arch/sh/kernel/return_address.c

   1 /*
   2  * arch/sh/kernel/return_address.c
   3  *
   4  * Copyright (C) 2009  Matt Fleming
   5  * Copyright (C) 2009  Paul Mundt
   6  *
   7  * This file is subject to the terms and conditions of the GNU General Public
   8  * License.  See the file "COPYING" in the main directory of this archive
   9  * for more details.
  10  */
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <asm/dwarf.h>
  14
  15 #ifdef CONFIG_DWARF_UNWINDER
  16
  17 void *return_address(unsigned int depth)
  18 {
  19         struct dwarf_frame *frame;
  20         unsigned long ra;
  21         int i;
  22
  23         for (i = 0, frame = NULL, ra = 0; i <= depth; i++) {
  24                 struct dwarf_frame *tmp;
  25
  26                 tmp = dwarf_unwind_stack(ra, frame);
  27
  28                 if (frame)
  29                         dwarf_free_frame(frame);
  30
  31                 frame = tmp;
  32
  33                 if (!frame || !frame->return_addr)
  34                         break;
  35
  36                 ra = frame->return_addr;
  37         }
  38
  39         /* Failed to unwind the stack to the specified depth. */
  40         WARN_ON(i != depth + 1);
  41
  42         if (frame)
  43                 dwarf_free_frame(frame);
  44
  45         return (void *)ra;
  46 }
  47
  48 #else
  49
  50 void *return_address(unsigned int depth)
  51 {
  52         return NULL;
  53 }
  54
  55 #endif
  56
  57 EXPORT_SYMBOL_GPL(return_address);