1 // layout.cc -- lay out output file sections for gold 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 <cerrno> 26 #include <cstring> 27 #include <algorithm> 28 #include <iostream> 29 #include <fstream> 30 #include <utility> 31 #include <fcntl.h> 32 #include <fnmatch.h> 33 #include <unistd.h> 34 #include "libiberty.h" 35 #include "md5.h" 36 #include "sha1.h" 37 38 #include "parameters.h" 39 #include "options.h" 40 #include "mapfile.h" 41 #include "script.h" 42 #include "script-sections.h" 43 #include "output.h" 44 #include "symtab.h" 45 #include "dynobj.h" 46 #include "ehframe.h" 47 #include "gdb-index.h" 48 #include "compressed_output.h" 49 #include "reduced_debug_output.h" 50 #include "object.h" 51 #include "reloc.h" 52 #include "descriptors.h" 53 #include "plugin.h" 54 #include "incremental.h" 55 #include "layout.h" 56 57 namespace gold 58 { 59 60 // Class Free_list. 61 62 // The total number of free lists used. 63 unsigned int Free_list::num_lists = 0; 64 // The total number of free list nodes used. 65 unsigned int Free_list::num_nodes = 0; 66 // The total number of calls to Free_list::remove. 67 unsigned int Free_list::num_removes = 0; 68 // The total number of nodes visited during calls to Free_list::remove. 69 unsigned int Free_list::num_remove_visits = 0; 70 // The total number of calls to Free_list::allocate. 71 unsigned int Free_list::num_allocates = 0; 72 // The total number of nodes visited during calls to Free_list::allocate. 73 unsigned int Free_list::num_allocate_visits = 0; 74 75 // Initialize the free list. Creates a single free list node that 76 // describes the entire region of length LEN. If EXTEND is true, 77 // allocate() is allowed to extend the region beyond its initial 78 // length. 79 80 void 81 Free_list::init(off_t len, bool extend) 82 { 83 this->list_.push_front(Free_list_node(0, len)); 84 this->last_remove_ = this->list_.begin(); 85 this->extend_ = extend; 86 this->length_ = len; 87 ++Free_list::num_lists; 88 ++Free_list::num_nodes; 89 } 90 91 // Remove a chunk from the free list. Because we start with a single 92 // node that covers the entire section, and remove chunks from it one 93 // at a time, we do not need to coalesce chunks or handle cases that 94 // span more than one free node. We expect to remove chunks from the 95 // free list in order, and we expect to have only a few chunks of free 96 // space left (corresponding to files that have changed since the last 97 // incremental link), so a simple linear list should provide sufficient 98 // performance. 99 100 void 101 Free_list::remove(off_t start, off_t end) 102 { 103 if (start == end) 104 return; 105 gold_assert(start < end); 106 107 ++Free_list::num_removes; 108 109 Iterator p = this->last_remove_; 110 if (p->start_ > start) 111 p = this->list_.begin(); 112 113 for (; p != this->list_.end(); ++p) 114 { 115 ++Free_list::num_remove_visits; 116 // Find a node that wholly contains the indicated region. 117 if (p->start_ <= start && p->end_ >= end) 118 { 119 // Case 1: the indicated region spans the whole node. 120 // Add some fuzz to avoid creating tiny free chunks. 121 if (p->start_ + 3 >= start && p->end_ <= end + 3) 122 p = this->list_.erase(p); 123 // Case 2: remove a chunk from the start of the node. 124 else if (p->start_ + 3 >= start) 125 p->start_ = end; 126 // Case 3: remove a chunk from the end of the node. 127 else if (p->end_ <= end + 3) 128 p->end_ = start; 129 // Case 4: remove a chunk from the middle, and split 130 // the node into two. 131 else 132 { 133 Free_list_node newnode(p->start_, start); 134 p->start_ = end; 135 this->list_.insert(p, newnode); 136 ++Free_list::num_nodes; 137 } 138 this->last_remove_ = p; 139 return; 140 } 141 } 142 143 // Did not find a node containing the given chunk. This could happen 144 // because a small chunk was already removed due to the fuzz. 145 gold_debug(DEBUG_INCREMENTAL, 146 "Free_list::remove(%d,%d) not found", 147 static_cast<int>(start), static_cast<int>(end)); 148 } 149 150 // Allocate a chunk of size LEN from the free list. Returns -1ULL 151 // if a sufficiently large chunk of free space is not found. 152 // We use a simple first-fit algorithm. 153 154 off_t 155 Free_list::allocate(off_t len, uint64_t align, off_t minoff) 156 { 157 gold_debug(DEBUG_INCREMENTAL, 158 "Free_list::allocate(%08lx, %d, %08lx)", 159 static_cast<long>(len), static_cast<int>(align), 160 static_cast<long>(minoff)); 161 if (len == 0) 162 return align_address(minoff, align); 163 164 ++Free_list::num_allocates; 165 166 // We usually want to drop free chunks smaller than 4 bytes. 167 // If we need to guarantee a minimum hole size, though, we need 168 // to keep track of all free chunks. 169 const int fuzz = this->min_hole_ > 0 ? 0 : 3; 170 171 for (Iterator p = this->list_.begin(); p != this->list_.end(); ++p) 172 { 173 ++Free_list::num_allocate_visits; 174 off_t start = p->start_ > minoff ? p->start_ : minoff; 175 start = align_address(start, align); 176 off_t end = start + len; 177 if (end > p->end_ && p->end_ == this->length_ && this->extend_) 178 { 179 this->length_ = end; 180 p->end_ = end; 181 } 182 if (end == p->end_ || (end <= p->end_ - this->min_hole_)) 183 { 184 if (p->start_ + fuzz >= start && p->end_ <= end + fuzz) 185 this->list_.erase(p); 186 else if (p->start_ + fuzz >= start) 187 p->start_ = end; 188 else if (p->end_ <= end + fuzz) 189 p->end_ = start; 190 else 191 { 192 Free_list_node newnode(p->start_, start); 193 p->start_ = end; 194 this->list_.insert(p, newnode); 195 ++Free_list::num_nodes; 196 } 197 return start; 198 } 199 } 200 if (this->extend_) 201 { 202 off_t start = align_address(this->length_, align); 203 this->length_ = start + len; 204 return start; 205 } 206 return -1; 207 } 208 209 // Dump the free list (for debugging). 210 void 211 Free_list::dump() 212 { 213 gold_info("Free list:\n start end length\n"); 214 for (Iterator p = this->list_.begin(); p != this->list_.end(); ++p) 215 gold_info(" %08lx %08lx %08lx", static_cast<long>(p->start_), 216 static_cast<long>(p->end_), 217 static_cast<long>(p->end_ - p->start_)); 218 } 219 220 // Print the statistics for the free lists. 221 void 222 Free_list::print_stats() 223 { 224 fprintf(stderr, _("%s: total free lists: %u\n"), 225 program_name, Free_list::num_lists); 226 fprintf(stderr, _("%s: total free list nodes: %u\n"), 227 program_name, Free_list::num_nodes); 228 fprintf(stderr, _("%s: calls to Free_list::remove: %u\n"), 229 program_name, Free_list::num_removes); 230 fprintf(stderr, _("%s: nodes visited: %u\n"), 231 program_name, Free_list::num_remove_visits); 232 fprintf(stderr, _("%s: calls to Free_list::allocate: %u\n"), 233 program_name, Free_list::num_allocates); 234 fprintf(stderr, _("%s: nodes visited: %u\n"), 235 program_name, Free_list::num_allocate_visits); 236 } 237 238 // A Hash_task computes the MD5 checksum of an array of char. 239 240 class Hash_task : public Task 241 { 242 public: 243 Hash_task(Output_file* of, 244 size_t offset, 245 size_t size, 246 unsigned char* dst, 247 Task_token* final_blocker) 248 : of_(of), offset_(offset), size_(size), dst_(dst), 249 final_blocker_(final_blocker) 250 { } 251 252 void 253 run(Workqueue*) 254 { 255 const unsigned char* iv = 256 this->of_->get_input_view(this->offset_, this->size_); 257 md5_buffer(reinterpret_cast<const char*>(iv), this->size_, this->dst_); 258 this->of_->free_input_view(this->offset_, this->size_, iv); 259 } 260 261 Task_token* 262 is_runnable() 263 { return NULL; } 264 265 // Unblock FINAL_BLOCKER_ when done. 266 void 267 locks(Task_locker* tl) 268 { tl->add(this, this->final_blocker_); } 269 270 std::string 271 get_name() const 272 { return "Hash_task"; } 273 274 private: 275 Output_file* of_; 276 const size_t offset_; 277 const size_t size_; 278 unsigned char* const dst_; 279 Task_token* const final_blocker_; 280 }; 281 282 // Layout::Relaxation_debug_check methods. 283 284 // Check that sections and special data are in reset states. 285 // We do not save states for Output_sections and special Output_data. 286 // So we check that they have not assigned any addresses or offsets. 287 // clean_up_after_relaxation simply resets their addresses and offsets. 288 void 289 Layout::Relaxation_debug_check::check_output_data_for_reset_values( 290 const Layout::Section_list& sections, 291 const Layout::Data_list& special_outputs, 292 const Layout::Data_list& relax_outputs) 293 { 294 for(Layout::Section_list::const_iterator p = sections.begin(); 295 p != sections.end(); 296 ++p) 297 gold_assert((*p)->address_and_file_offset_have_reset_values()); 298 299 for(Layout::Data_list::const_iterator p = special_outputs.begin(); 300 p != special_outputs.end(); 301 ++p) 302 gold_assert((*p)->address_and_file_offset_have_reset_values()); 303 304 gold_assert(relax_outputs.empty()); 305 } 306 307 // Save information of SECTIONS for checking later. 308 309 void 310 Layout::Relaxation_debug_check::read_sections( 311 const Layout::Section_list& sections) 312 { 313 for(Layout::Section_list::const_iterator p = sections.begin(); 314 p != sections.end(); 315 ++p) 316 { 317 Output_section* os = *p; 318 Section_info info; 319 info.output_section = os; 320 info.address = os->is_address_valid() ? os->address() : 0; 321 info.data_size = os->is_data_size_valid() ? os->data_size() : -1; 322 info.offset = os->is_offset_valid()? os->offset() : -1 ; 323 this->section_infos_.push_back(info); 324 } 325 } 326 327 // Verify SECTIONS using previously recorded information. 328 329 void 330 Layout::Relaxation_debug_check::verify_sections( 331 const Layout::Section_list& sections) 332 { 333 size_t i = 0; 334 for(Layout::Section_list::const_iterator p = sections.begin(); 335 p != sections.end(); 336 ++p, ++i) 337 { 338 Output_section* os = *p; 339 uint64_t address = os->is_address_valid() ? os->address() : 0; 340 off_t data_size = os->is_data_size_valid() ? os->data_size() : -1; 341 off_t offset = os->is_offset_valid()? os->offset() : -1 ; 342 343 if (i >= this->section_infos_.size()) 344 { 345 gold_fatal("Section_info of %s missing.\n", os->name()); 346 } 347 const Section_info& info = this->section_infos_[i]; 348 if (os != info.output_section) 349 gold_fatal("Section order changed. Expecting %s but see %s\n", 350 info.output_section->name(), os->name()); 351 if (address != info.address 352 || data_size != info.data_size 353 || offset != info.offset) 354 gold_fatal("Section %s changed.\n", os->name()); 355 } 356 } 357 358 // Layout_task_runner methods. 359 360 // Lay out the sections. This is called after all the input objects 361 // have been read. 362 363 void 364 Layout_task_runner::run(Workqueue* workqueue, const Task* task) 365 { 366 // See if any of the input definitions violate the One Definition Rule. 367 // TODO: if this is too slow, do this as a task, rather than inline. 368 this->symtab_->detect_odr_violations(task, this->options_.output_file_name()); 369 370 Layout* layout = this->layout_; 371 off_t file_size = layout->finalize(this->input_objects_, 372 this->symtab_, 373 this->target_, 374 task); 375 376 // Now we know the final size of the output file and we know where 377 // each piece of information goes. 378 379 if (this->mapfile_ != NULL) 380 { 381 this->mapfile_->print_discarded_sections(this->input_objects_); 382 layout->print_to_mapfile(this->mapfile_); 383 } 384 385 Output_file* of; 386 if (layout->incremental_base() == NULL) 387 { 388 of = new Output_file(parameters->options().output_file_name()); 389 if (this->options_.oformat_enum() != General_options::OBJECT_FORMAT_ELF) 390 of->set_is_temporary(); 391 of->open(file_size); 392 } 393 else 394 { 395 of = layout->incremental_base()->output_file(); 396 397 // Apply the incremental relocations for symbols whose values 398 // have changed. We do this before we resize the file and start 399 // writing anything else to it, so that we can read the old 400 // incremental information from the file before (possibly) 401 // overwriting it. 402 if (parameters->incremental_update()) 403 layout->incremental_base()->apply_incremental_relocs(this->symtab_, 404 this->layout_, 405 of); 406 407 of->resize(file_size); 408 } 409 410 // Queue up the final set of tasks. 411 gold::queue_final_tasks(this->options_, this->input_objects_, 412 this->symtab_, layout, workqueue, of); 413 } 414 415 // Layout methods. 416 417 Layout::Layout(int number_of_input_files, Script_options* script_options) 418 : number_of_input_files_(number_of_input_files), 419 script_options_(script_options), 420 namepool_(), 421 sympool_(), 422 dynpool_(), 423 signatures_(), 424 section_name_map_(), 425 segment_list_(), 426 section_list_(), 427 unattached_section_list_(), 428 special_output_list_(), 429 relax_output_list_(), 430 section_headers_(NULL), 431 tls_segment_(NULL), 432 relro_segment_(NULL), 433 interp_segment_(NULL), 434 increase_relro_(0), 435 symtab_section_(NULL), 436 symtab_xindex_(NULL), 437 dynsym_section_(NULL), 438 dynsym_xindex_(NULL), 439 dynamic_section_(NULL), 440 dynamic_symbol_(NULL), 441 dynamic_data_(NULL), 442 eh_frame_section_(NULL), 443 eh_frame_data_(NULL), 444 added_eh_frame_data_(false), 445 eh_frame_hdr_section_(NULL), 446 gdb_index_data_(NULL), 447 build_id_note_(NULL), 448 debug_abbrev_(NULL), 449 debug_info_(NULL), 450 group_signatures_(), 451 output_file_size_(-1), 452 have_added_input_section_(false), 453 sections_are_attached_(false), 454 input_requires_executable_stack_(false), 455 input_with_gnu_stack_note_(false), 456 input_without_gnu_stack_note_(false), 457 has_static_tls_(false), 458 any_postprocessing_sections_(false), 459 resized_signatures_(false), 460 have_stabstr_section_(false), 461 section_ordering_specified_(false), 462 unique_segment_for_sections_specified_(false), 463 incremental_inputs_(NULL), 464 record_output_section_data_from_script_(false), 465 script_output_section_data_list_(), 466 segment_states_(NULL), 467 relaxation_debug_check_(NULL), 468 section_order_map_(), 469 section_segment_map_(), 470 input_section_position_(), 471 input_section_glob_(), 472 incremental_base_(NULL), 473 free_list_() 474 { 475 // Make space for more than enough segments for a typical file. 476 // This is just for efficiency--it's OK if we wind up needing more. 477 this->segment_list_.reserve(12); 478 479 // We expect two unattached Output_data objects: the file header and 480 // the segment headers. 481 this->special_output_list_.reserve(2); 482 483 // Initialize structure needed for an incremental build. 484 if (parameters->incremental()) 485 this->incremental_inputs_ = new Incremental_inputs; 486 487 // The section name pool is worth optimizing in all cases, because 488 // it is small, but there are often overlaps due to .rel sections. 489 this->namepool_.set_optimize(); 490 } 491 492 // For incremental links, record the base file to be modified. 493 494 void 495 Layout::set_incremental_base(Incremental_binary* base) 496 { 497 this->incremental_base_ = base; 498 this->free_list_.init(base->output_file()->filesize(), true); 499 } 500 501 // Hash a key we use to look up an output section mapping. 502 503 size_t 504 Layout::Hash_key::operator()(const Layout::Key& k) const 505 { 506 return k.first + k.second.first + k.second.second; 507 } 508 509 // These are the debug sections that are actually used by gdb. 510 // Currently, we've checked versions of gdb up to and including 7.4. 511 // We only check the part of the name that follows ".debug_" or 512 // ".zdebug_". 513 514 static const char* gdb_sections[] = 515 { 516 "abbrev", 517 "addr", // Fission extension 518 // "aranges", // not used by gdb as of 7.4 519 "frame", 520 "gdb_scripts", 521 "info", 522 "types", 523 "line", 524 "loc", 525 "macinfo", 526 "macro", 527 // "pubnames", // not used by gdb as of 7.4 528 // "pubtypes", // not used by gdb as of 7.4 529 // "gnu_pubnames", // Fission extension 530 // "gnu_pubtypes", // Fission extension 531 "ranges", 532 "str", 533 "str_offsets", 534 }; 535 536 // This is the minimum set of sections needed for line numbers. 537 538 static const char* lines_only_debug_sections[] = 539 { 540 "abbrev", 541 // "addr", // Fission extension 542 // "aranges", // not used by gdb as of 7.4 543 // "frame", 544 // "gdb_scripts", 545 "info", 546 // "types", 547 "line", 548 // "loc", 549 // "macinfo", 550 // "macro", 551 // "pubnames", // not used by gdb as of 7.4 552 // "pubtypes", // not used by gdb as of 7.4 553 // "gnu_pubnames", // Fission extension 554 // "gnu_pubtypes", // Fission extension 555 // "ranges", 556 "str", 557 "str_offsets", // Fission extension 558 }; 559 560 // These sections are the DWARF fast-lookup tables, and are not needed 561 // when building a .gdb_index section. 562 563 static const char* gdb_fast_lookup_sections[] = 564 { 565 "aranges", 566 "pubnames", 567 "gnu_pubnames", 568 "pubtypes", 569 "gnu_pubtypes", 570 }; 571 572 // Returns whether the given debug section is in the list of 573 // debug-sections-used-by-some-version-of-gdb. SUFFIX is the 574 // portion of the name following ".debug_" or ".zdebug_". 575 576 static inline bool 577 is_gdb_debug_section(const char* suffix) 578 { 579 // We can do this faster: binary search or a hashtable. But why bother? 580 for (size_t i = 0; i < sizeof(gdb_sections)/sizeof(*gdb_sections); ++i) 581 if (strcmp(suffix, gdb_sections[i]) == 0) 582 return true; 583 return false; 584 } 585 586 // Returns whether the given section is needed for lines-only debugging. 587 588 static inline bool 589 is_lines_only_debug_section(const char* suffix) 590 { 591 // We can do this faster: binary search or a hashtable. But why bother? 592 for (size_t i = 0; 593 i < sizeof(lines_only_debug_sections)/sizeof(*lines_only_debug_sections); 594 ++i) 595 if (strcmp(suffix, lines_only_debug_sections[i]) == 0) 596 return true; 597 return false; 598 } 599 600 // Returns whether the given section is a fast-lookup section that 601 // will not be needed when building a .gdb_index section. 602 603 static inline bool 604 is_gdb_fast_lookup_section(const char* suffix) 605 { 606 // We can do this faster: binary search or a hashtable. But why bother? 607 for (size_t i = 0; 608 i < sizeof(gdb_fast_lookup_sections)/sizeof(*gdb_fast_lookup_sections); 609 ++i) 610 if (strcmp(suffix, gdb_fast_lookup_sections[i]) == 0) 611 return true; 612 return false; 613 } 614 615 // Sometimes we compress sections. This is typically done for 616 // sections that are not part of normal program execution (such as 617 // .debug_* sections), and where the readers of these sections know 618 // how to deal with compressed sections. This routine doesn't say for 619 // certain whether we'll compress -- it depends on commandline options 620 // as well -- just whether this section is a candidate for compression. 621 // (The Output_compressed_section class decides whether to compress 622 // a given section, and picks the name of the compressed section.) 623 624 static bool 625 is_compressible_debug_section(const char* secname) 626 { 627 return (is_prefix_of(".debug", secname)); 628 } 629 630 // We may see compressed debug sections in input files. Return TRUE 631 // if this is the name of a compressed debug section. 632 633 bool 634 is_compressed_debug_section(const char* secname) 635 { 636 return (is_prefix_of(".zdebug", secname)); 637 } 638 639 std::string 640 corresponding_uncompressed_section_name(std::string secname) 641 { 642 gold_assert(secname[0] == '.' && secname[1] == 'z'); 643 std::string ret("."); 644 ret.append(secname, 2, std::string::npos); 645 return ret; 646 } 647 648 // Whether to include this section in the link. 649 650 template<int size, bool big_endian> 651 bool 652 Layout::include_section(Sized_relobj_file<size, big_endian>*, const char* name, 653 const elfcpp::Shdr<size, big_endian>& shdr) 654 { 655 if (!parameters->options().relocatable() 656 && (shdr.get_sh_flags() & elfcpp::SHF_EXCLUDE)) 657 return false; 658 659 elfcpp::Elf_Word sh_type = shdr.get_sh_type(); 660 661 if ((sh_type >= elfcpp::SHT_LOOS && sh_type <= elfcpp::SHT_HIOS) 662 || (sh_type >= elfcpp::SHT_LOPROC && sh_type <= elfcpp::SHT_HIPROC)) 663 return parameters->target().should_include_section(sh_type); 664 665 switch (sh_type) 666 { 667 case elfcpp::SHT_NULL: 668 case elfcpp::SHT_SYMTAB: 669 case elfcpp::SHT_DYNSYM: 670 case elfcpp::SHT_HASH: 671 case elfcpp::SHT_DYNAMIC: 672 case elfcpp::SHT_SYMTAB_SHNDX: 673 return false; 674 675 case elfcpp::SHT_STRTAB: 676 // Discard the sections which have special meanings in the ELF 677 // ABI. Keep others (e.g., .stabstr). We could also do this by 678 // checking the sh_link fields of the appropriate sections. 679 return (strcmp(name, ".dynstr") != 0 680 && strcmp(name, ".strtab") != 0 681 && strcmp(name, ".shstrtab") != 0); 682 683 case elfcpp::SHT_RELA: 684 case elfcpp::SHT_REL: 685 case elfcpp::SHT_GROUP: 686 // If we are emitting relocations these should be handled 687 // elsewhere. 688 gold_assert(!parameters->options().relocatable()); 689 return false; 690 691 case elfcpp::SHT_PROGBITS: 692 if (parameters->options().strip_debug() 693 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0) 694 { 695 if (is_debug_info_section(name)) 696 return false; 697 } 698 if (parameters->options().strip_debug_non_line() 699 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0) 700 { 701 // Debugging sections can only be recognized by name. 702 if (is_prefix_of(".debug_", name) 703 && !is_lines_only_debug_section(name + 7)) 704 return false; 705 if (is_prefix_of(".zdebug_", name) 706 && !is_lines_only_debug_section(name + 8)) 707 return false; 708 } 709 if (parameters->options().strip_debug_gdb() 710 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0) 711 { 712 // Debugging sections can only be recognized by name. 713 if (is_prefix_of(".debug_", name) 714 && !is_gdb_debug_section(name + 7)) 715 return false; 716 if (is_prefix_of(".zdebug_", name) 717 && !is_gdb_debug_section(name + 8)) 718 return false; 719 } 720 if (parameters->options().gdb_index() 721 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0) 722 { 723 // When building .gdb_index, we can strip .debug_pubnames, 724 // .debug_pubtypes, and .debug_aranges sections. 725 if (is_prefix_of(".debug_", name) 726 && is_gdb_fast_lookup_section(name + 7)) 727 return false; 728 if (is_prefix_of(".zdebug_", name) 729 && is_gdb_fast_lookup_section(name + 8)) 730 return false; 731 } 732 if (parameters->options().strip_lto_sections() 733 && !parameters->options().relocatable() 734 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0) 735 { 736 // Ignore LTO sections containing intermediate code. 737 if (is_prefix_of(".gnu.lto_", name)) 738 return false; 739 } 740 // The GNU linker strips .gnu_debuglink sections, so we do too. 741 // This is a feature used to keep debugging information in 742 // separate files. 743 if (strcmp(name, ".gnu_debuglink") == 0) 744 return false; 745 return true; 746 747 default: 748 return true; 749 } 750 } 751 752 // Return an output section named NAME, or NULL if there is none. 753 754 Output_section* 755 Layout::find_output_section(const char* name) const 756 { 757 for (Section_list::const_iterator p = this->section_list_.begin(); 758 p != this->section_list_.end(); 759 ++p) 760 if (strcmp((*p)->name(), name) == 0) 761 return *p; 762 return NULL; 763 } 764 765 // Return an output segment of type TYPE, with segment flags SET set 766 // and segment flags CLEAR clear. Return NULL if there is none. 767 768 Output_segment* 769 Layout::find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set, 770 elfcpp::Elf_Word clear) const 771 { 772 for (Segment_list::const_iterator p = this->segment_list_.begin(); 773 p != this->segment_list_.end(); 774 ++p) 775 if (static_cast<elfcpp::PT>((*p)->type()) == type 776 && ((*p)->flags() & set) == set 777 && ((*p)->flags() & clear) == 0) 778 return *p; 779 return NULL; 780 } 781 782 // When we put a .ctors or .dtors section with more than one word into 783 // a .init_array or .fini_array section, we need to reverse the words 784 // in the .ctors/.dtors section. This is because .init_array executes 785 // constructors front to back, where .ctors executes them back to 786 // front, and vice-versa for .fini_array/.dtors. Although we do want 787 // to remap .ctors/.dtors into .init_array/.fini_array because it can 788 // be more efficient, we don't want to change the order in which 789 // constructors/destructors are run. This set just keeps track of 790 // these sections which need to be reversed. It is only changed by 791 // Layout::layout. It should be a private member of Layout, but that 792 // would require layout.h to #include object.h to get the definition 793 // of Section_id. 794 static Unordered_set<Section_id, Section_id_hash> ctors_sections_in_init_array; 795 796 // Return whether OBJECT/SHNDX is a .ctors/.dtors section mapped to a 797 // .init_array/.fini_array section. 798 799 bool 800 Layout::is_ctors_in_init_array(Relobj* relobj, unsigned int shndx) const 801 { 802 return (ctors_sections_in_init_array.find(Section_id(relobj, shndx)) 803 != ctors_sections_in_init_array.end()); 804 } 805 806 // Return the output section to use for section NAME with type TYPE 807 // and section flags FLAGS. NAME must be canonicalized in the string 808 // pool, and NAME_KEY is the key. ORDER is where this should appear 809 // in the output sections. IS_RELRO is true for a relro section. 