1 // gold.cc -- main linker functions 2 3 // Copyright (C) 2006-2016 Free Software Foundation, Inc. 4 // Written by Ian Lance Taylor <iant (at) google.com>. 5 6 // This file is part of gold. 7 8 // This program is free software; you can redistribute it and/or modify 9 // it under the terms of the GNU General Public License as published by 10 // the Free Software Foundation; either version 3 of the License, or 11 // (at your option) any later version. 12 13 // This program is distributed in the hope that it will be useful, 14 // but WITHOUT ANY WARRANTY; without even the implied warranty of 15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 // GNU General Public License for more details. 17 18 // You should have received a copy of the GNU General Public License 19 // along with this program; if not, write to the Free Software 20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, 21 // MA 02110-1301, USA. 22 23 #include "gold.h" 24 25 #include <cstdlib> 26 #include <cstdio> 27 #include <cstring> 28 #include <unistd.h> 29 #include <algorithm> 30 #include "libiberty.h" 31 32 #include "options.h" 33 #include "target-select.h" 34 #include "debug.h" 35 #include "workqueue.h" 36 #include "dirsearch.h" 37 #include "readsyms.h" 38 #include "symtab.h" 39 #include "common.h" 40 #include "object.h" 41 #include "layout.h" 42 #include "reloc.h" 43 #include "defstd.h" 44 #include "plugin.h" 45 #include "gc.h" 46 #include "icf.h" 47 #include "incremental.h" 48 #include "timer.h" 49 50 namespace gold 51 { 52 53 class Object; 54 55 const char* program_name; 56 57 static Task* 58 process_incremental_input(Incremental_binary*, unsigned int, Input_objects*, 59 Symbol_table*, Layout*, Dirsearch*, Mapfile*, 60 Task_token*, Task_token*); 61 62 void 63 gold_exit(Exit_status status) 64 { 65 if (parameters != NULL 66 && parameters->options_valid() 67 && parameters->options().has_plugins()) 68 parameters->options().plugins()->cleanup(); 69 if (status != GOLD_OK && parameters != NULL && parameters->options_valid()) 70 unlink_if_ordinary(parameters->options().output_file_name()); 71 exit(status); 72 } 73 74 void 75 gold_nomem() 76 { 77 // We are out of memory, so try hard to print a reasonable message. 78 // Note that we don't try to translate this message, since the 79 // translation process itself will require memory. 80 81 // LEN only exists to avoid a pointless warning when write is 82 // declared with warn_use_result, as when compiling with 83 // -D_USE_FORTIFY on GNU/Linux. Casting to void does not appear to 84 // work, at least not with gcc 4.3.0. 85 86 ssize_t len = write(2, program_name, strlen(program_name)); 87 if (len >= 0) 88 { 89 const char* const s = ": out of memory\n"; 90 len = write(2, s, strlen(s)); 91 } 92 gold_exit(GOLD_ERR); 93 } 94 95 // Handle an unreachable case. 96 97 void 98 do_gold_unreachable(const char* filename, int lineno, const char* function) 99 { 100 fprintf(stderr, _("%s: internal error in %s, at %s:%d\n"), 101 program_name, function, filename, lineno); 102 gold_exit(GOLD_ERR); 103 } 104 105 // This class arranges to run the functions done in the middle of the 106 // link. It is just a closure. 107 108 class Middle_runner : public Task_function_runner 109 { 110 public: 111 Middle_runner(const General_options& options, 112 const Input_objects* input_objects, 113 Symbol_table* symtab, 114 Layout* layout, Mapfile* mapfile) 115 : options_(options), input_objects_(input_objects), symtab_(symtab), 116 layout_(layout), mapfile_(mapfile) 117 { } 118 119 void 120 run(Workqueue*, const Task*); 121 122 private: 123 const General_options& options_; 124 const Input_objects* input_objects_; 125 Symbol_table* symtab_; 126 Layout* layout_; 127 Mapfile* mapfile_; 128 }; 129 130 void 131 Middle_runner::run(Workqueue* workqueue, const Task* task) 132 { 133 queue_middle_tasks(this->options_, task, this->input_objects_, this->symtab_, 134 this->layout_, workqueue, this->mapfile_); 135 } 136 137 // This class arranges the tasks to process the relocs for garbage collection. 