1/* Do relocations for ELF dynamic linking.
2 Copyright (C) 1995-2021 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/* This file may be included twice, to define both
20 `elf_dynamic_do_rel' and `elf_dynamic_do_rela'. */
21
22#ifdef DO_RELA
23# define elf_dynamic_do_Rel elf_dynamic_do_Rela
24# define Rel Rela
25# define elf_machine_rel elf_machine_rela
26# define elf_machine_rel_relative elf_machine_rela_relative
27#endif
28
29#ifndef DO_ELF_MACHINE_REL_RELATIVE
30# define DO_ELF_MACHINE_REL_RELATIVE(map, l_addr, relative) \
31 elf_machine_rel_relative (l_addr, relative, \
32 (void *) (l_addr + relative->r_offset))
33#endif
34
35/* Perform the relocations in MAP on the running program image as specified
36 by RELTAG, SZTAG. If LAZY is nonzero, this is the first pass on PLT
37 relocations; they should be set up to call _dl_runtime_resolve, rather
38 than fully resolved now. */
39
40auto inline void __attribute__ ((always_inline))
41elf_dynamic_do_Rel (struct link_map *map,
42 ElfW(Addr) reladdr, ElfW(Addr) relsize,
43 __typeof (((ElfW(Dyn) *) 0)->d_un.d_val) nrelative,
44 int lazy, int skip_ifunc)
45{
46 const ElfW(Rel) *r = (const void *) reladdr;
47 const ElfW(Rel) *end = (const void *) (reladdr + relsize);
48 ElfW(Addr) l_addr = map->l_addr;
49# if defined ELF_MACHINE_IRELATIVE && !defined RTLD_BOOTSTRAP
50 const ElfW(Rel) *r2 = NULL;
51 const ElfW(Rel) *end2 = NULL;
52# endif
53
54#if (!defined DO_RELA || !defined ELF_MACHINE_PLT_REL) && !defined RTLD_BOOTSTRAP
55 /* We never bind lazily during ld.so bootstrap. Unfortunately gcc is
56 not clever enough to see through all the function calls to realize
57 that. */
58 if (lazy)
59 {
60 /* Doing lazy PLT relocations; they need very little info. */
61 for (; r < end; ++r)
62# ifdef ELF_MACHINE_IRELATIVE
63 if (ELFW(R_TYPE) (r->r_info) == ELF_MACHINE_IRELATIVE)
64 {
65 if (r2 == NULL)
66 r2 = r;
67 end2 = r;
68 }
69 else
70# endif
71 elf_machine_lazy_rel (map, l_addr, r, skip_ifunc);
72
73# ifdef ELF_MACHINE_IRELATIVE
74 if (r2 != NULL)
75 for (; r2 <= end2; ++r2)
76 if (ELFW(R_TYPE) (r2->r_info) == ELF_MACHINE_IRELATIVE)
77 elf_machine_lazy_rel (map, l_addr, r2, skip_ifunc);
78# endif
79 }
80 else
81#endif
82 {
83 const ElfW(Sym) *const symtab =
84 (const void *) D_PTR (map, l_info[DT_SYMTAB]);
85 const ElfW(Rel) *relative = r;
86 r += nrelative;
87
88#ifndef RTLD_BOOTSTRAP
89 /* This is defined in rtld.c, but nowhere in the static libc.a; make
90 the reference weak so static programs can still link. This
91 declaration cannot be done when compiling rtld.c (i.e. #ifdef
92 RTLD_BOOTSTRAP) because rtld.c contains the common defn for
93 _dl_rtld_map, which is incompatible with a weak decl in the same
94 file. */
95# ifndef SHARED
96 weak_extern (GL(dl_rtld_map));
97# endif
98 if (map != &GL(dl_rtld_map)) /* Already done in rtld itself. */
99# if !defined DO_RELA || defined ELF_MACHINE_REL_RELATIVE
100 /* Rela platforms get the offset from r_addend and this must
101 be copied in the relocation address. Therefore we can skip
102 the relative relocations only if this is for rel
103 relocations or rela relocations if they are computed as
104 memory_loc += l_addr... */
105 if (l_addr != 0)
106# else
107 /* ...or we know the object has been prelinked. */
108 if (l_addr != 0 || ! map->l_info[VALIDX(DT_GNU_PRELINKED)])
109# endif
110#endif
111 for (; relative < r; ++relative)
112 DO_ELF_MACHINE_REL_RELATIVE (map, l_addr, relative);
113
114#ifdef RTLD_BOOTSTRAP
115 /* The dynamic linker always uses versioning. */
116 assert (map->l_info[VERSYMIDX (DT_VERSYM)] != NULL);
117#else
118 if (map->l_info[VERSYMIDX (DT_VERSYM)])
119#endif
120 {
121 const ElfW(Half) *const version =
122 (const void *) D_PTR (map, l_info[VERSYMIDX (DT_VERSYM)]);
123
124 for (; r < end; ++r)
125 {
126#if defined ELF_MACHINE_IRELATIVE && !defined RTLD_BOOTSTRAP
127 if (ELFW(R_TYPE) (r->r_info) == ELF_MACHINE_IRELATIVE)
128 {
129 if (r2 == NULL)
130 r2 = r;
131 end2 = r;
132 continue;
133 }
134#endif
135
136 ElfW(Half) ndx = version[ELFW(R_SYM) (r->r_info)] & 0x7fff;
137 elf_machine_rel (map, r, &symtab[ELFW(R_SYM) (r->r_info)],
138 &map->l_versions[ndx],
139 (void *) (l_addr + r->r_offset), skip_ifunc);
140 }
141
142#if defined ELF_MACHINE_IRELATIVE && !defined RTLD_BOOTSTRAP
143 if (r2 != NULL)
144 for (; r2 <= end2; ++r2)
145 if (ELFW(R_TYPE) (r2->r_info) == ELF_MACHINE_IRELATIVE)
146 {
147 ElfW(Half) ndx
148 = version[ELFW(R_SYM) (r2->r_info)] & 0x7fff;
149 elf_machine_rel (map, r2,
150 &symtab[ELFW(R_SYM) (r2->r_info)],
151 &map->l_versions[ndx],
152 (void *) (l_addr + r2->r_offset),
153 skip_ifunc);
154 }
155#endif
156 }
157#ifndef RTLD_BOOTSTRAP
158 else
159 {
160 for (; r < end; ++r)
161# ifdef ELF_MACHINE_IRELATIVE
162 if (ELFW(R_TYPE) (r->r_info) == ELF_MACHINE_IRELATIVE)
163 {
164 if (r2 == NULL)
165 r2 = r;
166 end2 = r;
167 }
168 else
169# endif
170 elf_machine_rel (map, r, &symtab[ELFW(R_SYM) (r->r_info)], NULL,
171 (void *) (l_addr + r->r_offset), skip_ifunc);
172
173# ifdef ELF_MACHINE_IRELATIVE
174 if (r2 != NULL)
175 for (; r2 <= end2; ++r2)
176 if (ELFW(R_TYPE) (r2->r_info) == ELF_MACHINE_IRELATIVE)
177 elf_machine_rel (map, r2, &symtab[ELFW(R_SYM) (r2->r_info)],
178 NULL, (void *) (l_addr + r2->r_offset),
179 skip_ifunc);
180# endif
181 }
182#endif
183 }
184}
185
186#undef elf_dynamic_do_Rel
187#undef Rel
188#undef elf_machine_rel
189#undef elf_machine_rel_relative
190#undef DO_ELF_MACHINE_REL_RELATIVE
191#undef DO_RELA
192