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)
229 bfd_use_reserved_id = 1;
230 abfd = bfd_create (concat (name, IRONLY_SUFFIX, (const char *)NULL),
232 bfd_set_arch_info (abfd, bfd_get_arch_info (srctemplate));
233 bfd_make_writable (abfd);
234 /* Create a minimal set of sections to own the symbols. */
235 sec = bfd_make_section_old_way (abfd, ".text");
236 bfd_set_section_flags (abfd, sec,
237 (SEC_CODE | SEC_HAS_CONTENTS | SEC_READONLY
238 | SEC_ALLOC | SEC_LOAD | SEC_KEEP));
239 sec->output_section = sec;
240 sec->output_offset = 0;
244 /* Check if the BFD is an IR dummy. */
246 is_ir_dummy_bfd (const bfd *abfd)
248 size_t namlen = strlen (abfd->filename);
249 if (namlen < IRONLY_SUFFIX_LEN)
251 return !strcmp (abfd->filename + namlen - IRONLY_SUFFIX_LEN, IRONLY_SUFFIX);
254 /* Helpers to convert between BFD and GOLD symbol formats. */
255 static enum ld_plugin_status
256 asymbol_from_plugin_symbol (bfd *abfd, asymbol *asym,
257 const struct ld_plugin_symbol *ldsym)
259 flagword flags = BSF_NO_FLAGS;
260 struct bfd_section *section;
262 asym->the_bfd = abfd;
263 asym->name = ldsym->version
264 ? concat (ldsym->name, "@", ldsym->version, NULL)
274 section = bfd_get_section_by_name (abfd, ".text");
281 section = bfd_und_section_ptr;
286 section = bfd_com_section_ptr;
287 asym->value = ldsym->size;
294 asym->section = section;
296 /* Visibility only applies on ELF targets. */
297 if (bfd_get_flavour (abfd) == bfd_target_elf_flavour)
299 elf_symbol_type *elfsym = elf_symbol_from (abfd, asym);
301 einfo (_("%P%F: %s: non-ELF symbol in ELF BFD!"), asym->name);
302 elfsym->internal_elf_sym.st_other &= ~3;
303 elfsym->internal_elf_sym.st_other |= ldsym->visibility;
309 /* Register a claim-file handler. */
310 static enum ld_plugin_status
311 register_claim_file (ld_plugin_claim_file_handler handler)
313 ASSERT (called_plugin);
314 called_plugin->claim_file_handler = handler;
318 /* Register an all-symbols-read handler. */
319 static enum ld_plugin_status
320 register_all_symbols_read (ld_plugin_all_symbols_read_handler handler)
322 ASSERT (called_plugin);
323 called_plugin->all_symbols_read_handler = handler;
327 /* Register a cleanup handler. */
328 static enum ld_plugin_status
329 register_cleanup (ld_plugin_cleanup_handler handler)
331 ASSERT (called_plugin);
332 called_plugin->cleanup_handler = handler;
336 /* Add symbols from a plugin-claimed input file. */
337 static enum ld_plugin_status
338 add_symbols (void *handle, int nsyms, const struct ld_plugin_symbol *syms)
343 ASSERT (called_plugin);
344 symptrs = xmalloc (nsyms * sizeof *symptrs);
345 for (n = 0; n < nsyms; n++)
347 enum ld_plugin_status rv;
348 asymbol *bfdsym = bfd_make_empty_symbol (abfd);
350 rv = asymbol_from_plugin_symbol (abfd, bfdsym, syms + n);
354 bfd_set_symtab (abfd, symptrs, nsyms);
358 /* Get the input file information with an open (possibly re-opened)
360 static enum ld_plugin_status
361 get_input_file (const void *handle, struct ld_plugin_input_file *file)
363 ASSERT (called_plugin);
369 /* Release the input file. */
370 static enum ld_plugin_status
371 release_input_file (const void *handle)
373 ASSERT (called_plugin);
378 /* Get the symbol resolution info for a plugin-claimed input file. */
