1/*
2 * Copyright (C) 2014 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *  * Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 *  * Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in
12 *    the documentation and/or other materials provided with the
13 *    distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <private/bionic_asm.h>
30
31// gdb is smart enough to unwind through signal frames with just the regular
32// CFI information but libgcc and libunwind both need extra help. We do this
33// by using .fnstart/.fnend and inserting a nop before both __restore and
34// __restore_rt (but covered by the .fnstart/.fnend) so that although they're
35// not inside the functions from objdump's point of view, an unwinder that
36// blindly looks at the previous instruction (but is then smart enough to check
37// the unwind information to find out where it landed) gets the right answer.
38// Make sure not to have both DWARF and ARM unwind information, so only
39// use the ARM unwind information.
40
41// We need to place .fnstart ourselves (but we may as well keep the free .fnend).
42#undef __bionic_asm_custom_entry
43#define __bionic_asm_custom_entry(f)
44
45  .fnstart
46  .save {r0-r15}
47  .pad #32
48  nop
49ENTRY_PRIVATE_NO_DWARF(__restore)
50  // This function must have exactly this instruction sequence.
51  mov r7, #__NR_sigreturn
52  swi #0
53END_NO_DWARF(__restore)
54
55  .fnstart
56  .save {r0-r15}
57  .pad #160
58  nop
59ENTRY_PRIVATE_NO_DWARF(__restore_rt)
60  // This function must have exactly this instruction sequence.
61  mov r7, #__NR_rt_sigreturn
62  swi #0
63END_NO_DWARF(__restore_rt)
64