simplify the stacktrace code
[linux-3.10.git] / arch / mips / kernel / stacktrace.c
1 /*
2  * arch/mips/kernel/stacktrace.c
3  *
4  * Stack trace management functions
5  *
6  *  Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
7  */
8 #include <linux/sched.h>
9 #include <linux/stacktrace.h>
10 #include <asm/stacktrace.h>
11
12 /*
13  * Save stack-backtrace addresses into a stack_trace buffer:
14  */
15 static void save_raw_context_stack(struct stack_trace *trace,
16         unsigned long reg29)
17 {
18         unsigned long *sp = (unsigned long *)reg29;
19         unsigned long addr;
20
21         while (!kstack_end(sp)) {
22                 addr = *sp++;
23                 if (__kernel_text_address(addr)) {
24                         if (trace->skip > 0)
25                                 trace->skip--;
26                         else
27                                 trace->entries[trace->nr_entries++] = addr;
28                         if (trace->nr_entries >= trace->max_entries)
29                                 break;
30                 }
31         }
32 }
33
34 static void save_context_stack(struct stack_trace *trace, struct pt_regs *regs)
35 {
36         unsigned long sp = regs->regs[29];
37 #ifdef CONFIG_KALLSYMS
38         unsigned long ra = regs->regs[31];
39         unsigned long pc = regs->cp0_epc;
40
41         if (raw_show_trace || !__kernel_text_address(pc)) {
42                 unsigned long stack_page =
43                         (unsigned long)task_stack_page(current);
44                 if (stack_page && sp >= stack_page &&
45                     sp <= stack_page + THREAD_SIZE - 32)
46                         save_raw_context_stack(trace, sp);
47                 return;
48         }
49         do {
50                 if (trace->skip > 0)
51                         trace->skip--;
52                 else
53                         trace->entries[trace->nr_entries++] = pc;
54                 if (trace->nr_entries >= trace->max_entries)
55                         break;
56                 pc = unwind_stack(current, &sp, pc, &ra);
57         } while (pc);
58 #else
59         save_raw_context_stack(trace, sp);
60 #endif
61 }
62
63 /*
64  * Save stack-backtrace addresses into a stack_trace buffer.
65  */
66 void save_stack_trace(struct stack_trace *trace)
67 {
68         struct pt_regs dummyregs;
69         struct pt_regs *regs = &dummyregs;
70
71         WARN_ON(trace->nr_entries || !trace->max_entries);
72
73         prepare_frametrace(regs);
74         save_context_stack(trace, regs);
75 }