1 /* x86 specific support for ELF
2 Copyright (C) 2017-2024 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 /* Don't generate unused section symbols. */
22 #define TARGET_KEEP_UNUSED_SECTION_SYMBOLS false
23
24 #include "sysdep.h"
25 #include "bfd.h"
26 #include "bfdlink.h"
27 #include "libbfd.h"
28 #include "elf-bfd.h"
29 #include "hashtab.h"
30 #include "elf-linker-x86.h"
31 #include "elf/i386.h"
32 #include "elf/x86-64.h"
33 #include "sframe-api.h"
34
35 #define X86_64_PCREL_TYPE_P(TYPE) \
36 ((TYPE) == R_X86_64_PC8 \
37 || (TYPE) == R_X86_64_PC16 \
38 || (TYPE) == R_X86_64_PC32 \
39 || (TYPE) == R_X86_64_PC64)
40 #define I386_PCREL_TYPE_P(TYPE) ((TYPE) == R_386_PC32)
41 #define X86_PCREL_TYPE_P(IS_X86_64, TYPE) \
42 ((IS_X86_64) ? X86_64_PCREL_TYPE_P (TYPE) : I386_PCREL_TYPE_P (TYPE))
43
44 #define X86_64_SIZE_TYPE_P(TYPE) \
45 ((TYPE) == R_X86_64_SIZE32 || (TYPE) == R_X86_64_SIZE64)
46 #define I386_SIZE_TYPE_P(TYPE) ((TYPE) == R_386_SIZE32)
47 #define X86_SIZE_TYPE_P(IS_X86_64, TYPE) \
48 ((IS_X86_64) ? X86_64_SIZE_TYPE_P(TYPE) : I386_SIZE_TYPE_P (TYPE))
49
50 #define X86_64_GOT_TYPE_P(TYPE) \
51 ((TYPE) == R_X86_64_GOTPCREL \
52 || (TYPE) == R_X86_64_GOTPCRELX \
53 || (TYPE) == R_X86_64_REX_GOTPCRELX \
54 || (TYPE) == R_X86_64_GOT32 \
55 || (TYPE) == R_X86_64_GOT64 \
56 || (TYPE) == R_X86_64_GOTPCREL64 \
57 || (TYPE) == R_X86_64_GOTPLT64)
58 #define I386_GOT_TYPE_P(TYPE) \
59 ((TYPE) == R_386_GOT32 || (TYPE) == R_386_GOT32X)
60 #define X86_GOT_TYPE_P(IS_X86_64, TYPE) \
61 ((IS_X86_64) ? X86_64_GOT_TYPE_P (TYPE) : I386_GOT_TYPE_P (TYPE))
62
63 #define X86_64_RELATIVE_RELOC_TYPE_P(TYPE) \
64 (X86_64_PCREL_TYPE_P (TYPE) \
65 || (TYPE) == R_X86_64_8 \
66 || (TYPE) == R_X86_64_16 \
67 || (TYPE) == R_X86_64_32 \
68 || (TYPE) == R_X86_64_32S \
69 || (TYPE) == R_X86_64_64)
70 #define I386_RELATIVE_RELOC_TYPE_P(TYPE) \
71 ((TYPE) == R_386_32 || (TYPE) == R_386_PC32)
72 #define X86_RELATIVE_RELOC_TYPE_P(IS_X86_64, TYPE) \
73 ((IS_X86_64) \
74 ? X86_64_RELATIVE_RELOC_TYPE_P (TYPE) \
75 : I386_RELATIVE_RELOC_TYPE_P(TYPE))
76
77 #define X86_64_NEED_DYNAMIC_RELOC_TYPE_P(TYPE) \
78 (X86_64_SIZE_TYPE_P (TYPE) \
79 || X86_64_RELATIVE_RELOC_TYPE_P (TYPE))
80 #define I386_NEED_DYNAMIC_RELOC_TYPE_P(TYPE) \
81 (I386_SIZE_TYPE_P (TYPE) \
82 || I386_RELATIVE_RELOC_TYPE_P (TYPE) \
83 || (TYPE) == R_386_TLS_IE \
84 || (TYPE) == R_386_TLS_LE \
85 || (TYPE) == R_386_TLS_LE_32)
86 #define X86_NEED_DYNAMIC_RELOC_TYPE_P(IS_X86_64, TYPE) \
87 ((IS_X86_64) \
88 ? X86_64_NEED_DYNAMIC_RELOC_TYPE_P (TYPE) \
89 : I386_NEED_DYNAMIC_RELOC_TYPE_P (TYPE))
90
91 #define X86_LOCAL_GOT_RELATIVE_RELOC_P(IS_X86_64, INFO, SYM) \
92 (bfd_link_pic (INFO) \
93 && (!(IS_X86_64) || ((SYM) != NULL && (SYM)->st_shndx != SHN_ABS)))
94
95 #define PLT_CIE_LENGTH 20
96 #define PLT_FDE_LENGTH 36
97 #define PLT_FDE_START_OFFSET 4 + PLT_CIE_LENGTH + 8
98 #define PLT_FDE_LEN_OFFSET 4 + PLT_CIE_LENGTH + 12
99
100 /* This must be the same as sframe_get_hdr_size (sfh). For x86-64, this value
101 is the same as sizeof (sframe_header) because there is no SFrame auxilliary
102 header. */
103 #define PLT_SFRAME_FDE_START_OFFSET sizeof (sframe_header)
104
105 #define ABI_64_P(abfd) \
106 (get_elf_backend_data (abfd)->s->elfclass == ELFCLASS64)
107
108 /* If ELIMINATE_COPY_RELOCS is non-zero, the linker will try to avoid
109 copying dynamic variables from a shared lib into an app's dynbss
110 section, and instead use a dynamic relocation to point into the
