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 | |
29 | ENTRY (__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 | |
51 | PSEUDO_END (__vfork) |
52 | libc_hidden_def (__vfork) |
53 | |
54 | weak_alias (__vfork, vfork) |
55 | strong_alias (__vfork, __libc_vfork) |
56 | |