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0afcef53 L |
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" | |
0afcef53 L |
27 | #include "hashtab.h" |
28 | ||
765e526c L |
29 | #define ABI_64_P(abfd) \ |
30 | (get_elf_backend_data (abfd)->s->elfclass == ELFCLASS64) | |
31 | ||
0afcef53 L |
32 | /* If ELIMINATE_COPY_RELOCS is non-zero, the linker will try to avoid |
33 | copying dynamic variables from a shared lib into an app's dynbss | |
34 | section, and instead use a dynamic relocation to point into the | |
35 | shared lib. */ | |
36 | #define ELIMINATE_COPY_RELOCS 1 | |
37 | ||
38 | #define elf_x86_hash_table(p, id) \ | |
39 | (elf_hash_table_id ((struct elf_link_hash_table *) ((p)->hash)) == (id) \ | |
40 | ? ((struct elf_x86_link_hash_table *) ((p)->hash)) : NULL) | |
41 | ||
42 | /* Is a undefined weak symbol which is resolved to 0. Reference to an | |
43 | undefined weak symbol is resolved to 0 when building executable if | |
44 | it isn't dynamic and | |
45 | 1. Has non-GOT/non-PLT relocations in text section. Or | |
46 | 2. Has no GOT/PLT relocation. | |
47 | Local undefined weak symbol is always resolved to 0. | |
48 | */ | |
49 | #define UNDEFINED_WEAK_RESOLVED_TO_ZERO(INFO, ID, GOT_RELOC, EH) \ | |
50 | ((EH)->elf.root.type == bfd_link_hash_undefweak \ | |
51 | && ((EH)->elf.forced_local \ | |
52 | || (bfd_link_executable (INFO) \ | |
53 | && (elf_x86_hash_table ((INFO), (ID))->interp == NULL \ | |
54 | || !(GOT_RELOC) \ | |
55 | || (EH)->has_non_got_reloc \ | |
56 | || !(INFO)->dynamic_undefined_weak)))) | |
57 | ||
58 | /* Should copy relocation be generated for a symbol. Don't generate | |
59 | copy relocation against a protected symbol defined in a shared | |
60 | object with GNU_PROPERTY_NO_COPY_ON_PROTECTED. */ | |
61 | #define SYMBOL_NO_COPYRELOC(INFO, EH) \ | |
62 | ((EH)->def_protected \ | |
63 | && ((EH)->elf.root.type == bfd_link_hash_defined \ | |
64 | || (EH)->elf.root.type == bfd_link_hash_defweak) \ | |
65 | && elf_has_no_copy_on_protected ((EH)->elf.root.u.def.section->owner) \ | |
66 | && ((EH)->elf.root.u.def.section->owner->flags & DYNAMIC) != 0 \ | |
67 | && ((EH)->elf.root.u.def.section->flags & SEC_CODE) == 0) | |
68 | ||
69 | /* x86 ELF linker hash entry. */ | |
70 | ||
71 | struct elf_x86_link_hash_entry | |
72 | { | |
73 | struct elf_link_hash_entry elf; | |
74 | ||
75 | /* Track dynamic relocs copied for this symbol. */ | |
76 | struct elf_dyn_relocs *dyn_relocs; | |
77 | ||
78 | unsigned char tls_type; | |
79 | ||
80 | /* TRUE if symbol has GOT or PLT relocations. */ | |
81 | unsigned int has_got_reloc : 1; | |
82 | ||
83 | /* TRUE if symbol has non-GOT/non-PLT relocations in text sections. */ | |
84 | unsigned int has_non_got_reloc : 1; | |
85 | ||
86 | /* Don't call finish_dynamic_symbol on this symbol. */ | |
87 | unsigned int no_finish_dynamic_symbol : 1; | |
88 | ||
89 | /* TRUE if symbol is __tls_get_addr. */ | |
90 | unsigned int tls_get_addr : 1; | |
91 | ||
92 | /* TRUE if symbol is defined as a protected symbol. */ | |
93 | unsigned int def_protected : 1; | |
94 | ||
95 | /* Symbol is referenced by R_386_GOTOFF relocation. This is only used | |
96 | by i386. */ | |
97 | unsigned int gotoff_ref : 1; | |
98 | ||
99 | /* TRUE if a weak symbol with a real definition needs a copy reloc. | |
100 | When there is a weak symbol with a real definition, the processor | |
101 | independent code will have arranged for us to see the real | |
102 | definition first. We need to copy the needs_copy bit from the | |
