arch/arm/kernel/stacktrace.c

   1 #include <linux/module.h>
   2 #include <linux/sched.h>
   3 #include <linux/stacktrace.h>
   4
   5 #include "stacktrace.h"
   6
   7 int walk_stackframe(unsigned long fp, unsigned long low, unsigned long high,
   8                     int (*fn)(struct stackframe *, void *), void *data)
   9 {
  10         struct stackframe *frame;
  11
  12         do {
  13                 /*
  14                  * Check current frame pointer is within bounds
  15                  */
  16                 if (fp < (low + 12) || fp + 4 >= high)
  17                         break;
  18
  19                 frame = (struct stackframe *)(fp - 12);
  20
  21                 if (fn(frame, data))
  22                         break;
  23
  24                 /*
  25                  * Update the low bound - the next frame must always
  26                  * be at a higher address than the current frame.
  27                  */
  28                 low = fp + 4;
  29                 fp = frame->fp;
  30         } while (fp);
  31
  32         return 0;
  33 }
  34 EXPORT_SYMBOL(walk_stackframe);
  35
  36 #ifdef CONFIG_STACKTRACE
  37 struct stack_trace_data {
  38         struct stack_trace *trace;
  39         unsigned int no_sched_functions;
  40         unsigned int skip;
  41 };
  42
  43 static int save_trace(struct stackframe *frame, void *d)
  44 {
  45         struct stack_trace_data *data = d;
  46         struct stack_trace *trace = data->trace;
  47         unsigned long addr = frame->lr;
  48
  49         if (data->no_sched_functions && in_sched_functions(addr))
  50                 return 0;
  51         if (data->skip) {
  52                 data->skip--;
  53                 return 0;
  54         }
  55
  56         trace->entries[trace->nr_entries++] = addr;
  57
  58         return trace->nr_entries >= trace->max_entries;
  59 }
  60
  61 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
  62 {
  63         struct stack_trace_data data;
  64         unsigned long fp, base;
  65
  66         data.trace = trace;
  67         data.skip = trace->skip;
  68         base = (unsigned long)task_stack_page(tsk);
  69
  70         if (tsk != current) {
  71 #ifdef CONFIG_SMP
  72                 /*
  73                  * What guarantees do we have here that 'tsk'
  74                  * is not running on another CPU?
  75                  */
  76                 BUG();
  77 #else
  78                 data.no_sched_functions = 1;
  79                 fp = thread_saved_fp(tsk);
  80 #endif
  81         } else {
  82                 data.no_sched_functions = 0;
  83                 asm("mov %0, fp" : "=r" (fp));
  84         }
  85
  86         walk_stackframe(fp, base, base + THREAD_SIZE, save_trace, &data);
  87         if (trace->nr_entries < trace->max_entries)
  88                 trace->entries[trace->nr_entries++] = ULONG_MAX;
  89 }
  90
  91 void save_stack_trace(struct stack_trace *trace)
  92 {
  93         save_stack_trace_tsk(current, trace);
  94 }
  95 EXPORT_SYMBOL_GPL(save_stack_trace);
  96 #endif