138 139 class Gc_runner : public Task_function_runner 140 { 141 public: 142 Gc_runner(const General_options& options, 143 const Input_objects* input_objects, 144 Symbol_table* symtab, 145 Layout* layout, Mapfile* mapfile) 146 : options_(options), input_objects_(input_objects), symtab_(symtab), 147 layout_(layout), mapfile_(mapfile) 148 { } 149 150 void 151 run(Workqueue*, const Task*); 152 153 private: 154 const General_options& options_; 155 const Input_objects* input_objects_; 156 Symbol_table* symtab_; 157 Layout* layout_; 158 Mapfile* mapfile_; 159 }; 160 161 void 162 Gc_runner::run(Workqueue* workqueue, const Task* task) 163 { 164 queue_middle_gc_tasks(this->options_, task, this->input_objects_, 165 this->symtab_, this->layout_, workqueue, 166 this->mapfile_); 167 } 168 169 // Queue up the initial set of tasks for this link job. 170 171 void 172 queue_initial_tasks(const General_options& options, 173 Dirsearch& search_path, 174 const Command_line& cmdline, 175 Workqueue* workqueue, Input_objects* input_objects, 176 Symbol_table* symtab, Layout* layout, Mapfile* mapfile) 177 { 178 if (cmdline.begin() == cmdline.end()) 179 { 180 bool is_ok = false; 181 if (options.printed_version()) 182 is_ok = true; 183 if (options.print_output_format()) 184 { 185 print_output_format(); 186 is_ok = true; 187 } 188 if (is_ok) 189 gold_exit(GOLD_OK); 190 gold_fatal(_("no input files")); 191 } 192 193 int thread_count = options.thread_count_initial(); 194 if (thread_count == 0) 195 thread_count = cmdline.number_of_input_files(); 196 workqueue->set_thread_count(thread_count); 197 198 // For incremental links, the base output file. 199 Incremental_binary* ibase = NULL; 200 201 if (parameters->incremental_update()) 202 { 203 Output_file* of = new Output_file(options.output_file_name()); 204 if (of->open_base_file(options.incremental_base(), true)) 205 { 206 ibase = open_incremental_binary(of); 207 if (ibase != NULL 208 && ibase->check_inputs(cmdline, layout->incremental_inputs())) 209 ibase->init_layout(layout); 210 else 211 { 212 delete ibase; 213 ibase = NULL; 214 of->close(); 215 } 216 } 217 if (ibase == NULL) 218 { 219 if (set_parameters_incremental_full()) 220 gold_info(_("linking with --incremental-full")); 221 else 222 gold_fallback(_("restart link with --incremental-full")); 223 } 224 } 225 226 // Read the input files. We have to add the symbols to the symbol 227 // table in order. We do this by creating a separate blocker for 228 // each input file. We associate the blocker with the following 229 // input file, to give us a convenient place to delete it. 230 Task_token* this_blocker = NULL; 231 if (ibase == NULL) 232 { 233 // Normal link. Queue a Read_symbols task for each input file 234 // on the command line. 235 for (Command_line::const_iterator p = cmdline.begin(); 236 p != cmdline.end(); 237 ++p) 238 { 239 Task_token* next_blocker = new Task_token(true); 240 next_blocker->add_blocker(); 241 workqueue->queue(new Read_symbols(input_objects, symtab, layout, 242 &search_path, 0, mapfile, &*p, NULL, 243 NULL, this_blocker, next_blocker)); 244 this_blocker = next_blocker; 245 } 246 } 247 else 248 { 249 // Incremental update link. Process the list of input files 250 // stored in the base file, and queue a task for each file: 251 // a Read_symbols task for a changed file, and an Add_symbols task 252 // for an unchanged file. We need to mark all the space used by 253 // unchanged files before we can start any tasks running. 254 unsigned int input_file_count = ibase->input_file_count(); 255 std::vector<Task*> tasks; 256 tasks.reserve(input_file_count); 257 for (unsigned int i = 0; i < input_file_count; ++i) 258 { 259 Task_token* next_blocker = new Task_token(true); 260 next_blocker->add_blocker(); 261 Task* t = process_incremental_input(ibase, i, input_objects, symtab, 262 layout, &search_path, mapfile, 263 this_blocker, next_blocker); 264 tasks.push_back(t); 265 this_blocker = next_blocker; 266 } 267 // Now we can queue the tasks. 