111 shared lib. */
112 #define ELIMINATE_COPY_RELOCS 1
113
114 #define elf_x86_hash_table(p, id) \
115 (is_elf_hash_table ((p)->hash) \
116 && elf_hash_table_id ((struct elf_link_hash_table *) ((p)->hash)) == (id) \
117 ? ((struct elf_x86_link_hash_table *) ((p)->hash)) : NULL)
118
119 /* Will references to this symbol always be local in this object? */
120 #define SYMBOL_REFERENCES_LOCAL_P(INFO, H) \
121 _bfd_x86_elf_link_symbol_references_local ((INFO), (H))
122
123 /* TRUE if an undefined weak symbol should be resolved to 0. Local
124 undefined weak symbol is always resolved to 0. Reference to an
125 undefined weak symbol is resolved to 0 in executable if undefined
126 weak symbol should be resolved to 0 (zero_undefweak > 0). */
127 #define UNDEFINED_WEAK_RESOLVED_TO_ZERO(INFO, EH) \
128 ((EH)->elf.root.type == bfd_link_hash_undefweak \
129 && (SYMBOL_REFERENCES_LOCAL_P ((INFO), &(EH)->elf) \
130 || (bfd_link_executable (INFO) \
131 && (EH)->zero_undefweak > 0)))
132
133 /* Should copy relocation be generated for a symbol. Don't generate
134 copy relocation against a protected symbol defined in a shared
135 object. */
136 #define SYMBOL_NO_COPYRELOC(INFO, EH) \
137 ((EH)->def_protected \
138 && ((EH)->elf.root.type == bfd_link_hash_defined \
139 || (EH)->elf.root.type == bfd_link_hash_defweak) \
140 && ((EH)->elf.root.u.def.section->owner->flags & DYNAMIC) != 0 \
141 && ((EH)->elf.root.u.def.section->flags & SEC_CODE) == 0)
142
143 /* TRUE if dynamic relocation is needed. If we are creating a shared
144 library, and this is a reloc against a global symbol, or a non PC
145 relative reloc against a local symbol, then we need to copy the reloc
146 into the shared library. However, if we are linking with -Bsymbolic,
147 we do not need to copy a reloc against a global symbol which is
148 defined in an object we are including in the link (i.e., DEF_REGULAR
149 is set).
150
151 If PCREL_PLT is true, don't generate dynamic relocation in PIE for
152 PC-relative relocation against a dynamic function definition in data
153 section when PLT address can be used.
154
155 If on the other hand, we are creating an executable, we may need to
156 keep relocations for symbols satisfied by a dynamic library if we
157 manage to avoid copy relocs for the symbol.
158
159 We also need to generate dynamic pointer relocation against
160 STT_GNU_IFUNC symbol in the non-code section. */
161 #define NEED_DYNAMIC_RELOCATION_P(IS_X86_64, INFO, PCREL_PLT, H, SEC, \
162 R_TYPE, POINTER_TYPE) \
163 ((bfd_link_pic (INFO) \
164 && (! X86_PCREL_TYPE_P (IS_X86_64, R_TYPE) \
165 || ((H) != NULL \
166 && (! (bfd_link_pie (INFO) \
167 || SYMBOLIC_BIND ((INFO), (H))) \
168 || (H)->root.type == bfd_link_hash_defweak \
169 || (!(bfd_link_pie (INFO) \
170 && (PCREL_PLT) \
171 && (H)->plt.refcount > 0 \
172 && ((SEC)->flags & SEC_CODE) == 0 \
173 && (H)->type == STT_FUNC \
174 && (H)->def_dynamic) \
175 && !(H)->def_regular))))) \
176 || ((H) != NULL \
177 && (H)->type == STT_GNU_IFUNC \
178 && (R_TYPE) == POINTER_TYPE \
179 && ((SEC)->flags & SEC_CODE) == 0) \
180 || (ELIMINATE_COPY_RELOCS \
181 && !bfd_link_pic (INFO) \
182 && (H) != NULL \
183 && ((H)->root.type == bfd_link_hash_defweak \
184 || !(H)->def_regular)))
185
186 /* TRUE if dynamic relocation should be generated. Don't copy a
187 pc-relative relocation into the output file if the symbol needs
188 copy reloc or the symbol is undefined when building executable.
