binutils (2.41)
1 /* bfdlink.h -- header file for BFD link routines
2 Copyright (C) 1993-2023 Free Software Foundation, Inc.
3 Written by Steve Chamberlain and Ian Lance Taylor, Cygnus Support.
4
5 This file is part of BFD, the Binary File Descriptor library.
6
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
11
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, write to the Free Software
19 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
20 MA 02110-1301, USA. */
21
22 #ifndef BFDLINK_H
23 #define BFDLINK_H
24
25 /* Which symbols to strip during a link. */
26 enum bfd_link_strip
27 {
28 strip_none, /* Don't strip any symbols. */
29 strip_debugger, /* Strip debugging symbols. */
30 strip_some, /* keep_hash is the list of symbols to keep. */
31 strip_all /* Strip all symbols. */
32 };
33
34 /* Which local symbols to discard during a link. This is irrelevant
35 if strip_all is used. */
36 enum bfd_link_discard
37 {
38 discard_sec_merge, /* Discard local temporary symbols in SEC_MERGE
39 sections. */
40 discard_none, /* Don't discard any locals. */
41 discard_l, /* Discard local temporary symbols. */
42 discard_all /* Discard all locals. */
43 };
44
45 enum notice_asneeded_action {
46 notice_as_needed,
47 notice_not_needed,
48 notice_needed
49 };
50
51 /* Whether to generate ELF common symbols with the STT_COMMON type
52 during a relocatable link. */
53 enum bfd_link_elf_stt_common
54 {
55 unchanged,
56 elf_stt_common,
57 no_elf_stt_common
58 };
59
60 /* Describes the type of hash table entry structure being used.
61 Different hash table structure have different fields and so
62 support different linking features. */
63 enum bfd_link_hash_table_type
64 {
65 bfd_link_generic_hash_table,
66 bfd_link_elf_hash_table
67 };
68
69 /* These are the possible types of an entry in the BFD link hash
70 table. */
71
72 enum bfd_link_hash_type
73 {
74 bfd_link_hash_new, /* Symbol is new. */
75 bfd_link_hash_undefined, /* Symbol seen before, but undefined. */
76 bfd_link_hash_undefweak, /* Symbol is weak and undefined. */
77 bfd_link_hash_defined, /* Symbol is defined. */
78 bfd_link_hash_defweak, /* Symbol is weak and defined. */
79 bfd_link_hash_common, /* Symbol is common. */
80 bfd_link_hash_indirect, /* Symbol is an indirect link. */
81 bfd_link_hash_warning /* Like indirect, but warn if referenced. */
82 };
83
84 enum bfd_link_common_skip_ar_symbols
85 {
86 bfd_link_common_skip_none,
87 bfd_link_common_skip_text,
88 bfd_link_common_skip_data,
89 bfd_link_common_skip_all
90 };
91
92 struct bfd_link_hash_common_entry
93 {
94 unsigned int alignment_power; /* Alignment. */
95 asection *section; /* Symbol section. */
96 };
97
98 /* The linking routines use a hash table which uses this structure for
99 its elements. */
100
101 struct bfd_link_hash_entry
102 {
103 /* Base hash table entry structure. */
104 struct bfd_hash_entry root;
105
106 /* Type of this entry. */
107 ENUM_BITFIELD (bfd_link_hash_type) type : 8;
108
109 /* Symbol is referenced in a normal regular object file,
110 as distinct from a LTO IR object file. */
111 unsigned int non_ir_ref_regular : 1;
112
113 /* Symbol is referenced in a normal dynamic object file,
114 as distinct from a LTO IR object file. */
115 unsigned int non_ir_ref_dynamic : 1;
116
117 /* The symbol, SYM, is referenced by __real_SYM in an object file. */
118 unsigned int ref_real : 1;
119
120 /* Symbol is a built-in define. These will be overridden by PROVIDE
121 in a linker script. */
122 unsigned int linker_def : 1;
123
124 /* Symbol defined in a linker script. */
125 unsigned int ldscript_def : 1;
126
127 /* Symbol will be converted from absolute to section-relative. Set for
128 symbols defined by a script from "dot" (also SEGMENT_START or ORIGIN)
129 outside of an output section statement. */
130 unsigned int rel_from_abs : 1;
131
132 /* A union of information depending upon the type. */
133 union
134 {
135 /* Nothing is kept for bfd_hash_new. */
136 /* bfd_link_hash_undefined, bfd_link_hash_undefweak. */
137 struct
138 {
139 /* Undefined and common symbols are kept in a linked list through
140 this field. This field is present in all of the union element
141 so that we don't need to remove entries from the list when we
142 change their type. Removing entries would either require the
143 list to be doubly linked, which would waste more memory, or
144 require a traversal. When an undefined or common symbol is
145 created, it should be added to this list, the head of which is in
146 the link hash table itself. As symbols are defined, they need
147 not be removed from the list; anything which reads the list must
148 doublecheck the symbol type.
