ld/plugin.c

   1 /* Plugin control for the GNU linker.
   2    Copyright 2010, 2011 Free Software Foundation, Inc.
   3
   4    This file is part of the GNU Binutils.
   5
   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.
  10
  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.
  15
  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.  */
  20
  21 #include "sysdep.h"
  22 #include "libiberty.h"
  23 #include "bfd.h"
  24 #include "bfdlink.h"
  25 #include "bfdver.h"
  26 #include "ld.h"
  27 #include "ldmain.h"
  28 #include "ldmisc.h"
  29 #include "ldexp.h"
  30 #include "ldlang.h"
  31 #include "ldfile.h"
  32 #include "plugin.h"
  33 #include "plugin-api.h"
  34 #include "elf-bfd.h"
  35 #if !defined (HAVE_DLFCN_H) && defined (HAVE_WINDOWS_H)
  36 #include <Windows.h>
  37 #endif
  38
  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
  41    plugin.  */
  42 #define IRONLY_SUFFIX           ".ironly\004"
  43
  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)
  47
  48 /* Stores a single argument passed to a plugin.  */
  49 typedef struct plugin_arg
  50 {
  51   struct plugin_arg *next;
  52   const char *arg;
  53 } plugin_arg_t;
  54
  55 /* Holds all details of a single plugin.  */
  56 typedef struct plugin
  57 {
  58   /* Next on the list of plugins, or NULL at end of chain.  */
  59   struct plugin *next;
  60   /* The argument string given to --plugin.  */
  61   const char *name;
  62   /* The shared library handle returned by dlopen.  */
  63   void *dlhandle;
  64   /* The list of argument string given to --plugin-opt.  */
  65   plugin_arg_t *args;
  66   /* Number of args in the list, for convenience.  */
  67   size_t n_args;
  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;
  74 } plugin_t;
  75
  76 /* The master list of all plugins.  */
  77 static plugin_t *plugins_list = NULL;
  78
  79 /* We keep a tail pointer for easy linking on the end.  */
  80 static plugin_t **plugins_tail_chain_ptr = &plugins_list;
  81
  82 /* The last plugin added to the list, for receiving args.  */
  83 static plugin_t *last_plugin = NULL;
  84
  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;
  87
  88 /* The plugin which is currently having a callback executed.  */
  89 static plugin_t *called_plugin = NULL;
  90
  91 /* Last plugin to cause an error, if any.  */
  92 static const char *error_plugin = NULL;
  93
  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;
 100
 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;
 104
 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;
 110
 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[] =
 113 {
 114   LDPT_MESSAGE,
 115   LDPT_API_VERSION,
 116   LDPT_GNU_LD_VERSION,
 117   LDPT_LINKER_OUTPUT,
 118   LDPT_OUTPUT_NAME,
 119   LDPT_REGISTER_CLAIM_FILE_HOOK,
 120   LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK,
 121   LDPT_REGISTER_CLEANUP_HOOK,
 122   LDPT_ADD_SYMBOLS,
 123   LDPT_GET_INPUT_FILE,
 124   LDPT_RELEASE_INPUT_FILE,
 125   LDPT_GET_SYMBOLS,
 126   LDPT_ADD_INPUT_FILE,
 127   LDPT_ADD_INPUT_LIBRARY,
 128   LDPT_SET_EXTRA_LIBRARY_PATH
 129 };
 130
 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);
 133
 134 #if !defined (HAVE_DLFCN_H) && defined (HAVE_WINDOWS_H)
 135
 136 #define RTLD_NOW 0      /* Dummy value.  */
 137
 138 static void *
 139 dlopen (const char *file, int mode ATTRIBUTE_UNUSED)
 140 {
 141   return LoadLibrary (file);
 142 }
 143
 144 static void *
 145 dlsym (void *handle, const char *name)
 146 {
 147   return GetProcAddress (handle, name);
 148 }
 149
 150 static int
 151 dlclose (void *handle)
 152 {
 153   FreeLibrary (handle);
 154   return 0;
 155 }
 156