268 for (unsigned int i = 0; i < tasks.size(); i++) 269 workqueue->queue(tasks[i]); 270 } 271 272 if (options.has_plugins()) 273 { 274 Task_token* next_blocker = new Task_token(true); 275 next_blocker->add_blocker(); 276 workqueue->queue(new Plugin_hook(options, input_objects, symtab, layout, 277 &search_path, mapfile, this_blocker, 278 next_blocker)); 279 this_blocker = next_blocker; 280 } 281 282 if (options.relocatable() 283 && (options.gc_sections() || options.icf_enabled())) 284 gold_error(_("cannot mix -r with --gc-sections or --icf")); 285 286 if (options.gc_sections() || options.icf_enabled()) 287 { 288 workqueue->queue(new Task_function(new Gc_runner(options, 289 input_objects, 290 symtab, 291 layout, 292 mapfile), 293 this_blocker, 294 "Task_function Gc_runner")); 295 } 296 else 297 { 298 workqueue->queue(new Task_function(new Middle_runner(options, 299 input_objects, 300 symtab, 301 layout, 302 mapfile), 303 this_blocker, 304 "Task_function Middle_runner")); 305 } 306 } 307 308 // Process an incremental input file: if it is unchanged from the previous 309 // link, return a task to add its symbols from the base file's incremental 310 // info; if it has changed, return a normal Read_symbols task. We create a 311 // task for every input file, if only to report the file for rebuilding the 312 // incremental info. 313 314 static Task* 315 process_incremental_input(Incremental_binary* ibase, 316 unsigned int input_file_index, 317 Input_objects* input_objects, 318 Symbol_table* symtab, 319 Layout* layout, 320 Dirsearch* search_path, 321 Mapfile* mapfile, 322 Task_token* this_blocker, 323 Task_token* next_blocker) 324 { 325 const Incremental_binary::Input_reader* input_reader = 326 ibase->get_input_reader(input_file_index); 327 Incremental_input_type input_type = input_reader->type(); 328 329 // Get the input argument corresponding to this input file, matching on 330 // the argument serial number. If the input file cannot be matched 331 // to an existing input argument, synthesize a new one. 332 const Input_argument* input_argument = 333 ibase->get_input_argument(input_file_index); 334 if (input_argument == NULL) 335 { 336 Input_file_argument file(input_reader->filename(), 337 Input_file_argument::INPUT_FILE_TYPE_FILE, 338 "", false, parameters->options()); 339 Input_argument* arg = new Input_argument(file); 340 arg->set_script_info(ibase->get_script_info(input_file_index)); 341 input_argument = arg; 342 } 343 344 gold_debug(DEBUG_INCREMENTAL, "Incremental object: %s, type %d", 345 input_reader->filename(), input_type); 346 347 if (input_type == INCREMENTAL_INPUT_SCRIPT) 348 { 349 // Incremental_binary::check_inputs should have cancelled the 350 // incremental update if the script has changed. 351 gold_assert(!ibase->file_has_changed(input_file_index)); 352 return new Check_script(layout, ibase, input_file_index, input_reader, 353 this_blocker, next_blocker); 354 } 355 356 if (input_type == INCREMENTAL_INPUT_ARCHIVE) 357 { 358 Incremental_library* lib = ibase->get_library(input_file_index); 359 gold_assert(lib != NULL); 360 if (lib->filename() == "/group/" 361 || !ibase->file_has_changed(input_file_index)) 362 { 363 // Queue a task to check that no references have been added to any 364 // of the library's unused symbols. 365 return new Check_library(symtab, layout, ibase, input_file_index, 366 input_reader, this_blocker, next_blocker); 367 } 368 else 369 { 370 // Queue a Read_symbols task to process the archive normally. 371 return new Read_symbols(input_objects, symtab, layout, search_path, 372 0, mapfile, input_argument, NULL, NULL, 373 this_blocker, next_blocker); 374 } 375 } 376 377 if (input_type == INCREMENTAL_INPUT_ARCHIVE_MEMBER) 378 { 379 // For archive members, check the timestamp of the containing archive. 380 Incremental_library* lib = ibase->get_library(input_file_index); 381 gold_assert(lib != NULL); 382 // Process members of a --start-lib/--end-lib group as normal objects. 383 if (lib->filename() != "/group/") 384 { 385 if (ibase->file_has_changed(lib->input_file_index())) 386 { 387 return new Read_member(input_objects, symtab, layout, mapfile, 388 input_reader, this_blocker, next_blocker); 389 } 390 else 391 { 392 // The previous contributions from this file will be kept. 393 // Mark the pieces of output sections contributed by this 394 // object. 