103 | real definition and check it when allowing copy reloc in PIE. This | |
104 | is only used by x86-64. */ | |
105 | unsigned int needs_copy : 1; | |
106 | ||
107 | /* Reference count of C/C++ function pointer relocations in read-write | |
108 | section which can be resolved at run-time. */ | |
109 | bfd_signed_vma func_pointer_refcount; | |
110 | ||
111 | /* Information about the GOT PLT entry. Filled when there are both | |
112 | GOT and PLT relocations against the same function. */ | |
113 | union gotplt_union plt_got; | |
114 | ||
115 | /* Information about the second PLT entry. */ | |
116 | union gotplt_union plt_second; | |
117 | ||
118 | /* Offset of the GOTPLT entry reserved for the TLS descriptor, | |
119 | starting at the end of the jump table. */ | |
120 | bfd_vma tlsdesc_got; | |
121 | }; | |
122 | ||
765e526c L |
123 | struct elf_x86_lazy_plt_layout |
124 | { | |
125 | /* The first entry in an absolute lazy procedure linkage table looks | |
126 | like this. */ | |
127 | const bfd_byte *plt0_entry; | |
128 | unsigned int plt0_entry_size; /* Size of PLT0 entry. */ | |
129 | ||
130 | /* Later entries in an absolute lazy procedure linkage table look | |
131 | like this. */ | |
132 | const bfd_byte *plt_entry; | |
133 | unsigned int plt_entry_size; /* Size of each PLT entry. */ | |
134 | ||
135 | /* Offsets into plt0_entry that are to be replaced with GOT[1] and | |
136 | GOT[2]. */ | |
137 | unsigned int plt0_got1_offset; | |
138 | unsigned int plt0_got2_offset; | |
139 | ||
140 | /* Offset of the end of the PC-relative instruction containing | |
141 | plt0_got2_offset. This is for x86-64 only. */ | |
142 | unsigned int plt0_got2_insn_end; | |
143 | ||
144 | /* Offsets into plt_entry that are to be replaced with... */ | |
145 | unsigned int plt_got_offset; /* ... address of this symbol in .got. */ | |
146 | unsigned int plt_reloc_offset; /* ... offset into relocation table. */ | |
147 | unsigned int plt_plt_offset; /* ... offset to start of .plt. */ | |
148 | ||
149 | /* Length of the PC-relative instruction containing plt_got_offset. | |
150 | This is used for x86-64 only. */ | |
151 | unsigned int plt_got_insn_size; | |
152 | ||
153 | /* Offset of the end of the PC-relative jump to plt0_entry. This is | |
154 | used for x86-64 only. */ | |
155 | unsigned int plt_plt_insn_end; | |
156 | ||
157 | /* Offset into plt_entry where the initial value of the GOT entry | |
158 | points. */ | |
159 | unsigned int plt_lazy_offset; | |
160 | ||
161 | /* The first entry in a PIC lazy procedure linkage table looks like | |
a6798bab | 162 | this. */ |
765e526c L |
163 | const bfd_byte *pic_plt0_entry; |
164 | ||
165 | /* Subsequent entries in a PIC lazy procedure linkage table look | |
a6798bab | 166 | like this. */ |
765e526c L |
167 | const bfd_byte *pic_plt_entry; |
168 | ||
169 | /* .eh_frame covering the lazy .plt section. */ | |
170 | const bfd_byte *eh_frame_plt; | |
171 | unsigned int eh_frame_plt_size; | |
172 | }; | |
173 | ||
174 | struct elf_x86_non_lazy_plt_layout | |
175 | { | |
176 | /* Entries in an absolute non-lazy procedure linkage table look like | |
177 | this. */ | |
178 | const bfd_byte *plt_entry; | |
a6798bab | 179 | /* Entries in a PIC non-lazy procedure linkage table look like this. */ |
765e526c L |
180 | const bfd_byte *pic_plt_entry; |
181 | ||
182 | unsigned int plt_entry_size; /* Size of each PLT entry. */ | |
183 | ||
184 | /* Offsets into plt_entry that are to be replaced with... */ | |