 157 #endif /* !defined (HAVE_DLFCN_H) && defined (HAVE_WINDOWS_H)  */
 158
 159 /* Helper function for exiting with error status.  */
 160 static int
 161 set_plugin_error (const char *plugin)
 162 {
 163   error_plugin = plugin;
 164   return -1;
 165 }
 166
 167 /* Test if an error occurred.  */
 168 static bfd_boolean
 169 plugin_error_p (void)
 170 {
 171   return error_plugin != NULL;
 172 }
 173
 174 /* Return name of plugin which caused an error if any.  */
 175 const char *
 176 plugin_error_plugin (void)
 177 {
 178   return error_plugin ? error_plugin : _("<no plugin>");
 179 }
 180
 181 /* Handle -plugin arg: find and load plugin, or return error.  */
 182 int
 183 plugin_opt_plugin (const char *plugin)
 184 {
 185   plugin_t *newplug;
 186
 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);
 193
 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;
 197
 198   /* Record it as current plugin for receiving args.  */
 199   last_plugin = newplug;
 200   last_plugin_args_tail_chain_ptr = &newplug->args;
 201   return 0;
 202 }
 203
 204 /* Accumulate option arguments for last-loaded plugin, or return
 205    error if none.  */
 206 int
 207 plugin_opt_plugin_arg (const char *arg)
 208 {
 209   plugin_arg_t *newarg;
 210
 211   if (!last_plugin)
 212     return set_plugin_error (_("<no plugin>"));
 213
 214   newarg = xmalloc (sizeof *newarg);
 215   newarg->arg = arg;
 216   newarg->next = NULL;
 217
 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++;
 222   return 0;
 223 }
 224
 225 /* Create a dummy BFD.  */
 226 bfd *
 227 plugin_get_ir_dummy_bfd (const char *name, bfd *srctemplate)
 228 {
 229   asection *sec;
 230   bfd *abfd;
 231
 232   bfd_use_reserved_id = 1;
 233   abfd = bfd_create (concat (name, IRONLY_SUFFIX, (const char *)NULL),
 234                      srctemplate);
 235   bfd_set_arch_info (abfd, bfd_get_arch_info (srctemplate));
 236   bfd_make_writable (abfd);
 237   bfd_copy_private_bfd_data (srctemplate, abfd);
 238   bfd_set_gp_size (abfd, bfd_get_gp_size (abfd));
 239   /* Create a minimal set of sections to own the symbols.  */
 240   sec = bfd_make_section_old_way (abfd, ".text");
 241   bfd_set_section_flags (abfd, sec,
 242                          (SEC_CODE | SEC_HAS_CONTENTS | SEC_READONLY
 243                           | SEC_ALLOC | SEC_LOAD | SEC_KEEP));
 244   sec->output_section = sec;
 245   sec->output_offset = 0;
 246   return abfd;
 247 }
 248
 249 /* Check if the BFD passed in is an IR dummy object file.  */
 250 static bfd_boolean
 251 is_ir_dummy_bfd (const bfd *abfd)
 252 {
 253   size_t namlen;
 254
 255   if (abfd == NULL)
 256     return FALSE;
 257   namlen = strlen (abfd->filename);
 258   if (namlen < IRONLY_SUFFIX_LEN)
 259     return FALSE;
 260   return !strcmp (abfd->filename + namlen - IRONLY_SUFFIX_LEN, IRONLY_SUFFIX);
 261 }
 262
 263 /* Helpers to convert between BFD and GOLD symbol formats.  */
 264 static enum ld_plugin_status
 265 asymbol_from_plugin_symbol (bfd *abfd, asymbol *asym,
 266                             const struct ld_plugin_symbol *ldsym)
 267 {
 268   flagword flags = BSF_NO_FLAGS;
 269   struct bfd_section *section;
 270
 271   asym->the_bfd = abfd;
 272   asym->name = (ldsym->version
 273                 ? concat (ldsym->name, "@", ldsym->version, NULL)
 274                 : ldsym->name);
 275   asym->value = 0;
 276   switch (ldsym->def)
 277     {
 278     case LDPK_WEAKDEF:
 279       flags = BSF_WEAK;
 280       /* FALLTHRU */
 281     case LDPK_DEF:
 282       flags |= BSF_GLOBAL;
 283       section = bfd_get_section_by_name (abfd, ".text");
 284       break;
 285
 286     case LDPK_WEAKUNDEF:
 287       flags = BSF_WEAK;
