizeof(struct perf_event_header) >= 16*1024)
         return false;
 
     return true;
 }
 
 static void perf_group_attach(struct perf_event *event)
 {
     struct perf_event *group_leader = event->group_leader, *pos;
 
     lockdep_assert_held(&event->ctx->lock);
 
     /*
      * We can have double attach due to group movement in perf_event_open.
      */
     if (event->attach_state & PERF_ATTACH_GROUP)
         return;
 
     event->attach_state |= PERF_ATTACH_GROUP;
 
     if (group_leader == event)
         return;
 
     WARN_ON_ONCE(group_leader->ctx != event->ctx);
 
     group_leader->group_caps &= event->event_caps;
 
     list_add_tail(&event->sibling_list, &group_leader->sibling_list);
     group_leader->nr_siblings++;
 
     perf_event__header_size(group_leader);
 
     for_each_sibling_event(pos, group_leader)
         perf_event__header_size(pos);
 }
 
 /*
  * Remove an event from the lists for its context.
  * Must be called with ctx->mutex and ctx->lock held.
  */
 static void
 list_del_event(struct perf_event *event, struct perf_event_context *ctx)
 {
     WARN_ON_ONCE(event->ctx != ctx);
     lockdep_assert_held(&ctx->lock);
 
     /*
      * We can have double detach due to exit/hot-unplug + close.
      */
     if (!(event->attach_state & PERF_ATTACH_CONTEXT))
         return;
 
     event->attach_state &= ~PERF_ATTACH_CONTEXT;
 
     ctx->nr_events--;
     if (event->hw.flags & PERF_EVENT_FLAG_USER_READ_CNT)
         ctx->nr_user--;
     if (event->attr.inherit_stat)
         ctx->nr_stat--;
 
     list_del_rcu(&event->event_entry);
 
     if (event->group_leader == event)
         del_event_from_groups(event, ctx);
 
     /*
      * If event was in error state, then keep it
      * that way, otherwise bogus counts will be
      * returned on read(). The only way to get out
      * of error state is by explicit re-enabling
      * of the event
      */
     if (event->state > PERF_EVENT_STATE_OFF) {
         perf_cgroup_event_disable(event, ctx);
         perf_event_set_state(event, PERF_EVENT_STATE_OFF);
     }
 
     ctx->generation++;
 }
 
 static int
 perf_aux_output_match(struct perf_event *event, struct perf_event *aux_event)
 {
     if (!has_aux(aux_event))
         return 0;
 
     if (!event->pmu->aux_output_match)
         return 0;
 
     return event->pmu->aux_output_match(aux_event);
 }
 
 static void put_event(struct perf_event *event);
 static void event_sched_out(struct perf_event *event,
                 struct perf_cpu_context *cpuctx,
                 struct perf_event_context *ctx);
 
 static void perf_put_aux_event(struct perf_event *event)
 {
     struct perf_event_context *ctx = event->ctx;
     struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
     struct perf_event *iter;
 
     /*
      * If event uses aux_event tear down the link
      */
     if (event->aux_event) {
         iter = event->aux_event;
         event->aux_event = NULL;
         put_event(iter);
         return;
     }
 
     /*
      * If the event is an aux_event, tear down all links to
      * it from other events.
      */
     for_each_sibling_event(iter, event->group_leader) {
         if (iter->aux_event != event)
             continue;
 
         iter->aux_event = NULL;
         put_event(event);
 
         /*
          * If it's ACTIVE, schedule it out and put it into ERROR
          * state so that we don't try to schedule it again. Note
          * that perf_event_enable() will clear the ERROR status.
          */
         event_sched_out(iter, cpuctx, ctx);
         perf_event_set_state(event, PERF_EVENT_STATE_ERROR);
     }
 }
 
 static bool perf_need_aux_event(struct perf_event *event)
 {
     return !!event->attr.aux_output || !!event->attr.aux_sample_size;
 }
 
 static int perf_get_aux_event(struct perf_event *event,
                   struct perf_event *group_leader)
 {
     /*
      * Our group leader must be an aux event if we want to be
      * an aux_output. This way, the aux event will precede its
      * aux_output events in the group, and therefore will always
      * schedule first.
      */
     if (!group_leader)
         return 0;
 
     /*
      * aux_output and aux_sample_size are mutually exclusive.
      */
     if (event->attr.aux_output && event->attr.aux_sample_size)
         return 0;
 
     if (event->attr.aux_output &&
         !perf_aux_output_match(event, group_leader))
         return 0;
 
     if (event->attr.aux_sample_size && !group_leader->pmu->snapshot_aux)
         return 0;
 
     if (!atomic_long_inc_not_zero(&group_leader->refcount))
         return 0;
 
     /*
      * Link aux_outputs to their aux event; this is undone in
      * perf_group_detach() by perf_put_aux_event(). When the
      * group in torn down, the aux_output events loose their
      * link to the aux_event and can't schedule any more.
      */
     event->aux_event = group_leader;
 
     return 1;
 }
 
 static inline struct list_head *get_event_list(struct perf_event *event)
 {
     struct perf_event_context *ctx = event->ctx;
     return event->attr.pinned ? &ctx->pinned_active : &ctx->flexible_active;
 }
 
 /*
  * Events that have PERF_EV_CAP_SIBLING require being part of a group and
  * cannot exist on their own, schedule them out and move them into the ERROR
  * state. Also see _perf_event_enable(), it will not be able to recover
  * this ERROR state.
  */
 static inline void perf_remove_sibling_event(struct perf_event *event)
 {
     struct perf_event_context *ctx = event->ctx;
     struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
 
     event_sched_out(event, cpuctx, ctx);
     perf_event_set_state(event, PERF_EVENT_STATE_ERROR);
 }
 
 static void perf_group_detach(struct perf_event *event)
 {
     struct perf_event *leader = event->group_leader;
     struct perf_event *sibling, *tmp;
     struct perf_event_context *ctx = event->ctx;
 
     lockdep_assert_held(&ctx->lock);
 
     /*
      * We can have double detach due to exit/hot-unplug + close.
      */
     if (!(event->attach_state & PERF_ATTACH_GROUP))
         return;
 
     event->attach_state &= ~PERF_ATTACH_GROUP;
 
     perf_put_aux_event(event);
 
     /*
      * If this is a sibling, remove it from its group.
      */
     if (leader != event) {
         list_del_init(&event->sibling_list);
         event->group_leader->nr_siblings--;
         goto out;
     }
 
     /*
      * If this was a group event with sibling events then
      * upgrade the siblings to singleton events by adding them
      * to whatever list we are on.
      */
     list_for_each_entry_safe(sibling, tmp, &event->sibling_list, sibling_list) {
 
         if (sibling->event_caps & PERF_EV_CAP_SIBLING)
             perf_remove_sibling_event(sibling);
 
         sibling->group_leader = sibling;
         list_del_init(&sibling->sibling_list);
 
         /* Inherit group flags from the previous leader */
         sibling->group_caps = event->group_caps;
 
         if (!RB_EMPTY_NODE(&event->group_node)) {
             add_event_to_groups(sibling, event->ctx);
 
             if (sibling->state == PERF_EVENT_STATE_ACTIVE)
                 list_add_tail(&sibling->active_list, get_event_list(sibling));
         }
 
         WARN_ON_ONCE(sibling->ctx != event->ctx);
     }
 
 out:
     for_each_sibling_event(tmp, leader)
         perf_event__header_size(tmp);
 
     perf_event__header_size(leader);
 }
 
 static void sync_child_event(struct perf_event *child_event);
 
 static void perf_child_detach(struct perf_event *event)
 {
     struct perf_event *parent_event = event->parent;
 
     if (!(event->attach_state & PERF_ATTACH_CHILD))
         return;
 
     event->attach_state &= ~PERF_ATTACH_CHILD;
 
     if (WARN_ON_ONCE(!parent_event))
         return;
 
     lockdep_assert_held(&parent_event->child_mutex);
 
     sync_child_event(event);
     list_del_init(&event->child_list);
 }
 
 static bool is_orphaned_event(struct perf_event *event)
 {
     return event->state == PERF_EVENT_STATE_DEAD;
 }
 
 static inline int __pmu_filter_match(struct perf_event *event)
 {
     struct pmu *pmu = event->pmu;
     return pmu->filter_match ? pmu->filter_match(event) : 1;
 }
 
 /*
  * Check whether we should attempt to schedule an event group based on
  * PMU-specific filtering. An event group can consist of HW and SW events,
  * potentially with a SW leader, so we must check all the filters, to
  * determine whether a group is schedulable:
  */
 static inline int pmu_filter_match(struct perf_event *event)
 {
     struct perf_event *sibling;
 
     if (!__pmu_filter_match(event))
         return 0;
 
     for_each_sibling_event(sibling, event) {
         if (!__pmu_filter_match(sibling))
             return 0;
     }
 
     return 1;
 }
 
 static inline int
 event_filter_match(struct perf_event *event)
 {
     return (event->cpu == -1 || event->cpu == smp_processor_id()) &&
            perf_cgroup_match(event) && pmu_filter_match(event);
 }
 
 static void
 event_sched_out(struct perf_event *event,
           struct perf_cpu_context *cpuctx,
           struct perf_event_context *ctx)
 {
     enum perf_event_state state = PERF_EVENT_STATE_INACTIVE;
 
     WARN_ON_ONCE(event->ctx != ctx);
     lockdep_assert_held(&ctx->lock);
 
     if (event->state != PERF_EVENT_STATE_ACTIVE)
         return;
 
     /*
      * Asymmetry; we only schedule events _IN_ through ctx_sched_in(), but
      * we can schedule events _OUT_ individually through things like
      * __perf_remove_from_context().
      */
     list_del_init(&event->active_list);
 
     perf_pmu_disable(event->pmu);
 
     event->pmu->del(event, 0);
     event->oncpu = -1;
 
     if (READ_ONCE(event->pending_disable) >= 0) {
         WRITE_ONCE(event->pending_disable, -1);
         perf_cgroup_event_disable(event, ctx);
         state = PERF_EVENT_STATE_OFF;
     }
     perf_event_set_state(event, state);
 
     if (!is_software_event(event))
         cpuctx->active_oncpu--;
     if (!--ctx->nr_active)
         perf_event_ctx_deactivate(ctx);
     if (event->attr.freq && event->attr.sample_freq)
         ctx->nr_freq--;
     if (event->attr.exclusive || !cpuctx->active_oncpu)
         cpuctx->exclusive = 0;
 
     perf_pmu_enable(event->pmu);
 }
 
 static void
 group_sched_out(struct perf_event *group_event,
         struct perf_cpu_context *cpuctx,
         struct perf_event_context *ctx)
 {
     struct perf_event *event;
 
     if (group_event->state != PERF_EVENT_STATE_ACTIVE)
         return;
 
     perf_pmu_disable(ctx->pmu);
 
     event_sched_out(group_event, cpuctx, ctx);
 
     /*
      * Schedule out siblings (if any):
      */
     for_each_sibling_event(event, group_event)
         event_sched_out(event, cpuctx, ctx);
 
     perf_pmu_enable(ctx->pmu);
 }
 
 #define DETACH_GROUP    0x01UL
 #define DETACH_CHILD    0x02UL
 
 /*
  * Cross CPU call to remove a performance event
  *
  * We disable the event on the hardware level first. After that we
  * remove it from the context list.
  */
 static void
 __perf_remove_from_context(struct perf_event *event,
                struct perf_cpu_context *cpuctx,
                struct perf_event_context *ctx,
                void *info)
 {
     unsigned long flags = (unsigned long)info;
 
     if (ctx->is_active & EVENT_TIME) {
         update_context_time(ctx);
         update_cgrp_time_from_cpuctx(cpuctx, false);
     }
 
     event_sched_out(event, cpuctx, ctx);
     if (flags & DETACH_GROUP)
         perf_group_detach(event);
     if (flags & DETACH_CHILD)
         perf_child_detach(event);
     list_del_event(event, ctx);
 
     if (!ctx->nr_events && ctx->is_active) {
         if (ctx == &cpuctx->ctx)
             update_cgrp_time_from_cpuctx(cpuctx, true);
 
         ctx->is_active = 0;
         ctx->rotate_necessary = 0;
         if (ctx->task) {
             WARN_ON_ONCE(cpuctx->task_ctx != ctx);
             cpuctx->task_ctx = NULL;
         }
     }
 }
 
 /*
  * Remove the event from a task's (or a CPU's) list of events.
  *
  * If event->ctx is a cloned context, callers must make sure that
  * every task struct that event->ctx->task could possibly point to
  * remains valid.  This is OK when called from perf_release since
  * that only calls us on the top-level context, which can't be a clone.
  * When called from perf_event_exit_task, it's OK because the
  * context has been detached from its task.
  */
 static void perf_remove_from_context(struct perf_event *event, unsigned long flags)
 {
     struct perf_event_context *ctx = event->ctx;
 
     lockdep_assert_held(&ctx->mutex);
 
     /*
      * Because of perf_event_exit_task(), perf_remove_from_context() ought
      * to work in the face of TASK_TOMBSTONE, unlike every other
      * event_function_call() user.
      */
     raw_spin_lock_irq(&ctx->lock);
     /*
      * Cgroup events are per-cpu events, and must IPI because of
      * cgrp_cpuctx_list.
      */
     if (!ctx->is_active && !is_cgroup_event(event)) {
         __perf_remove_from_context(event, __get_cpu_context(ctx),
                        ctx, (void *)flags);
         raw_spin_unlock_irq(&ctx->lock);
         return;
     }
     raw_spin_unlock_irq(&ctx->lock);
 
     event_function_call(event, __perf_remove_from_context, (void *)flags);
 }
 
 /*
  * Cross CPU call to disable a performance event
  */
 static void __perf_event_disable(struct perf_event *event,
                  struct perf_cpu_context *cpuctx,
                  struct perf_event_context *ctx,
                  void *info)
 {
     if (event->state < PERF_EVENT_STATE_INACTIVE)
         return;
 
     if (ctx->is_active & EVENT_TIME) {
         update_context_time(ctx);
         update_cgrp_time_from_event(event);
     }
 
     if (event == event->group_leader)
         group_sched_out(event, cpuctx, ctx);
     else
         event_sched_out(event, cpuctx, ctx);
 
     perf_event_set_state(event, PERF_EVENT_STATE_OFF);
     perf_cgroup_event_disable(event, ctx);
 }
 
 /*
  * Disable an event.
  *
  * If event->ctx is a cloned context, callers must make sure that
  * every task struct that event->ctx->task could possibly point to
  * remains valid.  This condition is satisfied when called through
  * perf_event_for_each_child or perf_event_for_each because they
  * hold the top-level event's child_mutex, so any descendant that
  * goes to exit will block in perf_event_exit_event().
  *
  * When called from perf_pending_event it's OK because event->ctx
  * is the current context on this CPU and preemption is disabled,
  * hence we can't get into perf_event_task_sched_out for this context.
  */
 static void _perf_event_disable(struct perf_event *event)
 {
     struct perf_event_context *ctx = event->ctx;
 
     raw_spin_lock_irq(&ctx->lock);
     if (event->state <= PERF_EVENT_STATE_OFF) {
         raw_spin_unlock_irq(&ctx->lock);
         return;
     }
     raw_spin_unlock_irq(&ctx->lock);
 
     event_function_call(event, __perf_event_disable, NULL);
 }
 
 void perf_event_disable_local(struct perf_event *event)
 {
     event_function_local(event, __perf_event_disable, NULL);
 }
 
 /*
  * Strictly speaking kernel users cannot create groups and therefore this
  * interface does not need the perf_event_ctx_lock() magic.
  */
 void perf_event_disable(struct perf_event *event)
 {
     struct perf_event_context *ctx;
 
     ctx = perf_event_ctx_lock(event);
     _perf_event_disable(event);
     perf_event_ctx_unlock(event, ctx);
 }
 EXPORT_SYMBOL_GPL(perf_event_disable);
 
 void perf_event_disable_inatomic(struct perf_event *event)
 {
     WRITE_ONCE(event->pending_disable, smp_processor_id());
     /* can fail, see perf_pending_event_disable() */
     irq_work_queue(&event->pending);
 }
 
 #define MAX_INTERRUPTS (~0ULL)
 
 static void perf_log_throttle(struct perf_event *event, int enable);
 static void perf_log_itrace_start(struct perf_event *event);
 
 static int
 event_sched_in(struct perf_event *event,
          struct perf_cpu_context *cpuctx,
          struct perf_event_context *ctx)
 {
     int ret = 0;
 
     WARN_ON_ONCE(event->ctx != ctx);
 
     lockdep_assert_held(&ctx->lock);
 
     if (event->state <= PERF_EVENT_STATE_OFF)
         return 0;
 
     WRITE_ONCE(event->oncpu, smp_processor_id());
     /*
      * Order event::oncpu write to happen before the ACTIVE state is
      * visible. This allows perf_event_{stop,read}() to observe the correct
      * ->oncpu if it sees ACTIVE.
      */
     smp_wmb();
     perf_event_set_state(event, PERF_EVENT_STATE_ACTIVE);
 
     /*
      * Unthrottle events, since we scheduled we might have missed several
      * ticks already, also for a heavily scheduling task there is little
      * guarantee it'll get a tick in a timely manner.
      */
     if (unlikely(event->hw.interrupts == MAX_INTERRUPTS)) {
         perf_log_throttle(event, 1);
         event->hw.interrupts = 0;
     }
 
     perf_pmu_disable(event->pmu);
 
     perf_log_itrace_start(event);
 
     if (event->pmu->add(event, PERF_EF_START)) {
         perf_event_set_state(event, PERF_EVENT_STATE_INACTIVE);
         event->oncpu = -1;
         ret = -EAGAIN;
         goto out;
     }
 
     if (!is_software_event(event))
         cpuctx->active_oncpu++;
     if (!ctx->nr_active++)
         perf_event_ctx_activate(ctx);
     if (event->attr.freq && event->attr.sample_freq)
         ctx->nr_freq++;
 
     if (event->attr.exclusive)
         cpuctx->exclusive = 1;
 
 out:
     perf_pmu_enable(event->pmu);
 
     return ret;
 }
 
 static int
 group_sched_in(struct perf_event *group_event,
            struct perf_cpu_context *cpuctx,
            struct perf_event_context *ctx)
 {
     struct perf_event *event, *partial_group = NULL;
     struct pmu *pmu = ctx->pmu;
 
     if (group_event->state == PERF_EVENT_STATE_OFF)
         return 0;
 
     pmu->start_txn(pmu, PERF_PMU_TXN_ADD);
 
     if (event_sched_in(group_event, cpuctx, ctx))
         goto error;
 
     /*
      * Schedule in siblings as one group (if any):
      */
     for_each_sibling_event(event, group_event) {
         if (event_sched_in(event, cpuctx, ctx)) {
             partial_group = event;
             goto group_error;
         }
     }
 
     if (!pmu->commit_txn(pmu))
         return 0;
 
 group_error:
     /*
      * Groups can be scheduled in as one unit only, so undo any
      * partial group before returning:
      * The events up to the failed event are scheduled out normally.
      */
     for_each_sibling_event(event, group_event) {
         if (event == partial_group)
             break;
 
         event_sched_out(event, cpuctx, ctx);
     }
     event_sched_out(group_event, cpuctx, ctx);
 
 error:
     pmu->cancel_txn(pmu);
     return -EAGAIN;
 }
 
 /*
  * Work out whether we can put this event group on the CPU now.
  */
 static int group_can_go_on(struct perf_event *event,
                struct perf_cpu_context *cpuctx,
                int can_add_hw)
 {
     /*
      * Groups consisting entirely of software events can always go on.
      */
     if (event->group_caps & PERF_EV_CAP_SOFTWARE)
         return 1;
     /*
      * If an exclusive group is already on, no other hardware
      * events can go on.
      */
     if (cpuctx->exclusive)
         return 0;
     /*
      * If this group is exclusive and there are already
      * events on the CPU, it can't go on.
      */
     if (event->attr.exclusive && !list_empty(get_event_list(event)))
         return 0;
     /*
      * Otherwise, try to add it if all previous groups were able
      * to go on.
      */
     return can_add_hw;
 }
 
 static void add_event_to_ctx(struct perf_event *event,
                    struct perf_event_context *ctx)
 {
     list_add_event(event, ctx);
     perf_group_attach(event);
 }
 
 static void ctx_sched_out(struct perf_event_context *ctx,
               struct perf_cpu_context *cpuctx,
               enum event_type_t event_type);
 static void
 ctx_sched_in(struct perf_event_context *ctx,
          struct perf_cpu_context *cpuctx,
          enum event_type_t event_type);
 
 static void task_ctx_sched_out(struct perf_cpu_context *cpuctx,
                    struct perf_event_context *ctx,
                    enum event_type_t event_type)
 {
     if (!cpuctx->task_ctx)
         return;
 
     if (WARN_ON_ONCE(ctx != cpuctx->task_ctx))
         return;
 
     ctx_sched_out(ctx, cpuctx, event_type);
 }
 
 static void perf_event_sched_in(struct perf_cpu_context *cpuctx,
                 struct perf_event_context *ctx)
 {
     cpu_ctx_sched_in(cpuctx, EVENT_PINNED);
     if (ctx)
         ctx_sched_in(ctx, cpuctx, EVENT_PINNED);
     cpu_ctx_sched_in(cpuctx, EVENT_FLEXIBLE);
     if (ctx)
         ctx_sched_in(ctx, cpuctx, EVENT_FLEXIBLE);
 }
 
 /*
  * We want to maintain the following priority of scheduling:
  *  - CPU pinned (EVENT_CPU | EVENT_PINNED)
  *  - task pinned (EVENT_PINNED)
  *  - CPU flexible (EVENT_CPU | EVENT_FLEXIBLE)
  *  - task flexible (EVENT_FLEXIBLE).
  *
  * In order to avoid unscheduling and scheduling back in everything every
  * time an event is added, only do it for the groups of equal priority and
  * below.
  *
  * This can be called after a batch operation on task events, in which case
  * event_type is a bit mask of the types of events involved. For CPU events,
  * event_type is only either EVENT_PINNED or EVENT_FLEXIBLE.
  */
 static void ctx_resched(struct perf_cpu_context *cpuctx,
             struct perf_event_context *task_ctx,
             enum event_type_t event_type)
 {
     enum event_type_t ctx_event_type;
     bool cpu_event = !!(event_type & EVENT_CPU);
 
     /*
      * If pinned groups are involved, flexible groups also need to be
      * scheduled out.
      */
     if (event_type & EVENT_PINNED)
         event_type |= EVENT_FLEXIBLE;
 
     ctx_event_type = event_type & EVENT_ALL;
 
     perf_pmu_disable(cpuctx->ctx.pmu);
     if (task_ctx)
         task_ctx_sched_out(cpuctx, task_ctx, event_type);
 
     /*
      * Decide which cpu ctx groups to schedule out based on the types
      * of events that caused rescheduling:
      *  - EVENT_CPU: schedule out corresponding groups;
      *  - EVENT_PINNED task events: schedule out EVENT_FLEXIBLE groups;
      *  - otherwise, do nothing more.
      */
     if (cpu_event)
         cpu_ctx_sched_out(cpuctx, ctx_event_type);
     else if (ctx_event_type & EVENT_PINNED)
         cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
 
     perf_event_sched_in(cpuctx, task_ctx);
     perf_pmu_enable(cpuctx->ctx.pmu);
 }
 
 void perf_pmu_resched(struct pmu *pmu)
 {
     struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
     struct perf_event_context *task_ctx = cpuctx->task_ctx;
 
     perf_ctx_lock(cpuctx, task_ctx);
     ctx_resched(cpuctx, task_ctx, EVENT_ALL|EVENT_CPU);
     perf_ctx_unlock(cpuctx, task_ctx);
 }
 
 /*
  * Cross CPU call to install and enable a performance event
  *
  * Very similar to remote_function() + event_function() but cannot assume that
  * things like ctx->is_active and cpuctx->task_ctx are set.
  */
 static int  __perf_install_in_context(void *info)
 {
     struct perf_event *event = info;
     struct perf_event_context *ctx = event->ctx;
     struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
     struct perf_event_context *task_ctx = cpuctx->task_ctx;
     bool reprogram = true;
     int ret = 0;
 
     raw_spin_lock(&cpuctx->ctx.lock);
     if (ctx->task) {
         raw_spin_lock(&ctx->lock);
         task_ctx = ctx;
 
         reprogram = (ctx->task == current);
 
         /*
          * If the task is running, it must be running on this CPU,
          * otherwise we cannot reprogram things.
          *
          * If its not running, we don't care, ctx->lock will
          * serialize against it becoming runnable.
          */
         if (task_curr(ctx->task) && !reprogram) {
             ret = -ESRCH;
             goto unlock;
         }
 
         WARN_ON_ONCE(reprogram && cpuctx->task_ctx && cpuctx->task_ctx != ctx);
     } else if (task_ctx) {
         raw_spin_lock(&task_ctx->lock);
     }
 
 #ifdef CONFIG_CGROUP_PERF
     if (event->state > PERF_EVENT_STATE_OFF && is_cgroup_event(event)) {
         /*
          * If the current cgroup doesn't match the event's
          * cgroup, we should not try to schedule it.
          */
         struct perf_cgroup *cgrp = perf_cgroup_from_task(current, ctx);
         reprogram = cgroup_is_descendant(cgrp->css.cgroup,
                     event->cgrp->css.cgroup);
     }
 #endif
 
     if (reprogram) {
         ctx_sched_out(ctx, cpuctx, EVENT_TIME);
         add_event_to_ctx(event, ctx);
         ctx_resched(cpuctx, task_ctx, get_event_type(event));
     } else {
         add_event_to_ctx(event, ctx);
     }
 
 unlock:
     perf_ctx_unlock(cpuctx, task_ctx);
 
     return ret;
 }
 
 static bool exclusive_event_installable(struct perf_event *event,
                     struct perf_event_context *ctx);
 
 /*
  * Attach a performance event to a context.
  *
  * Very similar to event_function_call, see comment there.
  */
 static void
 perf_install_in_context(struct perf_event_context *ctx,
             struct perf_event *event,
             int cpu)
 {
     struct task_struct *task = READ_ONCE(ctx->task);
 
     lockdep_assert_held(&ctx->mutex);
 
     WARN_ON_ONCE(!exclusive_event_installable(event, ctx));
 
     if (event->cpu != -1)
         event->cpu = cpu;
 
     /*
      * Ensures that if we can observe event->ctx, both the event and ctx
      * will be 'complete'. See perf_iterate_sb_cpu().
      */
     smp_store_release(&event->ctx, ctx);
 
     /*
      * perf_event_attr::disabled events will not run and can be initialized
      * without IPI. Except when this is the first event for the context, in
      * that case we need the magic of the IPI to set ctx->is_active.
      * Similarly, cgroup events for the context also needs the IPI to
      * manipulate the cgrp_cpuctx_list.
      *
      * The IOC_ENABLE that is sure to follow the creation of a disabled
      * event will issue the IPI and reprogram the hardware.
      */
     if (__perf_effective_state(event) == PERF_EVENT_STATE_OFF &&
         ctx->nr_events && !is_cgroup_event(event)) {
         raw_spin_lock_irq(&ctx->lock);
         if (ctx->task == TASK_TOMBSTONE) {
             raw_spin_unlock_irq(&ctx->lock);
             return;
         }
         add_event_to_ctx(event, ctx);
         raw_spin_unlock_irq(&ctx->lock);
         return;
     }
 
     if (!task) {
         cpu_function_call(cpu, __perf_install_in_context, event);
         return;
     }
 
     /*
      * Should not happen, we validate the ctx is still alive before calling.
      */
     if (WARN_ON_ONCE(task == TASK_TOMBSTONE))
         return;
 
     /*
      * Installing events is tricky because we cannot rely on ctx->is_active
      * to be set in case this is the nr_events 0 -> 1 transition.
      *
      * Instead we use task_curr(), which tells us if the task is running.
      * However, since we use task_curr() outside of rq::lock, we can race
      * against the actual state. This means the result can be wrong.
      *
      * If we get a false positive, we retry, this is harmless.
      *
      * If we get a false negative, things are complicated. If we are after
      * perf_event_context_sched_in() ctx::lock will serialize us, and the
      * value must be correct. If we're before, it doesn't matter since
      * perf_event_context_sched_in() will program the counter.
      *
      * However, this hinges on the remote context switch having observed
      * our task->perf_event_ctxp[] store, such that it will in fact take
      * ctx::lock in perf_event_context_sched_in().
      *
      * We do this by task_function_call(), if the IPI fails to hit the task
      * we know any future context switch of task must see the
      * perf_event_ctpx[] store.
      */
 
     /*
      * This smp_mb() orders the task->perf_event_ctxp[] store with the
      * task_cpu() load, such that if the IPI then does not find the task
      * running, a future context switch of that task must observe the
      * store.
      */
     smp_mb();
 again:
     if (!task_function_call(task, __perf_install_in_context, event))
         return;
 
     raw_spin_lock_irq(&ctx->lock);
     task = ctx->task;
     if (WARN_ON_ONCE(task == TASK_TOMBSTONE)) {
         /*
          * Cannot happen because we already checked above (which also
          * cannot happen), and we hold ctx->mutex, which serializes us
          * against perf_event_exit_task_context().
          */
         raw_spin_unlock_irq(&ctx->lock);
         return;
     }
     /*
      * If the task is not running, ctx->lock will avoid it becoming so,
      * thus we can safely install the event.
      */
     if (task_curr(task)) {
         raw_spin_unlock_irq(&ctx->lock);
         goto again;
     }
     add_event_to_ctx(event, ctx);
     raw_spin_unlock_irq(&ctx->lock);
 }
 
 /*
  * Cross CPU call to enable a performance event
  */
 static void __perf_event_enable(struct perf_event *event,
                 struct perf_cpu_context *cpuctx,
                 struct perf_event_context *ctx,
                 void *info)
 {
     struct perf_event *leader = event->group_leader;
     struct perf_event_context *task_ctx;
 
     if (event->state >= PERF_EVENT_STATE_INACTIVE ||
         event->state <= PERF_EVENT_STATE_ERROR)
         return;
 
     if (ctx->is_active)
         ctx_sched_out(ctx, cpuctx, EVENT_TIME);
 
     perf_event_set_state(event, PERF_EVENT_STATE_INACTIVE);
     perf_cgroup_event_enable(event, ctx);
 
     if (!ctx->is_active)
         return;
 
     if (!event_filter_match(event)) {
         ctx_sched_in(ctx, cpuctx, EVENT_TIME);
         return;
     }
 
     /*
      * If the event is in a group and isn't the group leader,
      * then don't put it on unless the group is on.
      */
     if (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE) {
         ctx_sched_in(ctx, cpuctx, EVENT_TIME);
         return;
     }
 
     task_ctx = cpuctx->task_ctx;
     if (ctx->task)
         WARN_ON_ONCE(task_ctx != ctx);
 
     ctx_resched(cpuctx, task_ctx, get_event_type(event));
 }
 
 /*
  * Enable an event.
  *
  * If event->ctx is a cloned context, callers must make sure that
  * every task struct that event->ctx->task could possibly point to
  * remains valid.  This condition is satisfied when called through
  * perf_event_for_each_child or perf_event_for_each as described
  * for perf_event_disable.
  */
 static void _perf_event_enable(struct perf_event *event)
 {
     struct perf_event_context *ctx = event->ctx;
 
     raw_spin_lock_irq(&ctx->lock);
     if (event->state >= PERF_EVENT_STATE_INACTIVE ||
         event->state <  PERF_EVENT_STATE_ERROR) {
 out:
         raw_spin_unlock_irq(&ctx->lock);
         return;
     }
 
     /*
      * If the event is in error state, clear that first.
      *
      * That way, if we see the event in error state below, we know that it
      * has gone back into error state, as distinct from the task having
      * been scheduled away before the cross-call arrived.
      */
     if (event->state == PERF_EVENT_STATE_ERROR) {
         /*
          * Detached SIBLING events cannot leave ERROR state.
          */
         if (event->event_caps & PERF_EV_CAP_SIBLING &&
             event->group_leader == event)
             goto out;
 
         event->state = PERF_EVENT_STATE_OFF;
     }
     raw_spin_unlock_irq(&ctx->lock);
 
     event_function_call(event, __perf_event_enable, NULL);
 }
 
 /*
  * See perf_event_disable();
  */
 void perf_event_enable(struct perf_event *event)
 {
     struct perf_event_context *ctx;
 
     ctx = perf_event_ctx_lock(event);
     _perf_event_enable(event);
     perf_event_ctx_unlock(event, ctx);
 }
 EXPORT_SYMBOL_GPL(perf_event_enable);
 
 struct stop_event_data {
     struct perf_event   *event;
     unsigned int        restart;
 };
 
 static int __perf_event_stop(void *info)
 {
     struct stop_event_data *sd = info;
     struct perf_event *event = sd->event;
 
     /* if it's already INACTIVE, do nothing */
     if (READ_ONCE(event->state) != PERF_EVENT_STATE_ACTIVE)
         return 0;
 
     /* matches smp_wmb() in event_sched_in() */
     smp_rmb();
 
     /*
      * There is a window with interrupts enabled before we get here,
      * so we need to check again lest we try to stop another CPU's event.
      */
     if (READ_ONCE(event->oncpu) != smp_processor_id())
         return -EAGAIN;
 
     event->pmu->stop(event, PERF_EF_UPDATE);
 
     /*
      * May race with the actual stop (through perf_pmu_output_stop()),
      * but it is only used for events with AUX ring buffer, and such
      * events will refuse to restart because of rb::aux_mmap_count==0,
      * see comments in perf_aux_output_begin().
      *
      * Since this is happening on an event-local CPU, no trace is lost
      * while restarting.
      */
     if (sd->restart)
         event->pmu->start(event, 0);
 
     return 0;
 }
 
 static int perf_event_stop(struct perf_event *event, int restart)
 {
     struct stop_event_data sd = {
         .event      = event,
         .restart    = restart,
     };
     int ret = 0;
 
     do {
         if (READ_ONCE(event->state) != PERF_EVENT_STATE_ACTIVE)
             return 0;
 
         /* matches smp_wmb() in event_sched_in() */
         smp_rmb();
 
         /*
          * We only want to restart ACTIVE events, so if the event goes
          * inactive here (event->oncpu==-1), there's nothing more to do;
          * fall through with ret==-ENXIO.
          */
         ret = cpu_function_call(READ_ONCE(event->oncpu),
                     __perf_event_stop, &sd);
     } while (ret == -EAGAIN);
 
     return ret;
 }
 
 /*
  * In order to contain the amount of racy and tricky in the address filter
  * configuration management, it is a two part process:
  *
  * (p1) when userspace mappings change as a result of (1) or (2) or (3) below,
  *      we update the addresses of corresponding vmas in
  *  event::addr_filter_ranges array and bump the event::addr_filters_gen;
  * (p2) when an event is scheduled in (pmu::add), it calls
  *      perf_event_addr_filters_sync() which calls pmu::addr_filters_sync()
  *      if the generation has changed since the previous call.
  *
  * If (p1) happens while the event is active, we restart it to force (p2).
  *
  * (1) perf_addr_filters_apply(): adjusting filters' offsets based on
  *     pre-existing mappings, called once when new filters arrive via SET_FILTER
  *     ioctl;
  * (2) perf_addr_filters_adjust(): adjusting filters' offsets based on newly
  *     registered mapping, called for every new mmap(), with mm::mmap_lock down
  *     for reading;
  * (3) perf_event_addr_filters_exec(): clearing filters' offsets in the process
  *     of exec.
  */
 void perf_event_addr_filters_sync(struct perf_event *event)
 {
     struct perf_addr_filters_head *ifh = perf_event_addr_filters(event);
 
     if (!has_addr_filter(event))
         return;
 
     raw_spin_lock(&ifh->lock);
     if (event->addr_filters_gen != event->hw.addr_filters_gen) {
         event->pmu->addr_filters_sync(event);
         event->hw.addr_filters_gen = event->addr_filters_gen;
     }
     raw_spin_unlock(&ifh->lock);
 }
 EXPORT_SYMBOL_GPL(perf_event_addr_filters_sync);
 
 static int _perf_event_refresh(struct perf_event *event, int refresh)
 {
     /*
      * not supported on inherited events
      */
     if (event->attr.inherit || !is_sampling_event(event))
         return -EINVAL;
 
     atomic_add(refresh, &event->event_limit);
     _perf_event_enable(event);
 
     return 0;
 }
 
 /*
  * See perf_event_disable()
  */
 int perf_event_refresh(struct perf_event *event, int refresh)
 {
     struct perf_event_context *ctx;
     int ret;
 
     ctx = perf_event_ctx_lock(event);
     ret = _perf_event_refresh(event, refresh);
     perf_event_ctx_unlock(event, ctx);
 
     return ret;
 }
 EXPORT_SYMBOL_GPL(perf_event_refresh);
 
 static int perf_event_modify_breakpoint(struct perf_event *bp,
                      struct perf_event_attr *attr)
 {
     int err;
 
     _perf_event_disable(bp);
 
     err = modify_user_hw_breakpoint_check(bp, attr, true);
 
     if (!bp->attr.disabled)
         _perf_event_enable(bp);
 
     return err;
 }
 
 /*
  * Copy event-type-independent attributes that may be modified.
  */
 static void perf_event_modify_copy_attr(struct perf_event_attr *to,
                     const struct perf_event_attr *from)
 {
     to->sig_data = from->sig_data;
 }
 
 static int perf_event_modify_attr(struct perf_event *event,
                   struct perf_event_attr *attr)
 {
     int (*func)(struct perf_event *, struct perf_event_attr *);
     struct perf_event *child;
     int err;
 
     if (event->attr.type != attr->type)
         return -EINVAL;
 
     switch (event->attr.type) {
     case PERF_TYPE_BREAKPOINT:
         func = perf_event_modify_breakpoint;
         break;
     default:
         /* Place holder for future additions. */
         return -EOPNOTSUPP;
     }
 
     WARN_ON_ONCE(event->ctx->parent_ctx);
 
     mutex_lock(&event->child_mutex);
     /*
      * Event-type-independent attributes must be copied before event-type
      * modification, which will validate that final attributes match the
      * source attributes after all relevant attributes have been copied.
      */
     perf_event_modify_copy_attr(&event->attr, attr);
     err = func(event, attr);
     if (err)
         goto out;
     list_for_each_entry(child, &event->child_list, child_list) {
         perf_event_modify_copy_attr(&child->attr, attr);
         err = func(child, attr);
         if (err)
             goto out;
     }
 out:
     mutex_unlock(&event->child_mutex);
     return err;
 }
 
 static void ctx_sched_out(struct perf_event_context *ctx,
               struct perf_cpu_context *cpuctx,
               enum event_type_t event_type)
 {
     struct perf_event *event, *tmp;
     int is_active = ctx->is_active;
 
     lockdep_assert_held(&ctx->lock);
 
     if (likely(!ctx->nr_events)) {
         /*
          * See __perf_remove_from_context().
          */
         WARN_ON_ONCE(ctx->is_active);
         if (ctx->task)
             WARN_ON_ONCE(cpuctx->task_ctx);
         return;
     }
 
     /*
      * Always update time if it was set; not only when it changes.
      * Otherwise we can 'forget' to update time for any but the last
      * context we sched out. For example:
      *
      *   ctx_sched_out(.event_type = EVENT_FLEXIBLE)
      *   ctx_sched_out(.event_type = EVENT_PINNED)
      *
      * would only update time for the pinned events.
      */
     if (is_active & EVENT_TIME) {
         /* update (and stop) ctx time */
         update_context_time(ctx);
         update_cgrp_time_from_cpuctx(cpuctx, ctx == &cpuctx->ctx);
         /*
          * CPU-release for the below ->is_active store,
          * see __load_acquire() in perf_event_time_now()
          */
         barrier();
     }
 
     ctx->is_active &= ~event_type;
     if (!(ctx->is_active & EVENT_ALL))
         ctx->is_active = 0;
 
     if (ctx->task) {
         WARN_ON_ONCE(cpuctx->task_ctx != ctx);
         if (!ctx->is_active)
             cpuctx->task_ctx = NULL;
     }
 
     is_active ^= ctx->is_active; /* changed bits */
 
     if (!ctx->nr_active || !(is_active & EVENT_ALL))
         return;
 
     perf_pmu_disable(ctx->pmu);
     if (is_active & EVENT_PINNED) {
         list_for_each_entry_safe(event, tmp, &ctx->pinned_active, active_list)
             group_sched_out(event, cpuctx, ctx);
     }
 
     if (is_active & EVENT_FLEXIBLE) {
         list_for_each_entry_safe(event, tmp, &ctx->flexible_active, active_list)
             group_sched_out(event, cpuctx, ctx);
 
         /*
          * Since we cleared EVENT_FLEXIBLE, also clear
          * rotate_necessary, is will be reset by
          * ctx_flexible_sched_in() when needed.
          */
         ctx->rotate_necessary = 0;
     }
     perf_pmu_enable(ctx->pmu);
 }
 
 /*
  * Test whether two contexts are equivalent, i.e. whether they have both been
  * cloned from the same version of the same context.
  *
  * Equivalence is measured using a generation number in the context that is
  * incremented on each modification to it; see unclone_ctx(), list_add_event()
  * and list_del_event().
  */
 static int context_equiv(struct perf_event_context *ctx1,
              struct perf_event_context *ctx2)
 {
     lockdep_assert_held(&ctx1->lock);
     lockdep_assert_held(&ctx2->lock);
 
     /* Pinning disables the swap optimization */
     if (ctx1->pin_count || ctx2->pin_count)
         return 0;
 
     /* If ctx1 is the parent of ctx2 */
     if (ctx1 == ctx2->parent_ctx && ctx1->generation == ctx2->parent_gen)
         return 1;
 
     /* If ctx2 is the parent of ctx1 */
     if (ctx1->parent_ctx == ctx2 && ctx1->parent_gen == ctx2->generation)
         return 1;
 
     /*
      * If ctx1 and ctx2 have the same parent; we flatten the parent
      * hierarchy, see perf_event_init_context().
      */
     if (ctx1->parent_ctx && ctx1->parent_ctx == ctx2->parent_ctx &&
             ctx1->parent_gen == ctx2->parent_gen)
         return 1;
 
     /* Unmatched */
     return 0;
 }
 
 static void __perf_event_sync_stat(struct perf_event *event,
                      struct perf_event *next_event)
 {
     u64 value;
 
     if (!event->attr.inherit_stat)
         return;
 
