1 /* bfdlink.h -- header file for BFD link routines
2 Copyright 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2002
3 Free Software Foundation, Inc.
4 Written by Steve Chamberlain and Ian Lance Taylor, Cygnus Support.
6 This file is part of BFD, the Binary File Descriptor library.
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or
11 (at your option) any later version.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with this program; if not, write to the Free Software
20 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
25 /* Which symbols to strip during a link. */
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. */
38 discard_sec_merge
, /* Discard local temporary symbols in SEC_MERGE
40 discard_none
, /* Don't discard any locals. */
41 discard_l
, /* Discard local temporary symbols. */
42 discard_all
/* Discard all locals. */
45 /* Describes the type of hash table entry structure being used.
46 Different hash table structure have different fields and so
47 support different linking features. */
48 enum bfd_link_hash_table_type
50 bfd_link_generic_hash_table
,
51 bfd_link_elf_hash_table
54 /* These are the possible types of an entry in the BFD link hash
57 enum bfd_link_hash_type
59 bfd_link_hash_new
, /* Symbol is new. */
60 bfd_link_hash_undefined
, /* Symbol seen before, but undefined. */
61 bfd_link_hash_undefweak
, /* Symbol is weak and undefined. */
62 bfd_link_hash_defined
, /* Symbol is defined. */
63 bfd_link_hash_defweak
, /* Symbol is weak and defined. */
64 bfd_link_hash_common
, /* Symbol is common. */
65 bfd_link_hash_indirect
, /* Symbol is an indirect link. */
66 bfd_link_hash_warning
/* Like indirect, but warn if referenced. */
69 /* The linking routines use a hash table which uses this structure for
72 struct bfd_link_hash_entry
74 /* Base hash table entry structure. */
75 struct bfd_hash_entry root
;
76 /* Type of this entry. */
77 enum bfd_link_hash_type type
;
79 /* Undefined and common symbols are kept in a linked list through
80 this field. This field is not in the union because that would
81 force us to remove entries from the list when we changed their
82 type, which would force the list to be doubly linked, which would
83 waste more memory. When an undefined or common symbol is
84 created, it should be added to this list, the head of which is in
85 the link hash table itself. As symbols are defined, they need
86 not be removed from the list; anything which reads the list must
87 doublecheck the symbol type.
89 Weak symbols are not kept on this list.
91 Defined and defweak symbols use this field as a reference marker.
92 If the field is not NULL, or this structure is the tail of the
93 undefined symbol list, the symbol has been referenced. If the
94 symbol is undefined and becomes defined, this field will
95 automatically be non-NULL since the symbol will have been on the
96 undefined symbol list. */
97 struct bfd_link_hash_entry
*next
;
98 /* A union of information depending upon the type. */
101 /* Nothing is kept for bfd_hash_new. */
102 /* bfd_link_hash_undefined, bfd_link_hash_undefweak. */
105 bfd
*abfd
; /* BFD symbol was found in. */
107 /* bfd_link_hash_defined, bfd_link_hash_defweak. */
110 bfd_vma value
; /* Symbol value. */
111 asection
*section
; /* Symbol section. */
113 /* bfd_link_hash_indirect, bfd_link_hash_warning. */
116 struct bfd_link_hash_entry
*link
; /* Real symbol. */
117 const char *warning
; /* Warning (bfd_link_hash_warning only). */
119 /* bfd_link_hash_common. */
122 /* The linker needs to know three things about common
123 symbols: the size, the alignment, and the section in
124 which the symbol should be placed. We store the size
125 here, and we allocate a small structure to hold the
126 section and the alignment. The alignment is stored as a
127 power of two. We don't store all the information
128 directly because we don't want to increase the size of
129 the union; this structure is a major space user in the
131 bfd_size_type size
; /* Common symbol size. */
132 struct bfd_link_hash_common_entry
134 unsigned int alignment_power
; /* Alignment. */
135 asection
*section
; /* Symbol section. */
141 /* This is the link hash table. It is a derived class of
144 struct bfd_link_hash_table
146 /* The hash table itself. */
147 struct bfd_hash_table table
;
148 /* The back end which created this hash table. This indicates the
