1 /* linker.c -- BFD linker routines
2 Copyright (C) 1993-2016 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. */
33 The linker uses three special entry points in the BFD target
34 vector. It is not necessary to write special routines for
35 these entry points when creating a new BFD back end, since
36 generic versions are provided. However, writing them can
37 speed up linking and make it use significantly less runtime
40 The first routine creates a hash table used by the other
41 routines. The second routine adds the symbols from an object
42 file to the hash table. The third routine takes all the
43 object files and links them together to create the output
44 file. These routines are designed so that the linker proper
45 does not need to know anything about the symbols in the object
46 files that it is linking. The linker merely arranges the
47 sections as directed by the linker script and lets BFD handle
48 the details of symbols and relocs.
50 The second routine and third routines are passed a pointer to
51 a <<struct bfd_link_info>> structure (defined in
52 <<bfdlink.h>>) which holds information relevant to the link,
53 including the linker hash table (which was created by the
54 first routine) and a set of callback functions to the linker
57 The generic linker routines are in <<linker.c>>, and use the
58 header file <<genlink.h>>. As of this writing, the only back
59 ends which have implemented versions of these routines are
60 a.out (in <<aoutx.h>>) and ECOFF (in <<ecoff.c>>). The a.out
61 routines are used as examples throughout this section.
64 @* Creating a Linker Hash Table::
65 @* Adding Symbols to the Hash Table::
66 @* Performing the Final Link::
70 Creating a Linker Hash Table, Adding Symbols to the Hash Table, Linker Functions, Linker Functions
72 Creating a linker hash table
74 @cindex _bfd_link_hash_table_create in target vector
75 @cindex target vector (_bfd_link_hash_table_create)
76 The linker routines must create a hash table, which must be
77 derived from <<struct bfd_link_hash_table>> described in
78 <<bfdlink.c>>. @xref{Hash Tables}, for information on how to
79 create a derived hash table. This entry point is called using
80 the target vector of the linker output file.
82 The <<_bfd_link_hash_table_create>> entry point must allocate
83 and initialize an instance of the desired hash table. If the
84 back end does not require any additional information to be
85 stored with the entries in the hash table, the entry point may
86 simply create a <<struct bfd_link_hash_table>>. Most likely,
87 however, some additional information will be needed.
89 For example, with each entry in the hash table the a.out
90 linker keeps the index the symbol has in the final output file
91 (this index number is used so that when doing a relocatable
92 link the symbol index used in the output file can be quickly
93 filled in when copying over a reloc). The a.out linker code
94 defines the required structures and functions for a hash table
95 derived from <<struct bfd_link_hash_table>>. The a.out linker
96 hash table is created by the function
97 <<NAME(aout,link_hash_table_create)>>; it simply allocates
98 space for the hash table, initializes it, and returns a
101 When writing the linker routines for a new back end, you will
102 generally not know exactly which fields will be required until
103 you have finished. You should simply create a new hash table
104 which defines no additional fields, and then simply add fields
105 as they become necessary.
108 Adding Symbols to the Hash Table, Performing the Final Link, Creating a Linker Hash Table, Linker Functions
110 Adding symbols to the hash table
112 @cindex _bfd_link_add_symbols in target vector
113 @cindex target vector (_bfd_link_add_symbols)
114 The linker proper will call the <<_bfd_link_add_symbols>>
115 entry point for each object file or archive which is to be
116 linked (typically these are the files named on the command
117 line, but some may also come from the linker script). The
118 entry point is responsible for examining the file. For an
119 object file, BFD must add any relevant symbol information to
120 the hash table. For an archive, BFD must determine which
121 elements of the archive should be used and adding them to the
124 The a.out version of this entry point is
125 <<NAME(aout,link_add_symbols)>>.
128 @* Differing file formats::
129 @* Adding symbols from an object file::
130 @* Adding symbols from an archive::
134 Differing file formats, Adding symbols from an object file, Adding Symbols to the Hash Table, Adding Symbols to the Hash Table
136 Differing file formats
138 Normally all the files involved in a link will be of the same
139 format, but it is also possible to link together different
140 format object files, and the back end must support that. The
141 <<_bfd_link_add_symbols>> entry point is called via the target
142 vector of the file to be added. This has an important
143 consequence: the function may not assume that the hash table
144 is the type created by the corresponding
145 <<_bfd_link_hash_table_create>> vector. All the
146 <<_bfd_link_add_symbols>> function can assume about the hash
147 table is that it is derived from <<struct
148 bfd_link_hash_table>>.
150 Sometimes the <<_bfd_link_add_symbols>> function must store
151 some information in the hash table entry to be used by the
152 <<_bfd_final_link>> function. In such a case the output bfd
153 xvec must be checked to make sure that the hash table was
154 created by an object file of the same format.
156 The <<_bfd_final_link>> routine must be prepared to handle a
157 hash entry without any extra information added by the
158 <<_bfd_link_add_symbols>> function. A hash entry without
159 extra information will also occur when the linker script
160 directs the linker to create a symbol. Note that, regardless
161 of how a hash table entry is added, all the fields will be
162 initialized to some sort of null value by the hash table entry
163 initialization function.
165 See <<ecoff_link_add_externals>> for an example of how to
166 check the output bfd before saving information (in this
167 case, the ECOFF external symbol debugging information) in a
171 Adding symbols from an object file, Adding symbols from an archive, Differing file formats, Adding Symbols to the Hash Table
173 Adding symbols from an object file
175 When the <<_bfd_link_add_symbols>> routine is passed an object
176 file, it must add all externally visible symbols in that
177 object file to the hash table. The actual work of adding the
178 symbol to the hash table is normally handled by the function
179 <<_bfd_generic_link_add_one_symbol>>. The
180 <<_bfd_link_add_symbols>> routine is responsible for reading
181 all the symbols from the object file and passing the correct
182 information to <<_bfd_generic_link_add_one_symbol>>.
184 The <<_bfd_link_add_symbols>> routine should not use
185 <<bfd_canonicalize_symtab>> to read the symbols. The point of
186 providing this routine is to avoid the overhead of converting
187 the symbols into generic <<asymbol>> structures.
189 @findex _bfd_generic_link_add_one_symbol
190 <<_bfd_generic_link_add_one_symbol>> handles the details of
191 combining common symbols, warning about multiple definitions,
192 and so forth. It takes arguments which describe the symbol to
193 add, notably symbol flags, a section, and an offset. The
194 symbol flags include such things as <<BSF_WEAK>> or
195 <<BSF_INDIRECT>>. The section is a section in the object
196 file, or something like <<bfd_und_section_ptr>> for an undefined
197 symbol or <<bfd_com_section_ptr>> for a common symbol.
199 If the <<_bfd_final_link>> routine is also going to need to
200 read the symbol information, the <<_bfd_link_add_symbols>>
201 routine should save it somewhere attached to the object file
202 BFD. However, the information should only be saved if the
203 <<keep_memory>> field of the <<info>> argument is TRUE, so
204 that the <<-no-keep-memory>> linker switch is effective.
206 The a.out function which adds symbols from an object file is
207 <<aout_link_add_object_symbols>>, and most of the interesting
208 work is in <<aout_link_add_symbols>>. The latter saves
209 pointers to the hash tables entries created by
210 <<_bfd_generic_link_add_one_symbol>> indexed by symbol number,
211 so that the <<_bfd_final_link>> routine does not have to call
212 the hash table lookup routine to locate the entry.
215 Adding symbols from an archive, , Adding symbols from an object file, Adding Symbols to the Hash Table
217 Adding symbols from an archive
219 When the <<_bfd_link_add_symbols>> routine is passed an
220 archive, it must look through the symbols defined by the
221 archive and decide which elements of the archive should be
222 included in the link. For each such element it must call the
223 <<add_archive_element>> linker callback, and it must add the
224 symbols from the object file to the linker hash table. (The
225 callback may in fact indicate that a replacement BFD should be
226 used, in which case the symbols from that BFD should be added
227 to the linker hash table instead.)
229 @findex _bfd_generic_link_add_archive_symbols
230 In most cases the work of looking through the symbols in the
231 archive should be done by the
232 <<_bfd_generic_link_add_archive_symbols>> function.
233 <<_bfd_generic_link_add_archive_symbols>> is passed a function
234 to call to make the final decision about adding an archive
235 element to the link and to do the actual work of adding the
236 symbols to the linker hash table. If the element is to
237 be included, the <<add_archive_element>> linker callback
238 routine must be called with the element as an argument, and
239 the element's symbols must be added to the linker hash table
240 just as though the element had itself been passed to the
241 <<_bfd_link_add_symbols>> function.
243 When the a.out <<_bfd_link_add_symbols>> function receives an
244 archive, it calls <<_bfd_generic_link_add_archive_symbols>>
245 passing <<aout_link_check_archive_element>> as the function
246 argument. <<aout_link_check_archive_element>> calls
247 <<aout_link_check_ar_symbols>>. If the latter decides to add
248 the element (an element is only added if it provides a real,
249 non-common, definition for a previously undefined or common
250 symbol) it calls the <<add_archive_element>> callback and then
251 <<aout_link_check_archive_element>> calls
252 <<aout_link_add_symbols>> to actually add the symbols to the
253 linker hash table - possibly those of a substitute BFD, if the
254 <<add_archive_element>> callback avails itself of that option.
256 The ECOFF back end is unusual in that it does not normally
257 call <<_bfd_generic_link_add_archive_symbols>>, because ECOFF
258 archives already contain a hash table of symbols. The ECOFF
259 back end searches the archive itself to avoid the overhead of
260 creating a new hash table.
263 Performing the Final Link, , Adding Symbols to the Hash Table, Linker Functions
265 Performing the final link
267 @cindex _bfd_link_final_link in target vector
268 @cindex target vector (_bfd_final_link)
269 When all the input files have been processed, the linker calls
270 the <<_bfd_final_link>> entry point of the output BFD. This
271 routine is responsible for producing the final output file,
272 which has several aspects. It must relocate the contents of
273 the input sections and copy the data into the output sections.
274 It must build an output symbol table including any local
275 symbols from the input files and the global symbols from the
276 hash table. When producing relocatable output, it must
277 modify the input relocs and write them into the output file.
278 There may also be object format dependent work to be done.
280 The linker will also call the <<write_object_contents>> entry
281 point when the BFD is closed. The two entry points must work
282 together in order to produce the correct output file.
284 The details of how this works are inevitably dependent upon
285 the specific object file format. The a.out
286 <<_bfd_final_link>> routine is <<NAME(aout,final_link)>>.
289 @* Information provided by the linker::
290 @* Relocating the section contents::
291 @* Writing the symbol table::
295 Information provided by the linker, Relocating the section contents, Performing the Final Link, Performing the Final Link
297 Information provided by the linker
299 Before the linker calls the <<_bfd_final_link>> entry point,
300 it sets up some data structures for the function to use.
302 The <<input_bfds>> field of the <<bfd_link_info>> structure
303 will point to a list of all the input files included in the
304 link. These files are linked through the <<link.next>> field
305 of the <<bfd>> structure.
307 Each section in the output file will have a list of
308 <<link_order>> structures attached to the <<map_head.link_order>>
309 field (the <<link_order>> structure is defined in
310 <<bfdlink.h>>). These structures describe how to create the
311 contents of the output section in terms of the contents of
312 various input sections, fill constants, and, eventually, other
313 types of information. They also describe relocs that must be
314 created by the BFD backend, but do not correspond to any input
315 file; this is used to support -Ur, which builds constructors
316 while generating a relocatable object file.
319 Relocating the section contents, Writing the symbol table, Information provided by the linker, Performing the Final Link
321 Relocating the section contents
323 The <<_bfd_final_link>> function should look through the
324 <<link_order>> structures attached to each section of the
325 output file. Each <<link_order>> structure should either be
326 handled specially, or it should be passed to the function
327 <<_bfd_default_link_order>> which will do the right thing
328 (<<_bfd_default_link_order>> is defined in <<linker.c>>).
