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1 /* bfdlink.h -- header file for BFD link routines
2 Copyright (C) 1993-2025 Free Software Foundation, Inc.
3 Written by Steve Chamberlain and Ian Lance Taylor, Cygnus Support.
5 This file is part of BFD, the Binary File Descriptor library.
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.
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.
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. */
22 #ifndef BFDLINK_H
23 #define BFDLINK_H
25 /* Which symbols to strip during a link. */
26 enum bfd_link_strip
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. */
34 /* Which local symbols to discard during a link. This is irrelevant
35 if strip_all is used. */
36 enum bfd_link_discard
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. */
45 enum notice_asneeded_action {
46 notice_as_needed,
47 notice_not_needed,
48 notice_needed
51 /* Whether to generate ELF common symbols with the STT_COMMON type
52 during a relocatable link. */
53 enum bfd_link_elf_stt_common
55 unchanged,
56 elf_stt_common,
57 no_elf_stt_common
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
65 bfd_link_generic_hash_table,
66 bfd_link_elf_hash_table
69 /* These are the possible types of an entry in the BFD link hash
70 table. */
72 enum bfd_link_hash_type
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. */
84 enum bfd_link_common_skip_ar_symbols
86 bfd_link_common_skip_none,
87 bfd_link_common_skip_text,
88 bfd_link_common_skip_data,
89 bfd_link_common_skip_all
92 struct bfd_link_hash_common_entry
94 unsigned int alignment_power; /* Alignment. */
95 asection *section; /* Symbol section. */
98 /* The linking routines use a hash table which uses this structure for
99 its elements. */
101 struct bfd_link_hash_entry
103 /* Base hash table entry structure. */
104 struct bfd_hash_entry root;
106 /* Type of this entry. */
107 ENUM_BITFIELD (bfd_link_hash_type) type : 8;
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;
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;
117 /* The symbol, SYM, is referenced by __real_SYM in an object file. */
118 unsigned int ref_real : 1;
120 /* The symbol is a wrapper symbol, __wrap_SYM. */
121 unsigned int wrapper_symbol : 1;
123 /* Symbol is a built-in define. These will be overridden by PROVIDE
124 in a linker script. */
125 unsigned int linker_def : 1;
127 /* Symbol defined in a linker script. */
128 unsigned int ldscript_def : 1;
130 /* Symbol will be converted from absolute to section-relative. Set for
131 symbols defined by a script from "dot" (also SEGMENT_START or ORIGIN)
132 outside of an output section statement. */
133 unsigned int rel_from_abs : 1;
135 /* A union of information depending upon the type. */
136 union
138 /* Nothing is kept for bfd_hash_new. */
139 /* bfd_link_hash_undefined, bfd_link_hash_undefweak. */
140 struct
142 /* Undefined and common symbols are kept in a linked list through
143 this field. This field is present in all of the union element
144 so that we don't need to remove entries from the list when we
145 change their type. Removing entries would either require the
146 list to be doubly linked, which would waste more memory, or
147 require a traversal. When an undefined or common symbol is
148 created, it should be added to this list, the head of which is in
149 the link hash table itself. As symbols are defined, they need
150 not be removed from the list; anything which reads the list must
151 doublecheck the symbol type.
153 Weak symbols are not kept on this list.
155 Defined and defweak symbols use this field as a reference marker.
156 If the field is not NULL, or this structure is the tail of the
157 undefined symbol list, the symbol has been referenced. If the
158 symbol is undefined and becomes defined, this field will
159 automatically be non-NULL since the symbol will have been on the
160 undefined symbol list. */
161 struct bfd_link_hash_entry *next;
162 /* BFD symbol was found in. */
163 bfd *abfd;
164 } undef;
165 /* bfd_link_hash_defined, bfd_link_hash_defweak. */
166 struct
168 struct bfd_link_hash_entry *next;
169 /* Symbol section. */
170 asection *section;
171 /* Symbol value. */
172 bfd_vma value;
173 } def;
174 /* bfd_link_hash_indirect, bfd_link_hash_warning. */
175 struct
177 struct bfd_link_hash_entry *next;
178 /* Real symbol. */
179 struct bfd_link_hash_entry *link;
180 /* Warning message (bfd_link_hash_warning only). */
181 const char *warning;
182 } i;
183 /* bfd_link_hash_common. */
184 struct
186 struct bfd_link_hash_entry *next;
187 /* The linker needs to know three things about common
188 symbols: the size, the alignment, and the section in
189 which the symbol should be placed. We store the size
190 here, and we allocate a small structure to hold the
191 section and the alignment. The alignment is stored as a
192 power of two. We don't store all the information
193 directly because we don't want to increase the size of
194 the union; this structure is a major space user in the
195 linker. */
196 struct bfd_link_hash_common_entry *p;