379 static enum ld_plugin_status
380 get_symbols (const void *handle, int nsyms, struct ld_plugin_symbol *syms)
382 const bfd *abfd = handle;
384 ASSERT (called_plugin);
385 for (n = 0; n < nsyms; n++)
387 struct bfd_link_hash_entry *blhe;
390 blhe = bfd_link_hash_lookup (link_info.hash, syms[n].name,
394 syms[n].resolution = LDPR_UNKNOWN;
398 /* Determine resolution from blhe type and symbol's original type. */
399 if (blhe->type == bfd_link_hash_undefined
400 || blhe->type == bfd_link_hash_undefweak)
402 syms[n].resolution = LDPR_UNDEF;
405 if (blhe->type != bfd_link_hash_defined
406 && blhe->type != bfd_link_hash_defweak
407 && blhe->type != bfd_link_hash_common)
409 /* We should not have a new, indirect or warning symbol here. */
410 einfo ("%P%F: %s: plugin symbol table corrupt (sym type %d)",
411 called_plugin->name, blhe->type);
414 /* We need to know if the sym is referenced from non-IR files. */
415 ironly = !bfd_hash_lookup (non_ironly_hash, syms[n].name, FALSE, FALSE);
417 /* If it was originally undefined or common, then it has been
418 resolved; determine how. */
419 if (syms[n].def == LDPK_UNDEF || syms[n].def == LDPK_WEAKUNDEF
420 || syms[n].def == LDPK_COMMON)
422 asection *owner_sec = (blhe->type == bfd_link_hash_common)
423 ? blhe->u.c.p->section
424 : blhe->u.def.section;
425 if (owner_sec->owner == link_info.output_bfd)
426 syms[n].resolution = LDPR_RESOLVED_EXEC;
427 else if (owner_sec->owner == abfd)
428 syms[n].resolution = (ironly)
429 ? LDPR_PREVAILING_DEF_IRONLY
430 : LDPR_PREVAILING_DEF;
431 else if (is_ir_dummy_bfd (owner_sec->owner))
432 syms[n].resolution = LDPR_RESOLVED_IR;
433 else if (owner_sec->owner->flags & DYNAMIC)
434 syms[n].resolution = LDPR_RESOLVED_DYN;
436 syms[n].resolution = LDPR_RESOLVED_EXEC;
440 /* Was originally def, or weakdef. Does it prevail? If the
441 owner is the original dummy bfd that supplied it, then this
442 is the definition that has prevailed. */
443 if (blhe->u.def.section->owner == link_info.output_bfd)
444 syms[n].resolution = LDPR_PREEMPTED_REG;
445 else if (blhe->u.def.section->owner == abfd)
447 syms[n].resolution = (ironly)
448 ? LDPR_PREVAILING_DEF_IRONLY
449 : LDPR_PREVAILING_DEF;
453 /* Was originally def, weakdef, or common, but has been pre-empted. */
454 syms[n].resolution = is_ir_dummy_bfd (blhe->u.def.section->owner)
456 : LDPR_PREEMPTED_REG;
461 /* Add a new (real) input file generated by a plugin. */
462 static enum ld_plugin_status
463 add_input_file (const char *pathname)
465 ASSERT (called_plugin);
466 if (!lang_add_input_file (xstrdup (pathname), lang_input_file_is_file_enum,
472 /* Add a new (real) library required by a plugin. */
473 static enum ld_plugin_status
474 add_input_library (const char *pathname)
476 ASSERT (called_plugin);
477 if (!lang_add_input_file (xstrdup (pathname), lang_input_file_is_l_enum,
483 /* Set the extra library path to be used by libraries added via
484 add_input_library. */
485 static enum ld_plugin_status
486 set_extra_library_path (const char *path)
488 ASSERT (called_plugin);
489 ldfile_add_library_path (xstrdup (path), FALSE);
493 /* Issue a diagnostic message from a plugin. */
494 static enum ld_plugin_status
495 message (int level, const char *format, ...)
