text: /* libunwind - a platform-independent unwind library
     Copyright (C) 2012 Tommi Rantala <tt.rantala@gmail.com>
     Copyright (C) 2013 Linaro Limited
  
  This file is part of libunwind.
  
  Permission is hereby granted, free of charge, to any person obtaining
  a copy of this software and associated documentation files (the
  "Software"), to deal in the Software without restriction, including
  without limitation the rights to use, copy, modify, merge, publish,
  distribute, sublicense, and/or sell copies of the Software, and to
  permit persons to whom the Software is furnished to do so, subject to
  the following conditions:
  
  The above copyright notice and this permission notice shall be
  included in all copies or substantial portions of the Software.
  
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
  
  #include "unwind_i.h"
  
  /* The restorer stub will always have the form:
  
     d2801168        movz    x8, #0x8b
     d4000001        svc     #0x0
  */
  
  PROTECTED int
  unw_is_signal_frame (unw_cursor_t *cursor)
  {
  #ifdef __linux__
    struct cursor *c = (struct cursor *) cursor;
    unw_word_t w0, ip;
    unw_addr_space_t as;
    unw_accessors_t *a;
    void *arg;
    int ret;
  
    as = c->dwarf.as;
    a = unw_get_accessors (as);
    arg = c->dwarf.as_arg;
  
    ip = c->dwarf.ip;
    /* ANDROID support update. */
    /* Undo the attempt to correct the PC or we'll be pointing to the nop instead of the mov. */
    ip += 4;
    /* ANDROID support update. */
  
    ret = (*a->access_mem) (as, ip, &w0, 0, arg);
    if (ret < 0)
    /* ANDROID support update. */
      return 0;
    /* End ANDROID update. */
  
    /* FIXME: distinguish 32bit insn vs 64bit registers.  */
    if (w0 != 0xd4000001d2801168)
      return 0;
  
    return 1;
  
  #else
    return -UNW_ENOINFO;
  #endif
  }
  