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. */
175 const char *plugin_error_plugin (void)
177 return error_plugin ? error_plugin : _("<no plugin>");
180 /* Handle -plugin arg: find and load plugin, or return error. */
181 int plugin_opt_plugin (const char *plugin)
185 newplug = xmalloc (sizeof *newplug);
186 memset (newplug, 0, sizeof *newplug);
187 newplug->name = plugin;
188 newplug->dlhandle = dlopen (plugin, RTLD_NOW);
189 if (!newplug->dlhandle)
190 return set_plugin_error (plugin);
192 /* Chain on end, so when we run list it is in command-line order. */
193 *plugins_tail_chain_ptr = newplug;
194 plugins_tail_chain_ptr = &newplug->next;
196 /* Record it as current plugin for receiving args. */
197 last_plugin = newplug;
198 last_plugin_args_tail_chain_ptr = &newplug->args;
202 /* Accumulate option arguments for last-loaded plugin, or return
204 int plugin_opt_plugin_arg (const char *arg)
206 plugin_arg_t *newarg;
209 return set_plugin_error (_("<no plugin>"));
211 newarg = xmalloc (sizeof *newarg);
215 /* Chain on end to preserve command-line order. */
216 *last_plugin_args_tail_chain_ptr = newarg;
217 last_plugin_args_tail_chain_ptr = &newarg->next;
218 last_plugin->n_args++;
222 /* Create a dummy BFD. */
224 plugin_get_ir_dummy_bfd (const char *name, bfd *srctemplate)
227 bfd *abfd = bfd_create (
228 concat (name, IRONLY_SUFFIX, (const char *)NULL),
230 bfd_set_arch_info (abfd, bfd_get_arch_info (srctemplate));
231 bfd_make_writable (abfd);
232 /* Create a minimal set of sections to own the symbols. */
233 sec = bfd_make_section_old_way (abfd, ".text");
234 bfd_set_section_flags (abfd, sec,
235 SEC_CODE | SEC_HAS_CONTENTS | SEC_READONLY
236 | SEC_ALLOC | SEC_LOAD | SEC_KEEP);
237 sec->output_section = sec;
238 sec->output_offset = 0;
242 /* Check if the BFD is an IR dummy. */
244 is_ir_dummy_bfd (const bfd *abfd)
246 size_t namlen = strlen (abfd->filename);
247 if (namlen < IRONLY_SUFFIX_LEN)
249 return !strcmp (abfd->filename + namlen - IRONLY_SUFFIX_LEN, IRONLY_SUFFIX);
252 /* Helpers to convert between BFD and GOLD symbol formats. */
253 static enum ld_plugin_status
254 asymbol_from_plugin_symbol (bfd *abfd, asymbol *asym,
255 const struct ld_plugin_symbol *ldsym)
257 flagword flags = BSF_NO_FLAGS;
258 struct bfd_section *section;
260 asym->the_bfd = abfd;
261 asym->name = ldsym->version
262 ? concat (ldsym->name, "@", ldsym->version, NULL)
272 section = bfd_get_section_by_name (abfd, ".text");
279 section = bfd_und_section_ptr;
284 section = bfd_com_section_ptr;
285 asym->value = ldsym->size;
292 asym->section = section;
294 /* Visibility only applies on ELF targets. */
295 if (bfd_get_flavour (abfd) == bfd_target_elf_flavour)
297 elf_symbol_type *elfsym = elf_symbol_from (abfd, asym);
299 einfo (_("%P%F: %s: non-ELF symbol in ELF BFD!"), asym->name);
300 elfsym->internal_elf_sym.st_other &= ~3;
301 elfsym->internal_elf_sym.st_other |= ldsym->visibility;
307 /* Register a claim-file handler. */
308 static enum ld_plugin_status
309 register_claim_file (ld_plugin_claim_file_handler handler)
311 ASSERT (called_plugin);
312 called_plugin->claim_file_handler = handler;
316 /* Register an all-symbols-read handler. */
317 static enum ld_plugin_status
