1 | /* Inline functions for dynamic linking. |
2 | Copyright (C) 1995-2020 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 macro is used as a callback from elf_machine_rel{a,} when a |
20 | static TLS reloc is about to be performed. Since (in dl-load.c) we |
21 | permit dynamic loading of objects that might use such relocs, we |
22 | have to check whether each use is actually doable. If the object |
23 | whose TLS segment the reference resolves to was allocated space in |
24 | the static TLS block at startup, then it's ok. Otherwise, we make |
25 | an attempt to allocate it in surplus space on the fly. If that |
26 | can't be done, we fall back to the error that DF_STATIC_TLS is |
27 | intended to produce. */ |
28 | #define HAVE_STATIC_TLS(map, sym_map) \ |
29 | (__builtin_expect ((sym_map)->l_tls_offset != NO_TLS_OFFSET \ |
30 | && ((sym_map)->l_tls_offset \ |
31 | != FORCED_DYNAMIC_TLS_OFFSET), 1)) |
32 | |
33 | #define CHECK_STATIC_TLS(map, sym_map) \ |
34 | do { \ |
35 | if (!HAVE_STATIC_TLS (map, sym_map)) \ |
36 | _dl_allocate_static_tls (sym_map); \ |
37 | } while (0) |
38 | |
39 | #define TRY_STATIC_TLS(map, sym_map) \ |
40 | (__builtin_expect ((sym_map)->l_tls_offset \ |
41 | != FORCED_DYNAMIC_TLS_OFFSET, 1) \ |
42 | && (__builtin_expect ((sym_map)->l_tls_offset != NO_TLS_OFFSET, 1) \ |
43 | || _dl_try_allocate_static_tls (sym_map) == 0)) |
44 | |
45 | int _dl_try_allocate_static_tls (struct link_map *map) attribute_hidden; |
46 | |
47 | #include <elf.h> |
48 | |
49 | #ifdef RESOLVE_MAP |
50 | /* We pass reloc_addr as a pointer to void, as opposed to a pointer to |
51 | ElfW(Addr), because not all architectures can assume that the |
52 | relocated address is properly aligned, whereas the compiler is |
53 | entitled to assume that a pointer to a type is properly aligned for |
54 | the type. Even if we cast the pointer back to some other type with |
55 | less strict alignment requirements, the compiler might still |
56 | remember that the pointer was originally more aligned, thereby |
57 | optimizing away alignment tests or using word instructions for |
58 | copying memory, breaking the very code written to handle the |
59 | unaligned cases. */ |
60 | # if ! ELF_MACHINE_NO_REL |
61 | auto inline void __attribute__((always_inline)) |
62 | elf_machine_rel (struct link_map *map, const ElfW(Rel) *reloc, |
63 | const ElfW(Sym) *sym, const struct r_found_version *version, |
64 | void *const reloc_addr, int skip_ifunc); |
65 | auto inline void __attribute__((always_inline)) |
66 | elf_machine_rel_relative (ElfW(Addr) l_addr, const ElfW(Rel) *reloc, |
67 | void *const reloc_addr); |
68 | # endif |
69 | # if ! ELF_MACHINE_NO_RELA |
70 | auto inline void __attribute__((always_inline)) |
71 | elf_machine_rela (struct link_map *map, const ElfW(Rela) *reloc, |
72 | const ElfW(Sym) *sym, const struct r_found_version *version, |
73 | void *const reloc_addr, int skip_ifunc); |
74 | auto inline void __attribute__((always_inline)) |
75 | elf_machine_rela_relative (ElfW(Addr) l_addr, const ElfW(Rela) *reloc, |
76 | void *const reloc_addr); |
77 | # endif |
78 | # if ELF_MACHINE_NO_RELA || defined ELF_MACHINE_PLT_REL |
79 | auto inline void __attribute__((always_inline)) |
80 | elf_machine_lazy_rel (struct link_map *map, |
81 | ElfW(Addr) l_addr, const ElfW(Rel) *reloc, |
82 | int skip_ifunc); |
83 | # else |
84 | auto inline void __attribute__((always_inline)) |
85 | elf_machine_lazy_rel (struct link_map *map, |
86 | ElfW(Addr) l_addr, const ElfW(Rela) *reloc, |
87 | int skip_ifunc); |
88 | # endif |
89 | #endif |
90 | |
91 | #include <dl-machine.h> |
92 | |
93 | #include "get-dynamic-info.h" |
94 | |
95 | #ifdef RESOLVE_MAP |
96 | |
97 | # if defined RTLD_BOOTSTRAP || defined STATIC_PIE_BOOTSTRAP |
98 | # define ELF_DURING_STARTUP (1) |
99 | # else |
100 | # define ELF_DURING_STARTUP (0) |
101 | # endif |
102 | |
103 | /* Get the definitions of `elf_dynamic_do_rel' and `elf_dynamic_do_rela'. |
