| 1 | // layout.h -- lay out output file sections for gold -*- C++ -*- |
| 2 | |
| 3 | // Copyright 2006, 2007, 2008, 2009 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 | #ifndef GOLD_LAYOUT_H |
| 24 | #define GOLD_LAYOUT_H |
| 25 | |
| 26 | #include <cstring> |
| 27 | #include <list> |
| 28 | #include <string> |
| 29 | #include <utility> |
| 30 | #include <vector> |
| 31 | |
| 32 | #include "script.h" |
| 33 | #include "workqueue.h" |
| 34 | #include "object.h" |
| 35 | #include "dynobj.h" |
| 36 | #include "stringpool.h" |
| 37 | |
| 38 | namespace gold |
| 39 | { |
| 40 | |
| 41 | class General_options; |
| 42 | class Incremental_inputs; |
| 43 | class Input_objects; |
| 44 | class Mapfile; |
| 45 | class Symbol_table; |
| 46 | class Output_section_data; |
| 47 | class Output_section; |
| 48 | class Output_section_headers; |
| 49 | class Output_segment; |
| 50 | class Output_data; |
| 51 | class Output_data_dynamic; |
| 52 | class Output_symtab_xindex; |
| 53 | class Output_reduced_debug_abbrev_section; |
| 54 | class Output_reduced_debug_info_section; |
| 55 | class Eh_frame; |
| 56 | class Target; |
| 57 | |
| 58 | // This task function handles mapping the input sections to output |
| 59 | // sections and laying them out in memory. |
| 60 | |
| 61 | class Layout_task_runner : public Task_function_runner |
| 62 | { |
| 63 | public: |
| 64 | // OPTIONS is the command line options, INPUT_OBJECTS is the list of |
| 65 | // input objects, SYMTAB is the symbol table, LAYOUT is the layout |
| 66 | // object. |
| 67 | Layout_task_runner(const General_options& options, |
| 68 | const Input_objects* input_objects, |
| 69 | Symbol_table* symtab, |
| 70 | Target* target, |
| 71 | Layout* layout, |
| 72 | Mapfile* mapfile) |
| 73 | : options_(options), input_objects_(input_objects), symtab_(symtab), |
| 74 | target_(target), layout_(layout), mapfile_(mapfile) |
| 75 | { } |
| 76 | |
| 77 | // Run the operation. |
| 78 | void |
| 79 | run(Workqueue*, const Task*); |
| 80 | |
| 81 | private: |
| 82 | Layout_task_runner(const Layout_task_runner&); |
| 83 | Layout_task_runner& operator=(const Layout_task_runner&); |
| 84 | |
| 85 | const General_options& options_; |
| 86 | const Input_objects* input_objects_; |
| 87 | Symbol_table* symtab_; |
| 88 | Target* target_; |
| 89 | Layout* layout_; |
| 90 | Mapfile* mapfile_; |
| 91 | }; |
| 92 | |
| 93 | // This struct holds information about the comdat or .gnu.linkonce |
| 94 | // that will be kept. |
| 95 | |
| 96 | struct Kept_section |
| 97 | { |
| 98 | Kept_section() |
| 99 | : object(NULL), shndx(0), is_group(false), group_sections(NULL) |
| 100 | { } |
| 101 | Kept_section(Relobj* a_object, unsigned int a_shndx, bool a_is_group) |
| 102 | : object(a_object), shndx(a_shndx), is_group(a_is_group), |
| 103 | group_sections(NULL) |
| 104 | { } |
| 105 | |
| 106 | typedef Unordered_map<std::string, unsigned int> Comdat_group; |
| 107 | |
| 108 | // The object containing the comdat or .gnu.linkonce. |
| 109 | Relobj* object; |
| 110 | // Index to the group section for comdats and the section itself for |
| 111 | // .gnu.linkonce. |
| 112 | unsigned int shndx; |
| 113 | // The Kept_sections are values of a mapping, that maps names to |
| 114 | // them. This field is true if this struct is associated with the |
| 115 | // name of a comdat or .gnu.linkonce, false if it is associated with |
| 116 | // the name of a symbol obtained from the .gnu.linkonce.* name |
| 117 | // through some heuristics. |
| 118 | bool is_group; |
| 119 | // For comdats, a map from names of the sections in the group to |
| 120 | // indexes in OBJECT_. NULL for .gnu.linkonce. |
| 121 | Comdat_group* group_sections; |
| 122 | }; |
| 123 | |
| 124 | // This class handles the details of laying out input sections. |
| 125 | |
| 126 | class Layout |
| 127 | { |
| 128 | public: |
| 129 | Layout(int number_of_input_files, Script_options*); |
| 130 | |
| 131 | // Given an input section SHNDX, named NAME, with data in SHDR, from |
| 132 | // the object file OBJECT, return the output section where this |
| 133 | // input section should go. RELOC_SHNDX is the index of a |
| 134 | // relocation section which applies to this section, or 0 if none, |
| 135 | // or -1U if more than one. RELOC_TYPE is the type of the |