197 /* Common symbol size. */
198 bfd_size_type size;
199 } c;
200 } u;
203 /* This is the link hash table. It is a derived class of
204 bfd_hash_table. */
206 struct bfd_link_hash_table
208 /* The hash table itself. */
209 struct bfd_hash_table table;
210 /* A linked list of undefined and common symbols, linked through the
211 next field in the bfd_link_hash_entry structure. */
212 struct bfd_link_hash_entry *undefs;
213 /* Entries are added to the tail of the undefs list. */
214 struct bfd_link_hash_entry *undefs_tail;
215 /* Function to free the hash table on closing BFD. */
216 void (*hash_table_free) (bfd *);
217 /* The type of the link hash table. */
218 enum bfd_link_hash_table_type type;
221 /* Look up an entry in a link hash table. If FOLLOW is TRUE, this
222 follows bfd_link_hash_indirect and bfd_link_hash_warning links to
223 the real symbol. */
224 extern struct bfd_link_hash_entry *bfd_link_hash_lookup
225 (struct bfd_link_hash_table *, const char *, bool create,
226 bool copy, bool follow);
228 /* Look up an entry in the main linker hash table if the symbol might
229 be wrapped. This should only be used for references to an
230 undefined symbol, not for definitions of a symbol. */
232 extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup
233 (bfd *, struct bfd_link_info *, const char *, bool, bool, bool);
235 /* If H is a wrapped symbol, ie. the symbol name starts with "__wrap_"
236 and the remainder is found in wrap_hash, return the real symbol. */
238 extern struct bfd_link_hash_entry *unwrap_hash_lookup
239 (struct bfd_link_info *, bfd *, struct bfd_link_hash_entry *);
241 /* Traverse a link hash table. */
242 extern void bfd_link_hash_traverse
243 (struct bfd_link_hash_table *,
244 bool (*) (struct bfd_link_hash_entry *, void *),
245 void *);
247 /* Add an entry to the undefs list. */
248 extern void bfd_link_add_undef
249 (struct bfd_link_hash_table *, struct bfd_link_hash_entry *);
251 /* Remove symbols from the undefs list that don't belong there. */
252 extern void bfd_link_repair_undef_list
253 (struct bfd_link_hash_table *table);
255 /* Read symbols and cache symbol pointer array in outsymbols. */
256 extern bool bfd_generic_link_read_symbols (bfd *);
258 /* Check the relocs in the BFD. Called after all the input
259 files have been loaded, and garbage collection has tagged
260 any unneeded sections. */
261 extern bool bfd_link_check_relocs (bfd *,struct bfd_link_info *);
263 struct bfd_sym_chain
265 struct bfd_sym_chain *next;
266 const char *name;
269 /* How to handle unresolved symbols.
270 There are four possibilities which are enumerated below: */
271 enum report_method
273 /* This is the initial value when then link_info structure is created.
274 It allows the various stages of the linker to determine whether they
275 allowed to set the value. */
276 RM_NOT_YET_SET = 0,
277 RM_IGNORE,
278 RM_DIAGNOSE,
281 /* How to handle DT_TEXTREL. */
283 enum textrel_check_method
285 textrel_check_none,
286 textrel_check_warning,
287 textrel_check_error
290 #define bfd_link_textrel_check(info) \
291 (info->textrel_check != textrel_check_none)
293 typedef enum {with_flags, without_flags} flag_type;
295 /* A section flag list. */
296 struct flag_info_list
298 flag_type with;
299 const char *name;
300 bool valid;
301 struct flag_info_list *next;
304 /* Section flag info. */
305 struct flag_info
307 flagword only_with_flags;
308 flagword not_with_flags;
309 struct flag_info_list *flag_list;
310 bool flags_initialized;
313 struct bfd_elf_dynamic_list;
314 struct bfd_elf_version_tree;
316 /* Types of output. */
318 enum output_type
320 type_pde,
321 type_pie,
322 type_relocatable,
323 type_dll,
326 #define bfd_link_pde(info) ((info)->type == type_pde)
327 #define bfd_link_dll(info) ((info)->type == type_dll)
328 #define bfd_link_relocatable(info) ((info)->type == type_relocatable)
329 #define bfd_link_pie(info) ((info)->type == type_pie)
330 #define bfd_link_executable(info) (bfd_link_pde (info) || bfd_link_pie (info))
331 #define bfd_link_pic(info) (bfd_link_dll (info) || bfd_link_pie (info))
333 /* This structure holds all the information needed to communicate
334 between BFD and the linker when doing a link. */
336 struct bfd_link_info
338 /* Output type. */
339 ENUM_BITFIELD (output_type) type : 2;
341 /* TRUE if BFD should pre-bind symbols in a shared object. */
342 unsigned int symbolic: 1;
344 /* TRUE if BFD should export all symbols in the dynamic symbol table
345 of an executable, rather than only those used. */
346 unsigned int export_dynamic: 1;
348 /* TRUE if a default symbol version should be created and used for
349 exported symbols. */
350 unsigned int create_default_symver: 1;
352 /* TRUE if unreferenced sections should be removed. */
353 unsigned int gc_sections: 1;
355 /* TRUE if exported symbols should be kept during section gc. */
356 unsigned int gc_keep_exported: 1;
358 /* TRUE if every symbol should be reported back via the notice
359 callback. */
360 unsigned int notice_all: 1;
362 /* TRUE if the LTO plugin is active. */
