1 /* Plugin control for the GNU linker.
2 Copyright 2010 Free Software Foundation, Inc.
4 This file is part of the GNU Binutils.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
19 MA 02110-1301, USA. */
22 #include "libiberty.h"
33 #include "plugin-api.h"
35 #if !defined (HAVE_DLFCN_H) && defined (HAVE_WINDOWS_H)
39 /* The suffix to append to the name of the real (claimed) object file
40 when generating a dummy BFD to hold the IR symbols sent from the
42 #define IRONLY_SUFFIX ".ironly\004"
44 /* This is sizeof an array of chars, not sizeof a const char *. We
45 also have to avoid inadvertently counting the trailing NUL. */
46 #define IRONLY_SUFFIX_LEN (sizeof (IRONLY_SUFFIX) - 1)
48 /* Stores a single argument passed to a plugin. */
49 typedef struct plugin_arg
51 struct plugin_arg *next;
55 /* Holds all details of a single plugin. */
58 /* Next on the list of plugins, or NULL at end of chain. */
60 /* The argument string given to --plugin. */
62 /* The shared library handle returned by dlopen. */
64 /* The list of argument string given to --plugin-opt. */
66 /* Number of args in the list, for convenience. */
68 /* The plugin's event handlers. */
69 ld_plugin_claim_file_handler claim_file_handler;
70 ld_plugin_all_symbols_read_handler all_symbols_read_handler;
71 ld_plugin_cleanup_handler cleanup_handler;
72 /* TRUE if the cleanup handlers have been called. */
73 bfd_boolean cleanup_done;
76 /* The master list of all plugins. */
77 static plugin_t *plugins_list = NULL;
79 /* We keep a tail pointer for easy linking on the end. */
80 static plugin_t **plugins_tail_chain_ptr = &plugins_list;
82 /* The last plugin added to the list, for receiving args. */
83 static plugin_t *last_plugin = NULL;
85 /* The tail of the arg chain of the last plugin added to the list. */
86 static plugin_arg_t **last_plugin_args_tail_chain_ptr = NULL;
88 /* The plugin which is currently having a callback executed. */
89 static plugin_t *called_plugin = NULL;
91 /* Last plugin to cause an error, if any. */
92 static const char *error_plugin = NULL;
94 /* A hash table that records symbols referenced by non-IR files. Used
95 at get_symbols time to determine whether any prevailing defs from
96 IR files are referenced only from other IR files, so tthat we can
97 we can distinguish the LDPR_PREVAILING_DEF and LDPR_PREVAILING_DEF_IRONLY
98 cases when establishing symbol resolutions. */
99 static struct bfd_hash_table *non_ironly_hash = NULL;
101 /* Set at all symbols read time, to avoid recursively offering the plugin
102 its own newly-added input files and libs to claim. */
103 static bfd_boolean no_more_claiming = FALSE;
105 /* If the --allow-multiple-definition command-line option is active, we
106 have to disable it so that BFD always calls our hook, and simulate the
107 effect (when not resolving IR vs. real symbols) ourselves by ensuring
108 TRUE is returned from the hook. */
109 static bfd_boolean plugin_cached_allow_multiple_defs = FALSE;
111 /* List of tags to set in the constant leading part of the tv array. */
112 static const enum ld_plugin_tag tv_header_tags[] =
119 LDPT_REGISTER_CLAIM_FILE_HOOK,
120 LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK,
121 LDPT_REGISTER_CLEANUP_HOOK,
124 LDPT_RELEASE_INPUT_FILE,
127 LDPT_ADD_INPUT_LIBRARY,
128 LDPT_SET_EXTRA_LIBRARY_PATH
131 /* How many entries in the constant leading part of the tv array. */
132 static const size_t tv_header_size = ARRAY_SIZE (tv_header_tags);
134 #if !defined (HAVE_DLFCN_H) && defined (HAVE_WINDOWS_H)
136 #define RTLD_NOW 0 /* Dummy value. */
139 dlopen (const char *file, int mode ATTRIBUTE_UNUSED)
141 return LoadLibrary (file);
145 dlsym (void *handle, const char *name)
147 return GetProcAddress (handle, name);