498 va_start (args, format);
503 vfinfo (stdout, format, args, FALSE);
506 vfinfo (stdout, format, args, TRUE);
512 char *newfmt = ACONCAT ((level == LDPL_FATAL ? "%F" : "%X",
514 vfinfo (stderr, newfmt, args, TRUE);
523 /* Helper to size leading part of tv array and set it up. */
525 set_tv_header (struct ld_plugin_tv *tv)
530 static const unsigned int major = (unsigned)(BFD_VERSION / 100000000UL);
531 static const unsigned int minor = (unsigned)(BFD_VERSION / 1000000UL) % 100;
534 return tv_header_size;
536 for (i = 0; i < tv_header_size; i++)
538 tv[i].tv_tag = tv_header_tags[i];
539 #define TVU(x) tv[i].tv_u.tv_ ## x
540 switch (tv[i].tv_tag)
543 TVU(message) = message;
545 case LDPT_API_VERSION:
546 TVU(val) = LD_PLUGIN_API_VERSION;
548 case LDPT_GNU_LD_VERSION:
549 TVU(val) = major * 100 + minor;
551 case LDPT_LINKER_OUTPUT:
552 TVU(val) = link_info.relocatable ? LDPO_REL
553 : (link_info.shared ? LDPO_DYN : LDPO_EXEC);
555 case LDPT_OUTPUT_NAME:
556 TVU(string) = output_filename;
558 case LDPT_REGISTER_CLAIM_FILE_HOOK:
559 TVU(register_claim_file) = register_claim_file;
561 case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK:
562 TVU(register_all_symbols_read) = register_all_symbols_read;
564 case LDPT_REGISTER_CLEANUP_HOOK:
565 TVU(register_cleanup) = register_cleanup;
567 case LDPT_ADD_SYMBOLS:
568 TVU(add_symbols) = add_symbols;
570 case LDPT_GET_INPUT_FILE:
571 TVU(get_input_file) = get_input_file;
573 case LDPT_RELEASE_INPUT_FILE:
574 TVU(release_input_file) = release_input_file;
576 case LDPT_GET_SYMBOLS:
577 TVU(get_symbols) = get_symbols;
579 case LDPT_ADD_INPUT_FILE:
580 TVU(add_input_file) = add_input_file;
582 case LDPT_ADD_INPUT_LIBRARY:
583 TVU(add_input_library) = add_input_library;
585 case LDPT_SET_EXTRA_LIBRARY_PATH:
586 TVU(set_extra_library_path) = set_extra_library_path;
589 /* Added a new entry to the array without adding
590 a new case to set up its value is a bug. */
595 return tv_header_size;
598 /* Append the per-plugin args list and trailing LDPT_NULL to tv. */
600 set_tv_plugin_args (plugin_t *plugin, struct ld_plugin_tv *tv)
602 plugin_arg_t *arg = plugin->args;
605 tv->tv_tag = LDPT_OPTION;
606 tv->tv_u.tv_string = arg->arg;
610 tv->tv_tag = LDPT_NULL;
614 /* Load up and initialise all plugins after argument parsing. */
615 int plugin_load_plugins (void)
617 struct ld_plugin_tv *my_tv;
618 unsigned int max_args = 0;
619 plugin_t *curplug = plugins_list;
621 /* If there are no plugins, we need do nothing this run. */
625 /* First pass over plugins to find max # args needed so that we
626 can size and allocate the tv array. */
629 if (curplug->n_args > max_args)
630 max_args = curplug->n_args;
631 curplug = curplug->next;
634 /* Allocate tv array and initialise constant part. */
635 my_tv = xmalloc ((max_args + 1 + tv_header_size) * sizeof *my_tv);
636 set_tv_header (my_tv);
638 /* Pass over plugins again, activating them. */
639 curplug = plugins_list;
642 enum ld_plugin_status rv;
643 ld_plugin_onload onloadfn = dlsym (curplug->dlhandle, "onload");
645 onloadfn = dlsym (curplug->dlhandle, "_onload");
647 return set_plugin_error (curplug->name);
648 set_tv_plugin_args (curplug, &my_tv[tv_header_size]);
649 called_plugin = curplug;
650 rv = (*onloadfn) (my_tv);
651 called_plugin = NULL;
653 return set_plugin_error (curplug->name);
654 curplug = curplug->next;
657 /* Since plugin(s) inited ok, assume they're going to want symbol
658 resolutions, which needs us to track which symbols are referenced
659 by non-IR files using the linker's notice callback. */
660 link_info.notice_all = TRUE;
665 /* Call 'claim file' hook for all plugins. */
667 plugin_call_claim_file (const struct ld_plugin_input_file *file, int *claimed)
669 plugin_t *curplug = plugins_list;
671 if (no_more_claiming)
673 while (curplug && !*claimed)
675 if (curplug->claim_file_handler)
677 enum ld_plugin_status rv;
678 called_plugin = curplug;
679 rv = (*curplug->claim_file_handler) (file, claimed);
680 called_plugin = NULL;
682 set_plugin_error (curplug->name);
684 curplug = curplug->next;
686 return plugin_error_p () ? -1 : 0;
689 /* Call 'all symbols read' hook for all plugins. */
691 plugin_call_all_symbols_read (void)
693 plugin_t *curplug = plugins_list;
695 /* Disable any further file-claiming. */
