Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland...
[linux-2.6] / 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 }