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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
 /*
  * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
  *
  */
 #include <linux/sched/task_stack.h>
 #include <linux/stacktrace.h>
 #include <linux/security.h>
 #include <linux/kallsyms.h>
 #include <linux/seq_file.h>
 #include <linux/spinlock.h>
 #include <linux/uaccess.h>
 #include <linux/ftrace.h>
 #include <linux/module.h>
 #include <linux/sysctl.h>
 #include <linux/init.h>
 
 #include <asm/setup.h>
 
 #include "trace.h"
 
 #define STACK_TRACE_ENTRIES 500
 
 static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES];
 static unsigned stack_trace_index[STACK_TRACE_ENTRIES];
 
 static unsigned int stack_trace_nr_entries;
 static unsigned long stack_trace_max_size;
 static arch_spinlock_t stack_trace_max_lock =
     (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
 
 DEFINE_PER_CPU(int, disable_stack_tracer);
 static DEFINE_MUTEX(stack_sysctl_mutex);
 
 int stack_tracer_enabled;
 
 static void print_max_stack(void)
 {
     long i;
     int size;
 
     pr_emerg("        Depth    Size   Location    (%d entries)\n"
                "        -----    ----   --------\n",
                stack_trace_nr_entries);
 
     for (i = 0; i < stack_trace_nr_entries; i++) {
         if (i + 1 == stack_trace_nr_entries)
             size = stack_trace_index[i];
         else
             size = stack_trace_index[i] - stack_trace_index[i+1];
 
         pr_emerg("%3ld) %8d   %5d   %pS\n", i, stack_trace_index[i],
                 size, (void *)stack_dump_trace[i]);
     }
 }
 
 /*
  * The stack tracer looks for a maximum stack at each call from a function. It
  * registers a callback from ftrace, and in that callback it examines the stack
  * size. It determines the stack size from the variable passed in, which is the
  * address of a local variable in the stack_trace_call() callback function.
  * The stack size is calculated by the address of the local variable to the top
  * of the current stack. If that size is smaller than the currently saved max
  * stack size, nothing more is done.
  *
  * If the size of the stack is greater than the maximum recorded size, then the
  * following algorithm takes place.
  *
  * For architectures (like x86) that store the function's return address before
  * saving the function's local variables, the stack will look something like
  * this:
  *
  *   [ top of stack ]
  *    0: sys call entry frame
  *   10: return addr to entry code
  *   11: start of sys_foo frame
  *   20: return addr to sys_foo
  *   21: start of kernel_func_bar frame
  *   30: return addr to kernel_func_bar
  *   31: [ do trace stack here ]
  *
  * The save_stack_trace() is called returning all the functions it finds in the
  * current stack. Which would be (from the bottom of the stack to the top):
  *
  *   return addr to kernel_func_bar
  *   return addr to sys_foo
  *   return addr to entry code
  *
  * Now to figure out how much each of these functions' local variable size is,
  * a search of the stack is made to find these values. When a match is made, it
  * is added to the stack_dump_trace[] array. The offset into the stack is saved
  * in the stack_trace_index[] array. The above example would show:
  *
  *        stack_dump_trace[]        |   stack_trace_index[]
  *        ------------------        +   -------------------
  *  return addr to kernel_func_bar  |          30
  *  return addr to sys_foo          |          20
  *  return addr to entry            |          10
  *
  * The print_max_stack() function above, uses these values to print the size of
  * each function's portion of the stack.
  *
  *  for (i = 0; i < nr_entries; i++) {
  *     size = i == nr_entries - 1 ? stack_trace_index[i] :
  *                    stack_trace_index[i] - stack_trace_index[i+1]
  *     print "%d %d %d %s\n", i, stack_trace_index[i], size, stack_dump_trace[i]);
  *  }
  *
  * The above shows
  *
  *     depth size  location
  *     ----- ----  --------
  *  0    30   10   kernel_func_bar
  *  1    20   10   sys_foo
  *  2    10   10   entry code
  *
  * Now for architectures that might save the return address after the functions
  * local variables (saving the link register before calling nested functions),
  * this will cause the stack to look a little different:
  *
  * [ top of stack ]
  *  0: sys call entry frame
  * 10: start of sys_foo_frame
  * 19: return addr to entry code << lr saved before calling kernel_func_bar
  * 20: start of kernel_func_bar frame
  * 29: return addr to sys_foo_frame << lr saved before calling next function
  * 30: [ do trace stack here ]
  *
  * Although the functions returned by save_stack_trace() may be the same, the
  * placement in the stack will be different. Using the same algorithm as above
  * would yield:
  *
  *        stack_dump_trace[]        |   stack_trace_index[]
  *        ------------------        +   -------------------
  *  return addr to kernel_func_bar  |          30
  *  return addr to sys_foo          |          29
  *  return addr to entry            |          19
  *
  * Where the mapping is off by one:
  *
  *   kernel_func_bar stack frame size is 29 - 19 not 30 - 29!
  *
  * To fix this, if the architecture sets ARCH_RET_ADDR_AFTER_LOCAL_VARS the
  * values in stack_trace_index[] are shifted by one to and the number of
  * stack trace entries is decremented by one.
  *
  *        stack_dump_trace[]        |   stack_trace_index[]
  *        ------------------        +   -------------------
  *  return addr to kernel_func_bar  |          29
  *  return addr to sys_foo          |          19
  *
  * Although the entry function is not displayed, the first function (sys_foo)
  * will still include the stack size of it.
  */
 static void check_stack(unsigned long ip, unsigned long *stack)
 {
     unsigned long this_size, flags; unsigned long *p, *top, *start;
     static int tracer_frame;
     int frame_size = READ_ONCE(tracer_frame);
     int i, x;
 