395 ibase->reserve_layout(input_file_index); 396 Object* obj = make_sized_incremental_object(ibase, 397 input_file_index, 398 input_type, 399 input_reader); 400 return new Add_symbols(input_objects, symtab, layout, 401 search_path, 0, mapfile, input_argument, 402 obj, lib, NULL, this_blocker, 403 next_blocker); 404 } 405 } 406 } 407 408 // Normal object file or shared library. Check if the file has changed 409 // since the last incremental link. 410 if (ibase->file_has_changed(input_file_index)) 411 { 412 return new Read_symbols(input_objects, symtab, layout, search_path, 0, 413 mapfile, input_argument, NULL, NULL, 414 this_blocker, next_blocker); 415 } 416 else 417 { 418 // The previous contributions from this file will be kept. 419 // Mark the pieces of output sections contributed by this object. 420 ibase->reserve_layout(input_file_index); 421 Object* obj = make_sized_incremental_object(ibase, 422 input_file_index, 423 input_type, 424 input_reader); 425 return new Add_symbols(input_objects, symtab, layout, search_path, 0, 426 mapfile, input_argument, obj, NULL, NULL, 427 this_blocker, next_blocker); 428 } 429 } 430 431 // Queue up a set of tasks to be done before queueing the middle set 432 // of tasks. This is only necessary when garbage collection 433 // (--gc-sections) of unused sections is desired. The relocs are read 434 // and processed here early to determine the garbage sections before the 435 // relocs can be scanned in later tasks. 436 437 void 438 queue_middle_gc_tasks(const General_options& options, 439 const Task* , 440 const Input_objects* input_objects, 441 Symbol_table* symtab, 442 Layout* layout, 443 Workqueue* workqueue, 444 Mapfile* mapfile) 445 { 446 // Read_relocs for all the objects must be done and processed to find 447 // unused sections before any scanning of the relocs can take place. 448 Task_token* this_blocker = NULL; 449 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 450 p != input_objects->relobj_end(); 451 ++p) 452 { 453 Task_token* next_blocker = new Task_token(true); 454 next_blocker->add_blocker(); 455 workqueue->queue(new Read_relocs(symtab, layout, *p, this_blocker, 456 next_blocker)); 457 this_blocker = next_blocker; 458 } 459 460 // If we are given only archives in input, we have no regular 461 // objects and THIS_BLOCKER is NULL here. Create a dummy 462 // blocker here so that we can run the middle tasks immediately. 463 if (this_blocker == NULL) 464 { 465 gold_assert(input_objects->number_of_relobjs() == 0); 466 this_blocker = new Task_token(true); 467 } 468 469 workqueue->queue(new Task_function(new Middle_runner(options, 470 input_objects, 471 symtab, 472 layout, 473 mapfile), 474 this_blocker, 475 "Task_function Middle_runner")); 476 } 477 478 // Queue up the middle set of tasks. These are the tasks which run 479 // after all the input objects have been found and all the symbols 480 // have been read, but before we lay out the output file. 481 482 void 483 queue_middle_tasks(const General_options& options, 484 const Task* task, 485 const Input_objects* input_objects, 486 Symbol_table* symtab, 487 Layout* layout, 488 Workqueue* workqueue, 489 Mapfile* mapfile) 490 { 491 Timer* timer = parameters->timer(); 492 if (timer != NULL) 493 timer->stamp(0); 494 495 // We have to support the case of not seeing any input objects, and 496 // generate an empty file. Existing builds depend on being able to 497 // pass an empty archive to the linker and get an empty object file 498 // out. In order to do this we need to use a default target. 499 if (input_objects->number_of_input_objects() == 0 500 && layout->incremental_base() == NULL) 501 parameters_force_valid_target(); 502 503 // Add any symbols named with -u options to the symbol table. 504 symtab->add_undefined_symbols_from_command_line(layout); 505 506 // If garbage collection was chosen, relocs have been read and processed 507 // at this point by pre_middle_tasks. Layout can then be done for all 508 // objects. 