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/sched.h>
  14 #include <linux/stacktrace.h>
  15 #include <asm/ptrace.h>
  16
  17 /*
  18  * Save stack-backtrace addresses into a stack_trace buffer.
  19  */
  20 void save_stack_trace(struct stack_trace *trace)
  21 {
  22         unsigned long sp;
  23
  24         asm("mr %0,1" : "=r" (sp));
  25
  26         for (;;) {
  27                 unsigned long *stack = (unsigned long *) sp;
  28                 unsigned long newsp, ip;
  29
  30                 if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
  31                         return;
  32
  33                 newsp = stack[0];
  34                 ip = stack[STACK_FRAME_LR_SAVE];
  35
  36                 if (!trace->skip)
  37                         trace->entries[trace->nr_entries++] = ip;
  38                 else
  39                         trace->skip--;
  40
  41                 if (trace->nr_entries >= trace->max_entries)
  42                         return;
  43
  44                 sp = newsp;
  45         }
  46 }