 288       /* FALLTHRU */
 289     case LDPK_UNDEF:
 290       section = bfd_und_section_ptr;
 291       break;
 292
 293     case LDPK_COMMON:
 294       flags = BSF_GLOBAL;
 295       section = bfd_com_section_ptr;
 296       asym->value = ldsym->size;
 297       /* For ELF targets, set alignment of common symbol to 1.  */
 298       if (bfd_get_flavour (abfd) == bfd_target_elf_flavour)
 299         ((elf_symbol_type *) asym)->internal_elf_sym.st_value = 1;
 300       break;
 301
 302     default:
 303       return LDPS_ERR;
 304     }
 305   asym->flags = flags;
 306   asym->section = section;
 307
 308   /* Visibility only applies on ELF targets.  */
 309   if (bfd_get_flavour (abfd) == bfd_target_elf_flavour)
 310     {
 311       elf_symbol_type *elfsym = elf_symbol_from (abfd, asym);
 312       unsigned char visibility;
 313
 314       if (!elfsym)
 315         einfo (_("%P%F: %s: non-ELF symbol in ELF BFD!\n"), asym->name);
 316       switch (ldsym->visibility)
 317         {
 318         default:
 319           einfo (_("%P%F: unknown ELF symbol visibility: %d!\n"),
 320                  ldsym->visibility);
 321         case LDPV_DEFAULT:
 322           visibility = STV_DEFAULT;
 323           break;
 324         case LDPV_PROTECTED:
 325           visibility = STV_PROTECTED;
 326           break;
 327         case LDPV_INTERNAL:
 328           visibility = STV_INTERNAL;
 329           break;
 330         case LDPV_HIDDEN:
 331           visibility = STV_HIDDEN;
 332           break;
 333         }
 334       elfsym->internal_elf_sym.st_other
 335         = (visibility | (elfsym->internal_elf_sym.st_other
 336                          & ~ELF_ST_VISIBILITY (-1)));
 337     }
 338
 339   return LDPS_OK;
 340 }
 341
 342 /* Register a claim-file handler.  */
 343 static enum ld_plugin_status
 344 register_claim_file (ld_plugin_claim_file_handler handler)
 345 {
 346   ASSERT (called_plugin);
 347   called_plugin->claim_file_handler = handler;
 348   return LDPS_OK;
 349 }
 350
 351 /* Register an all-symbols-read handler.  */
 352 static enum ld_plugin_status
 353 register_all_symbols_read (ld_plugin_all_symbols_read_handler handler)
 354 {
 355   ASSERT (called_plugin);
 356   called_plugin->all_symbols_read_handler = handler;
 357   return LDPS_OK;
 358 }
 359
 360 /* Register a cleanup handler.  */
 361 static enum ld_plugin_status
 362 register_cleanup (ld_plugin_cleanup_handler handler)
 363 {
 364   ASSERT (called_plugin);
 365   called_plugin->cleanup_handler = handler;
 366   return LDPS_OK;
 367 }
 368
 369 /* Add symbols from a plugin-claimed input file.  */
 370 static enum ld_plugin_status
 371 add_symbols (void *handle, int nsyms, const struct ld_plugin_symbol *syms)
 372 {
 373   asymbol **symptrs;
 374   bfd *abfd = handle;
 375   int n;
 376   ASSERT (called_plugin);
 377   symptrs = xmalloc (nsyms * sizeof *symptrs);
 378   for (n = 0; n < nsyms; n++)
 379     {
 380       enum ld_plugin_status rv;
 381       asymbol *bfdsym = bfd_make_empty_symbol (abfd);
 382       symptrs[n] = bfdsym;
 383       rv = asymbol_from_plugin_symbol (abfd, bfdsym, syms + n);
 384       if (rv != LDPS_OK)
 385         return rv;
 386     }
 387   bfd_set_symtab (abfd, symptrs, nsyms);
 388   return LDPS_OK;
 389 }
 390
 391 /* Get the input file information with an open (possibly re-opened)
 392    file descriptor.  */
 393 static enum ld_plugin_status
 394 get_input_file (const void *handle, struct ld_plugin_input_file *file)
 395 {
 396   ASSERT (called_plugin);
 397   handle = handle;
 398   file = file;
 399   return LDPS_ERR;
 400 }
 401
 402 /* Release the input file.  */
 403 static enum ld_plugin_status