509 if (parameters->options().gc_sections()) 510 { 511 // Find the start symbol if any. 512 Symbol* sym = symtab->lookup(parameters->entry()); 513 if (sym != NULL) 514 symtab->gc_mark_symbol(sym); 515 sym = symtab->lookup(parameters->options().init()); 516 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj()) 517 symtab->gc_mark_symbol(sym); 518 sym = symtab->lookup(parameters->options().fini()); 519 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj()) 520 symtab->gc_mark_symbol(sym); 521 // Symbols named with -u should not be considered garbage. 522 symtab->gc_mark_undef_symbols(layout); 523 gold_assert(symtab->gc() != NULL); 524 // Do a transitive closure on all references to determine the worklist. 525 symtab->gc()->do_transitive_closure(); 526 } 527 528 // If identical code folding (--icf) is chosen it makes sense to do it 529 // only after garbage collection (--gc-sections) as we do not want to 530 // be folding sections that will be garbage. 531 if (parameters->options().icf_enabled()) 532 { 533 symtab->icf()->find_identical_sections(input_objects, symtab); 534 } 535 536 // Call Object::layout for the second time to determine the 537 // output_sections for all referenced input sections. When 538 // --gc-sections or --icf is turned on, or when certain input 539 // sections have to be mapped to unique segments, Object::layout 540 // is called twice. It is called the first time when symbols 541 // are added. 542 if (parameters->options().gc_sections() 543 || parameters->options().icf_enabled() 544 || layout->is_unique_segment_for_sections_specified()) 545 { 546 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 547 p != input_objects->relobj_end(); 548 ++p) 549 { 550 Task_lock_obj<Object> tlo(task, *p); 551 (*p)->layout(symtab, layout, NULL); 552 } 553 } 554 555 // Layout deferred objects due to plugins. 556 if (parameters->options().has_plugins()) 557 { 558 Plugin_manager* plugins = parameters->options().plugins(); 559 gold_assert(plugins != NULL); 560 plugins->layout_deferred_objects(); 561 } 562 563 Target *target = NULL; 564 565 // TODO(tmsriram): figure out a more principled way to get the target 566 if (parameters->target_valid()) 567 target = const_cast<Target*>(¶meters->target()); 568 569 // Check if we need to disable PIE because of an unsafe data segment size. 570 // Go through each Output section and get the size. At this point, we do not 571 // have the exact size of the data segment but this is a very close estimate. 572 // We are doing this here because disabling PIE later is too late. Further, 573 // if we miss some cases which are on the edge, it will be caught later in 574 // layout.cc where we check with the exact size of the data segment and warn 575 // if it is breached. 576 if (parameters->options().disable_pie_when_unsafe_data_size() 577 && parameters->options().pie() && target->max_pie_data_segment_size()) 578 { 579 uint64_t segment_size = 0; 580 for (Layout::Section_list::const_iterator p = layout->section_list().begin(); 581 p != layout->section_list().end(); 582 ++p) 583 { 584 Output_section *os = *p; 585 if (os->is_section_flag_set(elfcpp::SHF_ALLOC) 586 && os->is_section_flag_set(elfcpp::SHF_WRITE)) 587 { 588 segment_size += os->current_data_size(); 589 } 590 // Count read-only sections if --rosegment is set. 591 else if (parameters->options().rosegment() 592 && os->is_section_flag_set(elfcpp::SHF_ALLOC) 593 && !os->is_section_flag_set(elfcpp::SHF_EXECINSTR)) 594 { 595 segment_size += os->current_data_size(); 596 } 597 } 598 // We are using an estimate for data segment size here as we have not 599 // accounted for the GOT and DYNAMIC sections. Experiments show that the 600 // estimate is within 1% of the actual size for most binaries. So, we 601 // will add 1% to the estimated size. 602 // If we miss disabling PIE here because our estimate is wrong, the 603 // check in layout.cc will catch it and warn. 604 uint64_t est_size_of_got_and_dynamic = segment_size / 100; 605 if ((segment_size + est_size_of_got_and_dynamic) 606 >= target->max_pie_data_segment_size()) 607 { 608 gold_info( 609 _("Disabling PIE for this link. The estimated data segment size" 610 " (%" PRIu64 " > %" PRIu64 ") would exceed the safe limits for" 611 " PIE."), 612 (segment_size + est_size_of_got_and_dynamic), 613 target->max_pie_data_segment_size()); 614 const_cast<General_options*> 615 (¶meters->options())->set_pie_value(false); 616 } 617 618 } 619 620 // Finalize the .eh_frame section. 