kernel/2.6.29.6-aldebaran-rt/arch/arm/kernel/return_address.c

   1 #include <linux/module.h>
   2 #include <linux/sched.h>
   3
   4 #include "stacktrace.h"
   5
   6 struct return_address_data {
   7         unsigned int level;
   8         void *addr;
   9 };
  10
  11 static int save_return_addr(struct stackframe *frame, void *d)
  12 {
  13         struct return_address_data *data = d;
  14
  15         if (!data->level) {
  16                 data->addr = (void *)frame->lr;
  17
  18                 return 1;
  19         } else {
  20                 --data->level;
  21                 return 0;
  22         }
  23 }
  24
  25 void *return_address(unsigned int level)
  26 {
  27         unsigned long fp, base;
  28         struct return_address_data data;
  29
  30         data.level = level + 1;
  31
  32         base = (unsigned long)task_stack_page(current);
  33         asm("mov %0, fp" : "=r" (fp));
  34
  35         walk_stackframe(fp, base, base + THREAD_SIZE, save_return_addr, &data);
  36
  37         if (!data.level)
  38                 return data.addr;
  39         else
  40                 return NULL;
  41 }
  42 EXPORT_SYMBOL_GPL(return_address);