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/export.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, int savesched)
  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                     (savesched || !in_sched_functions(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,
  35         struct task_struct *tsk, struct pt_regs *regs, int savesched)
  36 {
  37         unsigned long sp = regs->regs[29];
  38 #ifdef CONFIG_KALLSYMS
  39         unsigned long ra = regs->regs[31];
  40         unsigned long pc = regs->cp0_epc;
  41
  42         if (raw_show_trace || !__kernel_text_address(pc)) {
  43                 unsigned long stack_page =
  44                         (unsigned long)task_stack_page(tsk);
  45                 if (stack_page && sp >= stack_page &&
  46                     sp <= stack_page + THREAD_SIZE - 32)
  47                         save_raw_context_stack(trace, sp, savesched);
  48                 return;
  49         }
  50         do {
  51                 if (savesched || !in_sched_functions(pc)) {
  52                         if (trace->skip > 0)
  53                                 trace->skip--;
  54                         else
  55                                 trace->entries[trace->nr_entries++] = pc;
  56                         if (trace->nr_entries >= trace->max_entries)
  57                                 break;
  58                 }
  59                 pc = unwind_stack(tsk, &sp, pc, &ra);
  60         } while (pc);
  61 #else
  62         save_raw_context_stack(trace, sp, savesched);
  63 #endif
  64 }
  65
  66 /*
  67  * Save stack-backtrace addresses into a stack_trace buffer.
  68  */
  69 void save_stack_trace(struct stack_trace *trace)
  70 {
  71         save_stack_trace_tsk(current, trace);
  72 }
  73 EXPORT_SYMBOL_GPL(save_stack_trace);
  74
  75 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
  76 {
  77         struct pt_regs dummyregs;
  78         struct pt_regs *regs = &dummyregs;
  79
  80         WARN_ON(trace->nr_entries || !trace->max_entries);
  81
  82         if (tsk != current) {
  83                 regs->regs[29] = tsk->thread.reg29;
  84                 regs->regs[31] = 0;
  85                 regs->cp0_epc = tsk->thread.reg31;
  86         } else
  87                 prepare_frametrace(regs);
  88         save_context_stack(trace, tsk, regs, tsk == current);
  89 }
  90 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);