810 811 Output_section* 812 Layout::get_output_section(const char* name, Stringpool::Key name_key, 813 elfcpp::Elf_Word type, elfcpp::Elf_Xword flags, 814 Output_section_order order, bool is_relro) 815 { 816 elfcpp::Elf_Word lookup_type = type; 817 818 // For lookup purposes, treat INIT_ARRAY, FINI_ARRAY, and 819 // PREINIT_ARRAY like PROGBITS. This ensures that we combine 820 // .init_array, .fini_array, and .preinit_array sections by name 821 // whatever their type in the input file. We do this because the 822 // types are not always right in the input files. 823 if (lookup_type == elfcpp::SHT_INIT_ARRAY 824 || lookup_type == elfcpp::SHT_FINI_ARRAY 825 || lookup_type == elfcpp::SHT_PREINIT_ARRAY) 826 lookup_type = elfcpp::SHT_PROGBITS; 827 828 elfcpp::Elf_Xword lookup_flags = flags; 829 830 // Ignoring SHF_WRITE and SHF_EXECINSTR here means that we combine 831 // read-write with read-only sections. Some other ELF linkers do 832 // not do this. FIXME: Perhaps there should be an option 833 // controlling this. 834 lookup_flags &= ~(elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR); 835 836 const Key key(name_key, std::make_pair(lookup_type, lookup_flags)); 837 const std::pair<Key, Output_section*> v(key, NULL); 838 std::pair<Section_name_map::iterator, bool> ins( 839 this->section_name_map_.insert(v)); 840 841 if (!ins.second) 842 return ins.first->second; 843 else 844 { 845 // This is the first time we've seen this name/type/flags 846 // combination. For compatibility with the GNU linker, we 847 // combine sections with contents and zero flags with sections 848 // with non-zero flags. This is a workaround for cases where 849 // assembler code forgets to set section flags. FIXME: Perhaps 850 // there should be an option to control this. 851 Output_section* os = NULL; 852 853 if (lookup_type == elfcpp::SHT_PROGBITS) 854 { 855 if (flags == 0) 856 { 857 Output_section* same_name = this->find_output_section(name); 858 if (same_name != NULL 859 && (same_name->type() == elfcpp::SHT_PROGBITS 860 || same_name->type() == elfcpp::SHT_INIT_ARRAY 861 || same_name->type() == elfcpp::SHT_FINI_ARRAY 862 || same_name->type() == elfcpp::SHT_PREINIT_ARRAY) 863 && (same_name->flags() & elfcpp::SHF_TLS) == 0) 864 os = same_name; 865 } 866 else if ((flags & elfcpp::SHF_TLS) == 0) 867 { 868 elfcpp::Elf_Xword zero_flags = 0; 869 const Key zero_key(name_key, std::make_pair(lookup_type, 870 zero_flags)); 871 Section_name_map::iterator p = 872 this->section_name_map_.find(zero_key); 873 if (p != this->section_name_map_.end()) 874 os = p->second; 875 } 876 } 877 878 if (os == NULL) 879 os = this->make_output_section(name, type, flags, order, is_relro); 880 881 ins.first->second = os; 882 return os; 883 } 884 } 885 886 // Returns TRUE iff NAME (an input section from RELOBJ) will 887 // be mapped to an output section that should be KEPT. 888 889 bool 890 Layout::keep_input_section(const Relobj* relobj, const char* name) 891 { 892 if (! this->script_options_->saw_sections_clause()) 893 return false; 894 895 Script_sections* ss = this->script_options_->script_sections(); 896 const char* file_name = relobj == NULL ? NULL : relobj->name().c_str(); 897 Output_section** output_section_slot; 898 Script_sections::Section_type script_section_type; 899 bool keep; 900 901 name = ss->output_section_name(file_name, name, &output_section_slot, 902 &script_section_type, &keep); 903 return name != NULL && keep; 904 } 905 906 // Clear the input section flags that should not be copied to the 907 // output section. 908 909 elfcpp::Elf_Xword 910 Layout::get_output_section_flags(elfcpp::Elf_Xword input_section_flags) 911 { 912 // Some flags in the input section should not be automatically 913 // copied to the output section. 914 input_section_flags &= ~ (elfcpp::SHF_INFO_LINK 915 | elfcpp::SHF_GROUP 916 | elfcpp::SHF_COMPRESSED 917 | elfcpp::SHF_MERGE 918 | elfcpp::SHF_STRINGS); 919 920 // We only clear the SHF_LINK_ORDER flag in for 921 // a non-relocatable link. 922 if (!parameters->options().relocatable()) 923 input_section_flags &= ~elfcpp::SHF_LINK_ORDER; 924 925 return input_section_flags; 926 } 927 928 // Pick the output section to use for section NAME, in input file 929 // RELOBJ, with type TYPE and flags FLAGS. RELOBJ may be NULL for a 930 // linker created section. IS_INPUT_SECTION is true if we are 931 // choosing an output section for an input section found in a input 932 // file. ORDER is where this section should appear in the output 933 // sections. IS_RELRO is true for a relro section. This will return 934 // NULL if the input section should be discarded. 935 936 Output_section* 937 Layout::choose_output_section(const Relobj* relobj, const char* name, 938 elfcpp::Elf_Word type, elfcpp::Elf_Xword flags, 939 bool is_input_section, Output_section_order order, 940 bool is_relro) 941 { 942 // We should not see any input sections after we have attached 943 // sections to segments. 944 gold_assert(!is_input_section || !this->sections_are_attached_); 945 946 flags = this->get_output_section_flags(flags); 947 948 if (this->script_options_->saw_sections_clause()) 949 { 950 // We are using a SECTIONS clause, so the output section is 951 // chosen based only on the name. 952 953 Script_sections* ss = this->script_options_->script_sections(); 954 const char* file_name = relobj == NULL ? NULL : relobj->name().c_str(); 955 Output_section** output_section_slot; 956 Script_sections::Section_type script_section_type; 957 const char* orig_name = name; 958 bool keep; 959 name = ss->output_section_name(file_name, name, &output_section_slot, 960 &script_section_type, &keep); 961 962 if (name == NULL) 963 { 964 gold_debug(DEBUG_SCRIPT, _("Unable to create output section '%s' " 965 "because it is not allowed by the " 966 "SECTIONS clause of the linker script"), 967 orig_name); 968 // The SECTIONS clause says to discard this input section. 969 return NULL; 970 } 971 972 // We can only handle script section types ST_NONE and ST_NOLOAD. 973 switch (script_section_type) 974 { 975 case Script_sections::ST_NONE: 976 break; 977 case Script_sections::ST_NOLOAD: 978 flags &= elfcpp::SHF_ALLOC; 979 break; 980 default: 981 gold_unreachable(); 982 } 983 984 // If this is an orphan section--one not mentioned in the linker 985 // script--then OUTPUT_SECTION_SLOT will be NULL, and we do the 986 // default processing below. 987 988 if (output_section_slot != NULL) 989 { 990 if (*output_section_slot != NULL) 991 { 992 (*output_section_slot)->update_flags_for_input_section(flags); 993 return *output_section_slot; 994 } 995 996 // We don't put sections found in the linker script into 997 // SECTION_NAME_MAP_. That keeps us from getting confused 998 // if an orphan section is mapped to a section with the same 999 // name as one in the linker script. 1000 1001 name = this->namepool_.add(name, false, NULL); 1002 1003 Output_section* os = this->make_output_section(name, type, flags, 1004 order, is_relro); 1005 1006 os->set_found_in_sections_clause(); 1007 1008 // Special handling for NOLOAD sections. 1009 if (script_section_type == Script_sections::ST_NOLOAD) 1010 { 1011 os->set_is_noload(); 1012 1013 // The constructor of Output_section sets addresses of non-ALLOC 1014 // sections to 0 by default. We don't want that for NOLOAD 1015 // sections even if they have no SHF_ALLOC flag. 1016 if ((os->flags() & elfcpp::SHF_ALLOC) == 0 1017 && os->is_address_valid()) 1018 { 1019 gold_assert(os->address() == 0 1020 && !os->is_offset_valid() 1021 && !os->is_data_size_valid()); 1022 os->reset_address_and_file_offset(); 1023 } 1024 } 1025 1026 *output_section_slot = os; 1027 return os; 1028 } 1029 } 1030 1031 // FIXME: Handle SHF_OS_NONCONFORMING somewhere. 1032 1033 size_t len = strlen(name); 1034 std::string uncompressed_name; 1035 1036 // Compressed debug sections should be mapped to the corresponding 1037 // uncompressed section. 1038 if (is_compressed_debug_section(name)) 1039 { 1040 uncompressed_name = 1041 corresponding_uncompressed_section_name(std::string(name, len)); 1042 name = uncompressed_name.c_str(); 1043 len = uncompressed_name.length(); 1044 } 1045 1046 // Turn NAME from the name of the input section into the name of the 1047 // output section. 1048 if (is_input_section 1049 && !this->script_options_->saw_sections_clause() 1050 && !parameters->options().relocatable()) 1051 { 1052 const char *orig_name = name; 1053 name = parameters->target().output_section_name(relobj, name, &len); 1054 if (name == NULL) 1055 name = Layout::output_section_name(relobj, orig_name, &len); 1056 } 1057 1058 Stringpool::Key name_key; 1059 name = this->namepool_.add_with_length(name, len, true, &name_key); 1060 1061 // Find or make the output section. The output section is selected 1062 // based on the section name, type, and flags. 1063 return this->get_output_section(name, name_key, type, flags, order, is_relro); 1064 } 1065 1066 // For incremental links, record the initial fixed layout of a section 1067 // from the base file, and return a pointer to the Output_section. 1068 1069 template<int size, bool big_endian> 1070 Output_section* 1071 Layout::init_fixed_output_section(const char* name, 1072 elfcpp::Shdr<size, big_endian>& shdr) 1073 { 1074 unsigned int sh_type = shdr.get_sh_type(); 1075 1076 // We preserve the layout of PROGBITS, NOBITS, INIT_ARRAY, FINI_ARRAY, 1077 // PRE_INIT_ARRAY, and NOTE sections. 1078 // All others will be created from scratch and reallocated. 1079 if (!can_incremental_update(sh_type)) 1080 return NULL; 1081 1082 // If we're generating a .gdb_index section, we need to regenerate 1083 // it from scratch. 1084 if (parameters->options().gdb_index() 1085 && sh_type == elfcpp::SHT_PROGBITS 1086 && strcmp(name, ".gdb_index") == 0) 1087 return NULL; 1088 1089 typename elfcpp::Elf_types<size>::Elf_Addr sh_addr = shdr.get_sh_addr(); 1090 typename elfcpp::Elf_types<size>::Elf_Off sh_offset = shdr.get_sh_offset(); 1091 typename elfcpp::Elf_types<size>::Elf_WXword sh_size = shdr.get_sh_size(); 1092 typename elfcpp::Elf_types<size>::Elf_WXword sh_flags = shdr.get_sh_flags(); 1093 typename elfcpp::Elf_types<size>::Elf_WXword sh_addralign = 1094 shdr.get_sh_addralign(); 1095 1096 // Make the output section. 1097 Stringpool::Key name_key; 1098 name = this->namepool_.add(name, true, &name_key); 1099 Output_section* os = this->get_output_section(name, name_key, sh_type, 1100 sh_flags, ORDER_INVALID, false); 1101 os->set_fixed_layout(sh_addr, sh_offset, sh_size, sh_addralign); 1102 if (sh_type != elfcpp::SHT_NOBITS) 1103 this->free_list_.remove(sh_offset, sh_offset + sh_size); 1104 return os; 1105 } 1106 1107 // Return the index by which an input section should be ordered. This 1108 // is used to sort some .text sections, for compatibility with GNU ld. 1109 1110 int 1111 Layout::special_ordering_of_input_section(const char* name) 1112 { 1113 // The GNU linker has some special handling for some sections that 1114 // wind up in the .text section. Sections that start with these 1115 // prefixes must appear first, and must appear in the order listed 1116 // here. 1117 static const char* const text_section_sort[] = 1118 { 1119 ".text.unlikely", 1120 ".text.exit", 1121 ".text.startup", 1122 ".text.hot" 1123 }; 1124 1125 for (size_t i = 0; 1126 i < sizeof(text_section_sort) / sizeof(text_section_sort[0]); 1127 i++) 1128 if (is_prefix_of(text_section_sort[i], name)) 1129 return i; 1130 1131 return -1; 1132 } 1133 1134 // Return the output section to use for input section SHNDX, with name 1135 // NAME, with header HEADER, from object OBJECT. RELOC_SHNDX is the 1136 // index of a relocation section which applies to this section, or 0 1137 // if none, or -1U if more than one. RELOC_TYPE is the type of the 1138 // relocation section if there is one. Set *OFF to the offset of this 1139 // input section without the output section. Return NULL if the 1140 // section should be discarded. Set *OFF to -1 if the section 1141 // contents should not be written directly to the output file, but 1142 // will instead receive special handling. 1143 1144 template<int size, bool big_endian> 1145 Output_section* 1146 Layout::layout(Sized_relobj_file<size, big_endian>* object, unsigned int shndx, 1147 const char* name, const elfcpp::Shdr<size, big_endian>& shdr, 1148 unsigned int reloc_shndx, unsigned int, off_t* off) 1149 { 1150 *off = 0; 1151 1152 if (!this->include_section(object, name, shdr)) 1153 return NULL; 1154 1155 elfcpp::Elf_Word sh_type = shdr.get_sh_type(); 1156 1157 // In a relocatable link a grouped section must not be combined with 1158 // any other sections. 1159 Output_section* os; 1160 if (parameters->options().relocatable() 1161 && (shdr.get_sh_flags() & elfcpp::SHF_GROUP) != 0) 1162 { 1163 // Some flags in the input section should not be automatically 1164 // copied to the output section. 1165 elfcpp::Elf_Xword flags = (shdr.get_sh_flags() 1166 & ~ elfcpp::SHF_COMPRESSED); 1167 name = this->namepool_.add(name, true, NULL); 1168 os = this->make_output_section(name, sh_type, flags, 1169 ORDER_INVALID, false); 1170 } 1171 else 1172 { 1173 // Plugins can choose to place one or more subsets of sections in 1174 // unique segments and this is done by mapping these section subsets 1175 // to unique output sections. Check if this section needs to be 1176 // remapped to a unique output section. 1177 Section_segment_map::iterator it 1178 = this->section_segment_map_.find(Const_section_id(object, shndx)); 1179 if (it == this->section_segment_map_.end()) 1180 { 1181 os = this->choose_output_section(object, name, sh_type, 1182 shdr.get_sh_flags(), true, 1183 ORDER_INVALID, false); 1184 } 1185 else 1186 { 1187 // We know the name of the output section, directly call 1188 // get_output_section here by-passing choose_output_section. 1189 elfcpp::Elf_Xword flags 1190 = this->get_output_section_flags(shdr.get_sh_flags()); 1191 1192 const char* os_name = it->second->name; 1193 Stringpool::Key name_key; 1194 os_name = this->namepool_.add(os_name, true, &name_key); 1195 os = this->get_output_section(os_name, name_key, sh_type, flags, 1196 ORDER_INVALID, false); 1197 if (!os->is_unique_segment()) 1198 { 1199 os->set_is_unique_segment(); 1200 os->set_extra_segment_flags(it->second->flags); 1201 os->set_segment_alignment(it->second->align); 1202 } 1203 } 1204 if (os == NULL) 1205 return NULL; 1206 } 1207 1208 // By default the GNU linker sorts input sections whose names match 1209 // .ctors.*, .dtors.*, .init_array.*, or .fini_array.*. The 1210 // sections are sorted by name. This is used to implement 1211 // constructor priority ordering. We are compatible. When we put 1212 // .ctor sections in .init_array and .dtor sections in .fini_array, 1213 // we must also sort plain .ctor and .dtor sections. 1214 if (!this->script_options_->saw_sections_clause() 1215 && !parameters->options().relocatable() 1216 && (is_prefix_of(".ctors.", name) 1217 || is_prefix_of(".dtors.", name) 1218 || is_prefix_of(".init_array.", name) 1219 || is_prefix_of(".fini_array.", name) 1220 || (parameters->options().ctors_in_init_array() 1221 && (strcmp(name, ".ctors") == 0 1222 || strcmp(name, ".dtors") == 0)))) 1223 os->set_must_sort_attached_input_sections(); 1224 1225 // By default the GNU linker sorts some special text sections ahead 1226 // of others. We are compatible. 1227 if (parameters->options().text_reorder() 1228 && !this->script_options_->saw_sections_clause() 1229 && !this->is_section_ordering_specified() 1230 && !parameters->options().relocatable() 1231 && Layout::special_ordering_of_input_section(name) >= 0) 1232 os->set_must_sort_attached_input_sections(); 1233 1234 // If this is a .ctors or .ctors.* section being mapped to a 1235 // .init_array section, or a .dtors or .dtors.* section being mapped 1236 // to a .fini_array section, we will need to reverse the words if 1237 // there is more than one. Record this section for later. See 1238 // ctors_sections_in_init_array above. 1239 if (!this->script_options_->saw_sections_clause() 1240 && !parameters->options().relocatable() 1241 && shdr.get_sh_size() > size / 8 1242 && (((strcmp(name, ".ctors") == 0 1243 || is_prefix_of(".ctors.", name)) 1244 && strcmp(os->name(), ".init_array") == 0) 1245 || ((strcmp(name, ".dtors") == 0 1246 || is_prefix_of(".dtors.", name)) 1247 && strcmp(os->name(), ".fini_array") == 0))) 1248 ctors_sections_in_init_array.insert(Section_id(object, shndx)); 1249 1250 // FIXME: Handle SHF_LINK_ORDER somewhere. 1251 1252 elfcpp::Elf_Xword orig_flags = os->flags(); 1253 1254 *off = os->add_input_section(this, object, shndx, name, shdr, reloc_shndx, 1255 this->script_options_->saw_sections_clause()); 1256 1257 // If the flags changed, we may have to change the order. 1258 if ((orig_flags & elfcpp::SHF_ALLOC) != 0) 1259 { 1260 orig_flags &= (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR); 1261 elfcpp::Elf_Xword new_flags = 1262 os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR); 1263 if (orig_flags != new_flags) 1264 os->set_order(this->default_section_order(os, false)); 1265 } 1266 1267 this->have_added_input_section_ = true; 1268 1269 return os; 1270 } 1271 1272 // Maps section SECN to SEGMENT s. 1273 void 1274 Layout::insert_section_segment_map(Const_section_id secn, 1275 Unique_segment_info *s) 1276 { 1277 gold_assert(this->unique_segment_for_sections_specified_); 1278 this->section_segment_map_[secn] = s; 1279 } 1280 1281 // Handle a relocation section when doing a relocatable link. 1282 1283 template<int size, bool big_endian> 1284 Output_section* 1285 Layout::layout_reloc(Sized_relobj_file<size, big_endian>* object, 1286 unsigned int, 1287 const elfcpp::Shdr<size, big_endian>& shdr, 1288 Output_section* data_section, 1289 Relocatable_relocs* rr) 1290 { 1291 gold_assert(parameters->options().relocatable() 1292 || parameters->options().emit_relocs()); 1293 1294 int sh_type = shdr.get_sh_type(); 1295 1296 std::string name; 1297 if (sh_type == elfcpp::SHT_REL) 1298 name = ".rel"; 1299 else if (sh_type == elfcpp::SHT_RELA) 1300 name = ".rela"; 1301 else 1302 gold_unreachable(); 1303 name += data_section->name(); 1304 1305 // In a relocatable link relocs for a grouped section must not be 1306 // combined with other reloc sections. 1307 Output_section* os; 1308 if (!parameters->options().relocatable() 1309 || (data_section->flags() & elfcpp::SHF_GROUP) == 0) 1310 os = this->choose_output_section(object, name.c_str(), sh_type, 1311 shdr.get_sh_flags(), false, 1312 ORDER_INVALID, false); 1313 else 1314 { 1315 const char* n = this->namepool_.add(name.c_str(), true, NULL); 1316 os = this->make_output_section(n, sh_type, shdr.get_sh_flags(), 1317 ORDER_INVALID, false); 1318 } 1319 1320 os->set_should_link_to_symtab(); 1321 os->set_info_section(data_section); 1322 1323 Output_section_data* posd; 1324 if (sh_type == elfcpp::SHT_REL) 1325 { 1326 os->set_entsize(elfcpp::Elf_sizes<size>::rel_size); 1327 posd = new Output_relocatable_relocs<elfcpp::SHT_REL, 1328 size, 1329 big_endian>(rr); 1330 } 1331 else if (sh_type == elfcpp::SHT_RELA) 1332 { 1333 os->set_entsize(elfcpp::Elf_sizes<size>::rela_size); 1334 posd = new Output_relocatable_relocs<elfcpp::SHT_RELA, 1335 size, 1336 big_endian>(rr); 1337 } 1338 else 1339 gold_unreachable(); 1340 1341 os->add_output_section_data(posd); 1342 rr->set_output_data(posd); 1343 1344 return os; 1345 } 1346 1347 // Handle a group section when doing a relocatable link. 1348 1349 template<int size, bool big_endian> 1350 void 1351 Layout::layout_group(Symbol_table* symtab, 1352 Sized_relobj_file<size, big_endian>* object, 1353 unsigned int, 1354 const char* group_section_name, 1355 const char* signature, 1356 const elfcpp::Shdr<size, big_endian>& shdr, 1357 elfcpp::Elf_Word flags, 1358 std::vector<unsigned int>* shndxes) 1359 { 1360 gold_assert(parameters->options().relocatable()); 1361 gold_assert(shdr.get_sh_type() == elfcpp::SHT_GROUP); 1362 group_section_name = this->namepool_.add(group_section_name, true, NULL); 1363 Output_section* os = this->make_output_section(group_section_name, 1364 elfcpp::SHT_GROUP, 1365 shdr.get_sh_flags(), 1366 ORDER_INVALID, false); 1367 1368 // We need to find a symbol with the signature in the symbol table. 1369 // If we don't find one now, we need to look again later. 1370 Symbol* sym = symtab->lookup(signature, NULL); 1371 if (sym != NULL) 1372 os->set_info_symndx(sym); 1373 else 1374 { 1375 // Reserve some space to minimize reallocations. 1376 if (this->group_signatures_.empty()) 1377 this->group_signatures_.reserve(this->number_of_input_files_ * 16); 1378 1379 // We will wind up using a symbol whose name is the signature. 1380 // So just put the signature in the symbol name pool to save it. 1381 signature = symtab->canonicalize_name(signature); 1382 this->group_signatures_.push_back(Group_signature(os, signature)); 1383 } 1384 1385 os->set_should_link_to_symtab(); 1386 os->set_entsize(4); 1387 1388 section_size_type entry_count = 1389 convert_to_section_size_type(shdr.get_sh_size() / 4); 1390 Output_section_data* posd = 1391 new Output_data_group<size, big_endian>(object, entry_count, flags, 1392 shndxes); 1393 os->add_output_section_data(posd); 1394 } 1395 1396 // Special GNU handling of sections name .eh_frame. They will 1397 // normally hold exception frame data as defined by the C++ ABI 1398 // (http://codesourcery.com/cxx-abi/). 1399 1400 template<int size, bool big_endian> 1401 Output_section* 1402 Layout::layout_eh_frame(Sized_relobj_file<size, big_endian>* object, 1403 const unsigned char* symbols, 1404 off_t symbols_size, 1405 const unsigned char* symbol_names, 1406 off_t symbol_names_size, 1407 unsigned int shndx, 1408 const elfcpp::Shdr<size, big_endian>& shdr, 1409 unsigned int reloc_shndx, unsigned int reloc_type, 1410 off_t* off) 1411 { 1412 gold_assert(shdr.get_sh_type() == elfcpp::SHT_PROGBITS 1413 || shdr.get_sh_type() == elfcpp::SHT_X86_64_UNWIND); 1414 gold_assert((shdr.get_sh_flags() & elfcpp::SHF_ALLOC) != 0); 1415 1416 Output_section* os = this->make_eh_frame_section(object); 1417 if (os == NULL) 1418 return NULL; 1419 1420 gold_assert(this->eh_frame_section_ == os); 1421 1422 elfcpp::Elf_Xword orig_flags = os->flags(); 1423 1424 Eh_frame::Eh_frame_section_disposition disp = 1425 Eh_frame::EH_UNRECOGNIZED_SECTION; 1426 if (!parameters->incremental()) 1427 { 1428 disp = this->eh_frame_data_->add_ehframe_input_section(object, 1429 symbols, 1430 symbols_size, 1431 symbol_names, 1432 symbol_names_size, 1433 shndx, 1434 reloc_shndx, 1435 reloc_type); 1436 } 1437 1438 if (disp == Eh_frame::EH_OPTIMIZABLE_SECTION) 1439 { 1440 os->update_flags_for_input_section(shdr.get_sh_flags()); 1441 1442 // A writable .eh_frame section is a RELRO section. 1443 if ((orig_flags & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR)) 1444 != (os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR))) 1445 { 1446 os->set_is_relro(); 1447 os->set_order(ORDER_RELRO); 1448 } 1449 1450 *off = -1; 1451 return os; 1452 } 1453 1454 if (disp == Eh_frame::EH_END_MARKER_SECTION && !this->added_eh_frame_data_) 1455 { 1456 // We found the end marker section, so now we can add the set of 1457 // optimized sections to the output section. We need to postpone 1458 // adding this until we've found a section we can optimize so that 1459 // the .eh_frame section in crtbeginT.o winds up at the start of 1460 // the output section. 1461 os->add_output_section_data(this->eh_frame_data_); 1462 this->added_eh_frame_data_ = true; 1463 } 1464 1465 // We couldn't handle this .eh_frame section for some reason. 1466 // Add it as a normal section. 1467 bool saw_sections_clause = this->script_options_->saw_sections_clause(); 1468 *off = os->add_input_section(this, object, shndx, ".eh_frame", shdr, 1469 reloc_shndx, saw_sections_clause); 1470 this->have_added_input_section_ = true; 1471 1472 if ((orig_flags & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR)) 1473 != (os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR))) 1474 os->set_order(this->default_section_order(os, false)); 1475 1476 return os; 1477 } 1478 1479 void 1480 Layout::finalize_eh_frame_section() 1481 { 1482 // If we never found an end marker section, we need to add the 1483 // optimized eh sections to the output section now. 1484 if (!parameters->incremental() 1485 && this->eh_frame_section_ != NULL 1486 && !this->added_eh_frame_data_) 1487 { 1488 this->eh_frame_section_->add_output_section_data(this->eh_frame_data_); 1489 this->added_eh_frame_data_ = true; 1490 } 1491 } 1492 1493 // Create and return the magic .eh_frame section. Create 1494 // .eh_frame_hdr also if appropriate. OBJECT is the object with the 1495 // input .eh_frame section; it may be NULL. 1496 1497 Output_section* 1498 Layout::make_eh_frame_section(const Relobj* object) 1499 { 1500 // FIXME: On x86_64, this could use SHT_X86_64_UNWIND rather than 1501 // SHT_PROGBITS. 