1 // layout.cc -- lay out output file sections for gold 2 3 // Copyright (C) 2006-2020 Free Software Foundation, Inc. 4 // Written by Ian Lance Taylor <iant@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 #ifdef __MINGW32__ 38 #include <windows.h> 39 #include <rpcdce.h> 40 #endif 41 42 #include "parameters.h" 43 #include "options.h" 44 #include "mapfile.h" 45 #include "script.h" 46 #include "script-sections.h" 47 #include "output.h" 48 #include "symtab.h" 49 #include "dynobj.h" 50 #include "ehframe.h" 51 #include "gdb-index.h" 52 #include "compressed_output.h" 53 #include "reduced_debug_output.h" 54 #include "object.h" 55 #include "reloc.h" 56 #include "descriptors.h" 57 #include "plugin.h" 58 #include "incremental.h" 59 #include "layout.h" 60 61 namespace gold 62 { 63 64 // Class Free_list. 65 66 // The total number of free lists used. 67 unsigned int Free_list::num_lists = 0; 68 // The total number of free list nodes used. 69 unsigned int Free_list::num_nodes = 0; 70 // The total number of calls to Free_list::remove. 71 unsigned int Free_list::num_removes = 0; 72 // The total number of nodes visited during calls to Free_list::remove. 73 unsigned int Free_list::num_remove_visits = 0; 74 // The total number of calls to Free_list::allocate. 75 unsigned int Free_list::num_allocates = 0; 76 // The total number of nodes visited during calls to Free_list::allocate. 77 unsigned int Free_list::num_allocate_visits = 0; 78 79 // Initialize the free list. Creates a single free list node that 80 // describes the entire region of length LEN. If EXTEND is true, 81 // allocate() is allowed to extend the region beyond its initial 82 // length. 83 84 void 85 Free_list::init(off_t len, bool extend) 86 { 87 this->list_.push_front(Free_list_node(0, len)); 88 this->last_remove_ = this->list_.begin(); 89 this->extend_ = extend; 90 this->length_ = len; 91 ++Free_list::num_lists; 92 ++Free_list::num_nodes; 93 } 94 95 // Remove a chunk from the free list. Because we start with a single 96 // node that covers the entire section, and remove chunks from it one 97 // at a time, we do not need to coalesce chunks or handle cases that 98 // span more than one free node. We expect to remove chunks from the 99 // free list in order, and we expect to have only a few chunks of free 100 // space left (corresponding to files that have changed since the last 101 // incremental link), so a simple linear list should provide sufficient 102 // performance. 103 104 void 105 Free_list::remove(off_t start, off_t end) 106 { 107 if (start == end) 108 return; 109 gold_assert(start < end); 110 111 ++Free_list::num_removes; 112 113 Iterator p = this->last_remove_; 114 if (p->start_ > start) 115 p = this->list_.begin(); 116 117 for (; p != this->list_.end(); ++p) 118 { 119 ++Free_list::num_remove_visits; 120 // Find a node that wholly contains the indicated region. 121 if (p->start_ <= start && p->end_ >= end) 122 { 123 // Case 1: the indicated region spans the whole node. 124 // Add some fuzz to avoid creating tiny free chunks. 125 if (p->start_ + 3 >= start && p->end_ <= end + 3) 126 p = this->list_.erase(p); 127 // Case 2: remove a chunk from the start of the node. 128 else if (p->start_ + 3 >= start) 129 p->start_ = end; 130 // Case 3: remove a chunk from the end of the node. 131 else if (p->end_ <= end + 3) 132 p->end_ = start; 133 // Case 4: remove a chunk from the middle, and split 134 // the node into two. 135 else 136 { 137 Free_list_node newnode(p->start_, start); 138 p->start_ = end; 139 this->list_.insert(p, newnode); 140 ++Free_list::num_nodes; 141 } 142 this->last_remove_ = p; 143 return; 144 } 145 } 146 147 // Did not find a node containing the given chunk. This could happen 148 // because a small chunk was already removed due to the fuzz. 149 gold_debug(DEBUG_INCREMENTAL, 150 "Free_list::remove(%d,%d) not found", 151 static_cast<int>(start), static_cast<int>(end)); 152 } 153 154 // Allocate a chunk of size LEN from the free list. Returns -1ULL 155 // if a sufficiently large chunk of free space is not found. 156 // We use a simple first-fit algorithm. 157 158 off_t 159 Free_list::allocate(off_t len, uint64_t align, off_t minoff) 160 { 161 gold_debug(DEBUG_INCREMENTAL, 162 "Free_list::allocate(%08lx, %d, %08lx)", 163 static_cast<long>(len), static_cast<int>(align), 164 static_cast<long>(minoff)); 165 if (len == 0) 166 return align_address(minoff, align); 167 168 ++Free_list::num_allocates; 169 170 // We usually want to drop free chunks smaller than 4 bytes. 171 // If we need to guarantee a minimum hole size, though, we need 172 // to keep track of all free chunks. 173 const int fuzz = this->min_hole_ > 0 ? 0 : 3; 174 175 for (Iterator p = this->list_.begin(); p != this->list_.end(); ++p) 176 { 177 ++Free_list::num_allocate_visits; 178 off_t start = p->start_ > minoff ? p->start_ : minoff; 179 start = align_address(start, align); 180 off_t end = start + len; 181 if (end > p->end_ && p->end_ == this->length_ && this->extend_) 182 { 183 this->length_ = end; 184 p->end_ = end; 185 } 186 if (end == p->end_ || (end <= p->end_ - this->min_hole_)) 187 { 188 if (p->start_ + fuzz >= start && p->end_ <= end + fuzz) 189 this->list_.erase(p); 190 else if (p->start_ + fuzz >= start) 191 p->start_ = end; 192 else if (p->end_ <= end + fuzz) 193 p->end_ = start; 194 else 195 { 196 Free_list_node newnode(p->start_, start); 197 p->start_ = end; 198 this->list_.insert(p, newnode); 199 ++Free_list::num_nodes; 200 } 201 return start; 202 } 203 } 204 if (this->extend_) 205 { 206 off_t start = align_address(this->length_, align); 207 this->length_ = start + len; 208 return start; 209 } 210 return -1; 211 } 212 213 // Dump the free list (for debugging). 214 void 215 Free_list::dump() 216 { 217 gold_info("Free list:\n start end length\n"); 218 for (Iterator p = this->list_.begin(); p != this->list_.end(); ++p) 219 gold_info(" %08lx %08lx %08lx", static_cast<long>(p->start_), 220 static_cast<long>(p->end_), 221 static_cast<long>(p->end_ - p->start_)); 222 } 223 224 // Print the statistics for the free lists. 225 void 226 Free_list::print_stats() 227 { 228 fprintf(stderr, _("%s: total free lists: %u\n"), 229 program_name, Free_list::num_lists); 230 fprintf(stderr, _("%s: total free list nodes: %u\n"), 231 program_name, Free_list::num_nodes); 232 fprintf(stderr, _("%s: calls to Free_list::remove: %u\n"), 233 program_name, Free_list::num_removes); 234 fprintf(stderr, _("%s: nodes visited: %u\n"), 235 program_name, Free_list::num_remove_visits); 236 fprintf(stderr, _("%s: calls to Free_list::allocate: %u\n"), 237 program_name, Free_list::num_allocates); 238 fprintf(stderr, _("%s: nodes visited: %u\n"), 239 program_name, Free_list::num_allocate_visits); 240 } 241 242 // A Hash_task computes the MD5 checksum of an array of char. 243 244 class Hash_task : public Task 245 { 246 public: 247 Hash_task(Output_file* of, 248 size_t offset, 249 size_t size, 250 unsigned char* dst, 251 Task_token* final_blocker) 252 : of_(of), offset_(offset), size_(size), dst_(dst), 253 final_blocker_(final_blocker) 254 { } 255 256 void 257 run(Workqueue*) 258 { 259 const unsigned char* iv = 260 this->of_->get_input_view(this->offset_, this->size_); 261 md5_buffer(reinterpret_cast<const char*>(iv), this->size_, this->dst_); 262 this->of_->free_input_view(this->offset_, this->size_, iv); 263 } 264 265 Task_token* 266 is_runnable() 267 { return NULL; } 268 269 // Unblock FINAL_BLOCKER_ when done. 270 void 271 locks(Task_locker* tl) 272 { tl->add(this, this->final_blocker_); } 273 274 std::string 275 get_name() const 276 { return "Hash_task"; } 277 278 private: 279 Output_file* of_; 280 const size_t offset_; 281 const size_t size_; 282 unsigned char* const dst_; 283 Task_token* const final_blocker_; 284 }; 285 286 // Layout::Relaxation_debug_check methods. 287 288 // Check that sections and special data are in reset states. 289 // We do not save states for Output_sections and special Output_data. 290 // So we check that they have not assigned any addresses or offsets. 291 // clean_up_after_relaxation simply resets their addresses and offsets. 292 void 293 Layout::Relaxation_debug_check::check_output_data_for_reset_values( 294 const Layout::Section_list& sections, 295 const Layout::Data_list& special_outputs, 296 const Layout::Data_list& relax_outputs) 297 { 298 for(Layout::Section_list::const_iterator p = sections.begin(); 299 p != sections.end(); 300 ++p) 301 gold_assert((*p)->address_and_file_offset_have_reset_values()); 302 303 for(Layout::Data_list::const_iterator p = special_outputs.begin(); 304 p != special_outputs.end(); 305 ++p) 306 gold_assert((*p)->address_and_file_offset_have_reset_values()); 307 308 gold_assert(relax_outputs.empty()); 309 } 310 311 // Save information of SECTIONS for checking later. 312 313 void 314 Layout::Relaxation_debug_check::read_sections( 315 const Layout::Section_list& sections) 316 { 317 for(Layout::Section_list::const_iterator p = sections.begin(); 318 p != sections.end(); 319 ++p) 320 { 321 Output_section* os = *p; 322 Section_info info; 323 info.output_section = os; 324 info.address = os->is_address_valid() ? os->address() : 0; 325 info.data_size = os->is_data_size_valid() ? os->data_size() : -1; 326 info.offset = os->is_offset_valid()? os->offset() : -1 ; 327 this->section_infos_.push_back(info); 328 } 329 } 330 331 // Verify SECTIONS using previously recorded information. 332 333 void 334 Layout::Relaxation_debug_check::verify_sections( 335 const Layout::Section_list& sections) 336 { 337 size_t i = 0; 338 for(Layout::Section_list::const_iterator p = sections.begin(); 339 p != sections.end(); 340 ++p, ++i) 341 { 342 Output_section* os = *p; 343 uint64_t address = os->is_address_valid() ? os->address() : 0; 344 off_t data_size = os->is_data_size_valid() ? os->data_size() : -1; 345 off_t offset = os->is_offset_valid()? os->offset() : -1 ; 346 347 if (i >= this->section_infos_.size()) 348 { 349 gold_fatal("Section_info of %s missing.\n", os->name()); 350 } 351 const Section_info& info = this->section_infos_[i]; 352 if (os != info.output_section) 353 gold_fatal("Section order changed. Expecting %s but see %s\n", 354 info.output_section->name(), os->name()); 355 if (address != info.address 356 || data_size != info.data_size 357 || offset != info.offset) 358 gold_fatal("Section %s changed.\n", os->name()); 359 } 360 } 361 362 // Layout_task_runner methods. 363 364 // Lay out the sections. This is called after all the input objects 365 // have been read. 366 367 void 368 Layout_task_runner::run(Workqueue* workqueue, const Task* task) 369 { 370 // See if any of the input definitions violate the One Definition Rule. 371 // TODO: if this is too slow, do this as a task, rather than inline. 372 this->symtab_->detect_odr_violations(task, this->options_.output_file_name()); 373 374 Layout* layout = this->layout_; 375 off_t file_size = layout->finalize(this->input_objects_, 376 this->symtab_, 377 this->target_, 378 task); 379 380 // Now we know the final size of the output file and we know where 381 // each piece of information goes. 382 383 if (this->mapfile_ != NULL) 384 { 385 this->mapfile_->print_discarded_sections(this->input_objects_); 386 layout->print_to_mapfile(this->mapfile_); 387 } 388 389 Output_file* of; 390 if (layout->incremental_base() == NULL) 391 { 392 of = new Output_file(parameters->options().output_file_name()); 393 if (this->options_.oformat_enum() != General_options::OBJECT_FORMAT_ELF) 394 of->set_is_temporary(); 395 of->open(file_size); 396 } 397 else 398 { 399 of = layout->incremental_base()->output_file(); 400 401 // Apply the incremental relocations for symbols whose values 402 // have changed. We do this before we resize the file and start 403 // writing anything else to it, so that we can read the old 404 // incremental information from the file before (possibly) 405 // overwriting it. 406 if (parameters->incremental_update()) 407 layout->incremental_base()->apply_incremental_relocs(this->symtab_, 408 this->layout_, 409 of); 410 411 of->resize(file_size); 412 } 413 414 // Queue up the final set of tasks. 415 gold::queue_final_tasks(this->options_, this->input_objects_, 416 this->symtab_, layout, workqueue, of); 417 } 418 419 // Layout methods. 420 421 Layout::Layout(int number_of_input_files, Script_options* script_options) 422 : number_of_input_files_(number_of_input_files), 423 script_options_(script_options), 424 namepool_(), 425 sympool_(), 426 dynpool_(), 427 signatures_(), 428 section_name_map_(), 429 segment_list_(), 430 section_list_(), 431 unattached_section_list_(), 432 special_output_list_(), 433 relax_output_list_(), 434 section_headers_(NULL), 435 tls_segment_(NULL), 436 relro_segment_(NULL), 437 interp_segment_(NULL), 438 increase_relro_(0), 439 symtab_section_(NULL), 440 symtab_xindex_(NULL), 441 dynsym_section_(NULL), 442 dynsym_xindex_(NULL), 443 dynamic_section_(NULL), 444 dynamic_symbol_(NULL), 445 dynamic_data_(NULL), 446 eh_frame_section_(NULL), 447 eh_frame_data_(NULL), 448 added_eh_frame_data_(false), 449 eh_frame_hdr_section_(NULL), 450 gdb_index_data_(NULL), 451 build_id_note_(NULL), 452 debug_abbrev_(NULL), 453 debug_info_(NULL), 454 group_signatures_(), 455 output_file_size_(-1), 456 have_added_input_section_(false), 457 sections_are_attached_(false), 458 input_requires_executable_stack_(false), 459 input_with_gnu_stack_note_(false), 460 input_without_gnu_stack_note_(false), 461 has_static_tls_(false), 462 any_postprocessing_sections_(false), 463 resized_signatures_(false), 464 have_stabstr_section_(false), 465 section_ordering_specified_(false), 466 unique_segment_for_sections_specified_(false), 467 incremental_inputs_(NULL), 468 record_output_section_data_from_script_(false), 469 lto_slim_object_(false), 470 script_output_section_data_list_(), 471 segment_states_(NULL), 472 relaxation_debug_check_(NULL), 473 section_order_map_(), 474 section_segment_map_(), 475 input_section_position_(), 476 input_section_glob_(), 477 incremental_base_(NULL), 478 free_list_(), 479 gnu_properties_() 480 { 481 // Make space for more than enough segments for a typical file. 482 // This is just for efficiency--it's OK if we wind up needing more. 483 this->segment_list_.reserve(12); 484 485 // We expect two unattached Output_data objects: the file header and 486 // the segment headers. 487 this->special_output_list_.reserve(2); 488 489 // Initialize structure needed for an incremental build. 490 if (parameters->incremental()) 491 this->incremental_inputs_ = new Incremental_inputs; 492 493 // The section name pool is worth optimizing in all cases, because 494 // it is small, but there are often overlaps due to .rel sections. 495 this->namepool_.set_optimize(); 496 } 497 498 // For incremental links, record the base file to be modified. 499 500 void 501 Layout::set_incremental_base(Incremental_binary* base) 502 { 503 this->incremental_base_ = base; 504 this->free_list_.init(base->output_file()->filesize(), true); 505 } 506 507 // Hash a key we use to look up an output section mapping. 508 509 size_t 510 Layout::Hash_key::operator()(const Layout::Key& k) const 511 { 512 return k.first + k.second.first + k.second.second; 513 } 514 515 // These are the debug sections that are actually used by gdb. 516 // Currently, we've checked versions of gdb up to and including 7.4. 517 // We only check the part of the name that follows ".debug_" or 518 // ".zdebug_". 519 520 static const char* gdb_sections[] = 521 { 522 "abbrev", 523 "addr", // Fission extension 524 // "aranges", // not used by gdb as of 7.4 525 "frame", 526 "gdb_scripts", 527 "info", 528 "types", 529 "line", 530 "loc", 531 "macinfo", 532 "macro", 533 // "pubnames", // not used by gdb as of 7.4 534 // "pubtypes", // not used by gdb as of 7.4 535 // "gnu_pubnames", // Fission extension 536 // "gnu_pubtypes", // Fission extension 537 "ranges", 538 "str", 539 "str_offsets", 540 }; 541 542 // This is the minimum set of sections needed for line numbers. 543 544 static const char* lines_only_debug_sections[] = 545 { 546 "abbrev", 547 // "addr", // Fission extension 548 // "aranges", // not used by gdb as of 7.4 549 // "frame", 550 // "gdb_scripts", 551 "info", 552 // "types", 553 "line", 554 // "loc", 555 // "macinfo", 556 // "macro", 557 // "pubnames", // not used by gdb as of 7.4 558 // "pubtypes", // not used by gdb as of 7.4 559 // "gnu_pubnames", // Fission extension 560 // "gnu_pubtypes", // Fission extension 561 // "ranges", 562 "str", 563 "str_offsets", // Fission extension 564 }; 565 566 // These sections are the DWARF fast-lookup tables, and are not needed 567 // when building a .gdb_index section. 568 569 static const char* gdb_fast_lookup_sections[] = 570 { 571 "aranges", 572 "pubnames", 573 "gnu_pubnames", 574 "pubtypes", 575 "gnu_pubtypes", 576 }; 577 578 // Returns whether the given debug section is in the list of 579 // debug-sections-used-by-some-version-of-gdb. SUFFIX is the 580 // portion of the name following ".debug_" or ".zdebug_". 581 582 static inline bool 583 is_gdb_debug_section(const char* suffix) 584 { 585 // We can do this faster: binary search or a hashtable. But why bother? 586 for (size_t i = 0; i < sizeof(gdb_sections)/sizeof(*gdb_sections); ++i) 587 if (strcmp(suffix, gdb_sections[i]) == 0) 588 return true; 589 return false; 590 } 591 592 // Returns whether the given section is needed for lines-only debugging. 593 594 static inline bool 595 is_lines_only_debug_section(const char* suffix) 596 { 597 // We can do this faster: binary search or a hashtable. But why bother? 598 for (size_t i = 0; 599 i < sizeof(lines_only_debug_sections)/sizeof(*lines_only_debug_sections); 600 ++i) 601 if (strcmp(suffix, lines_only_debug_sections[i]) == 0) 602 return true; 603 return false; 604 } 605 606 // Returns whether the given section is a fast-lookup section that 607 // will not be needed when building a .gdb_index section. 608 609 static inline bool 610 is_gdb_fast_lookup_section(const char* suffix) 611 { 612 // We can do this faster: binary search or a hashtable. But why bother? 613 for (size_t i = 0; 614 i < sizeof(gdb_fast_lookup_sections)/sizeof(*gdb_fast_lookup_sections); 615 ++i) 616 if (strcmp(suffix, gdb_fast_lookup_sections[i]) == 0) 617 return true; 618 return false; 619 } 620 621 // Sometimes we compress sections. This is typically done for 622 // sections that are not part of normal program execution (such as 623 // .debug_* sections), and where the readers of these sections know 624 // how to deal with compressed sections. This routine doesn't say for 625 // certain whether we'll compress -- it depends on commandline options 626 // as well -- just whether this section is a candidate for compression. 627 // (The Output_compressed_section class decides whether to compress 628 // a given section, and picks the name of the compressed section.) 629 630 static bool 631 is_compressible_debug_section(const char* secname) 632 { 633 return (is_prefix_of(".debug", secname)); 634 } 635 636 // We may see compressed debug sections in input files. Return TRUE 637 // if this is the name of a compressed debug section. 638 639 bool 640 is_compressed_debug_section(const char* secname) 641 { 642 return (is_prefix_of(".zdebug", secname)); 643 } 644 645 std::string 646 corresponding_uncompressed_section_name(std::string secname) 647 { 648 gold_assert(secname[0] == '.' && secname[1] == 'z'); 649 std::string ret("."); 650 ret.append(secname, 2, std::string::npos); 651 return ret; 652 } 653 654 // Whether to include this section in the link. 655 656 template<int size, bool big_endian> 657 bool 658 Layout::include_section(Sized_relobj_file<size, big_endian>*, const char* name, 659 const elfcpp::Shdr<size, big_endian>& shdr) 660 { 661 if (!parameters->options().relocatable() 662 && (shdr.get_sh_flags() & elfcpp::SHF_EXCLUDE)) 663 return false; 664 665 elfcpp::Elf_Word sh_type = shdr.get_sh_type(); 666 667 if ((sh_type >= elfcpp::SHT_LOOS && sh_type <= elfcpp::SHT_HIOS) 668 || (sh_type >= elfcpp::SHT_LOPROC && sh_type <= elfcpp::SHT_HIPROC)) 669 return parameters->target().should_include_section(sh_type); 670 671 switch (sh_type) 672 { 673 case elfcpp::SHT_NULL: 674 case elfcpp::SHT_SYMTAB: 675 case elfcpp::SHT_DYNSYM: 676 case elfcpp::SHT_HASH: 677 case elfcpp::SHT_DYNAMIC: 678 case elfcpp::SHT_SYMTAB_SHNDX: 679 return false; 680 681 case elfcpp::SHT_STRTAB: 682 // Discard the sections which have special meanings in the ELF 683 // ABI. Keep others (e.g., .stabstr). We could also do this by 684 // checking the sh_link fields of the appropriate sections. 685 return (strcmp(name, ".dynstr") != 0 686 && strcmp(name, ".strtab") != 0 687 && strcmp(name, ".shstrtab") != 0); 688 689 case elfcpp::SHT_RELA: 690 case elfcpp::SHT_REL: 691 case elfcpp::SHT_GROUP: 692 // If we are emitting relocations these should be handled 693 // elsewhere. 694 gold_assert(!parameters->options().relocatable()); 695 return false; 696 697 case elfcpp::SHT_PROGBITS: 698 if (parameters->options().strip_debug() 699 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0) 700 { 701 if (is_debug_info_section(name)) 702 return false; 703 } 704 if (parameters->options().strip_debug_non_line() 705 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0) 706 { 707 // Debugging sections can only be recognized by name. 708 if (is_prefix_of(".debug_", name) 709 && !is_lines_only_debug_section(name + 7)) 710 return false; 711 if (is_prefix_of(".zdebug_", name) 712 && !is_lines_only_debug_section(name + 8)) 713 return false; 714 } 715 if (parameters->options().strip_debug_gdb() 716 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0) 717 { 718 // Debugging sections can only be recognized by name. 719 if (is_prefix_of(".debug_", name) 720 && !is_gdb_debug_section(name + 7)) 721 return false; 722 if (is_prefix_of(".zdebug_", name) 723 && !is_gdb_debug_section(name + 8)) 724 return false; 725 } 726 if (parameters->options().gdb_index() 727 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0) 728 { 729 // When building .gdb_index, we can strip .debug_pubnames, 730 // .debug_pubtypes, and .debug_aranges sections. 731 if (is_prefix_of(".debug_", name) 732 && is_gdb_fast_lookup_section(name + 7)) 733 return false; 734 if (is_prefix_of(".zdebug_", name) 735 && is_gdb_fast_lookup_section(name + 8)) 736 return false; 737 } 738 if (parameters->options().strip_lto_sections() 739 && !parameters->options().relocatable() 740 && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC) == 0) 741 { 742 // Ignore LTO sections containing intermediate code. 743 if (is_prefix_of(".gnu.lto_", name)) 744 return false; 745 } 746 // The GNU linker strips .gnu_debuglink sections, so we do too. 747 // This is a feature used to keep debugging information in 748 // separate files. 749 if (strcmp(name, ".gnu_debuglink") == 0) 750 return false; 751 return true; 752 753 default: 754 return true; 755 } 756 } 757 758 // Return an output section named NAME, or NULL if there is none. 759 760 Output_section* 761 Layout::find_output_section(const char* name) const 762 { 763 for (Section_list::const_iterator p = this->section_list_.begin(); 764 p != this->section_list_.end(); 765 ++p) 766 if (strcmp((*p)->name(), name) == 0) 767 return *p; 768 return NULL; 769 } 770 771 // Return an output segment of type TYPE, with segment flags SET set 772 // and segment flags CLEAR clear. Return NULL if there is none. 773 774 Output_segment* 775 Layout::find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set, 776 elfcpp::Elf_Word clear) const 777 { 778 for (Segment_list::const_iterator p = this->segment_list_.begin(); 779 p != this->segment_list_.end(); 780 ++p) 781 if (static_cast<elfcpp::PT>((*p)->type()) == type 782 && ((*p)->flags() & set) == set 783 && ((*p)->flags() & clear) == 0) 784 return *p; 785 return NULL; 786 } 787 788 // When we put a .ctors or .dtors section with more than one word into 789 // a .init_array or .fini_array section, we need to reverse the words 790 // in the .ctors/.dtors section. This is because .init_array executes 791 // constructors front to back, where .ctors executes them back to 792 // front, and vice-versa for .fini_array/.dtors. Although we do want 793 // to remap .ctors/.dtors into .init_array/.fini_array because it can 794 // be more efficient, we don't want to change the order in which 795 // constructors/destructors are run. This set just keeps track of 796 // these sections which need to be reversed. It is only changed by 797 // Layout::layout. It should be a private member of Layout, but that 798 // would require layout.h to #include object.h to get the definition 799 // of Section_id. 800 static Unordered_set<Section_id, Section_id_hash> ctors_sections_in_init_array; 801 802 // Return whether OBJECT/SHNDX is a .ctors/.dtors section mapped to a 803 // .init_array/.fini_array section. 804 805 bool 806 Layout::is_ctors_in_init_array(Relobj* relobj, unsigned int shndx) const 807 { 808 return (ctors_sections_in_init_array.find(Section_id(relobj, shndx)) 809 != ctors_sections_in_init_array.end()); 810 } 811 812 // Return the output section to use for section NAME with type TYPE 813 // and section flags FLAGS. NAME must be canonicalized in the string 814 // pool, and NAME_KEY is the key. ORDER is where this should appear 815 // in the output sections. IS_RELRO is true for a relro section. 816 817 Output_section* 818 Layout::get_output_section(const char* name, Stringpool::Key name_key, 819 elfcpp::Elf_Word type, elfcpp::Elf_Xword flags, 820 Output_section_order order, bool is_relro) 821 { 822 elfcpp::Elf_Word lookup_type = type; 823 824 // For lookup purposes, treat INIT_ARRAY, FINI_ARRAY, and 825 // PREINIT_ARRAY like PROGBITS. This ensures that we combine 826 // .init_array, .fini_array, and .preinit_array sections by name 827 // whatever their type in the input file. We do this because the 828 // types are not always right in the input files. 