/* Plugin control for the GNU linker. Copyright 2010 Free Software Foundation, Inc. This file is part of the GNU Binutils. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */ #include "sysdep.h" #include "libiberty.h" #include "bfd.h" #include "bfdlink.h" #include "bfdver.h" #include "ld.h" #include "ldmain.h" #include "ldmisc.h" #include "ldexp.h" #include "ldlang.h" #include "ldfile.h" #include "plugin.h" #include "plugin-api.h" #include "elf-bfd.h" #if !defined (HAVE_DLFCN_H) && defined (HAVE_WINDOWS_H) #include #endif /* The suffix to append to the name of the real (claimed) object file when generating a dummy BFD to hold the IR symbols sent from the plugin. */ #define IRONLY_SUFFIX ".ironly\004" /* This is sizeof an array of chars, not sizeof a const char *. We also have to avoid inadvertently counting the trailing NUL. */ #define IRONLY_SUFFIX_LEN (sizeof (IRONLY_SUFFIX) - 1) /* Stores a single argument passed to a plugin. */ typedef struct plugin_arg { struct plugin_arg *next; const char *arg; } plugin_arg_t; /* Holds all details of a single plugin. */ typedef struct plugin { /* Next on the list of plugins, or NULL at end of chain. */ struct plugin *next; /* The argument string given to --plugin. */ const char *name; /* The shared library handle returned by dlopen. */ void *dlhandle; /* The list of argument string given to --plugin-opt. */ plugin_arg_t *args; /* Number of args in the list, for convenience. */ size_t n_args; /* The plugin's event handlers. */ ld_plugin_claim_file_handler claim_file_handler; ld_plugin_all_symbols_read_handler all_symbols_read_handler; ld_plugin_cleanup_handler cleanup_handler; /* TRUE if the cleanup handlers have been called. */ bfd_boolean cleanup_done; } plugin_t; /* The master list of all plugins. */ static plugin_t *plugins_list = NULL; /* We keep a tail pointer for easy linking on the end. */ static plugin_t **plugins_tail_chain_ptr = &plugins_list; /* The last plugin added to the list, for receiving args. */ static plugin_t *last_plugin = NULL; /* The tail of the arg chain of the last plugin added to the list. */ static plugin_arg_t **last_plugin_args_tail_chain_ptr = NULL; /* The plugin which is currently having a callback executed. */ static plugin_t *called_plugin = NULL; /* Last plugin to cause an error, if any. */ static const char *error_plugin = NULL; /* A hash table that records symbols referenced by non-IR files. Used at get_symbols time to determine whether any prevailing defs from IR files are referenced only from other IR files, so tthat we can we can distinguish the LDPR_PREVAILING_DEF and LDPR_PREVAILING_DEF_IRONLY cases when establishing symbol resolutions. */ static struct bfd_hash_table *non_ironly_hash = NULL; /* Set at all symbols read time, to avoid recursively offering the plugin its own newly-added input files and libs to claim. */ static bfd_boolean no_more_claiming = FALSE; /* If the --allow-multiple-definition command-line option is active, we have to disable it so that BFD always calls our hook, and simulate the effect (when not resolving IR vs. real symbols) ourselves by ensuring TRUE is returned from the hook. */ static bfd_boolean plugin_cached_allow_multiple_defs = FALSE; /* Call 'cleanup' hook for all plugins at exit. */ static void plugin_call_cleanup (void); /* List of tags to set in the constant leading part of the tv array. */ static const enum ld_plugin_tag