1502 Output_section* os = this->choose_output_section(object, ".eh_frame", 1503 elfcpp::SHT_PROGBITS, 1504 elfcpp::SHF_ALLOC, false, 1505 ORDER_EHFRAME, false); 1506 if (os == NULL) 1507 return NULL; 1508 1509 if (this->eh_frame_section_ == NULL) 1510 { 1511 this->eh_frame_section_ = os; 1512 this->eh_frame_data_ = new Eh_frame(); 1513 1514 // For incremental linking, we do not optimize .eh_frame sections 1515 // or create a .eh_frame_hdr section. 1516 if (parameters->options().eh_frame_hdr() && !parameters->incremental()) 1517 { 1518 Output_section* hdr_os = 1519 this->choose_output_section(NULL, ".eh_frame_hdr", 1520 elfcpp::SHT_PROGBITS, 1521 elfcpp::SHF_ALLOC, false, 1522 ORDER_EHFRAME, false); 1523 1524 if (hdr_os != NULL) 1525 { 1526 Eh_frame_hdr* hdr_posd = new Eh_frame_hdr(os, 1527 this->eh_frame_data_); 1528 hdr_os->add_output_section_data(hdr_posd); 1529 1530 hdr_os->set_after_input_sections(); 1531 1532 if (!this->script_options_->saw_phdrs_clause()) 1533 { 1534 Output_segment* hdr_oseg; 1535 hdr_oseg = this->make_output_segment(elfcpp::PT_GNU_EH_FRAME, 1536 elfcpp::PF_R); 1537 hdr_oseg->add_output_section_to_nonload(hdr_os, 1538 elfcpp::PF_R); 1539 } 1540 1541 this->eh_frame_data_->set_eh_frame_hdr(hdr_posd); 1542 } 1543 } 1544 } 1545 1546 return os; 1547 } 1548 1549 // Add an exception frame for a PLT. This is called from target code. 1550 1551 void 1552 Layout::add_eh_frame_for_plt(Output_data* plt, const unsigned char* cie_data, 1553 size_t cie_length, const unsigned char* fde_data, 1554 size_t fde_length) 1555 { 1556 if (parameters->incremental()) 1557 { 1558 // FIXME: Maybe this could work some day.... 1559 return; 1560 } 1561 Output_section* os = this->make_eh_frame_section(NULL); 1562 if (os == NULL) 1563 return; 1564 this->eh_frame_data_->add_ehframe_for_plt(plt, cie_data, cie_length, 1565 fde_data, fde_length); 1566 if (!this->added_eh_frame_data_) 1567 { 1568 os->add_output_section_data(this->eh_frame_data_); 1569 this->added_eh_frame_data_ = true; 1570 } 1571 } 1572 1573 // Scan a .debug_info or .debug_types section, and add summary 1574 // information to the .gdb_index section. 1575 1576 template<int size, bool big_endian> 1577 void 1578 Layout::add_to_gdb_index(bool is_type_unit, 1579 Sized_relobj<size, big_endian>* object, 1580 const unsigned char* symbols, 1581 off_t symbols_size, 1582 unsigned int shndx, 1583 unsigned int reloc_shndx, 1584 unsigned int reloc_type) 1585 { 1586 if (this->gdb_index_data_ == NULL) 1587 { 1588 Output_section* os = this->choose_output_section(NULL, ".gdb_index", 1589 elfcpp::SHT_PROGBITS, 0, 1590 false, ORDER_INVALID, 1591 false); 1592 if (os == NULL) 1593 return; 1594 1595 this->gdb_index_data_ = new Gdb_index(os); 1596 os->add_output_section_data(this->gdb_index_data_); 1597 os->set_after_input_sections(); 1598 } 1599 1600 this->gdb_index_data_->scan_debug_info(is_type_unit, object, symbols, 1601 symbols_size, shndx, reloc_shndx, 1602 reloc_type); 1603 } 1604 1605 // Add POSD to an output section using NAME, TYPE, and FLAGS. Return 1606 // the output section. 1607 1608 Output_section* 1609 Layout::add_output_section_data(const char* name, elfcpp::Elf_Word type, 1610 elfcpp::Elf_Xword flags, 1611 Output_section_data* posd, 1612 Output_section_order order, bool is_relro) 1613 { 1614 Output_section* os = this->choose_output_section(NULL, name, type, flags, 1615 false, order, is_relro); 1616 if (os != NULL) 1617 os->add_output_section_data(posd); 1618 return os; 1619 } 1620 1621 // Map section flags to segment flags. 1622 1623 elfcpp::Elf_Word 1624 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags) 1625 { 1626 elfcpp::Elf_Word ret = elfcpp::PF_R; 1627 if ((flags & elfcpp::SHF_WRITE) != 0) 1628 ret |= elfcpp::PF_W; 1629 if ((flags & elfcpp::SHF_EXECINSTR) != 0) 1630 ret |= elfcpp::PF_X; 1631 return ret; 1632 } 1633 1634 // Make a new Output_section, and attach it to segments as 1635 // appropriate. ORDER is the order in which this section should 1636 // appear in the output segment. IS_RELRO is true if this is a relro 1637 // (read-only after relocations) section. 1638 1639 Output_section* 1640 Layout::make_output_section(const char* name, elfcpp::Elf_Word type, 1641 elfcpp::Elf_Xword flags, 1642 Output_section_order order, bool is_relro) 1643 { 1644 Output_section* os; 1645 if ((flags & elfcpp::SHF_ALLOC) == 0 1646 && strcmp(parameters->options().compress_debug_sections(), "none") != 0 1647 && is_compressible_debug_section(name)) 1648 os = new Output_compressed_section(¶meters->options(), name, type, 1649 flags); 1650 else if ((flags & elfcpp::SHF_ALLOC) == 0 1651 && parameters->options().strip_debug_non_line() 1652 && strcmp(".debug_abbrev", name) == 0) 1653 { 1654 os = this->debug_abbrev_ = new Output_reduced_debug_abbrev_section( 1655 name, type, flags); 1656 if (this->debug_info_) 1657 this->debug_info_->set_abbreviations(this->debug_abbrev_); 1658 } 1659 else if ((flags & elfcpp::SHF_ALLOC) == 0 1660 && parameters->options().strip_debug_non_line() 1661 && strcmp(".debug_info", name) == 0) 1662 { 1663 os = this->debug_info_ = new Output_reduced_debug_info_section( 1664 name, type, flags); 1665 if (this->debug_abbrev_) 1666 this->debug_info_->set_abbreviations(this->debug_abbrev_); 1667 } 1668 else 1669 { 1670 // Sometimes .init_array*, .preinit_array* and .fini_array* do 1671 // not have correct section types. Force them here. 1672 if (type == elfcpp::SHT_PROGBITS) 1673 { 1674 if (is_prefix_of(".init_array", name)) 1675 type = elfcpp::SHT_INIT_ARRAY; 1676 else if (is_prefix_of(".preinit_array", name)) 1677 type = elfcpp::SHT_PREINIT_ARRAY; 1678 else if (is_prefix_of(".fini_array", name)) 1679 type = elfcpp::SHT_FINI_ARRAY; 1680 } 1681 1682 // FIXME: const_cast is ugly. 1683 Target* target = const_cast<Target*>(¶meters->target()); 1684 os = target->make_output_section(name, type, flags); 1685 } 1686 1687 // With -z relro, we have to recognize the special sections by name. 1688 // There is no other way. 1689 bool is_relro_local = false; 1690 if (!this->script_options_->saw_sections_clause() 1691 && parameters->options().relro() 1692 && (flags & elfcpp::SHF_ALLOC) != 0 1693 && (flags & elfcpp::SHF_WRITE) != 0) 1694 { 1695 if (type == elfcpp::SHT_PROGBITS) 1696 { 1697 if ((flags & elfcpp::SHF_TLS) != 0) 1698 is_relro = true; 1699 else if (strcmp(name, ".data.rel.ro") == 0) 1700 is_relro = true; 1701 else if (strcmp(name, ".data.rel.ro.local") == 0) 1702 { 1703 is_relro = true; 1704 is_relro_local = true; 1705 } 1706 else if (strcmp(name, ".ctors") == 0 1707 || strcmp(name, ".dtors") == 0 1708 || strcmp(name, ".jcr") == 0) 1709 is_relro = true; 1710 } 1711 else if (type == elfcpp::SHT_INIT_ARRAY 1712 || type == elfcpp::SHT_FINI_ARRAY 1713 || type == elfcpp::SHT_PREINIT_ARRAY) 1714 is_relro = true; 1715 } 1716 1717 if (is_relro) 1718 os->set_is_relro(); 1719 1720 if (order == ORDER_INVALID && (flags & elfcpp::SHF_ALLOC) != 0) 1721 order = this->default_section_order(os, is_relro_local); 1722 1723 os->set_order(order); 1724 1725 parameters->target().new_output_section(os); 1726 1727 this->section_list_.push_back(os); 1728 1729 // The GNU linker by default sorts some sections by priority, so we 1730 // do the same. We need to know that this might happen before we 1731 // attach any input sections. 1732 if (!this->script_options_->saw_sections_clause() 1733 && !parameters->options().relocatable() 1734 && (strcmp(name, ".init_array") == 0 1735 || strcmp(name, ".fini_array") == 0 1736 || (!parameters->options().ctors_in_init_array() 1737 && (strcmp(name, ".ctors") == 0 1738 || strcmp(name, ".dtors") == 0)))) 1739 os->set_may_sort_attached_input_sections(); 1740 1741 // The GNU linker by default sorts .text.{unlikely,exit,startup,hot} 1742 // sections before other .text sections. We are compatible. We 1743 // need to know that this might happen before we attach any input 1744 // sections. 1745 if (parameters->options().text_reorder() 1746 && !this->script_options_->saw_sections_clause() 1747 && !this->is_section_ordering_specified() 1748 && !parameters->options().relocatable() 1749 && strcmp(name, ".text") == 0) 1750 os->set_may_sort_attached_input_sections(); 1751 1752 // GNU linker sorts section by name with --sort-section=name. 1753 if (strcmp(parameters->options().sort_section(), "name") == 0) 1754 os->set_must_sort_attached_input_sections(); 1755 1756 // Check for .stab*str sections, as .stab* sections need to link to 1757 // them. 1758 if (type == elfcpp::SHT_STRTAB 1759 && !this->have_stabstr_section_ 1760 && strncmp(name, ".stab", 5) == 0 1761 && strcmp(name + strlen(name) - 3, "str") == 0) 1762 this->have_stabstr_section_ = true; 1763 1764 // During a full incremental link, we add patch space to most 1765 // PROGBITS and NOBITS sections. Flag those that may be 1766 // arbitrarily padded. 1767 if ((type == elfcpp::SHT_PROGBITS || type == elfcpp::SHT_NOBITS) 1768 && order != ORDER_INTERP 1769 && order != ORDER_INIT 1770 && order != ORDER_PLT 1771 && order != ORDER_FINI 1772 && order != ORDER_RELRO_LAST 1773 && order != ORDER_NON_RELRO_FIRST 1774 && strcmp(name, ".eh_frame") != 0 1775 && strcmp(name, ".ctors") != 0 1776 && strcmp(name, ".dtors") != 0 1777 && strcmp(name, ".jcr") != 0) 1778 { 1779 os->set_is_patch_space_allowed(); 1780 1781 // Certain sections require "holes" to be filled with 1782 // specific fill patterns. These fill patterns may have 1783 // a minimum size, so we must prevent allocations from the 1784 // free list that leave a hole smaller than the minimum. 1785 if (strcmp(name, ".debug_info") == 0) 1786 os->set_free_space_fill(new Output_fill_debug_info(false)); 1787 else if (strcmp(name, ".debug_types") == 0) 1788 os->set_free_space_fill(new Output_fill_debug_info(true)); 1789 else if (strcmp(name, ".debug_line") == 0) 1790 os->set_free_space_fill(new Output_fill_debug_line()); 1791 } 1792 1793 // If we have already attached the sections to segments, then we 1794 // need to attach this one now. This happens for sections created 1795 // directly by the linker. 1796 if (this->sections_are_attached_) 1797 this->attach_section_to_segment(¶meters->target(), os); 1798 1799 return os; 1800 } 1801 1802 // Return the default order in which a section should be placed in an 1803 // output segment. This function captures a lot of the ideas in 1804 // ld/scripttempl/elf.sc in the GNU linker. Note that the order of a 1805 // linker created section is normally set when the section is created; 1806 // this function is used for input sections. 1807 1808 Output_section_order 1809 Layout::default_section_order(Output_section* os, bool is_relro_local) 1810 { 1811 gold_assert((os->flags() & elfcpp::SHF_ALLOC) != 0); 1812 bool is_write = (os->flags() & elfcpp::SHF_WRITE) != 0; 1813 bool is_execinstr = (os->flags() & elfcpp::SHF_EXECINSTR) != 0; 1814 bool is_bss = false; 1815 1816 switch (os->type()) 1817 { 1818 default: 1819 case elfcpp::SHT_PROGBITS: 1820 break; 1821 case elfcpp::SHT_NOBITS: 1822 is_bss = true; 1823 break; 1824 case elfcpp::SHT_RELA: 1825 case elfcpp::SHT_REL: 1826 if (!is_write) 1827 return ORDER_DYNAMIC_RELOCS; 1828 break; 1829 case elfcpp::SHT_HASH: 1830 case elfcpp::SHT_DYNAMIC: 1831 case elfcpp::SHT_SHLIB: 1832 case elfcpp::SHT_DYNSYM: 1833 case elfcpp::SHT_GNU_HASH: 1834 case elfcpp::SHT_GNU_verdef: 1835 case elfcpp::SHT_GNU_verneed: 1836 case elfcpp::SHT_GNU_versym: 1837 if (!is_write) 1838 return ORDER_DYNAMIC_LINKER; 1839 break; 1840 case elfcpp::SHT_NOTE: 1841 return is_write ? ORDER_RW_NOTE : ORDER_RO_NOTE; 1842 } 1843 1844 if ((os->flags() & elfcpp::SHF_TLS) != 0) 1845 return is_bss ? ORDER_TLS_BSS : ORDER_TLS_DATA; 1846 1847 if (!is_bss && !is_write) 1848 { 1849 if (is_execinstr) 1850 { 1851 if (strcmp(os->name(), ".init") == 0) 1852 return ORDER_INIT; 1853 else if (strcmp(os->name(), ".fini") == 0) 1854 return ORDER_FINI; 1855 } 1856 return is_execinstr ? ORDER_TEXT : ORDER_READONLY; 1857 } 1858 1859 if (os->is_relro()) 1860 return is_relro_local ? ORDER_RELRO_LOCAL : ORDER_RELRO; 1861 1862 if (os->is_small_section()) 1863 return is_bss ? ORDER_SMALL_BSS : ORDER_SMALL_DATA; 1864 if (os->is_large_section()) 1865 return is_bss ? ORDER_LARGE_BSS : ORDER_LARGE_DATA; 1866 1867 return is_bss ? ORDER_BSS : ORDER_DATA; 1868 } 1869 1870 // Attach output sections to segments. This is called after we have 1871 // seen all the input sections. 1872 1873 void 1874 Layout::attach_sections_to_segments(const Target* target) 1875 { 1876 for (Section_list::iterator p = this->section_list_.begin(); 1877 p != this->section_list_.end(); 1878 ++p) 1879 this->attach_section_to_segment(target, *p); 1880 1881 this->sections_are_attached_ = true; 1882 } 1883 1884 // Attach an output section to a segment. 1885 1886 void 1887 Layout::attach_section_to_segment(const Target* target, Output_section* os) 1888 { 1889 if ((os->flags() & elfcpp::SHF_ALLOC) == 0) 1890 this->unattached_section_list_.push_back(os); 1891 else 1892 this->attach_allocated_section_to_segment(target, os); 1893 } 1894 1895 // Attach an allocated output section to a segment. 1896 1897 void 1898 Layout::attach_allocated_section_to_segment(const Target* target, 1899 Output_section* os) 1900 { 1901 elfcpp::Elf_Xword flags = os->flags(); 1902 gold_assert((flags & elfcpp::SHF_ALLOC) != 0); 1903 1904 if (parameters->options().relocatable()) 1905 return; 1906 1907 // If we have a SECTIONS clause, we can't handle the attachment to 1908 // segments until after we've seen all the sections. 1909 if (this->script_options_->saw_sections_clause()) 1910 return; 1911 1912 gold_assert(!this->script_options_->saw_phdrs_clause()); 1913 1914 // This output section goes into a PT_LOAD segment. 1915 1916 elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags); 1917 1918 // If this output section's segment has extra flags that need to be set, 1919 // coming from a linker plugin, do that. 1920 seg_flags |= os->extra_segment_flags(); 1921 1922 // Check for --section-start. 1923 uint64_t addr; 1924 bool is_address_set = parameters->options().section_start(os->name(), &addr); 1925 1926 // In general the only thing we really care about for PT_LOAD 1927 // segments is whether or not they are writable or executable, 1928 // so that is how we search for them. 1929 // Large data sections also go into their own PT_LOAD segment. 1930 // People who need segments sorted on some other basis will 1931 // have to use a linker script. 1932 1933 Segment_list::const_iterator p; 1934 if (!os->is_unique_segment()) 1935 { 1936 for (p = this->segment_list_.begin(); 1937 p != this->segment_list_.end(); 1938 ++p) 1939 { 1940 if ((*p)->type() != elfcpp::PT_LOAD) 1941 continue; 1942 if ((*p)->is_unique_segment()) 1943 continue; 1944 if (!parameters->options().omagic() 1945 && ((*p)->flags() & elfcpp::PF_W) != (seg_flags & elfcpp::PF_W)) 1946 continue; 1947 if ((target->isolate_execinstr() || parameters->options().rosegment()) 1948 && ((*p)->flags() & elfcpp::PF_X) != (seg_flags & elfcpp::PF_X)) 1949 continue; 1950 // If -Tbss was specified, we need to separate the data and BSS 1951 // segments. 1952 if (parameters->options().user_set_Tbss()) 1953 { 1954 if ((os->type() == elfcpp::SHT_NOBITS) 1955 == (*p)->has_any_data_sections()) 1956 continue; 1957 } 1958 if (os->is_large_data_section() && !(*p)->is_large_data_segment()) 1959 continue; 1960 1961 if (is_address_set) 1962 { 1963 if ((*p)->are_addresses_set()) 1964 continue; 1965 1966 (*p)->add_initial_output_data(os); 1967 (*p)->update_flags_for_output_section(seg_flags); 1968 (*p)->set_addresses(addr, addr); 1969 break; 1970 } 1971 1972 (*p)->add_output_section_to_load(this, os, seg_flags); 1973 break; 1974 } 1975 } 1976 1977 if (p == this->segment_list_.end() 1978 || os->is_unique_segment()) 1979 { 1980 Output_segment* oseg = this->make_output_segment(elfcpp::PT_LOAD, 1981 seg_flags); 1982 if (os->is_large_data_section()) 1983 oseg->set_is_large_data_segment(); 1984 oseg->add_output_section_to_load(this, os, seg_flags); 1985 if (is_address_set) 1986 oseg->set_addresses(addr, addr); 1987 // Check if segment should be marked unique. For segments marked 1988 // unique by linker plugins, set the new alignment if specified. 1989 if (os->is_unique_segment()) 1990 { 1991 oseg->set_is_unique_segment(); 1992 if (os->segment_alignment() != 0) 1993 oseg->set_minimum_p_align(os->segment_alignment()); 1994 } 1995 } 1996 1997 // If we see a loadable SHT_NOTE section, we create a PT_NOTE 1998 // segment. 1999 if (os->type() == elfcpp::SHT_NOTE) 2000 { 2001 // See if we already have an equivalent PT_NOTE segment. 2002 for (p = this->segment_list_.begin(); 2003 p != segment_list_.end(); 2004 ++p) 2005 { 2006 if ((*p)->type() == elfcpp::PT_NOTE 2007 && (((*p)->flags() & elfcpp::PF_W) 2008 == (seg_flags & elfcpp::PF_W))) 2009 { 2010 (*p)->add_output_section_to_nonload(os, seg_flags); 2011 break; 2012 } 2013 } 2014 2015 if (p == this->segment_list_.end()) 2016 { 2017 Output_segment* oseg = this->make_output_segment(elfcpp::PT_NOTE, 2018 seg_flags); 2019 oseg->add_output_section_to_nonload(os, seg_flags); 2020 } 2021 } 2022 2023 // If we see a loadable SHF_TLS section, we create a PT_TLS 2024 // segment. There can only be one such segment. 2025 if ((flags & elfcpp::SHF_TLS) != 0) 2026 { 2027 if (this->tls_segment_ == NULL) 2028 this->make_output_segment(elfcpp::PT_TLS, seg_flags); 2029 this->tls_segment_->add_output_section_to_nonload(os, seg_flags); 2030 } 2031 2032 // If -z relro is in effect, and we see a relro section, we create a 2033 // PT_GNU_RELRO segment. There can only be one such segment. 2034 if (os->is_relro() && parameters->options().relro()) 2035 { 2036 gold_assert(seg_flags == (elfcpp::PF_R | elfcpp::PF_W)); 2037 if (this->relro_segment_ == NULL) 2038 this->make_output_segment(elfcpp::PT_GNU_RELRO, seg_flags); 2039 this->relro_segment_->add_output_section_to_nonload(os, seg_flags); 2040 } 2041 2042 // If we see a section named .interp, put it into a PT_INTERP 2043 // segment. This seems broken to me, but this is what GNU ld does, 2044 // and glibc expects it. 2045 if (strcmp(os->name(), ".interp") == 0 2046 && !this->script_options_->saw_phdrs_clause()) 2047 { 2048 if (this->interp_segment_ == NULL) 2049 this->make_output_segment(elfcpp::PT_INTERP, seg_flags); 2050 else 2051 gold_warning(_("multiple '.interp' sections in input files " 2052 "may cause confusing PT_INTERP segment")); 2053 this->interp_segment_->add_output_section_to_nonload(os, seg_flags); 2054 } 2055 } 2056 2057 // Make an output section for a script. 2058 2059 Output_section* 2060 Layout::make_output_section_for_script( 2061 const char* name, 2062 Script_sections::Section_type section_type) 2063 { 2064 name = this->namepool_.add(name, false, NULL); 2065 elfcpp::Elf_Xword sh_flags = elfcpp::SHF_ALLOC; 2066 if (section_type == Script_sections::ST_NOLOAD) 2067 sh_flags = 0; 2068 Output_section* os = this->make_output_section(name, elfcpp::SHT_PROGBITS, 2069 sh_flags, ORDER_INVALID, 2070 false); 2071 os->set_found_in_sections_clause(); 2072 if (section_type == Script_sections::ST_NOLOAD) 2073 os->set_is_noload(); 2074 return os; 2075 } 2076 2077 // Return the number of segments we expect to see. 2078 2079 size_t 2080 Layout::expected_segment_count() const 2081 { 2082 size_t ret = this->segment_list_.size(); 2083 2084 // If we didn't see a SECTIONS clause in a linker script, we should 2085 // already have the complete list of segments. Otherwise we ask the 2086 // SECTIONS clause how many segments it expects, and add in the ones 2087 // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.) 2088 2089 if (!this->script_options_->saw_sections_clause()) 2090 return ret; 2091 else 2092 { 2093 const Script_sections* ss = this->script_options_->script_sections(); 2094 return ret + ss->expected_segment_count(this); 2095 } 2096 } 2097 2098 // Handle the .note.GNU-stack section at layout time. SEEN_GNU_STACK 2099 // is whether we saw a .note.GNU-stack section in the object file. 2100 // GNU_STACK_FLAGS is the section flags. The flags give the 2101 // protection required for stack memory. We record this in an 2102 // executable as a PT_GNU_STACK segment. If an object file does not 2103 // have a .note.GNU-stack segment, we must assume that it is an old 2104 // object. On some targets that will force an executable stack. 2105 2106 void 2107 Layout::layout_gnu_stack(bool seen_gnu_stack, uint64_t gnu_stack_flags, 2108 const Object* obj) 2109 { 2110 if (!seen_gnu_stack) 2111 { 2112 this->input_without_gnu_stack_note_ = true; 2113 if (parameters->options().warn_execstack() 2114 && parameters->target().is_default_stack_executable()) 2115 gold_warning(_("%s: missing .note.GNU-stack section" 2116 " implies executable stack"), 2117 obj->name().c_str()); 2118 } 2119 else 2120 { 2121 this->input_with_gnu_stack_note_ = true; 2122 if ((gnu_stack_flags & elfcpp::SHF_EXECINSTR) != 0) 2123 { 2124 this->input_requires_executable_stack_ = true; 2125 if (parameters->options().warn_execstack()) 2126 gold_warning(_("%s: requires executable stack"), 2127 obj->name().c_str()); 2128 } 2129 } 2130 } 2131 2132 // Create automatic note sections. 2133 2134 void 2135 Layout::create_notes() 2136 { 2137 this->create_gold_note(); 2138 this->create_stack_segment(); 2139 this->create_build_id(); 2140 } 2141 2142 // Create the dynamic sections which are needed before we read the 2143 // relocs. 2144 2145 void 2146 Layout::create_initial_dynamic_sections(Symbol_table* symtab) 2147 { 2148 if (parameters->doing_static_link()) 2149 return; 2150 2151 this->dynamic_section_ = this->choose_output_section(NULL, ".dynamic", 2152 elfcpp::SHT_DYNAMIC, 2153 (elfcpp::SHF_ALLOC 2154 | elfcpp::SHF_WRITE), 2155 false, ORDER_RELRO, 2156 true); 2157 2158 // A linker script may discard .dynamic, so check for NULL. 2159 if (this->dynamic_section_ != NULL) 2160 { 2161 this->dynamic_symbol_ = 2162 symtab->define_in_output_data("_DYNAMIC", NULL, 2163 Symbol_table::PREDEFINED, 2164 this->dynamic_section_, 0, 0, 2165 elfcpp::STT_OBJECT, elfcpp::STB_LOCAL, 2166 elfcpp::STV_HIDDEN, 0, false, false); 2167 2168 this->dynamic_data_ = new Output_data_dynamic(&this->dynpool_); 2169 2170 this->dynamic_section_->add_output_section_data(this->dynamic_data_); 2171 } 2172 } 2173 2174 // For each output section whose name can be represented as C symbol, 2175 // define __start and __stop symbols for the section. This is a GNU 2176 // extension. 2177 2178 void 2179 Layout::define_section_symbols(Symbol_table* symtab) 2180 { 2181 for (Section_list::const_iterator p = this->section_list_.begin(); 2182 p != this->section_list_.end(); 2183 ++p) 2184 { 2185 const char* const name = (*p)->name(); 2186 if (is_cident(name)) 2187 { 2188 const std::string name_string(name); 2189 const std::string start_name(cident_section_start_prefix 2190 + name_string); 2191 const std::string stop_name(cident_section_stop_prefix 2192 + name_string); 2193 2194 symtab->define_in_output_data(start_name.c_str(), 2195 NULL, // version 2196 Symbol_table::PREDEFINED, 2197 *p, 2198 0, // value 2199 0, // symsize 2200 elfcpp::STT_NOTYPE, 2201 elfcpp::STB_GLOBAL, 2202 elfcpp::STV_DEFAULT, 2203 0, // nonvis 2204 false, // offset_is_from_end 2205 true); // only_if_ref 2206 2207 symtab->define_in_output_data(stop_name.c_str(), 2208 NULL, // version 2209 Symbol_table::PREDEFINED, 2210 *p, 2211 0, // value 2212 0, // symsize 2213 elfcpp::STT_NOTYPE, 2214 elfcpp::STB_GLOBAL, 2215 elfcpp::STV_DEFAULT, 2216 0, // nonvis 2217 true, // offset_is_from_end 2218 true); // only_if_ref 2219 } 2220 } 2221 } 2222 2223 // Define symbols for group signatures. 2224 2225 void 2226 Layout::define_group_signatures(Symbol_table* symtab) 2227 { 2228 for (Group_signatures::iterator p = this->group_signatures_.begin(); 2229 p != this->group_signatures_.end(); 2230 ++p) 2231 { 2232 Symbol* sym = symtab->lookup(p->signature, NULL); 2233 if (sym != NULL) 2234 p->section->set_info_symndx(sym); 2235 else 2236 { 2237 // Force the name of the group section to the group 2238 // signature, and use the group's section symbol as the 2239 // signature symbol. 2240 if (strcmp(p->section->name(), p->signature) != 0) 2241 { 2242 const char* name = this->namepool_.add(p->signature, 2243 true, NULL); 2244 p->section->set_name(name); 2245 } 2246 p->section->set_needs_symtab_index(); 2247 p->section->set_info_section_symndx(p->section); 2248 } 2249 } 2250 2251 this->group_signatures_.clear(); 2252 } 2253 2254 // Find the first read-only PT_LOAD segment, creating one if 2255 // necessary. 2256 2257 Output_segment* 2258 Layout::find_first_load_seg(const Target* target) 2259 { 2260 Output_segment* best = NULL; 2261 for (Segment_list::const_iterator p = this->segment_list_.begin(); 2262 p != this->segment_list_.end(); 2263 ++p) 2264 { 2265 if ((*p)->type() == elfcpp::PT_LOAD 2266 && ((*p)->flags() & elfcpp::PF_R) != 0 2267 && (parameters->options().omagic() 2268 || ((*p)->flags() & elfcpp::PF_W) == 0) 2269 && (!target->isolate_execinstr() 2270 || ((*p)->flags() & elfcpp::PF_X) == 0)) 2271 { 2272 if (best == NULL || this->segment_precedes(*p, best)) 2273 best = *p; 2274 } 2275 } 2276 if (best != NULL) 2277 return best; 2278 2279 gold_assert(!this->script_options_->saw_phdrs_clause()); 2280 2281 Output_segment* load_seg = this->make_output_segment(elfcpp::PT_LOAD, 2282 elfcpp::PF_R); 2283 return load_seg; 2284 } 2285 2286 // Save states of all current output segments. Store saved states 2287 // in SEGMENT_STATES. 