1 /* Inline functions for dynamic linking.
2 Copyright (C) 1995-2024 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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.
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.
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/>. */
19 #include <dl-machine.h>
23 /* We pass reloc_addr as a pointer to void, as opposed to a pointer to
24 ElfW(Addr), because not all architectures can assume that the
25 relocated address is properly aligned, whereas the compiler is
26 entitled to assume that a pointer to a type is properly aligned for
27 the type. Even if we cast the pointer back to some other type with
28 less strict alignment requirements, the compiler might still
29 remember that the pointer was originally more aligned, thereby
30 optimizing away alignment tests or using word instructions for
31 copying memory, breaking the very code written to handle the
33 # if ! ELF_MACHINE_NO_REL
34 static inline void __attribute__((always_inline))
35 elf_machine_rel (struct link_map *map, struct r_scope_elem *scope[],
36 const ElfW(Rel) *reloc, const ElfW(Sym) *sym,
37 const struct r_found_version *version,
38 void *const reloc_addr, int skip_ifunc);
39 static inline void __attribute__((always_inline))
40 elf_machine_rel_relative (ElfW(Addr) l_addr, const ElfW(Rel) *reloc,
41 void *const reloc_addr);
43 # if ! ELF_MACHINE_NO_RELA
44 static inline void __attribute__((always_inline))
45 elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
46 const ElfW(Rela) *reloc, const ElfW(Sym) *sym,
47 const struct r_found_version *version, void *const reloc_addr,
49 static inline void __attribute__((always_inline))
50 elf_machine_rela_relative (ElfW(Addr) l_addr, const ElfW(Rela) *reloc,
51 void *const reloc_addr);
53 # if ELF_MACHINE_NO_RELA || defined ELF_MACHINE_PLT_REL
54 static inline void __attribute__((always_inline))
55 elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[],
56 ElfW(Addr) l_addr, const ElfW(Rel) *reloc,
59 static inline void __attribute__((always_inline))
60 elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[],
61 ElfW(Addr) l_addr, const ElfW(Rela) *reloc,
68 /* Get the definitions of `elf_dynamic_do_rel' and `elf_dynamic_do_rela'.
69 These functions are almost identical, so we use cpp magic to avoid
70 duplicating their code. It cannot be done in a more general function
71 because we must be able to completely inline. */
73 /* On some machines, notably SPARC, DT_REL* includes DT_JMPREL in its
74 range. Note that according to the ELF spec, this is completely legal!
76 We are guaranteed that we have one of three situations. Either DT_JMPREL
77 comes immediately after DT_REL*, or there is overlap and DT_JMPREL
78 consumes precisely the very end of the DT_REL*, or DT_JMPREL and DT_REL*
79 are completely separate and there is a gap between them. */
81 # define _ELF_DYNAMIC_DO_RELOC(RELOC, reloc, map, scope, do_lazy, skip_ifunc, test_rel) \
83 struct { ElfW(Addr) start, size; \
84 __typeof (((ElfW(Dyn) *) 0)->d_un.d_val) nrelative; int lazy; } \
85 ranges[2] = { { 0, 0, 0, 0 }, { 0, 0, 0, 0 } }; \
87 /* With DT_RELR, DT_RELA/DT_REL can have zero value. */ \
88 if ((map)->l_info[DT_##RELOC] != NULL \