tv_header_tags[] = { LDPT_MESSAGE, LDPT_API_VERSION, LDPT_GNU_LD_VERSION, LDPT_LINKER_OUTPUT, LDPT_OUTPUT_NAME, LDPT_REGISTER_CLAIM_FILE_HOOK, LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK, LDPT_REGISTER_CLEANUP_HOOK, LDPT_ADD_SYMBOLS, LDPT_GET_INPUT_FILE, LDPT_RELEASE_INPUT_FILE, LDPT_GET_SYMBOLS, LDPT_ADD_INPUT_FILE, LDPT_ADD_INPUT_LIBRARY, LDPT_SET_EXTRA_LIBRARY_PATH }; /* How many entries in the constant leading part of the tv array. */ static const size_t tv_header_size = ARRAY_SIZE (tv_header_tags); #if !defined (HAVE_DLFCN_H) && defined (HAVE_WINDOWS_H) #define RTLD_NOW 0 /* Dummy value. */ static void * dlopen (const char *file, int mode ATTRIBUTE_UNUSED) { return LoadLibrary (file); } static void * dlsym (void *handle, const char *name) { return GetProcAddress (handle, name); } static int dlclose (void *handle) { FreeLibrary (handle); return 0; } #endif /* !defined (HAVE_DLFCN_H) && defined (HAVE_WINDOWS_H) */ /* Helper function for exiting with error status. */ static int set_plugin_error (const char *plugin) { error_plugin = plugin; return -1; } /* Test if an error occurred. */ static bfd_boolean plugin_error_p (void) { return error_plugin != NULL; } /* Return name of plugin which caused an error if any. */ const char * plugin_error_plugin (void) { return error_plugin ? error_plugin : _(""); } /* Handle -plugin arg: find and load plugin, or return error. */ int plugin_opt_plugin (const char *plugin) { plugin_t *newplug; newplug = xmalloc (sizeof *newplug); memset (newplug, 0, sizeof *newplug); newplug->name = plugin; newplug->dlhandle = dlopen (plugin, RTLD_NOW); if (!newplug->dlhandle) return set_plugin_error (plugin); /* Chain on end, so when we run list it is in command-line order. */ *plugins_tail_chain_ptr = newplug; plugins_tail_chain_ptr = &newplug->next; /* Record it as current plugin for receiving args. */ last_plugin = newplug; last_plugin_args_tail_chain_ptr = &newplug->args; return 0; } /* Accumulate option arguments for last-loaded plugin, or return error if none. */ int plugin_opt_plugin_arg (const char *arg) { plugin_arg_t *newarg; if (!last_plugin) return set_plugin_error (_("")); newarg = xmalloc (sizeof *newarg); newarg->arg = arg; newarg->next = NULL; /* Chain on end to preserve command-line order. */ *last_plugin_args_tail_chain_ptr = newarg; last_plugin_args_tail_chain_ptr = &newarg->next; last_plugin->n_args++; return 0; } /* Create a dummy BFD. */ bfd * plugin_get_ir_dummy_bfd (const char *name, bfd *srctemplate) { asection *sec; bfd *abfd; bfd_use_reserved_id = 1; abfd = bfd_create (concat (name, IRONLY_SUFFIX, (const char *)NULL), srctemplate); bfd_set_arch_info (abfd, bfd_get_arch_info (srctemplate)); bfd_make_writable (abfd); /* Create a minimal set of sections to own the symbols. */ sec = bfd_make_section_old_way (abfd, ".text"); bfd_set_section_flags (abfd, sec, (SEC_CODE | SEC_HAS_CONTENTS | SEC_READONLY | SEC_ALLOC | SEC_LOAD | SEC_KEEP)); sec->output_section = sec; sec->output_offset = 0; return abfd; } /* Check if the BFD passed in is an IR dummy object file. */ static bfd_boolean is_ir_dummy_bfd (const bfd *abfd) { size_t namlen; if (abfd == NULL) return FALSE; namlen = strlen (abfd->filename); if (namlen < IRONLY_SUFFIX_LEN) return FALSE; return !strcmp (abfd->filename + namlen - IRONLY_SUFFIX_LEN, IRONLY_SUFFIX); } /* Helpers to convert between BFD and GOLD symbol formats. */ static enum ld_plugin_status asymbol_from_plugin_symbol (bfd *abfd, asymbol *asym, const struct ld_plugin_symbol *ldsym) { flagword flags = BSF_NO_FLAGS; struct