| 136 | // relocation section if there is one. Set *OFFSET to the offset |
| 137 | // within the output section. |
| 138 | template<int size, bool big_endian> |
| 139 | Output_section* |
| 140 | layout(Sized_relobj<size, big_endian> *object, unsigned int shndx, |
| 141 | const char* name, const elfcpp::Shdr<size, big_endian>& shdr, |
| 142 | unsigned int reloc_shndx, unsigned int reloc_type, off_t* offset); |
| 143 | |
| 144 | // Layout an input reloc section when doing a relocatable link. The |
| 145 | // section is RELOC_SHNDX in OBJECT, with data in SHDR. |
| 146 | // DATA_SECTION is the reloc section to which it refers. RR is the |
| 147 | // relocatable information. |
| 148 | template<int size, bool big_endian> |
| 149 | Output_section* |
| 150 | layout_reloc(Sized_relobj<size, big_endian>* object, |
| 151 | unsigned int reloc_shndx, |
| 152 | const elfcpp::Shdr<size, big_endian>& shdr, |
| 153 | Output_section* data_section, |
| 154 | Relocatable_relocs* rr); |
| 155 | |
| 156 | // Layout a group section when doing a relocatable link. |
| 157 | template<int size, bool big_endian> |
| 158 | void |
| 159 | layout_group(Symbol_table* symtab, |
| 160 | Sized_relobj<size, big_endian>* object, |
| 161 | unsigned int group_shndx, |
| 162 | const char* group_section_name, |
| 163 | const char* signature, |
| 164 | const elfcpp::Shdr<size, big_endian>& shdr, |
| 165 | elfcpp::Elf_Word flags, |
| 166 | std::vector<unsigned int>* shndxes); |
| 167 | |
| 168 | // Like layout, only for exception frame sections. OBJECT is an |
| 169 | // object file. SYMBOLS is the contents of the symbol table |
| 170 | // section, with size SYMBOLS_SIZE. SYMBOL_NAMES is the contents of |
| 171 | // the symbol name section, with size SYMBOL_NAMES_SIZE. SHNDX is a |
| 172 | // .eh_frame section in OBJECT. SHDR is the section header. |
| 173 | // RELOC_SHNDX is the index of a relocation section which applies to |
| 174 | // this section, or 0 if none, or -1U if more than one. RELOC_TYPE |
| 175 | // is the type of the relocation section if there is one. This |
| 176 | // returns the output section, and sets *OFFSET to the offset. |
| 177 | template<int size, bool big_endian> |
| 178 | Output_section* |
| 179 | layout_eh_frame(Sized_relobj<size, big_endian>* object, |
| 180 | const unsigned char* symbols, |
| 181 | off_t symbols_size, |
| 182 | const unsigned char* symbol_names, |
| 183 | off_t symbol_names_size, |
| 184 | unsigned int shndx, |
| 185 | const elfcpp::Shdr<size, big_endian>& shdr, |
| 186 | unsigned int reloc_shndx, unsigned int reloc_type, |
| 187 | off_t* offset); |
| 188 | |
| 189 | // Handle a GNU stack note. This is called once per input object |
| 190 | // file. SEEN_GNU_STACK is true if the object file has a |
| 191 | // .note.GNU-stack section. GNU_STACK_FLAGS is the section flags |
| 192 | // from that section if there was one. |
| 193 | void |
| 194 | layout_gnu_stack(bool seen_gnu_stack, uint64_t gnu_stack_flags); |
| 195 | |
| 196 | // Add an Output_section_data to the layout. This is used for |
| 197 | // special sections like the GOT section. |
| 198 | Output_section* |
| 199 | add_output_section_data(const char* name, elfcpp::Elf_Word type, |
| 200 | elfcpp::Elf_Xword flags, |
| 201 | Output_section_data*); |
| 202 | |
| 203 | // Create dynamic sections if necessary. |
| 204 | void |
| 205 | create_initial_dynamic_sections(Symbol_table*); |
| 206 | |
| 207 | // Define __start and __stop symbols for output sections. |
| 208 | void |
| 209 | define_section_symbols(Symbol_table*); |
| 210 | |
| 211 | // Create sections for linker scripts. |
| 212 | void |
| 213 | create_script_sections() |
| 214 | { this->script_options_->create_script_sections(this); } |
| 215 | |
| 216 | // Define symbols from any linker script. |
| 217 | void |
| 218 | define_script_symbols(Symbol_table* symtab) |
| 219 | { this->script_options_->add_symbols_to_table(symtab); } |
| 220 | |
| 221 | // Define symbols for group signatures. |
| 222 | void |
| 223 | define_group_signatures(Symbol_table*); |
| 224 | |
| 225 | // Return the Stringpool used for symbol names. |
| 226 | const Stringpool* |
| 227 | sympool() const |
| 228 | { return &this->sympool_; } |
| 229 | |
| 230 | // Return the Stringpool used for dynamic symbol names and dynamic |
