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 #include <asm/asm-offsets.h>
  17
  18 /*
  19  * Save stack-backtrace addresses into a stack_trace buffer.
  20  */
  21 void save_stack_trace(struct stack_trace *trace)
  22 {
  23         unsigned long sp;
  24
  25         asm("mr %0,1" : "=r" (sp));
  26
  27         for (;;) {
  28                 unsigned long *stack = (unsigned long *) sp;
  29                 unsigned long newsp, ip;
  30
  31                 if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
  32                         return;
  33
  34                 newsp = stack[0];
  35                 ip = stack[STACK_FRAME_LR_SAVE];
  36
  37                 if (!trace->skip)
  38                         trace->entries[trace->nr_entries++] = ip;
  39                 else
  40                         trace->skip--;
  41
  42                 if (trace->nr_entries >= trace->max_entries)
  43                         return;
  44
  45                 sp = newsp;
  46         }
  47 }