 404 release_input_file (const void *handle)
 405 {
 406   ASSERT (called_plugin);
 407   handle = handle;
 408   return LDPS_ERR;
 409 }
 410
 411 /* Return TRUE if a defined symbol might be reachable from outside the
 412    universe of claimed objects.  */
 413 static inline bfd_boolean
 414 is_visible_from_outside (struct ld_plugin_symbol *lsym, asection *section,
 415                          struct bfd_link_hash_entry *blhe)
 416 {
 417   /* Section's owner may be NULL if it is the absolute
 418      section, fortunately is_ir_dummy_bfd handles that.  */
 419   if (!is_ir_dummy_bfd (section->owner))
 420     return TRUE;
 421   if (link_info.relocatable)
 422     return TRUE;
 423   if (link_info.export_dynamic || link_info.shared)
 424     {
 425       /* Only ELF symbols really have visibility.  */
 426       if (bfd_get_flavour (link_info.output_bfd) == bfd_target_elf_flavour)
 427         {
 428           struct elf_link_hash_entry *el = (struct elf_link_hash_entry *)blhe;
 429           int vis = ELF_ST_VISIBILITY (el->other);
 430           return vis == STV_DEFAULT || vis == STV_PROTECTED;
 431         }
 432       /* On non-ELF targets, we can safely make inferences by considering
 433          what visibility the plugin would have liked to apply when it first
 434          sent us the symbol.  During ELF symbol processing, visibility only
 435          ever becomes more restrictive, not less, when symbols are merged,
 436          so this is a conservative estimate; it may give false positives,
 437          declaring something visible from outside when it in fact would
 438          not have been, but this will only lead to missed optimisation
 439          opportunities during LTRANS at worst; it will not give false
 440          negatives, which can lead to the disastrous conclusion that the
 441          related symbol is IRONLY.  (See GCC PR46319 for an example.)  */
 442       return (lsym->visibility == LDPV_DEFAULT
 443               || lsym->visibility == LDPV_PROTECTED);
 444     }
 445   return FALSE;
 446 }
 447
 448 /* Get the symbol resolution info for a plugin-claimed input file.  */
 449 static enum ld_plugin_status
 450 get_symbols (const void *handle, int nsyms, struct ld_plugin_symbol *syms)
 451 {
 452   const bfd *abfd = handle;
 453   int n;
 454   ASSERT (called_plugin);
 455   for (n = 0; n < nsyms; n++)
 456     {
 457       struct bfd_link_hash_entry *blhe;
 458       bfd_boolean ironly;
 459       asection *owner_sec;
 460
 461       blhe = bfd_link_hash_lookup (link_info.hash, syms[n].name,
 462                                    FALSE, FALSE, TRUE);
 463       if (!blhe)
 464         {
 465           syms[n].resolution = LDPR_UNKNOWN;
 466           continue;
 467         }
 468
 469       /* Determine resolution from blhe type and symbol's original type.  */
 470       if (blhe->type == bfd_link_hash_undefined
 471           || blhe->type == bfd_link_hash_undefweak)
 472         {
 473           syms[n].resolution = LDPR_UNDEF;
 474           continue;
 475         }
 476       if (blhe->type != bfd_link_hash_defined
 477           && blhe->type != bfd_link_hash_defweak
 478           && blhe->type != bfd_link_hash_common)
 479         {
 480           /* We should not have a new, indirect or warning symbol here.  */
 481           einfo ("%P%F: %s: plugin symbol table corrupt (sym type %d)\n",
 482                  called_plugin->name, blhe->type);
 483         }
 484
 485       /* Find out which section owns the symbol.  Since it's not undef,
 486          it must have an owner; if it's not a common symbol, both defs
 487          and weakdefs keep it in the same place. */