621 layout->finalize_eh_frame_section(); 622 623 /* If plugins have specified a section order, re-arrange input sections 624 according to a specified section order. If --section-ordering-file is 625 also specified, do not do anything here. */ 626 if (parameters->options().has_plugins() 627 && layout->is_section_ordering_specified() 628 && !parameters->options().section_ordering_file ()) 629 { 630 for (Layout::Section_list::const_iterator p 631 = layout->section_list().begin(); 632 p != layout->section_list().end(); 633 ++p) 634 (*p)->update_section_layout(layout->get_section_order_map()); 635 } 636 637 if (parameters->options().gc_sections() 638 || parameters->options().icf_enabled()) 639 { 640 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 641 p != input_objects->relobj_end(); 642 ++p) 643 { 644 // Update the value of output_section stored in rd. 645 Read_relocs_data* rd = (*p)->get_relocs_data(); 646 for (Read_relocs_data::Relocs_list::iterator q = rd->relocs.begin(); 647 q != rd->relocs.end(); 648 ++q) 649 { 650 q->output_section = (*p)->output_section(q->data_shndx); 651 q->needs_special_offset_handling = 652 (*p)->is_output_section_offset_invalid(q->data_shndx); 653 } 654 } 655 } 656 657 int thread_count = options.thread_count_middle(); 658 if (thread_count == 0) 659 thread_count = std::max(2, input_objects->number_of_input_objects()); 660 workqueue->set_thread_count(thread_count); 661 662 // Now we have seen all the input files. 663 const bool doing_static_link = 664 (!input_objects->any_dynamic() 665 && !parameters->options().output_is_position_independent()); 666 set_parameters_doing_static_link(doing_static_link); 667 if (!doing_static_link && options.is_static()) 668 { 669 // We print out just the first .so we see; there may be others. 670 gold_assert(input_objects->dynobj_begin() != input_objects->dynobj_end()); 671 gold_error(_("cannot mix -static with dynamic object %s"), 672 (*input_objects->dynobj_begin())->name().c_str()); 673 } 674 if (!doing_static_link && parameters->options().relocatable()) 675 gold_fatal(_("cannot mix -r with dynamic object %s"), 676 (*input_objects->dynobj_begin())->name().c_str()); 677 if (!doing_static_link 678 && options.oformat_enum() != General_options::OBJECT_FORMAT_ELF) 679 gold_fatal(_("cannot use non-ELF output format with dynamic object %s"), 680 (*input_objects->dynobj_begin())->name().c_str()); 681 682 if (parameters->options().relocatable()) 683 { 684 Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 685 if (p != input_objects->relobj_end()) 686 { 687 bool uses_split_stack = (*p)->uses_split_stack(); 688 for (++p; p != input_objects->relobj_end(); ++p) 689 { 690 if ((*p)->uses_split_stack() != uses_split_stack) 691 gold_fatal(_("cannot mix split-stack '%s' and " 692 "non-split-stack '%s' when using -r"), 693 (*input_objects->relobj_begin())->name().c_str(), 694 (*p)->name().c_str()); 695 } 696 } 697 } 698 699 // For incremental updates, record the existing GOT and PLT entries, 700 // and the COPY relocations. 701 if (parameters->incremental_update()) 702 { 703 Incremental_binary* ibase = layout->incremental_base(); 704 ibase->process_got_plt(symtab, layout); 705 ibase->emit_copy_relocs(symtab); 706 } 707 708 if (is_debugging_enabled(DEBUG_SCRIPT)) 709 layout->script_options()->print(stderr); 710 711 // For each dynamic object, record whether we've seen all the 712 // dynamic objects that it depends upon. 713 input_objects->check_dynamic_dependencies(); 714 715 // Do the --no-undefined-version check. 