829 if (lookup_type == elfcpp::SHT_INIT_ARRAY 830 || lookup_type == elfcpp::SHT_FINI_ARRAY 831 || lookup_type == elfcpp::SHT_PREINIT_ARRAY) 832 lookup_type = elfcpp::SHT_PROGBITS; 833 834 elfcpp::Elf_Xword lookup_flags = flags; 835 836 // Ignoring SHF_WRITE and SHF_EXECINSTR here means that we combine 837 // read-write with read-only sections. Some other ELF linkers do 838 // not do this. FIXME: Perhaps there should be an option 839 // controlling this. 840 lookup_flags &= ~(elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR); 841 842 const Key key(name_key, std::make_pair(lookup_type, lookup_flags)); 843 const std::pair<Key, Output_section*> v(key, NULL); 844 std::pair<Section_name_map::iterator, bool> ins( 845 this->section_name_map_.insert(v)); 846 847 if (!ins.second) 848 return ins.first->second; 849 else 850 { 851 // This is the first time we've seen this name/type/flags 852 // combination. For compatibility with the GNU linker, we 853 // combine sections with contents and zero flags with sections 854 // with non-zero flags. This is a workaround for cases where 855 // assembler code forgets to set section flags. FIXME: Perhaps 856 // there should be an option to control this. 857 Output_section* os = NULL; 858 859 if (lookup_type == elfcpp::SHT_PROGBITS) 860 { 861 if (flags == 0) 862 { 863 Output_section* same_name = this->find_output_section(name); 864 if (same_name != NULL 865 && (same_name->type() == elfcpp::SHT_PROGBITS 866 || same_name->type() == elfcpp::SHT_INIT_ARRAY 867 || same_name->type() == elfcpp::SHT_FINI_ARRAY 868 || same_name->type() == elfcpp::SHT_PREINIT_ARRAY) 869 && (same_name->flags() & elfcpp::SHF_TLS) == 0) 870 os = same_name; 871 } 872 else if ((flags & elfcpp::SHF_TLS) == 0) 873 { 874 elfcpp::Elf_Xword zero_flags = 0; 875 const Key zero_key(name_key, std::make_pair(lookup_type, 876 zero_flags)); 877 Section_name_map::iterator p = 878 this->section_name_map_.find(zero_key); 879 if (p != this->section_name_map_.end()) 880 os = p->second; 881 } 882 } 883 884 if (os == NULL) 885 os = this->make_output_section(name, type, flags, order, is_relro); 886 887 ins.first->second = os; 888 return os; 889 } 890 } 891 892 // Returns TRUE iff NAME (an input section from RELOBJ) will 893 // be mapped to an output section that should be KEPT. 894 895 bool 896 Layout::keep_input_section(const Relobj* relobj, const char* name) 897 { 898 if (! this->script_options_->saw_sections_clause()) 899 return false; 900 901 Script_sections* ss = this->script_options_->script_sections(); 902 const char* file_name = relobj == NULL ? NULL : relobj->name().c_str(); 903 Output_section** output_section_slot; 904 Script_sections::Section_type script_section_type; 905 bool keep; 906 907 name = ss->output_section_name(file_name, name, &output_section_slot, 908 &script_section_type, &keep, true); 909 return name != NULL && keep; 910 } 911 912 // Clear the input section flags that should not be copied to the 913 // output section. 914 915 elfcpp::Elf_Xword 916 Layout::get_output_section_flags(elfcpp::Elf_Xword input_section_flags) 917 { 918 // Some flags in the input section should not be automatically 919 // copied to the output section. 920 input_section_flags &= ~ (elfcpp::SHF_INFO_LINK 921 | elfcpp::SHF_GROUP 922 | elfcpp::SHF_COMPRESSED 923 | elfcpp::SHF_MERGE 924 | elfcpp::SHF_STRINGS); 925 926 // We only clear the SHF_LINK_ORDER flag in for 927 // a non-relocatable link. 928 if (!parameters->options().relocatable()) 929 input_section_flags &= ~elfcpp::SHF_LINK_ORDER; 930 931 return input_section_flags; 932 } 933 934 // Pick the output section to use for section NAME, in input file 935 // RELOBJ, with type TYPE and flags FLAGS. RELOBJ may be NULL for a 936 // linker created section. IS_INPUT_SECTION is true if we are 937 // choosing an output section for an input section found in a input 938 // file. ORDER is where this section should appear in the output 939 // sections. IS_RELRO is true for a relro section. This will return 940 // NULL if the input section should be discarded. MATCH_INPUT_SPEC 941 // is true if the section name should be matched against input specs 942 // in a linker script. 943 944 Output_section* 945 Layout::choose_output_section(const Relobj* relobj, const char* name, 946 elfcpp::Elf_Word type, elfcpp::Elf_Xword flags, 947 bool is_input_section, Output_section_order order, 948 bool is_relro, bool is_reloc, 949 bool match_input_spec) 950 { 951 // We should not see any input sections after we have attached 952 // sections to segments. 953 gold_assert(!is_input_section || !this->sections_are_attached_); 954 955 flags = this->get_output_section_flags(flags); 956 957 if (this->script_options_->saw_sections_clause() && !is_reloc) 958 { 959 // We are using a SECTIONS clause, so the output section is 960 // chosen based only on the name. 961 962 Script_sections* ss = this->script_options_->script_sections(); 963 const char* file_name = relobj == NULL ? NULL : relobj->name().c_str(); 964 Output_section** output_section_slot; 965 Script_sections::Section_type script_section_type; 966 const char* orig_name = name; 967 bool keep; 968 name = ss->output_section_name(file_name, name, &output_section_slot, 969 &script_section_type, &keep, 970 match_input_spec); 971 972 if (name == NULL) 973 { 974 gold_debug(DEBUG_SCRIPT, _("Unable to create output section '%s' " 975 "because it is not allowed by the " 976 "SECTIONS clause of the linker script"), 977 orig_name); 978 // The SECTIONS clause says to discard this input section. 979 return NULL; 980 } 981 982 // We can only handle script section types ST_NONE and ST_NOLOAD. 983 switch (script_section_type) 984 { 985 case Script_sections::ST_NONE: 986 break; 987 case Script_sections::ST_NOLOAD: 988 flags &= elfcpp::SHF_ALLOC; 989 break; 990 default: 991 gold_unreachable(); 992 } 993 994 // If this is an orphan section--one not mentioned in the linker 995 // script--then OUTPUT_SECTION_SLOT will be NULL, and we do the 996 // default processing below. 997 998 if (output_section_slot != NULL) 999 { 1000 if (*output_section_slot != NULL) 1001 { 1002 (*output_section_slot)->update_flags_for_input_section(flags); 1003 return *output_section_slot; 1004 } 1005 1006 // We don't put sections found in the linker script into 1007 // SECTION_NAME_MAP_. That keeps us from getting confused 1008 // if an orphan section is mapped to a section with the same 1009 // name as one in the linker script. 1010 1011 name = this->namepool_.add(name, false, NULL); 1012 1013 Output_section* os = this->make_output_section(name, type, flags, 1014 order, is_relro); 1015 1016 os->set_found_in_sections_clause(); 1017 1018 // Special handling for NOLOAD sections. 1019 if (script_section_type == Script_sections::ST_NOLOAD) 1020 { 1021 os->set_is_noload(); 1022 1023 // The constructor of Output_section sets addresses of non-ALLOC 1024 // sections to 0 by default. We don't want that for NOLOAD 1025 // sections even if they have no SHF_ALLOC flag. 1026 if ((os->flags() & elfcpp::SHF_ALLOC) == 0 1027 && os->is_address_valid()) 1028 { 1029 gold_assert(os->address() == 0 1030 && !os->is_offset_valid() 1031 && !os->is_data_size_valid()); 1032 os->reset_address_and_file_offset(); 1033 } 1034 } 1035 1036 *output_section_slot = os; 1037 return os; 1038 } 1039 } 1040 1041 // FIXME: Handle SHF_OS_NONCONFORMING somewhere. 1042 1043 size_t len = strlen(name); 1044 std::string uncompressed_name; 1045 1046 // Compressed debug sections should be mapped to the corresponding 1047 // uncompressed section. 1048 if (is_compressed_debug_section(name)) 1049 { 1050 uncompressed_name = 1051 corresponding_uncompressed_section_name(std::string(name, len)); 1052 name = uncompressed_name.c_str(); 1053 len = uncompressed_name.length(); 1054 } 1055 1056 // Turn NAME from the name of the input section into the name of the 1057 // output section. 1058 if (is_input_section 1059 && !this->script_options_->saw_sections_clause() 1060 && !parameters->options().relocatable()) 1061 { 1062 const char *orig_name = name; 1063 name = parameters->target().output_section_name(relobj, name, &len); 1064 if (name == NULL) 1065 name = Layout::output_section_name(relobj, orig_name, &len); 1066 } 1067 1068 Stringpool::Key name_key; 1069 name = this->namepool_.add_with_length(name, len, true, &name_key); 1070 1071 // Find or make the output section. The output section is selected 1072 // based on the section name, type, and flags. 1073 return this->get_output_section(name, name_key, type, flags, order, is_relro); 1074 } 1075 1076 // For incremental links, record the initial fixed layout of a section 1077 // from the base file, and return a pointer to the Output_section. 1078 1079 template<int size, bool big_endian> 1080 Output_section* 1081 Layout::init_fixed_output_section(const char* name, 1082 elfcpp::Shdr<size, big_endian>& shdr) 1083 { 1084 unsigned int sh_type = shdr.get_sh_type(); 1085 1086 // We preserve the layout of PROGBITS, NOBITS, INIT_ARRAY, FINI_ARRAY, 1087 // PRE_INIT_ARRAY, and NOTE sections. 1088 // All others will be created from scratch and reallocated. 1089 if (!can_incremental_update(sh_type)) 1090 return NULL; 1091 1092 // If we're generating a .gdb_index section, we need to regenerate 1093 // it from scratch. 1094 if (parameters->options().gdb_index() 1095 && sh_type == elfcpp::SHT_PROGBITS 1096 && strcmp(name, ".gdb_index") == 0) 1097 return NULL; 1098 1099 typename elfcpp::Elf_types<size>::Elf_Addr sh_addr = shdr.get_sh_addr(); 1100 typename elfcpp::Elf_types<size>::Elf_Off sh_offset = shdr.get_sh_offset(); 1101 typename elfcpp::Elf_types<size>::Elf_WXword sh_size = shdr.get_sh_size(); 1102 typename elfcpp::Elf_types<size>::Elf_WXword sh_flags = shdr.get_sh_flags(); 1103 typename elfcpp::Elf_types<size>::Elf_WXword sh_addralign = 1104 shdr.get_sh_addralign(); 1105 1106 // Make the output section. 1107 Stringpool::Key name_key; 1108 name = this->namepool_.add(name, true, &name_key); 1109 Output_section* os = this->get_output_section(name, name_key, sh_type, 1110 sh_flags, ORDER_INVALID, false); 1111 os->set_fixed_layout(sh_addr, sh_offset, sh_size, sh_addralign); 1112 if (sh_type != elfcpp::SHT_NOBITS) 1113 this->free_list_.remove(sh_offset, sh_offset + sh_size); 1114 return os; 1115 } 1116 1117 // Return the index by which an input section should be ordered. This 1118 // is used to sort some .text sections, for compatibility with GNU ld. 1119 1120 int 1121 Layout::special_ordering_of_input_section(const char* name) 1122 { 1123 // The GNU linker has some special handling for some sections that 1124 // wind up in the .text section. Sections that start with these 1125 // prefixes must appear first, and must appear in the order listed 1126 // here. 1127 static const char* const text_section_sort[] = 1128 { 1129 ".text.unlikely", 1130 ".text.exit", 1131 ".text.startup", 1132 ".text.hot", 1133 ".text.sorted" 1134 }; 1135 1136 for (size_t i = 0; 1137 i < sizeof(text_section_sort) / sizeof(text_section_sort[0]); 1138 i++) 1139 if (is_prefix_of(text_section_sort[i], name)) 1140 return i; 1141 1142 return -1; 1143 } 1144 1145 // Return the output section to use for input section SHNDX, with name 1146 // NAME, with header HEADER, from object OBJECT. RELOC_SHNDX is the 1147 // index of a relocation section which applies to this section, or 0 1148 // if none, or -1U if more than one. RELOC_TYPE is the type of the 1149 // relocation section if there is one. Set *OFF to the offset of this 1150 // input section without the output section. Return NULL if the 1151 // section should be discarded. Set *OFF to -1 if the section 1152 // contents should not be written directly to the output file, but 1153 // will instead receive special handling. 1154 1155 template<int size, bool big_endian> 1156 Output_section* 1157 Layout::layout(Sized_relobj_file<size, big_endian>* object, unsigned int shndx, 1158 const char* name, const elfcpp::Shdr<size, big_endian>& shdr, 1159 unsigned int sh_type, unsigned int reloc_shndx, 1160 unsigned int, off_t* off) 1161 { 1162 *off = 0; 1163 1164 if (!this->include_section(object, name, shdr)) 1165 return NULL; 1166 1167 // In a relocatable link a grouped section must not be combined with 1168 // any other sections. 1169 Output_section* os; 1170 if (parameters->options().relocatable() 1171 && (shdr.get_sh_flags() & elfcpp::SHF_GROUP) != 0) 1172 { 1173 // Some flags in the input section should not be automatically 1174 // copied to the output section. 1175 elfcpp::Elf_Xword flags = (shdr.get_sh_flags() 1176 & ~ elfcpp::SHF_COMPRESSED); 1177 name = this->namepool_.add(name, true, NULL); 1178 os = this->make_output_section(name, sh_type, flags, 1179 ORDER_INVALID, false); 1180 } 1181 else 1182 { 1183 // All ".text.unlikely.*" sections can be moved to a unique 1184 // segment with --text-unlikely-segment option. 1185 bool text_unlikely_segment 1186 = (parameters->options().text_unlikely_segment() 1187 && is_prefix_of(".text.unlikely", 1188 object->section_name(shndx).c_str())); 1189 if (text_unlikely_segment) 1190 { 1191 elfcpp::Elf_Xword flags 1192 = this->get_output_section_flags(shdr.get_sh_flags()); 1193 1194 Stringpool::Key name_key; 1195 const char* os_name = this->namepool_.add(".text.unlikely", true, 1196 &name_key); 1197 os = this->get_output_section(os_name, name_key, sh_type, flags, 1198 ORDER_INVALID, false); 1199 // Map this output section to a unique segment. This is done to 1200 // separate "text" that is not likely to be executed from "text" 1201 // that is likely executed. 1202 os->set_is_unique_segment(); 1203 } 1204 else 1205 { 1206 // Plugins can choose to place one or more subsets of sections in 1207 // unique segments and this is done by mapping these section subsets 1208 // to unique output sections. Check if this section needs to be 1209 // remapped to a unique output section. 1210 Section_segment_map::iterator it 1211 = this->section_segment_map_.find(Const_section_id(object, shndx)); 1212 if (it == this->section_segment_map_.end()) 1213 { 1214 os = this->choose_output_section(object, name, sh_type, 1215 shdr.get_sh_flags(), true, 1216 ORDER_INVALID, false, false, 1217 true); 1218 } 1219 else 1220 { 1221 // We know the name of the output section, directly call 1222 // get_output_section here by-passing choose_output_section. 1223 elfcpp::Elf_Xword flags 1224 = this->get_output_section_flags(shdr.get_sh_flags()); 1225 1226 const char* os_name = it->second->name; 1227 Stringpool::Key name_key; 1228 os_name = this->namepool_.add(os_name, true, &name_key); 1229 os = this->get_output_section(os_name, name_key, sh_type, flags, 1230 ORDER_INVALID, false); 1231 if (!os->is_unique_segment()) 1232 { 1233 os->set_is_unique_segment(); 1234 os->set_extra_segment_flags(it->second->flags); 1235 os->set_segment_alignment(it->second->align); 1236 } 1237 } 1238 } 1239 if (os == NULL) 1240 return NULL; 1241 } 1242 1243 // By default the GNU linker sorts input sections whose names match 1244 // .ctors.*, .dtors.*, .init_array.*, or .fini_array.*. The 1245 // sections are sorted by name. This is used to implement 1246 // constructor priority ordering. We are compatible. When we put 1247 // .ctor sections in .init_array and .dtor sections in .fini_array, 1248 // we must also sort plain .ctor and .dtor sections. 1249 if (!this->script_options_->saw_sections_clause() 1250 && !parameters->options().relocatable() 1251 && (is_prefix_of(".ctors.", name) 1252 || is_prefix_of(".dtors.", name) 1253 || is_prefix_of(".init_array.", name) 1254 || is_prefix_of(".fini_array.", name) 1255 || (parameters->options().ctors_in_init_array() 1256 && (strcmp(name, ".ctors") == 0 1257 || strcmp(name, ".dtors") == 0)))) 1258 os->set_must_sort_attached_input_sections(); 1259 1260 // By default the GNU linker sorts some special text sections ahead 1261 // of others. We are compatible. 1262 if (parameters->options().text_reorder() 1263 && !this->script_options_->saw_sections_clause() 1264 && !this->is_section_ordering_specified() 1265 && !parameters->options().relocatable() 1266 && Layout::special_ordering_of_input_section(name) >= 0) 1267 os->set_must_sort_attached_input_sections(); 1268 1269 // If this is a .ctors or .ctors.* section being mapped to a 1270 // .init_array section, or a .dtors or .dtors.* section being mapped 1271 // to a .fini_array section, we will need to reverse the words if 1272 // there is more than one. Record this section for later. See 1273 // ctors_sections_in_init_array above. 1274 if (!this->script_options_->saw_sections_clause() 1275 && !parameters->options().relocatable() 1276 && shdr.get_sh_size() > size / 8 1277 && (((strcmp(name, ".ctors") == 0 1278 || is_prefix_of(".ctors.", name)) 1279 && strcmp(os->name(), ".init_array") == 0) 1280 || ((strcmp(name, ".dtors") == 0 1281 || is_prefix_of(".dtors.", name)) 1282 && strcmp(os->name(), ".fini_array") == 0))) 1283 ctors_sections_in_init_array.insert(Section_id(object, shndx)); 1284 1285 // FIXME: Handle SHF_LINK_ORDER somewhere. 1286 1287 elfcpp::Elf_Xword orig_flags = os->flags(); 1288 1289 *off = os->add_input_section(this, object, shndx, name, shdr, reloc_shndx, 1290 this->script_options_->saw_sections_clause()); 1291 1292 // If the flags changed, we may have to change the order. 1293 if ((orig_flags & elfcpp::SHF_ALLOC) != 0) 1294 { 1295 orig_flags &= (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR); 1296 elfcpp::Elf_Xword new_flags = 1297 os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR); 1298 if (orig_flags != new_flags) 1299 os->set_order(this->default_section_order(os, false)); 1300 } 1301 1302 this->have_added_input_section_ = true; 1303 1304 return os; 1305 } 1306 1307 // Maps section SECN to SEGMENT s. 1308 void 1309 Layout::insert_section_segment_map(Const_section_id secn, 1310 Unique_segment_info *s) 1311 { 1312 gold_assert(this->unique_segment_for_sections_specified_); 1313 this->section_segment_map_[secn] = s; 1314 } 1315 1316 // Handle a relocation section when doing a relocatable link. 1317 1318 template<int size, bool big_endian> 1319 Output_section* 1320 Layout::layout_reloc(Sized_relobj_file<size, big_endian>*, 1321 unsigned int, 1322 const elfcpp::Shdr<size, big_endian>& shdr, 1323 Output_section* data_section, 1324 Relocatable_relocs* rr) 1325 { 1326 gold_assert(parameters->options().relocatable() 1327 || parameters->options().emit_relocs()); 1328 1329 int sh_type = shdr.get_sh_type(); 1330 1331 std::string name; 1332 if (sh_type == elfcpp::SHT_REL) 1333 name = ".rel"; 1334 else if (sh_type == elfcpp::SHT_RELA) 1335 name = ".rela"; 1336 else 1337 gold_unreachable(); 1338 name += data_section->name(); 1339 1340 // If the output data section already has a reloc section, use that; 1341 // otherwise, make a new one. 1342 Output_section* os = data_section->reloc_section(); 1343 if (os == NULL) 1344 { 1345 const char* n = this->namepool_.add(name.c_str(), true, NULL); 1346 os = this->make_output_section(n, sh_type, shdr.get_sh_flags(), 1347 ORDER_INVALID, false); 1348 os->set_should_link_to_symtab(); 1349 os->set_info_section(data_section); 1350 data_section->set_reloc_section(os); 1351 } 1352 1353 Output_section_data* posd; 1354 if (sh_type == elfcpp::SHT_REL) 1355 { 1356 os->set_entsize(elfcpp::Elf_sizes<size>::rel_size); 1357 posd = new Output_relocatable_relocs<elfcpp::SHT_REL, 1358 size, 1359 big_endian>(rr); 1360 } 1361 else if (sh_type == elfcpp::SHT_RELA) 1362 { 1363 os->set_entsize(elfcpp::Elf_sizes<size>::rela_size); 1364 posd = new Output_relocatable_relocs<elfcpp::SHT_RELA, 1365 size, 1366 big_endian>(rr); 1367 } 1368 else 1369 gold_unreachable(); 1370 1371 os->add_output_section_data(posd); 1372 rr->set_output_data(posd); 1373 1374 return os; 1375 } 1376 1377 // Handle a group section when doing a relocatable link. 1378 1379 template<int size, bool big_endian> 1380 void 1381 Layout::layout_group(Symbol_table* symtab, 1382 Sized_relobj_file<size, big_endian>* object, 1383 unsigned int, 1384 const char* group_section_name, 1385 const char* signature, 1386 const elfcpp::Shdr<size, big_endian>& shdr, 1387 elfcpp::Elf_Word flags, 1388 std::vector<unsigned int>* shndxes) 1389 { 1390 gold_assert(parameters->options().relocatable()); 1391 gold_assert(shdr.get_sh_type() == elfcpp::SHT_GROUP); 1392 group_section_name = this->namepool_.add(group_section_name, true, NULL); 1393 Output_section* os = this->make_output_section(group_section_name, 1394 elfcpp::SHT_GROUP, 1395 shdr.get_sh_flags(), 1396 ORDER_INVALID, false); 1397 1398 // We need to find a symbol with the signature in the symbol table. 1399 // If we don't find one now, we need to look again later. 1400 Symbol* sym = symtab->lookup(signature, NULL); 1401 if (sym != NULL) 1402 os->set_info_symndx(sym); 1403 else 1404 { 1405 // Reserve some space to minimize reallocations. 1406 if (this->group_signatures_.empty()) 1407 this->group_signatures_.reserve(this->number_of_input_files_ * 16); 1408 1409 // We will wind up using a symbol whose name is the signature. 1410 // So just put the signature in the symbol name pool to save it. 1411 signature = symtab->canonicalize_name(signature); 1412 this->group_signatures_.push_back(Group_signature(os, signature)); 1413 } 1414 1415 os->set_should_link_to_symtab(); 1416 os->set_entsize(4); 1417 1418 section_size_type entry_count = 1419 convert_to_section_size_type(shdr.get_sh_size() / 4); 1420 Output_section_data* posd = 1421 new Output_data_group<size, big_endian>(object, entry_count, flags, 1422 shndxes); 1423 os->add_output_section_data(posd); 1424 } 1425 1426 // Special GNU handling of sections name .eh_frame. They will 1427 // normally hold exception frame data as defined by the C++ ABI 1428 // (http://codesourcery.com/cxx-abi/). 1429 1430 template<int size, bool big_endian> 1431 Output_section* 1432 Layout::layout_eh_frame(Sized_relobj_file<size, big_endian>* object, 1433 const unsigned char* symbols, 1434 off_t symbols_size, 1435 const unsigned char* symbol_names, 1436 off_t symbol_names_size, 1437 unsigned int shndx, 1438 const elfcpp::Shdr<size, big_endian>& shdr, 1439 unsigned int reloc_shndx, unsigned int reloc_type, 1440 off_t* off) 1441 { 1442 const unsigned int unwind_section_type = 1443 parameters->target().unwind_section_type(); 1444 1445 gold_assert(shdr.get_sh_type() == elfcpp::SHT_PROGBITS 1446 || shdr.get_sh_type() == unwind_section_type); 1447 gold_assert((shdr.get_sh_flags() & elfcpp::SHF_ALLOC) != 0); 1448 1449 Output_section* os = this->make_eh_frame_section(object); 1450 if (os == NULL) 1451 return NULL; 1452 1453 gold_assert(this->eh_frame_section_ == os); 1454 1455 elfcpp::Elf_Xword orig_flags = os->flags(); 1456 1457 Eh_frame::Eh_frame_section_disposition disp = 1458 Eh_frame::EH_UNRECOGNIZED_SECTION; 1459 if (!parameters->incremental()) 1460 { 1461 disp = this->eh_frame_data_->add_ehframe_input_section(object, 1462 symbols, 1463 symbols_size, 1464 symbol_names, 1465 symbol_names_size, 1466 shndx, 1467 reloc_shndx, 1468 reloc_type); 1469 } 1470 1471 if (disp == Eh_frame::EH_OPTIMIZABLE_SECTION) 1472 { 1473 os->update_flags_for_input_section(shdr.get_sh_flags()); 1474 1475 // A writable .eh_frame section is a RELRO section. 1476 if ((orig_flags & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR)) 1477 != (os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR))) 1478 { 1479 os->set_is_relro(); 1480 os->set_order(ORDER_RELRO); 1481 } 1482 1483 *off = -1; 1484 return os; 1485 } 1486 1487 if (disp == Eh_frame::EH_END_MARKER_SECTION && !this->added_eh_frame_data_) 1488 { 1489 // We found the end marker section, so now we can add the set of 1490 // optimized sections to the output section. We need to postpone 1491 // adding this until we've found a section we can optimize so that 1492 // the .eh_frame section in crtbeginT.o winds up at the start of 1493 // the output section. 1494 os->add_output_section_data(this->eh_frame_data_); 1495 this->added_eh_frame_data_ = true; 1496 } 1497 1498 // We couldn't handle this .eh_frame section for some reason. 1499 // Add it as a normal section. 1500 bool saw_sections_clause = this->script_options_->saw_sections_clause(); 1501 *off = os->add_input_section(this, object, shndx, ".eh_frame", shdr, 1502 reloc_shndx, saw_sections_clause); 1503 this->have_added_input_section_ = true; 1504 1505 if ((orig_flags & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR)) 1506 != (os->flags() & (elfcpp::SHF_WRITE | elfcpp::SHF_EXECINSTR))) 1507 os->set_order(this->default_section_order(os, false)); 1508 1509 return os; 1510 } 1511 1512 void 1513 Layout::finalize_eh_frame_section() 1514 { 1515 // If we never found an end marker section, we need to add the 1516 // optimized eh sections to the output section now. 1517 if (!parameters->incremental() 1518 && this->eh_frame_section_ != NULL 1519 && !this->added_eh_frame_data_) 1520 { 1521 this->eh_frame_section_->add_output_section_data(this->eh_frame_data_); 1522 this->added_eh_frame_data_ = true; 1523 } 1524 } 1525 1526 // Create and return the magic .eh_frame section. Create 1527 // .eh_frame_hdr also if appropriate. OBJECT is the object with the 1528 // input .eh_frame section; it may be NULL. 1529 1530 Output_section* 1531 Layout::make_eh_frame_section(const Relobj* object) 1532 { 1533 const unsigned int unwind_section_type = 1534 parameters->target().unwind_section_type(); 1535 1536 Output_section* os = this->choose_output_section(object, ".eh_frame", 1537 unwind_section_type, 1538 elfcpp::SHF_ALLOC, false, 1539 ORDER_EHFRAME, false, false, 1540 false); 1541 if (os == NULL) 1542 return NULL; 1543 1544 if (this->eh_frame_section_ == NULL) 1545 { 1546 this->eh_frame_section_ = os; 1547 this->eh_frame_data_ = new Eh_frame(); 1548 1549 // For incremental linking, we do not optimize .eh_frame sections 1550 // or create a .eh_frame_hdr section. 1551 if (parameters->options().eh_frame_hdr() && !parameters->incremental()) 1552 { 1553 Output_section* hdr_os = 1554 this->choose_output_section(NULL, ".eh_frame_hdr", 1555 unwind_section_type, 1556 elfcpp::SHF_ALLOC, false, 1557 ORDER_EHFRAME, false, false, 1558 false); 1559 1560 if (hdr_os != NULL) 1561 { 1562 Eh_frame_hdr* hdr_posd = new Eh_frame_hdr(os, 1563 this->eh_frame_data_); 1564 hdr_os->add_output_section_data(hdr_posd); 1565 1566 hdr_os->set_after_input_sections(); 1567 1568 if (!this->script_options_->saw_phdrs_clause()) 1569 { 1570 Output_segment* hdr_oseg; 1571 hdr_oseg = this->make_output_segment(elfcpp::PT_GNU_EH_FRAME, 1572 elfcpp::PF_R); 1573 hdr_oseg->add_output_section_to_nonload(hdr_os, 1574 elfcpp::PF_R); 1575 } 1576 1577 this->eh_frame_data_->set_eh_frame_hdr(hdr_posd); 1578 } 1579 } 1580 } 1581 1582 return os; 1583 } 1584 1585 // Add an exception frame for a PLT. This is called from target code. 1586 1587 void 1588 Layout::add_eh_frame_for_plt(Output_data* plt, const unsigned char* cie_data, 1589 size_t cie_length, const unsigned char* fde_data, 1590 size_t fde_length) 1591 { 1592 if (parameters->incremental()) 1593 { 1594 // FIXME: Maybe this could work some day.... 1595 return; 1596 } 1597 Output_section* os = this->make_eh_frame_section(NULL); 1598 if (os == NULL) 1599 return; 1600 this->eh_frame_data_->add_ehframe_for_plt(plt, cie_data, cie_length, 1601 fde_data, fde_length); 1602 if (!this->added_eh_frame_data_) 1603 { 1604 os->add_output_section_data(this->eh_frame_data_); 1605 this->added_eh_frame_data_ = true; 1606 } 1607 } 1608 1609 // Remove all post-map .eh_frame information for a PLT. 1610 1611 void 1612 Layout::remove_eh_frame_for_plt(Output_data* plt, const unsigned char* cie_data, 1613 size_t cie_length) 1614 { 1615 if (parameters->incremental()) 1616 { 1617 // FIXME: Maybe this could work some day.... 1618 return; 1619 } 1620 this->eh_frame_data_->remove_ehframe_for_plt(plt, cie_data, cie_length); 1621 } 1622 1623 // Scan a .debug_info or .debug_types section, and add summary 1624 // information to the .gdb_index section. 