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1 | /* x86 specific support for ELF |
2 | Copyright (C) 2017 Free Software Foundation, Inc. | |
3 | ||
4 | This file is part of BFD, the Binary File Descriptor library. | |
5 | ||
6 | This program is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 3 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | This program 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 | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with this program; if not, write to the Free Software | |
18 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, | |
19 | MA 02110-1301, USA. */ | |
20 | ||
21 | #include "sysdep.h" | |
22 | #include "bfd.h" | |
23 | #include "bfdlink.h" | |
24 | #include "libbfd.h" | |
25 | #include "elf-bfd.h" | |
26 | #include "bfd_stdint.h" | |
27 | #include "objalloc.h" | |
28 | #include "hashtab.h" | |
29 | ||
30 | /* If ELIMINATE_COPY_RELOCS is non-zero, the linker will try to avoid | |
31 | copying dynamic variables from a shared lib into an app's dynbss | |
32 | section, and instead use a dynamic relocation to point into the | |
33 | shared lib. */ | |
34 | #define ELIMINATE_COPY_RELOCS 1 | |
35 | ||
36 | #define elf_x86_hash_table(p, id) \ | |
37 | (elf_hash_table_id ((struct elf_link_hash_table *) ((p)->hash)) == (id) \ | |
38 | ? ((struct elf_x86_link_hash_table *) ((p)->hash)) : NULL) | |
39 | ||
40 | /* Is a undefined weak symbol which is resolved to 0. Reference to an | |
41 | undefined weak symbol is resolved to 0 when building executable if | |
42 | it isn't dynamic and | |
43 | 1. Has non-GOT/non-PLT relocations in text section. Or | |
44 | 2. Has no GOT/PLT relocation. | |
45 | Local undefined weak symbol is always resolved to 0. | |
46 | */ | |
47 | #define UNDEFINED_WEAK_RESOLVED_TO_ZERO(INFO, ID, GOT_RELOC, EH) \ | |
48 | ((EH)->elf.root.type == bfd_link_hash_undefweak \ | |
49 | && ((EH)->elf.forced_local \ | |
50 | || (bfd_link_executable (INFO) \ | |
51 | && (elf_x86_hash_table ((INFO), (ID))->interp == NULL \ | |
52 | || !(GOT_RELOC) \ | |
53 | || (EH)->has_non_got_reloc \ | |
54 | || !(INFO)->dynamic_undefined_weak)))) | |
55 | ||
56 | /* Should copy relocation be generated for a symbol. Don't generate | |
57 | copy relocation against a protected symbol defined in a shared | |
58 | object with GNU_PROPERTY_NO_COPY_ON_PROTECTED. */ | |
59 | #define SYMBOL_NO_COPYRELOC(INFO, EH) \ | |
60 | ((EH)->def_protected \ | |
61 | && ((EH)->elf.root.type == bfd_link_hash_defined \ | |
62 | || (EH)->elf.root.type == bfd_link_hash_defweak) \ | |
63 | && elf_has_no_copy_on_protected ((EH)->elf.root.u.def.section->owner) \ | |
64 | && ((EH)->elf.root.u.def.section->owner->flags & DYNAMIC) != 0 \ | |
65 | && ((EH)->elf.root.u.def.section->flags & SEC_CODE) == 0) | |
66 | ||
67 | /* x86 ELF linker hash entry. */ | |
68 | ||
69 | struct elf_x86_link_hash_entry | |
70 | { | |
71 | struct elf_link_hash_entry elf; | |
72 | ||
73 | /* Track dynamic relocs copied for this symbol. */ | |
74 | struct elf_dyn_relocs *dyn_relocs; | |
75 | ||
76 | unsigned char tls_type; | |
77 | ||
78 | /* TRUE if symbol has GOT or PLT relocations. */ | |
79 | unsigned int has_got_reloc : 1; | |
80 | ||
81 | /* TRUE if symbol has non-GOT/non-PLT relocations in text sections. */ | |
82 | unsigned int has_non_got_reloc : 1; | |
83 | ||
84 | /* Don't call finish_dynamic_symbol on this symbol. */ | |
85 | unsigned int no_finish_dynamic_symbol : 1; | |
86 | ||
87 | /* TRUE if symbol is __tls_get_addr. */ | |
88 | unsigned int tls_get_addr : 1; | |
89 | ||
90 | /* TRUE if symbol is defined as a protected symbol. */ | |
91 | unsigned int def_protected : 1; | |
92 | ||