151 dlclose (void *handle)
153 FreeLibrary (handle);
157 #endif /* !defined (HAVE_DLFCN_H) && defined (HAVE_WINDOWS_H) */
159 /* Helper function for exiting with error status. */
161 set_plugin_error (const char *plugin)
163 error_plugin = plugin;
167 /* Test if an error occurred. */
169 plugin_error_p (void)
171 return error_plugin != NULL;
174 /* Return name of plugin which caused an error if any. */
176 plugin_error_plugin (void)
178 return error_plugin ? error_plugin : _("<no plugin>");
181 /* Handle -plugin arg: find and load plugin, or return error. */
183 plugin_opt_plugin (const char *plugin)
187 newplug = xmalloc (sizeof *newplug);
188 memset (newplug, 0, sizeof *newplug);
189 newplug->name = plugin;
190 newplug->dlhandle = dlopen (plugin, RTLD_NOW);
191 if (!newplug->dlhandle)
192 return set_plugin_error (plugin);
194 /* Chain on end, so when we run list it is in command-line order. */
195 *plugins_tail_chain_ptr = newplug;
196 plugins_tail_chain_ptr = &newplug->next;
198 /* Record it as current plugin for receiving args. */
199 last_plugin = newplug;
200 last_plugin_args_tail_chain_ptr = &newplug->args;
204 /* Accumulate option arguments for last-loaded plugin, or return
207 plugin_opt_plugin_arg (const char *arg)
209 plugin_arg_t *newarg;
212 return set_plugin_error (_("<no plugin>"));
214 newarg = xmalloc (sizeof *newarg);
218 /* Chain on end to preserve command-line order. */
219 *last_plugin_args_tail_chain_ptr = newarg;
220 last_plugin_args_tail_chain_ptr = &newarg->next;
221 last_plugin->n_args++;
225 /* Create a dummy BFD. */
227 plugin_get_ir_dummy_bfd (const char *name, bfd *srctemplate)
232 bfd_use_reserved_id = 1;
233 abfd = bfd_create (concat (name, IRONLY_SUFFIX, (const char *)NULL),
235 bfd_set_arch_info (abfd, bfd_get_arch_info (srctemplate));
236 bfd_make_writable (abfd);
237 /* Create a minimal set of sections to own the symbols. */
238 sec = bfd_make_section_old_way (abfd, ".text");
239 bfd_set_section_flags (abfd, sec,
240 (SEC_CODE | SEC_HAS_CONTENTS | SEC_READONLY
241 | SEC_ALLOC | SEC_LOAD | SEC_KEEP));
242 sec->output_section = sec;
243 sec->output_offset = 0;
247 /* Check if the BFD passed in is an IR dummy object file. */
249 is_ir_dummy_bfd (const bfd *abfd)
255 namlen = strlen (abfd->filename);
256 if (namlen < IRONLY_SUFFIX_LEN)
258 return !strcmp (abfd->filename + namlen - IRONLY_SUFFIX_LEN, IRONLY_SUFFIX);
261 /* Helpers to convert between BFD and GOLD symbol formats. */
262 static enum ld_plugin_status
263 asymbol_from_plugin_symbol (bfd *abfd, asymbol *asym,
264 const struct ld_plugin_symbol *ldsym)
266 flagword flags = BSF_NO_FLAGS;
267 struct bfd_section *section;
269 asym->the_bfd = abfd;
270 asym->name = ldsym->version
271 ? concat (ldsym->name, "@", ldsym->version, NULL)
281 section = bfd_get_section_by_name (abfd, ".text");
288 section = bfd_und_section_ptr;
293 section = bfd_com_section_ptr;
294 asym->value = ldsym->size;
301 asym->section = section;
303 /* Visibility only applies on ELF targets. */
304 if (bfd_get_flavour (abfd) == bfd_target_elf_flavour)
306 elf_symbol_type *elfsym = elf_symbol_from (abfd, asym);
308 einfo (_("%P%F: %s: non-ELF symbol in ELF BFD!"), asym->name);
309 elfsym->internal_elf_sym.st_other &= ~3;
310 elfsym->internal_elf_sym.st_other |= ldsym->visibility;
316 /* Register a claim-file handler. */
317 static enum ld_plugin_status
318 register_claim_file (ld_plugin_claim_file_handler handler)
320 ASSERT (called_plugin);
321 called_plugin->claim_file_handler = handler;
325 /* Register an all-symbols-read handler. */
326 static enum ld_plugin_status
327 register_all_symbols_read (ld_plugin_all_symbols_read_handler handler)
329 ASSERT (called_plugin);
330 called_plugin->all_symbols_read_handler = handler;