 488       owner_sec = (blhe->type == bfd_link_hash_common)
 489         ? blhe->u.c.p->section
 490         : blhe->u.def.section;
 491
 492       /* We need to know if the sym is referenced from non-IR files.  Or
 493          even potentially-referenced, perhaps in a future final link if
 494          this is a partial one, perhaps dynamically at load-time if the
 495          symbol is externally visible.  */
 496       ironly = (!is_visible_from_outside (&syms[n], owner_sec, blhe)
 497                 && !bfd_hash_lookup (non_ironly_hash, syms[n].name,
 498                                      FALSE, FALSE));
 499
 500       /* If it was originally undefined or common, then it has been
 501          resolved; determine how.  */
 502       if (syms[n].def == LDPK_UNDEF
 503           || syms[n].def == LDPK_WEAKUNDEF
 504           || syms[n].def == LDPK_COMMON)
 505         {
 506           if (owner_sec->owner == link_info.output_bfd)
 507             syms[n].resolution = LDPR_RESOLVED_EXEC;
 508           else if (owner_sec->owner == abfd)
 509             syms[n].resolution = (ironly
 510                                   ? LDPR_PREVAILING_DEF_IRONLY
 511                                   : LDPR_PREVAILING_DEF);
 512           else if (is_ir_dummy_bfd (owner_sec->owner))
 513             syms[n].resolution = LDPR_RESOLVED_IR;
 514           else if (owner_sec->owner != NULL
 515                    && (owner_sec->owner->flags & DYNAMIC) != 0)
 516             syms[n].resolution =  LDPR_RESOLVED_DYN;
 517           else
 518             syms[n].resolution = LDPR_RESOLVED_EXEC;
 519           continue;
 520         }
 521
 522       /* Was originally def, or weakdef.  Does it prevail?  If the
 523          owner is the original dummy bfd that supplied it, then this
 524          is the definition that has prevailed.  */
 525       if (owner_sec->owner == link_info.output_bfd)
 526         syms[n].resolution = LDPR_PREEMPTED_REG;
 527       else if (owner_sec->owner == abfd)
 528         {
 529           syms[n].resolution = (ironly
 530                                 ? LDPR_PREVAILING_DEF_IRONLY
 531                                 : LDPR_PREVAILING_DEF);
 532           continue;
 533         }
 534
 535       /* Was originally def, weakdef, or common, but has been pre-empted.  */
 536       syms[n].resolution = is_ir_dummy_bfd (owner_sec->owner)
 537         ? LDPR_PREEMPTED_IR
 538         : LDPR_PREEMPTED_REG;
 539     }
 540   return LDPS_OK;
 541 }
 542
 543 /* Add a new (real) input file generated by a plugin.  */
 544 static enum ld_plugin_status
 545 add_input_file (const char *pathname)
 546 {
 547   ASSERT (called_plugin);
 548   if (!lang_add_input_file (xstrdup (pathname), lang_input_file_is_file_enum,
 549                             NULL))
 550     return LDPS_ERR;
 551   return LDPS_OK;
 552 }
 553
 554 /* Add a new (real) library required by a plugin.  */
 555 static enum ld_plugin_status
 556 add_input_library (const char *pathname)
 557 {
 558   ASSERT (called_plugin);
 559   if (!lang_add_input_file (xstrdup (pathname), lang_input_file_is_l_enum,
 560                             NULL))
 561     return LDPS_ERR;
 562   return LDPS_OK;
 563 }
 564
 565 /* Set the extra library path to be used by libraries added via
 566    add_input_library.  */
 567 static enum ld_plugin_status
 568 set_extra_library_path (const char *path)
 569 {
 570   ASSERT (called_plugin);
 571   ldfile_add_library_path (xstrdup (path), FALSE);
 572   return LDPS_OK;
 573 }
 574
 575 /* Issue a diagnostic message from a plugin.  */
 576 static enum ld_plugin_status
 577 message (int level, const char *format, ...)