| 231 | // tags. |
| 232 | const Stringpool* |
| 233 | dynpool() const |
| 234 | { return &this->dynpool_; } |
| 235 | |
| 236 | // Return the symtab_xindex section used to hold large section |
| 237 | // indexes for the normal symbol table. |
| 238 | Output_symtab_xindex* |
| 239 | symtab_xindex() const |
| 240 | { return this->symtab_xindex_; } |
| 241 | |
| 242 | // Return the dynsym_xindex section used to hold large section |
| 243 | // indexes for the dynamic symbol table. |
| 244 | Output_symtab_xindex* |
| 245 | dynsym_xindex() const |
| 246 | { return this->dynsym_xindex_; } |
| 247 | |
| 248 | // Return whether a section is a .gnu.linkonce section, given the |
| 249 | // section name. |
| 250 | static inline bool |
| 251 | is_linkonce(const char* name) |
| 252 | { return strncmp(name, ".gnu.linkonce", sizeof(".gnu.linkonce") - 1) == 0; } |
| 253 | |
| 254 | // Return true if a section is a debugging section. |
| 255 | static inline bool |
| 256 | is_debug_info_section(const char* name) |
| 257 | { |
| 258 | // Debugging sections can only be recognized by name. |
| 259 | return (strncmp(name, ".debug", sizeof(".debug") - 1) == 0 |
| 260 | || strncmp(name, ".gnu.linkonce.wi.", |
| 261 | sizeof(".gnu.linkonce.wi.") - 1) == 0 |
| 262 | || strncmp(name, ".line", sizeof(".line") - 1) == 0 |
| 263 | || strncmp(name, ".stab", sizeof(".stab") - 1) == 0); |
| 264 | } |
| 265 | |
| 266 | // Check if a comdat group or .gnu.linkonce section with the given |
| 267 | // NAME is selected for the link. If there is already a section, |
| 268 | // *KEPT_SECTION is set to point to the signature and the function |
| 269 | // returns false. Otherwise, the CANDIDATE signature is recorded |
| 270 | // for this NAME in the layout object, *KEPT_SECTION is set to the |
| 271 | // internal copy and the function return false. In some cases, with |
| 272 | // CANDIDATE->GROUP_ being false, KEPT_SECTION can point back to |
| 273 | // CANDIDATE. |
| 274 | bool |
| 275 | find_or_add_kept_section(const std::string& name, |
| 276 | Kept_section* candidate, |
| 277 | Kept_section** kept_section); |
| 278 | |
| 279 | // Find the given comdat signature, and return the object and section |
| 280 | // index of the kept group. |
| 281 | Relobj* |
| 282 | find_kept_object(const std::string&, unsigned int*) const; |
| 283 | |
| 284 | // Finalize the layout after all the input sections have been added. |
| 285 | off_t |
| 286 | finalize(const Input_objects*, Symbol_table*, Target*, const Task*); |
| 287 | |
| 288 | // Return whether any sections require postprocessing. |
| 289 | bool |
| 290 | any_postprocessing_sections() const |
| 291 | { return this->any_postprocessing_sections_; } |
| 292 | |
| 293 | // Return the size of the output file. |
| 294 | off_t |
| 295 | output_file_size() const |
| 296 | { return this->output_file_size_; } |
| 297 | |
| 298 | // Return the TLS segment. This will return NULL if there isn't |
| 299 | // one. |
| 300 | Output_segment* |
| 301 | tls_segment() const |
| 302 | { return this->tls_segment_; } |
| 303 | |
| 304 | // Return the normal symbol table. |
| 305 | Output_section* |
| 306 | symtab_section() const |
| 307 | { |
| 308 | gold_assert(this->symtab_section_ != NULL); |
| 309 | return this->symtab_section_; |
| 310 | } |
| 311 | |
| 312 | // Return the dynamic symbol table. |
| 313 | Output_section* |
| 314 | dynsym_section() const |
| 315 | { |
| 316 | gold_assert(this->dynsym_section_ != NULL); |
| 317 | return this->dynsym_section_; |
| 318 | } |
| 319 | |
| 320 | // Return the dynamic tags. |
| 321 | Output_data_dynamic* |
| 322 | dynamic_data() const |
| 323 | { return this->dynamic_data_; } |
| 324 | |
| 325 | // Write out the output sections. |
| 326 | void |
| 327 | write_output_sections(Output_file* of) const; |
| 328 | |
| 329 | // Write out data not associated with an input file or the symbol |
| 330 | // table. |
| 331 | void |
| 332 | write_data(const Symbol_table*, Output_file*) const; |
| 333 | |
| 334 | // Write out output sections which can not be written until all the |
| 335 | // input sections are complete. |
| 336 | void |
| 337 | write_sections_after_input_sections(Output_file* of); |
| 338 | |
| 339 | // Return an output section named NAME, or NULL if there is none. |
| 340 | Output_section* |