1625 1626 template<int size, bool big_endian> 1627 void 1628 Layout::add_to_gdb_index(bool is_type_unit, 1629 Sized_relobj<size, big_endian>* object, 1630 const unsigned char* symbols, 1631 off_t symbols_size, 1632 unsigned int shndx, 1633 unsigned int reloc_shndx, 1634 unsigned int reloc_type) 1635 { 1636 if (this->gdb_index_data_ == NULL) 1637 { 1638 Output_section* os = this->choose_output_section(NULL, ".gdb_index", 1639 elfcpp::SHT_PROGBITS, 0, 1640 false, ORDER_INVALID, 1641 false, false, false); 1642 if (os == NULL) 1643 return; 1644 1645 this->gdb_index_data_ = new Gdb_index(os); 1646 os->add_output_section_data(this->gdb_index_data_); 1647 os->set_after_input_sections(); 1648 } 1649 1650 this->gdb_index_data_->scan_debug_info(is_type_unit, object, symbols, 1651 symbols_size, shndx, reloc_shndx, 1652 reloc_type); 1653 } 1654 1655 // Add POSD to an output section using NAME, TYPE, and FLAGS. Return 1656 // the output section. 1657 1658 Output_section* 1659 Layout::add_output_section_data(const char* name, elfcpp::Elf_Word type, 1660 elfcpp::Elf_Xword flags, 1661 Output_section_data* posd, 1662 Output_section_order order, bool is_relro) 1663 { 1664 Output_section* os = this->choose_output_section(NULL, name, type, flags, 1665 false, order, is_relro, 1666 false, false); 1667 if (os != NULL) 1668 os->add_output_section_data(posd); 1669 return os; 1670 } 1671 1672 // Map section flags to segment flags. 1673 1674 elfcpp::Elf_Word 1675 Layout::section_flags_to_segment(elfcpp::Elf_Xword flags) 1676 { 1677 elfcpp::Elf_Word ret = elfcpp::PF_R; 1678 if ((flags & elfcpp::SHF_WRITE) != 0) 1679 ret |= elfcpp::PF_W; 1680 if ((flags & elfcpp::SHF_EXECINSTR) != 0) 1681 ret |= elfcpp::PF_X; 1682 return ret; 1683 } 1684 1685 // Make a new Output_section, and attach it to segments as 1686 // appropriate. ORDER is the order in which this section should 1687 // appear in the output segment. IS_RELRO is true if this is a relro 1688 // (read-only after relocations) section. 1689 1690 Output_section* 1691 Layout::make_output_section(const char* name, elfcpp::Elf_Word type, 1692 elfcpp::Elf_Xword flags, 1693 Output_section_order order, bool is_relro) 1694 { 1695 Output_section* os; 1696 if ((flags & elfcpp::SHF_ALLOC) == 0 1697 && strcmp(parameters->options().compress_debug_sections(), "none") != 0 1698 && is_compressible_debug_section(name)) 1699 os = new Output_compressed_section(¶meters->options(), name, type, 1700 flags); 1701 else if ((flags & elfcpp::SHF_ALLOC) == 0 1702 && parameters->options().strip_debug_non_line() 1703 && strcmp(".debug_abbrev", name) == 0) 1704 { 1705 os = this->debug_abbrev_ = new Output_reduced_debug_abbrev_section( 1706 name, type, flags); 1707 if (this->debug_info_) 1708 this->debug_info_->set_abbreviations(this->debug_abbrev_); 1709 } 1710 else if ((flags & elfcpp::SHF_ALLOC) == 0 1711 && parameters->options().strip_debug_non_line() 1712 && strcmp(".debug_info", name) == 0) 1713 { 1714 os = this->debug_info_ = new Output_reduced_debug_info_section( 1715 name, type, flags); 1716 if (this->debug_abbrev_) 1717 this->debug_info_->set_abbreviations(this->debug_abbrev_); 1718 } 1719 else 1720 { 1721 // Sometimes .init_array*, .preinit_array* and .fini_array* do 1722 // not have correct section types. Force them here. 1723 if (type == elfcpp::SHT_PROGBITS) 1724 { 1725 if (is_prefix_of(".init_array", name)) 1726 type = elfcpp::SHT_INIT_ARRAY; 1727 else if (is_prefix_of(".preinit_array", name)) 1728 type = elfcpp::SHT_PREINIT_ARRAY; 1729 else if (is_prefix_of(".fini_array", name)) 1730 type = elfcpp::SHT_FINI_ARRAY; 1731 } 1732 1733 // FIXME: const_cast is ugly. 1734 Target* target = const_cast<Target*>(¶meters->target()); 1735 os = target->make_output_section(name, type, flags); 1736 } 1737 1738 // With -z relro, we have to recognize the special sections by name. 1739 // There is no other way. 1740 bool is_relro_local = false; 1741 if (!this->script_options_->saw_sections_clause() 1742 && parameters->options().relro() 1743 && (flags & elfcpp::SHF_ALLOC) != 0 1744 && (flags & elfcpp::SHF_WRITE) != 0) 1745 { 1746 if (type == elfcpp::SHT_PROGBITS) 1747 { 1748 if ((flags & elfcpp::SHF_TLS) != 0) 1749 is_relro = true; 1750 else if (strcmp(name, ".data.rel.ro") == 0) 1751 is_relro = true; 1752 else if (strcmp(name, ".data.rel.ro.local") == 0) 1753 { 1754 is_relro = true; 1755 is_relro_local = true; 1756 } 1757 else if (strcmp(name, ".ctors") == 0 1758 || strcmp(name, ".dtors") == 0 1759 || strcmp(name, ".jcr") == 0) 1760 is_relro = true; 1761 } 1762 else if (type == elfcpp::SHT_INIT_ARRAY 1763 || type == elfcpp::SHT_FINI_ARRAY 1764 || type == elfcpp::SHT_PREINIT_ARRAY) 1765 is_relro = true; 1766 } 1767 1768 if (is_relro) 1769 os->set_is_relro(); 1770 1771 if (order == ORDER_INVALID && (flags & elfcpp::SHF_ALLOC) != 0) 1772 order = this->default_section_order(os, is_relro_local); 1773 1774 os->set_order(order); 1775 1776 parameters->target().new_output_section(os); 1777 1778 this->section_list_.push_back(os); 1779 1780 // The GNU linker by default sorts some sections by priority, so we 1781 // do the same. We need to know that this might happen before we 1782 // attach any input sections. 1783 if (!this->script_options_->saw_sections_clause() 1784 && !parameters->options().relocatable() 1785 && (strcmp(name, ".init_array") == 0 1786 || strcmp(name, ".fini_array") == 0 1787 || (!parameters->options().ctors_in_init_array() 1788 && (strcmp(name, ".ctors") == 0 1789 || strcmp(name, ".dtors") == 0)))) 1790 os->set_may_sort_attached_input_sections(); 1791 1792 // The GNU linker by default sorts .text.{unlikely,exit,startup,hot} 1793 // sections before other .text sections. We are compatible. We 1794 // need to know that this might happen before we attach any input 1795 // sections. 1796 if (parameters->options().text_reorder() 1797 && !this->script_options_->saw_sections_clause() 1798 && !this->is_section_ordering_specified() 1799 && !parameters->options().relocatable() 1800 && strcmp(name, ".text") == 0) 1801 os->set_may_sort_attached_input_sections(); 1802 1803 // GNU linker sorts section by name with --sort-section=name. 1804 if (strcmp(parameters->options().sort_section(), "name") == 0) 1805 os->set_must_sort_attached_input_sections(); 1806 1807 // Check for .stab*str sections, as .stab* sections need to link to 1808 // them. 1809 if (type == elfcpp::SHT_STRTAB 1810 && !this->have_stabstr_section_ 1811 && strncmp(name, ".stab", 5) == 0 1812 && strcmp(name + strlen(name) - 3, "str") == 0) 1813 this->have_stabstr_section_ = true; 1814 1815 // During a full incremental link, we add patch space to most 1816 // PROGBITS and NOBITS sections. Flag those that may be 1817 // arbitrarily padded. 1818 if ((type == elfcpp::SHT_PROGBITS || type == elfcpp::SHT_NOBITS) 1819 && order != ORDER_INTERP 1820 && order != ORDER_INIT 1821 && order != ORDER_PLT 1822 && order != ORDER_FINI 1823 && order != ORDER_RELRO_LAST 1824 && order != ORDER_NON_RELRO_FIRST 1825 && strcmp(name, ".eh_frame") != 0 1826 && strcmp(name, ".ctors") != 0 1827 && strcmp(name, ".dtors") != 0 1828 && strcmp(name, ".jcr") != 0) 1829 { 1830 os->set_is_patch_space_allowed(); 1831 1832 // Certain sections require "holes" to be filled with 1833 // specific fill patterns. These fill patterns may have 1834 // a minimum size, so we must prevent allocations from the 1835 // free list that leave a hole smaller than the minimum. 1836 if (strcmp(name, ".debug_info") == 0) 1837 os->set_free_space_fill(new Output_fill_debug_info(false)); 1838 else if (strcmp(name, ".debug_types") == 0) 1839 os->set_free_space_fill(new Output_fill_debug_info(true)); 1840 else if (strcmp(name, ".debug_line") == 0) 1841 os->set_free_space_fill(new Output_fill_debug_line()); 1842 } 1843 1844 // If we have already attached the sections to segments, then we 1845 // need to attach this one now. This happens for sections created 1846 // directly by the linker. 1847 if (this->sections_are_attached_) 1848 this->attach_section_to_segment(¶meters->target(), os); 1849 1850 return os; 1851 } 1852 1853 // Return the default order in which a section should be placed in an 1854 // output segment. This function captures a lot of the ideas in 1855 // ld/scripttempl/elf.sc in the GNU linker. Note that the order of a 1856 // linker created section is normally set when the section is created; 1857 // this function is used for input sections. 1858 1859 Output_section_order 1860 Layout::default_section_order(Output_section* os, bool is_relro_local) 1861 { 1862 gold_assert((os->flags() & elfcpp::SHF_ALLOC) != 0); 1863 bool is_write = (os->flags() & elfcpp::SHF_WRITE) != 0; 1864 bool is_execinstr = (os->flags() & elfcpp::SHF_EXECINSTR) != 0; 1865 bool is_bss = false; 1866 1867 switch (os->type()) 1868 { 1869 default: 1870 case elfcpp::SHT_PROGBITS: 1871 break; 1872 case elfcpp::SHT_NOBITS: 1873 is_bss = true; 1874 break; 1875 case elfcpp::SHT_RELA: 1876 case elfcpp::SHT_REL: 1877 if (!is_write) 1878 return ORDER_DYNAMIC_RELOCS; 1879 break; 1880 case elfcpp::SHT_HASH: 1881 case elfcpp::SHT_DYNAMIC: 1882 case elfcpp::SHT_SHLIB: 1883 case elfcpp::SHT_DYNSYM: 1884 case elfcpp::SHT_GNU_HASH: 1885 case elfcpp::SHT_GNU_verdef: 1886 case elfcpp::SHT_GNU_verneed: 1887 case elfcpp::SHT_GNU_versym: 1888 if (!is_write) 1889 return ORDER_DYNAMIC_LINKER; 1890 break; 1891 case elfcpp::SHT_NOTE: 1892 return is_write ? ORDER_RW_NOTE : ORDER_RO_NOTE; 1893 } 1894 1895 if ((os->flags() & elfcpp::SHF_TLS) != 0) 1896 return is_bss ? ORDER_TLS_BSS : ORDER_TLS_DATA; 1897 1898 if (!is_bss && !is_write) 1899 { 1900 if (is_execinstr) 1901 { 1902 if (strcmp(os->name(), ".init") == 0) 1903 return ORDER_INIT; 1904 else if (strcmp(os->name(), ".fini") == 0) 1905 return ORDER_FINI; 1906 else if (parameters->options().keep_text_section_prefix()) 1907 { 1908 // -z,keep-text-section-prefix introduces additional 1909 // output sections. 1910 if (strcmp(os->name(), ".text.hot") == 0) 1911 return ORDER_TEXT_HOT; 1912 else if (strcmp(os->name(), ".text.startup") == 0) 1913 return ORDER_TEXT_STARTUP; 1914 else if (strcmp(os->name(), ".text.exit") == 0) 1915 return ORDER_TEXT_EXIT; 1916 else if (strcmp(os->name(), ".text.unlikely") == 0) 1917 return ORDER_TEXT_UNLIKELY; 1918 } 1919 } 1920 return is_execinstr ? ORDER_TEXT : ORDER_READONLY; 1921 } 1922 1923 if (os->is_relro()) 1924 return is_relro_local ? ORDER_RELRO_LOCAL : ORDER_RELRO; 1925 1926 if (os->is_small_section()) 1927 return is_bss ? ORDER_SMALL_BSS : ORDER_SMALL_DATA; 1928 if (os->is_large_section()) 1929 return is_bss ? ORDER_LARGE_BSS : ORDER_LARGE_DATA; 1930 1931 return is_bss ? ORDER_BSS : ORDER_DATA; 1932 } 1933 1934 // Attach output sections to segments. This is called after we have 1935 // seen all the input sections. 1936 1937 void 1938 Layout::attach_sections_to_segments(const Target* target) 1939 { 1940 for (Section_list::iterator p = this->section_list_.begin(); 1941 p != this->section_list_.end(); 1942 ++p) 1943 this->attach_section_to_segment(target, *p); 1944 1945 this->sections_are_attached_ = true; 1946 } 1947 1948 // Attach an output section to a segment. 1949 1950 void 1951 Layout::attach_section_to_segment(const Target* target, Output_section* os) 1952 { 1953 if ((os->flags() & elfcpp::SHF_ALLOC) == 0) 1954 this->unattached_section_list_.push_back(os); 1955 else 1956 this->attach_allocated_section_to_segment(target, os); 1957 } 1958 1959 // Attach an allocated output section to a segment. 1960 1961 void 1962 Layout::attach_allocated_section_to_segment(const Target* target, 1963 Output_section* os) 1964 { 1965 elfcpp::Elf_Xword flags = os->flags(); 1966 gold_assert((flags & elfcpp::SHF_ALLOC) != 0); 1967 1968 if (parameters->options().relocatable()) 1969 return; 1970 1971 // If we have a SECTIONS clause, we can't handle the attachment to 1972 // segments until after we've seen all the sections. 1973 if (this->script_options_->saw_sections_clause()) 1974 return; 1975 1976 gold_assert(!this->script_options_->saw_phdrs_clause()); 1977 1978 // This output section goes into a PT_LOAD segment. 1979 1980 elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags); 1981 1982 // If this output section's segment has extra flags that need to be set, 1983 // coming from a linker plugin, do that. 1984 seg_flags |= os->extra_segment_flags(); 1985 1986 // Check for --section-start. 1987 uint64_t addr; 1988 bool is_address_set = parameters->options().section_start(os->name(), &addr); 1989 1990 // In general the only thing we really care about for PT_LOAD 1991 // segments is whether or not they are writable or executable, 1992 // so that is how we search for them. 1993 // Large data sections also go into their own PT_LOAD segment. 1994 // People who need segments sorted on some other basis will 1995 // have to use a linker script. 1996 1997 Segment_list::const_iterator p; 1998 if (!os->is_unique_segment()) 1999 { 2000 for (p = this->segment_list_.begin(); 2001 p != this->segment_list_.end(); 2002 ++p) 2003 { 2004 if ((*p)->type() != elfcpp::PT_LOAD) 2005 continue; 2006 if ((*p)->is_unique_segment()) 2007 continue; 2008 if (!parameters->options().omagic() 2009 && ((*p)->flags() & elfcpp::PF_W) != (seg_flags & elfcpp::PF_W)) 2010 continue; 2011 if ((target->isolate_execinstr() || parameters->options().rosegment()) 2012 && ((*p)->flags() & elfcpp::PF_X) != (seg_flags & elfcpp::PF_X)) 2013 continue; 2014 // If -Tbss was specified, we need to separate the data and BSS 2015 // segments. 2016 if (parameters->options().user_set_Tbss()) 2017 { 2018 if ((os->type() == elfcpp::SHT_NOBITS) 2019 == (*p)->has_any_data_sections()) 2020 continue; 2021 } 2022 if (os->is_large_data_section() && !(*p)->is_large_data_segment()) 2023 continue; 2024 2025 if (is_address_set) 2026 { 2027 if ((*p)->are_addresses_set()) 2028 continue; 2029 2030 (*p)->add_initial_output_data(os); 2031 (*p)->update_flags_for_output_section(seg_flags); 2032 (*p)->set_addresses(addr, addr); 2033 break; 2034 } 2035 2036 (*p)->add_output_section_to_load(this, os, seg_flags); 2037 break; 2038 } 2039 } 2040 2041 if (p == this->segment_list_.end() 2042 || os->is_unique_segment()) 2043 { 2044 Output_segment* oseg = this->make_output_segment(elfcpp::PT_LOAD, 2045 seg_flags); 2046 if (os->is_large_data_section()) 2047 oseg->set_is_large_data_segment(); 2048 oseg->add_output_section_to_load(this, os, seg_flags); 2049 if (is_address_set) 2050 oseg->set_addresses(addr, addr); 2051 // Check if segment should be marked unique. For segments marked 2052 // unique by linker plugins, set the new alignment if specified. 2053 if (os->is_unique_segment()) 2054 { 2055 oseg->set_is_unique_segment(); 2056 if (os->segment_alignment() != 0) 2057 oseg->set_minimum_p_align(os->segment_alignment()); 2058 } 2059 } 2060 2061 // If we see a loadable SHT_NOTE section, we create a PT_NOTE 2062 // segment. 2063 if (os->type() == elfcpp::SHT_NOTE) 2064 { 2065 // See if we already have an equivalent PT_NOTE segment. 2066 for (p = this->segment_list_.begin(); 2067 p != segment_list_.end(); 2068 ++p) 2069 { 2070 if ((*p)->type() == elfcpp::PT_NOTE 2071 && (((*p)->flags() & elfcpp::PF_W) 2072 == (seg_flags & elfcpp::PF_W))) 2073 { 2074 (*p)->add_output_section_to_nonload(os, seg_flags); 2075 break; 2076 } 2077 } 2078 2079 if (p == this->segment_list_.end()) 2080 { 2081 Output_segment* oseg = this->make_output_segment(elfcpp::PT_NOTE, 2082 seg_flags); 2083 oseg->add_output_section_to_nonload(os, seg_flags); 2084 } 2085 } 2086 2087 // If we see a loadable SHF_TLS section, we create a PT_TLS 2088 // segment. There can only be one such segment. 2089 if ((flags & elfcpp::SHF_TLS) != 0) 2090 { 2091 if (this->tls_segment_ == NULL) 2092 this->make_output_segment(elfcpp::PT_TLS, seg_flags); 2093 this->tls_segment_->add_output_section_to_nonload(os, seg_flags); 2094 } 2095 2096 // If -z relro is in effect, and we see a relro section, we create a 2097 // PT_GNU_RELRO segment. There can only be one such segment. 2098 if (os->is_relro() && parameters->options().relro()) 2099 { 2100 gold_assert(seg_flags == (elfcpp::PF_R | elfcpp::PF_W)); 2101 if (this->relro_segment_ == NULL) 2102 this->make_output_segment(elfcpp::PT_GNU_RELRO, seg_flags); 2103 this->relro_segment_->add_output_section_to_nonload(os, seg_flags); 2104 } 2105 2106 // If we see a section named .interp, put it into a PT_INTERP 2107 // segment. This seems broken to me, but this is what GNU ld does, 2108 // and glibc expects it. 2109 if (strcmp(os->name(), ".interp") == 0 2110 && !this->script_options_->saw_phdrs_clause()) 2111 { 2112 if (this->interp_segment_ == NULL) 2113 this->make_output_segment(elfcpp::PT_INTERP, seg_flags); 2114 else 2115 gold_warning(_("multiple '.interp' sections in input files " 2116 "may cause confusing PT_INTERP segment")); 2117 this->interp_segment_->add_output_section_to_nonload(os, seg_flags); 2118 } 2119 } 2120 2121 // Make an output section for a script. 2122 2123 Output_section* 2124 Layout::make_output_section_for_script( 2125 const char* name, 2126 Script_sections::Section_type section_type) 2127 { 2128 name = this->namepool_.add(name, false, NULL); 2129 elfcpp::Elf_Xword sh_flags = elfcpp::SHF_ALLOC; 2130 if (section_type == Script_sections::ST_NOLOAD) 2131 sh_flags = 0; 2132 Output_section* os = this->make_output_section(name, elfcpp::SHT_PROGBITS, 2133 sh_flags, ORDER_INVALID, 2134 false); 2135 os->set_found_in_sections_clause(); 2136 if (section_type == Script_sections::ST_NOLOAD) 2137 os->set_is_noload(); 2138 return os; 2139 } 2140 2141 // Return the number of segments we expect to see. 2142 2143 size_t 2144 Layout::expected_segment_count() const 2145 { 2146 size_t ret = this->segment_list_.size(); 2147 2148 // If we didn't see a SECTIONS clause in a linker script, we should 2149 // already have the complete list of segments. Otherwise we ask the 2150 // SECTIONS clause how many segments it expects, and add in the ones 2151 // we already have (PT_GNU_STACK, PT_GNU_EH_FRAME, etc.) 2152 2153 if (!this->script_options_->saw_sections_clause()) 2154 return ret; 2155 else 2156 { 2157 const Script_sections* ss = this->script_options_->script_sections(); 2158 return ret + ss->expected_segment_count(this); 2159 } 2160 } 2161 2162 // Handle the .note.GNU-stack section at layout time. SEEN_GNU_STACK 2163 // is whether we saw a .note.GNU-stack section in the object file. 2164 // GNU_STACK_FLAGS is the section flags. The flags give the 2165 // protection required for stack memory. We record this in an 2166 // executable as a PT_GNU_STACK segment. If an object file does not 2167 // have a .note.GNU-stack segment, we must assume that it is an old 2168 // object. On some targets that will force an executable stack. 2169 2170 void 2171 Layout::layout_gnu_stack(bool seen_gnu_stack, uint64_t gnu_stack_flags, 2172 const Object* obj) 2173 { 2174 if (!seen_gnu_stack) 2175 { 2176 this->input_without_gnu_stack_note_ = true; 2177 if (parameters->options().warn_execstack() 2178 && parameters->target().is_default_stack_executable()) 2179 gold_warning(_("%s: missing .note.GNU-stack section" 2180 " implies executable stack"), 2181 obj->name().c_str()); 2182 } 2183 else 2184 { 2185 this->input_with_gnu_stack_note_ = true; 2186 if ((gnu_stack_flags & elfcpp::SHF_EXECINSTR) != 0) 2187 { 2188 this->input_requires_executable_stack_ = true; 2189 if (parameters->options().warn_execstack()) 2190 gold_warning(_("%s: requires executable stack"), 2191 obj->name().c_str()); 2192 } 2193 } 2194 } 2195 2196 // Read a value with given size and endianness. 2197 2198 static inline uint64_t 2199 read_sized_value(size_t size, const unsigned char* buf, bool is_big_endian, 2200 const Object* object) 2201 { 2202 uint64_t val = 0; 2203 if (size == 4) 2204 { 2205 if (is_big_endian) 2206 val = elfcpp::Swap<32, true>::readval(buf); 2207 else 2208 val = elfcpp::Swap<32, false>::readval(buf); 2209 } 2210 else if (size == 8) 2211 { 2212 if (is_big_endian) 2213 val = elfcpp::Swap<64, true>::readval(buf); 2214 else 2215 val = elfcpp::Swap<64, false>::readval(buf); 2216 } 2217 else 2218 { 2219 gold_warning(_("%s: in .note.gnu.property section, " 2220 "pr_datasz must be 4 or 8"), 2221 object->name().c_str()); 2222 } 2223 return val; 2224 } 2225 2226 // Write a value with given size and endianness. 2227 2228 static inline void 2229 write_sized_value(uint64_t value, size_t size, unsigned char* buf, 2230 bool is_big_endian) 2231 { 2232 if (size == 4) 2233 { 2234 if (is_big_endian) 2235 elfcpp::Swap<32, true>::writeval(buf, static_cast<uint32_t>(value)); 2236 else 2237 elfcpp::Swap<32, false>::writeval(buf, static_cast<uint32_t>(value)); 2238 } 2239 else if (size == 8) 2240 { 2241 if (is_big_endian) 2242 elfcpp::Swap<64, true>::writeval(buf, value); 2243 else 2244 elfcpp::Swap<64, false>::writeval(buf, value); 2245 } 2246 else 2247 { 2248 // We will have already complained about this. 2249 } 2250 } 2251 2252 // Handle the .note.gnu.property section at layout time. 2253 2254 void 2255 Layout::layout_gnu_property(unsigned int note_type, 2256 unsigned int pr_type, 2257 size_t pr_datasz, 2258 const unsigned char* pr_data, 2259 const Object* object) 2260 { 2261 // We currently support only the one note type. 2262 gold_assert(note_type == elfcpp::NT_GNU_PROPERTY_TYPE_0); 2263 2264 if (pr_type >= elfcpp::GNU_PROPERTY_LOPROC 2265 && pr_type < elfcpp::GNU_PROPERTY_HIPROC) 2266 { 2267 // Target-dependent property value; call the target to record. 2268 const int size = parameters->target().get_size(); 2269 const bool is_big_endian = parameters->target().is_big_endian(); 2270 if (size == 32) 2271 { 2272 if (is_big_endian) 2273 { 2274 #ifdef HAVE_TARGET_32_BIG 2275 parameters->sized_target<32, true>()-> 2276 record_gnu_property(note_type, pr_type, pr_datasz, pr_data, 2277 object); 2278 #else 2279 gold_unreachable(); 2280 #endif 2281 } 2282 else 2283 { 2284 #ifdef HAVE_TARGET_32_LITTLE 2285 parameters->sized_target<32, false>()-> 2286 record_gnu_property(note_type, pr_type, pr_datasz, pr_data, 2287 object); 2288 #else 2289 gold_unreachable(); 2290 #endif 2291 } 2292 } 2293 else if (size == 64) 2294 { 2295 if (is_big_endian) 2296 { 2297 #ifdef HAVE_TARGET_64_BIG 2298 parameters->sized_target<64, true>()-> 2299 record_gnu_property(note_type, pr_type, pr_datasz, pr_data, 2300 object); 2301 #else 2302 gold_unreachable(); 2303 #endif 2304 } 2305 else 2306 { 2307 #ifdef HAVE_TARGET_64_LITTLE 2308 parameters->sized_target<64, false>()-> 2309 record_gnu_property(note_type, pr_type, pr_datasz, pr_data, 2310 object); 2311 #else 2312 gold_unreachable(); 2313 #endif 2314 } 2315 } 2316 else 2317 gold_unreachable(); 2318 return; 2319 } 2320 2321 Gnu_properties::iterator pprop = this->gnu_properties_.find(pr_type); 2322 if (pprop == this->gnu_properties_.end()) 2323 { 2324 Gnu_property prop; 2325 prop.pr_datasz = pr_datasz; 2326 prop.pr_data = new unsigned char[pr_datasz]; 2327 memcpy(prop.pr_data, pr_data, pr_datasz); 2328 this->gnu_properties_[pr_type] = prop; 2329 } 2330 else 2331 { 2332 const bool is_big_endian = parameters->target().is_big_endian(); 2333 switch (pr_type) 2334 { 2335 case elfcpp::GNU_PROPERTY_STACK_SIZE: 2336 // Record the maximum value seen. 2337 { 2338 uint64_t val1 = read_sized_value(pprop->second.pr_datasz, 2339 pprop->second.pr_data, 2340 is_big_endian, object); 2341 uint64_t val2 = read_sized_value(pr_datasz, pr_data, 2342 is_big_endian, object); 2343 if (val2 > val1) 2344 write_sized_value(val2, pprop->second.pr_datasz, 2345 pprop->second.pr_data, is_big_endian); 2346 } 2347 break; 2348 case elfcpp::GNU_PROPERTY_NO_COPY_ON_PROTECTED: 2349 // No data to merge. 2350 break; 2351 default: 2352 gold_warning(_("%s: unknown program property type %d " 2353 "in .note.gnu.property section"), 2354 object->name().c_str(), pr_type); 2355 } 2356 } 2357 } 2358 2359 // Merge per-object properties with program properties. 2360 // This lets the target identify objects that are missing certain 2361 // properties, in cases where properties must be ANDed together. 2362 2363 void 2364 Layout::merge_gnu_properties(const Object* object) 2365 { 2366 const int size = parameters->target().get_size(); 2367 const bool is_big_endian = parameters->target().is_big_endian(); 2368 if (size == 32) 2369 { 2370 if (is_big_endian) 2371 { 2372 #ifdef HAVE_TARGET_32_BIG 2373 parameters->sized_target<32, true>()->merge_gnu_properties(object); 2374 #else 2375 gold_unreachable(); 2376 #endif 2377 } 2378 else 2379 { 2380 #ifdef HAVE_TARGET_32_LITTLE 2381 parameters->sized_target<32, false>()->merge_gnu_properties(object); 2382 #else 2383 gold_unreachable(); 2384 #endif 2385 } 2386 } 2387 else if (size == 64) 2388 { 2389 if (is_big_endian) 2390 { 2391 #ifdef HAVE_TARGET_64_BIG 2392 parameters->sized_target<64, true>()->merge_gnu_properties(object); 2393 #else 2394 gold_unreachable(); 2395 #endif 2396 } 2397 else 2398 { 2399 #ifdef HAVE_TARGET_64_LITTLE 2400 parameters->sized_target<64, false>()->merge_gnu_properties(object); 2401 #else 2402 gold_unreachable(); 2403 #endif 2404 } 2405 } 2406 else 2407 gold_unreachable(); 2408 } 2409 2410 // Add a target-specific property for the output .note.gnu.property section. 2411 2412 void 2413 Layout::add_gnu_property(unsigned int note_type, 2414 unsigned int pr_type, 2415 size_t pr_datasz, 2416 const unsigned char* pr_data) 2417 { 2418 gold_assert(note_type == elfcpp::NT_GNU_PROPERTY_TYPE_0); 2419 2420 Gnu_property prop; 2421 prop.pr_datasz = pr_datasz; 2422 prop.pr_data = new unsigned char[pr_datasz]; 2423 memcpy(prop.pr_data, pr_data, pr_datasz); 2424 this->gnu_properties_[pr_type] = prop; 2425 } 2426 2427 // Create automatic note sections. 