330 For efficiency, a <<link_order>> of type
331 <<bfd_indirect_link_order>> whose associated section belongs
332 to a BFD of the same format as the output BFD must be handled
333 specially. This type of <<link_order>> describes part of an
334 output section in terms of a section belonging to one of the
335 input files. The <<_bfd_final_link>> function should read the
336 contents of the section and any associated relocs, apply the
337 relocs to the section contents, and write out the modified
338 section contents. If performing a relocatable link, the
339 relocs themselves must also be modified and written out.
341 @findex _bfd_relocate_contents
342 @findex _bfd_final_link_relocate
343 The functions <<_bfd_relocate_contents>> and
344 <<_bfd_final_link_relocate>> provide some general support for
345 performing the actual relocations, notably overflow checking.
346 Their arguments include information about the symbol the
347 relocation is against and a <<reloc_howto_type>> argument
348 which describes the relocation to perform. These functions
349 are defined in <<reloc.c>>.
351 The a.out function which handles reading, relocating, and
352 writing section contents is <<aout_link_input_section>>. The
353 actual relocation is done in <<aout_link_input_section_std>>
354 and <<aout_link_input_section_ext>>.
357 Writing the symbol table, , Relocating the section contents, Performing the Final Link
359 Writing the symbol table
361 The <<_bfd_final_link>> function must gather all the symbols
362 in the input files and write them out. It must also write out
363 all the symbols in the global hash table. This must be
364 controlled by the <<strip>> and <<discard>> fields of the
365 <<bfd_link_info>> structure.
367 The local symbols of the input files will not have been
368 entered into the linker hash table. The <<_bfd_final_link>>
369 routine must consider each input file and include the symbols
370 in the output file. It may be convenient to do this when
371 looking through the <<link_order>> structures, or it may be
372 done by stepping through the <<input_bfds>> list.
374 The <<_bfd_final_link>> routine must also traverse the global
375 hash table to gather all the externally visible symbols. It
376 is possible that most of the externally visible symbols may be
377 written out when considering the symbols of each input file,
378 but it is still necessary to traverse the hash table since the
379 linker script may have defined some symbols that are not in
380 any of the input files.
382 The <<strip>> field of the <<bfd_link_info>> structure
383 controls which symbols are written out. The possible values
384 are listed in <<bfdlink.h>>. If the value is <<strip_some>>,
385 then the <<keep_hash>> field of the <<bfd_link_info>>
386 structure is a hash table of symbols to keep; each symbol
387 should be looked up in this hash table, and only symbols which
388 are present should be included in the output file.
390 If the <<strip>> field of the <<bfd_link_info>> structure
391 permits local symbols to be written out, the <<discard>> field
392 is used to further controls which local symbols are included
393 in the output file. If the value is <<discard_l>>, then all
394 local symbols which begin with a certain prefix are discarded;
395 this is controlled by the <<bfd_is_local_label_name>> entry point.
397 The a.out backend handles symbols by calling
398 <<aout_link_write_symbols>> on each input BFD and then
399 traversing the global hash table with the function
400 <<aout_link_write_other_symbol>>. It builds a string table
401 while writing out the symbols, which is written to the output
402 file at the end of <<NAME(aout,final_link)>>.
405 static bfd_boolean generic_link_add_object_symbols
406 (bfd *, struct bfd_link_info *, bfd_boolean collect);
407 static bfd_boolean generic_link_add_symbols
408 (bfd *, struct bfd_link_info *, bfd_boolean);
409 static bfd_boolean generic_link_check_archive_element_no_collect
410 (bfd *, struct bfd_link_info *, struct bfd_link_hash_entry *, const char *,
412 static bfd_boolean generic_link_check_archive_element_collect
413 (bfd *, struct bfd_link_info *, struct bfd_link_hash_entry *, const char *,
415 static bfd_boolean generic_link_check_archive_element
416 (bfd *, struct bfd_link_info *, struct bfd_link_hash_entry *, const char *,
417 bfd_boolean *, bfd_boolean);
418 static bfd_boolean generic_link_add_symbol_list
419 (bfd *, struct bfd_link_info *, bfd_size_type count, asymbol **,
421 static bfd_boolean generic_add_output_symbol
422 (bfd *, size_t *psymalloc, asymbol *);
423 static bfd_boolean default_data_link_order
424 (bfd *, struct bfd_link_info *, asection *, struct bfd_link_order *);
425 static bfd_boolean default_indirect_link_order
426 (bfd *, struct bfd_link_info *, asection *, struct bfd_link_order *,
429 /* The link hash table structure is defined in bfdlink.h. It provides
430 a base hash table which the backend specific hash tables are built
433 /* Routine to create an entry in the link hash table. */
435 struct bfd_hash_entry *
436 _bfd_link_hash_newfunc (struct bfd_hash_entry *entry,
437 struct bfd_hash_table *table,
440 /* Allocate the structure if it has not already been allocated by a
444 entry = (struct bfd_hash_entry *)
445 bfd_hash_allocate (table, sizeof (struct bfd_link_hash_entry));
450 /* Call the allocation method of the superclass. */
451 entry = bfd_hash_newfunc (entry, table, string);
454 struct bfd_link_hash_entry *h = (struct bfd_link_hash_entry *) entry;
456 /* Initialize the local fields. */
457 memset ((char *) &h->root + sizeof (h->root), 0,
458 sizeof (*h) - sizeof (h->root));
464 /* Initialize a link hash table. The BFD argument is the one
465 responsible for creating this table. */
468 _bfd_link_hash_table_init
469 (struct bfd_link_hash_table *table,
470 bfd *abfd ATTRIBUTE_UNUSED,
471 struct bfd_hash_entry *(*newfunc) (struct bfd_hash_entry *,
472 struct bfd_hash_table *,
474 unsigned int entsize)
478 BFD_ASSERT (!abfd->is_linker_output && !abfd->link.hash);
479 table->undefs = NULL;
480 table->undefs_tail = NULL;
481 table->type = bfd_link_generic_hash_table;
483 ret = bfd_hash_table_init (&table->table, newfunc, entsize);
486 /* Arrange for destruction of this hash table on closing ABFD. */
487 table->hash_table_free = _bfd_generic_link_hash_table_free;
488 abfd->link.hash = table;
489 abfd->is_linker_output = TRUE;
494 /* Look up a symbol in a link hash table. If follow is TRUE, we
495 follow bfd_link_hash_indirect and bfd_link_hash_warning links to
498 struct bfd_link_hash_entry *
499 bfd_link_hash_lookup (struct bfd_link_hash_table *table,
505 struct bfd_link_hash_entry *ret;
507 ret = ((struct bfd_link_hash_entry *)
508 bfd_hash_lookup (&table->table, string, create, copy));
510 if (follow && ret != NULL)
512 while (ret->type == bfd_link_hash_indirect
513 || ret->type == bfd_link_hash_warning)
520 /* Look up a symbol in the main linker hash table if the symbol might
521 be wrapped. This should only be used for references to an
522 undefined symbol, not for definitions of a symbol. */
524 struct bfd_link_hash_entry *
525 bfd_wrapped_link_hash_lookup (bfd *abfd,
526 struct bfd_link_info *info,
534 if (info->wrap_hash != NULL)
540 if (*l == bfd_get_symbol_leading_char (abfd) || *l == info->wrap_char)
547 #define WRAP "__wrap_"
549 if (bfd_hash_lookup (info->wrap_hash, l, FALSE, FALSE) != NULL)
552 struct bfd_link_hash_entry *h;
554 /* This symbol is being wrapped. We want to replace all
555 references to SYM with references to __wrap_SYM. */
557 amt = strlen (l) + sizeof WRAP + 1;
558 n = (char *) bfd_malloc (amt);
566 h = bfd_link_hash_lookup (info->hash, n, create, TRUE, follow);
572 #define REAL "__real_"
575 && CONST_STRNEQ (l, REAL)
576 && bfd_hash_lookup (info->wrap_hash, l + sizeof REAL - 1,
577 FALSE, FALSE) != NULL)
580 struct bfd_link_hash_entry *h;
582 /* This is a reference to __real_SYM, where SYM is being
583 wrapped. We want to replace all references to __real_SYM
584 with references to SYM. */
586 amt = strlen (l + sizeof REAL - 1) + 2;
587 n = (char *) bfd_malloc (amt);
593 strcat (n, l + sizeof REAL - 1);
594 h = bfd_link_hash_lookup (info->hash, n, create, TRUE, follow);
602 return bfd_link_hash_lookup (info->hash, string, create, copy, follow);
605 /* If H is a wrapped symbol, ie. the symbol name starts with "__wrap_"
606 and the remainder is found in wrap_hash, return the real symbol. */
608 struct bfd_link_hash_entry *
609 unwrap_hash_lookup (struct bfd_link_info *info,
611 struct bfd_link_hash_entry *h)
613 const char *l = h->root.string;
615 if (*l == bfd_get_symbol_leading_char (input_bfd)
616 || *l == info->wrap_char)
619 if (CONST_STRNEQ (l, WRAP))
621 l += sizeof WRAP - 1;
623 if (bfd_hash_lookup (info->wrap_hash, l, FALSE, FALSE) != NULL)
626 if (l - (sizeof WRAP - 1) != h->root.string)
630 *(char *) l = *h->root.string;
632 h = bfd_link_hash_lookup (info->hash, l, FALSE, FALSE, FALSE);
641 /* Traverse a generic link hash table. Differs from bfd_hash_traverse
642 in the treatment of warning symbols. When warning symbols are
643 created they replace the real symbol, so you don't get to see the
644 real symbol in a bfd_hash_travere. This traversal calls func with
648 bfd_link_hash_traverse
649 (struct bfd_link_hash_table *htab,
650 bfd_boolean (*func) (struct bfd_link_hash_entry *, void *),
655 htab->table.frozen = 1;
656 for (i = 0; i < htab->table.size; i++)
658 struct bfd_link_hash_entry *p;
660 p = (struct bfd_link_hash_entry *) htab->table.table[i];
661 for (; p != NULL; p = (struct bfd_link_hash_entry *) p->root.next)
662 if (!(*func) (p->type == bfd_link_hash_warning ? p->u.i.link : p, info))
666 htab->table.frozen = 0;
669 /* Add a symbol to the linker hash table undefs list. */
672 bfd_link_add_undef (struct bfd_link_hash_table *table,
673 struct bfd_link_hash_entry *h)
675 BFD_ASSERT (h->u.undef.next == NULL);
676 if (table->undefs_tail != NULL)
677 table->undefs_tail->u.undef.next = h;
678 if (table->undefs == NULL)
680 table->undefs_tail = h;
683 /* The undefs list was designed so that in normal use we don't need to
684 remove entries. However, if symbols on the list are changed from
685 bfd_link_hash_undefined to either bfd_link_hash_undefweak or
686 bfd_link_hash_new for some reason, then they must be removed from the
687 list. Failure to do so might result in the linker attempting to add
688 the symbol to the list again at a later stage. */
691 bfd_link_repair_undef_list (struct bfd_link_hash_table *table)
693 struct bfd_link_hash_entry **pun;
695 pun = &table->undefs;
698 struct bfd_link_hash_entry *h = *pun;
700 if (h->type == bfd_link_hash_new
701 || h->type == bfd_link_hash_undefweak)
703 *pun = h->u.undef.next;
704 h->u.undef.next = NULL;
705 if (h == table->undefs_tail)
707 if (pun == &table->undefs)
708 table->undefs_tail = NULL;
710 /* pun points at an u.undef.next field. Go back to
711 the start of the link_hash_entry. */
712 table->undefs_tail = (struct bfd_link_hash_entry *)
713 ((char *) pun - ((char *) &h->u.undef.next - (char *) h));
718 pun = &h->u.undef.next;
722 /* Routine to create an entry in a generic link hash table. */
724 struct bfd_hash_entry *
725 _bfd_generic_link_hash_newfunc (struct bfd_hash_entry *entry,
726 struct bfd_hash_table *table,
729 /* Allocate the structure if it has not already been allocated by a
733 entry = (struct bfd_hash_entry *)
734 bfd_hash_allocate (table, sizeof (struct generic_link_hash_entry));
739 /* Call the allocation method of the superclass. */
740 entry = _bfd_link_hash_newfunc (entry, table, string);
743 struct generic_link_hash_entry *ret;
745 /* Set local fields. */
746 ret = (struct generic_link_hash_entry *) entry;
747 ret->written = FALSE;
754 /* Create a generic link hash table. */
756 struct bfd_link_hash_table *
757 _bfd_generic_link_hash_table_create (bfd *abfd)
759 struct generic_link_hash_table *ret;
760 bfd_size_type amt = sizeof (struct generic_link_hash_table);
762 ret = (struct generic_link_hash_table *) bfd_malloc (amt);
765 if (! _bfd_link_hash_table_init (&ret->root, abfd,
766 _bfd_generic_link_hash_newfunc,
767 sizeof (struct generic_link_hash_entry)))
776 _bfd_generic_link_hash_table_free (bfd *obfd)
778 struct generic_link_hash_table *ret;
780 BFD_ASSERT (obfd->is_linker_output && obfd->link.hash);
781 ret = (struct generic_link_hash_table *) obfd->link.hash;
782 bfd_hash_table_free (&ret->root.table);
784 obfd->link.hash = NULL;
785 obfd->is_linker_output = FALSE;
788 /* Grab the symbols for an object file when doing a generic link. We
789 store the symbols in the outsymbols field. We need to keep them
790 around for the entire link to ensure that we only read them once.