2288 2289 void 2290 Layout::save_segments(Segment_states* segment_states) 2291 { 2292 for (Segment_list::const_iterator p = this->segment_list_.begin(); 2293 p != this->segment_list_.end(); 2294 ++p) 2295 { 2296 Output_segment* segment = *p; 2297 // Shallow copy. 2298 Output_segment* copy = new Output_segment(*segment); 2299 (*segment_states)[segment] = copy; 2300 } 2301 } 2302 2303 // Restore states of output segments and delete any segment not found in 2304 // SEGMENT_STATES. 2305 2306 void 2307 Layout::restore_segments(const Segment_states* segment_states) 2308 { 2309 // Go through the segment list and remove any segment added in the 2310 // relaxation loop. 2311 this->tls_segment_ = NULL; 2312 this->relro_segment_ = NULL; 2313 Segment_list::iterator list_iter = this->segment_list_.begin(); 2314 while (list_iter != this->segment_list_.end()) 2315 { 2316 Output_segment* segment = *list_iter; 2317 Segment_states::const_iterator states_iter = 2318 segment_states->find(segment); 2319 if (states_iter != segment_states->end()) 2320 { 2321 const Output_segment* copy = states_iter->second; 2322 // Shallow copy to restore states. 2323 *segment = *copy; 2324 2325 // Also fix up TLS and RELRO segment pointers as appropriate. 2326 if (segment->type() == elfcpp::PT_TLS) 2327 this->tls_segment_ = segment; 2328 else if (segment->type() == elfcpp::PT_GNU_RELRO) 2329 this->relro_segment_ = segment; 2330 2331 ++list_iter; 2332 } 2333 else 2334 { 2335 list_iter = this->segment_list_.erase(list_iter); 2336 // This is a segment created during section layout. It should be 2337 // safe to remove it since we should have removed all pointers to it. 2338 delete segment; 2339 } 2340 } 2341 } 2342 2343 // Clean up after relaxation so that sections can be laid out again. 2344 2345 void 2346 Layout::clean_up_after_relaxation() 2347 { 2348 // Restore the segments to point state just prior to the relaxation loop. 2349 Script_sections* script_section = this->script_options_->script_sections(); 2350 script_section->release_segments(); 2351 this->restore_segments(this->segment_states_); 2352 2353 // Reset section addresses and file offsets 2354 for (Section_list::iterator p = this->section_list_.begin(); 2355 p != this->section_list_.end(); 2356 ++p) 2357 { 2358 (*p)->restore_states(); 2359 2360 // If an input section changes size because of relaxation, 2361 // we need to adjust the section offsets of all input sections. 2362 // after such a section. 2363 if ((*p)->section_offsets_need_adjustment()) 2364 (*p)->adjust_section_offsets(); 2365 2366 (*p)->reset_address_and_file_offset(); 2367 } 2368 2369 // Reset special output object address and file offsets. 2370 for (Data_list::iterator p = this->special_output_list_.begin(); 2371 p != this->special_output_list_.end(); 2372 ++p) 2373 (*p)->reset_address_and_file_offset(); 2374 2375 // A linker script may have created some output section data objects. 2376 // They are useless now. 2377 for (Output_section_data_list::const_iterator p = 2378 this->script_output_section_data_list_.begin(); 2379 p != this->script_output_section_data_list_.end(); 2380 ++p) 2381 delete *p; 2382 this->script_output_section_data_list_.clear(); 2383 2384 // Special-case fill output objects are recreated each time through 2385 // the relaxation loop. 2386 this->reset_relax_output(); 2387 } 2388 2389 void 2390 Layout::reset_relax_output() 2391 { 2392 for (Data_list::const_iterator p = this->relax_output_list_.begin(); 2393 p != this->relax_output_list_.end(); 2394 ++p) 2395 delete *p; 2396 this->relax_output_list_.clear(); 2397 } 2398 2399 // Prepare for relaxation. 2400 2401 void 2402 Layout::prepare_for_relaxation() 2403 { 2404 // Create an relaxation debug check if in debugging mode. 2405 if (is_debugging_enabled(DEBUG_RELAXATION)) 2406 this->relaxation_debug_check_ = new Relaxation_debug_check(); 2407 2408 // Save segment states. 2409 this->segment_states_ = new Segment_states(); 2410 this->save_segments(this->segment_states_); 2411 2412 for(Section_list::const_iterator p = this->section_list_.begin(); 2413 p != this->section_list_.end(); 2414 ++p) 2415 (*p)->save_states(); 2416 2417 if (is_debugging_enabled(DEBUG_RELAXATION)) 2418 this->relaxation_debug_check_->check_output_data_for_reset_values( 2419 this->section_list_, this->special_output_list_, 2420 this->relax_output_list_); 2421 2422 // Also enable recording of output section data from scripts. 2423 this->record_output_section_data_from_script_ = true; 2424 } 2425 2426 // If the user set the address of the text segment, that may not be 2427 // compatible with putting the segment headers and file headers into 2428 // that segment. For isolate_execinstr() targets, it's the rodata 2429 // segment rather than text where we might put the headers. 2430 static inline bool 2431 load_seg_unusable_for_headers(const Target* target) 2432 { 2433 const General_options& options = parameters->options(); 2434 if (target->isolate_execinstr()) 2435 return (options.user_set_Trodata_segment() 2436 && options.Trodata_segment() % target->abi_pagesize() != 0); 2437 else 2438 return (options.user_set_Ttext() 2439 && options.Ttext() % target->abi_pagesize() != 0); 2440 } 2441 2442 // Relaxation loop body: If target has no relaxation, this runs only once 2443 // Otherwise, the target relaxation hook is called at the end of 2444 // each iteration. If the hook returns true, it means re-layout of 2445 // section is required. 2446 // 2447 // The number of segments created by a linking script without a PHDRS 2448 // clause may be affected by section sizes and alignments. There is 2449 // a remote chance that relaxation causes different number of PT_LOAD 2450 // segments are created and sections are attached to different segments. 2451 // Therefore, we always throw away all segments created during section 2452 // layout. In order to be able to restart the section layout, we keep 2453 // a copy of the segment list right before the relaxation loop and use 2454 // that to restore the segments. 2455 // 2456 // PASS is the current relaxation pass number. 2457 // SYMTAB is a symbol table. 2458 // PLOAD_SEG is the address of a pointer for the load segment. 2459 // PHDR_SEG is a pointer to the PHDR segment. 2460 // SEGMENT_HEADERS points to the output segment header. 2461 // FILE_HEADER points to the output file header. 2462 // PSHNDX is the address to store the output section index. 2463 2464 off_t inline 2465 Layout::relaxation_loop_body( 2466 int pass, 2467 Target* target, 2468 Symbol_table* symtab, 2469 Output_segment** pload_seg, 2470 Output_segment* phdr_seg, 2471 Output_segment_headers* segment_headers, 2472 Output_file_header* file_header, 2473 unsigned int* pshndx) 2474 { 2475 // If this is not the first iteration, we need to clean up after 2476 // relaxation so that we can lay out the sections again. 2477 if (pass != 0) 2478 this->clean_up_after_relaxation(); 2479 2480 // If there is a SECTIONS clause, put all the input sections into 2481 // the required order. 2482 Output_segment* load_seg; 2483 if (this->script_options_->saw_sections_clause()) 2484 load_seg = this->set_section_addresses_from_script(symtab); 2485 else if (parameters->options().relocatable()) 2486 load_seg = NULL; 2487 else 2488 load_seg = this->find_first_load_seg(target); 2489 2490 if (parameters->options().oformat_enum() 2491 != General_options::OBJECT_FORMAT_ELF) 2492 load_seg = NULL; 2493 2494 if (load_seg_unusable_for_headers(target)) 2495 { 2496 load_seg = NULL; 2497 phdr_seg = NULL; 2498 } 2499 2500 gold_assert(phdr_seg == NULL 2501 || load_seg != NULL 2502 || this->script_options_->saw_sections_clause()); 2503 2504 // If the address of the load segment we found has been set by 2505 // --section-start rather than by a script, then adjust the VMA and 2506 // LMA downward if possible to include the file and section headers. 2507 uint64_t header_gap = 0; 2508 if (load_seg != NULL 2509 && load_seg->are_addresses_set() 2510 && !this->script_options_->saw_sections_clause() 2511 && !parameters->options().relocatable()) 2512 { 2513 file_header->finalize_data_size(); 2514 segment_headers->finalize_data_size(); 2515 size_t sizeof_headers = (file_header->data_size() 2516 + segment_headers->data_size()); 2517 const uint64_t abi_pagesize = target->abi_pagesize(); 2518 uint64_t hdr_paddr = load_seg->paddr() - sizeof_headers; 2519 hdr_paddr &= ~(abi_pagesize - 1); 2520 uint64_t subtract = load_seg->paddr() - hdr_paddr; 2521 if (load_seg->paddr() < subtract || load_seg->vaddr() < subtract) 2522 load_seg = NULL; 2523 else 2524 { 2525 load_seg->set_addresses(load_seg->vaddr() - subtract, 2526 load_seg->paddr() - subtract); 2527 header_gap = subtract - sizeof_headers; 2528 } 2529 } 2530 2531 // Lay out the segment headers. 2532 if (!parameters->options().relocatable()) 2533 { 2534 gold_assert(segment_headers != NULL); 2535 if (header_gap != 0 && load_seg != NULL) 2536 { 2537 Output_data_zero_fill* z = new Output_data_zero_fill(header_gap, 1); 2538 load_seg->add_initial_output_data(z); 2539 } 2540 if (load_seg != NULL) 2541 load_seg->add_initial_output_data(segment_headers); 2542 if (phdr_seg != NULL) 2543 phdr_seg->add_initial_output_data(segment_headers); 2544 } 2545 2546 // Lay out the file header. 2547 if (load_seg != NULL) 2548 load_seg->add_initial_output_data(file_header); 2549 2550 if (this->script_options_->saw_phdrs_clause() 2551 && !parameters->options().relocatable()) 2552 { 2553 // Support use of FILEHDRS and PHDRS attachments in a PHDRS 2554 // clause in a linker script. 2555 Script_sections* ss = this->script_options_->script_sections(); 2556 ss->put_headers_in_phdrs(file_header, segment_headers); 2557 } 2558 2559 // We set the output section indexes in set_segment_offsets and 2560 // set_section_indexes. 2561 *pshndx = 1; 2562 2563 // Set the file offsets of all the segments, and all the sections 2564 // they contain. 2565 off_t off; 2566 if (!parameters->options().relocatable()) 2567 off = this->set_segment_offsets(target, load_seg, pshndx); 2568 else 2569 off = this->set_relocatable_section_offsets(file_header, pshndx); 2570 2571 // Verify that the dummy relaxation does not change anything. 2572 if (is_debugging_enabled(DEBUG_RELAXATION)) 2573 { 2574 if (pass == 0) 2575 this->relaxation_debug_check_->read_sections(this->section_list_); 2576 else 2577 this->relaxation_debug_check_->verify_sections(this->section_list_); 2578 } 2579 2580 *pload_seg = load_seg; 2581 return off; 2582 } 2583 2584 // Search the list of patterns and find the postion of the given section 2585 // name in the output section. If the section name matches a glob 2586 // pattern and a non-glob name, then the non-glob position takes 2587 // precedence. Return 0 if no match is found. 2588 2589 unsigned int 2590 Layout::find_section_order_index(const std::string& section_name) 2591 { 2592 Unordered_map<std::string, unsigned int>::iterator map_it; 2593 map_it = this->input_section_position_.find(section_name); 2594 if (map_it != this->input_section_position_.end()) 2595 return map_it->second; 2596 2597 // Absolute match failed. Linear search the glob patterns. 2598 std::vector<std::string>::iterator it; 2599 for (it = this->input_section_glob_.begin(); 2600 it != this->input_section_glob_.end(); 2601 ++it) 2602 { 2603 if (fnmatch((*it).c_str(), section_name.c_str(), FNM_NOESCAPE) == 0) 2604 { 2605 map_it = this->input_section_position_.find(*it); 2606 gold_assert(map_it != this->input_section_position_.end()); 2607 return map_it->second; 2608 } 2609 } 2610 return 0; 2611 } 2612 2613 // Read the sequence of input sections from the file specified with 2614 // option --section-ordering-file. 2615 2616 void 2617 Layout::read_layout_from_file() 2618 { 2619 const char* filename = parameters->options().section_ordering_file(); 2620 std::ifstream in; 2621 std::string line; 2622 2623 in.open(filename); 2624 if (!in) 2625 gold_fatal(_("unable to open --section-ordering-file file %s: %s"), 2626 filename, strerror(errno)); 2627 2628 std::getline(in, line); // this chops off the trailing \n, if any 2629 unsigned int position = 1; 2630 this->set_section_ordering_specified(); 2631 2632 while (in) 2633 { 2634 if (!line.empty() && line[line.length() - 1] == '\r') // Windows 2635 line.resize(line.length() - 1); 2636 // Ignore comments, beginning with '#' 2637 if (line[0] == '#') 2638 { 2639 std::getline(in, line); 2640 continue; 2641 } 2642 this->input_section_position_[line] = position; 2643 // Store all glob patterns in a vector. 2644 if (is_wildcard_string(line.c_str())) 2645 this->input_section_glob_.push_back(line); 2646 position++; 2647 std::getline(in, line); 2648 } 2649 } 2650 2651 // Finalize the layout. When this is called, we have created all the 2652 // output sections and all the output segments which are based on 2653 // input sections. We have several things to do, and we have to do 2654 // them in the right order, so that we get the right results correctly 2655 // and efficiently. 2656 2657 // 1) Finalize the list of output segments and create the segment 2658 // table header. 2659 2660 // 2) Finalize the dynamic symbol table and associated sections. 2661 2662 // 3) Determine the final file offset of all the output segments. 2663 2664 // 4) Determine the final file offset of all the SHF_ALLOC output 2665 // sections. 2666 2667 // 5) Create the symbol table sections and the section name table 2668 // section. 2669 2670 // 6) Finalize the symbol table: set symbol values to their final 2671 // value and make a final determination of which symbols are going 2672 // into the output symbol table. 2673 2674 // 7) Create the section table header. 2675 2676 // 8) Determine the final file offset of all the output sections which 2677 // are not SHF_ALLOC, including the section table header. 2678 2679 // 9) Finalize the ELF file header. 2680 2681 // This function returns the size of the output file. 2682 2683 off_t 2684 Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab, 2685 Target* target, const Task* task) 2686 { 2687 target->finalize_sections(this, input_objects, symtab); 2688 2689 this->count_local_symbols(task, input_objects); 2690 2691 this->link_stabs_sections(); 2692 2693 Output_segment* phdr_seg = NULL; 2694 if (!parameters->options().relocatable() && !parameters->doing_static_link()) 2695 { 2696 // There was a dynamic object in the link. We need to create 2697 // some information for the dynamic linker. 2698 2699 // Create the PT_PHDR segment which will hold the program 2700 // headers. 2701 if (!this->script_options_->saw_phdrs_clause()) 2702 phdr_seg = this->make_output_segment(elfcpp::PT_PHDR, elfcpp::PF_R); 2703 2704 // Create the dynamic symbol table, including the hash table. 2705 Output_section* dynstr; 2706 std::vector<Symbol*> dynamic_symbols; 2707 unsigned int local_dynamic_count; 2708 Versions versions(*this->script_options()->version_script_info(), 2709 &this->dynpool_); 2710 this->create_dynamic_symtab(input_objects, symtab, &dynstr, 2711 &local_dynamic_count, &dynamic_symbols, 2712 &versions); 2713 2714 // Create the .interp section to hold the name of the 2715 // interpreter, and put it in a PT_INTERP segment. Don't do it 2716 // if we saw a .interp section in an input file. 2717 if ((!parameters->options().shared() 2718 || parameters->options().dynamic_linker() != NULL) 2719 && this->interp_segment_ == NULL) 2720 this->create_interp(target); 2721 2722 // Finish the .dynamic section to hold the dynamic data, and put 2723 // it in a PT_DYNAMIC segment. 2724 this->finish_dynamic_section(input_objects, symtab); 2725 2726 // We should have added everything we need to the dynamic string 2727 // table. 2728 this->dynpool_.set_string_offsets(); 2729 2730 // Create the version sections. We can't do this until the 2731 // dynamic string table is complete. 2732 this->create_version_sections(&versions, symtab, local_dynamic_count, 2733 dynamic_symbols, dynstr); 2734 2735 // Set the size of the _DYNAMIC symbol. We can't do this until 2736 // after we call create_version_sections. 2737 this->set_dynamic_symbol_size(symtab); 2738 } 2739 2740 // Create segment headers. 2741 Output_segment_headers* segment_headers = 2742 (parameters->options().relocatable() 2743 ? NULL 2744 : new Output_segment_headers(this->segment_list_)); 2745 2746 // Lay out the file header. 2747 Output_file_header* file_header = new Output_file_header(target, symtab, 2748 segment_headers); 2749 2750 this->special_output_list_.push_back(file_header); 2751 if (segment_headers != NULL) 2752 this->special_output_list_.push_back(segment_headers); 2753 2754 // Find approriate places for orphan output sections if we are using 2755 // a linker script. 2756 if (this->script_options_->saw_sections_clause()) 2757 this->place_orphan_sections_in_script(); 2758 2759 Output_segment* load_seg; 2760 off_t off; 2761 unsigned int shndx; 2762 int pass = 0; 2763 2764 // Take a snapshot of the section layout as needed. 2765 if (target->may_relax()) 2766 this->prepare_for_relaxation(); 2767 2768 // Run the relaxation loop to lay out sections. 2769 do 2770 { 2771 off = this->relaxation_loop_body(pass, target, symtab, &load_seg, 2772 phdr_seg, segment_headers, file_header, 2773 &shndx); 2774 pass++; 2775 } 2776 while (target->may_relax() 2777 && target->relax(pass, input_objects, symtab, this, task)); 2778 2779 // Check if data segment size is less than the safe value with PIE links. 2780 if (parameters->options().pie() && target->max_pie_data_segment_size()) 2781 { 2782 Segment_list::const_iterator p; 2783 uint64_t re_vaddr = 0, re_memsz = 0, rw_vaddr = 0, rw_memsz = 0; 2784 uint64_t data_seg_size = 0; 2785 for (p = this->segment_list_.begin(); 2786 p != this->segment_list_.end(); 2787 ++p) 2788 { 2789 // With -Wl,--rosegment, note the end addr of "R E" segment. 2790 if (parameters->options().rosegment() 2791 && (*p)->type() == elfcpp::PT_LOAD 2792 && ((*p)->flags() & elfcpp::PF_X) != 0 2793 && ((*p)->flags() & elfcpp::PF_R) != 0) 2794 { 2795 re_vaddr = (*p)->vaddr(); 2796 re_memsz = (*p)->memsz(); 2797 continue; 2798 } 2799 if ((*p)->type() == elfcpp::PT_LOAD 2800 && ((*p)->flags() & elfcpp::PF_W) != 0 2801 && ((*p)->flags() & elfcpp::PF_R) != 0) 2802 { 2803 rw_vaddr = (*p)->vaddr(); 2804 rw_memsz = (*p)->memsz(); 2805 break; 2806 } 2807 } 2808 2809 // With -Wl,--rosegment, report data segment size as delta of end of 2810 // "RW" segment and end of "R E" segment. Otherwise, data segment 2811 // size is just the memsz of "RW" segment. 2812 if (parameters->options().rosegment()) 2813 data_seg_size = (rw_vaddr + rw_memsz) - (re_vaddr + re_memsz); 2814 else 2815 data_seg_size = rw_memsz; 2816 2817 if (data_seg_size >= target->max_pie_data_segment_size()) 2818 gold_warning( 2819 _("Unsafe PIE data segment size (%" PRIu64 " > %" PRIu64 "). " 2820 "For kernels with CONFIG_ARCH_BINFMT_ELF_RANDOMIZE_PIE enabled, " 2821 "load_elf_binary() attempts to map a PIE binary into an address " 2822 "range immediately below mm->mmap_base. The first PT_LOAD segment " 2823 "is mapped below mm->mmap_base, the subsequent PT_LOAD segment(s) " 2824 "end up being mapped above mm->mmap_base into the area that is " 2825 "supposed to be the \"gap\" between the stack and the binary. Since" 2826 " the size of the \"gap\" on x86_64 is only guaranteed to be 128MB " 2827 "this means that binaries with large data segments > 128MB can end " 2828 "up mapping part of their data segment over their stack resulting " 2829 "in corruption of the stack. Any PIE binary with a data segment > " 2830 "128MB is vulnerable to this. It is suggested to turn off PIE."), 2831 data_seg_size, 2832 target->max_pie_data_segment_size()); 2833 } 2834 2835 // If there is a load segment that contains the file and program headers, 2836 // provide a symbol __ehdr_start pointing there. 2837 // A program can use this to examine itself robustly. 2838 Symbol *ehdr_start = symtab->lookup("__ehdr_start"); 2839 if (ehdr_start != NULL && ehdr_start->is_predefined()) 2840 { 2841 if (load_seg != NULL) 2842 ehdr_start->set_output_segment(load_seg, Symbol::SEGMENT_START); 2843 else 2844 ehdr_start->set_undefined(); 2845 } 2846 2847 // Set the file offsets of all the non-data sections we've seen so 2848 // far which don't have to wait for the input sections. We need 2849 // this in order to finalize local symbols in non-allocated 2850 // sections. 2851 off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS); 2852 2853 // Set the section indexes of all unallocated sections seen so far, 2854 // in case any of them are somehow referenced by a symbol. 2855 shndx = this->set_section_indexes(shndx); 2856 2857 // Create the symbol table sections. 2858 this->create_symtab_sections(input_objects, symtab, shndx, &off); 2859 if (!parameters->doing_static_link()) 2860 this->assign_local_dynsym_offsets(input_objects); 2861 2862 // Process any symbol assignments from a linker script. This must 2863 // be called after the symbol table has been finalized. 2864 this->script_options_->finalize_symbols(symtab, this); 2865 2866 // Create the incremental inputs sections. 2867 if (this->incremental_inputs_) 2868 { 2869 this->incremental_inputs_->finalize(); 2870 this->create_incremental_info_sections(symtab); 2871 } 2872 2873 // Create the .shstrtab section. 2874 Output_section* shstrtab_section = this->create_shstrtab(); 2875 2876 // Set the file offsets of the rest of the non-data sections which 2877 // don't have to wait for the input sections. 2878 off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS); 2879 2880 // Now that all sections have been created, set the section indexes 2881 // for any sections which haven't been done yet. 2882 shndx = this->set_section_indexes(shndx); 2883 2884 // Create the section table header. 2885 this->create_shdrs(shstrtab_section, &off); 2886 2887 // If there are no sections which require postprocessing, we can 2888 // handle the section names now, and avoid a resize later. 2889 if (!this->any_postprocessing_sections_) 2890 { 2891 off = this->set_section_offsets(off, 2892 POSTPROCESSING_SECTIONS_PASS); 2893 off = 2894 this->set_section_offsets(off, 2895 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS); 2896 } 2897 2898 file_header->set_section_info(this->section_headers_, shstrtab_section); 2899 2900 // Now we know exactly where everything goes in the output file 2901 // (except for non-allocated sections which require postprocessing). 2902 Output_data::layout_complete(); 2903 2904 this->output_file_size_ = off; 2905 2906 return off; 2907 } 2908 2909 // Create a note header following the format defined in the ELF ABI. 2910 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name 2911 // of the section to create, DESCSZ is the size of the descriptor. 2912 // ALLOCATE is true if the section should be allocated in memory. 2913 // This returns the new note section. It sets *TRAILING_PADDING to 2914 // the number of trailing zero bytes required. 2915 2916 Output_section* 2917 Layout::create_note(const char* name, int note_type, 2918 const char* section_name, size_t descsz, 2919 bool allocate, size_t* trailing_padding) 2920 { 2921 // Authorities all agree that the values in a .note field should 2922 // be aligned on 4-byte boundaries for 32-bit binaries. However, 2923 // they differ on what the alignment is for 64-bit binaries. 2924 // The GABI says unambiguously they take 8-byte alignment: 2925 // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section 2926 // Other documentation says alignment should always be 4 bytes: 2927 // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format 2928 // GNU ld and GNU readelf both support the latter (at least as of 2929 // version 2.16.91), and glibc always generates the latter for 2930 // .note.ABI-tag (as of version 1.6), so that's the one we go with 2931 // here. 2932 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default. 2933 const int size = parameters->target().get_size(); 2934 #else 2935 const int size = 32; 2936 #endif 2937 2938 // The contents of the .note section. 