185 | unsigned int plt_got_offset; /* ... address of this symbol in .got. */ | |
186 | ||
187 | /* Length of the PC-relative instruction containing plt_got_offset. | |
188 | This is used for x86-64 only. */ | |
189 | unsigned int plt_got_insn_size; | |
190 | ||
191 | /* .eh_frame covering the non-lazy .plt section. */ | |
192 | const bfd_byte *eh_frame_plt; | |
193 | unsigned int eh_frame_plt_size; | |
194 | }; | |
195 | ||
196 | struct elf_x86_plt_layout | |
197 | { | |
198 | /* The first entry in a lazy procedure linkage table looks like this. | |
199 | This is only used for i386 where absolute PLT0 and PIC PLT0 are | |
200 | different. */ | |
201 | const bfd_byte *plt0_entry; | |
202 | /* Entries in a procedure linkage table look like this. */ | |
203 | const bfd_byte *plt_entry; | |
204 | unsigned int plt_entry_size; /* Size of each PLT entry. */ | |
205 | ||
206 | /* 1 has PLT0. */ | |
207 | unsigned int has_plt0; | |
208 | ||
209 | /* Offsets into plt_entry that are to be replaced with... */ | |
210 | unsigned int plt_got_offset; /* ... address of this symbol in .got. */ | |
211 | ||
212 | /* Length of the PC-relative instruction containing plt_got_offset. | |
213 | This is only used for x86-64. */ | |
214 | unsigned int plt_got_insn_size; | |
215 | ||
216 | /* .eh_frame covering the .plt section. */ | |
217 | const bfd_byte *eh_frame_plt; | |
218 | unsigned int eh_frame_plt_size; | |
219 | }; | |
220 | ||
0afcef53 L |
221 | /* The first 3 values in tls_type of x86 ELF linker hash entry. */ |
222 | #define GOT_UNKNOWN 0 | |
223 | #define GOT_NORMAL 1 | |
224 | #define GOT_TLS_GD 2 | |
225 | ||
226 | #define elf_x86_hash_entry(ent) \ | |
227 | ((struct elf_x86_link_hash_entry *)(ent)) | |
228 | ||
229 | /* x86 ELF linker hash table. */ | |
230 | ||
231 | struct elf_x86_link_hash_table | |
232 | { | |
233 | struct elf_link_hash_table elf; | |
234 | ||
235 | /* Short-cuts to get to dynamic linker sections. */ | |
236 | asection *interp; | |
237 | asection *plt_eh_frame; | |
238 | asection *plt_second; | |
239 | asection *plt_second_eh_frame; | |
240 | asection *plt_got; | |
241 | asection *plt_got_eh_frame; | |
242 | ||
765e526c L |
243 | /* Parameters describing PLT generation, lazy or non-lazy. */ |
244 | struct elf_x86_plt_layout plt; | |
245 | ||
246 | /* Parameters describing lazy PLT generation. */ | |
247 | const struct elf_x86_lazy_plt_layout *lazy_plt; | |
248 | ||
249 | /* Parameters describing non-lazy PLT generation. */ | |
250 | const struct elf_x86_non_lazy_plt_layout *non_lazy_plt; | |
251 | ||
0afcef53 L |
252 | union |
253 | { | |
254 | bfd_signed_vma refcount; | |
255 | bfd_vma offset; | |
256 | } tls_ld_or_ldm_got; | |
257 | ||
258 | /* The amount of space used by the jump slots in the GOT. */ | |
259 | bfd_vma sgotplt_jump_table_size; | |
260 | ||
261 | /* Small local sym cache. */ | |
262 | struct sym_cache sym_cache; | |
263 | ||
264 | /* _TLS_MODULE_BASE_ symbol. */ | |
265 | struct bfd_link_hash_entry *tls_module_base; | |
266 | ||
267 | /* Used by local STT_GNU_IFUNC symbols. */ | |
268 | htab_t loc_hash_table; | |
269 | void * loc_hash_memory; | |
270 | ||
271 | /* The offset into splt of the PLT entry for the TLS descriptor | |
272 | resolver. Special values are 0, if not necessary (or not found | |
273 | to be necessary yet), and -1 if needed but not determined | |
274 | yet. */ | |
275 | bfd_vma tlsdesc_plt; | |
276 | ||
277 | /* The offset into sgot of the GOT entry used by the PLT entry | |
278 | above. */ | |
279 | bfd_vma tlsdesc_got; | |