2428 2429 void 2430 Layout::create_notes() 2431 { 2432 this->create_gnu_properties_note(); 2433 this->create_gold_note(); 2434 this->create_stack_segment(); 2435 this->create_build_id(); 2436 } 2437 2438 // Create the dynamic sections which are needed before we read the 2439 // relocs. 2440 2441 void 2442 Layout::create_initial_dynamic_sections(Symbol_table* symtab) 2443 { 2444 if (parameters->doing_static_link()) 2445 return; 2446 2447 this->dynamic_section_ = this->choose_output_section(NULL, ".dynamic", 2448 elfcpp::SHT_DYNAMIC, 2449 (elfcpp::SHF_ALLOC 2450 | elfcpp::SHF_WRITE), 2451 false, ORDER_RELRO, 2452 true, false, false); 2453 2454 // A linker script may discard .dynamic, so check for NULL. 2455 if (this->dynamic_section_ != NULL) 2456 { 2457 this->dynamic_symbol_ = 2458 symtab->define_in_output_data("_DYNAMIC", NULL, 2459 Symbol_table::PREDEFINED, 2460 this->dynamic_section_, 0, 0, 2461 elfcpp::STT_OBJECT, elfcpp::STB_LOCAL, 2462 elfcpp::STV_HIDDEN, 0, false, false); 2463 2464 this->dynamic_data_ = new Output_data_dynamic(&this->dynpool_); 2465 2466 this->dynamic_section_->add_output_section_data(this->dynamic_data_); 2467 } 2468 } 2469 2470 // For each output section whose name can be represented as C symbol, 2471 // define __start and __stop symbols for the section. This is a GNU 2472 // extension. 2473 2474 void 2475 Layout::define_section_symbols(Symbol_table* symtab) 2476 { 2477 for (Section_list::const_iterator p = this->section_list_.begin(); 2478 p != this->section_list_.end(); 2479 ++p) 2480 { 2481 const char* const name = (*p)->name(); 2482 if (is_cident(name)) 2483 { 2484 const std::string name_string(name); 2485 const std::string start_name(cident_section_start_prefix 2486 + name_string); 2487 const std::string stop_name(cident_section_stop_prefix 2488 + name_string); 2489 2490 symtab->define_in_output_data(start_name.c_str(), 2491 NULL, // version 2492 Symbol_table::PREDEFINED, 2493 *p, 2494 0, // value 2495 0, // symsize 2496 elfcpp::STT_NOTYPE, 2497 elfcpp::STB_GLOBAL, 2498 elfcpp::STV_PROTECTED, 2499 0, // nonvis 2500 false, // offset_is_from_end 2501 true); // only_if_ref 2502 2503 symtab->define_in_output_data(stop_name.c_str(), 2504 NULL, // version 2505 Symbol_table::PREDEFINED, 2506 *p, 2507 0, // value 2508 0, // symsize 2509 elfcpp::STT_NOTYPE, 2510 elfcpp::STB_GLOBAL, 2511 elfcpp::STV_PROTECTED, 2512 0, // nonvis 2513 true, // offset_is_from_end 2514 true); // only_if_ref 2515 } 2516 } 2517 } 2518 2519 // Define symbols for group signatures. 2520 2521 void 2522 Layout::define_group_signatures(Symbol_table* symtab) 2523 { 2524 for (Group_signatures::iterator p = this->group_signatures_.begin(); 2525 p != this->group_signatures_.end(); 2526 ++p) 2527 { 2528 Symbol* sym = symtab->lookup(p->signature, NULL); 2529 if (sym != NULL) 2530 p->section->set_info_symndx(sym); 2531 else 2532 { 2533 // Force the name of the group section to the group 2534 // signature, and use the group's section symbol as the 2535 // signature symbol. 2536 if (strcmp(p->section->name(), p->signature) != 0) 2537 { 2538 const char* name = this->namepool_.add(p->signature, 2539 true, NULL); 2540 p->section->set_name(name); 2541 } 2542 p->section->set_needs_symtab_index(); 2543 p->section->set_info_section_symndx(p->section); 2544 } 2545 } 2546 2547 this->group_signatures_.clear(); 2548 } 2549 2550 // Find the first read-only PT_LOAD segment, creating one if 2551 // necessary. 2552 2553 Output_segment* 2554 Layout::find_first_load_seg(const Target* target) 2555 { 2556 Output_segment* best = NULL; 2557 for (Segment_list::const_iterator p = this->segment_list_.begin(); 2558 p != this->segment_list_.end(); 2559 ++p) 2560 { 2561 if ((*p)->type() == elfcpp::PT_LOAD 2562 && ((*p)->flags() & elfcpp::PF_R) != 0 2563 && (parameters->options().omagic() 2564 || ((*p)->flags() & elfcpp::PF_W) == 0) 2565 && (!target->isolate_execinstr() 2566 || ((*p)->flags() & elfcpp::PF_X) == 0)) 2567 { 2568 if (best == NULL || this->segment_precedes(*p, best)) 2569 best = *p; 2570 } 2571 } 2572 if (best != NULL) 2573 return best; 2574 2575 gold_assert(!this->script_options_->saw_phdrs_clause()); 2576 2577 Output_segment* load_seg = this->make_output_segment(elfcpp::PT_LOAD, 2578 elfcpp::PF_R); 2579 return load_seg; 2580 } 2581 2582 // Save states of all current output segments. Store saved states 2583 // in SEGMENT_STATES. 2584 2585 void 2586 Layout::save_segments(Segment_states* segment_states) 2587 { 2588 for (Segment_list::const_iterator p = this->segment_list_.begin(); 2589 p != this->segment_list_.end(); 2590 ++p) 2591 { 2592 Output_segment* segment = *p; 2593 // Shallow copy. 2594 Output_segment* copy = new Output_segment(*segment); 2595 (*segment_states)[segment] = copy; 2596 } 2597 } 2598 2599 // Restore states of output segments and delete any segment not found in 2600 // SEGMENT_STATES. 2601 2602 void 2603 Layout::restore_segments(const Segment_states* segment_states) 2604 { 2605 // Go through the segment list and remove any segment added in the 2606 // relaxation loop. 2607 this->tls_segment_ = NULL; 2608 this->relro_segment_ = NULL; 2609 Segment_list::iterator list_iter = this->segment_list_.begin(); 2610 while (list_iter != this->segment_list_.end()) 2611 { 2612 Output_segment* segment = *list_iter; 2613 Segment_states::const_iterator states_iter = 2614 segment_states->find(segment); 2615 if (states_iter != segment_states->end()) 2616 { 2617 const Output_segment* copy = states_iter->second; 2618 // Shallow copy to restore states. 2619 *segment = *copy; 2620 2621 // Also fix up TLS and RELRO segment pointers as appropriate. 2622 if (segment->type() == elfcpp::PT_TLS) 2623 this->tls_segment_ = segment; 2624 else if (segment->type() == elfcpp::PT_GNU_RELRO) 2625 this->relro_segment_ = segment; 2626 2627 ++list_iter; 2628 } 2629 else 2630 { 2631 list_iter = this->segment_list_.erase(list_iter); 2632 // This is a segment created during section layout. It should be 2633 // safe to remove it since we should have removed all pointers to it. 2634 delete segment; 2635 } 2636 } 2637 } 2638 2639 // Clean up after relaxation so that sections can be laid out again. 2640 2641 void 2642 Layout::clean_up_after_relaxation() 2643 { 2644 // Restore the segments to point state just prior to the relaxation loop. 2645 Script_sections* script_section = this->script_options_->script_sections(); 2646 script_section->release_segments(); 2647 this->restore_segments(this->segment_states_); 2648 2649 // Reset section addresses and file offsets 2650 for (Section_list::iterator p = this->section_list_.begin(); 2651 p != this->section_list_.end(); 2652 ++p) 2653 { 2654 (*p)->restore_states(); 2655 2656 // If an input section changes size because of relaxation, 2657 // we need to adjust the section offsets of all input sections. 2658 // after such a section. 2659 if ((*p)->section_offsets_need_adjustment()) 2660 (*p)->adjust_section_offsets(); 2661 2662 (*p)->reset_address_and_file_offset(); 2663 } 2664 2665 // Reset special output object address and file offsets. 2666 for (Data_list::iterator p = this->special_output_list_.begin(); 2667 p != this->special_output_list_.end(); 2668 ++p) 2669 (*p)->reset_address_and_file_offset(); 2670 2671 // A linker script may have created some output section data objects. 2672 // They are useless now. 2673 for (Output_section_data_list::const_iterator p = 2674 this->script_output_section_data_list_.begin(); 2675 p != this->script_output_section_data_list_.end(); 2676 ++p) 2677 delete *p; 2678 this->script_output_section_data_list_.clear(); 2679 2680 // Special-case fill output objects are recreated each time through 2681 // the relaxation loop. 2682 this->reset_relax_output(); 2683 } 2684 2685 void 2686 Layout::reset_relax_output() 2687 { 2688 for (Data_list::const_iterator p = this->relax_output_list_.begin(); 2689 p != this->relax_output_list_.end(); 2690 ++p) 2691 delete *p; 2692 this->relax_output_list_.clear(); 2693 } 2694 2695 // Prepare for relaxation. 2696 2697 void 2698 Layout::prepare_for_relaxation() 2699 { 2700 // Create an relaxation debug check if in debugging mode. 2701 if (is_debugging_enabled(DEBUG_RELAXATION)) 2702 this->relaxation_debug_check_ = new Relaxation_debug_check(); 2703 2704 // Save segment states. 2705 this->segment_states_ = new Segment_states(); 2706 this->save_segments(this->segment_states_); 2707 2708 for(Section_list::const_iterator p = this->section_list_.begin(); 2709 p != this->section_list_.end(); 2710 ++p) 2711 (*p)->save_states(); 2712 2713 if (is_debugging_enabled(DEBUG_RELAXATION)) 2714 this->relaxation_debug_check_->check_output_data_for_reset_values( 2715 this->section_list_, this->special_output_list_, 2716 this->relax_output_list_); 2717 2718 // Also enable recording of output section data from scripts. 2719 this->record_output_section_data_from_script_ = true; 2720 } 2721 2722 // If the user set the address of the text segment, that may not be 2723 // compatible with putting the segment headers and file headers into 2724 // that segment. For isolate_execinstr() targets, it's the rodata 2725 // segment rather than text where we might put the headers. 2726 static inline bool 2727 load_seg_unusable_for_headers(const Target* target) 2728 { 2729 const General_options& options = parameters->options(); 2730 if (target->isolate_execinstr()) 2731 return (options.user_set_Trodata_segment() 2732 && options.Trodata_segment() % target->abi_pagesize() != 0); 2733 else 2734 return (options.user_set_Ttext() 2735 && options.Ttext() % target->abi_pagesize() != 0); 2736 } 2737 2738 // Relaxation loop body: If target has no relaxation, this runs only once 2739 // Otherwise, the target relaxation hook is called at the end of 2740 // each iteration. If the hook returns true, it means re-layout of 2741 // section is required. 2742 // 2743 // The number of segments created by a linking script without a PHDRS 2744 // clause may be affected by section sizes and alignments. There is 2745 // a remote chance that relaxation causes different number of PT_LOAD 2746 // segments are created and sections are attached to different segments. 2747 // Therefore, we always throw away all segments created during section 2748 // layout. In order to be able to restart the section layout, we keep 2749 // a copy of the segment list right before the relaxation loop and use 2750 // that to restore the segments. 2751 // 2752 // PASS is the current relaxation pass number. 2753 // SYMTAB is a symbol table. 2754 // PLOAD_SEG is the address of a pointer for the load segment. 2755 // PHDR_SEG is a pointer to the PHDR segment. 2756 // SEGMENT_HEADERS points to the output segment header. 2757 // FILE_HEADER points to the output file header. 2758 // PSHNDX is the address to store the output section index. 2759 2760 off_t inline 2761 Layout::relaxation_loop_body( 2762 int pass, 2763 Target* target, 2764 Symbol_table* symtab, 2765 Output_segment** pload_seg, 2766 Output_segment* phdr_seg, 2767 Output_segment_headers* segment_headers, 2768 Output_file_header* file_header, 2769 unsigned int* pshndx) 2770 { 2771 // If this is not the first iteration, we need to clean up after 2772 // relaxation so that we can lay out the sections again. 2773 if (pass != 0) 2774 this->clean_up_after_relaxation(); 2775 2776 // If there is a SECTIONS clause, put all the input sections into 2777 // the required order. 2778 Output_segment* load_seg; 2779 if (this->script_options_->saw_sections_clause()) 2780 load_seg = this->set_section_addresses_from_script(symtab); 2781 else if (parameters->options().relocatable()) 2782 load_seg = NULL; 2783 else 2784 load_seg = this->find_first_load_seg(target); 2785 2786 if (parameters->options().oformat_enum() 2787 != General_options::OBJECT_FORMAT_ELF) 2788 load_seg = NULL; 2789 2790 if (load_seg_unusable_for_headers(target)) 2791 { 2792 load_seg = NULL; 2793 phdr_seg = NULL; 2794 } 2795 2796 gold_assert(phdr_seg == NULL 2797 || load_seg != NULL 2798 || this->script_options_->saw_sections_clause()); 2799 2800 // If the address of the load segment we found has been set by 2801 // --section-start rather than by a script, then adjust the VMA and 2802 // LMA downward if possible to include the file and section headers. 2803 uint64_t header_gap = 0; 2804 if (load_seg != NULL 2805 && load_seg->are_addresses_set() 2806 && !this->script_options_->saw_sections_clause() 2807 && !parameters->options().relocatable()) 2808 { 2809 file_header->finalize_data_size(); 2810 segment_headers->finalize_data_size(); 2811 size_t sizeof_headers = (file_header->data_size() 2812 + segment_headers->data_size()); 2813 const uint64_t abi_pagesize = target->abi_pagesize(); 2814 uint64_t hdr_paddr = load_seg->paddr() - sizeof_headers; 2815 hdr_paddr &= ~(abi_pagesize - 1); 2816 uint64_t subtract = load_seg->paddr() - hdr_paddr; 2817 if (load_seg->paddr() < subtract || load_seg->vaddr() < subtract) 2818 load_seg = NULL; 2819 else 2820 { 2821 load_seg->set_addresses(load_seg->vaddr() - subtract, 2822 load_seg->paddr() - subtract); 2823 header_gap = subtract - sizeof_headers; 2824 } 2825 } 2826 2827 // Lay out the segment headers. 2828 if (!parameters->options().relocatable()) 2829 { 2830 gold_assert(segment_headers != NULL); 2831 if (header_gap != 0 && load_seg != NULL) 2832 { 2833 Output_data_zero_fill* z = new Output_data_zero_fill(header_gap, 1); 2834 load_seg->add_initial_output_data(z); 2835 } 2836 if (load_seg != NULL) 2837 load_seg->add_initial_output_data(segment_headers); 2838 if (phdr_seg != NULL) 2839 phdr_seg->add_initial_output_data(segment_headers); 2840 } 2841 2842 // Lay out the file header. 2843 if (load_seg != NULL) 2844 load_seg->add_initial_output_data(file_header); 2845 2846 if (this->script_options_->saw_phdrs_clause() 2847 && !parameters->options().relocatable()) 2848 { 2849 // Support use of FILEHDRS and PHDRS attachments in a PHDRS 2850 // clause in a linker script. 2851 Script_sections* ss = this->script_options_->script_sections(); 2852 ss->put_headers_in_phdrs(file_header, segment_headers); 2853 } 2854 2855 // We set the output section indexes in set_segment_offsets and 2856 // set_section_indexes. 2857 *pshndx = 1; 2858 2859 // Set the file offsets of all the segments, and all the sections 2860 // they contain. 2861 off_t off; 2862 if (!parameters->options().relocatable()) 2863 off = this->set_segment_offsets(target, load_seg, pshndx); 2864 else 2865 off = this->set_relocatable_section_offsets(file_header, pshndx); 2866 2867 // Verify that the dummy relaxation does not change anything. 2868 if (is_debugging_enabled(DEBUG_RELAXATION)) 2869 { 2870 if (pass == 0) 2871 this->relaxation_debug_check_->read_sections(this->section_list_); 2872 else 2873 this->relaxation_debug_check_->verify_sections(this->section_list_); 2874 } 2875 2876 *pload_seg = load_seg; 2877 return off; 2878 } 2879 2880 // Search the list of patterns and find the position of the given section 2881 // name in the output section. If the section name matches a glob 2882 // pattern and a non-glob name, then the non-glob position takes 2883 // precedence. Return 0 if no match is found. 2884 2885 unsigned int 2886 Layout::find_section_order_index(const std::string& section_name) 2887 { 2888 Unordered_map<std::string, unsigned int>::iterator map_it; 2889 map_it = this->input_section_position_.find(section_name); 2890 if (map_it != this->input_section_position_.end()) 2891 return map_it->second; 2892 2893 // Absolute match failed. Linear search the glob patterns. 2894 std::vector<std::string>::iterator it; 2895 for (it = this->input_section_glob_.begin(); 2896 it != this->input_section_glob_.end(); 2897 ++it) 2898 { 2899 if (fnmatch((*it).c_str(), section_name.c_str(), FNM_NOESCAPE) == 0) 2900 { 2901 map_it = this->input_section_position_.find(*it); 2902 gold_assert(map_it != this->input_section_position_.end()); 2903 return map_it->second; 2904 } 2905 } 2906 return 0; 2907 } 2908 2909 // Read the sequence of input sections from the file specified with 2910 // option --section-ordering-file. 2911 2912 void 2913 Layout::read_layout_from_file() 2914 { 2915 const char* filename = parameters->options().section_ordering_file(); 2916 std::ifstream in; 2917 std::string line; 2918 2919 in.open(filename); 2920 if (!in) 2921 gold_fatal(_("unable to open --section-ordering-file file %s: %s"), 2922 filename, strerror(errno)); 2923 2924 std::getline(in, line); // this chops off the trailing \n, if any 2925 unsigned int position = 1; 2926 this->set_section_ordering_specified(); 2927 2928 while (in) 2929 { 2930 if (!line.empty() && line[line.length() - 1] == '\r') // Windows 2931 line.resize(line.length() - 1); 2932 // Ignore comments, beginning with '#' 2933 if (line[0] == '#') 2934 { 2935 std::getline(in, line); 2936 continue; 2937 } 2938 this->input_section_position_[line] = position; 2939 // Store all glob patterns in a vector. 2940 if (is_wildcard_string(line.c_str())) 2941 this->input_section_glob_.push_back(line); 2942 position++; 2943 std::getline(in, line); 2944 } 2945 } 2946 2947 // Finalize the layout. When this is called, we have created all the 2948 // output sections and all the output segments which are based on 2949 // input sections. We have several things to do, and we have to do 2950 // them in the right order, so that we get the right results correctly 2951 // and efficiently. 2952 2953 // 1) Finalize the list of output segments and create the segment 2954 // table header. 2955 2956 // 2) Finalize the dynamic symbol table and associated sections. 2957 2958 // 3) Determine the final file offset of all the output segments. 2959 2960 // 4) Determine the final file offset of all the SHF_ALLOC output 2961 // sections. 2962 2963 // 5) Create the symbol table sections and the section name table 2964 // section. 2965 2966 // 6) Finalize the symbol table: set symbol values to their final 2967 // value and make a final determination of which symbols are going 2968 // into the output symbol table. 2969 2970 // 7) Create the section table header. 2971 2972 // 8) Determine the final file offset of all the output sections which 2973 // are not SHF_ALLOC, including the section table header. 2974 2975 // 9) Finalize the ELF file header. 2976 2977 // This function returns the size of the output file. 2978 2979 off_t 2980 Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab, 2981 Target* target, const Task* task) 2982 { 2983 unsigned int local_dynamic_count = 0; 2984 unsigned int forced_local_dynamic_count = 0; 2985 2986 target->finalize_sections(this, input_objects, symtab); 2987 2988 this->count_local_symbols(task, input_objects); 2989 2990 this->link_stabs_sections(); 2991 2992 Output_segment* phdr_seg = NULL; 2993 if (!parameters->options().relocatable() && !parameters->doing_static_link()) 2994 { 2995 // There was a dynamic object in the link. We need to create 2996 // some information for the dynamic linker. 2997 2998 // Create the PT_PHDR segment which will hold the program 2999 // headers. 3000 if (!this->script_options_->saw_phdrs_clause()) 3001 phdr_seg = this->make_output_segment(elfcpp::PT_PHDR, elfcpp::PF_R); 3002 3003 // Create the dynamic symbol table, including the hash table. 3004 Output_section* dynstr; 3005 std::vector<Symbol*> dynamic_symbols; 3006 Versions versions(*this->script_options()->version_script_info(), 3007 &this->dynpool_); 3008 this->create_dynamic_symtab(input_objects, symtab, &dynstr, 3009 &local_dynamic_count, 3010 &forced_local_dynamic_count, 3011 &dynamic_symbols, 3012 &versions); 3013 3014 // Create the .interp section to hold the name of the 3015 // interpreter, and put it in a PT_INTERP segment. Don't do it 3016 // if we saw a .interp section in an input file. 3017 if ((!parameters->options().shared() 3018 || parameters->options().dynamic_linker() != NULL) 3019 && this->interp_segment_ == NULL) 3020 this->create_interp(target); 3021 3022 // Finish the .dynamic section to hold the dynamic data, and put 3023 // it in a PT_DYNAMIC segment. 3024 this->finish_dynamic_section(input_objects, symtab); 3025 3026 // We should have added everything we need to the dynamic string 3027 // table. 3028 this->dynpool_.set_string_offsets(); 3029 3030 // Create the version sections. We can't do this until the 3031 // dynamic string table is complete. 3032 this->create_version_sections(&versions, symtab, 3033 (local_dynamic_count 3034 + forced_local_dynamic_count), 3035 dynamic_symbols, dynstr); 3036 3037 // Set the size of the _DYNAMIC symbol. We can't do this until 3038 // after we call create_version_sections. 3039 this->set_dynamic_symbol_size(symtab); 3040 } 3041 3042 // Create segment headers. 3043 Output_segment_headers* segment_headers = 3044 (parameters->options().relocatable() 3045 ? NULL 3046 : new Output_segment_headers(this->segment_list_)); 3047 3048 // Lay out the file header. 3049 Output_file_header* file_header = new Output_file_header(target, symtab, 3050 segment_headers); 3051 3052 this->special_output_list_.push_back(file_header); 3053 if (segment_headers != NULL) 3054 this->special_output_list_.push_back(segment_headers); 3055 3056 // Find approriate places for orphan output sections if we are using 3057 // a linker script. 3058 if (this->script_options_->saw_sections_clause()) 3059 this->place_orphan_sections_in_script(); 3060 3061 Output_segment* load_seg; 3062 off_t off; 3063 unsigned int shndx; 3064 int pass = 0; 3065 3066 // Take a snapshot of the section layout as needed. 3067 if (target->may_relax()) 3068 this->prepare_for_relaxation(); 3069 3070 // Run the relaxation loop to lay out sections. 3071 do 3072 { 3073 off = this->relaxation_loop_body(pass, target, symtab, &load_seg, 3074 phdr_seg, segment_headers, file_header, 3075 &shndx); 3076 pass++; 3077 } 3078 while (target->may_relax() 3079 && target->relax(pass, input_objects, symtab, this, task)); 3080 3081 // If there is a load segment that contains the file and program headers, 3082 // provide a symbol __ehdr_start pointing there. 3083 // A program can use this to examine itself robustly. 3084 Symbol *ehdr_start = symtab->lookup("__ehdr_start"); 3085 if (ehdr_start != NULL && ehdr_start->is_predefined()) 3086 { 3087 if (load_seg != NULL) 3088 ehdr_start->set_output_segment(load_seg, Symbol::SEGMENT_START); 3089 else 3090 ehdr_start->set_undefined(); 3091 } 3092 3093 // Set the file offsets of all the non-data sections we've seen so 3094 // far which don't have to wait for the input sections. We need 3095 // this in order to finalize local symbols in non-allocated 3096 // sections. 3097 off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS); 3098 3099 // Set the section indexes of all unallocated sections seen so far, 3100 // in case any of them are somehow referenced by a symbol. 3101 shndx = this->set_section_indexes(shndx); 3102 3103 // Create the symbol table sections. 3104 this->create_symtab_sections(input_objects, symtab, shndx, &off, 3105 local_dynamic_count); 3106 if (!parameters->doing_static_link()) 3107 this->assign_local_dynsym_offsets(input_objects); 3108 3109 // Process any symbol assignments from a linker script. This must 3110 // be called after the symbol table has been finalized. 3111 this->script_options_->finalize_symbols(symtab, this); 3112 3113 // Create the incremental inputs sections. 3114 if (this->incremental_inputs_) 3115 { 3116 this->incremental_inputs_->finalize(); 3117 this->create_incremental_info_sections(symtab); 3118 } 3119 3120 // Create the .shstrtab section. 3121 Output_section* shstrtab_section = this->create_shstrtab(); 3122 3123 // Set the file offsets of the rest of the non-data sections which 3124 // don't have to wait for the input sections. 3125 off = this->set_section_offsets(off, BEFORE_INPUT_SECTIONS_PASS); 3126 3127 // Now that all sections have been created, set the section indexes 3128 // for any sections which haven't been done yet. 3129 shndx = this->set_section_indexes(shndx); 3130 3131 // Create the section table header. 3132 this->create_shdrs(shstrtab_section, &off); 3133 3134 // If there are no sections which require postprocessing, we can 3135 // handle the section names now, and avoid a resize later. 3136 if (!this->any_postprocessing_sections_) 3137 { 3138 off = this->set_section_offsets(off, 3139 POSTPROCESSING_SECTIONS_PASS); 3140 off = 3141 this->set_section_offsets(off, 3142 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS); 3143 } 3144 3145 file_header->set_section_info(this->section_headers_, shstrtab_section); 3146 3147 // Now we know exactly where everything goes in the output file 3148 // (except for non-allocated sections which require postprocessing). 3149 Output_data::layout_complete(); 3150 3151 this->output_file_size_ = off; 3152 3153 return off; 3154 } 3155 3156 // Create a note header following the format defined in the ELF ABI. 3157 // NAME is the name, NOTE_TYPE is the type, SECTION_NAME is the name 3158 // of the section to create, DESCSZ is the size of the descriptor. 3159 // ALLOCATE is true if the section should be allocated in memory. 3160 // This returns the new note section. It sets *TRAILING_PADDING to 3161 // the number of trailing zero bytes required. 3162 3163 Output_section* 3164 Layout::create_note(const char* name, int note_type, 3165 const char* section_name, size_t descsz, 3166 bool allocate, size_t* trailing_padding) 3167 { 3168 // Authorities all agree that the values in a .note field should 3169 // be aligned on 4-byte boundaries for 32-bit binaries. However, 3170 // they differ on what the alignment is for 64-bit binaries. 3171 // The GABI says unambiguously they take 8-byte alignment: 3172 // http://sco.com/developers/gabi/latest/ch5.pheader.html#note_section 3173 // Other documentation says alignment should always be 4 bytes: 3174 // http://www.netbsd.org/docs/kernel/elf-notes.html#note-format 3175 // GNU ld and GNU readelf both support the latter (at least as of 3176 // version 2.16.91), and glibc always generates the latter for 3177 // .note.ABI-tag (as of version 1.6), so that's the one we go with 3178 // here. 3179 #ifdef GABI_FORMAT_FOR_DOTNOTE_SECTION // This is not defined by default. 3180 const int size = parameters->target().get_size(); 3181 #else 3182 const int size = 32; 3183 #endif 3184 3185 // The contents of the .note section. 