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 <linux/module.h>
  17 #include <asm/ptrace.h>
  18 #include <asm/processor.h>
  19
  20 /*
  21  * Save stack-backtrace addresses into a stack_trace buffer.
  22  */
  23 static void save_context_stack(struct stack_trace *trace, unsigned long sp,
  24                         struct task_struct *tsk, int savesched)
  25 {
  26         for (;;) {
  27                 unsigned long *stack = (unsigned long *) sp;
  28                 unsigned long newsp, ip;
  29
  30                 if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD))
  31                         return;
  32
  33                 newsp = stack[0];
  34                 ip = stack[STACK_FRAME_LR_SAVE];
  35
  36                 if (savesched || !in_sched_functions(ip)) {
  37                         if (!trace->skip)
  38                                 trace->entries[trace->nr_entries++] = ip;
  39                         else
  40                                 trace->skip--;
  41                 }
  42
  43                 if (trace->nr_entries >= trace->max_entries)
  44                         return;
  45
  46                 sp = newsp;
  47         }
  48 }
  49
  50 void save_stack_trace(struct stack_trace *trace)
  51 {
  52         unsigned long sp;
  53
  54         asm("mr %0,1" : "=r" (sp));
  55
  56         save_context_stack(trace, sp, current, 1);
  57 }
  58 EXPORT_SYMBOL_GPL(save_stack_trace);
  59
  60 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
  61 {
  62         save_context_stack(trace, tsk->thread.regs->gpr[1], tsk, 0);
  63 }
  64 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);