716 if (!parameters->options().undefined_version()) 717 { 718 Script_options* so = layout->script_options(); 719 so->version_script_info()->check_unmatched_names(symtab); 720 } 721 722 // Create any automatic note sections. 723 layout->create_notes(); 724 725 // Create any output sections required by any linker script. 726 layout->create_script_sections(); 727 728 // Define some sections and symbols needed for a dynamic link. This 729 // handles some cases we want to see before we read the relocs. 730 layout->create_initial_dynamic_sections(symtab); 731 732 // Define symbols from any linker scripts. 733 layout->define_script_symbols(symtab); 734 735 // Attach sections to segments. 736 layout->attach_sections_to_segments(target); 737 738 if (!parameters->options().relocatable()) 739 { 740 // Predefine standard symbols. 741 define_standard_symbols(symtab, layout); 742 743 // Define __start and __stop symbols for output sections where 744 // appropriate. 745 layout->define_section_symbols(symtab); 746 747 // Define target-specific symbols. 748 target->define_standard_symbols(symtab, layout); 749 } 750 751 // Make sure we have symbols for any required group signatures. 752 layout->define_group_signatures(symtab); 753 754 Task_token* this_blocker = NULL; 755 756 // Allocate common symbols. We use a blocker to run this before the 757 // Scan_relocs tasks, because it writes to the symbol table just as 758 // they do. 759 if (parameters->options().define_common()) 760 { 761 this_blocker = new Task_token(true); 762 this_blocker->add_blocker(); 763 workqueue->queue(new Allocate_commons_task(symtab, layout, mapfile, 764 this_blocker)); 765 } 766 767 // If doing garbage collection, the relocations have already been read. 768 // Otherwise, read and scan the relocations. 769 if (parameters->options().gc_sections() 770 || parameters->options().icf_enabled()) 771 { 772 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 773 p != input_objects->relobj_end(); 774 ++p) 775 { 776 Task_token* next_blocker = new Task_token(true); 777 next_blocker->add_blocker(); 778 workqueue->queue(new Scan_relocs(symtab, layout, *p, 779 (*p)->get_relocs_data(), 780 this_blocker, next_blocker)); 781 this_blocker = next_blocker; 782 } 783 } 784 else 785 { 786 // Read the relocations of the input files. We do this to find 787 // which symbols are used by relocations which require a GOT and/or 788 // a PLT entry, or a COPY reloc. When we implement garbage 789 // collection we will do it here by reading the relocations in a 790 // breadth first search by references. 791 // 792 // We could also read the relocations during the first pass, and 793 // mark symbols at that time. That is how the old GNU linker works. 794 // Doing that is more complex, since we may later decide to discard 795 // some of the sections, and thus change our minds about the types 796 // of references made to the symbols. 797 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 798 p != input_objects->relobj_end(); 799 ++p) 800 { 801 Task_token* next_blocker = new Task_token(true); 802 next_blocker->add_blocker(); 803 workqueue->queue(new Read_relocs(symtab, layout, *p, this_blocker, 804 next_blocker)); 805 this_blocker = next_blocker; 806 } 807 } 808 809 if (this_blocker == NULL) 810 { 811 if (input_objects->number_of_relobjs() == 0) 812 { 813 // If we are given only archives in input, we have no regular 814 // objects and THIS_BLOCKER is NULL here. Create a dummy 815 // blocker here so that we can run the layout task immediately. 816 this_blocker = new Task_token(true); 817 } 818 else 819 { 820 // If we failed to open any input files, it's possible for 821 // THIS_BLOCKER to be NULL here. There's no real point in 822 // continuing if that happens. 