2939 size_t namesz = strlen(name) + 1; 2940 size_t aligned_namesz = align_address(namesz, size / 8); 2941 size_t aligned_descsz = align_address(descsz, size / 8); 2942 2943 size_t notehdrsz = 3 * (size / 8) + aligned_namesz; 2944 2945 unsigned char* buffer = new unsigned char[notehdrsz]; 2946 memset(buffer, 0, notehdrsz); 2947 2948 bool is_big_endian = parameters->target().is_big_endian(); 2949 2950 if (size == 32) 2951 { 2952 if (!is_big_endian) 2953 { 2954 elfcpp::Swap<32, false>::writeval(buffer, namesz); 2955 elfcpp::Swap<32, false>::writeval(buffer + 4, descsz); 2956 elfcpp::Swap<32, false>::writeval(buffer + 8, note_type); 2957 } 2958 else 2959 { 2960 elfcpp::Swap<32, true>::writeval(buffer, namesz); 2961 elfcpp::Swap<32, true>::writeval(buffer + 4, descsz); 2962 elfcpp::Swap<32, true>::writeval(buffer + 8, note_type); 2963 } 2964 } 2965 else if (size == 64) 2966 { 2967 if (!is_big_endian) 2968 { 2969 elfcpp::Swap<64, false>::writeval(buffer, namesz); 2970 elfcpp::Swap<64, false>::writeval(buffer + 8, descsz); 2971 elfcpp::Swap<64, false>::writeval(buffer + 16, note_type); 2972 } 2973 else 2974 { 2975 elfcpp::Swap<64, true>::writeval(buffer, namesz); 2976 elfcpp::Swap<64, true>::writeval(buffer + 8, descsz); 2977 elfcpp::Swap<64, true>::writeval(buffer + 16, note_type); 2978 } 2979 } 2980 else 2981 gold_unreachable(); 2982 2983 memcpy(buffer + 3 * (size / 8), name, namesz); 2984 2985 elfcpp::Elf_Xword flags = 0; 2986 Output_section_order order = ORDER_INVALID; 2987 if (allocate) 2988 { 2989 flags = elfcpp::SHF_ALLOC; 2990 order = ORDER_RO_NOTE; 2991 } 2992 Output_section* os = this->choose_output_section(NULL, section_name, 2993 elfcpp::SHT_NOTE, 2994 flags, false, order, false); 2995 if (os == NULL) 2996 return NULL; 2997 2998 Output_section_data* posd = new Output_data_const_buffer(buffer, notehdrsz, 2999 size / 8, 3000 "** note header"); 3001 os->add_output_section_data(posd); 3002 3003 *trailing_padding = aligned_descsz - descsz; 3004 3005 return os; 3006 } 3007 3008 // For an executable or shared library, create a note to record the 3009 // version of gold used to create the binary. 3010 3011 void 3012 Layout::create_gold_note() 3013 { 3014 if (parameters->options().relocatable() 3015 || parameters->incremental_update()) 3016 return; 3017 3018 std::string desc = std::string("gold ") + gold::get_version_string(); 3019 3020 size_t trailing_padding; 3021 Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION, 3022 ".note.gnu.gold-version", desc.size(), 3023 false, &trailing_padding); 3024 if (os == NULL) 3025 return; 3026 3027 Output_section_data* posd = new Output_data_const(desc, 4); 3028 os->add_output_section_data(posd); 3029 3030 if (trailing_padding > 0) 3031 { 3032 posd = new Output_data_zero_fill(trailing_padding, 0); 3033 os->add_output_section_data(posd); 3034 } 3035 } 3036 3037 // Record whether the stack should be executable. This can be set 3038 // from the command line using the -z execstack or -z noexecstack 3039 // options. Otherwise, if any input file has a .note.GNU-stack 3040 // section with the SHF_EXECINSTR flag set, the stack should be 3041 // executable. Otherwise, if at least one input file a 3042 // .note.GNU-stack section, and some input file has no .note.GNU-stack 3043 // section, we use the target default for whether the stack should be 3044 // executable. If -z stack-size was used to set a p_memsz value for 3045 // PT_GNU_STACK, we generate the segment regardless. Otherwise, we 3046 // don't generate a stack note. When generating a object file, we 3047 // create a .note.GNU-stack section with the appropriate marking. 3048 // When generating an executable or shared library, we create a 3049 // PT_GNU_STACK segment. 3050 3051 void 3052 Layout::create_stack_segment() 3053 { 3054 bool is_stack_executable; 3055 if (parameters->options().is_execstack_set()) 3056 { 3057 is_stack_executable = parameters->options().is_stack_executable(); 3058 if (!is_stack_executable 3059 && this->input_requires_executable_stack_ 3060 && parameters->options().warn_execstack()) 3061 gold_warning(_("one or more inputs require executable stack, " 3062 "but -z noexecstack was given")); 3063 } 3064 else if (!this->input_with_gnu_stack_note_ 3065 && (!parameters->options().user_set_stack_size() 3066 || parameters->options().relocatable())) 3067 return; 3068 else 3069 { 3070 if (this->input_requires_executable_stack_) 3071 is_stack_executable = true; 3072 else if (this->input_without_gnu_stack_note_) 3073 is_stack_executable = 3074 parameters->target().is_default_stack_executable(); 3075 else 3076 is_stack_executable = false; 3077 } 3078 3079 if (parameters->options().relocatable()) 3080 { 3081 const char* name = this->namepool_.add(".note.GNU-stack", false, NULL); 3082 elfcpp::Elf_Xword flags = 0; 3083 if (is_stack_executable) 3084 flags |= elfcpp::SHF_EXECINSTR; 3085 this->make_output_section(name, elfcpp::SHT_PROGBITS, flags, 3086 ORDER_INVALID, false); 3087 } 3088 else 3089 { 3090 if (this->script_options_->saw_phdrs_clause()) 3091 return; 3092 int flags = elfcpp::PF_R | elfcpp::PF_W; 3093 if (is_stack_executable) 3094 flags |= elfcpp::PF_X; 3095 Output_segment* seg = 3096 this->make_output_segment(elfcpp::PT_GNU_STACK, flags); 3097 seg->set_size(parameters->options().stack_size()); 3098 // BFD lets targets override this default alignment, but the only 3099 // targets that do so are ones that Gold does not support so far. 3100 seg->set_minimum_p_align(16); 3101 } 3102 } 3103 3104 // If --build-id was used, set up the build ID note. 3105 3106 void 3107 Layout::create_build_id() 3108 { 3109 if (!parameters->options().user_set_build_id()) 3110 return; 3111 3112 const char* style = parameters->options().build_id(); 3113 if (strcmp(style, "none") == 0) 3114 return; 3115 3116 // Set DESCSZ to the size of the note descriptor. When possible, 3117 // set DESC to the note descriptor contents. 3118 size_t descsz; 3119 std::string desc; 3120 if (strcmp(style, "md5") == 0) 3121 descsz = 128 / 8; 3122 else if ((strcmp(style, "sha1") == 0) || (strcmp(style, "tree") == 0)) 3123 descsz = 160 / 8; 3124 else if (strcmp(style, "uuid") == 0) 3125 { 3126 const size_t uuidsz = 128 / 8; 3127 3128 char buffer[uuidsz]; 3129 memset(buffer, 0, uuidsz); 3130 3131 int descriptor = open_descriptor(-1, "/dev/urandom", O_RDONLY); 3132 if (descriptor < 0) 3133 gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"), 3134 strerror(errno)); 3135 else 3136 { 3137 ssize_t got = ::read(descriptor, buffer, uuidsz); 3138 release_descriptor(descriptor, true); 3139 if (got < 0) 3140 gold_error(_("/dev/urandom: read failed: %s"), strerror(errno)); 3141 else if (static_cast<size_t>(got) != uuidsz) 3142 gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"), 3143 uuidsz, got); 3144 } 3145 3146 desc.assign(buffer, uuidsz); 3147 descsz = uuidsz; 3148 } 3149 else if (strncmp(style, "0x", 2) == 0) 3150 { 3151 hex_init(); 3152 const char* p = style + 2; 3153 while (*p != '\0') 3154 { 3155 if (hex_p(p[0]) && hex_p(p[1])) 3156 { 3157 char c = (hex_value(p[0]) << 4) | hex_value(p[1]); 3158 desc += c; 3159 p += 2; 3160 } 3161 else if (*p == '-' || *p == ':') 3162 ++p; 3163 else 3164 gold_fatal(_("--build-id argument '%s' not a valid hex number"), 3165 style); 3166 } 3167 descsz = desc.size(); 3168 } 3169 else 3170 gold_fatal(_("unrecognized --build-id argument '%s'"), style); 3171 3172 // Create the note. 3173 size_t trailing_padding; 3174 Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID, 3175 ".note.gnu.build-id", descsz, true, 3176 &trailing_padding); 3177 if (os == NULL) 3178 return; 3179 3180 if (!desc.empty()) 3181 { 3182 // We know the value already, so we fill it in now. 3183 gold_assert(desc.size() == descsz); 3184 3185 Output_section_data* posd = new Output_data_const(desc, 4); 3186 os->add_output_section_data(posd); 3187 3188 if (trailing_padding != 0) 3189 { 3190 posd = new Output_data_zero_fill(trailing_padding, 0); 3191 os->add_output_section_data(posd); 3192 } 3193 } 3194 else 3195 { 3196 // We need to compute a checksum after we have completed the 3197 // link. 3198 gold_assert(trailing_padding == 0); 3199 this->build_id_note_ = new Output_data_zero_fill(descsz, 4); 3200 os->add_output_section_data(this->build_id_note_); 3201 } 3202 } 3203 3204 // If we have both .stabXX and .stabXXstr sections, then the sh_link 3205 // field of the former should point to the latter. I'm not sure who 3206 // started this, but the GNU linker does it, and some tools depend 3207 // upon it. 3208 3209 void 3210 Layout::link_stabs_sections() 3211 { 3212 if (!this->have_stabstr_section_) 3213 return; 3214 3215 for (Section_list::iterator p = this->section_list_.begin(); 3216 p != this->section_list_.end(); 3217 ++p) 3218 { 3219 if ((*p)->type() != elfcpp::SHT_STRTAB) 3220 continue; 3221 3222 const char* name = (*p)->name(); 3223 if (strncmp(name, ".stab", 5) != 0) 3224 continue; 3225 3226 size_t len = strlen(name); 3227 if (strcmp(name + len - 3, "str") != 0) 3228 continue; 3229 3230 std::string stab_name(name, len - 3); 3231 Output_section* stab_sec; 3232 stab_sec = this->find_output_section(stab_name.c_str()); 3233 if (stab_sec != NULL) 3234 stab_sec->set_link_section(*p); 3235 } 3236 } 3237 3238 // Create .gnu_incremental_inputs and related sections needed 3239 // for the next run of incremental linking to check what has changed. 3240 3241 void 3242 Layout::create_incremental_info_sections(Symbol_table* symtab) 3243 { 3244 Incremental_inputs* incr = this->incremental_inputs_; 3245 3246 gold_assert(incr != NULL); 3247 3248 // Create the .gnu_incremental_inputs, _symtab, and _relocs input sections. 3249 incr->create_data_sections(symtab); 3250 3251 // Add the .gnu_incremental_inputs section. 3252 const char* incremental_inputs_name = 3253 this->namepool_.add(".gnu_incremental_inputs", false, NULL); 3254 Output_section* incremental_inputs_os = 3255 this->make_output_section(incremental_inputs_name, 3256 elfcpp::SHT_GNU_INCREMENTAL_INPUTS, 0, 3257 ORDER_INVALID, false); 3258 incremental_inputs_os->add_output_section_data(incr->inputs_section()); 3259 3260 // Add the .gnu_incremental_symtab section. 3261 const char* incremental_symtab_name = 3262 this->namepool_.add(".gnu_incremental_symtab", false, NULL); 3263 Output_section* incremental_symtab_os = 3264 this->make_output_section(incremental_symtab_name, 3265 elfcpp::SHT_GNU_INCREMENTAL_SYMTAB, 0, 3266 ORDER_INVALID, false); 3267 incremental_symtab_os->add_output_section_data(incr->symtab_section()); 3268 incremental_symtab_os->set_entsize(4); 3269 3270 // Add the .gnu_incremental_relocs section. 3271 const char* incremental_relocs_name = 3272 this->namepool_.add(".gnu_incremental_relocs", false, NULL); 3273 Output_section* incremental_relocs_os = 3274 this->make_output_section(incremental_relocs_name, 3275 elfcpp::SHT_GNU_INCREMENTAL_RELOCS, 0, 3276 ORDER_INVALID, false); 3277 incremental_relocs_os->add_output_section_data(incr->relocs_section()); 3278 incremental_relocs_os->set_entsize(incr->relocs_entsize()); 3279 3280 // Add the .gnu_incremental_got_plt section. 3281 const char* incremental_got_plt_name = 3282 this->namepool_.add(".gnu_incremental_got_plt", false, NULL); 3283 Output_section* incremental_got_plt_os = 3284 this->make_output_section(incremental_got_plt_name, 3285 elfcpp::SHT_GNU_INCREMENTAL_GOT_PLT, 0, 3286 ORDER_INVALID, false); 3287 incremental_got_plt_os->add_output_section_data(incr->got_plt_section()); 3288 3289 // Add the .gnu_incremental_strtab section. 3290 const char* incremental_strtab_name = 3291 this->namepool_.add(".gnu_incremental_strtab", false, NULL); 3292 Output_section* incremental_strtab_os = this->make_output_section(incremental_strtab_name, 3293 elfcpp::SHT_STRTAB, 0, 3294 ORDER_INVALID, false); 3295 Output_data_strtab* strtab_data = 3296 new Output_data_strtab(incr->get_stringpool()); 3297 incremental_strtab_os->add_output_section_data(strtab_data); 3298 3299 incremental_inputs_os->set_after_input_sections(); 3300 incremental_symtab_os->set_after_input_sections(); 3301 incremental_relocs_os->set_after_input_sections(); 3302 incremental_got_plt_os->set_after_input_sections(); 3303 3304 incremental_inputs_os->set_link_section(incremental_strtab_os); 3305 incremental_symtab_os->set_link_section(incremental_inputs_os); 3306 incremental_relocs_os->set_link_section(incremental_inputs_os); 3307 incremental_got_plt_os->set_link_section(incremental_inputs_os); 3308 } 3309 3310 // Return whether SEG1 should be before SEG2 in the output file. This 3311 // is based entirely on the segment type and flags. When this is 3312 // called the segment addresses have normally not yet been set. 3313 3314 bool 3315 Layout::segment_precedes(const Output_segment* seg1, 3316 const Output_segment* seg2) 3317 { 3318 elfcpp::Elf_Word type1 = seg1->type(); 3319 elfcpp::Elf_Word type2 = seg2->type(); 3320 3321 // The single PT_PHDR segment is required to precede any loadable 3322 // segment. We simply make it always first. 3323 if (type1 == elfcpp::PT_PHDR) 3324 { 3325 gold_assert(type2 != elfcpp::PT_PHDR); 3326 return true; 3327 } 3328 if (type2 == elfcpp::PT_PHDR) 3329 return false; 3330 3331 // The single PT_INTERP segment is required to precede any loadable 3332 // segment. We simply make it always second. 3333 if (type1 == elfcpp::PT_INTERP) 3334 { 3335 gold_assert(type2 != elfcpp::PT_INTERP); 3336 return true; 3337 } 3338 if (type2 == elfcpp::PT_INTERP) 3339 return false; 3340 3341 // We then put PT_LOAD segments before any other segments. 3342 if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD) 3343 return true; 3344 if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD) 3345 return false; 3346 3347 // We put the PT_TLS segment last except for the PT_GNU_RELRO 3348 // segment, because that is where the dynamic linker expects to find 3349 // it (this is just for efficiency; other positions would also work 3350 // correctly). 3351 if (type1 == elfcpp::PT_TLS 3352 && type2 != elfcpp::PT_TLS 3353 && type2 != elfcpp::PT_GNU_RELRO) 3354 return false; 3355 if (type2 == elfcpp::PT_TLS 3356 && type1 != elfcpp::PT_TLS 3357 && type1 != elfcpp::PT_GNU_RELRO) 3358 return true; 3359 3360 // We put the PT_GNU_RELRO segment last, because that is where the 3361 // dynamic linker expects to find it (as with PT_TLS, this is just 3362 // for efficiency). 3363 if (type1 == elfcpp::PT_GNU_RELRO && type2 != elfcpp::PT_GNU_RELRO) 3364 return false; 3365 if (type2 == elfcpp::PT_GNU_RELRO && type1 != elfcpp::PT_GNU_RELRO) 3366 return true; 3367 3368 const elfcpp::Elf_Word flags1 = seg1->flags(); 3369 const elfcpp::Elf_Word flags2 = seg2->flags(); 3370 3371 // The order of non-PT_LOAD segments is unimportant. We simply sort 3372 // by the numeric segment type and flags values. There should not 3373 // be more than one segment with the same type and flags, except 3374 // when a linker script specifies such. 3375 if (type1 != elfcpp::PT_LOAD) 3376 { 3377 if (type1 != type2) 3378 return type1 < type2; 3379 gold_assert(flags1 != flags2 3380 || this->script_options_->saw_phdrs_clause()); 3381 return flags1 < flags2; 3382 } 3383 3384 // If the addresses are set already, sort by load address. 3385 if (seg1->are_addresses_set()) 3386 { 3387 if (!seg2->are_addresses_set()) 3388 return true; 3389 3390 unsigned int section_count1 = seg1->output_section_count(); 3391 unsigned int section_count2 = seg2->output_section_count(); 3392 if (section_count1 == 0 && section_count2 > 0) 3393 return true; 3394 if (section_count1 > 0 && section_count2 == 0) 3395 return false; 3396 3397 uint64_t paddr1 = (seg1->are_addresses_set() 3398 ? seg1->paddr() 3399 : seg1->first_section_load_address()); 3400 uint64_t paddr2 = (seg2->are_addresses_set() 3401 ? seg2->paddr() 3402 : seg2->first_section_load_address()); 3403 3404 if (paddr1 != paddr2) 3405 return paddr1 < paddr2; 3406 } 3407 else if (seg2->are_addresses_set()) 3408 return false; 3409 3410 // A segment which holds large data comes after a segment which does 3411 // not hold large data. 3412 if (seg1->is_large_data_segment()) 3413 { 3414 if (!seg2->is_large_data_segment()) 3415 return false; 3416 } 3417 else if (seg2->is_large_data_segment()) 3418 return true; 3419 3420 // Otherwise, we sort PT_LOAD segments based on the flags. Readonly 3421 // segments come before writable segments. Then writable segments 3422 // with data come before writable segments without data. Then 3423 // executable segments come before non-executable segments. Then 3424 // the unlikely case of a non-readable segment comes before the 3425 // normal case of a readable segment. If there are multiple 3426 // segments with the same type and flags, we require that the 3427 // address be set, and we sort by virtual address and then physical 3428 // address. 3429 if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W)) 3430 return (flags1 & elfcpp::PF_W) == 0; 3431 if ((flags1 & elfcpp::PF_W) != 0 3432 && seg1->has_any_data_sections() != seg2->has_any_data_sections()) 3433 return seg1->has_any_data_sections(); 3434 if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X)) 3435 return (flags1 & elfcpp::PF_X) != 0; 3436 if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R)) 3437 return (flags1 & elfcpp::PF_R) == 0; 3438 3439 // We shouldn't get here--we shouldn't create segments which we 3440 // can't distinguish. Unless of course we are using a weird linker 3441 // script or overlapping --section-start options. We could also get 3442 // here if plugins want unique segments for subsets of sections. 3443 gold_assert(this->script_options_->saw_phdrs_clause() 3444 || parameters->options().any_section_start() 3445 || this->is_unique_segment_for_sections_specified()); 3446 return false; 3447 } 3448 3449 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE. 3450 3451 static off_t 3452 align_file_offset(off_t off, uint64_t addr, uint64_t abi_pagesize) 3453 { 3454 uint64_t unsigned_off = off; 3455 uint64_t aligned_off = ((unsigned_off & ~(abi_pagesize - 1)) 3456 | (addr & (abi_pagesize - 1))); 3457 if (aligned_off < unsigned_off) 3458 aligned_off += abi_pagesize; 3459 return aligned_off; 3460 } 3461 3462 // On targets where the text segment contains only executable code, 3463 // a non-executable segment is never the text segment. 3464 3465 static inline bool 3466 is_text_segment(const Target* target, const Output_segment* seg) 3467 { 3468 elfcpp::Elf_Xword flags = seg->flags(); 3469 if ((flags & elfcpp::PF_W) != 0) 3470 return false; 3471 if ((flags & elfcpp::PF_X) == 0) 3472 return !target->isolate_execinstr(); 3473 return true; 3474 } 3475 3476 // Set the file offsets of all the segments, and all the sections they 3477 // contain. They have all been created. LOAD_SEG must be be laid out 3478 // first. Return the offset of the data to follow. 3479 3480 off_t 3481 Layout::set_segment_offsets(const Target* target, Output_segment* load_seg, 3482 unsigned int* pshndx) 3483 { 3484 // Sort them into the final order. We use a stable sort so that we 3485 // don't randomize the order of indistinguishable segments created 3486 // by linker scripts. 3487 std::stable_sort(this->segment_list_.begin(), this->segment_list_.end(), 3488 Layout::Compare_segments(this)); 3489 3490 // Find the PT_LOAD segments, and set their addresses and offsets 3491 // and their section's addresses and offsets. 3492 uint64_t start_addr; 3493 if (parameters->options().user_set_Ttext()) 3494 start_addr = parameters->options().Ttext(); 3495 else if (parameters->options().output_is_position_independent()) 3496 start_addr = 0; 3497 else 3498 start_addr = target->default_text_segment_address(); 3499 3500 uint64_t addr = start_addr; 3501 off_t off = 0; 3502 3503 // If LOAD_SEG is NULL, then the file header and segment headers 3504 // will not be loadable. But they still need to be at offset 0 in 3505 // the file. Set their offsets now. 3506 if (load_seg == NULL) 3507 { 3508 for (Data_list::iterator p = this->special_output_list_.begin(); 3509 p != this->special_output_list_.end(); 3510 ++p) 3511 { 3512 off = align_address(off, (*p)->addralign()); 3513 (*p)->set_address_and_file_offset(0, off); 3514 off += (*p)->data_size(); 3515 } 3516 } 3517 3518 unsigned int increase_relro = this->increase_relro_; 3519 if (this->script_options_->saw_sections_clause()) 3520 increase_relro = 0; 3521 3522 const bool check_sections = parameters->options().check_sections(); 3523 Output_segment* last_load_segment = NULL; 3524 3525 unsigned int shndx_begin = *pshndx; 3526 unsigned int shndx_load_seg = *pshndx; 3527 3528 for (Segment_list::iterator p = this->segment_list_.begin(); 3529 p != this->segment_list_.end(); 3530 ++p) 3531 { 3532 if ((*p)->type() == elfcpp::PT_LOAD) 3533 { 3534 if (target->isolate_execinstr()) 3535 { 3536 // When we hit the segment that should contain the 3537 // file headers, reset the file offset so we place 3538 // it and subsequent segments appropriately. 3539 // We'll fix up the preceding segments below. 3540 if (load_seg == *p) 3541 { 3542 if (off == 0) 3543 load_seg = NULL; 3544 else 3545 { 3546 off = 0; 3547 shndx_load_seg = *pshndx; 3548 } 3549 } 3550 } 3551 else 3552 { 3553 // Verify that the file headers fall into the first segment. 3554 if (load_seg != NULL && load_seg != *p) 3555 gold_unreachable(); 3556 load_seg = NULL; 3557 } 3558 3559 bool are_addresses_set = (*p)->are_addresses_set(); 3560 if (are_addresses_set) 3561 { 3562 // When it comes to setting file offsets, we care about 3563 // the physical address. 3564 addr = (*p)->paddr(); 3565 } 3566 else if (parameters->options().user_set_Ttext() 3567 && (parameters->options().omagic() 3568 || is_text_segment(target, *p))) 3569 { 3570 are_addresses_set = true; 3571 } 3572 else if (parameters->options().user_set_Trodata_segment() 3573 && ((*p)->flags() & (elfcpp::PF_W | elfcpp::PF_X)) == 0) 3574 { 3575 addr = parameters->options().Trodata_segment(); 3576 are_addresses_set = true; 3577 } 3578 else if (parameters->options().user_set_Tdata() 3579 && ((*p)->flags() & elfcpp::PF_W) != 0 3580 && (!parameters->options().user_set_Tbss() 3581 || (*p)->has_any_data_sections())) 3582 { 3583 addr = parameters->options().Tdata(); 3584 are_addresses_set = true; 3585 } 3586 else if (parameters->options().user_set_Tbss() 3587 && ((*p)->flags() & elfcpp::PF_W) != 0 3588 && !(*p)->has_any_data_sections()) 3589 { 3590 addr = parameters->options().Tbss(); 3591 are_addresses_set = true; 3592 } 3593 3594 uint64_t orig_addr = addr; 3595 uint64_t orig_off = off; 3596 3597 uint64_t aligned_addr = 0; 3598 uint64_t abi_pagesize = target->abi_pagesize(); 3599 uint64_t common_pagesize = target->common_pagesize(); 3600 3601 if (!parameters->options().nmagic() 3602 && !parameters->options().omagic()) 3603 (*p)->set_minimum_p_align(abi_pagesize); 3604 3605 if (!are_addresses_set) 3606 { 3607 // Skip the address forward one page, maintaining the same 3608 // position within the page. This lets us store both segments 3609 // overlapping on a single page in the file, but the loader will 3610 // put them on different pages in memory. We will revisit this 3611 // decision once we know the size of the segment. 3612 3613 uint64_t max_align = (*p)->maximum_alignment(); 3614 if (max_align > abi_pagesize) 3615 addr = align_address(addr, max_align); 3616 aligned_addr = addr; 3617 3618 if (load_seg == *p) 3619 { 3620 // This is the segment that will contain the file 3621 // headers, so its offset will have to be exactly zero. 3622 gold_assert(orig_off == 0); 3623 3624 // If the target wants a fixed minimum distance from the 3625 // text segment to the read-only segment, move up now. 3626 uint64_t min_addr = 3627 start_addr + (parameters->options().user_set_rosegment_gap() 3628 ? parameters->options().rosegment_gap() 3629 : target->rosegment_gap()); 3630 if (addr < min_addr) 3631 addr = min_addr; 3632 3633 // But this is not the first segment! To make its 3634 // address congruent with its offset, that address better 3635 // be aligned to the ABI-mandated page size. 3636 addr = align_address(addr, abi_pagesize); 3637 aligned_addr = addr; 3638 } 3639 else 3640 { 3641 if ((addr & (abi_pagesize - 1)) != 0) 3642 addr = addr + abi_pagesize; 3643 3644 off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1)); 3645 } 3646 } 3647 3648 if (!parameters->options().nmagic() 3649 && !parameters->options().omagic()) 3650 { 3651 // Here we are also taking care of the case when 3652 // the maximum segment alignment is larger than the page size. 3653 off = align_file_offset(off, addr, 3654 std::max(abi_pagesize, 3655 (*p)->maximum_alignment())); 3656 } 3657 else 3658 { 3659 // This is -N or -n with a section script which prevents 3660 // us from using a load segment. We need to ensure that 3661 // the file offset is aligned to the alignment of the 3662 // segment. This is because the linker script 3663 // implicitly assumed a zero offset. If we don't align 3664 // here, then the alignment of the sections in the 3665 // linker script may not match the alignment of the 3666 // sections in the set_section_addresses call below, 3667 // causing an error about dot moving backward. 