| 341 | find_output_section(const char* name) const; |
| 342 | |
| 343 | // Return an output segment of type TYPE, with segment flags SET set |
| 344 | // and segment flags CLEAR clear. Return NULL if there is none. |
| 345 | Output_segment* |
| 346 | find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set, |
| 347 | elfcpp::Elf_Word clear) const; |
| 348 | |
| 349 | // Return the number of segments we expect to produce. |
| 350 | size_t |
| 351 | expected_segment_count() const; |
| 352 | |
| 353 | // Set a flag to indicate that an object file uses the static TLS model. |
| 354 | void |
| 355 | set_has_static_tls() |
| 356 | { this->has_static_tls_ = true; } |
| 357 | |
| 358 | // Return true if any object file uses the static TLS model. |
| 359 | bool |
| 360 | has_static_tls() const |
| 361 | { return this->has_static_tls_; } |
| 362 | |
| 363 | // Return the options which may be set by a linker script. |
| 364 | Script_options* |
| 365 | script_options() |
| 366 | { return this->script_options_; } |
| 367 | |
| 368 | const Script_options* |
| 369 | script_options() const |
| 370 | { return this->script_options_; } |
| 371 | |
| 372 | // Return the object managing inputs in incremental build. NULL in |
| 373 | // non-incremental builds. |
| 374 | Incremental_inputs* |
| 375 | incremental_inputs() |
| 376 | { return this->incremental_inputs_; } |
| 377 | |
| 378 | // Compute and write out the build ID if needed. |
| 379 | void |
| 380 | write_build_id(Output_file*) const; |
| 381 | |
| 382 | // Rewrite output file in binary format. |
| 383 | void |
| 384 | write_binary(Output_file* in) const; |
| 385 | |
| 386 | // Print output sections to the map file. |
| 387 | void |
| 388 | print_to_mapfile(Mapfile*) const; |
| 389 | |
| 390 | // Dump statistical information to stderr. |
| 391 | void |
| 392 | print_stats() const; |
| 393 | |
| 394 | // A list of segments. |
| 395 | |
| 396 | typedef std::vector<Output_segment*> Segment_list; |
| 397 | |
| 398 | // A list of sections. |
| 399 | |
| 400 | typedef std::vector<Output_section*> Section_list; |
| 401 | |
| 402 | // The list of information to write out which is not attached to |
| 403 | // either a section or a segment. |
| 404 | typedef std::vector<Output_data*> Data_list; |
| 405 | |
| 406 | // Store the allocated sections into the section list. This is used |
| 407 | // by the linker script code. |
| 408 | void |
| 409 | get_allocated_sections(Section_list*) const; |
| 410 | |
| 411 | // Make a section for a linker script to hold data. |
| 412 | Output_section* |
| 413 | make_output_section_for_script(const char* name); |
| 414 | |
| 415 | // Make a segment. This is used by the linker script code. |
| 416 | Output_segment* |
| 417 | make_output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags); |
| 418 | |
| 419 | // Return the number of segments. |
| 420 | size_t |
| 421 | segment_count() const |
| 422 | { return this->segment_list_.size(); } |
| 423 | |
| 424 | // Map from section flags to segment flags. |
| 425 | static elfcpp::Elf_Word |
| 426 | section_flags_to_segment(elfcpp::Elf_Xword flags); |
| 427 | |
| 428 | // Attach sections to segments. |
| 429 | void |
| 430 | attach_sections_to_segments(); |
| 431 | |
| 432 | private: |
| 433 | Layout(const Layout&); |
| 434 | Layout& operator=(const Layout&); |
| 435 | |
| 436 | // Mapping from .gnu.linkonce section names to output section names. |
| 437 | struct Linkonce_mapping |
| 438 | { |
| 439 | const char* from; |
| 440 | int fromlen; |
| 441 | const char* to; |
| 442 | int tolen; |
| 443 | }; |
| 444 | static const Linkonce_mapping linkonce_mapping[]; |
| 445 | static const int linkonce_mapping_count; |
| 446 | |
| 447 | // During a relocatable link, a list of group sections and |
| 448 | // signatures. |
| 449 | struct Group_signature |
| 450 | { |
| 451 | // The group section. |
| 452 | Output_section* section; |
| 453 | // The signature. |
| 454 | const char* signature; |
| 455 | |
| 456 | Group_signature() |
| 457 | : section(NULL), signature(NULL) |
| 458 | { } |
| 459 | |
| 460 | Group_signature(Output_section* sectiona, const char* signaturea) |
| 461 | : section(sectiona), signature(signaturea) |
| 462 | { } |
| 463 | }; |
| 464 | typedef std::vector<Group_signature> Group_signatures; |
| 465 | |