89 && (map)->l_info[DT_##RELOC]->d_un.d_ptr != 0) \
91 ranges[0].start = D_PTR ((map), l_info[DT_##RELOC]); \
92 ranges[0].size = (map)->l_info[DT_##RELOC##SZ]->d_un.d_val; \
93 if (map->l_info[VERSYMIDX (DT_##RELOC##COUNT)] != NULL) \
95 = map->l_info[VERSYMIDX (DT_##RELOC##COUNT)]->d_un.d_val; \
97 if ((map)->l_info[DT_PLTREL] \
98 && (!test_rel || (map)->l_info[DT_PLTREL]->d_un.d_val == DT_##RELOC)) \
100 ElfW(Addr) start = D_PTR ((map), l_info[DT_JMPREL]); \
101 ElfW(Addr) size = (map)->l_info[DT_PLTRELSZ]->d_un.d_val; \
103 if (ranges[0].start == 0) \
104 ranges[0].start = start; \
105 if (ranges[0].start + ranges[0].size == (start + size)) \
106 ranges[0].size -= size; \
108 && (ranges[0].start + ranges[0].size) == start) \
110 /* Combine processing the sections. */ \
111 ranges[0].size += size; \
115 ranges[1].start = start; \
116 ranges[1].size = size; \
117 ranges[1].lazy = (do_lazy); \
121 for (int ranges_index = 0; ranges_index < 2; ++ranges_index) \
122 elf_dynamic_do_##reloc ((map), scope, \
123 ranges[ranges_index].start, \
124 ranges[ranges_index].size, \
125 ranges[ranges_index].nrelative, \
126 ranges[ranges_index].lazy, \
130 # if ELF_MACHINE_NO_REL || ELF_MACHINE_NO_RELA
131 # define _ELF_CHECK_REL 0
133 # define _ELF_CHECK_REL 1
136 # if ! ELF_MACHINE_NO_REL
138 # define ELF_DYNAMIC_DO_REL(map, scope, lazy, skip_ifunc) \
139 _ELF_DYNAMIC_DO_RELOC (REL, Rel, map, scope, lazy, skip_ifunc, _ELF_CHECK_REL)
141 # define ELF_DYNAMIC_DO_REL(map, scope, lazy, skip_ifunc) /* Nothing to do. */
144 # if ! ELF_MACHINE_NO_RELA
147 # define ELF_DYNAMIC_DO_RELA(map, scope, lazy, skip_ifunc) \
148 _ELF_DYNAMIC_DO_RELOC (RELA, Rela, map, scope, lazy, skip_ifunc, _ELF_CHECK_REL)
150 # define ELF_DYNAMIC_DO_RELA(map, scope, lazy, skip_ifunc) /* Nothing to do. */
153 # define ELF_DYNAMIC_DO_RELR(map) \
155 ElfW(Addr) l_addr = (map)->l_addr, *where = 0; \
156 const ElfW(Relr) *r, *end; \
157 if ((map)->l_info[DT_RELR] == NULL) \
159 r = (const ElfW(Relr) *)D_PTR((map), l_info[DT_RELR]); \
160 end = (const ElfW(Relr) *)((const char *)r + \
161 (map)->l_info[DT_RELRSZ]->d_un.d_val); \
162 for (; r < end; r++) \
164 ElfW(Relr) entry = *r; \
165 if ((entry & 1) == 0) \
167 where = (ElfW(Addr) *)(l_addr + entry); \
168 *where++ += l_addr; \
172 for (long int i = 0; (entry >>= 1) != 0; i++) \
173 if ((entry & 1) != 0) \
174 where[i] += l_addr; \
175 where += CHAR_BIT * sizeof(ElfW(Relr)) - 1; \
180 # ifndef ELF_DYNAMIC_AFTER_RELOC
181 # define ELF_DYNAMIC_AFTER_RELOC(map, lazy)
184 /* This can't just be an inline function because GCC is too dumb
185 to inline functions containing inlines themselves. */
186 # ifdef RTLD_BOOTSTRAP
187 # define DO_RTLD_BOOTSTRAP 1
189 # define DO_RTLD_BOOTSTRAP 0
191 # define ELF_DYNAMIC_RELOCATE(map, scope, lazy, consider_profile, skip_ifunc) \
193 int edr_lazy = elf_machine_runtime_setup ((map), (scope), (lazy), \
194 (consider_profile)); \
195 if (((map) != &GL(dl_rtld_map) || DO_RTLD_BOOTSTRAP)) \
196 ELF_DYNAMIC_DO_RELR (map); \
197 ELF_DYNAMIC_DO_REL ((map), (scope), edr_lazy, skip_ifunc); \
198 ELF_DYNAMIC_DO_RELA ((map), (scope), edr_lazy, skip_ifunc); \
199 ELF_DYNAMIC_AFTER_RELOC ((map), (edr_lazy)); \