3668 off = align_address(off, (*p)->maximum_alignment()); 3669 } 3670 3671 unsigned int shndx_hold = *pshndx; 3672 bool has_relro = false; 3673 uint64_t new_addr = (*p)->set_section_addresses(target, this, 3674 false, addr, 3675 &increase_relro, 3676 &has_relro, 3677 &off, pshndx); 3678 3679 // Now that we know the size of this segment, we may be able 3680 // to save a page in memory, at the cost of wasting some 3681 // file space, by instead aligning to the start of a new 3682 // page. Here we use the real machine page size rather than 3683 // the ABI mandated page size. If the segment has been 3684 // aligned so that the relro data ends at a page boundary, 3685 // we do not try to realign it. 3686 3687 if (!are_addresses_set 3688 && !has_relro 3689 && aligned_addr != addr 3690 && !parameters->incremental()) 3691 { 3692 uint64_t first_off = (common_pagesize 3693 - (aligned_addr 3694 & (common_pagesize - 1))); 3695 uint64_t last_off = new_addr & (common_pagesize - 1); 3696 if (first_off > 0 3697 && last_off > 0 3698 && ((aligned_addr & ~ (common_pagesize - 1)) 3699 != (new_addr & ~ (common_pagesize - 1))) 3700 && first_off + last_off <= common_pagesize) 3701 { 3702 *pshndx = shndx_hold; 3703 addr = align_address(aligned_addr, common_pagesize); 3704 addr = align_address(addr, (*p)->maximum_alignment()); 3705 if ((addr & (abi_pagesize - 1)) != 0) 3706 addr = addr + abi_pagesize; 3707 off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1)); 3708 off = align_file_offset(off, addr, abi_pagesize); 3709 3710 increase_relro = this->increase_relro_; 3711 if (this->script_options_->saw_sections_clause()) 3712 increase_relro = 0; 3713 has_relro = false; 3714 3715 new_addr = (*p)->set_section_addresses(target, this, 3716 true, addr, 3717 &increase_relro, 3718 &has_relro, 3719 &off, pshndx); 3720 } 3721 } 3722 3723 addr = new_addr; 3724 3725 // Implement --check-sections. We know that the segments 3726 // are sorted by LMA. 3727 if (check_sections && last_load_segment != NULL) 3728 { 3729 gold_assert(last_load_segment->paddr() <= (*p)->paddr()); 3730 if (last_load_segment->paddr() + last_load_segment->memsz() 3731 > (*p)->paddr()) 3732 { 3733 unsigned long long lb1 = last_load_segment->paddr(); 3734 unsigned long long le1 = lb1 + last_load_segment->memsz(); 3735 unsigned long long lb2 = (*p)->paddr(); 3736 unsigned long long le2 = lb2 + (*p)->memsz(); 3737 gold_error(_("load segment overlap [0x%llx -> 0x%llx] and " 3738 "[0x%llx -> 0x%llx]"), 3739 lb1, le1, lb2, le2); 3740 } 3741 } 3742 last_load_segment = *p; 3743 } 3744 } 3745 3746 if (load_seg != NULL && target->isolate_execinstr()) 3747 { 3748 // Process the early segments again, setting their file offsets 3749 // so they land after the segments starting at LOAD_SEG. 3750 off = align_file_offset(off, 0, target->abi_pagesize()); 3751 3752 this->reset_relax_output(); 3753 3754 for (Segment_list::iterator p = this->segment_list_.begin(); 3755 *p != load_seg; 3756 ++p) 3757 { 3758 if ((*p)->type() == elfcpp::PT_LOAD) 3759 { 3760 // We repeat the whole job of assigning addresses and 3761 // offsets, but we really only want to change the offsets and 3762 // must ensure that the addresses all come out the same as 3763 // they did the first time through. 3764 bool has_relro = false; 3765 const uint64_t old_addr = (*p)->vaddr(); 3766 const uint64_t old_end = old_addr + (*p)->memsz(); 3767 uint64_t new_addr = (*p)->set_section_addresses(target, this, 3768 true, old_addr, 3769 &increase_relro, 3770 &has_relro, 3771 &off, 3772 &shndx_begin); 3773 gold_assert(new_addr == old_end); 3774 } 3775 } 3776 3777 gold_assert(shndx_begin == shndx_load_seg); 3778 } 3779 3780 // Handle the non-PT_LOAD segments, setting their offsets from their 3781 // section's offsets. 3782 for (Segment_list::iterator p = this->segment_list_.begin(); 3783 p != this->segment_list_.end(); 3784 ++p) 3785 { 3786 // PT_GNU_STACK was set up correctly when it was created. 3787 if ((*p)->type() != elfcpp::PT_LOAD 3788 && (*p)->type() != elfcpp::PT_GNU_STACK) 3789 (*p)->set_offset((*p)->type() == elfcpp::PT_GNU_RELRO 3790 ? increase_relro 3791 : 0); 3792 } 3793 3794 // Set the TLS offsets for each section in the PT_TLS segment. 3795 if (this->tls_segment_ != NULL) 3796 this->tls_segment_->set_tls_offsets(); 3797 3798 return off; 3799 } 3800 3801 // Set the offsets of all the allocated sections when doing a 3802 // relocatable link. This does the same jobs as set_segment_offsets, 3803 // only for a relocatable link. 3804 3805 off_t 3806 Layout::set_relocatable_section_offsets(Output_data* file_header, 3807 unsigned int* pshndx) 3808 { 3809 off_t off = 0; 3810 3811 file_header->set_address_and_file_offset(0, 0); 3812 off += file_header->data_size(); 3813 3814 for (Section_list::iterator p = this->section_list_.begin(); 3815 p != this->section_list_.end(); 3816 ++p) 3817 { 3818 // We skip unallocated sections here, except that group sections 3819 // have to come first. 3820 if (((*p)->flags() & elfcpp::SHF_ALLOC) == 0 3821 && (*p)->type() != elfcpp::SHT_GROUP) 3822 continue; 3823 3824 off = align_address(off, (*p)->addralign()); 3825 3826 // The linker script might have set the address. 3827 if (!(*p)->is_address_valid()) 3828 (*p)->set_address(0); 3829 (*p)->set_file_offset(off); 3830 (*p)->finalize_data_size(); 3831 if ((*p)->type() != elfcpp::SHT_NOBITS) 3832 off += (*p)->data_size(); 3833 3834 (*p)->set_out_shndx(*pshndx); 3835 ++*pshndx; 3836 } 3837 3838 return off; 3839 } 3840 3841 // Set the file offset of all the sections not associated with a 3842 // segment. 3843 3844 off_t 3845 Layout::set_section_offsets(off_t off, Layout::Section_offset_pass pass) 3846 { 3847 off_t startoff = off; 3848 off_t maxoff = off; 3849 3850 for (Section_list::iterator p = this->unattached_section_list_.begin(); 3851 p != this->unattached_section_list_.end(); 3852 ++p) 3853 { 3854 // The symtab section is handled in create_symtab_sections. 3855 if (*p == this->symtab_section_) 3856 continue; 3857 3858 // If we've already set the data size, don't set it again. 3859 if ((*p)->is_offset_valid() && (*p)->is_data_size_valid()) 3860 continue; 3861 3862 if (pass == BEFORE_INPUT_SECTIONS_PASS 3863 && (*p)->requires_postprocessing()) 3864 { 3865 (*p)->create_postprocessing_buffer(); 3866 this->any_postprocessing_sections_ = true; 3867 } 3868 3869 if (pass == BEFORE_INPUT_SECTIONS_PASS 3870 && (*p)->after_input_sections()) 3871 continue; 3872 else if (pass == POSTPROCESSING_SECTIONS_PASS 3873 && (!(*p)->after_input_sections() 3874 || (*p)->type() == elfcpp::SHT_STRTAB)) 3875 continue; 3876 else if (pass == STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS 3877 && (!(*p)->after_input_sections() 3878 || (*p)->type() != elfcpp::SHT_STRTAB)) 3879 continue; 3880 3881 if (!parameters->incremental_update()) 3882 { 3883 off = align_address(off, (*p)->addralign()); 3884 (*p)->set_file_offset(off); 3885 (*p)->finalize_data_size(); 3886 } 3887 else 3888 { 3889 // Incremental update: allocate file space from free list. 3890 (*p)->pre_finalize_data_size(); 3891 off_t current_size = (*p)->current_data_size(); 3892 off = this->allocate(current_size, (*p)->addralign(), startoff); 3893 if (off == -1) 3894 { 3895 if (is_debugging_enabled(DEBUG_INCREMENTAL)) 3896 this->free_list_.dump(); 3897 gold_assert((*p)->output_section() != NULL); 3898 gold_fallback(_("out of patch space for section %s; " 3899 "relink with --incremental-full"), 3900 (*p)->output_section()->name()); 3901 } 3902 (*p)->set_file_offset(off); 3903 (*p)->finalize_data_size(); 3904 if ((*p)->data_size() > current_size) 3905 { 3906 gold_assert((*p)->output_section() != NULL); 3907 gold_fallback(_("%s: section changed size; " 3908 "relink with --incremental-full"), 3909 (*p)->output_section()->name()); 3910 } 3911 gold_debug(DEBUG_INCREMENTAL, 3912 "set_section_offsets: %08lx %08lx %s", 3913 static_cast<long>(off), 3914 static_cast<long>((*p)->data_size()), 3915 ((*p)->output_section() != NULL 3916 ? (*p)->output_section()->name() : "(special)")); 3917 } 3918 3919 off += (*p)->data_size(); 3920 if (off > maxoff) 3921 maxoff = off; 3922 3923 // At this point the name must be set. 3924 if (pass != STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS) 3925 this->namepool_.add((*p)->name(), false, NULL); 3926 } 3927 return maxoff; 3928 } 3929 3930 // Set the section indexes of all the sections not associated with a 3931 // segment. 3932 3933 unsigned int 3934 Layout::set_section_indexes(unsigned int shndx) 3935 { 3936 for (Section_list::iterator p = this->unattached_section_list_.begin(); 3937 p != this->unattached_section_list_.end(); 3938 ++p) 3939 { 3940 if (!(*p)->has_out_shndx()) 3941 { 3942 (*p)->set_out_shndx(shndx); 3943 ++shndx; 3944 } 3945 } 3946 return shndx; 3947 } 3948 3949 // Set the section addresses according to the linker script. This is 3950 // only called when we see a SECTIONS clause. This returns the 3951 // program segment which should hold the file header and segment 3952 // headers, if any. It will return NULL if they should not be in a 3953 // segment. 3954 3955 Output_segment* 3956 Layout::set_section_addresses_from_script(Symbol_table* symtab) 3957 { 3958 Script_sections* ss = this->script_options_->script_sections(); 3959 gold_assert(ss->saw_sections_clause()); 3960 return this->script_options_->set_section_addresses(symtab, this); 3961 } 3962 3963 // Place the orphan sections in the linker script. 3964 3965 void 3966 Layout::place_orphan_sections_in_script() 3967 { 3968 Script_sections* ss = this->script_options_->script_sections(); 3969 gold_assert(ss->saw_sections_clause()); 3970 3971 // Place each orphaned output section in the script. 3972 for (Section_list::iterator p = this->section_list_.begin(); 3973 p != this->section_list_.end(); 3974 ++p) 3975 { 3976 if (!(*p)->found_in_sections_clause()) 3977 ss->place_orphan(*p); 3978 } 3979 } 3980 3981 // Count the local symbols in the regular symbol table and the dynamic 3982 // symbol table, and build the respective string pools. 3983 3984 void 3985 Layout::count_local_symbols(const Task* task, 3986 const Input_objects* input_objects) 3987 { 3988 // First, figure out an upper bound on the number of symbols we'll 3989 // be inserting into each pool. This helps us create the pools with 3990 // the right size, to avoid unnecessary hashtable resizing. 3991 unsigned int symbol_count = 0; 3992 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 3993 p != input_objects->relobj_end(); 3994 ++p) 3995 symbol_count += (*p)->local_symbol_count(); 3996 3997 // Go from "upper bound" to "estimate." We overcount for two 3998 // reasons: we double-count symbols that occur in more than one 3999 // object file, and we count symbols that are dropped from the 4000 // output. Add it all together and assume we overcount by 100%. 4001 symbol_count /= 2; 4002 4003 // We assume all symbols will go into both the sympool and dynpool. 4004 this->sympool_.reserve(symbol_count); 4005 this->dynpool_.reserve(symbol_count); 4006 4007 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 4008 p != input_objects->relobj_end(); 4009 ++p) 4010 { 4011 Task_lock_obj<Object> tlo(task, *p); 4012 (*p)->count_local_symbols(&this->sympool_, &this->dynpool_); 4013 } 4014 } 4015 4016 // Create the symbol table sections. Here we also set the final 4017 // values of the symbols. At this point all the loadable sections are 4018 // fully laid out. SHNUM is the number of sections so far. 4019 4020 void 4021 Layout::create_symtab_sections(const Input_objects* input_objects, 4022 Symbol_table* symtab, 4023 unsigned int shnum, 4024 off_t* poff) 4025 { 4026 int symsize; 4027 unsigned int align; 4028 if (parameters->target().get_size() == 32) 4029 { 4030 symsize = elfcpp::Elf_sizes<32>::sym_size; 4031 align = 4; 4032 } 4033 else if (parameters->target().get_size() == 64) 4034 { 4035 symsize = elfcpp::Elf_sizes<64>::sym_size; 4036 align = 8; 4037 } 4038 else 4039 gold_unreachable(); 4040 4041 // Compute file offsets relative to the start of the symtab section. 4042 off_t off = 0; 4043 4044 // Save space for the dummy symbol at the start of the section. We 4045 // never bother to write this out--it will just be left as zero. 4046 off += symsize; 4047 unsigned int local_symbol_index = 1; 4048 4049 // Add STT_SECTION symbols for each Output section which needs one. 4050 for (Section_list::iterator p = this->section_list_.begin(); 4051 p != this->section_list_.end(); 4052 ++p) 4053 { 4054 if (!(*p)->needs_symtab_index()) 4055 (*p)->set_symtab_index(-1U); 4056 else 4057 { 4058 (*p)->set_symtab_index(local_symbol_index); 4059 ++local_symbol_index; 4060 off += symsize; 4061 } 4062 } 4063 4064 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 4065 p != input_objects->relobj_end(); 4066 ++p) 4067 { 4068 unsigned int index = (*p)->finalize_local_symbols(local_symbol_index, 4069 off, symtab); 4070 off += (index - local_symbol_index) * symsize; 4071 local_symbol_index = index; 4072 } 4073 4074 unsigned int local_symcount = local_symbol_index; 4075 gold_assert(static_cast<off_t>(local_symcount * symsize) == off); 4076 4077 off_t dynoff; 4078 size_t dyn_global_index; 4079 size_t dyncount; 4080 if (this->dynsym_section_ == NULL) 4081 { 4082 dynoff = 0; 4083 dyn_global_index = 0; 4084 dyncount = 0; 4085 } 4086 else 4087 { 4088 dyn_global_index = this->dynsym_section_->info(); 4089 off_t locsize = dyn_global_index * this->dynsym_section_->entsize(); 4090 dynoff = this->dynsym_section_->offset() + locsize; 4091 dyncount = (this->dynsym_section_->data_size() - locsize) / symsize; 4092 gold_assert(static_cast<off_t>(dyncount * symsize) 4093 == this->dynsym_section_->data_size() - locsize); 4094 } 4095 4096 off_t global_off = off; 4097 off = symtab->finalize(off, dynoff, dyn_global_index, dyncount, 4098 &this->sympool_, &local_symcount); 4099 4100 if (!parameters->options().strip_all()) 4101 { 4102 this->sympool_.set_string_offsets(); 4103 4104 const char* symtab_name = this->namepool_.add(".symtab", false, NULL); 4105 Output_section* osymtab = this->make_output_section(symtab_name, 4106 elfcpp::SHT_SYMTAB, 4107 0, ORDER_INVALID, 4108 false); 4109 this->symtab_section_ = osymtab; 4110 4111 Output_section_data* pos = new Output_data_fixed_space(off, align, 4112 "** symtab"); 4113 osymtab->add_output_section_data(pos); 4114 4115 // We generate a .symtab_shndx section if we have more than 4116 // SHN_LORESERVE sections. Technically it is possible that we 4117 // don't need one, because it is possible that there are no 4118 // symbols in any of sections with indexes larger than 4119 // SHN_LORESERVE. That is probably unusual, though, and it is 4120 // easier to always create one than to compute section indexes 4121 // twice (once here, once when writing out the symbols). 4122 if (shnum >= elfcpp::SHN_LORESERVE) 4123 { 4124 const char* symtab_xindex_name = this->namepool_.add(".symtab_shndx", 4125 false, NULL); 4126 Output_section* osymtab_xindex = 4127 this->make_output_section(symtab_xindex_name, 4128 elfcpp::SHT_SYMTAB_SHNDX, 0, 4129 ORDER_INVALID, false); 4130 4131 size_t symcount = off / symsize; 4132 this->symtab_xindex_ = new Output_symtab_xindex(symcount); 4133 4134 osymtab_xindex->add_output_section_data(this->symtab_xindex_); 4135 4136 osymtab_xindex->set_link_section(osymtab); 4137 osymtab_xindex->set_addralign(4); 4138 osymtab_xindex->set_entsize(4); 4139 4140 osymtab_xindex->set_after_input_sections(); 4141 4142 // This tells the driver code to wait until the symbol table 4143 // has written out before writing out the postprocessing 4144 // sections, including the .symtab_shndx section. 4145 this->any_postprocessing_sections_ = true; 4146 } 4147 4148 const char* strtab_name = this->namepool_.add(".strtab", false, NULL); 4149 Output_section* ostrtab = this->make_output_section(strtab_name, 4150 elfcpp::SHT_STRTAB, 4151 0, ORDER_INVALID, 4152 false); 4153 4154 Output_section_data* pstr = new Output_data_strtab(&this->sympool_); 4155 ostrtab->add_output_section_data(pstr); 4156 4157 off_t symtab_off; 4158 if (!parameters->incremental_update()) 4159 symtab_off = align_address(*poff, align); 4160 else 4161 { 4162 symtab_off = this->allocate(off, align, *poff); 4163 if (off == -1) 4164 gold_fallback(_("out of patch space for symbol table; " 4165 "relink with --incremental-full")); 4166 gold_debug(DEBUG_INCREMENTAL, 4167 "create_symtab_sections: %08lx %08lx .symtab", 4168 static_cast<long>(symtab_off), 4169 static_cast<long>(off)); 4170 } 4171 4172 symtab->set_file_offset(symtab_off + global_off); 4173 osymtab->set_file_offset(symtab_off); 4174 osymtab->finalize_data_size(); 4175 osymtab->set_link_section(ostrtab); 4176 osymtab->set_info(local_symcount); 4177 osymtab->set_entsize(symsize); 4178 4179 if (symtab_off + off > *poff) 4180 *poff = symtab_off + off; 4181 } 4182 } 4183 4184 // Create the .shstrtab section, which holds the names of the 4185 // sections. At the time this is called, we have created all the 4186 // output sections except .shstrtab itself. 4187 4188 Output_section* 4189 Layout::create_shstrtab() 4190 { 4191 // FIXME: We don't need to create a .shstrtab section if we are 4192 // stripping everything. 4193 4194 const char* name = this->namepool_.add(".shstrtab", false, NULL); 4195 4196 Output_section* os = this->make_output_section(name, elfcpp::SHT_STRTAB, 0, 4197 ORDER_INVALID, false); 4198 4199 if (strcmp(parameters->options().compress_debug_sections(), "none") != 0) 4200 { 4201 // We can't write out this section until we've set all the 4202 // section names, and we don't set the names of compressed 4203 // output sections until relocations are complete. FIXME: With 4204 // the current names we use, this is unnecessary. 4205 os->set_after_input_sections(); 4206 } 4207 4208 Output_section_data* posd = new Output_data_strtab(&this->namepool_); 4209 os->add_output_section_data(posd); 4210 4211 return os; 4212 } 4213 4214 // Create the section headers. SIZE is 32 or 64. OFF is the file 4215 // offset. 4216 4217 void 4218 Layout::create_shdrs(const Output_section* shstrtab_section, off_t* poff) 4219 { 4220 Output_section_headers* oshdrs; 4221 oshdrs = new Output_section_headers(this, 4222 &this->segment_list_, 4223 &this->section_list_, 4224 &this->unattached_section_list_, 4225 &this->namepool_, 4226 shstrtab_section); 4227 off_t off; 4228 if (!parameters->incremental_update()) 4229 off = align_address(*poff, oshdrs->addralign()); 4230 else 4231 { 4232 oshdrs->pre_finalize_data_size(); 4233 off = this->allocate(oshdrs->data_size(), oshdrs->addralign(), *poff); 4234 if (off == -1) 4235 gold_fallback(_("out of patch space for section header table; " 4236 "relink with --incremental-full")); 4237 gold_debug(DEBUG_INCREMENTAL, 4238 "create_shdrs: %08lx %08lx (section header table)", 4239 static_cast<long>(off), 4240 static_cast<long>(off + oshdrs->data_size())); 4241 } 4242 oshdrs->set_address_and_file_offset(0, off); 4243 off += oshdrs->data_size(); 4244 if (off > *poff) 4245 *poff = off; 4246 this->section_headers_ = oshdrs; 4247 } 4248 4249 // Count the allocated sections. 4250 4251 size_t 4252 Layout::allocated_output_section_count() const 4253 { 4254 size_t section_count = 0; 4255 for (Segment_list::const_iterator p = this->segment_list_.begin(); 4256 p != this->segment_list_.end(); 4257 ++p) 4258 section_count += (*p)->output_section_count(); 4259 return section_count; 4260 } 4261 4262 // Create the dynamic symbol table. 4263 4264 void 4265 Layout::create_dynamic_symtab(const Input_objects* input_objects, 4266 Symbol_table* symtab, 4267 Output_section** pdynstr, 4268 unsigned int* plocal_dynamic_count, 4269 std::vector<Symbol*>* pdynamic_symbols, 4270 Versions* pversions) 4271 { 4272 // Count all the symbols in the dynamic symbol table, and set the 4273 // dynamic symbol indexes. 4274 4275 // Skip symbol 0, which is always all zeroes. 4276 unsigned int index = 1; 4277 4278 // Add STT_SECTION symbols for each Output section which needs one. 4279 for (Section_list::iterator p = this->section_list_.begin(); 4280 p != this->section_list_.end(); 4281 ++p) 4282 { 4283 if (!(*p)->needs_dynsym_index()) 4284 (*p)->set_dynsym_index(-1U); 4285 else 4286 { 4287 (*p)->set_dynsym_index(index); 4288 ++index; 4289 } 4290 } 4291 4292 // Count the local symbols that need to go in the dynamic symbol table, 4293 // and set the dynamic symbol indexes. 4294 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 4295 p != input_objects->relobj_end(); 4296 ++p) 4297 { 4298 unsigned int new_index = (*p)->set_local_dynsym_indexes(index); 4299 index = new_index; 4300 } 4301 4302 unsigned int local_symcount = index; 4303 *plocal_dynamic_count = local_symcount; 4304 4305 index = symtab->set_dynsym_indexes(index, pdynamic_symbols, 4306 &this->dynpool_, pversions); 4307 4308 int symsize; 4309 unsigned int align; 4310 const int size = parameters->target().get_size(); 4311 if (size == 32) 4312 { 4313 symsize = elfcpp::Elf_sizes<32>::sym_size; 4314 align = 4; 4315 } 4316 else if (size == 64) 4317 { 4318 symsize = elfcpp::Elf_sizes<64>::sym_size; 4319 align = 8; 4320 } 4321 else 4322 gold_unreachable(); 4323 4324 // Create the dynamic symbol table section. 4325 4326 Output_section* dynsym = this->choose_output_section(NULL, ".dynsym", 4327 elfcpp::SHT_DYNSYM, 4328 elfcpp::SHF_ALLOC, 4329 false, 4330 ORDER_DYNAMIC_LINKER, 4331 false); 4332 4333 // Check for NULL as a linker script may discard .dynsym. 4334 if (dynsym != NULL) 4335 { 4336 Output_section_data* odata = new Output_data_fixed_space(index * symsize, 4337 align, 4338 "** dynsym"); 4339 dynsym->add_output_section_data(odata); 4340 4341 dynsym->set_info(local_symcount); 4342 dynsym->set_entsize(symsize); 4343 dynsym->set_addralign(align); 4344 4345 this->dynsym_section_ = dynsym; 4346 } 4347 4348 Output_data_dynamic* const odyn = this->dynamic_data_; 4349 if (odyn != NULL) 4350 { 4351 odyn->add_section_address(elfcpp::DT_SYMTAB, dynsym); 4352 odyn->add_constant(elfcpp::DT_SYMENT, symsize); 4353 } 4354 4355 // If there are more than SHN_LORESERVE allocated sections, we 4356 // create a .dynsym_shndx section. It is possible that we don't 4357 // need one, because it is possible that there are no dynamic 4358 // symbols in any of the sections with indexes larger than 4359 // SHN_LORESERVE. This is probably unusual, though, and at this 4360 // time we don't know the actual section indexes so it is 4361 // inconvenient to check. 4362 if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE) 4363 { 4364 Output_section* dynsym_xindex = 4365 this->choose_output_section(NULL, ".dynsym_shndx", 4366 elfcpp::SHT_SYMTAB_SHNDX, 4367 elfcpp::SHF_ALLOC, 4368 false, ORDER_DYNAMIC_LINKER, false); 4369 4370 if (dynsym_xindex != NULL) 4371 { 4372 this->dynsym_xindex_ = new Output_symtab_xindex(index); 4373 4374 dynsym_xindex->add_output_section_data(this->dynsym_xindex_); 4375 4376 dynsym_xindex->set_link_section(dynsym); 4377 dynsym_xindex->set_addralign(4); 4378 dynsym_xindex->set_entsize(4); 4379 4380 dynsym_xindex->set_after_input_sections(); 4381 4382 // This tells the driver code to wait until the symbol table 4383 // has written out before writing out the postprocessing 4384 // sections, including the .dynsym_shndx section. 4385 this->any_postprocessing_sections_ = true; 4386 } 4387 } 4388 4389 // Create the dynamic string table section. 4390 4391 Output_section* dynstr = this->choose_output_section(NULL, ".dynstr", 4392 elfcpp::SHT_STRTAB, 4393 elfcpp::SHF_ALLOC, 4394 false, 4395 ORDER_DYNAMIC_LINKER, 4396 false); 4397 *pdynstr = dynstr; 4398 if (dynstr != NULL) 4399 { 4400 Output_section_data* strdata = new Output_data_strtab(&this->dynpool_); 4401 dynstr->add_output_section_data(strdata); 4402 4403 if (dynsym != NULL) 4404 dynsym->set_link_section(dynstr); 4405 if (this->dynamic_section_ != NULL) 4406 this->dynamic_section_->set_link_section(dynstr); 4407 4408 if (odyn != NULL) 4409 { 4410 odyn->add_section_address(elfcpp::DT_STRTAB, dynstr); 4411 odyn->add_section_size(elfcpp::DT_STRSZ, dynstr); 4412 } 4413 } 4414 4415 // Create the hash tables. The Gnu-style hash table must be 4416 // built first, because it changes the order of the symbols 4417 // in the dynamic symbol table. 4418 4419 if (strcmp(parameters->options().hash_style(), "gnu") == 0 4420 || strcmp(parameters->options().hash_style(), "both") == 0) 4421 { 4422 unsigned char* phash; 4423 unsigned int hashlen; 4424 Dynobj::create_gnu_hash_table(*pdynamic_symbols, local_symcount, 4425 &phash, &hashlen); 4426 4427 Output_section* hashsec = 4428 this->choose_output_section(NULL, ".gnu.hash", elfcpp::SHT_GNU_HASH, 4429 elfcpp::SHF_ALLOC, false, 4430 ORDER_DYNAMIC_LINKER, false); 4431 4432 Output_section_data* hashdata = new Output_data_const_buffer(phash, 4433 hashlen, 4434 align, 4435 "** hash"); 4436 if (hashsec != NULL && hashdata != NULL) 4437 hashsec->add_output_section_data(hashdata); 4438 4439 if (hashsec != NULL) 4440 { 4441 if (dynsym != NULL) 4442 hashsec->set_link_section(dynsym); 4443 4444 // For a 64-bit target, the entries in .gnu.hash do not have 4445 // a uniform size, so we only set the entry size for a 4446 // 32-bit target. 4447 if (parameters->target().get_size() == 32) 4448 hashsec->set_entsize(4); 4449 4450 if (odyn != NULL) 4451 odyn->add_section_address(elfcpp::DT_GNU_HASH, hashsec); 4452 } 4453 } 4454 4455 if (strcmp(parameters->options().hash_style(), "sysv") == 0 4456 || strcmp(parameters->options().hash_style(), "both") == 0) 4457 { 4458 unsigned char* phash; 4459 unsigned int hashlen; 4460 Dynobj::create_elf_hash_table(*pdynamic_symbols, local_symcount, 4461 &phash, &hashlen); 4462 4463 Output_section* hashsec = 4464 this->choose_output_section(NULL, ".hash", elfcpp::SHT_HASH, 4465 elfcpp::SHF_ALLOC, false, 4466 ORDER_DYNAMIC_LINKER, false); 4467 4468 Output_section_data* hashdata = new Output_data_const_buffer(phash, 4469 hashlen, 4470 align, 4471 "** hash"); 4472 if (hashsec != NULL && hashdata != NULL) 4473 hashsec->add_output_section_data(hashdata); 4474 4475 if (hashsec != NULL) 4476 { 4477 if (dynsym != NULL) 4478 hashsec->set_link_section(dynsym); 4479 hashsec->set_entsize(parameters->target().hash_entry_size() / 8); 4480 } 4481 4482 if (odyn != NULL) 4483 odyn->add_section_address(elfcpp::DT_HASH, hashsec); 4484 } 4485 } 4486 4487 // Assign offsets to each local portion of the dynamic symbol table. 