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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-only
 /* Copyright (c) 2020 Facebook */
 
 #include <linux/init.h>
 #include <linux/namei.h>
 #include <linux/pid_namespace.h>
 #include <linux/fs.h>
 #include <linux/fdtable.h>
 #include <linux/filter.h>
 #include <linux/btf_ids.h>
 #include "mmap_unlock_work.h"
 
 struct bpf_iter_seq_task_common {
     struct pid_namespace *ns;
 };
 
 struct bpf_iter_seq_task_info {
     /* The first field must be struct bpf_iter_seq_task_common.
      * this is assumed by {init, fini}_seq_pidns() callback functions.
      */
     struct bpf_iter_seq_task_common common;
     u32 tid;
 };
 
 static struct task_struct *task_seq_get_next(struct pid_namespace *ns,
                          u32 *tid,
                          bool skip_if_dup_files)
 {
     struct task_struct *task = NULL;
     struct pid *pid;
 
     rcu_read_lock();
 retry:
     pid = find_ge_pid(*tid, ns);
     if (pid) {
         *tid = pid_nr_ns(pid, ns);
         task = get_pid_task(pid, PIDTYPE_PID);
         if (!task) {
             ++*tid;
             goto retry;
         } else if (skip_if_dup_files && !thread_group_leader(task) &&
                task->files == task->group_leader->files) {
             put_task_struct(task);
             task = NULL;
             ++*tid;
             goto retry;
         }
     }
     rcu_read_unlock();
 
     return task;
 }
 
 static void *task_seq_start(struct seq_file *seq, loff_t *pos)
 {
     struct bpf_iter_seq_task_info *info = seq->private;
     struct task_struct *task;
 
     task = task_seq_get_next(info->common.ns, &info->tid, false);
     if (!task)
         return NULL;
 
     if (*pos == 0)
         ++*pos;
     return task;
 }
 
 static void *task_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 {
     struct bpf_iter_seq_task_info *info = seq->private;
     struct task_struct *task;
 
     ++*pos;
     ++info->tid;
     put_task_struct((struct task_struct *)v);
     task = task_seq_get_next(info->common.ns, &info->tid, false);
     if (!task)
         return NULL;
 
     return task;
 }
 
 struct bpf_iter__task {
     __bpf_md_ptr(struct bpf_iter_meta *, meta);
     __bpf_md_ptr(struct task_struct *, task);
 };
 
 DEFINE_BPF_ITER_FUNC(task, struct bpf_iter_meta *meta, struct task_struct *task)
 
 static int __task_seq_show(struct seq_file *seq, struct task_struct *task,
                bool in_stop)
 {
     struct bpf_iter_meta meta;
     struct bpf_iter__task ctx;
     struct bpf_prog *prog;
 
     meta.seq = seq;
     prog = bpf_iter_get_info(&meta, in_stop);
     if (!prog)
         return 0;
 
     ctx.meta = &meta;
     ctx.task = task;
     return bpf_iter_run_prog(prog, &ctx);
 }
 
 static int task_seq_show(struct seq_file *seq, void *v)
 {
     return __task_seq_show(seq, v, false);
 }
 
 static void task_seq_stop(struct seq_file *seq, void *v)
 {
     if (!v)
         (void)__task_seq_show(seq, v, true);
     else
         put_task_struct((struct task_struct *)v);
 }
 
 static const struct seq_operations task_seq_ops = {
     .start  = task_seq_start,
     .next   = task_seq_next,
     .stop   = task_seq_stop,
     .show   = task_seq_show,
 };
 
 struct bpf_iter_seq_task_file_info {
     /* The first field must be struct bpf_iter_seq_task_common.
      * this is assumed by {init, fini}_seq_pidns() callback functions.
      */
     struct bpf_iter_seq_task_common common;
     struct task_struct *task;
     u32 tid;
     u32 fd;
 };
 
 static struct file *
 task_file_seq_get_next(struct bpf_iter_seq_task_file_info *info)
 {
     struct pid_namespace *ns = info->common.ns;
     u32 curr_tid = info->tid;
     struct task_struct *curr_task;
     unsigned int curr_fd = info->fd;
 
