1/* Copyright (C) 2001-2016 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <http://www.gnu.org/licenses/>. */
17
18#include <sysdep.h>
19#define _ERRNO_H 1
20#include <bits/errno.h>
21#include <tcb-offsets.h>
22
23
24/* Clone the calling process, but without copying the whole address space.
25 The calling process is suspended until the new process exits or is
26 replaced by a call to `execve'. Return -1 for errors, 0 to the new process,
27 and the process ID of the new process to the old process. */
28
29ENTRY (__vfork)
30
31 /* Pop the return PC value into RDI. We need a register that
32 is preserved by the syscall and that we're allowed to destroy. */
33 popq %rdi
34 cfi_adjust_cfa_offset(-8)
35 cfi_register(%rip, %rdi)
36
37 /* Stuff the syscall number in RAX and enter into the kernel. */
38 movl $SYS_ify (vfork), %eax
39 syscall
40
41 /* Push back the return PC. */
42 pushq %rdi
43 cfi_adjust_cfa_offset(8)
44
45 cmpl $-4095, %eax
46 jae SYSCALL_ERROR_LABEL /* Branch forward if it failed. */
47
48 /* Normal return. */
49 ret
50
51PSEUDO_END (__vfork)
52libc_hidden_def (__vfork)
53
54weak_alias (__vfork, vfork)
55strong_alias (__vfork, __libc_vfork)
56