791 If we read them multiple times, we might wind up with relocs and
792 the hash table pointing to different instances of the symbol
796 bfd_generic_link_read_symbols (bfd *abfd)
798 if (bfd_get_outsymbols (abfd) == NULL)
803 symsize = bfd_get_symtab_upper_bound (abfd);
806 bfd_get_outsymbols (abfd) = (struct bfd_symbol **) bfd_alloc (abfd,
808 if (bfd_get_outsymbols (abfd) == NULL && symsize != 0)
810 symcount = bfd_canonicalize_symtab (abfd, bfd_get_outsymbols (abfd));
813 bfd_get_symcount (abfd) = symcount;
819 /* Generic function to add symbols to from an object file to the
820 global hash table. This version does not automatically collect
821 constructors by name. */
824 _bfd_generic_link_add_symbols (bfd *abfd, struct bfd_link_info *info)
826 return generic_link_add_symbols (abfd, info, FALSE);
829 /* Generic function to add symbols from an object file to the global
830 hash table. This version automatically collects constructors by
831 name, as the collect2 program does. It should be used for any
832 target which does not provide some other mechanism for setting up
833 constructors and destructors; these are approximately those targets
834 for which gcc uses collect2 and do not support stabs. */
837 _bfd_generic_link_add_symbols_collect (bfd *abfd, struct bfd_link_info *info)
839 return generic_link_add_symbols (abfd, info, TRUE);
842 /* Indicate that we are only retrieving symbol values from this
843 section. We want the symbols to act as though the values in the
844 file are absolute. */
847 _bfd_generic_link_just_syms (asection *sec,
848 struct bfd_link_info *info ATTRIBUTE_UNUSED)
850 sec->sec_info_type = SEC_INFO_TYPE_JUST_SYMS;
851 sec->output_section = bfd_abs_section_ptr;
852 sec->output_offset = sec->vma;
855 /* Copy the symbol type and other attributes for a linker script
856 assignment from HSRC to HDEST.
857 The default implementation does nothing. */
859 _bfd_generic_copy_link_hash_symbol_type (bfd *abfd ATTRIBUTE_UNUSED,
860 struct bfd_link_hash_entry *hdest ATTRIBUTE_UNUSED,
861 struct bfd_link_hash_entry *hsrc ATTRIBUTE_UNUSED)
865 /* Add symbols from an object file to the global hash table. */
868 generic_link_add_symbols (bfd *abfd,
869 struct bfd_link_info *info,
874 switch (bfd_get_format (abfd))
877 ret = generic_link_add_object_symbols (abfd, info, collect);
880 ret = (_bfd_generic_link_add_archive_symbols
883 ? generic_link_check_archive_element_collect
884 : generic_link_check_archive_element_no_collect)));
887 bfd_set_error (bfd_error_wrong_format);
894 /* Add symbols from an object file to the global hash table. */
897 generic_link_add_object_symbols (bfd *abfd,
898 struct bfd_link_info *info,
901 bfd_size_type symcount;
902 struct bfd_symbol **outsyms;
904 if (!bfd_generic_link_read_symbols (abfd))
906 symcount = _bfd_generic_link_get_symcount (abfd);
907 outsyms = _bfd_generic_link_get_symbols (abfd);
908 return generic_link_add_symbol_list (abfd, info, symcount, outsyms, collect);
911 /* Generic function to add symbols from an archive file to the global
912 hash file. This function presumes that the archive symbol table
913 has already been read in (this is normally done by the
914 bfd_check_format entry point). It looks through the archive symbol
915 table for symbols that are undefined or common in the linker global
916 symbol hash table. When one is found, the CHECKFN argument is used
917 to see if an object file should be included. This allows targets
918 to customize common symbol behaviour. CHECKFN should set *PNEEDED
919 to TRUE if the object file should be included, and must also call
920 the bfd_link_info add_archive_element callback function and handle
921 adding the symbols to the global hash table. CHECKFN must notice
922 if the callback indicates a substitute BFD, and arrange to add
923 those symbols instead if it does so. CHECKFN should only return
924 FALSE if some sort of error occurs. */
927 _bfd_generic_link_add_archive_symbols
929 struct bfd_link_info *info,
930 bfd_boolean (*checkfn) (bfd *, struct bfd_link_info *,
931 struct bfd_link_hash_entry *, const char *,
936 unsigned char *included;
938 if (! bfd_has_map (abfd))
940 /* An empty archive is a special case. */
941 if (bfd_openr_next_archived_file (abfd, NULL) == NULL)
943 bfd_set_error (bfd_error_no_armap);
947 amt = bfd_ardata (abfd)->symdef_count;
950 amt *= sizeof (*included);
951 included = (unsigned char *) bfd_zmalloc (amt);
952 if (included == NULL)
961 file_ptr last_ar_offset = -1;
962 bfd_boolean needed = FALSE;
966 arsyms = bfd_ardata (abfd)->symdefs;
967 arsym_end = arsyms + bfd_ardata (abfd)->symdef_count;
968 for (arsym = arsyms, indx = 0; arsym < arsym_end; arsym++, indx++)
970 struct bfd_link_hash_entry *h;
971 struct bfd_link_hash_entry *undefs_tail;
975 if (needed && arsym->file_offset == last_ar_offset)
981 h = bfd_link_hash_lookup (info->hash, arsym->name,
985 && info->pei386_auto_import
986 && CONST_STRNEQ (arsym->name, "__imp_"))
987 h = bfd_link_hash_lookup (info->hash, arsym->name + 6,
992 if (h->type != bfd_link_hash_undefined
993 && h->type != bfd_link_hash_common)
995 if (h->type != bfd_link_hash_undefweak)
996 /* Symbol must be defined. Don't check it again. */
1001 if (last_ar_offset != arsym->file_offset)
1003 last_ar_offset = arsym->file_offset;
1004 element = _bfd_get_elt_at_filepos (abfd, last_ar_offset);
1006 || !bfd_check_format (element, bfd_object))
1010 undefs_tail = info->hash->undefs_tail;
1012 /* CHECKFN will see if this element should be included, and
1013 go ahead and include it if appropriate. */
1014 if (! (*checkfn) (element, info, h, arsym->name, &needed))
1021 /* Look backward to mark all symbols from this object file
1022 which we have already seen in this pass. */
1031 while (arsyms[mark].file_offset == last_ar_offset);
1033 if (undefs_tail != info->hash->undefs_tail)
1047 /* See if we should include an archive element. This version is used
1048 when we do not want to automatically collect constructors based on
1049 the symbol name, presumably because we have some other mechanism
1050 for finding them. */
1053 generic_link_check_archive_element_no_collect (bfd *abfd,
1054 struct bfd_link_info *info,
1055 struct bfd_link_hash_entry *h,
1057 bfd_boolean *pneeded)
1059 return generic_link_check_archive_element (abfd, info, h, name, pneeded,
1063 /* See if we should include an archive element. This version is used
1064 when we want to automatically collect constructors based on the
1065 symbol name, as collect2 does. */
1068 generic_link_check_archive_element_collect (bfd *abfd,
1069 struct bfd_link_info *info,
1070 struct bfd_link_hash_entry *h,
1072 bfd_boolean *pneeded)
1074 return generic_link_check_archive_element (abfd, info, h, name, pneeded,
1078 /* See if we should include an archive element. Optionally collect
1082 generic_link_check_archive_element (bfd *abfd,
1083 struct bfd_link_info *info,
1084 struct bfd_link_hash_entry *h,
1085 const char *name ATTRIBUTE_UNUSED,
1086 bfd_boolean *pneeded,
1087 bfd_boolean collect)
1089 asymbol **pp, **ppend;
1093 if (!bfd_generic_link_read_symbols (abfd))
1096 pp = _bfd_generic_link_get_symbols (abfd);
1097 ppend = pp + _bfd_generic_link_get_symcount (abfd);
1098 for (; pp < ppend; pp++)
1104 /* We are only interested in globally visible symbols. */
1105 if (! bfd_is_com_section (p->section)
1106 && (p->flags & (BSF_GLOBAL | BSF_INDIRECT | BSF_WEAK)) == 0)
1109 /* We are only interested if we know something about this
1110 symbol, and it is undefined or common. An undefined weak
1111 symbol (type bfd_link_hash_undefweak) is not considered to be
1112 a reference when pulling files out of an archive. See the
1113 SVR4 ABI, p. 4-27. */
1114 h = bfd_link_hash_lookup (info->hash, bfd_asymbol_name (p), FALSE,
1117 || (h->type != bfd_link_hash_undefined
1118 && h->type != bfd_link_hash_common))
1121 /* P is a symbol we are looking for. */
1123 if (! bfd_is_com_section (p->section)
1124 || (h->type == bfd_link_hash_undefined
1125 && h->u.undef.abfd == NULL))
1127 /* P is not a common symbol, or an undefined reference was
1128 created from outside BFD such as from a linker -u option.