     /*
      * Update the event value, we cannot use perf_event_read()
      * because we're in the middle of a context switch and have IRQs
      * disabled, which upsets smp_call_function_single(), however
      * we know the event must be on the current CPU, therefore we
      * don't need to use it.
      */
     if (event->state == PERF_EVENT_STATE_ACTIVE)
         event->pmu->read(event);
 
     perf_event_update_time(event);
 
     /*
      * In order to keep per-task stats reliable we need to flip the event
      * values when we flip the contexts.
      */
     value = local64_read(&next_event->count);
     value = local64_xchg(&event->count, value);
     local64_set(&next_event->count, value);
 
     swap(event->total_time_enabled, next_event->total_time_enabled);
     swap(event->total_time_running, next_event->total_time_running);
 
     /*
      * Since we swizzled the values, update the user visible data too.
      */
     perf_event_update_userpage(event);
     perf_event_update_userpage(next_event);
 }
 
 static void perf_event_sync_stat(struct perf_event_context *ctx,
                    struct perf_event_context *next_ctx)
 {
     struct perf_event *event, *next_event;
 
     if (!ctx->nr_stat)
         return;
 
     update_context_time(ctx);
 
     event = list_first_entry(&ctx->event_list,
                    struct perf_event, event_entry);
 
     next_event = list_first_entry(&next_ctx->event_list,
                     struct perf_event, event_entry);
 
     while (&event->event_entry != &ctx->event_list &&
            &next_event->event_entry != &next_ctx->event_list) {
 
         __perf_event_sync_stat(event, next_event);
 
         event = list_next_entry(event, event_entry);
         next_event = list_next_entry(next_event, event_entry);
     }
 }
 
 static void perf_event_context_sched_out(struct task_struct *task, int ctxn,
                      struct task_struct *next)
 {
     struct perf_event_context *ctx = task->perf_event_ctxp[ctxn];
     struct perf_event_context *next_ctx;
     struct perf_event_context *parent, *next_parent;
     struct perf_cpu_context *cpuctx;
     int do_switch = 1;
     struct pmu *pmu;
 
     if (likely(!ctx))
         return;
 
     pmu = ctx->pmu;
     cpuctx = __get_cpu_context(ctx);
     if (!cpuctx->task_ctx)
         return;
 
     rcu_read_lock();
     next_ctx = next->perf_event_ctxp[ctxn];
     if (!next_ctx)
         goto unlock;
 
     parent = rcu_dereference(ctx->parent_ctx);
     next_parent = rcu_dereference(next_ctx->parent_ctx);
 
     /* If neither context have a parent context; they cannot be clones. */
     if (!parent && !next_parent)
         goto unlock;
 
     if (next_parent == ctx || next_ctx == parent || next_parent == parent) {
         /*
          * Looks like the two contexts are clones, so we might be
          * able to optimize the context switch.  We lock both
          * contexts and check that they are clones under the
          * lock (including re-checking that neither has been
          * uncloned in the meantime).  It doesn't matter which
          * order we take the locks because no other cpu could
          * be trying to lock both of these tasks.
          */
         raw_spin_lock(&ctx->lock);
         raw_spin_lock_nested(&next_ctx->lock, SINGLE_DEPTH_NESTING);
         if (context_equiv(ctx, next_ctx)) {
 
             WRITE_ONCE(ctx->task, next);
             WRITE_ONCE(next_ctx->task, task);
 
             perf_pmu_disable(pmu);
 
             if (cpuctx->sched_cb_usage && pmu->sched_task)
                 pmu->sched_task(ctx, false);
 
             /*
              * PMU specific parts of task perf context can require
              * additional synchronization. As an example of such
              * synchronization see implementation details of Intel
              * LBR call stack data profiling;
              */
             if (pmu->swap_task_ctx)
                 pmu->swap_task_ctx(ctx, next_ctx);
             else
                 swap(ctx->task_ctx_data, next_ctx->task_ctx_data);
 
             perf_pmu_enable(pmu);
 
             /*
              * RCU_INIT_POINTER here is safe because we've not
              * modified the ctx and the above modification of
              * ctx->task and ctx->task_ctx_data are immaterial
              * since those values are always verified under
              * ctx->lock which we're now holding.
              */
             RCU_INIT_POINTER(task->perf_event_ctxp[ctxn], next_ctx);
             RCU_INIT_POINTER(next->perf_event_ctxp[ctxn], ctx);
 
             do_switch = 0;
 
             perf_event_sync_stat(ctx, next_ctx);
         }
         raw_spin_unlock(&next_ctx->lock);
         raw_spin_unlock(&ctx->lock);
     }
 unlock:
     rcu_read_unlock();
 
     if (do_switch) {
         raw_spin_lock(&ctx->lock);
         perf_pmu_disable(pmu);
 
         if (cpuctx->sched_cb_usage && pmu->sched_task)
             pmu->sched_task(ctx, false);
         task_ctx_sched_out(cpuctx, ctx, EVENT_ALL);
 
         perf_pmu_enable(pmu);
         raw_spin_unlock(&ctx->lock);
     }
 }
 
 static DEFINE_PER_CPU(struct list_head, sched_cb_list);
 
 void perf_sched_cb_dec(struct pmu *pmu)
 {
     struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
 
     this_cpu_dec(perf_sched_cb_usages);
 
     if (!--cpuctx->sched_cb_usage)
         list_del(&cpuctx->sched_cb_entry);
 }
 
 
 void perf_sched_cb_inc(struct pmu *pmu)
 {
     struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
 
     if (!cpuctx->sched_cb_usage++)
         list_add(&cpuctx->sched_cb_entry, this_cpu_ptr(&sched_cb_list));
 
     this_cpu_inc(perf_sched_cb_usages);
 }
 
 /*
  * This function provides the context switch callback to the lower code
  * layer. It is invoked ONLY when the context switch callback is enabled.
  *
  * This callback is relevant even to per-cpu events; for example multi event
  * PEBS requires this to provide PID/TID information. This requires we flush
  * all queued PEBS records before we context switch to a new task.
  */
 static void __perf_pmu_sched_task(struct perf_cpu_context *cpuctx, bool sched_in)
 {
     struct pmu *pmu;
 
     pmu = cpuctx->ctx.pmu; /* software PMUs will not have sched_task */
 
     if (WARN_ON_ONCE(!pmu->sched_task))
         return;
 
     perf_ctx_lock(cpuctx, cpuctx->task_ctx);
     perf_pmu_disable(pmu);
 
     pmu->sched_task(cpuctx->task_ctx, sched_in);
 
     perf_pmu_enable(pmu);
     perf_ctx_unlock(cpuctx, cpuctx->task_ctx);
 }
 
 static void perf_pmu_sched_task(struct task_struct *prev,
                 struct task_struct *next,
                 bool sched_in)
 {
     struct perf_cpu_context *cpuctx;
 
     if (prev == next)
         return;
 
     list_for_each_entry(cpuctx, this_cpu_ptr(&sched_cb_list), sched_cb_entry) {
         /* will be handled in perf_event_context_sched_in/out */
         if (cpuctx->task_ctx)
             continue;
 
         __perf_pmu_sched_task(cpuctx, sched_in);
     }
 }
 
 static void perf_event_switch(struct task_struct *task,
                   struct task_struct *next_prev, bool sched_in);
 
 #define for_each_task_context_nr(ctxn)                  \
     for ((ctxn) = 0; (ctxn) < perf_nr_task_contexts; (ctxn)++)
 
 /*
  * Called from scheduler to remove the events of the current task,
  * with interrupts disabled.
  *
  * We stop each event and update the event value in event->count.
  *
  * This does not protect us against NMI, but disable()
  * sets the disabled bit in the control field of event _before_
  * accessing the event control register. If a NMI hits, then it will
  * not restart the event.
  */
 void __perf_event_task_sched_out(struct task_struct *task,
                  struct task_struct *next)
 {
     int ctxn;
 
     if (__this_cpu_read(perf_sched_cb_usages))
         perf_pmu_sched_task(task, next, false);
 
     if (atomic_read(&nr_switch_events))
         perf_event_switch(task, next, false);
 
     for_each_task_context_nr(ctxn)
         perf_event_context_sched_out(task, ctxn, next);
 
     /*
      * if cgroup events exist on this CPU, then we need
      * to check if we have to switch out PMU state.
      * cgroup event are system-wide mode only
      */
     if (atomic_read(this_cpu_ptr(&perf_cgroup_events)))
         perf_cgroup_switch(next);
 }
 
 /*
  * Called with IRQs disabled
  */
 static void cpu_ctx_sched_out(struct perf_cpu_context *cpuctx,
                   enum event_type_t event_type)
 {
     ctx_sched_out(&cpuctx->ctx, cpuctx, event_type);
 }
 
 static bool perf_less_group_idx(const void *l, const void *r)
 {
     const struct perf_event *le = *(const struct perf_event **)l;
     const struct perf_event *re = *(const struct perf_event **)r;
 
     return le->group_index < re->group_index;
 }
 
 static void swap_ptr(void *l, void *r)
 {
     void **lp = l, **rp = r;
 
     swap(*lp, *rp);
 }
 
 static const struct min_heap_callbacks perf_min_heap = {
     .elem_size = sizeof(struct perf_event *),
     .less = perf_less_group_idx,
     .swp = swap_ptr,
 };
 
 static void __heap_add(struct min_heap *heap, struct perf_event *event)
 {
     struct perf_event **itrs = heap->data;
 
     if (event) {
         itrs[heap->nr] = event;
         heap->nr++;
     }
 }
 
 static noinline int visit_groups_merge(struct perf_cpu_context *cpuctx,
                 struct perf_event_groups *groups, int cpu,
                 int (*func)(struct perf_event *, void *),
                 void *data)
 {
 #ifdef CONFIG_CGROUP_PERF
     struct cgroup_subsys_state *css = NULL;
 #endif
     /* Space for per CPU and/or any CPU event iterators. */
     struct perf_event *itrs[2];
     struct min_heap event_heap;
     struct perf_event **evt;
     int ret;
 
     if (cpuctx) {
         event_heap = (struct min_heap){
             .data = cpuctx->heap,
             .nr = 0,
             .size = cpuctx->heap_size,
         };
 
         lockdep_assert_held(&cpuctx->ctx.lock);
 
 #ifdef CONFIG_CGROUP_PERF
         if (cpuctx->cgrp)
             css = &cpuctx->cgrp->css;
 #endif
     } else {
         event_heap = (struct min_heap){
             .data = itrs,
             .nr = 0,
             .size = ARRAY_SIZE(itrs),
         };
         /* Events not within a CPU context may be on any CPU. */
         __heap_add(&event_heap, perf_event_groups_first(groups, -1, NULL));
     }
     evt = event_heap.data;
 
     __heap_add(&event_heap, perf_event_groups_first(groups, cpu, NULL));
 
 #ifdef CONFIG_CGROUP_PERF
     for (; css; css = css->parent)
         __heap_add(&event_heap, perf_event_groups_first(groups, cpu, css->cgroup));
 #endif
 
     min_heapify_all(&event_heap, &perf_min_heap);
 
     while (event_heap.nr) {
         ret = func(*evt, data);
         if (ret)
             return ret;
 
         *evt = perf_event_groups_next(*evt);
         if (*evt)
             min_heapify(&event_heap, 0, &perf_min_heap);
         else
             min_heap_pop(&event_heap, &perf_min_heap);
     }
 
     return 0;
 }
 
 /*
  * Because the userpage is strictly per-event (there is no concept of context,
  * so there cannot be a context indirection), every userpage must be updated
  * when context time starts :-(
  *
  * IOW, we must not miss EVENT_TIME edges.
  */
 static inline bool event_update_userpage(struct perf_event *event)
 {
     if (likely(!atomic_read(&event->mmap_count)))
         return false;
 
     perf_event_update_time(event);
     perf_event_update_userpage(event);
 
     return true;
 }
 
 static inline void group_update_userpage(struct perf_event *group_event)
 {
     struct perf_event *event;
 
     if (!event_update_userpage(group_event))
         return;
 
     for_each_sibling_event(event, group_event)
         event_update_userpage(event);
 }
 
 static int merge_sched_in(struct perf_event *event, void *data)
 {
     struct perf_event_context *ctx = event->ctx;
     struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
     int *can_add_hw = data;
 
     if (event->state <= PERF_EVENT_STATE_OFF)
         return 0;
 
     if (!event_filter_match(event))
         return 0;
 
     if (group_can_go_on(event, cpuctx, *can_add_hw)) {
         if (!group_sched_in(event, cpuctx, ctx))
             list_add_tail(&event->active_list, get_event_list(event));
     }
 
     if (event->state == PERF_EVENT_STATE_INACTIVE) {
         *can_add_hw = 0;
         if (event->attr.pinned) {
             perf_cgroup_event_disable(event, ctx);
             perf_event_set_state(event, PERF_EVENT_STATE_ERROR);
         } else {
             ctx->rotate_necessary = 1;
             perf_mux_hrtimer_restart(cpuctx);
             group_update_userpage(event);
         }
     }
 
     return 0;
 }
 
 static void
 ctx_pinned_sched_in(struct perf_event_context *ctx,
             struct perf_cpu_context *cpuctx)
 {
     int can_add_hw = 1;
 
     if (ctx != &cpuctx->ctx)
         cpuctx = NULL;
 
     visit_groups_merge(cpuctx, &ctx->pinned_groups,
                smp_processor_id(),
                merge_sched_in, &can_add_hw);
 }
 
 static void
 ctx_flexible_sched_in(struct perf_event_context *ctx,
               struct perf_cpu_context *cpuctx)
 {
     int can_add_hw = 1;
 
     if (ctx != &cpuctx->ctx)
         cpuctx = NULL;
 
     visit_groups_merge(cpuctx, &ctx->flexible_groups,
                smp_processor_id(),
                merge_sched_in, &can_add_hw);
 }
 
 static void
 ctx_sched_in(struct perf_event_context *ctx,
          struct perf_cpu_context *cpuctx,
          enum event_type_t event_type)
 {
     int is_active = ctx->is_active;
 
     lockdep_assert_held(&ctx->lock);
 
     if (likely(!ctx->nr_events))
         return;
 
     if (is_active ^ EVENT_TIME) {
         /* start ctx time */
         __update_context_time(ctx, false);
         perf_cgroup_set_timestamp(cpuctx);
         /*
          * CPU-release for the below ->is_active store,
          * see __load_acquire() in perf_event_time_now()
          */
         barrier();
     }
 
     ctx->is_active |= (event_type | EVENT_TIME);
     if (ctx->task) {
         if (!is_active)
             cpuctx->task_ctx = ctx;
         else
             WARN_ON_ONCE(cpuctx->task_ctx != ctx);
     }
 
     is_active ^= ctx->is_active; /* changed bits */
 
     /*
      * First go through the list and put on any pinned groups
      * in order to give them the best chance of going on.
      */
     if (is_active & EVENT_PINNED)
         ctx_pinned_sched_in(ctx, cpuctx);
 
     /* Then walk through the lower prio flexible groups */
     if (is_active & EVENT_FLEXIBLE)
         ctx_flexible_sched_in(ctx, cpuctx);
 }
 
 static void cpu_ctx_sched_in(struct perf_cpu_context *cpuctx,
                  enum event_type_t event_type)
 {
     struct perf_event_context *ctx = &cpuctx->ctx;
 
     ctx_sched_in(ctx, cpuctx, event_type);
 }
 
 static void perf_event_context_sched_in(struct perf_event_context *ctx,
                     struct task_struct *task)
 {
     struct perf_cpu_context *cpuctx;
     struct pmu *pmu;
 
     cpuctx = __get_cpu_context(ctx);
 
     /*
      * HACK: for HETEROGENEOUS the task context might have switched to a
      * different PMU, force (re)set the context,
      */
     pmu = ctx->pmu = cpuctx->ctx.pmu;
 
     if (cpuctx->task_ctx == ctx) {
         if (cpuctx->sched_cb_usage)
             __perf_pmu_sched_task(cpuctx, true);
         return;
     }
 
     perf_ctx_lock(cpuctx, ctx);
     /*
      * We must check ctx->nr_events while holding ctx->lock, such
      * that we serialize against perf_install_in_context().
      */
     if (!ctx->nr_events)
         goto unlock;
 
     perf_pmu_disable(pmu);
     /*
      * We want to keep the following priority order:
      * cpu pinned (that don't need to move), task pinned,
      * cpu flexible, task flexible.
      *
      * However, if task's ctx is not carrying any pinned
      * events, no need to flip the cpuctx's events around.
      */
     if (!RB_EMPTY_ROOT(&ctx->pinned_groups.tree))
         cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
     perf_event_sched_in(cpuctx, ctx);
 
     if (cpuctx->sched_cb_usage && pmu->sched_task)
         pmu->sched_task(cpuctx->task_ctx, true);
 
     perf_pmu_enable(pmu);
 
 unlock:
     perf_ctx_unlock(cpuctx, ctx);
 }
 
 /*
  * Called from scheduler to add the events of the current task
  * with interrupts disabled.
  *
  * We restore the event value and then enable it.
  *
  * This does not protect us against NMI, but enable()
  * sets the enabled bit in the control field of event _before_
  * accessing the event control register. If a NMI hits, then it will
  * keep the event running.
  */
 void __perf_event_task_sched_in(struct task_struct *prev,
                 struct task_struct *task)
 {
     struct perf_event_context *ctx;
     int ctxn;
 
     for_each_task_context_nr(ctxn) {
         ctx = task->perf_event_ctxp[ctxn];
         if (likely(!ctx))
             continue;
 
         perf_event_context_sched_in(ctx, task);
     }
 
     if (atomic_read(&nr_switch_events))
         perf_event_switch(task, prev, true);
 
     if (__this_cpu_read(perf_sched_cb_usages))
         perf_pmu_sched_task(prev, task, true);
 }
 
 static u64 perf_calculate_period(struct perf_event *event, u64 nsec, u64 count)
 {
     u64 frequency = event->attr.sample_freq;
     u64 sec = NSEC_PER_SEC;
     u64 divisor, dividend;
 
     int count_fls, nsec_fls, frequency_fls, sec_fls;
 
     count_fls = fls64(count);
     nsec_fls = fls64(nsec);
     frequency_fls = fls64(frequency);
     sec_fls = 30;
 
     /*
      * We got @count in @nsec, with a target of sample_freq HZ
      * the target period becomes:
      *
      *             @count * 10^9
      * period = -------------------
      *          @nsec * sample_freq
      *
      */
 
     /*
      * Reduce accuracy by one bit such that @a and @b converge
      * to a similar magnitude.
      */
 #define REDUCE_FLS(a, b)        \
 do {                    \
     if (a##_fls > b##_fls) {    \
         a >>= 1;        \
         a##_fls--;      \
     } else {            \
         b >>= 1;        \
         b##_fls--;      \
     }               \
 } while (0)
 
     /*
      * Reduce accuracy until either term fits in a u64, then proceed with
      * the other, so that finally we can do a u64/u64 division.
      */
     while (count_fls + sec_fls > 64 && nsec_fls + frequency_fls > 64) {
         REDUCE_FLS(nsec, frequency);
         REDUCE_FLS(sec, count);
     }
 
     if (count_fls + sec_fls > 64) {
         divisor = nsec * frequency;
 
         while (count_fls + sec_fls > 64) {
             REDUCE_FLS(count, sec);
             divisor >>= 1;
         }
 
         dividend = count * sec;
     } else {
         dividend = count * sec;
 
         while (nsec_fls + frequency_fls > 64) {
             REDUCE_FLS(nsec, frequency);
             dividend >>= 1;
         }
 
         divisor = nsec * frequency;
     }
 
     if (!divisor)
         return dividend;
 
     return div64_u64(dividend, divisor);
 }
 
 static DEFINE_PER_CPU(int, perf_throttled_count);
 static DEFINE_PER_CPU(u64, perf_throttled_seq);
 
 static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count, bool disable)
 {
     struct hw_perf_event *hwc = &event->hw;
     s64 period, sample_period;
     s64 delta;
 
     period = perf_calculate_period(event, nsec, count);
 
     delta = (s64)(period - hwc->sample_period);
     delta = (delta + 7) / 8; /* low pass filter */
 
     sample_period = hwc->sample_period + delta;
 
     if (!sample_period)
         sample_period = 1;
 
     hwc->sample_period = sample_period;
 
     if (local64_read(&hwc->period_left) > 8*sample_period) {
         if (disable)
             event->pmu->stop(event, PERF_EF_UPDATE);
 
         local64_set(&hwc->period_left, 0);
 
         if (disable)
             event->pmu->start(event, PERF_EF_RELOAD);
     }
 }
 
 /*
  * combine freq adjustment with unthrottling to avoid two passes over the
  * events. At the same time, make sure, having freq events does not change
  * the rate of unthrottling as that would introduce bias.
  */
 static void perf_adjust_freq_unthr_context(struct perf_event_context *ctx,
                        int needs_unthr)
 {
     struct perf_event *event;
     struct hw_perf_event *hwc;
     u64 now, period = TICK_NSEC;
     s64 delta;
 
     /*
      * only need to iterate over all events iff:
      * - context have events in frequency mode (needs freq adjust)
      * - there are events to unthrottle on this cpu
      */
     if (!(ctx->nr_freq || needs_unthr))
         return;
 
     raw_spin_lock(&ctx->lock);
     perf_pmu_disable(ctx->pmu);
 
     list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
         if (event->state != PERF_EVENT_STATE_ACTIVE)
             continue;
 
         if (!event_filter_match(event))
             continue;
 
         perf_pmu_disable(event->pmu);
 
         hwc = &event->hw;
 
         if (hwc->interrupts == MAX_INTERRUPTS) {
             hwc->interrupts = 0;
             perf_log_throttle(event, 1);
             event->pmu->start(event, 0);
         }
 
         if (!event->attr.freq || !event->attr.sample_freq)
             goto next;
 
         /*
          * stop the event and update event->count
          */
         event->pmu->stop(event, PERF_EF_UPDATE);
 
         now = local64_read(&event->count);
         delta = now - hwc->freq_count_stamp;
         hwc->freq_count_stamp = now;
 
         /*
          * restart the event
          * reload only if value has changed
          * we have stopped the event so tell that
          * to perf_adjust_period() to avoid stopping it
          * twice.
          */
         if (delta > 0)
             perf_adjust_period(event, period, delta, false);
 
         event->pmu->start(event, delta > 0 ? PERF_EF_RELOAD : 0);
     next:
         perf_pmu_enable(event->pmu);
     }
 
     perf_pmu_enable(ctx->pmu);
     raw_spin_unlock(&ctx->lock);
 }
 
 /*
  * Move @event to the tail of the @ctx's elegible events.
  */
 static void rotate_ctx(struct perf_event_context *ctx, struct perf_event *event)
 {
     /*
      * Rotate the first entry last of non-pinned groups. Rotation might be
      * disabled by the inheritance code.
      */
     if (ctx->rotate_disable)
         return;
 
     perf_event_groups_delete(&ctx->flexible_groups, event);
     perf_event_groups_insert(&ctx->flexible_groups, event);
 }
 
 /* pick an event from the flexible_groups to rotate */
 static inline struct perf_event *
 ctx_event_to_rotate(struct perf_event_context *ctx)
 {
     struct perf_event *event;
 
     /* pick the first active flexible event */
     event = list_first_entry_or_null(&ctx->flexible_active,
                      struct perf_event, active_list);
 
     /* if no active flexible event, pick the first event */
     if (!event) {
         event = rb_entry_safe(rb_first(&ctx->flexible_groups.tree),
                       typeof(*event), group_node);
     }
 
     /*
      * Unconditionally clear rotate_necessary; if ctx_flexible_sched_in()
      * finds there are unschedulable events, it will set it again.
      */
     ctx->rotate_necessary = 0;
 
     return event;
 }
 
 static bool perf_rotate_context(struct perf_cpu_context *cpuctx)
 {
     struct perf_event *cpu_event = NULL, *task_event = NULL;
     struct perf_event_context *task_ctx = NULL;
     int cpu_rotate, task_rotate;
 
     /*
      * Since we run this from IRQ context, nobody can install new
      * events, thus the event count values are stable.
      */
 
     cpu_rotate = cpuctx->ctx.rotate_necessary;
     task_ctx = cpuctx->task_ctx;
     task_rotate = task_ctx ? task_ctx->rotate_necessary : 0;
 
     if (!(cpu_rotate || task_rotate))
         return false;
 
     perf_ctx_lock(cpuctx, cpuctx->task_ctx);
     perf_pmu_disable(cpuctx->ctx.pmu);
 
     if (task_rotate)
         task_event = ctx_event_to_rotate(task_ctx);
     if (cpu_rotate)
         cpu_event = ctx_event_to_rotate(&cpuctx->ctx);
 
     /*
      * As per the order given at ctx_resched() first 'pop' task flexible
      * and then, if needed CPU flexible.
      */
     if (task_event || (task_ctx && cpu_event))
         ctx_sched_out(task_ctx, cpuctx, EVENT_FLEXIBLE);
     if (cpu_event)
         cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
 
     if (task_event)
         rotate_ctx(task_ctx, task_event);
     if (cpu_event)
         rotate_ctx(&cpuctx->ctx, cpu_event);
 
     perf_event_sched_in(cpuctx, task_ctx);
 
     perf_pmu_enable(cpuctx->ctx.pmu);
     perf_ctx_unlock(cpuctx, cpuctx->task_ctx);
 
     return true;
 }
 
 void perf_event_task_tick(void)
 {
     struct list_head *head = this_cpu_ptr(&active_ctx_list);
     struct perf_event_context *ctx, *tmp;
     int throttled;
 
     lockdep_assert_irqs_disabled();
 
     __this_cpu_inc(perf_throttled_seq);
     throttled = __this_cpu_xchg(perf_throttled_count, 0);
     tick_dep_clear_cpu(smp_processor_id(), TICK_DEP_BIT_PERF_EVENTS);
 
     list_for_each_entry_safe(ctx, tmp, head, active_ctx_list)
         perf_adjust_freq_unthr_context(ctx, throttled);
 }
 
 static int event_enable_on_exec(struct perf_event *event,
                 struct perf_event_context *ctx)
 {
     if (!event->attr.enable_on_exec)
         return 0;
 
     event->attr.enable_on_exec = 0;
     if (event->state >= PERF_EVENT_STATE_INACTIVE)
         return 0;
 
     perf_event_set_state(event, PERF_EVENT_STATE_INACTIVE);
 
     return 1;
 }
 
 /*
  * Enable all of a task's events that have been marked enable-on-exec.
  * This expects task == current.
  */
 static void perf_event_enable_on_exec(int ctxn)
 {
     struct perf_event_context *ctx, *clone_ctx = NULL;
     enum event_type_t event_type = 0;
     struct perf_cpu_context *cpuctx;
     struct perf_event *event;
     unsigned long flags;
     int enabled = 0;
 
     local_irq_save(flags);
     ctx = current->perf_event_ctxp[ctxn];
     if (!ctx || !ctx->nr_events)
         goto out;
 
     cpuctx = __get_cpu_context(ctx);
     perf_ctx_lock(cpuctx, ctx);
     ctx_sched_out(ctx, cpuctx, EVENT_TIME);
     list_for_each_entry(event, &ctx->event_list, event_entry) {
         enabled |= event_enable_on_exec(event, ctx);
         event_type |= get_event_type(event);
     }
 
     /*
      * Unclone and reschedule this context if we enabled any event.
      */
     if (enabled) {
         clone_ctx = unclone_ctx(ctx);
         ctx_resched(cpuctx, ctx, event_type);
     } else {
         ctx_sched_in(ctx, cpuctx, EVENT_TIME);
     }
     perf_ctx_unlock(cpuctx, ctx);
 
 out:
     local_irq_restore(flags);
 
     if (clone_ctx)
         put_ctx(clone_ctx);
 }
 
 static void perf_remove_from_owner(struct perf_event *event);
 static void perf_event_exit_event(struct perf_event *event,
                   struct perf_event_context *ctx);
 
 /*
  * Removes all events from the current task that have been marked
  * remove-on-exec, and feeds their values back to parent events.
  */
 static void perf_event_remove_on_exec(int ctxn)
 {
     struct perf_event_context *ctx, *clone_ctx = NULL;
     struct perf_event *event, *next;
     unsigned long flags;
     bool modified = false;
 
     ctx = perf_pin_task_context(current, ctxn);
     if (!ctx)
         return;
 
     mutex_lock(&ctx->mutex);
 
     if (WARN_ON_ONCE(ctx->task != current))
         goto unlock;
 
     list_for_each_entry_safe(event, next, &ctx->event_list, event_entry) {
         if (!event->attr.remove_on_exec)
             continue;
 
         if (!is_kernel_event(event))
             perf_remove_from_owner(event);
 
         modified = true;
 
         perf_event_exit_event(event, ctx);
     }
 
     raw_spin_lock_irqsave(&ctx->lock, flags);
     if (modified)
         clone_ctx = unclone_ctx(ctx);
     --ctx->pin_count;
     raw_spin_unlock_irqrestore(&ctx->lock, flags);
 
 unlock:
     mutex_unlock(&ctx->mutex);
 
     put_ctx(ctx);
     if (clone_ctx)
         put_ctx(clone_ctx);
 }
 
 struct perf_read_data {
     struct perf_event *event;
     bool group;
     int ret;
 };
 
 static int __perf_event_read_cpu(struct perf_event *event, int event_cpu)
 {
     u16 local_pkg, event_pkg;
 
     if (event->group_caps & PERF_EV_CAP_READ_ACTIVE_PKG) {
         int local_cpu = smp_processor_id();
 
         event_pkg = topology_physical_package_id(event_cpu);
         local_pkg = topology_physical_package_id(local_cpu);
 
         if (event_pkg == local_pkg)
             return local_cpu;
     }
 
     return event_cpu;
 }
 
 /*
  * Cross CPU call to read the hardware event
  */
 static void __perf_event_read(void *info)
 {
     struct perf_read_data *data = info;
     struct perf_event *sub, *event = data->event;
     struct perf_event_context *ctx = event->ctx;
     struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
     struct pmu *pmu = event->pmu;
 
     /*
      * If this is a task context, we need to check whether it is
      * the current task context of this cpu.  If not it has been
      * scheduled out before the smp call arrived.  In that case
      * event->count would have been updated to a recent sample
      * when the event was scheduled out.
      */
     if (ctx->task && cpuctx->task_ctx != ctx)
         return;
 
     raw_spin_lock(&ctx->lock);
     if (ctx->is_active & EVENT_TIME) {
         update_context_time(ctx);
         update_cgrp_time_from_event(event);
     }
 
     perf_event_update_time(event);
     if (data->group)
         perf_event_update_sibling_time(event);
 
     if (event->state != PERF_EVENT_STATE_ACTIVE)
         goto unlock;
 
     if (!data->group) {
         pmu->read(event);
         data->ret = 0;
         goto unlock;
     }
 
     pmu->start_txn(pmu, PERF_PMU_TXN_READ);
 
     pmu->read(event);
 
     for_each_sibling_event(sub, event) {
         if (sub->state == PERF_EVENT_STATE_ACTIVE) {
             /*
              * Use sibling's PMU rather than @event's since
              * sibling could be on different (eg: software) PMU.
              */
             sub->pmu->read(sub);
         }
     }
 
     data->ret = pmu->commit_txn(pmu);
 
 unlock:
     raw_spin_unlock(&ctx->lock);
 }
 
 static inline u64 perf_event_count(struct perf_event *event)
 {
     return local64_read(&event->count) + atomic64_read(&event->child_count);
 }
 
 static void calc_timer_values(struct perf_event *event,
                 u64 *now,
                 u64 *enabled,
                 u64 *running)
 {
     u64 ctx_time;
 
     *now = perf_clock();
     ctx_time = perf_event_time_now(event, *now);
     __perf_update_times(event, ctx_time, enabled, running);
 }
 
 /*
  * NMI-safe method to read a local event, that is an event that
  * is:
  *   - either for the current task, or for this CPU
  *   - does not have inherit set, for inherited task events
  *     will not be local and we cannot read them atomically
  *   - must not have a pmu::count method
  */
 int perf_event_read_local(struct perf_event *event, u64 *value,
               u64 *enabled, u64 *running)
 {
     unsigned long flags;
     int ret = 0;
 
     /*
      * Disabling interrupts avoids all counter scheduling (context
      * switches, timer based rotation and IPIs).
      */
     local_irq_save(flags);
 
     /*
      * It must not be an event with inherit set, we cannot read
      * all child counters from atomic context.
      */
     if (event->attr.inherit) {
         ret = -EOPNOTSUPP;
         goto out;
     }
 
     /* If this is a per-task event, it must be for current */
     if ((event->attach_state & PERF_ATTACH_TASK) &&
         event->hw.target != current) {
         ret = -EINVAL;
         goto out;
     }
 
     /* If this is a per-CPU event, it must be for this CPU */
     if (!(event->attach_state & PERF_ATTACH_TASK) &&
         event->cpu != smp_processor_id()) {
         ret = -EINVAL;
         goto out;
     }
 
     /* If this is a pinned event it must be running on this CPU */
     if (event->attr.pinned && event->oncpu != smp_processor_id()) {
         ret = -EBUSY;
         goto out;
     }
 
     /*
      * If the event is currently on this CPU, its either a per-task event,
      * or local to this CPU. Furthermore it means its ACTIVE (otherwise
      * oncpu == -1).
      */
     if (event->oncpu == smp_processor_id())
         event->pmu->read(event);
 
     *value = local64_read(&event->count);
     if (enabled || running) {
         u64 __enabled, __running, __now;
 
         calc_timer_values(event, &__now, &__enabled, &__running);
         if (enabled)
             *enabled = __enabled;
         if (running)
             *running = __running;
     }
 out:
     local_irq_restore(flags);
 
     return ret;
 }
 
 static int perf_event_read(struct perf_event *event, bool group)
 {
     enum perf_event_state state = READ_ONCE(event->state);
     int event_cpu, ret = 0;
 
     /*
      * If event is enabled and currently active on a CPU, update the
      * value in the event structure:
      */
 again:
     if (state == PERF_EVENT_STATE_ACTIVE) {
         struct perf_read_data data;
 
         /*
          * Orders the ->state and ->oncpu loads such that if we see
          * ACTIVE we must also see the right ->oncpu.
          *
          * Matches the smp_wmb() from event_sched_in().
          */
         smp_rmb();
 
         event_cpu = READ_ONCE(event->oncpu);
         if ((unsigned)event_cpu >= nr_cpu_ids)
             return 0;
 
         data = (struct perf_read_data){
             .event = event,
             .group = group,
             .ret = 0,
         };
 
         preempt_disable();
         event_cpu = __perf_event_read_cpu(event, event_cpu);
 
         /*
          * Purposely ignore the smp_call_function_single() return
          * value.
          *
          * If event_cpu isn't a valid CPU it means the event got
          * scheduled out and that will have updated the event count.
          *
          * Therefore, either way, we'll have an up-to-date event count
          * after this.
          */
         (void)smp_call_function_single(event_cpu, __perf_event_read, &data, 1);
         preempt_enable();
         ret = data.ret;
 
     } else if (state == PERF_EVENT_STATE_INACTIVE) {
         struct perf_event_context *ctx = event->ctx;
         unsigned long flags;
 
         raw_spin_lock_irqsave(&ctx->lock, flags);
         state = event->state;
         if (state != PERF_EVENT_STATE_INACTIVE) {
             raw_spin_unlock_irqrestore(&ctx->lock, flags);
             goto again;
         }
 
         /*
          * May read while context is not active (e.g., thread is
          * blocked), in that case we cannot update context time
          */
         if (ctx->is_active & EVENT_TIME) {
             update_context_time(ctx);
             update_cgrp_time_from_event(event);
         }
 
         perf_event_update_time(event);
         if (group)
             perf_event_update_sibling_time(event);
         raw_spin_unlock_irqrestore(&ctx->lock, flags);
     }
 
     return ret;
 }
 
 /*
  * Initialize the perf_event context in a task_struct:
  */
 static void __perf_event_init_context(struct perf_event_context *ctx)
 {
     raw_spin_lock_init(&ctx->lock);
     mutex_init(&ctx->mutex);
     INIT_LIST_HEAD(&ctx->active_ctx_list);
     perf_event_groups_init(&ctx->pinned_groups);
     perf_event_groups_init(&ctx->flexible_groups);
     INIT_LIST_HEAD(&ctx->event_list);
     INIT_LIST_HEAD(&ctx->pinned_active);
     INIT_LIST_HEAD(&ctx->flexible_active);
     refcount_set(&ctx->refcount, 1);
 }
 
 static struct perf_event_context *
 alloc_perf_context(struct pmu *pmu, struct task_struct *task)
 {
     struct perf_event_context *ctx;
 
     ctx = kzalloc(sizeof(struct perf_event_context), GFP_KERNEL);
     if (!ctx)
         return NULL;
 
     __perf_event_init_context(ctx);
     if (task)
         ctx->task = get_task_struct(task);
     ctx->pmu = pmu;
 
     return ctx;
 }
 
 static struct task_struct *
 find_lively_task_by_vpid(pid_t vpid)
 {
     struct task_struct *task;
 
     rcu_read_lock();
     if (!vpid)
         task = current;
     else
         task = find_task_by_vpid(vpid);
     if (task)
         get_task_struct(task);
     rcu_read_unlock();
 
     if (!task)
         return ERR_PTR(-ESRCH);
 
     return task;
 }
 
 /*
  * Returns a matching context with refcount and pincount.
  */
 static struct perf_event_context *
 find_get_context(struct pmu *pmu, struct task_struct *task,
         struct perf_event *event)
 {
     struct perf_event_context *ctx, *clone_ctx = NULL;
     struct perf_cpu_context *cpuctx;
     void *task_ctx_data = NULL;
     unsigned long flags;
     int ctxn, err;
     int cpu = event->cpu;
 
     if (!task) {
         /* Must be root to operate on a CPU event: */
         err = perf_allow_cpu(&event->attr);
         if (err)
             return ERR_PTR(err);
 
         cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
         ctx = &cpuctx->ctx;
         get_ctx(ctx);
         raw_spin_lock_irqsave(&ctx->lock, flags);
         ++ctx->pin_count;
         raw_spin_unlock_irqrestore(&ctx->lock, flags);
 
         return ctx;
     }
 
     err = -EINVAL;
     ctxn = pmu->task_ctx_nr;
     if (ctxn < 0)
         goto errout;
 
     if (event->attach_state & PERF_ATTACH_TASK_DATA) {
         task_ctx_data = alloc_task_ctx_data(pmu);
         if (!task_ctx_data) {
             err = -ENOMEM;
             goto errout;
         }
     }
 
 retry:
     ctx = perf_lock_task_context(task, ctxn, &flags);
     if (ctx) {
         clone_ctx = unclone_ctx(ctx);
         ++ctx->pin_count;
 
         if (task_ctx_data && !ctx->task_ctx_data) {
             ctx->task_ctx_data = task_ctx_data;
             task_ctx_data = NULL;
         }
         raw_spin_unlock_irqrestore(&ctx->lock, flags);
 
         if (clone_ctx)
             put_ctx(clone_ctx);
     } else {
         ctx = alloc_perf_context(pmu, task);
         err = -ENOMEM;
         if (!ctx)
             goto errout;
 
         if (task_ctx_data) {
             ctx->task_ctx_data = task_ctx_data;
             task_ctx_data = NULL;
         }
 
         err = 0;
         mutex_lock(&task->perf_event_mutex);
         /*
          * If it has already passed perf_event_exit_task().
          * we must see PF_EXITING, it takes this mutex too.
          */
         if (task->flags & PF_EXITING)
             err = -ESRCH;
         else if (task->perf_event_ctxp[ctxn])
             err = -EAGAIN;
         else {
             get_ctx(ctx);
             ++ctx->pin_count;
             rcu_assign_pointer(task->perf_event_ctxp[ctxn], ctx);
         }
         mutex_unlock(&task->perf_event_mutex);
 
         if (unlikely(err)) {
             put_ctx(ctx);
 
             if (err == -EAGAIN)
                 goto retry;
             goto errout;
         }
     }
 
     free_task_ctx_data(pmu, task_ctx_data);
     return ctx;
 
 errout:
     free_task_ctx_data(pmu, task_ctx_data);
     return ERR_PTR(err);
 }
 
 static void perf_event_free_filter(struct perf_event *event);
 
 static void free_event_rcu(struct rcu_head *head)
 {
     struct perf_event *event;
 
     event = container_of(head, struct perf_event, rcu_head);
     if (event->ns)
         put_pid_ns(event->ns);
     perf_event_free_filter(event);
     kmem_cache_free(perf_event_cache, event);
 }
 
 static void ring_buffer_attach(struct perf_event *event,
                    struct perf_buffer *rb);
 
 static void detach_sb_event(struct perf_event *event)
 {
     struct pmu_event_list *pel = per_cpu_ptr(&pmu_sb_events, event->cpu);
 
     raw_spin_lock(&pel->lock);
     list_del_rcu(&event->sb_list);
     raw_spin_unlock(&pel->lock);
 }
 
 static bool is_sb_event(struct perf_event *event)
 {
     struct perf_event_attr *attr = &event->attr;
 
     if (event->parent)
         return false;
 
     if (event->attach_state & PERF_ATTACH_TASK)
         return false;
 
     if (attr->mmap || attr->mmap_data || attr->mmap2 ||
         attr->comm || attr->comm_exec ||
         attr->task || attr->ksymbol ||
         attr->context_switch || attr->text_poke ||
         attr->bpf_event)
         return true;
     return false;
 }
 
 static void unaccount_pmu_sb_event(struct perf_event *event)
 {
     if (is_sb_event(event))
         detach_sb_event(event);
 }
 
 static void unaccount_event_cpu(struct perf_event *event, int cpu)
 {
     if (event->parent)
         return;
 
     if (is_cgroup_event(event))
         atomic_dec(&per_cpu(perf_cgroup_events, cpu));
 }
 