334 /* Register a cleanup handler. */
335 static enum ld_plugin_status
336 register_cleanup (ld_plugin_cleanup_handler handler)
338 ASSERT (called_plugin);
339 called_plugin->cleanup_handler = handler;
343 /* Add symbols from a plugin-claimed input file. */
344 static enum ld_plugin_status
345 add_symbols (void *handle, int nsyms, const struct ld_plugin_symbol *syms)
350 ASSERT (called_plugin);
351 symptrs = xmalloc (nsyms * sizeof *symptrs);
352 for (n = 0; n < nsyms; n++)
354 enum ld_plugin_status rv;
355 asymbol *bfdsym = bfd_make_empty_symbol (abfd);
357 rv = asymbol_from_plugin_symbol (abfd, bfdsym, syms + n);
361 bfd_set_symtab (abfd, symptrs, nsyms);
365 /* Get the input file information with an open (possibly re-opened)
367 static enum ld_plugin_status
368 get_input_file (const void *handle, struct ld_plugin_input_file *file)
370 ASSERT (called_plugin);
376 /* Release the input file. */
377 static enum ld_plugin_status
378 release_input_file (const void *handle)
380 ASSERT (called_plugin);
385 /* Return TRUE if a defined symbol might be reachable from outside the
386 universe of claimed objects. */
387 static inline bfd_boolean
388 is_visible_from_outside (struct ld_plugin_symbol *lsym, asection *section,
389 struct bfd_link_hash_entry *blhe)
391 /* Section's owner may be NULL if it is the absolute
392 section, fortunately is_ir_dummy_bfd handles that. */
393 if (!is_ir_dummy_bfd (section->owner))
395 if (link_info.relocatable)
397 if (link_info.export_dynamic || link_info.shared)
399 /* Only ELF symbols really have visibility. */
400 if (bfd_get_flavour (link_info.output_bfd) == bfd_target_elf_flavour)
402 struct elf_link_hash_entry *el = (struct elf_link_hash_entry *)blhe;
403 int vis = ELF_ST_VISIBILITY (el->other);
404 return vis == STV_DEFAULT || vis == STV_PROTECTED;
406 /* On non-ELF targets, we can safely make inferences by considering
407 what visibility the plugin would have liked to apply when it first
408 sent us the symbol. During ELF symbol processing, visibility only
409 ever becomes more restrictive, not less, when symbols are merged,
410 so this is a conservative estimate; it may give false positives,
411 declaring something visible from outside when it in fact would
412 not have been, but this will only lead to missed optimisation
413 opportunities during LTRANS at worst; it will not give false
414 negatives, which can lead to the disastrous conclusion that the
415 related symbol is IRONLY. (See GCC PR46319 for an example.) */
416 return lsym->visibility == LDPV_DEFAULT
417 || lsym->visibility == LDPV_PROTECTED;
422 /* Get the symbol resolution info for a plugin-claimed input file. */
423 static enum ld_plugin_status
424 get_symbols (const void *handle, int nsyms, struct ld_plugin_symbol *syms)
426 const bfd *abfd = handle;
428 ASSERT (called_plugin);
429 for (n = 0; n < nsyms; n++)
431 struct bfd_link_hash_entry *blhe;
435 blhe = bfd_link_hash_lookup (link_info.hash, syms[n].name,
439 syms[n].resolution = LDPR_UNKNOWN;
443 /* Determine resolution from blhe type and symbol's original type. */
444 if (blhe->type == bfd_link_hash_undefined
445 || blhe->type == bfd_link_hash_undefweak)
447 syms[n].resolution = LDPR_UNDEF;
450 if (blhe->type != bfd_link_hash_defined
451 && blhe->type != bfd_link_hash_defweak
452 && blhe->type != bfd_link_hash_common)
454 /* We should not have a new, indirect or warning symbol here. */
455 einfo ("%P%F: %s: plugin symbol table corrupt (sym type %d)",
456 called_plugin->name, blhe->type);
459 /* Find out which section owns the symbol. Since it's not undef,
460 it must have an owner; if it's not a common symbol, both defs
461 and weakdefs keep it in the same place. */
462 owner_sec = (blhe->type == bfd_link_hash_common)