| 466 | // Create a note section, filling in the header. |
| 467 | Output_section* |
| 468 | create_note(const char* name, int note_type, const char *section_name, |
| 469 | size_t descsz, bool allocate, size_t* trailing_padding); |
| 470 | |
| 471 | // Create a note section for gold version. |
| 472 | void |
| 473 | create_gold_note(); |
| 474 | |
| 475 | // Record whether the stack must be executable. |
| 476 | void |
| 477 | create_executable_stack_info(const Target*); |
| 478 | |
| 479 | // Create a build ID note if needed. |
| 480 | void |
| 481 | create_build_id(); |
| 482 | |
| 483 | // Create .gnu_incremental_inputs and .gnu_incremental_strtab sections needed |
| 484 | // for the next run of incremental linking to check what has changed. |
| 485 | void |
| 486 | create_incremental_info_sections(); |
| 487 | |
| 488 | // Find the first read-only PT_LOAD segment, creating one if |
| 489 | // necessary. |
| 490 | Output_segment* |
| 491 | find_first_load_seg(); |
| 492 | |
| 493 | // Count the local symbols in the regular symbol table and the dynamic |
| 494 | // symbol table, and build the respective string pools. |
| 495 | void |
| 496 | count_local_symbols(const Task*, const Input_objects*); |
| 497 | |
| 498 | // Create the output sections for the symbol table. |
| 499 | void |
| 500 | create_symtab_sections(const Input_objects*, Symbol_table*, |
| 501 | unsigned int, off_t*); |
| 502 | |
| 503 | // Create the .shstrtab section. |
| 504 | Output_section* |
| 505 | create_shstrtab(); |
| 506 | |
| 507 | // Create the section header table. |
| 508 | void |
| 509 | create_shdrs(const Output_section* shstrtab_section, off_t*); |
| 510 | |
| 511 | // Create the dynamic symbol table. |
| 512 | void |
| 513 | create_dynamic_symtab(const Input_objects*, Symbol_table*, |
| 514 | Output_section** pdynstr, |
| 515 | unsigned int* plocal_dynamic_count, |
| 516 | std::vector<Symbol*>* pdynamic_symbols, |
| 517 | Versions* versions); |
| 518 | |
| 519 | // Assign offsets to each local portion of the dynamic symbol table. |
| 520 | void |
| 521 | assign_local_dynsym_offsets(const Input_objects*); |
| 522 | |
| 523 | // Finish the .dynamic section and PT_DYNAMIC segment. |
| 524 | void |
| 525 | finish_dynamic_section(const Input_objects*, const Symbol_table*); |
| 526 | |
| 527 | // Create the .interp section and PT_INTERP segment. |
| 528 | void |
| 529 | create_interp(const Target* target); |
| 530 | |
| 531 | // Create the version sections. |
| 532 | void |
| 533 | create_version_sections(const Versions*, |
| 534 | const Symbol_table*, |
| 535 | unsigned int local_symcount, |
| 536 | const std::vector<Symbol*>& dynamic_symbols, |
| 537 | const Output_section* dynstr); |
| 538 | |
| 539 | template<int size, bool big_endian> |
| 540 | void |
| 541 | sized_create_version_sections(const Versions* versions, |
| 542 | const Symbol_table*, |
| 543 | unsigned int local_symcount, |
| 544 | const std::vector<Symbol*>& dynamic_symbols, |
| 545 | const Output_section* dynstr); |
| 546 | |
| 547 | // Return whether to include this section in the link. |
| 548 | template<int size, bool big_endian> |
| 549 | bool |
| 550 | include_section(Sized_relobj<size, big_endian>* object, const char* name, |
| 551 | const elfcpp::Shdr<size, big_endian>&); |
| 552 | |
| 553 | // Return the output section name to use given an input section |
| 554 | // name. Set *PLEN to the length of the name. *PLEN must be |
| 555 | // initialized to the length of NAME. |
| 556 | static const char* |
| 557 | output_section_name(const char* name, size_t* plen); |
| 558 | |
| 559 | // Return the output section name to use for a linkonce section |
| 560 | // name. PLEN is as for output_section_name. |
| 561 | static const char* |
| 562 | linkonce_output_name(const char* name, size_t* plen); |
| 563 | |
| 564 | // Return the number of allocated output sections. |
| 565 | size_t |
| 566 | allocated_output_section_count() const; |
| 567 | |
| 568 | // Return the output section for NAME, TYPE and FLAGS. |
| 569 | Output_section* |
| 570 | get_output_section(const char* name, Stringpool::Key name_key, |
| 571 | elfcpp::Elf_Word type, elfcpp::Elf_Xword flags); |
| 572 | |
| 573 | // Choose the output section for NAME in RELOBJ. |
| 574 | Output_section* |