     this_size = ((unsigned long)stack) & (THREAD_SIZE-1);
     this_size = THREAD_SIZE - this_size;
     /* Remove the frame of the tracer */
     this_size -= frame_size;
 
     if (this_size <= stack_trace_max_size)
         return;
 
     /* we do not handle interrupt stacks yet */
     if (!object_is_on_stack(stack))
         return;
 
     /* Can't do this from NMI context (can cause deadlocks) */
     if (in_nmi())
         return;
 
     local_irq_save(flags);
     arch_spin_lock(&stack_trace_max_lock);
 
     /* In case another CPU set the tracer_frame on us */
     if (unlikely(!frame_size))
         this_size -= tracer_frame;
 
     /* a race could have already updated it */
     if (this_size <= stack_trace_max_size)
         goto out;
 
     stack_trace_max_size = this_size;
 
     stack_trace_nr_entries = stack_trace_save(stack_dump_trace,
                            ARRAY_SIZE(stack_dump_trace) - 1,
                            0);
 
     /* Skip over the overhead of the stack tracer itself */
     for (i = 0; i < stack_trace_nr_entries; i++) {
         if (stack_dump_trace[i] == ip)
             break;
     }
 
     /*
      * Some archs may not have the passed in ip in the dump.
      * If that happens, we need to show everything.
      */
     if (i == stack_trace_nr_entries)
         i = 0;
 
     /*
      * Now find where in the stack these are.
      */
     x = 0;
     start = stack;
     top = (unsigned long *)
         (((unsigned long)start & ~(THREAD_SIZE-1)) + THREAD_SIZE);
 
     /*
      * Loop through all the entries. One of the entries may
      * for some reason be missed on the stack, so we may
      * have to account for them. If they are all there, this
      * loop will only happen once. This code only takes place
      * on a new max, so it is far from a fast path.
      */
     while (i < stack_trace_nr_entries) {
         int found = 0;
 
         stack_trace_index[x] = this_size;
         p = start;
 
         for (; p < top && i < stack_trace_nr_entries; p++) {
             /*
              * The READ_ONCE_NOCHECK is used to let KASAN know that
              * this is not a stack-out-of-bounds error.
              */
             if ((READ_ONCE_NOCHECK(*p)) == stack_dump_trace[i]) {
                 stack_dump_trace[x] = stack_dump_trace[i++];
                 this_size = stack_trace_index[x++] =
                     (top - p) * sizeof(unsigned long);
                 found = 1;
                 /* Start the search from here */
                 start = p + 1;
                 /*
                  * We do not want to show the overhead
                  * of the stack tracer stack in the
                  * max stack. If we haven't figured
                  * out what that is, then figure it out
                  * now.
                  */
                 if (unlikely(!tracer_frame)) {
                     tracer_frame = (p - stack) *
                         sizeof(unsigned long);
                     stack_trace_max_size -= tracer_frame;
                 }
             }
         }
 
         if (!found)
             i++;
     }
 
 #ifdef ARCH_FTRACE_SHIFT_STACK_TRACER
     /*
      * Some archs will store the link register before calling
      * nested functions. This means the saved return address
      * comes after the local storage, and we need to shift
      * for that.
      */
     if (x > 1) {
         memmove(&stack_trace_index[0], &stack_trace_index[1],
             sizeof(stack_trace_index[0]) * (x - 1));
         x--;
     }
 #endif
 
     stack_trace_nr_entries = x;
 
     if (task_stack_end_corrupted(current)) {
         print_max_stack();
         BUG();
     }
 
  out:
     arch_spin_unlock(&stack_trace_max_lock);
     local_irq_restore(flags);
 }
 