463 ? blhe->u.c.p->section
464 : blhe->u.def.section;
466 /* We need to know if the sym is referenced from non-IR files. Or
467 even potentially-referenced, perhaps in a future final link if
468 this is a partial one, perhaps dynamically at load-time if the
469 symbol is externally visible. */
470 ironly = !is_visible_from_outside (&syms[n], owner_sec, blhe)
471 && !bfd_hash_lookup (non_ironly_hash, syms[n].name, FALSE, FALSE);
473 /* If it was originally undefined or common, then it has been
474 resolved; determine how. */
475 if (syms[n].def == LDPK_UNDEF || syms[n].def == LDPK_WEAKUNDEF
476 || syms[n].def == LDPK_COMMON)
478 if (owner_sec->owner == link_info.output_bfd)
479 syms[n].resolution = LDPR_RESOLVED_EXEC;
480 else if (owner_sec->owner == abfd)
481 syms[n].resolution = (ironly)
482 ? LDPR_PREVAILING_DEF_IRONLY
483 : LDPR_PREVAILING_DEF;
484 else if (is_ir_dummy_bfd (owner_sec->owner))
485 syms[n].resolution = LDPR_RESOLVED_IR;
486 else if (owner_sec->owner->flags & DYNAMIC)
487 syms[n].resolution = LDPR_RESOLVED_DYN;
489 syms[n].resolution = LDPR_RESOLVED_EXEC;
493 /* Was originally def, or weakdef. Does it prevail? If the
494 owner is the original dummy bfd that supplied it, then this
495 is the definition that has prevailed. */
496 if (owner_sec->owner == link_info.output_bfd)
497 syms[n].resolution = LDPR_PREEMPTED_REG;
498 else if (owner_sec->owner == abfd)
500 syms[n].resolution = (ironly)
501 ? LDPR_PREVAILING_DEF_IRONLY
502 : LDPR_PREVAILING_DEF;
506 /* Was originally def, weakdef, or common, but has been pre-empted. */
507 syms[n].resolution = is_ir_dummy_bfd (owner_sec->owner)
509 : LDPR_PREEMPTED_REG;
514 /* Add a new (real) input file generated by a plugin. */
515 static enum ld_plugin_status
516 add_input_file (const char *pathname)
518 ASSERT (called_plugin);
519 if (!lang_add_input_file (xstrdup (pathname), lang_input_file_is_file_enum,
525 /* Add a new (real) library required by a plugin. */
526 static enum ld_plugin_status
527 add_input_library (const char *pathname)
529 ASSERT (called_plugin);
530 if (!lang_add_input_file (xstrdup (pathname), lang_input_file_is_l_enum,
536 /* Set the extra library path to be used by libraries added via
537 add_input_library. */
538 static enum ld_plugin_status
539 set_extra_library_path (const char *path)
541 ASSERT (called_plugin);
542 ldfile_add_library_path (xstrdup (path), FALSE);
546 /* Issue a diagnostic message from a plugin. */
547 static enum ld_plugin_status
548 message (int level, const char *format, ...)
551 va_start (args, format);
556 vfinfo (stdout, format, args, FALSE);
559 vfinfo (stdout, format, args, TRUE);
565 char *newfmt = ACONCAT ((level == LDPL_FATAL ? "%F" : "%X",
567 vfinfo (stderr, newfmt, args, TRUE);
576 /* Helper to size leading part of tv array and set it up. */
578 set_tv_header (struct ld_plugin_tv *tv)
583 static const unsigned int major = (unsigned)(BFD_VERSION / 100000000UL);
584 static const unsigned int minor = (unsigned)(BFD_VERSION / 1000000UL) % 100;
587 return tv_header_size;
589 for (i = 0; i < tv_header_size; i++)
591 tv[i].tv_tag = tv_header_tags[i];
592 #define TVU(x) tv[i].tv_u.tv_ ## x
593 switch (tv[i].tv_tag)
596 TVU(message) = message;
598 case LDPT_API_VERSION:
599 TVU(val) = LD_PLUGIN_API_VERSION;
601 case LDPT_GNU_LD_VERSION:
602 TVU(val) = major * 100 + minor;
604 case LDPT_LINKER_OUTPUT:
605 TVU(val) = link_info.relocatable ? LDPO_REL
606 : (link_info.shared ? LDPO_DYN : LDPO_EXEC);
608 case LDPT_OUTPUT_NAME:
609 TVU(string) = output_filename;
611 case LDPT_REGISTER_CLAIM_FILE_HOOK:
612 TVU(register_claim_file) = register_claim_file;
614 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK:
615 TVU(register_all_symbols_read) = register_all_symbols_read;
617 case LDPT_REGISTER_CLEANUP_HOOK:
618 TVU(register_cleanup) = register_cleanup;
620 case LDPT_ADD_SYMBOLS:
621 TVU(add_symbols) = add_symbols;
623 case LDPT_GET_INPUT_FILE:
624 TVU(get_input_file) = get_input_file;
626 case LDPT_RELEASE_INPUT_FILE:
627 TVU(release_input_file) = release_input_file;
629 case LDPT_GET_SYMBOLS:
630 TVU(get_symbols) = get_symbols;
632 case LDPT_ADD_INPUT_FILE:
633 TVU(add_input_file) = add_input_file;
635 case LDPT_ADD_INPUT_LIBRARY:
636 TVU(add_input_library) = add_input_library;
638 case LDPT_SET_EXTRA_LIBRARY_PATH:
639 TVU(set_extra_library_path) = set_extra_library_path;
642 /* Added a new entry to the array without adding
643 a new case to set up its value is a bug. */
648 return tv_header_size;
651 /* Append the per-plugin args list and trailing LDPT_NULL to tv. */
653 set_tv_plugin_args (plugin_t *plugin, struct ld_plugin_tv *tv)
655 plugin_arg_t *arg = plugin->args;
658 tv->tv_tag = LDPT_OPTION;
659 tv->tv_u.tv_string = arg->arg;
663 tv->tv_tag = LDPT_NULL;
667 /* Return true if any plugins are active this run. Only valid
668 after options have been processed. */
670 plugin_active_plugins_p (void)
672 return plugins_list != NULL;
675 /* Load up and initialise all plugins after argument parsing. */
677 plugin_load_plugins (void)
679 struct ld_plugin_tv *my_tv;
680 unsigned int max_args = 0;
681 plugin_t *curplug = plugins_list;
683 /* If there are no plugins, we need do nothing this run. */
687 /* First pass over plugins to find max # args needed so that we
688 can size and allocate the tv array. */
691 if (curplug->n_args > max_args)
692 max_args = curplug->n_args;
693 curplug = curplug->next;
696 /* Allocate tv array and initialise constant part. */
697 my_tv = xmalloc ((max_args + 1 + tv_header_size) * sizeof *my_tv);
698 set_tv_header (my_tv);
700 /* Pass over plugins again, activating them. */
701 curplug = plugins_list;
704 enum ld_plugin_status rv;
705 ld_plugin_onload onloadfn = dlsym (curplug->dlhandle, "onload");
707 onloadfn = dlsym (curplug->dlhandle, "_onload");
709 return set_plugin_error (curplug->name);
710 set_tv_plugin_args (curplug, &my_tv[tv_header_size]);
711 called_plugin = curplug;
712 rv = (*onloadfn) (my_tv);
713 called_plugin = NULL;
715 return set_plugin_error (curplug->name);
716 curplug = curplug->next;
719 /* Since plugin(s) inited ok, assume they're going to want symbol
720 resolutions, which needs us to track which symbols are referenced
721 by non-IR files using the linker's notice callback. */
722 link_info.notice_all = TRUE;
727 /* Call 'claim file' hook for all plugins. */
729 plugin_call_claim_file (const struct ld_plugin_input_file *file, int *claimed)
731 plugin_t *curplug = plugins_list;
733 if (no_more_claiming)
735 while (curplug && !*claimed)
737 if (curplug->claim_file_handler)
739 enum ld_plugin_status rv;
740 called_plugin = curplug;
741 rv = (*curplug->claim_file_handler) (file, claimed);
742 called_plugin = NULL;
744 set_plugin_error (curplug->name);
746 curplug = curplug->next;
748 return plugin_error_p () ? -1 : 0;
751 /* Call 'all symbols read' hook for all plugins. */
753 plugin_call_all_symbols_read (void)
755 plugin_t *curplug = plugins_list;
757 /* Disable any further file-claiming. */
758 no_more_claiming = TRUE;
760 /* If --allow-multiple-definition is in effect, we need to disable it,
761 as the plugin infrastructure relies on the multiple_definition
762 callback to swap out the dummy IR-only BFDs for new real ones
763 when it starts opening the files added during this callback. */
764 plugin_cached_allow_multiple_defs = link_info.allow_multiple_definition;
765 link_info.allow_multiple_definition = FALSE;
769 if (curplug->all_symbols_read_handler)
771 enum ld_plugin_status rv;
772 called_plugin = curplug;