280 | ||
281 | /* The index of the next R_X86_64_JUMP_SLOT entry in .rela.plt. */ | |
282 | bfd_vma next_jump_slot_index; | |
283 | /* The index of the next R_X86_64_IRELATIVE entry in .rela.plt. */ | |
284 | bfd_vma next_irelative_index; | |
285 | ||
286 | /* TRUE if there are dynamic relocs against IFUNC symbols that apply | |
287 | to read-only sections. */ | |
288 | bfd_boolean readonly_dynrelocs_against_ifunc; | |
289 | ||
765e526c L |
290 | /* The (unloaded but important) .rel.plt.unloaded section on VxWorks. |
291 | This is used for i386 only. */ | |
292 | asection *srelplt2; | |
293 | ||
294 | /* The index of the next unused R_386_TLS_DESC slot in .rel.plt. This | |
295 | is used for i386 only. */ | |
296 | bfd_vma next_tls_desc_index; | |
297 | ||
0afcef53 L |
298 | bfd_vma (*r_info) (bfd_vma, bfd_vma); |
299 | bfd_vma (*r_sym) (bfd_vma); | |
300 | unsigned int pointer_r_type; | |
301 | int dynamic_interpreter_size; | |
302 | const char *dynamic_interpreter; | |
303 | const char *tls_get_addr; | |
304 | }; | |
305 | ||
a6798bab L |
306 | struct elf_x86_plt_layout_table |
307 | { | |
308 | /* The lazy PLT layout. */ | |
309 | const struct elf_x86_lazy_plt_layout *lazy_plt; | |
310 | ||
311 | /* The non-lazy PLT layout. */ | |
312 | const struct elf_x86_non_lazy_plt_layout *non_lazy_plt; | |
313 | ||
314 | /* The lazy PLT layout for IBT. */ | |
315 | const struct elf_x86_lazy_plt_layout *lazy_ibt_plt; | |
316 | ||
317 | /* The non-lazy PLT layout for IBT. */ | |
318 | const struct elf_x86_non_lazy_plt_layout *non_lazy_ibt_plt; | |
319 | ||
c6295c22 | 320 | /* TRUE if this is a normal x86 target. */ |
a6798bab L |
321 | bfd_boolean normal_target; |
322 | ||
323 | /* TRUE if this is a VxWorks x86 target. */ | |
324 | bfd_boolean is_vxworks; | |
325 | }; | |
326 | ||
0afcef53 L |
327 | struct elf_x86_obj_tdata |
328 | { | |
329 | struct elf_obj_tdata root; | |
330 | ||
331 | /* tls_type for each local got entry. */ | |
332 | char *local_got_tls_type; | |
333 | ||
334 | /* GOTPLT entries for TLS descriptors. */ | |
335 | bfd_vma *local_tlsdesc_gotent; | |
336 | }; | |
337 | ||
f493882d L |
338 | enum elf_x86_plt_type |
339 | { | |
340 | plt_non_lazy = 0, | |
341 | plt_lazy = 1 << 0, | |
342 | plt_pic = 1 << 1, | |
343 | plt_second = 1 << 2, | |
344 | plt_unknown = -1 | |
345 | }; | |
346 | ||
347 | struct elf_x86_plt | |
348 | { | |
349 | const char *name; | |
350 | asection *sec; | |
351 | bfd_byte *contents; | |
352 | enum elf_x86_plt_type type; | |
353 | unsigned int plt_got_offset; | |
354 | unsigned int plt_entry_size; | |
355 | unsigned int plt_got_insn_size; /* Only used for x86-64. */ | |
356 | long count; | |
357 | }; | |
358 | ||
0afcef53 L |
359 | #define elf_x86_tdata(abfd) \ |
360 | ((struct elf_x86_obj_tdata *) (abfd)->tdata.any) | |
361 | ||
362 | #define elf_x86_local_got_tls_type(abfd) \ | |
363 | (elf_x86_tdata (abfd)->local_got_tls_type) | |
364 | ||
365 | #define elf_x86_local_tlsdesc_gotent(abfd) \ | |
366 | (elf_x86_tdata (abfd)->local_tlsdesc_gotent) | |
367 | ||
39946cc2 L |
368 | extern bfd_boolean _bfd_x86_elf_mkobject |
369 | (bfd *); | |
370 | ||
0afcef53 L |
371 | extern void _bfd_x86_elf_set_tls_module_base |
372 | (struct bfd_link_info *); | |
373 | ||
374 | extern bfd_vma _bfd_x86_elf_dtpoff_base | |
375 | (struct bfd_link_info *); | |
376 | ||
377 | extern bfd_boolean _bfd_x86_elf_readonly_dynrelocs | |
378 | (struct elf_link_hash_entry *, void *); | |
379 | ||