 #ifdef CONFIG_NO_HZ_FULL
 static DEFINE_SPINLOCK(nr_freq_lock);
 #endif
 
 static void unaccount_freq_event_nohz(void)
 {
 #ifdef CONFIG_NO_HZ_FULL
     spin_lock(&nr_freq_lock);
     if (atomic_dec_and_test(&nr_freq_events))
         tick_nohz_dep_clear(TICK_DEP_BIT_PERF_EVENTS);
     spin_unlock(&nr_freq_lock);
 #endif
 }
 
 static void unaccount_freq_event(void)
 {
     if (tick_nohz_full_enabled())
         unaccount_freq_event_nohz();
     else
         atomic_dec(&nr_freq_events);
 }
 
 static void unaccount_event(struct perf_event *event)
 {
     bool dec = false;
 
     if (event->parent)
         return;
 
     if (event->attach_state & (PERF_ATTACH_TASK | PERF_ATTACH_SCHED_CB))
         dec = true;
     if (event->attr.mmap || event->attr.mmap_data)
         atomic_dec(&nr_mmap_events);
     if (event->attr.build_id)
         atomic_dec(&nr_build_id_events);
     if (event->attr.comm)
         atomic_dec(&nr_comm_events);
     if (event->attr.namespaces)
         atomic_dec(&nr_namespaces_events);
     if (event->attr.cgroup)
         atomic_dec(&nr_cgroup_events);
     if (event->attr.task)
         atomic_dec(&nr_task_events);
     if (event->attr.freq)
         unaccount_freq_event();
     if (event->attr.context_switch) {
         dec = true;
         atomic_dec(&nr_switch_events);
     }
     if (is_cgroup_event(event))
         dec = true;
     if (has_branch_stack(event))
         dec = true;
     if (event->attr.ksymbol)
         atomic_dec(&nr_ksymbol_events);
     if (event->attr.bpf_event)
         atomic_dec(&nr_bpf_events);
     if (event->attr.text_poke)
         atomic_dec(&nr_text_poke_events);
 
     if (dec) {
         if (!atomic_add_unless(&perf_sched_count, -1, 1))
             schedule_delayed_work(&perf_sched_work, HZ);
     }
 
     unaccount_event_cpu(event, event->cpu);
 
     unaccount_pmu_sb_event(event);
 }
 
 static void perf_sched_delayed(struct work_struct *work)
 {
     mutex_lock(&perf_sched_mutex);
     if (atomic_dec_and_test(&perf_sched_count))
         static_branch_disable(&perf_sched_events);
     mutex_unlock(&perf_sched_mutex);
 }
 
 /*
  * The following implement mutual exclusion of events on "exclusive" pmus
  * (PERF_PMU_CAP_EXCLUSIVE). Such pmus can only have one event scheduled
  * at a time, so we disallow creating events that might conflict, namely:
  *
  *  1) cpu-wide events in the presence of per-task events,
  *  2) per-task events in the presence of cpu-wide events,
  *  3) two matching events on the same context.
  *
  * The former two cases are handled in the allocation path (perf_event_alloc(),
  * _free_event()), the latter -- before the first perf_install_in_context().
  */
 static int exclusive_event_init(struct perf_event *event)
 {
     struct pmu *pmu = event->pmu;
 
     if (!is_exclusive_pmu(pmu))
         return 0;
 
     /*
      * Prevent co-existence of per-task and cpu-wide events on the
      * same exclusive pmu.
      *
      * Negative pmu::exclusive_cnt means there are cpu-wide
      * events on this "exclusive" pmu, positive means there are
      * per-task events.
      *
      * Since this is called in perf_event_alloc() path, event::ctx
      * doesn't exist yet; it is, however, safe to use PERF_ATTACH_TASK
      * to mean "per-task event", because unlike other attach states it
      * never gets cleared.
      */
     if (event->attach_state & PERF_ATTACH_TASK) {
         if (!atomic_inc_unless_negative(&pmu->exclusive_cnt))
             return -EBUSY;
     } else {
         if (!atomic_dec_unless_positive(&pmu->exclusive_cnt))
             return -EBUSY;
     }
 
     return 0;
 }
 
 static void exclusive_event_destroy(struct perf_event *event)
 {
     struct pmu *pmu = event->pmu;
 
     if (!is_exclusive_pmu(pmu))
         return;
 
     /* see comment in exclusive_event_init() */
     if (event->attach_state & PERF_ATTACH_TASK)
         atomic_dec(&pmu->exclusive_cnt);
     else
         atomic_inc(&pmu->exclusive_cnt);
 }
 
 static bool exclusive_event_match(struct perf_event *e1, struct perf_event *e2)
 {
     if ((e1->pmu == e2->pmu) &&
         (e1->cpu == e2->cpu ||
          e1->cpu == -1 ||
          e2->cpu == -1))
         return true;
     return false;
 }
 
 static bool exclusive_event_installable(struct perf_event *event,
                     struct perf_event_context *ctx)
 {
     struct perf_event *iter_event;
     struct pmu *pmu = event->pmu;
 
     lockdep_assert_held(&ctx->mutex);
 
     if (!is_exclusive_pmu(pmu))
         return true;
 
     list_for_each_entry(iter_event, &ctx->event_list, event_entry) {
         if (exclusive_event_match(iter_event, event))
             return false;
     }
 
     return true;
 }
 
 static void perf_addr_filters_splice(struct perf_event *event,
                        struct list_head *head);
 
 static void _free_event(struct perf_event *event)
 {
     irq_work_sync(&event->pending);
 
     unaccount_event(event);
 
     security_perf_event_free(event);
 
     if (event->rb) {
         /*
          * Can happen when we close an event with re-directed output.
          *
          * Since we have a 0 refcount, perf_mmap_close() will skip
          * over us; possibly making our ring_buffer_put() the last.
          */
         mutex_lock(&event->mmap_mutex);
         ring_buffer_attach(event, NULL);
         mutex_unlock(&event->mmap_mutex);
     }
 
     if (is_cgroup_event(event))
         perf_detach_cgroup(event);
 
     if (!event->parent) {
         if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)
             put_callchain_buffers();
     }
 
     perf_event_free_bpf_prog(event);
     perf_addr_filters_splice(event, NULL);
     kfree(event->addr_filter_ranges);
 
     if (event->destroy)
         event->destroy(event);
 
     /*
      * Must be after ->destroy(), due to uprobe_perf_close() using
      * hw.target.
      */
     if (event->hw.target)
         put_task_struct(event->hw.target);
 
     /*
      * perf_event_free_task() relies on put_ctx() being 'last', in particular
      * all task references must be cleaned up.
      */
     if (event->ctx)
         put_ctx(event->ctx);
 
     exclusive_event_destroy(event);
     module_put(event->pmu->module);
 
     call_rcu(&event->rcu_head, free_event_rcu);
 }
 
 /*
  * Used to free events which have a known refcount of 1, such as in error paths
  * where the event isn't exposed yet and inherited events.
  */
 static void free_event(struct perf_event *event)
 {
     if (WARN(atomic_long_cmpxchg(&event->refcount, 1, 0) != 1,
                 "unexpected event refcount: %ld; ptr=%p\n",
                 atomic_long_read(&event->refcount), event)) {
         /* leak to avoid use-after-free */
         return;
     }
 
     _free_event(event);
 }
 
 /*
  * Remove user event from the owner task.
  */
 static void perf_remove_from_owner(struct perf_event *event)
 {
     struct task_struct *owner;
 
     rcu_read_lock();
     /*
      * Matches the smp_store_release() in perf_event_exit_task(). If we
      * observe !owner it means the list deletion is complete and we can
      * indeed free this event, otherwise we need to serialize on
      * owner->perf_event_mutex.
      */
     owner = READ_ONCE(event->owner);
     if (owner) {
         /*
          * Since delayed_put_task_struct() also drops the last
          * task reference we can safely take a new reference
          * while holding the rcu_read_lock().
          */
         get_task_struct(owner);
     }
     rcu_read_unlock();
 
     if (owner) {
         /*
          * If we're here through perf_event_exit_task() we're already
          * holding ctx->mutex which would be an inversion wrt. the
          * normal lock order.
          *
          * However we can safely take this lock because its the child
          * ctx->mutex.
          */
         mutex_lock_nested(&owner->perf_event_mutex, SINGLE_DEPTH_NESTING);
 
         /*
          * We have to re-check the event->owner field, if it is cleared
          * we raced with perf_event_exit_task(), acquiring the mutex
          * ensured they're done, and we can proceed with freeing the
          * event.
          */
         if (event->owner) {
             list_del_init(&event->owner_entry);
             smp_store_release(&event->owner, NULL);
         }
         mutex_unlock(&owner->perf_event_mutex);
         put_task_struct(owner);
     }
 }
 
 static void put_event(struct perf_event *event)
 {
     if (!atomic_long_dec_and_test(&event->refcount))
         return;
 
     _free_event(event);
 }
 
 /*
  * Kill an event dead; while event:refcount will preserve the event
  * object, it will not preserve its functionality. Once the last 'user'
  * gives up the object, we'll destroy the thing.
  */
 int perf_event_release_kernel(struct perf_event *event)
 {
     struct perf_event_context *ctx = event->ctx;
     struct perf_event *child, *tmp;
     LIST_HEAD(free_list);
 
     /*
      * If we got here through err_file: fput(event_file); we will not have
      * attached to a context yet.
      */
     if (!ctx) {
         WARN_ON_ONCE(event->attach_state &
                 (PERF_ATTACH_CONTEXT|PERF_ATTACH_GROUP));
         goto no_ctx;
     }
 
     if (!is_kernel_event(event))
         perf_remove_from_owner(event);
 
     ctx = perf_event_ctx_lock(event);
     WARN_ON_ONCE(ctx->parent_ctx);
     perf_remove_from_context(event, DETACH_GROUP);
 
     raw_spin_lock_irq(&ctx->lock);
     /*
      * Mark this event as STATE_DEAD, there is no external reference to it
      * anymore.
      *
      * Anybody acquiring event->child_mutex after the below loop _must_
      * also see this, most importantly inherit_event() which will avoid
      * placing more children on the list.
      *
      * Thus this guarantees that we will in fact observe and kill _ALL_
      * child events.
      */
     event->state = PERF_EVENT_STATE_DEAD;
     raw_spin_unlock_irq(&ctx->lock);
 
     perf_event_ctx_unlock(event, ctx);
 
 again:
     mutex_lock(&event->child_mutex);
     list_for_each_entry(child, &event->child_list, child_list) {
 
         /*
          * Cannot change, child events are not migrated, see the
          * comment with perf_event_ctx_lock_nested().
          */
         ctx = READ_ONCE(child->ctx);
         /*
          * Since child_mutex nests inside ctx::mutex, we must jump
          * through hoops. We start by grabbing a reference on the ctx.
          *
          * Since the event cannot get freed while we hold the
          * child_mutex, the context must also exist and have a !0
          * reference count.
          */
         get_ctx(ctx);
 
         /*
          * Now that we have a ctx ref, we can drop child_mutex, and
          * acquire ctx::mutex without fear of it going away. Then we
          * can re-acquire child_mutex.
          */
         mutex_unlock(&event->child_mutex);
         mutex_lock(&ctx->mutex);
         mutex_lock(&event->child_mutex);
 
         /*
          * Now that we hold ctx::mutex and child_mutex, revalidate our
          * state, if child is still the first entry, it didn't get freed
          * and we can continue doing so.
          */
         tmp = list_first_entry_or_null(&event->child_list,
                            struct perf_event, child_list);
         if (tmp == child) {
             perf_remove_from_context(child, DETACH_GROUP);
             list_move(&child->child_list, &free_list);
             /*
              * This matches the refcount bump in inherit_event();
              * this can't be the last reference.
              */
             put_event(event);
         }
 
         mutex_unlock(&event->child_mutex);
         mutex_unlock(&ctx->mutex);
         put_ctx(ctx);
         goto again;
     }
     mutex_unlock(&event->child_mutex);
 
     list_for_each_entry_safe(child, tmp, &free_list, child_list) {
         void *var = &child->ctx->refcount;
 
         list_del(&child->child_list);
         free_event(child);
 
         /*
          * Wake any perf_event_free_task() waiting for this event to be
          * freed.
          */
         smp_mb(); /* pairs with wait_var_event() */
         wake_up_var(var);
     }
 
 no_ctx:
     put_event(event); /* Must be the 'last' reference */
     return 0;
 }
 EXPORT_SYMBOL_GPL(perf_event_release_kernel);
 
 /*
  * Called when the last reference to the file is gone.
  */
 static int perf_release(struct inode *inode, struct file *file)
 {
     perf_event_release_kernel(file->private_data);
     return 0;
 }
 
 static u64 __perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running)
 {
     struct perf_event *child;
     u64 total = 0;
 
     *enabled = 0;
     *running = 0;
 
     mutex_lock(&event->child_mutex);
 
     (void)perf_event_read(event, false);
     total += perf_event_count(event);
 
     *enabled += event->total_time_enabled +
             atomic64_read(&event->child_total_time_enabled);
     *running += event->total_time_running +
             atomic64_read(&event->child_total_time_running);
 
     list_for_each_entry(child, &event->child_list, child_list) {
         (void)perf_event_read(child, false);
         total += perf_event_count(child);
         *enabled += child->total_time_enabled;
         *running += child->total_time_running;
     }
     mutex_unlock(&event->child_mutex);
 
     return total;
 }
 
 u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running)
 {
     struct perf_event_context *ctx;
     u64 count;
 
     ctx = perf_event_ctx_lock(event);
     count = __perf_event_read_value(event, enabled, running);
     perf_event_ctx_unlock(event, ctx);
 
     return count;
 }
 EXPORT_SYMBOL_GPL(perf_event_read_value);
 
 static int __perf_read_group_add(struct perf_event *leader,
                     u64 read_format, u64 *values)
 {
     struct perf_event_context *ctx = leader->ctx;
     struct perf_event *sub;
     unsigned long flags;
     int n = 1; /* skip @nr */
     int ret;
 
     ret = perf_event_read(leader, true);
     if (ret)
         return ret;
 
     raw_spin_lock_irqsave(&ctx->lock, flags);
 
     /*
      * Since we co-schedule groups, {enabled,running} times of siblings
      * will be identical to those of the leader, so we only publish one
      * set.
      */
     if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
         values[n++] += leader->total_time_enabled +
             atomic64_read(&leader->child_total_time_enabled);
     }
 
     if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
         values[n++] += leader->total_time_running +
             atomic64_read(&leader->child_total_time_running);
     }
 
     /*
      * Write {count,id} tuples for every sibling.
      */
     values[n++] += perf_event_count(leader);
     if (read_format & PERF_FORMAT_ID)
         values[n++] = primary_event_id(leader);
     if (read_format & PERF_FORMAT_LOST)
         values[n++] = atomic64_read(&leader->lost_samples);
 
     for_each_sibling_event(sub, leader) {
         values[n++] += perf_event_count(sub);
         if (read_format & PERF_FORMAT_ID)
             values[n++] = primary_event_id(sub);
         if (read_format & PERF_FORMAT_LOST)
             values[n++] = atomic64_read(&sub->lost_samples);
     }
 
     raw_spin_unlock_irqrestore(&ctx->lock, flags);
     return 0;
 }
 
 static int perf_read_group(struct perf_event *event,
                    u64 read_format, char __user *buf)
 {
     struct perf_event *leader = event->group_leader, *child;
     struct perf_event_context *ctx = leader->ctx;
     int ret;
     u64 *values;
 
     lockdep_assert_held(&ctx->mutex);
 
     values = kzalloc(event->read_size, GFP_KERNEL);
     if (!values)
         return -ENOMEM;
 
     values[0] = 1 + leader->nr_siblings;
 
     /*
      * By locking the child_mutex of the leader we effectively
      * lock the child list of all siblings.. XXX explain how.
      */
     mutex_lock(&leader->child_mutex);
 
     ret = __perf_read_group_add(leader, read_format, values);
     if (ret)
         goto unlock;
 
     list_for_each_entry(child, &leader->child_list, child_list) {
         ret = __perf_read_group_add(child, read_format, values);
         if (ret)
             goto unlock;
     }
 
     mutex_unlock(&leader->child_mutex);
 
     ret = event->read_size;
     if (copy_to_user(buf, values, event->read_size))
         ret = -EFAULT;
     goto out;
 
 unlock:
     mutex_unlock(&leader->child_mutex);
 out:
     kfree(values);
     return ret;
 }
 
 static int perf_read_one(struct perf_event *event,
                  u64 read_format, char __user *buf)
 {
     u64 enabled, running;
     u64 values[5];
     int n = 0;
 
     values[n++] = __perf_event_read_value(event, &enabled, &running);
     if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
         values[n++] = enabled;
     if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
         values[n++] = running;
     if (read_format & PERF_FORMAT_ID)
         values[n++] = primary_event_id(event);
     if (read_format & PERF_FORMAT_LOST)
         values[n++] = atomic64_read(&event->lost_samples);
 
     if (copy_to_user(buf, values, n * sizeof(u64)))
         return -EFAULT;
 
     return n * sizeof(u64);
 }
 
 static bool is_event_hup(struct perf_event *event)
 {
     bool no_children;
 
     if (event->state > PERF_EVENT_STATE_EXIT)
         return false;
 
     mutex_lock(&event->child_mutex);
     no_children = list_empty(&event->child_list);
     mutex_unlock(&event->child_mutex);
     return no_children;
 }
 
 /*
  * Read the performance event - simple non blocking version for now
  */
 static ssize_t
 __perf_read(struct perf_event *event, char __user *buf, size_t count)
 {
     u64 read_format = event->attr.read_format;
     int ret;
 
     /*
      * Return end-of-file for a read on an event that is in
      * error state (i.e. because it was pinned but it couldn't be
      * scheduled on to the CPU at some point).
      */
     if (event->state == PERF_EVENT_STATE_ERROR)
         return 0;
 
     if (count < event->read_size)
         return -ENOSPC;
 
     WARN_ON_ONCE(event->ctx->parent_ctx);
     if (read_format & PERF_FORMAT_GROUP)
         ret = perf_read_group(event, read_format, buf);
     else
         ret = perf_read_one(event, read_format, buf);
 
     return ret;
 }
 
 static ssize_t
 perf_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 {
     struct perf_event *event = file->private_data;
     struct perf_event_context *ctx;
     int ret;
 
     ret = security_perf_event_read(event);
     if (ret)
         return ret;
 
     ctx = perf_event_ctx_lock(event);
     ret = __perf_read(event, buf, count);
     perf_event_ctx_unlock(event, ctx);
 
     return ret;
 }
 
 static __poll_t perf_poll(struct file *file, poll_table *wait)
 {
     struct perf_event *event = file->private_data;
     struct perf_buffer *rb;
     __poll_t events = EPOLLHUP;
 
     poll_wait(file, &event->waitq, wait);
 
     if (is_event_hup(event))
         return events;
 
     /*
      * Pin the event->rb by taking event->mmap_mutex; otherwise
      * perf_event_set_output() can swizzle our rb and make us miss wakeups.
      */
     mutex_lock(&event->mmap_mutex);
     rb = event->rb;
     if (rb)
         events = atomic_xchg(&rb->poll, 0);
     mutex_unlock(&event->mmap_mutex);
     return events;
 }
 
 static void _perf_event_reset(struct perf_event *event)
 {
     (void)perf_event_read(event, false);
     local64_set(&event->count, 0);
     perf_event_update_userpage(event);
 }
 
 /* Assume it's not an event with inherit set. */
 u64 perf_event_pause(struct perf_event *event, bool reset)
 {
     struct perf_event_context *ctx;
     u64 count;
 
     ctx = perf_event_ctx_lock(event);
     WARN_ON_ONCE(event->attr.inherit);
     _perf_event_disable(event);
     count = local64_read(&event->count);
     if (reset)
         local64_set(&event->count, 0);
     perf_event_ctx_unlock(event, ctx);
 
     return count;
 }
 EXPORT_SYMBOL_GPL(perf_event_pause);
 
 /*
  * Holding the top-level event's child_mutex means that any
  * descendant process that has inherited this event will block
  * in perf_event_exit_event() if it goes to exit, thus satisfying the
  * task existence requirements of perf_event_enable/disable.
  */
 static void perf_event_for_each_child(struct perf_event *event,
                     void (*func)(struct perf_event *))
 {
     struct perf_event *child;
 
     WARN_ON_ONCE(event->ctx->parent_ctx);
 
     mutex_lock(&event->child_mutex);
     func(event);
     list_for_each_entry(child, &event->child_list, child_list)
         func(child);
     mutex_unlock(&event->child_mutex);
 }
 
 static void perf_event_for_each(struct perf_event *event,
                   void (*func)(struct perf_event *))
 {
     struct perf_event_context *ctx = event->ctx;
     struct perf_event *sibling;
 
     lockdep_assert_held(&ctx->mutex);
 
     event = event->group_leader;
 
     perf_event_for_each_child(event, func);
     for_each_sibling_event(sibling, event)
         perf_event_for_each_child(sibling, func);
 }
 
 static void __perf_event_period(struct perf_event *event,
                 struct perf_cpu_context *cpuctx,
                 struct perf_event_context *ctx,
                 void *info)
 {
     u64 value = *((u64 *)info);
     bool active;
 
     if (event->attr.freq) {
         event->attr.sample_freq = value;
     } else {
         event->attr.sample_period = value;
         event->hw.sample_period = value;
     }
 
     active = (event->state == PERF_EVENT_STATE_ACTIVE);
     if (active) {
         perf_pmu_disable(ctx->pmu);
         /*
          * We could be throttled; unthrottle now to avoid the tick
          * trying to unthrottle while we already re-started the event.
          */
         if (event->hw.interrupts == MAX_INTERRUPTS) {
             event->hw.interrupts = 0;
             perf_log_throttle(event, 1);
         }
         event->pmu->stop(event, PERF_EF_UPDATE);
     }
 
     local64_set(&event->hw.period_left, 0);
 
     if (active) {
         event->pmu->start(event, PERF_EF_RELOAD);
         perf_pmu_enable(ctx->pmu);
     }
 }
 
 static int perf_event_check_period(struct perf_event *event, u64 value)
 {
     return event->pmu->check_period(event, value);
 }
 
 static int _perf_event_period(struct perf_event *event, u64 value)
 {
     if (!is_sampling_event(event))
         return -EINVAL;
 
     if (!value)
         return -EINVAL;
 
     if (event->attr.freq && value > sysctl_perf_event_sample_rate)
         return -EINVAL;
 
     if (perf_event_check_period(event, value))
         return -EINVAL;
 
     if (!event->attr.freq && (value & (1ULL << 63)))
         return -EINVAL;
 
     event_function_call(event, __perf_event_period, &value);
 
     return 0;
 }
 
 int perf_event_period(struct perf_event *event, u64 value)
 {
     struct perf_event_context *ctx;
     int ret;
 
     ctx = perf_event_ctx_lock(event);
     ret = _perf_event_period(event, value);
     perf_event_ctx_unlock(event, ctx);
 
     return ret;
 }
 EXPORT_SYMBOL_GPL(perf_event_period);
 
 static const struct file_operations perf_fops;
 
 static inline int perf_fget_light(int fd, struct fd *p)
 {
     struct fd f = fdget(fd);
     if (!f.file)
         return -EBADF;
 
     if (f.file->f_op != &perf_fops) {
         fdput(f);
         return -EBADF;
     }
     *p = f;
     return 0;
 }
 
 static int perf_event_set_output(struct perf_event *event,
                  struct perf_event *output_event);
 static int perf_event_set_filter(struct perf_event *event, void __user *arg);
 static int perf_copy_attr(struct perf_event_attr __user *uattr,
               struct perf_event_attr *attr);
 
 static long _perf_ioctl(struct perf_event *event, unsigned int cmd, unsigned long arg)
 {
     void (*func)(struct perf_event *);
     u32 flags = arg;
 
     switch (cmd) {
     case PERF_EVENT_IOC_ENABLE:
         func = _perf_event_enable;
         break;
     case PERF_EVENT_IOC_DISABLE:
         func = _perf_event_disable;
         break;
     case PERF_EVENT_IOC_RESET:
         func = _perf_event_reset;
         break;
 
     case PERF_EVENT_IOC_REFRESH:
         return _perf_event_refresh(event, arg);
 
     case PERF_EVENT_IOC_PERIOD:
     {
         u64 value;
 
         if (copy_from_user(&value, (u64 __user *)arg, sizeof(value)))
             return -EFAULT;
 
         return _perf_event_period(event, value);
     }
     case PERF_EVENT_IOC_ID:
     {
         u64 id = primary_event_id(event);
 
         if (copy_to_user((void __user *)arg, &id, sizeof(id)))
             return -EFAULT;
         return 0;
     }
 
     case PERF_EVENT_IOC_SET_OUTPUT:
     {
         int ret;
         if (arg != -1) {
             struct perf_event *output_event;
             struct fd output;
             ret = perf_fget_light(arg, &output);
             if (ret)
                 return ret;
             output_event = output.file->private_data;
             ret = perf_event_set_output(event, output_event);
             fdput(output);
         } else {
             ret = perf_event_set_output(event, NULL);
         }
         return ret;
     }
 
     case PERF_EVENT_IOC_SET_FILTER:
         return perf_event_set_filter(event, (void __user *)arg);
 
     case PERF_EVENT_IOC_SET_BPF:
     {
         struct bpf_prog *prog;
         int err;
 
         prog = bpf_prog_get(arg);
         if (IS_ERR(prog))
             return PTR_ERR(prog);
 
         err = perf_event_set_bpf_prog(event, prog, 0);
         if (err) {
             bpf_prog_put(prog);
             return err;
         }
 
         return 0;
     }
 
     case PERF_EVENT_IOC_PAUSE_OUTPUT: {
         struct perf_buffer *rb;
 
         rcu_read_lock();
         rb = rcu_dereference(event->rb);
         if (!rb || !rb->nr_pages) {
             rcu_read_unlock();
             return -EINVAL;
         }
         rb_toggle_paused(rb, !!arg);
         rcu_read_unlock();
         return 0;
     }
 
     case PERF_EVENT_IOC_QUERY_BPF:
         return perf_event_query_prog_array(event, (void __user *)arg);
 
     case PERF_EVENT_IOC_MODIFY_ATTRIBUTES: {
         struct perf_event_attr new_attr;
         int err = perf_copy_attr((struct perf_event_attr __user *)arg,
                      &new_attr);
 
         if (err)
             return err;
 
         return perf_event_modify_attr(event,  &new_attr);
     }
     default:
         return -ENOTTY;
     }
 
     if (flags & PERF_IOC_FLAG_GROUP)
         perf_event_for_each(event, func);
     else
         perf_event_for_each_child(event, func);
 
     return 0;
 }
 
 static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
     struct perf_event *event = file->private_data;
     struct perf_event_context *ctx;
     long ret;
 
     /* Treat ioctl like writes as it is likely a mutating operation. */
     ret = security_perf_event_write(event);
     if (ret)
         return ret;
 
     ctx = perf_event_ctx_lock(event);
     ret = _perf_ioctl(event, cmd, arg);
     perf_event_ctx_unlock(event, ctx);
 
     return ret;
 }
 
 #ifdef CONFIG_COMPAT
 static long perf_compat_ioctl(struct file *file, unsigned int cmd,
                 unsigned long arg)
 {
     switch (_IOC_NR(cmd)) {
     case _IOC_NR(PERF_EVENT_IOC_SET_FILTER):
     case _IOC_NR(PERF_EVENT_IOC_ID):
     case _IOC_NR(PERF_EVENT_IOC_QUERY_BPF):
     case _IOC_NR(PERF_EVENT_IOC_MODIFY_ATTRIBUTES):
         /* Fix up pointer size (usually 4 -> 8 in 32-on-64-bit case */
         if (_IOC_SIZE(cmd) == sizeof(compat_uptr_t)) {
             cmd &= ~IOCSIZE_MASK;
             cmd |= sizeof(void *) << IOCSIZE_SHIFT;
         }
         break;
     }
     return perf_ioctl(file, cmd, arg);
 }
 #else
 # define perf_compat_ioctl NULL
 #endif
 
 int perf_event_task_enable(void)
 {
     struct perf_event_context *ctx;
     struct perf_event *event;
 
     mutex_lock(&current->perf_event_mutex);
     list_for_each_entry(event, &current->perf_event_list, owner_entry) {
         ctx = perf_event_ctx_lock(event);
         perf_event_for_each_child(event, _perf_event_enable);
         perf_event_ctx_unlock(event, ctx);
     }
     mutex_unlock(&current->perf_event_mutex);
 
     return 0;
 }
 
 int perf_event_task_disable(void)
 {
     struct perf_event_context *ctx;
     struct perf_event *event;
 
     mutex_lock(&current->perf_event_mutex);
     list_for_each_entry(event, &current->perf_event_list, owner_entry) {
         ctx = perf_event_ctx_lock(event);
         perf_event_for_each_child(event, _perf_event_disable);
         perf_event_ctx_unlock(event, ctx);
     }
     mutex_unlock(&current->perf_event_mutex);
 
     return 0;
 }
 
 static int perf_event_index(struct perf_event *event)
 {
     if (event->hw.state & PERF_HES_STOPPED)
         return 0;
 
     if (event->state != PERF_EVENT_STATE_ACTIVE)
         return 0;
 
     return event->pmu->event_idx(event);
 }
 
 static void perf_event_init_userpage(struct perf_event *event)
 {
     struct perf_event_mmap_page *userpg;
     struct perf_buffer *rb;
 
     rcu_read_lock();
     rb = rcu_dereference(event->rb);
     if (!rb)
         goto unlock;
 
     userpg = rb->user_page;
 
     /* Allow new userspace to detect that bit 0 is deprecated */
     userpg->cap_bit0_is_deprecated = 1;
     userpg->size = offsetof(struct perf_event_mmap_page, __reserved);
     userpg->data_offset = PAGE_SIZE;
     userpg->data_size = perf_data_size(rb);
 
 unlock:
     rcu_read_unlock();
 }
 
 void __weak arch_perf_update_userpage(
     struct perf_event *event, struct perf_event_mmap_page *userpg, u64 now)
 {
 }
 
 /*
  * Callers need to ensure there can be no nesting of this function, otherwise
  * the seqlock logic goes bad. We can not serialize this because the arch
  * code calls this from NMI context.
  */
 void perf_event_update_userpage(struct perf_event *event)
 {
     struct perf_event_mmap_page *userpg;
     struct perf_buffer *rb;
     u64 enabled, running, now;
 
     rcu_read_lock();
     rb = rcu_dereference(event->rb);
     if (!rb)
         goto unlock;
 
     /*
      * compute total_time_enabled, total_time_running
      * based on snapshot values taken when the event
      * was last scheduled in.
      *
      * we cannot simply called update_context_time()
      * because of locking issue as we can be called in
      * NMI context
      */
     calc_timer_values(event, &now, &enabled, &running);
 
     userpg = rb->user_page;
     /*
      * Disable preemption to guarantee consistent time stamps are stored to
      * the user page.
      */
     preempt_disable();
     ++userpg->lock;
     barrier();
     userpg->index = perf_event_index(event);
     userpg->offset = perf_event_count(event);
     if (userpg->index)
         userpg->offset -= local64_read(&event->hw.prev_count);
 
     userpg->time_enabled = enabled +
             atomic64_read(&event->child_total_time_enabled);
 
     userpg->time_running = running +
             atomic64_read(&event->child_total_time_running);
 
     arch_perf_update_userpage(event, userpg, now);
 
     barrier();
     ++userpg->lock;
     preempt_enable();
 unlock:
     rcu_read_unlock();
 }
 EXPORT_SYMBOL_GPL(perf_event_update_userpage);
 
 static vm_fault_t perf_mmap_fault(struct vm_fault *vmf)
 {
     struct perf_event *event = vmf->vma->vm_file->private_data;
     struct perf_buffer *rb;
     vm_fault_t ret = VM_FAULT_SIGBUS;
 
     if (vmf->flags & FAULT_FLAG_MKWRITE) {
         if (vmf->pgoff == 0)
             ret = 0;
         return ret;
     }
 
     rcu_read_lock();
     rb = rcu_dereference(event->rb);
     if (!rb)
         goto unlock;
 
     if (vmf->pgoff && (vmf->flags & FAULT_FLAG_WRITE))
         goto unlock;
 
     vmf->page = perf_mmap_to_page(rb, vmf->pgoff);
     if (!vmf->page)
         goto unlock;
 
     get_page(vmf->page);
     vmf->page->mapping = vmf->vma->vm_file->f_mapping;
     vmf->page->index   = vmf->pgoff;
 
     ret = 0;
 unlock:
     rcu_read_unlock();
 
     return ret;
 }
 
 static void ring_buffer_attach(struct perf_event *event,
                    struct perf_buffer *rb)
 {
     struct perf_buffer *old_rb = NULL;
     unsigned long flags;
 
     WARN_ON_ONCE(event->parent);
 
     if (event->rb) {
         /*
          * Should be impossible, we set this when removing
          * event->rb_entry and wait/clear when adding event->rb_entry.
          */
         WARN_ON_ONCE(event->rcu_pending);
 
         old_rb = event->rb;
         spin_lock_irqsave(&old_rb->event_lock, flags);
         list_del_rcu(&event->rb_entry);
         spin_unlock_irqrestore(&old_rb->event_lock, flags);
 
         event->rcu_batches = get_state_synchronize_rcu();
         event->rcu_pending = 1;
     }
 
     if (rb) {
         if (event->rcu_pending) {
             cond_synchronize_rcu(event->rcu_batches);
             event->rcu_pending = 0;
         }
 
         spin_lock_irqsave(&rb->event_lock, flags);
         list_add_rcu(&event->rb_entry, &rb->event_list);
         spin_unlock_irqrestore(&rb->event_lock, flags);
     }
 
     /*
      * Avoid racing with perf_mmap_close(AUX): stop the event
      * before swizzling the event::rb pointer; if it's getting
      * unmapped, its aux_mmap_count will be 0 and it won't
      * restart. See the comment in __perf_pmu_output_stop().
      *
      * Data will inevitably be lost when set_output is done in
      * mid-air, but then again, whoever does it like this is
      * not in for the data anyway.
      */
     if (has_aux(event))
         perf_event_stop(event, 0);
 
     rcu_assign_pointer(event->rb, rb);
 
     if (old_rb) {
         ring_buffer_put(old_rb);
         /*
          * Since we detached before setting the new rb, so that we
          * could attach the new rb, we could have missed a wakeup.
          * Provide it now.
          */
         wake_up_all(&event->waitq);
     }
 }
 
 static void ring_buffer_wakeup(struct perf_event *event)
 {
     struct perf_buffer *rb;
 
     if (event->parent)
         event = event->parent;
 
     rcu_read_lock();
     rb = rcu_dereference(event->rb);
     if (rb) {
         list_for_each_entry_rcu(event, &rb->event_list, rb_entry)
             wake_up_all(&event->waitq);
     }
     rcu_read_unlock();
 }
 
 struct perf_buffer *ring_buffer_get(struct perf_event *event)
 {
     struct perf_buffer *rb;
 
     if (event->parent)
         event = event->parent;
 
     rcu_read_lock();
     rb = rcu_dereference(event->rb);
     if (rb) {
         if (!refcount_inc_not_zero(&rb->refcount))
             rb = NULL;
     }
     rcu_read_unlock();
 
     return rb;
 }
 
 void ring_buffer_put(struct perf_buffer *rb)
 {
     if (!refcount_dec_and_test(&rb->refcount))
         return;
 
     WARN_ON_ONCE(!list_empty(&rb->event_list));
 
     call_rcu(&rb->rcu_head, rb_free_rcu);
 }
 
 static void perf_mmap_open(struct vm_area_struct *vma)
 {
     struct perf_event *event = vma->vm_file->private_data;
 
     atomic_inc(&event->mmap_count);
     atomic_inc(&event->rb->mmap_count);
 
     if (vma->vm_pgoff)
         atomic_inc(&event->rb->aux_mmap_count);
 
     if (event->pmu->event_mapped)
         event->pmu->event_mapped(event, vma->vm_mm);
 }
 
 static void perf_pmu_output_stop(struct perf_event *event);
 
 /*
  * A buffer can be mmap()ed multiple times; either directly through the same
  * event, or through other events by use of perf_event_set_output().
  *
  * In order to undo the VM accounting done by perf_mmap() we need to destroy
  * the buffer here, where we still have a VM context. This means we need
  * to detach all events redirecting to us.
  */
 static void perf_mmap_close(struct vm_area_struct *vma)
 {
     struct perf_event *event = vma->vm_file->private_data;
     struct perf_buffer *rb = ring_buffer_get(event);
     struct user_struct *mmap_user = rb->mmap_user;
     int mmap_locked = rb->mmap_locked;
     unsigned long size = perf_data_size(rb);
     bool detach_rest = false;
 
     if (event->pmu->event_unmapped)
         event->pmu->event_unmapped(event, vma->vm_mm);
 
     /*
      * rb->aux_mmap_count will always drop before rb->mmap_count and
      * event->mmap_count, so it is ok to use event->mmap_mutex to
      * serialize with perf_mmap here.
      */
     if (rb_has_aux(rb) && vma->vm_pgoff == rb->aux_pgoff &&
         atomic_dec_and_mutex_lock(&rb->aux_mmap_count, &event->mmap_mutex)) {
         /*
          * Stop all AUX events that are writing to this buffer,
          * so that we can free its AUX pages and corresponding PMU
          * data. Note that after rb::aux_mmap_count dropped to zero,
          * they won't start any more (see perf_aux_output_begin()).
          */
         perf_pmu_output_stop(event);
 
         /* now it's safe to free the pages */
         atomic_long_sub(rb->aux_nr_pages - rb->aux_mmap_locked, &mmap_user->locked_vm);
         atomic64_sub(rb->aux_mmap_locked, &vma->vm_mm->pinned_vm);
 
         /* this has to be the last one */
         rb_free_aux(rb);
         WARN_ON_ONCE(refcount_read(&rb->aux_refcount));
 
         mutex_unlock(&event->mmap_mutex);
     }
 
     if (atomic_dec_and_test(&rb->mmap_count))
         detach_rest = true;
 
     if (!atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex))
         goto out_put;
 
     ring_buffer_attach(event, NULL);
     mutex_unlock(&event->mmap_mutex);
 
     /* If there's still other mmap()s of this buffer, we're done. */
     if (!detach_rest)
         goto out_put;
 
     /*
      * No other mmap()s, detach from all other events that might redirect
      * into the now unreachable buffer. Somewhat complicated by the
      * fact that rb::event_lock otherwise nests inside mmap_mutex.
      */
 again:
     rcu_read_lock();
     list_for_each_entry_rcu(event, &rb->event_list, rb_entry) {
         if (!atomic_long_inc_not_zero(&event->refcount)) {
             /*
              * This event is en-route to free_event() which will
              * detach it and remove it from the list.
              */
             continue;
         }
         rcu_read_unlock();
 
         mutex_lock(&event->mmap_mutex);
         /*
          * Check we didn't race with perf_event_set_output() which can
          * swizzle the rb from under us while we were waiting to
          * acquire mmap_mutex.
          *
          * If we find a different rb; ignore this event, a next
          * iteration will no longer find it on the list. We have to
          * still restart the iteration to make sure we're not now
          * iterating the wrong list.
          */
         if (event->rb == rb)
             ring_buffer_attach(event, NULL);
 
         mutex_unlock(&event->mmap_mutex);
         put_event(event);
 
         /*
          * Restart the iteration; either we're on the wrong list or
          * destroyed its integrity by doing a deletion.
          */
         goto again;
     }
     rcu_read_unlock();
 
     /*
      * It could be there's still a few 0-ref events on the list; they'll
      * get cleaned up by free_event() -- they'll also still have their
      * ref on the rb and will free it whenever they are done with it.
      *
      * Aside from that, this buffer is 'fully' detached and unmapped,
      * undo the VM accounting.
      */
 
     atomic_long_sub((size >> PAGE_SHIFT) + 1 - mmap_locked,
             &mmap_user->locked_vm);
     atomic64_sub(mmap_locked, &vma->vm_mm->pinned_vm);
     free_uid(mmap_user);
 
 out_put:
     ring_buffer_put(rb); /* could be last */
 }
 
 static const struct vm_operations_struct perf_mmap_vmops = {
     .open       = perf_mmap_open,
     .close      = perf_mmap_close, /* non mergeable */
     .fault      = perf_mmap_fault,
     .page_mkwrite   = perf_mmap_fault,
 };
 
 static int perf_mmap(struct file *file, struct vm_area_struct *vma)
 {
     struct perf_event *event = file->private_data;
     unsigned long user_locked, user_lock_limit;
     struct user_struct *user = current_user();
     struct perf_buffer *rb = NULL;
     unsigned long locked, lock_limit;
     unsigned long vma_size;
     unsigned long nr_pages;
     long user_extra = 0, extra = 0;
     int ret = 0, flags = 0;
 
     /*
      * Don't allow mmap() of inherited per-task counters. This would
      * create a performance issue due to all children writing to the
      * same rb.
      */
     if (event->cpu == -1 && event->attr.inherit)
         return -EINVAL;
 
     if (!(vma->vm_flags & VM_SHARED))
         return -EINVAL;
 
     ret = security_perf_event_read(event);
     if (ret)
         return ret;
 
     vma_size = vma->vm_end - vma->vm_start;
 
     if (vma->vm_pgoff == 0) {
         nr_pages = (vma_size / PAGE_SIZE) - 1;
     } else {
         /*
          * AUX area mapping: if rb->aux_nr_pages != 0, it's already
          * mapped, all subsequent mappings should have the same size
          * and offset. Must be above the normal perf buffer.
          */
         u64 aux_offset, aux_size;
 
         if (!event->rb)
             return -EINVAL;
 
         nr_pages = vma_size / PAGE_SIZE;
 
         mutex_lock(&event->mmap_mutex);
         ret = -EINVAL;
 
         rb = event->rb;
         if (!rb)
             goto aux_unlock;
 
         aux_offset = READ_ONCE(rb->user_page->aux_offset);
         aux_size = READ_ONCE(rb->user_page->aux_size);
 
         if (aux_offset < perf_data_size(rb) + PAGE_SIZE)
             goto aux_unlock;
 
         if (aux_offset != vma->vm_pgoff << PAGE_SHIFT)
             goto aux_unlock;
 
         /* already mapped with a different offset */
         if (rb_has_aux(rb) && rb->aux_pgoff != vma->vm_pgoff)
             goto aux_unlock;
 
         if (aux_size != vma_size || aux_size != nr_pages * PAGE_SIZE)
             goto aux_unlock;
 
         /* already mapped with a different size */
         if (rb_has_aux(rb) && rb->aux_nr_pages != nr_pages)
             goto aux_unlock;
 
         if (!is_power_of_2(nr_pages))
             goto aux_unlock;
 
         if (!atomic_inc_not_zero(&rb->mmap_count))
             goto aux_unlock;
 
         if (rb_has_aux(rb)) {
             atomic_inc(&rb->aux_mmap_count);
             ret = 0;
             goto unlock;
         }
 
         atomic_set(&rb->aux_mmap_count, 1);
         user_extra = nr_pages;
 
         goto accounting;
     }
 
     /*
      * If we have rb pages ensure they're a power-of-two number, so we
      * can do bitmasks instead of modulo.
      */
     if (nr_pages != 0 && !is_power_of_2(nr_pages))
         return -EINVAL;
 
     if (vma_size != PAGE_SIZE * (1 + nr_pages))
         return -EINVAL;
 
