1/*
2 * Copyright (C) 2013 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 <platform/bionic/tls_defines.h>
30#include <private/bionic_asm.h>
31
32// This custom code preserves the return address across the system call.
33
34ENTRY(vfork)
35__BIONIC_WEAK_ASM_FOR_NATIVE_BRIDGE(vfork)
36  popq    %rdi  // Grab the return address.
37
38  // Set cached_pid_ to 0, vforked_ to 1, and stash the previous value.
39  mov     %fs:0, %r8
40  mov     (TLS_SLOT_THREAD_ID * 8)(%r8), %r8
41  movl    20(%r8), %r9d
42  movl    $0x80000000, 20(%r8)
43
44  movl    $__NR_vfork, %eax
45  syscall
46  pushq   %rdi  // Restore the return address.
47
48  test    %eax, %eax
49  jz      1f
50
51  // rc != 0: restore the previous cached_pid_/vforked_ values.
52  movl    %r9d, 20(%r8)
53
54  cmpq    $-MAX_ERRNO, %rax
55  jb      1f
56  negl    %eax
57  movl    %eax, %edi
58  call    __set_errno_internal
591:
60  ret
61END(vfork)
62