Linux Kernel  3.7.1
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return_address.c
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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  if (!tmp)
28  return NULL;
29 
30  if (frame)
31  dwarf_free_frame(frame);
32 
33  frame = tmp;
34 
35  if (!frame || !frame->return_addr)
36  break;
37 
38  ra = frame->return_addr;
39  }
40 
41  /* Failed to unwind the stack to the specified depth. */
42  WARN_ON(i != depth + 1);
43 
44  if (frame)
45  dwarf_free_frame(frame);
46 
47  return (void *)ra;
48 }
49 
50 #else
51 
52 void *return_address(unsigned int depth)
53 {
54  return NULL;
55 }
56 
57 #endif
58