     WARN_ON_ONCE(event->ctx->parent_ctx);
 again:
     mutex_lock(&event->mmap_mutex);
     if (event->rb) {
         if (data_page_nr(event->rb) != nr_pages) {
             ret = -EINVAL;
             goto unlock;
         }
 
         if (!atomic_inc_not_zero(&event->rb->mmap_count)) {
             /*
              * Raced against perf_mmap_close(); remove the
              * event and try again.
              */
             ring_buffer_attach(event, NULL);
             mutex_unlock(&event->mmap_mutex);
             goto again;
         }
 
         goto unlock;
     }
 
     user_extra = nr_pages + 1;
 
 accounting:
     user_lock_limit = sysctl_perf_event_mlock >> (PAGE_SHIFT - 10);
 
     /*
      * Increase the limit linearly with more CPUs:
      */
     user_lock_limit *= num_online_cpus();
 
     user_locked = atomic_long_read(&user->locked_vm);
 
     /*
      * sysctl_perf_event_mlock may have changed, so that
      *     user->locked_vm > user_lock_limit
      */
     if (user_locked > user_lock_limit)
         user_locked = user_lock_limit;
     user_locked += user_extra;
 
     if (user_locked > user_lock_limit) {
         /*
          * charge locked_vm until it hits user_lock_limit;
          * charge the rest from pinned_vm
          */
         extra = user_locked - user_lock_limit;
         user_extra -= extra;
     }
 
     lock_limit = rlimit(RLIMIT_MEMLOCK);
     lock_limit >>= PAGE_SHIFT;
     locked = atomic64_read(&vma->vm_mm->pinned_vm) + extra;
 
     if ((locked > lock_limit) && perf_is_paranoid() &&
         !capable(CAP_IPC_LOCK)) {
         ret = -EPERM;
         goto unlock;
     }
 
     WARN_ON(!rb && event->rb);
 
     if (vma->vm_flags & VM_WRITE)
         flags |= RING_BUFFER_WRITABLE;
 
     if (!rb) {
         rb = rb_alloc(nr_pages,
                   event->attr.watermark ? event->attr.wakeup_watermark : 0,
                   event->cpu, flags);
 
         if (!rb) {
             ret = -ENOMEM;
             goto unlock;
         }
 
         atomic_set(&rb->mmap_count, 1);
         rb->mmap_user = get_current_user();
         rb->mmap_locked = extra;
 
         ring_buffer_attach(event, rb);
 
         perf_event_update_time(event);
         perf_event_init_userpage(event);
         perf_event_update_userpage(event);
     } else {
         ret = rb_alloc_aux(rb, event, vma->vm_pgoff, nr_pages,
                    event->attr.aux_watermark, flags);
         if (!ret)
             rb->aux_mmap_locked = extra;
     }
 
 unlock:
     if (!ret) {
         atomic_long_add(user_extra, &user->locked_vm);
         atomic64_add(extra, &vma->vm_mm->pinned_vm);
 
         atomic_inc(&event->mmap_count);
     } else if (rb) {
         atomic_dec(&rb->mmap_count);
     }
 aux_unlock:
     mutex_unlock(&event->mmap_mutex);
 
     /*
      * Since pinned accounting is per vm we cannot allow fork() to copy our
      * vma.
      */
     vma->vm_flags |= VM_DONTCOPY | VM_DONTEXPAND | VM_DONTDUMP;
     vma->vm_ops = &perf_mmap_vmops;
 
     if (event->pmu->event_mapped)
         event->pmu->event_mapped(event, vma->vm_mm);
 
     return ret;
 }
 
 static int perf_fasync(int fd, struct file *filp, int on)
 {
     struct inode *inode = file_inode(filp);
     struct perf_event *event = filp->private_data;
     int retval;
 
     inode_lock(inode);
     retval = fasync_helper(fd, filp, on, &event->fasync);
     inode_unlock(inode);
 
     if (retval < 0)
         return retval;
 
     return 0;
 }
 
 static const struct file_operations perf_fops = {
     .llseek         = no_llseek,
     .release        = perf_release,
     .read           = perf_read,
     .poll           = perf_poll,
     .unlocked_ioctl     = perf_ioctl,
     .compat_ioctl       = perf_compat_ioctl,
     .mmap           = perf_mmap,
     .fasync         = perf_fasync,
 };
 
 /*
  * Perf event wakeup
  *
  * If there's data, ensure we set the poll() state and publish everything
  * to user-space before waking everybody up.
  */
 
 static inline struct fasync_struct **perf_event_fasync(struct perf_event *event)
 {
     /* only the parent has fasync state */
     if (event->parent)
         event = event->parent;
     return &event->fasync;
 }
 
 void perf_event_wakeup(struct perf_event *event)
 {
     ring_buffer_wakeup(event);
 
     if (event->pending_kill) {
         kill_fasync(perf_event_fasync(event), SIGIO, event->pending_kill);
         event->pending_kill = 0;
     }
 }
 
 static void perf_sigtrap(struct perf_event *event)
 {
     /*
      * We'd expect this to only occur if the irq_work is delayed and either
      * ctx->task or current has changed in the meantime. This can be the
      * case on architectures that do not implement arch_irq_work_raise().
      */
     if (WARN_ON_ONCE(event->ctx->task != current))
         return;
 
     /*
      * perf_pending_event() can race with the task exiting.
      */
     if (current->flags & PF_EXITING)
         return;
 
     send_sig_perf((void __user *)event->pending_addr,
               event->attr.type, event->attr.sig_data);
 }
 
 static void perf_pending_event_disable(struct perf_event *event)
 {
     int cpu = READ_ONCE(event->pending_disable);
 
     if (cpu < 0)
         return;
 
     if (cpu == smp_processor_id()) {
         WRITE_ONCE(event->pending_disable, -1);
 
         if (event->attr.sigtrap) {
             perf_sigtrap(event);
             atomic_set_release(&event->event_limit, 1); /* rearm event */
             return;
         }
 
         perf_event_disable_local(event);
         return;
     }
 
     /*
      *  CPU-A           CPU-B
      *
      *  perf_event_disable_inatomic()
      *    @pending_disable = CPU-A;
      *    irq_work_queue();
      *
      *  sched-out
      *    @pending_disable = -1;
      *
      *              sched-in
      *              perf_event_disable_inatomic()
      *                @pending_disable = CPU-B;
      *                irq_work_queue(); // FAILS
      *
      *  irq_work_run()
      *    perf_pending_event()
      *
      * But the event runs on CPU-B and wants disabling there.
      */
     irq_work_queue_on(&event->pending, cpu);
 }
 
 static void perf_pending_event(struct irq_work *entry)
 {
     struct perf_event *event = container_of(entry, struct perf_event, pending);
     int rctx;
 
     rctx = perf_swevent_get_recursion_context();
     /*
      * If we 'fail' here, that's OK, it means recursion is already disabled
      * and we won't recurse 'further'.
      */
 
     perf_pending_event_disable(event);
 
     if (event->pending_wakeup) {
         event->pending_wakeup = 0;
         perf_event_wakeup(event);
     }
 
     if (rctx >= 0)
         perf_swevent_put_recursion_context(rctx);
 }
 
 #ifdef CONFIG_GUEST_PERF_EVENTS
 struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
 
 DEFINE_STATIC_CALL_RET0(__perf_guest_state, *perf_guest_cbs->state);
 DEFINE_STATIC_CALL_RET0(__perf_guest_get_ip, *perf_guest_cbs->get_ip);
 DEFINE_STATIC_CALL_RET0(__perf_guest_handle_intel_pt_intr, *perf_guest_cbs->handle_intel_pt_intr);
 
 void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 {
     if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs)))
         return;
 
     rcu_assign_pointer(perf_guest_cbs, cbs);
     static_call_update(__perf_guest_state, cbs->state);
     static_call_update(__perf_guest_get_ip, cbs->get_ip);
 
     /* Implementing ->handle_intel_pt_intr is optional. */
     if (cbs->handle_intel_pt_intr)
         static_call_update(__perf_guest_handle_intel_pt_intr,
                    cbs->handle_intel_pt_intr);
 }
 EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
 
 void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 {
     if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs) != cbs))
         return;
 
     rcu_assign_pointer(perf_guest_cbs, NULL);
     static_call_update(__perf_guest_state, (void *)&__static_call_return0);
     static_call_update(__perf_guest_get_ip, (void *)&__static_call_return0);
     static_call_update(__perf_guest_handle_intel_pt_intr,
                (void *)&__static_call_return0);
     synchronize_rcu();
 }
 EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
 #endif
 
 static void
 perf_output_sample_regs(struct perf_output_handle *handle,
             struct pt_regs *regs, u64 mask)
 {
     int bit;
     DECLARE_BITMAP(_mask, 64);
 
     bitmap_from_u64(_mask, mask);
     for_each_set_bit(bit, _mask, sizeof(mask) * BITS_PER_BYTE) {
         u64 val;
 
         val = perf_reg_value(regs, bit);
         perf_output_put(handle, val);
     }
 }
 
 static void perf_sample_regs_user(struct perf_regs *regs_user,
                   struct pt_regs *regs)
 {
     if (user_mode(regs)) {
         regs_user->abi = perf_reg_abi(current);
         regs_user->regs = regs;
     } else if (!(current->flags & PF_KTHREAD)) {
         perf_get_regs_user(regs_user, regs);
     } else {
         regs_user->abi = PERF_SAMPLE_REGS_ABI_NONE;
         regs_user->regs = NULL;
     }
 }
 
 static void perf_sample_regs_intr(struct perf_regs *regs_intr,
                   struct pt_regs *regs)
 {
     regs_intr->regs = regs;
     regs_intr->abi  = perf_reg_abi(current);
 }
 
 
 /*
  * Get remaining task size from user stack pointer.
  *
  * It'd be better to take stack vma map and limit this more
  * precisely, but there's no way to get it safely under interrupt,
  * so using TASK_SIZE as limit.
  */
 static u64 perf_ustack_task_size(struct pt_regs *regs)
 {
     unsigned long addr = perf_user_stack_pointer(regs);
 
     if (!addr || addr >= TASK_SIZE)
         return 0;
 
     return TASK_SIZE - addr;
 }
 
 static u16
 perf_sample_ustack_size(u16 stack_size, u16 header_size,
             struct pt_regs *regs)
 {
     u64 task_size;
 
     /* No regs, no stack pointer, no dump. */
     if (!regs)
         return 0;
 
     /*
      * Check if we fit in with the requested stack size into the:
      * - TASK_SIZE
      *   If we don't, we limit the size to the TASK_SIZE.
      *
      * - remaining sample size
      *   If we don't, we customize the stack size to
      *   fit in to the remaining sample size.
      */
 
     task_size  = min((u64) USHRT_MAX, perf_ustack_task_size(regs));
     stack_size = min(stack_size, (u16) task_size);
 
     /* Current header size plus static size and dynamic size. */
     header_size += 2 * sizeof(u64);
 
     /* Do we fit in with the current stack dump size? */
     if ((u16) (header_size + stack_size) < header_size) {
         /*
          * If we overflow the maximum size for the sample,
          * we customize the stack dump size to fit in.
          */
         stack_size = USHRT_MAX - header_size - sizeof(u64);
         stack_size = round_up(stack_size, sizeof(u64));
     }
 
     return stack_size;
 }
 
 static void
 perf_output_sample_ustack(struct perf_output_handle *handle, u64 dump_size,
               struct pt_regs *regs)
 {
     /* Case of a kernel thread, nothing to dump */
     if (!regs) {
         u64 size = 0;
         perf_output_put(handle, size);
     } else {
         unsigned long sp;
         unsigned int rem;
         u64 dyn_size;
 
         /*
          * We dump:
          * static size
          *   - the size requested by user or the best one we can fit
          *     in to the sample max size
          * data
          *   - user stack dump data
          * dynamic size
          *   - the actual dumped size
          */
 
         /* Static size. */
         perf_output_put(handle, dump_size);
 
         /* Data. */
         sp = perf_user_stack_pointer(regs);
         rem = __output_copy_user(handle, (void *) sp, dump_size);
         dyn_size = dump_size - rem;
 
         perf_output_skip(handle, rem);
 
         /* Dynamic size. */
         perf_output_put(handle, dyn_size);
     }
 }
 
 static unsigned long perf_prepare_sample_aux(struct perf_event *event,
                       struct perf_sample_data *data,
                       size_t size)
 {
     struct perf_event *sampler = event->aux_event;
     struct perf_buffer *rb;
 
     data->aux_size = 0;
 
     if (!sampler)
         goto out;
 
     if (WARN_ON_ONCE(READ_ONCE(sampler->state) != PERF_EVENT_STATE_ACTIVE))
         goto out;
 
     if (WARN_ON_ONCE(READ_ONCE(sampler->oncpu) != smp_processor_id()))
         goto out;
 
     rb = ring_buffer_get(sampler);
     if (!rb)
         goto out;
 
     /*
      * If this is an NMI hit inside sampling code, don't take
      * the sample. See also perf_aux_sample_output().
      */
     if (READ_ONCE(rb->aux_in_sampling)) {
         data->aux_size = 0;
     } else {
         size = min_t(size_t, size, perf_aux_size(rb));
         data->aux_size = ALIGN(size, sizeof(u64));
     }
     ring_buffer_put(rb);
 
 out:
     return data->aux_size;
 }
 
 static long perf_pmu_snapshot_aux(struct perf_buffer *rb,
                                  struct perf_event *event,
                                  struct perf_output_handle *handle,
                                  unsigned long size)
 {
     unsigned long flags;
     long ret;
 
     /*
      * Normal ->start()/->stop() callbacks run in IRQ mode in scheduler
      * paths. If we start calling them in NMI context, they may race with
      * the IRQ ones, that is, for example, re-starting an event that's just
      * been stopped, which is why we're using a separate callback that
      * doesn't change the event state.
      *
      * IRQs need to be disabled to prevent IPIs from racing with us.
      */
     local_irq_save(flags);
     /*
      * Guard against NMI hits inside the critical section;
      * see also perf_prepare_sample_aux().
      */
     WRITE_ONCE(rb->aux_in_sampling, 1);
     barrier();
 
     ret = event->pmu->snapshot_aux(event, handle, size);
 
     barrier();
     WRITE_ONCE(rb->aux_in_sampling, 0);
     local_irq_restore(flags);
 
     return ret;
 }
 
 static void perf_aux_sample_output(struct perf_event *event,
                    struct perf_output_handle *handle,
                    struct perf_sample_data *data)
 {
     struct perf_event *sampler = event->aux_event;
     struct perf_buffer *rb;
     unsigned long pad;
     long size;
 
     if (WARN_ON_ONCE(!sampler || !data->aux_size))
         return;
 
     rb = ring_buffer_get(sampler);
     if (!rb)
         return;
 
     size = perf_pmu_snapshot_aux(rb, sampler, handle, data->aux_size);
 
     /*
      * An error here means that perf_output_copy() failed (returned a
      * non-zero surplus that it didn't copy), which in its current
      * enlightened implementation is not possible. If that changes, we'd
      * like to know.
      */
     if (WARN_ON_ONCE(size < 0))
         goto out_put;
 
     /*
      * The pad comes from ALIGN()ing data->aux_size up to u64 in
      * perf_prepare_sample_aux(), so should not be more than that.
      */
     pad = data->aux_size - size;
     if (WARN_ON_ONCE(pad >= sizeof(u64)))
         pad = 8;
 
     if (pad) {
         u64 zero = 0;
         perf_output_copy(handle, &zero, pad);
     }
 
 out_put:
     ring_buffer_put(rb);
 }
 
 static void __perf_event_header__init_id(struct perf_event_header *header,
                      struct perf_sample_data *data,
                      struct perf_event *event)
 {
     u64 sample_type = event->attr.sample_type;
 
     data->type = sample_type;
     header->size += event->id_header_size;
 
     if (sample_type & PERF_SAMPLE_TID) {
         /* namespace issues */
         data->tid_entry.pid = perf_event_pid(event, current);
         data->tid_entry.tid = perf_event_tid(event, current);
     }
 
     if (sample_type & PERF_SAMPLE_TIME)
         data->time = perf_event_clock(event);
 
     if (sample_type & (PERF_SAMPLE_ID | PERF_SAMPLE_IDENTIFIER))
         data->id = primary_event_id(event);
 
     if (sample_type & PERF_SAMPLE_STREAM_ID)
         data->stream_id = event->id;
 
     if (sample_type & PERF_SAMPLE_CPU) {
         data->cpu_entry.cpu  = raw_smp_processor_id();
         data->cpu_entry.reserved = 0;
     }
 }
 
 void perf_event_header__init_id(struct perf_event_header *header,
                 struct perf_sample_data *data,
                 struct perf_event *event)
 {
     if (event->attr.sample_id_all)
         __perf_event_header__init_id(header, data, event);
 }
 
 static void __perf_event__output_id_sample(struct perf_output_handle *handle,
                        struct perf_sample_data *data)
 {
     u64 sample_type = data->type;
 
     if (sample_type & PERF_SAMPLE_TID)
         perf_output_put(handle, data->tid_entry);
 
     if (sample_type & PERF_SAMPLE_TIME)
         perf_output_put(handle, data->time);
 
     if (sample_type & PERF_SAMPLE_ID)
         perf_output_put(handle, data->id);
 
     if (sample_type & PERF_SAMPLE_STREAM_ID)
         perf_output_put(handle, data->stream_id);
 
     if (sample_type & PERF_SAMPLE_CPU)
         perf_output_put(handle, data->cpu_entry);
 
     if (sample_type & PERF_SAMPLE_IDENTIFIER)
         perf_output_put(handle, data->id);
 }
 
 void perf_event__output_id_sample(struct perf_event *event,
                   struct perf_output_handle *handle,
                   struct perf_sample_data *sample)
 {
     if (event->attr.sample_id_all)
         __perf_event__output_id_sample(handle, sample);
 }
 
 static void perf_output_read_one(struct perf_output_handle *handle,
                  struct perf_event *event,
                  u64 enabled, u64 running)
 {
     u64 read_format = event->attr.read_format;
     u64 values[5];
     int n = 0;
 
     values[n++] = perf_event_count(event);
     if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
         values[n++] = enabled +
             atomic64_read(&event->child_total_time_enabled);
     }
     if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
         values[n++] = running +
             atomic64_read(&event->child_total_time_running);
     }
     if (read_format & PERF_FORMAT_ID)
         values[n++] = primary_event_id(event);
     if (read_format & PERF_FORMAT_LOST)
         values[n++] = atomic64_read(&event->lost_samples);
 
     __output_copy(handle, values, n * sizeof(u64));
 }
 
 static void perf_output_read_group(struct perf_output_handle *handle,
                 struct perf_event *event,
                 u64 enabled, u64 running)
 {
     struct perf_event *leader = event->group_leader, *sub;
     u64 read_format = event->attr.read_format;
     unsigned long flags;
     u64 values[6];
     int n = 0;
 
     /*
      * Disabling interrupts avoids all counter scheduling
      * (context switches, timer based rotation and IPIs).
      */
     local_irq_save(flags);
 
     values[n++] = 1 + leader->nr_siblings;
 
     if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
         values[n++] = enabled;
 
     if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
         values[n++] = running;
 
     if ((leader != event) &&
         (leader->state == PERF_EVENT_STATE_ACTIVE))
         leader->pmu->read(leader);
 
     values[n++] = perf_event_count(leader);
     if (read_format & PERF_FORMAT_ID)
         values[n++] = primary_event_id(leader);
     if (read_format & PERF_FORMAT_LOST)
         values[n++] = atomic64_read(&leader->lost_samples);
 
     __output_copy(handle, values, n * sizeof(u64));
 
     for_each_sibling_event(sub, leader) {
         n = 0;
 
         if ((sub != event) &&
             (sub->state == PERF_EVENT_STATE_ACTIVE))
             sub->pmu->read(sub);
 
         values[n++] = perf_event_count(sub);
         if (read_format & PERF_FORMAT_ID)
             values[n++] = primary_event_id(sub);
         if (read_format & PERF_FORMAT_LOST)
             values[n++] = atomic64_read(&sub->lost_samples);
 
         __output_copy(handle, values, n * sizeof(u64));
     }
 
     local_irq_restore(flags);
 }
 
 #define PERF_FORMAT_TOTAL_TIMES (PERF_FORMAT_TOTAL_TIME_ENABLED|\
                  PERF_FORMAT_TOTAL_TIME_RUNNING)
 
 /*
  * XXX PERF_SAMPLE_READ vs inherited events seems difficult.
  *
  * The problem is that its both hard and excessively expensive to iterate the
  * child list, not to mention that its impossible to IPI the children running
  * on another CPU, from interrupt/NMI context.
  */
 static void perf_output_read(struct perf_output_handle *handle,
                  struct perf_event *event)
 {
     u64 enabled = 0, running = 0, now;
     u64 read_format = event->attr.read_format;
 
     /*
      * compute total_time_enabled, total_time_running
      * based on snapshot values taken when the event
      * was last scheduled in.
      *
      * we cannot simply called update_context_time()
      * because of locking issue as we are called in
      * NMI context
      */
     if (read_format & PERF_FORMAT_TOTAL_TIMES)
         calc_timer_values(event, &now, &enabled, &running);
 
     if (event->attr.read_format & PERF_FORMAT_GROUP)
         perf_output_read_group(handle, event, enabled, running);
     else
         perf_output_read_one(handle, event, enabled, running);
 }
 
 static inline bool perf_sample_save_hw_index(struct perf_event *event)
 {
     return event->attr.branch_sample_type & PERF_SAMPLE_BRANCH_HW_INDEX;
 }
 
 void perf_output_sample(struct perf_output_handle *handle,
             struct perf_event_header *header,
             struct perf_sample_data *data,
             struct perf_event *event)
 {
     u64 sample_type = data->type;
 
     perf_output_put(handle, *header);
 
     if (sample_type & PERF_SAMPLE_IDENTIFIER)
         perf_output_put(handle, data->id);
 
     if (sample_type & PERF_SAMPLE_IP)
         perf_output_put(handle, data->ip);
 
     if (sample_type & PERF_SAMPLE_TID)
         perf_output_put(handle, data->tid_entry);
 
     if (sample_type & PERF_SAMPLE_TIME)
         perf_output_put(handle, data->time);
 
     if (sample_type & PERF_SAMPLE_ADDR)
         perf_output_put(handle, data->addr);
 
     if (sample_type & PERF_SAMPLE_ID)
         perf_output_put(handle, data->id);
 
     if (sample_type & PERF_SAMPLE_STREAM_ID)
         perf_output_put(handle, data->stream_id);
 
     if (sample_type & PERF_SAMPLE_CPU)
         perf_output_put(handle, data->cpu_entry);
 
     if (sample_type & PERF_SAMPLE_PERIOD)
         perf_output_put(handle, data->period);
 
     if (sample_type & PERF_SAMPLE_READ)
         perf_output_read(handle, event);
 
     if (sample_type & PERF_SAMPLE_CALLCHAIN) {
         int size = 1;
 
         size += data->callchain->nr;
         size *= sizeof(u64);
         __output_copy(handle, data->callchain, size);
     }
 
     if (sample_type & PERF_SAMPLE_RAW) {
         struct perf_raw_record *raw = data->raw;
 
         if (raw) {
             struct perf_raw_frag *frag = &raw->frag;
 
             perf_output_put(handle, raw->size);
             do {
                 if (frag->copy) {
                     __output_custom(handle, frag->copy,
                             frag->data, frag->size);
                 } else {
                     __output_copy(handle, frag->data,
                               frag->size);
                 }
                 if (perf_raw_frag_last(frag))
                     break;
                 frag = frag->next;
             } while (1);
             if (frag->pad)
                 __output_skip(handle, NULL, frag->pad);
         } else {
             struct {
                 u32 size;
                 u32 data;
             } raw = {
                 .size = sizeof(u32),
                 .data = 0,
             };
             perf_output_put(handle, raw);
         }
     }
 
     if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
         if (data->br_stack) {
             size_t size;
 
             size = data->br_stack->nr
                  * sizeof(struct perf_branch_entry);
 
             perf_output_put(handle, data->br_stack->nr);
             if (perf_sample_save_hw_index(event))
                 perf_output_put(handle, data->br_stack->hw_idx);
             perf_output_copy(handle, data->br_stack->entries, size);
         } else {
             /*
              * we always store at least the value of nr
              */
             u64 nr = 0;
             perf_output_put(handle, nr);
         }
     }
 
     if (sample_type & PERF_SAMPLE_REGS_USER) {
         u64 abi = data->regs_user.abi;
 
         /*
          * If there are no regs to dump, notice it through
          * first u64 being zero (PERF_SAMPLE_REGS_ABI_NONE).
          */
         perf_output_put(handle, abi);
 
         if (abi) {
             u64 mask = event->attr.sample_regs_user;
             perf_output_sample_regs(handle,
                         data->regs_user.regs,
                         mask);
         }
     }
 
     if (sample_type & PERF_SAMPLE_STACK_USER) {
         perf_output_sample_ustack(handle,
                       data->stack_user_size,
                       data->regs_user.regs);
     }
 
     if (sample_type & PERF_SAMPLE_WEIGHT_TYPE)
         perf_output_put(handle, data->weight.full);
 
     if (sample_type & PERF_SAMPLE_DATA_SRC)
         perf_output_put(handle, data->data_src.val);
 
     if (sample_type & PERF_SAMPLE_TRANSACTION)
         perf_output_put(handle, data->txn);
 
     if (sample_type & PERF_SAMPLE_REGS_INTR) {
         u64 abi = data->regs_intr.abi;
         /*
          * If there are no regs to dump, notice it through
          * first u64 being zero (PERF_SAMPLE_REGS_ABI_NONE).
          */
         perf_output_put(handle, abi);
 
         if (abi) {
             u64 mask = event->attr.sample_regs_intr;
 
             perf_output_sample_regs(handle,
                         data->regs_intr.regs,
                         mask);
         }
     }
 
     if (sample_type & PERF_SAMPLE_PHYS_ADDR)
         perf_output_put(handle, data->phys_addr);
 
     if (sample_type & PERF_SAMPLE_CGROUP)
         perf_output_put(handle, data->cgroup);
 
     if (sample_type & PERF_SAMPLE_DATA_PAGE_SIZE)
         perf_output_put(handle, data->data_page_size);
 
     if (sample_type & PERF_SAMPLE_CODE_PAGE_SIZE)
         perf_output_put(handle, data->code_page_size);
 
     if (sample_type & PERF_SAMPLE_AUX) {
         perf_output_put(handle, data->aux_size);
 
         if (data->aux_size)
             perf_aux_sample_output(event, handle, data);
     }
 
     if (!event->attr.watermark) {
         int wakeup_events = event->attr.wakeup_events;
 
         if (wakeup_events) {
             struct perf_buffer *rb = handle->rb;
             int events = local_inc_return(&rb->events);
 
             if (events >= wakeup_events) {
                 local_sub(wakeup_events, &rb->events);
                 local_inc(&rb->wakeup);
             }
         }
     }
 }
 
 static u64 perf_virt_to_phys(u64 virt)
 {
     u64 phys_addr = 0;
 
     if (!virt)
         return 0;
 
     if (virt >= TASK_SIZE) {
         /* If it's vmalloc()d memory, leave phys_addr as 0 */
         if (virt_addr_valid((void *)(uintptr_t)virt) &&
             !(virt >= VMALLOC_START && virt < VMALLOC_END))
             phys_addr = (u64)virt_to_phys((void *)(uintptr_t)virt);
     } else {
         /*
          * Walking the pages tables for user address.
          * Interrupts are disabled, so it prevents any tear down
          * of the page tables.
          * Try IRQ-safe get_user_page_fast_only first.
          * If failed, leave phys_addr as 0.
          */
         if (current->mm != NULL) {
             struct page *p;
 
             pagefault_disable();
             if (get_user_page_fast_only(virt, 0, &p)) {
                 phys_addr = page_to_phys(p) + virt % PAGE_SIZE;
                 put_page(p);
             }
             pagefault_enable();
         }
     }
 
     return phys_addr;
 }
 
 /*
  * Return the pagetable size of a given virtual address.
  */
 static u64 perf_get_pgtable_size(struct mm_struct *mm, unsigned long addr)
 {
     u64 size = 0;
 
 #ifdef CONFIG_HAVE_FAST_GUP
     pgd_t *pgdp, pgd;
     p4d_t *p4dp, p4d;
     pud_t *pudp, pud;
     pmd_t *pmdp, pmd;
     pte_t *ptep, pte;
 
     pgdp = pgd_offset(mm, addr);
     pgd = READ_ONCE(*pgdp);
     if (pgd_none(pgd))
         return 0;
 
     if (pgd_leaf(pgd))
         return pgd_leaf_size(pgd);
 
     p4dp = p4d_offset_lockless(pgdp, pgd, addr);
     p4d = READ_ONCE(*p4dp);
     if (!p4d_present(p4d))
         return 0;
 
     if (p4d_leaf(p4d))
         return p4d_leaf_size(p4d);
 
     pudp = pud_offset_lockless(p4dp, p4d, addr);
     pud = READ_ONCE(*pudp);
     if (!pud_present(pud))
         return 0;
 
     if (pud_leaf(pud))
         return pud_leaf_size(pud);
 
     pmdp = pmd_offset_lockless(pudp, pud, addr);
     pmd = READ_ONCE(*pmdp);
     if (!pmd_present(pmd))
         return 0;
 
     if (pmd_leaf(pmd))
         return pmd_leaf_size(pmd);
 
     ptep = pte_offset_map(&pmd, addr);
     pte = ptep_get_lockless(ptep);
     if (pte_present(pte))
         size = pte_leaf_size(pte);
     pte_unmap(ptep);
 #endif /* CONFIG_HAVE_FAST_GUP */
 
     return size;
 }
 
 static u64 perf_get_page_size(unsigned long addr)
 {
     struct mm_struct *mm;
     unsigned long flags;
     u64 size;
 
     if (!addr)
         return 0;
 
     /*
      * Software page-table walkers must disable IRQs,
      * which prevents any tear down of the page tables.
      */
     local_irq_save(flags);
 
     mm = current->mm;
     if (!mm) {
         /*
          * For kernel threads and the like, use init_mm so that
          * we can find kernel memory.
          */
         mm = &init_mm;
     }
 
     size = perf_get_pgtable_size(mm, addr);
 
     local_irq_restore(flags);
 
     return size;
 }
 
 static struct perf_callchain_entry __empty_callchain = { .nr = 0, };
 
 struct perf_callchain_entry *
 perf_callchain(struct perf_event *event, struct pt_regs *regs)
 {
     bool kernel = !event->attr.exclude_callchain_kernel;
     bool user   = !event->attr.exclude_callchain_user;
     /* Disallow cross-task user callchains. */
     bool crosstask = event->ctx->task && event->ctx->task != current;
     const u32 max_stack = event->attr.sample_max_stack;
     struct perf_callchain_entry *callchain;
 
     if (!kernel && !user)
         return &__empty_callchain;
 
     callchain = get_perf_callchain(regs, 0, kernel, user,
                        max_stack, crosstask, true);
     return callchain ?: &__empty_callchain;
 }
 
 void perf_prepare_sample(struct perf_event_header *header,
              struct perf_sample_data *data,
              struct perf_event *event,
              struct pt_regs *regs)
 {
     u64 sample_type = event->attr.sample_type;
 
     header->type = PERF_RECORD_SAMPLE;
     header->size = sizeof(*header) + event->header_size;
 
     header->misc = 0;
     header->misc |= perf_misc_flags(regs);
 
     __perf_event_header__init_id(header, data, event);
 
     if (sample_type & (PERF_SAMPLE_IP | PERF_SAMPLE_CODE_PAGE_SIZE))
         data->ip = perf_instruction_pointer(regs);
 
     if (sample_type & PERF_SAMPLE_CALLCHAIN) {
         int size = 1;
 
         if (!(sample_type & __PERF_SAMPLE_CALLCHAIN_EARLY))
             data->callchain = perf_callchain(event, regs);
 
         size += data->callchain->nr;
 
         header->size += size * sizeof(u64);
     }
 
     if (sample_type & PERF_SAMPLE_RAW) {
         struct perf_raw_record *raw = data->raw;
         int size;
 
         if (raw) {
             struct perf_raw_frag *frag = &raw->frag;
             u32 sum = 0;
 
             do {
                 sum += frag->size;
                 if (perf_raw_frag_last(frag))
                     break;
                 frag = frag->next;
             } while (1);
 
             size = round_up(sum + sizeof(u32), sizeof(u64));
             raw->size = size - sizeof(u32);
             frag->pad = raw->size - sum;
         } else {
             size = sizeof(u64);
         }
 
         header->size += size;
     }
 
     if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
         int size = sizeof(u64); /* nr */
         if (data->br_stack) {
             if (perf_sample_save_hw_index(event))
                 size += sizeof(u64);
 
             size += data->br_stack->nr
                   * sizeof(struct perf_branch_entry);
         }
         header->size += size;
     }
 
     if (sample_type & (PERF_SAMPLE_REGS_USER | PERF_SAMPLE_STACK_USER))
         perf_sample_regs_user(&data->regs_user, regs);
 
     if (sample_type & PERF_SAMPLE_REGS_USER) {
         /* regs dump ABI info */
         int size = sizeof(u64);
 
         if (data->regs_user.regs) {
             u64 mask = event->attr.sample_regs_user;
             size += hweight64(mask) * sizeof(u64);
         }
 
         header->size += size;
     }
 
     if (sample_type & PERF_SAMPLE_STACK_USER) {
         /*
          * Either we need PERF_SAMPLE_STACK_USER bit to be always
          * processed as the last one or have additional check added
          * in case new sample type is added, because we could eat
          * up the rest of the sample size.
          */
         u16 stack_size = event->attr.sample_stack_user;
         u16 size = sizeof(u64);
 
         stack_size = perf_sample_ustack_size(stack_size, header->size,
                              data->regs_user.regs);
 
         /*
          * If there is something to dump, add space for the dump
          * itself and for the field that tells the dynamic size,
          * which is how many have been actually dumped.
          */
         if (stack_size)
             size += sizeof(u64) + stack_size;
 
         data->stack_user_size = stack_size;
         header->size += size;
     }
 
     if (sample_type & PERF_SAMPLE_REGS_INTR) {
         /* regs dump ABI info */
         int size = sizeof(u64);
 
         perf_sample_regs_intr(&data->regs_intr, regs);
 
         if (data->regs_intr.regs) {
             u64 mask = event->attr.sample_regs_intr;
 
             size += hweight64(mask) * sizeof(u64);
         }
 
         header->size += size;
     }
 
     if (sample_type & PERF_SAMPLE_PHYS_ADDR)
         data->phys_addr = perf_virt_to_phys(data->addr);
 
 #ifdef CONFIG_CGROUP_PERF
     if (sample_type & PERF_SAMPLE_CGROUP) {
         struct cgroup *cgrp;
 
         /* protected by RCU */
         cgrp = task_css_check(current, perf_event_cgrp_id, 1)->cgroup;
         data->cgroup = cgroup_id(cgrp);
     }
 #endif
 
     /*
      * PERF_DATA_PAGE_SIZE requires PERF_SAMPLE_ADDR. If the user doesn't
      * require PERF_SAMPLE_ADDR, kernel implicitly retrieve the data->addr,
      * but the value will not dump to the userspace.
      */
     if (sample_type & PERF_SAMPLE_DATA_PAGE_SIZE)
         data->data_page_size = perf_get_page_size(data->addr);
 
     if (sample_type & PERF_SAMPLE_CODE_PAGE_SIZE)
         data->code_page_size = perf_get_page_size(data->ip);
 
     if (sample_type & PERF_SAMPLE_AUX) {
         u64 size;
 
         header->size += sizeof(u64); /* size */
 
         /*
          * Given the 16bit nature of header::size, an AUX sample can
          * easily overflow it, what with all the preceding sample bits.
          * Make sure this doesn't happen by using up to U16_MAX bytes
          * per sample in total (rounded down to 8 byte boundary).
          */
         size = min_t(size_t, U16_MAX - header->size,
                  event->attr.aux_sample_size);
         size = rounddown(size, 8);
         size = perf_prepare_sample_aux(event, data, size);
 
         WARN_ON_ONCE(size + header->size > U16_MAX);
         header->size += size;
     }
     /*
      * If you're adding more sample types here, you likely need to do
      * something about the overflowing header::size, like repurpose the
      * lowest 3 bits of size, which should be always zero at the moment.
      * This raises a more important question, do we really need 512k sized
      * samples and why, so good argumentation is in order for whatever you
      * do here next.
      */
     WARN_ON_ONCE(header->size & 7);
 }
 
 static __always_inline int
 __perf_event_output(struct perf_event *event,
             struct perf_sample_data *data,
             struct pt_regs *regs,
             int (*output_begin)(struct perf_output_handle *,
                     struct perf_sample_data *,
                     struct perf_event *,
                     unsigned int))
 {
     struct perf_output_handle handle;
     struct perf_event_header header;
     int err;
 
     /* protect the callchain buffers */
     rcu_read_lock();
 
     perf_prepare_sample(&header, data, event, regs);
 
     err = output_begin(&handle, data, event, header.size);
     if (err)
         goto exit;
 
     perf_output_sample(&handle, &header, data, event);
 
     perf_output_end(&handle);
 
 exit:
     rcu_read_unlock();
     return err;
 }
 
 void
 perf_event_output_forward(struct perf_event *event,
              struct perf_sample_data *data,
              struct pt_regs *regs)
 {
     __perf_event_output(event, data, regs, perf_output_begin_forward);
 }
 
 void
 perf_event_output_backward(struct perf_event *event,
                struct perf_sample_data *data,
                struct pt_regs *regs)
 {
     __perf_event_output(event, data, regs, perf_output_begin_backward);
 }
 
 int
 perf_event_output(struct perf_event *event,
           struct perf_sample_data *data,
           struct pt_regs *regs)
 {
     return __perf_event_output(event, data, regs, perf_output_begin);
 }
 
 /*
  * read event_id
  */
 
 struct perf_read_event {
     struct perf_event_header    header;
 
     u32             pid;
     u32             tid;
 };
 
 static void
 perf_event_read_event(struct perf_event *event,
             struct task_struct *task)
 {
     struct perf_output_handle handle;
     struct perf_sample_data sample;
     struct perf_read_event read_event = {
         .header = {
             .type = PERF_RECORD_READ,
             .misc = 0,
             .size = sizeof(read_event) + event->read_size,
         },
         .pid = perf_event_pid(event, task),
         .tid = perf_event_tid(event, task),
     };
     int ret;
 
     perf_event_header__init_id(&read_event.header, &sample, event);
     ret = perf_output_begin(&handle, &sample, event, read_event.header.size);
     if (ret)
         return;
 
     perf_output_put(&handle, read_event);
     perf_output_read(&handle, event);
     perf_event__output_id_sample(event, &handle, &sample);
 
     perf_output_end(&handle);
 }
 
 typedef void (perf_iterate_f)(struct perf_event *event, void *data);
 
 static void
 perf_iterate_ctx(struct perf_event_context *ctx,
            perf_iterate_f output,
            void *data, bool all)
 {
     struct perf_event *event;
 
     list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
         if (!all) {
             if (event->state < PERF_EVENT_STATE_INACTIVE)
                 continue;
             if (!event_filter_match(event))
                 continue;
         }
 
         output(event, data);
     }
 }
 
 static void perf_iterate_sb_cpu(perf_iterate_f output, void *data)
 {
     struct pmu_event_list *pel = this_cpu_ptr(&pmu_sb_events);
     struct perf_event *event;
 
     list_for_each_entry_rcu(event, &pel->list, sb_list) {
         /*
          * Skip events that are not fully formed yet; ensure that
          * if we observe event->ctx, both event and ctx will be
          * complete enough. See perf_install_in_context().
          */
         if (!smp_load_acquire(&event->ctx))
             continue;
 
         if (event->state < PERF_EVENT_STATE_INACTIVE)
             continue;
         if (!event_filter_match(event))
             continue;
         output(event, data);
     }
 }
 
 /*
  * Iterate all events that need to receive side-band events.
  *
  * For new callers; ensure that account_pmu_sb_event() includes
  * your event, otherwise it might not get delivered.
  */
 static void
 perf_iterate_sb(perf_iterate_f output, void *data,
            struct perf_event_context *task_ctx)
 {
     struct perf_event_context *ctx;
     int ctxn;
 
     rcu_read_lock();
     preempt_disable();
 
     /*
      * If we have task_ctx != NULL we only notify the task context itself.
      * The task_ctx is set only for EXIT events before releasing task
      * context.
      */
     if (task_ctx) {
         perf_iterate_ctx(task_ctx, output, data, false);
         goto done;
     }
 
     perf_iterate_sb_cpu(output, data);
 
     for_each_task_context_nr(ctxn) {
         ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
         if (ctx)
             perf_iterate_ctx(ctx, output, data, false);
     }
 done:
     preempt_enable();
     rcu_read_unlock();
 }
 
 /*
  * Clear all file-based filters at exec, they'll have to be
  * re-instated when/if these objects are mmapped again.
  */
 static void perf_event_addr_filters_exec(struct perf_event *event, void *data)
 {
     struct perf_addr_filters_head *ifh = perf_event_addr_filters(event);
     struct perf_addr_filter *filter;
     unsigned int restart = 0, count = 0;
     unsigned long flags;
 
     if (!has_addr_filter(event))
         return;
 
     raw_spin_lock_irqsave(&ifh->lock, flags);
     list_for_each_entry(filter, &ifh->list, entry) {
         if (filter->path.dentry) {
             event->addr_filter_ranges[count].start = 0;
             event->addr_filter_ranges[count].size = 0;
             restart++;
         }
 
         count++;
     }
 
     if (restart)
         event->addr_filters_gen++;
     raw_spin_unlock_irqrestore(&ifh->lock, flags);
 
     if (restart)
         perf_event_stop(event, 1);
 }
 
 void perf_event_exec(void)
 {
     struct perf_event_context *ctx;
     int ctxn;
 
     for_each_task_context_nr(ctxn) {
         perf_event_enable_on_exec(ctxn);
         perf_event_remove_on_exec(ctxn);
 
         rcu_read_lock();
         ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
         if (ctx) {
             perf_iterate_ctx(ctx, perf_event_addr_filters_exec,
                      NULL, true);
         }
         rcu_read_unlock();
     }
 }
 
 struct remote_output {
     struct perf_buffer  *rb;
     int         err;
 };
 
 static void __perf_event_output_stop(struct perf_event *event, void *data)
 {
     struct perf_event *parent = event->parent;
     struct remote_output *ro = data;
     struct perf_buffer *rb = ro->rb;
     struct stop_event_data sd = {
         .event  = event,
     };
 
     if (!has_aux(event))
         return;
 
     if (!parent)
         parent = event;
 