149
150 Weak symbols are not kept on this list.
151
152 Defined and defweak symbols use this field as a reference marker.
153 If the field is not NULL, or this structure is the tail of the
154 undefined symbol list, the symbol has been referenced. If the
155 symbol is undefined and becomes defined, this field will
156 automatically be non-NULL since the symbol will have been on the
157 undefined symbol list. */
158 struct bfd_link_hash_entry *next;
159 /* BFD symbol was found in. */
160 bfd *abfd;
161 } undef;
162 /* bfd_link_hash_defined, bfd_link_hash_defweak. */
163 struct
164 {
165 struct bfd_link_hash_entry *next;
166 /* Symbol section. */
167 asection *section;
168 /* Symbol value. */
169 bfd_vma value;
170 } def;
171 /* bfd_link_hash_indirect, bfd_link_hash_warning. */
172 struct
173 {
174 struct bfd_link_hash_entry *next;
175 /* Real symbol. */
176 struct bfd_link_hash_entry *link;
177 /* Warning message (bfd_link_hash_warning only). */
178 const char *warning;
179 } i;
180 /* bfd_link_hash_common. */
181 struct
182 {
183 struct bfd_link_hash_entry *next;
184 /* The linker needs to know three things about common
185 symbols: the size, the alignment, and the section in
186 which the symbol should be placed. We store the size
187 here, and we allocate a small structure to hold the
188 section and the alignment. The alignment is stored as a
189 power of two. We don't store all the information
190 directly because we don't want to increase the size of
191 the union; this structure is a major space user in the
192 linker. */
193 struct bfd_link_hash_common_entry *p;
194 /* Common symbol size. */
195 bfd_size_type size;
196 } c;
197 } u;
198 };
199
200 /* This is the link hash table. It is a derived class of
201 bfd_hash_table. */
202
203 struct bfd_link_hash_table
204 {
205 /* The hash table itself. */
206 struct bfd_hash_table table;
207 /* A linked list of undefined and common symbols, linked through the
208 next field in the bfd_link_hash_entry structure. */
209 struct bfd_link_hash_entry *undefs;
210 /* Entries are added to the tail of the undefs list. */
211 struct bfd_link_hash_entry *undefs_tail;
212 /* Function to free the hash table on closing BFD. */
213 void (*hash_table_free) (bfd *);
214 /* The type of the link hash table. */
215 enum bfd_link_hash_table_type type;
216 };
217
218 /* Look up an entry in a link hash table. If FOLLOW is TRUE, this
219 follows bfd_link_hash_indirect and bfd_link_hash_warning links to
220 the real symbol. */
221 extern struct bfd_link_hash_entry *bfd_link_hash_lookup
222 (struct bfd_link_hash_table *, const char *, bool create,
223 bool copy, bool follow);
224
225 /* Look up an entry in the main linker hash table if the symbol might
226 be wrapped. This should only be used for references to an
227 undefined symbol, not for definitions of a symbol. */
228
229 extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup
230 (bfd *, struct bfd_link_info *, const char *, bool, bool, bool);
231
232 /* If H is a wrapped symbol, ie. the symbol name starts with "__wrap_"
233 and the remainder is found in wrap_hash, return the real symbol. */
234
235 extern struct bfd_link_hash_entry *unwrap_hash_lookup
236 (struct bfd_link_info *, bfd *, struct bfd_link_hash_entry *);
237
238 /* Traverse a link hash table. */
239 extern void bfd_link_hash_traverse
240 (struct bfd_link_hash_table *,
241 bool (*) (struct bfd_link_hash_entry *, void *),
242 void *);
243
244 /* Add an entry to the undefs list. */
245 extern void bfd_link_add_undef
246 (struct bfd_link_hash_table *, struct bfd_link_hash_entry *);
247
248 /* Remove symbols from the undefs list that don't belong there. */
249 extern void bfd_link_repair_undef_list
250 (struct bfd_link_hash_table *table);
251
252 /* Read symbols and cache symbol pointer array in outsymbols. */
253 extern bool bfd_generic_link_read_symbols (bfd *);
254
255 /* Check the relocs in the BFD. Called after all the input
256 files have been loaded, and garbage collection has tagged
257 any unneeded sections. */
258 extern bool bfd_link_check_relocs (bfd *,struct bfd_link_info *);
259
260 struct bfd_sym_chain
261 {
262 struct bfd_sym_chain *next;
263 const char *name;
264 };
265
266 /* How to handle unresolved symbols.
267 There are four possibilities which are enumerated below: */
268 enum report_method
269 {
270 /* This is the initial value when then link_info structure is created.