318 register_all_symbols_read (ld_plugin_all_symbols_read_handler handler)
320 ASSERT (called_plugin);
321 called_plugin->all_symbols_read_handler = handler;
325 /* Register a cleanup handler. */
326 static enum ld_plugin_status
327 register_cleanup (ld_plugin_cleanup_handler handler)
329 ASSERT (called_plugin);
330 called_plugin->cleanup_handler = handler;
334 /* Add symbols from a plugin-claimed input file. */
335 static enum ld_plugin_status
336 add_symbols (void *handle, int nsyms, const struct ld_plugin_symbol *syms)
341 ASSERT (called_plugin);
342 symptrs = xmalloc (nsyms * sizeof *symptrs);
343 for (n = 0; n < nsyms; n++)
345 enum ld_plugin_status rv;
346 asymbol *bfdsym = bfd_make_empty_symbol (abfd);
348 rv = asymbol_from_plugin_symbol (abfd, bfdsym, syms + n);
352 bfd_set_symtab (abfd, symptrs, nsyms);
356 /* Get the input file information with an open (possibly re-opened)
358 static enum ld_plugin_status
359 get_input_file (const void *handle, struct ld_plugin_input_file *file)
361 ASSERT (called_plugin);
367 /* Release the input file. */
368 static enum ld_plugin_status
369 release_input_file (const void *handle)
371 ASSERT (called_plugin);
376 /* Get the symbol resolution info for a plugin-claimed input file. */
377 static enum ld_plugin_status
378 get_symbols (const void *handle, int nsyms, struct ld_plugin_symbol *syms)
380 const bfd *abfd = handle;
382 ASSERT (called_plugin);
383 for (n = 0; n < nsyms; n++)
385 struct bfd_link_hash_entry *blhe;
388 blhe = bfd_link_hash_lookup (link_info.hash, syms[n].name,
392 syms[n].resolution = LDPR_UNKNOWN;
396 /* Determine resolution from blhe type and symbol's original type. */
397 if (blhe->type == bfd_link_hash_undefined
398 || blhe->type == bfd_link_hash_undefweak)
400 syms[n].resolution = LDPR_UNDEF;
403 if (blhe->type != bfd_link_hash_defined
404 && blhe->type != bfd_link_hash_defweak
405 && blhe->type != bfd_link_hash_common)
407 /* We should not have a new, indirect or warning symbol here. */
408 einfo ("%P%F: %s: plugin symbol table corrupt (sym type %d)",
409 called_plugin->name, blhe->type);
412 /* We need to know if the sym is referenced from non-IR files. */
413 ironly = !bfd_hash_lookup (non_ironly_hash, syms[n].name, FALSE, FALSE);
415 /* If it was originally undefined or common, then it has been
416 resolved; determine how. */
417 if (syms[n].def == LDPK_UNDEF || syms[n].def == LDPK_WEAKUNDEF
418 || syms[n].def == LDPK_COMMON)
420 asection *owner_sec = (blhe->type == bfd_link_hash_common)
421 ? blhe->u.c.p->section
422 : blhe->u.def.section;
423 if (owner_sec->owner == link_info.output_bfd)
424 syms[n].resolution = LDPR_RESOLVED_EXEC;
425 else if (owner_sec->owner == abfd)
426 syms[n].resolution = (ironly)
427 ? LDPR_PREVAILING_DEF_IRONLY
428 : LDPR_PREVAILING_DEF;
429 else if (is_ir_dummy_bfd (owner_sec->owner))
430 syms[n].resolution = LDPR_RESOLVED_IR;
431 else if (owner_sec->owner->flags & DYNAMIC)
432 syms[n].resolution = LDPR_RESOLVED_DYN;
434 syms[n].resolution = LDPR_RESOLVED_EXEC;
438 /* Was originally def, or weakdef. Does it prevail? If the
439 owner is the original dummy bfd that supplied it, then this
440 is the definition that has prevailed. */
441 if (blhe->u.def.section->owner == link_info.output_bfd)
442 syms[n].resolution = LDPR_PREEMPTED_REG;