823 gold_assert(parameters->errors()->error_count() > 0); 824 gold_exit(GOLD_ERR); 825 } 826 } 827 828 // When all those tasks are complete, we can start laying out the 829 // output file. 830 workqueue->queue(new Task_function(new Layout_task_runner(options, 831 input_objects, 832 symtab, 833 target, 834 layout, 835 mapfile), 836 this_blocker, 837 "Task_function Layout_task_runner")); 838 } 839 840 // Queue up the final set of tasks. This is called at the end of 841 // Layout_task. 842 843 void 844 queue_final_tasks(const General_options& options, 845 const Input_objects* input_objects, 846 const Symbol_table* symtab, 847 Layout* layout, 848 Workqueue* workqueue, 849 Output_file* of) 850 { 851 Timer* timer = parameters->timer(); 852 if (timer != NULL) 853 timer->stamp(1); 854 855 int thread_count = options.thread_count_final(); 856 if (thread_count == 0) 857 thread_count = std::max(2, input_objects->number_of_input_objects()); 858 workqueue->set_thread_count(thread_count); 859 860 bool any_postprocessing_sections = layout->any_postprocessing_sections(); 861 862 // Use a blocker to wait until all the input sections have been 863 // written out. 864 Task_token* input_sections_blocker = NULL; 865 if (!any_postprocessing_sections) 866 { 867 input_sections_blocker = new Task_token(true); 868 // Write_symbols_task, Relocate_tasks. 869 input_sections_blocker->add_blocker(); 870 input_sections_blocker->add_blockers(input_objects->number_of_relobjs()); 871 } 872 873 // Use a blocker to block any objects which have to wait for the 874 // output sections to complete before they can apply relocations. 875 Task_token* output_sections_blocker = new Task_token(true); 876 output_sections_blocker->add_blocker(); 877 878 // Use a blocker to block the final cleanup task. 879 Task_token* final_blocker = new Task_token(true); 880 // Write_symbols_task, Write_sections_task, Write_data_task, 881 // Relocate_tasks. 882 final_blocker->add_blockers(3); 883 final_blocker->add_blockers(input_objects->number_of_relobjs()); 884 if (!any_postprocessing_sections) 885 final_blocker->add_blocker(); 886 887 // Queue a task to write out the symbol table. 888 workqueue->queue(new Write_symbols_task(layout, 889 symtab, 890 input_objects, 891 layout->sympool(), 892 layout->dynpool(), 893 of, 894 final_blocker)); 895 896 // Queue a task to write out the output sections. 897 workqueue->queue(new Write_sections_task(layout, of, output_sections_blocker, 898 input_sections_blocker, 899 final_blocker)); 900 901 // Queue a task to write out everything else. 902 workqueue->queue(new Write_data_task(layout, symtab, of, final_blocker)); 903 904 // Queue a task for each input object to relocate the sections and 905 // write out the local symbols. 906 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 907 p != input_objects->relobj_end(); 908 ++p) 909 workqueue->queue(new Relocate_task(symtab, layout, *p, of, 910 input_sections_blocker, 911 output_sections_blocker, 912 final_blocker)); 913 914 // Queue a task to write out the output sections which depend on 915 // input sections. If there are any sections which require 916 // postprocessing, then we need to do this last, since it may resize 917 // the output file. 918 if (!any_postprocessing_sections) 919 { 920 Task* t = new Write_after_input_sections_task(layout, of, 921 input_sections_blocker, 922 final_blocker); 923 workqueue->queue(t); 924 } 925 else 926 { 927 Task_token* new_final_blocker = new Task_token(true); 928 new_final_blocker->add_blocker(); 929 Task* t = new Write_after_input_sections_task(layout, of, 930 final_blocker, 931 new_final_blocker); 932 workqueue->queue(t); 933 final_blocker = new_final_blocker; 934 } 935 936 // Create tasks for tree-style build ID computation, if necessary. 937 if (strcmp(options.build_id(), "tree") == 0) 938 { 939 // Queue a task to compute the build id. This will be blocked by 940 // FINAL_BLOCKER, and will in turn schedule the task to close 941 // the output file. 942 workqueue->queue(new Task_function(new Build_id_task_runner(&options, 943 layout, 944 of), 945 final_blocker, 946 "Task_function Build_id_task_runner")); 947 } 948 else 949 { 950 // Queue a task to close the output file. This will be blocked by 951 // FINAL_BLOCKER. 952 workqueue->queue(new Task_function(new Close_task_runner(&options, layout, 953 of, NULL, 0), 954 final_blocker, 955 "Task_function Close_task_runner")); 956 } 957 958 } 959 960 } // End namespace gold. 961