363 unsigned int lto_plugin_active: 1;
365 /* TRUE if all LTO IR symbols have been read. */
366 unsigned int lto_all_symbols_read : 1;
368 /* TRUE if global symbols in discarded sections should be stripped. */
369 unsigned int strip_discarded: 1;
371 /* TRUE if all data symbols should be dynamic. */
372 unsigned int dynamic_data: 1;
374 /* TRUE if section groups should be resolved. */
375 unsigned int resolve_section_groups: 1;
377 /* Set if output file is big-endian, or if that is unknown, from
378 the command line or first input file endianness. */
379 unsigned int big_endian : 1;
381 /* Which symbols to strip. */
382 ENUM_BITFIELD (bfd_link_strip) strip : 2;
384 /* Which local symbols to discard. */
385 ENUM_BITFIELD (bfd_link_discard) discard : 2;
387 /* Whether to generate ELF common symbols with the STT_COMMON type. */
388 ENUM_BITFIELD (bfd_link_elf_stt_common) elf_stt_common : 2;
390 /* Criteria for skipping symbols when determining
391 whether to include an object from an archive. */
392 ENUM_BITFIELD (bfd_link_common_skip_ar_symbols) common_skip_ar_symbols : 2;
394 /* What to do with unresolved symbols in an object file.
395 When producing executables the default is GENERATE_ERROR.
396 When producing shared libraries the default is IGNORE. The
397 assumption with shared libraries is that the reference will be
398 resolved at load/execution time. */
399 ENUM_BITFIELD (report_method) unresolved_syms_in_objects : 2;
401 /* What to do with unresolved symbols in a shared library.
402 The same defaults apply. */
403 ENUM_BITFIELD (report_method) unresolved_syms_in_shared_libs : 2;
405 /* TRUE if unresolved symbols are to be warned, rather than errored. */
406 unsigned int warn_unresolved_syms: 1;
408 /* TRUE if shared objects should be linked directly, not shared. */
409 unsigned int static_link: 1;
411 /* TRUE if symbols should be retained in memory, FALSE if they
412 should be freed and reread. */
413 unsigned int keep_memory: 1;
415 /* TRUE if BFD should generate relocation information in the final
416 executable. */
417 unsigned int emitrelocations: 1;
419 /* TRUE if PT_GNU_RELRO segment should be created. */
420 unsigned int relro: 1;
422 /* TRUE if DT_RELR should be enabled for compact relative
423 relocations. */
424 unsigned int enable_dt_relr: 1;
426 /* TRUE if separate code segment should be created. */
427 unsigned int separate_code: 1;
429 /* TRUE if only one read-only, non-code segment should be created. */
430 unsigned int one_rosegment: 1;
432 /* TRUE if GNU_PROPERTY_MEMORY_SEAL should be generated. */
433 unsigned int memory_seal: 1;
435 /* Nonzero if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
436 should be created. 1 for DWARF2 tables, 2 for compact tables. */
437 unsigned int eh_frame_hdr_type: 2;
439 /* What to do with DT_TEXTREL in output. */
440 ENUM_BITFIELD (textrel_check_method) textrel_check: 2;
442 /* TRUE if .hash section should be created. */
443 unsigned int emit_hash: 1;
445 /* TRUE if .gnu.hash section should be created. */
446 unsigned int emit_gnu_hash: 1;
448 /* If TRUE reduce memory overheads, at the expense of speed. This will
449 cause map file generation to use an O(N^2) algorithm and disable
450 caching ELF symbol buffer. */
451 unsigned int reduce_memory_overheads: 1;
453 /* TRUE if the output file should be in a traditional format. This
454 is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
455 on the output file, but may be checked when reading the input
456 files. */
457 unsigned int traditional_format: 1;
459 /* TRUE if non-PLT relocs should be merged into one reloc section
460 and sorted so that relocs against the same symbol come together. */
461 unsigned int combreloc: 1;
463 /* TRUE if a default symbol version should be created and used for
464 imported symbols. */
465 unsigned int default_imported_symver: 1;
467 /* TRUE if the new ELF dynamic tags are enabled. */
468 unsigned int new_dtags: 1;
470 /* FALSE if .eh_frame unwind info should be generated for PLT and other
471 linker created sections, TRUE if it should be omitted. */
472 unsigned int no_ld_generated_unwind_info: 1;
474 /* TRUE if BFD should generate a "task linked" object file,
475 similar to relocatable but also with globals converted to
476 statics. */
477 unsigned int task_link: 1;
479 /* TRUE if ok to have multiple definitions, without warning. */
480 unsigned int allow_multiple_definition: 1;
482 /* TRUE if multiple definition of absolute symbols (eg. from -R) should
483 be reported. */
484 unsigned int prohibit_multiple_definition_absolute: 1;
486 /* TRUE if multiple definitions should only warn. */
487 unsigned int warn_multiple_definition: 1;
489 /* TRUE if ok to have version with no definition. */
490 unsigned int allow_undefined_version: 1;
492 /* TRUE if some symbols have to be dynamic, controlled by
493 --dynamic-list command line options. */
494 unsigned int dynamic: 1;
496 /* Set if the "-z execstack" option has been used to request that a
497 PT_GNU_STACK segment should be created with PF_R, PF_W and PF_X
498 flags set.