271 It allows the various stages of the linker to determine whether they
272 allowed to set the value. */
273 RM_NOT_YET_SET = 0,
274 RM_IGNORE,
275 RM_DIAGNOSE,
276 };
277
278 /* How to handle DT_TEXTREL. */
279
280 enum textrel_check_method
281 {
282 textrel_check_none,
283 textrel_check_warning,
284 textrel_check_error
285 };
286
287 #define bfd_link_textrel_check(info) \
288 (info->textrel_check != textrel_check_none)
289
290 typedef enum {with_flags, without_flags} flag_type;
291
292 /* A section flag list. */
293 struct flag_info_list
294 {
295 flag_type with;
296 const char *name;
297 bool valid;
298 struct flag_info_list *next;
299 };
300
301 /* Section flag info. */
302 struct flag_info
303 {
304 flagword only_with_flags;
305 flagword not_with_flags;
306 struct flag_info_list *flag_list;
307 bool flags_initialized;
308 };
309
310 struct bfd_elf_dynamic_list;
311 struct bfd_elf_version_tree;
312
313 /* Types of output. */
314
315 enum output_type
316 {
317 type_pde,
318 type_pie,
319 type_relocatable,
320 type_dll,
321 };
322
323 #define bfd_link_pde(info) ((info)->type == type_pde)
324 #define bfd_link_dll(info) ((info)->type == type_dll)
325 #define bfd_link_relocatable(info) ((info)->type == type_relocatable)
326 #define bfd_link_pie(info) ((info)->type == type_pie)
327 #define bfd_link_executable(info) (bfd_link_pde (info) || bfd_link_pie (info))
328 #define bfd_link_pic(info) (bfd_link_dll (info) || bfd_link_pie (info))
329
330 /* This structure holds all the information needed to communicate
331 between BFD and the linker when doing a link. */
332
333 struct bfd_link_info
334 {
335 /* Output type. */
336 ENUM_BITFIELD (output_type) type : 2;
337
338 /* TRUE if BFD should pre-bind symbols in a shared object. */
339 unsigned int symbolic: 1;
340
341 /* TRUE if BFD should export all symbols in the dynamic symbol table
342 of an executable, rather than only those used. */
343 unsigned int export_dynamic: 1;
344
345 /* TRUE if a default symbol version should be created and used for
346 exported symbols. */
347 unsigned int create_default_symver: 1;
348
349 /* TRUE if unreferenced sections should be removed. */
350 unsigned int gc_sections: 1;
351
352 /* TRUE if exported symbols should be kept during section gc. */
353 unsigned int gc_keep_exported: 1;
354
355 /* TRUE if every symbol should be reported back via the notice
356 callback. */
357 unsigned int notice_all: 1;
358
359 /* TRUE if the LTO plugin is active. */
360 unsigned int lto_plugin_active: 1;
361
362 /* TRUE if all LTO IR symbols have been read. */
363 unsigned int lto_all_symbols_read : 1;
364
365 /* TRUE if global symbols in discarded sections should be stripped. */
366 unsigned int strip_discarded: 1;
367
368 /* TRUE if all data symbols should be dynamic. */
369 unsigned int dynamic_data: 1;
370
371 /* TRUE if section groups should be resolved. */
372 unsigned int resolve_section_groups: 1;
373
374 /* Set if output file is big-endian, or if that is unknown, from
375 the command line or first input file endianness. */
376 unsigned int big_endian : 1;
377
378 /* Which symbols to strip. */
379 ENUM_BITFIELD (bfd_link_strip) strip : 2;
380
381 /* Which local symbols to discard. */
382 ENUM_BITFIELD (bfd_link_discard) discard : 2;
383
384 /* Whether to generate ELF common symbols with the STT_COMMON type. */
385 ENUM_BITFIELD (bfd_link_elf_stt_common) elf_stt_common : 2;
386
387 /* Criteria for skipping symbols when determining
388 whether to include an object from an archive. */
389 ENUM_BITFIELD (bfd_link_common_skip_ar_symbols) common_skip_ar_symbols : 2;
390
391 /* What to do with unresolved symbols in an object file.
392 When producing executables the default is GENERATE_ERROR.
393 When producing shared libraries the default is IGNORE. The
394 assumption with shared libraries is that the reference will be
395 resolved at load/execution time. */
396 ENUM_BITFIELD (report_method) unresolved_syms_in_objects : 2;
397
398 /* What to do with unresolved symbols in a shared library.