189 Copy dynamic function pointer relocations. Don't generate dynamic
190 relocations against resolved undefined weak symbols in PIE, except
191 when PC32_RELOC is TRUE. Undefined weak symbol is bound locally
192 when PIC is false. Don't generate dynamic relocations against
193 non-preemptible absolute symbol. NB: rel_from_abs is set on symbols
194 defined by linker scripts from "dot" (also SEGMENT_START or ORIGIN)
195 outside of an output section statement, which will be converted from
196 absolute to section-relative in set_sym_sections called from
197 ldexp_finalize_syms after ldemul_finish. */
198 #define GENERATE_DYNAMIC_RELOCATION_P(IS_X86_64, INFO, EH, R_TYPE, \
199 SEC, NEED_COPY_RELOC_IN_PIE, \
200 RESOLVED_TO_ZERO, PC32_RELOC) \
201 ((bfd_link_pic (INFO) \
202 && !(bfd_is_abs_section (SEC) \
203 && ((EH) == NULL \
204 || (EH)->elf.root.rel_from_abs == 0) \
205 && ((EH) == NULL \
206 || SYMBOL_REFERENCES_LOCAL (INFO, &(EH)->elf))) \
207 && !(NEED_COPY_RELOC_IN_PIE) \
208 && ((EH) == NULL \
209 || ((ELF_ST_VISIBILITY ((EH)->elf.other) == STV_DEFAULT \
210 && (!(RESOLVED_TO_ZERO) || PC32_RELOC)) \
211 || (EH)->elf.root.type != bfd_link_hash_undefweak)) \
212 && ((!X86_PCREL_TYPE_P (IS_X86_64, R_TYPE) \
213 && !X86_SIZE_TYPE_P (IS_X86_64, R_TYPE)) \
214 || ! SYMBOL_CALLS_LOCAL ((INFO), \
215 (struct elf_link_hash_entry *) (EH)))) \
216 || (ELIMINATE_COPY_RELOCS \
217 && !bfd_link_pic (INFO) \
218 && (EH) != NULL \
219 && (EH)->elf.dynindx != -1 \
220 && (!(EH)->elf.non_got_ref \
221 || ((EH)->elf.root.type == bfd_link_hash_undefweak \
222 && !(RESOLVED_TO_ZERO))) \
223 && (((EH)->elf.def_dynamic && !(EH)->elf.def_regular) \
224 || (EH)->elf.root.type == bfd_link_hash_undefined)))
225
226 /* TRUE if this input relocation should be copied to output. H->dynindx
227 may be -1 if this symbol was marked to become local. */
228 #define COPY_INPUT_RELOC_P(IS_X86_64, INFO, H, R_TYPE) \
229 ((H) != NULL \
230 && (H)->dynindx != -1 \
231 && (X86_PCREL_TYPE_P (IS_X86_64, R_TYPE) \
232 || !(bfd_link_executable (INFO) || SYMBOLIC_BIND ((INFO), (H))) \
233 || !(H)->def_regular))
234
235 /* TRUE if this is actually a static link, or it is a -Bsymbolic link
236 and the symbol is defined locally, or the symbol was forced to be
237 local because of a version file. */
238 #define RESOLVED_LOCALLY_P(INFO, H, HTAB) \
239 (!WILL_CALL_FINISH_DYNAMIC_SYMBOL ((HTAB)->elf.dynamic_sections_created, \
240 bfd_link_pic (INFO), (H)) \
241 || (bfd_link_pic (INFO) \
242 && SYMBOL_REFERENCES_LOCAL_P ((INFO), (H))) \
243 || (ELF_ST_VISIBILITY ((H)->other) \
244 && (H)->root.type == bfd_link_hash_undefweak))
245
246 /* TRUE if this symbol isn't defined by a shared object. */
247 #define SYMBOL_DEFINED_NON_SHARED_P(H) \
248 ((H)->def_regular \
249 || (H)->root.linker_def \
250 || (H)->root.ldscript_def \
251 || ((struct elf_x86_link_hash_entry *) (H))->linker_def \
252 || ELF_COMMON_DEF_P (H))
253
254 /* Return TRUE if the symbol described by a linker hash entry H is
255 going to be absolute. Similar to bfd_is_abs_symbol, but excluding
256 all linker-script defined symbols. */
257 #define ABS_SYMBOL_P(H) \
258 (bfd_is_abs_symbol (&(H)->root) && !(H)->root.ldscript_def)
259
260 /* TRUE if relative relocation should be generated. GOT reference to
261 global symbol in PIC will lead to dynamic symbol. It becomes a
262 problem when "time" or "times" is defined as a variable in an
263 executable, clashing with functions of the same name in libc. If a
264 symbol isn't undefined weak symbol, don't make it dynamic in PIC and
265 generate relative relocation. Don't generate relative relocation
266 against non-preemptible absolute symbol. */
267 #define GENERATE_RELATIVE_RELOC_P(INFO, H) \
268 ((H)->dynindx == -1 \
269 && !(H)->forced_local \
270 && (H)->root.type != bfd_link_hash_undefweak \
271 && bfd_link_pic (INFO) \
272 && !ABS_SYMBOL_P (H))
273
274 /* TRUE if this is a pointer reference to a local IFUNC. */
275 #define POINTER_LOCAL_IFUNC_P(INFO, H) \
276 ((H)->dynindx == -1 \
277 || (H)->forced_local \
278 || bfd_link_executable (INFO))
279
280 /* TRUE if this is a PLT reference to a local IFUNC. */
281 #define PLT_LOCAL_IFUNC_P(INFO, H) \
282 ((H)->dynindx == -1 \
283 || ((bfd_link_executable (INFO) \
284 || ELF_ST_VISIBILITY ((H)->other) != STV_DEFAULT) \
285 && (H)->def_regular \
286 && (H)->type == STT_GNU_IFUNC))
287
288 /* TRUE if TLS IE->LE transition is OK. */
289 #define TLS_TRANSITION_IE_TO_LE_P(INFO, H, TLS_TYPE) \
290 (bfd_link_executable (INFO) \
291 && (H) != NULL \
292 && (H)->dynindx == -1 \
293 && (TLS_TYPE & GOT_TLS_IE))
294
295 /* Verify that the symbol has an entry in the procedure linkage table. */
296 #define VERIFY_PLT_ENTRY(INFO, H, PLT, GOTPLT, RELPLT, LOCAL_UNDEFWEAK) \
297 do \
298 { \
299 if (((H)->dynindx == -1 \
300 && !LOCAL_UNDEFWEAK \
301 && !(((H)->forced_local || bfd_link_executable (INFO)) \
302 && (H)->def_regular \
303 && (H)->type == STT_GNU_IFUNC)) \
304 || (PLT) == NULL \
305 || (GOTPLT) == NULL \
306 || (RELPLT) == NULL) \
307 abort (); \
308 } \
309 while (0);
310
311 /* Verify that the symbol supports copy relocation. */
312 #define VERIFY_COPY_RELOC(H, HTAB) \
313 do \
314 { \
315 if ((H)->dynindx == -1 \
316 || ((H)->root.type != bfd_link_hash_defined \
317 && (H)->root.type != bfd_link_hash_defweak) \
318 || (HTAB)->elf.srelbss == NULL \
319 || (HTAB)->elf.sreldynrelro == NULL) \
320 abort (); \
321 } \
322 while (0);
323
324 /* x86 ELF linker hash entry. */
325
326 struct elf_x86_link_hash_entry
327 {
328 struct elf_link_hash_entry elf;
329
330 unsigned char tls_type;
331
332 /* Bit 0: Symbol has no GOT nor PLT relocations.