1129 This object file defines the symbol, so pull it in. */
1131 if (!(*info->callbacks
1132 ->add_archive_element) (info, abfd, bfd_asymbol_name (p),
1135 /* Potentially, the add_archive_element hook may have set a
1136 substitute BFD for us. */
1137 return generic_link_add_object_symbols (abfd, info, collect);
1140 /* P is a common symbol. */
1142 if (h->type == bfd_link_hash_undefined)
1148 /* Turn the symbol into a common symbol but do not link in
1149 the object file. This is how a.out works. Object
1150 formats that require different semantics must implement
1151 this function differently. This symbol is already on the
1152 undefs list. We add the section to a common section
1153 attached to symbfd to ensure that it is in a BFD which
1154 will be linked in. */
1155 symbfd = h->u.undef.abfd;
1156 h->type = bfd_link_hash_common;
1157 h->u.c.p = (struct bfd_link_hash_common_entry *)
1158 bfd_hash_allocate (&info->hash->table,
1159 sizeof (struct bfd_link_hash_common_entry));
1160 if (h->u.c.p == NULL)
1163 size = bfd_asymbol_value (p);
1166 power = bfd_log2 (size);
1169 h->u.c.p->alignment_power = power;
1171 if (p->section == bfd_com_section_ptr)
1172 h->u.c.p->section = bfd_make_section_old_way (symbfd, "COMMON");
1174 h->u.c.p->section = bfd_make_section_old_way (symbfd,
1176 h->u.c.p->section->flags |= SEC_ALLOC;
1180 /* Adjust the size of the common symbol if necessary. This
1181 is how a.out works. Object formats that require
1182 different semantics must implement this function
1184 if (bfd_asymbol_value (p) > h->u.c.size)
1185 h->u.c.size = bfd_asymbol_value (p);
1189 /* This archive element is not needed. */
1193 /* Add the symbols from an object file to the global hash table. ABFD
1194 is the object file. INFO is the linker information. SYMBOL_COUNT
1195 is the number of symbols. SYMBOLS is the list of symbols. COLLECT
1196 is TRUE if constructors should be automatically collected by name
1197 as is done by collect2. */
1200 generic_link_add_symbol_list (bfd *abfd,
1201 struct bfd_link_info *info,
1202 bfd_size_type symbol_count,
1204 bfd_boolean collect)
1206 asymbol **pp, **ppend;
1209 ppend = symbols + symbol_count;
1210 for (; pp < ppend; pp++)
1216 if ((p->flags & (BSF_INDIRECT
1221 || bfd_is_und_section (bfd_get_section (p))
1222 || bfd_is_com_section (bfd_get_section (p))
1223 || bfd_is_ind_section (bfd_get_section (p)))
1227 struct generic_link_hash_entry *h;
1228 struct bfd_link_hash_entry *bh;
1230 string = name = bfd_asymbol_name (p);
1231 if (((p->flags & BSF_INDIRECT) != 0
1232 || bfd_is_ind_section (p->section))
1236 string = bfd_asymbol_name (*pp);
1238 else if ((p->flags & BSF_WARNING) != 0
1241 /* The name of P is actually the warning string, and the
1242 next symbol is the one to warn about. */
1244 name = bfd_asymbol_name (*pp);
1248 if (! (_bfd_generic_link_add_one_symbol
1249 (info, abfd, name, p->flags, bfd_get_section (p),
1250 p->value, string, FALSE, collect, &bh)))
1252 h = (struct generic_link_hash_entry *) bh;
1254 /* If this is a constructor symbol, and the linker didn't do
1255 anything with it, then we want to just pass the symbol
1256 through to the output file. This will happen when
1258 if ((p->flags & BSF_CONSTRUCTOR) != 0
1259 && (h == NULL || h->root.type == bfd_link_hash_new))
1265 /* Save the BFD symbol so that we don't lose any backend
1266 specific information that may be attached to it. We only
1267 want this one if it gives more information than the
1268 existing one; we don't want to replace a defined symbol
1269 with an undefined one. This routine may be called with a
1270 hash table other than the generic hash table, so we only
1271 do this if we are certain that the hash table is a
1273 if (info->output_bfd->xvec == abfd->xvec)
1276 || (! bfd_is_und_section (bfd_get_section (p))
1277 && (! bfd_is_com_section (bfd_get_section (p))
1278 || bfd_is_und_section (bfd_get_section (h->sym)))))
1281 /* BSF_OLD_COMMON is a hack to support COFF reloc
1282 reading, and it should go away when the COFF
1283 linker is switched to the new version. */
1284 if (bfd_is_com_section (bfd_get_section (p)))
1285 p->flags |= BSF_OLD_COMMON;
1289 /* Store a back pointer from the symbol to the hash
1290 table entry for the benefit of relaxation code until
1291 it gets rewritten to not use asymbol structures.
1292 Setting this is also used to check whether these
1293 symbols were set up by the generic linker. */
1301 /* We use a state table to deal with adding symbols from an object
1302 file. The first index into the state table describes the symbol
1303 from the object file. The second index into the state table is the
1304 type of the symbol in the hash table. */
1306 /* The symbol from the object file is turned into one of these row
1311 UNDEF_ROW, /* Undefined. */
1312 UNDEFW_ROW, /* Weak undefined. */
1313 DEF_ROW, /* Defined. */
1314 DEFW_ROW, /* Weak defined. */
1315 COMMON_ROW, /* Common. */
1316 INDR_ROW, /* Indirect. */
1317 WARN_ROW, /* Warning. */
1318 SET_ROW /* Member of set. */
1321 /* apparently needed for Hitachi 3050R(HI-UX/WE2)? */
1324 /* The actions to take in the state table. */
1329 UND, /* Mark symbol undefined. */
1330 WEAK, /* Mark symbol weak undefined. */
1331 DEF, /* Mark symbol defined. */
1332 DEFW, /* Mark symbol weak defined. */
1333 COM, /* Mark symbol common. */
1334 REF, /* Mark defined symbol referenced. */
1335 CREF, /* Possibly warn about common reference to defined symbol. */
1336 CDEF, /* Define existing common symbol. */
1337 NOACT, /* No action. */
1338 BIG, /* Mark symbol common using largest size. */
1339 MDEF, /* Multiple definition error. */
1340 MIND, /* Multiple indirect symbols. */
1341 IND, /* Make indirect symbol. */
1342 CIND, /* Make indirect symbol from existing common symbol. */
1343 SET, /* Add value to set. */
1344 MWARN, /* Make warning symbol. */
1345 WARN, /* Warn if referenced, else MWARN. */
1346 CYCLE, /* Repeat with symbol pointed to. */
1347 REFC, /* Mark indirect symbol referenced and then CYCLE. */
1348 WARNC /* Issue warning and then CYCLE. */
1351 /* The state table itself. The first index is a link_row and the
1352 second index is a bfd_link_hash_type. */
1354 static const enum link_action link_action[8][8] =
1356 /* current\prev new undef undefw def defw com indr warn */
1357 /* UNDEF_ROW */ {UND, NOACT, UND, REF, REF, NOACT, REFC, WARNC },
1358 /* UNDEFW_ROW */ {WEAK, NOACT, NOACT, REF, REF, NOACT, REFC, WARNC },
1359 /* DEF_ROW */ {DEF, DEF, DEF, MDEF, DEF, CDEF, MDEF, CYCLE },
1360 /* DEFW_ROW */ {DEFW, DEFW, DEFW, NOACT, NOACT, NOACT, NOACT, CYCLE },
1361 /* COMMON_ROW */ {COM, COM, COM, CREF, COM, BIG, REFC, WARNC },
1362 /* INDR_ROW */ {IND, IND, IND, MDEF, IND, CIND, MIND, CYCLE },
1363 /* WARN_ROW */ {MWARN, WARN, WARN, WARN, WARN, WARN, WARN, NOACT },
1364 /* SET_ROW */ {SET, SET, SET, SET, SET, SET, CYCLE, CYCLE }
1367 /* Most of the entries in the LINK_ACTION table are straightforward,
1368 but a few are somewhat subtle.
1370 A reference to an indirect symbol (UNDEF_ROW/indr or
1371 UNDEFW_ROW/indr) is counted as a reference both to the indirect
1372 symbol and to the symbol the indirect symbol points to.
1374 A reference to a warning symbol (UNDEF_ROW/warn or UNDEFW_ROW/warn)
1375 causes the warning to be issued.
1377 A common definition of an indirect symbol (COMMON_ROW/indr) is
1378 treated as a multiple definition error. Likewise for an indirect
1379 definition of a common symbol (INDR_ROW/com).
1381 An indirect definition of a warning (INDR_ROW/warn) does not cause
1382 the warning to be issued.
1384 If a warning is created for an indirect symbol (WARN_ROW/indr) no
1385 warning is created for the symbol the indirect symbol points to.
1387 Adding an entry to a set does not count as a reference to a set,
1388 and no warning is issued (SET_ROW/warn). */
1390 /* Return the BFD in which a hash entry has been defined, if known. */
1393 hash_entry_bfd (struct bfd_link_hash_entry *h)
1395 while (h->type == bfd_link_hash_warning)
1401 case bfd_link_hash_undefined:
1402 case bfd_link_hash_undefweak:
1403 return h->u.undef.abfd;
1404 case bfd_link_hash_defined:
1405 case bfd_link_hash_defweak:
1406 return h->u.def.section->owner;
1407 case bfd_link_hash_common:
1408 return h->u.c.p->section->owner;
1413 /* Add a symbol to the global hash table.
1414 ABFD is the BFD the symbol comes from.
1415 NAME is the name of the symbol.
1416 FLAGS is the BSF_* bits associated with the symbol.
1417 SECTION is the section in which the symbol is defined; this may be
1418 bfd_und_section_ptr or bfd_com_section_ptr.
1419 VALUE is the value of the symbol, relative to the section.
1420 STRING is used for either an indirect symbol, in which case it is
1421 the name of the symbol to indirect to, or a warning symbol, in
1422 which case it is the warning string.
1423 COPY is TRUE if NAME or STRING must be copied into locally
1424 allocated memory if they need to be saved.
1425 COLLECT is TRUE if we should automatically collect gcc constructor
1426 or destructor names as collect2 does.
1427 HASHP, if not NULL, is a place to store the created hash table
1428 entry; if *HASHP is not NULL, the caller has already looked up
1429 the hash table entry, and stored it in *HASHP. */
1432 _bfd_generic_link_add_one_symbol (struct bfd_link_info *info,
1440 bfd_boolean collect,
1441 struct bfd_link_hash_entry **hashp)
1444 struct bfd_link_hash_entry *h;
1445 struct bfd_link_hash_entry *inh = NULL;
1448 BFD_ASSERT (section != NULL);
1450 if (bfd_is_ind_section (section)
1451 || (flags & BSF_INDIRECT) != 0)
1454 /* Create the indirect symbol here. This is for the benefit of
1455 the plugin "notice" function.