443 else if (blhe->u.def.section->owner == abfd)
445 syms[n].resolution = (ironly)
446 ? LDPR_PREVAILING_DEF_IRONLY
447 : LDPR_PREVAILING_DEF;
451 /* Was originally def, weakdef, or common, but has been pre-empted. */
452 syms[n].resolution = is_ir_dummy_bfd (blhe->u.def.section->owner)
454 : LDPR_PREEMPTED_REG;
459 /* Add a new (real) input file generated by a plugin. */
460 static enum ld_plugin_status
461 add_input_file (const char *pathname)
463 ASSERT (called_plugin);
464 if (!lang_add_input_file (xstrdup (pathname), lang_input_file_is_file_enum,
470 /* Add a new (real) library required by a plugin. */
471 static enum ld_plugin_status
472 add_input_library (const char *pathname)
474 ASSERT (called_plugin);
475 if (!lang_add_input_file (xstrdup (pathname), lang_input_file_is_l_enum,
481 /* Set the extra library path to be used by libraries added via
482 add_input_library. */
483 static enum ld_plugin_status
484 set_extra_library_path (const char *path)
486 ASSERT (called_plugin);
487 ldfile_add_library_path (xstrdup (path), FALSE);
491 /* Issue a diagnostic message from a plugin. */
492 static enum ld_plugin_status
493 message (int level, const char *format, ...)
496 va_start (args, format);
501 vfinfo (stdout, format, args, FALSE);
504 vfinfo (stdout, format, args, TRUE);
510 char *newfmt = ACONCAT ((level == LDPL_FATAL ? "%F" : "%X",
512 vfinfo (stderr, newfmt, args, TRUE);
521 /* Helper to size leading part of tv array and set it up. */
523 set_tv_header (struct ld_plugin_tv *tv)
528 static const unsigned int major = (unsigned)(BFD_VERSION / 100000000UL);
529 static const unsigned int minor = (unsigned)(BFD_VERSION / 1000000UL) % 100;
532 return tv_header_size;
534 for (i = 0; i < tv_header_size; i++)
536 tv[i].tv_tag = tv_header_tags[i];
537 #define TVU(x) tv[i].tv_u.tv_ ## x
538 switch (tv[i].tv_tag)
541 TVU(message) = message;
543 case LDPT_API_VERSION:
544 TVU(val) = LD_PLUGIN_API_VERSION;
546 case LDPT_GNU_LD_VERSION:
547 TVU(val) = major * 100 + minor;
549 case LDPT_LINKER_OUTPUT:
550 TVU(val) = link_info.relocatable ? LDPO_REL
551 : (link_info.shared ? LDPO_DYN : LDPO_EXEC);
553 case LDPT_OUTPUT_NAME:
554 TVU(string) = output_filename;
556 case LDPT_REGISTER_CLAIM_FILE_HOOK:
557 TVU(register_claim_file) = register_claim_file;
559 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK:
560 TVU(register_all_symbols_read) = register_all_symbols_read;
562 case LDPT_REGISTER_CLEANUP_HOOK:
563 TVU(register_cleanup) = register_cleanup;
565 case LDPT_ADD_SYMBOLS:
566 TVU(add_symbols) = add_symbols;
568 case LDPT_GET_INPUT_FILE:
569 TVU(get_input_file) = get_input_file;
571 case LDPT_RELEASE_INPUT_FILE:
572 TVU(release_input_file) = release_input_file;
574 case LDPT_GET_SYMBOLS:
575 TVU(get_symbols) = get_symbols;
577 case LDPT_ADD_INPUT_FILE:
578 TVU(add_input_file) = add_input_file;
580 case LDPT_ADD_INPUT_LIBRARY:
581 TVU(add_input_library) = add_input_library;
583 case LDPT_SET_EXTRA_LIBRARY_PATH:
584 TVU(set_extra_library_path) = set_extra_library_path;
587 /* Added a new entry to the array without adding
588 a new case to set up its value is a bug. */
593 return tv_header_size;
596 /* Append the per-plugin args list and trailing LDPT_NULL to tv. */