333 Bit 1: Symbol has non-GOT/non-PLT relocations in text sections.
334 zero_undefweak is initialized to 1 and undefined weak symbol
335 should be resolved to 0 if zero_undefweak > 0. */
336 unsigned int zero_undefweak : 2;
337
338 /* Don't call finish_dynamic_symbol on this symbol. */
339 unsigned int no_finish_dynamic_symbol : 1;
340
341 /* R_*_RELATIVE relocation in GOT for this symbol has been
342 processed. */
343 unsigned int got_relative_reloc_done : 1;
344
345 /* TRUE if symbol is __tls_get_addr. */
346 unsigned int tls_get_addr : 1;
347
348 /* TRUE if symbol is defined as a protected symbol. */
349 unsigned int def_protected : 1;
350
351 /* 0: Symbol references are unknown.
352 1: Symbol references aren't local.
353 2: Symbol references are local.
354 */
355 unsigned int local_ref : 2;
356
357 /* TRUE if symbol is defined by linker. */
358 unsigned int linker_def : 1;
359
360 /* TRUE if symbol is referenced by a non-GOT/non-PLT relocation in a
361 relocatable object file without indirect external access marker. */
362 unsigned int non_got_ref_without_indirect_extern_access : 1;
363
364 /* TRUE if symbol is referenced by R_386_GOTOFF relocation. This is
365 only used by i386. */
366 unsigned int gotoff_ref : 1;
367
368 /* TRUE if a weak symbol with a real definition needs a copy reloc.
369 When there is a weak symbol with a real definition, the processor
370 independent code will have arranged for us to see the real
371 definition first. We need to copy the needs_copy bit from the
372 real definition and check it when allowing copy reloc in PIE. This
373 is only used by x86-64. */
374 unsigned int needs_copy : 1;
375
376 /* Information about the GOT PLT entry. Filled when there are both
377 GOT and PLT relocations against the same function. */
378 union gotplt_union plt_got;
379
380 /* Information about the second PLT entry. */
381 union gotplt_union plt_second;
382
383 /* Offset of the GOTPLT entry reserved for the TLS descriptor,
384 starting at the end of the jump table. */
385 bfd_vma tlsdesc_got;
386 };
387
388 #define SFRAME_PLT0_MAX_NUM_FRES 2
389 #define SFRAME_PLTN_MAX_NUM_FRES 2
390
391 struct elf_x86_sframe_plt
392 {
393 unsigned int plt0_entry_size;
394 unsigned int plt0_num_fres;
395 const sframe_frame_row_entry *plt0_fres[SFRAME_PLT0_MAX_NUM_FRES];
396
397 unsigned int pltn_entry_size;
398 unsigned int pltn_num_fres;
399 const sframe_frame_row_entry *pltn_fres[SFRAME_PLTN_MAX_NUM_FRES];
400
401 unsigned int sec_pltn_entry_size;
402 unsigned int sec_pltn_num_fres;
403 const sframe_frame_row_entry *sec_pltn_fres[SFRAME_PLTN_MAX_NUM_FRES];
404 };
405
406 struct elf_x86_lazy_plt_layout
407 {
408 /* The first entry in a lazy procedure linkage table looks like this. */
409 const bfd_byte *plt0_entry;
410 unsigned int plt0_entry_size; /* Size of PLT0 entry. */
411
412 /* Later entries in a lazy procedure linkage table look like this. */
413 const bfd_byte *plt_entry;
414 unsigned int plt_entry_size; /* Size of each PLT entry. */
415
416 /* The TLSDESC entry in a lazy procedure linkage table looks like
417 this. This is for x86-64 only. */
418 const bfd_byte *plt_tlsdesc_entry;
419 unsigned int plt_tlsdesc_entry_size; /* Size of TLSDESC entry. */
420
421 /* Offsets into the TLSDESC entry that are to be replaced with
422 GOT+8 and GOT+TDG. These are for x86-64 only. */
423 unsigned int plt_tlsdesc_got1_offset;
424 unsigned int plt_tlsdesc_got2_offset;
425
426 /* Offset of the end of the PC-relative instructions containing
427 plt_tlsdesc_got1_offset and plt_tlsdesc_got2_offset. These
428 are for x86-64 only. */
429 unsigned int plt_tlsdesc_got1_insn_end;
430 unsigned int plt_tlsdesc_got2_insn_end;
431
432 /* Offsets into plt0_entry that are to be replaced with GOT[1] and
433 GOT[2]. */
434 unsigned int plt0_got1_offset;
435 unsigned int plt0_got2_offset;
436
437 /* Offset of the end of the PC-relative instruction containing
438 plt0_got2_offset. This is for x86-64 only. */
439 unsigned int plt0_got2_insn_end;
440
441 /* Offsets into plt_entry that are to be replaced with... */
442 unsigned int plt_got_offset; /* ... address of this symbol in .got. */
443 unsigned int plt_reloc_offset; /* ... offset into relocation table. */
444 unsigned int plt_plt_offset; /* ... offset to start of .plt. */
445
446 /* Length of the PC-relative instruction containing plt_got_offset.
