ARM: mmp: fix potential NULL dereference
[linux/fpc-iii.git] / arch / mips / kernel / stacktrace.c
blob1ba775d24d38f890d4e29a2168b533870d7cfb8b
1 /*
2 * Stack trace management functions
4 * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
5 */
6 #include <linux/sched.h>
7 #include <linux/stacktrace.h>
8 #include <linux/export.h>
9 #include <asm/stacktrace.h>
12 * Save stack-backtrace addresses into a stack_trace buffer:
14 static void save_raw_context_stack(struct stack_trace *trace,
15 unsigned long reg29)
17 unsigned long *sp = (unsigned long *)reg29;
18 unsigned long addr;
20 while (!kstack_end(sp)) {
21 addr = *sp++;
22 if (__kernel_text_address(addr)) {
23 if (trace->skip > 0)
24 trace->skip--;
25 else
26 trace->entries[trace->nr_entries++] = addr;
27 if (trace->nr_entries >= trace->max_entries)
28 break;
33 static void save_context_stack(struct stack_trace *trace,
34 struct task_struct *tsk, struct pt_regs *regs)
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;
41 if (raw_show_trace || !__kernel_text_address(pc)) {
42 unsigned long stack_page =
43 (unsigned long)task_stack_page(tsk);
44 if (stack_page && sp >= stack_page &&
45 sp <= stack_page + THREAD_SIZE - 32)
46 save_raw_context_stack(trace, sp);
47 return;
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(tsk, &sp, pc, &ra);
57 } while (pc);
58 #else
59 save_raw_context_stack(trace, sp);
60 #endif
64 * Save stack-backtrace addresses into a stack_trace buffer.
66 void save_stack_trace(struct stack_trace *trace)
68 save_stack_trace_tsk(current, trace);
70 EXPORT_SYMBOL_GPL(save_stack_trace);
72 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
74 struct pt_regs dummyregs;
75 struct pt_regs *regs = &dummyregs;
77 WARN_ON(trace->nr_entries || !trace->max_entries);
79 if (tsk != current) {
80 regs->regs[29] = tsk->thread.reg29;
81 regs->regs[31] = 0;
82 regs->cp0_epc = tsk->thread.reg31;
83 } else
84 prepare_frametrace(regs);
85 save_context_stack(trace, tsk, regs);
87 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);