500 Note - if performing a relocatable link then a .note.GNU-stack
501 section will be created instead, if one does not exist already.
502 The section will have the SHF_EXECINSTR flag bit set. */
503 unsigned int execstack: 1;
505 /* Set if the "-z noexecstack" option has been used to request that a
506 PT_GNU_STACK segment should be created with PF_R and PF_W flags. Or
507 a non-executable .note.GNU-stack section for relocateable links.
509 Note - this flag is not quite orthogonal to execstack, since both
510 of these flags can be 0. In this case a stack segment can still
511 be created, but it will only have the PF_X flag bit set if one or
512 more of the input files contains a .note.GNU-stack section with the
513 SHF_EXECINSTR flag bit set, or if the default behaviour for the
514 architecture is to create executable stacks.
516 The execstack and noexecstack flags should never both be 1. */
517 unsigned int noexecstack: 1;
519 /* Tri-state variable:
520 0 => do not warn when creating an executable stack.
521 1 => always warn when creating an executable stack (for any reason).
522 2 => only warn when an executable stack has been requested an object
523 file and execstack is 0 or noexecstack is 1.
524 3 => not used. */
525 unsigned int warn_execstack: 2;
526 /* TRUE if a warning generated because of warn_execstack should be instead
527 be treated as an error. */
528 unsigned int error_execstack: 1;
530 /* TRUE if warnings should NOT be generated for TLS segments with eXecute
531 permission or LOAD segments with RWX permissions. */
532 unsigned int no_warn_rwx_segments: 1;
533 /* TRUE if the user gave either --warn-rwx-segments or
534 --no-warn-rwx-segments on the linker command line. */
535 unsigned int user_warn_rwx_segments: 1;
536 /* TRUE if warnings generated when no_warn_rwx_segements is 0 should
537 instead be treated as errors. */
538 unsigned int warn_is_error_for_rwx_segments: 1;
540 /* TRUE if the stack can be made executable because of the absence of a
541 .note.GNU-stack section in an input file. Note - even if this field
542 is set, some targets may choose to ignore the setting and not create
543 an executable stack. */
544 unsigned int default_execstack : 1;
546 /* TRUE if we want to produced optimized output files. This might
547 need much more time and therefore must be explicitly selected. */
548 unsigned int optimize: 1;
550 /* TRUE if user should be informed of removed unreferenced sections. */
551 unsigned int print_gc_sections: 1;
553 /* TRUE if we should warn alternate ELF machine code. */
554 unsigned int warn_alternate_em: 1;
556 /* TRUE if the linker script contained an explicit PHDRS command. */
557 unsigned int user_phdrs: 1;
559 /* TRUE if program headers ought to be loaded. */
560 unsigned int load_phdrs: 1;
562 /* TRUE if we should check relocations after all input files have
563 been opened. */
564 unsigned int check_relocs_after_open_input: 1;
566 /* TRUE if generation of .interp/PT_INTERP should be suppressed. */
567 unsigned int nointerp: 1;
569 /* TRUE if common symbols should be treated as undefined. */
570 unsigned int inhibit_common_definition : 1;
572 /* TRUE if "-Map map" is passed to linker. */
573 unsigned int has_map_file : 1;
575 /* TRUE if "--enable-non-contiguous-regions" is passed to the
576 linker. */
577 unsigned int non_contiguous_regions : 1;
579 /* TRUE if "--enable-non-contiguous-regions-warnings" is passed to
580 the linker. */
581 unsigned int non_contiguous_regions_warnings : 1;
583 /* TRUE if all symbol names should be unique. */
584 unsigned int unique_symbol : 1;
586 /* TRUE if maxpagesize is set on command-line. */
587 unsigned int maxpagesize_is_set : 1;
589 /* TRUE if commonpagesize is set on command-line. */
590 unsigned int commonpagesize_is_set : 1;
592 /* Char that may appear as the first char of a symbol, but should be
593 skipped (like symbol_leading_char) when looking up symbols in
594 wrap_hash. Used by PowerPC Linux for 'dot' symbols. */
595 char wrap_char;
597 /* Separator between archive and filename in linker script filespecs. */
598 char path_separator;
600 /* Default stack size. Zero means default (often zero itself), -1
601 means explicitly zero-sized. */
602 bfd_signed_vma stacksize;
604 /* Enable or disable target specific optimizations.