| 575 | choose_output_section(const Relobj* relobj, const char* name, |
| 576 | elfcpp::Elf_Word type, elfcpp::Elf_Xword flags, |
| 577 | bool is_input_section); |
| 578 | |
| 579 | // Create a new Output_section. |
| 580 | Output_section* |
| 581 | make_output_section(const char* name, elfcpp::Elf_Word type, |
| 582 | elfcpp::Elf_Xword flags); |
| 583 | |
| 584 | // Attach a section to a segment. |
| 585 | void |
| 586 | attach_section_to_segment(Output_section*); |
| 587 | |
| 588 | // Attach an allocated section to a segment. |
| 589 | void |
| 590 | attach_allocated_section_to_segment(Output_section*); |
| 591 | |
| 592 | // Set the final file offsets of all the segments. |
| 593 | off_t |
| 594 | set_segment_offsets(const Target*, Output_segment*, unsigned int* pshndx); |
| 595 | |
| 596 | // Set the file offsets of the sections when doing a relocatable |
| 597 | // link. |
| 598 | off_t |
| 599 | set_relocatable_section_offsets(Output_data*, unsigned int* pshndx); |
| 600 | |
| 601 | // Set the final file offsets of all the sections not associated |
| 602 | // with a segment. We set section offsets in three passes: the |
| 603 | // first handles all allocated sections, the second sections that |
| 604 | // require postprocessing, and the last the late-bound STRTAB |
| 605 | // sections (probably only shstrtab, which is the one we care about |
| 606 | // because it holds section names). |
| 607 | enum Section_offset_pass |
| 608 | { |
| 609 | BEFORE_INPUT_SECTIONS_PASS, |
| 610 | POSTPROCESSING_SECTIONS_PASS, |
| 611 | STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS |
| 612 | }; |
| 613 | off_t |
| 614 | set_section_offsets(off_t, Section_offset_pass pass); |
| 615 | |
| 616 | // Set the final section indexes of all the sections not associated |
| 617 | // with a segment. Returns the next unused index. |
| 618 | unsigned int |
| 619 | set_section_indexes(unsigned int pshndx); |
| 620 | |
| 621 | // Set the section addresses when using a script. |
| 622 | Output_segment* |
| 623 | set_section_addresses_from_script(Symbol_table*); |
| 624 | |
| 625 | // Return whether SEG1 comes before SEG2 in the output file. |
| 626 | static bool |
| 627 | segment_precedes(const Output_segment* seg1, const Output_segment* seg2); |
| 628 | |
| 629 | // A mapping used for kept comdats/.gnu.linkonce group signatures. |
| 630 | typedef Unordered_map<std::string, Kept_section> Signatures; |
| 631 | |
| 632 | // Mapping from input section name/type/flags to output section. We |
| 633 | // use canonicalized strings here. |
| 634 | |
| 635 | typedef std::pair<Stringpool::Key, |
| 636 | std::pair<elfcpp::Elf_Word, elfcpp::Elf_Xword> > Key; |
| 637 | |
| 638 | struct Hash_key |
| 639 | { |
| 640 | size_t |
| 641 | operator()(const Key& k) const; |
| 642 | }; |
| 643 | |
| 644 | typedef Unordered_map<Key, Output_section*, Hash_key> Section_name_map; |
| 645 | |
| 646 | // A comparison class for segments. |
| 647 | |
| 648 | struct Compare_segments |
| 649 | { |
| 650 | bool |
| 651 | operator()(const Output_segment* seg1, const Output_segment* seg2) |
| 652 | { return Layout::segment_precedes(seg1, seg2); } |
| 653 | }; |
| 654 | |
| 655 | // The number of input files, for sizing tables. |
| 656 | int number_of_input_files_; |
| 657 | // Information set by scripts or by command line options. |
| 658 | Script_options* script_options_; |
| 659 | // The output section names. |
| 660 | Stringpool namepool_; |
| 661 | // The output symbol names. |
| 662 | Stringpool sympool_; |
| 663 | // The dynamic strings, if needed. |
| 664 | Stringpool dynpool_; |
| 665 | // The list of group sections and linkonce sections which we have seen. |
| 666 | Signatures signatures_; |
| 667 | // The mapping from input section name/type/flags to output sections. |
| 668 | Section_name_map section_name_map_; |
| 669 | // The list of output segments. |
| 670 | Segment_list segment_list_; |
| 671 | // The list of output sections. |
| 672 | Section_list section_list_; |
| 673 | // The list of output sections which are not attached to any output |
| 674 | // segment. |
| 675 | Section_list unattached_section_list_; |
| 676 | // The list of unattached Output_data objects which require special |
| 677 | // handling because they are not Output_sections. |
| 678 | Data_list special_output_list_; |