bfd_section *section; asym->the_bfd = abfd; asym->name = (ldsym->version ? concat (ldsym->name, "@", ldsym->version, NULL) : ldsym->name); asym->value = 0; switch (ldsym->def) { case LDPK_WEAKDEF: flags = BSF_WEAK; /* FALLTHRU */ case LDPK_DEF: flags |= BSF_GLOBAL; section = bfd_get_section_by_name (abfd, ".text"); break; case LDPK_WEAKUNDEF: flags = BSF_WEAK; /* FALLTHRU */ case LDPK_UNDEF: section = bfd_und_section_ptr; break; case LDPK_COMMON: flags = BSF_GLOBAL; section = bfd_com_section_ptr; asym->value = ldsym->size; /* For ELF targets, set alignment of common symbol to 1. */ if (bfd_get_flavour (abfd) == bfd_target_elf_flavour) ((elf_symbol_type *) asym)->internal_elf_sym.st_value = 1; break; default: return LDPS_ERR; } asym->flags = flags; asym->section = section; /* Visibility only applies on ELF targets. */ if (bfd_get_flavour (abfd) == bfd_target_elf_flavour) { elf_symbol_type *elfsym = elf_symbol_from (abfd, asym); unsigned char visibility; if (!elfsym) einfo (_("%P%F: %s: non-ELF symbol in ELF BFD!\n"), asym->name); switch (ldsym->visibility) { default: einfo (_("%P%F: unknown ELF symbol visibility: %d!\n"), ldsym->visibility); case LDPV_DEFAULT: visibility = STV_DEFAULT; break; case LDPV_PROTECTED: visibility = STV_PROTECTED; break; case LDPV_INTERNAL: visibility = STV_INTERNAL; break; case LDPV_HIDDEN: visibility = STV_HIDDEN; break; } elfsym->internal_elf_sym.st_other = (visibility | (elfsym->internal_elf_sym.st_other & ~ELF_ST_VISIBILITY (-1))); } return LDPS_OK; } /* Register a claim-file handler. */ static enum ld_plugin_status register_claim_file (ld_plugin_claim_file_handler handler) { ASSERT (called_plugin); called_plugin->claim_file_handler = handler; return LDPS_OK; } /* Register an all-symbols-read handler. */ static enum ld_plugin_status register_all_symbols_read (ld_plugin_all_symbols_read_handler handler) { ASSERT (called_plugin); called_plugin->all_symbols_read_handler = handler; return LDPS_OK; } /* Register a cleanup handler. */ static enum ld_plugin_status register_cleanup (ld_plugin_cleanup_handler handler) { ASSERT (called_plugin); called_plugin->cleanup_handler = handler; return LDPS_OK; } /* Add symbols from a plugin-claimed input file. */ static enum ld_plugin_status add_symbols (void *handle, int nsyms, const struct ld_plugin_symbol *syms) { asymbol **symptrs; bfd *abfd = handle; int n; ASSERT (called_plugin); symptrs = xmalloc (nsyms * sizeof *symptrs); for (n = 0; n < nsyms; n++) { enum ld_plugin_status rv; asymbol *bfdsym = bfd_make_empty_symbol (abfd); symptrs[n] = bfdsym; rv = asymbol_from_plugin_symbol (abfd, bfdsym, syms + n); if (rv != LDPS_OK) return rv; } bfd_set_symtab (abfd, symptrs, nsyms); return LDPS_OK; } /* Get the input file information with an open (possibly re-opened) file descriptor. */ static enum ld_plugin_status get_input_file (const void *handle, struct ld_plugin_input_file *file) { ASSERT (called_plugin); handle = handle; file = file; return LDPS_ERR; } /* Release the input file. */ static enum ld_plugin_status release_input_file (const void *handle) { ASSERT (called_plugin); handle = handle; return LDPS_ERR; } /* Return TRUE if a defined symbol might be reachable from outside the universe of claimed objects. */ static inline bfd_boolean is_visible_from_outside (struct ld_plugin_symbol *lsym, asection *section, struct bfd_link_hash_entry *blhe) { /* Section's owner may be NULL if it is the absolute section, fortunately is_ir_dummy_bfd handles that. */ if (!is_ir_dummy_bfd (section->owner)) return TRUE; if (link_info.relocatable) return TRUE; if (link_info.export_dynamic || link_info.shared) { /* Only ELF symbols really have visibility. */ if (bfd_get_flavour (link_info.output_bfd) == bfd_target_elf_flavour) { struct elf_link_hash_entry *el = (struct elf_link_hash_entry *)blhe; int vis = ELF_ST_VISIBILITY (el->other); return vis == STV_DEFAULT || vis == STV_PROTECTED; } /* On non-ELF targets, we can safely make inferences by considering what visibility the plugin would have liked to apply when it first sent us the symbol. During ELF symbol processing, visibility only ever becomes more restrictive, not less, when symbols are merged, so this is a conservative estimate; it may give false positives, declaring something visible from outside when it in fact would not have been, but this will only lead to missed optimisation opportunities during LTRANS at worst; it will not give false negatives, which can lead to the disastrous conclusion that the related symbol is IRONLY. (See GCC PR46319 for an example.) */ return (lsym->visibility == LDPV_DEFAULT || lsym->visibility == LDPV_PROTECTED); } return FALSE; } /* Get the symbol resolution info for a plugin-claimed input file. */ static enum ld_plugin_status get_symbols (const void *handle, int nsyms, struct ld_plugin_symbol *syms) { const bfd *abfd = handle; int n; ASSERT (called_plugin); for (n = 0; n < nsyms; n++) { struct bfd_link_hash_entry *blhe; bfd_boolean ironly; asection *owner_sec; blhe = bfd_link_hash_lookup (link_info.hash, syms[n].name, FALSE, FALSE, TRUE); if (!blhe) { syms[n].resolution = LDPR_UNKNOWN; continue; } /* Determine resolution from blhe type and symbol's original type. */ if (blhe->type == bfd_link_hash_undefined || blhe->type == bfd_link_hash_undefweak) { syms[n].resolution = LDPR_UNDEF; continue; } if (blhe->type != bfd_link_hash_defined && blhe->type != bfd_link_hash_defweak && blhe->type != bfd_link_hash_common) { /* We should not have a new, indirect or warning symbol here. */ einfo ("%P%F: %s: plugin symbol table corrupt (sym type %d)\n", called_plugin->name, blhe->type); } /* Find out which section owns the symbol. Since it's not undef, it must have an owner; if it's not a common symbol, both defs and weakdefs keep it in the same place. */ owner_sec = (blhe->type == bfd_link_hash_common) ? blhe->u.c.p->section : blhe->u.def.section; /* We need to know if the sym is referenced from non-IR files. Or even potentially-referenced, perhaps in a future final link if this is a partial one, perhaps dynamically at load-time if the symbol is externally visible. */ ironly = !is_visible_from_outside (&syms[n], owner_sec, blhe) && !bfd_hash_lookup (non_ironly_hash, syms[n].name, FALSE, FALSE); /* If it was originally undefined or common, then it has been resolved; determine how. */ if (syms[n].def == LDPK_UNDEF || syms[n].def == LDPK_WEAKUNDEF || syms[n].def == LDPK_COMMON) { if (owner_sec->owner == link_info.output_bfd) syms[n].resolution = LDPR_RESOLVED_EXEC; else if (owner_sec->owner == abfd) syms[n].resolution = (ironly ? LDPR_PREVAILING_DEF_IRONLY : LDPR_PREVAILING_DEF); else if (is_ir_dummy_bfd (owner_sec->owner)) syms[n].resolution = LDPR_RESOLVED_IR; else if (owner_sec->owner->flags & DYNAMIC) syms[n].resolution = LDPR_RESOLVED_DYN; else syms[n].resolution = LDPR_RESOLVED_EXEC; continue; } /* Was originally def, or weakdef. Does it prevail? If the owner is the original dummy bfd that supplied it, then this is