149 type of the entries in the hash table, which is sometimes
150 important information when linking object files of different
152 const bfd_target
*creator
;
153 /* A linked list of undefined and common symbols, linked through the
154 next field in the bfd_link_hash_entry structure. */
155 struct bfd_link_hash_entry
*undefs
;
156 /* Entries are added to the tail of the undefs list. */
157 struct bfd_link_hash_entry
*undefs_tail
;
158 /* The type of the ink hash table. */
159 enum bfd_link_hash_table_type type
;
162 /* Look up an entry in a link hash table. If FOLLOW is true, this
163 follows bfd_link_hash_indirect and bfd_link_hash_warning links to
165 extern struct bfd_link_hash_entry
*bfd_link_hash_lookup
166 PARAMS ((struct bfd_link_hash_table
*, const char *, boolean create
,
167 boolean copy
, boolean follow
));
169 /* Look up an entry in the main linker hash table if the symbol might
170 be wrapped. This should only be used for references to an
171 undefined symbol, not for definitions of a symbol. */
173 extern struct bfd_link_hash_entry
*bfd_wrapped_link_hash_lookup
174 PARAMS ((bfd
*, struct bfd_link_info
*, const char *, boolean
, boolean
,
177 /* Traverse a link hash table. */
178 extern void bfd_link_hash_traverse
179 PARAMS ((struct bfd_link_hash_table
*,
180 boolean (*) (struct bfd_link_hash_entry
*, PTR
),
183 /* Add an entry to the undefs list. */
184 extern void bfd_link_add_undef
185 PARAMS ((struct bfd_link_hash_table
*, struct bfd_link_hash_entry
*));
187 /* This structure holds all the information needed to communicate
188 between BFD and the linker when doing a link. */
192 /* Function callbacks. */
193 const struct bfd_link_callbacks
*callbacks
;
194 /* true if BFD should generate a relocateable object file. */
195 boolean relocateable
;
196 /* true if BFD should generate relocation information in the final executable. */
197 boolean emitrelocations
;
198 /* true if BFD should generate a "task linked" object file,
199 similar to relocatable but also with globals converted to statics. */
201 /* true if BFD should generate a shared object. */
203 /* true if BFD should pre-bind symbols in a shared object. */
205 /* true if BFD should export all symbols in the dynamic symbol table
206 of an executable, rather than only those used. */
207 boolean export_dynamic
;
208 /* true if shared objects should be linked directly, not shared. */
210 /* true if the output file should be in a traditional format. This
211 is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
212 on the output file, but may be checked when reading the input
214 boolean traditional_format
;
215 /* true if we want to produced optimized output files. This might
216 need much more time and therefore must be explicitly selected. */
218 /* true if BFD should generate errors for undefined symbols
219 even if generating a shared object. */
220 boolean no_undefined
;
221 /* true if BFD should allow undefined symbols in shared objects even
222 when no_undefined is set to disallow undefined symbols. The net
223 result will be that undefined symbols in regular objects will
224 still trigger an error, but undefined symbols in shared objects
225 will be ignored. The implementation of no_undefined makes the
226 assumption that the runtime linker will choke on undefined
227 symbols. However there is at least one system (BeOS) where
228 undefined symbols in shared libraries is normal since the kernel
229 patches them at load time to select which function is most
230 appropriate for the current architecture. I.E. dynamically
231 select an appropriate memset function. Apparently it is also
232 normal for HPPA shared libraries to have undefined symbols. */
233 boolean allow_shlib_undefined
;
234 /* True if ok to have multiple definition. */
235 boolean allow_multiple_definition
;
236 /* Which symbols to strip. */
237 enum bfd_link_strip strip
;
238 /* Which local symbols to discard. */
239 enum bfd_link_discard discard
;
240 /* true if symbols should be retained in memory, false if they
241 should be freed and reread. */
243 /* The list of input BFD's involved in the link. These are chained
244 together via the link_next field. */
246 /* If a symbol should be created for each input BFD, this is section
247 where those symbols should be placed. It must be a section in
248 the output BFD. It may be NULL, in which case no such symbols
