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/sched/task_stack.h>
   9 #include <linux/stacktrace.h>
  10 #include <linux/export.h>
  11 #include <asm/stacktrace.h>
  12
  13 /*
  14  * Save stack-backtrace addresses into a stack_trace buffer:
  15  */
  16 static void save_raw_context_stack(struct stack_trace *trace,
  17         unsigned long reg29, int savesched)
  18 {
  19         unsigned long *sp = (unsigned long *)reg29;
  20         unsigned long addr;
  21
  22         while (!kstack_end(sp)) {
  23                 addr = *sp++;
  24                 if (__kernel_text_address(addr) &&
  25                     (savesched || !in_sched_functions(addr))) {
  26                         if (trace->skip > 0)
  27                                 trace->skip--;
  28                         else
  29                                 trace->entries[trace->nr_entries++] = addr;
  30                         if (trace->nr_entries >= trace->max_entries)
  31                                 break;
  32                 }
  33         }
  34 }
  35
  36 static void save_context_stack(struct stack_trace *trace,
  37         struct task_struct *tsk, struct pt_regs *regs, int savesched)
  38 {
  39         unsigned long sp = regs->regs[29];
  40 #ifdef CONFIG_KALLSYMS
  41         unsigned long ra = regs->regs[31];
  42         unsigned long pc = regs->cp0_epc;
  43
  44         if (raw_show_trace || !__kernel_text_address(pc)) {
  45                 unsigned long stack_page =
  46                         (unsigned long)task_stack_page(tsk);
  47                 if (stack_page && sp >= stack_page &&
  48                     sp <= stack_page + THREAD_SIZE - 32)
  49                         save_raw_context_stack(trace, sp, savesched);
  50                 return;
  51         }
  52         do {
  53                 if (savesched || !in_sched_functions(pc)) {
  54                         if (trace->skip > 0)
  55                                 trace->skip--;
  56                         else
  57                                 trace->entries[trace->nr_entries++] = pc;
  58                         if (trace->nr_entries >= trace->max_entries)
  59                                 break;
  60                 }
  61                 pc = unwind_stack(tsk, &sp, pc, &ra);
  62         } while (pc);
  63 #else
  64         save_raw_context_stack(trace, sp, savesched);
  65 #endif
  66 }
  67
  68 /*
  69  * Save stack-backtrace addresses into a stack_trace buffer.
  70  */
  71 void save_stack_trace(struct stack_trace *trace)
  72 {
  73         save_stack_trace_tsk(current, trace);
  74 }
  75 EXPORT_SYMBOL_GPL(save_stack_trace);
  76
  77 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
  78 {
  79         struct pt_regs dummyregs;
  80         struct pt_regs *regs = &dummyregs;
  81
  82         WARN_ON(trace->nr_entries || !trace->max_entries);
  83
  84         if (tsk != current) {
  85                 regs->regs[29] = tsk->thread.reg29;
  86                 regs->regs[31] = 0;
  87                 regs->cp0_epc = tsk->thread.reg31;
  88         } else
  89                 prepare_frametrace(regs);
  90         save_context_stack(trace, tsk, regs, tsk == current);
  91 }
  92 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);