     /* If this function returns a non-NULL file object,
      * it held a reference to the task/file.
      * Otherwise, it does not hold any reference.
      */
 again:
     if (info->task) {
         curr_task = info->task;
         curr_fd = info->fd;
     } else {
                 curr_task = task_seq_get_next(ns, &curr_tid, true);
                 if (!curr_task) {
                         info->task = NULL;
                         info->tid = curr_tid;
                         return NULL;
                 }
 
                 /* set info->task and info->tid */
         info->task = curr_task;
         if (curr_tid == info->tid) {
             curr_fd = info->fd;
         } else {
             info->tid = curr_tid;
             curr_fd = 0;
         }
     }
 
     rcu_read_lock();
     for (;; curr_fd++) {
         struct file *f;
         f = task_lookup_next_fd_rcu(curr_task, &curr_fd);
         if (!f)
             break;
         if (!get_file_rcu(f))
             continue;
 
         /* set info->fd */
         info->fd = curr_fd;
         rcu_read_unlock();
         return f;
     }
 
     /* the current task is done, go to the next task */
     rcu_read_unlock();
     put_task_struct(curr_task);
     info->task = NULL;
     info->fd = 0;
     curr_tid = ++(info->tid);
     goto again;
 }
 
 static void *task_file_seq_start(struct seq_file *seq, loff_t *pos)
 {
     struct bpf_iter_seq_task_file_info *info = seq->private;
     struct file *file;
 
     info->task = NULL;
     file = task_file_seq_get_next(info);
     if (file && *pos == 0)
         ++*pos;
 
     return file;
 }
 
 static void *task_file_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 {
     struct bpf_iter_seq_task_file_info *info = seq->private;
 
     ++*pos;
     ++info->fd;
     fput((struct file *)v);
     return task_file_seq_get_next(info);
 }
 
 struct bpf_iter__task_file {
     __bpf_md_ptr(struct bpf_iter_meta *, meta);
     __bpf_md_ptr(struct task_struct *, task);
     u32 fd __aligned(8);
     __bpf_md_ptr(struct file *, file);
 };
 
 DEFINE_BPF_ITER_FUNC(task_file, struct bpf_iter_meta *meta,
              struct task_struct *task, u32 fd,
              struct file *file)
 
 static int __task_file_seq_show(struct seq_file *seq, struct file *file,
                 bool in_stop)
 {
     struct bpf_iter_seq_task_file_info *info = seq->private;
     struct bpf_iter__task_file ctx;
     struct bpf_iter_meta meta;
     struct bpf_prog *prog;
 
     meta.seq = seq;
     prog = bpf_iter_get_info(&meta, in_stop);
     if (!prog)
         return 0;
 
     ctx.meta = &meta;
     ctx.task = info->task;
     ctx.fd = info->fd;
     ctx.file = file;
     return bpf_iter_run_prog(prog, &ctx);
 }
 
 static int task_file_seq_show(struct seq_file *seq, void *v)
 {
     return __task_file_seq_show(seq, v, false);
 }
 
 static void task_file_seq_stop(struct seq_file *seq, void *v)
 {
     struct bpf_iter_seq_task_file_info *info = seq->private;
 
     if (!v) {
         (void)__task_file_seq_show(seq, v, true);
     } else {
         fput((struct file *)v);
         put_task_struct(info->task);
         info->task = NULL;
     }
 }
 
 static int init_seq_pidns(void *priv_data, struct bpf_iter_aux_info *aux)
 {
     struct bpf_iter_seq_task_common *common = priv_data;
 
     common->ns = get_pid_ns(task_active_pid_ns(current));
     return 0;
 }
 
 static void fini_seq_pidns(void *priv_data)
 {
     struct bpf_iter_seq_task_common *common = priv_data;
 
     put_pid_ns(common->ns);
 }
 
 static const struct seq_operations task_file_seq_ops = {
     .start  = task_file_seq_start,
     .next   = task_file_seq_next,
     .stop   = task_file_seq_stop,
     .show   = task_file_seq_show,
 };
 
 struct bpf_iter_seq_task_vma_info {
     /* The first field must be struct bpf_iter_seq_task_common.
      * this is assumed by {init, fini}_seq_pidns() callback functions.
      */
     struct bpf_iter_seq_task_common common;
     struct task_struct *task;
     struct vm_area_struct *vma;
     u32 tid;
     unsigned long prev_vm_start;
     unsigned long prev_vm_end;
 };
 
 enum bpf_task_vma_iter_find_op {
     task_vma_iter_first_vma,   /* use mm->mmap */
     task_vma_iter_next_vma,    /* use curr_vma->vm_next */
     task_vma_iter_find_vma,    /* use find_vma() to find next vma */
 };
 
 static struct vm_area_struct *
 task_vma_seq_get_next(struct bpf_iter_seq_task_vma_info *info)
 {
     struct pid_namespace *ns = info->common.ns;
     enum bpf_task_vma_iter_find_op op;
     struct vm_area_struct *curr_vma;
     struct task_struct *curr_task;
     u32 curr_tid = info->tid;
 