447 This is used for x86-64 only. */
448 unsigned int plt_got_insn_size;
449
450 /* Offset of the end of the PC-relative jump to plt0_entry. This is
451 used for x86-64 only. */
452 unsigned int plt_plt_insn_end;
453
454 /* Offset into plt_entry where the initial value of the GOT entry
455 points. */
456 unsigned int plt_lazy_offset;
457
458 /* The first entry in a PIC lazy procedure linkage table looks like
459 this. */
460 const bfd_byte *pic_plt0_entry;
461
462 /* Subsequent entries in a PIC lazy procedure linkage table look
463 like this. */
464 const bfd_byte *pic_plt_entry;
465
466 /* .eh_frame covering the lazy .plt section. */
467 const bfd_byte *eh_frame_plt;
468 unsigned int eh_frame_plt_size;
469 };
470
471 struct elf_x86_non_lazy_plt_layout
472 {
473 /* Entries in a non-lazy procedure linkage table look like this. */
474 const bfd_byte *plt_entry;
475 /* Entries in a PIC non-lazy procedure linkage table look like this.
476 This is only used for i386 where absolute PLT and PIC PLT are
477 different. */
478 const bfd_byte *pic_plt_entry;
479
480 unsigned int plt_entry_size; /* Size of each PLT entry. */
481
482 /* Offsets into plt_entry that are to be replaced with... */
483 unsigned int plt_got_offset; /* ... address of this symbol in .got. */
484
485 /* Length of the PC-relative instruction containing plt_got_offset.
486 This is used for x86-64 only. */
487 unsigned int plt_got_insn_size;
488
489 /* .eh_frame covering the non-lazy .plt section. */
490 const bfd_byte *eh_frame_plt;
491 unsigned int eh_frame_plt_size;
492 };
493
494 struct elf_x86_plt_layout
495 {
496 /* The first entry in a lazy procedure linkage table looks like this. */
497 const bfd_byte *plt0_entry;
498 /* Entries in a procedure linkage table look like this. */
499 const bfd_byte *plt_entry;
500 unsigned int plt_entry_size; /* Size of each PLT entry. */
501
502 /* 1 has PLT0. */
503 unsigned int has_plt0;
504
505 /* Offset of indirect branch in plt_entry. */
506 unsigned int plt_indirect_branch_offset;
507
508 /* Offsets into plt_entry that are to be replaced with... */
509 unsigned int plt_got_offset; /* ... address of this symbol in .got. */
510
511 /* Length of the PC-relative instruction containing plt_got_offset.
512 This is only used for x86-64. */
513 unsigned int plt_got_insn_size;
514
515 /* Alignment of the .iplt section. */
516 unsigned int iplt_alignment;
517
518 /* .eh_frame covering the .plt section. */
519 const bfd_byte *eh_frame_plt;
520 unsigned int eh_frame_plt_size;
521 };
522
523 /* Values in tls_type of x86 ELF linker hash entry. */
524 #define GOT_UNKNOWN 0
525 #define GOT_NORMAL 1
526 #define GOT_TLS_GD 2
527 #define GOT_TLS_IE 4
528 #define GOT_TLS_IE_POS 5
529 #define GOT_TLS_IE_NEG 6
530 #define GOT_TLS_IE_BOTH 7
531 #define GOT_TLS_GDESC 8
532 #define GOT_ABS 9
533 #define GOT_TLS_GD_BOTH_P(type) \
534 ((type) == (GOT_TLS_GD | GOT_TLS_GDESC))
535 #define GOT_TLS_GD_P(type) \
536 ((type) == GOT_TLS_GD || GOT_TLS_GD_BOTH_P (type))
537 #define GOT_TLS_GDESC_P(type) \
538 ((type) == GOT_TLS_GDESC || GOT_TLS_GD_BOTH_P (type))
539 #define GOT_TLS_GD_ANY_P(type) \
540 (GOT_TLS_GD_P (type) || GOT_TLS_GDESC_P (type))
541
542 #define elf_x86_hash_entry(ent) \
543 ((struct elf_x86_link_hash_entry *)(ent))
544
545 /* Information of an input relocation used to compute its contribution
546 to the DT_RELR section size. */
547
548 struct elf_x86_relative_reloc_record
549 {
550 /* The original relocation info. */
551 Elf_Internal_Rela rel;
552 /* The input or the GOT section where the relocation is applied. */
553 asection *sec;
554 /* Local symbol info. NULL for global symbol. */
555 Elf_Internal_Sym *sym;
556 union
557 {
558 /* Section where the local symbol is defined. */
559 asection *sym_sec;
560 /* Global symbol hash. */
561 struct elf_link_hash_entry *h;
562 } u;
563 /* The offset into the output section where the relative relocation
564 will be applied at run-time. */
565 bfd_vma offset;
566 /* The run-time address. */
567 bfd_vma address;
568 };
569
570 struct elf_x86_relative_reloc_data
571 {
572 bfd_size_type count;
573 bfd_size_type size;
574 struct elf_x86_relative_reloc_record *data;
575 };
576
577 /* DT_RELR bitmap. */
578 struct elf_dt_relr_bitmap
579 {
580 bfd_size_type count;
581 bfd_size_type size;
582 union
583 {
584 /* 32-bit bitmap. */
585 uint32_t *elf32;
586 /* 64-bit bitmap. */
587 uint64_t *elf64;
588 } u;
589 };
590
591 /* x86 ELF linker hash table. */
592
593 struct elf_x86_link_hash_table
594 {
595 struct elf_link_hash_table elf;
596
597 /* Short-cuts to get to dynamic linker sections. */
598 asection *interp;
599 asection *plt_eh_frame;
600 asection *plt_second;
601 asection *plt_second_eh_frame;
602 asection *plt_got;
603 asection *plt_got_eh_frame;
604
605 sframe_encoder_ctx *plt_cfe_ctx;
606 asection *plt_sframe;
607 sframe_encoder_ctx *plt_second_cfe_ctx;
608 asection *plt_second_sframe;
609
610 /* Parameters describing PLT generation, lazy or non-lazy. */
611 struct elf_x86_plt_layout plt;
612
613 /* Parameters describing lazy PLT generation. */
614 const struct elf_x86_lazy_plt_layout *lazy_plt;
615
616 /* Parameters describing non-lazy PLT generation. */
617 const struct elf_x86_non_lazy_plt_layout *non_lazy_plt;
618
619 /* The .sframe helper object for .plt section.