 578 {
 579   va_list args;
 580   va_start (args, format);
 581
 582   switch (level)
 583     {
 584     case LDPL_INFO:
 585       vfinfo (stdout, format, args, FALSE);
 586       putchar ('\n');
 587       break;
 588     case LDPL_WARNING:
 589       vfinfo (stdout, format, args, TRUE);
 590       putchar ('\n');
 591       break;
 592     case LDPL_FATAL:
 593     case LDPL_ERROR:
 594     default:
 595         {
 596           char *newfmt = ACONCAT ((level == LDPL_FATAL
 597                                    ? "%P%F: " : "%P%X: ",
 598                                    format, "\n", NULL));
 599           fflush (stdout);
 600           vfinfo (stderr, newfmt, args, TRUE);
 601           fflush (stderr);
 602         }
 603       break;
 604     }
 605
 606   va_end (args);
 607   return LDPS_OK;
 608 }
 609
 610 /* Helper to size leading part of tv array and set it up. */
 611 static size_t
 612 set_tv_header (struct ld_plugin_tv *tv)
 613 {
 614   size_t i;
 615
 616   /* Version info.  */
 617   static const unsigned int major = (unsigned)(BFD_VERSION / 100000000UL);
 618   static const unsigned int minor = (unsigned)(BFD_VERSION / 1000000UL) % 100;
 619
 620   if (!tv)
 621     return tv_header_size;
 622
 623   for (i = 0; i < tv_header_size; i++)
 624     {
 625       tv[i].tv_tag = tv_header_tags[i];
 626 #define TVU(x) tv[i].tv_u.tv_ ## x
 627       switch (tv[i].tv_tag)
 628         {
 629         case LDPT_MESSAGE:
 630           TVU(message) = message;
 631           break;
 632         case LDPT_API_VERSION:
 633           TVU(val) = LD_PLUGIN_API_VERSION;
 634           break;
 635         case LDPT_GNU_LD_VERSION:
 636           TVU(val) = major * 100 + minor;
 637           break;
 638         case LDPT_LINKER_OUTPUT:
 639           TVU(val) = (link_info.relocatable
 640                       ? LDPO_REL
 641                       : (link_info.shared ? LDPO_DYN : LDPO_EXEC));
 642           break;
 643         case LDPT_OUTPUT_NAME:
 644           TVU(string) = output_filename;
 645           break;
 646         case LDPT_REGISTER_CLAIM_FILE_HOOK:
 647           TVU(register_claim_file) = register_claim_file;
 648           break;
 649         case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK:
 650           TVU(register_all_symbols_read) = register_all_symbols_read;
 651           break;
 652         case LDPT_REGISTER_CLEANUP_HOOK:
 653           TVU(register_cleanup) = register_cleanup;
 654           break;
 655         case LDPT_ADD_SYMBOLS:
 656           TVU(add_symbols) = add_symbols;
 657           break;
 658         case LDPT_GET_INPUT_FILE:
 659           TVU(get_input_file) = get_input_file;
 660           break;
 661         case LDPT_RELEASE_INPUT_FILE:
 662           TVU(release_input_file) = release_input_file;
 663           break;
 664         case LDPT_GET_SYMBOLS:
 665           TVU(get_symbols) = get_symbols;
 666           break;
 667         case LDPT_ADD_INPUT_FILE:
 668           TVU(add_input_file) = add_input_file;
 669           break;
 670         case LDPT_ADD_INPUT_LIBRARY:
 671           TVU(add_input_library) = add_input_library;
 672           break;
 673         case LDPT_SET_EXTRA_LIBRARY_PATH:
 674           TVU(set_extra_library_path) = set_extra_library_path;
 675           break;
 676         default:
 677           /* Added a new entry to the array without adding
 678              a new case to set up its value is a bug.  */
 679           FAIL ();
 680         }
 681 #undef TVU
 682     }
 683   return tv_header_size;
 684 }
 685
 686 /* Append the per-plugin args list and trailing LDPT_NULL to tv.  */
 687 static void
 688 set_tv_plugin_args (plugin_t *plugin, struct ld_plugin_tv *tv)
 689 {
 690   plugin_arg_t *arg = plugin->args;
 691   while (arg)
 692     {
 693       tv->tv_tag = LDPT_OPTION;
 694       tv->tv_u.tv_string = arg->arg;
 695       arg = arg->next;
 696       tv++;
 697     }
 698   tv->tv_tag = LDPT_NULL;
 699   tv->tv_u.tv_val = 0;
 700 }
 701
 702 /* Return true if any plugins are active this run.  Only valid
 703    after options have been processed.  */
 704 bfd_boolean
 705 plugin_active_plugins_p (void)
 706 {
 707   return plugins_list != NULL;
 708 }
 709
 710 /* Load up and initialise all plugins after argument parsing.  */
 711 int
 712 plugin_load_plugins (void)
 713 {