249 will be created. This is to support CREATE_OBJECT_SYMBOLS in the
250 linker command language. */
251 asection
*create_object_symbols_section
;
252 /* Hash table handled by BFD. */
253 struct bfd_link_hash_table
*hash
;
254 /* Hash table of symbols to keep. This is NULL unless strip is
256 struct bfd_hash_table
*keep_hash
;
257 /* true if every symbol should be reported back via the notice
260 /* Hash table of symbols to report back via the notice callback. If
261 this is NULL, and notice_all is false, then no symbols are
263 struct bfd_hash_table
*notice_hash
;
264 /* Hash table of symbols which are being wrapped (the --wrap linker
265 option). If this is NULL, no symbols are being wrapped. */
266 struct bfd_hash_table
*wrap_hash
;
267 /* If a base output file is wanted, then this points to it */
270 /* If non-zero, specifies that branches which are problematic for the
271 MPC860 C0 (or earlier) should be checked for and modified. It gives the
272 number of bytes that should be checked at the end of each text page. */
275 /* The function to call when the executable or shared object is
277 const char *init_function
;
278 /* The function to call when the executable or shared object is
280 const char *fini_function
;
282 /* true if the new ELF dynamic tags are enabled. */
285 /* May be used to set DT_FLAGS for ELF. */
288 /* May be used to set DT_FLAGS_1 for ELF. */
291 /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
292 should be generated/linked against. Set to 1 if this feature
293 is explicitly requested by the user, -1 if enabled by default. */
294 int pei386_auto_import
;
296 /* True if non-PLT relocs should be merged into one reloc section
297 and sorted so that relocs against the same symbol come together. */
300 /* True if executable should not contain copy relocs.
301 Setting this true may result in a non-sharable text segment. */
304 /* True if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
305 should be created. */
306 boolean eh_frame_hdr
;
308 /* How many spare .dynamic DT_NULL entries should be added? */
309 unsigned int spare_dynamic_tags
;
312 /* This structures holds a set of callback functions. These are
313 called by the BFD linker routines. The first argument to each
314 callback function is the bfd_link_info structure being used. Each
315 function returns a boolean value. If the function returns false,
316 then the BFD function which called it will return with a failure
319 struct bfd_link_callbacks
321 /* A function which is called when an object is added from an
322 archive. ABFD is the archive element being added. NAME is the
323 name of the symbol which caused the archive element to be pulled
325 boolean (*add_archive_element
) PARAMS ((struct bfd_link_info
*,
328 /* A function which is called when a symbol is found with multiple
329 definitions. NAME is the symbol which is defined multiple times.
330 OBFD is the old BFD, OSEC is the old section, OVAL is the old
331 value, NBFD is the new BFD, NSEC is the new section, and NVAL is
332 the new value. OBFD may be NULL. OSEC and NSEC may be
333 bfd_com_section or bfd_ind_section. */
334 boolean (*multiple_definition
) PARAMS ((struct bfd_link_info
*,
342 /* A function which is called when a common symbol is defined
343 multiple times. NAME is the symbol appearing multiple times.
344 OBFD is the BFD of the existing symbol; it may be NULL if this is
345 not known. OTYPE is the type of the existing symbol, which may
346 be bfd_link_hash_defined, bfd_link_hash_defweak,
347 bfd_link_hash_common, or bfd_link_hash_indirect. If OTYPE is
348 bfd_link_hash_common, OSIZE is the size of the existing symbol.
349 NBFD is the BFD of the new symbol. NTYPE is the type of the new
350 symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
351 bfd_link_hash_indirect. If NTYPE is bfd_link_hash_common, NSIZE
352 is the size of the new symbol. */
353 boolean (*multiple_common
) PARAMS ((struct bfd_link_info
*,
356 enum bfd_link_hash_type otype
,
359 enum bfd_link_hash_type ntype
,
361 /* A function which is called to add a symbol to a set. ENTRY is
362 the link hash table entry for the set itself (e.g.,
363 __CTOR_LIST__). RELOC is the relocation to use for an entry in
364 the set when generating a relocateable file, and is also used to
365 get the size of the entry when generating an executable file.