| 679 | // The section headers. |
| 680 | Output_section_headers* section_headers_; |
| 681 | // A pointer to the PT_TLS segment if there is one. |
| 682 | Output_segment* tls_segment_; |
| 683 | // A pointer to the PT_GNU_RELRO segment if there is one. |
| 684 | Output_segment* relro_segment_; |
| 685 | // The SHT_SYMTAB output section. |
| 686 | Output_section* symtab_section_; |
| 687 | // The SHT_SYMTAB_SHNDX for the regular symbol table if there is one. |
| 688 | Output_symtab_xindex* symtab_xindex_; |
| 689 | // The SHT_DYNSYM output section if there is one. |
| 690 | Output_section* dynsym_section_; |
| 691 | // The SHT_SYMTAB_SHNDX for the dynamic symbol table if there is one. |
| 692 | Output_symtab_xindex* dynsym_xindex_; |
| 693 | // The SHT_DYNAMIC output section if there is one. |
| 694 | Output_section* dynamic_section_; |
| 695 | // The dynamic data which goes into dynamic_section_. |
| 696 | Output_data_dynamic* dynamic_data_; |
| 697 | // The exception frame output section if there is one. |
| 698 | Output_section* eh_frame_section_; |
| 699 | // The exception frame data for eh_frame_section_. |
| 700 | Eh_frame* eh_frame_data_; |
| 701 | // Whether we have added eh_frame_data_ to the .eh_frame section. |
| 702 | bool added_eh_frame_data_; |
| 703 | // The exception frame header output section if there is one. |
| 704 | Output_section* eh_frame_hdr_section_; |
| 705 | // The space for the build ID checksum if there is one. |
| 706 | Output_section_data* build_id_note_; |
| 707 | // The output section containing dwarf abbreviations |
| 708 | Output_reduced_debug_abbrev_section* debug_abbrev_; |
| 709 | // The output section containing the dwarf debug info tree |
| 710 | Output_reduced_debug_info_section* debug_info_; |
| 711 | // A list of group sections and their signatures. |
| 712 | Group_signatures group_signatures_; |
| 713 | // The size of the output file. |
| 714 | off_t output_file_size_; |
| 715 | // Whether we have attached the sections to the segments. |
| 716 | bool sections_are_attached_; |
| 717 | // Whether we have seen an object file marked to require an |
| 718 | // executable stack. |
| 719 | bool input_requires_executable_stack_; |
| 720 | // Whether we have seen at least one object file with an executable |
| 721 | // stack marker. |
| 722 | bool input_with_gnu_stack_note_; |
| 723 | // Whether we have seen at least one object file without an |
| 724 | // executable stack marker. |
| 725 | bool input_without_gnu_stack_note_; |
| 726 | // Whether we have seen an object file that uses the static TLS model. |
| 727 | bool has_static_tls_; |
| 728 | // Whether any sections require postprocessing. |
| 729 | bool any_postprocessing_sections_; |
| 730 | // Whether we have resized the signatures_ hash table. |
| 731 | bool resized_signatures_; |
| 732 | // In incremental build, holds information check the inputs and build the |
| 733 | // .gnu_incremental_inputs section. |
| 734 | Incremental_inputs* incremental_inputs_; |
| 735 | }; |
| 736 | |
| 737 | // This task handles writing out data in output sections which is not |
| 738 | // part of an input section, or which requires special handling. When |
| 739 | // this is done, it unblocks both output_sections_blocker and |
| 740 | // final_blocker. |
| 741 | |
| 742 | class Write_sections_task : public Task |
| 743 | { |
| 744 | public: |
| 745 | Write_sections_task(const Layout* layout, Output_file* of, |
| 746 | Task_token* output_sections_blocker, |
| 747 | Task_token* final_blocker) |
| 748 | : layout_(layout), of_(of), |
| 749 | output_sections_blocker_(output_sections_blocker), |
| 750 | final_blocker_(final_blocker) |
| 751 | { } |
| 752 | |
| 753 | // The standard Task methods. |
| 754 | |
| 755 | Task_token* |
| 756 | is_runnable(); |
| 757 | |
| 758 | void |
| 759 | locks(Task_locker*); |
| 760 | |
| 761 | void |
| 762 | run(Workqueue*); |
| 763 | |
| 764 | std::string |
| 765 | get_name() const |
| 766 | { return "Write_sections_task"; } |
| 767 | |
| 768 | private: |
| 769 | class Write_sections_locker; |
| 770 | |
| 771 | const Layout* layout_; |
| 772 | Output_file* of_; |
| 773 | Task_token* output_sections_blocker_; |
| 774 | Task_token* final_blocker_; |
| 775 | }; |
| 776 | |