606 Not all targets have optimizations to enable.
608 Normally these optimizations are disabled by default but some targets
609 prefer to enable them by default. So this field is a tri-state variable.
610 The values are:
612 zero: Enable the optimizations (either from --relax being specified on
613 the command line or the backend's before_allocation emulation function.
615 positive: The user has requested that these optimizations be disabled.
616 (Via the --no-relax command line option).
618 negative: The optimizations are disabled. (Set when initializing the
619 args_type structure in ldmain.c:main. */
620 signed int disable_target_specific_optimizations;
622 /* Function callbacks. */
623 const struct bfd_link_callbacks *callbacks;
625 /* Hash table handled by BFD. */
626 struct bfd_link_hash_table *hash;
628 /* Hash table of symbols to keep. This is NULL unless strip is
629 strip_some. */
630 struct bfd_hash_table *keep_hash;
632 /* Hash table of symbols to report back via the notice callback. If
633 this is NULL, and notice_all is FALSE, then no symbols are
634 reported back. */
635 struct bfd_hash_table *notice_hash;
637 /* Hash table of symbols which are being wrapped (the --wrap linker
638 option). If this is NULL, no symbols are being wrapped. */
639 struct bfd_hash_table *wrap_hash;
641 /* Hash table of symbols which may be left unresolved during
642 a link. If this is NULL, no symbols can be left unresolved. */
643 struct bfd_hash_table *ignore_hash;
645 /* The output BFD. */
646 bfd *output_bfd;
648 /* The import library generated. */
649 bfd *out_implib_bfd;
651 /* The list of input BFD's involved in the link. These are chained
652 together via the link.next field. */
653 bfd *input_bfds;
654 bfd **input_bfds_tail;
656 /* If a symbol should be created for each input BFD, this is section
657 where those symbols should be placed. It must be a section in
658 the output BFD. It may be NULL, in which case no such symbols
659 will be created. This is to support CREATE_OBJECT_SYMBOLS in the
660 linker command language. */
661 asection *create_object_symbols_section;
663 /* List of global symbol names that are starting points for marking
664 sections against garbage collection. */
665 struct bfd_sym_chain *gc_sym_list;
667 /* If a base output file is wanted, then this points to it */
668 void *base_file;
670 /* The function to call when the executable or shared object is
671 loaded. */
672 const char *init_function;
674 /* The function to call when the executable or shared object is
675 unloaded. */
676 const char *fini_function;
678 /* Number of relaxation passes. Usually only one relaxation pass
679 is needed. But a backend can have as many relaxation passes as
680 necessary. During bfd_relax_section call, it is set to the
681 current pass, starting from 0. */
682 int relax_pass;
684 /* Number of relaxation trips. This number is incremented every
685 time the relaxation pass is restarted due to a previous
686 relaxation returning true in *AGAIN. */
687 int relax_trip;
689 /* > 0 to treat protected data defined in the shared library as
690 reference external. 0 to treat it as internal. -1 to let
691 backend to decide. */
692 int extern_protected_data;
694 /* 1 to make undefined weak symbols dynamic when building a dynamic
695 object. 0 to resolve undefined weak symbols to zero. -1 to let
696 the backend decide. */
697 int dynamic_undefined_weak;
699 /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
700 should be generated/linked against. Set to 1 if this feature
701 is explicitly requested by the user, -1 if enabled by default. */
702 int pei386_auto_import;
704 /* Non-zero if runtime relocs for DATA items with non-zero addends
705 in pei386 DLLs should be generated. Set to 1 if this feature
706 is explicitly requested by the user, -1 if enabled by default. */
707 int pei386_runtime_pseudo_reloc;
709 /* How many spare .dynamic DT_NULL entries should be added? */
710 unsigned int spare_dynamic_tags;
712 /* GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS control:
713 > 1: Turn on by -z indirect-extern-access or by backend.
714 == 1: Turn on by an input.
715 0: Turn off.
716 < 0: Turn on if it is set on any inputs or let backend to
717 decide. */
718 int indirect_extern_access;
720 /* Non-zero if executable should not contain copy relocs.
721 > 1: Implied by indirect_extern_access.
722 == 1: Turn on by -z nocopyreloc.
723 0: Turn off.