399 The same defaults apply. */
400 ENUM_BITFIELD (report_method) unresolved_syms_in_shared_libs : 2;
401
402 /* TRUE if unresolved symbols are to be warned, rather than errored. */
403 unsigned int warn_unresolved_syms: 1;
404
405 /* TRUE if shared objects should be linked directly, not shared. */
406 unsigned int static_link: 1;
407
408 /* TRUE if symbols should be retained in memory, FALSE if they
409 should be freed and reread. */
410 unsigned int keep_memory: 1;
411
412 /* TRUE if BFD should generate relocation information in the final
413 executable. */
414 unsigned int emitrelocations: 1;
415
416 /* TRUE if PT_GNU_RELRO segment should be created. */
417 unsigned int relro: 1;
418
419 /* TRUE if DT_RELR should be enabled for compact relative
420 relocations. */
421 unsigned int enable_dt_relr: 1;
422
423 /* TRUE if separate code segment should be created. */
424 unsigned int separate_code: 1;
425
426 /* Nonzero if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
427 should be created. 1 for DWARF2 tables, 2 for compact tables. */
428 unsigned int eh_frame_hdr_type: 2;
429
430 /* What to do with DT_TEXTREL in output. */
431 ENUM_BITFIELD (textrel_check_method) textrel_check: 2;
432
433 /* TRUE if .hash section should be created. */
434 unsigned int emit_hash: 1;
435
436 /* TRUE if .gnu.hash section should be created. */
437 unsigned int emit_gnu_hash: 1;
438
439 /* If TRUE reduce memory overheads, at the expense of speed. This will
440 cause map file generation to use an O(N^2) algorithm and disable
441 caching ELF symbol buffer. */
442 unsigned int reduce_memory_overheads: 1;
443
444 /* TRUE if the output file should be in a traditional format. This
445 is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
446 on the output file, but may be checked when reading the input
447 files. */
448 unsigned int traditional_format: 1;
449
450 /* TRUE if non-PLT relocs should be merged into one reloc section
451 and sorted so that relocs against the same symbol come together. */
452 unsigned int combreloc: 1;
453
454 /* TRUE if a default symbol version should be created and used for
455 imported symbols. */
456 unsigned int default_imported_symver: 1;
457
458 /* TRUE if the new ELF dynamic tags are enabled. */
459 unsigned int new_dtags: 1;
460
461 /* FALSE if .eh_frame unwind info should be generated for PLT and other
462 linker created sections, TRUE if it should be omitted. */
463 unsigned int no_ld_generated_unwind_info: 1;
464
465 /* TRUE if BFD should generate a "task linked" object file,
466 similar to relocatable but also with globals converted to
467 statics. */
468 unsigned int task_link: 1;
469
470 /* TRUE if ok to have multiple definitions, without warning. */
471 unsigned int allow_multiple_definition: 1;
472
473 /* TRUE if multiple definition of absolute symbols (eg. from -R) should
474 be reported. */
475 unsigned int prohibit_multiple_definition_absolute: 1;
476
477 /* TRUE if multiple definitions should only warn. */
478 unsigned int warn_multiple_definition: 1;
479
480 /* TRUE if ok to have version with no definition. */
481 unsigned int allow_undefined_version: 1;
482
483 /* TRUE if some symbols have to be dynamic, controlled by
484 --dynamic-list command line options. */
485 unsigned int dynamic: 1;
486
487 /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X
488 flags. */
489 unsigned int execstack: 1;
490
491 /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W
492 flags. */
493 unsigned int noexecstack: 1;
494
495 /* Tri-state variable:
496 0 => do not warn when creating an executable stack.
497 1 => always warn when creating an executable stack.
498 >1 => warn when creating an executable stack if execstack is 0. */
499 unsigned int warn_execstack: 2;
500
501 /* TRUE if warnings should not be generated for TLS segments with eXecute
502 permission or LOAD segments with RWX permissions. */
503 unsigned int no_warn_rwx_segments: 1;
504 /* TRUE if the user gave either --warn-rwx-segments or
505 --no-warn-rwx-segments. */
506 unsigned int user_warn_rwx_segments: 1;
507
508 /* TRUE if the stack can be made executable because of the absence of a
509 .note.GNU-stack section in an input file. Note - even if this field
510 is set, some targets may choose to ignore the setting and not create
511 an executable stack. */
512 unsigned int default_execstack : 1;
513
514 /* TRUE if we want to produced optimized output files. This might
515 need much more time and therefore must be explicitly selected. */
516 unsigned int optimize: 1;
517
518 /* TRUE if user should be informed of removed unreferenced sections. */
519 unsigned int print_gc_sections: 1;
520
521 /* TRUE if we should warn alternate ELF machine code. */
522 unsigned int warn_alternate_em: 1;
523
524 /* TRUE if the linker script contained an explicit PHDRS command. */
525 unsigned int user_phdrs: 1;
526
527 /* TRUE if program headers ought to be loaded. */
528 unsigned int load_phdrs: 1;
529
530 /* TRUE if we should check relocations after all input files have
531 been opened. */
532 unsigned int check_relocs_after_open_input: 1;
533
534 /* TRUE if generation of .interp/PT_INTERP should be suppressed. */
535 unsigned int nointerp: 1;
536
537 /* TRUE if common symbols should be treated as undefined. */
538 unsigned int inhibit_common_definition : 1;
539
540 /* TRUE if "-Map map" is passed to linker. */
541 unsigned int has_map_file : 1;
542
543 /* TRUE if "--enable-non-contiguous-regions" is passed to the
544 linker. */
545 unsigned int non_contiguous_regions : 1;
546
547 /* TRUE if "--enable-non-contiguous-regions-warnings" is passed to
548 the linker. */
549 unsigned int non_contiguous_regions_warnings : 1;
550
551 /* TRUE if all symbol names should be unique. */
552 unsigned int unique_symbol : 1;
553
554 /* TRUE if maxpagesize is set on command-line. */
555 unsigned int maxpagesize_is_set : 1;
556
557 /* TRUE if commonpagesize is set on command-line. */
558 unsigned int commonpagesize_is_set : 1;
559
560 /* Char that may appear as the first char of a symbol, but should be
561 skipped (like symbol_leading_char) when looking up symbols in
562 wrap_hash. Used by PowerPC Linux for 'dot' symbols. */
563 char wrap_char;
564
565 /* Separator between archive and filename in linker script filespecs. */
566 char path_separator;
567
568 /* Default stack size. Zero means default (often zero itself), -1
569 means explicitly zero-sized. */
570 bfd_signed_vma stacksize;
571
572 /* Enable or disable target specific optimizations.