the definition that has prevailed. */ if (owner_sec->owner == link_info.output_bfd) syms[n].resolution = LDPR_PREEMPTED_REG; else if (owner_sec->owner == abfd) { syms[n].resolution = (ironly ? LDPR_PREVAILING_DEF_IRONLY : LDPR_PREVAILING_DEF); continue; } /* Was originally def, weakdef, or common, but has been pre-empted. */ syms[n].resolution = is_ir_dummy_bfd (owner_sec->owner) ? LDPR_PREEMPTED_IR : LDPR_PREEMPTED_REG; } return LDPS_OK; } /* Add a new (real) input file generated by a plugin. */ static enum ld_plugin_status add_input_file (const char *pathname) { ASSERT (called_plugin); if (!lang_add_input_file (xstrdup (pathname), lang_input_file_is_file_enum, NULL)) return LDPS_ERR; return LDPS_OK; } /* Add a new (real) library required by a plugin. */ static enum ld_plugin_status add_input_library (const char *pathname) { ASSERT (called_plugin); if (!lang_add_input_file (xstrdup (pathname), lang_input_file_is_l_enum, NULL)) return LDPS_ERR; return LDPS_OK; } /* Set the extra library path to be used by libraries added via add_input_library. */ static enum ld_plugin_status set_extra_library_path (const char *path) { ASSERT (called_plugin); ldfile_add_library_path (xstrdup (path), FALSE); return LDPS_OK; } /* Issue a diagnostic message from a plugin. */ static enum ld_plugin_status message (int level, const char *format, ...) { va_list args; va_start (args, format); switch (level) { case LDPL_INFO: vfinfo (stdout, format, args, FALSE); break; case LDPL_WARNING: vfinfo (stdout, format, args, TRUE); break; case LDPL_FATAL: case LDPL_ERROR: default: { char *newfmt = ACONCAT ((level == LDPL_FATAL ? "%P%F: " : "%P%X: ", format, "\n", NULL)); vfinfo (stderr, newfmt, args, TRUE); } break; } putchar('\n'); va_end (args); return LDPS_OK; } /* Helper to size leading part of tv array and set it up. */ static size_t set_tv_header (struct ld_plugin_tv *tv) { size_t i; /* Version info. */ static const unsigned int major = (unsigned)(BFD_VERSION / 100000000UL); static const unsigned int minor = (unsigned)(BFD_VERSION / 1000000UL) % 100; if (!tv) return tv_header_size; for (i = 0; i < tv_header_size; i++) { tv[i].tv_tag = tv_header_tags[i]; #define TVU(x) tv[i].tv_u.tv_ ## x switch (tv[i].tv_tag) { case LDPT_MESSAGE: TVU(message) = message; break; case LDPT_API_VERSION: TVU(val) = LD_PLUGIN_API_VERSION; break; case LDPT_GNU_LD_VERSION: TVU(val) = major * 100 + minor; break; case LDPT_LINKER_OUTPUT: TVU(val) = (link_info.relocatable ? LDPO_REL : (link_info.shared ? LDPO_DYN : LDPO_EXEC)); break; case LDPT_OUTPUT_NAME: TVU(string) = output_filename; break; case LDPT_REGISTER_CLAIM_FILE_HOOK: TVU(register_claim_file) = register_claim_file; break; case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: TVU(register_all_symbols_read) = register_all_symbols_read; break; case LDPT_REGISTER_CLEANUP_HOOK: TVU(register_cleanup) = register_cleanup; break; case LDPT_ADD_SYMBOLS: TVU(add_symbols) = add_symbols; break; case LDPT_GET_INPUT_FILE: TVU(get_input_file) = get_input_file; break; case LDPT_RELEASE_INPUT_FILE: TVU(release_input_file) = release_input_file; break; case LDPT_GET_SYMBOLS: TVU(get_symbols) = get_symbols; break; case LDPT_ADD_INPUT_FILE: TVU(add_input_file) = add_input_file; break; case LDPT_ADD_INPUT_LIBRARY: TVU(add_input_library) = add_input_library; break; case LDPT_SET_EXTRA_LIBRARY_PATH: TVU(set_extra_library_path) = set_extra_library_path; break; default: /* Added a new entry to the array without adding a new case to