380 | extern struct elf_link_hash_entry * _bfd_elf_x86_get_local_sym_hash | |
381 | (struct elf_x86_link_hash_table *, bfd *, const Elf_Internal_Rela *, | |
382 | bfd_boolean); | |
383 | ||
384 | extern hashval_t _bfd_x86_elf_local_htab_hash | |
385 | (const void *); | |
386 | ||
387 | extern int _bfd_x86_elf_local_htab_eq | |
388 | (const void *, const void *); | |
389 | ||
390 | extern struct bfd_hash_entry * _bfd_x86_elf_link_hash_newfunc | |
391 | (struct bfd_hash_entry *, struct bfd_hash_table *, const char *); | |
392 | ||
765e526c | 393 | extern struct bfd_link_hash_table * _bfd_x86_elf_link_hash_table_create |
0afcef53 L |
394 | (bfd *); |
395 | ||
396 | extern int _bfd_x86_elf_compare_relocs | |
397 | (const void *, const void *); | |
398 | ||
399 | extern bfd_boolean _bfd_x86_elf_link_check_relocs | |
400 | (bfd *, struct bfd_link_info *); | |
401 | ||
402 | extern bfd_boolean _bfd_x86_elf_always_size_sections | |
403 | (bfd *, struct bfd_link_info *); | |
404 | ||
405 | extern void _bfd_x86_elf_merge_symbol_attribute | |
406 | (struct elf_link_hash_entry *, const Elf_Internal_Sym *, | |
407 | bfd_boolean, bfd_boolean); | |
408 | ||
409 | extern void _bfd_x86_elf_copy_indirect_symbol | |
410 | (struct bfd_link_info *, struct elf_link_hash_entry *, | |
411 | struct elf_link_hash_entry *); | |
412 | ||
413 | extern bfd_boolean _bfd_x86_elf_fixup_symbol | |
414 | (struct bfd_link_info *, struct elf_link_hash_entry *); | |
415 | ||
416 | extern bfd_boolean _bfd_x86_elf_hash_symbol | |
417 | (struct elf_link_hash_entry *); | |
418 | ||
f493882d L |
419 | extern long _bfd_x86_elf_get_synthetic_symtab |
420 | (bfd *, long, long, bfd_vma, struct elf_x86_plt [], asymbol **, | |
421 | asymbol **); | |
422 | ||
0afcef53 L |
423 | extern enum elf_property_kind _bfd_x86_elf_parse_gnu_properties |
424 | (bfd *, unsigned int, bfd_byte *, unsigned int); | |
425 | ||
426 | extern bfd_boolean _bfd_x86_elf_merge_gnu_properties | |
427 | (struct bfd_link_info *, bfd *, elf_property *, elf_property *); | |
428 | ||
a6798bab L |
429 | extern bfd * _bfd_x86_elf_link_setup_gnu_properties |
430 | (struct bfd_link_info *, struct elf_x86_plt_layout_table *); | |
431 | ||
39946cc2 L |
432 | #define bfd_elf64_mkobject \ |
433 | _bfd_x86_elf_mkobject | |
434 | #define bfd_elf32_mkobject \ | |
435 | _bfd_x86_elf_mkobject | |
765e526c L |
436 | #define bfd_elf64_bfd_link_hash_table_create \ |
437 | _bfd_x86_elf_link_hash_table_create | |
438 | #define bfd_elf32_bfd_link_hash_table_create \ | |
439 | _bfd_x86_elf_link_hash_table_create | |
0afcef53 L |
440 | #define bfd_elf64_bfd_link_check_relocs \ |
441 | _bfd_x86_elf_link_check_relocs | |
442 | #define bfd_elf32_bfd_link_check_relocs \ | |
443 | _bfd_x86_elf_link_check_relocs | |
444 | ||
445 | #define elf_backend_always_size_sections \ | |
446 | _bfd_x86_elf_always_size_sections | |
447 | #define elf_backend_merge_symbol_attribute \ | |
448 | _bfd_x86_elf_merge_symbol_attribute | |
449 | #define elf_backend_copy_indirect_symbol \ | |
450 | _bfd_x86_elf_copy_indirect_symbol | |
451 | #define elf_backend_fixup_symbol \ | |
452 | _bfd_x86_elf_fixup_symbol | |
453 | #define elf_backend_hash_symbol \ | |
454 | _bfd_x86_elf_hash_symbol | |
455 | #define elf_backend_omit_section_dynsym \ | |
456 | ((bfd_boolean (*) (bfd *, struct bfd_link_info *, asection *)) bfd_true) | |
457 | #define elf_backend_parse_gnu_properties \ | |
458 | _bfd_x86_elf_parse_gnu_properties | |
459 | #define elf_backend_merge_gnu_properties \ | |
460 | _bfd_x86_elf_merge_gnu_properties |