366 ABFD, SEC and VALUE identify the value to add to the set. */
367 boolean (*add_to_set
) PARAMS ((struct bfd_link_info
*,
368 struct bfd_link_hash_entry
*entry
,
369 bfd_reloc_code_real_type reloc
,
370 bfd
*abfd
, asection
*sec
, bfd_vma value
));
371 /* A function which is called when the name of a g++ constructor or
372 destructor is found. This is only called by some object file
373 formats. CONSTRUCTOR is true for a constructor, false for a
374 destructor. This will use BFD_RELOC_CTOR when generating a
375 relocateable file. NAME is the name of the symbol found. ABFD,
376 SECTION and VALUE are the value of the symbol. */
377 boolean (*constructor
) PARAMS ((struct bfd_link_info
*,
379 const char *name
, bfd
*abfd
, asection
*sec
,
381 /* A function which is called to issue a linker warning. For
382 example, this is called when there is a reference to a warning
383 symbol. WARNING is the warning to be issued. SYMBOL is the name
384 of the symbol which triggered the warning; it may be NULL if
385 there is none. ABFD, SECTION and ADDRESS identify the location
386 which trigerred the warning; either ABFD or SECTION or both may
387 be NULL if the location is not known. */
388 boolean (*warning
) PARAMS ((struct bfd_link_info
*,
389 const char *warning
, const char *symbol
,
390 bfd
*abfd
, asection
*section
,
392 /* A function which is called when a relocation is attempted against
393 an undefined symbol. NAME is the symbol which is undefined.
394 ABFD, SECTION and ADDRESS identify the location from which the
395 reference is made. FATAL indicates whether an undefined symbol is
396 a fatal error or not. In some cases SECTION may be NULL. */
397 boolean (*undefined_symbol
) PARAMS ((struct bfd_link_info
*,
398 const char *name
, bfd
*abfd
,
402 /* A function which is called when a reloc overflow occurs. NAME is
403 the name of the symbol or section the reloc is against,
404 RELOC_NAME is the name of the relocation, and ADDEND is any
405 addend that is used. ABFD, SECTION and ADDRESS identify the
406 location at which the overflow occurs; if this is the result of a
407 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
408 ABFD will be NULL. */
409 boolean (*reloc_overflow
) PARAMS ((struct bfd_link_info
*,
411 const char *reloc_name
, bfd_vma addend
,
412 bfd
*abfd
, asection
*section
,
414 /* A function which is called when a dangerous reloc is performed.
415 The canonical example is an a29k IHCONST reloc which does not
416 follow an IHIHALF reloc. MESSAGE is an appropriate message.
417 ABFD, SECTION and ADDRESS identify the location at which the
418 problem occurred; if this is the result of a
419 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
420 ABFD will be NULL. */
421 boolean (*reloc_dangerous
) PARAMS ((struct bfd_link_info
*,
423 bfd
*abfd
, asection
*section
,
425 /* A function which is called when a reloc is found to be attached
426 to a symbol which is not being written out. NAME is the name of
427 the symbol. ABFD, SECTION and ADDRESS identify the location of
428 the reloc; if this is the result of a
429 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
430 ABFD will be NULL. */
431 boolean (*unattached_reloc
) PARAMS ((struct bfd_link_info
*,
433 bfd
*abfd
, asection
*section
,
435 /* A function which is called when a symbol in notice_hash is
436 defined or referenced. NAME is the symbol. ABFD, SECTION and
437 ADDRESS are the value of the symbol. If SECTION is
438 bfd_und_section, this is a reference. */
439 boolean (*notice
) PARAMS ((struct bfd_link_info
*, const char *name
,
440 bfd
*abfd
, asection
*section
, bfd_vma address
));
443 /* The linker builds link_order structures which tell the code how to
444 include input data in the output file. */
446 /* These are the types of link_order structures. */
448 enum bfd_link_order_type
450 bfd_undefined_link_order
, /* Undefined. */
451 bfd_indirect_link_order
, /* Built from a section. */
452 bfd_data_link_order
, /* Set to explicit data. */
453 bfd_section_reloc_link_order
, /* Relocate against a section. */
454 bfd_symbol_reloc_link_order
/* Relocate against a symbol. */
457 /* This is the link_order structure itself. These form a chain
458 attached to the section whose contents they are describing. */
460 struct bfd_link_order
462 /* Next link_order in chain. */
463 struct bfd_link_order
*next
;
464 /* Type of link_order. */
465 enum bfd_link_order_type type
;
466 /* Offset within output section. */
468 /* Size within output section. */
470 /* Type specific information. */
475 /* Section to include. If this is used, then
476 section->output_section must be the section the
477 link_order is attached to, section->output_offset must
478 equal the link_order offset field, and section->_raw_size
479 must equal the link_order size field. Maybe these
480 restrictions should be relaxed someday. */
485 /* Size of contents, or zero when contents size == size
486 within output section.