1456 STRING is the name of the symbol we want to indirect to. */
1457 inh = bfd_wrapped_link_hash_lookup (abfd, info, string, TRUE,
1462 else if ((flags & BSF_WARNING) != 0)
1464 else if ((flags & BSF_CONSTRUCTOR) != 0)
1466 else if (bfd_is_und_section (section))
1468 if ((flags & BSF_WEAK) != 0)
1473 else if ((flags & BSF_WEAK) != 0)
1475 else if (bfd_is_com_section (section))
1478 if (!bfd_link_relocatable (info)
1479 && strcmp (name, "__gnu_lto_slim") == 0)
1480 (*_bfd_error_handler)
1481 (_("%s: plugin needed to handle lto object"),
1482 bfd_get_filename (abfd));
1487 if (hashp != NULL && *hashp != NULL)
1491 if (row == UNDEF_ROW || row == UNDEFW_ROW)
1492 h = bfd_wrapped_link_hash_lookup (abfd, info, name, TRUE, copy, FALSE);
1494 h = bfd_link_hash_lookup (info->hash, name, TRUE, copy, FALSE);
1503 if (info->notice_all
1504 || (info->notice_hash != NULL
1505 && bfd_hash_lookup (info->notice_hash, name, FALSE, FALSE) != NULL))
1507 if (! (*info->callbacks->notice) (info, h, inh,
1508 abfd, section, value, flags))
1517 enum link_action action;
1520 action = link_action[(int) row][(int) h->type];
1531 /* Make a new undefined symbol. */
1532 h->type = bfd_link_hash_undefined;
1533 h->u.undef.abfd = abfd;
1534 bfd_link_add_undef (info->hash, h);
1538 /* Make a new weak undefined symbol. */
1539 h->type = bfd_link_hash_undefweak;
1540 h->u.undef.abfd = abfd;
1544 /* We have found a definition for a symbol which was
1545 previously common. */
1546 BFD_ASSERT (h->type == bfd_link_hash_common);
1547 if (! ((*info->callbacks->multiple_common)
1548 (info, h, abfd, bfd_link_hash_defined, 0)))
1554 enum bfd_link_hash_type oldtype;
1556 /* Define a symbol. */
1559 h->type = bfd_link_hash_defweak;
1561 h->type = bfd_link_hash_defined;
1562 h->u.def.section = section;
1563 h->u.def.value = value;
1566 /* If we have been asked to, we act like collect2 and
1567 identify all functions that might be global
1568 constructors and destructors and pass them up in a
1569 callback. We only do this for certain object file
1570 types, since many object file types can handle this
1572 if (collect && name[0] == '_')
1576 /* A constructor or destructor name starts like this:
1577 _+GLOBAL_[_.$][ID][_.$] where the first [_.$] and
1578 the second are the same character (we accept any
1579 character there, in case a new object file format
1580 comes along with even worse naming restrictions). */
1582 #define CONS_PREFIX "GLOBAL_"
1583 #define CONS_PREFIX_LEN (sizeof CONS_PREFIX - 1)
1588 if (s[0] == 'G' && CONST_STRNEQ (s, CONS_PREFIX))
1592 c = s[CONS_PREFIX_LEN + 1];
1593 if ((c == 'I' || c == 'D')
1594 && s[CONS_PREFIX_LEN] == s[CONS_PREFIX_LEN + 2])
1596 /* If this is a definition of a symbol which
1597 was previously weakly defined, we are in
1598 trouble. We have already added a
1599 constructor entry for the weak defined
1600 symbol, and now we are trying to add one
1601 for the new symbol. Fortunately, this case
1602 should never arise in practice. */
1603 if (oldtype == bfd_link_hash_defweak)
1606 if (! ((*info->callbacks->constructor)
1608 h->root.string, abfd, section, value)))
1618 /* We have found a common definition for a symbol. */
1619 if (h->type == bfd_link_hash_new)
1620 bfd_link_add_undef (info->hash, h);
1621 h->type = bfd_link_hash_common;
1622 h->u.c.p = (struct bfd_link_hash_common_entry *)
1623 bfd_hash_allocate (&info->hash->table,
1624 sizeof (struct bfd_link_hash_common_entry));
1625 if (h->u.c.p == NULL)
1628 h->u.c.size = value;
1630 /* Select a default alignment based on the size. This may
1631 be overridden by the caller. */
1635 power = bfd_log2 (value);
1638 h->u.c.p->alignment_power = power;
1641 /* The section of a common symbol is only used if the common
1642 symbol is actually allocated. It basically provides a
1643 hook for the linker script to decide which output section
1644 the common symbols should be put in. In most cases, the
1645 section of a common symbol will be bfd_com_section_ptr,
1646 the code here will choose a common symbol section named
1647 "COMMON", and the linker script will contain *(COMMON) in
1648 the appropriate place. A few targets use separate common
1649 sections for small symbols, and they require special
1651 if (section == bfd_com_section_ptr)
1653 h->u.c.p->section = bfd_make_section_old_way (abfd, "COMMON");
1654 h->u.c.p->section->flags |= SEC_ALLOC;
1656 else if (section->owner != abfd)
1658 h->u.c.p->section = bfd_make_section_old_way (abfd,
1660 h->u.c.p->section->flags |= SEC_ALLOC;
1663 h->u.c.p->section = section;
1668 /* A reference to a defined symbol. */
1669 if (h->u.undef.next == NULL && info->hash->undefs_tail != h)
1670 h->u.undef.next = h;
1674 /* We have found a common definition for a symbol which
1675 already had a common definition. Use the maximum of the
1676 two sizes, and use the section required by the larger symbol. */
1677 BFD_ASSERT (h->type == bfd_link_hash_common);
1678 if (! ((*info->callbacks->multiple_common)
1679 (info, h, abfd, bfd_link_hash_common, value)))
1681 if (value > h->u.c.size)
1685 h->u.c.size = value;
1687 /* Select a default alignment based on the size. This may
1688 be overridden by the caller. */
1689 power = bfd_log2 (value);
1692 h->u.c.p->alignment_power = power;
1694 /* Some systems have special treatment for small commons,
1695 hence we want to select the section used by the larger
1696 symbol. This makes sure the symbol does not go in a
1697 small common section if it is now too large. */
1698 if (section == bfd_com_section_ptr)
1701 = bfd_make_section_old_way (abfd, "COMMON");
1702 h->u.c.p->section->flags |= SEC_ALLOC;
1704 else if (section->owner != abfd)
1707 = bfd_make_section_old_way (abfd, section->name);
1708 h->u.c.p->section->flags |= SEC_ALLOC;
1711 h->u.c.p->section = section;
1716 /* We have found a common definition for a symbol which
1717 was already defined. */
1718 if (! ((*info->callbacks->multiple_common)
1719 (info, h, abfd, bfd_link_hash_common, value)))
1724 /* Multiple indirect symbols. This is OK if they both point
1725 to the same symbol. */
1726 if (strcmp (h->u.i.link->root.string, string) == 0)
1730 /* Handle a multiple definition. */
1731 if (! ((*info->callbacks->multiple_definition)
1732 (info, h, abfd, section, value)))
1737 /* Create an indirect symbol from an existing common symbol. */
1738 BFD_ASSERT (h->type == bfd_link_hash_common);
1739 if (! ((*info->callbacks->multiple_common)
1740 (info, h, abfd, bfd_link_hash_indirect, 0)))
1744 if (inh->type == bfd_link_hash_indirect
1745 && inh->u.i.link == h)
1747 (*_bfd_error_handler)
1748 (_("%B: indirect symbol `%s' to `%s' is a loop"),
1749 abfd, name, string);
1750 bfd_set_error (bfd_error_invalid_operation);
1753 if (inh->type == bfd_link_hash_new)
1755 inh->type = bfd_link_hash_undefined;
1756 inh->u.undef.abfd = abfd;
1757 bfd_link_add_undef (info->hash, inh);
1760 /* If the indirect symbol has been referenced, we need to
1761 push the reference down to the symbol we are referencing. */
1762 if (h->type != bfd_link_hash_new)
1764 /* ??? If inh->type == bfd_link_hash_undefweak this
1765 converts inh to bfd_link_hash_undefined. */
1770 h->type = bfd_link_hash_indirect;
1772 /* Not setting h = h->u.i.link here means that when cycle is
1773 set above we'll always go to REFC, and then cycle again
1774 to the indirected symbol. This means that any successful
1775 change of an existing symbol to indirect counts as a
1776 reference. ??? That may not be correct when the existing
1777 symbol was defweak. */
1781 /* Add an entry to a set. */
1782 if (! (*info->callbacks->add_to_set) (info, h, BFD_RELOC_CTOR,
1783 abfd, section, value))
1788 /* Issue a warning and cycle, except when the reference is
1790 if (h->u.i.warning != NULL
1791 && (abfd->flags & BFD_PLUGIN) == 0)
1793 if (! (*info->callbacks->warning) (info, h->u.i.warning,
1794 h->root.string, abfd,
1797 /* Only issue a warning once. */
1798 h->u.i.warning = NULL;
1802 /* Try again with the referenced symbol. */
1808 /* A reference to an indirect symbol. */
1809 if (h->u.undef.next == NULL && info->hash->undefs_tail != h)
1810 h->u.undef.next = h;
1816 /* Warn if this symbol has been referenced already from non-IR,
1817 otherwise add a warning. */
1818 if ((!info->lto_plugin_active
1819 && (h->u.undef.next != NULL || info->hash->undefs_tail == h))
1822 if (! (*info->callbacks->warning) (info, string, h->root.string,
1823 hash_entry_bfd (h), NULL, 0))
1829 /* Make a warning symbol. */
1831 struct bfd_link_hash_entry *sub;
1833 /* STRING is the warning to give. */
1834 sub = ((struct bfd_link_hash_entry *)
1835 ((*info->hash->table.newfunc)
1836 (NULL, &info->hash->table, h->root.string)));
1840 sub->type = bfd_link_hash_warning;
1843 sub->u.i.warning = string;
1847 size_t len = strlen (string) + 1;
1849 w = (char *) bfd_hash_allocate (&info->hash->table, len);
1852 memcpy (w, string, len);
1853 sub->u.i.warning = w;
1856 bfd_hash_replace (&info->hash->table,
1857 (struct bfd_hash_entry *) h,
1858 (struct bfd_hash_entry *) sub);
1870 /* Generic final link routine. */
1873 _bfd_generic_final_link (bfd *abfd, struct bfd_link_info *info)
1877 struct bfd_link_order *p;
1879 struct generic_write_global_symbol_info wginfo;
1881 bfd_get_outsymbols (abfd) = NULL;
1882 bfd_get_symcount (abfd) = 0;
1885 /* Mark all sections which will be included in the output file. */
1886 for (o = abfd->sections; o != NULL; o = o->next)
1887 for (p = o->map_head.link_order; p != NULL; p = p->next)
1888 if (p->type == bfd_indirect_link_order)
1889 p->u.indirect.section->linker_mark = TRUE;
1891 /* Build the output symbol table. */
1892 for (sub = info->input_bfds; sub != NULL; sub = sub->link.next)
1893 if (! _bfd_generic_link_output_symbols (abfd, sub, info, &outsymalloc))
1896 /* Accumulate the global symbols. */
1898 wginfo.output_bfd = abfd;
1899 wginfo.psymalloc = &outsymalloc;
1900 _bfd_generic_link_hash_traverse (_bfd_generic_hash_table (info),
1901 _bfd_generic_link_write_global_symbol,
1904 /* Make sure we have a trailing NULL pointer on OUTSYMBOLS. We
1905 shouldn't really need one, since we have SYMCOUNT, but some old
1906 code still expects one. */
1907 if (! generic_add_output_symbol (abfd, &outsymalloc, NULL))
1910 if (bfd_link_relocatable (info))
1912 /* Allocate space for the output relocs for each section. */
1913 for (o = abfd->sections; o != NULL; o = o->next)
1916 for (p = o->map_head.link_order; p != NULL; p = p->next)