104 | These functions are almost identical, so we use cpp magic to avoid |
105 | duplicating their code. It cannot be done in a more general function |
106 | because we must be able to completely inline. */ |
107 | |
108 | /* On some machines, notably SPARC, DT_REL* includes DT_JMPREL in its |
109 | range. Note that according to the ELF spec, this is completely legal! |
110 | |
111 | We are guarenteed that we have one of three situations. Either DT_JMPREL |
112 | comes immediately after DT_REL*, or there is overlap and DT_JMPREL |
113 | consumes precisely the very end of the DT_REL*, or DT_JMPREL and DT_REL* |
114 | are completely separate and there is a gap between them. */ |
115 | |
116 | # define _ELF_DYNAMIC_DO_RELOC(RELOC, reloc, map, do_lazy, skip_ifunc, test_rel) \ |
117 | do { \ |
118 | struct { ElfW(Addr) start, size; \ |
119 | __typeof (((ElfW(Dyn) *) 0)->d_un.d_val) nrelative; int lazy; } \ |
120 | ranges[2] = { { 0, 0, 0, 0 }, { 0, 0, 0, 0 } }; \ |
121 | \ |
122 | if ((map)->l_info[DT_##RELOC]) \ |
123 | { \ |
124 | ranges[0].start = D_PTR ((map), l_info[DT_##RELOC]); \ |
125 | ranges[0].size = (map)->l_info[DT_##RELOC##SZ]->d_un.d_val; \ |
126 | if (map->l_info[VERSYMIDX (DT_##RELOC##COUNT)] != NULL) \ |
127 | ranges[0].nrelative \ |
128 | = map->l_info[VERSYMIDX (DT_##RELOC##COUNT)]->d_un.d_val; \ |
129 | } \ |
130 | if ((map)->l_info[DT_PLTREL] \ |
131 | && (!test_rel || (map)->l_info[DT_PLTREL]->d_un.d_val == DT_##RELOC)) \ |
132 | { \ |
133 | ElfW(Addr) start = D_PTR ((map), l_info[DT_JMPREL]); \ |
134 | ElfW(Addr) size = (map)->l_info[DT_PLTRELSZ]->d_un.d_val; \ |
135 | \ |
136 | if (ranges[0].start + ranges[0].size == (start + size)) \ |
137 | ranges[0].size -= size; \ |
138 | if (ELF_DURING_STARTUP \ |
139 | || (!(do_lazy) \ |
140 | && (ranges[0].start + ranges[0].size) == start)) \ |
141 | { \ |
142 | /* Combine processing the sections. */ \ |
143 | ranges[0].size += size; \ |
144 | } \ |
145 | else \ |
146 | { \ |
147 | ranges[1].start = start; \ |
148 | ranges[1].size = size; \ |
149 | ranges[1].lazy = (do_lazy); \ |
150 | } \ |
151 | } \ |
152 | \ |
153 | if (ELF_DURING_STARTUP) \ |
154 | elf_dynamic_do_##reloc ((map), ranges[0].start, ranges[0].size, \ |
155 | ranges[0].nrelative, 0, skip_ifunc); \ |
156 | else \ |
157 | { \ |
158 | int ranges_index; \ |
159 | for (ranges_index = 0; ranges_index < 2; ++ranges_index) \ |
160 | elf_dynamic_do_##reloc ((map), \ |
161 | ranges[ranges_index].start, \ |
162 | ranges[ranges_index].size, \ |
163 | ranges[ranges_index].nrelative, \ |
164 | ranges[ranges_index].lazy, \ |
165 | skip_ifunc); \ |
166 | } \ |
167 | } while (0) |
168 | |
169 | # if ELF_MACHINE_NO_REL || ELF_MACHINE_NO_RELA |
170 | # define _ELF_CHECK_REL 0 |
171 | # else |
172 | # define _ELF_CHECK_REL 1 |
173 | # endif |
174 | |
175 | # if ! ELF_MACHINE_NO_REL |
176 | # include "do-rel.h" |
177 | # define ELF_DYNAMIC_DO_REL(map, lazy, skip_ifunc) \ |
178 | _ELF_DYNAMIC_DO_RELOC (REL, Rel, map, lazy, skip_ifunc, _ELF_CHECK_REL) |
179 | # else |
180 | # define ELF_DYNAMIC_DO_REL(map, lazy, skip_ifunc) /* Nothing to do. */ |
181 | # endif |
182 | |
183 | # if ! ELF_MACHINE_NO_RELA |
184 | # define DO_RELA |
185 | # include "do-rel.h" |
186 | # define ELF_DYNAMIC_DO_RELA(map, lazy, skip_ifunc) \ |
187 | _ELF_DYNAMIC_DO_RELOC (RELA, Rela, map, lazy, skip_ifunc, _ELF_CHECK_REL) |
188 | # else |
189 | # define ELF_DYNAMIC_DO_RELA(map, lazy, skip_ifunc) /* Nothing to do. */ |
190 | # endif |
191 | |
192 | /* This can't just be an inline function because GCC is too dumb |
193 | to inline functions containing inlines themselves. */ |
194 | # define ELF_DYNAMIC_RELOCATE(map, lazy, consider_profile, skip_ifunc) \ |
195 | do { \ |
196 | int edr_lazy = elf_machine_runtime_setup ((map), (lazy), \ |
197 | (consider_profile)); \ |
198 | ELF_DYNAMIC_DO_REL ((map), edr_lazy, skip_ifunc); \ |
199 | ELF_DYNAMIC_DO_RELA ((map), edr_lazy, skip_ifunc); \ |
200 | } while (0) |
201 | |
202 | #endif |
203 | |