4488 4489 void 4490 Layout::assign_local_dynsym_offsets(const Input_objects* input_objects) 4491 { 4492 Output_section* dynsym = this->dynsym_section_; 4493 if (dynsym == NULL) 4494 return; 4495 4496 off_t off = dynsym->offset(); 4497 4498 // Skip the dummy symbol at the start of the section. 4499 off += dynsym->entsize(); 4500 4501 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 4502 p != input_objects->relobj_end(); 4503 ++p) 4504 { 4505 unsigned int count = (*p)->set_local_dynsym_offset(off); 4506 off += count * dynsym->entsize(); 4507 } 4508 } 4509 4510 // Create the version sections. 4511 4512 void 4513 Layout::create_version_sections(const Versions* versions, 4514 const Symbol_table* symtab, 4515 unsigned int local_symcount, 4516 const std::vector<Symbol*>& dynamic_symbols, 4517 const Output_section* dynstr) 4518 { 4519 if (!versions->any_defs() && !versions->any_needs()) 4520 return; 4521 4522 switch (parameters->size_and_endianness()) 4523 { 4524 #ifdef HAVE_TARGET_32_LITTLE 4525 case Parameters::TARGET_32_LITTLE: 4526 this->sized_create_version_sections<32, false>(versions, symtab, 4527 local_symcount, 4528 dynamic_symbols, dynstr); 4529 break; 4530 #endif 4531 #ifdef HAVE_TARGET_32_BIG 4532 case Parameters::TARGET_32_BIG: 4533 this->sized_create_version_sections<32, true>(versions, symtab, 4534 local_symcount, 4535 dynamic_symbols, dynstr); 4536 break; 4537 #endif 4538 #ifdef HAVE_TARGET_64_LITTLE 4539 case Parameters::TARGET_64_LITTLE: 4540 this->sized_create_version_sections<64, false>(versions, symtab, 4541 local_symcount, 4542 dynamic_symbols, dynstr); 4543 break; 4544 #endif 4545 #ifdef HAVE_TARGET_64_BIG 4546 case Parameters::TARGET_64_BIG: 4547 this->sized_create_version_sections<64, true>(versions, symtab, 4548 local_symcount, 4549 dynamic_symbols, dynstr); 4550 break; 4551 #endif 4552 default: 4553 gold_unreachable(); 4554 } 4555 } 4556 4557 // Create the version sections, sized version. 4558 4559 template<int size, bool big_endian> 4560 void 4561 Layout::sized_create_version_sections( 4562 const Versions* versions, 4563 const Symbol_table* symtab, 4564 unsigned int local_symcount, 4565 const std::vector<Symbol*>& dynamic_symbols, 4566 const Output_section* dynstr) 4567 { 4568 Output_section* vsec = this->choose_output_section(NULL, ".gnu.version", 4569 elfcpp::SHT_GNU_versym, 4570 elfcpp::SHF_ALLOC, 4571 false, 4572 ORDER_DYNAMIC_LINKER, 4573 false); 4574 4575 // Check for NULL since a linker script may discard this section. 4576 if (vsec != NULL) 4577 { 4578 unsigned char* vbuf; 4579 unsigned int vsize; 4580 versions->symbol_section_contents<size, big_endian>(symtab, 4581 &this->dynpool_, 4582 local_symcount, 4583 dynamic_symbols, 4584 &vbuf, &vsize); 4585 4586 Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2, 4587 "** versions"); 4588 4589 vsec->add_output_section_data(vdata); 4590 vsec->set_entsize(2); 4591 vsec->set_link_section(this->dynsym_section_); 4592 } 4593 4594 Output_data_dynamic* const odyn = this->dynamic_data_; 4595 if (odyn != NULL && vsec != NULL) 4596 odyn->add_section_address(elfcpp::DT_VERSYM, vsec); 4597 4598 if (versions->any_defs()) 4599 { 4600 Output_section* vdsec; 4601 vdsec = this->choose_output_section(NULL, ".gnu.version_d", 4602 elfcpp::SHT_GNU_verdef, 4603 elfcpp::SHF_ALLOC, 4604 false, ORDER_DYNAMIC_LINKER, false); 4605 4606 if (vdsec != NULL) 4607 { 4608 unsigned char* vdbuf; 4609 unsigned int vdsize; 4610 unsigned int vdentries; 4611 versions->def_section_contents<size, big_endian>(&this->dynpool_, 4612 &vdbuf, &vdsize, 4613 &vdentries); 4614 4615 Output_section_data* vddata = 4616 new Output_data_const_buffer(vdbuf, vdsize, 4, "** version defs"); 4617 4618 vdsec->add_output_section_data(vddata); 4619 vdsec->set_link_section(dynstr); 4620 vdsec->set_info(vdentries); 4621 4622 if (odyn != NULL) 4623 { 4624 odyn->add_section_address(elfcpp::DT_VERDEF, vdsec); 4625 odyn->add_constant(elfcpp::DT_VERDEFNUM, vdentries); 4626 } 4627 } 4628 } 4629 4630 if (versions->any_needs()) 4631 { 4632 Output_section* vnsec; 4633 vnsec = this->choose_output_section(NULL, ".gnu.version_r", 4634 elfcpp::SHT_GNU_verneed, 4635 elfcpp::SHF_ALLOC, 4636 false, ORDER_DYNAMIC_LINKER, false); 4637 4638 if (vnsec != NULL) 4639 { 4640 unsigned char* vnbuf; 4641 unsigned int vnsize; 4642 unsigned int vnentries; 4643 versions->need_section_contents<size, big_endian>(&this->dynpool_, 4644 &vnbuf, &vnsize, 4645 &vnentries); 4646 4647 Output_section_data* vndata = 4648 new Output_data_const_buffer(vnbuf, vnsize, 4, "** version refs"); 4649 4650 vnsec->add_output_section_data(vndata); 4651 vnsec->set_link_section(dynstr); 4652 vnsec->set_info(vnentries); 4653 4654 if (odyn != NULL) 4655 { 4656 odyn->add_section_address(elfcpp::DT_VERNEED, vnsec); 4657 odyn->add_constant(elfcpp::DT_VERNEEDNUM, vnentries); 4658 } 4659 } 4660 } 4661 } 4662 4663 // Create the .interp section and PT_INTERP segment. 4664 4665 void 4666 Layout::create_interp(const Target* target) 4667 { 4668 gold_assert(this->interp_segment_ == NULL); 4669 4670 const char* interp = parameters->options().dynamic_linker(); 4671 if (interp == NULL) 4672 { 4673 interp = target->dynamic_linker(); 4674 gold_assert(interp != NULL); 4675 } 4676 4677 size_t len = strlen(interp) + 1; 4678 4679 Output_section_data* odata = new Output_data_const(interp, len, 1); 4680 4681 Output_section* osec = this->choose_output_section(NULL, ".interp", 4682 elfcpp::SHT_PROGBITS, 4683 elfcpp::SHF_ALLOC, 4684 false, ORDER_INTERP, 4685 false); 4686 if (osec != NULL) 4687 osec->add_output_section_data(odata); 4688 } 4689 4690 // Add dynamic tags for the PLT and the dynamic relocs. This is 4691 // called by the target-specific code. This does nothing if not doing 4692 // a dynamic link. 4693 4694 // USE_REL is true for REL relocs rather than RELA relocs. 4695 4696 // If PLT_GOT is not NULL, then DT_PLTGOT points to it. 4697 4698 // If PLT_REL is not NULL, it is used for DT_PLTRELSZ, and DT_JMPREL, 4699 // and we also set DT_PLTREL. We use PLT_REL's output section, since 4700 // some targets have multiple reloc sections in PLT_REL. 4701 4702 // If DYN_REL is not NULL, it is used for DT_REL/DT_RELA, 4703 // DT_RELSZ/DT_RELASZ, DT_RELENT/DT_RELAENT. Again we use the output 4704 // section. 4705 4706 // If ADD_DEBUG is true, we add a DT_DEBUG entry when generating an 4707 // executable. 4708 4709 void 4710 Layout::add_target_dynamic_tags(bool use_rel, const Output_data* plt_got, 4711 const Output_data* plt_rel, 4712 const Output_data_reloc_generic* dyn_rel, 4713 bool add_debug, bool dynrel_includes_plt, 4714 const Output_data_reloc_generic* dyn_relr) 4715 { 4716 Output_data_dynamic* odyn = this->dynamic_data_; 4717 if (odyn == NULL) 4718 return; 4719 4720 if (plt_got != NULL && plt_got->output_section() != NULL) 4721 odyn->add_section_address(elfcpp::DT_PLTGOT, plt_got); 4722 4723 if (plt_rel != NULL && plt_rel->output_section() != NULL) 4724 { 4725 odyn->add_section_size(elfcpp::DT_PLTRELSZ, plt_rel->output_section()); 4726 odyn->add_section_address(elfcpp::DT_JMPREL, plt_rel->output_section()); 4727 odyn->add_constant(elfcpp::DT_PLTREL, 4728 use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA); 4729 } 4730 4731 if ((dyn_rel != NULL && dyn_rel->output_section() != NULL) 4732 || (dynrel_includes_plt 4733 && plt_rel != NULL 4734 && plt_rel->output_section() != NULL)) 4735 { 4736 bool have_dyn_rel = dyn_rel != NULL && dyn_rel->output_section() != NULL; 4737 bool have_plt_rel = plt_rel != NULL && plt_rel->output_section() != NULL; 4738 odyn->add_section_address(use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA, 4739 (have_dyn_rel 4740 ? dyn_rel->output_section() 4741 : plt_rel->output_section())); 4742 elfcpp::DT size_tag = use_rel ? elfcpp::DT_RELSZ : elfcpp::DT_RELASZ; 4743 if (have_dyn_rel && have_plt_rel && dynrel_includes_plt) 4744 odyn->add_section_size(size_tag, 4745 dyn_rel->output_section(), 4746 plt_rel->output_section()); 4747 else if (have_dyn_rel) 4748 odyn->add_section_size(size_tag, dyn_rel->output_section()); 4749 else 4750 odyn->add_section_size(size_tag, plt_rel->output_section()); 4751 const int size = parameters->target().get_size(); 4752 elfcpp::DT rel_tag; 4753 int rel_size; 4754 if (use_rel) 4755 { 4756 rel_tag = elfcpp::DT_RELENT; 4757 if (size == 32) 4758 rel_size = Reloc_types<elfcpp::SHT_REL, 32, false>::reloc_size; 4759 else if (size == 64) 4760 rel_size = Reloc_types<elfcpp::SHT_REL, 64, false>::reloc_size; 4761 else 4762 gold_unreachable(); 4763 } 4764 else 4765 { 4766 rel_tag = elfcpp::DT_RELAENT; 4767 if (size == 32) 4768 rel_size = Reloc_types<elfcpp::SHT_RELA, 32, false>::reloc_size; 4769 else if (size == 64) 4770 rel_size = Reloc_types<elfcpp::SHT_RELA, 64, false>::reloc_size; 4771 else 4772 gold_unreachable(); 4773 } 4774 odyn->add_constant(rel_tag, rel_size); 4775 4776 if (parameters->options().combreloc() && have_dyn_rel) 4777 { 4778 size_t c = dyn_rel->relative_reloc_count(); 4779 if (c > 0) 4780 odyn->add_constant((use_rel 4781 ? elfcpp::DT_RELCOUNT 4782 : elfcpp::DT_RELACOUNT), 4783 c); 4784 } 4785 } 4786 4787 if (dyn_relr != NULL && dyn_relr->output_section() != NULL) 4788 { 4789 const int size = parameters->target().get_size(); 4790 odyn->add_section_address(elfcpp::DT_RELR, dyn_relr->output_section()); 4791 odyn->add_section_size(elfcpp::DT_RELRSZ, dyn_relr->output_section()); 4792 odyn->add_constant(elfcpp::DT_RELRENT, size / 8); 4793 if (parameters->options().combreloc()) 4794 odyn->add_constant(elfcpp::DT_RELRCOUNT, 4795 dyn_relr->relative_reloc_count()); 4796 } 4797 4798 if (add_debug && !parameters->options().shared()) 4799 { 4800 // The value of the DT_DEBUG tag is filled in by the dynamic 4801 // linker at run time, and used by the debugger. 4802 odyn->add_constant(elfcpp::DT_DEBUG, 0); 4803 } 4804 } 4805 4806 void 4807 Layout::add_target_specific_dynamic_tag(elfcpp::DT tag, unsigned int val) 4808 { 4809 Output_data_dynamic* odyn = this->dynamic_data_; 4810 if (odyn == NULL) 4811 return; 4812 odyn->add_constant(tag, val); 4813 } 4814 4815 // Finish the .dynamic section and PT_DYNAMIC segment. 4816 4817 void 4818 Layout::finish_dynamic_section(const Input_objects* input_objects, 4819 const Symbol_table* symtab) 4820 { 4821 if (!this->script_options_->saw_phdrs_clause() 4822 && this->dynamic_section_ != NULL) 4823 { 4824 Output_segment* oseg = this->make_output_segment(elfcpp::PT_DYNAMIC, 4825 (elfcpp::PF_R 4826 | elfcpp::PF_W)); 4827 oseg->add_output_section_to_nonload(this->dynamic_section_, 4828 elfcpp::PF_R | elfcpp::PF_W); 4829 } 4830 4831 Output_data_dynamic* const odyn = this->dynamic_data_; 4832 if (odyn == NULL) 4833 return; 4834 4835 for (Input_objects::Dynobj_iterator p = input_objects->dynobj_begin(); 4836 p != input_objects->dynobj_end(); 4837 ++p) 4838 { 4839 if (!(*p)->is_needed() && (*p)->as_needed()) 4840 { 4841 // This dynamic object was linked with --as-needed, but it 4842 // is not needed. 4843 continue; 4844 } 4845 4846 odyn->add_string(elfcpp::DT_NEEDED, (*p)->soname()); 4847 } 4848 4849 if (parameters->options().shared()) 4850 { 4851 const char* soname = parameters->options().soname(); 4852 if (soname != NULL) 4853 odyn->add_string(elfcpp::DT_SONAME, soname); 4854 } 4855 4856 Symbol* sym = symtab->lookup(parameters->options().init()); 4857 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj()) 4858 odyn->add_symbol(elfcpp::DT_INIT, sym); 4859 4860 sym = symtab->lookup(parameters->options().fini()); 4861 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj()) 4862 odyn->add_symbol(elfcpp::DT_FINI, sym); 4863 4864 // Look for .init_array, .preinit_array and .fini_array by checking 4865 // section types. 4866 for(Layout::Section_list::const_iterator p = this->section_list_.begin(); 4867 p != this->section_list_.end(); 4868 ++p) 4869 switch((*p)->type()) 4870 { 4871 case elfcpp::SHT_FINI_ARRAY: 4872 odyn->add_section_address(elfcpp::DT_FINI_ARRAY, *p); 4873 odyn->add_section_size(elfcpp::DT_FINI_ARRAYSZ, *p); 4874 break; 4875 case elfcpp::SHT_INIT_ARRAY: 4876 odyn->add_section_address(elfcpp::DT_INIT_ARRAY, *p); 4877 odyn->add_section_size(elfcpp::DT_INIT_ARRAYSZ, *p); 4878 break; 4879 case elfcpp::SHT_PREINIT_ARRAY: 4880 odyn->add_section_address(elfcpp::DT_PREINIT_ARRAY, *p); 4881 odyn->add_section_size(elfcpp::DT_PREINIT_ARRAYSZ, *p); 4882 break; 4883 default: 4884 break; 4885 } 4886 4887 // Add a DT_RPATH entry if needed. 4888 const General_options::Dir_list& rpath(parameters->options().rpath()); 4889 if (!rpath.empty()) 4890 { 4891 std::string rpath_val; 4892 for (General_options::Dir_list::const_iterator p = rpath.begin(); 4893 p != rpath.end(); 4894 ++p) 4895 { 4896 if (rpath_val.empty()) 4897 rpath_val = p->name(); 4898 else 4899 { 4900 // Eliminate duplicates. 4901 General_options::Dir_list::const_iterator q; 4902 for (q = rpath.begin(); q != p; ++q) 4903 if (q->name() == p->name()) 4904 break; 4905 if (q == p) 4906 { 4907 rpath_val += ':'; 4908 rpath_val += p->name(); 4909 } 4910 } 4911 } 4912 4913 if (!parameters->options().enable_new_dtags()) 4914 odyn->add_string(elfcpp::DT_RPATH, rpath_val); 4915 else 4916 odyn->add_string(elfcpp::DT_RUNPATH, rpath_val); 4917 } 4918 4919 // Look for text segments that have dynamic relocations. 4920 bool have_textrel = false; 4921 if (!this->script_options_->saw_sections_clause()) 4922 { 4923 for (Segment_list::const_iterator p = this->segment_list_.begin(); 4924 p != this->segment_list_.end(); 4925 ++p) 4926 { 4927 if ((*p)->type() == elfcpp::PT_LOAD 4928 && ((*p)->flags() & elfcpp::PF_W) == 0 4929 && (*p)->has_dynamic_reloc()) 4930 { 4931 have_textrel = true; 4932 break; 4933 } 4934 } 4935 } 4936 else 4937 { 4938 // We don't know the section -> segment mapping, so we are 4939 // conservative and just look for readonly sections with 4940 // relocations. If those sections wind up in writable segments, 4941 // then we have created an unnecessary DT_TEXTREL entry. 4942 for (Section_list::const_iterator p = this->section_list_.begin(); 4943 p != this->section_list_.end(); 4944 ++p) 4945 { 4946 if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0 4947 && ((*p)->flags() & elfcpp::SHF_WRITE) == 0 4948 && (*p)->has_dynamic_reloc()) 4949 { 4950 have_textrel = true; 4951 break; 4952 } 4953 } 4954 } 4955 4956 if (parameters->options().filter() != NULL) 4957 odyn->add_string(elfcpp::DT_FILTER, parameters->options().filter()); 4958 if (parameters->options().any_auxiliary()) 4959 { 4960 for (options::String_set::const_iterator p = 4961 parameters->options().auxiliary_begin(); 4962 p != parameters->options().auxiliary_end(); 4963 ++p) 4964 odyn->add_string(elfcpp::DT_AUXILIARY, *p); 4965 } 4966 4967 // Add a DT_FLAGS entry if necessary. 4968 unsigned int flags = 0; 4969 if (have_textrel) 4970 { 4971 // Add a DT_TEXTREL for compatibility with older loaders. 4972 odyn->add_constant(elfcpp::DT_TEXTREL, 0); 4973 flags |= elfcpp::DF_TEXTREL; 4974 4975 if (parameters->options().text()) 4976 gold_error(_("read-only segment has dynamic relocations")); 4977 else if (parameters->options().warn_shared_textrel() 4978 && parameters->options().shared()) 4979 gold_warning(_("shared library text segment is not shareable")); 4980 } 4981 if (parameters->options().shared() && this->has_static_tls()) 4982 flags |= elfcpp::DF_STATIC_TLS; 4983 if (parameters->options().origin()) 4984 flags |= elfcpp::DF_ORIGIN; 4985 if (parameters->options().Bsymbolic() 4986 && !parameters->options().have_dynamic_list()) 4987 { 4988 flags |= elfcpp::DF_SYMBOLIC; 4989 // Add DT_SYMBOLIC for compatibility with older loaders. 4990 odyn->add_constant(elfcpp::DT_SYMBOLIC, 0); 4991 } 4992 if (parameters->options().now()) 4993 flags |= elfcpp::DF_BIND_NOW; 4994 if (flags != 0) 4995 odyn->add_constant(elfcpp::DT_FLAGS, flags); 4996 4997 flags = 0; 4998 if (parameters->options().global()) 4999 flags |= elfcpp::DF_1_GLOBAL; 5000 if (parameters->options().initfirst()) 5001 flags |= elfcpp::DF_1_INITFIRST; 5002 if (parameters->options().interpose()) 5003 flags |= elfcpp::DF_1_INTERPOSE; 5004 if (parameters->options().loadfltr()) 5005 flags |= elfcpp::DF_1_LOADFLTR; 5006 if (parameters->options().nodefaultlib()) 5007 flags |= elfcpp::DF_1_NODEFLIB; 5008 if (parameters->options().nodelete()) 5009 flags |= elfcpp::DF_1_NODELETE; 5010 if (parameters->options().nodlopen()) 5011 flags |= elfcpp::DF_1_NOOPEN; 5012 if (parameters->options().nodump()) 5013 flags |= elfcpp::DF_1_NODUMP; 5014 if (!parameters->options().shared()) 5015 flags &= ~(elfcpp::DF_1_INITFIRST 5016 | elfcpp::DF_1_NODELETE 5017 | elfcpp::DF_1_NOOPEN); 5018 if (parameters->options().origin()) 5019 flags |= elfcpp::DF_1_ORIGIN; 5020 if (parameters->options().now()) 5021 flags |= elfcpp::DF_1_NOW; 5022 if (parameters->options().Bgroup()) 5023 flags |= elfcpp::DF_1_GROUP; 5024 if (flags != 0) 5025 odyn->add_constant(elfcpp::DT_FLAGS_1, flags); 5026 } 5027 5028 // Set the size of the _DYNAMIC symbol table to be the size of the 5029 // dynamic data. 5030 5031 void 5032 Layout::set_dynamic_symbol_size(const Symbol_table* symtab) 5033 { 5034 Output_data_dynamic* const odyn = this->dynamic_data_; 5035 if (odyn == NULL) 5036 return; 5037 odyn->finalize_data_size(); 5038 if (this->dynamic_symbol_ == NULL) 5039 return; 5040 off_t data_size = odyn->data_size(); 5041 const int size = parameters->target().get_size(); 5042 if (size == 32) 5043 symtab->get_sized_symbol<32>(this->dynamic_symbol_)->set_symsize(data_size); 5044 else if (size == 64) 5045 symtab->get_sized_symbol<64>(this->dynamic_symbol_)->set_symsize(data_size); 5046 else 5047 gold_unreachable(); 5048 } 5049 5050 // The mapping of input section name prefixes to output section names. 5051 // In some cases one prefix is itself a prefix of another prefix; in 5052 // such a case the longer prefix must come first. These prefixes are 5053 // based on the GNU linker default ELF linker script. 5054 5055 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 } 5056 #define MAPPING_INIT_EXACT(f, t) { f, 0, t, sizeof(t) - 1 } 5057 const Layout::Section_name_mapping Layout::section_name_mapping[] = 5058 { 5059 MAPPING_INIT(".text.", ".text"), 5060 MAPPING_INIT(".rodata.", ".rodata"), 5061 MAPPING_INIT(".data.rel.ro.local.", ".data.rel.ro.local"), 5062 MAPPING_INIT_EXACT(".data.rel.ro.local", ".data.rel.ro.local"), 5063 MAPPING_INIT(".data.rel.ro.", ".data.rel.ro"), 5064 MAPPING_INIT_EXACT(".data.rel.ro", ".data.rel.ro"), 5065 MAPPING_INIT(".data.", ".data"), 5066 MAPPING_INIT(".bss.", ".bss"), 5067 MAPPING_INIT(".tdata.", ".tdata"), 5068 MAPPING_INIT(".tbss.", ".tbss"), 5069 MAPPING_INIT(".init_array.", ".init_array"), 5070 MAPPING_INIT(".fini_array.", ".fini_array"), 5071 MAPPING_INIT(".sdata.", ".sdata"), 5072 MAPPING_INIT(".sbss.", ".sbss"), 5073 // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled 5074 // differently depending on whether it is creating a shared library. 5075 MAPPING_INIT(".sdata2.", ".sdata"), 5076 MAPPING_INIT(".sbss2.", ".sbss"), 5077 MAPPING_INIT(".lrodata.", ".lrodata"), 5078 MAPPING_INIT(".ldata.", ".ldata"), 5079 MAPPING_INIT(".lbss.", ".lbss"), 5080 MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"), 5081 MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"), 5082 MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"), 5083 MAPPING_INIT(".gnu.linkonce.t.", ".text"), 5084 MAPPING_INIT(".gnu.linkonce.r.", ".rodata"), 5085 MAPPING_INIT(".gnu.linkonce.d.", ".data"), 5086 MAPPING_INIT(".gnu.linkonce.b.", ".bss"), 5087 MAPPING_INIT(".gnu.linkonce.s.", ".sdata"), 5088 MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"), 5089 MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"), 5090 MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"), 5091 MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"), 5092 MAPPING_INIT(".gnu.linkonce.td.", ".tdata"), 5093 MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"), 5094 MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"), 5095 MAPPING_INIT(".gnu.linkonce.l.", ".ldata"), 5096 MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"), 5097 MAPPING_INIT(".ARM.extab", ".ARM.extab"), 5098 MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"), 5099 MAPPING_INIT(".ARM.exidx", ".ARM.exidx"), 5100 MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"), 5101 MAPPING_INIT("_function_patch_prologue.", "_function_patch_prologue"), 5102 MAPPING_INIT("_function_patch_epilogue.", "_function_patch_epilogue"), 5103 }; 5104 #undef MAPPING_INIT 5105 #undef MAPPING_INIT_EXACT 5106 5107 const int Layout::section_name_mapping_count = 5108 (sizeof(Layout::section_name_mapping) 5109 / sizeof(Layout::section_name_mapping[0])); 5110 5111 // Choose the output section name to use given an input section name. 5112 // Set *PLEN to the length of the name. *PLEN is initialized to the 5113 // length of NAME. 5114 5115 const char* 5116 Layout::output_section_name(const Relobj* relobj, const char* name, 5117 size_t* plen) 5118 { 5119 // gcc 4.3 generates the following sorts of section names when it 5120 // needs a section name specific to a function: 5121 // .text.FN 5122 // .rodata.FN 5123 // .sdata2.FN 5124 // .data.FN 5125 // .data.rel.FN 5126 // .data.rel.local.FN 5127 // .data.rel.ro.FN 5128 // .data.rel.ro.local.FN 5129 // .sdata.FN 5130 // .bss.FN 5131 // .sbss.FN 5132 // .tdata.FN 5133 // .tbss.FN 5134 5135 // The GNU linker maps all of those to the part before the .FN, 5136 // except that .data.rel.local.FN is mapped to .data, and 5137 // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections 5138 // beginning with .data.rel.ro.local are grouped together. 5139 5140 // For an anonymous namespace, the string FN can contain a '.'. 5141 5142 // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the 5143 // GNU linker maps to .rodata. 5144 5145 // The .data.rel.ro sections are used with -z relro. The sections 5146 // are recognized by name. We use the same names that the GNU 5147 // linker does for these sections. 5148 5149 // It is hard to handle this in a principled way, so we don't even 5150 // try. We use a table of mappings. If the input section name is 5151 // not found in the table, we simply use it as the output section 5152 // name. 5153 5154 const Section_name_mapping* psnm = section_name_mapping; 5155 for (int i = 0; i < section_name_mapping_count; ++i, ++psnm) 5156 { 5157 if (psnm->fromlen > 0) 5158 { 5159 if (strncmp(name, psnm->from, psnm->fromlen) == 0) 5160 { 5161 *plen = psnm->tolen; 5162 return psnm->to; 5163 } 5164 } 5165 else 5166 { 5167 if (strcmp(name, psnm->from) == 0) 5168 { 5169 *plen = psnm->tolen; 5170 return psnm->to; 5171 } 5172 } 5173 } 5174 5175 // As an additional complication, .ctors sections are output in 5176 // either .ctors or .init_array sections, and .dtors sections are 5177 // output in either .dtors or .fini_array sections. 5178 if (is_prefix_of(".ctors.", name) || is_prefix_of(".dtors.", name)) 5179 { 5180 if (parameters->options().ctors_in_init_array()) 5181 { 5182 *plen = 11; 5183 return name[1] == 'c' ? ".init_array" : ".fini_array"; 5184 } 5185 else 5186 { 5187 *plen = 6; 5188 return name[1] == 'c' ? ".ctors" : ".dtors"; 5189 } 5190 } 5191 if (parameters->options().ctors_in_init_array() 5192 && (strcmp(name, ".ctors") == 0 || strcmp(name, ".dtors") == 0)) 5193 { 5194 // To make .init_array/.fini_array work with gcc we must exclude 5195 // .ctors and .dtors sections from the crtbegin and crtend 5196 // files. 5197 if (relobj == NULL 5198 || (!Layout::match_file_name(relobj, "crtbegin") 5199 && !Layout::match_file_name(relobj, "crtend"))) 5200 { 5201 *plen = 11; 5202 return name[1] == 'c' ? ".init_array" : ".fini_array"; 5203 } 5204 } 5205 5206 return name; 5207 } 5208 5209 // Return true if RELOBJ is an input file whose base name matches 5210 // FILE_NAME. The base name must have an extension of ".o", and must 5211 // be exactly FILE_NAME.o or FILE_NAME, one character, ".o". This is 5212 // to match crtbegin.o as well as crtbeginS.o without getting confused 5213 // by other possibilities. Overall matching the file name this way is 5214 // a dreadful hack, but the GNU linker does it in order to better 5215 // support gcc, and we need to be compatible. 5216 5217 bool 5218 Layout::match_file_name(const Relobj* relobj, const char* match) 5219 { 5220 const std::string& file_name(relobj->name()); 5221 const char* base_name = lbasename(file_name.c_str()); 5222 size_t match_len = strlen(match); 5223 if (strncmp(base_name, match, match_len) != 0) 5224 return false; 5225 size_t base_len = strlen(base_name); 5226 if (base_len != match_len + 2 && base_len != match_len + 3) 5227 return false; 5228 return memcmp(base_name + base_len - 2, ".o", 2) == 0; 5229 } 5230 5231 // Check if a comdat group or .gnu.linkonce section with the given 5232 // NAME is selected for the link. If there is already a section, 5233 // *KEPT_SECTION is set to point to the existing section and the 5234 // function returns false. Otherwise, OBJECT, SHNDX, IS_COMDAT, and 5235 // IS_GROUP_NAME are recorded for this NAME in the layout object, 5236 // *KEPT_SECTION is set to the internal copy and the function returns 5237 // true. 5238 5239 bool 5240 Layout::find_or_add_kept_section(const std::string& name, 5241 Relobj* object, 5242 unsigned int shndx, 5243 bool is_comdat, 5244 bool is_group_name, 5245 Kept_section** kept_section) 5246 { 5247 // It's normal to see a couple of entries here, for the x86 thunk 5248 // sections. If we see more than a few, we're linking a C++ 5249 // program, and we resize to get more space to minimize rehashing. 