 /* Some archs may not define MCOUNT_INSN_SIZE */
 #ifndef MCOUNT_INSN_SIZE
 # define MCOUNT_INSN_SIZE 0
 #endif
 
 static void
 stack_trace_call(unsigned long ip, unsigned long parent_ip,
          struct ftrace_ops *op, struct ftrace_regs *fregs)
 {
     unsigned long stack;
 
     preempt_disable_notrace();
 
     /* no atomic needed, we only modify this variable by this cpu */
     __this_cpu_inc(disable_stack_tracer);
     if (__this_cpu_read(disable_stack_tracer) != 1)
         goto out;
 
     /* If rcu is not watching, then save stack trace can fail */
     if (!rcu_is_watching())
         goto out;
 
     ip += MCOUNT_INSN_SIZE;
 
     check_stack(ip, &stack);
 
  out:
     __this_cpu_dec(disable_stack_tracer);
     /* prevent recursion in schedule */
     preempt_enable_notrace();
 }
 
 static struct ftrace_ops trace_ops __read_mostly =
 {
     .func = stack_trace_call,
 };
 
 static ssize_t
 stack_max_size_read(struct file *filp, char __user *ubuf,
             size_t count, loff_t *ppos)
 {
     unsigned long *ptr = filp->private_data;
     char buf[64];
     int r;
 
     r = snprintf(buf, sizeof(buf), "%ld\n", *ptr);
     if (r > sizeof(buf))
         r = sizeof(buf);
     return simple_read_from_buffer(ubuf, count, ppos, buf, r);
 }
 
 static ssize_t
 stack_max_size_write(struct file *filp, const char __user *ubuf,
              size_t count, loff_t *ppos)
 {
     long *ptr = filp->private_data;
     unsigned long val, flags;
     int ret;
 
     ret = kstrtoul_from_user(ubuf, count, 10, &val);
     if (ret)
         return ret;
 
     local_irq_save(flags);
 
     /*
      * In case we trace inside arch_spin_lock() or after (NMI),
      * we will cause circular lock, so we also need to increase
      * the percpu disable_stack_tracer here.
      */
     __this_cpu_inc(disable_stack_tracer);
 
     arch_spin_lock(&stack_trace_max_lock);
     *ptr = val;
     arch_spin_unlock(&stack_trace_max_lock);
 
     __this_cpu_dec(disable_stack_tracer);
     local_irq_restore(flags);
 
     return count;
 }
 
 static const struct file_operations stack_max_size_fops = {
     .open       = tracing_open_generic,
     .read       = stack_max_size_read,
     .write      = stack_max_size_write,
     .llseek     = default_llseek,
 };
 
 static void *
 __next(struct seq_file *m, loff_t *pos)
 {
     long n = *pos - 1;
 
     if (n >= stack_trace_nr_entries)
         return NULL;
 
     m->private = (void *)n;
     return &m->private;
 }
 
 static void *
 t_next(struct seq_file *m, void *v, loff_t *pos)
 {
     (*pos)++;
     return __next(m, pos);
 }
 
 static void *t_start(struct seq_file *m, loff_t *pos)
 {
     local_irq_disable();
 
     __this_cpu_inc(disable_stack_tracer);
 
     arch_spin_lock(&stack_trace_max_lock);
 
     if (*pos == 0)
         return SEQ_START_TOKEN;
 
     return __next(m, pos);
 }
 
 static void t_stop(struct seq_file *m, void *p)
 {
     arch_spin_unlock(&stack_trace_max_lock);
 