598 set_tv_plugin_args (plugin_t *plugin, struct ld_plugin_tv *tv)
600 plugin_arg_t *arg = plugin->args;
603 tv->tv_tag = LDPT_OPTION;
604 tv->tv_u.tv_string = arg->arg;
608 tv->tv_tag = LDPT_NULL;
612 /* Load up and initialise all plugins after argument parsing. */
613 int plugin_load_plugins (void)
615 struct ld_plugin_tv *my_tv;
616 unsigned int max_args = 0;
617 plugin_t *curplug = plugins_list;
619 /* If there are no plugins, we need do nothing this run. */
623 /* First pass over plugins to find max # args needed so that we
624 can size and allocate the tv array. */
627 if (curplug->n_args > max_args)
628 max_args = curplug->n_args;
629 curplug = curplug->next;
632 /* Allocate tv array and initialise constant part. */
633 my_tv = xmalloc ((max_args + 1 + tv_header_size) * sizeof *my_tv);
634 set_tv_header (my_tv);
636 /* Pass over plugins again, activating them. */
637 curplug = plugins_list;
640 enum ld_plugin_status rv;
641 ld_plugin_onload onloadfn = dlsym (curplug->dlhandle, "onload");
643 onloadfn = dlsym (curplug->dlhandle, "_onload");
645 return set_plugin_error (curplug->name);
646 set_tv_plugin_args (curplug, &my_tv[tv_header_size]);
647 called_plugin = curplug;
648 rv = (*onloadfn) (my_tv);
649 called_plugin = NULL;
651 return set_plugin_error (curplug->name);
652 curplug = curplug->next;
655 /* Since plugin(s) inited ok, assume they're going to want symbol
656 resolutions, which needs us to track which symbols are referenced
657 by non-IR files using the linker's notice callback. */
658 link_info.notice_all = TRUE;
663 /* Call 'claim file' hook for all plugins. */
665 plugin_call_claim_file (const struct ld_plugin_input_file *file, int *claimed)
667 plugin_t *curplug = plugins_list;
669 if (no_more_claiming)
671 while (curplug && !*claimed)
673 if (curplug->claim_file_handler)
675 enum ld_plugin_status rv;
676 called_plugin = curplug;
677 rv = (*curplug->claim_file_handler) (file, claimed);
678 called_plugin = NULL;
680 set_plugin_error (curplug->name);
682 curplug = curplug->next;
684 return plugin_error_p () ? -1 : 0;
687 /* Call 'all symbols read' hook for all plugins. */
689 plugin_call_all_symbols_read (void)
691 plugin_t *curplug = plugins_list;
693 /* Disable any further file-claiming. */
694 no_more_claiming = TRUE;
696 /* If --allow-multiple-definition is in effect, we need to disable it,
697 as the plugin infrastructure relies on the multiple_definition
698 callback to swap out the dummy IR-only BFDs for new real ones
699 when it starts opening the files added during this callback. */
700 plugin_cached_allow_multiple_defs = link_info.allow_multiple_definition;
701 link_info.allow_multiple_definition = FALSE;
705 if (curplug->all_symbols_read_handler)
707 enum ld_plugin_status rv;
708 called_plugin = curplug;
709 rv = (*curplug->all_symbols_read_handler) ();
710 called_plugin = NULL;
712 set_plugin_error (curplug->name);
714 curplug = curplug->next;
716 return plugin_error_p () ? -1 : 0;
719 /* Call 'cleanup' hook for all plugins. */
721 plugin_call_cleanup (void)
723 plugin_t *curplug = plugins_list;
726 if (curplug->cleanup_handler && !curplug->cleanup_done)
728 enum ld_plugin_status rv;
729 curplug->cleanup_done = TRUE;
730 called_plugin = curplug;
731 rv = (*curplug->cleanup_handler) ();