573
574 Not all targets have optimizations to enable.
575
576 Normally these optimizations are disabled by default but some targets
577 prefer to enable them by default. So this field is a tri-state variable.
578 The values are:
579
580 zero: Enable the optimizations (either from --relax being specified on
581 the command line or the backend's before_allocation emulation function.
582
583 positive: The user has requested that these optimizations be disabled.
584 (Via the --no-relax command line option).
585
586 negative: The optimizations are disabled. (Set when initializing the
587 args_type structure in ldmain.c:main. */
588 signed int disable_target_specific_optimizations;
589
590 /* Function callbacks. */
591 const struct bfd_link_callbacks *callbacks;
592
593 /* Hash table handled by BFD. */
594 struct bfd_link_hash_table *hash;
595
596 /* Hash table of symbols to keep. This is NULL unless strip is
597 strip_some. */
598 struct bfd_hash_table *keep_hash;
599
600 /* Hash table of symbols to report back via the notice callback. If
601 this is NULL, and notice_all is FALSE, then no symbols are
602 reported back. */
603 struct bfd_hash_table *notice_hash;
604
605 /* Hash table of symbols which are being wrapped (the --wrap linker
606 option). If this is NULL, no symbols are being wrapped. */
607 struct bfd_hash_table *wrap_hash;
608
609 /* Hash table of symbols which may be left unresolved during
610 a link. If this is NULL, no symbols can be left unresolved. */
611 struct bfd_hash_table *ignore_hash;
612
613 /* The output BFD. */
614 bfd *output_bfd;
615
616 /* The import library generated. */
617 bfd *out_implib_bfd;
618
619 /* The list of input BFD's involved in the link. These are chained
620 together via the link.next field. */
621 bfd *input_bfds;
622 bfd **input_bfds_tail;
623
624 /* If a symbol should be created for each input BFD, this is section
625 where those symbols should be placed. It must be a section in
626 the output BFD. It may be NULL, in which case no such symbols
627 will be created. This is to support CREATE_OBJECT_SYMBOLS in the
628 linker command language. */
629 asection *create_object_symbols_section;
630
631 /* List of global symbol names that are starting points for marking
632 sections against garbage collection. */
633 struct bfd_sym_chain *gc_sym_list;
634
635 /* If a base output file is wanted, then this points to it */
636 void *base_file;
637
638 /* The function to call when the executable or shared object is
639 loaded. */
640 const char *init_function;
641
642 /* The function to call when the executable or shared object is
643 unloaded. */
644 const char *fini_function;
645
646 /* Number of relaxation passes. Usually only one relaxation pass
647 is needed. But a backend can have as many relaxation passes as
648 necessary. During bfd_relax_section call, it is set to the
649 current pass, starting from 0. */
650 int relax_pass;
651
652 /* Number of relaxation trips. This number is incremented every
653 time the relaxation pass is restarted due to a previous
654 relaxation returning true in *AGAIN. */
655 int relax_trip;
656
657 /* > 0 to treat protected data defined in the shared library as
658 reference external. 0 to treat it as internal. -1 to let
659 backend to decide. */
660 int extern_protected_data;
661
662 /* 1 to make undefined weak symbols dynamic when building a dynamic
663 object. 0 to resolve undefined weak symbols to zero. -1 to let
664 the backend decide. */
665 int dynamic_undefined_weak;
666
667 /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
668 should be generated/linked against. Set to 1 if this feature
669 is explicitly requested by the user, -1 if enabled by default. */
670 int pei386_auto_import;
671
672 /* Non-zero if runtime relocs for DATA items with non-zero addends
673 in pei386 DLLs should be generated. Set to 1 if this feature
674 is explicitly requested by the user, -1 if enabled by default. */
675 int pei386_runtime_pseudo_reloc;
676
677 /* How many spare .dynamic DT_NULL entries should be added? */
678 unsigned int spare_dynamic_tags;
679
680 /* GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS control:
681 > 1: Turn on by -z indirect-extern-access or by backend.
682 == 1: Turn on by an input.
683 0: Turn off.
684 < 0: Turn on if it is set on any inputs or let backend to
685 decide. */
686 int indirect_extern_access;
687
688 /* Non-zero if executable should not contain copy relocs.
689 > 1: Implied by indirect_extern_access.
690 == 1: Turn on by -z nocopyreloc.
691 0: Turn off.