93 | /* Symbol is referenced by R_386_GOTOFF relocation. This is only used | |
94 | by i386. */ | |
95 | unsigned int gotoff_ref : 1; | |
96 | ||
97 | /* TRUE if a weak symbol with a real definition needs a copy reloc. | |
98 | When there is a weak symbol with a real definition, the processor | |
99 | independent code will have arranged for us to see the real | |
100 | definition first. We need to copy the needs_copy bit from the | |
101 | real definition and check it when allowing copy reloc in PIE. This | |
102 | is only used by x86-64. */ | |
103 | unsigned int needs_copy : 1; | |
104 | ||
105 | /* Reference count of C/C++ function pointer relocations in read-write | |
106 | section which can be resolved at run-time. */ | |
107 | bfd_signed_vma func_pointer_refcount; | |
108 | ||
109 | /* Information about the GOT PLT entry. Filled when there are both | |
110 | GOT and PLT relocations against the same function. */ | |
111 | union gotplt_union plt_got; | |
112 | ||
113 | /* Information about the second PLT entry. */ | |
114 | union gotplt_union plt_second; | |
115 | ||
116 | /* Offset of the GOTPLT entry reserved for the TLS descriptor, | |
117 | starting at the end of the jump table. */ | |
118 | bfd_vma tlsdesc_got; | |
119 | }; | |
120 | ||
121 | /* The first 3 values in tls_type of x86 ELF linker hash entry. */ | |
122 | #define GOT_UNKNOWN 0 | |
123 | #define GOT_NORMAL 1 | |
124 | #define GOT_TLS_GD 2 | |
125 | ||
126 | #define elf_x86_hash_entry(ent) \ | |
127 | ((struct elf_x86_link_hash_entry *)(ent)) | |
128 | ||
129 | /* x86 ELF linker hash table. */ | |
130 | ||
131 | struct elf_x86_link_hash_table | |
132 | { | |
133 | struct elf_link_hash_table elf; | |
134 | ||
135 | /* Short-cuts to get to dynamic linker sections. */ | |
136 | asection *interp; | |
137 | asection *plt_eh_frame; | |
138 | asection *plt_second; | |
139 | asection *plt_second_eh_frame; | |
140 | asection *plt_got; | |
141 | asection *plt_got_eh_frame; | |
142 | ||
143 | union | |
144 | { | |
145 | bfd_signed_vma refcount; | |
146 | bfd_vma offset; | |
147 | } tls_ld_or_ldm_got; | |
148 | ||
149 | /* The amount of space used by the jump slots in the GOT. */ | |
150 | bfd_vma sgotplt_jump_table_size; | |
151 | ||
152 | /* Small local sym cache. */ | |
153 | struct sym_cache sym_cache; | |
154 | ||
155 | /* _TLS_MODULE_BASE_ symbol. */ | |
156 | struct bfd_link_hash_entry *tls_module_base; | |
157 | ||
158 | /* Used by local STT_GNU_IFUNC symbols. */ | |
159 | htab_t loc_hash_table; | |
160 | void * loc_hash_memory; | |
161 | ||
162 | /* The offset into splt of the PLT entry for the TLS descriptor | |
163 | resolver. Special values are 0, if not necessary (or not found | |
164 | to be necessary yet), and -1 if needed but not determined | |
165 | yet. */ | |
166 | bfd_vma tlsdesc_plt; | |
167 | ||
168 | /* The offset into sgot of the GOT entry used by the PLT entry | |
169 | above. */ | |
170 | bfd_vma tlsdesc_got; | |
171 | ||
172 | /* The index of the next R_X86_64_JUMP_SLOT entry in .rela.plt. */ | |
173 | bfd_vma next_jump_slot_index; | |
174 | /* The index of the next R_X86_64_IRELATIVE entry in .rela.plt. */ | |
175 | bfd_vma next_irelative_index; | |
176 | ||
177 | /* TRUE if there are dynamic relocs against IFUNC symbols that apply | |
178 | to read-only sections. */ | |
179 | bfd_boolean readonly_dynrelocs_against_ifunc; | |
180 | ||
181 | bfd_vma (*r_info) (bfd_vma, bfd_vma); | |
182 | bfd_vma (*r_sym) (bfd_vma); | |
183 | unsigned int pointer_r_type; | |
184 | int dynamic_interpreter_size; | |
185 | const char *dynamic_interpreter; | |
186 | const char *tls_get_addr; | |
187 | }; | |
188 | ||
189 | struct elf_x86_obj_tdata | |
190 | { | |