5250 if (this->signatures_.size() > 4 5251 && !this->resized_signatures_) 5252 { 5253 reserve_unordered_map(&this->signatures_, 5254 this->number_of_input_files_ * 64); 5255 this->resized_signatures_ = true; 5256 } 5257 5258 Kept_section candidate; 5259 std::pair<Signatures::iterator, bool> ins = 5260 this->signatures_.insert(std::make_pair(name, candidate)); 5261 5262 if (kept_section != NULL) 5263 *kept_section = &ins.first->second; 5264 if (ins.second) 5265 { 5266 // This is the first time we've seen this signature. 5267 ins.first->second.set_object(object); 5268 ins.first->second.set_shndx(shndx); 5269 if (is_comdat) 5270 ins.first->second.set_is_comdat(); 5271 if (is_group_name) 5272 ins.first->second.set_is_group_name(); 5273 return true; 5274 } 5275 5276 // We have already seen this signature. 5277 5278 if (ins.first->second.is_group_name()) 5279 { 5280 // We've already seen a real section group with this signature. 5281 // If the kept group is from a plugin object, and we're in the 5282 // replacement phase, accept the new one as a replacement. 5283 if (ins.first->second.object() == NULL 5284 && parameters->options().plugins()->in_replacement_phase()) 5285 { 5286 ins.first->second.set_object(object); 5287 ins.first->second.set_shndx(shndx); 5288 return true; 5289 } 5290 return false; 5291 } 5292 else if (is_group_name) 5293 { 5294 // This is a real section group, and we've already seen a 5295 // linkonce section with this signature. Record that we've seen 5296 // a section group, and don't include this section group. 5297 ins.first->second.set_is_group_name(); 5298 return false; 5299 } 5300 else 5301 { 5302 // We've already seen a linkonce section and this is a linkonce 5303 // section. These don't block each other--this may be the same 5304 // symbol name with different section types. 5305 return true; 5306 } 5307 } 5308 5309 // Store the allocated sections into the section list. 5310 5311 void 5312 Layout::get_allocated_sections(Section_list* section_list) const 5313 { 5314 for (Section_list::const_iterator p = this->section_list_.begin(); 5315 p != this->section_list_.end(); 5316 ++p) 5317 if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0) 5318 section_list->push_back(*p); 5319 } 5320 5321 // Store the executable sections into the section list. 5322 5323 void 5324 Layout::get_executable_sections(Section_list* section_list) const 5325 { 5326 for (Section_list::const_iterator p = this->section_list_.begin(); 5327 p != this->section_list_.end(); 5328 ++p) 5329 if (((*p)->flags() & (elfcpp::SHF_ALLOC | elfcpp::SHF_EXECINSTR)) 5330 == (elfcpp::SHF_ALLOC | elfcpp::SHF_EXECINSTR)) 5331 section_list->push_back(*p); 5332 } 5333 5334 // Create an output segment. 5335 5336 Output_segment* 5337 Layout::make_output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags) 5338 { 5339 gold_assert(!parameters->options().relocatable()); 5340 Output_segment* oseg = new Output_segment(type, flags); 5341 this->segment_list_.push_back(oseg); 5342 5343 if (type == elfcpp::PT_TLS) 5344 this->tls_segment_ = oseg; 5345 else if (type == elfcpp::PT_GNU_RELRO) 5346 this->relro_segment_ = oseg; 5347 else if (type == elfcpp::PT_INTERP) 5348 this->interp_segment_ = oseg; 5349 5350 return oseg; 5351 } 5352 5353 // Return the file offset of the normal symbol table. 5354 5355 off_t 5356 Layout::symtab_section_offset() const 5357 { 5358 if (this->symtab_section_ != NULL) 5359 return this->symtab_section_->offset(); 5360 return 0; 5361 } 5362 5363 // Return the section index of the normal symbol table. It may have 5364 // been stripped by the -s/--strip-all option. 5365 5366 unsigned int 5367 Layout::symtab_section_shndx() const 5368 { 5369 if (this->symtab_section_ != NULL) 5370 return this->symtab_section_->out_shndx(); 5371 return 0; 5372 } 5373 5374 // Write out the Output_sections. Most won't have anything to write, 5375 // since most of the data will come from input sections which are 5376 // handled elsewhere. But some Output_sections do have Output_data. 5377 5378 void 5379 Layout::write_output_sections(Output_file* of) const 5380 { 5381 for (Section_list::const_iterator p = this->section_list_.begin(); 5382 p != this->section_list_.end(); 5383 ++p) 5384 { 5385 if (!(*p)->after_input_sections()) 5386 (*p)->write(of); 5387 } 5388 } 5389 5390 // Write out data not associated with a section or the symbol table. 5391 5392 void 5393 Layout::write_data(const Symbol_table* symtab, Output_file* of) const 5394 { 5395 if (!parameters->options().strip_all()) 5396 { 5397 const Output_section* symtab_section = this->symtab_section_; 5398 for (Section_list::const_iterator p = this->section_list_.begin(); 5399 p != this->section_list_.end(); 5400 ++p) 5401 { 5402 if ((*p)->needs_symtab_index()) 5403 { 5404 gold_assert(symtab_section != NULL); 5405 unsigned int index = (*p)->symtab_index(); 5406 gold_assert(index > 0 && index != -1U); 5407 off_t off = (symtab_section->offset() 5408 + index * symtab_section->entsize()); 5409 symtab->write_section_symbol(*p, this->symtab_xindex_, of, off); 5410 } 5411 } 5412 } 5413 5414 const Output_section* dynsym_section = this->dynsym_section_; 5415 for (Section_list::const_iterator p = this->section_list_.begin(); 5416 p != this->section_list_.end(); 5417 ++p) 5418 { 5419 if ((*p)->needs_dynsym_index()) 5420 { 5421 gold_assert(dynsym_section != NULL); 5422 unsigned int index = (*p)->dynsym_index(); 5423 gold_assert(index > 0 && index != -1U); 5424 off_t off = (dynsym_section->offset() 5425 + index * dynsym_section->entsize()); 5426 symtab->write_section_symbol(*p, this->dynsym_xindex_, of, off); 5427 } 5428 } 5429 5430 // Write out the Output_data which are not in an Output_section. 5431 for (Data_list::const_iterator p = this->special_output_list_.begin(); 5432 p != this->special_output_list_.end(); 5433 ++p) 5434 (*p)->write(of); 5435 5436 // Write out the Output_data which are not in an Output_section 5437 // and are regenerated in each iteration of relaxation. 5438 for (Data_list::const_iterator p = this->relax_output_list_.begin(); 5439 p != this->relax_output_list_.end(); 5440 ++p) 5441 (*p)->write(of); 5442 } 5443 5444 // Write out the Output_sections which can only be written after the 5445 // input sections are complete. 5446 5447 void 5448 Layout::write_sections_after_input_sections(Output_file* of) 5449 { 5450 // Determine the final section offsets, and thus the final output 5451 // file size. Note we finalize the .shstrab last, to allow the 5452 // after_input_section sections to modify their section-names before 5453 // writing. 5454 if (this->any_postprocessing_sections_) 5455 { 5456 off_t off = this->output_file_size_; 5457 off = this->set_section_offsets(off, POSTPROCESSING_SECTIONS_PASS); 5458 5459 // Now that we've finalized the names, we can finalize the shstrab. 5460 off = 5461 this->set_section_offsets(off, 5462 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS); 5463 5464 if (off > this->output_file_size_) 5465 { 5466 of->resize(off); 5467 this->output_file_size_ = off; 5468 } 5469 } 5470 5471 for (Section_list::const_iterator p = this->section_list_.begin(); 5472 p != this->section_list_.end(); 5473 ++p) 5474 { 5475 if ((*p)->after_input_sections()) 5476 (*p)->write(of); 5477 } 5478 5479 this->section_headers_->write(of); 5480 } 5481 5482 // If a tree-style build ID was requested, the parallel part of that computation 5483 // is already done, and the final hash-of-hashes is computed here. For other 5484 // types of build IDs, all the work is done here. 5485 5486 void 5487 Layout::write_build_id(Output_file* of, unsigned char* array_of_hashes, 5488 size_t size_of_hashes) const 5489 { 5490 if (this->build_id_note_ == NULL) 5491 return; 5492 5493 unsigned char* ov = of->get_output_view(this->build_id_note_->offset(), 5494 this->build_id_note_->data_size()); 5495 5496 if (array_of_hashes == NULL) 5497 { 5498 const size_t output_file_size = this->output_file_size(); 5499 const unsigned char* iv = of->get_input_view(0, output_file_size); 5500 const char* style = parameters->options().build_id(); 5501 5502 // If we get here with style == "tree" then the output must be 5503 // too small for chunking, and we use SHA-1 in that case. 5504 if ((strcmp(style, "sha1") == 0) || (strcmp(style, "tree") == 0)) 5505 sha1_buffer(reinterpret_cast<const char*>(iv), output_file_size, ov); 5506 else if (strcmp(style, "md5") == 0) 5507 md5_buffer(reinterpret_cast<const char*>(iv), output_file_size, ov); 5508 else 5509 gold_unreachable(); 5510 5511 of->free_input_view(0, output_file_size, iv); 5512 } 5513 else 5514 { 5515 // Non-overlapping substrings of the output file have been hashed. 5516 // Compute SHA-1 hash of the hashes. 5517 sha1_buffer(reinterpret_cast<const char*>(array_of_hashes), 5518 size_of_hashes, ov); 5519 delete[] array_of_hashes; 5520 } 5521 5522 of->write_output_view(this->build_id_note_->offset(), 5523 this->build_id_note_->data_size(), 5524 ov); 5525 } 5526 5527 // Write out a binary file. This is called after the link is 5528 // complete. IN is the temporary output file we used to generate the 5529 // ELF code. We simply walk through the segments, read them from 5530 // their file offset in IN, and write them to their load address in 5531 // the output file. FIXME: with a bit more work, we could support 5532 // S-records and/or Intel hex format here. 5533 5534 void 5535 Layout::write_binary(Output_file* in) const 5536 { 5537 gold_assert(parameters->options().oformat_enum() 5538 == General_options::OBJECT_FORMAT_BINARY); 5539 5540 // Get the size of the binary file. 5541 uint64_t max_load_address = 0; 5542 for (Segment_list::const_iterator p = this->segment_list_.begin(); 5543 p != this->segment_list_.end(); 5544 ++p) 5545 { 5546 if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0) 5547 { 5548 uint64_t max_paddr = (*p)->paddr() + (*p)->filesz(); 5549 if (max_paddr > max_load_address) 5550 max_load_address = max_paddr; 5551 } 5552 } 5553 5554 Output_file out(parameters->options().output_file_name()); 5555 out.open(max_load_address); 5556 5557 for (Segment_list::const_iterator p = this->segment_list_.begin(); 5558 p != this->segment_list_.end(); 5559 ++p) 5560 { 5561 if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0) 5562 { 5563 const unsigned char* vin = in->get_input_view((*p)->offset(), 5564 (*p)->filesz()); 5565 unsigned char* vout = out.get_output_view((*p)->paddr(), 5566 (*p)->filesz()); 5567 memcpy(vout, vin, (*p)->filesz()); 5568 out.write_output_view((*p)->paddr(), (*p)->filesz(), vout); 5569 in->free_input_view((*p)->offset(), (*p)->filesz(), vin); 5570 } 5571 } 5572 5573 out.close(); 5574 } 5575 5576 // Print the output sections to the map file. 5577 5578 void 5579 Layout::print_to_mapfile(Mapfile* mapfile) const 5580 { 5581 for (Segment_list::const_iterator p = this->segment_list_.begin(); 5582 p != this->segment_list_.end(); 5583 ++p) 5584 (*p)->print_sections_to_mapfile(mapfile); 5585 for (Section_list::const_iterator p = this->unattached_section_list_.begin(); 5586 p != this->unattached_section_list_.end(); 5587 ++p) 5588 (*p)->print_to_mapfile(mapfile); 5589 } 5590 5591 // Print statistical information to stderr. This is used for --stats. 5592 5593 void 5594 Layout::print_stats() const 5595 { 5596 this->namepool_.print_stats("section name pool"); 5597 this->sympool_.print_stats("output symbol name pool"); 5598 this->dynpool_.print_stats("dynamic name pool"); 5599 5600 for (Section_list::const_iterator p = this->section_list_.begin(); 5601 p != this->section_list_.end(); 5602 ++p) 5603 (*p)->print_merge_stats(); 5604 } 5605 5606 // Write_sections_task methods. 5607 5608 // We can always run this task. 5609 5610 Task_token* 5611 Write_sections_task::is_runnable() 5612 { 5613 return NULL; 5614 } 5615 5616 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER 5617 // when finished. 5618 5619 void 5620 Write_sections_task::locks(Task_locker* tl) 5621 { 5622 tl->add(this, this->output_sections_blocker_); 5623 if (this->input_sections_blocker_ != NULL) 5624 tl->add(this, this->input_sections_blocker_); 5625 tl->add(this, this->final_blocker_); 5626 } 5627 5628 // Run the task--write out the data. 5629 5630 void 5631 Write_sections_task::run(Workqueue*) 5632 { 5633 this->layout_->write_output_sections(this->of_); 5634 } 5635 5636 // Write_data_task methods. 5637 5638 // We can always run this task. 5639 5640 Task_token* 5641 Write_data_task::is_runnable() 5642 { 5643 return NULL; 5644 } 5645 5646 // We need to unlock FINAL_BLOCKER when finished. 5647 5648 void 5649 Write_data_task::locks(Task_locker* tl) 5650 { 5651 tl->add(this, this->final_blocker_); 5652 } 5653 5654 // Run the task--write out the data. 5655 5656 void 5657 Write_data_task::run(Workqueue*) 5658 { 5659 this->layout_->write_data(this->symtab_, this->of_); 5660 } 5661 5662 // Write_symbols_task methods. 5663 5664 // We can always run this task. 5665 5666 Task_token* 5667 Write_symbols_task::is_runnable() 5668 { 5669 return NULL; 5670 } 5671 5672 // We need to unlock FINAL_BLOCKER when finished. 5673 5674 void 5675 Write_symbols_task::locks(Task_locker* tl) 5676 { 5677 tl->add(this, this->final_blocker_); 5678 } 5679 5680 // Run the task--write out the symbols. 5681 5682 void 5683 Write_symbols_task::run(Workqueue*) 5684 { 5685 this->symtab_->write_globals(this->sympool_, this->dynpool_, 5686 this->layout_->symtab_xindex(), 5687 this->layout_->dynsym_xindex(), this->of_); 5688 } 5689 5690 // Write_after_input_sections_task methods. 5691 5692 // We can only run this task after the input sections have completed. 5693 5694 Task_token* 5695 Write_after_input_sections_task::is_runnable() 5696 { 5697 if (this->input_sections_blocker_->is_blocked()) 5698 return this->input_sections_blocker_; 5699 return NULL; 5700 } 5701 5702 // We need to unlock FINAL_BLOCKER when finished. 5703 5704 void 5705 Write_after_input_sections_task::locks(Task_locker* tl) 5706 { 5707 tl->add(this, this->final_blocker_); 5708 } 5709 5710 // Run the task. 5711 5712 void 5713 Write_after_input_sections_task::run(Workqueue*) 5714 { 5715 this->layout_->write_sections_after_input_sections(this->of_); 5716 } 5717 5718 // Build IDs can be computed as a "flat" sha1 or md5 of a string of bytes, 5719 // or as a "tree" where each chunk of the string is hashed and then those 5720 // hashes are put into a (much smaller) string which is hashed with sha1. 5721 // We compute a checksum over the entire file because that is simplest. 5722 5723 void 5724 Build_id_task_runner::run(Workqueue* workqueue, const Task*) 5725 { 5726 Task_token* post_hash_tasks_blocker = new Task_token(true); 5727 const Layout* layout = this->layout_; 5728 Output_file* of = this->of_; 5729 const size_t filesize = (layout->output_file_size() <= 0 ? 0 5730 : static_cast<size_t>(layout->output_file_size())); 5731 unsigned char* array_of_hashes = NULL; 5732 size_t size_of_hashes = 0; 5733 5734 if (strcmp(this->options_->build_id(), "tree") == 0 5735 && this->options_->build_id_chunk_size_for_treehash() > 0 5736 && filesize > 0 5737 && (filesize >= this->options_->build_id_min_file_size_for_treehash())) 5738 { 5739 static const size_t MD5_OUTPUT_SIZE_IN_BYTES = 16; 5740 const size_t chunk_size = 5741 this->options_->build_id_chunk_size_for_treehash(); 5742 const size_t num_hashes = ((filesize - 1) / chunk_size) + 1; 5743 post_hash_tasks_blocker->add_blockers(num_hashes); 5744 size_of_hashes = num_hashes * MD5_OUTPUT_SIZE_IN_BYTES; 5745 array_of_hashes = new unsigned char[size_of_hashes]; 5746 unsigned char *dst = array_of_hashes; 5747 for (size_t i = 0, src_offset = 0; i < num_hashes; 5748 i++, dst += MD5_OUTPUT_SIZE_IN_BYTES, src_offset += chunk_size) 5749 { 5750 size_t size = std::min(chunk_size, filesize - src_offset); 5751 workqueue->queue(new Hash_task(of, 5752 src_offset, 5753 size, 5754 dst, 5755 post_hash_tasks_blocker)); 5756 } 5757 } 5758 5759 // Queue the final task to write the build id and close the output file. 5760 workqueue->queue(new Task_function(new Close_task_runner(this->options_, 5761 layout, 5762 of, 5763 array_of_hashes, 5764 size_of_hashes), 5765 post_hash_tasks_blocker, 5766 "Task_function Close_task_runner")); 5767 } 5768 5769 // Close_task_runner methods. 5770 5771 // Finish up the build ID computation, if necessary, and write a binary file, 5772 // if necessary. Then close the output file. 5773 5774 void 5775 Close_task_runner::run(Workqueue*, const Task*) 5776 { 5777 // At this point the multi-threaded part of the build ID computation, 5778 // if any, is done. See Build_id_task_runner. 5779 this->layout_->write_build_id(this->of_, this->array_of_hashes_, 5780 this->size_of_hashes_); 5781 5782 // If we've been asked to create a binary file, we do so here. 5783 if (this->options_->oformat_enum() != General_options::OBJECT_FORMAT_ELF) 5784 this->layout_->write_binary(this->of_); 5785 5786 this->of_->close(); 5787 } 5788 5789 // Instantiate the templates we need. We could use the configure 5790 // script to restrict this to only the ones for implemented targets. 5791 5792 #ifdef HAVE_TARGET_32_LITTLE 5793 template 5794 Output_section* 5795 Layout::init_fixed_output_section<32, false>( 5796 const char* name, 5797 elfcpp::Shdr<32, false>& shdr); 5798 #endif 5799 5800 #ifdef HAVE_TARGET_32_BIG 5801 template 5802 Output_section* 5803 Layout::init_fixed_output_section<32, true>( 5804 const char* name, 5805 elfcpp::Shdr<32, true>& shdr); 5806 #endif 5807 5808 #ifdef HAVE_TARGET_64_LITTLE 5809 template 5810 Output_section* 5811 Layout::init_fixed_output_section<64, false>( 5812 const char* name, 5813 elfcpp::Shdr<64, false>& shdr); 5814 #endif 5815 5816 #ifdef HAVE_TARGET_64_BIG 5817 template 5818 Output_section* 5819 Layout::init_fixed_output_section<64, true>( 5820 const char* name, 5821 elfcpp::Shdr<64, true>& shdr); 5822 #endif 5823 5824 #ifdef HAVE_TARGET_32_LITTLE 5825 template 5826 Output_section* 5827 Layout::layout<32, false>(Sized_relobj_file<32, false>* object, 5828 unsigned int shndx, 5829 const char* name, 5830 const elfcpp::Shdr<32, false>& shdr, 5831 unsigned int, unsigned int, off_t*); 5832 #endif 5833 5834 #ifdef HAVE_TARGET_32_BIG 5835 template 5836 Output_section* 5837 Layout::layout<32, true>(Sized_relobj_file<32, true>* object, 5838 unsigned int shndx, 5839 const char* name, 5840 const elfcpp::Shdr<32, true>& shdr, 5841 unsigned int, unsigned int, off_t*); 5842 #endif 5843 5844 #ifdef HAVE_TARGET_64_LITTLE 5845 template 5846 Output_section* 5847 Layout::layout<64, false>(Sized_relobj_file<64, false>* object, 5848 unsigned int shndx, 5849 const char* name, 5850 const elfcpp::Shdr<64, false>& shdr, 5851 unsigned int, unsigned int, off_t*); 5852 #endif 5853 5854 #ifdef HAVE_TARGET_64_BIG 5855 template 5856 Output_section* 5857 Layout::layout<64, true>(Sized_relobj_file<64, true>* object, 5858 unsigned int shndx, 5859 const char* name, 5860 const elfcpp::Shdr<64, true>& shdr, 5861 unsigned int, unsigned int, off_t*); 5862 #endif 5863 5864 #ifdef HAVE_TARGET_32_LITTLE 5865 template 5866 Output_section* 5867 Layout::layout_reloc<32, false>(Sized_relobj_file<32, false>* object, 5868 unsigned int reloc_shndx, 5869 const elfcpp::Shdr<32, false>& shdr, 5870 Output_section* data_section, 5871 Relocatable_relocs* rr); 5872 #endif 5873 5874 #ifdef HAVE_TARGET_32_BIG 5875 template 5876 Output_section* 5877 Layout::layout_reloc<32, true>(Sized_relobj_file<32, true>* object, 5878 unsigned int reloc_shndx, 5879 const elfcpp::Shdr<32, true>& shdr, 5880 Output_section* data_section, 5881 Relocatable_relocs* rr); 5882 #endif 5883 5884 #ifdef HAVE_TARGET_64_LITTLE 5885 template 5886 Output_section* 5887 Layout::layout_reloc<64, false>(Sized_relobj_file<64, false>* object, 5888 unsigned int reloc_shndx, 5889 const elfcpp::Shdr<64, false>& shdr, 5890 Output_section* data_section, 5891 Relocatable_relocs* rr); 5892 #endif 5893 5894 #ifdef HAVE_TARGET_64_BIG 5895 template 5896 Output_section* 5897 Layout::layout_reloc<64, true>(Sized_relobj_file<64, true>* object, 5898 unsigned int reloc_shndx, 5899 const elfcpp::Shdr<64, true>& shdr, 5900 Output_section* data_section, 5901 Relocatable_relocs* rr); 5902 #endif 5903 5904 #ifdef HAVE_TARGET_32_LITTLE 5905 template 5906 void 5907 Layout::layout_group<32, false>(Symbol_table* symtab, 5908 Sized_relobj_file<32, false>* object, 5909 unsigned int, 5910 const char* group_section_name, 5911 const char* signature, 5912 const elfcpp::Shdr<32, false>& shdr, 5913 elfcpp::Elf_Word flags, 5914 std::vector<unsigned int>* shndxes); 5915 #endif 5916 5917 #ifdef HAVE_TARGET_32_BIG 5918 template 5919 void 5920 Layout::layout_group<32, true>(Symbol_table* symtab, 5921 Sized_relobj_file<32, true>* object, 5922 unsigned int, 5923 const char* group_section_name, 5924 const char* signature, 5925 const elfcpp::Shdr<32, true>& shdr, 5926 elfcpp::Elf_Word flags, 5927 std::vector<unsigned int>* shndxes); 5928 #endif 5929 5930 #ifdef HAVE_TARGET_64_LITTLE 5931 template 5932 void 5933 Layout::layout_group<64, false>(Symbol_table* symtab, 5934 Sized_relobj_file<64, false>* object, 5935 unsigned int, 5936 const char* group_section_name, 5937 const char* signature, 5938 const elfcpp::Shdr<64, false>& shdr, 5939 elfcpp::Elf_Word flags, 5940 std::vector<unsigned int>* shndxes); 5941 #endif 5942 5943 #ifdef HAVE_TARGET_64_BIG 5944 template 5945 void 5946 Layout::layout_group<64, true>(Symbol_table* symtab, 5947 Sized_relobj_file<64, true>* object, 5948 unsigned int, 5949 const char* group_section_name, 5950 const char* signature, 5951 const elfcpp::Shdr<64, true>& shdr, 5952 elfcpp::Elf_Word flags, 5953 std::vector<unsigned int>* shndxes); 5954 #endif 5955 5956 #ifdef HAVE_TARGET_32_LITTLE 5957 template 5958 Output_section* 5959 Layout::layout_eh_frame<32, false>(Sized_relobj_file<32, false>* object, 5960 const unsigned char* symbols, 5961 off_t symbols_size, 5962 const unsigned char* symbol_names, 5963 off_t symbol_names_size, 5964 unsigned int shndx, 5965 const elfcpp::Shdr<32, false>& shdr, 5966 unsigned int reloc_shndx, 5967 unsigned int reloc_type, 5968 off_t* off); 5969 #endif 5970 5971 #ifdef HAVE_TARGET_32_BIG 5972 template 5973 Output_section* 5974 Layout::layout_eh_frame<32, true>(Sized_relobj_file<32, true>* object, 5975 const unsigned char* symbols, 5976 off_t symbols_size, 5977 const unsigned char* symbol_names, 5978 off_t symbol_names_size, 5979 unsigned int shndx, 5980 const elfcpp::Shdr<32, true>& shdr, 5981 unsigned int reloc_shndx, 5982 unsigned int reloc_type, 5983 off_t* off); 5984 #endif 5985 5986 #ifdef HAVE_TARGET_64_LITTLE 5987 template 5988 Output_section* 5989 Layout::layout_eh_frame<64, false>(Sized_relobj_file<64, false>* object, 5990 const unsigned char* symbols, 5991 off_t symbols_size, 5992 const unsigned char* symbol_names, 5993 off_t symbol_names_size, 5994 unsigned int shndx, 5995 const elfcpp::Shdr<64, false>& shdr, 5996 unsigned int reloc_shndx, 5997 unsigned int reloc_type, 5998 off_t* off); 5999 #endif 6000 6001 #ifdef HAVE_TARGET_64_BIG 6002 template 6003 Output_section* 6004 Layout::layout_eh_frame<64, true>(Sized_relobj_file<64, true>* object, 6005 const unsigned char* symbols, 6006 off_t symbols_size, 6007 const unsigned char* symbol_names, 6008 off_t symbol_names_size, 6009 unsigned int shndx, 6010 const elfcpp::Shdr<64, true>& shdr, 6011 unsigned int reloc_shndx, 6012 unsigned int reloc_type, 6013 off_t* off); 6014 #endif 6015 6016 #ifdef HAVE_TARGET_32_LITTLE 6017 template 6018 void 6019 Layout::add_to_gdb_index(bool is_type_unit, 6020 Sized_relobj<32, false>* object, 6021 const unsigned char* symbols, 6022 off_t symbols_size, 6023 unsigned int shndx, 6024 unsigned int reloc_shndx, 6025 unsigned int reloc_type); 6026 #endif 6027 6028 #ifdef HAVE_TARGET_32_BIG 6029 template 6030 void 6031 Layout::add_to_gdb_index(bool is_type_unit, 6032 Sized_relobj<32, true>* object, 6033 const unsigned char* symbols, 6034 off_t symbols_size, 6035 unsigned int shndx, 6036 unsigned int reloc_shndx, 6037 unsigned int reloc_type); 6038 #endif 6039 6040 #ifdef HAVE_TARGET_64_LITTLE 6041 template 6042 void 6043 Layout::add_to_gdb_index(bool is_type_unit, 6044 Sized_relobj<64, false>* object, 6045 const unsigned char* symbols, 6046 off_t symbols_size, 6047 unsigned int shndx, 6048 unsigned int reloc_shndx, 6049 unsigned int reloc_type); 6050 #endif 6051 6052 #ifdef HAVE_TARGET_64_BIG 6053 template 6054 void 6055 Layout::add_to_gdb_index(bool is_type_unit, 6056 Sized_relobj<64, true>* object, 6057 const unsigned char* symbols, 6058 off_t symbols_size, 6059 unsigned int shndx, 6060 unsigned int reloc_shndx, 6061 unsigned int reloc_type); 6062 #endif 6063 6064 } // End namespace gold. 6065