692 Setting this to non-zero may result in a non-sharable text
693 segment. */
694 int nocopyreloc;
695
696 /* Pointer to the GNU_PROPERTY_1_NEEDED property in memory. */
697 bfd_byte *needed_1_p;
698
699 /* May be used to set DT_FLAGS for ELF. */
700 bfd_vma flags;
701
702 /* May be used to set DT_FLAGS_1 for ELF. */
703 bfd_vma flags_1;
704
705 /* May be used to set DT_GNU_FLAGS_1 for ELF. */
706 bfd_vma gnu_flags_1;
707
708 /* TRUE if references to __start_/__stop_ synthesized symbols do not
709 specially retain C identifier named sections. */
710 int start_stop_gc;
711
712 /* May be used to set ELF visibility for __start_* / __stop_. */
713 unsigned int start_stop_visibility;
714
715 /* The maximum page size for ELF. */
716 bfd_vma maxpagesize;
717
718 /* The common page size for ELF. */
719 bfd_vma commonpagesize;
720
721 /* Start and end of RELRO region. */
722 bfd_vma relro_start, relro_end;
723
724 /* List of symbols should be dynamic. */
725 struct bfd_elf_dynamic_list *dynamic_list;
726
727 /* The version information. */
728 struct bfd_elf_version_tree *version_info;
729
730 /* Size of cache. Backend can use it to keep strace cache size. */
731 bfd_size_type cache_size;
732
733 /* The maximum cache size. Backend can use cache_size and and
734 max_cache_size to decide if keep_memory should be honored. */
735 bfd_size_type max_cache_size;
736 };
737
738 /* Some forward-definitions used by some callbacks. */
739
740 struct elf_strtab_hash;
741 struct elf_internal_sym;
742
743 /* This structures holds a set of callback functions. These are called
744 by the BFD linker routines. */
745
746 struct bfd_link_callbacks
747 {
748 /* A function which is called when an object is added from an
749 archive. ABFD is the archive element being added. NAME is the
750 name of the symbol which caused the archive element to be pulled
751 in. This function may set *SUBSBFD to point to an alternative
752 BFD from which symbols should in fact be added in place of the
753 original BFD's symbols. Returns TRUE if the object should be
754 added, FALSE if it should be skipped. */
755 bool (*add_archive_element)
756 (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd);
757 /* A function which is called when a symbol is found with multiple
758 definitions. H is the symbol which is defined multiple times.
759 NBFD is the new BFD, NSEC is the new section, and NVAL is the new
760 value. NSEC may be bfd_com_section or bfd_ind_section. */
761 void (*multiple_definition)
762 (struct bfd_link_info *, struct bfd_link_hash_entry *h,
763 bfd *nbfd, asection *nsec, bfd_vma nval);
764 /* A function which is called when a common symbol is defined
765 multiple times. H is the symbol appearing multiple times.
766 NBFD is the BFD of the new symbol. NTYPE is the type of the new
767 symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
768 bfd_link_hash_indirect. If NTYPE is bfd_link_hash_common, NSIZE
769 is the size of the new symbol. */
770 void (*multiple_common)
771 (struct bfd_link_info *, struct bfd_link_hash_entry *h,
772 bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
773 /* A function which is called to add a symbol to a set. ENTRY is
774 the link hash table entry for the set itself (e.g.,
775 __CTOR_LIST__). RELOC is the relocation to use for an entry in
776 the set when generating a relocatable file, and is also used to
777 get the size of the entry when generating an executable file.
778 ABFD, SEC and VALUE identify the value to add to the set. */
779 void (*add_to_set)
780 (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
781 bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
782 /* A function which is called when the name of a g++ constructor or
783 destructor is found. This is only called by some object file
784 formats. CONSTRUCTOR is TRUE for a constructor, FALSE for a
785 destructor. This will use BFD_RELOC_CTOR when generating a
786 relocatable file. NAME is the name of the symbol found. ABFD,
787 SECTION and VALUE are the value of the symbol. */
788 void (*constructor)
789 (struct bfd_link_info *, bool constructor, const char *name,
790 bfd *abfd, asection *sec, bfd_vma value);
791 /* A function which is called to issue a linker warning. For
792 example, this is called when there is a reference to a warning
793 symbol. WARNING is the warning to be issued. SYMBOL is the name
794 of the symbol which triggered the warning; it may be NULL if
795 there is none. ABFD, SECTION and ADDRESS identify the location
796 which trigerred the warning; either ABFD or SECTION or both may
797 be NULL if the location is not known. */
798 void (*warning)
799 (struct bfd_link_info *, const char *warning, const char *symbol,
800 bfd *abfd, asection *section, bfd_vma address);
801 /* A function which is called when a relocation is attempted against
802 an undefined symbol. NAME is the symbol which is undefined.
803 ABFD, SECTION and ADDRESS identify the location from which the
804 reference is made. IS_FATAL indicates whether an undefined symbol is
805 a fatal error or not. In some cases SECTION may be NULL. */
806 void (*undefined_symbol)
807 (struct bfd_link_info *, const char *name, bfd *abfd,
808 asection *section, bfd_vma address, bool is_fatal);
809 /* A function which is called when a reloc overflow occurs. ENTRY is
810 the link hash table entry for the symbol the reloc is against.
