Pileus Git - ~andy/linux/blob - 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 struct pt_regs * save_context_stack(struct stack_trace *trace,
  35         struct task_struct *task, struct pt_regs *regs)
  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         unsigned long stack_page =
  42                 (unsigned long)task_stack_page(task);
  43         extern void ret_from_irq(void);
  44         extern void ret_from_exception(void);
  45
  46         if (raw_show_trace || !__kernel_text_address(pc)) {
  47                 if (stack_page && sp >= stack_page &&
  48                     sp <= stack_page + THREAD_SIZE - 32)
  49                         save_raw_context_stack(trace, sp);
  50                 return NULL;
  51         }
  52         do {
  53                 if (trace->skip > 0)
  54                         trace->skip--;
  55                 else
  56                         trace->entries[trace->nr_entries++] = pc;
  57                 if (trace->nr_entries >= trace->max_entries)
  58                         break;
  59                 /*
  60                  * If we reached the bottom of interrupt context,
  61                  * return saved pt_regs.
  62                  */
  63                 if (pc == (unsigned long)ret_from_irq ||
  64                     pc == (unsigned long)ret_from_exception) {
  65                         if (stack_page && sp >= stack_page &&
  66                             sp <= stack_page + THREAD_SIZE - 32)
  67                                 return (struct pt_regs *)sp;
  68                         break;
  69                 }
  70                 pc = unwind_stack(task, &sp, pc, ra);
  71                 ra = 0;
  72         } while (pc);
  73 #else
  74         save_raw_context_stack(sp);
  75 #endif
  76
  77         return NULL;
  78 }
  79
  80 /*
  81  * Save stack-backtrace addresses into a stack_trace buffer.
  82  */
  83 void save_stack_trace(struct stack_trace *trace, struct task_struct *task)
  84 {
  85         struct pt_regs dummyregs;
  86         struct pt_regs *regs = &dummyregs;
  87
  88         WARN_ON(trace->nr_entries || !trace->max_entries);
  89
  90         if (task && task != current) {
  91                 regs->regs[29] = task->thread.reg29;
  92                 regs->regs[31] = 0;
  93                 regs->cp0_epc = task->thread.reg31;
  94         } else {
  95                 if (!task)
  96                         task = current;
  97                 prepare_frametrace(regs);
  98         }
  99
 100         while (1) {
 101                 regs = save_context_stack(trace, task, regs);
 102                 if (!regs || trace->nr_entries >= trace->max_entries)
 103                         break;
 104         }
 105 }