arch/powerpc/kernel/stacktrace.c

   1 /*
   2  * Stack trace utility
   3  *
   4  * Copyright 2008 Christoph Hellwig, IBM Corp.
   5  *
   6  *
   7  *      This program is free software; you can redistribute it and/or
   8  *      modify it under the terms of the GNU General Public License
   9  *      as published by the Free Software Foundation; either version
  10  *      2 of the License, or (at your option) any later version.
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/sched.h>
  15 #include <linux/stacktrace.h>
  16 #include <asm/ptrace.h>
  17 #include <asm/processor.h>
  18
  19 /*
  20  * Save stack-backtrace addresses into a stack_trace buffer.
  21  */
  22 static void save_context_stack(struct stack_trace *trace, unsigned long sp,
  23                         struct task_struct *tsk, int savesched)
  24 {
  25         for (;;) {
  26                 unsigned long *stack = (unsigned long *) sp;
  27                 unsigned long newsp, ip;
  28
  29                 if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD))
  30                         return;
  31
  32                 newsp = stack[0];
  33                 ip = stack[STACK_FRAME_LR_SAVE];
  34
  35                 if (savesched || !in_sched_functions(ip)) {
  36                         if (!trace->skip)
  37                                 trace->entries[trace->nr_entries++] = ip;
  38                         else
  39                                 trace->skip--;
  40                 }
  41
  42                 if (trace->nr_entries >= trace->max_entries)
  43                         return;
  44
  45                 sp = newsp;
  46         }
  47 }
  48
  49 void save_stack_trace(struct stack_trace *trace)
  50 {
  51         unsigned long sp;
  52
  53         asm("mr %0,1" : "=r" (sp));
  54
  55         save_context_stack(trace, sp, current, 1);
  56 }
  57 EXPORT_SYMBOL_GPL(save_stack_trace);
  58
  59 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
  60 {
  61         save_context_stack(trace, tsk->thread.ksp, tsk, 0);
  62 }
  63 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);