     /*
      * In case of inheritance, it will be the parent that links to the
      * ring-buffer, but it will be the child that's actually using it.
      *
      * We are using event::rb to determine if the event should be stopped,
      * however this may race with ring_buffer_attach() (through set_output),
      * which will make us skip the event that actually needs to be stopped.
      * So ring_buffer_attach() has to stop an aux event before re-assigning
      * its rb pointer.
      */
     if (rcu_dereference(parent->rb) == rb)
         ro->err = __perf_event_stop(&sd);
 }
 
 static int __perf_pmu_output_stop(void *info)
 {
     struct perf_event *event = info;
     struct pmu *pmu = event->ctx->pmu;
     struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
     struct remote_output ro = {
         .rb = event->rb,
     };
 
     rcu_read_lock();
     perf_iterate_ctx(&cpuctx->ctx, __perf_event_output_stop, &ro, false);
     if (cpuctx->task_ctx)
         perf_iterate_ctx(cpuctx->task_ctx, __perf_event_output_stop,
                    &ro, false);
     rcu_read_unlock();
 
     return ro.err;
 }
 
 static void perf_pmu_output_stop(struct perf_event *event)
 {
     struct perf_event *iter;
     int err, cpu;
 
 restart:
     rcu_read_lock();
     list_for_each_entry_rcu(iter, &event->rb->event_list, rb_entry) {
         /*
          * For per-CPU events, we need to make sure that neither they
          * nor their children are running; for cpu==-1 events it's
          * sufficient to stop the event itself if it's active, since
          * it can't have children.
          */
         cpu = iter->cpu;
         if (cpu == -1)
             cpu = READ_ONCE(iter->oncpu);
 
         if (cpu == -1)
             continue;
 
         err = cpu_function_call(cpu, __perf_pmu_output_stop, event);
         if (err == -EAGAIN) {
             rcu_read_unlock();
             goto restart;
         }
     }
     rcu_read_unlock();
 }
 
 /*
  * task tracking -- fork/exit
  *
  * enabled by: attr.comm | attr.mmap | attr.mmap2 | attr.mmap_data | attr.task
  */
 
 struct perf_task_event {
     struct task_struct      *task;
     struct perf_event_context   *task_ctx;
 
     struct {
         struct perf_event_header    header;
 
         u32             pid;
         u32             ppid;
         u32             tid;
         u32             ptid;
         u64             time;
     } event_id;
 };
 
 static int perf_event_task_match(struct perf_event *event)
 {
     return event->attr.comm  || event->attr.mmap ||
            event->attr.mmap2 || event->attr.mmap_data ||
            event->attr.task;
 }
 
 static void perf_event_task_output(struct perf_event *event,
                    void *data)
 {
     struct perf_task_event *task_event = data;
     struct perf_output_handle handle;
     struct perf_sample_data sample;
     struct task_struct *task = task_event->task;
     int ret, size = task_event->event_id.header.size;
 
     if (!perf_event_task_match(event))
         return;
 
     perf_event_header__init_id(&task_event->event_id.header, &sample, event);
 
     ret = perf_output_begin(&handle, &sample, event,
                 task_event->event_id.header.size);
     if (ret)
         goto out;
 
     task_event->event_id.pid = perf_event_pid(event, task);
     task_event->event_id.tid = perf_event_tid(event, task);
 
     if (task_event->event_id.header.type == PERF_RECORD_EXIT) {
         task_event->event_id.ppid = perf_event_pid(event,
                             task->real_parent);
         task_event->event_id.ptid = perf_event_pid(event,
                             task->real_parent);
     } else {  /* PERF_RECORD_FORK */
         task_event->event_id.ppid = perf_event_pid(event, current);
         task_event->event_id.ptid = perf_event_tid(event, current);
     }
 
     task_event->event_id.time = perf_event_clock(event);
 
     perf_output_put(&handle, task_event->event_id);
 
     perf_event__output_id_sample(event, &handle, &sample);
 
     perf_output_end(&handle);
 out:
     task_event->event_id.header.size = size;
 }
 
 static void perf_event_task(struct task_struct *task,
                   struct perf_event_context *task_ctx,
                   int new)
 {
     struct perf_task_event task_event;
 
     if (!atomic_read(&nr_comm_events) &&
         !atomic_read(&nr_mmap_events) &&
         !atomic_read(&nr_task_events))
         return;
 
     task_event = (struct perf_task_event){
         .task     = task,
         .task_ctx = task_ctx,
         .event_id    = {
             .header = {
                 .type = new ? PERF_RECORD_FORK : PERF_RECORD_EXIT,
                 .misc = 0,
                 .size = sizeof(task_event.event_id),
             },
             /* .pid  */
             /* .ppid */
             /* .tid  */
             /* .ptid */
             /* .time */
         },
     };
 
     perf_iterate_sb(perf_event_task_output,
                &task_event,
                task_ctx);
 }
 
 void perf_event_fork(struct task_struct *task)
 {
     perf_event_task(task, NULL, 1);
     perf_event_namespaces(task);
 }
 
 /*
  * comm tracking
  */
 
 struct perf_comm_event {
     struct task_struct  *task;
     char            *comm;
     int         comm_size;
 
     struct {
         struct perf_event_header    header;
 
         u32             pid;
         u32             tid;
     } event_id;
 };
 
 static int perf_event_comm_match(struct perf_event *event)
 {
     return event->attr.comm;
 }
 
 static void perf_event_comm_output(struct perf_event *event,
                    void *data)
 {
     struct perf_comm_event *comm_event = data;
     struct perf_output_handle handle;
     struct perf_sample_data sample;
     int size = comm_event->event_id.header.size;
     int ret;
 
     if (!perf_event_comm_match(event))
         return;
 
     perf_event_header__init_id(&comm_event->event_id.header, &sample, event);
     ret = perf_output_begin(&handle, &sample, event,
                 comm_event->event_id.header.size);
 
     if (ret)
         goto out;
 
     comm_event->event_id.pid = perf_event_pid(event, comm_event->task);
     comm_event->event_id.tid = perf_event_tid(event, comm_event->task);
 
     perf_output_put(&handle, comm_event->event_id);
     __output_copy(&handle, comm_event->comm,
                    comm_event->comm_size);
 
     perf_event__output_id_sample(event, &handle, &sample);
 
     perf_output_end(&handle);
 out:
     comm_event->event_id.header.size = size;
 }
 
 static void perf_event_comm_event(struct perf_comm_event *comm_event)
 {
     char comm[TASK_COMM_LEN];
     unsigned int size;
 
     memset(comm, 0, sizeof(comm));
     strlcpy(comm, comm_event->task->comm, sizeof(comm));
     size = ALIGN(strlen(comm)+1, sizeof(u64));
 
     comm_event->comm = comm;
     comm_event->comm_size = size;
 
     comm_event->event_id.header.size = sizeof(comm_event->event_id) + size;
 
     perf_iterate_sb(perf_event_comm_output,
                comm_event,
                NULL);
 }
 
 void perf_event_comm(struct task_struct *task, bool exec)
 {
     struct perf_comm_event comm_event;
 
     if (!atomic_read(&nr_comm_events))
         return;
 
     comm_event = (struct perf_comm_event){
         .task   = task,
         /* .comm      */
         /* .comm_size */
         .event_id  = {
             .header = {
                 .type = PERF_RECORD_COMM,
                 .misc = exec ? PERF_RECORD_MISC_COMM_EXEC : 0,
                 /* .size */
             },
             /* .pid */
             /* .tid */
         },
     };
 
     perf_event_comm_event(&comm_event);
 }
 
 /*
  * namespaces tracking
  */
 
 struct perf_namespaces_event {
     struct task_struct      *task;
 
     struct {
         struct perf_event_header    header;
 
         u32             pid;
         u32             tid;
         u64             nr_namespaces;
         struct perf_ns_link_info    link_info[NR_NAMESPACES];
     } event_id;
 };
 
 static int perf_event_namespaces_match(struct perf_event *event)
 {
     return event->attr.namespaces;
 }
 
 static void perf_event_namespaces_output(struct perf_event *event,
                      void *data)
 {
     struct perf_namespaces_event *namespaces_event = data;
     struct perf_output_handle handle;
     struct perf_sample_data sample;
     u16 header_size = namespaces_event->event_id.header.size;
     int ret;
 
     if (!perf_event_namespaces_match(event))
         return;
 
     perf_event_header__init_id(&namespaces_event->event_id.header,
                    &sample, event);
     ret = perf_output_begin(&handle, &sample, event,
                 namespaces_event->event_id.header.size);
     if (ret)
         goto out;
 
     namespaces_event->event_id.pid = perf_event_pid(event,
                             namespaces_event->task);
     namespaces_event->event_id.tid = perf_event_tid(event,
                             namespaces_event->task);
 
     perf_output_put(&handle, namespaces_event->event_id);
 
     perf_event__output_id_sample(event, &handle, &sample);
 
     perf_output_end(&handle);
 out:
     namespaces_event->event_id.header.size = header_size;
 }
 
 static void perf_fill_ns_link_info(struct perf_ns_link_info *ns_link_info,
                    struct task_struct *task,
                    const struct proc_ns_operations *ns_ops)
 {
     struct path ns_path;
     struct inode *ns_inode;
     int error;
 
     error = ns_get_path(&ns_path, task, ns_ops);
     if (!error) {
         ns_inode = ns_path.dentry->d_inode;
         ns_link_info->dev = new_encode_dev(ns_inode->i_sb->s_dev);
         ns_link_info->ino = ns_inode->i_ino;
         path_put(&ns_path);
     }
 }
 
 void perf_event_namespaces(struct task_struct *task)
 {
     struct perf_namespaces_event namespaces_event;
     struct perf_ns_link_info *ns_link_info;
 
     if (!atomic_read(&nr_namespaces_events))
         return;
 
     namespaces_event = (struct perf_namespaces_event){
         .task   = task,
         .event_id  = {
             .header = {
                 .type = PERF_RECORD_NAMESPACES,
                 .misc = 0,
                 .size = sizeof(namespaces_event.event_id),
             },
             /* .pid */
             /* .tid */
             .nr_namespaces = NR_NAMESPACES,
             /* .link_info[NR_NAMESPACES] */
         },
     };
 
     ns_link_info = namespaces_event.event_id.link_info;
 
     perf_fill_ns_link_info(&ns_link_info[MNT_NS_INDEX],
                    task, &mntns_operations);
 
 #ifdef CONFIG_USER_NS
     perf_fill_ns_link_info(&ns_link_info[USER_NS_INDEX],
                    task, &userns_operations);
 #endif
 #ifdef CONFIG_NET_NS
     perf_fill_ns_link_info(&ns_link_info[NET_NS_INDEX],
                    task, &netns_operations);
 #endif
 #ifdef CONFIG_UTS_NS
     perf_fill_ns_link_info(&ns_link_info[UTS_NS_INDEX],
                    task, &utsns_operations);
 #endif
 #ifdef CONFIG_IPC_NS
     perf_fill_ns_link_info(&ns_link_info[IPC_NS_INDEX],
                    task, &ipcns_operations);
 #endif
 #ifdef CONFIG_PID_NS
     perf_fill_ns_link_info(&ns_link_info[PID_NS_INDEX],
                    task, &pidns_operations);
 #endif
 #ifdef CONFIG_CGROUPS
     perf_fill_ns_link_info(&ns_link_info[CGROUP_NS_INDEX],
                    task, &cgroupns_operations);
 #endif
 
     perf_iterate_sb(perf_event_namespaces_output,
             &namespaces_event,
             NULL);
 }
 
 /*
  * cgroup tracking
  */
 #ifdef CONFIG_CGROUP_PERF
 
 struct perf_cgroup_event {
     char                *path;
     int             path_size;
     struct {
         struct perf_event_header    header;
         u64             id;
         char                path[];
     } event_id;
 };
 
 static int perf_event_cgroup_match(struct perf_event *event)
 {
     return event->attr.cgroup;
 }
 
 static void perf_event_cgroup_output(struct perf_event *event, void *data)
 {
     struct perf_cgroup_event *cgroup_event = data;
     struct perf_output_handle handle;
     struct perf_sample_data sample;
     u16 header_size = cgroup_event->event_id.header.size;
     int ret;
 
     if (!perf_event_cgroup_match(event))
         return;
 
     perf_event_header__init_id(&cgroup_event->event_id.header,
                    &sample, event);
     ret = perf_output_begin(&handle, &sample, event,
                 cgroup_event->event_id.header.size);
     if (ret)
         goto out;
 
     perf_output_put(&handle, cgroup_event->event_id);
     __output_copy(&handle, cgroup_event->path, cgroup_event->path_size);
 
     perf_event__output_id_sample(event, &handle, &sample);
 
     perf_output_end(&handle);
 out:
     cgroup_event->event_id.header.size = header_size;
 }
 
 static void perf_event_cgroup(struct cgroup *cgrp)
 {
     struct perf_cgroup_event cgroup_event;
     char path_enomem[16] = "//enomem";
     char *pathname;
     size_t size;
 
     if (!atomic_read(&nr_cgroup_events))
         return;
 
     cgroup_event = (struct perf_cgroup_event){
         .event_id  = {
             .header = {
                 .type = PERF_RECORD_CGROUP,
                 .misc = 0,
                 .size = sizeof(cgroup_event.event_id),
             },
             .id = cgroup_id(cgrp),
         },
     };
 
     pathname = kmalloc(PATH_MAX, GFP_KERNEL);
     if (pathname == NULL) {
         cgroup_event.path = path_enomem;
     } else {
         /* just to be sure to have enough space for alignment */
         cgroup_path(cgrp, pathname, PATH_MAX - sizeof(u64));
         cgroup_event.path = pathname;
     }
 
     /*
      * Since our buffer works in 8 byte units we need to align our string
      * size to a multiple of 8. However, we must guarantee the tail end is
      * zero'd out to avoid leaking random bits to userspace.
      */
     size = strlen(cgroup_event.path) + 1;
     while (!IS_ALIGNED(size, sizeof(u64)))
         cgroup_event.path[size++] = '\0';
 
     cgroup_event.event_id.header.size += size;
     cgroup_event.path_size = size;
 
     perf_iterate_sb(perf_event_cgroup_output,
             &cgroup_event,
             NULL);
 
     kfree(pathname);
 }
 
 #endif
 
 /*
  * mmap tracking
  */
 
 struct perf_mmap_event {
     struct vm_area_struct   *vma;
 
     const char      *file_name;
     int         file_size;
     int         maj, min;
     u64         ino;
     u64         ino_generation;
     u32         prot, flags;
     u8          build_id[BUILD_ID_SIZE_MAX];
     u32         build_id_size;
 
     struct {
         struct perf_event_header    header;
 
         u32             pid;
         u32             tid;
         u64             start;
         u64             len;
         u64             pgoff;
     } event_id;
 };
 
 static int perf_event_mmap_match(struct perf_event *event,
                  void *data)
 {
     struct perf_mmap_event *mmap_event = data;
     struct vm_area_struct *vma = mmap_event->vma;
     int executable = vma->vm_flags & VM_EXEC;
 
     return (!executable && event->attr.mmap_data) ||
            (executable && (event->attr.mmap || event->attr.mmap2));
 }
 
 static void perf_event_mmap_output(struct perf_event *event,
                    void *data)
 {
     struct perf_mmap_event *mmap_event = data;
     struct perf_output_handle handle;
     struct perf_sample_data sample;
     int size = mmap_event->event_id.header.size;
     u32 type = mmap_event->event_id.header.type;
     bool use_build_id;
     int ret;
 
     if (!perf_event_mmap_match(event, data))
         return;
 
     if (event->attr.mmap2) {
         mmap_event->event_id.header.type = PERF_RECORD_MMAP2;
         mmap_event->event_id.header.size += sizeof(mmap_event->maj);
         mmap_event->event_id.header.size += sizeof(mmap_event->min);
         mmap_event->event_id.header.size += sizeof(mmap_event->ino);
         mmap_event->event_id.header.size += sizeof(mmap_event->ino_generation);
         mmap_event->event_id.header.size += sizeof(mmap_event->prot);
         mmap_event->event_id.header.size += sizeof(mmap_event->flags);
     }
 
     perf_event_header__init_id(&mmap_event->event_id.header, &sample, event);
     ret = perf_output_begin(&handle, &sample, event,
                 mmap_event->event_id.header.size);
     if (ret)
         goto out;
 
     mmap_event->event_id.pid = perf_event_pid(event, current);
     mmap_event->event_id.tid = perf_event_tid(event, current);
 
     use_build_id = event->attr.build_id && mmap_event->build_id_size;
 
     if (event->attr.mmap2 && use_build_id)
         mmap_event->event_id.header.misc |= PERF_RECORD_MISC_MMAP_BUILD_ID;
 
     perf_output_put(&handle, mmap_event->event_id);
 
     if (event->attr.mmap2) {
         if (use_build_id) {
             u8 size[4] = { (u8) mmap_event->build_id_size, 0, 0, 0 };
 
             __output_copy(&handle, size, 4);
             __output_copy(&handle, mmap_event->build_id, BUILD_ID_SIZE_MAX);
         } else {
             perf_output_put(&handle, mmap_event->maj);
             perf_output_put(&handle, mmap_event->min);
             perf_output_put(&handle, mmap_event->ino);
             perf_output_put(&handle, mmap_event->ino_generation);
         }
         perf_output_put(&handle, mmap_event->prot);
         perf_output_put(&handle, mmap_event->flags);
     }
 
     __output_copy(&handle, mmap_event->file_name,
                    mmap_event->file_size);
 
     perf_event__output_id_sample(event, &handle, &sample);
 
     perf_output_end(&handle);
 out:
     mmap_event->event_id.header.size = size;
     mmap_event->event_id.header.type = type;
 }
 
 static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
 {
     struct vm_area_struct *vma = mmap_event->vma;
     struct file *file = vma->vm_file;
     int maj = 0, min = 0;
     u64 ino = 0, gen = 0;
     u32 prot = 0, flags = 0;
     unsigned int size;
     char tmp[16];
     char *buf = NULL;
     char *name;
 
     if (vma->vm_flags & VM_READ)
         prot |= PROT_READ;
     if (vma->vm_flags & VM_WRITE)
         prot |= PROT_WRITE;
     if (vma->vm_flags & VM_EXEC)
         prot |= PROT_EXEC;
 
     if (vma->vm_flags & VM_MAYSHARE)
         flags = MAP_SHARED;
     else
         flags = MAP_PRIVATE;
 
     if (vma->vm_flags & VM_LOCKED)
         flags |= MAP_LOCKED;
     if (is_vm_hugetlb_page(vma))
         flags |= MAP_HUGETLB;
 
     if (file) {
         struct inode *inode;
         dev_t dev;
 
         buf = kmalloc(PATH_MAX, GFP_KERNEL);
         if (!buf) {
             name = "//enomem";
             goto cpy_name;
         }
         /*
          * d_path() works from the end of the rb backwards, so we
          * need to add enough zero bytes after the string to handle
          * the 64bit alignment we do later.
          */
         name = file_path(file, buf, PATH_MAX - sizeof(u64));
         if (IS_ERR(name)) {
             name = "//toolong";
             goto cpy_name;
         }
         inode = file_inode(vma->vm_file);
         dev = inode->i_sb->s_dev;
         ino = inode->i_ino;
         gen = inode->i_generation;
         maj = MAJOR(dev);
         min = MINOR(dev);
 
         goto got_name;
     } else {
         if (vma->vm_ops && vma->vm_ops->name) {
             name = (char *) vma->vm_ops->name(vma);
             if (name)
                 goto cpy_name;
         }
 
         name = (char *)arch_vma_name(vma);
         if (name)
             goto cpy_name;
 
         if (vma->vm_start <= vma->vm_mm->start_brk &&
                 vma->vm_end >= vma->vm_mm->brk) {
             name = "[heap]";
             goto cpy_name;
         }
         if (vma->vm_start <= vma->vm_mm->start_stack &&
                 vma->vm_end >= vma->vm_mm->start_stack) {
             name = "[stack]";
             goto cpy_name;
         }
 
         name = "//anon";
         goto cpy_name;
     }
 
 cpy_name:
     strlcpy(tmp, name, sizeof(tmp));
     name = tmp;
 got_name:
     /*
      * Since our buffer works in 8 byte units we need to align our string
      * size to a multiple of 8. However, we must guarantee the tail end is
      * zero'd out to avoid leaking random bits to userspace.
      */
     size = strlen(name)+1;
     while (!IS_ALIGNED(size, sizeof(u64)))
         name[size++] = '\0';
 
     mmap_event->file_name = name;
     mmap_event->file_size = size;
     mmap_event->maj = maj;
     mmap_event->min = min;
     mmap_event->ino = ino;
     mmap_event->ino_generation = gen;
     mmap_event->prot = prot;
     mmap_event->flags = flags;
 
     if (!(vma->vm_flags & VM_EXEC))
         mmap_event->event_id.header.misc |= PERF_RECORD_MISC_MMAP_DATA;
 
     mmap_event->event_id.header.size = sizeof(mmap_event->event_id) + size;
 
     if (atomic_read(&nr_build_id_events))
         build_id_parse(vma, mmap_event->build_id, &mmap_event->build_id_size);
 
     perf_iterate_sb(perf_event_mmap_output,
                mmap_event,
                NULL);
 
     kfree(buf);
 }
 
 /*
  * Check whether inode and address range match filter criteria.
  */
 static bool perf_addr_filter_match(struct perf_addr_filter *filter,
                      struct file *file, unsigned long offset,
                      unsigned long size)
 {
     /* d_inode(NULL) won't be equal to any mapped user-space file */
     if (!filter->path.dentry)
         return false;
 
     if (d_inode(filter->path.dentry) != file_inode(file))
         return false;
 
     if (filter->offset > offset + size)
         return false;
 
     if (filter->offset + filter->size < offset)
         return false;
 
     return true;
 }
 
 static bool perf_addr_filter_vma_adjust(struct perf_addr_filter *filter,
                     struct vm_area_struct *vma,
                     struct perf_addr_filter_range *fr)
 {
     unsigned long vma_size = vma->vm_end - vma->vm_start;
     unsigned long off = vma->vm_pgoff << PAGE_SHIFT;
     struct file *file = vma->vm_file;
 
     if (!perf_addr_filter_match(filter, file, off, vma_size))
         return false;
 
     if (filter->offset < off) {
         fr->start = vma->vm_start;
         fr->size = min(vma_size, filter->size - (off - filter->offset));
     } else {
         fr->start = vma->vm_start + filter->offset - off;
         fr->size = min(vma->vm_end - fr->start, filter->size);
     }
 
     return true;
 }
 
 static void __perf_addr_filters_adjust(struct perf_event *event, void *data)
 {
     struct perf_addr_filters_head *ifh = perf_event_addr_filters(event);
     struct vm_area_struct *vma = data;
     struct perf_addr_filter *filter;
     unsigned int restart = 0, count = 0;
     unsigned long flags;
 
     if (!has_addr_filter(event))
         return;
 
     if (!vma->vm_file)
         return;
 
     raw_spin_lock_irqsave(&ifh->lock, flags);
     list_for_each_entry(filter, &ifh->list, entry) {
         if (perf_addr_filter_vma_adjust(filter, vma,
                         &event->addr_filter_ranges[count]))
             restart++;
 
         count++;
     }
 
     if (restart)
         event->addr_filters_gen++;
     raw_spin_unlock_irqrestore(&ifh->lock, flags);
 
     if (restart)
         perf_event_stop(event, 1);
 }
 
 /*
  * Adjust all task's events' filters to the new vma
  */
 static void perf_addr_filters_adjust(struct vm_area_struct *vma)
 {
     struct perf_event_context *ctx;
     int ctxn;
 
     /*
      * Data tracing isn't supported yet and as such there is no need
      * to keep track of anything that isn't related to executable code:
      */
     if (!(vma->vm_flags & VM_EXEC))
         return;
 
     rcu_read_lock();
     for_each_task_context_nr(ctxn) {
         ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
         if (!ctx)
             continue;
 
         perf_iterate_ctx(ctx, __perf_addr_filters_adjust, vma, true);
     }
     rcu_read_unlock();
 }
 
 void perf_event_mmap(struct vm_area_struct *vma)
 {
     struct perf_mmap_event mmap_event;
 
     if (!atomic_read(&nr_mmap_events))
         return;
 
     mmap_event = (struct perf_mmap_event){
         .vma    = vma,
         /* .file_name */
         /* .file_size */
         .event_id  = {
             .header = {
                 .type = PERF_RECORD_MMAP,
                 .misc = PERF_RECORD_MISC_USER,
                 /* .size */
             },
             /* .pid */
             /* .tid */
             .start  = vma->vm_start,
             .len    = vma->vm_end - vma->vm_start,
             .pgoff  = (u64)vma->vm_pgoff << PAGE_SHIFT,
         },
         /* .maj (attr_mmap2 only) */
         /* .min (attr_mmap2 only) */
         /* .ino (attr_mmap2 only) */
         /* .ino_generation (attr_mmap2 only) */
         /* .prot (attr_mmap2 only) */
         /* .flags (attr_mmap2 only) */
     };
 
     perf_addr_filters_adjust(vma);
     perf_event_mmap_event(&mmap_event);
 }
 
 void perf_event_aux_event(struct perf_event *event, unsigned long head,
               unsigned long size, u64 flags)
 {
     struct perf_output_handle handle;
     struct perf_sample_data sample;
     struct perf_aux_event {
         struct perf_event_header    header;
         u64             offset;
         u64             size;
         u64             flags;
     } rec = {
         .header = {
             .type = PERF_RECORD_AUX,
             .misc = 0,
             .size = sizeof(rec),
         },
         .offset     = head,
         .size       = size,
         .flags      = flags,
     };
     int ret;
 
     perf_event_header__init_id(&rec.header, &sample, event);
     ret = perf_output_begin(&handle, &sample, event, rec.header.size);
 
     if (ret)
         return;
 
     perf_output_put(&handle, rec);
     perf_event__output_id_sample(event, &handle, &sample);
 
     perf_output_end(&handle);
 }
 
 /*
  * Lost/dropped samples logging
  */
 void perf_log_lost_samples(struct perf_event *event, u64 lost)
 {
     struct perf_output_handle handle;
     struct perf_sample_data sample;
     int ret;
 
     struct {
         struct perf_event_header    header;
         u64             lost;
     } lost_samples_event = {
         .header = {
             .type = PERF_RECORD_LOST_SAMPLES,
             .misc = 0,
             .size = sizeof(lost_samples_event),
         },
         .lost       = lost,
     };
 
     perf_event_header__init_id(&lost_samples_event.header, &sample, event);
 
     ret = perf_output_begin(&handle, &sample, event,
                 lost_samples_event.header.size);
     if (ret)
         return;
 
     perf_output_put(&handle, lost_samples_event);
     perf_event__output_id_sample(event, &handle, &sample);
     perf_output_end(&handle);
 }
 
 /*
  * context_switch tracking
  */
 
 struct perf_switch_event {
     struct task_struct  *task;
     struct task_struct  *next_prev;
 
     struct {
         struct perf_event_header    header;
         u32             next_prev_pid;
         u32             next_prev_tid;
     } event_id;
 };
 
 static int perf_event_switch_match(struct perf_event *event)
 {
     return event->attr.context_switch;
 }
 
 static void perf_event_switch_output(struct perf_event *event, void *data)
 {
     struct perf_switch_event *se = data;
     struct perf_output_handle handle;
     struct perf_sample_data sample;
     int ret;
 
     if (!perf_event_switch_match(event))
         return;
 
     /* Only CPU-wide events are allowed to see next/prev pid/tid */
     if (event->ctx->task) {
         se->event_id.header.type = PERF_RECORD_SWITCH;
         se->event_id.header.size = sizeof(se->event_id.header);
     } else {
         se->event_id.header.type = PERF_RECORD_SWITCH_CPU_WIDE;
         se->event_id.header.size = sizeof(se->event_id);
         se->event_id.next_prev_pid =
                     perf_event_pid(event, se->next_prev);
         se->event_id.next_prev_tid =
                     perf_event_tid(event, se->next_prev);
     }
 
     perf_event_header__init_id(&se->event_id.header, &sample, event);
 
     ret = perf_output_begin(&handle, &sample, event, se->event_id.header.size);
     if (ret)
         return;
 
     if (event->ctx->task)
         perf_output_put(&handle, se->event_id.header);
     else
         perf_output_put(&handle, se->event_id);
 
     perf_event__output_id_sample(event, &handle, &sample);
 
     perf_output_end(&handle);
 }
 
 static void perf_event_switch(struct task_struct *task,
                   struct task_struct *next_prev, bool sched_in)
 {
     struct perf_switch_event switch_event;
 
     /* N.B. caller checks nr_switch_events != 0 */
 
     switch_event = (struct perf_switch_event){
         .task       = task,
         .next_prev  = next_prev,
         .event_id   = {
             .header = {
                 /* .type */
                 .misc = sched_in ? 0 : PERF_RECORD_MISC_SWITCH_OUT,
                 /* .size */
             },
             /* .next_prev_pid */
             /* .next_prev_tid */
         },
     };
 
     if (!sched_in && task->on_rq) {
         switch_event.event_id.header.misc |=
                 PERF_RECORD_MISC_SWITCH_OUT_PREEMPT;
     }
 
     perf_iterate_sb(perf_event_switch_output, &switch_event, NULL);
 }
 
 /*
  * IRQ throttle logging
  */
 
 static void perf_log_throttle(struct perf_event *event, int enable)
 {
     struct perf_output_handle handle;
     struct perf_sample_data sample;
     int ret;
 
     struct {
         struct perf_event_header    header;
         u64             time;
         u64             id;
         u64             stream_id;
     } throttle_event = {
         .header = {
             .type = PERF_RECORD_THROTTLE,
             .misc = 0,
             .size = sizeof(throttle_event),
         },
         .time       = perf_event_clock(event),
         .id     = primary_event_id(event),
         .stream_id  = event->id,
     };
 
     if (enable)
         throttle_event.header.type = PERF_RECORD_UNTHROTTLE;
 
     perf_event_header__init_id(&throttle_event.header, &sample, event);
 
     ret = perf_output_begin(&handle, &sample, event,
                 throttle_event.header.size);
     if (ret)
         return;
 
     perf_output_put(&handle, throttle_event);
     perf_event__output_id_sample(event, &handle, &sample);
     perf_output_end(&handle);
 }
 
 /*
  * ksymbol register/unregister tracking
  */
 
 struct perf_ksymbol_event {
     const char  *name;
     int     name_len;
     struct {
         struct perf_event_header        header;
         u64             addr;
         u32             len;
         u16             ksym_type;
         u16             flags;
     } event_id;
 };
 
 static int perf_event_ksymbol_match(struct perf_event *event)
 {
     return event->attr.ksymbol;
 }
 
 static void perf_event_ksymbol_output(struct perf_event *event, void *data)
 {
     struct perf_ksymbol_event *ksymbol_event = data;
     struct perf_output_handle handle;
     struct perf_sample_data sample;
     int ret;
 
     if (!perf_event_ksymbol_match(event))
         return;
 
     perf_event_header__init_id(&ksymbol_event->event_id.header,
                    &sample, event);
     ret = perf_output_begin(&handle, &sample, event,
                 ksymbol_event->event_id.header.size);
     if (ret)
         return;
 
     perf_output_put(&handle, ksymbol_event->event_id);
     __output_copy(&handle, ksymbol_event->name, ksymbol_event->name_len);
     perf_event__output_id_sample(event, &handle, &sample);
 
     perf_output_end(&handle);
 }
 
 void perf_event_ksymbol(u16 ksym_type, u64 addr, u32 len, bool unregister,
             const char *sym)
 {
     struct perf_ksymbol_event ksymbol_event;
     char name[KSYM_NAME_LEN];
     u16 flags = 0;
     int name_len;
 
     if (!atomic_read(&nr_ksymbol_events))
         return;
 
     if (ksym_type >= PERF_RECORD_KSYMBOL_TYPE_MAX ||
         ksym_type == PERF_RECORD_KSYMBOL_TYPE_UNKNOWN)
         goto err;
 
     strlcpy(name, sym, KSYM_NAME_LEN);
     name_len = strlen(name) + 1;
     while (!IS_ALIGNED(name_len, sizeof(u64)))
         name[name_len++] = '\0';
     BUILD_BUG_ON(KSYM_NAME_LEN % sizeof(u64));
 
     if (unregister)
         flags |= PERF_RECORD_KSYMBOL_FLAGS_UNREGISTER;
 
     ksymbol_event = (struct perf_ksymbol_event){
         .name = name,
         .name_len = name_len,
         .event_id = {
             .header = {
                 .type = PERF_RECORD_KSYMBOL,
                 .size = sizeof(ksymbol_event.event_id) +
                     name_len,
             },
             .addr = addr,
             .len = len,
             .ksym_type = ksym_type,
             .flags = flags,
         },
     };
 
     perf_iterate_sb(perf_event_ksymbol_output, &ksymbol_event, NULL);
     return;
 err:
     WARN_ONCE(1, "%s: Invalid KSYMBOL type 0x%x\n", __func__, ksym_type);
 }
 
 /*
  * bpf program load/unload tracking
  */
 
 struct perf_bpf_event {
     struct bpf_prog *prog;
     struct {
         struct perf_event_header        header;
         u16             type;
         u16             flags;
         u32             id;
         u8              tag[BPF_TAG_SIZE];
     } event_id;
 };
 
 static int perf_event_bpf_match(struct perf_event *event)
 {
     return event->attr.bpf_event;
 }
 
 static void perf_event_bpf_output(struct perf_event *event, void *data)
 {
     struct perf_bpf_event *bpf_event = data;
     struct perf_output_handle handle;
     struct perf_sample_data sample;
     int ret;
 
     if (!perf_event_bpf_match(event))
         return;
 
     perf_event_header__init_id(&bpf_event->event_id.header,
                    &sample, event);
     ret = perf_output_begin(&handle, data, event,
                 bpf_event->event_id.header.size);
     if (ret)
         return;
 
     perf_output_put(&handle, bpf_event->event_id);
     perf_event__output_id_sample(event, &handle, &sample);
 
     perf_output_end(&handle);
 }
 
 static void perf_event_bpf_emit_ksymbols(struct bpf_prog *prog,
                      enum perf_bpf_event_type type)
 {
     bool unregister = type == PERF_BPF_EVENT_PROG_UNLOAD;
     int i;
 
     if (prog->aux->func_cnt == 0) {
         perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF,
                    (u64)(unsigned long)prog->bpf_func,
                    prog->jited_len, unregister,
                    prog->aux->ksym.name);
     } else {
         for (i = 0; i < prog->aux->func_cnt; i++) {
             struct bpf_prog *subprog = prog->aux->func[i];
 
             perf_event_ksymbol(
                 PERF_RECORD_KSYMBOL_TYPE_BPF,
                 (u64)(unsigned long)subprog->bpf_func,
                 subprog->jited_len, unregister,
                 prog->aux->ksym.name);
         }
     }
 }
 
 void perf_event_bpf_event(struct bpf_prog *prog,
               enum perf_bpf_event_type type,
               u16 flags)
 {
     struct perf_bpf_event bpf_event;
 
     if (type <= PERF_BPF_EVENT_UNKNOWN ||
         type >= PERF_BPF_EVENT_MAX)
         return;
 
     switch (type) {
     case PERF_BPF_EVENT_PROG_LOAD:
     case PERF_BPF_EVENT_PROG_UNLOAD:
         if (atomic_read(&nr_ksymbol_events))
             perf_event_bpf_emit_ksymbols(prog, type);
         break;
     default:
         break;
     }
 
     if (!atomic_read(&nr_bpf_events))
         return;
 
     bpf_event = (struct perf_bpf_event){
         .prog = prog,
         .event_id = {
             .header = {
                 .type = PERF_RECORD_BPF_EVENT,
                 .size = sizeof(bpf_event.event_id),
             },
             .type = type,
             .flags = flags,
             .id = prog->aux->id,
         },
     };
 
     BUILD_BUG_ON(BPF_TAG_SIZE % sizeof(u64));
 
     memcpy(bpf_event.event_id.tag, prog->tag, BPF_TAG_SIZE);
     perf_iterate_sb(perf_event_bpf_output, &bpf_event, NULL);
 }
 
 struct perf_text_poke_event {
     const void      *old_bytes;
     const void      *new_bytes;
     size_t          pad;
     u16         old_len;
     u16         new_len;
 
     struct {
         struct perf_event_header    header;
 
         u64             addr;
     } event_id;
 };
 
 static int perf_event_text_poke_match(struct perf_event *event)
 {
     return event->attr.text_poke;
 }
 
 static void perf_event_text_poke_output(struct perf_event *event, void *data)
 {
     struct perf_text_poke_event *text_poke_event = data;
     struct perf_output_handle handle;
     struct perf_sample_data sample;
     u64 padding = 0;
     int ret;
 
     if (!perf_event_text_poke_match(event))
         return;
 
     perf_event_header__init_id(&text_poke_event->event_id.header, &sample, event);
 
     ret = perf_output_begin(&handle, &sample, event,
                 text_poke_event->event_id.header.size);
     if (ret)
         return;
 
     perf_output_put(&handle, text_poke_event->event_id);
     perf_output_put(&handle, text_poke_event->old_len);
     perf_output_put(&handle, text_poke_event->new_len);
 
     __output_copy(&handle, text_poke_event->old_bytes, text_poke_event->old_len);
     __output_copy(&handle, text_poke_event->new_bytes, text_poke_event->new_len);
 
     if (text_poke_event->pad)
         __output_copy(&handle, &padding, text_poke_event->pad);
 
     perf_event__output_id_sample(event, &handle, &sample);
 
     perf_output_end(&handle);
 }
 
 void perf_event_text_poke(const void *addr, const void *old_bytes,
               size_t old_len, const void *new_bytes, size_t new_len)
 {
     struct perf_text_poke_event text_poke_event;
     size_t tot, pad;
 
     if (!atomic_read(&nr_text_poke_events))
         return;
 
     tot  = sizeof(text_poke_event.old_len) + old_len;
     tot += sizeof(text_poke_event.new_len) + new_len;
     pad  = ALIGN(tot, sizeof(u64)) - tot;
 
     text_poke_event = (struct perf_text_poke_event){
         .old_bytes    = old_bytes,
         .new_bytes    = new_bytes,
         .pad          = pad,
         .old_len      = old_len,
         .new_len      = new_len,
         .event_id  = {
             .header = {
                 .type = PERF_RECORD_TEXT_POKE,
                 .misc = PERF_RECORD_MISC_KERNEL,
                 .size = sizeof(text_poke_event.event_id) + tot + pad,
             },
             .addr = (unsigned long)addr,
         },
     };
 
     perf_iterate_sb(perf_event_text_poke_output, &text_poke_event, NULL);
 }
 
 void perf_event_itrace_started(struct perf_event *event)
 {
     event->attach_state |= PERF_ATTACH_ITRACE;
 }
 
 static void perf_log_itrace_start(struct perf_event *event)
 {
     struct perf_output_handle handle;
     struct perf_sample_data sample;
     struct perf_aux_event {
         struct perf_event_header        header;
         u32             pid;
         u32             tid;
     } rec;
     int ret;
 
     if (event->parent)
         event = event->parent;
 
     if (!(event->pmu->capabilities & PERF_PMU_CAP_ITRACE) ||
         event->attach_state & PERF_ATTACH_ITRACE)
         return;
 
     rec.header.type = PERF_RECORD_ITRACE_START;
     rec.header.misc = 0;
     rec.header.size = sizeof(rec);
     rec.pid = perf_event_pid(event, current);
     rec.tid = perf_event_tid(event, current);
 
     perf_event_header__init_id(&rec.header, &sample, event);
     ret = perf_output_begin(&handle, &sample, event, rec.header.size);
 
     if (ret)
         return;
 
     perf_output_put(&handle, rec);
     perf_event__output_id_sample(event, &handle, &sample);
 
     perf_output_end(&handle);
 }
 
 void perf_report_aux_output_id(struct perf_event *event, u64 hw_id)
 {
     struct perf_output_handle handle;
     struct perf_sample_data sample;
     struct perf_aux_event {
         struct perf_event_header        header;
         u64             hw_id;
     } rec;
     int ret;
 
     if (event->parent)
         event = event->parent;
 
     rec.header.type = PERF_RECORD_AUX_OUTPUT_HW_ID;
     rec.header.misc = 0;
     rec.header.size = sizeof(rec);
     rec.hw_id   = hw_id;
 
     perf_event_header__init_id(&rec.header, &sample, event);
     ret = perf_output_begin(&handle, &sample, event, rec.header.size);
 
     if (ret)
         return;
 
     perf_output_put(&handle, rec);
     perf_event__output_id_sample(event, &handle, &sample);
 
     perf_output_end(&handle);
 }
 
 static int
 __perf_event_account_interrupt(struct perf_event *event, int throttle)
 {
     struct hw_perf_event *hwc = &event->hw;
     int ret = 0;
     u64 seq;
 
     seq = __this_cpu_read(perf_throttled_seq);
     if (seq != hwc->interrupts_seq) {
         hwc->interrupts_seq = seq;
         hwc->interrupts = 1;
     } else {
         hwc->interrupts++;
         if (unlikely(throttle
                  && hwc->interrupts >= max_samples_per_tick)) {
             __this_cpu_inc(perf_throttled_count);
             tick_dep_set_cpu(smp_processor_id(), TICK_DEP_BIT_PERF_EVENTS);
             hwc->interrupts = MAX_INTERRUPTS;
             perf_log_throttle(event, 0);
             ret = 1;
         }
     }
 
     if (event->attr.freq) {
         u64 now = perf_clock();
         s64 delta = now - hwc->freq_time_stamp;
 
         hwc->freq_time_stamp = now;
 
         if (delta > 0 && delta < 2*TICK_NSEC)
             perf_adjust_period(event, delta, hwc->last_period, true);
     }
 
     return ret;
 }
 
 int perf_event_account_interrupt(struct perf_event *event)
 {
     return __perf_event_account_interrupt(event, 1);
 }
 
 /*
  * Generic event overflow handling, sampling.
  */
 
 static int __perf_event_overflow(struct perf_event *event,
                    int throttle, struct perf_sample_data *data,
                    struct pt_regs *regs)
 {
     int events = atomic_read(&event->event_limit);
     int ret = 0;
 
     /*
      * Non-sampling counters might still use the PMI to fold short
      * hardware counters, ignore those.
      */
     if (unlikely(!is_sampling_event(event)))
         return 0;
 
     ret = __perf_event_account_interrupt(event, throttle);
 