773 rv = (*curplug->all_symbols_read_handler) ();
774 called_plugin = NULL;
776 set_plugin_error (curplug->name);
778 curplug = curplug->next;
780 return plugin_error_p () ? -1 : 0;
783 /* Call 'cleanup' hook for all plugins. */
785 plugin_call_cleanup (void)
787 plugin_t *curplug = plugins_list;
790 if (curplug->cleanup_handler && !curplug->cleanup_done)
792 enum ld_plugin_status rv;
793 curplug->cleanup_done = TRUE;
794 called_plugin = curplug;
795 rv = (*curplug->cleanup_handler) ();
796 called_plugin = NULL;
798 set_plugin_error (curplug->name);
799 dlclose (curplug->dlhandle);
801 curplug = curplug->next;
803 return plugin_error_p () ? -1 : 0;
806 /* Lazily init the non_ironly hash table. */
808 init_non_ironly_hash (void)
810 if (non_ironly_hash == NULL)
813 (struct bfd_hash_table *) xmalloc (sizeof (struct bfd_hash_table));
814 if (!bfd_hash_table_init_n (non_ironly_hash,
816 sizeof (struct bfd_hash_entry),
818 einfo (_("%P%F: bfd_hash_table_init failed: %E\n"));
822 /* To determine which symbols should be resolved LDPR_PREVAILING_DEF
823 and which LDPR_PREVAILING_DEF_IRONLY, we notice all the symbols as
824 the linker adds them to the linker hash table. If we see a symbol
825 being referenced from a non-IR file, we add it to the non_ironly hash
826 table. If we can't find it there at get_symbols time, we know that
827 it was referenced only by IR files. We have to notice_all symbols,
828 because we won't necessarily know until later which ones will be
829 contributed by IR files. */
831 plugin_notice (struct bfd_link_info *info ATTRIBUTE_UNUSED,
832 const char *name, bfd *abfd,
833 asection *section, bfd_vma value ATTRIBUTE_UNUSED)
835 bfd_boolean is_ref = bfd_is_und_section (section);
836 bfd_boolean is_dummy = is_ir_dummy_bfd (abfd);
837 init_non_ironly_hash ();
838 /* We only care about refs, not defs, indicated by section pointing
839 to the undefined section (according to the bfd linker notice callback
840 interface definition). */
841 if (is_ref && !is_dummy)
843 /* This is a ref from a non-IR file, so note the ref'd symbol
844 in the non-IR-only hash. */
845 if (!bfd_hash_lookup (non_ironly_hash, name, TRUE, TRUE))
846 einfo (_("%P%X: %s: hash table failure adding symbol %s"),
847 abfd->filename, name);
849 else if (!is_ref && is_dummy)
851 /* No further processing since this is a def from an IR dummy BFD. */
855 /* Continue with cref/nocrossref/trace-sym processing. */
859 /* When we add new object files to the link at all symbols read time,
860 these contain the real code and symbols generated from the IR files,
861 and so duplicate all the definitions already supplied by the dummy
862 IR-only BFDs that we created at claim files time. We use the linker's
863 multiple-definitions callback hook to fix up the clash, discarding
864 the symbol from the IR-only BFD in favour of the symbol from the
865 real BFD. We return true if this was not-really-a-clash because
866 we've fixed it up, or anyway if --allow-multiple-definition was in
867 effect (before we disabled it to ensure we got called back). */
869 plugin_multiple_definition (struct bfd_link_info *info, const char *name,
870 bfd *obfd, asection *osec ATTRIBUTE_UNUSED,
871 bfd_vma oval ATTRIBUTE_UNUSED,
872 bfd *nbfd, asection *nsec, bfd_vma nval)
874 if (is_ir_dummy_bfd (obfd))
876 struct bfd_link_hash_entry *blhe = bfd_link_hash_lookup (info->hash,
877 name, FALSE, FALSE, FALSE);
879 einfo (_("%P%X: %s: can't find IR symbol '%s'"), nbfd->filename,
881 else if (blhe->type != bfd_link_hash_defined)
882 einfo (_("%P%x: %s: bad IR symbol type %d"), name, blhe->type);
883 /* Replace it with new details. */
884 blhe->u.def.section = nsec;
885 blhe->u.def.value = nval;
888 return plugin_cached_allow_multiple_defs;