3186 size_t namesz = strlen(name) + 1; 3187 size_t aligned_namesz = align_address(namesz, size / 8); 3188 size_t aligned_descsz = align_address(descsz, size / 8); 3189 3190 size_t notehdrsz = 3 * (size / 8) + aligned_namesz; 3191 3192 unsigned char* buffer = new unsigned char[notehdrsz]; 3193 memset(buffer, 0, notehdrsz); 3194 3195 bool is_big_endian = parameters->target().is_big_endian(); 3196 3197 if (size == 32) 3198 { 3199 if (!is_big_endian) 3200 { 3201 elfcpp::Swap<32, false>::writeval(buffer, namesz); 3202 elfcpp::Swap<32, false>::writeval(buffer + 4, descsz); 3203 elfcpp::Swap<32, false>::writeval(buffer + 8, note_type); 3204 } 3205 else 3206 { 3207 elfcpp::Swap<32, true>::writeval(buffer, namesz); 3208 elfcpp::Swap<32, true>::writeval(buffer + 4, descsz); 3209 elfcpp::Swap<32, true>::writeval(buffer + 8, note_type); 3210 } 3211 } 3212 else if (size == 64) 3213 { 3214 if (!is_big_endian) 3215 { 3216 elfcpp::Swap<64, false>::writeval(buffer, namesz); 3217 elfcpp::Swap<64, false>::writeval(buffer + 8, descsz); 3218 elfcpp::Swap<64, false>::writeval(buffer + 16, note_type); 3219 } 3220 else 3221 { 3222 elfcpp::Swap<64, true>::writeval(buffer, namesz); 3223 elfcpp::Swap<64, true>::writeval(buffer + 8, descsz); 3224 elfcpp::Swap<64, true>::writeval(buffer + 16, note_type); 3225 } 3226 } 3227 else 3228 gold_unreachable(); 3229 3230 memcpy(buffer + 3 * (size / 8), name, namesz); 3231 3232 elfcpp::Elf_Xword flags = 0; 3233 Output_section_order order = ORDER_INVALID; 3234 if (allocate) 3235 { 3236 flags = elfcpp::SHF_ALLOC; 3237 order = ORDER_RO_NOTE; 3238 } 3239 Output_section* os = this->choose_output_section(NULL, section_name, 3240 elfcpp::SHT_NOTE, 3241 flags, false, order, false, 3242 false, true); 3243 if (os == NULL) 3244 return NULL; 3245 3246 Output_section_data* posd = new Output_data_const_buffer(buffer, notehdrsz, 3247 size / 8, 3248 "** note header"); 3249 os->add_output_section_data(posd); 3250 3251 *trailing_padding = aligned_descsz - descsz; 3252 3253 return os; 3254 } 3255 3256 // Create a .note.gnu.property section to record program properties 3257 // accumulated from the input files. 3258 3259 void 3260 Layout::create_gnu_properties_note() 3261 { 3262 parameters->target().finalize_gnu_properties(this); 3263 3264 if (this->gnu_properties_.empty()) 3265 return; 3266 3267 const unsigned int size = parameters->target().get_size(); 3268 const bool is_big_endian = parameters->target().is_big_endian(); 3269 3270 // Compute the total size of the properties array. 3271 size_t descsz = 0; 3272 for (Gnu_properties::const_iterator prop = this->gnu_properties_.begin(); 3273 prop != this->gnu_properties_.end(); 3274 ++prop) 3275 { 3276 descsz = align_address(descsz + 8 + prop->second.pr_datasz, size / 8); 3277 } 3278 3279 // Create the note section. 3280 size_t trailing_padding; 3281 Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_PROPERTY_TYPE_0, 3282 ".note.gnu.property", descsz, 3283 true, &trailing_padding); 3284 if (os == NULL) 3285 return; 3286 gold_assert(trailing_padding == 0); 3287 3288 // Allocate and fill the properties array. 3289 unsigned char* desc = new unsigned char[descsz]; 3290 unsigned char* p = desc; 3291 for (Gnu_properties::const_iterator prop = this->gnu_properties_.begin(); 3292 prop != this->gnu_properties_.end(); 3293 ++prop) 3294 { 3295 size_t datasz = prop->second.pr_datasz; 3296 size_t aligned_datasz = align_address(prop->second.pr_datasz, size / 8); 3297 write_sized_value(prop->first, 4, p, is_big_endian); 3298 write_sized_value(datasz, 4, p + 4, is_big_endian); 3299 memcpy(p + 8, prop->second.pr_data, datasz); 3300 if (aligned_datasz > datasz) 3301 memset(p + 8 + datasz, 0, aligned_datasz - datasz); 3302 p += 8 + aligned_datasz; 3303 } 3304 Output_section_data* posd = new Output_data_const(desc, descsz, 4); 3305 os->add_output_section_data(posd); 3306 } 3307 3308 // For an executable or shared library, create a note to record the 3309 // version of gold used to create the binary. 3310 3311 void 3312 Layout::create_gold_note() 3313 { 3314 if (parameters->options().relocatable() 3315 || parameters->incremental_update()) 3316 return; 3317 3318 std::string desc = std::string("gold ") + gold::get_version_string(); 3319 3320 size_t trailing_padding; 3321 Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_GOLD_VERSION, 3322 ".note.gnu.gold-version", desc.size(), 3323 false, &trailing_padding); 3324 if (os == NULL) 3325 return; 3326 3327 Output_section_data* posd = new Output_data_const(desc, 4); 3328 os->add_output_section_data(posd); 3329 3330 if (trailing_padding > 0) 3331 { 3332 posd = new Output_data_zero_fill(trailing_padding, 0); 3333 os->add_output_section_data(posd); 3334 } 3335 } 3336 3337 // Record whether the stack should be executable. This can be set 3338 // from the command line using the -z execstack or -z noexecstack 3339 // options. Otherwise, if any input file has a .note.GNU-stack 3340 // section with the SHF_EXECINSTR flag set, the stack should be 3341 // executable. Otherwise, if at least one input file a 3342 // .note.GNU-stack section, and some input file has no .note.GNU-stack 3343 // section, we use the target default for whether the stack should be 3344 // executable. If -z stack-size was used to set a p_memsz value for 3345 // PT_GNU_STACK, we generate the segment regardless. Otherwise, we 3346 // don't generate a stack note. When generating a object file, we 3347 // create a .note.GNU-stack section with the appropriate marking. 3348 // When generating an executable or shared library, we create a 3349 // PT_GNU_STACK segment. 3350 3351 void 3352 Layout::create_stack_segment() 3353 { 3354 bool is_stack_executable; 3355 if (parameters->options().is_execstack_set()) 3356 { 3357 is_stack_executable = parameters->options().is_stack_executable(); 3358 if (!is_stack_executable 3359 && this->input_requires_executable_stack_ 3360 && parameters->options().warn_execstack()) 3361 gold_warning(_("one or more inputs require executable stack, " 3362 "but -z noexecstack was given")); 3363 } 3364 else if (!this->input_with_gnu_stack_note_ 3365 && (!parameters->options().user_set_stack_size() 3366 || parameters->options().relocatable())) 3367 return; 3368 else 3369 { 3370 if (this->input_requires_executable_stack_) 3371 is_stack_executable = true; 3372 else if (this->input_without_gnu_stack_note_) 3373 is_stack_executable = 3374 parameters->target().is_default_stack_executable(); 3375 else 3376 is_stack_executable = false; 3377 } 3378 3379 if (parameters->options().relocatable()) 3380 { 3381 const char* name = this->namepool_.add(".note.GNU-stack", false, NULL); 3382 elfcpp::Elf_Xword flags = 0; 3383 if (is_stack_executable) 3384 flags |= elfcpp::SHF_EXECINSTR; 3385 this->make_output_section(name, elfcpp::SHT_PROGBITS, flags, 3386 ORDER_INVALID, false); 3387 } 3388 else 3389 { 3390 if (this->script_options_->saw_phdrs_clause()) 3391 return; 3392 int flags = elfcpp::PF_R | elfcpp::PF_W; 3393 if (is_stack_executable) 3394 flags |= elfcpp::PF_X; 3395 Output_segment* seg = 3396 this->make_output_segment(elfcpp::PT_GNU_STACK, flags); 3397 seg->set_size(parameters->options().stack_size()); 3398 // BFD lets targets override this default alignment, but the only 3399 // targets that do so are ones that Gold does not support so far. 3400 seg->set_minimum_p_align(16); 3401 } 3402 } 3403 3404 // If --build-id was used, set up the build ID note. 3405 3406 void 3407 Layout::create_build_id() 3408 { 3409 if (!parameters->options().user_set_build_id()) 3410 return; 3411 3412 const char* style = parameters->options().build_id(); 3413 if (strcmp(style, "none") == 0) 3414 return; 3415 3416 // Set DESCSZ to the size of the note descriptor. When possible, 3417 // set DESC to the note descriptor contents. 3418 size_t descsz; 3419 std::string desc; 3420 if (strcmp(style, "md5") == 0) 3421 descsz = 128 / 8; 3422 else if ((strcmp(style, "sha1") == 0) || (strcmp(style, "tree") == 0)) 3423 descsz = 160 / 8; 3424 else if (strcmp(style, "uuid") == 0) 3425 { 3426 #ifndef __MINGW32__ 3427 const size_t uuidsz = 128 / 8; 3428 3429 char buffer[uuidsz]; 3430 memset(buffer, 0, uuidsz); 3431 3432 int descriptor = open_descriptor(-1, "/dev/urandom", O_RDONLY); 3433 if (descriptor < 0) 3434 gold_error(_("--build-id=uuid failed: could not open /dev/urandom: %s"), 3435 strerror(errno)); 3436 else 3437 { 3438 ssize_t got = ::read(descriptor, buffer, uuidsz); 3439 release_descriptor(descriptor, true); 3440 if (got < 0) 3441 gold_error(_("/dev/urandom: read failed: %s"), strerror(errno)); 3442 else if (static_cast<size_t>(got) != uuidsz) 3443 gold_error(_("/dev/urandom: expected %zu bytes, got %zd bytes"), 3444 uuidsz, got); 3445 } 3446 3447 desc.assign(buffer, uuidsz); 3448 descsz = uuidsz; 3449 #else // __MINGW32__ 3450 UUID uuid; 3451 typedef RPC_STATUS (RPC_ENTRY *UuidCreateFn)(UUID *Uuid); 3452 3453 HMODULE rpc_library = LoadLibrary("rpcrt4.dll"); 3454 if (!rpc_library) 3455 gold_error(_("--build-id=uuid failed: could not load rpcrt4.dll")); 3456 else 3457 { 3458 UuidCreateFn uuid_create = reinterpret_cast<UuidCreateFn>( 3459 GetProcAddress(rpc_library, "UuidCreate")); 3460 if (!uuid_create) 3461 gold_error(_("--build-id=uuid failed: could not find UuidCreate")); 3462 else if (uuid_create(&uuid) != RPC_S_OK) 3463 gold_error(_("__build_id=uuid failed: call UuidCreate() failed")); 3464 FreeLibrary(rpc_library); 3465 } 3466 desc.assign(reinterpret_cast<const char *>(&uuid), sizeof(UUID)); 3467 descsz = sizeof(UUID); 3468 #endif // __MINGW32__ 3469 } 3470 else if (strncmp(style, "0x", 2) == 0) 3471 { 3472 hex_init(); 3473 const char* p = style + 2; 3474 while (*p != '\0') 3475 { 3476 if (hex_p(p[0]) && hex_p(p[1])) 3477 { 3478 char c = (hex_value(p[0]) << 4) | hex_value(p[1]); 3479 desc += c; 3480 p += 2; 3481 } 3482 else if (*p == '-' || *p == ':') 3483 ++p; 3484 else 3485 gold_fatal(_("--build-id argument '%s' not a valid hex number"), 3486 style); 3487 } 3488 descsz = desc.size(); 3489 } 3490 else 3491 gold_fatal(_("unrecognized --build-id argument '%s'"), style); 3492 3493 // Create the note. 3494 size_t trailing_padding; 3495 Output_section* os = this->create_note("GNU", elfcpp::NT_GNU_BUILD_ID, 3496 ".note.gnu.build-id", descsz, true, 3497 &trailing_padding); 3498 if (os == NULL) 3499 return; 3500 3501 if (!desc.empty()) 3502 { 3503 // We know the value already, so we fill it in now. 3504 gold_assert(desc.size() == descsz); 3505 3506 Output_section_data* posd = new Output_data_const(desc, 4); 3507 os->add_output_section_data(posd); 3508 3509 if (trailing_padding != 0) 3510 { 3511 posd = new Output_data_zero_fill(trailing_padding, 0); 3512 os->add_output_section_data(posd); 3513 } 3514 } 3515 else 3516 { 3517 // We need to compute a checksum after we have completed the 3518 // link. 3519 gold_assert(trailing_padding == 0); 3520 this->build_id_note_ = new Output_data_zero_fill(descsz, 4); 3521 os->add_output_section_data(this->build_id_note_); 3522 } 3523 } 3524 3525 // If we have both .stabXX and .stabXXstr sections, then the sh_link 3526 // field of the former should point to the latter. I'm not sure who 3527 // started this, but the GNU linker does it, and some tools depend 3528 // upon it. 3529 3530 void 3531 Layout::link_stabs_sections() 3532 { 3533 if (!this->have_stabstr_section_) 3534 return; 3535 3536 for (Section_list::iterator p = this->section_list_.begin(); 3537 p != this->section_list_.end(); 3538 ++p) 3539 { 3540 if ((*p)->type() != elfcpp::SHT_STRTAB) 3541 continue; 3542 3543 const char* name = (*p)->name(); 3544 if (strncmp(name, ".stab", 5) != 0) 3545 continue; 3546 3547 size_t len = strlen(name); 3548 if (strcmp(name + len - 3, "str") != 0) 3549 continue; 3550 3551 std::string stab_name(name, len - 3); 3552 Output_section* stab_sec; 3553 stab_sec = this->find_output_section(stab_name.c_str()); 3554 if (stab_sec != NULL) 3555 stab_sec->set_link_section(*p); 3556 } 3557 } 3558 3559 // Create .gnu_incremental_inputs and related sections needed 3560 // for the next run of incremental linking to check what has changed. 3561 3562 void 3563 Layout::create_incremental_info_sections(Symbol_table* symtab) 3564 { 3565 Incremental_inputs* incr = this->incremental_inputs_; 3566 3567 gold_assert(incr != NULL); 3568 3569 // Create the .gnu_incremental_inputs, _symtab, and _relocs input sections. 3570 incr->create_data_sections(symtab); 3571 3572 // Add the .gnu_incremental_inputs section. 3573 const char* incremental_inputs_name = 3574 this->namepool_.add(".gnu_incremental_inputs", false, NULL); 3575 Output_section* incremental_inputs_os = 3576 this->make_output_section(incremental_inputs_name, 3577 elfcpp::SHT_GNU_INCREMENTAL_INPUTS, 0, 3578 ORDER_INVALID, false); 3579 incremental_inputs_os->add_output_section_data(incr->inputs_section()); 3580 3581 // Add the .gnu_incremental_symtab section. 3582 const char* incremental_symtab_name = 3583 this->namepool_.add(".gnu_incremental_symtab", false, NULL); 3584 Output_section* incremental_symtab_os = 3585 this->make_output_section(incremental_symtab_name, 3586 elfcpp::SHT_GNU_INCREMENTAL_SYMTAB, 0, 3587 ORDER_INVALID, false); 3588 incremental_symtab_os->add_output_section_data(incr->symtab_section()); 3589 incremental_symtab_os->set_entsize(4); 3590 3591 // Add the .gnu_incremental_relocs section. 3592 const char* incremental_relocs_name = 3593 this->namepool_.add(".gnu_incremental_relocs", false, NULL); 3594 Output_section* incremental_relocs_os = 3595 this->make_output_section(incremental_relocs_name, 3596 elfcpp::SHT_GNU_INCREMENTAL_RELOCS, 0, 3597 ORDER_INVALID, false); 3598 incremental_relocs_os->add_output_section_data(incr->relocs_section()); 3599 incremental_relocs_os->set_entsize(incr->relocs_entsize()); 3600 3601 // Add the .gnu_incremental_got_plt section. 3602 const char* incremental_got_plt_name = 3603 this->namepool_.add(".gnu_incremental_got_plt", false, NULL); 3604 Output_section* incremental_got_plt_os = 3605 this->make_output_section(incremental_got_plt_name, 3606 elfcpp::SHT_GNU_INCREMENTAL_GOT_PLT, 0, 3607 ORDER_INVALID, false); 3608 incremental_got_plt_os->add_output_section_data(incr->got_plt_section()); 3609 3610 // Add the .gnu_incremental_strtab section. 3611 const char* incremental_strtab_name = 3612 this->namepool_.add(".gnu_incremental_strtab", false, NULL); 3613 Output_section* incremental_strtab_os = this->make_output_section(incremental_strtab_name, 3614 elfcpp::SHT_STRTAB, 0, 3615 ORDER_INVALID, false); 3616 Output_data_strtab* strtab_data = 3617 new Output_data_strtab(incr->get_stringpool()); 3618 incremental_strtab_os->add_output_section_data(strtab_data); 3619 3620 incremental_inputs_os->set_after_input_sections(); 3621 incremental_symtab_os->set_after_input_sections(); 3622 incremental_relocs_os->set_after_input_sections(); 3623 incremental_got_plt_os->set_after_input_sections(); 3624 3625 incremental_inputs_os->set_link_section(incremental_strtab_os); 3626 incremental_symtab_os->set_link_section(incremental_inputs_os); 3627 incremental_relocs_os->set_link_section(incremental_inputs_os); 3628 incremental_got_plt_os->set_link_section(incremental_inputs_os); 3629 } 3630 3631 // Return whether SEG1 should be before SEG2 in the output file. This 3632 // is based entirely on the segment type and flags. When this is 3633 // called the segment addresses have normally not yet been set. 3634 3635 bool 3636 Layout::segment_precedes(const Output_segment* seg1, 3637 const Output_segment* seg2) 3638 { 3639 // In order to produce a stable ordering if we're called with the same pointer 3640 // return false. 3641 if (seg1 == seg2) 3642 return false; 3643 3644 elfcpp::Elf_Word type1 = seg1->type(); 3645 elfcpp::Elf_Word type2 = seg2->type(); 3646 3647 // The single PT_PHDR segment is required to precede any loadable 3648 // segment. We simply make it always first. 3649 if (type1 == elfcpp::PT_PHDR) 3650 { 3651 gold_assert(type2 != elfcpp::PT_PHDR); 3652 return true; 3653 } 3654 if (type2 == elfcpp::PT_PHDR) 3655 return false; 3656 3657 // The single PT_INTERP segment is required to precede any loadable 3658 // segment. We simply make it always second. 3659 if (type1 == elfcpp::PT_INTERP) 3660 { 3661 gold_assert(type2 != elfcpp::PT_INTERP); 3662 return true; 3663 } 3664 if (type2 == elfcpp::PT_INTERP) 3665 return false; 3666 3667 // We then put PT_LOAD segments before any other segments. 3668 if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD) 3669 return true; 3670 if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD) 3671 return false; 3672 3673 // We put the PT_TLS segment last except for the PT_GNU_RELRO 3674 // segment, because that is where the dynamic linker expects to find 3675 // it (this is just for efficiency; other positions would also work 3676 // correctly). 3677 if (type1 == elfcpp::PT_TLS 3678 && type2 != elfcpp::PT_TLS 3679 && type2 != elfcpp::PT_GNU_RELRO) 3680 return false; 3681 if (type2 == elfcpp::PT_TLS 3682 && type1 != elfcpp::PT_TLS 3683 && type1 != elfcpp::PT_GNU_RELRO) 3684 return true; 3685 3686 // We put the PT_GNU_RELRO segment last, because that is where the 3687 // dynamic linker expects to find it (as with PT_TLS, this is just 3688 // for efficiency). 3689 if (type1 == elfcpp::PT_GNU_RELRO && type2 != elfcpp::PT_GNU_RELRO) 3690 return false; 3691 if (type2 == elfcpp::PT_GNU_RELRO && type1 != elfcpp::PT_GNU_RELRO) 3692 return true; 3693 3694 const elfcpp::Elf_Word flags1 = seg1->flags(); 3695 const elfcpp::Elf_Word flags2 = seg2->flags(); 3696 3697 // The order of non-PT_LOAD segments is unimportant. We simply sort 3698 // by the numeric segment type and flags values. There should not 3699 // be more than one segment with the same type and flags, except 3700 // when a linker script specifies such. 3701 if (type1 != elfcpp::PT_LOAD) 3702 { 3703 if (type1 != type2) 3704 return type1 < type2; 3705 gold_assert(flags1 != flags2 3706 || this->script_options_->saw_phdrs_clause()); 3707 return flags1 < flags2; 3708 } 3709 3710 // If the addresses are set already, sort by load address. 3711 if (seg1->are_addresses_set()) 3712 { 3713 if (!seg2->are_addresses_set()) 3714 return true; 3715 3716 unsigned int section_count1 = seg1->output_section_count(); 3717 unsigned int section_count2 = seg2->output_section_count(); 3718 if (section_count1 == 0 && section_count2 > 0) 3719 return true; 3720 if (section_count1 > 0 && section_count2 == 0) 3721 return false; 3722 3723 uint64_t paddr1 = (seg1->are_addresses_set() 3724 ? seg1->paddr() 3725 : seg1->first_section_load_address()); 3726 uint64_t paddr2 = (seg2->are_addresses_set() 3727 ? seg2->paddr() 3728 : seg2->first_section_load_address()); 3729 3730 if (paddr1 != paddr2) 3731 return paddr1 < paddr2; 3732 } 3733 else if (seg2->are_addresses_set()) 3734 return false; 3735 3736 // A segment which holds large data comes after a segment which does 3737 // not hold large data. 3738 if (seg1->is_large_data_segment()) 3739 { 3740 if (!seg2->is_large_data_segment()) 3741 return false; 3742 } 3743 else if (seg2->is_large_data_segment()) 3744 return true; 3745 3746 // Otherwise, we sort PT_LOAD segments based on the flags. Readonly 3747 // segments come before writable segments. Then writable segments 3748 // with data come before writable segments without data. Then 3749 // executable segments come before non-executable segments. Then 3750 // the unlikely case of a non-readable segment comes before the 3751 // normal case of a readable segment. If there are multiple 3752 // segments with the same type and flags, we require that the 3753 // address be set, and we sort by virtual address and then physical 3754 // address. 3755 if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W)) 3756 return (flags1 & elfcpp::PF_W) == 0; 3757 if ((flags1 & elfcpp::PF_W) != 0 3758 && seg1->has_any_data_sections() != seg2->has_any_data_sections()) 3759 return seg1->has_any_data_sections(); 3760 if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X)) 3761 return (flags1 & elfcpp::PF_X) != 0; 3762 if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R)) 3763 return (flags1 & elfcpp::PF_R) == 0; 3764 3765 // We shouldn't get here--we shouldn't create segments which we 3766 // can't distinguish. Unless of course we are using a weird linker 3767 // script or overlapping --section-start options. We could also get 3768 // here if plugins want unique segments for subsets of sections. 3769 gold_assert(this->script_options_->saw_phdrs_clause() 3770 || parameters->options().any_section_start() 3771 || this->is_unique_segment_for_sections_specified() 3772 || parameters->options().text_unlikely_segment()); 3773 return false; 3774 } 3775 3776 // Increase OFF so that it is congruent to ADDR modulo ABI_PAGESIZE. 3777 3778 static off_t 3779 align_file_offset(off_t off, uint64_t addr, uint64_t abi_pagesize) 3780 { 3781 uint64_t unsigned_off = off; 3782 uint64_t aligned_off = ((unsigned_off & ~(abi_pagesize - 1)) 3783 | (addr & (abi_pagesize - 1))); 3784 if (aligned_off < unsigned_off) 3785 aligned_off += abi_pagesize; 3786 return aligned_off; 3787 } 3788 3789 // On targets where the text segment contains only executable code, 3790 // a non-executable segment is never the text segment. 3791 3792 static inline bool 3793 is_text_segment(const Target* target, const Output_segment* seg) 3794 { 3795 elfcpp::Elf_Xword flags = seg->flags(); 3796 if ((flags & elfcpp::PF_W) != 0) 3797 return false; 3798 if ((flags & elfcpp::PF_X) == 0) 3799 return !target->isolate_execinstr(); 3800 return true; 3801 } 3802 3803 // Set the file offsets of all the segments, and all the sections they 3804 // contain. They have all been created. LOAD_SEG must be laid out 3805 // first. Return the offset of the data to follow. 3806 3807 off_t 3808 Layout::set_segment_offsets(const Target* target, Output_segment* load_seg, 3809 unsigned int* pshndx) 3810 { 3811 // Sort them into the final order. We use a stable sort so that we 3812 // don't randomize the order of indistinguishable segments created 3813 // by linker scripts. 3814 std::stable_sort(this->segment_list_.begin(), this->segment_list_.end(), 3815 Layout::Compare_segments(this)); 3816 3817 // Find the PT_LOAD segments, and set their addresses and offsets 3818 // and their section's addresses and offsets. 3819 uint64_t start_addr; 3820 if (parameters->options().user_set_Ttext()) 3821 start_addr = parameters->options().Ttext(); 3822 else if (parameters->options().output_is_position_independent()) 3823 start_addr = 0; 3824 else 3825 start_addr = target->default_text_segment_address(); 3826 3827 uint64_t addr = start_addr; 3828 off_t off = 0; 3829 3830 // If LOAD_SEG is NULL, then the file header and segment headers 3831 // will not be loadable. But they still need to be at offset 0 in 3832 // the file. Set their offsets now. 3833 if (load_seg == NULL) 3834 { 3835 for (Data_list::iterator p = this->special_output_list_.begin(); 3836 p != this->special_output_list_.end(); 3837 ++p) 3838 { 3839 off = align_address(off, (*p)->addralign()); 3840 (*p)->set_address_and_file_offset(0, off); 3841 off += (*p)->data_size(); 3842 } 3843 } 3844 3845 unsigned int increase_relro = this->increase_relro_; 3846 if (this->script_options_->saw_sections_clause()) 3847 increase_relro = 0; 3848 3849 const bool check_sections = parameters->options().check_sections(); 3850 Output_segment* last_load_segment = NULL; 3851 3852 unsigned int shndx_begin = *pshndx; 3853 unsigned int shndx_load_seg = *pshndx; 3854 3855 for (Segment_list::iterator p = this->segment_list_.begin(); 3856 p != this->segment_list_.end(); 3857 ++p) 3858 { 3859 if ((*p)->type() == elfcpp::PT_LOAD) 3860 { 3861 if (target->isolate_execinstr()) 3862 { 3863 // When we hit the segment that should contain the 3864 // file headers, reset the file offset so we place 3865 // it and subsequent segments appropriately. 3866 // We'll fix up the preceding segments below. 3867 if (load_seg == *p) 3868 { 3869 if (off == 0) 3870 load_seg = NULL; 3871 else 3872 { 3873 off = 0; 3874 shndx_load_seg = *pshndx; 3875 } 3876 } 3877 } 3878 else 3879 { 3880 // Verify that the file headers fall into the first segment. 3881 if (load_seg != NULL && load_seg != *p) 3882 gold_unreachable(); 3883 load_seg = NULL; 3884 } 3885 3886 bool are_addresses_set = (*p)->are_addresses_set(); 3887 if (are_addresses_set) 3888 { 3889 // When it comes to setting file offsets, we care about 3890 // the physical address. 3891 addr = (*p)->paddr(); 3892 } 3893 else if (parameters->options().user_set_Ttext() 3894 && (parameters->options().omagic() 3895 || is_text_segment(target, *p))) 3896 { 3897 are_addresses_set = true; 3898 } 3899 else if (parameters->options().user_set_Trodata_segment() 3900 && ((*p)->flags() & (elfcpp::PF_W | elfcpp::PF_X)) == 0) 3901 { 3902 addr = parameters->options().Trodata_segment(); 3903 are_addresses_set = true; 3904 } 3905 else if (parameters->options().user_set_Tdata() 3906 && ((*p)->flags() & elfcpp::PF_W) != 0 3907 && (!parameters->options().user_set_Tbss() 3908 || (*p)->has_any_data_sections())) 3909 { 3910 addr = parameters->options().Tdata(); 3911 are_addresses_set = true; 3912 } 3913 else if (parameters->options().user_set_Tbss() 3914 && ((*p)->flags() & elfcpp::PF_W) != 0 3915 && !(*p)->has_any_data_sections()) 3916 { 3917 addr = parameters->options().Tbss(); 3918 are_addresses_set = true; 3919 } 3920 3921 uint64_t orig_addr = addr; 3922 uint64_t orig_off = off; 3923 3924 uint64_t aligned_addr = 0; 3925 uint64_t abi_pagesize = target->abi_pagesize(); 3926 uint64_t common_pagesize = target->common_pagesize(); 3927 3928 if (!parameters->options().nmagic() 3929 && !parameters->options().omagic()) 3930 (*p)->set_minimum_p_align(abi_pagesize); 3931 3932 if (!are_addresses_set) 3933 { 3934 // Skip the address forward one page, maintaining the same 3935 // position within the page. This lets us store both segments 3936 // overlapping on a single page in the file, but the loader will 3937 // put them on different pages in memory. We will revisit this 3938 // decision once we know the size of the segment. 