 714   struct ld_plugin_tv *my_tv;
 715   unsigned int max_args = 0;
 716   plugin_t *curplug = plugins_list;
 717
 718   /* If there are no plugins, we need do nothing this run.  */
 719   if (!curplug)
 720     return 0;
 721
 722   /* First pass over plugins to find max # args needed so that we
 723      can size and allocate the tv array.  */
 724   while (curplug)
 725     {
 726       if (curplug->n_args > max_args)
 727         max_args = curplug->n_args;
 728       curplug = curplug->next;
 729     }
 730
 731   /* Allocate tv array and initialise constant part.  */
 732   my_tv = xmalloc ((max_args + 1 + tv_header_size) * sizeof *my_tv);
 733   set_tv_header (my_tv);
 734
 735   /* Pass over plugins again, activating them.  */
 736   curplug = plugins_list;
 737   while (curplug)
 738     {
 739       enum ld_plugin_status rv;
 740       ld_plugin_onload onloadfn = dlsym (curplug->dlhandle, "onload");
 741       if (!onloadfn)
 742         onloadfn = dlsym (curplug->dlhandle, "_onload");
 743       if (!onloadfn)
 744         return set_plugin_error (curplug->name);
 745       set_tv_plugin_args (curplug, &my_tv[tv_header_size]);
 746       called_plugin = curplug;
 747       rv = (*onloadfn) (my_tv);
 748       called_plugin = NULL;
 749       if (rv != LDPS_OK)
 750         return set_plugin_error (curplug->name);
 751       curplug = curplug->next;
 752     }
 753
 754   /* Since plugin(s) inited ok, assume they're going to want symbol
 755      resolutions, which needs us to track which symbols are referenced
 756      by non-IR files using the linker's notice callback.  */
 757   link_info.notice_all = TRUE;
 758
 759   return 0;
 760 }
 761
 762 /* Call 'claim file' hook for all plugins.  */
 763 int
 764 plugin_call_claim_file (const struct ld_plugin_input_file *file, int *claimed)
 765 {
 766   plugin_t *curplug = plugins_list;
 767   *claimed = FALSE;
 768   if (no_more_claiming)
 769     return 0;
 770   while (curplug && !*claimed)
 771     {
 772       if (curplug->claim_file_handler)
 773         {
 774           enum ld_plugin_status rv;
 775           called_plugin = curplug;
 776           rv = (*curplug->claim_file_handler) (file, claimed);
 777           called_plugin = NULL;
 778           if (rv != LDPS_OK)
 779             set_plugin_error (curplug->name);
 780         }
 781       curplug = curplug->next;
 782     }
 783   return plugin_error_p () ? -1 : 0;
 784 }
 785
 786 /* Call 'all symbols read' hook for all plugins.  */
 787 int
 788 plugin_call_all_symbols_read (void)
 789 {
 790   plugin_t *curplug = plugins_list;
 791
 792   /* Disable any further file-claiming.  */
 793   no_more_claiming = TRUE;
 794
 795   /* If --allow-multiple-definition is in effect, we need to disable it,
 796      as the plugin infrastructure relies on the multiple_definition
 797      callback to swap out the dummy IR-only BFDs for new real ones
 798      when it starts opening the files added during this callback.  */
 799   plugin_cached_allow_multiple_defs = link_info.allow_multiple_definition;
 800   link_info.allow_multiple_definition = FALSE;
 801
 802   while (curplug)
 803     {
 804       if (curplug->all_symbols_read_handler)
 805         {
 806           enum ld_plugin_status rv;
 807           called_plugin = curplug;
 808           rv = (*curplug->all_symbols_read_handler) ();
 809           called_plugin = NULL;
 810           if (rv != LDPS_OK)
 811             set_plugin_error (curplug->name);
 812         }
 813       curplug = curplug->next;
 814     }
 815   return plugin_error_p () ? -1 : 0;
 816 }
 817
 818 /* Call 'cleanup' hook for all plugins at exit.  */
 819 void
 820 plugin_call_cleanup (void)
 821 {
 822   plugin_t *curplug = plugins_list;
 823   while (curplug)
 824     {
 825       if (curplug->cleanup_handler && !curplug->cleanup_done)
 826         {
 827           enum ld_plugin_status rv;
 828           curplug->cleanup_done = TRUE;
 829           called_plugin = curplug;
 830           rv = (*curplug->cleanup_handler) ();
 831           called_plugin = NULL;
 832           if (rv != LDPS_OK)
 833             set_plugin_error (curplug->name);
 834           dlclose (curplug->dlhandle);
 835         }
 836       curplug = curplug->next;
 837     }
 838   if (plugin_error_p ())
 839     info_msg (_("%P: %s: error in plugin cleanup (ignored)\n"),