1918 if (p->type == bfd_section_reloc_link_order
1919 || p->type == bfd_symbol_reloc_link_order)
1921 else if (p->type == bfd_indirect_link_order)
1923 asection *input_section;
1930 input_section = p->u.indirect.section;
1931 input_bfd = input_section->owner;
1932 relsize = bfd_get_reloc_upper_bound (input_bfd,
1936 relocs = (arelent **) bfd_malloc (relsize);
1937 if (!relocs && relsize != 0)
1939 symbols = _bfd_generic_link_get_symbols (input_bfd);
1940 reloc_count = bfd_canonicalize_reloc (input_bfd,
1945 if (reloc_count < 0)
1947 BFD_ASSERT ((unsigned long) reloc_count
1948 == input_section->reloc_count);
1949 o->reloc_count += reloc_count;
1952 if (o->reloc_count > 0)
1956 amt = o->reloc_count;
1957 amt *= sizeof (arelent *);
1958 o->orelocation = (struct reloc_cache_entry **) bfd_alloc (abfd, amt);
1959 if (!o->orelocation)
1961 o->flags |= SEC_RELOC;
1962 /* Reset the count so that it can be used as an index
1963 when putting in the output relocs. */
1969 /* Handle all the link order information for the sections. */
1970 for (o = abfd->sections; o != NULL; o = o->next)
1972 for (p = o->map_head.link_order; p != NULL; p = p->next)
1976 case bfd_section_reloc_link_order:
1977 case bfd_symbol_reloc_link_order:
1978 if (! _bfd_generic_reloc_link_order (abfd, info, o, p))
1981 case bfd_indirect_link_order:
1982 if (! default_indirect_link_order (abfd, info, o, p, TRUE))
1986 if (! _bfd_default_link_order (abfd, info, o, p))
1996 /* Add an output symbol to the output BFD. */
1999 generic_add_output_symbol (bfd *output_bfd, size_t *psymalloc, asymbol *sym)
2001 if (bfd_get_symcount (output_bfd) >= *psymalloc)
2006 if (*psymalloc == 0)
2011 amt *= sizeof (asymbol *);
2012 newsyms = (asymbol **) bfd_realloc (bfd_get_outsymbols (output_bfd), amt);
2013 if (newsyms == NULL)
2015 bfd_get_outsymbols (output_bfd) = newsyms;
2018 bfd_get_outsymbols (output_bfd) [bfd_get_symcount (output_bfd)] = sym;
2020 ++ bfd_get_symcount (output_bfd);
2025 /* Handle the symbols for an input BFD. */
2028 _bfd_generic_link_output_symbols (bfd *output_bfd,
2030 struct bfd_link_info *info,
2036 if (!bfd_generic_link_read_symbols (input_bfd))
2039 /* Create a filename symbol if we are supposed to. */
2040 if (info->create_object_symbols_section != NULL)
2044 for (sec = input_bfd->sections; sec != NULL; sec = sec->next)
2046 if (sec->output_section == info->create_object_symbols_section)
2050 newsym = bfd_make_empty_symbol (input_bfd);
2053 newsym->name = input_bfd->filename;
2055 newsym->flags = BSF_LOCAL | BSF_FILE;
2056 newsym->section = sec;
2058 if (! generic_add_output_symbol (output_bfd, psymalloc,
2067 /* Adjust the values of the globally visible symbols, and write out
2069 sym_ptr = _bfd_generic_link_get_symbols (input_bfd);
2070 sym_end = sym_ptr + _bfd_generic_link_get_symcount (input_bfd);
2071 for (; sym_ptr < sym_end; sym_ptr++)
2074 struct generic_link_hash_entry *h;
2079 if ((sym->flags & (BSF_INDIRECT
2084 || bfd_is_und_section (bfd_get_section (sym))
2085 || bfd_is_com_section (bfd_get_section (sym))
2086 || bfd_is_ind_section (bfd_get_section (sym)))
2088 if (sym->udata.p != NULL)
2089 h = (struct generic_link_hash_entry *) sym->udata.p;
2090 else if ((sym->flags & BSF_CONSTRUCTOR) != 0)
2092 /* This case normally means that the main linker code
2093 deliberately ignored this constructor symbol. We
2094 should just pass it through. This will screw up if
2095 the constructor symbol is from a different,
2096 non-generic, object file format, but the case will
2097 only arise when linking with -r, which will probably
2098 fail anyhow, since there will be no way to represent
2099 the relocs in the output format being used. */
2102 else if (bfd_is_und_section (bfd_get_section (sym)))
2103 h = ((struct generic_link_hash_entry *)
2104 bfd_wrapped_link_hash_lookup (output_bfd, info,
2105 bfd_asymbol_name (sym),
2106 FALSE, FALSE, TRUE));
2108 h = _bfd_generic_link_hash_lookup (_bfd_generic_hash_table (info),
2109 bfd_asymbol_name (sym),
2110 FALSE, FALSE, TRUE);
2114 /* Force all references to this symbol to point to
2115 the same area in memory. It is possible that
2116 this routine will be called with a hash table
2117 other than a generic hash table, so we double
2119 if (info->output_bfd->xvec == input_bfd->xvec)
2122 *sym_ptr = sym = h->sym;
2125 switch (h->root.type)
2128 case bfd_link_hash_new:
2130 case bfd_link_hash_undefined:
2132 case bfd_link_hash_undefweak:
2133 sym->flags |= BSF_WEAK;
2135 case bfd_link_hash_indirect:
2136 h = (struct generic_link_hash_entry *) h->root.u.i.link;
2138 case bfd_link_hash_defined:
2139 sym->flags |= BSF_GLOBAL;
2140 sym->flags &=~ (BSF_WEAK | BSF_CONSTRUCTOR);
2141 sym->value = h->root.u.def.value;
2142 sym->section = h->root.u.def.section;
2144 case bfd_link_hash_defweak:
2145 sym->flags |= BSF_WEAK;
2146 sym->flags &=~ BSF_CONSTRUCTOR;
2147 sym->value = h->root.u.def.value;
2148 sym->section = h->root.u.def.section;
2150 case bfd_link_hash_common:
2151 sym->value = h->root.u.c.size;
2152 sym->flags |= BSF_GLOBAL;
2153 if (! bfd_is_com_section (sym->section))
2155 BFD_ASSERT (bfd_is_und_section (sym->section));
2156 sym->section = bfd_com_section_ptr;
2158 /* We do not set the section of the symbol to
2159 h->root.u.c.p->section. That value was saved so
2160 that we would know where to allocate the symbol
2161 if it was defined. In this case the type is
2162 still bfd_link_hash_common, so we did not define
2163 it, so we do not want to use that section. */
2169 /* This switch is straight from the old code in
2170 write_file_locals in ldsym.c. */
2171 if (info->strip == strip_all
2172 || (info->strip == strip_some
2173 && bfd_hash_lookup (info->keep_hash, bfd_asymbol_name (sym),
2174 FALSE, FALSE) == NULL))
2176 else if ((sym->flags & (BSF_GLOBAL | BSF_WEAK)) != 0)
2178 /* If this symbol is marked as occurring now, rather
2179 than at the end, output it now. This is used for
2180 COFF C_EXT FCN symbols. FIXME: There must be a
2182 if (bfd_asymbol_bfd (sym) == input_bfd
2183 && (sym->flags & BSF_NOT_AT_END) != 0)
2188 else if (bfd_is_ind_section (sym->section))
2190 else if ((sym->flags & BSF_DEBUGGING) != 0)
2192 if (info->strip == strip_none)
2197 else if (bfd_is_und_section (sym->section)
2198 || bfd_is_com_section (sym->section))
2200 else if ((sym->flags & BSF_LOCAL) != 0)
2202 if ((sym->flags & BSF_WARNING) != 0)
2206 switch (info->discard)
2212 case discard_sec_merge:
2214 if (bfd_link_relocatable (info)
2215 || ! (sym->section->flags & SEC_MERGE))
2219 if (bfd_is_local_label (input_bfd, sym))
2230 else if ((sym->flags & BSF_CONSTRUCTOR))
2232 if (info->strip != strip_all)
2237 else if (sym->flags == 0
2238 && (sym->section->owner->flags & BFD_PLUGIN) != 0)
2239 /* LTO doesn't set symbol information. We get here with the
2240 generic linker for a symbol that was "common" but no longer
2241 needs to be global. */
2246 /* If this symbol is in a section which is not being included
2247 in the output file, then we don't want to output the
2249 if (!bfd_is_abs_section (sym->section)
2250 && bfd_section_removed_from_list (output_bfd,
2251 sym->section->output_section))
2256 if (! generic_add_output_symbol (output_bfd, psymalloc, sym))
2266 /* Set the section and value of a generic BFD symbol based on a linker
2267 hash table entry. */
2270 set_symbol_from_hash (asymbol *sym, struct bfd_link_hash_entry *h)
2277 case bfd_link_hash_new:
2278 /* This can happen when a constructor symbol is seen but we are
2279 not building constructors. */
2280 if (sym->section != NULL)
2282 BFD_ASSERT ((sym->flags & BSF_CONSTRUCTOR) != 0);
2286 sym->flags |= BSF_CONSTRUCTOR;
2287 sym->section = bfd_abs_section_ptr;
2291 case bfd_link_hash_undefined:
2292 sym->section = bfd_und_section_ptr;
2295 case bfd_link_hash_undefweak:
2296 sym->section = bfd_und_section_ptr;
2298 sym->flags |= BSF_WEAK;
2300 case bfd_link_hash_defined:
2301 sym->section = h->u.def.section;
2302 sym->value = h->u.def.value;
2304 case bfd_link_hash_defweak:
2305 sym->flags |= BSF_WEAK;
2306 sym->section = h->u.def.section;
2307 sym->value = h->u.def.value;
2309 case bfd_link_hash_common:
2310 sym->value = h->u.c.size;
2311 if (sym->section == NULL)
2312 sym->section = bfd_com_section_ptr;
2313 else if (! bfd_is_com_section (sym->section))
2315 BFD_ASSERT (bfd_is_und_section (sym->section));
2316 sym->section = bfd_com_section_ptr;
2318 /* Do not set the section; see _bfd_generic_link_output_symbols. */
2320 case bfd_link_hash_indirect:
2321 case bfd_link_hash_warning:
2322 /* FIXME: What should we do here? */
2327 /* Write out a global symbol, if it hasn't already been written out.
2328 This is called for each symbol in the hash table. */
2331 _bfd_generic_link_write_global_symbol (struct generic_link_hash_entry *h,
2334 struct generic_write_global_symbol_info *wginfo =
2335 (struct generic_write_global_symbol_info *) data;
2343 if (wginfo->info->strip == strip_all
2344 || (wginfo->info->strip == strip_some
2345 && bfd_hash_lookup (wginfo->info->keep_hash, h->root.root.string,
2346 FALSE, FALSE) == NULL))
2353 sym = bfd_make_empty_symbol (wginfo->output_bfd);
2356 sym->name = h->root.root.string;
2360 set_symbol_from_hash (sym, &h->root);
2362 sym->flags |= BSF_GLOBAL;
2364 if (! generic_add_output_symbol (wginfo->output_bfd, wginfo->psymalloc,
2367 /* FIXME: No way to return failure. */
2374 /* Create a relocation. */
2377 _bfd_generic_reloc_link_order (bfd *abfd,
2378 struct bfd_link_info *info,
2380 struct bfd_link_order *link_order)
2384 if (! bfd_link_relocatable (info))
2386 if (sec->orelocation == NULL)
2389 r = (arelent *) bfd_alloc (abfd, sizeof (arelent));
2393 r->address = link_order->offset;
2394 r->howto = bfd_reloc_type_lookup (abfd, link_order->u.reloc.p->reloc);
2397 bfd_set_error (bfd_error_bad_value);
2401 /* Get the symbol to use for the relocation. */
2402 if (link_order->type == bfd_section_reloc_link_order)
2403 r->sym_ptr_ptr = link_order->u.reloc.p->u.section->symbol_ptr_ptr;
2406 struct generic_link_hash_entry *h;
2408 h = ((struct generic_link_hash_entry *)
2409 bfd_wrapped_link_hash_lookup (abfd, info,
2410 link_order->u.reloc.p->u.name,
2411 FALSE, FALSE, TRUE));
2415 if (! ((*info->callbacks->unattached_reloc)
2416 (info, link_order->u.reloc.p->u.name, NULL, NULL, 0)))
2418 bfd_set_error (bfd_error_bad_value);
2421 r->sym_ptr_ptr = &h->sym;
2424 /* If this is an inplace reloc, write the addend to the object file.