811 NAME is the name of the local symbol or section the reloc is
812 against, RELOC_NAME is the name of the relocation, and ADDEND is
813 any addend that is used. ABFD, SECTION and ADDRESS identify the
814 location at which the overflow occurs; if this is the result of a
815 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
816 ABFD will be NULL. */
817 void (*reloc_overflow)
818 (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
819 const char *name, const char *reloc_name, bfd_vma addend,
820 bfd *abfd, asection *section, bfd_vma address);
821 /* A function which is called when a dangerous reloc is performed.
822 MESSAGE is an appropriate message.
823 ABFD, SECTION and ADDRESS identify the location at which the
824 problem occurred; if this is the result of a
825 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
826 ABFD will be NULL. */
827 void (*reloc_dangerous)
828 (struct bfd_link_info *, const char *message,
829 bfd *abfd, asection *section, bfd_vma address);
830 /* A function which is called when a reloc is found to be attached
831 to a symbol which is not being written out. NAME is the name of
832 the symbol. ABFD, SECTION and ADDRESS identify the location of
833 the reloc; if this is the result of a
834 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
835 ABFD will be NULL. */
836 void (*unattached_reloc)
837 (struct bfd_link_info *, const char *name,
838 bfd *abfd, asection *section, bfd_vma address);
839 /* A function which is called when a symbol in notice_hash is
840 defined or referenced. H is the symbol, INH the indirect symbol
841 if applicable. ABFD, SECTION and ADDRESS are the (new) value of
842 the symbol. If SECTION is bfd_und_section, this is a reference.
843 FLAGS are the symbol BSF_* flags. */
844 bool (*notice)
845 (struct bfd_link_info *, struct bfd_link_hash_entry *h,
846 struct bfd_link_hash_entry *inh,
847 bfd *abfd, asection *section, bfd_vma address, flagword flags);
848 /* Error or warning link info message. */
849 void (*einfo)
850 (const char *fmt, ...);
851 /* General link info message. */
852 void (*info)
853 (const char *fmt, ...);
854 /* Message to be printed in linker map file. */
855 void (*minfo)
856 (const char *fmt, ...);
857 /* This callback provides a chance for users of the BFD library to
858 override its decision about whether to place two adjacent sections
859 into the same segment. */
860 bool (*override_segment_assignment)
861 (struct bfd_link_info *, bfd * abfd,
862 asection * current_section, asection * previous_section,
863 bool new_segment);
864 /* This callback provides a chance for callers of the BFD to examine the
865 ELF (dynamic) string table once it is complete. */
866 void (*examine_strtab)
867 (struct elf_strtab_hash *symstrtab);
868 /* This callback is called just before a symbol is swapped out, so that the
869 CTF machinery can look up symbols during construction. The name is
870 already an external strtab offset at this point. */
871 void (*ctf_new_symbol)
872 (int symidx, struct elf_internal_sym *sym);
873 /* Likewise, for dynamic symbols. */
874 void (*ctf_new_dynsym)
875 (int symidx, struct elf_internal_sym *sym);
876 /* This callback should emit the CTF section into a non-loadable section in
877 the output BFD named .ctf or a name beginning with ".ctf.". */
878 void (*emit_ctf)
879 (void);
880 };
881
882 /* The linker builds link_order structures which tell the code how to
883 include input data in the output file. */
884
885 /* These are the types of link_order structures. */
886
887 enum bfd_link_order_type
888 {
889 bfd_undefined_link_order, /* Undefined. */
890 bfd_indirect_link_order, /* Built from a section. */
891 bfd_data_link_order, /* Set to explicit data. */
892 bfd_section_reloc_link_order, /* Relocate against a section. */
893 bfd_symbol_reloc_link_order /* Relocate against a symbol. */
894 };
895
896 /* This is the link_order structure itself. These form a chain
897 attached to the output section whose contents they are describing. */
898
899 struct bfd_link_order
900 {
901 /* Next link_order in chain. */
902 struct bfd_link_order *next;
903 /* Type of link_order. */
904 enum bfd_link_order_type type;
905 /* Offset within output section in bytes. */
906 bfd_vma offset;
907 /* Size within output section in octets. */
908 bfd_size_type size;
909 /* Type specific information. */
910 union
911 {
912 struct
913 {
914 /* Section to include. If this is used, then
915 section->output_section must be the section the
916 link_order is attached to, section->output_offset must
917 equal the link_order offset field, and section->size
918 must equal the link_order size field. Maybe these
919 restrictions should be relaxed someday. */
920 asection *section;
921 } indirect;
922 struct
923 {
924 /* Size of contents, or zero when contents should be filled by
925 the architecture-dependent fill function.
926 A non-zero value allows filling of the output section
927 with an arbitrary repeated pattern. */
928 unsigned int size;
929 /* Data to put into file. */
930 bfd_byte *contents;
931 } data;
932 struct
933 {
934 /* Description of reloc to generate. Used for
935 bfd_section_reloc_link_order and
936 bfd_symbol_reloc_link_order. */
937 struct bfd_link_order_reloc *p;
938 } reloc;
939 } u;
940 };
941
942 /* A linker order of type bfd_section_reloc_link_order or
943 bfd_symbol_reloc_link_order means to create a reloc against a
944 section or symbol, respectively. This is used to implement -Ur to
945 generate relocs for the constructor tables. The
946 bfd_link_order_reloc structure describes the reloc that BFD should
947 create. It is similar to a arelent, but I didn't use arelent
948 because the linker does not know anything about most symbols, and
949 any asymbol structure it creates will be partially meaningless.