     /* If this function returns a non-NULL vma, it holds a reference to
      * the task_struct, and holds read lock on vma->mm->mmap_lock.
      * If this function returns NULL, it does not hold any reference or
      * lock.
      */
     if (info->task) {
         curr_task = info->task;
         curr_vma = info->vma;
         /* In case of lock contention, drop mmap_lock to unblock
          * the writer.
          *
          * After relock, call find(mm, prev_vm_end - 1) to find
          * new vma to process.
          *
          *   +------+------+-----------+
          *   | VMA1 | VMA2 | VMA3      |
          *   +------+------+-----------+
          *   |      |      |           |
          *  4k     8k     16k         400k
          *
          * For example, curr_vma == VMA2. Before unlock, we set
          *
          *    prev_vm_start = 8k
          *    prev_vm_end   = 16k
          *
          * There are a few cases:
          *
          * 1) VMA2 is freed, but VMA3 exists.
          *
          *    find_vma() will return VMA3, just process VMA3.
          *
          * 2) VMA2 still exists.
          *
          *    find_vma() will return VMA2, process VMA2->next.
          *
          * 3) no more vma in this mm.
          *
          *    Process the next task.
          *
          * 4) find_vma() returns a different vma, VMA2'.
          *
          *    4.1) If VMA2 covers same range as VMA2', skip VMA2',
          *         because we already covered the range;
          *    4.2) VMA2 and VMA2' covers different ranges, process
          *         VMA2'.
          */
         if (mmap_lock_is_contended(curr_task->mm)) {
             info->prev_vm_start = curr_vma->vm_start;
             info->prev_vm_end = curr_vma->vm_end;
             op = task_vma_iter_find_vma;
             mmap_read_unlock(curr_task->mm);
             if (mmap_read_lock_killable(curr_task->mm))
                 goto finish;
         } else {
             op = task_vma_iter_next_vma;
         }
     } else {
 again:
         curr_task = task_seq_get_next(ns, &curr_tid, true);
         if (!curr_task) {
             info->tid = curr_tid + 1;
             goto finish;
         }
 
         if (curr_tid != info->tid) {
             info->tid = curr_tid;
             /* new task, process the first vma */
             op = task_vma_iter_first_vma;
         } else {
             /* Found the same tid, which means the user space
              * finished data in previous buffer and read more.
              * We dropped mmap_lock before returning to user
              * space, so it is necessary to use find_vma() to
              * find the next vma to process.
              */
             op = task_vma_iter_find_vma;
         }
 
         if (!curr_task->mm)
             goto next_task;
 
         if (mmap_read_lock_killable(curr_task->mm))
             goto finish;
     }
 
     switch (op) {
     case task_vma_iter_first_vma:
         curr_vma = curr_task->mm->mmap;
         break;
     case task_vma_iter_next_vma:
         curr_vma = curr_vma->vm_next;
         break;
     case task_vma_iter_find_vma:
         /* We dropped mmap_lock so it is necessary to use find_vma
          * to find the next vma. This is similar to the  mechanism
          * in show_smaps_rollup().
          */
         curr_vma = find_vma(curr_task->mm, info->prev_vm_end - 1);
         /* case 1) and 4.2) above just use curr_vma */
 
