Merge branch 'x86/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux...
[linux-2.6.git] / 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 <linux/module.h>
16 #include <asm/ptrace.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 }
48 EXPORT_SYMBOL_GPL(save_stack_trace);