732 called_plugin = NULL;
734 set_plugin_error (curplug->name);
735 dlclose (curplug->dlhandle);
737 curplug = curplug->next;
739 return plugin_error_p () ? -1 : 0;
742 /* Lazily init the non_ironly hash table. */
744 init_non_ironly_hash (void)
746 if (non_ironly_hash == NULL)
749 (struct bfd_hash_table *) xmalloc (sizeof (struct bfd_hash_table));
750 if (!bfd_hash_table_init_n (non_ironly_hash,
752 sizeof (struct bfd_hash_entry),
754 einfo (_("%P%F: bfd_hash_table_init failed: %E\n"));
758 /* To determine which symbols should be resolved LDPR_PREVAILING_DEF
759 and which LDPR_PREVAILING_DEF_IRONLY, we notice all the symbols as
760 the linker adds them to the linker hash table. If we see a symbol
761 being referenced from a non-IR file, we add it to the non_ironly hash
762 table. If we can't find it there at get_symbols time, we know that
763 it was referenced only by IR files. We have to notice_all symbols,
764 because we won't necessarily know until later which ones will be
765 contributed by IR files. */
767 plugin_notice (struct bfd_link_info *info ATTRIBUTE_UNUSED,
768 const char *name, bfd *abfd,
769 asection *section, bfd_vma value ATTRIBUTE_UNUSED)
771 bfd_boolean is_ref = bfd_is_und_section (section);
772 bfd_boolean is_dummy = is_ir_dummy_bfd (abfd);
773 init_non_ironly_hash ();
774 /* We only care about refs, not defs, indicated by section pointing
775 to the undefined section (according to the bfd linker notice callback
776 interface definition). */
777 if (is_ref && !is_dummy)
779 /* This is a ref from a non-IR file, so note the ref'd symbol
780 in the non-IR-only hash. */
781 if (!bfd_hash_lookup (non_ironly_hash, name, TRUE, TRUE))
782 einfo (_("%P%X: %s: hash table failure adding symbol %s"),
783 abfd->filename, name);
785 else if (!is_ref && is_dummy)
787 /* No further processing since this is a def from an IR dummy BFD. */
791 /* Continue with cref/nocrossref/trace-sym processing. */
795 /* When we add new object files to the link at all symbols read time,
796 these contain the real code and symbols generated from the IR files,
797 and so duplicate all the definitions already supplied by the dummy
798 IR-only BFDs that we created at claim files time. We use the linker's
799 multiple-definitions callback hook to fix up the clash, discarding
800 the symbol from the IR-only BFD in favour of the symbol from the
801 real BFD. We return true if this was not-really-a-clash because
802 we've fixed it up, or anyway if --allow-multiple-definition was in
803 effect (before we disabled it to ensure we got called back). */
805 plugin_multiple_definition (struct bfd_link_info *info, const char *name,
806 bfd *obfd, asection *osec ATTRIBUTE_UNUSED,
807 bfd_vma oval ATTRIBUTE_UNUSED,
808 bfd *nbfd, asection *nsec, bfd_vma nval)
810 if (is_ir_dummy_bfd (obfd))
812 struct bfd_link_hash_entry *blhe = bfd_link_hash_lookup (info->hash,
813 name, FALSE, FALSE, FALSE);
815 einfo (_("%P%X: %s: can't find IR symbol '%s'"), nbfd->filename,
817 else if (blhe->type != bfd_link_hash_defined)
818 einfo (_("%P%x: %s: bad IR symbol type %d"), name, blhe->type);
819 /* Replace it with new details. */
820 blhe->u.def.section = nsec;
821 blhe->u.def.value = nval;
824 return plugin_cached_allow_multiple_defs;