         /* check for case 2) or case 4.1) above */
         if (curr_vma &&
             curr_vma->vm_start == info->prev_vm_start &&
             curr_vma->vm_end == info->prev_vm_end)
             curr_vma = curr_vma->vm_next;
         break;
     }
     if (!curr_vma) {
         /* case 3) above, or case 2) 4.1) with vma->next == NULL */
         mmap_read_unlock(curr_task->mm);
         goto next_task;
     }
     info->task = curr_task;
     info->vma = curr_vma;
     return curr_vma;
 
 next_task:
     put_task_struct(curr_task);
     info->task = NULL;
     curr_tid++;
     goto again;
 
 finish:
     if (curr_task)
         put_task_struct(curr_task);
     info->task = NULL;
     info->vma = NULL;
     return NULL;
 }
 
 static void *task_vma_seq_start(struct seq_file *seq, loff_t *pos)
 {
     struct bpf_iter_seq_task_vma_info *info = seq->private;
     struct vm_area_struct *vma;
 
     vma = task_vma_seq_get_next(info);
     if (vma && *pos == 0)
         ++*pos;
 
     return vma;
 }
 
 static void *task_vma_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 {
     struct bpf_iter_seq_task_vma_info *info = seq->private;
 
     ++*pos;
     return task_vma_seq_get_next(info);
 }
 
 struct bpf_iter__task_vma {
     __bpf_md_ptr(struct bpf_iter_meta *, meta);
     __bpf_md_ptr(struct task_struct *, task);
     __bpf_md_ptr(struct vm_area_struct *, vma);
 };
 
 DEFINE_BPF_ITER_FUNC(task_vma, struct bpf_iter_meta *meta,
              struct task_struct *task, struct vm_area_struct *vma)
 
 static int __task_vma_seq_show(struct seq_file *seq, bool in_stop)
 {
     struct bpf_iter_seq_task_vma_info *info = seq->private;
     struct bpf_iter__task_vma ctx;
     struct bpf_iter_meta meta;
     struct bpf_prog *prog;
 
     meta.seq = seq;
     prog = bpf_iter_get_info(&meta, in_stop);
     if (!prog)
         return 0;
 
     ctx.meta = &meta;
     ctx.task = info->task;
     ctx.vma = info->vma;
     return bpf_iter_run_prog(prog, &ctx);
 }
 
 static int task_vma_seq_show(struct seq_file *seq, void *v)
 {
     return __task_vma_seq_show(seq, false);
 }
 
 static void task_vma_seq_stop(struct seq_file *seq, void *v)
 {
     struct bpf_iter_seq_task_vma_info *info = seq->private;
 
     if (!v) {
         (void)__task_vma_seq_show(seq, true);
     } else {
         /* info->vma has not been seen by the BPF program. If the
          * user space reads more, task_vma_seq_get_next should
          * return this vma again. Set prev_vm_start to ~0UL,
          * so that we don't skip the vma returned by the next
          * find_vma() (case task_vma_iter_find_vma in
          * task_vma_seq_get_next()).
          */
         info->prev_vm_start = ~0UL;
         info->prev_vm_end = info->vma->vm_end;
         mmap_read_unlock(info->task->mm);
         put_task_struct(info->task);
         info->task = NULL;
     }
 }
 
 static const struct seq_operations task_vma_seq_ops = {
     .start  = task_vma_seq_start,
     .next   = task_vma_seq_next,
     .stop   = task_vma_seq_stop,
     .show   = task_vma_seq_show,
 };
 
 static const struct bpf_iter_seq_info task_seq_info = {
     .seq_ops        = &task_seq_ops,
     .init_seq_private   = init_seq_pidns,
     .fini_seq_private   = fini_seq_pidns,
     .seq_priv_size      = sizeof(struct bpf_iter_seq_task_info),
 };
 
 static struct bpf_iter_reg task_reg_info = {
     .target         = "task",
     .feature        = BPF_ITER_RESCHED,
     .ctx_arg_info_size  = 1,
     .ctx_arg_info       = {
         { offsetof(struct bpf_iter__task, task),
           PTR_TO_BTF_ID_OR_NULL },
     },
     .seq_info       = &task_seq_info,
 };
 
 static const struct bpf_iter_seq_info task_file_seq_info = {
     .seq_ops        = &task_file_seq_ops,
     .init_seq_private   = init_seq_pidns,
     .fini_seq_private   = fini_seq_pidns,
     .seq_priv_size      = sizeof(struct bpf_iter_seq_task_file_info),
 };
 
 static struct bpf_iter_reg task_file_reg_info = {
     .target         = "task_file",
     .feature        = BPF_ITER_RESCHED,
     .ctx_arg_info_size  = 2,
     .ctx_arg_info       = {
         { offsetof(struct bpf_iter__task_file, task),
           PTR_TO_BTF_ID_OR_NULL },
         { offsetof(struct bpf_iter__task_file, file),
           PTR_TO_BTF_ID_OR_NULL },
     },
     .seq_info       = &task_file_seq_info,
 };
 
