1/* libunwind - a platform-independent unwind library
2   Copyright (C) 2012 Tommi Rantala <tt.rantala@gmail.com>
3   Copyright (C) 2013 Linaro Limited
4
5This file is part of libunwind.
6
7Permission is hereby granted, free of charge, to any person obtaining
8a copy of this software and associated documentation files (the
9"Software"), to deal in the Software without restriction, including
10without limitation the rights to use, copy, modify, merge, publish,
11distribute, sublicense, and/or sell copies of the Software, and to
12permit persons to whom the Software is furnished to do so, subject to
13the following conditions:
14
15The above copyright notice and this permission notice shall be
16included in all copies or substantial portions of the Software.
17
18THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
19EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
21NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
22LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
23OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
24WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
25
26#include "unwind_i.h"
27
28/* The restorer stub will always have the form:
29
30   d2801168        movz    x8, #0x8b
31   d4000001        svc     #0x0
32*/
33
34PROTECTED int
35unw_is_signal_frame (unw_cursor_t *cursor)
36{
37#ifdef __linux__
38  struct cursor *c = (struct cursor *) cursor;
39  unw_word_t w0, ip;
40  unw_addr_space_t as;
41  unw_accessors_t *a;
42  void *arg;
43  int ret;
44
45  as = c->dwarf.as;
46  a = unw_get_accessors (as);
47  arg = c->dwarf.as_arg;
48
49  ip = c->dwarf.ip;
50  /* ANDROID support update. */
51  /* Undo the attempt to correct the PC or we'll be pointing to the nop instead of the mov. */
52  ip += 4;
53  /* ANDROID support update. */
54
55  ret = (*a->access_mem) (as, ip, &w0, 0, arg);
56  if (ret < 0)
57  /* ANDROID support update. */
58    return 0;
59  /* End ANDROID update. */
60
61  /* FIXME: distinguish 32bit insn vs 64bit registers.  */
62  if (w0 != 0xd4000001d2801168)
63    return 0;
64
65  return 1;
66
67#else
68  return -UNW_ENOINFO;
69#endif
70}
71