1 | /* vfork ABI-compatibility entry points for libpthread. |
2 | Copyright (C) 2014-2016 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ |
18 | |
19 | #include <unistd.h> |
20 | #include <shlib-compat.h> |
21 | |
22 | /* libpthread used to have its own vfork implementation that differed |
23 | from libc's only in having a pointless micro-optimization. There |
24 | is no longer any use to having a separate copy in libpthread, but |
25 | the historical ABI requires it. For static linking, there is no |
26 | need to provide anything here--the libc version will be linked in. |
27 | For shared library ABI compatibility, there must be __vfork and |
28 | vfork symbols in libpthread.so; so we define them using IFUNC to |
29 | redirect to the libc function. */ |
30 | |
31 | /* Note! If the architecture doesn't support IFUNC, then we need an |
32 | alternate target-specific mechanism to implement this. So we just |
33 | assume IFUNC here and require that the target override this file |
34 | if necessary. |
35 | |
36 | If the architecture can assume all supported versions of gcc will |
37 | produce a tail-call to __libc_vfork, consider including the version |
38 | in sysdeps/unix/sysv/linux/aarch64/pt-vfork.c. */ |
39 | |
40 | #if !HAVE_IFUNC |
41 | # error "must write pt-vfork for this machine or get IFUNC support" |
42 | #endif |
43 | |
44 | #if (SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_20) \ |
45 | || SHLIB_COMPAT (libpthread, GLIBC_2_1_2, GLIBC_2_20)) |
46 | |
47 | extern __typeof (vfork) __libc_vfork; /* Defined in libc. */ |
48 | |
49 | static __typeof (vfork) * |
50 | __attribute__ ((used)) |
51 | vfork_resolve (void) |
52 | { |
53 | return &__libc_vfork; |
54 | } |
55 | |
56 | # ifdef HAVE_ASM_SET_DIRECTIVE |
57 | # define DEFINE_VFORK(name) \ |
58 | asm (".set " #name ", vfork_resolve\n" \ |
59 | ".globl " #name "\n" \ |
60 | ".type " #name ", %gnu_indirect_function"); |
61 | # else |
62 | # define DEFINE_VFORK(name) \ |
63 | asm (#name " = vfork_resolve\n" \ |
64 | ".globl " #name "\n" \ |
65 | ".type " #name ", %gnu_indirect_function"); |
66 | # endif |
67 | #endif |
68 | |
69 | #if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_20) |
70 | DEFINE_VFORK (vfork_ifunc) |
71 | compat_symbol (libpthread, vfork_ifunc, vfork, GLIBC_2_0); |
72 | #endif |
73 | |
74 | #if SHLIB_COMPAT (libpthread, GLIBC_2_1_2, GLIBC_2_20) |
75 | DEFINE_VFORK (__vfork_ifunc) |
76 | compat_symbol (libpthread, __vfork_ifunc, __vfork, GLIBC_2_1_2); |
77 | #endif |
78 | |