set up its value is a bug. */ FAIL (); } #undef TVU } return tv_header_size; } /* Append the per-plugin args list and trailing LDPT_NULL to tv. */ static void set_tv_plugin_args (plugin_t *plugin, struct ld_plugin_tv *tv) { plugin_arg_t *arg = plugin->args; while (arg) { tv->tv_tag = LDPT_OPTION; tv->tv_u.tv_string = arg->arg; arg = arg->next; tv++; } tv->tv_tag = LDPT_NULL; tv->tv_u.tv_val = 0; } /* Return true if any plugins are active this run. Only valid after options have been processed. */ bfd_boolean plugin_active_plugins_p (void) { return plugins_list != NULL; } /* Load up and initialise all plugins after argument parsing. */ int plugin_load_plugins (void) { struct ld_plugin_tv *my_tv; unsigned int max_args = 0; plugin_t *curplug = plugins_list; /* If there are no plugins, we need do nothing this run. */ if (!curplug) return 0; xatexit (plugin_call_cleanup); /* First pass over plugins to find max # args needed so that we can size and allocate the tv array. */ while (curplug) { if (curplug->n_args > max_args) max_args = curplug->n_args; curplug = curplug->next; } /* Allocate tv array and initialise constant part. */ my_tv = xmalloc ((max_args + 1 + tv_header_size) * sizeof *my_tv); set_tv_header (my_tv); /* Pass over plugins again, activating them. */ curplug = plugins_list; while (curplug) { enum ld_plugin_status rv; ld_plugin_onload onloadfn = dlsym (curplug->dlhandle, "onload"); if (!onloadfn) onloadfn = dlsym (curplug->dlhandle, "_onload"); if (!onloadfn) return set_plugin_error (curplug->name); set_tv_plugin_args (curplug, &my_tv[tv_header_size]); called_plugin = curplug; rv = (*onloadfn) (my_tv); called_plugin = NULL; if (rv != LDPS_OK) return set_plugin_error (curplug->name); curplug = curplug->next; } /* Since plugin(s) inited ok, assume they're going to want symbol resolutions, which needs us to track which symbols are referenced by non-IR files using the linker's notice callback. */ link_info.notice_all = TRUE; return 0; } /* Call 'claim file' hook for all plugins. */ int plugin_call_claim_file (const struct ld_plugin_input_file *file, int *claimed) { plugin_t *curplug = plugins_list; *claimed = FALSE; if (no_more_claiming) return 0; while (curplug && !*claimed) { if (curplug->claim_file_handler) { enum ld_plugin_status rv; called_plugin = curplug; rv = (*curplug->claim_file_handler) (file, claimed); called_plugin = NULL; if (rv != LDPS_OK) set_plugin_error (curplug->name); } curplug = curplug->next; } return plugin_error_p () ? -1 : 0; } /* Call 'all symbols read' hook for all plugins. */ int plugin_call_all_symbols_read (void) { plugin_t *curplug = plugins_list; /* Disable any further file-claiming. */ no_more_claiming = TRUE; /* If --allow-multiple-definition is in effect, we need to disable it, as the plugin infrastructure relies on the multiple_definition callback to swap out the dummy IR-only BFDs for new real ones when it starts opening the files added during this callback. */ plugin_cached_allow_multiple_defs = link_info.allow_multiple_definition; link_info.allow_multiple_definition = FALSE; while (curplug) { if (curplug->all_symbols_read_handler) { enum ld_plugin_status rv; called_plugin = curplug; rv = (*curplug->all_symbols_read_handler) (); called_plugin = NULL; if (rv != LDPS_OK) set_plugin_error (curplug->name); } curplug = curplug->next; } return plugin_error_p () ? -1 : 0; } /* Call 'cleanup' hook for all plugins at exit. */ static void plugin_call_cleanup (void) { plugin_t *curplug = plugins_list; while (curplug) { if (curplug->cleanup_handler && !curplug->cleanup_done) { enum ld_plugin_status rv; curplug->cleanup_done = TRUE; called_plugin = curplug; rv = (*curplug->cleanup_handler) (); called_plugin = NULL; if (rv != LDPS_OK) set_plugin_error (curplug->name); dlclose (curplug->dlhandle); } curplug = curplug->next; } if (plugin_error_p ()) info_msg (_("%P: %s: error in plugin cleanup (ignored)\n"), plugin_error_plugin ()); } /* Lazily init the non_ironly hash table. */ static void init_non_ironly_hash (void) { if (non_ironly_hash == NULL) { non_ironly_hash = (struct bfd_hash_table *) xmalloc (sizeof (struct bfd_hash_table)); if (!bfd_hash_table_init_n (non_ironly_hash, bfd_hash_newfunc, sizeof (struct bfd_hash_entry), 61)) einfo (_("%P%F: bfd_hash_table_init failed: %E\n")); } } /* To determine which symbols should be resolved LDPR_PREVAILING_DEF and which LDPR_PREVAILING_DEF_IRONLY, we notice all the symbols as the linker adds them to the linker hash table. If we see a symbol being referenced from a non-IR file, we add it to the non_ironly hash table. If we can't find it there at get_symbols time, we know that it was referenced only by IR files. We have to notice_all symbols, because we won't necessarily know until later which ones will be contributed by IR files. */ bfd_boolean plugin_notice (struct bfd_link_info *info ATTRIBUTE_UNUSED, const char *name, bfd *abfd, asection *section, bfd_vma value ATTRIBUTE_UNUSED) { bfd_boolean is_ref = bfd_is_und_section (section); bfd_boolean is_dummy = is_ir_dummy_bfd (abfd); init_non_ironly_hash (); /* We only care about refs, not defs, indicated by section pointing to the undefined section (according to the bfd linker notice callback interface definition). */ if (is_ref && !is_dummy) { /* This is a ref from a non-IR file, so note the ref'd symbol in the non-IR-only hash. */ if (!bfd_hash_lookup (non_ironly_hash, name, TRUE, TRUE)) einfo (_("%P%X: %s: hash table failure adding symbol %s\n"), abfd->filename, name); } else if (!is_ref && is_dummy) { /* No further processing since this is a def from an IR dummy BFD. */ return FALSE; } /* Continue with cref/nocrossref/trace-sym processing. */ return TRUE; } /* When we add new object files to the link at all symbols read time, these contain the real code and symbols generated from the IR files, and so duplicate all the definitions already supplied by the dummy IR-only BFDs that we created at claim files time. We use the linker's multiple-definitions callback hook to fix up the clash, discarding the symbol from the IR-only BFD in favour of the symbol from the real BFD. We return true if this was not-really-a-clash because we've fixed it up, or anyway if --allow-multiple-definition was in effect (before we disabled it to ensure we got called back). */ bfd_boolean plugin_multiple_definition (struct bfd_link_info *info, const char *name, bfd *obfd, asection *osec ATTRIBUTE_UNUSED, bfd_vma oval ATTRIBUTE_UNUSED, bfd *nbfd, asection *nsec, bfd_vma nval) { if (is_ir_dummy_bfd (obfd)) { struct bfd_link_hash_entry *blhe = bfd_link_hash_lookup (info->hash, name, FALSE, FALSE, FALSE); if (!blhe) einfo (_("%P%X: %s: can't find IR symbol '%s'\n"), nbfd->filename, name); else if (blhe->type != bfd_link_hash_defined) einfo (_("%P%x: %s: bad IR symbol type %d\n"), name, blhe->type); /* Replace it with new details. */ blhe->u.def.section = nsec; blhe->u.def.value = nval; return TRUE; } return plugin_cached_allow_multiple_defs; }