1 /* libunwind - a platform-independent unwind library
2 Copyright (C) 2012 Tommi Rantala <tt.rantala@gmail.com>
3
4 This file is part of libunwind.
5
6 Permission is hereby granted, free of charge, to any person obtaining
7 a copy of this software and associated documentation files (the
8 "Software"), to deal in the Software without restriction, including
9 without limitation the rights to use, copy, modify, merge, publish,
10 distribute, sublicense, and/or sell copies of the Software, and to
11 permit persons to whom the Software is furnished to do so, subject to
12 the following conditions:
13
14 The above copyright notice and this permission notice shall be
15 included in all copies or substantial portions of the Software.
16
17 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
18 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
19 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
20 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
21 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
22 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
23 WITH 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
29 00000000 <__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
47 00000020 <__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
66 int
unw_is_signal_frame(unw_cursor_t * cursor)67 unw_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_int (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