3939 3940 uint64_t max_align = (*p)->maximum_alignment(); 3941 if (max_align > abi_pagesize) 3942 addr = align_address(addr, max_align); 3943 aligned_addr = addr; 3944 3945 if (load_seg == *p) 3946 { 3947 // This is the segment that will contain the file 3948 // headers, so its offset will have to be exactly zero. 3949 gold_assert(orig_off == 0); 3950 3951 // If the target wants a fixed minimum distance from the 3952 // text segment to the read-only segment, move up now. 3953 uint64_t min_addr = 3954 start_addr + (parameters->options().user_set_rosegment_gap() 3955 ? parameters->options().rosegment_gap() 3956 : target->rosegment_gap()); 3957 if (addr < min_addr) 3958 addr = min_addr; 3959 3960 // But this is not the first segment! To make its 3961 // address congruent with its offset, that address better 3962 // be aligned to the ABI-mandated page size. 3963 addr = align_address(addr, abi_pagesize); 3964 aligned_addr = addr; 3965 } 3966 else 3967 { 3968 if ((addr & (abi_pagesize - 1)) != 0) 3969 addr = addr + abi_pagesize; 3970 3971 off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1)); 3972 } 3973 } 3974 3975 if (!parameters->options().nmagic() 3976 && !parameters->options().omagic()) 3977 { 3978 // Here we are also taking care of the case when 3979 // the maximum segment alignment is larger than the page size. 3980 off = align_file_offset(off, addr, 3981 std::max(abi_pagesize, 3982 (*p)->maximum_alignment())); 3983 } 3984 else 3985 { 3986 // This is -N or -n with a section script which prevents 3987 // us from using a load segment. We need to ensure that 3988 // the file offset is aligned to the alignment of the 3989 // segment. This is because the linker script 3990 // implicitly assumed a zero offset. If we don't align 3991 // here, then the alignment of the sections in the 3992 // linker script may not match the alignment of the 3993 // sections in the set_section_addresses call below, 3994 // causing an error about dot moving backward. 3995 off = align_address(off, (*p)->maximum_alignment()); 3996 } 3997 3998 unsigned int shndx_hold = *pshndx; 3999 bool has_relro = false; 4000 uint64_t new_addr = (*p)->set_section_addresses(target, this, 4001 false, addr, 4002 &increase_relro, 4003 &has_relro, 4004 &off, pshndx); 4005 4006 // Now that we know the size of this segment, we may be able 4007 // to save a page in memory, at the cost of wasting some 4008 // file space, by instead aligning to the start of a new 4009 // page. Here we use the real machine page size rather than 4010 // the ABI mandated page size. If the segment has been 4011 // aligned so that the relro data ends at a page boundary, 4012 // we do not try to realign it. 4013 4014 if (!are_addresses_set 4015 && !has_relro 4016 && aligned_addr != addr 4017 && !parameters->incremental()) 4018 { 4019 uint64_t first_off = (common_pagesize 4020 - (aligned_addr 4021 & (common_pagesize - 1))); 4022 uint64_t last_off = new_addr & (common_pagesize - 1); 4023 if (first_off > 0 4024 && last_off > 0 4025 && ((aligned_addr & ~ (common_pagesize - 1)) 4026 != (new_addr & ~ (common_pagesize - 1))) 4027 && first_off + last_off <= common_pagesize) 4028 { 4029 *pshndx = shndx_hold; 4030 addr = align_address(aligned_addr, common_pagesize); 4031 addr = align_address(addr, (*p)->maximum_alignment()); 4032 if ((addr & (abi_pagesize - 1)) != 0) 4033 addr = addr + abi_pagesize; 4034 off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1)); 4035 off = align_file_offset(off, addr, abi_pagesize); 4036 4037 increase_relro = this->increase_relro_; 4038 if (this->script_options_->saw_sections_clause()) 4039 increase_relro = 0; 4040 has_relro = false; 4041 4042 new_addr = (*p)->set_section_addresses(target, this, 4043 true, addr, 4044 &increase_relro, 4045 &has_relro, 4046 &off, pshndx); 4047 } 4048 } 4049 4050 addr = new_addr; 4051 4052 // Implement --check-sections. We know that the segments 4053 // are sorted by LMA. 4054 if (check_sections && last_load_segment != NULL) 4055 { 4056 gold_assert(last_load_segment->paddr() <= (*p)->paddr()); 4057 if (last_load_segment->paddr() + last_load_segment->memsz() 4058 > (*p)->paddr()) 4059 { 4060 unsigned long long lb1 = last_load_segment->paddr(); 4061 unsigned long long le1 = lb1 + last_load_segment->memsz(); 4062 unsigned long long lb2 = (*p)->paddr(); 4063 unsigned long long le2 = lb2 + (*p)->memsz(); 4064 gold_error(_("load segment overlap [0x%llx -> 0x%llx] and " 4065 "[0x%llx -> 0x%llx]"), 4066 lb1, le1, lb2, le2); 4067 } 4068 } 4069 last_load_segment = *p; 4070 } 4071 } 4072 4073 if (load_seg != NULL && target->isolate_execinstr()) 4074 { 4075 // Process the early segments again, setting their file offsets 4076 // so they land after the segments starting at LOAD_SEG. 4077 off = align_file_offset(off, 0, target->abi_pagesize()); 4078 4079 this->reset_relax_output(); 4080 4081 for (Segment_list::iterator p = this->segment_list_.begin(); 4082 *p != load_seg; 4083 ++p) 4084 { 4085 if ((*p)->type() == elfcpp::PT_LOAD) 4086 { 4087 // We repeat the whole job of assigning addresses and 4088 // offsets, but we really only want to change the offsets and 4089 // must ensure that the addresses all come out the same as 4090 // they did the first time through. 4091 bool has_relro = false; 4092 const uint64_t old_addr = (*p)->vaddr(); 4093 const uint64_t old_end = old_addr + (*p)->memsz(); 4094 uint64_t new_addr = (*p)->set_section_addresses(target, this, 4095 true, old_addr, 4096 &increase_relro, 4097 &has_relro, 4098 &off, 4099 &shndx_begin); 4100 gold_assert(new_addr == old_end); 4101 } 4102 } 4103 4104 gold_assert(shndx_begin == shndx_load_seg); 4105 } 4106 4107 // Handle the non-PT_LOAD segments, setting their offsets from their 4108 // section's offsets. 4109 for (Segment_list::iterator p = this->segment_list_.begin(); 4110 p != this->segment_list_.end(); 4111 ++p) 4112 { 4113 // PT_GNU_STACK was set up correctly when it was created. 4114 if ((*p)->type() != elfcpp::PT_LOAD 4115 && (*p)->type() != elfcpp::PT_GNU_STACK) 4116 (*p)->set_offset((*p)->type() == elfcpp::PT_GNU_RELRO 4117 ? increase_relro 4118 : 0); 4119 } 4120 4121 // Set the TLS offsets for each section in the PT_TLS segment. 4122 if (this->tls_segment_ != NULL) 4123 this->tls_segment_->set_tls_offsets(); 4124 4125 return off; 4126 } 4127 4128 // Set the offsets of all the allocated sections when doing a 4129 // relocatable link. This does the same jobs as set_segment_offsets, 4130 // only for a relocatable link. 4131 4132 off_t 4133 Layout::set_relocatable_section_offsets(Output_data* file_header, 4134 unsigned int* pshndx) 4135 { 4136 off_t off = 0; 4137 4138 file_header->set_address_and_file_offset(0, 0); 4139 off += file_header->data_size(); 4140 4141 for (Section_list::iterator p = this->section_list_.begin(); 4142 p != this->section_list_.end(); 4143 ++p) 4144 { 4145 // We skip unallocated sections here, except that group sections 4146 // have to come first. 4147 if (((*p)->flags() & elfcpp::SHF_ALLOC) == 0 4148 && (*p)->type() != elfcpp::SHT_GROUP) 4149 continue; 4150 4151 off = align_address(off, (*p)->addralign()); 4152 4153 // The linker script might have set the address. 4154 if (!(*p)->is_address_valid()) 4155 (*p)->set_address(0); 4156 (*p)->set_file_offset(off); 4157 (*p)->finalize_data_size(); 4158 if ((*p)->type() != elfcpp::SHT_NOBITS) 4159 off += (*p)->data_size(); 4160 4161 (*p)->set_out_shndx(*pshndx); 4162 ++*pshndx; 4163 } 4164 4165 return off; 4166 } 4167 4168 // Set the file offset of all the sections not associated with a 4169 // segment. 4170 4171 off_t 4172 Layout::set_section_offsets(off_t off, Layout::Section_offset_pass pass) 4173 { 4174 off_t startoff = off; 4175 off_t maxoff = off; 4176 4177 for (Section_list::iterator p = this->unattached_section_list_.begin(); 4178 p != this->unattached_section_list_.end(); 4179 ++p) 4180 { 4181 // The symtab section is handled in create_symtab_sections. 4182 if (*p == this->symtab_section_) 4183 continue; 4184 4185 // If we've already set the data size, don't set it again. 4186 if ((*p)->is_offset_valid() && (*p)->is_data_size_valid()) 4187 continue; 4188 4189 if (pass == BEFORE_INPUT_SECTIONS_PASS 4190 && (*p)->requires_postprocessing()) 4191 { 4192 (*p)->create_postprocessing_buffer(); 4193 this->any_postprocessing_sections_ = true; 4194 } 4195 4196 if (pass == BEFORE_INPUT_SECTIONS_PASS 4197 && (*p)->after_input_sections()) 4198 continue; 4199 else if (pass == POSTPROCESSING_SECTIONS_PASS 4200 && (!(*p)->after_input_sections() 4201 || (*p)->type() == elfcpp::SHT_STRTAB)) 4202 continue; 4203 else if (pass == STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS 4204 && (!(*p)->after_input_sections() 4205 || (*p)->type() != elfcpp::SHT_STRTAB)) 4206 continue; 4207 4208 if (!parameters->incremental_update()) 4209 { 4210 off = align_address(off, (*p)->addralign()); 4211 (*p)->set_file_offset(off); 4212 (*p)->finalize_data_size(); 4213 } 4214 else 4215 { 4216 // Incremental update: allocate file space from free list. 4217 (*p)->pre_finalize_data_size(); 4218 off_t current_size = (*p)->current_data_size(); 4219 off = this->allocate(current_size, (*p)->addralign(), startoff); 4220 if (off == -1) 4221 { 4222 if (is_debugging_enabled(DEBUG_INCREMENTAL)) 4223 this->free_list_.dump(); 4224 gold_assert((*p)->output_section() != NULL); 4225 gold_fallback(_("out of patch space for section %s; " 4226 "relink with --incremental-full"), 4227 (*p)->output_section()->name()); 4228 } 4229 (*p)->set_file_offset(off); 4230 (*p)->finalize_data_size(); 4231 if ((*p)->data_size() > current_size) 4232 { 4233 gold_assert((*p)->output_section() != NULL); 4234 gold_fallback(_("%s: section changed size; " 4235 "relink with --incremental-full"), 4236 (*p)->output_section()->name()); 4237 } 4238 gold_debug(DEBUG_INCREMENTAL, 4239 "set_section_offsets: %08lx %08lx %s", 4240 static_cast<long>(off), 4241 static_cast<long>((*p)->data_size()), 4242 ((*p)->output_section() != NULL 4243 ? (*p)->output_section()->name() : "(special)")); 4244 } 4245 4246 off += (*p)->data_size(); 4247 if (off > maxoff) 4248 maxoff = off; 4249 4250 // At this point the name must be set. 4251 if (pass != STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS) 4252 this->namepool_.add((*p)->name(), false, NULL); 4253 } 4254 return maxoff; 4255 } 4256 4257 // Set the section indexes of all the sections not associated with a 4258 // segment. 4259 4260 unsigned int 4261 Layout::set_section_indexes(unsigned int shndx) 4262 { 4263 for (Section_list::iterator p = this->unattached_section_list_.begin(); 4264 p != this->unattached_section_list_.end(); 4265 ++p) 4266 { 4267 if (!(*p)->has_out_shndx()) 4268 { 4269 (*p)->set_out_shndx(shndx); 4270 ++shndx; 4271 } 4272 } 4273 return shndx; 4274 } 4275 4276 // Set the section addresses according to the linker script. This is 4277 // only called when we see a SECTIONS clause. This returns the 4278 // program segment which should hold the file header and segment 4279 // headers, if any. It will return NULL if they should not be in a 4280 // segment. 4281 4282 Output_segment* 4283 Layout::set_section_addresses_from_script(Symbol_table* symtab) 4284 { 4285 Script_sections* ss = this->script_options_->script_sections(); 4286 gold_assert(ss->saw_sections_clause()); 4287 return this->script_options_->set_section_addresses(symtab, this); 4288 } 4289 4290 // Place the orphan sections in the linker script. 4291 4292 void 4293 Layout::place_orphan_sections_in_script() 4294 { 4295 Script_sections* ss = this->script_options_->script_sections(); 4296 gold_assert(ss->saw_sections_clause()); 4297 4298 // Place each orphaned output section in the script. 4299 for (Section_list::iterator p = this->section_list_.begin(); 4300 p != this->section_list_.end(); 4301 ++p) 4302 { 4303 if (!(*p)->found_in_sections_clause()) 4304 ss->place_orphan(*p); 4305 } 4306 } 4307 4308 // Count the local symbols in the regular symbol table and the dynamic 4309 // symbol table, and build the respective string pools. 4310 4311 void 4312 Layout::count_local_symbols(const Task* task, 4313 const Input_objects* input_objects) 4314 { 4315 // First, figure out an upper bound on the number of symbols we'll 4316 // be inserting into each pool. This helps us create the pools with 4317 // the right size, to avoid unnecessary hashtable resizing. 4318 unsigned int symbol_count = 0; 4319 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 4320 p != input_objects->relobj_end(); 4321 ++p) 4322 symbol_count += (*p)->local_symbol_count(); 4323 4324 // Go from "upper bound" to "estimate." We overcount for two 4325 // reasons: we double-count symbols that occur in more than one 4326 // object file, and we count symbols that are dropped from the 4327 // output. Add it all together and assume we overcount by 100%. 4328 symbol_count /= 2; 4329 4330 // We assume all symbols will go into both the sympool and dynpool. 4331 this->sympool_.reserve(symbol_count); 4332 this->dynpool_.reserve(symbol_count); 4333 4334 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 4335 p != input_objects->relobj_end(); 4336 ++p) 4337 { 4338 Task_lock_obj<Object> tlo(task, *p); 4339 (*p)->count_local_symbols(&this->sympool_, &this->dynpool_); 4340 } 4341 } 4342 4343 // Create the symbol table sections. Here we also set the final 4344 // values of the symbols. At this point all the loadable sections are 4345 // fully laid out. SHNUM is the number of sections so far. 4346 4347 void 4348 Layout::create_symtab_sections(const Input_objects* input_objects, 4349 Symbol_table* symtab, 4350 unsigned int shnum, 4351 off_t* poff, 4352 unsigned int local_dynamic_count) 4353 { 4354 int symsize; 4355 unsigned int align; 4356 if (parameters->target().get_size() == 32) 4357 { 4358 symsize = elfcpp::Elf_sizes<32>::sym_size; 4359 align = 4; 4360 } 4361 else if (parameters->target().get_size() == 64) 4362 { 4363 symsize = elfcpp::Elf_sizes<64>::sym_size; 4364 align = 8; 4365 } 4366 else 4367 gold_unreachable(); 4368 4369 // Compute file offsets relative to the start of the symtab section. 4370 off_t off = 0; 4371 4372 // Save space for the dummy symbol at the start of the section. We 4373 // never bother to write this out--it will just be left as zero. 4374 off += symsize; 4375 unsigned int local_symbol_index = 1; 4376 4377 // Add STT_SECTION symbols for each Output section which needs one. 4378 for (Section_list::iterator p = this->section_list_.begin(); 4379 p != this->section_list_.end(); 4380 ++p) 4381 { 4382 if (!(*p)->needs_symtab_index()) 4383 (*p)->set_symtab_index(-1U); 4384 else 4385 { 4386 (*p)->set_symtab_index(local_symbol_index); 4387 ++local_symbol_index; 4388 off += symsize; 4389 } 4390 } 4391 4392 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 4393 p != input_objects->relobj_end(); 4394 ++p) 4395 { 4396 unsigned int index = (*p)->finalize_local_symbols(local_symbol_index, 4397 off, symtab); 4398 off += (index - local_symbol_index) * symsize; 4399 local_symbol_index = index; 4400 } 4401 4402 unsigned int local_symcount = local_symbol_index; 4403 gold_assert(static_cast<off_t>(local_symcount * symsize) == off); 4404 4405 off_t dynoff; 4406 size_t dyncount; 4407 if (this->dynsym_section_ == NULL) 4408 { 4409 dynoff = 0; 4410 dyncount = 0; 4411 } 4412 else 4413 { 4414 off_t locsize = local_dynamic_count * this->dynsym_section_->entsize(); 4415 dynoff = this->dynsym_section_->offset() + locsize; 4416 dyncount = (this->dynsym_section_->data_size() - locsize) / symsize; 4417 gold_assert(static_cast<off_t>(dyncount * symsize) 4418 == this->dynsym_section_->data_size() - locsize); 4419 } 4420 4421 off_t global_off = off; 4422 off = symtab->finalize(off, dynoff, local_dynamic_count, dyncount, 4423 &this->sympool_, &local_symcount); 4424 4425 if (!parameters->options().strip_all()) 4426 { 4427 this->sympool_.set_string_offsets(); 4428 4429 const char* symtab_name = this->namepool_.add(".symtab", false, NULL); 4430 Output_section* osymtab = this->make_output_section(symtab_name, 4431 elfcpp::SHT_SYMTAB, 4432 0, ORDER_INVALID, 4433 false); 4434 this->symtab_section_ = osymtab; 4435 4436 Output_section_data* pos = new Output_data_fixed_space(off, align, 4437 "** symtab"); 4438 osymtab->add_output_section_data(pos); 4439 4440 // We generate a .symtab_shndx section if we have more than 4441 // SHN_LORESERVE sections. Technically it is possible that we 4442 // don't need one, because it is possible that there are no 4443 // symbols in any of sections with indexes larger than 4444 // SHN_LORESERVE. That is probably unusual, though, and it is 4445 // easier to always create one than to compute section indexes 4446 // twice (once here, once when writing out the symbols). 4447 if (shnum >= elfcpp::SHN_LORESERVE) 4448 { 4449 const char* symtab_xindex_name = this->namepool_.add(".symtab_shndx", 4450 false, NULL); 4451 Output_section* osymtab_xindex = 4452 this->make_output_section(symtab_xindex_name, 4453 elfcpp::SHT_SYMTAB_SHNDX, 0, 4454 ORDER_INVALID, false); 4455 4456 size_t symcount = off / symsize; 4457 this->symtab_xindex_ = new Output_symtab_xindex(symcount); 4458 4459 osymtab_xindex->add_output_section_data(this->symtab_xindex_); 4460 4461 osymtab_xindex->set_link_section(osymtab); 4462 osymtab_xindex->set_addralign(4); 4463 osymtab_xindex->set_entsize(4); 4464 4465 osymtab_xindex->set_after_input_sections(); 4466 4467 // This tells the driver code to wait until the symbol table 4468 // has written out before writing out the postprocessing 4469 // sections, including the .symtab_shndx section. 4470 this->any_postprocessing_sections_ = true; 4471 } 4472 4473 const char* strtab_name = this->namepool_.add(".strtab", false, NULL); 4474 Output_section* ostrtab = this->make_output_section(strtab_name, 4475 elfcpp::SHT_STRTAB, 4476 0, ORDER_INVALID, 4477 false); 4478 4479 Output_section_data* pstr = new Output_data_strtab(&this->sympool_); 4480 ostrtab->add_output_section_data(pstr); 4481 4482 off_t symtab_off; 4483 if (!parameters->incremental_update()) 4484 symtab_off = align_address(*poff, align); 4485 else 4486 { 4487 symtab_off = this->allocate(off, align, *poff); 4488 if (off == -1) 4489 gold_fallback(_("out of patch space for symbol table; " 4490 "relink with --incremental-full")); 4491 gold_debug(DEBUG_INCREMENTAL, 4492 "create_symtab_sections: %08lx %08lx .symtab", 4493 static_cast<long>(symtab_off), 4494 static_cast<long>(off)); 4495 } 4496 4497 symtab->set_file_offset(symtab_off + global_off); 4498 osymtab->set_file_offset(symtab_off); 4499 osymtab->finalize_data_size(); 4500 osymtab->set_link_section(ostrtab); 4501 osymtab->set_info(local_symcount); 4502 osymtab->set_entsize(symsize); 4503 4504 if (symtab_off + off > *poff) 4505 *poff = symtab_off + off; 4506 } 4507 } 4508 4509 // Create the .shstrtab section, which holds the names of the 4510 // sections. At the time this is called, we have created all the 4511 // output sections except .shstrtab itself. 4512 4513 Output_section* 4514 Layout::create_shstrtab() 4515 { 4516 // FIXME: We don't need to create a .shstrtab section if we are 4517 // stripping everything. 4518 4519 const char* name = this->namepool_.add(".shstrtab", false, NULL); 4520 4521 Output_section* os = this->make_output_section(name, elfcpp::SHT_STRTAB, 0, 4522 ORDER_INVALID, false); 4523 4524 if (strcmp(parameters->options().compress_debug_sections(), "none") != 0) 4525 { 4526 // We can't write out this section until we've set all the 4527 // section names, and we don't set the names of compressed 4528 // output sections until relocations are complete. FIXME: With 4529 // the current names we use, this is unnecessary. 4530 os->set_after_input_sections(); 4531 } 4532 4533 Output_section_data* posd = new Output_data_strtab(&this->namepool_); 4534 os->add_output_section_data(posd); 4535 4536 return os; 4537 } 4538 4539 // Create the section headers. SIZE is 32 or 64. OFF is the file 4540 // offset. 4541 4542 void 4543 Layout::create_shdrs(const Output_section* shstrtab_section, off_t* poff) 4544 { 4545 Output_section_headers* oshdrs; 4546 oshdrs = new Output_section_headers(this, 4547 &this->segment_list_, 4548 &this->section_list_, 4549 &this->unattached_section_list_, 4550 &this->namepool_, 4551 shstrtab_section); 4552 off_t off; 4553 if (!parameters->incremental_update()) 4554 off = align_address(*poff, oshdrs->addralign()); 4555 else 4556 { 4557 oshdrs->pre_finalize_data_size(); 4558 off = this->allocate(oshdrs->data_size(), oshdrs->addralign(), *poff); 4559 if (off == -1) 4560 gold_fallback(_("out of patch space for section header table; " 4561 "relink with --incremental-full")); 4562 gold_debug(DEBUG_INCREMENTAL, 4563 "create_shdrs: %08lx %08lx (section header table)", 4564 static_cast<long>(off), 4565 static_cast<long>(off + oshdrs->data_size())); 4566 } 4567 oshdrs->set_address_and_file_offset(0, off); 4568 off += oshdrs->data_size(); 4569 if (off > *poff) 4570 *poff = off; 4571 this->section_headers_ = oshdrs; 4572 } 4573 4574 // Count the allocated sections. 4575 4576 size_t 4577 Layout::allocated_output_section_count() const 4578 { 4579 size_t section_count = 0; 4580 for (Segment_list::const_iterator p = this->segment_list_.begin(); 4581 p != this->segment_list_.end(); 4582 ++p) 4583 section_count += (*p)->output_section_count(); 4584 return section_count; 4585 } 4586 4587 // Create the dynamic symbol table. 4588 // *PLOCAL_DYNAMIC_COUNT will be set to the number of local symbols 4589 // from input objects, and *PFORCED_LOCAL_DYNAMIC_COUNT will be set 4590 // to the number of global symbols that have been forced local. 4591 // We need to remember the former because the forced-local symbols are 4592 // written along with the global symbols in Symtab::write_globals(). 4593 4594 void 4595 Layout::create_dynamic_symtab(const Input_objects* input_objects, 4596 Symbol_table* symtab, 4597 Output_section** pdynstr, 4598 unsigned int* plocal_dynamic_count, 4599 unsigned int* pforced_local_dynamic_count, 4600 std::vector<Symbol*>* pdynamic_symbols, 4601 Versions* pversions) 4602 { 4603 // Count all the symbols in the dynamic symbol table, and set the 4604 // dynamic symbol indexes. 4605 4606 // Skip symbol 0, which is always all zeroes. 4607 unsigned int index = 1; 4608 4609 // Add STT_SECTION symbols for each Output section which needs one. 4610 for (Section_list::iterator p = this->section_list_.begin(); 4611 p != this->section_list_.end(); 4612 ++p) 4613 { 4614 if (!(*p)->needs_dynsym_index()) 4615 (*p)->set_dynsym_index(-1U); 4616 else 4617 { 4618 (*p)->set_dynsym_index(index); 4619 ++index; 4620 } 4621 } 4622 4623 // Count the local symbols that need to go in the dynamic symbol table, 4624 // and set the dynamic symbol indexes. 4625 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 4626 p != input_objects->relobj_end(); 4627 ++p) 4628 { 4629 unsigned int new_index = (*p)->set_local_dynsym_indexes(index); 4630 index = new_index; 4631 } 4632 4633 unsigned int local_symcount = index; 4634 unsigned int forced_local_count = 0; 4635 4636 index = symtab->set_dynsym_indexes(index, &forced_local_count, 4637 pdynamic_symbols, &this->dynpool_, 4638 pversions); 4639 4640 *plocal_dynamic_count = local_symcount; 4641 *pforced_local_dynamic_count = forced_local_count; 4642 4643 int symsize; 4644 unsigned int align; 4645 const int size = parameters->target().get_size(); 4646 if (size == 32) 4647 { 4648 symsize = elfcpp::Elf_sizes<32>::sym_size; 4649 align = 4; 4650 } 4651 else if (size == 64) 4652 { 4653 symsize = elfcpp::Elf_sizes<64>::sym_size; 4654 align = 8; 4655 } 4656 else 4657 gold_unreachable(); 4658 4659 // Create the dynamic symbol table section. 4660 4661 Output_section* dynsym = this->choose_output_section(NULL, ".dynsym", 4662 elfcpp::SHT_DYNSYM, 4663 elfcpp::SHF_ALLOC, 4664 false, 4665 ORDER_DYNAMIC_LINKER, 4666 false, false, false); 4667 4668 // Check for NULL as a linker script may discard .dynsym. 4669 if (dynsym != NULL) 4670 { 4671 Output_section_data* odata = new Output_data_fixed_space(index * symsize, 4672 align, 4673 "** dynsym"); 4674 dynsym->add_output_section_data(odata); 4675 4676 dynsym->set_info(local_symcount + forced_local_count); 4677 dynsym->set_entsize(symsize); 4678 dynsym->set_addralign(align); 4679 4680 this->dynsym_section_ = dynsym; 4681 } 4682 4683 Output_data_dynamic* const odyn = this->dynamic_data_; 4684 if (odyn != NULL) 4685 { 4686 odyn->add_section_address(elfcpp::DT_SYMTAB, dynsym); 4687 odyn->add_constant(elfcpp::DT_SYMENT, symsize); 4688 } 4689 4690 // If there are more than SHN_LORESERVE allocated sections, we 4691 // create a .dynsym_shndx section. It is possible that we don't 4692 // need one, because it is possible that there are no dynamic 4693 // symbols in any of the sections with indexes larger than 4694 // SHN_LORESERVE. This is probably unusual, though, and at this 4695 // time we don't know the actual section indexes so it is 4696 // inconvenient to check. 4697 if (this->allocated_output_section_count() >= elfcpp::SHN_LORESERVE) 4698 { 4699 Output_section* dynsym_xindex = 4700 this->choose_output_section(NULL, ".dynsym_shndx", 4701 elfcpp::SHT_SYMTAB_SHNDX, 4702 elfcpp::SHF_ALLOC, 4703 false, ORDER_DYNAMIC_LINKER, false, false, 4704 false); 4705 4706 if (dynsym_xindex != NULL) 4707 { 4708 this->dynsym_xindex_ = new Output_symtab_xindex(index); 4709 4710 dynsym_xindex->add_output_section_data(this->dynsym_xindex_); 4711 4712 dynsym_xindex->set_link_section(dynsym); 4713 dynsym_xindex->set_addralign(4); 4714 dynsym_xindex->set_entsize(4); 4715 4716 dynsym_xindex->set_after_input_sections(); 4717 4718 // This tells the driver code to wait until the symbol table 4719 // has written out before writing out the postprocessing 4720 // sections, including the .dynsym_shndx section. 4721 this->any_postprocessing_sections_ = true; 4722 } 4723 } 4724 4725 // Create the dynamic string table section. 4726 4727 Output_section* dynstr = this->choose_output_section(NULL, ".dynstr", 4728 elfcpp::SHT_STRTAB, 4729 elfcpp::SHF_ALLOC, 4730 false, 4731 ORDER_DYNAMIC_LINKER, 4732 false, false, false); 4733 *pdynstr = dynstr; 4734 if (dynstr != NULL) 4735 { 4736 Output_section_data* strdata = new Output_data_strtab(&this->dynpool_); 4737 dynstr->add_output_section_data(strdata); 4738 4739 if (dynsym != NULL) 4740 dynsym->set_link_section(dynstr); 4741 if (this->dynamic_section_ != NULL) 4742 this->dynamic_section_->set_link_section(dynstr); 4743 4744 if (odyn != NULL) 4745 { 4746 odyn->add_section_address(elfcpp::DT_STRTAB, dynstr); 4747 odyn->add_section_size(elfcpp::DT_STRSZ, dynstr); 4748 } 4749 } 4750 4751 // Create the hash tables. The Gnu-style hash table must be 4752 // built first, because it changes the order of the symbols 4753 // in the dynamic symbol table. 