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stacktrace.c

/*
 * Stack trace utility
 *
 * Copyright 2008 Christoph Hellwig, IBM Corp.
 *
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/stacktrace.h>
#include <asm/ptrace.h>
#include <asm/processor.h>

/*
 * Save stack-backtrace addresses into a stack_trace buffer.
 */
static void save_context_stack(struct stack_trace *trace, unsigned long sp,
                  struct task_struct *tsk, int savesched)
{
      for (;;) {
            unsigned long *stack = (unsigned long *) sp;
            unsigned long newsp, ip;

            if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD))
                  return;

            newsp = stack[0];
            ip = stack[STACK_FRAME_LR_SAVE];

            if (savesched || !in_sched_functions(ip)) {
                  if (!trace->skip)
                        trace->entries[trace->nr_entries++] = ip;
                  else
                        trace->skip--;
            }

            if (trace->nr_entries >= trace->max_entries)
                  return;

            sp = newsp;
      }
}

void save_stack_trace(struct stack_trace *trace)
{
      unsigned long sp;

      asm("mr %0,1" : "=r" (sp));

      save_context_stack(trace, sp, current, 1);
}
EXPORT_SYMBOL_GPL(save_stack_trace);

void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
{
      save_context_stack(trace, tsk->thread.ksp, tsk, 0);
}
EXPORT_SYMBOL_GPL(save_stack_trace_tsk);

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