     /*
      * XXX event_limit might not quite work as expected on inherited
      * events
      */
 
     event->pending_kill = POLL_IN;
     if (events && atomic_dec_and_test(&event->event_limit)) {
         ret = 1;
         event->pending_kill = POLL_HUP;
         event->pending_addr = data->addr;
 
         perf_event_disable_inatomic(event);
     }
 
     READ_ONCE(event->overflow_handler)(event, data, regs);
 
     if (*perf_event_fasync(event) && event->pending_kill) {
         event->pending_wakeup = 1;
         irq_work_queue(&event->pending);
     }
 
     return ret;
 }
 
 int perf_event_overflow(struct perf_event *event,
               struct perf_sample_data *data,
               struct pt_regs *regs)
 {
     return __perf_event_overflow(event, 1, data, regs);
 }
 
 /*
  * Generic software event infrastructure
  */
 
 struct swevent_htable {
     struct swevent_hlist        *swevent_hlist;
     struct mutex            hlist_mutex;
     int             hlist_refcount;
 
     /* Recursion avoidance in each contexts */
     int             recursion[PERF_NR_CONTEXTS];
 };
 
 static DEFINE_PER_CPU(struct swevent_htable, swevent_htable);
 
 /*
  * We directly increment event->count and keep a second value in
  * event->hw.period_left to count intervals. This period event
  * is kept in the range [-sample_period, 0] so that we can use the
  * sign as trigger.
  */
 
 u64 perf_swevent_set_period(struct perf_event *event)
 {
     struct hw_perf_event *hwc = &event->hw;
     u64 period = hwc->last_period;
     u64 nr, offset;
     s64 old, val;
 
     hwc->last_period = hwc->sample_period;
 
 again:
     old = val = local64_read(&hwc->period_left);
     if (val < 0)
         return 0;
 
     nr = div64_u64(period + val, period);
     offset = nr * period;
     val -= offset;
     if (local64_cmpxchg(&hwc->period_left, old, val) != old)
         goto again;
 
     return nr;
 }
 
 static void perf_swevent_overflow(struct perf_event *event, u64 overflow,
                     struct perf_sample_data *data,
                     struct pt_regs *regs)
 {
     struct hw_perf_event *hwc = &event->hw;
     int throttle = 0;
 
     if (!overflow)
         overflow = perf_swevent_set_period(event);
 
     if (hwc->interrupts == MAX_INTERRUPTS)
         return;
 
     for (; overflow; overflow--) {
         if (__perf_event_overflow(event, throttle,
                         data, regs)) {
             /*
              * We inhibit the overflow from happening when
              * hwc->interrupts == MAX_INTERRUPTS.
              */
             break;
         }
         throttle = 1;
     }
 }
 
 static void perf_swevent_event(struct perf_event *event, u64 nr,
                    struct perf_sample_data *data,
                    struct pt_regs *regs)
 {
     struct hw_perf_event *hwc = &event->hw;
 
     local64_add(nr, &event->count);
 
     if (!regs)
         return;
 
     if (!is_sampling_event(event))
         return;
 
     if ((event->attr.sample_type & PERF_SAMPLE_PERIOD) && !event->attr.freq) {
         data->period = nr;
         return perf_swevent_overflow(event, 1, data, regs);
     } else
         data->period = event->hw.last_period;
 
     if (nr == 1 && hwc->sample_period == 1 && !event->attr.freq)
         return perf_swevent_overflow(event, 1, data, regs);
 
     if (local64_add_negative(nr, &hwc->period_left))
         return;
 
     perf_swevent_overflow(event, 0, data, regs);
 }
 
 static int perf_exclude_event(struct perf_event *event,
                   struct pt_regs *regs)
 {
     if (event->hw.state & PERF_HES_STOPPED)
         return 1;
 
     if (regs) {
         if (event->attr.exclude_user && user_mode(regs))
             return 1;
 
         if (event->attr.exclude_kernel && !user_mode(regs))
             return 1;
     }
 
     return 0;
 }
 
 static int perf_swevent_match(struct perf_event *event,
                 enum perf_type_id type,
                 u32 event_id,
                 struct perf_sample_data *data,
                 struct pt_regs *regs)
 {
     if (event->attr.type != type)
         return 0;
 
     if (event->attr.config != event_id)
         return 0;
 
     if (perf_exclude_event(event, regs))
         return 0;
 
     return 1;
 }
 
 static inline u64 swevent_hash(u64 type, u32 event_id)
 {
     u64 val = event_id | (type << 32);
 
     return hash_64(val, SWEVENT_HLIST_BITS);
 }
 
 static inline struct hlist_head *
 __find_swevent_head(struct swevent_hlist *hlist, u64 type, u32 event_id)
 {
     u64 hash = swevent_hash(type, event_id);
 
     return &hlist->heads[hash];
 }
 
 /* For the read side: events when they trigger */
 static inline struct hlist_head *
 find_swevent_head_rcu(struct swevent_htable *swhash, u64 type, u32 event_id)
 {
     struct swevent_hlist *hlist;
 
     hlist = rcu_dereference(swhash->swevent_hlist);
     if (!hlist)
         return NULL;
 
     return __find_swevent_head(hlist, type, event_id);
 }
 
 /* For the event head insertion and removal in the hlist */
 static inline struct hlist_head *
 find_swevent_head(struct swevent_htable *swhash, struct perf_event *event)
 {
     struct swevent_hlist *hlist;
     u32 event_id = event->attr.config;
     u64 type = event->attr.type;
 
     /*
      * Event scheduling is always serialized against hlist allocation
      * and release. Which makes the protected version suitable here.
      * The context lock guarantees that.
      */
     hlist = rcu_dereference_protected(swhash->swevent_hlist,
                       lockdep_is_held(&event->ctx->lock));
     if (!hlist)
         return NULL;
 
     return __find_swevent_head(hlist, type, event_id);
 }
 
 static void do_perf_sw_event(enum perf_type_id type, u32 event_id,
                     u64 nr,
                     struct perf_sample_data *data,
                     struct pt_regs *regs)
 {
     struct swevent_htable *swhash = this_cpu_ptr(&swevent_htable);
     struct perf_event *event;
     struct hlist_head *head;
 
     rcu_read_lock();
     head = find_swevent_head_rcu(swhash, type, event_id);
     if (!head)
         goto end;
 
     hlist_for_each_entry_rcu(event, head, hlist_entry) {
         if (perf_swevent_match(event, type, event_id, data, regs))
             perf_swevent_event(event, nr, data, regs);
     }
 end:
     rcu_read_unlock();
 }
 
 DEFINE_PER_CPU(struct pt_regs, __perf_regs[4]);
 
 int perf_swevent_get_recursion_context(void)
 {
     struct swevent_htable *swhash = this_cpu_ptr(&swevent_htable);
 
     return get_recursion_context(swhash->recursion);
 }
 EXPORT_SYMBOL_GPL(perf_swevent_get_recursion_context);
 
 void perf_swevent_put_recursion_context(int rctx)
 {
     struct swevent_htable *swhash = this_cpu_ptr(&swevent_htable);
 
     put_recursion_context(swhash->recursion, rctx);
 }
 
 void ___perf_sw_event(u32 event_id, u64 nr, struct pt_regs *regs, u64 addr)
 {
     struct perf_sample_data data;
 
     if (WARN_ON_ONCE(!regs))
         return;
 
     perf_sample_data_init(&data, addr, 0);
     do_perf_sw_event(PERF_TYPE_SOFTWARE, event_id, nr, &data, regs);
 }
 
 void __perf_sw_event(u32 event_id, u64 nr, struct pt_regs *regs, u64 addr)
 {
     int rctx;
 
     preempt_disable_notrace();
     rctx = perf_swevent_get_recursion_context();
     if (unlikely(rctx < 0))
         goto fail;
 
     ___perf_sw_event(event_id, nr, regs, addr);
 
     perf_swevent_put_recursion_context(rctx);
 fail:
     preempt_enable_notrace();
 }
 
 static void perf_swevent_read(struct perf_event *event)
 {
 }
 
 static int perf_swevent_add(struct perf_event *event, int flags)
 {
     struct swevent_htable *swhash = this_cpu_ptr(&swevent_htable);
     struct hw_perf_event *hwc = &event->hw;
     struct hlist_head *head;
 
     if (is_sampling_event(event)) {
         hwc->last_period = hwc->sample_period;
         perf_swevent_set_period(event);
     }
 
     hwc->state = !(flags & PERF_EF_START);
 
     head = find_swevent_head(swhash, event);
     if (WARN_ON_ONCE(!head))
         return -EINVAL;
 
     hlist_add_head_rcu(&event->hlist_entry, head);
     perf_event_update_userpage(event);
 
     return 0;
 }
 
 static void perf_swevent_del(struct perf_event *event, int flags)
 {
     hlist_del_rcu(&event->hlist_entry);
 }
 
 static void perf_swevent_start(struct perf_event *event, int flags)
 {
     event->hw.state = 0;
 }
 
 static void perf_swevent_stop(struct perf_event *event, int flags)
 {
     event->hw.state = PERF_HES_STOPPED;
 }
 
 /* Deref the hlist from the update side */
 static inline struct swevent_hlist *
 swevent_hlist_deref(struct swevent_htable *swhash)
 {
     return rcu_dereference_protected(swhash->swevent_hlist,
                      lockdep_is_held(&swhash->hlist_mutex));
 }
 
 static void swevent_hlist_release(struct swevent_htable *swhash)
 {
     struct swevent_hlist *hlist = swevent_hlist_deref(swhash);
 
     if (!hlist)
         return;
 
     RCU_INIT_POINTER(swhash->swevent_hlist, NULL);
     kfree_rcu(hlist, rcu_head);
 }
 
 static void swevent_hlist_put_cpu(int cpu)
 {
     struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
 
     mutex_lock(&swhash->hlist_mutex);
 
     if (!--swhash->hlist_refcount)
         swevent_hlist_release(swhash);
 
     mutex_unlock(&swhash->hlist_mutex);
 }
 
 static void swevent_hlist_put(void)
 {
     int cpu;
 
     for_each_possible_cpu(cpu)
         swevent_hlist_put_cpu(cpu);
 }
 
 static int swevent_hlist_get_cpu(int cpu)
 {
     struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
     int err = 0;
 
     mutex_lock(&swhash->hlist_mutex);
     if (!swevent_hlist_deref(swhash) &&
         cpumask_test_cpu(cpu, perf_online_mask)) {
         struct swevent_hlist *hlist;
 
         hlist = kzalloc(sizeof(*hlist), GFP_KERNEL);
         if (!hlist) {
             err = -ENOMEM;
             goto exit;
         }
         rcu_assign_pointer(swhash->swevent_hlist, hlist);
     }
     swhash->hlist_refcount++;
 exit:
     mutex_unlock(&swhash->hlist_mutex);
 
     return err;
 }
 
 static int swevent_hlist_get(void)
 {
     int err, cpu, failed_cpu;
 
     mutex_lock(&pmus_lock);
     for_each_possible_cpu(cpu) {
         err = swevent_hlist_get_cpu(cpu);
         if (err) {
             failed_cpu = cpu;
             goto fail;
         }
     }
     mutex_unlock(&pmus_lock);
     return 0;
 fail:
     for_each_possible_cpu(cpu) {
         if (cpu == failed_cpu)
             break;
         swevent_hlist_put_cpu(cpu);
     }
     mutex_unlock(&pmus_lock);
     return err;
 }
 
 struct static_key perf_swevent_enabled[PERF_COUNT_SW_MAX];
 
 static void sw_perf_event_destroy(struct perf_event *event)
 {
     u64 event_id = event->attr.config;
 
     WARN_ON(event->parent);
 
     static_key_slow_dec(&perf_swevent_enabled[event_id]);
     swevent_hlist_put();
 }
 
 static int perf_swevent_init(struct perf_event *event)
 {
     u64 event_id = event->attr.config;
 
     if (event->attr.type != PERF_TYPE_SOFTWARE)
         return -ENOENT;
 
     /*
      * no branch sampling for software events
      */
     if (has_branch_stack(event))
         return -EOPNOTSUPP;
 
     switch (event_id) {
     case PERF_COUNT_SW_CPU_CLOCK:
     case PERF_COUNT_SW_TASK_CLOCK:
         return -ENOENT;
 
     default:
         break;
     }
 
     if (event_id >= PERF_COUNT_SW_MAX)
         return -ENOENT;
 
     if (!event->parent) {
         int err;
 
         err = swevent_hlist_get();
         if (err)
             return err;
 
         static_key_slow_inc(&perf_swevent_enabled[event_id]);
         event->destroy = sw_perf_event_destroy;
     }
 
     return 0;
 }
 
 static struct pmu perf_swevent = {
     .task_ctx_nr    = perf_sw_context,
 
     .capabilities   = PERF_PMU_CAP_NO_NMI,
 
     .event_init = perf_swevent_init,
     .add        = perf_swevent_add,
     .del        = perf_swevent_del,
     .start      = perf_swevent_start,
     .stop       = perf_swevent_stop,
     .read       = perf_swevent_read,
 };
 
 #ifdef CONFIG_EVENT_TRACING
 
 static int perf_tp_filter_match(struct perf_event *event,
                 struct perf_sample_data *data)
 {
     void *record = data->raw->frag.data;
 
     /* only top level events have filters set */
     if (event->parent)
         event = event->parent;
 
     if (likely(!event->filter) || filter_match_preds(event->filter, record))
         return 1;
     return 0;
 }
 
 static int perf_tp_event_match(struct perf_event *event,
                 struct perf_sample_data *data,
                 struct pt_regs *regs)
 {
     if (event->hw.state & PERF_HES_STOPPED)
         return 0;
     /*
      * If exclude_kernel, only trace user-space tracepoints (uprobes)
      */
     if (event->attr.exclude_kernel && !user_mode(regs))
         return 0;
 
     if (!perf_tp_filter_match(event, data))
         return 0;
 
     return 1;
 }
 
 void perf_trace_run_bpf_submit(void *raw_data, int size, int rctx,
                    struct trace_event_call *call, u64 count,
                    struct pt_regs *regs, struct hlist_head *head,
                    struct task_struct *task)
 {
     if (bpf_prog_array_valid(call)) {
         *(struct pt_regs **)raw_data = regs;
         if (!trace_call_bpf(call, raw_data) || hlist_empty(head)) {
             perf_swevent_put_recursion_context(rctx);
             return;
         }
     }
     perf_tp_event(call->event.type, count, raw_data, size, regs, head,
               rctx, task);
 }
 EXPORT_SYMBOL_GPL(perf_trace_run_bpf_submit);
 
 void perf_tp_event(u16 event_type, u64 count, void *record, int entry_size,
            struct pt_regs *regs, struct hlist_head *head, int rctx,
            struct task_struct *task)
 {
     struct perf_sample_data data;
     struct perf_event *event;
 
     struct perf_raw_record raw = {
         .frag = {
             .size = entry_size,
             .data = record,
         },
     };
 
     perf_sample_data_init(&data, 0, 0);
     data.raw = &raw;
 
     perf_trace_buf_update(record, event_type);
 
     hlist_for_each_entry_rcu(event, head, hlist_entry) {
         if (perf_tp_event_match(event, &data, regs))
             perf_swevent_event(event, count, &data, regs);
     }
 
     /*
      * If we got specified a target task, also iterate its context and
      * deliver this event there too.
      */
     if (task && task != current) {
         struct perf_event_context *ctx;
         struct trace_entry *entry = record;
 
         rcu_read_lock();
         ctx = rcu_dereference(task->perf_event_ctxp[perf_sw_context]);
         if (!ctx)
             goto unlock;
 
         list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
             if (event->cpu != smp_processor_id())
                 continue;
             if (event->attr.type != PERF_TYPE_TRACEPOINT)
                 continue;
             if (event->attr.config != entry->type)
                 continue;
             /* Cannot deliver synchronous signal to other task. */
             if (event->attr.sigtrap)
                 continue;
             if (perf_tp_event_match(event, &data, regs))
                 perf_swevent_event(event, count, &data, regs);
         }
 unlock:
         rcu_read_unlock();
     }
 
     perf_swevent_put_recursion_context(rctx);
 }
 EXPORT_SYMBOL_GPL(perf_tp_event);
 
 static void tp_perf_event_destroy(struct perf_event *event)
 {
     perf_trace_destroy(event);
 }
 
 static int perf_tp_event_init(struct perf_event *event)
 {
     int err;
 
     if (event->attr.type != PERF_TYPE_TRACEPOINT)
         return -ENOENT;
 
     /*
      * no branch sampling for tracepoint events
      */
     if (has_branch_stack(event))
         return -EOPNOTSUPP;
 
     err = perf_trace_init(event);
     if (err)
         return err;
 
     event->destroy = tp_perf_event_destroy;
 
     return 0;
 }
 
 static struct pmu perf_tracepoint = {
     .task_ctx_nr    = perf_sw_context,
 
     .event_init = perf_tp_event_init,
     .add        = perf_trace_add,
     .del        = perf_trace_del,
     .start      = perf_swevent_start,
     .stop       = perf_swevent_stop,
     .read       = perf_swevent_read,
 };
 
 #if defined(CONFIG_KPROBE_EVENTS) || defined(CONFIG_UPROBE_EVENTS)
 /*
  * Flags in config, used by dynamic PMU kprobe and uprobe
  * The flags should match following PMU_FORMAT_ATTR().
  *
  * PERF_PROBE_CONFIG_IS_RETPROBE if set, create kretprobe/uretprobe
  *                               if not set, create kprobe/uprobe
  *
  * The following values specify a reference counter (or semaphore in the
  * terminology of tools like dtrace, systemtap, etc.) Userspace Statically
  * Defined Tracepoints (USDT). Currently, we use 40 bit for the offset.
  *
  * PERF_UPROBE_REF_CTR_OFFSET_BITS  # of bits in config as th offset
  * PERF_UPROBE_REF_CTR_OFFSET_SHIFT # of bits to shift left
  */
 enum perf_probe_config {
     PERF_PROBE_CONFIG_IS_RETPROBE = 1U << 0,  /* [k,u]retprobe */
     PERF_UPROBE_REF_CTR_OFFSET_BITS = 32,
     PERF_UPROBE_REF_CTR_OFFSET_SHIFT = 64 - PERF_UPROBE_REF_CTR_OFFSET_BITS,
 };
 
 PMU_FORMAT_ATTR(retprobe, "config:0");
 #endif
 
 #ifdef CONFIG_KPROBE_EVENTS
 static struct attribute *kprobe_attrs[] = {
     &format_attr_retprobe.attr,
     NULL,
 };
 
 static struct attribute_group kprobe_format_group = {
     .name = "format",
     .attrs = kprobe_attrs,
 };
 
 static const struct attribute_group *kprobe_attr_groups[] = {
     &kprobe_format_group,
     NULL,
 };
 
 static int perf_kprobe_event_init(struct perf_event *event);
 static struct pmu perf_kprobe = {
     .task_ctx_nr    = perf_sw_context,
     .event_init = perf_kprobe_event_init,
     .add        = perf_trace_add,
     .del        = perf_trace_del,
     .start      = perf_swevent_start,
     .stop       = perf_swevent_stop,
     .read       = perf_swevent_read,
     .attr_groups    = kprobe_attr_groups,
 };
 
 static int perf_kprobe_event_init(struct perf_event *event)
 {
     int err;
     bool is_retprobe;
 
     if (event->attr.type != perf_kprobe.type)
         return -ENOENT;
 
     if (!perfmon_capable())
         return -EACCES;
 
     /*
      * no branch sampling for probe events
      */
     if (has_branch_stack(event))
         return -EOPNOTSUPP;
 
     is_retprobe = event->attr.config & PERF_PROBE_CONFIG_IS_RETPROBE;
     err = perf_kprobe_init(event, is_retprobe);
     if (err)
         return err;
 
     event->destroy = perf_kprobe_destroy;
 
     return 0;
 }
 #endif /* CONFIG_KPROBE_EVENTS */
 
 #ifdef CONFIG_UPROBE_EVENTS
 PMU_FORMAT_ATTR(ref_ctr_offset, "config:32-63");
 
 static struct attribute *uprobe_attrs[] = {
     &format_attr_retprobe.attr,
     &format_attr_ref_ctr_offset.attr,
     NULL,
 };
 
 static struct attribute_group uprobe_format_group = {
     .name = "format",
     .attrs = uprobe_attrs,
 };
 
 static const struct attribute_group *uprobe_attr_groups[] = {
     &uprobe_format_group,
     NULL,
 };
 
 static int perf_uprobe_event_init(struct perf_event *event);
 static struct pmu perf_uprobe = {
     .task_ctx_nr    = perf_sw_context,
     .event_init = perf_uprobe_event_init,
     .add        = perf_trace_add,
     .del        = perf_trace_del,
     .start      = perf_swevent_start,
     .stop       = perf_swevent_stop,
     .read       = perf_swevent_read,
     .attr_groups    = uprobe_attr_groups,
 };
 
 static int perf_uprobe_event_init(struct perf_event *event)
 {
     int err;
     unsigned long ref_ctr_offset;
     bool is_retprobe;
 
     if (event->attr.type != perf_uprobe.type)
         return -ENOENT;
 
     if (!perfmon_capable())
         return -EACCES;
 
     /*
      * no branch sampling for probe events
      */
     if (has_branch_stack(event))
         return -EOPNOTSUPP;
 
     is_retprobe = event->attr.config & PERF_PROBE_CONFIG_IS_RETPROBE;
     ref_ctr_offset = event->attr.config >> PERF_UPROBE_REF_CTR_OFFSET_SHIFT;
     err = perf_uprobe_init(event, ref_ctr_offset, is_retprobe);
     if (err)
         return err;
 
     event->destroy = perf_uprobe_destroy;
 
     return 0;
 }
 #endif /* CONFIG_UPROBE_EVENTS */
 
 static inline void perf_tp_register(void)
 {
     perf_pmu_register(&perf_tracepoint, "tracepoint", PERF_TYPE_TRACEPOINT);
 #ifdef CONFIG_KPROBE_EVENTS
     perf_pmu_register(&perf_kprobe, "kprobe", -1);
 #endif
 #ifdef CONFIG_UPROBE_EVENTS
     perf_pmu_register(&perf_uprobe, "uprobe", -1);
 #endif
 }
 
 static void perf_event_free_filter(struct perf_event *event)
 {
     ftrace_profile_free_filter(event);
 }
 
 #ifdef CONFIG_BPF_SYSCALL
 static void bpf_overflow_handler(struct perf_event *event,
                  struct perf_sample_data *data,
                  struct pt_regs *regs)
 {
     struct bpf_perf_event_data_kern ctx = {
         .data = data,
         .event = event,
     };
     struct bpf_prog *prog;
     int ret = 0;
 
     ctx.regs = perf_arch_bpf_user_pt_regs(regs);
     if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1))
         goto out;
     rcu_read_lock();
     prog = READ_ONCE(event->prog);
     if (prog)
         ret = bpf_prog_run(prog, &ctx);
     rcu_read_unlock();
 out:
     __this_cpu_dec(bpf_prog_active);
     if (!ret)
         return;
 
     event->orig_overflow_handler(event, data, regs);
 }
 
 static int perf_event_set_bpf_handler(struct perf_event *event,
                       struct bpf_prog *prog,
                       u64 bpf_cookie)
 {
     if (event->overflow_handler_context)
         /* hw breakpoint or kernel counter */
         return -EINVAL;
 
     if (event->prog)
         return -EEXIST;
 
     if (prog->type != BPF_PROG_TYPE_PERF_EVENT)
         return -EINVAL;
 
     if (event->attr.precise_ip &&
         prog->call_get_stack &&
         (!(event->attr.sample_type & __PERF_SAMPLE_CALLCHAIN_EARLY) ||
          event->attr.exclude_callchain_kernel ||
          event->attr.exclude_callchain_user)) {
         /*
          * On perf_event with precise_ip, calling bpf_get_stack()
          * may trigger unwinder warnings and occasional crashes.
          * bpf_get_[stack|stackid] works around this issue by using
          * callchain attached to perf_sample_data. If the
          * perf_event does not full (kernel and user) callchain
          * attached to perf_sample_data, do not allow attaching BPF
          * program that calls bpf_get_[stack|stackid].
          */
         return -EPROTO;
     }
 
     event->prog = prog;
     event->bpf_cookie = bpf_cookie;
     event->orig_overflow_handler = READ_ONCE(event->overflow_handler);
     WRITE_ONCE(event->overflow_handler, bpf_overflow_handler);
     return 0;
 }
 
 static void perf_event_free_bpf_handler(struct perf_event *event)
 {
     struct bpf_prog *prog = event->prog;
 
     if (!prog)
         return;
 
     WRITE_ONCE(event->overflow_handler, event->orig_overflow_handler);
     event->prog = NULL;
     bpf_prog_put(prog);
 }
 #else
 static int perf_event_set_bpf_handler(struct perf_event *event,
                       struct bpf_prog *prog,
                       u64 bpf_cookie)
 {
     return -EOPNOTSUPP;
 }
 static void perf_event_free_bpf_handler(struct perf_event *event)
 {
 }
 #endif
 
 /*
  * returns true if the event is a tracepoint, or a kprobe/upprobe created
  * with perf_event_open()
  */
 static inline bool perf_event_is_tracing(struct perf_event *event)
 {
     if (event->pmu == &perf_tracepoint)
         return true;
 #ifdef CONFIG_KPROBE_EVENTS
     if (event->pmu == &perf_kprobe)
         return true;
 #endif
 #ifdef CONFIG_UPROBE_EVENTS
     if (event->pmu == &perf_uprobe)
         return true;
 #endif
     return false;
 }
 
 int perf_event_set_bpf_prog(struct perf_event *event, struct bpf_prog *prog,
                 u64 bpf_cookie)
 {
     bool is_kprobe, is_uprobe, is_tracepoint, is_syscall_tp;
 
     if (!perf_event_is_tracing(event))
         return perf_event_set_bpf_handler(event, prog, bpf_cookie);
 
     is_kprobe = event->tp_event->flags & TRACE_EVENT_FL_KPROBE;
     is_uprobe = event->tp_event->flags & TRACE_EVENT_FL_UPROBE;
     is_tracepoint = event->tp_event->flags & TRACE_EVENT_FL_TRACEPOINT;
     is_syscall_tp = is_syscall_trace_event(event->tp_event);
     if (!is_kprobe && !is_uprobe && !is_tracepoint && !is_syscall_tp)
         /* bpf programs can only be attached to u/kprobe or tracepoint */
         return -EINVAL;
 
     if (((is_kprobe || is_uprobe) && prog->type != BPF_PROG_TYPE_KPROBE) ||
         (is_tracepoint && prog->type != BPF_PROG_TYPE_TRACEPOINT) ||
         (is_syscall_tp && prog->type != BPF_PROG_TYPE_TRACEPOINT))
         return -EINVAL;
 
     if (prog->type == BPF_PROG_TYPE_KPROBE && prog->aux->sleepable && !is_uprobe)
         /* only uprobe programs are allowed to be sleepable */
         return -EINVAL;
 
     /* Kprobe override only works for kprobes, not uprobes. */
     if (prog->kprobe_override && !is_kprobe)
         return -EINVAL;
 
     if (is_tracepoint || is_syscall_tp) {
         int off = trace_event_get_offsets(event->tp_event);
 
         if (prog->aux->max_ctx_offset > off)
             return -EACCES;
     }
 
     return perf_event_attach_bpf_prog(event, prog, bpf_cookie);
 }
 
 void perf_event_free_bpf_prog(struct perf_event *event)
 {
     if (!perf_event_is_tracing(event)) {
         perf_event_free_bpf_handler(event);
         return;
     }
     perf_event_detach_bpf_prog(event);
 }
 
 #else
 
 static inline void perf_tp_register(void)
 {
 }
 
 static void perf_event_free_filter(struct perf_event *event)
 {
 }
 
 int perf_event_set_bpf_prog(struct perf_event *event, struct bpf_prog *prog,
                 u64 bpf_cookie)
 {
     return -ENOENT;
 }
 
 void perf_event_free_bpf_prog(struct perf_event *event)
 {
 }
 #endif /* CONFIG_EVENT_TRACING */
 
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 void perf_bp_event(struct perf_event *bp, void *data)
 {
     struct perf_sample_data sample;
     struct pt_regs *regs = data;
 
     perf_sample_data_init(&sample, bp->attr.bp_addr, 0);
 
     if (!bp->hw.state && !perf_exclude_event(bp, regs))
         perf_swevent_event(bp, 1, &sample, regs);
 }
 #endif
 
 /*
  * Allocate a new address filter
  */
 static struct perf_addr_filter *
 perf_addr_filter_new(struct perf_event *event, struct list_head *filters)
 {
     int node = cpu_to_node(event->cpu == -1 ? 0 : event->cpu);
     struct perf_addr_filter *filter;
 
     filter = kzalloc_node(sizeof(*filter), GFP_KERNEL, node);
     if (!filter)
         return NULL;
 
     INIT_LIST_HEAD(&filter->entry);
     list_add_tail(&filter->entry, filters);
 
     return filter;
 }
 
 static void free_filters_list(struct list_head *filters)
 {
     struct perf_addr_filter *filter, *iter;
 
     list_for_each_entry_safe(filter, iter, filters, entry) {
         path_put(&filter->path);
         list_del(&filter->entry);
         kfree(filter);
     }
 }
 
 /*
  * Free existing address filters and optionally install new ones
  */
 static void perf_addr_filters_splice(struct perf_event *event,
                      struct list_head *head)
 {
     unsigned long flags;
     LIST_HEAD(list);
 
     if (!has_addr_filter(event))
         return;
 
     /* don't bother with children, they don't have their own filters */
     if (event->parent)
         return;
 
     raw_spin_lock_irqsave(&event->addr_filters.lock, flags);
 
     list_splice_init(&event->addr_filters.list, &list);
     if (head)
         list_splice(head, &event->addr_filters.list);
 
     raw_spin_unlock_irqrestore(&event->addr_filters.lock, flags);
 
     free_filters_list(&list);
 }
 
 /*
  * Scan through mm's vmas and see if one of them matches the
  * @filter; if so, adjust filter's address range.
  * Called with mm::mmap_lock down for reading.
  */
 static void perf_addr_filter_apply(struct perf_addr_filter *filter,
                    struct mm_struct *mm,
                    struct perf_addr_filter_range *fr)
 {
     struct vm_area_struct *vma;
 
     for (vma = mm->mmap; vma; vma = vma->vm_next) {
         if (!vma->vm_file)
             continue;
 
         if (perf_addr_filter_vma_adjust(filter, vma, fr))
             return;
     }
 }
 
 /*
  * Update event's address range filters based on the
  * task's existing mappings, if any.
  */
 static void perf_event_addr_filters_apply(struct perf_event *event)
 {
     struct perf_addr_filters_head *ifh = perf_event_addr_filters(event);
     struct task_struct *task = READ_ONCE(event->ctx->task);
     struct perf_addr_filter *filter;
     struct mm_struct *mm = NULL;
     unsigned int count = 0;
     unsigned long flags;
 
     /*
      * We may observe TASK_TOMBSTONE, which means that the event tear-down
      * will stop on the parent's child_mutex that our caller is also holding
      */
     if (task == TASK_TOMBSTONE)
         return;
 
     if (ifh->nr_file_filters) {
         mm = get_task_mm(task);
         if (!mm)
             goto restart;
 
         mmap_read_lock(mm);
     }
 
     raw_spin_lock_irqsave(&ifh->lock, flags);
     list_for_each_entry(filter, &ifh->list, entry) {
         if (filter->path.dentry) {
             /*
              * Adjust base offset if the filter is associated to a
              * binary that needs to be mapped:
              */
             event->addr_filter_ranges[count].start = 0;
             event->addr_filter_ranges[count].size = 0;
 
             perf_addr_filter_apply(filter, mm, &event->addr_filter_ranges[count]);
         } else {
             event->addr_filter_ranges[count].start = filter->offset;
             event->addr_filter_ranges[count].size  = filter->size;
         }
 
         count++;
     }
 
     event->addr_filters_gen++;
     raw_spin_unlock_irqrestore(&ifh->lock, flags);
 
     if (ifh->nr_file_filters) {
         mmap_read_unlock(mm);
 
         mmput(mm);
     }
 
 restart:
     perf_event_stop(event, 1);
 }
 
 /*
  * Address range filtering: limiting the data to certain
  * instruction address ranges. Filters are ioctl()ed to us from
  * userspace as ascii strings.
  *
  * Filter string format:
  *
  * ACTION RANGE_SPEC
  * where ACTION is one of the
  *  * "filter": limit the trace to this region
  *  * "start": start tracing from this address
  *  * "stop": stop tracing at this address/region;
  * RANGE_SPEC is
  *  * for kernel addresses: <start address>[/<size>]
  *  * for object files:     <start address>[/<size>]@</path/to/object/file>
  *
  * if <size> is not specified or is zero, the range is treated as a single
  * address; not valid for ACTION=="filter".
  */
 enum {
     IF_ACT_NONE = -1,
     IF_ACT_FILTER,
     IF_ACT_START,
     IF_ACT_STOP,
     IF_SRC_FILE,
     IF_SRC_KERNEL,
     IF_SRC_FILEADDR,
     IF_SRC_KERNELADDR,
 };
 
 enum {
     IF_STATE_ACTION = 0,
     IF_STATE_SOURCE,
     IF_STATE_END,
 };
 
 static const match_table_t if_tokens = {
     { IF_ACT_FILTER,    "filter" },
     { IF_ACT_START,     "start" },
     { IF_ACT_STOP,      "stop" },
     { IF_SRC_FILE,      "%u/%u@%s" },
     { IF_SRC_KERNEL,    "%u/%u" },
     { IF_SRC_FILEADDR,  "%u@%s" },
     { IF_SRC_KERNELADDR,    "%u" },
     { IF_ACT_NONE,      NULL },
 };
 
 /*
  * Address filter string parser
  */
 static int
 perf_event_parse_addr_filter(struct perf_event *event, char *fstr,
                  struct list_head *filters)
 {
     struct perf_addr_filter *filter = NULL;
     char *start, *orig, *filename = NULL;
     substring_t args[MAX_OPT_ARGS];
     int state = IF_STATE_ACTION, token;
     unsigned int kernel = 0;
     int ret = -EINVAL;
 
     orig = fstr = kstrdup(fstr, GFP_KERNEL);
     if (!fstr)
         return -ENOMEM;
 
     while ((start = strsep(&fstr, " ,\n")) != NULL) {
         static const enum perf_addr_filter_action_t actions[] = {
             [IF_ACT_FILTER] = PERF_ADDR_FILTER_ACTION_FILTER,
             [IF_ACT_START]  = PERF_ADDR_FILTER_ACTION_START,
             [IF_ACT_STOP]   = PERF_ADDR_FILTER_ACTION_STOP,
         };
         ret = -EINVAL;
 
         if (!*start)
             continue;
 
         /* filter definition begins */
         if (state == IF_STATE_ACTION) {
             filter = perf_addr_filter_new(event, filters);
             if (!filter)
                 goto fail;
         }
 
         token = match_token(start, if_tokens, args);
         switch (token) {
         case IF_ACT_FILTER:
         case IF_ACT_START:
         case IF_ACT_STOP:
             if (state != IF_STATE_ACTION)
                 goto fail;
 
             filter->action = actions[token];
             state = IF_STATE_SOURCE;
             break;
 
         case IF_SRC_KERNELADDR:
         case IF_SRC_KERNEL:
             kernel = 1;
             fallthrough;
 
         case IF_SRC_FILEADDR:
         case IF_SRC_FILE:
             if (state != IF_STATE_SOURCE)
                 goto fail;
 
             *args[0].to = 0;
             ret = kstrtoul(args[0].from, 0, &filter->offset);
             if (ret)
                 goto fail;
 
             if (token == IF_SRC_KERNEL || token == IF_SRC_FILE) {
                 *args[1].to = 0;
                 ret = kstrtoul(args[1].from, 0, &filter->size);
                 if (ret)
                     goto fail;
             }
 
             if (token == IF_SRC_FILE || token == IF_SRC_FILEADDR) {
                 int fpos = token == IF_SRC_FILE ? 2 : 1;
 
                 kfree(filename);
                 filename = match_strdup(&args[fpos]);
                 if (!filename) {
                     ret = -ENOMEM;
                     goto fail;
                 }
             }
 
             state = IF_STATE_END;
             break;
 
         default:
             goto fail;
         }
 
         /*
          * Filter definition is fully parsed, validate and install it.
          * Make sure that it doesn't contradict itself or the event's
          * attribute.
          */
         if (state == IF_STATE_END) {
             ret = -EINVAL;
 
             /*
              * ACTION "filter" must have a non-zero length region
              * specified.
              */
             if (filter->action == PERF_ADDR_FILTER_ACTION_FILTER &&
                 !filter->size)
                 goto fail;
 
             if (!kernel) {
                 if (!filename)
                     goto fail;
 
                 /*
                  * For now, we only support file-based filters
                  * in per-task events; doing so for CPU-wide
                  * events requires additional context switching
                  * trickery, since same object code will be
                  * mapped at different virtual addresses in
                  * different processes.
                  */
                 ret = -EOPNOTSUPP;
                 if (!event->ctx->task)
                     goto fail;
 
                 /* look up the path and grab its inode */
                 ret = kern_path(filename, LOOKUP_FOLLOW,
                         &filter->path);
                 if (ret)
                     goto fail;
 
                 ret = -EINVAL;
                 if (!filter->path.dentry ||
                     !S_ISREG(d_inode(filter->path.dentry)
                          ->i_mode))
                     goto fail;
 
                 event->addr_filters.nr_file_filters++;
             }
 
             /* ready to consume more filters */
             kfree(filename);
             filename = NULL;
             state = IF_STATE_ACTION;
             filter = NULL;
             kernel = 0;
         }
     }
 
     if (state != IF_STATE_ACTION)
         goto fail;
 
     kfree(filename);
     kfree(orig);
 
     return 0;
 
 fail:
     kfree(filename);
     free_filters_list(filters);
     kfree(orig);
 
     return ret;
 }
 
 static int
 perf_event_set_addr_filter(struct perf_event *event, char *filter_str)
 {
     LIST_HEAD(filters);
     int ret;
 
     /*
      * Since this is called in perf_ioctl() path, we're already holding
      * ctx::mutex.
      */
     lockdep_assert_held(&event->ctx->mutex);
 
     if (WARN_ON_ONCE(event->parent))
         return -EINVAL;
 
     ret = perf_event_parse_addr_filter(event, filter_str, &filters);
     if (ret)
         goto fail_clear_files;
 
     ret = event->pmu->addr_filters_validate(&filters);
     if (ret)
         goto fail_free_filters;
 
     /* remove existing filters, if any */
     perf_addr_filters_splice(event, &filters);
 
     /* install new filters */
     perf_event_for_each_child(event, perf_event_addr_filters_apply);
 
     return ret;
 
 fail_free_filters:
     free_filters_list(&filters);
 
 fail_clear_files:
     event->addr_filters.nr_file_filters = 0;
 
     return ret;
 }
 
 static int perf_event_set_filter(struct perf_event *event, void __user *arg)
 {
     int ret = -EINVAL;
     char *filter_str;
 
     filter_str = strndup_user(arg, PAGE_SIZE);
     if (IS_ERR(filter_str))
         return PTR_ERR(filter_str);
 
 #ifdef CONFIG_EVENT_TRACING
     if (perf_event_is_tracing(event)) {
         struct perf_event_context *ctx = event->ctx;
 
         /*
          * Beware, here be dragons!!
          *
          * the tracepoint muck will deadlock against ctx->mutex, but
          * the tracepoint stuff does not actually need it. So
          * temporarily drop ctx->mutex. As per perf_event_ctx_lock() we
          * already have a reference on ctx.
          *
          * This can result in event getting moved to a different ctx,
          * but that does not affect the tracepoint state.
          */
         mutex_unlock(&ctx->mutex);
         ret = ftrace_profile_set_filter(event, event->attr.config, filter_str);
         mutex_lock(&ctx->mutex);
     } else
 #endif
     if (has_addr_filter(event))
         ret = perf_event_set_addr_filter(event, filter_str);
 
     kfree(filter_str);
     return ret;
 }
 
 /*
  * hrtimer based swevent callback
  */
 
 static enum hrtimer_restart perf_swevent_hrtimer(struct hrtimer *hrtimer)
 {
     enum hrtimer_restart ret = HRTIMER_RESTART;
     struct perf_sample_data data;
     struct pt_regs *regs;
     struct perf_event *event;
     u64 period;
 
     event = container_of(hrtimer, struct perf_event, hw.hrtimer);
 
     if (event->state != PERF_EVENT_STATE_ACTIVE)
         return HRTIMER_NORESTART;
 
     event->pmu->read(event);
 
     perf_sample_data_init(&data, 0, event->hw.last_period);
     regs = get_irq_regs();
 
     if (regs && !perf_exclude_event(event, regs)) {
         if (!(event->attr.exclude_idle && is_idle_task(current)))
             if (__perf_event_overflow(event, 1, &data, regs))
                 ret = HRTIMER_NORESTART;
     }
 
     period = max_t(u64, 10000, event->hw.sample_period);
     hrtimer_forward_now(hrtimer, ns_to_ktime(period));
 
     return ret;
 }
 
 static void perf_swevent_start_hrtimer(struct perf_event *event)
 {
     struct hw_perf_event *hwc = &event->hw;
     s64 period;
 
     if (!is_sampling_event(event))
         return;
 
     period = local64_read(&hwc->period_left);
     if (period) {
         if (period < 0)
             period = 10000;
 
         local64_set(&hwc->period_left, 0);
     } else {
         period = max_t(u64, 10000, hwc->sample_period);
     }
     hrtimer_start(&hwc->hrtimer, ns_to_ktime(period),
               HRTIMER_MODE_REL_PINNED_HARD);
 }
 
 static void perf_swevent_cancel_hrtimer(struct perf_event *event)
 {
     struct hw_perf_event *hwc = &event->hw;
 
     if (is_sampling_event(event)) {
         ktime_t remaining = hrtimer_get_remaining(&hwc->hrtimer);
         local64_set(&hwc->period_left, ktime_to_ns(remaining));
 
         hrtimer_cancel(&hwc->hrtimer);
     }
 }
 
 static void perf_swevent_init_hrtimer(struct perf_event *event)
 {
     struct hw_perf_event *hwc = &event->hw;
 
     if (!is_sampling_event(event))
         return;
 
     hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
     hwc->hrtimer.function = perf_swevent_hrtimer;
 
     /*
      * Since hrtimers have a fixed rate, we can do a static freq->period
      * mapping and avoid the whole period adjust feedback stuff.
      */
     if (event->attr.freq) {
         long freq = event->attr.sample_freq;
 
         event->attr.sample_period = NSEC_PER_SEC / freq;
         hwc->sample_period = event->attr.sample_period;
         local64_set(&hwc->period_left, hwc->sample_period);
         hwc->last_period = hwc->sample_period;
         event->attr.freq = 0;
     }
 }
 