4754 4755 if (strcmp(parameters->options().hash_style(), "gnu") == 0 4756 || strcmp(parameters->options().hash_style(), "both") == 0) 4757 { 4758 unsigned char* phash; 4759 unsigned int hashlen; 4760 Dynobj::create_gnu_hash_table(*pdynamic_symbols, 4761 local_symcount + forced_local_count, 4762 &phash, &hashlen); 4763 4764 Output_section* hashsec = 4765 this->choose_output_section(NULL, ".gnu.hash", elfcpp::SHT_GNU_HASH, 4766 elfcpp::SHF_ALLOC, false, 4767 ORDER_DYNAMIC_LINKER, false, false, 4768 false); 4769 4770 Output_section_data* hashdata = new Output_data_const_buffer(phash, 4771 hashlen, 4772 align, 4773 "** hash"); 4774 if (hashsec != NULL && hashdata != NULL) 4775 hashsec->add_output_section_data(hashdata); 4776 4777 if (hashsec != NULL) 4778 { 4779 if (dynsym != NULL) 4780 hashsec->set_link_section(dynsym); 4781 4782 // For a 64-bit target, the entries in .gnu.hash do not have 4783 // a uniform size, so we only set the entry size for a 4784 // 32-bit target. 4785 if (parameters->target().get_size() == 32) 4786 hashsec->set_entsize(4); 4787 4788 if (odyn != NULL) 4789 odyn->add_section_address(elfcpp::DT_GNU_HASH, hashsec); 4790 } 4791 } 4792 4793 if (strcmp(parameters->options().hash_style(), "sysv") == 0 4794 || strcmp(parameters->options().hash_style(), "both") == 0) 4795 { 4796 unsigned char* phash; 4797 unsigned int hashlen; 4798 Dynobj::create_elf_hash_table(*pdynamic_symbols, 4799 local_symcount + forced_local_count, 4800 &phash, &hashlen); 4801 4802 Output_section* hashsec = 4803 this->choose_output_section(NULL, ".hash", elfcpp::SHT_HASH, 4804 elfcpp::SHF_ALLOC, false, 4805 ORDER_DYNAMIC_LINKER, false, false, 4806 false); 4807 4808 Output_section_data* hashdata = new Output_data_const_buffer(phash, 4809 hashlen, 4810 align, 4811 "** hash"); 4812 if (hashsec != NULL && hashdata != NULL) 4813 hashsec->add_output_section_data(hashdata); 4814 4815 if (hashsec != NULL) 4816 { 4817 if (dynsym != NULL) 4818 hashsec->set_link_section(dynsym); 4819 hashsec->set_entsize(parameters->target().hash_entry_size() / 8); 4820 } 4821 4822 if (odyn != NULL) 4823 odyn->add_section_address(elfcpp::DT_HASH, hashsec); 4824 } 4825 } 4826 4827 // Assign offsets to each local portion of the dynamic symbol table. 4828 4829 void 4830 Layout::assign_local_dynsym_offsets(const Input_objects* input_objects) 4831 { 4832 Output_section* dynsym = this->dynsym_section_; 4833 if (dynsym == NULL) 4834 return; 4835 4836 off_t off = dynsym->offset(); 4837 4838 // Skip the dummy symbol at the start of the section. 4839 off += dynsym->entsize(); 4840 4841 for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); 4842 p != input_objects->relobj_end(); 4843 ++p) 4844 { 4845 unsigned int count = (*p)->set_local_dynsym_offset(off); 4846 off += count * dynsym->entsize(); 4847 } 4848 } 4849 4850 // Create the version sections. 4851 4852 void 4853 Layout::create_version_sections(const Versions* versions, 4854 const Symbol_table* symtab, 4855 unsigned int local_symcount, 4856 const std::vector<Symbol*>& dynamic_symbols, 4857 const Output_section* dynstr) 4858 { 4859 if (!versions->any_defs() && !versions->any_needs()) 4860 return; 4861 4862 switch (parameters->size_and_endianness()) 4863 { 4864 #ifdef HAVE_TARGET_32_LITTLE 4865 case Parameters::TARGET_32_LITTLE: 4866 this->sized_create_version_sections<32, false>(versions, symtab, 4867 local_symcount, 4868 dynamic_symbols, dynstr); 4869 break; 4870 #endif 4871 #ifdef HAVE_TARGET_32_BIG 4872 case Parameters::TARGET_32_BIG: 4873 this->sized_create_version_sections<32, true>(versions, symtab, 4874 local_symcount, 4875 dynamic_symbols, dynstr); 4876 break; 4877 #endif 4878 #ifdef HAVE_TARGET_64_LITTLE 4879 case Parameters::TARGET_64_LITTLE: 4880 this->sized_create_version_sections<64, false>(versions, symtab, 4881 local_symcount, 4882 dynamic_symbols, dynstr); 4883 break; 4884 #endif 4885 #ifdef HAVE_TARGET_64_BIG 4886 case Parameters::TARGET_64_BIG: 4887 this->sized_create_version_sections<64, true>(versions, symtab, 4888 local_symcount, 4889 dynamic_symbols, dynstr); 4890 break; 4891 #endif 4892 default: 4893 gold_unreachable(); 4894 } 4895 } 4896 4897 // Create the version sections, sized version. 4898 4899 template<int size, bool big_endian> 4900 void 4901 Layout::sized_create_version_sections( 4902 const Versions* versions, 4903 const Symbol_table* symtab, 4904 unsigned int local_symcount, 4905 const std::vector<Symbol*>& dynamic_symbols, 4906 const Output_section* dynstr) 4907 { 4908 Output_section* vsec = this->choose_output_section(NULL, ".gnu.version", 4909 elfcpp::SHT_GNU_versym, 4910 elfcpp::SHF_ALLOC, 4911 false, 4912 ORDER_DYNAMIC_LINKER, 4913 false, false, false); 4914 4915 // Check for NULL since a linker script may discard this section. 4916 if (vsec != NULL) 4917 { 4918 unsigned char* vbuf; 4919 unsigned int vsize; 4920 versions->symbol_section_contents<size, big_endian>(symtab, 4921 &this->dynpool_, 4922 local_symcount, 4923 dynamic_symbols, 4924 &vbuf, &vsize); 4925 4926 Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2, 4927 "** versions"); 4928 4929 vsec->add_output_section_data(vdata); 4930 vsec->set_entsize(2); 4931 vsec->set_link_section(this->dynsym_section_); 4932 } 4933 4934 Output_data_dynamic* const odyn = this->dynamic_data_; 4935 if (odyn != NULL && vsec != NULL) 4936 odyn->add_section_address(elfcpp::DT_VERSYM, vsec); 4937 4938 if (versions->any_defs()) 4939 { 4940 Output_section* vdsec; 4941 vdsec = this->choose_output_section(NULL, ".gnu.version_d", 4942 elfcpp::SHT_GNU_verdef, 4943 elfcpp::SHF_ALLOC, 4944 false, ORDER_DYNAMIC_LINKER, false, 4945 false, false); 4946 4947 if (vdsec != NULL) 4948 { 4949 unsigned char* vdbuf; 4950 unsigned int vdsize; 4951 unsigned int vdentries; 4952 versions->def_section_contents<size, big_endian>(&this->dynpool_, 4953 &vdbuf, &vdsize, 4954 &vdentries); 4955 4956 Output_section_data* vddata = 4957 new Output_data_const_buffer(vdbuf, vdsize, 4, "** version defs"); 4958 4959 vdsec->add_output_section_data(vddata); 4960 vdsec->set_link_section(dynstr); 4961 vdsec->set_info(vdentries); 4962 4963 if (odyn != NULL) 4964 { 4965 odyn->add_section_address(elfcpp::DT_VERDEF, vdsec); 4966 odyn->add_constant(elfcpp::DT_VERDEFNUM, vdentries); 4967 } 4968 } 4969 } 4970 4971 if (versions->any_needs()) 4972 { 4973 Output_section* vnsec; 4974 vnsec = this->choose_output_section(NULL, ".gnu.version_r", 4975 elfcpp::SHT_GNU_verneed, 4976 elfcpp::SHF_ALLOC, 4977 false, ORDER_DYNAMIC_LINKER, false, 4978 false, false); 4979 4980 if (vnsec != NULL) 4981 { 4982 unsigned char* vnbuf; 4983 unsigned int vnsize; 4984 unsigned int vnentries; 4985 versions->need_section_contents<size, big_endian>(&this->dynpool_, 4986 &vnbuf, &vnsize, 4987 &vnentries); 4988 4989 Output_section_data* vndata = 4990 new Output_data_const_buffer(vnbuf, vnsize, 4, "** version refs"); 4991 4992 vnsec->add_output_section_data(vndata); 4993 vnsec->set_link_section(dynstr); 4994 vnsec->set_info(vnentries); 4995 4996 if (odyn != NULL) 4997 { 4998 odyn->add_section_address(elfcpp::DT_VERNEED, vnsec); 4999 odyn->add_constant(elfcpp::DT_VERNEEDNUM, vnentries); 5000 } 5001 } 5002 } 5003 } 5004 5005 // Create the .interp section and PT_INTERP segment. 5006 5007 void 5008 Layout::create_interp(const Target* target) 5009 { 5010 gold_assert(this->interp_segment_ == NULL); 5011 5012 const char* interp = parameters->options().dynamic_linker(); 5013 if (interp == NULL) 5014 { 5015 interp = target->dynamic_linker(); 5016 gold_assert(interp != NULL); 5017 } 5018 5019 size_t len = strlen(interp) + 1; 5020 5021 Output_section_data* odata = new Output_data_const(interp, len, 1); 5022 5023 Output_section* osec = this->choose_output_section(NULL, ".interp", 5024 elfcpp::SHT_PROGBITS, 5025 elfcpp::SHF_ALLOC, 5026 false, ORDER_INTERP, 5027 false, false, false); 5028 if (osec != NULL) 5029 osec->add_output_section_data(odata); 5030 } 5031 5032 // Add dynamic tags for the PLT and the dynamic relocs. This is 5033 // called by the target-specific code. This does nothing if not doing 5034 // a dynamic link. 5035 5036 // USE_REL is true for REL relocs rather than RELA relocs. 5037 5038 // If PLT_GOT is not NULL, then DT_PLTGOT points to it. 5039 5040 // If PLT_REL is not NULL, it is used for DT_PLTRELSZ, and DT_JMPREL, 5041 // and we also set DT_PLTREL. We use PLT_REL's output section, since 5042 // some targets have multiple reloc sections in PLT_REL. 5043 5044 // If DYN_REL is not NULL, it is used for DT_REL/DT_RELA, 5045 // DT_RELSZ/DT_RELASZ, DT_RELENT/DT_RELAENT. Again we use the output 5046 // section. 5047 5048 // If ADD_DEBUG is true, we add a DT_DEBUG entry when generating an 5049 // executable. 5050 5051 void 5052 Layout::add_target_dynamic_tags(bool use_rel, const Output_data* plt_got, 5053 const Output_data* plt_rel, 5054 const Output_data_reloc_generic* dyn_rel, 5055 bool add_debug, bool dynrel_includes_plt) 5056 { 5057 Output_data_dynamic* odyn = this->dynamic_data_; 5058 if (odyn == NULL) 5059 return; 5060 5061 if (plt_got != NULL && plt_got->output_section() != NULL) 5062 odyn->add_section_address(elfcpp::DT_PLTGOT, plt_got); 5063 5064 if (plt_rel != NULL && plt_rel->output_section() != NULL) 5065 { 5066 odyn->add_section_size(elfcpp::DT_PLTRELSZ, plt_rel->output_section()); 5067 odyn->add_section_address(elfcpp::DT_JMPREL, plt_rel->output_section()); 5068 odyn->add_constant(elfcpp::DT_PLTREL, 5069 use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA); 5070 } 5071 5072 if ((dyn_rel != NULL && dyn_rel->output_section() != NULL) 5073 || (dynrel_includes_plt 5074 && plt_rel != NULL 5075 && plt_rel->output_section() != NULL)) 5076 { 5077 bool have_dyn_rel = dyn_rel != NULL && dyn_rel->output_section() != NULL; 5078 bool have_plt_rel = plt_rel != NULL && plt_rel->output_section() != NULL; 5079 odyn->add_section_address(use_rel ? elfcpp::DT_REL : elfcpp::DT_RELA, 5080 (have_dyn_rel 5081 ? dyn_rel->output_section() 5082 : plt_rel->output_section())); 5083 elfcpp::DT size_tag = use_rel ? elfcpp::DT_RELSZ : elfcpp::DT_RELASZ; 5084 if (have_dyn_rel && have_plt_rel && dynrel_includes_plt) 5085 odyn->add_section_size(size_tag, 5086 dyn_rel->output_section(), 5087 plt_rel->output_section()); 5088 else if (have_dyn_rel) 5089 odyn->add_section_size(size_tag, dyn_rel->output_section()); 5090 else 5091 odyn->add_section_size(size_tag, plt_rel->output_section()); 5092 const int size = parameters->target().get_size(); 5093 elfcpp::DT rel_tag; 5094 int rel_size; 5095 if (use_rel) 5096 { 5097 rel_tag = elfcpp::DT_RELENT; 5098 if (size == 32) 5099 rel_size = Reloc_types<elfcpp::SHT_REL, 32, false>::reloc_size; 5100 else if (size == 64) 5101 rel_size = Reloc_types<elfcpp::SHT_REL, 64, false>::reloc_size; 5102 else 5103 gold_unreachable(); 5104 } 5105 else 5106 { 5107 rel_tag = elfcpp::DT_RELAENT; 5108 if (size == 32) 5109 rel_size = Reloc_types<elfcpp::SHT_RELA, 32, false>::reloc_size; 5110 else if (size == 64) 5111 rel_size = Reloc_types<elfcpp::SHT_RELA, 64, false>::reloc_size; 5112 else 5113 gold_unreachable(); 5114 } 5115 odyn->add_constant(rel_tag, rel_size); 5116 5117 if (parameters->options().combreloc() && have_dyn_rel) 5118 { 5119 size_t c = dyn_rel->relative_reloc_count(); 5120 if (c > 0) 5121 odyn->add_constant((use_rel 5122 ? elfcpp::DT_RELCOUNT 5123 : elfcpp::DT_RELACOUNT), 5124 c); 5125 } 5126 } 5127 5128 if (add_debug && !parameters->options().shared()) 5129 { 5130 // The value of the DT_DEBUG tag is filled in by the dynamic 5131 // linker at run time, and used by the debugger. 5132 odyn->add_constant(elfcpp::DT_DEBUG, 0); 5133 } 5134 } 5135 5136 void 5137 Layout::add_target_specific_dynamic_tag(elfcpp::DT tag, unsigned int val) 5138 { 5139 Output_data_dynamic* odyn = this->dynamic_data_; 5140 if (odyn == NULL) 5141 return; 5142 odyn->add_constant(tag, val); 5143 } 5144 5145 // Finish the .dynamic section and PT_DYNAMIC segment. 5146 5147 void 5148 Layout::finish_dynamic_section(const Input_objects* input_objects, 5149 const Symbol_table* symtab) 5150 { 5151 if (!this->script_options_->saw_phdrs_clause() 5152 && this->dynamic_section_ != NULL) 5153 { 5154 Output_segment* oseg = this->make_output_segment(elfcpp::PT_DYNAMIC, 5155 (elfcpp::PF_R 5156 | elfcpp::PF_W)); 5157 oseg->add_output_section_to_nonload(this->dynamic_section_, 5158 elfcpp::PF_R | elfcpp::PF_W); 5159 } 5160 5161 Output_data_dynamic* const odyn = this->dynamic_data_; 5162 if (odyn == NULL) 5163 return; 5164 5165 for (Input_objects::Dynobj_iterator p = input_objects->dynobj_begin(); 5166 p != input_objects->dynobj_end(); 5167 ++p) 5168 { 5169 if (!(*p)->is_needed() && (*p)->as_needed()) 5170 { 5171 // This dynamic object was linked with --as-needed, but it 5172 // is not needed. 5173 continue; 5174 } 5175 5176 odyn->add_string(elfcpp::DT_NEEDED, (*p)->soname()); 5177 } 5178 5179 if (parameters->options().shared()) 5180 { 5181 const char* soname = parameters->options().soname(); 5182 if (soname != NULL) 5183 odyn->add_string(elfcpp::DT_SONAME, soname); 5184 } 5185 5186 Symbol* sym = symtab->lookup(parameters->options().init()); 5187 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj()) 5188 odyn->add_symbol(elfcpp::DT_INIT, sym); 5189 5190 sym = symtab->lookup(parameters->options().fini()); 5191 if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj()) 5192 odyn->add_symbol(elfcpp::DT_FINI, sym); 5193 5194 // Look for .init_array, .preinit_array and .fini_array by checking 5195 // section types. 5196 for(Layout::Section_list::const_iterator p = this->section_list_.begin(); 5197 p != this->section_list_.end(); 5198 ++p) 5199 switch((*p)->type()) 5200 { 5201 case elfcpp::SHT_FINI_ARRAY: 5202 odyn->add_section_address(elfcpp::DT_FINI_ARRAY, *p); 5203 odyn->add_section_size(elfcpp::DT_FINI_ARRAYSZ, *p); 5204 break; 5205 case elfcpp::SHT_INIT_ARRAY: 5206 odyn->add_section_address(elfcpp::DT_INIT_ARRAY, *p); 5207 odyn->add_section_size(elfcpp::DT_INIT_ARRAYSZ, *p); 5208 break; 5209 case elfcpp::SHT_PREINIT_ARRAY: 5210 odyn->add_section_address(elfcpp::DT_PREINIT_ARRAY, *p); 5211 odyn->add_section_size(elfcpp::DT_PREINIT_ARRAYSZ, *p); 5212 break; 5213 default: 5214 break; 5215 } 5216 5217 // Add a DT_RPATH entry if needed. 5218 const General_options::Dir_list& rpath(parameters->options().rpath()); 5219 if (!rpath.empty()) 5220 { 5221 std::string rpath_val; 5222 for (General_options::Dir_list::const_iterator p = rpath.begin(); 5223 p != rpath.end(); 5224 ++p) 5225 { 5226 if (rpath_val.empty()) 5227 rpath_val = p->name(); 5228 else 5229 { 5230 // Eliminate duplicates. 5231 General_options::Dir_list::const_iterator q; 5232 for (q = rpath.begin(); q != p; ++q) 5233 if (q->name() == p->name()) 5234 break; 5235 if (q == p) 5236 { 5237 rpath_val += ':'; 5238 rpath_val += p->name(); 5239 } 5240 } 5241 } 5242 5243 if (!parameters->options().enable_new_dtags()) 5244 odyn->add_string(elfcpp::DT_RPATH, rpath_val); 5245 else 5246 odyn->add_string(elfcpp::DT_RUNPATH, rpath_val); 5247 } 5248 5249 // Look for text segments that have dynamic relocations. 5250 bool have_textrel = false; 5251 if (!this->script_options_->saw_sections_clause()) 5252 { 5253 for (Segment_list::const_iterator p = this->segment_list_.begin(); 5254 p != this->segment_list_.end(); 5255 ++p) 5256 { 5257 if ((*p)->type() == elfcpp::PT_LOAD 5258 && ((*p)->flags() & elfcpp::PF_W) == 0 5259 && (*p)->has_dynamic_reloc()) 5260 { 5261 have_textrel = true; 5262 break; 5263 } 5264 } 5265 } 5266 else 5267 { 5268 // We don't know the section -> segment mapping, so we are 5269 // conservative and just look for readonly sections with 5270 // relocations. If those sections wind up in writable segments, 5271 // then we have created an unnecessary DT_TEXTREL entry. 5272 for (Section_list::const_iterator p = this->section_list_.begin(); 5273 p != this->section_list_.end(); 5274 ++p) 5275 { 5276 if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0 5277 && ((*p)->flags() & elfcpp::SHF_WRITE) == 0 5278 && (*p)->has_dynamic_reloc()) 5279 { 5280 have_textrel = true; 5281 break; 5282 } 5283 } 5284 } 5285 5286 if (parameters->options().filter() != NULL) 5287 odyn->add_string(elfcpp::DT_FILTER, parameters->options().filter()); 5288 if (parameters->options().any_auxiliary()) 5289 { 5290 for (options::String_set::const_iterator p = 5291 parameters->options().auxiliary_begin(); 5292 p != parameters->options().auxiliary_end(); 5293 ++p) 5294 odyn->add_string(elfcpp::DT_AUXILIARY, *p); 5295 } 5296 5297 // Add a DT_FLAGS entry if necessary. 5298 unsigned int flags = 0; 5299 if (have_textrel) 5300 { 5301 // Add a DT_TEXTREL for compatibility with older loaders. 5302 odyn->add_constant(elfcpp::DT_TEXTREL, 0); 5303 flags |= elfcpp::DF_TEXTREL; 5304 5305 if (parameters->options().text()) 5306 gold_error(_("read-only segment has dynamic relocations")); 5307 else if (parameters->options().warn_shared_textrel() 5308 && parameters->options().shared()) 5309 gold_warning(_("shared library text segment is not shareable")); 5310 } 5311 if (parameters->options().shared() && this->has_static_tls()) 5312 flags |= elfcpp::DF_STATIC_TLS; 5313 if (parameters->options().origin()) 5314 flags |= elfcpp::DF_ORIGIN; 5315 if (parameters->options().Bsymbolic() 5316 && !parameters->options().have_dynamic_list()) 5317 { 5318 flags |= elfcpp::DF_SYMBOLIC; 5319 // Add DT_SYMBOLIC for compatibility with older loaders. 5320 odyn->add_constant(elfcpp::DT_SYMBOLIC, 0); 5321 } 5322 if (parameters->options().now()) 5323 flags |= elfcpp::DF_BIND_NOW; 5324 if (flags != 0) 5325 odyn->add_constant(elfcpp::DT_FLAGS, flags); 5326 5327 flags = 0; 5328 if (parameters->options().global()) 5329 flags |= elfcpp::DF_1_GLOBAL; 5330 if (parameters->options().initfirst()) 5331 flags |= elfcpp::DF_1_INITFIRST; 5332 if (parameters->options().interpose()) 5333 flags |= elfcpp::DF_1_INTERPOSE; 5334 if (parameters->options().loadfltr()) 5335 flags |= elfcpp::DF_1_LOADFLTR; 5336 if (parameters->options().nodefaultlib()) 5337 flags |= elfcpp::DF_1_NODEFLIB; 5338 if (parameters->options().nodelete()) 5339 flags |= elfcpp::DF_1_NODELETE; 5340 if (parameters->options().nodlopen()) 5341 flags |= elfcpp::DF_1_NOOPEN; 5342 if (parameters->options().nodump()) 5343 flags |= elfcpp::DF_1_NODUMP; 5344 if (!parameters->options().shared()) 5345 flags &= ~(elfcpp::DF_1_INITFIRST 5346 | elfcpp::DF_1_NODELETE 5347 | elfcpp::DF_1_NOOPEN); 5348 if (parameters->options().origin()) 5349 flags |= elfcpp::DF_1_ORIGIN; 5350 if (parameters->options().now()) 5351 flags |= elfcpp::DF_1_NOW; 5352 if (parameters->options().Bgroup()) 5353 flags |= elfcpp::DF_1_GROUP; 5354 if (flags != 0) 5355 odyn->add_constant(elfcpp::DT_FLAGS_1, flags); 5356 } 5357 5358 // Set the size of the _DYNAMIC symbol table to be the size of the 5359 // dynamic data. 5360 5361 void 5362 Layout::set_dynamic_symbol_size(const Symbol_table* symtab) 5363 { 5364 Output_data_dynamic* const odyn = this->dynamic_data_; 5365 if (odyn == NULL) 5366 return; 5367 odyn->finalize_data_size(); 5368 if (this->dynamic_symbol_ == NULL) 5369 return; 5370 off_t data_size = odyn->data_size(); 5371 const int size = parameters->target().get_size(); 5372 if (size == 32) 5373 symtab->get_sized_symbol<32>(this->dynamic_symbol_)->set_symsize(data_size); 5374 else if (size == 64) 5375 symtab->get_sized_symbol<64>(this->dynamic_symbol_)->set_symsize(data_size); 5376 else 5377 gold_unreachable(); 5378 } 5379 5380 // The mapping of input section name prefixes to output section names. 5381 // In some cases one prefix is itself a prefix of another prefix; in 5382 // such a case the longer prefix must come first. These prefixes are 5383 // based on the GNU linker default ELF linker script. 5384 5385 #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 } 5386 #define MAPPING_INIT_EXACT(f, t) { f, 0, t, sizeof(t) - 1 } 5387 const Layout::Section_name_mapping Layout::section_name_mapping[] = 5388 { 5389 MAPPING_INIT(".text.", ".text"), 5390 MAPPING_INIT(".rodata.", ".rodata"), 5391 MAPPING_INIT(".data.rel.ro.local.", ".data.rel.ro.local"), 5392 MAPPING_INIT_EXACT(".data.rel.ro.local", ".data.rel.ro.local"), 5393 MAPPING_INIT(".data.rel.ro.", ".data.rel.ro"), 5394 MAPPING_INIT_EXACT(".data.rel.ro", ".data.rel.ro"), 5395 MAPPING_INIT(".data.", ".data"), 5396 MAPPING_INIT(".bss.", ".bss"), 5397 MAPPING_INIT(".tdata.", ".tdata"), 5398 MAPPING_INIT(".tbss.", ".tbss"), 5399 MAPPING_INIT(".init_array.", ".init_array"), 5400 MAPPING_INIT(".fini_array.", ".fini_array"), 5401 MAPPING_INIT(".sdata.", ".sdata"), 5402 MAPPING_INIT(".sbss.", ".sbss"), 5403 // FIXME: In the GNU linker, .sbss2 and .sdata2 are handled 5404 // differently depending on whether it is creating a shared library. 5405 MAPPING_INIT(".sdata2.", ".sdata"), 5406 MAPPING_INIT(".sbss2.", ".sbss"), 5407 MAPPING_INIT(".lrodata.", ".lrodata"), 5408 MAPPING_INIT(".ldata.", ".ldata"), 5409 MAPPING_INIT(".lbss.", ".lbss"), 5410 MAPPING_INIT(".gcc_except_table.", ".gcc_except_table"), 5411 MAPPING_INIT(".gnu.linkonce.d.rel.ro.local.", ".data.rel.ro.local"), 5412 MAPPING_INIT(".gnu.linkonce.d.rel.ro.", ".data.rel.ro"), 5413 MAPPING_INIT(".gnu.linkonce.t.", ".text"), 5414 MAPPING_INIT(".gnu.linkonce.r.", ".rodata"), 5415 MAPPING_INIT(".gnu.linkonce.d.", ".data"), 5416 MAPPING_INIT(".gnu.linkonce.b.", ".bss"), 5417 MAPPING_INIT(".gnu.linkonce.s.", ".sdata"), 5418 MAPPING_INIT(".gnu.linkonce.sb.", ".sbss"), 5419 MAPPING_INIT(".gnu.linkonce.s2.", ".sdata"), 5420 MAPPING_INIT(".gnu.linkonce.sb2.", ".sbss"), 5421 MAPPING_INIT(".gnu.linkonce.wi.", ".debug_info"), 5422 MAPPING_INIT(".gnu.linkonce.td.", ".tdata"), 5423 MAPPING_INIT(".gnu.linkonce.tb.", ".tbss"), 5424 MAPPING_INIT(".gnu.linkonce.lr.", ".lrodata"), 5425 MAPPING_INIT(".gnu.linkonce.l.", ".ldata"), 5426 MAPPING_INIT(".gnu.linkonce.lb.", ".lbss"), 5427 MAPPING_INIT(".ARM.extab", ".ARM.extab"), 5428 MAPPING_INIT(".gnu.linkonce.armextab.", ".ARM.extab"), 5429 MAPPING_INIT(".ARM.exidx", ".ARM.exidx"), 5430 MAPPING_INIT(".gnu.linkonce.armexidx.", ".ARM.exidx"), 5431 MAPPING_INIT(".gnu.build.attributes.", ".gnu.build.attributes"), 5432 }; 5433 5434 // Mapping for ".text" section prefixes with -z,keep-text-section-prefix. 5435 const Layout::Section_name_mapping Layout::text_section_name_mapping[] = 5436 { 5437 MAPPING_INIT(".text.hot.", ".text.hot"), 5438 MAPPING_INIT_EXACT(".text.hot", ".text.hot"), 5439 MAPPING_INIT(".text.unlikely.", ".text.unlikely"), 5440 MAPPING_INIT_EXACT(".text.unlikely", ".text.unlikely"), 5441 MAPPING_INIT(".text.startup.", ".text.startup"), 5442 MAPPING_INIT_EXACT(".text.startup", ".text.startup"), 5443 MAPPING_INIT(".text.exit.", ".text.exit"), 5444 MAPPING_INIT_EXACT(".text.exit", ".text.exit"), 5445 MAPPING_INIT(".text.", ".text"), 5446 }; 5447 #undef MAPPING_INIT 5448 #undef MAPPING_INIT_EXACT 5449 5450 const int Layout::section_name_mapping_count = 5451 (sizeof(Layout::section_name_mapping) 5452 / sizeof(Layout::section_name_mapping[0])); 5453 5454 const int Layout::text_section_name_mapping_count = 5455 (sizeof(Layout::text_section_name_mapping) 5456 / sizeof(Layout::text_section_name_mapping[0])); 5457 5458 // Find section name NAME in PSNM and return the mapped name if found 5459 // with the length set in PLEN. 5460 const char * 5461 Layout::match_section_name(const Layout::Section_name_mapping* psnm, 5462 const int count, 5463 const char* name, size_t* plen) 5464 { 5465 for (int i = 0; i < count; ++i, ++psnm) 5466 { 5467 if (psnm->fromlen > 0) 5468 { 5469 if (strncmp(name, psnm->from, psnm->fromlen) == 0) 5470 { 5471 *plen = psnm->tolen; 5472 return psnm->to; 5473 } 5474 } 5475 else 5476 { 5477 if (strcmp(name, psnm->from) == 0) 5478 { 5479 *plen = psnm->tolen; 5480 return psnm->to; 5481 } 5482 } 5483 } 5484 return NULL; 5485 } 5486 5487 // Choose the output section name to use given an input section name. 5488 // Set *PLEN to the length of the name. *PLEN is initialized to the 5489 // length of NAME. 5490 5491 const char* 5492 Layout::output_section_name(const Relobj* relobj, const char* name, 5493 size_t* plen) 5494 { 5495 // gcc 4.3 generates the following sorts of section names when it 5496 // needs a section name specific to a function: 5497 // .text.FN 5498 // .rodata.FN 5499 // .sdata2.FN 5500 // .data.FN 5501 // .data.rel.FN 5502 // .data.rel.local.FN 5503 // .data.rel.ro.FN 5504 // .data.rel.ro.local.FN 5505 // .sdata.FN 5506 // .bss.FN 5507 // .sbss.FN 5508 // .tdata.FN 5509 // .tbss.FN 5510 5511 // The GNU linker maps all of those to the part before the .FN, 5512 // except that .data.rel.local.FN is mapped to .data, and 5513 // .data.rel.ro.local.FN is mapped to .data.rel.ro. The sections 5514 // beginning with .data.rel.ro.local are grouped together. 5515 5516 // For an anonymous namespace, the string FN can contain a '.'. 5517 5518 // Also of interest: .rodata.strN.N, .rodata.cstN, both of which the 5519 // GNU linker maps to .rodata. 5520 5521 // The .data.rel.ro sections are used with -z relro. The sections 5522 // are recognized by name. We use the same names that the GNU 5523 // linker does for these sections. 5524 5525 // It is hard to handle this in a principled way, so we don't even 5526 // try. We use a table of mappings. If the input section name is 5527 // not found in the table, we simply use it as the output section 5528 // name. 5529 5530 if (parameters->options().keep_text_section_prefix() 5531 && is_prefix_of(".text", name)) 5532 { 5533 const char* match = match_section_name(text_section_name_mapping, 5534 text_section_name_mapping_count, 5535 name, plen); 5536 if (match != NULL) 5537 return match; 5538 } 5539 5540 const char* match = match_section_name(section_name_mapping, 5541 section_name_mapping_count, name, plen); 5542 if (match != NULL) 5543 return match; 5544 5545 // As an additional complication, .ctors sections are output in 5546 // either .ctors or .init_array sections, and .dtors sections are 5547 // output in either .dtors or .fini_array sections. 5548 if (is_prefix_of(".ctors.", name) || is_prefix_of(".dtors.", name)) 5549 { 5550 if (parameters->options().ctors_in_init_array()) 5551 { 5552 *plen = 11; 5553 return name[1] == 'c' ? ".init_array" : ".fini_array"; 5554 } 5555 else 5556 { 5557 *plen = 6; 5558 return name[1] == 'c' ? ".ctors" : ".dtors"; 5559 } 5560 } 5561 if (parameters->options().ctors_in_init_array() 5562 && (strcmp(name, ".ctors") == 0 || strcmp(name, ".dtors") == 0)) 5563 { 5564 // To make .init_array/.fini_array work with gcc we must exclude 5565 // .ctors and .dtors sections from the crtbegin and crtend 5566 // files. 