1/* ELF symbol resolve functions for VDSO objects.
2 Copyright (C) 2005-2021 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 <https://www.gnu.org/licenses/>. */
18
19#ifndef _DL_VDSO_H
20#define _DL_VDSO_H 1
21
22#include <ldsodefs.h>
23#include <dl-hash.h>
24
25/* If the architecture support vDSO it should define which is the expected
26 kernel version and hash value through both VDSO_NAME and VDSO_HASH
27 (usually defined at architecture sysdep.h). */
28
29#ifndef VDSO_NAME
30# define VDSO_NAME "LINUX_0.0"
31#endif
32#ifndef VDSO_HASH
33# define VDSO_HASH 0
34#endif
35
36/* Functions for resolving symbols in the VDSO link map. */
37static inline void *
38dl_vdso_vsym (const char *name)
39{
40 struct link_map *map = GLRO (dl_sysinfo_map);
41 if (map == NULL)
42 return NULL;
43
44 /* Use a WEAK REF so we don't error out if the symbol is not found. */
45 ElfW (Sym) wsym = { 0 };
46 wsym.st_info = (unsigned char) ELFW (ST_INFO (STB_WEAK, STT_NOTYPE));
47
48 struct r_found_version rfv = { VDSO_NAME, VDSO_HASH, 1, NULL };
49
50 /* Search the scope of the vdso map. */
51 const ElfW (Sym) *ref = &wsym;
52 lookup_t result = GLRO (dl_lookup_symbol_x) (name, map, &ref,
53 map->l_local_scope,
54 &rfv, 0, 0, NULL);
55 return ref != NULL ? DL_SYMBOL_ADDRESS (result, ref) : NULL;
56}
57
58#endif /* dl-vdso.h */
59