724 Setting this to non-zero may result in a non-sharable text
725 segment. */
726 int nocopyreloc;
728 /* Pointer to the GNU_PROPERTY_1_NEEDED property in memory. */
729 bfd_byte *needed_1_p;
731 /* May be used to set DT_FLAGS for ELF. */
732 bfd_vma flags;
734 /* May be used to set DT_FLAGS_1 for ELF. */
735 bfd_vma flags_1;
737 /* May be used to set DT_GNU_FLAGS_1 for ELF. */
738 bfd_vma gnu_flags_1;
740 /* TRUE if references to __start_/__stop_ synthesized symbols do not
741 specially retain C identifier named sections. */
742 int start_stop_gc;
744 /* May be used to set ELF visibility for __start_* / __stop_. */
745 unsigned int start_stop_visibility;
747 /* The maximum page size for ELF. */
748 bfd_vma maxpagesize;
750 /* The common page size for ELF. */
751 bfd_vma commonpagesize;
753 /* Start and end of RELRO region. */
754 bfd_vma relro_start, relro_end;
756 /* List of symbols should be dynamic. */
757 struct bfd_elf_dynamic_list *dynamic_list;
759 /* The version information. */
760 struct bfd_elf_version_tree *version_info;
762 /* Size of cache. Backend can use it to keep strace cache size. */
763 bfd_size_type cache_size;
765 /* The maximum cache size. Backend can use cache_size and and
766 max_cache_size to decide if keep_memory should be honored. */
767 bfd_size_type max_cache_size;
770 /* Some forward-definitions used by some callbacks. */
772 struct elf_strtab_hash;
773 struct elf_internal_sym;
775 /* This structures holds a set of callback functions. These are called
776 by the BFD linker routines. */
778 struct bfd_link_callbacks
780 /* A function which is called when an object is added from an
781 archive. ABFD is the archive element being added. NAME is the
782 name of the symbol which caused the archive element to be pulled
783 in. This function may set *SUBSBFD to point to an alternative
784 BFD from which symbols should in fact be added in place of the
785 original BFD's symbols. Returns TRUE if the object should be
786 added, FALSE if it should be skipped. */
787 bool (*add_archive_element)
788 (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd);
789 /* A function which is called when a symbol is found with multiple
790 definitions. H is the symbol which is defined multiple times.
791 NBFD is the new BFD, NSEC is the new section, and NVAL is the new
792 value. NSEC may be bfd_com_section or bfd_ind_section. */
793 void (*multiple_definition)
794 (struct bfd_link_info *, struct bfd_link_hash_entry *h,
795 bfd *nbfd, asection *nsec, bfd_vma nval);
796 /* A function which is called when a common symbol is defined
797 multiple times. H is the symbol appearing multiple times.
798 NBFD is the BFD of the new symbol. NTYPE is the type of the new
799 symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
800 bfd_link_hash_indirect. If NTYPE is bfd_link_hash_common, NSIZE
801 is the size of the new symbol. */
802 void (*multiple_common)
803 (struct bfd_link_info *, struct bfd_link_hash_entry *h,
804 bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
805 /* A function which is called to add a symbol to a set. ENTRY is
806 the link hash table entry for the set itself (e.g.,
807 __CTOR_LIST__). RELOC is the relocation to use for an entry in
808 the set when generating a relocatable file, and is also used to
809 get the size of the entry when generating an executable file.
810 ABFD, SEC and VALUE identify the value to add to the set. */
811 void (*add_to_set)
812 (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
813 bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
814 /* A function which is called when the name of a g++ constructor or
815 destructor is found. This is only called by some object file
816 formats. CONSTRUCTOR is TRUE for a constructor, FALSE for a
817 destructor. This will use BFD_RELOC_CTOR when generating a
818 relocatable file. NAME is the name of the symbol found. ABFD,
819 SECTION and VALUE are the value of the symbol. */
820 void (*constructor)
821 (struct bfd_link_info *, bool constructor, const char *name,
822 bfd *abfd, asection *sec, bfd_vma value);
823 /* A function which is called to issue a linker warning. For
824 example, this is called when there is a reference to a warning
825 symbol. WARNING is the warning to be issued. SYMBOL is the name
826 of the symbol which triggered the warning; it may be NULL if
827 there is none. ABFD, SECTION and ADDRESS identify the location
828 which trigerred the warning; either ABFD or SECTION or both may
829 be NULL if the location is not known. */
830 void (*warning)
831 (struct bfd_link_info *, const char *warning, const char *symbol,
832 bfd *abfd, asection *section, bfd_vma address);
833 /* A function which is called when a relocation is attempted against
834 an undefined symbol. NAME is the symbol which is undefined.
835 ABFD, SECTION and ADDRESS identify the location from which the
836 reference is made. IS_FATAL indicates whether an undefined symbol is
837 a fatal error or not. In some cases SECTION may be NULL. */
838 void (*undefined_symbol)
839 (struct bfd_link_info *, const char *name, bfd *abfd,
840 asection *section, bfd_vma address, bool is_fatal);
841 /* A function which is called when a reloc overflow occurs. ENTRY is
842 the link hash table entry for the symbol the reloc is against.