 static const struct bpf_iter_seq_info task_vma_seq_info = {
     .seq_ops        = &task_vma_seq_ops,
     .init_seq_private   = init_seq_pidns,
     .fini_seq_private   = fini_seq_pidns,
     .seq_priv_size      = sizeof(struct bpf_iter_seq_task_vma_info),
 };
 
 static struct bpf_iter_reg task_vma_reg_info = {
     .target         = "task_vma",
     .feature        = BPF_ITER_RESCHED,
     .ctx_arg_info_size  = 2,
     .ctx_arg_info       = {
         { offsetof(struct bpf_iter__task_vma, task),
           PTR_TO_BTF_ID_OR_NULL },
         { offsetof(struct bpf_iter__task_vma, vma),
           PTR_TO_BTF_ID_OR_NULL },
     },
     .seq_info       = &task_vma_seq_info,
 };
 
 BPF_CALL_5(bpf_find_vma, struct task_struct *, task, u64, start,
        bpf_callback_t, callback_fn, void *, callback_ctx, u64, flags)
 {
     struct mmap_unlock_irq_work *work = NULL;
     struct vm_area_struct *vma;
     bool irq_work_busy = false;
     struct mm_struct *mm;
     int ret = -ENOENT;
 
     if (flags)
         return -EINVAL;
 
     if (!task)
         return -ENOENT;
 
     mm = task->mm;
     if (!mm)
         return -ENOENT;
 
     irq_work_busy = bpf_mmap_unlock_get_irq_work(&work);
 
     if (irq_work_busy || !mmap_read_trylock(mm))
         return -EBUSY;
 
     vma = find_vma(mm, start);
 
     if (vma && vma->vm_start <= start && vma->vm_end > start) {
         callback_fn((u64)(long)task, (u64)(long)vma,
                 (u64)(long)callback_ctx, 0, 0);
         ret = 0;
     }
     bpf_mmap_unlock_mm(work, mm);
     return ret;
 }
 
 const struct bpf_func_proto bpf_find_vma_proto = {
     .func       = bpf_find_vma,
     .ret_type   = RET_INTEGER,
     .arg1_type  = ARG_PTR_TO_BTF_ID,
     .arg1_btf_id    = &btf_tracing_ids[BTF_TRACING_TYPE_TASK],
     .arg2_type  = ARG_ANYTHING,
     .arg3_type  = ARG_PTR_TO_FUNC,
     .arg4_type  = ARG_PTR_TO_STACK_OR_NULL,
     .arg5_type  = ARG_ANYTHING,
 };
 
 DEFINE_PER_CPU(struct mmap_unlock_irq_work, mmap_unlock_work);
 
 static void do_mmap_read_unlock(struct irq_work *entry)
 {
     struct mmap_unlock_irq_work *work;
 
     if (WARN_ON_ONCE(IS_ENABLED(CONFIG_PREEMPT_RT)))
         return;
 
     work = container_of(entry, struct mmap_unlock_irq_work, irq_work);
     mmap_read_unlock_non_owner(work->mm);
 }
 
 static int __init task_iter_init(void)
 {
     struct mmap_unlock_irq_work *work;
     int ret, cpu;
 
     for_each_possible_cpu(cpu) {
         work = per_cpu_ptr(&mmap_unlock_work, cpu);
         init_irq_work(&work->irq_work, do_mmap_read_unlock);
     }
 
     task_reg_info.ctx_arg_info[0].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_TASK];
     ret = bpf_iter_reg_target(&task_reg_info);
     if (ret)
         return ret;
 
     task_file_reg_info.ctx_arg_info[0].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_TASK];
     task_file_reg_info.ctx_arg_info[1].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_FILE];
     ret =  bpf_iter_reg_target(&task_file_reg_info);
     if (ret)
         return ret;
 
     task_vma_reg_info.ctx_arg_info[0].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_TASK];
     task_vma_reg_info.ctx_arg_info[1].btf_id = btf_tracing_ids[BTF_TRACING_TYPE_VMA];
     return bpf_iter_reg_target(&task_vma_reg_info);
 }
 late_initcall(task_iter_init);

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