620 This is used for x86-64 only. */
621 const struct elf_x86_sframe_plt *sframe_plt;
622
623 union
624 {
625 bfd_signed_vma refcount;
626 bfd_vma offset;
627 } tls_ld_or_ldm_got;
628
629 /* The amount of space used by the jump slots in the GOT. */
630 bfd_vma sgotplt_jump_table_size;
631
632 /* _TLS_MODULE_BASE_ symbol. */
633 struct bfd_link_hash_entry *tls_module_base;
634
635 /* Used by local STT_GNU_IFUNC symbols. */
636 htab_t loc_hash_table;
637 void * loc_hash_memory;
638
639 /* The index of the next R_X86_64_JUMP_SLOT entry in .rela.plt. */
640 bfd_vma next_jump_slot_index;
641 /* The index of the next R_X86_64_IRELATIVE entry in .rela.plt. */
642 bfd_vma next_irelative_index;
643
644 /* The (unloaded but important) .rel.plt.unloaded section on VxWorks.
645 This is used for i386 only. */
646 asection *srelplt2;
647
648 /* The index of the next unused R_386_TLS_DESC slot in .rel.plt. This
649 is only used for i386. */
650 bfd_vma next_tls_desc_index;
651
652 /* DT_RELR bitmap. */
653 struct elf_dt_relr_bitmap dt_relr_bitmap;
654
655 /* Relative relocation data. */
656 struct elf_x86_relative_reloc_data relative_reloc;
657
658 /* Unaligned relative relocation data. */
659 struct elf_x86_relative_reloc_data unaligned_relative_reloc;
660
661 /* Number of relative reloc generation pass. */
662 unsigned int generate_relative_reloc_pass;
663
664 /* Value used to fill the unused bytes of the first PLT entry. This
665 is only used for i386. */
666 bfd_byte plt0_pad_byte;
667
668 /* TRUE if GOT is referenced. */
669 unsigned int got_referenced : 1;
670
671 /* TRUE if PLT is PC-relative. PLT in PDE and PC-relative PLT in PIE
672 can be used as function address.
673
674 NB: i386 has non-PIC PLT and PIC PLT. Only non-PIC PLT in PDE can
675 be used as function address. PIC PLT in PIE can't be used as
676 function address. */
677 unsigned int pcrel_plt : 1;
678
679 bfd_vma (*r_info) (bfd_vma, bfd_vma);
680 bfd_vma (*r_sym) (bfd_vma);
681 bool (*is_reloc_section) (const char *);
682 unsigned int sizeof_reloc;
683 unsigned int got_entry_size;
684 unsigned int pointer_r_type;
685 unsigned int relative_r_type;
686 int dynamic_interpreter_size;
687 const char *dynamic_interpreter;
688 const char *tls_get_addr;
689 const char *relative_r_name;
690 void (*elf_append_reloc) (bfd *, asection *, Elf_Internal_Rela *);
691 void (*elf_write_addend) (bfd *, uint64_t, void *);
692 void (*elf_write_addend_in_got) (bfd *, uint64_t, void *);
693
694 /* Options passed from the linker. */
695 struct elf_linker_x86_params *params;
696 };
697
698 struct elf_x86_init_table
699 {
700 /* The lazy PLT layout. */
701 const struct elf_x86_lazy_plt_layout *lazy_plt;
702
703 /* The non-lazy PLT layout. */
704 const struct elf_x86_non_lazy_plt_layout *non_lazy_plt;
705
706 /* The lazy PLT layout for IBT. */
707 const struct elf_x86_lazy_plt_layout *lazy_ibt_plt;
708
709 /* The non-lazy PLT layout for IBT. */
710 const struct elf_x86_non_lazy_plt_layout *non_lazy_ibt_plt;
711
712 /* The .sframe helper object for lazy .plt section.
713 This is used for x86-64 only. */
714 const struct elf_x86_sframe_plt *sframe_lazy_plt;
715
716 /* The .sframe helper object for non-lazy .plt section.
717 This is used for x86-64 only. */
718 const struct elf_x86_sframe_plt *sframe_non_lazy_plt;
719
720 /* The .sframe helper object for lazy IBT .plt section.
721 This is used for x86-64 only. */
722 const struct elf_x86_sframe_plt *sframe_lazy_ibt_plt;
723
724 /* The .sframe helper object for non-lazy IBT .plt section.