950 This information could logically be in the bfd_link_order struct,
951 but I didn't want to waste the space since these types of relocs
952 are relatively rare. */
953
954 struct bfd_link_order_reloc
955 {
956 /* Reloc type. */
957 bfd_reloc_code_real_type reloc;
958
959 union
960 {
961 /* For type bfd_section_reloc_link_order, this is the section
962 the reloc should be against. This must be a section in the
963 output BFD, not any of the input BFDs. */
964 asection *section;
965 /* For type bfd_symbol_reloc_link_order, this is the name of the
966 symbol the reloc should be against. */
967 const char *name;
968 } u;
969
970 /* Addend to use. The object file should contain zero. The BFD
971 backend is responsible for filling in the contents of the object
972 file correctly. For some object file formats (e.g., COFF) the
973 addend must be stored into in the object file, and for some
974 (e.g., SPARC a.out) it is kept in the reloc. */
975 bfd_vma addend;
976 };
977
978 /* Allocate a new link_order for a section. */
979 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
980
981 struct bfd_section_already_linked;
982
983 extern bool bfd_section_already_linked_table_init (void);
984 extern void bfd_section_already_linked_table_free (void);
985 extern bool _bfd_handle_already_linked
986 (struct bfd_section *, struct bfd_section_already_linked *,
987 struct bfd_link_info *);
988
989 extern struct bfd_section *_bfd_nearby_section
990 (bfd *, struct bfd_section *, bfd_vma);
991
992 extern void _bfd_fix_excluded_sec_syms
993 (bfd *, struct bfd_link_info *);
994
995 /* These structures are used to describe version information for the
996 ELF linker. These structures could be manipulated entirely inside
997 BFD, but it would be a pain. Instead, the regular linker sets up
998 these structures, and then passes them into BFD. */
999
1000 /* Glob pattern for a version. */
1001
1002 struct bfd_elf_version_expr
1003 {
1004 /* Next glob pattern for this version. */
1005 struct bfd_elf_version_expr *next;
1006 /* Glob pattern. */
1007 const char *pattern;
1008 /* Set if pattern is not a glob. */
1009 unsigned int literal : 1;
1010 /* Defined by ".symver". */
1011 unsigned int symver : 1;
1012 /* Defined by version script. */
1013 unsigned int script : 1;
1014 /* Pattern type. */
1015 #define BFD_ELF_VERSION_C_TYPE 1
1016 #define BFD_ELF_VERSION_CXX_TYPE 2
1017 #define BFD_ELF_VERSION_JAVA_TYPE 4
1018 unsigned int mask : 3;
1019 };
1020
1021 struct bfd_elf_version_expr_head
1022 {
1023 /* List of all patterns, both wildcards and non-wildcards. */
1024 struct bfd_elf_version_expr *list;
1025 /* Hash table for non-wildcards. */
1026 void *htab;
1027 /* Remaining patterns. */
1028 struct bfd_elf_version_expr *remaining;
1029 /* What kind of pattern types are present in list (bitmask). */
1030 unsigned int mask;
1031 };
1032
1033 /* Version dependencies. */
1034
1035 struct bfd_elf_version_deps
1036 {
1037 /* Next dependency for this version. */
1038 struct bfd_elf_version_deps *next;
1039 /* The version which this version depends upon. */
1040 struct bfd_elf_version_tree *version_needed;
1041 };
1042
1043 /* A node in the version tree. */
1044
1045 struct bfd_elf_version_tree
1046 {
1047 /* Next version. */
1048 struct bfd_elf_version_tree *next;
1049 /* Name of this version. */
1050 const char *name;
1051 /* Version number. */
1052 unsigned int vernum;
1053 /* Regular expressions for global symbols in this version. */
1054 struct bfd_elf_version_expr_head globals;
1055 /* Regular expressions for local symbols in this version. */
1056 struct bfd_elf_version_expr_head locals;
1057 /* List of versions which this version depends upon. */
1058 struct bfd_elf_version_deps *deps;
1059 /* Index of the version name. This is used within BFD. */
1060 unsigned int name_indx;
1061 /* Whether this version tree was used. This is used within BFD. */
1062 int used;
1063 /* Matching hook. */
1064 struct bfd_elf_version_expr *(*match)
1065 (struct bfd_elf_version_expr_head *head,
1066 struct bfd_elf_version_expr *prev, const char *sym);
1067 };
1068
1069 struct bfd_elf_dynamic_list
1070 {
1071 struct bfd_elf_version_expr_head head;
1072 struct bfd_elf_version_expr *(*match)
1073 (struct bfd_elf_version_expr_head *head,
1074 struct bfd_elf_version_expr *prev, const char *sym);
1075 };
1076
1077 #endif
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