696 no_more_claiming = TRUE;
698 /* If --allow-multiple-definition is in effect, we need to disable it,
699 as the plugin infrastructure relies on the multiple_definition
700 callback to swap out the dummy IR-only BFDs for new real ones
701 when it starts opening the files added during this callback. */
702 plugin_cached_allow_multiple_defs = link_info.allow_multiple_definition;
703 link_info.allow_multiple_definition = FALSE;
707 if (curplug->all_symbols_read_handler)
709 enum ld_plugin_status rv;
710 called_plugin = curplug;
711 rv = (*curplug->all_symbols_read_handler) ();
712 called_plugin = NULL;
714 set_plugin_error (curplug->name);
716 curplug = curplug->next;
718 return plugin_error_p () ? -1 : 0;
721 /* Call 'cleanup' hook for all plugins. */
723 plugin_call_cleanup (void)
725 plugin_t *curplug = plugins_list;
728 if (curplug->cleanup_handler && !curplug->cleanup_done)
730 enum ld_plugin_status rv;
731 curplug->cleanup_done = TRUE;
732 called_plugin = curplug;
733 rv = (*curplug->cleanup_handler) ();
734 called_plugin = NULL;
736 set_plugin_error (curplug->name);
737 dlclose (curplug->dlhandle);
739 curplug = curplug->next;
741 return plugin_error_p () ? -1 : 0;
744 /* Lazily init the non_ironly hash table. */
746 init_non_ironly_hash (void)
748 if (non_ironly_hash == NULL)
751 (struct bfd_hash_table *) xmalloc (sizeof (struct bfd_hash_table));
752 if (!bfd_hash_table_init_n (non_ironly_hash,
754 sizeof (struct bfd_hash_entry),
756 einfo (_("%P%F: bfd_hash_table_init failed: %E\n"));
760 /* To determine which symbols should be resolved LDPR_PREVAILING_DEF
761 and which LDPR_PREVAILING_DEF_IRONLY, we notice all the symbols as
762 the linker adds them to the linker hash table. If we see a symbol
763 being referenced from a non-IR file, we add it to the non_ironly hash
764 table. If we can't find it there at get_symbols time, we know that
765 it was referenced only by IR files. We have to notice_all symbols,
766 because we won't necessarily know until later which ones will be
767 contributed by IR files. */
769 plugin_notice (struct bfd_link_info *info ATTRIBUTE_UNUSED,
770 const char *name, bfd *abfd,
771 asection *section, bfd_vma value ATTRIBUTE_UNUSED)
773 bfd_boolean is_ref = bfd_is_und_section (section);
774 bfd_boolean is_dummy = is_ir_dummy_bfd (abfd);
775 init_non_ironly_hash ();
776 /* We only care about refs, not defs, indicated by section pointing
777 to the undefined section (according to the bfd linker notice callback
778 interface definition). */
779 if (is_ref && !is_dummy)
781 /* This is a ref from a non-IR file, so note the ref'd symbol
782 in the non-IR-only hash. */
783 if (!bfd_hash_lookup (non_ironly_hash, name, TRUE, TRUE))
784 einfo (_("%P%X: %s: hash table failure adding symbol %s"),
785 abfd->filename, name);
787 else if (!is_ref && is_dummy)
789 /* No further processing since this is a def from an IR dummy BFD. */
793 /* Continue with cref/nocrossref/trace-sym processing. */
797 /* When we add new object files to the link at all symbols read time,
798 these contain the real code and symbols generated from the IR files,
799 and so duplicate all the definitions already supplied by the dummy
800 IR-only BFDs that we created at claim files time. We use the linker's
801 multiple-definitions callback hook to fix up the clash, discarding
802 the symbol from the IR-only BFD in favour of the symbol from the
803 real BFD. We return true if this was not-really-a-clash because
804 we've fixed it up, or anyway if --allow-multiple-definition was in
805 effect (before we disabled it to ensure we got called back). */
807 plugin_multiple_definition (struct bfd_link_info *info, const char *name,
808 bfd *obfd, asection *osec ATTRIBUTE_UNUSED,
809 bfd_vma oval ATTRIBUTE_UNUSED,
810 bfd *nbfd, asection *nsec, bfd_vma nval)
812 if (is_ir_dummy_bfd (obfd))
814 struct bfd_link_hash_entry *blhe = bfd_link_hash_lookup (info->hash,
815 name, FALSE, FALSE, FALSE);
817 einfo (_("%P%X: %s: can't find IR symbol '%s'"), nbfd->filename,
819 else if (blhe->type != bfd_link_hash_defined)
820 einfo (_("%P%x: %s: bad IR symbol type %d"), name, blhe->type);
821 /* Replace it with new details. */
822 blhe->u.def.section = nsec;
823 blhe->u.def.value = nval;
826 return plugin_cached_allow_multiple_defs;