725 This is used for x86-64 only. */
726 const struct elf_x86_sframe_plt *sframe_non_lazy_ibt_plt;
727
728 bfd_byte plt0_pad_byte;
729
730 bfd_vma (*r_info) (bfd_vma, bfd_vma);
731 bfd_vma (*r_sym) (bfd_vma);
732 };
733
734 struct elf_x86_obj_tdata
735 {
736 struct elf_obj_tdata root;
737
738 /* tls_type for each local got entry. */
739 char *local_got_tls_type;
740
741 /* GOTPLT entries for TLS descriptors. */
742 bfd_vma *local_tlsdesc_gotent;
743
744 /* R_*_RELATIVE relocation in GOT for this local symbol has been
745 processed. */
746 char *relative_reloc_done;
747 };
748
749 enum elf_x86_plt_type
750 {
751 plt_non_lazy = 0,
752 plt_lazy = 1 << 0,
753 plt_pic = 1 << 1,
754 plt_second = 1 << 2,
755 plt_unknown = -1
756 };
757
758 struct elf_x86_plt
759 {
760 const char *name;
761 asection *sec;
762 bfd_byte *contents;
763 enum elf_x86_plt_type type;
764 unsigned int plt_got_offset;
765 unsigned int plt_entry_size;
766 unsigned int plt_got_insn_size; /* Only used for x86-64. */
767 long count;
768 };
769
770 /* Set if a relocation is converted from a GOTPCREL relocation. */
771 #define R_X86_64_converted_reloc_bit (1 << 7)
772
773 #define elf_x86_tdata(abfd) \
774 ((struct elf_x86_obj_tdata *) (abfd)->tdata.any)
775
776 #define elf_x86_local_got_tls_type(abfd) \
777 (elf_x86_tdata (abfd)->local_got_tls_type)
778
779 #define elf_x86_local_tlsdesc_gotent(abfd) \
780 (elf_x86_tdata (abfd)->local_tlsdesc_gotent)
781
782 #define elf_x86_relative_reloc_done(abfd) \
783 (elf_x86_tdata (abfd)->relative_reloc_done)
784
785 #define elf_x86_compute_jump_table_size(htab) \
786 ((htab)->elf.srelplt->reloc_count * (htab)->got_entry_size)
787
788 #define is_x86_elf(bfd, htab) \
789 (bfd_get_flavour (bfd) == bfd_target_elf_flavour \
790 && elf_tdata (bfd) != NULL \
791 && elf_object_id (bfd) == (htab)->elf.hash_table_id)
792
793 /* Rename some of the generic section flags to better document how they
794 are used here. */
795 #define check_relocs_failed sec_flg0
796 #define relative_reloc_packed sec_flg1
797
798 extern bool _bfd_x86_elf_mkobject
799 (bfd *);
800
801 extern void _bfd_x86_elf_set_tls_module_base
802 (struct bfd_link_info *);
803
804 extern bfd_vma _bfd_x86_elf_dtpoff_base
805 (struct bfd_link_info *);
806
807 extern bool _bfd_x86_elf_readonly_dynrelocs
808 (struct elf_link_hash_entry *, void *);
809
810 extern struct elf_link_hash_entry * _bfd_elf_x86_get_local_sym_hash
811 (struct elf_x86_link_hash_table *, bfd *, const Elf_Internal_Rela *,
812 bool);
813
814 extern hashval_t _bfd_x86_elf_local_htab_hash
815 (const void *);
816
817 extern int _bfd_x86_elf_local_htab_eq
818 (const void *, const void *);
819
820 extern struct bfd_hash_entry * _bfd_x86_elf_link_hash_newfunc
821 (struct bfd_hash_entry *, struct bfd_hash_table *, const char *);
822
823 extern struct bfd_link_hash_table * _bfd_x86_elf_link_hash_table_create
824 (bfd *);
825
826 extern int _bfd_x86_elf_compare_relocs
827 (const void *, const void *);
828
829 extern bool _bfd_x86_elf_link_check_relocs
830 (bfd *, struct bfd_link_info *);
831
832 extern bool _bfd_x86_elf_check_relocs
833 (bfd *, struct bfd_link_info *, asection *,
834 const Elf_Internal_Rela *);
835
836 extern bool _bfd_x86_elf_link_relax_section
837 (bfd *, asection *, struct bfd_link_info *, bool *);
838
839 extern bool _bfd_elf_x86_size_relative_relocs
840 (struct bfd_link_info *, bool *);
841
842 extern bool _bfd_elf_x86_finish_relative_relocs
843 (struct bfd_link_info *);
844
845 extern void _bfd_elf32_write_addend (bfd *, uint64_t, void *);
846 extern void _bfd_elf64_write_addend (bfd *, uint64_t, void *);
847
848 extern bool _bfd_elf_x86_valid_reloc_p
849 (asection *, struct bfd_link_info *, struct elf_x86_link_hash_table *,
850 const Elf_Internal_Rela *, struct elf_link_hash_entry *,
851 Elf_Internal_Sym *, Elf_Internal_Shdr *, bool *);
852
853 extern bool _bfd_x86_elf_size_dynamic_sections
854 (bfd *, struct bfd_link_info *);
855
856 extern struct elf_x86_link_hash_table *_bfd_x86_elf_finish_dynamic_sections
857 (bfd *, struct bfd_link_info *);
858
859 extern bool _bfd_x86_elf_always_size_sections
860 (bfd *, struct bfd_link_info *);
861
862 extern void _bfd_x86_elf_merge_symbol_attribute
863 (struct elf_link_hash_entry *, unsigned int, bool, bool);
864
865 extern void _bfd_x86_elf_copy_indirect_symbol
866 (struct bfd_link_info *, struct elf_link_hash_entry *,
867 struct elf_link_hash_entry *);
868
