1/* ABI compatibility for 'longjmp' and 'siglongjmp' symbols in libpthread ABI.
2 X86 version.
3 Copyright (C) 1918-2020 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
19
20#include <pthreadP.h>
21#include <jmp_buf-ssp.h>
22
23#ifdef __x86_64__
24# define SHADOW_STACK_POINTER_SIZE 8
25#else
26# define SHADOW_STACK_POINTER_SIZE 4
27#endif
28
29/* Assert that the priv field in struct pthread_unwind_buf has space
30 to store shadow stack pointer. */
31_Static_assert ((offsetof (struct pthread_unwind_buf, priv)
32 <= SHADOW_STACK_POINTER_OFFSET)
33 && ((offsetof (struct pthread_unwind_buf, priv)
34 + sizeof (((struct pthread_unwind_buf *) 0)->priv))
35 >= (SHADOW_STACK_POINTER_OFFSET
36 + SHADOW_STACK_POINTER_SIZE)),
37 "Shadow stack pointer is not within private storage "
38 "of pthread_unwind_buf.");
39
40#include <shlib-compat.h>
41
42/* libpthread once had its own longjmp (and siglongjmp alias), though there
43 was no apparent reason for it. There is no use in having a separate
44 symbol in libpthread, but the historical ABI requires it. For static
45 linking, there is no need to provide anything here--the libc version
46 will be linked in. For shared library ABI compatibility, there must be
47 longjmp and siglongjmp symbols in libpthread.so.
48
49 With an IFUNC resolver, it would be possible to avoid the indirection,
50 but the IFUNC resolver might run before the __libc_longjmp symbol has
51 been relocated, in which case the IFUNC resolver would not be able to
52 provide the correct address. */
53
54#if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_22)
55
56static void __attribute__ ((noreturn, used))
57longjmp_compat (jmp_buf env, int val)
58{
59 /* NB: We call __libc_siglongjmp, instead of __libc_longjmp, since
60 __libc_longjmp is a private interface for cancellation which
61 doesn't restore shadow stack register. */
62 __libc_siglongjmp (env, val);
63}
64
65strong_alias (longjmp_compat, longjmp_alias)
66compat_symbol (libpthread, longjmp_alias, longjmp, GLIBC_2_0);
67
68strong_alias (longjmp_alias, siglongjmp_alias)
69compat_symbol (libpthread, siglongjmp_alias, siglongjmp, GLIBC_2_0);
70
71#endif
72