487 A non-zero value allows filling of the output section
488 with an arbitrary repeated pattern. */
490 /* Data to put into file. */
495 /* Description of reloc to generate. Used for
496 bfd_section_reloc_link_order and
497 bfd_symbol_reloc_link_order. */
498 struct bfd_link_order_reloc
*p
;
503 /* A linker order of type bfd_section_reloc_link_order or
504 bfd_symbol_reloc_link_order means to create a reloc against a
505 section or symbol, respectively. This is used to implement -Ur to
506 generate relocs for the constructor tables. The
507 bfd_link_order_reloc structure describes the reloc that BFD should
508 create. It is similar to a arelent, but I didn't use arelent
509 because the linker does not know anything about most symbols, and
510 any asymbol structure it creates will be partially meaningless.
511 This information could logically be in the bfd_link_order struct,
512 but I didn't want to waste the space since these types of relocs
513 are relatively rare. */
515 struct bfd_link_order_reloc
518 bfd_reloc_code_real_type reloc
;
522 /* For type bfd_section_reloc_link_order, this is the section
523 the reloc should be against. This must be a section in the
524 output BFD, not any of the input BFDs. */
526 /* For type bfd_symbol_reloc_link_order, this is the name of the
527 symbol the reloc should be against. */
531 /* Addend to use. The object file should contain zero. The BFD
532 backend is responsible for filling in the contents of the object
533 file correctly. For some object file formats (e.g., COFF) the
534 addend must be stored into in the object file, and for some
535 (e.g., SPARC a.out) it is kept in the reloc. */
539 /* Allocate a new link_order for a section. */
540 extern struct bfd_link_order
*bfd_new_link_order
PARAMS ((bfd
*, asection
*));
542 /* These structures are used to describe version information for the
543 ELF linker. These structures could be manipulated entirely inside
544 BFD, but it would be a pain. Instead, the regular linker sets up
545 these structures, and then passes them into BFD. */
547 /* Regular expressions for a version. */
549 struct bfd_elf_version_expr
551 /* Next regular expression for this version. */
552 struct bfd_elf_version_expr
*next
;
553 /* Regular expression. */
555 /* Matching function. */
556 int (*match
) PARAMS((struct bfd_elf_version_expr
*, const char *));
559 /* Version dependencies. */
561 struct bfd_elf_version_deps
563 /* Next dependency for this version. */
564 struct bfd_elf_version_deps
*next
;
565 /* The version which this version depends upon. */
566 struct bfd_elf_version_tree
*version_needed
;
569 /* A node in the version tree. */
571 struct bfd_elf_version_tree
574 struct bfd_elf_version_tree
*next
;
575 /* Name of this version. */
577 /* Version number. */
579 /* Regular expressions for global symbols in this version. */
580 struct bfd_elf_version_expr
*globals
;
581 /* Regular expressions for local symbols in this version. */
582 struct bfd_elf_version_expr
*locals
;
583 /* List of versions which this version depends upon. */
584 struct bfd_elf_version_deps
*deps
;
585 /* Index of the version name. This is used within BFD. */
586 unsigned int name_indx
;
587 /* Whether this version tree was used. This is used within BFD. */