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/sched/debug.h>
   8 #include <linux/stacktrace.h>
   9 #include <linux/export.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, int savesched)
  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                     (savesched || !in_sched_functions(addr))) {
  25                         if (trace->skip > 0)
  26                                 trace->skip--;
  27                         else
  28                                 trace->entries[trace->nr_entries++] = addr;
  29                         if (trace->nr_entries >= trace->max_entries)
  30                                 break;
  31                 }
  32         }
  33 }
  34
  35 static void save_context_stack(struct stack_trace *trace,
  36         struct task_struct *tsk, struct pt_regs *regs, int savesched)
  37 {
  38         unsigned long sp = regs->regs[29];
  39 #ifdef CONFIG_KALLSYMS
  40         unsigned long ra = regs->regs[31];
  41         unsigned long pc = regs->cp0_epc;
  42
  43         if (raw_show_trace || !__kernel_text_address(pc)) {
  44                 unsigned long stack_page =
  45                         (unsigned long)task_stack_page(tsk);
  46                 if (stack_page && sp >= stack_page &&
  47                     sp <= stack_page + THREAD_SIZE - 32)
  48                         save_raw_context_stack(trace, sp, savesched);
  49                 return;
  50         }
  51         do {
  52                 if (savesched || !in_sched_functions(pc)) {
  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                 pc = unwind_stack(tsk, &sp, pc, &ra);
  61         } while (pc);
  62 #else
  63         save_raw_context_stack(trace, sp, savesched);
  64 #endif
  65 }
  66
  67 /*
  68  * Save stack-backtrace addresses into a stack_trace buffer.
  69  */
  70 void save_stack_trace(struct stack_trace *trace)
  71 {
  72         save_stack_trace_tsk(current, trace);
  73 }
  74 EXPORT_SYMBOL_GPL(save_stack_trace);
  75
  76 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
  77 {
  78         struct pt_regs dummyregs;
  79         struct pt_regs *regs = &dummyregs;
  80
  81         WARN_ON(trace->nr_entries || !trace->max_entries);
  82
  83         if (tsk != current) {
  84                 regs->regs[29] = tsk->thread.reg29;
  85                 regs->regs[31] = 0;
  86                 regs->cp0_epc = tsk->thread.reg31;
  87         } else
  88                 prepare_frametrace(regs);
  89         save_context_stack(trace, tsk, regs, tsk == current);
  90 }
  91 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);