843 NAME is the name of the local symbol or section the reloc is
844 against, RELOC_NAME is the name of the relocation, and ADDEND is
845 any addend that is used. ABFD, SECTION and ADDRESS identify the
846 location at which the overflow occurs; if this is the result of a
847 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
848 ABFD will be NULL. */
849 void (*reloc_overflow)
850 (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
851 const char *name, const char *reloc_name, bfd_vma addend,
852 bfd *abfd, asection *section, bfd_vma address);
853 /* A function which is called when a dangerous reloc is performed.
854 MESSAGE is an appropriate message.
855 ABFD, SECTION and ADDRESS identify the location at which the
856 problem occurred; if this is the result of a
857 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
858 ABFD will be NULL. */
859 void (*reloc_dangerous)
860 (struct bfd_link_info *, const char *message,
861 bfd *abfd, asection *section, bfd_vma address);
862 /* A function which is called when a reloc is found to be attached
863 to a symbol which is not being written out. NAME is the name of
864 the symbol. ABFD, SECTION and ADDRESS identify the location of
865 the reloc; if this is the result of a
866 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
867 ABFD will be NULL. */
868 void (*unattached_reloc)
869 (struct bfd_link_info *, const char *name,
870 bfd *abfd, asection *section, bfd_vma address);
871 /* A function which is called when a symbol in notice_hash is
872 defined or referenced. H is the symbol, INH the indirect symbol
873 if applicable. ABFD, SECTION and ADDRESS are the (new) value of
874 the symbol. If SECTION is bfd_und_section, this is a reference.
875 FLAGS are the symbol BSF_* flags. */
876 bool (*notice)
877 (struct bfd_link_info *, struct bfd_link_hash_entry *h,
878 struct bfd_link_hash_entry *inh,
879 bfd *abfd, asection *section, bfd_vma address, flagword flags);
880 /* Error or warning link info message. */
881 void (*einfo)
882 (const char *fmt, ...);
883 /* General link info message. */
884 void (*info)
885 (const char *fmt, ...);
886 /* Message to be printed in linker map file. */
887 void (*minfo)
888 (const char *fmt, ...);
889 /* This callback provides a chance for users of the BFD library to
890 override its decision about whether to place two adjacent sections
891 into the same segment. */
892 bool (*override_segment_assignment)
893 (struct bfd_link_info *, bfd * abfd,
894 asection * current_section, asection * previous_section,
895 bool new_segment);
896 /* This callback provides a chance for callers of the BFD to examine the
897 ELF (dynamic) string table once it is complete. */
898 void (*examine_strtab)
899 (struct elf_strtab_hash *symstrtab);
900 /* This callback is called just before a symbol is swapped out, so that the
901 CTF machinery can look up symbols during construction. The name is
902 already an external strtab offset at this point. */
903 void (*ctf_new_symbol)
904 (int symidx, struct elf_internal_sym *sym);
905 /* Likewise, for dynamic symbols. */
906 void (*ctf_new_dynsym)
907 (int symidx, struct elf_internal_sym *sym);
908 /* This callback should emit the CTF section into a non-loadable section in
909 the output BFD named .ctf or a name beginning with ".ctf.". */
910 void (*emit_ctf)
911 (void);
914 /* The linker builds link_order structures which tell the code how to
915 include input data in the output file. */
917 /* These are the types of link_order structures. */
919 enum bfd_link_order_type
921 bfd_undefined_link_order, /* Undefined. */
922 bfd_indirect_link_order, /* Built from a section. */
923 bfd_data_link_order, /* Set to explicit data. */
924 bfd_section_reloc_link_order, /* Relocate against a section. */
925 bfd_symbol_reloc_link_order /* Relocate against a symbol. */
928 /* This is the link_order structure itself. These form a chain
929 attached to the output section whose contents they are describing. */
931 struct bfd_link_order
933 /* Next link_order in chain. */
934 struct bfd_link_order *next;
935 /* Type of link_order. */
936 enum bfd_link_order_type type;
937 /* Offset within output section in bytes. */
938 bfd_vma offset;
939 /* Size within output section in octets. */
940 bfd_size_type size;
941 /* Type specific information. */
942 union
944 struct
946 /* Section to include. If this is used, then
947 section->output_section must be the section the
948 link_order is attached to, section->output_offset must
949 equal the link_order offset field, and section->size
950 must equal the link_order size field. Maybe these
951 restrictions should be relaxed someday. */
952 asection *section;
953 } indirect;
954 struct
956 /* Size of contents, or zero when contents should be filled by
957 the architecture-dependent fill function.
958 A non-zero value allows filling of the output section
959 with an arbitrary repeated pattern. */
960 unsigned int size;
961 /* Data to put into file. */
962 bfd_byte *contents;
963 } data;
964 struct
966 /* Description of reloc to generate. Used for
967 bfd_section_reloc_link_order and
968 bfd_symbol_reloc_link_order. */
969 struct bfd_link_order_reloc *p;
970 } reloc;
971 } u;
974 /* A linker order of type bfd_section_reloc_link_order or
975 bfd_symbol_reloc_link_order means to create a reloc against a
976 section or symbol, respectively. This is used to implement -Ur to
977 generate relocs for the constructor tables. The
978 bfd_link_order_reloc structure describes the reloc that BFD should
979 create. It is similar to a arelent, but I didn't use arelent
980 because the linker does not know anything about most symbols, and
981 any asymbol structure it creates will be partially meaningless.