     __this_cpu_dec(disable_stack_tracer);
 
     local_irq_enable();
 }
 
 static void trace_lookup_stack(struct seq_file *m, long i)
 {
     unsigned long addr = stack_dump_trace[i];
 
     seq_printf(m, "%pS\n", (void *)addr);
 }
 
 static void print_disabled(struct seq_file *m)
 {
     seq_puts(m, "#\n"
          "#  Stack tracer disabled\n"
          "#\n"
          "# To enable the stack tracer, either add 'stacktrace' to the\n"
          "# kernel command line\n"
          "# or 'echo 1 > /proc/sys/kernel/stack_tracer_enabled'\n"
          "#\n");
 }
 
 static int t_show(struct seq_file *m, void *v)
 {
     long i;
     int size;
 
     if (v == SEQ_START_TOKEN) {
         seq_printf(m, "        Depth    Size   Location"
                "    (%d entries)\n"
                "        -----    ----   --------\n",
                stack_trace_nr_entries);
 
         if (!stack_tracer_enabled && !stack_trace_max_size)
             print_disabled(m);
 
         return 0;
     }
 
     i = *(long *)v;
 
     if (i >= stack_trace_nr_entries)
         return 0;
 
     if (i + 1 == stack_trace_nr_entries)
         size = stack_trace_index[i];
     else
         size = stack_trace_index[i] - stack_trace_index[i+1];
 
     seq_printf(m, "%3ld) %8d   %5d   ", i, stack_trace_index[i], size);
 
     trace_lookup_stack(m, i);
 
     return 0;
 }
 
 static const struct seq_operations stack_trace_seq_ops = {
     .start      = t_start,
     .next       = t_next,
     .stop       = t_stop,
     .show       = t_show,
 };
 
 static int stack_trace_open(struct inode *inode, struct file *file)
 {
     int ret;
 
     ret = security_locked_down(LOCKDOWN_TRACEFS);
     if (ret)
         return ret;
 
     return seq_open(file, &stack_trace_seq_ops);
 }
 
 static const struct file_operations stack_trace_fops = {
     .open       = stack_trace_open,
     .read       = seq_read,
     .llseek     = seq_lseek,
     .release    = seq_release,
 };
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 
 static int
 stack_trace_filter_open(struct inode *inode, struct file *file)
 {
     struct ftrace_ops *ops = inode->i_private;
 
     /* Checks for tracefs lockdown */
     return ftrace_regex_open(ops, FTRACE_ITER_FILTER,
                  inode, file);
 }
 
 static const struct file_operations stack_trace_filter_fops = {
     .open = stack_trace_filter_open,
     .read = seq_read,
     .write = ftrace_filter_write,
     .llseek = tracing_lseek,
     .release = ftrace_regex_release,
 };
 
 #endif /* CONFIG_DYNAMIC_FTRACE */
 
 int
 stack_trace_sysctl(struct ctl_table *table, int write, void *buffer,
            size_t *lenp, loff_t *ppos)
 {
     int was_enabled;
     int ret;
 
     mutex_lock(&stack_sysctl_mutex);
     was_enabled = !!stack_tracer_enabled;
 
     ret = proc_dointvec(table, write, buffer, lenp, ppos);
 
     if (ret || !write || (was_enabled == !!stack_tracer_enabled))
         goto out;
 
     if (stack_tracer_enabled)
         register_ftrace_function(&trace_ops);
     else
         unregister_ftrace_function(&trace_ops);
  out:
     mutex_unlock(&stack_sysctl_mutex);
     return ret;
 }
 
 static char stack_trace_filter_buf[COMMAND_LINE_SIZE+1] __initdata;
 
 static __init int enable_stacktrace(char *str)
 {
     int len;
 
     if ((len = str_has_prefix(str, "_filter=")))
         strncpy(stack_trace_filter_buf, str + len, COMMAND_LINE_SIZE);
 
     stack_tracer_enabled = 1;
     return 1;
 }
 __setup("stacktrace", enable_stacktrace);
 
 static __init int stack_trace_init(void)
 {
     int ret;
 
     ret = tracing_init_dentry();
     if (ret)
         return 0;
 
     trace_create_file("stack_max_size", TRACE_MODE_WRITE, NULL,
             &stack_trace_max_size, &stack_max_size_fops);
 
     trace_create_file("stack_trace", TRACE_MODE_READ, NULL,
             NULL, &stack_trace_fops);
 
 #ifdef CONFIG_DYNAMIC_FTRACE
     trace_create_file("stack_trace_filter", TRACE_MODE_WRITE, NULL,
               &trace_ops, &stack_trace_filter_fops);
 #endif
 
     if (stack_trace_filter_buf[0])
         ftrace_set_early_filter(&trace_ops, stack_trace_filter_buf, 1);
 
     if (stack_tracer_enabled)
         register_ftrace_function(&trace_ops);
 
     return 0;
 }
 
 device_initcall(stack_trace_init);

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