 /*
  * Software event: cpu wall time clock
  */
 
 static void cpu_clock_event_update(struct perf_event *event)
 {
     s64 prev;
     u64 now;
 
     now = local_clock();
     prev = local64_xchg(&event->hw.prev_count, now);
     local64_add(now - prev, &event->count);
 }
 
 static void cpu_clock_event_start(struct perf_event *event, int flags)
 {
     local64_set(&event->hw.prev_count, local_clock());
     perf_swevent_start_hrtimer(event);
 }
 
 static void cpu_clock_event_stop(struct perf_event *event, int flags)
 {
     perf_swevent_cancel_hrtimer(event);
     cpu_clock_event_update(event);
 }
 
 static int cpu_clock_event_add(struct perf_event *event, int flags)
 {
     if (flags & PERF_EF_START)
         cpu_clock_event_start(event, flags);
     perf_event_update_userpage(event);
 
     return 0;
 }
 
 static void cpu_clock_event_del(struct perf_event *event, int flags)
 {
     cpu_clock_event_stop(event, flags);
 }
 
 static void cpu_clock_event_read(struct perf_event *event)
 {
     cpu_clock_event_update(event);
 }
 
 static int cpu_clock_event_init(struct perf_event *event)
 {
     if (event->attr.type != PERF_TYPE_SOFTWARE)
         return -ENOENT;
 
     if (event->attr.config != PERF_COUNT_SW_CPU_CLOCK)
         return -ENOENT;
 
     /*
      * no branch sampling for software events
      */
     if (has_branch_stack(event))
         return -EOPNOTSUPP;
 
     perf_swevent_init_hrtimer(event);
 
     return 0;
 }
 
 static struct pmu perf_cpu_clock = {
     .task_ctx_nr    = perf_sw_context,
 
     .capabilities   = PERF_PMU_CAP_NO_NMI,
 
     .event_init = cpu_clock_event_init,
     .add        = cpu_clock_event_add,
     .del        = cpu_clock_event_del,
     .start      = cpu_clock_event_start,
     .stop       = cpu_clock_event_stop,
     .read       = cpu_clock_event_read,
 };
 
 /*
  * Software event: task time clock
  */
 
 static void task_clock_event_update(struct perf_event *event, u64 now)
 {
     u64 prev;
     s64 delta;
 
     prev = local64_xchg(&event->hw.prev_count, now);
     delta = now - prev;
     local64_add(delta, &event->count);
 }
 
 static void task_clock_event_start(struct perf_event *event, int flags)
 {
     local64_set(&event->hw.prev_count, event->ctx->time);
     perf_swevent_start_hrtimer(event);
 }
 
 static void task_clock_event_stop(struct perf_event *event, int flags)
 {
     perf_swevent_cancel_hrtimer(event);
     task_clock_event_update(event, event->ctx->time);
 }
 
 static int task_clock_event_add(struct perf_event *event, int flags)
 {
     if (flags & PERF_EF_START)
         task_clock_event_start(event, flags);
     perf_event_update_userpage(event);
 
     return 0;
 }
 
 static void task_clock_event_del(struct perf_event *event, int flags)
 {
     task_clock_event_stop(event, PERF_EF_UPDATE);
 }
 
 static void task_clock_event_read(struct perf_event *event)
 {
     u64 now = perf_clock();
     u64 delta = now - event->ctx->timestamp;
     u64 time = event->ctx->time + delta;
 
     task_clock_event_update(event, time);
 }
 
 static int task_clock_event_init(struct perf_event *event)
 {
     if (event->attr.type != PERF_TYPE_SOFTWARE)
         return -ENOENT;
 
     if (event->attr.config != PERF_COUNT_SW_TASK_CLOCK)
         return -ENOENT;
 
     /*
      * no branch sampling for software events
      */
     if (has_branch_stack(event))
         return -EOPNOTSUPP;
 
     perf_swevent_init_hrtimer(event);
 
     return 0;
 }
 
 static struct pmu perf_task_clock = {
     .task_ctx_nr    = perf_sw_context,
 
     .capabilities   = PERF_PMU_CAP_NO_NMI,
 
     .event_init = task_clock_event_init,
     .add        = task_clock_event_add,
     .del        = task_clock_event_del,
     .start      = task_clock_event_start,
     .stop       = task_clock_event_stop,
     .read       = task_clock_event_read,
 };
 
 static void perf_pmu_nop_void(struct pmu *pmu)
 {
 }
 
 static void perf_pmu_nop_txn(struct pmu *pmu, unsigned int flags)
 {
 }
 
 static int perf_pmu_nop_int(struct pmu *pmu)
 {
     return 0;
 }
 
 static int perf_event_nop_int(struct perf_event *event, u64 value)
 {
     return 0;
 }
 
 static DEFINE_PER_CPU(unsigned int, nop_txn_flags);
 
 static void perf_pmu_start_txn(struct pmu *pmu, unsigned int flags)
 {
     __this_cpu_write(nop_txn_flags, flags);
 
     if (flags & ~PERF_PMU_TXN_ADD)
         return;
 
     perf_pmu_disable(pmu);
 }
 
 static int perf_pmu_commit_txn(struct pmu *pmu)
 {
     unsigned int flags = __this_cpu_read(nop_txn_flags);
 
     __this_cpu_write(nop_txn_flags, 0);
 
     if (flags & ~PERF_PMU_TXN_ADD)
         return 0;
 
     perf_pmu_enable(pmu);
     return 0;
 }
 
 static void perf_pmu_cancel_txn(struct pmu *pmu)
 {
     unsigned int flags =  __this_cpu_read(nop_txn_flags);
 
     __this_cpu_write(nop_txn_flags, 0);
 
     if (flags & ~PERF_PMU_TXN_ADD)
         return;
 
     perf_pmu_enable(pmu);
 }
 
 static int perf_event_idx_default(struct perf_event *event)
 {
     return 0;
 }
 
 /*
  * Ensures all contexts with the same task_ctx_nr have the same
  * pmu_cpu_context too.
  */
 static struct perf_cpu_context __percpu *find_pmu_context(int ctxn)
 {
     struct pmu *pmu;
 
     if (ctxn < 0)
         return NULL;
 
     list_for_each_entry(pmu, &pmus, entry) {
         if (pmu->task_ctx_nr == ctxn)
             return pmu->pmu_cpu_context;
     }
 
     return NULL;
 }
 
 static void free_pmu_context(struct pmu *pmu)
 {
     /*
      * Static contexts such as perf_sw_context have a global lifetime
      * and may be shared between different PMUs. Avoid freeing them
      * when a single PMU is going away.
      */
     if (pmu->task_ctx_nr > perf_invalid_context)
         return;
 
     free_percpu(pmu->pmu_cpu_context);
 }
 
 /*
  * Let userspace know that this PMU supports address range filtering:
  */
 static ssize_t nr_addr_filters_show(struct device *dev,
                     struct device_attribute *attr,
                     char *page)
 {
     struct pmu *pmu = dev_get_drvdata(dev);
 
     return snprintf(page, PAGE_SIZE - 1, "%d\n", pmu->nr_addr_filters);
 }
 DEVICE_ATTR_RO(nr_addr_filters);
 
 static struct idr pmu_idr;
 
 static ssize_t
 type_show(struct device *dev, struct device_attribute *attr, char *page)
 {
     struct pmu *pmu = dev_get_drvdata(dev);
 
     return snprintf(page, PAGE_SIZE-1, "%d\n", pmu->type);
 }
 static DEVICE_ATTR_RO(type);
 
 static ssize_t
 perf_event_mux_interval_ms_show(struct device *dev,
                 struct device_attribute *attr,
                 char *page)
 {
     struct pmu *pmu = dev_get_drvdata(dev);
 
     return snprintf(page, PAGE_SIZE-1, "%d\n", pmu->hrtimer_interval_ms);
 }
 
 static DEFINE_MUTEX(mux_interval_mutex);
 
 static ssize_t
 perf_event_mux_interval_ms_store(struct device *dev,
                  struct device_attribute *attr,
                  const char *buf, size_t count)
 {
     struct pmu *pmu = dev_get_drvdata(dev);
     int timer, cpu, ret;
 
     ret = kstrtoint(buf, 0, &timer);
     if (ret)
         return ret;
 
     if (timer < 1)
         return -EINVAL;
 
     /* same value, noting to do */
     if (timer == pmu->hrtimer_interval_ms)
         return count;
 
     mutex_lock(&mux_interval_mutex);
     pmu->hrtimer_interval_ms = timer;
 
     /* update all cpuctx for this PMU */
     cpus_read_lock();
     for_each_online_cpu(cpu) {
         struct perf_cpu_context *cpuctx;
         cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
         cpuctx->hrtimer_interval = ns_to_ktime(NSEC_PER_MSEC * timer);
 
         cpu_function_call(cpu,
             (remote_function_f)perf_mux_hrtimer_restart, cpuctx);
     }
     cpus_read_unlock();
     mutex_unlock(&mux_interval_mutex);
 
     return count;
 }
 static DEVICE_ATTR_RW(perf_event_mux_interval_ms);
 
 static struct attribute *pmu_dev_attrs[] = {
     &dev_attr_type.attr,
     &dev_attr_perf_event_mux_interval_ms.attr,
     NULL,
 };
 ATTRIBUTE_GROUPS(pmu_dev);
 
 static int pmu_bus_running;
 static struct bus_type pmu_bus = {
     .name       = "event_source",
     .dev_groups = pmu_dev_groups,
 };
 
 static void pmu_dev_release(struct device *dev)
 {
     kfree(dev);
 }
 
 static int pmu_dev_alloc(struct pmu *pmu)
 {
     int ret = -ENOMEM;
 
     pmu->dev = kzalloc(sizeof(struct device), GFP_KERNEL);
     if (!pmu->dev)
         goto out;
 
     pmu->dev->groups = pmu->attr_groups;
     device_initialize(pmu->dev);
     ret = dev_set_name(pmu->dev, "%s", pmu->name);
     if (ret)
         goto free_dev;
 
     dev_set_drvdata(pmu->dev, pmu);
     pmu->dev->bus = &pmu_bus;
     pmu->dev->release = pmu_dev_release;
     ret = device_add(pmu->dev);
     if (ret)
         goto free_dev;
 
     /* For PMUs with address filters, throw in an extra attribute: */
     if (pmu->nr_addr_filters)
         ret = device_create_file(pmu->dev, &dev_attr_nr_addr_filters);
 
     if (ret)
         goto del_dev;
 
     if (pmu->attr_update)
         ret = sysfs_update_groups(&pmu->dev->kobj, pmu->attr_update);
 
     if (ret)
         goto del_dev;
 
 out:
     return ret;
 
 del_dev:
     device_del(pmu->dev);
 
 free_dev:
     put_device(pmu->dev);
     goto out;
 }
 
 static struct lock_class_key cpuctx_mutex;
 static struct lock_class_key cpuctx_lock;
 
 int perf_pmu_register(struct pmu *pmu, const char *name, int type)
 {
     int cpu, ret, max = PERF_TYPE_MAX;
 
     mutex_lock(&pmus_lock);
     ret = -ENOMEM;
     pmu->pmu_disable_count = alloc_percpu(int);
     if (!pmu->pmu_disable_count)
         goto unlock;
 
     pmu->type = -1;
     if (!name)
         goto skip_type;
     pmu->name = name;
 
     if (type != PERF_TYPE_SOFTWARE) {
         if (type >= 0)
             max = type;
 
         ret = idr_alloc(&pmu_idr, pmu, max, 0, GFP_KERNEL);
         if (ret < 0)
             goto free_pdc;
 
         WARN_ON(type >= 0 && ret != type);
 
         type = ret;
     }
     pmu->type = type;
 
     if (pmu_bus_running) {
         ret = pmu_dev_alloc(pmu);
         if (ret)
             goto free_idr;
     }
 
 skip_type:
     if (pmu->task_ctx_nr == perf_hw_context) {
         static int hw_context_taken = 0;
 
         /*
          * Other than systems with heterogeneous CPUs, it never makes
          * sense for two PMUs to share perf_hw_context. PMUs which are
          * uncore must use perf_invalid_context.
          */
         if (WARN_ON_ONCE(hw_context_taken &&
             !(pmu->capabilities & PERF_PMU_CAP_HETEROGENEOUS_CPUS)))
             pmu->task_ctx_nr = perf_invalid_context;
 
         hw_context_taken = 1;
     }
 
     pmu->pmu_cpu_context = find_pmu_context(pmu->task_ctx_nr);
     if (pmu->pmu_cpu_context)
         goto got_cpu_context;
 
     ret = -ENOMEM;
     pmu->pmu_cpu_context = alloc_percpu(struct perf_cpu_context);
     if (!pmu->pmu_cpu_context)
         goto free_dev;
 
     for_each_possible_cpu(cpu) {
         struct perf_cpu_context *cpuctx;
 
         cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
         __perf_event_init_context(&cpuctx->ctx);
         lockdep_set_class(&cpuctx->ctx.mutex, &cpuctx_mutex);
         lockdep_set_class(&cpuctx->ctx.lock, &cpuctx_lock);
         cpuctx->ctx.pmu = pmu;
         cpuctx->online = cpumask_test_cpu(cpu, perf_online_mask);
 
         __perf_mux_hrtimer_init(cpuctx, cpu);
 
         cpuctx->heap_size = ARRAY_SIZE(cpuctx->heap_default);
         cpuctx->heap = cpuctx->heap_default;
     }
 
 got_cpu_context:
     if (!pmu->start_txn) {
         if (pmu->pmu_enable) {
             /*
              * If we have pmu_enable/pmu_disable calls, install
              * transaction stubs that use that to try and batch
              * hardware accesses.
              */
             pmu->start_txn  = perf_pmu_start_txn;
             pmu->commit_txn = perf_pmu_commit_txn;
             pmu->cancel_txn = perf_pmu_cancel_txn;
         } else {
             pmu->start_txn  = perf_pmu_nop_txn;
             pmu->commit_txn = perf_pmu_nop_int;
             pmu->cancel_txn = perf_pmu_nop_void;
         }
     }
 
     if (!pmu->pmu_enable) {
         pmu->pmu_enable  = perf_pmu_nop_void;
         pmu->pmu_disable = perf_pmu_nop_void;
     }
 
     if (!pmu->check_period)
         pmu->check_period = perf_event_nop_int;
 
     if (!pmu->event_idx)
         pmu->event_idx = perf_event_idx_default;
 
     /*
      * Ensure the TYPE_SOFTWARE PMUs are at the head of the list,
      * since these cannot be in the IDR. This way the linear search
      * is fast, provided a valid software event is provided.
      */
     if (type == PERF_TYPE_SOFTWARE || !name)
         list_add_rcu(&pmu->entry, &pmus);
     else
         list_add_tail_rcu(&pmu->entry, &pmus);
 
     atomic_set(&pmu->exclusive_cnt, 0);
     ret = 0;
 unlock:
     mutex_unlock(&pmus_lock);
 
     return ret;
 
 free_dev:
     device_del(pmu->dev);
     put_device(pmu->dev);
 
 free_idr:
     if (pmu->type != PERF_TYPE_SOFTWARE)
         idr_remove(&pmu_idr, pmu->type);
 
 free_pdc:
     free_percpu(pmu->pmu_disable_count);
     goto unlock;
 }
 EXPORT_SYMBOL_GPL(perf_pmu_register);
 
 void perf_pmu_unregister(struct pmu *pmu)
 {
     mutex_lock(&pmus_lock);
     list_del_rcu(&pmu->entry);
 
     /*
      * We dereference the pmu list under both SRCU and regular RCU, so
      * synchronize against both of those.
      */
     synchronize_srcu(&pmus_srcu);
     synchronize_rcu();
 
     free_percpu(pmu->pmu_disable_count);
     if (pmu->type != PERF_TYPE_SOFTWARE)
         idr_remove(&pmu_idr, pmu->type);
     if (pmu_bus_running) {
         if (pmu->nr_addr_filters)
             device_remove_file(pmu->dev, &dev_attr_nr_addr_filters);
         device_del(pmu->dev);
         put_device(pmu->dev);
     }
     free_pmu_context(pmu);
     mutex_unlock(&pmus_lock);
 }
 EXPORT_SYMBOL_GPL(perf_pmu_unregister);
 
 static inline bool has_extended_regs(struct perf_event *event)
 {
     return (event->attr.sample_regs_user & PERF_REG_EXTENDED_MASK) ||
            (event->attr.sample_regs_intr & PERF_REG_EXTENDED_MASK);
 }
 
 static int perf_try_init_event(struct pmu *pmu, struct perf_event *event)
 {
     struct perf_event_context *ctx = NULL;
     int ret;
 
     if (!try_module_get(pmu->module))
         return -ENODEV;
 
     /*
      * A number of pmu->event_init() methods iterate the sibling_list to,
      * for example, validate if the group fits on the PMU. Therefore,
      * if this is a sibling event, acquire the ctx->mutex to protect
      * the sibling_list.
      */
     if (event->group_leader != event && pmu->task_ctx_nr != perf_sw_context) {
         /*
          * This ctx->mutex can nest when we're called through
          * inheritance. See the perf_event_ctx_lock_nested() comment.
          */
         ctx = perf_event_ctx_lock_nested(event->group_leader,
                          SINGLE_DEPTH_NESTING);
         BUG_ON(!ctx);
     }
 
     event->pmu = pmu;
     ret = pmu->event_init(event);
 
     if (ctx)
         perf_event_ctx_unlock(event->group_leader, ctx);
 
     if (!ret) {
         if (!(pmu->capabilities & PERF_PMU_CAP_EXTENDED_REGS) &&
             has_extended_regs(event))
             ret = -EOPNOTSUPP;
 
         if (pmu->capabilities & PERF_PMU_CAP_NO_EXCLUDE &&
             event_has_any_exclude_flag(event))
             ret = -EINVAL;
 
         if (ret && event->destroy)
             event->destroy(event);
     }
 
     if (ret)
         module_put(pmu->module);
 
     return ret;
 }
 
 static struct pmu *perf_init_event(struct perf_event *event)
 {
     bool extended_type = false;
     int idx, type, ret;
     struct pmu *pmu;
 
     idx = srcu_read_lock(&pmus_srcu);
 
     /* Try parent's PMU first: */
     if (event->parent && event->parent->pmu) {
         pmu = event->parent->pmu;
         ret = perf_try_init_event(pmu, event);
         if (!ret)
             goto unlock;
     }
 
     /*
      * PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE
      * are often aliases for PERF_TYPE_RAW.
      */
     type = event->attr.type;
     if (type == PERF_TYPE_HARDWARE || type == PERF_TYPE_HW_CACHE) {
         type = event->attr.config >> PERF_PMU_TYPE_SHIFT;
         if (!type) {
             type = PERF_TYPE_RAW;
         } else {
             extended_type = true;
             event->attr.config &= PERF_HW_EVENT_MASK;
         }
     }
 
 again:
     rcu_read_lock();
     pmu = idr_find(&pmu_idr, type);
     rcu_read_unlock();
     if (pmu) {
         if (event->attr.type != type && type != PERF_TYPE_RAW &&
             !(pmu->capabilities & PERF_PMU_CAP_EXTENDED_HW_TYPE))
             goto fail;
 
         ret = perf_try_init_event(pmu, event);
         if (ret == -ENOENT && event->attr.type != type && !extended_type) {
             type = event->attr.type;
             goto again;
         }
 
         if (ret)
             pmu = ERR_PTR(ret);
 
         goto unlock;
     }
 
     list_for_each_entry_rcu(pmu, &pmus, entry, lockdep_is_held(&pmus_srcu)) {
         ret = perf_try_init_event(pmu, event);
         if (!ret)
             goto unlock;
 
         if (ret != -ENOENT) {
             pmu = ERR_PTR(ret);
             goto unlock;
         }
     }
 fail:
     pmu = ERR_PTR(-ENOENT);
 unlock:
     srcu_read_unlock(&pmus_srcu, idx);
 
     return pmu;
 }
 
 static void attach_sb_event(struct perf_event *event)
 {
     struct pmu_event_list *pel = per_cpu_ptr(&pmu_sb_events, event->cpu);
 
     raw_spin_lock(&pel->lock);
     list_add_rcu(&event->sb_list, &pel->list);
     raw_spin_unlock(&pel->lock);
 }
 
 /*
  * We keep a list of all !task (and therefore per-cpu) events
  * that need to receive side-band records.
  *
  * This avoids having to scan all the various PMU per-cpu contexts
  * looking for them.
  */
 static void account_pmu_sb_event(struct perf_event *event)
 {
     if (is_sb_event(event))
         attach_sb_event(event);
 }
 
 static void account_event_cpu(struct perf_event *event, int cpu)
 {
     if (event->parent)
         return;
 
     if (is_cgroup_event(event))
         atomic_inc(&per_cpu(perf_cgroup_events, cpu));
 }
 
 /* Freq events need the tick to stay alive (see perf_event_task_tick). */
 static void account_freq_event_nohz(void)
 {
 #ifdef CONFIG_NO_HZ_FULL
     /* Lock so we don't race with concurrent unaccount */
     spin_lock(&nr_freq_lock);
     if (atomic_inc_return(&nr_freq_events) == 1)
         tick_nohz_dep_set(TICK_DEP_BIT_PERF_EVENTS);
     spin_unlock(&nr_freq_lock);
 #endif
 }
 
 static void account_freq_event(void)
 {
     if (tick_nohz_full_enabled())
         account_freq_event_nohz();
     else
         atomic_inc(&nr_freq_events);
 }
 
 
 static void account_event(struct perf_event *event)
 {
     bool inc = false;
 
     if (event->parent)
         return;
 
     if (event->attach_state & (PERF_ATTACH_TASK | PERF_ATTACH_SCHED_CB))
         inc = true;
     if (event->attr.mmap || event->attr.mmap_data)
         atomic_inc(&nr_mmap_events);
     if (event->attr.build_id)
         atomic_inc(&nr_build_id_events);
     if (event->attr.comm)
         atomic_inc(&nr_comm_events);
     if (event->attr.namespaces)
         atomic_inc(&nr_namespaces_events);
     if (event->attr.cgroup)
         atomic_inc(&nr_cgroup_events);
     if (event->attr.task)
         atomic_inc(&nr_task_events);
     if (event->attr.freq)
         account_freq_event();
     if (event->attr.context_switch) {
         atomic_inc(&nr_switch_events);
         inc = true;
     }
     if (has_branch_stack(event))
         inc = true;
     if (is_cgroup_event(event))
         inc = true;
     if (event->attr.ksymbol)
         atomic_inc(&nr_ksymbol_events);
     if (event->attr.bpf_event)
         atomic_inc(&nr_bpf_events);
     if (event->attr.text_poke)
         atomic_inc(&nr_text_poke_events);
 
     if (inc) {
         /*
          * We need the mutex here because static_branch_enable()
          * must complete *before* the perf_sched_count increment
          * becomes visible.
          */
         if (atomic_inc_not_zero(&perf_sched_count))
             goto enabled;
 
         mutex_lock(&perf_sched_mutex);
         if (!atomic_read(&perf_sched_count)) {
             static_branch_enable(&perf_sched_events);
             /*
              * Guarantee that all CPUs observe they key change and
              * call the perf scheduling hooks before proceeding to
              * install events that need them.
              */
             synchronize_rcu();
         }
         /*
          * Now that we have waited for the sync_sched(), allow further
          * increments to by-pass the mutex.
          */
         atomic_inc(&perf_sched_count);
         mutex_unlock(&perf_sched_mutex);
     }
 enabled:
 
     account_event_cpu(event, event->cpu);
 
     account_pmu_sb_event(event);
 }
 
 /*
  * Allocate and initialize an event structure
  */
 static struct perf_event *
 perf_event_alloc(struct perf_event_attr *attr, int cpu,
          struct task_struct *task,
          struct perf_event *group_leader,
          struct perf_event *parent_event,
          perf_overflow_handler_t overflow_handler,
          void *context, int cgroup_fd)
 {
     struct pmu *pmu;
     struct perf_event *event;
     struct hw_perf_event *hwc;
     long err = -EINVAL;
     int node;
 
     if ((unsigned)cpu >= nr_cpu_ids) {
         if (!task || cpu != -1)
             return ERR_PTR(-EINVAL);
     }
     if (attr->sigtrap && !task) {
         /* Requires a task: avoid signalling random tasks. */
         return ERR_PTR(-EINVAL);
     }
 
     node = (cpu >= 0) ? cpu_to_node(cpu) : -1;
     event = kmem_cache_alloc_node(perf_event_cache, GFP_KERNEL | __GFP_ZERO,
                       node);
     if (!event)
         return ERR_PTR(-ENOMEM);
 
     /*
      * Single events are their own group leaders, with an
      * empty sibling list:
      */
     if (!group_leader)
         group_leader = event;
 
     mutex_init(&event->child_mutex);
     INIT_LIST_HEAD(&event->child_list);
 
     INIT_LIST_HEAD(&event->event_entry);
     INIT_LIST_HEAD(&event->sibling_list);
     INIT_LIST_HEAD(&event->active_list);
     init_event_group(event);
     INIT_LIST_HEAD(&event->rb_entry);
     INIT_LIST_HEAD(&event->active_entry);
     INIT_LIST_HEAD(&event->addr_filters.list);
     INIT_HLIST_NODE(&event->hlist_entry);
 
 
     init_waitqueue_head(&event->waitq);
     event->pending_disable = -1;
     init_irq_work(&event->pending, perf_pending_event);
 
     mutex_init(&event->mmap_mutex);
     raw_spin_lock_init(&event->addr_filters.lock);
 
     atomic_long_set(&event->refcount, 1);
     event->cpu      = cpu;
     event->attr     = *attr;
     event->group_leader = group_leader;
     event->pmu      = NULL;
     event->oncpu        = -1;
 
     event->parent       = parent_event;
 
     event->ns       = get_pid_ns(task_active_pid_ns(current));
     event->id       = atomic64_inc_return(&perf_event_id);
 
     event->state        = PERF_EVENT_STATE_INACTIVE;
 
     if (parent_event)
         event->event_caps = parent_event->event_caps;
 
     if (event->attr.sigtrap)
         atomic_set(&event->event_limit, 1);
 
     if (task) {
         event->attach_state = PERF_ATTACH_TASK;
         /*
          * XXX pmu::event_init needs to know what task to account to
          * and we cannot use the ctx information because we need the
          * pmu before we get a ctx.
          */
         event->hw.target = get_task_struct(task);
     }
 
     event->clock = &local_clock;
     if (parent_event)
         event->clock = parent_event->clock;
 
     if (!overflow_handler && parent_event) {
         overflow_handler = parent_event->overflow_handler;
         context = parent_event->overflow_handler_context;
 #if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_EVENT_TRACING)
         if (overflow_handler == bpf_overflow_handler) {
             struct bpf_prog *prog = parent_event->prog;
 
             bpf_prog_inc(prog);
             event->prog = prog;
             event->orig_overflow_handler =
                 parent_event->orig_overflow_handler;
         }
 #endif
     }
 
     if (overflow_handler) {
         event->overflow_handler = overflow_handler;
         event->overflow_handler_context = context;
     } else if (is_write_backward(event)){
         event->overflow_handler = perf_event_output_backward;
         event->overflow_handler_context = NULL;
     } else {
         event->overflow_handler = perf_event_output_forward;
         event->overflow_handler_context = NULL;
     }
 
     perf_event__state_init(event);
 
     pmu = NULL;
 
     hwc = &event->hw;
     hwc->sample_period = attr->sample_period;
     if (attr->freq && attr->sample_freq)
         hwc->sample_period = 1;
     hwc->last_period = hwc->sample_period;
 
     local64_set(&hwc->period_left, hwc->sample_period);
 
     /*
      * We currently do not support PERF_SAMPLE_READ on inherited events.
      * See perf_output_read().
      */
     if (attr->inherit && (attr->sample_type & PERF_SAMPLE_READ))
         goto err_ns;
 
     if (!has_branch_stack(event))
         event->attr.branch_sample_type = 0;
 
     pmu = perf_init_event(event);
     if (IS_ERR(pmu)) {
         err = PTR_ERR(pmu);
         goto err_ns;
     }
 
     /*
      * Disallow uncore-cgroup events, they don't make sense as the cgroup will
      * be different on other CPUs in the uncore mask.
      */
     if (pmu->task_ctx_nr == perf_invalid_context && cgroup_fd != -1) {
         err = -EINVAL;
         goto err_pmu;
     }
 
     if (event->attr.aux_output &&
         !(pmu->capabilities & PERF_PMU_CAP_AUX_OUTPUT)) {
         err = -EOPNOTSUPP;
         goto err_pmu;
     }
 
     if (cgroup_fd != -1) {
         err = perf_cgroup_connect(cgroup_fd, event, attr, group_leader);
         if (err)
             goto err_pmu;
     }
 
     err = exclusive_event_init(event);
     if (err)
         goto err_pmu;
 
     if (has_addr_filter(event)) {
         event->addr_filter_ranges = kcalloc(pmu->nr_addr_filters,
                             sizeof(struct perf_addr_filter_range),
                             GFP_KERNEL);
         if (!event->addr_filter_ranges) {
             err = -ENOMEM;
             goto err_per_task;
         }
 
         /*
          * Clone the parent's vma offsets: they are valid until exec()
          * even if the mm is not shared with the parent.
          */
         if (event->parent) {
             struct perf_addr_filters_head *ifh = perf_event_addr_filters(event);
 
             raw_spin_lock_irq(&ifh->lock);
             memcpy(event->addr_filter_ranges,
                    event->parent->addr_filter_ranges,
                    pmu->nr_addr_filters * sizeof(struct perf_addr_filter_range));
             raw_spin_unlock_irq(&ifh->lock);
         }
 
         /* force hw sync on the address filters */
         event->addr_filters_gen = 1;
     }
 
     if (!event->parent) {
         if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) {
             err = get_callchain_buffers(attr->sample_max_stack);
             if (err)
                 goto err_addr_filters;
         }
     }
 
     err = security_perf_event_alloc(event);
     if (err)
         goto err_callchain_buffer;
 
     /* symmetric to unaccount_event() in _free_event() */
     account_event(event);
 
     return event;
 
 err_callchain_buffer:
     if (!event->parent) {
         if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)
             put_callchain_buffers();
     }
 err_addr_filters:
     kfree(event->addr_filter_ranges);
 
 err_per_task:
     exclusive_event_destroy(event);
 
 err_pmu:
     if (is_cgroup_event(event))
         perf_detach_cgroup(event);
     if (event->destroy)
         event->destroy(event);
     module_put(pmu->module);
 err_ns:
     if (event->ns)
         put_pid_ns(event->ns);
     if (event->hw.target)
         put_task_struct(event->hw.target);
     kmem_cache_free(perf_event_cache, event);
 
     return ERR_PTR(err);
 }
 
 static int perf_copy_attr(struct perf_event_attr __user *uattr,
               struct perf_event_attr *attr)
 {
     u32 size;
     int ret;
 
     /* Zero the full structure, so that a short copy will be nice. */
     memset(attr, 0, sizeof(*attr));
 
     ret = get_user(size, &uattr->size);
     if (ret)
         return ret;
 
     /* ABI compatibility quirk: */
     if (!size)
         size = PERF_ATTR_SIZE_VER0;
     if (size < PERF_ATTR_SIZE_VER0 || size > PAGE_SIZE)
         goto err_size;
 
     ret = copy_struct_from_user(attr, sizeof(*attr), uattr, size);
     if (ret) {
         if (ret == -E2BIG)
             goto err_size;
         return ret;
     }
 
     attr->size = size;
 
     if (attr->__reserved_1 || attr->__reserved_2 || attr->__reserved_3)
         return -EINVAL;
 
     if (attr->sample_type & ~(PERF_SAMPLE_MAX-1))
         return -EINVAL;
 
     if (attr->read_format & ~(PERF_FORMAT_MAX-1))
         return -EINVAL;
 
     if (attr->sample_type & PERF_SAMPLE_BRANCH_STACK) {
         u64 mask = attr->branch_sample_type;
 
         /* only using defined bits */
         if (mask & ~(PERF_SAMPLE_BRANCH_MAX-1))
             return -EINVAL;
 
         /* at least one branch bit must be set */
         if (!(mask & ~PERF_SAMPLE_BRANCH_PLM_ALL))
             return -EINVAL;
 
         /* propagate priv level, when not set for branch */
         if (!(mask & PERF_SAMPLE_BRANCH_PLM_ALL)) {
 
             /* exclude_kernel checked on syscall entry */
             if (!attr->exclude_kernel)
                 mask |= PERF_SAMPLE_BRANCH_KERNEL;
 
             if (!attr->exclude_user)
                 mask |= PERF_SAMPLE_BRANCH_USER;
 
             if (!attr->exclude_hv)
                 mask |= PERF_SAMPLE_BRANCH_HV;
             /*
              * adjust user setting (for HW filter setup)
              */
             attr->branch_sample_type = mask;
         }
         /* privileged levels capture (kernel, hv): check permissions */
         if (mask & PERF_SAMPLE_BRANCH_PERM_PLM) {
             ret = perf_allow_kernel(attr);
             if (ret)
                 return ret;
         }
     }
 
     if (attr->sample_type & PERF_SAMPLE_REGS_USER) {
         ret = perf_reg_validate(attr->sample_regs_user);
         if (ret)
             return ret;
     }
 
     if (attr->sample_type & PERF_SAMPLE_STACK_USER) {
         if (!arch_perf_have_user_stack_dump())
             return -ENOSYS;
 
         /*
          * We have __u32 type for the size, but so far
          * we can only use __u16 as maximum due to the
          * __u16 sample size limit.
          */
         if (attr->sample_stack_user >= USHRT_MAX)
             return -EINVAL;
         else if (!IS_ALIGNED(attr->sample_stack_user, sizeof(u64)))
             return -EINVAL;
     }
 
     if (!attr->sample_max_stack)
         attr->sample_max_stack = sysctl_perf_event_max_stack;
 
     if (attr->sample_type & PERF_SAMPLE_REGS_INTR)
         ret = perf_reg_validate(attr->sample_regs_intr);
 
 #ifndef CONFIG_CGROUP_PERF
     if (attr->sample_type & PERF_SAMPLE_CGROUP)
         return -EINVAL;
 #endif
     if ((attr->sample_type & PERF_SAMPLE_WEIGHT) &&
         (attr->sample_type & PERF_SAMPLE_WEIGHT_STRUCT))
         return -EINVAL;
 
     if (!attr->inherit && attr->inherit_thread)
         return -EINVAL;
 
     if (attr->remove_on_exec && attr->enable_on_exec)
         return -EINVAL;
 
     if (attr->sigtrap && !attr->remove_on_exec)
         return -EINVAL;
 
 out:
     return ret;
 
 err_size:
     put_user(sizeof(*attr), &uattr->size);
     ret = -E2BIG;
     goto out;
 }
 
 static void mutex_lock_double(struct mutex *a, struct mutex *b)
 {
     if (b < a)
         swap(a, b);
 
     mutex_lock(a);
     mutex_lock_nested(b, SINGLE_DEPTH_NESTING);
 }
 
 static int
 perf_event_set_output(struct perf_event *event, struct perf_event *output_event)
 {
     struct perf_buffer *rb = NULL;
     int ret = -EINVAL;
 
     if (!output_event) {
         mutex_lock(&event->mmap_mutex);
         goto set;
     }
 
     /* don't allow circular references */
     if (event == output_event)
         goto out;
 
     /*
      * Don't allow cross-cpu buffers
      */
     if (output_event->cpu != event->cpu)
         goto out;
 
     /*
      * If its not a per-cpu rb, it must be the same task.
      */
     if (output_event->cpu == -1 && output_event->ctx != event->ctx)
         goto out;
 
     /*
      * Mixing clocks in the same buffer is trouble you don't need.
      */
     if (output_event->clock != event->clock)
         goto out;
 
     /*
      * Either writing ring buffer from beginning or from end.
      * Mixing is not allowed.
      */
     if (is_write_backward(output_event) != is_write_backward(event))
         goto out;
 
     /*
      * If both events generate aux data, they must be on the same PMU
      */
     if (has_aux(event) && has_aux(output_event) &&
         event->pmu != output_event->pmu)
         goto out;
 
     /*
      * Hold both mmap_mutex to serialize against perf_mmap_close().  Since
      * output_event is already on rb->event_list, and the list iteration
      * restarts after every removal, it is guaranteed this new event is
      * observed *OR* if output_event is already removed, it's guaranteed we
      * observe !rb->mmap_count.
      */
     mutex_lock_double(&event->mmap_mutex, &output_event->mmap_mutex);
 set:
     /* Can't redirect output if we've got an active mmap() */
     if (atomic_read(&event->mmap_count))
         goto unlock;
 
     if (output_event) {
         /* get the rb we want to redirect to */
         rb = ring_buffer_get(output_event);
         if (!rb)
             goto unlock;
 
         /* did we race against perf_mmap_close() */
         if (!atomic_read(&rb->mmap_count)) {
             ring_buffer_put(rb);
             goto unlock;
         }
     }
 
     ring_buffer_attach(event, rb);
 
     ret = 0;
 unlock:
     mutex_unlock(&event->mmap_mutex);
     if (output_event)
         mutex_unlock(&output_event->mmap_mutex);
 
 out:
     return ret;
 }
 
 static int perf_event_set_clock(struct perf_event *event, clockid_t clk_id)
 {
     bool nmi_safe = false;
 
     switch (clk_id) {
     case CLOCK_MONOTONIC:
         event->clock = &ktime_get_mono_fast_ns;
         nmi_safe = true;
         break;
 
     case CLOCK_MONOTONIC_RAW:
         event->clock = &ktime_get_raw_fast_ns;
         nmi_safe = true;
         break;
 
     case CLOCK_REALTIME:
         event->clock = &ktime_get_real_ns;
         break;
 
     case CLOCK_BOOTTIME:
         event->clock = &ktime_get_boottime_ns;
         break;
 
     case CLOCK_TAI:
         event->clock = &ktime_get_clocktai_ns;
         break;
 
     default:
         return -EINVAL;
     }
 
     if (!nmi_safe && !(event->pmu->capabilities & PERF_PMU_CAP_NO_NMI))
         return -EINVAL;
 
     return 0;
 }
 
 /*
  * Variation on perf_event_ctx_lock_nested(), except we take two context
  * mutexes.
  */
 static struct perf_event_context *
 __perf_event_ctx_lock_double(struct perf_event *group_leader,
                  struct perf_event_context *ctx)
 {
     struct perf_event_context *gctx;
 
 again:
     rcu_read_lock();
     gctx = READ_ONCE(group_leader->ctx);
     if (!refcount_inc_not_zero(&gctx->refcount)) {
         rcu_read_unlock();
         goto again;
     }
     rcu_read_unlock();
 
     mutex_lock_double(&gctx->mutex, &ctx->mutex);
 
     if (group_leader->ctx != gctx) {
         mutex_unlock(&ctx->mutex);
         mutex_unlock(&gctx->mutex);
         put_ctx(gctx);
         goto again;
     }
 
     return gctx;
 }
 
 static bool
 perf_check_permission(struct perf_event_attr *attr, struct task_struct *task)
 {
     unsigned int ptrace_mode = PTRACE_MODE_READ_REALCREDS;
     bool is_capable = perfmon_capable();
 
     if (attr->sigtrap) {
         /*
          * perf_event_attr::sigtrap sends signals to the other task.
          * Require the current task to also have CAP_KILL.
          */
         rcu_read_lock();
         is_capable &= ns_capable(__task_cred(task)->user_ns, CAP_KILL);
         rcu_read_unlock();
 
         /*
          * If the required capabilities aren't available, checks for
          * ptrace permissions: upgrade to ATTACH, since sending signals
          * can effectively change the target task.
          */
         ptrace_mode = PTRACE_MODE_ATTACH_REALCREDS;
     }
 
     /*
      * Preserve ptrace permission check for backwards compatibility. The
      * ptrace check also includes checks that the current task and other
      * task have matching uids, and is therefore not done here explicitly.
      */
     return is_capable || ptrace_may_access(task, ptrace_mode);
 }
 
 /**
  * sys_perf_event_open - open a performance event, associate it to a task/cpu
  *
  * @attr_uptr:  event_id type attributes for monitoring/sampling
  * @pid:        target pid
  * @cpu:        target cpu
  * @group_fd:       group leader event fd
  * @flags:      perf event open flags
  */
 SYSCALL_DEFINE5(perf_event_open,
         struct perf_event_attr __user *, attr_uptr,
         pid_t, pid, int, cpu, int, group_fd, unsigned long, flags)
 {
     struct perf_event *group_leader = NULL, *output_event = NULL;
     struct perf_event *event, *sibling;
     struct perf_event_attr attr;
     struct perf_event_context *ctx, *gctx;
     struct file *event_file = NULL;
     struct fd group = {NULL, 0};
     struct task_struct *task = NULL;
     struct pmu *pmu;
     int event_fd;
     int move_group = 0;
     int err;
     int f_flags = O_RDWR;
     int cgroup_fd = -1;
 
     /* for future expandability... */
     if (flags & ~PERF_FLAG_ALL)
         return -EINVAL;
 
     /* Do we allow access to perf_event_open(2) ? */
     err = security_perf_event_open(&attr, PERF_SECURITY_OPEN);
     if (err)
         return err;
 
     err = perf_copy_attr(attr_uptr, &attr);
     if (err)
         return err;
 
     if (!attr.exclude_kernel) {
         err = perf_allow_kernel(&attr);
         if (err)
             return err;
     }
 
     if (attr.namespaces) {
         if (!perfmon_capable())
             return -EACCES;
     }
 
     if (attr.freq) {
         if (attr.sample_freq > sysctl_perf_event_sample_rate)
             return -EINVAL;
     } else {
         if (attr.sample_period & (1ULL << 63))
             return -EINVAL;
     }
 
     /* Only privileged users can get physical addresses */
     if ((attr.sample_type & PERF_SAMPLE_PHYS_ADDR)) {
         err = perf_allow_kernel(&attr);
         if (err)
             return err;
     }
 
     /* REGS_INTR can leak data, lockdown must prevent this */
     if (attr.sample_type & PERF_SAMPLE_REGS_INTR) {
         err = security_locked_down(LOCKDOWN_PERF);
         if (err)
             return err;
     }
 