5567 if (relobj == NULL 5568 || (!Layout::match_file_name(relobj, "crtbegin") 5569 && !Layout::match_file_name(relobj, "crtend"))) 5570 { 5571 *plen = 11; 5572 return name[1] == 'c' ? ".init_array" : ".fini_array"; 5573 } 5574 } 5575 5576 return name; 5577 } 5578 5579 // Return true if RELOBJ is an input file whose base name matches 5580 // FILE_NAME. The base name must have an extension of ".o", and must 5581 // be exactly FILE_NAME.o or FILE_NAME, one character, ".o". This is 5582 // to match crtbegin.o as well as crtbeginS.o without getting confused 5583 // by other possibilities. Overall matching the file name this way is 5584 // a dreadful hack, but the GNU linker does it in order to better 5585 // support gcc, and we need to be compatible. 5586 5587 bool 5588 Layout::match_file_name(const Relobj* relobj, const char* match) 5589 { 5590 const std::string& file_name(relobj->name()); 5591 const char* base_name = lbasename(file_name.c_str()); 5592 size_t match_len = strlen(match); 5593 if (strncmp(base_name, match, match_len) != 0) 5594 return false; 5595 size_t base_len = strlen(base_name); 5596 if (base_len != match_len + 2 && base_len != match_len + 3) 5597 return false; 5598 return memcmp(base_name + base_len - 2, ".o", 2) == 0; 5599 } 5600 5601 // Check if a comdat group or .gnu.linkonce section with the given 5602 // NAME is selected for the link. If there is already a section, 5603 // *KEPT_SECTION is set to point to the existing section and the 5604 // function returns false. Otherwise, OBJECT, SHNDX, IS_COMDAT, and 5605 // IS_GROUP_NAME are recorded for this NAME in the layout object, 5606 // *KEPT_SECTION is set to the internal copy and the function returns 5607 // true. 5608 5609 bool 5610 Layout::find_or_add_kept_section(const std::string& name, 5611 Relobj* object, 5612 unsigned int shndx, 5613 bool is_comdat, 5614 bool is_group_name, 5615 Kept_section** kept_section) 5616 { 5617 // It's normal to see a couple of entries here, for the x86 thunk 5618 // sections. If we see more than a few, we're linking a C++ 5619 // program, and we resize to get more space to minimize rehashing. 5620 if (this->signatures_.size() > 4 5621 && !this->resized_signatures_) 5622 { 5623 reserve_unordered_map(&this->signatures_, 5624 this->number_of_input_files_ * 64); 5625 this->resized_signatures_ = true; 5626 } 5627 5628 Kept_section candidate; 5629 std::pair<Signatures::iterator, bool> ins = 5630 this->signatures_.insert(std::make_pair(name, candidate)); 5631 5632 if (kept_section != NULL) 5633 *kept_section = &ins.first->second; 5634 if (ins.second) 5635 { 5636 // This is the first time we've seen this signature. 5637 ins.first->second.set_object(object); 5638 ins.first->second.set_shndx(shndx); 5639 if (is_comdat) 5640 ins.first->second.set_is_comdat(); 5641 if (is_group_name) 5642 ins.first->second.set_is_group_name(); 5643 return true; 5644 } 5645 5646 // We have already seen this signature. 5647 5648 if (ins.first->second.is_group_name()) 5649 { 5650 // We've already seen a real section group with this signature. 5651 // If the kept group is from a plugin object, and we're in the 5652 // replacement phase, accept the new one as a replacement. 5653 if (ins.first->second.object() == NULL 5654 && parameters->options().plugins()->in_replacement_phase()) 5655 { 5656 ins.first->second.set_object(object); 5657 ins.first->second.set_shndx(shndx); 5658 return true; 5659 } 5660 return false; 5661 } 5662 else if (is_group_name) 5663 { 5664 // This is a real section group, and we've already seen a 5665 // linkonce section with this signature. Record that we've seen 5666 // a section group, and don't include this section group. 5667 ins.first->second.set_is_group_name(); 5668 return false; 5669 } 5670 else 5671 { 5672 // We've already seen a linkonce section and this is a linkonce 5673 // section. These don't block each other--this may be the same 5674 // symbol name with different section types. 5675 return true; 5676 } 5677 } 5678 5679 // Store the allocated sections into the section list. 5680 5681 void 5682 Layout::get_allocated_sections(Section_list* section_list) const 5683 { 5684 for (Section_list::const_iterator p = this->section_list_.begin(); 5685 p != this->section_list_.end(); 5686 ++p) 5687 if (((*p)->flags() & elfcpp::SHF_ALLOC) != 0) 5688 section_list->push_back(*p); 5689 } 5690 5691 // Store the executable sections into the section list. 5692 5693 void 5694 Layout::get_executable_sections(Section_list* section_list) const 5695 { 5696 for (Section_list::const_iterator p = this->section_list_.begin(); 5697 p != this->section_list_.end(); 5698 ++p) 5699 if (((*p)->flags() & (elfcpp::SHF_ALLOC | elfcpp::SHF_EXECINSTR)) 5700 == (elfcpp::SHF_ALLOC | elfcpp::SHF_EXECINSTR)) 5701 section_list->push_back(*p); 5702 } 5703 5704 // Create an output segment. 5705 5706 Output_segment* 5707 Layout::make_output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags) 5708 { 5709 gold_assert(!parameters->options().relocatable()); 5710 Output_segment* oseg = new Output_segment(type, flags); 5711 this->segment_list_.push_back(oseg); 5712 5713 if (type == elfcpp::PT_TLS) 5714 this->tls_segment_ = oseg; 5715 else if (type == elfcpp::PT_GNU_RELRO) 5716 this->relro_segment_ = oseg; 5717 else if (type == elfcpp::PT_INTERP) 5718 this->interp_segment_ = oseg; 5719 5720 return oseg; 5721 } 5722 5723 // Return the file offset of the normal symbol table. 5724 5725 off_t 5726 Layout::symtab_section_offset() const 5727 { 5728 if (this->symtab_section_ != NULL) 5729 return this->symtab_section_->offset(); 5730 return 0; 5731 } 5732 5733 // Return the section index of the normal symbol table. It may have 5734 // been stripped by the -s/--strip-all option. 5735 5736 unsigned int 5737 Layout::symtab_section_shndx() const 5738 { 5739 if (this->symtab_section_ != NULL) 5740 return this->symtab_section_->out_shndx(); 5741 return 0; 5742 } 5743 5744 // Write out the Output_sections. Most won't have anything to write, 5745 // since most of the data will come from input sections which are 5746 // handled elsewhere. But some Output_sections do have Output_data. 5747 5748 void 5749 Layout::write_output_sections(Output_file* of) const 5750 { 5751 for (Section_list::const_iterator p = this->section_list_.begin(); 5752 p != this->section_list_.end(); 5753 ++p) 5754 { 5755 if (!(*p)->after_input_sections()) 5756 (*p)->write(of); 5757 } 5758 } 5759 5760 // Write out data not associated with a section or the symbol table. 5761 5762 void 5763 Layout::write_data(const Symbol_table* symtab, Output_file* of) const 5764 { 5765 if (!parameters->options().strip_all()) 5766 { 5767 const Output_section* symtab_section = this->symtab_section_; 5768 for (Section_list::const_iterator p = this->section_list_.begin(); 5769 p != this->section_list_.end(); 5770 ++p) 5771 { 5772 if ((*p)->needs_symtab_index()) 5773 { 5774 gold_assert(symtab_section != NULL); 5775 unsigned int index = (*p)->symtab_index(); 5776 gold_assert(index > 0 && index != -1U); 5777 off_t off = (symtab_section->offset() 5778 + index * symtab_section->entsize()); 5779 symtab->write_section_symbol(*p, this->symtab_xindex_, of, off); 5780 } 5781 } 5782 } 5783 5784 const Output_section* dynsym_section = this->dynsym_section_; 5785 for (Section_list::const_iterator p = this->section_list_.begin(); 5786 p != this->section_list_.end(); 5787 ++p) 5788 { 5789 if ((*p)->needs_dynsym_index()) 5790 { 5791 gold_assert(dynsym_section != NULL); 5792 unsigned int index = (*p)->dynsym_index(); 5793 gold_assert(index > 0 && index != -1U); 5794 off_t off = (dynsym_section->offset() 5795 + index * dynsym_section->entsize()); 5796 symtab->write_section_symbol(*p, this->dynsym_xindex_, of, off); 5797 } 5798 } 5799 5800 // Write out the Output_data which are not in an Output_section. 5801 for (Data_list::const_iterator p = this->special_output_list_.begin(); 5802 p != this->special_output_list_.end(); 5803 ++p) 5804 (*p)->write(of); 5805 5806 // Write out the Output_data which are not in an Output_section 5807 // and are regenerated in each iteration of relaxation. 5808 for (Data_list::const_iterator p = this->relax_output_list_.begin(); 5809 p != this->relax_output_list_.end(); 5810 ++p) 5811 (*p)->write(of); 5812 } 5813 5814 // Write out the Output_sections which can only be written after the 5815 // input sections are complete. 5816 5817 void 5818 Layout::write_sections_after_input_sections(Output_file* of) 5819 { 5820 // Determine the final section offsets, and thus the final output 5821 // file size. Note we finalize the .shstrab last, to allow the 5822 // after_input_section sections to modify their section-names before 5823 // writing. 5824 if (this->any_postprocessing_sections_) 5825 { 5826 off_t off = this->output_file_size_; 5827 off = this->set_section_offsets(off, POSTPROCESSING_SECTIONS_PASS); 5828 5829 // Now that we've finalized the names, we can finalize the shstrab. 5830 off = 5831 this->set_section_offsets(off, 5832 STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS); 5833 5834 if (off > this->output_file_size_) 5835 { 5836 of->resize(off); 5837 this->output_file_size_ = off; 5838 } 5839 } 5840 5841 for (Section_list::const_iterator p = this->section_list_.begin(); 5842 p != this->section_list_.end(); 5843 ++p) 5844 { 5845 if ((*p)->after_input_sections()) 5846 (*p)->write(of); 5847 } 5848 5849 this->section_headers_->write(of); 5850 } 5851 5852 // If a tree-style build ID was requested, the parallel part of that computation 5853 // is already done, and the final hash-of-hashes is computed here. For other 5854 // types of build IDs, all the work is done here. 5855 5856 void 5857 Layout::write_build_id(Output_file* of, unsigned char* array_of_hashes, 5858 size_t size_of_hashes) const 5859 { 5860 if (this->build_id_note_ == NULL) 5861 return; 5862 5863 unsigned char* ov = of->get_output_view(this->build_id_note_->offset(), 5864 this->build_id_note_->data_size()); 5865 5866 if (array_of_hashes == NULL) 5867 { 5868 const size_t output_file_size = this->output_file_size(); 5869 const unsigned char* iv = of->get_input_view(0, output_file_size); 5870 const char* style = parameters->options().build_id(); 5871 5872 // If we get here with style == "tree" then the output must be 5873 // too small for chunking, and we use SHA-1 in that case. 5874 if ((strcmp(style, "sha1") == 0) || (strcmp(style, "tree") == 0)) 5875 sha1_buffer(reinterpret_cast<const char*>(iv), output_file_size, ov); 5876 else if (strcmp(style, "md5") == 0) 5877 md5_buffer(reinterpret_cast<const char*>(iv), output_file_size, ov); 5878 else 5879 gold_unreachable(); 5880 5881 of->free_input_view(0, output_file_size, iv); 5882 } 5883 else 5884 { 5885 // Non-overlapping substrings of the output file have been hashed. 5886 // Compute SHA-1 hash of the hashes. 5887 sha1_buffer(reinterpret_cast<const char*>(array_of_hashes), 5888 size_of_hashes, ov); 5889 delete[] array_of_hashes; 5890 } 5891 5892 of->write_output_view(this->build_id_note_->offset(), 5893 this->build_id_note_->data_size(), 5894 ov); 5895 } 5896 5897 // Write out a binary file. This is called after the link is 5898 // complete. IN is the temporary output file we used to generate the 5899 // ELF code. We simply walk through the segments, read them from 5900 // their file offset in IN, and write them to their load address in 5901 // the output file. FIXME: with a bit more work, we could support 5902 // S-records and/or Intel hex format here. 5903 5904 void 5905 Layout::write_binary(Output_file* in) const 5906 { 5907 gold_assert(parameters->options().oformat_enum() 5908 == General_options::OBJECT_FORMAT_BINARY); 5909 5910 // Get the size of the binary file. 5911 uint64_t max_load_address = 0; 5912 for (Segment_list::const_iterator p = this->segment_list_.begin(); 5913 p != this->segment_list_.end(); 5914 ++p) 5915 { 5916 if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0) 5917 { 5918 uint64_t max_paddr = (*p)->paddr() + (*p)->filesz(); 5919 if (max_paddr > max_load_address) 5920 max_load_address = max_paddr; 5921 } 5922 } 5923 5924 Output_file out(parameters->options().output_file_name()); 5925 out.open(max_load_address); 5926 5927 for (Segment_list::const_iterator p = this->segment_list_.begin(); 5928 p != this->segment_list_.end(); 5929 ++p) 5930 { 5931 if ((*p)->type() == elfcpp::PT_LOAD && (*p)->filesz() > 0) 5932 { 5933 const unsigned char* vin = in->get_input_view((*p)->offset(), 5934 (*p)->filesz()); 5935 unsigned char* vout = out.get_output_view((*p)->paddr(), 5936 (*p)->filesz()); 5937 memcpy(vout, vin, (*p)->filesz()); 5938 out.write_output_view((*p)->paddr(), (*p)->filesz(), vout); 5939 in->free_input_view((*p)->offset(), (*p)->filesz(), vin); 5940 } 5941 } 5942 5943 out.close(); 5944 } 5945 5946 // Print the output sections to the map file. 5947 5948 void 5949 Layout::print_to_mapfile(Mapfile* mapfile) const 5950 { 5951 for (Segment_list::const_iterator p = this->segment_list_.begin(); 5952 p != this->segment_list_.end(); 5953 ++p) 5954 (*p)->print_sections_to_mapfile(mapfile); 5955 for (Section_list::const_iterator p = this->unattached_section_list_.begin(); 5956 p != this->unattached_section_list_.end(); 5957 ++p) 5958 (*p)->print_to_mapfile(mapfile); 5959 } 5960 5961 // Print statistical information to stderr. This is used for --stats. 5962 5963 void 5964 Layout::print_stats() const 5965 { 5966 this->namepool_.print_stats("section name pool"); 5967 this->sympool_.print_stats("output symbol name pool"); 5968 this->dynpool_.print_stats("dynamic name pool"); 5969 5970 for (Section_list::const_iterator p = this->section_list_.begin(); 5971 p != this->section_list_.end(); 5972 ++p) 5973 (*p)->print_merge_stats(); 5974 } 5975 5976 // Write_sections_task methods. 5977 5978 // We can always run this task. 5979 5980 Task_token* 5981 Write_sections_task::is_runnable() 5982 { 5983 return NULL; 5984 } 5985 5986 // We need to unlock both OUTPUT_SECTIONS_BLOCKER and FINAL_BLOCKER 5987 // when finished. 5988 5989 void 5990 Write_sections_task::locks(Task_locker* tl) 5991 { 5992 tl->add(this, this->output_sections_blocker_); 5993 if (this->input_sections_blocker_ != NULL) 5994 tl->add(this, this->input_sections_blocker_); 5995 tl->add(this, this->final_blocker_); 5996 } 5997 5998 // Run the task--write out the data. 5999 6000 void 6001 Write_sections_task::run(Workqueue*) 6002 { 6003 this->layout_->write_output_sections(this->of_); 6004 } 6005 6006 // Write_data_task methods. 6007 6008 // We can always run this task. 6009 6010 Task_token* 6011 Write_data_task::is_runnable() 6012 { 6013 return NULL; 6014 } 6015 6016 // We need to unlock FINAL_BLOCKER when finished. 6017 6018 void 6019 Write_data_task::locks(Task_locker* tl) 6020 { 6021 tl->add(this, this->final_blocker_); 6022 } 6023 6024 // Run the task--write out the data. 6025 6026 void 6027 Write_data_task::run(Workqueue*) 6028 { 6029 this->layout_->write_data(this->symtab_, this->of_); 6030 } 6031 6032 // Write_symbols_task methods. 6033 6034 // We can always run this task. 6035 6036 Task_token* 6037 Write_symbols_task::is_runnable() 6038 { 6039 return NULL; 6040 } 6041 6042 // We need to unlock FINAL_BLOCKER when finished. 6043 6044 void 6045 Write_symbols_task::locks(Task_locker* tl) 6046 { 6047 tl->add(this, this->final_blocker_); 6048 } 6049 6050 // Run the task--write out the symbols. 6051 6052 void 6053 Write_symbols_task::run(Workqueue*) 6054 { 6055 this->symtab_->write_globals(this->sympool_, this->dynpool_, 6056 this->layout_->symtab_xindex(), 6057 this->layout_->dynsym_xindex(), this->of_); 6058 } 6059 6060 // Write_after_input_sections_task methods. 6061 6062 // We can only run this task after the input sections have completed. 6063 6064 Task_token* 6065 Write_after_input_sections_task::is_runnable() 6066 { 6067 if (this->input_sections_blocker_->is_blocked()) 6068 return this->input_sections_blocker_; 6069 return NULL; 6070 } 6071 6072 // We need to unlock FINAL_BLOCKER when finished. 6073 6074 void 6075 Write_after_input_sections_task::locks(Task_locker* tl) 6076 { 6077 tl->add(this, this->final_blocker_); 6078 } 6079 6080 // Run the task. 6081 6082 void 6083 Write_after_input_sections_task::run(Workqueue*) 6084 { 6085 this->layout_->write_sections_after_input_sections(this->of_); 6086 } 6087 6088 // Build IDs can be computed as a "flat" sha1 or md5 of a string of bytes, 6089 // or as a "tree" where each chunk of the string is hashed and then those 6090 // hashes are put into a (much smaller) string which is hashed with sha1. 6091 // We compute a checksum over the entire file because that is simplest. 6092 6093 void 6094 Build_id_task_runner::run(Workqueue* workqueue, const Task*) 6095 { 6096 Task_token* post_hash_tasks_blocker = new Task_token(true); 6097 const Layout* layout = this->layout_; 6098 Output_file* of = this->of_; 6099 const size_t filesize = (layout->output_file_size() <= 0 ? 0 6100 : static_cast<size_t>(layout->output_file_size())); 6101 unsigned char* array_of_hashes = NULL; 6102 size_t size_of_hashes = 0; 6103 6104 if (strcmp(this->options_->build_id(), "tree") == 0 6105 && this->options_->build_id_chunk_size_for_treehash() > 0 6106 && filesize > 0 6107 && (filesize >= this->options_->build_id_min_file_size_for_treehash())) 6108 { 6109 static const size_t MD5_OUTPUT_SIZE_IN_BYTES = 16; 6110 const size_t chunk_size = 6111 this->options_->build_id_chunk_size_for_treehash(); 6112 const size_t num_hashes = ((filesize - 1) / chunk_size) + 1; 6113 post_hash_tasks_blocker->add_blockers(num_hashes); 6114 size_of_hashes = num_hashes * MD5_OUTPUT_SIZE_IN_BYTES; 6115 array_of_hashes = new unsigned char[size_of_hashes]; 6116 unsigned char *dst = array_of_hashes; 6117 for (size_t i = 0, src_offset = 0; i < num_hashes; 6118 i++, dst += MD5_OUTPUT_SIZE_IN_BYTES, src_offset += chunk_size) 6119 { 6120 size_t size = std::min(chunk_size, filesize - src_offset); 6121 workqueue->queue(new Hash_task(of, 6122 src_offset, 6123 size, 6124 dst, 6125 post_hash_tasks_blocker)); 6126 } 6127 } 6128 6129 // Queue the final task to write the build id and close the output file. 6130 workqueue->queue(new Task_function(new Close_task_runner(this->options_, 6131 layout, 6132 of, 6133 array_of_hashes, 6134 size_of_hashes), 6135 post_hash_tasks_blocker, 6136 "Task_function Close_task_runner")); 6137 } 6138 6139 // Close_task_runner methods. 6140 6141 // Finish up the build ID computation, if necessary, and write a binary file, 6142 // if necessary. Then close the output file. 6143 6144 void 6145 Close_task_runner::run(Workqueue*, const Task*) 6146 { 6147 // At this point the multi-threaded part of the build ID computation, 6148 // if any, is done. See Build_id_task_runner. 6149 this->layout_->write_build_id(this->of_, this->array_of_hashes_, 6150 this->size_of_hashes_); 6151 6152 // If we've been asked to create a binary file, we do so here. 6153 if (this->options_->oformat_enum() != General_options::OBJECT_FORMAT_ELF) 6154 this->layout_->write_binary(this->of_); 6155 6156 this->of_->close(); 6157 } 6158 6159 // Instantiate the templates we need. We could use the configure 6160 // script to restrict this to only the ones for implemented targets. 6161 6162 #ifdef HAVE_TARGET_32_LITTLE 6163 template 6164 Output_section* 6165 Layout::init_fixed_output_section<32, false>( 6166 const char* name, 6167 elfcpp::Shdr<32, false>& shdr); 6168 #endif 6169 6170 #ifdef HAVE_TARGET_32_BIG 6171 template 6172 Output_section* 6173 Layout::init_fixed_output_section<32, true>( 6174 const char* name, 6175 elfcpp::Shdr<32, true>& shdr); 6176 #endif 6177 6178 #ifdef HAVE_TARGET_64_LITTLE 6179 template 6180 Output_section* 6181 Layout::init_fixed_output_section<64, false>( 6182 const char* name, 6183 elfcpp::Shdr<64, false>& shdr); 6184 #endif 6185 6186 #ifdef HAVE_TARGET_64_BIG 6187 template 6188 Output_section* 6189 Layout::init_fixed_output_section<64, true>( 6190 const char* name, 6191 elfcpp::Shdr<64, true>& shdr); 6192 #endif 6193 6194 #ifdef HAVE_TARGET_32_LITTLE 6195 template 6196 Output_section* 6197 Layout::layout<32, false>(Sized_relobj_file<32, false>* object, 6198 unsigned int shndx, 6199 const char* name, 6200 const elfcpp::Shdr<32, false>& shdr, 6201 unsigned int, unsigned int, unsigned int, off_t*); 6202 #endif 6203 6204 #ifdef HAVE_TARGET_32_BIG 6205 template 6206 Output_section* 6207 Layout::layout<32, true>(Sized_relobj_file<32, true>* object, 6208 unsigned int shndx, 6209 const char* name, 6210 const elfcpp::Shdr<32, true>& shdr, 6211 unsigned int, unsigned int, unsigned int, off_t*); 6212 #endif 6213 6214 #ifdef HAVE_TARGET_64_LITTLE 6215 template 6216 Output_section* 6217 Layout::layout<64, false>(Sized_relobj_file<64, false>* object, 6218 unsigned int shndx, 6219 const char* name, 6220 const elfcpp::Shdr<64, false>& shdr, 6221 unsigned int, unsigned int, unsigned int, off_t*); 6222 #endif 6223 6224 #ifdef HAVE_TARGET_64_BIG 6225 template 6226 Output_section* 6227 Layout::layout<64, true>(Sized_relobj_file<64, true>* object, 6228 unsigned int shndx, 6229 const char* name, 6230 const elfcpp::Shdr<64, true>& shdr, 6231 unsigned int, unsigned int, unsigned int, off_t*); 6232 #endif 6233 6234 #ifdef HAVE_TARGET_32_LITTLE 6235 template 6236 Output_section* 6237 Layout::layout_reloc<32, false>(Sized_relobj_file<32, false>* object, 6238 unsigned int reloc_shndx, 6239 const elfcpp::Shdr<32, false>& shdr, 6240 Output_section* data_section, 6241 Relocatable_relocs* rr); 6242 #endif 6243 6244 #ifdef HAVE_TARGET_32_BIG 6245 template 6246 Output_section* 6247 Layout::layout_reloc<32, true>(Sized_relobj_file<32, true>* object, 6248 unsigned int reloc_shndx, 6249 const elfcpp::Shdr<32, true>& shdr, 6250 Output_section* data_section, 6251 Relocatable_relocs* rr); 6252 #endif 6253 6254 #ifdef HAVE_TARGET_64_LITTLE 6255 template 6256 Output_section* 6257 Layout::layout_reloc<64, false>(Sized_relobj_file<64, false>* object, 6258 unsigned int reloc_shndx, 6259 const elfcpp::Shdr<64, false>& shdr, 6260 Output_section* data_section, 6261 Relocatable_relocs* rr); 6262 #endif 6263 6264 #ifdef HAVE_TARGET_64_BIG 6265 template 6266 Output_section* 6267 Layout::layout_reloc<64, true>(Sized_relobj_file<64, true>* object, 6268 unsigned int reloc_shndx, 6269 const elfcpp::Shdr<64, true>& shdr, 6270 Output_section* data_section, 6271 Relocatable_relocs* rr); 6272 #endif 6273 6274 #ifdef HAVE_TARGET_32_LITTLE 6275 template 6276 void 6277 Layout::layout_group<32, false>(Symbol_table* symtab, 6278 Sized_relobj_file<32, false>* object, 6279 unsigned int, 6280 const char* group_section_name, 6281 const char* signature, 6282 const elfcpp::Shdr<32, false>& shdr, 6283 elfcpp::Elf_Word flags, 6284 std::vector<unsigned int>* shndxes); 6285 #endif 6286 6287 #ifdef HAVE_TARGET_32_BIG 6288 template 6289 void 6290 Layout::layout_group<32, true>(Symbol_table* symtab, 6291 Sized_relobj_file<32, true>* object, 6292 unsigned int, 6293 const char* group_section_name, 6294 const char* signature, 6295 const elfcpp::Shdr<32, true>& shdr, 6296 elfcpp::Elf_Word flags, 6297 std::vector<unsigned int>* shndxes); 6298 #endif 6299 6300 #ifdef HAVE_TARGET_64_LITTLE 6301 template 6302 void 6303 Layout::layout_group<64, false>(Symbol_table* symtab, 6304 Sized_relobj_file<64, false>* object, 6305 unsigned int, 6306 const char* group_section_name, 6307 const char* signature, 6308 const elfcpp::Shdr<64, false>& shdr, 6309 elfcpp::Elf_Word flags, 6310 std::vector<unsigned int>* shndxes); 6311 #endif 6312 6313 #ifdef HAVE_TARGET_64_BIG 6314 template 6315 void 6316 Layout::layout_group<64, true>(Symbol_table* symtab, 6317 Sized_relobj_file<64, true>* object, 6318 unsigned int, 6319 const char* group_section_name, 6320 const char* signature, 6321 const elfcpp::Shdr<64, true>& shdr, 6322 elfcpp::Elf_Word flags, 6323 std::vector<unsigned int>* shndxes); 6324 #endif 6325 6326 #ifdef HAVE_TARGET_32_LITTLE 6327 template 6328 Output_section* 6329 Layout::layout_eh_frame<32, false>(Sized_relobj_file<32, false>* object, 6330 const unsigned char* symbols, 6331 off_t symbols_size, 6332 const unsigned char* symbol_names, 6333 off_t symbol_names_size, 6334 unsigned int shndx, 6335 const elfcpp::Shdr<32, false>& shdr, 6336 unsigned int reloc_shndx, 6337 unsigned int reloc_type, 6338 off_t* off); 6339 #endif 6340 6341 #ifdef HAVE_TARGET_32_BIG 6342 template 6343 Output_section* 6344 Layout::layout_eh_frame<32, true>(Sized_relobj_file<32, true>* object, 6345 const unsigned char* symbols, 6346 off_t symbols_size, 6347 const unsigned char* symbol_names, 6348 off_t symbol_names_size, 6349 unsigned int shndx, 6350 const elfcpp::Shdr<32, true>& shdr, 6351 unsigned int reloc_shndx, 6352 unsigned int reloc_type, 6353 off_t* off); 6354 #endif 6355 6356 #ifdef HAVE_TARGET_64_LITTLE 6357 template 6358 Output_section* 6359 Layout::layout_eh_frame<64, false>(Sized_relobj_file<64, false>* object, 6360 const unsigned char* symbols, 6361 off_t symbols_size, 6362 const unsigned char* symbol_names, 6363 off_t symbol_names_size, 6364 unsigned int shndx, 6365 const elfcpp::Shdr<64, false>& shdr, 6366 unsigned int reloc_shndx, 6367 unsigned int reloc_type, 6368 off_t* off); 6369 #endif 6370 6371 #ifdef HAVE_TARGET_64_BIG 6372 template 6373 Output_section* 6374 Layout::layout_eh_frame<64, true>(Sized_relobj_file<64, true>* object, 6375 const unsigned char* symbols, 6376 off_t symbols_size, 6377 const unsigned char* symbol_names, 6378 off_t symbol_names_size, 6379 unsigned int shndx, 6380 const elfcpp::Shdr<64, true>& shdr, 6381 unsigned int reloc_shndx, 6382 unsigned int reloc_type, 6383 off_t* off); 6384 #endif 6385 6386 #ifdef HAVE_TARGET_32_LITTLE 6387 template 6388 void 6389 Layout::add_to_gdb_index(bool is_type_unit, 6390 Sized_relobj<32, false>* object, 6391 const unsigned char* symbols, 6392 off_t symbols_size, 6393 unsigned int shndx, 6394 unsigned int reloc_shndx, 6395 unsigned int reloc_type); 6396 #endif 6397 6398 #ifdef HAVE_TARGET_32_BIG 6399 template 6400 void 6401 Layout::add_to_gdb_index(bool is_type_unit, 6402 Sized_relobj<32, true>* object, 6403 const unsigned char* symbols, 6404 off_t symbols_size, 6405 unsigned int shndx, 6406 unsigned int reloc_shndx, 6407 unsigned int reloc_type); 6408 #endif 6409 6410 #ifdef HAVE_TARGET_64_LITTLE 6411 template 6412 void 6413 Layout::add_to_gdb_index(bool is_type_unit, 6414 Sized_relobj<64, false>* object, 6415 const unsigned char* symbols, 6416 off_t symbols_size, 6417 unsigned int shndx, 6418 unsigned int reloc_shndx, 6419 unsigned int reloc_type); 6420 #endif 6421 6422 #ifdef HAVE_TARGET_64_BIG 6423 template 6424 void 6425 Layout::add_to_gdb_index(bool is_type_unit, 6426 Sized_relobj<64, true>* object, 6427 const unsigned char* symbols, 6428 off_t symbols_size, 6429 unsigned int shndx, 6430 unsigned int reloc_shndx, 6431 unsigned int reloc_type); 6432 #endif 6433 6434 } // End namespace gold. 6435