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