1/* libunwind - a platform-independent unwind library
2   Copyright (C) 2012 Tommi Rantala <tt.rantala@gmail.com>
3
4This file is part of libunwind.
5
6Permission is hereby granted, free of charge, to any person obtaining
7a copy of this software and associated documentation files (the
8"Software"), to deal in the Software without restriction, including
9without limitation the rights to use, copy, modify, merge, publish,
10distribute, sublicense, and/or sell copies of the Software, and to
11permit persons to whom the Software is furnished to do so, subject to
12the following conditions:
13
14The above copyright notice and this permission notice shall be
15included in all copies or substantial portions of the Software.
16
17THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
18EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
19MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
20NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
21LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
22OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
23WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
24
25#include "unwind_i.h"
26
27/* Disassembly of the Linux VDSO sigreturn functions:
28
2900000000 <__kernel_sigreturn>:
30   0:   05 93           mov.w   e <__kernel_sigreturn+0xe>,r3   ! 77
31   2:   10 c3           trapa   #16
32   4:   0b 20           or      r0,r0
33   6:   0b 20           or      r0,r0
34   8:   0b 20           or      r0,r0
35   a:   0b 20           or      r0,r0
36   c:   0b 20           or      r0,r0
37   e:   77 00           .word 0x0077
38  10:   09 00           nop
39  12:   09 00           nop
40  14:   09 00           nop
41  16:   09 00           nop
42  18:   09 00           nop
43  1a:   09 00           nop
44  1c:   09 00           nop
45  1e:   09 00           nop
46
4700000020 <__kernel_rt_sigreturn>:
48  20:   05 93           mov.w   2e <__kernel_rt_sigreturn+0xe>,r3       ! ad
49  22:   10 c3           trapa   #16
50  24:   0b 20           or      r0,r0
51  26:   0b 20           or      r0,r0
52  28:   0b 20           or      r0,r0
53  2a:   0b 20           or      r0,r0
54  2c:   0b 20           or      r0,r0
55  2e:   ad 00           mov.w   @(r0,r10),r0
56  30:   09 00           nop
57  32:   09 00           nop
58  34:   09 00           nop
59  36:   09 00           nop
60  38:   09 00           nop
61  3a:   09 00           nop
62  3c:   09 00           nop
63  3e:   09 00           nop
64*/
65
66PROTECTED int
67unw_is_signal_frame (unw_cursor_t *cursor)
68{
69#ifdef __linux__
70  struct cursor *c = (struct cursor *) cursor;
71  unw_word_t w0, ip;
72  unw_addr_space_t as;
73  unw_accessors_t *a;
74  void *arg;
75  int ret;
76
77  as = c->dwarf.as;
78  a = unw_get_accessors (as);
79  arg = c->dwarf.as_arg;
80
81  ip = c->dwarf.ip;
82
83  ret = (*a->access_mem) (as, ip, &w0, 0, arg);
84  if (ret < 0)
85    return ret;
86
87  if (w0 != 0xc3109305)
88    return 0;
89
90  ret = (*a->access_mem) (as, ip+4, &w0, 0, arg);
91  if (ret < 0)
92    return ret;
93
94  if (w0 != 0x200b200b)
95    return 0;
96
97  ret = (*a->access_mem) (as, ip+8, &w0, 0, arg);
98  if (ret < 0)
99    return ret;
100
101  if (w0 != 0x200b200b)
102    return 0;
103
104  ret = (*a->access_mem) (as, ip+12, &w0, 0, arg);
105  if (ret < 0)
106    return ret;
107
108  if (w0 == 0x0077200b)
109    return 1; /* non-RT */
110  else if (w0 == 0x00ad200b)
111    return 2; /* RT */
112
113  /* does not look like a signal frame */
114  return 0;
115
116#else
117  return -UNW_ENOINFO;
118#endif
119}
120