982 This information could logically be in the bfd_link_order struct,
983 but I didn't want to waste the space since these types of relocs
984 are relatively rare. */
986 struct bfd_link_order_reloc
988 /* Reloc type. */
989 bfd_reloc_code_real_type reloc;
991 union
993 /* For type bfd_section_reloc_link_order, this is the section
994 the reloc should be against. This must be a section in the
995 output BFD, not any of the input BFDs. */
996 asection *section;
997 /* For type bfd_symbol_reloc_link_order, this is the name of the
998 symbol the reloc should be against. */
999 const char *name;
1000 } u;
1002 /* Addend to use. The object file should contain zero. The BFD
1003 backend is responsible for filling in the contents of the object
1004 file correctly. For some object file formats (e.g., COFF) the
1005 addend must be stored into in the object file, and for some
1006 (e.g., SPARC a.out) it is kept in the reloc. */
1007 bfd_vma addend;
1010 /* Allocate a new link_order for a section. */
1011 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
1013 struct bfd_section_already_linked;
1015 extern bool bfd_section_already_linked_table_init (void);
1016 extern void bfd_section_already_linked_table_free (void);
1017 extern bool _bfd_handle_already_linked
1018 (struct bfd_section *, struct bfd_section_already_linked *,
1019 struct bfd_link_info *);
1021 extern struct bfd_section *_bfd_nearby_section
1022 (bfd *, struct bfd_section *, bfd_vma);
1024 extern void _bfd_fix_excluded_sec_syms
1025 (bfd *, struct bfd_link_info *);
1027 /* These structures are used to describe version information for the
1028 ELF linker. These structures could be manipulated entirely inside
1029 BFD, but it would be a pain. Instead, the regular linker sets up
1030 these structures, and then passes them into BFD. */
1032 /* Glob pattern for a version. */
1034 struct bfd_elf_version_expr
1036 /* Next glob pattern for this version. */
1037 struct bfd_elf_version_expr *next;
1038 /* Glob pattern. */
1039 const char *pattern;
1040 /* Set if pattern is not a glob. */
1041 unsigned int literal : 1;
1042 /* Defined by ".symver". */
1043 unsigned int symver : 1;
1044 /* Defined by version script. */
1045 unsigned int script : 1;
1046 /* Pattern type. */
1047 #define BFD_ELF_VERSION_C_TYPE 1
1048 #define BFD_ELF_VERSION_CXX_TYPE 2
1049 #define BFD_ELF_VERSION_JAVA_TYPE 4
1050 unsigned int mask : 3;
1053 struct bfd_elf_version_expr_head
1055 /* List of all patterns, both wildcards and non-wildcards. */
1056 struct bfd_elf_version_expr *list;
1057 /* Hash table for non-wildcards. */
1058 void *htab;
1059 /* Remaining patterns. */
1060 struct bfd_elf_version_expr *remaining;
1061 /* What kind of pattern types are present in list (bitmask). */
1062 unsigned int mask;
1065 /* Version dependencies. */
1067 struct bfd_elf_version_deps
1069 /* Next dependency for this version. */
1070 struct bfd_elf_version_deps *next;
1071 /* The version which this version depends upon. */
1072 struct bfd_elf_version_tree *version_needed;
1075 /* A node in the version tree. */
1077 struct bfd_elf_version_tree
1079 /* Next version. */
1080 struct bfd_elf_version_tree *next;
1081 /* Name of this version. */
1082 const char *name;
1083 /* Version number. */
1084 unsigned int vernum;
1085 /* Regular expressions for global symbols in this version. */
1086 struct bfd_elf_version_expr_head globals;
1087 /* Regular expressions for local symbols in this version. */
1088 struct bfd_elf_version_expr_head locals;
1089 /* List of versions which this version depends upon. */
1090 struct bfd_elf_version_deps *deps;
1091 /* Index of the version name. This is used within BFD. */
1092 unsigned int name_indx;
1093 /* Whether this version tree was used. This is used within BFD. */
1094 int used;
1095 /* Matching hook. */
1096 struct bfd_elf_version_expr *(*match)
1097 (struct bfd_elf_version_expr_head *head,
1098 struct bfd_elf_version_expr *prev, const char *sym);
1101 struct bfd_elf_dynamic_list
1103 struct bfd_elf_version_expr_head head;
1104 struct bfd_elf_version_expr *(*match)
1105 (struct bfd_elf_version_expr_head *head,
1106 struct bfd_elf_version_expr *prev, const char *sym);
1109 #endif