 840               plugin_error_plugin ());
 841 }
 842
 843 /* Lazily init the non_ironly hash table.  */
 844 static void
 845 init_non_ironly_hash (void)
 846 {
 847   struct bfd_sym_chain *sym;
 848
 849   if (non_ironly_hash == NULL)
 850     {
 851       non_ironly_hash =
 852         (struct bfd_hash_table *) xmalloc (sizeof (struct bfd_hash_table));
 853       if (!bfd_hash_table_init_n (non_ironly_hash,
 854                                   bfd_hash_newfunc,
 855                                   sizeof (struct bfd_hash_entry),
 856                                   61))
 857         einfo (_("%P%F: bfd_hash_table_init failed: %E\n"));
 858
 859       for (sym = &entry_symbol; sym != NULL; sym = sym->next)
 860         if (sym->name
 861             && !bfd_hash_lookup (non_ironly_hash, sym->name, TRUE, TRUE))
 862           einfo (_("%P%X: hash table failure adding symbol %s\n"),
 863                  sym->name);
 864     }
 865 }
 866
 867 /* To determine which symbols should be resolved LDPR_PREVAILING_DEF
 868    and which LDPR_PREVAILING_DEF_IRONLY, we notice all the symbols as
 869    the linker adds them to the linker hash table.  If we see a symbol
 870    being referenced from a non-IR file, we add it to the non_ironly hash
 871    table.  If we can't find it there at get_symbols time, we know that
 872    it was referenced only by IR files.  We have to notice_all symbols,
 873    because we won't necessarily know until later which ones will be
 874    contributed by IR files.  */
 875 bfd_boolean
 876 plugin_notice (struct bfd_link_info *info ATTRIBUTE_UNUSED,
 877                const char *name, bfd *abfd,
 878                asection *section, bfd_vma value ATTRIBUTE_UNUSED)
 879 {
 880   bfd_boolean is_ref = bfd_is_und_section (section);
 881   bfd_boolean is_dummy = is_ir_dummy_bfd (abfd);
 882   init_non_ironly_hash ();
 883   /* We only care about refs, not defs, indicated by section pointing
 884      to the undefined section (according to the bfd linker notice callback
 885      interface definition).  */
 886   if (is_ref && !is_dummy)
 887     {
 888       /* This is a ref from a non-IR file, so note the ref'd symbol
 889          in the non-IR-only hash.  */
 890       if (!bfd_hash_lookup (non_ironly_hash, name, TRUE, TRUE))
 891         einfo (_("%P%X: %s: hash table failure adding symbol %s\n"),
 892                abfd->filename, name);
 893     }
 894   else if (!is_ref && is_dummy)
 895     {
 896       /* No further processing since this is a def from an IR dummy BFD.  */
 897       return FALSE;
 898     }
 899
 900   /* Continue with cref/nocrossref/trace-sym processing.  */
 901   return TRUE;
 902 }
 903
 904 /* When we add new object files to the link at all symbols read time,
 905    these contain the real code and symbols generated from the IR files,
 906    and so duplicate all the definitions already supplied by the dummy
 907    IR-only BFDs that we created at claim files time.  We use the linker's
 908    multiple-definitions callback hook to fix up the clash, discarding
 909    the symbol from the IR-only BFD in favour of the symbol from the
 910    real BFD.  We return true if this was not-really-a-clash because
 911    we've fixed it up, or anyway if --allow-multiple-definition was in
 912    effect (before we disabled it to ensure we got called back).  */
 913 bfd_boolean
 914 plugin_multiple_definition (struct bfd_link_info *info, const char *name,
 915                             bfd *obfd, asection *osec ATTRIBUTE_UNUSED,
 916                             bfd_vma oval ATTRIBUTE_UNUSED,
 917                             bfd *nbfd, asection *nsec, bfd_vma nval)
 918 {
 919   if (is_ir_dummy_bfd (obfd))
 920     {
 921       struct bfd_link_hash_entry *blhe
 922         = bfd_link_hash_lookup (info->hash, name, FALSE, FALSE, FALSE);
 923       if (!blhe)
 924         einfo (_("%P%X: %s: can't find IR symbol '%s'\n"), nbfd->filename,
 925                name);
 926       else if (blhe->type != bfd_link_hash_defined)
 927         einfo (_("%P%x: %s: bad IR symbol type %d\n"), name, blhe->type);
 928       /* Replace it with new details.  */
 929       blhe->u.def.section = nsec;
 930       blhe->u.def.value = nval;
 931       return TRUE;
 932     }
 933   return plugin_cached_allow_multiple_defs;
 934 }