     /*
      * In cgroup mode, the pid argument is used to pass the fd
      * opened to the cgroup directory in cgroupfs. The cpu argument
      * designates the cpu on which to monitor threads from that
      * cgroup.
      */
     if ((flags & PERF_FLAG_PID_CGROUP) && (pid == -1 || cpu == -1))
         return -EINVAL;
 
     if (flags & PERF_FLAG_FD_CLOEXEC)
         f_flags |= O_CLOEXEC;
 
     event_fd = get_unused_fd_flags(f_flags);
     if (event_fd < 0)
         return event_fd;
 
     if (group_fd != -1) {
         err = perf_fget_light(group_fd, &group);
         if (err)
             goto err_fd;
         group_leader = group.file->private_data;
         if (flags & PERF_FLAG_FD_OUTPUT)
             output_event = group_leader;
         if (flags & PERF_FLAG_FD_NO_GROUP)
             group_leader = NULL;
     }
 
     if (pid != -1 && !(flags & PERF_FLAG_PID_CGROUP)) {
         task = find_lively_task_by_vpid(pid);
         if (IS_ERR(task)) {
             err = PTR_ERR(task);
             goto err_group_fd;
         }
     }
 
     if (task && group_leader &&
         group_leader->attr.inherit != attr.inherit) {
         err = -EINVAL;
         goto err_task;
     }
 
     if (flags & PERF_FLAG_PID_CGROUP)
         cgroup_fd = pid;
 
     event = perf_event_alloc(&attr, cpu, task, group_leader, NULL,
                  NULL, NULL, cgroup_fd);
     if (IS_ERR(event)) {
         err = PTR_ERR(event);
         goto err_task;
     }
 
     if (is_sampling_event(event)) {
         if (event->pmu->capabilities & PERF_PMU_CAP_NO_INTERRUPT) {
             err = -EOPNOTSUPP;
             goto err_alloc;
         }
     }
 
     /*
      * Special case software events and allow them to be part of
      * any hardware group.
      */
     pmu = event->pmu;
 
     if (attr.use_clockid) {
         err = perf_event_set_clock(event, attr.clockid);
         if (err)
             goto err_alloc;
     }
 
     if (pmu->task_ctx_nr == perf_sw_context)
         event->event_caps |= PERF_EV_CAP_SOFTWARE;
 
     if (group_leader) {
         if (is_software_event(event) &&
             !in_software_context(group_leader)) {
             /*
              * If the event is a sw event, but the group_leader
              * is on hw context.
              *
              * Allow the addition of software events to hw
              * groups, this is safe because software events
              * never fail to schedule.
              */
             pmu = group_leader->ctx->pmu;
         } else if (!is_software_event(event) &&
                is_software_event(group_leader) &&
                (group_leader->group_caps & PERF_EV_CAP_SOFTWARE)) {
             /*
              * In case the group is a pure software group, and we
              * try to add a hardware event, move the whole group to
              * the hardware context.
              */
             move_group = 1;
         }
     }
 
     /*
      * Get the target context (task or percpu):
      */
     ctx = find_get_context(pmu, task, event);
     if (IS_ERR(ctx)) {
         err = PTR_ERR(ctx);
         goto err_alloc;
     }
 
     /*
      * Look up the group leader (we will attach this event to it):
      */
     if (group_leader) {
         err = -EINVAL;
 
         /*
          * Do not allow a recursive hierarchy (this new sibling
          * becoming part of another group-sibling):
          */
         if (group_leader->group_leader != group_leader)
             goto err_context;
 
         /* All events in a group should have the same clock */
         if (group_leader->clock != event->clock)
             goto err_context;
 
         /*
          * Make sure we're both events for the same CPU;
          * grouping events for different CPUs is broken; since
          * you can never concurrently schedule them anyhow.
          */
         if (group_leader->cpu != event->cpu)
             goto err_context;
 
         /*
          * Make sure we're both on the same task, or both
          * per-CPU events.
          */
         if (group_leader->ctx->task != ctx->task)
             goto err_context;
 
         /*
          * Do not allow to attach to a group in a different task
          * or CPU context. If we're moving SW events, we'll fix
          * this up later, so allow that.
          *
          * Racy, not holding group_leader->ctx->mutex, see comment with
          * perf_event_ctx_lock().
          */
         if (!move_group && group_leader->ctx != ctx)
             goto err_context;
 
         /*
          * Only a group leader can be exclusive or pinned
          */
         if (attr.exclusive || attr.pinned)
             goto err_context;
     }
 
     if (output_event) {
         err = perf_event_set_output(event, output_event);
         if (err)
             goto err_context;
     }
 
     event_file = anon_inode_getfile("[perf_event]", &perf_fops, event,
                     f_flags);
     if (IS_ERR(event_file)) {
         err = PTR_ERR(event_file);
         event_file = NULL;
         goto err_context;
     }
 
     if (task) {
         err = down_read_interruptible(&task->signal->exec_update_lock);
         if (err)
             goto err_file;
 
         /*
          * We must hold exec_update_lock across this and any potential
          * perf_install_in_context() call for this new event to
          * serialize against exec() altering our credentials (and the
          * perf_event_exit_task() that could imply).
          */
         err = -EACCES;
         if (!perf_check_permission(&attr, task))
             goto err_cred;
     }
 
     if (move_group) {
         gctx = __perf_event_ctx_lock_double(group_leader, ctx);
 
         if (gctx->task == TASK_TOMBSTONE) {
             err = -ESRCH;
             goto err_locked;
         }
 
         /*
          * Check if we raced against another sys_perf_event_open() call
          * moving the software group underneath us.
          */
         if (!(group_leader->group_caps & PERF_EV_CAP_SOFTWARE)) {
             /*
              * If someone moved the group out from under us, check
              * if this new event wound up on the same ctx, if so
              * its the regular !move_group case, otherwise fail.
              */
             if (gctx != ctx) {
                 err = -EINVAL;
                 goto err_locked;
             } else {
                 perf_event_ctx_unlock(group_leader, gctx);
                 move_group = 0;
                 goto not_move_group;
             }
         }
 
         /*
          * Failure to create exclusive events returns -EBUSY.
          */
         err = -EBUSY;
         if (!exclusive_event_installable(group_leader, ctx))
             goto err_locked;
 
         for_each_sibling_event(sibling, group_leader) {
             if (!exclusive_event_installable(sibling, ctx))
                 goto err_locked;
         }
     } else {
         mutex_lock(&ctx->mutex);
 
         /*
          * Now that we hold ctx->lock, (re)validate group_leader->ctx == ctx,
          * see the group_leader && !move_group test earlier.
          */
         if (group_leader && group_leader->ctx != ctx) {
             err = -EINVAL;
             goto err_locked;
         }
     }
 not_move_group:
 
     if (ctx->task == TASK_TOMBSTONE) {
         err = -ESRCH;
         goto err_locked;
     }
 
     if (!perf_event_validate_size(event)) {
         err = -E2BIG;
         goto err_locked;
     }
 
     if (!task) {
         /*
          * Check if the @cpu we're creating an event for is online.
          *
          * We use the perf_cpu_context::ctx::mutex to serialize against
          * the hotplug notifiers. See perf_event_{init,exit}_cpu().
          */
         struct perf_cpu_context *cpuctx =
             container_of(ctx, struct perf_cpu_context, ctx);
 
         if (!cpuctx->online) {
             err = -ENODEV;
             goto err_locked;
         }
     }
 
     if (perf_need_aux_event(event) && !perf_get_aux_event(event, group_leader)) {
         err = -EINVAL;
         goto err_locked;
     }
 
     /*
      * Must be under the same ctx::mutex as perf_install_in_context(),
      * because we need to serialize with concurrent event creation.
      */
     if (!exclusive_event_installable(event, ctx)) {
         err = -EBUSY;
         goto err_locked;
     }
 
     WARN_ON_ONCE(ctx->parent_ctx);
 
     /*
      * This is the point on no return; we cannot fail hereafter. This is
      * where we start modifying current state.
      */
 
     if (move_group) {
         /*
          * See perf_event_ctx_lock() for comments on the details
          * of swizzling perf_event::ctx.
          */
         perf_remove_from_context(group_leader, 0);
         put_ctx(gctx);
 
         for_each_sibling_event(sibling, group_leader) {
             perf_remove_from_context(sibling, 0);
             put_ctx(gctx);
         }
 
         /*
          * Wait for everybody to stop referencing the events through
          * the old lists, before installing it on new lists.
          */
         synchronize_rcu();
 
         /*
          * Install the group siblings before the group leader.
          *
          * Because a group leader will try and install the entire group
          * (through the sibling list, which is still in-tact), we can
          * end up with siblings installed in the wrong context.
          *
          * By installing siblings first we NO-OP because they're not
          * reachable through the group lists.
          */
         for_each_sibling_event(sibling, group_leader) {
             perf_event__state_init(sibling);
             perf_install_in_context(ctx, sibling, sibling->cpu);
             get_ctx(ctx);
         }
 
         /*
          * Removing from the context ends up with disabled
          * event. What we want here is event in the initial
          * startup state, ready to be add into new context.
          */
         perf_event__state_init(group_leader);
         perf_install_in_context(ctx, group_leader, group_leader->cpu);
         get_ctx(ctx);
     }
 
     /*
      * Precalculate sample_data sizes; do while holding ctx::mutex such
      * that we're serialized against further additions and before
      * perf_install_in_context() which is the point the event is active and
      * can use these values.
      */
     perf_event__header_size(event);
     perf_event__id_header_size(event);
 
     event->owner = current;
 
     perf_install_in_context(ctx, event, event->cpu);
     perf_unpin_context(ctx);
 
     if (move_group)
         perf_event_ctx_unlock(group_leader, gctx);
     mutex_unlock(&ctx->mutex);
 
     if (task) {
         up_read(&task->signal->exec_update_lock);
         put_task_struct(task);
     }
 
     mutex_lock(&current->perf_event_mutex);
     list_add_tail(&event->owner_entry, &current->perf_event_list);
     mutex_unlock(&current->perf_event_mutex);
 
     /*
      * Drop the reference on the group_event after placing the
      * new event on the sibling_list. This ensures destruction
      * of the group leader will find the pointer to itself in
      * perf_group_detach().
      */
     fdput(group);
     fd_install(event_fd, event_file);
     return event_fd;
 
 err_locked:
     if (move_group)
         perf_event_ctx_unlock(group_leader, gctx);
     mutex_unlock(&ctx->mutex);
 err_cred:
     if (task)
         up_read(&task->signal->exec_update_lock);
 err_file:
     fput(event_file);
 err_context:
     perf_unpin_context(ctx);
     put_ctx(ctx);
 err_alloc:
     /*
      * If event_file is set, the fput() above will have called ->release()
      * and that will take care of freeing the event.
      */
     if (!event_file)
         free_event(event);
 err_task:
     if (task)
         put_task_struct(task);
 err_group_fd:
     fdput(group);
 err_fd:
     put_unused_fd(event_fd);
     return err;
 }
 
 /**
  * perf_event_create_kernel_counter
  *
  * @attr: attributes of the counter to create
  * @cpu: cpu in which the counter is bound
  * @task: task to profile (NULL for percpu)
  * @overflow_handler: callback to trigger when we hit the event
  * @context: context data could be used in overflow_handler callback
  */
 struct perf_event *
 perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
                  struct task_struct *task,
                  perf_overflow_handler_t overflow_handler,
                  void *context)
 {
     struct perf_event_context *ctx;
     struct perf_event *event;
     int err;
 
     /*
      * Grouping is not supported for kernel events, neither is 'AUX',
      * make sure the caller's intentions are adjusted.
      */
     if (attr->aux_output)
         return ERR_PTR(-EINVAL);
 
     event = perf_event_alloc(attr, cpu, task, NULL, NULL,
                  overflow_handler, context, -1);
     if (IS_ERR(event)) {
         err = PTR_ERR(event);
         goto err;
     }
 
     /* Mark owner so we could distinguish it from user events. */
     event->owner = TASK_TOMBSTONE;
 
     /*
      * Get the target context (task or percpu):
      */
     ctx = find_get_context(event->pmu, task, event);
     if (IS_ERR(ctx)) {
         err = PTR_ERR(ctx);
         goto err_free;
     }
 
     WARN_ON_ONCE(ctx->parent_ctx);
     mutex_lock(&ctx->mutex);
     if (ctx->task == TASK_TOMBSTONE) {
         err = -ESRCH;
         goto err_unlock;
     }
 
     if (!task) {
         /*
          * Check if the @cpu we're creating an event for is online.
          *
          * We use the perf_cpu_context::ctx::mutex to serialize against
          * the hotplug notifiers. See perf_event_{init,exit}_cpu().
          */
         struct perf_cpu_context *cpuctx =
             container_of(ctx, struct perf_cpu_context, ctx);
         if (!cpuctx->online) {
             err = -ENODEV;
             goto err_unlock;
         }
     }
 
     if (!exclusive_event_installable(event, ctx)) {
         err = -EBUSY;
         goto err_unlock;
     }
 
     perf_install_in_context(ctx, event, event->cpu);
     perf_unpin_context(ctx);
     mutex_unlock(&ctx->mutex);
 
     return event;
 
 err_unlock:
     mutex_unlock(&ctx->mutex);
     perf_unpin_context(ctx);
     put_ctx(ctx);
 err_free:
     free_event(event);
 err:
     return ERR_PTR(err);
 }
 EXPORT_SYMBOL_GPL(perf_event_create_kernel_counter);
 
 void perf_pmu_migrate_context(struct pmu *pmu, int src_cpu, int dst_cpu)
 {
     struct perf_event_context *src_ctx;
     struct perf_event_context *dst_ctx;
     struct perf_event *event, *tmp;
     LIST_HEAD(events);
 
     src_ctx = &per_cpu_ptr(pmu->pmu_cpu_context, src_cpu)->ctx;
     dst_ctx = &per_cpu_ptr(pmu->pmu_cpu_context, dst_cpu)->ctx;
 
     /*
      * See perf_event_ctx_lock() for comments on the details
      * of swizzling perf_event::ctx.
      */
     mutex_lock_double(&src_ctx->mutex, &dst_ctx->mutex);
     list_for_each_entry_safe(event, tmp, &src_ctx->event_list,
                  event_entry) {
         perf_remove_from_context(event, 0);
         unaccount_event_cpu(event, src_cpu);
         put_ctx(src_ctx);
         list_add(&event->migrate_entry, &events);
     }
 
     /*
      * Wait for the events to quiesce before re-instating them.
      */
     synchronize_rcu();
 
     /*
      * Re-instate events in 2 passes.
      *
      * Skip over group leaders and only install siblings on this first
      * pass, siblings will not get enabled without a leader, however a
      * leader will enable its siblings, even if those are still on the old
      * context.
      */
     list_for_each_entry_safe(event, tmp, &events, migrate_entry) {
         if (event->group_leader == event)
             continue;
 
         list_del(&event->migrate_entry);
         if (event->state >= PERF_EVENT_STATE_OFF)
             event->state = PERF_EVENT_STATE_INACTIVE;
         account_event_cpu(event, dst_cpu);
         perf_install_in_context(dst_ctx, event, dst_cpu);
         get_ctx(dst_ctx);
     }
 
     /*
      * Once all the siblings are setup properly, install the group leaders
      * to make it go.
      */
     list_for_each_entry_safe(event, tmp, &events, migrate_entry) {
         list_del(&event->migrate_entry);
         if (event->state >= PERF_EVENT_STATE_OFF)
             event->state = PERF_EVENT_STATE_INACTIVE;
         account_event_cpu(event, dst_cpu);
         perf_install_in_context(dst_ctx, event, dst_cpu);
         get_ctx(dst_ctx);
     }
     mutex_unlock(&dst_ctx->mutex);
     mutex_unlock(&src_ctx->mutex);
 }
 EXPORT_SYMBOL_GPL(perf_pmu_migrate_context);
 
 static void sync_child_event(struct perf_event *child_event)
 {
     struct perf_event *parent_event = child_event->parent;
     u64 child_val;
 
     if (child_event->attr.inherit_stat) {
         struct task_struct *task = child_event->ctx->task;
 
         if (task && task != TASK_TOMBSTONE)
             perf_event_read_event(child_event, task);
     }
 
     child_val = perf_event_count(child_event);
 
     /*
      * Add back the child's count to the parent's count:
      */
     atomic64_add(child_val, &parent_event->child_count);
     atomic64_add(child_event->total_time_enabled,
              &parent_event->child_total_time_enabled);
     atomic64_add(child_event->total_time_running,
              &parent_event->child_total_time_running);
 }
 
 static void
 perf_event_exit_event(struct perf_event *event, struct perf_event_context *ctx)
 {
     struct perf_event *parent_event = event->parent;
     unsigned long detach_flags = 0;
 
     if (parent_event) {
         /*
          * Do not destroy the 'original' grouping; because of the
          * context switch optimization the original events could've
          * ended up in a random child task.
          *
          * If we were to destroy the original group, all group related
          * operations would cease to function properly after this
          * random child dies.
          *
          * Do destroy all inherited groups, we don't care about those
          * and being thorough is better.
          */
         detach_flags = DETACH_GROUP | DETACH_CHILD;
         mutex_lock(&parent_event->child_mutex);
     }
 
     perf_remove_from_context(event, detach_flags);
 
     raw_spin_lock_irq(&ctx->lock);
     if (event->state > PERF_EVENT_STATE_EXIT)
         perf_event_set_state(event, PERF_EVENT_STATE_EXIT);
     raw_spin_unlock_irq(&ctx->lock);
 
     /*
      * Child events can be freed.
      */
     if (parent_event) {
         mutex_unlock(&parent_event->child_mutex);
         /*
          * Kick perf_poll() for is_event_hup();
          */
         perf_event_wakeup(parent_event);
         free_event(event);
         put_event(parent_event);
         return;
     }
 
     /*
      * Parent events are governed by their filedesc, retain them.
      */
     perf_event_wakeup(event);
 }
 
 static void perf_event_exit_task_context(struct task_struct *child, int ctxn)
 {
     struct perf_event_context *child_ctx, *clone_ctx = NULL;
     struct perf_event *child_event, *next;
 
     WARN_ON_ONCE(child != current);
 
     child_ctx = perf_pin_task_context(child, ctxn);
     if (!child_ctx)
         return;
 
     /*
      * In order to reduce the amount of tricky in ctx tear-down, we hold
      * ctx::mutex over the entire thing. This serializes against almost
      * everything that wants to access the ctx.
      *
      * The exception is sys_perf_event_open() /
      * perf_event_create_kernel_count() which does find_get_context()
      * without ctx::mutex (it cannot because of the move_group double mutex
      * lock thing). See the comments in perf_install_in_context().
      */
     mutex_lock(&child_ctx->mutex);
 
     /*
      * In a single ctx::lock section, de-schedule the events and detach the
      * context from the task such that we cannot ever get it scheduled back
      * in.
      */
     raw_spin_lock_irq(&child_ctx->lock);
     task_ctx_sched_out(__get_cpu_context(child_ctx), child_ctx, EVENT_ALL);
 
     /*
      * Now that the context is inactive, destroy the task <-> ctx relation
      * and mark the context dead.
      */
     RCU_INIT_POINTER(child->perf_event_ctxp[ctxn], NULL);
     put_ctx(child_ctx); /* cannot be last */
     WRITE_ONCE(child_ctx->task, TASK_TOMBSTONE);
     put_task_struct(current); /* cannot be last */
 
     clone_ctx = unclone_ctx(child_ctx);
     raw_spin_unlock_irq(&child_ctx->lock);
 
     if (clone_ctx)
         put_ctx(clone_ctx);
 
     /*
      * Report the task dead after unscheduling the events so that we
      * won't get any samples after PERF_RECORD_EXIT. We can however still
      * get a few PERF_RECORD_READ events.
      */
     perf_event_task(child, child_ctx, 0);
 
     list_for_each_entry_safe(child_event, next, &child_ctx->event_list, event_entry)
         perf_event_exit_event(child_event, child_ctx);
 
     mutex_unlock(&child_ctx->mutex);
 
     put_ctx(child_ctx);
 }
 
 /*
  * When a child task exits, feed back event values to parent events.
  *
  * Can be called with exec_update_lock held when called from
  * setup_new_exec().
  */
 void perf_event_exit_task(struct task_struct *child)
 {
     struct perf_event *event, *tmp;
     int ctxn;
 
     mutex_lock(&child->perf_event_mutex);
     list_for_each_entry_safe(event, tmp, &child->perf_event_list,
                  owner_entry) {
         list_del_init(&event->owner_entry);
 
         /*
          * Ensure the list deletion is visible before we clear
          * the owner, closes a race against perf_release() where
          * we need to serialize on the owner->perf_event_mutex.
          */
         smp_store_release(&event->owner, NULL);
     }
     mutex_unlock(&child->perf_event_mutex);
 
     for_each_task_context_nr(ctxn)
         perf_event_exit_task_context(child, ctxn);
 
     /*
      * The perf_event_exit_task_context calls perf_event_task
      * with child's task_ctx, which generates EXIT events for
      * child contexts and sets child->perf_event_ctxp[] to NULL.
      * At this point we need to send EXIT events to cpu contexts.
      */
     perf_event_task(child, NULL, 0);
 }
 
 static void perf_free_event(struct perf_event *event,
                 struct perf_event_context *ctx)
 {
     struct perf_event *parent = event->parent;
 
     if (WARN_ON_ONCE(!parent))
         return;
 
     mutex_lock(&parent->child_mutex);
     list_del_init(&event->child_list);
     mutex_unlock(&parent->child_mutex);
 
     put_event(parent);
 
     raw_spin_lock_irq(&ctx->lock);
     perf_group_detach(event);
     list_del_event(event, ctx);
     raw_spin_unlock_irq(&ctx->lock);
     free_event(event);
 }
 
 /*
  * Free a context as created by inheritance by perf_event_init_task() below,
  * used by fork() in case of fail.
  *
  * Even though the task has never lived, the context and events have been
  * exposed through the child_list, so we must take care tearing it all down.
  */
 void perf_event_free_task(struct task_struct *task)
 {
     struct perf_event_context *ctx;
     struct perf_event *event, *tmp;
     int ctxn;
 
     for_each_task_context_nr(ctxn) {
         ctx = task->perf_event_ctxp[ctxn];
         if (!ctx)
             continue;
 
         mutex_lock(&ctx->mutex);
         raw_spin_lock_irq(&ctx->lock);
         /*
          * Destroy the task <-> ctx relation and mark the context dead.
          *
          * This is important because even though the task hasn't been
          * exposed yet the context has been (through child_list).
          */
         RCU_INIT_POINTER(task->perf_event_ctxp[ctxn], NULL);
         WRITE_ONCE(ctx->task, TASK_TOMBSTONE);
         put_task_struct(task); /* cannot be last */
         raw_spin_unlock_irq(&ctx->lock);
 
         list_for_each_entry_safe(event, tmp, &ctx->event_list, event_entry)
             perf_free_event(event, ctx);
 
         mutex_unlock(&ctx->mutex);
 
         /*
          * perf_event_release_kernel() could've stolen some of our
          * child events and still have them on its free_list. In that
          * case we must wait for these events to have been freed (in
          * particular all their references to this task must've been
          * dropped).
          *
          * Without this copy_process() will unconditionally free this
          * task (irrespective of its reference count) and
          * _free_event()'s put_task_struct(event->hw.target) will be a
          * use-after-free.
          *
          * Wait for all events to drop their context reference.
          */
         wait_var_event(&ctx->refcount, refcount_read(&ctx->refcount) == 1);
         put_ctx(ctx); /* must be last */
     }
 }
 
 void perf_event_delayed_put(struct task_struct *task)
 {
     int ctxn;
 
     for_each_task_context_nr(ctxn)
         WARN_ON_ONCE(task->perf_event_ctxp[ctxn]);
 }
 
 struct file *perf_event_get(unsigned int fd)
 {
     struct file *file = fget(fd);
     if (!file)
         return ERR_PTR(-EBADF);
 
     if (file->f_op != &perf_fops) {
         fput(file);
         return ERR_PTR(-EBADF);
     }
 
     return file;
 }
 
 const struct perf_event *perf_get_event(struct file *file)
 {
     if (file->f_op != &perf_fops)
         return ERR_PTR(-EINVAL);
 
     return file->private_data;
 }
 
 const struct perf_event_attr *perf_event_attrs(struct perf_event *event)
 {
     if (!event)
         return ERR_PTR(-EINVAL);
 
     return &event->attr;
 }
 
 /*
  * Inherit an event from parent task to child task.
  *
  * Returns:
  *  - valid pointer on success
  *  - NULL for orphaned events
  *  - IS_ERR() on error
  */
 static struct perf_event *
 inherit_event(struct perf_event *parent_event,
           struct task_struct *parent,
           struct perf_event_context *parent_ctx,
           struct task_struct *child,
           struct perf_event *group_leader,
           struct perf_event_context *child_ctx)
 {
     enum perf_event_state parent_state = parent_event->state;
     struct perf_event *child_event;
     unsigned long flags;
 
     /*
      * Instead of creating recursive hierarchies of events,
      * we link inherited events back to the original parent,
      * which has a filp for sure, which we use as the reference
      * count:
      */
     if (parent_event->parent)
         parent_event = parent_event->parent;
 
     child_event = perf_event_alloc(&parent_event->attr,
                        parent_event->cpu,
                        child,
                        group_leader, parent_event,
                        NULL, NULL, -1);
     if (IS_ERR(child_event))
         return child_event;
 
 
     if ((child_event->attach_state & PERF_ATTACH_TASK_DATA) &&
         !child_ctx->task_ctx_data) {
         struct pmu *pmu = child_event->pmu;
 
         child_ctx->task_ctx_data = alloc_task_ctx_data(pmu);
         if (!child_ctx->task_ctx_data) {
             free_event(child_event);
             return ERR_PTR(-ENOMEM);
         }
     }
 
     /*
      * is_orphaned_event() and list_add_tail(&parent_event->child_list)
      * must be under the same lock in order to serialize against
      * perf_event_release_kernel(), such that either we must observe
      * is_orphaned_event() or they will observe us on the child_list.
      */
     mutex_lock(&parent_event->child_mutex);
     if (is_orphaned_event(parent_event) ||
         !atomic_long_inc_not_zero(&parent_event->refcount)) {
         mutex_unlock(&parent_event->child_mutex);
         /* task_ctx_data is freed with child_ctx */
         free_event(child_event);
         return NULL;
     }
 
     get_ctx(child_ctx);
 
     /*
      * Make the child state follow the state of the parent event,
      * not its attr.disabled bit.  We hold the parent's mutex,
      * so we won't race with perf_event_{en, dis}able_family.
      */
     if (parent_state >= PERF_EVENT_STATE_INACTIVE)
         child_event->state = PERF_EVENT_STATE_INACTIVE;
     else
         child_event->state = PERF_EVENT_STATE_OFF;
 
     if (parent_event->attr.freq) {
         u64 sample_period = parent_event->hw.sample_period;
         struct hw_perf_event *hwc = &child_event->hw;
 
         hwc->sample_period = sample_period;
         hwc->last_period   = sample_period;
 
         local64_set(&hwc->period_left, sample_period);
     }
 
     child_event->ctx = child_ctx;
     child_event->overflow_handler = parent_event->overflow_handler;
     child_event->overflow_handler_context
         = parent_event->overflow_handler_context;
 
     /*
      * Precalculate sample_data sizes
      */
     perf_event__header_size(child_event);
     perf_event__id_header_size(child_event);
 
     /*
      * Link it up in the child's context:
      */
     raw_spin_lock_irqsave(&child_ctx->lock, flags);
     add_event_to_ctx(child_event, child_ctx);
     child_event->attach_state |= PERF_ATTACH_CHILD;
     raw_spin_unlock_irqrestore(&child_ctx->lock, flags);
 
     /*
      * Link this into the parent event's child list
      */
     list_add_tail(&child_event->child_list, &parent_event->child_list);
     mutex_unlock(&parent_event->child_mutex);
 
     return child_event;
 }
 
 /*
  * Inherits an event group.
  *
  * This will quietly suppress orphaned events; !inherit_event() is not an error.
  * This matches with perf_event_release_kernel() removing all child events.
  *
  * Returns:
  *  - 0 on success
  *  - <0 on error
  */
 static int inherit_group(struct perf_event *parent_event,
           struct task_struct *parent,
           struct perf_event_context *parent_ctx,
           struct task_struct *child,
           struct perf_event_context *child_ctx)
 {
     struct perf_event *leader;
     struct perf_event *sub;
     struct perf_event *child_ctr;
 
     leader = inherit_event(parent_event, parent, parent_ctx,
                  child, NULL, child_ctx);
     if (IS_ERR(leader))
         return PTR_ERR(leader);
     /*
      * @leader can be NULL here because of is_orphaned_event(). In this
      * case inherit_event() will create individual events, similar to what
      * perf_group_detach() would do anyway.
      */
     for_each_sibling_event(sub, parent_event) {
         child_ctr = inherit_event(sub, parent, parent_ctx,
                         child, leader, child_ctx);
         if (IS_ERR(child_ctr))
             return PTR_ERR(child_ctr);
 
         if (sub->aux_event == parent_event && child_ctr &&
             !perf_get_aux_event(child_ctr, leader))
             return -EINVAL;
     }
     return 0;
 }
 
 /*
  * Creates the child task context and tries to inherit the event-group.
  *
  * Clears @inherited_all on !attr.inherited or error. Note that we'll leave
  * inherited_all set when we 'fail' to inherit an orphaned event; this is
  * consistent with perf_event_release_kernel() removing all child events.
  *
  * Returns:
  *  - 0 on success
  *  - <0 on error
  */
 static int
 inherit_task_group(struct perf_event *event, struct task_struct *parent,
            struct perf_event_context *parent_ctx,
            struct task_struct *child, int ctxn,
            u64 clone_flags, int *inherited_all)
 {
     int ret;
     struct perf_event_context *child_ctx;
 
     if (!event->attr.inherit ||
         (event->attr.inherit_thread && !(clone_flags & CLONE_THREAD)) ||
         /* Do not inherit if sigtrap and signal handlers were cleared. */
         (event->attr.sigtrap && (clone_flags & CLONE_CLEAR_SIGHAND))) {
         *inherited_all = 0;
         return 0;
     }
 
     child_ctx = child->perf_event_ctxp[ctxn];
     if (!child_ctx) {
         /*
          * This is executed from the parent task context, so
          * inherit events that have been marked for cloning.
          * First allocate and initialize a context for the
          * child.
          */
         child_ctx = alloc_perf_context(parent_ctx->pmu, child);
         if (!child_ctx)
             return -ENOMEM;
 
         child->perf_event_ctxp[ctxn] = child_ctx;
     }
 
     ret = inherit_group(event, parent, parent_ctx,
                 child, child_ctx);
 
     if (ret)
         *inherited_all = 0;
 
     return ret;
 }
 
 /*
  * Initialize the perf_event context in task_struct
  */
 static int perf_event_init_context(struct task_struct *child, int ctxn,
                    u64 clone_flags)
 {
     struct perf_event_context *child_ctx, *parent_ctx;
     struct perf_event_context *cloned_ctx;
     struct perf_event *event;
     struct task_struct *parent = current;
     int inherited_all = 1;
     unsigned long flags;
     int ret = 0;
 
     if (likely(!parent->perf_event_ctxp[ctxn]))
         return 0;
 
     /*
      * If the parent's context is a clone, pin it so it won't get
      * swapped under us.
      */
     parent_ctx = perf_pin_task_context(parent, ctxn);
     if (!parent_ctx)
         return 0;
 
     /*
      * No need to check if parent_ctx != NULL here; since we saw
      * it non-NULL earlier, the only reason for it to become NULL
      * is if we exit, and since we're currently in the middle of
      * a fork we can't be exiting at the same time.
      */
 
     /*
      * Lock the parent list. No need to lock the child - not PID
      * hashed yet and not running, so nobody can access it.
      */
     mutex_lock(&parent_ctx->mutex);
 
     /*
      * We dont have to disable NMIs - we are only looking at
      * the list, not manipulating it:
      */
     perf_event_groups_for_each(event, &parent_ctx->pinned_groups) {
         ret = inherit_task_group(event, parent, parent_ctx,
                      child, ctxn, clone_flags,
                      &inherited_all);
         if (ret)
             goto out_unlock;
     }
 
     /*
      * We can't hold ctx->lock when iterating the ->flexible_group list due
      * to allocations, but we need to prevent rotation because
      * rotate_ctx() will change the list from interrupt context.
      */
     raw_spin_lock_irqsave(&parent_ctx->lock, flags);
     parent_ctx->rotate_disable = 1;
     raw_spin_unlock_irqrestore(&parent_ctx->lock, flags);
 
     perf_event_groups_for_each(event, &parent_ctx->flexible_groups) {
         ret = inherit_task_group(event, parent, parent_ctx,
                      child, ctxn, clone_flags,
                      &inherited_all);
         if (ret)
             goto out_unlock;
     }
 
     raw_spin_lock_irqsave(&parent_ctx->lock, flags);
     parent_ctx->rotate_disable = 0;
 
     child_ctx = child->perf_event_ctxp[ctxn];
 
     if (child_ctx && inherited_all) {
         /*
          * Mark the child context as a clone of the parent
          * context, or of whatever the parent is a clone of.
          *
          * Note that if the parent is a clone, the holding of
          * parent_ctx->lock avoids it from being uncloned.
          */
         cloned_ctx = parent_ctx->parent_ctx;
         if (cloned_ctx) {
             child_ctx->parent_ctx = cloned_ctx;
             child_ctx->parent_gen = parent_ctx->parent_gen;
         } else {
             child_ctx->parent_ctx = parent_ctx;
             child_ctx->parent_gen = parent_ctx->generation;
         }
         get_ctx(child_ctx->parent_ctx);
     }
 
     raw_spin_unlock_irqrestore(&parent_ctx->lock, flags);
 out_unlock:
     mutex_unlock(&parent_ctx->mutex);
 
     perf_unpin_context(parent_ctx);
     put_ctx(parent_ctx);
 
     return ret;
 }
 
 /*
  * Initialize the perf_event context in task_struct
  */
 int perf_event_init_task(struct task_struct *child, u64 clone_flags)
 {
     int ctxn, ret;
 
     memset(child->perf_event_ctxp, 0, sizeof(child->perf_event_ctxp));
     mutex_init(&child->perf_event_mutex);
     INIT_LIST_HEAD(&child->perf_event_list);
 
     for_each_task_context_nr(ctxn) {
         ret = perf_event_init_context(child, ctxn, clone_flags);
         if (ret) {
             perf_event_free_task(child);
             return ret;
         }
     }
 
     return 0;
 }
 
 static void __init perf_event_init_all_cpus(void)
 {
     struct swevent_htable *swhash;
     int cpu;
 
     zalloc_cpumask_var(&perf_online_mask, GFP_KERNEL);
 
     for_each_possible_cpu(cpu) {
         swhash = &per_cpu(swevent_htable, cpu);
         mutex_init(&swhash->hlist_mutex);
         INIT_LIST_HEAD(&per_cpu(active_ctx_list, cpu));
 
         INIT_LIST_HEAD(&per_cpu(pmu_sb_events.list, cpu));
         raw_spin_lock_init(&per_cpu(pmu_sb_events.lock, cpu));
 
 #ifdef CONFIG_CGROUP_PERF
         INIT_LIST_HEAD(&per_cpu(cgrp_cpuctx_list, cpu));
 #endif
         INIT_LIST_HEAD(&per_cpu(sched_cb_list, cpu));
     }
 }
 
 static void perf_swevent_init_cpu(unsigned int cpu)
 {
     struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
 
     mutex_lock(&swhash->hlist_mutex);
     if (swhash->hlist_refcount > 0 && !swevent_hlist_deref(swhash)) {
         struct swevent_hlist *hlist;
 
         hlist = kzalloc_node(sizeof(*hlist), GFP_KERNEL, cpu_to_node(cpu));
         WARN_ON(!hlist);
         rcu_assign_pointer(swhash->swevent_hlist, hlist);
     }
     mutex_unlock(&swhash->hlist_mutex);
 }
 
 #if defined CONFIG_HOTPLUG_CPU || defined CONFIG_KEXEC_CORE
 static void __perf_event_exit_context(void *__info)
 {
     struct perf_event_context *ctx = __info;
     struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
     struct perf_event *event;
 
     raw_spin_lock(&ctx->lock);
     ctx_sched_out(ctx, cpuctx, EVENT_TIME);
     list_for_each_entry(event, &ctx->event_list, event_entry)
         __perf_remove_from_context(event, cpuctx, ctx, (void *)DETACH_GROUP);
     raw_spin_unlock(&ctx->lock);
 }
 
 static void perf_event_exit_cpu_context(int cpu)
 {
     struct perf_cpu_context *cpuctx;
     struct perf_event_context *ctx;
     struct pmu *pmu;
 
     mutex_lock(&pmus_lock);
     list_for_each_entry(pmu, &pmus, entry) {
         cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
         ctx = &cpuctx->ctx;
 
         mutex_lock(&ctx->mutex);
         smp_call_function_single(cpu, __perf_event_exit_context, ctx, 1);
         cpuctx->online = 0;
         mutex_unlock(&ctx->mutex);
     }
     cpumask_clear_cpu(cpu, perf_online_mask);
     mutex_unlock(&pmus_lock);
 }
 #else
 
 static void perf_event_exit_cpu_context(int cpu) { }
 
 #endif
 
 int perf_event_init_cpu(unsigned int cpu)
 {
     struct perf_cpu_context *cpuctx;
     struct perf_event_context *ctx;
     struct pmu *pmu;
 
     perf_swevent_init_cpu(cpu);
 
     mutex_lock(&pmus_lock);
     cpumask_set_cpu(cpu, perf_online_mask);
     list_for_each_entry(pmu, &pmus, entry) {
         cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
         ctx = &cpuctx->ctx;
 
         mutex_lock(&ctx->mutex);
         cpuctx->online = 1;
         mutex_unlock(&ctx->mutex);
     }
     mutex_unlock(&pmus_lock);
 
     return 0;
 }
 
 int perf_event_exit_cpu(unsigned int cpu)
 {
     perf_event_exit_cpu_context(cpu);
     return 0;
 }
 
 static int
 perf_reboot(struct notifier_block *notifier, unsigned long val, void *v)
 {
     int cpu;
 
     for_each_online_cpu(cpu)
         perf_event_exit_cpu(cpu);
 
     return NOTIFY_OK;
 }
 
 /*
  * Run the perf reboot notifier at the very last possible moment so that
  * the generic watchdog code runs as long as possible.
  */
 static struct notifier_block perf_reboot_notifier = {
     .notifier_call = perf_reboot,
     .priority = INT_MIN,
 };
 
 void __init perf_event_init(void)
 {
     int ret;
 
     idr_init(&pmu_idr);
 
     perf_event_init_all_cpus();
     init_srcu_struct(&pmus_srcu);
     perf_pmu_register(&perf_swevent, "software", PERF_TYPE_SOFTWARE);
     perf_pmu_register(&perf_cpu_clock, NULL, -1);
     perf_pmu_register(&perf_task_clock, NULL, -1);
     perf_tp_register();
     perf_event_init_cpu(smp_processor_id());
     register_reboot_notifier(&perf_reboot_notifier);
 
     ret = init_hw_breakpoint();
     WARN(ret, "hw_breakpoint initialization failed with: %d", ret);
 
     perf_event_cache = KMEM_CACHE(perf_event, SLAB_PANIC);
 
     /*
      * Build time assertion that we keep the data_head at the intended
      * location.  IOW, validation we got the __reserved[] size right.
      */
     BUILD_BUG_ON((offsetof(struct perf_event_mmap_page, data_head))
              != 1024);
 }
 
 ssize_t perf_event_sysfs_show(struct device *dev, struct device_attribute *attr,
                   char *page)
 {
     struct perf_pmu_events_attr *pmu_attr =
         container_of(attr, struct perf_pmu_events_attr, attr);
 
     if (pmu_attr->event_str)
         return sprintf(page, "%s\n", pmu_attr->event_str);
 
     return 0;
 }
 EXPORT_SYMBOL_GPL(perf_event_sysfs_show);
 
 static int __init perf_event_sysfs_init(void)
 {
     struct pmu *pmu;
     int ret;
 
     mutex_lock(&pmus_lock);
 
     ret = bus_register(&pmu_bus);
     if (ret)
         goto unlock;
 
     list_for_each_entry(pmu, &pmus, entry) {
         if (!pmu->name || pmu->type < 0)
             continue;
 
         ret = pmu_dev_alloc(pmu);
         WARN(ret, "Failed to register pmu: %s, reason %d\n", pmu->name, ret);
     }
     pmu_bus_running = 1;
     ret = 0;
 
 unlock:
     mutex_unlock(&pmus_lock);
 
     return ret;
 }
 device_initcall(perf_event_sysfs_init);
 
 #ifdef CONFIG_CGROUP_PERF
 static struct cgroup_subsys_state *
 perf_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
 {
     struct perf_cgroup *jc;
 
     jc = kzalloc(sizeof(*jc), GFP_KERNEL);
     if (!jc)
         return ERR_PTR(-ENOMEM);
 
     jc->info = alloc_percpu(struct perf_cgroup_info);
     if (!jc->info) {
         kfree(jc);
         return ERR_PTR(-ENOMEM);
     }
 
     return &jc->css;
 }
 
 static void perf_cgroup_css_free(struct cgroup_subsys_state *css)
 {
     struct perf_cgroup *jc = container_of(css, struct perf_cgroup, css);
 
     free_percpu(jc->info);
     kfree(jc);
 }
 
 static int perf_cgroup_css_online(struct cgroup_subsys_state *css)
 {
     perf_event_cgroup(css->cgroup);
     return 0;
 }
 
 static int __perf_cgroup_move(void *info)
 {
     struct task_struct *task = info;
     rcu_read_lock();
     perf_cgroup_switch(task);
     rcu_read_unlock();
     return 0;
 }
 
 static void perf_cgroup_attach(struct cgroup_taskset *tset)
 {
     struct task_struct *task;
     struct cgroup_subsys_state *css;
 
     cgroup_taskset_for_each(task, css, tset)
         task_function_call(task, __perf_cgroup_move, task);
 }
 
 struct cgroup_subsys perf_event_cgrp_subsys = {
     .css_alloc  = perf_cgroup_css_alloc,
     .css_free   = perf_cgroup_css_free,
     .css_online = perf_cgroup_css_online,
     .attach     = perf_cgroup_attach,
     /*
      * Implicitly enable on dfl hierarchy so that perf events can
      * always be filtered by cgroup2 path as long as perf_event
      * controller is not mounted on a legacy hierarchy.
      */
     .implicit_on_dfl = true,
     .threaded   = true,
 };
 #endif /* CONFIG_CGROUP_PERF */
 
 DEFINE_STATIC_CALL_RET0(perf_snapshot_branch_stack, perf_snapshot_branch_stack_t);