191 | struct elf_obj_tdata root; | |
192 | ||
193 | /* tls_type for each local got entry. */ | |
194 | char *local_got_tls_type; | |
195 | ||
196 | /* GOTPLT entries for TLS descriptors. */ | |
197 | bfd_vma *local_tlsdesc_gotent; | |
198 | }; | |
199 | ||
200 | #define elf_x86_tdata(abfd) \ | |
201 | ((struct elf_x86_obj_tdata *) (abfd)->tdata.any) | |
202 | ||
203 | #define elf_x86_local_got_tls_type(abfd) \ | |
204 | (elf_x86_tdata (abfd)->local_got_tls_type) | |
205 | ||
206 | #define elf_x86_local_tlsdesc_gotent(abfd) \ | |
207 | (elf_x86_tdata (abfd)->local_tlsdesc_gotent) | |
208 | ||
209 | extern void _bfd_x86_elf_set_tls_module_base | |
210 | (struct bfd_link_info *); | |
211 | ||
212 | extern bfd_vma _bfd_x86_elf_dtpoff_base | |
213 | (struct bfd_link_info *); | |
214 | ||
215 | extern bfd_boolean _bfd_x86_elf_readonly_dynrelocs | |
216 | (struct elf_link_hash_entry *, void *); | |
217 | ||
218 | extern struct elf_link_hash_entry * _bfd_elf_x86_get_local_sym_hash | |
219 | (struct elf_x86_link_hash_table *, bfd *, const Elf_Internal_Rela *, | |
220 | bfd_boolean); | |
221 | ||
222 | extern hashval_t _bfd_x86_elf_local_htab_hash | |
223 | (const void *); | |
224 | ||
225 | extern int _bfd_x86_elf_local_htab_eq | |
226 | (const void *, const void *); | |
227 | ||
228 | extern struct bfd_hash_entry * _bfd_x86_elf_link_hash_newfunc | |
229 | (struct bfd_hash_entry *, struct bfd_hash_table *, const char *); | |
230 | ||
231 | extern void _bfd_x86_elf_link_hash_table_free | |
232 | (bfd *); | |
233 | ||
234 | extern int _bfd_x86_elf_compare_relocs | |
235 | (const void *, const void *); | |
236 | ||
237 | extern bfd_boolean _bfd_x86_elf_link_check_relocs | |
238 | (bfd *, struct bfd_link_info *); | |
239 | ||
240 | extern bfd_boolean _bfd_x86_elf_always_size_sections | |
241 | (bfd *, struct bfd_link_info *); | |
242 | ||
243 | extern void _bfd_x86_elf_merge_symbol_attribute | |
244 | (struct elf_link_hash_entry *, const Elf_Internal_Sym *, | |
245 | bfd_boolean, bfd_boolean); | |
246 | ||
247 | extern void _bfd_x86_elf_copy_indirect_symbol | |
248 | (struct bfd_link_info *, struct elf_link_hash_entry *, | |
249 | struct elf_link_hash_entry *); | |
250 | ||
251 | extern bfd_boolean _bfd_x86_elf_fixup_symbol | |
252 | (struct bfd_link_info *, struct elf_link_hash_entry *); | |
253 | ||
254 | extern bfd_boolean _bfd_x86_elf_hash_symbol | |
255 | (struct elf_link_hash_entry *); | |
256 | ||
257 | extern enum elf_property_kind _bfd_x86_elf_parse_gnu_properties | |
258 | (bfd *, unsigned int, bfd_byte *, unsigned int); | |
259 | ||
260 | extern bfd_boolean _bfd_x86_elf_merge_gnu_properties | |
261 | (struct bfd_link_info *, bfd *, elf_property *, elf_property *); | |
262 | ||
263 | #define bfd_elf64_bfd_link_check_relocs \ | |
264 | _bfd_x86_elf_link_check_relocs | |
265 | #define bfd_elf32_bfd_link_check_relocs \ | |
266 | _bfd_x86_elf_link_check_relocs | |
267 | ||
268 | #define elf_backend_always_size_sections \ | |
269 | _bfd_x86_elf_always_size_sections | |
270 | #define elf_backend_merge_symbol_attribute \ | |
271 | _bfd_x86_elf_merge_symbol_attribute | |
272 | #define elf_backend_copy_indirect_symbol \ | |
273 | _bfd_x86_elf_copy_indirect_symbol | |
274 | #define elf_backend_fixup_symbol \ | |
275 | _bfd_x86_elf_fixup_symbol | |
276 | #define elf_backend_hash_symbol \ | |
277 | _bfd_x86_elf_hash_symbol | |
278 | #define elf_backend_omit_section_dynsym \ | |
279 | ((bfd_boolean (*) (bfd *, struct bfd_link_info *, asection *)) bfd_true) | |
280 | #define elf_backend_parse_gnu_properties \ | |
281 | _bfd_x86_elf_parse_gnu_properties | |
282 | #define elf_backend_merge_gnu_properties \ | |
283 | _bfd_x86_elf_merge_gnu_properties |