release/src-rt-6.x.4708/linux/linux-2.6.36/arch/mips/kernel/stacktrace.c

   1 /*
   2  * Stack trace management functions
   3  *
   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/module.h>
   9 #include <asm/stacktrace.h>
  10
  11 /*
  12  * Save stack-backtrace addresses into a stack_trace buffer:
  13  */
  14 static void save_raw_context_stack(struct stack_trace *trace,
  15         unsigned long reg29)
  16 {
  17         unsigned long *sp = (unsigned long *)reg29;
  18         unsigned long addr;
  19
  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;
  29                 }
  30         }
  31 }
  32
  33 static void save_context_stack(struct stack_trace *trace,
  34         struct task_struct *tsk, 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(tsk);
  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(tsk, &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         save_stack_trace_tsk(current, trace);
  69 }
  70 EXPORT_SYMBOL_GPL(save_stack_trace);
  71
  72 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
  73 {
  74         struct pt_regs dummyregs;
  75         struct pt_regs *regs = &dummyregs;
  76
  77         WARN_ON(trace->nr_entries || !trace->max_entries);
  78
  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);
  86 }
  87 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);