2425 Otherwise, store it in the reloc addend. */
2426 if (! r->howto->partial_inplace)
2427 r->addend = link_order->u.reloc.p->addend;
2431 bfd_reloc_status_type rstat;
2436 size = bfd_get_reloc_size (r->howto);
2437 buf = (bfd_byte *) bfd_zmalloc (size);
2438 if (buf == NULL && size != 0)
2440 rstat = _bfd_relocate_contents (r->howto, abfd,
2441 (bfd_vma) link_order->u.reloc.p->addend,
2448 case bfd_reloc_outofrange:
2450 case bfd_reloc_overflow:
2451 if (! ((*info->callbacks->reloc_overflow)
2453 (link_order->type == bfd_section_reloc_link_order
2454 ? bfd_section_name (abfd, link_order->u.reloc.p->u.section)
2455 : link_order->u.reloc.p->u.name),
2456 r->howto->name, link_order->u.reloc.p->addend,
2464 loc = link_order->offset * bfd_octets_per_byte (abfd);
2465 ok = bfd_set_section_contents (abfd, sec, buf, loc, size);
2473 sec->orelocation[sec->reloc_count] = r;
2479 /* Allocate a new link_order for a section. */
2481 struct bfd_link_order *
2482 bfd_new_link_order (bfd *abfd, asection *section)
2484 bfd_size_type amt = sizeof (struct bfd_link_order);
2485 struct bfd_link_order *new_lo;
2487 new_lo = (struct bfd_link_order *) bfd_zalloc (abfd, amt);
2491 new_lo->type = bfd_undefined_link_order;
2493 if (section->map_tail.link_order != NULL)
2494 section->map_tail.link_order->next = new_lo;
2496 section->map_head.link_order = new_lo;
2497 section->map_tail.link_order = new_lo;
2502 /* Default link order processing routine. Note that we can not handle
2503 the reloc_link_order types here, since they depend upon the details
2504 of how the particular backends generates relocs. */
2507 _bfd_default_link_order (bfd *abfd,
2508 struct bfd_link_info *info,
2510 struct bfd_link_order *link_order)
2512 switch (link_order->type)
2514 case bfd_undefined_link_order:
2515 case bfd_section_reloc_link_order:
2516 case bfd_symbol_reloc_link_order:
2519 case bfd_indirect_link_order:
2520 return default_indirect_link_order (abfd, info, sec, link_order,
2522 case bfd_data_link_order:
2523 return default_data_link_order (abfd, info, sec, link_order);
2527 /* Default routine to handle a bfd_data_link_order. */
2530 default_data_link_order (bfd *abfd,
2531 struct bfd_link_info *info ATTRIBUTE_UNUSED,
2533 struct bfd_link_order *link_order)
2541 BFD_ASSERT ((sec->flags & SEC_HAS_CONTENTS) != 0);
2543 size = link_order->size;
2547 fill = link_order->u.data.contents;
2548 fill_size = link_order->u.data.size;
2551 fill = abfd->arch_info->fill (size, bfd_big_endian (abfd),
2552 (sec->flags & SEC_CODE) != 0);
2556 else if (fill_size < size)
2559 fill = (bfd_byte *) bfd_malloc (size);
2564 memset (p, (int) link_order->u.data.contents[0], (size_t) size);
2569 memcpy (p, link_order->u.data.contents, fill_size);
2573 while (size >= fill_size);
2575 memcpy (p, link_order->u.data.contents, (size_t) size);
2576 size = link_order->size;
2580 loc = link_order->offset * bfd_octets_per_byte (abfd);
2581 result = bfd_set_section_contents (abfd, sec, fill, loc, size);
2583 if (fill != link_order->u.data.contents)
2588 /* Default routine to handle a bfd_indirect_link_order. */
2591 default_indirect_link_order (bfd *output_bfd,
2592 struct bfd_link_info *info,
2593 asection *output_section,
2594 struct bfd_link_order *link_order,
2595 bfd_boolean generic_linker)
2597 asection *input_section;
2599 bfd_byte *contents = NULL;
2600 bfd_byte *new_contents;
2601 bfd_size_type sec_size;
2604 BFD_ASSERT ((output_section->flags & SEC_HAS_CONTENTS) != 0);
2606 input_section = link_order->u.indirect.section;
2607 input_bfd = input_section->owner;
2608 if (input_section->size == 0)
2611 BFD_ASSERT (input_section->output_section == output_section);
2612 BFD_ASSERT (input_section->output_offset == link_order->offset);
2613 BFD_ASSERT (input_section->size == link_order->size);
2615 if (bfd_link_relocatable (info)
2616 && input_section->reloc_count > 0
2617 && output_section->orelocation == NULL)
2619 /* Space has not been allocated for the output relocations.
2620 This can happen when we are called by a specific backend
2621 because somebody is attempting to link together different
2622 types of object files. Handling this case correctly is
2623 difficult, and sometimes impossible. */
2624 (*_bfd_error_handler)
2625 (_("Attempt to do relocatable link with %s input and %s output"),
2626 bfd_get_target (input_bfd), bfd_get_target (output_bfd));
2627 bfd_set_error (bfd_error_wrong_format);
2631 if (! generic_linker)
2636 /* Get the canonical symbols. The generic linker will always
2637 have retrieved them by this point, but we are being called by
2638 a specific linker, presumably because we are linking
2639 different types of object files together. */
2640 if (!bfd_generic_link_read_symbols (input_bfd))
2643 /* Since we have been called by a specific linker, rather than
2644 the generic linker, the values of the symbols will not be
2645 right. They will be the values as seen in the input file,
2646 not the values of the final link. We need to fix them up
2647 before we can relocate the section. */
2648 sympp = _bfd_generic_link_get_symbols (input_bfd);
2649 symppend = sympp + _bfd_generic_link_get_symcount (input_bfd);
2650 for (; sympp < symppend; sympp++)
2653 struct bfd_link_hash_entry *h;
2657 if ((sym->flags & (BSF_INDIRECT
2662 || bfd_is_und_section (bfd_get_section (sym))
2663 || bfd_is_com_section (bfd_get_section (sym))
2664 || bfd_is_ind_section (bfd_get_section (sym)))
2666 /* sym->udata may have been set by
2667 generic_link_add_symbol_list. */
2668 if (sym->udata.p != NULL)
2669 h = (struct bfd_link_hash_entry *) sym->udata.p;
2670 else if (bfd_is_und_section (bfd_get_section (sym)))
2671 h = bfd_wrapped_link_hash_lookup (output_bfd, info,
2672 bfd_asymbol_name (sym),
2673 FALSE, FALSE, TRUE);
2675 h = bfd_link_hash_lookup (info->hash,
2676 bfd_asymbol_name (sym),
2677 FALSE, FALSE, TRUE);
2679 set_symbol_from_hash (sym, h);
2684 if ((output_section->flags & (SEC_GROUP | SEC_LINKER_CREATED)) == SEC_GROUP
2685 && input_section->size != 0)
2687 /* Group section contents are set by bfd_elf_set_group_contents. */
2688 if (!output_bfd->output_has_begun)
2690 /* FIXME: This hack ensures bfd_elf_set_group_contents is called. */
2691 if (!bfd_set_section_contents (output_bfd, output_section, "", 0, 1))
2694 new_contents = output_section->contents;
2695 BFD_ASSERT (new_contents != NULL);
2696 BFD_ASSERT (input_section->output_offset == 0);
2700 /* Get and relocate the section contents. */
2701 sec_size = (input_section->rawsize > input_section->size
2702 ? input_section->rawsize
2703 : input_section->size);
2704 contents = (bfd_byte *) bfd_malloc (sec_size);
2705 if (contents == NULL && sec_size != 0)
2707 new_contents = (bfd_get_relocated_section_contents
2708 (output_bfd, info, link_order, contents,
2709 bfd_link_relocatable (info),
2710 _bfd_generic_link_get_symbols (input_bfd)));
2715 /* Output the section contents. */
2716 loc = input_section->output_offset * bfd_octets_per_byte (output_bfd);
2717 if (! bfd_set_section_contents (output_bfd, output_section,
2718 new_contents, loc, input_section->size))
2721 if (contents != NULL)
2726 if (contents != NULL)
2731 /* A little routine to count the number of relocs in a link_order
2735 _bfd_count_link_order_relocs (struct bfd_link_order *link_order)
2737 register unsigned int c;
2738 register struct bfd_link_order *l;
2741 for (l = link_order; l != NULL; l = l->next)
2743 if (l->type == bfd_section_reloc_link_order
2744 || l->type == bfd_symbol_reloc_link_order)
2753 bfd_link_split_section
2756 bfd_boolean bfd_link_split_section (bfd *abfd, asection *sec);
2759 Return nonzero if @var{sec} should be split during a
2760 reloceatable or final link.
2762 .#define bfd_link_split_section(abfd, sec) \
2763 . BFD_SEND (abfd, _bfd_link_split_section, (abfd, sec))
2769 _bfd_generic_link_split_section (bfd *abfd ATTRIBUTE_UNUSED,
2770 asection *sec ATTRIBUTE_UNUSED)
2777 bfd_section_already_linked
2780 bfd_boolean bfd_section_already_linked (bfd *abfd,
2782 struct bfd_link_info *info);
2785 Check if @var{data} has been already linked during a reloceatable
2786 or final link. Return TRUE if it has.
2788 .#define bfd_section_already_linked(abfd, sec, info) \
2789 . BFD_SEND (abfd, _section_already_linked, (abfd, sec, info))
2794 /* Sections marked with the SEC_LINK_ONCE flag should only be linked
2795 once into the output. This routine checks each section, and
2796 arrange to discard it if a section of the same name has already
2797 been linked. This code assumes that all relevant sections have the
2798 SEC_LINK_ONCE flag set; that is, it does not depend solely upon the
2799 section name. bfd_section_already_linked is called via
2800 bfd_map_over_sections. */
2802 /* The hash table. */
2804 static struct bfd_hash_table _bfd_section_already_linked_table;
2806 /* Support routines for the hash table used by section_already_linked,
2807 initialize the table, traverse, lookup, fill in an entry and remove
2811 bfd_section_already_linked_table_traverse
2812 (bfd_boolean (*func) (struct bfd_section_already_linked_hash_entry *,
2813 void *), void *info)
2815 bfd_hash_traverse (&_bfd_section_already_linked_table,
2816 (bfd_boolean (*) (struct bfd_hash_entry *,
2821 struct bfd_section_already_linked_hash_entry *
2822 bfd_section_already_linked_table_lookup (const char *name)
2824 return ((struct bfd_section_already_linked_hash_entry *)
2825 bfd_hash_lookup (&_bfd_section_already_linked_table, name,
2830 bfd_section_already_linked_table_insert
2831 (struct bfd_section_already_linked_hash_entry *already_linked_list,
2834 struct bfd_section_already_linked *l;
2836 /* Allocate the memory from the same obstack as the hash table is
2838 l = (struct bfd_section_already_linked *)
2839 bfd_hash_allocate (&_bfd_section_already_linked_table, sizeof *l);
2843 l->next = already_linked_list->entry;
2844 already_linked_list->entry = l;
2848 static struct bfd_hash_entry *
2849 already_linked_newfunc (struct bfd_hash_entry *entry ATTRIBUTE_UNUSED,
2850 struct bfd_hash_table *table,
2851 const char *string ATTRIBUTE_UNUSED)
2853 struct bfd_section_already_linked_hash_entry *ret =
2854 (struct bfd_section_already_linked_hash_entry *)
2855 bfd_hash_allocate (table, sizeof *ret);
2866 bfd_section_already_linked_table_init (void)
2868 return bfd_hash_table_init_n (&_bfd_section_already_linked_table,
2869 already_linked_newfunc,
2870 sizeof (struct bfd_section_already_linked_hash_entry),
2875 bfd_section_already_linked_table_free (void)
2877 bfd_hash_table_free (&_bfd_section_already_linked_table);
2880 /* Report warnings as appropriate for duplicate section SEC.