| 777 | // This task handles writing out data which is not part of a section |
| 778 | // or segment. |
| 779 | |
| 780 | class Write_data_task : public Task |
| 781 | { |
| 782 | public: |
| 783 | Write_data_task(const Layout* layout, const Symbol_table* symtab, |
| 784 | Output_file* of, Task_token* final_blocker) |
| 785 | : layout_(layout), symtab_(symtab), of_(of), final_blocker_(final_blocker) |
| 786 | { } |
| 787 | |
| 788 | // The standard Task methods. |
| 789 | |
| 790 | Task_token* |
| 791 | is_runnable(); |
| 792 | |
| 793 | void |
| 794 | locks(Task_locker*); |
| 795 | |
| 796 | void |
| 797 | run(Workqueue*); |
| 798 | |
| 799 | std::string |
| 800 | get_name() const |
| 801 | { return "Write_data_task"; } |
| 802 | |
| 803 | private: |
| 804 | const Layout* layout_; |
| 805 | const Symbol_table* symtab_; |
| 806 | Output_file* of_; |
| 807 | Task_token* final_blocker_; |
| 808 | }; |
| 809 | |
| 810 | // This task handles writing out the global symbols. |
| 811 | |
| 812 | class Write_symbols_task : public Task |
| 813 | { |
| 814 | public: |
| 815 | Write_symbols_task(const Layout* layout, const Symbol_table* symtab, |
| 816 | const Input_objects* input_objects, |
| 817 | const Stringpool* sympool, const Stringpool* dynpool, |
| 818 | Output_file* of, Task_token* final_blocker) |
| 819 | : layout_(layout), symtab_(symtab), input_objects_(input_objects), |
| 820 | sympool_(sympool), dynpool_(dynpool), of_(of), |
| 821 | final_blocker_(final_blocker) |
| 822 | { } |
| 823 | |
| 824 | // The standard Task methods. |
| 825 | |
| 826 | Task_token* |
| 827 | is_runnable(); |
| 828 | |
| 829 | void |
| 830 | locks(Task_locker*); |
| 831 | |
| 832 | void |
| 833 | run(Workqueue*); |
| 834 | |
| 835 | std::string |
| 836 | get_name() const |
| 837 | { return "Write_symbols_task"; } |
| 838 | |
| 839 | private: |
| 840 | const Layout* layout_; |
| 841 | const Symbol_table* symtab_; |
| 842 | const Input_objects* input_objects_; |
| 843 | const Stringpool* sympool_; |
| 844 | const Stringpool* dynpool_; |
| 845 | Output_file* of_; |
| 846 | Task_token* final_blocker_; |
| 847 | }; |
| 848 | |
| 849 | // This task handles writing out data in output sections which can't |
| 850 | // be written out until all the input sections have been handled. |
| 851 | // This is for sections whose contents is based on the contents of |
| 852 | // other output sections. |
| 853 | |
| 854 | class Write_after_input_sections_task : public Task |
| 855 | { |
| 856 | public: |
| 857 | Write_after_input_sections_task(Layout* layout, Output_file* of, |
| 858 | Task_token* input_sections_blocker, |
| 859 | Task_token* final_blocker) |
| 860 | : layout_(layout), of_(of), |
| 861 | input_sections_blocker_(input_sections_blocker), |
| 862 | final_blocker_(final_blocker) |
| 863 | { } |
| 864 | |
| 865 | // The standard Task methods. |
| 866 | |
| 867 | Task_token* |
| 868 | is_runnable(); |
| 869 | |
| 870 | void |
| 871 | locks(Task_locker*); |
| 872 | |
| 873 | void |
| 874 | run(Workqueue*); |
| 875 | |
| 876 | std::string |
| 877 | get_name() const |
| 878 | { return "Write_after_input_sections_task"; } |
| 879 | |
| 880 | private: |
| 881 | Layout* layout_; |
| 882 | Output_file* of_; |
| 883 | Task_token* input_sections_blocker_; |
| 884 | Task_token* final_blocker_; |
| 885 | }; |
| 886 | |
| 887 | // This task function handles closing the file. |
| 888 | |
| 889 | class Close_task_runner : public Task_function_runner |
| 890 | { |
| 891 | public: |
| 892 | Close_task_runner(const General_options* options, const Layout* layout, |
| 893 | Output_file* of) |
| 894 | : options_(options), layout_(layout), of_(of) |
| 895 | { } |
| 896 | |
| 897 | // Run the operation. |
| 898 | void |
| 899 | run(Workqueue*, const Task*); |
| 900 | |
| 901 | private: |
| 902 | const General_options* options_; |
| 903 | const Layout* layout_; |
| 904 | Output_file* of_; |
| 905 | }; |
| 906 | |
| 907 | // A small helper function to align an address. |
| 908 | |
| 909 | inline uint64_t |
| 910 | align_address(uint64_t address, uint64_t addralign) |
| 911 | { |
| 912 | if (addralign != 0) |
| 913 | address = (address + addralign - 1) &~ (addralign - 1); |
| 914 | return address; |
| 915 | } |
| 916 | |
| 917 | } // End namespace gold. |
| 918 | |
| 919 | #endif // !defined(GOLD_LAYOUT_H) |