869 extern bool _bfd_x86_elf_fixup_symbol
870 (struct bfd_link_info *, struct elf_link_hash_entry *);
871
872 extern bool _bfd_x86_elf_hash_symbol
873 (struct elf_link_hash_entry *);
874
875 extern bool _bfd_x86_elf_adjust_dynamic_symbol
876 (struct bfd_link_info *, struct elf_link_hash_entry *);
877
878 extern void _bfd_x86_elf_hide_symbol
879 (struct bfd_link_info *, struct elf_link_hash_entry *, bool);
880
881 extern bool _bfd_x86_elf_link_symbol_references_local
882 (struct bfd_link_info *, struct elf_link_hash_entry *);
883
884 extern asection * _bfd_x86_elf_gc_mark_hook
885 (asection *, struct bfd_link_info *, Elf_Internal_Rela *,
886 struct elf_link_hash_entry *, Elf_Internal_Sym *);
887
888 extern long _bfd_x86_elf_get_synthetic_symtab
889 (bfd *, long, long, bfd_vma, struct elf_x86_plt [], asymbol **,
890 asymbol **);
891
892 extern enum elf_property_kind _bfd_x86_elf_parse_gnu_properties
893 (bfd *, unsigned int, bfd_byte *, unsigned int);
894
895 extern bool _bfd_x86_elf_merge_gnu_properties
896 (struct bfd_link_info *, bfd *, bfd *, elf_property *, elf_property *);
897
898 extern void _bfd_x86_elf_link_fixup_gnu_properties
899 (struct bfd_link_info *, elf_property_list **);
900
901 extern bfd * _bfd_x86_elf_link_setup_gnu_properties
902 (struct bfd_link_info *, struct elf_x86_init_table *);
903
904 extern void _bfd_x86_elf_link_fixup_ifunc_symbol
905 (struct bfd_link_info *, struct elf_x86_link_hash_table *,
906 struct elf_link_hash_entry *, Elf_Internal_Sym *sym);
907
908 extern void _bfd_x86_elf_link_report_relative_reloc
909 (struct bfd_link_info *, asection *, struct elf_link_hash_entry *,
910 Elf_Internal_Sym *, const char *, const void *);
911
912 #define bfd_elf64_mkobject \
913 _bfd_x86_elf_mkobject
914 #define bfd_elf32_mkobject \
915 _bfd_x86_elf_mkobject
916 #define bfd_elf64_bfd_link_hash_table_create \
917 _bfd_x86_elf_link_hash_table_create
918 #define bfd_elf32_bfd_link_hash_table_create \
919 _bfd_x86_elf_link_hash_table_create
920 #define bfd_elf64_bfd_link_check_relocs \
921 _bfd_x86_elf_link_check_relocs
922 #define bfd_elf32_bfd_link_check_relocs \
923 _bfd_x86_elf_link_check_relocs
924 #define bfd_elf32_bfd_relax_section \
925 _bfd_x86_elf_link_relax_section
926 #define bfd_elf64_bfd_relax_section \
927 _bfd_x86_elf_link_relax_section
928
929 #define elf_backend_check_relocs \
930 _bfd_x86_elf_check_relocs
931 #define elf_backend_size_dynamic_sections \
932 _bfd_x86_elf_size_dynamic_sections
933 #define elf_backend_merge_symbol_attribute \
934 _bfd_x86_elf_merge_symbol_attribute
935 #define elf_backend_copy_indirect_symbol \
936 _bfd_x86_elf_copy_indirect_symbol
937 #define elf_backend_fixup_symbol \
938 _bfd_x86_elf_fixup_symbol
939 #define elf_backend_hash_symbol \
940 _bfd_x86_elf_hash_symbol
941 #define elf_backend_adjust_dynamic_symbol \
942 _bfd_x86_elf_adjust_dynamic_symbol
943 #define elf_backend_gc_mark_hook \
944 _bfd_x86_elf_gc_mark_hook
945 #define elf_backend_omit_section_dynsym \
946 _bfd_elf_omit_section_dynsym_all
947 #define elf_backend_parse_gnu_properties \
948 _bfd_x86_elf_parse_gnu_properties
949 #define elf_backend_merge_gnu_properties \
950 _bfd_x86_elf_merge_gnu_properties
951 #define elf_backend_fixup_gnu_properties \
952 _bfd_x86_elf_link_fixup_gnu_properties
953 #define elf_backend_size_relative_relocs \
954 _bfd_elf_x86_size_relative_relocs
955 #define elf_backend_finish_relative_relocs \
956 _bfd_elf_x86_finish_relative_relocs
957
958 #define ELF_P_ALIGN ELF_MINPAGESIZE
959
960 /* Allocate x86 GOT info for local symbols. */
961
962 static inline bool
elf_x86_allocate_local_got_info(bfd * abfd,bfd_size_type count)963 elf_x86_allocate_local_got_info (bfd *abfd, bfd_size_type count)
964 {
965 bfd_signed_vma *local_got_refcounts = elf_local_got_refcounts (abfd);
966 if (local_got_refcounts == NULL)
967 {
968 bfd_size_type size = count * (sizeof (bfd_signed_vma)
969 + sizeof (bfd_vma)
970 + 2 * sizeof(char));
971 local_got_refcounts = (bfd_signed_vma *) bfd_zalloc (abfd, size);
972 if (local_got_refcounts == NULL)
973 return false;
974 elf_local_got_refcounts (abfd) = local_got_refcounts;
975 elf_x86_local_tlsdesc_gotent (abfd) =
976 (bfd_vma *) (local_got_refcounts + count);
977 elf_x86_local_got_tls_type (abfd) =
978 (char *) (local_got_refcounts + 2 * count);
979 elf_x86_relative_reloc_done (abfd) =
980 ((char *) (local_got_refcounts + 2 * count)) + count;
981 }
982 return true;
983 }
984