2881 Return FALSE if we decide to keep SEC after all. */
2884 _bfd_handle_already_linked (asection *sec,
2885 struct bfd_section_already_linked *l,
2886 struct bfd_link_info *info)
2888 switch (sec->flags & SEC_LINK_DUPLICATES)
2893 case SEC_LINK_DUPLICATES_DISCARD:
2894 /* If we found an LTO IR match for this comdat group on
2895 the first pass, replace it with the LTO output on the
2896 second pass. We can't simply choose real object
2897 files over IR because the first pass may contain a
2898 mix of LTO and normal objects and we must keep the
2899 first match, be it IR or real. */
2900 if (sec->owner->lto_output
2901 && (l->sec->owner->flags & BFD_PLUGIN) != 0)
2908 case SEC_LINK_DUPLICATES_ONE_ONLY:
2909 info->callbacks->einfo
2910 (_("%B: ignoring duplicate section `%A'\n"),
2914 case SEC_LINK_DUPLICATES_SAME_SIZE:
2915 if ((l->sec->owner->flags & BFD_PLUGIN) != 0)
2917 else if (sec->size != l->sec->size)
2918 info->callbacks->einfo
2919 (_("%B: duplicate section `%A' has different size\n"),
2923 case SEC_LINK_DUPLICATES_SAME_CONTENTS:
2924 if ((l->sec->owner->flags & BFD_PLUGIN) != 0)
2926 else if (sec->size != l->sec->size)
2927 info->callbacks->einfo
2928 (_("%B: duplicate section `%A' has different size\n"),
2930 else if (sec->size != 0)
2932 bfd_byte *sec_contents, *l_sec_contents = NULL;
2934 if (!bfd_malloc_and_get_section (sec->owner, sec, &sec_contents))
2935 info->callbacks->einfo
2936 (_("%B: could not read contents of section `%A'\n"),
2938 else if (!bfd_malloc_and_get_section (l->sec->owner, l->sec,
2940 info->callbacks->einfo
2941 (_("%B: could not read contents of section `%A'\n"),
2942 l->sec->owner, l->sec);
2943 else if (memcmp (sec_contents, l_sec_contents, sec->size) != 0)
2944 info->callbacks->einfo
2945 (_("%B: duplicate section `%A' has different contents\n"),
2949 free (sec_contents);
2951 free (l_sec_contents);
2956 /* Set the output_section field so that lang_add_section
2957 does not create a lang_input_section structure for this
2958 section. Since there might be a symbol in the section
2959 being discarded, we must retain a pointer to the section
2960 which we are really going to use. */
2961 sec->output_section = bfd_abs_section_ptr;
2962 sec->kept_section = l->sec;
2966 /* This is used on non-ELF inputs. */
2969 _bfd_generic_section_already_linked (bfd *abfd ATTRIBUTE_UNUSED,
2971 struct bfd_link_info *info)
2974 struct bfd_section_already_linked *l;
2975 struct bfd_section_already_linked_hash_entry *already_linked_list;
2977 if ((sec->flags & SEC_LINK_ONCE) == 0)
2980 /* The generic linker doesn't handle section groups. */
2981 if ((sec->flags & SEC_GROUP) != 0)
2984 /* FIXME: When doing a relocatable link, we may have trouble
2985 copying relocations in other sections that refer to local symbols
2986 in the section being discarded. Those relocations will have to
2987 be converted somehow; as of this writing I'm not sure that any of
2988 the backends handle that correctly.
2990 It is tempting to instead not discard link once sections when
2991 doing a relocatable link (technically, they should be discarded
2992 whenever we are building constructors). However, that fails,
2993 because the linker winds up combining all the link once sections
2994 into a single large link once section, which defeats the purpose
2995 of having link once sections in the first place. */
2997 name = bfd_get_section_name (abfd, sec);
2999 already_linked_list = bfd_section_already_linked_table_lookup (name);
3001 l = already_linked_list->entry;
3004 /* The section has already been linked. See if we should
3006 return _bfd_handle_already_linked (sec, l, info);
3009 /* This is the first section with this name. Record it. */
3010 if (!bfd_section_already_linked_table_insert (already_linked_list, sec))
3011 info->callbacks->einfo (_("%F%P: already_linked_table: %E\n"));
3015 /* Choose a neighbouring section to S in OBFD that will be output, or
3016 the absolute section if ADDR is out of bounds of the neighbours. */
3019 _bfd_nearby_section (bfd *obfd, asection *s, bfd_vma addr)
3021 asection *next, *prev, *best;
3023 /* Find preceding kept section. */
3024 for (prev = s->prev; prev != NULL; prev = prev->prev)
3025 if ((prev->flags & SEC_EXCLUDE) == 0
3026 && !bfd_section_removed_from_list (obfd, prev))
3029 /* Find following kept section. Start at prev->next because
3030 other sections may have been added after S was removed. */
3031 if (s->prev != NULL)
3032 next = s->prev->next;
3034 next = s->owner->sections;
3035 for (; next != NULL; next = next->next)
3036 if ((next->flags & SEC_EXCLUDE) == 0
3037 && !bfd_section_removed_from_list (obfd, next))
3040 /* Choose better of two sections, based on flags. The idea
3041 is to choose a section that will be in the same segment
3042 as S would have been if it was kept. */
3047 best = bfd_abs_section_ptr;
3049 else if (next == NULL)
3051 else if (((prev->flags ^ next->flags)
3052 & (SEC_ALLOC | SEC_THREAD_LOCAL | SEC_LOAD)) != 0)
3054 if (((next->flags ^ s->flags)
3055 & (SEC_ALLOC | SEC_THREAD_LOCAL)) != 0
3056 /* We prefer to choose a loaded section. Section S
3057 doesn't have SEC_LOAD set (it being excluded, that
3058 part of the flag processing didn't happen) so we
3059 can't compare that flag to those of NEXT and PREV. */
3060 || ((prev->flags & SEC_LOAD) != 0
3061 && (next->flags & SEC_LOAD) == 0))
3064 else if (((prev->flags ^ next->flags) & SEC_READONLY) != 0)
3066 if (((next->flags ^ s->flags) & SEC_READONLY) != 0)
3069 else if (((prev->flags ^ next->flags) & SEC_CODE) != 0)
3071 if (((next->flags ^ s->flags) & SEC_CODE) != 0)
3076 /* Flags we care about are the same. Prefer the following
3077 section if that will result in a positive valued sym. */
3078 if (addr < next->vma)
3085 /* Convert symbols in excluded output sections to use a kept section. */
3088 fix_syms (struct bfd_link_hash_entry *h, void *data)
3090 bfd *obfd = (bfd *) data;
3092 if (h->type == bfd_link_hash_defined
3093 || h->type == bfd_link_hash_defweak)
3095 asection *s = h->u.def.section;
3097 && s->output_section != NULL
3098 && (s->output_section->flags & SEC_EXCLUDE) != 0
3099 && bfd_section_removed_from_list (obfd, s->output_section))
3103 h->u.def.value += s->output_offset + s->output_section->vma;
3104 op = _bfd_nearby_section (obfd, s->output_section, h->u.def.value);
3105 h->u.def.value -= op->vma;
3106 h->u.def.section = op;
3114 _bfd_fix_excluded_sec_syms (bfd *obfd, struct bfd_link_info *info)
3116 bfd_link_hash_traverse (info->hash, fix_syms, obfd);
3121 bfd_generic_define_common_symbol
3124 bfd_boolean bfd_generic_define_common_symbol
3125 (bfd *output_bfd, struct bfd_link_info *info,
3126 struct bfd_link_hash_entry *h);
3129 Convert common symbol @var{h} into a defined symbol.
3130 Return TRUE on success and FALSE on failure.
3132 .#define bfd_define_common_symbol(output_bfd, info, h) \
3133 . BFD_SEND (output_bfd, _bfd_define_common_symbol, (output_bfd, info, h))
3138 bfd_generic_define_common_symbol (bfd *output_bfd,
3139 struct bfd_link_info *info ATTRIBUTE_UNUSED,
3140 struct bfd_link_hash_entry *h)
3142 unsigned int power_of_two;
3143 bfd_vma alignment, size;
3146 BFD_ASSERT (h != NULL && h->type == bfd_link_hash_common);
3149 power_of_two = h->u.c.p->alignment_power;
3150 section = h->u.c.p->section;
3152 /* Increase the size of the section to align the common symbol.
3153 The alignment must be a power of two. */
3154 alignment = bfd_octets_per_byte (output_bfd) << power_of_two;
3155 BFD_ASSERT (alignment != 0 && (alignment & -alignment) == alignment);
3156 section->size += alignment - 1;
3157 section->size &= -alignment;
3159 /* Adjust the section's overall alignment if necessary. */
3160 if (power_of_two > section->alignment_power)
3161 section->alignment_power = power_of_two;
3163 /* Change the symbol from common to defined. */
3164 h->type = bfd_link_hash_defined;
3165 h->u.def.section = section;
3166 h->u.def.value = section->size;
3168 /* Increase the size of the section. */
3169 section->size += size;
3171 /* Make sure the section is allocated in memory, and make sure that
3172 it is no longer a common section. */
3173 section->flags |= SEC_ALLOC;
3174 section->flags &= ~SEC_IS_COMMON;
3180 bfd_find_version_for_sym
3183 struct bfd_elf_version_tree * bfd_find_version_for_sym
3184 (struct bfd_elf_version_tree *verdefs,
3185 const char *sym_name, bfd_boolean *hide);
3188 Search an elf version script tree for symbol versioning
3189 info and export / don't-export status for a given symbol.
3190 Return non-NULL on success and NULL on failure; also sets
3191 the output @samp{hide} boolean parameter.
3195 struct bfd_elf_version_tree *
3196 bfd_find_version_for_sym (struct bfd_elf_version_tree *verdefs,
3197 const char *sym_name,
3200 struct bfd_elf_version_tree *t;
3201 struct bfd_elf_version_tree *local_ver, *global_ver, *exist_ver;
3202 struct bfd_elf_version_tree *star_local_ver, *star_global_ver;
3206 star_local_ver = NULL;
3207 star_global_ver = NULL;
3209 for (t = verdefs; t != NULL; t = t->next)
3211 if (t->globals.list != NULL)
3213 struct bfd_elf_version_expr *d = NULL;
3215 while ((d = (*t->match) (&t->globals, d, sym_name)) != NULL)
3217 if (d->literal || strcmp (d->pattern, "*") != 0)
3220 star_global_ver = t;
3224 /* If the match is a wildcard pattern, keep looking for
3225 a more explicit, perhaps even local, match. */
3234 if (t->locals.list != NULL)
3236 struct bfd_elf_version_expr *d = NULL;
3238 while ((d = (*t->match) (&t->locals, d, sym_name)) != NULL)
3240 if (d->literal || strcmp (d->pattern, "*") != 0)
3244 /* If the match is a wildcard pattern, keep looking for
3245 a more explicit, perhaps even global, match. */
3248 /* An exact match overrides a global wildcard. */
3250 star_global_ver = NULL;
3260 if (global_ver == NULL && local_ver == NULL)
3261 global_ver = star_global_ver;
3263 if (global_ver != NULL)
3265 /* If we already have a versioned symbol that matches the
3266 node for this symbol, then we don't want to create a
3267 duplicate from the unversioned symbol. Instead hide the
3268 unversioned symbol. */
3269 *hide = exist_ver == global_ver;
3273 if (local_ver == NULL)
3274 local_ver = star_local_ver;
3276 if (local_ver != NULL)
3287 bfd_hide_sym_by_version
3290 bfd_boolean bfd_hide_sym_by_version
3291 (struct bfd_elf_version_tree *verdefs, const char *sym_name);
3294 Search an elf version script tree for symbol versioning
3295 info for a given symbol. Return TRUE if the symbol is hidden.
3300 bfd_hide_sym_by_version (struct bfd_elf_version_tree *verdefs,
3301 const char *sym_name)
3303 bfd_boolean hidden = FALSE;
3304 bfd_find_version_for_sym (verdefs, sym_name, &hidden);
3310 bfd_link_check_relocs
3313 bfd_boolean bfd_link_check_relocs
3314 (bfd *abfd, struct bfd_link_info *info);
3317 Checks the relocs in ABFD for validity.
3318 Does not execute the relocs.
3319 Return TRUE if everything is OK, FALSE otherwise.
3320 This is the external entry point to this code.
3324 bfd_link_check_relocs (bfd *abfd, struct bfd_link_info *info)
3326 return BFD_SEND (abfd, _bfd_link_check_relocs, (abfd, info));
3331 _bfd_generic_link_check_relocs
3334 bfd_boolean _bfd_generic_link_check_relocs
3335 (bfd *abfd, struct bfd_link_info *info);
3338 Stub function for targets that do not implement reloc checking.
3340 This is an internal function. It should not be called from
3341 outside the BFD library.
3345 _bfd_generic_link_check_relocs (bfd *abfd ATTRIBUTE_UNUSED,
3346 struct bfd_link_info *info ATTRIBUTE_UNUSED)