| 1 | // layout.h -- lay out output file sections for gold -*- C++ -*- |
| 2 | |
| 3 | // Copyright 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 |
| 4 | // Free Software Foundation, Inc. |
| 5 | // Written by Ian Lance Taylor <iant@google.com>. |
| 6 | |
| 7 | // This file is part of gold. |
| 8 | |
| 9 | // This program is free software; you can redistribute it and/or modify |
| 10 | // it under the terms of the GNU General Public License as published by |
| 11 | // the Free Software Foundation; either version 3 of the License, or |
| 12 | // (at your option) any later version. |
| 13 | |
| 14 | // This program is distributed in the hope that it will be useful, |
| 15 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 16 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 17 | // GNU General Public License for more details. |
| 18 | |
| 19 | // You should have received a copy of the GNU General Public License |
| 20 | // along with this program; if not, write to the Free Software |
| 21 | // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
| 22 | // MA 02110-1301, USA. |
| 23 | |
| 24 | #ifndef GOLD_LAYOUT_H |
| 25 | #define GOLD_LAYOUT_H |
| 26 | |
| 27 | #include <cstring> |
| 28 | #include <list> |
| 29 | #include <map> |
| 30 | #include <string> |
| 31 | #include <utility> |
| 32 | #include <vector> |
| 33 | |
| 34 | #include "script.h" |
| 35 | #include "workqueue.h" |
| 36 | #include "object.h" |
| 37 | #include "dynobj.h" |
| 38 | #include "stringpool.h" |
| 39 | |
| 40 | namespace gold |
| 41 | { |
| 42 | |
| 43 | class General_options; |
| 44 | class Incremental_inputs; |
| 45 | class Incremental_binary; |
| 46 | class Input_objects; |
| 47 | class Mapfile; |
| 48 | class Symbol_table; |
| 49 | class Output_section_data; |
| 50 | class Output_section; |
| 51 | class Output_section_headers; |
| 52 | class Output_segment_headers; |
| 53 | class Output_file_header; |
| 54 | class Output_segment; |
| 55 | class Output_data; |
| 56 | class Output_data_reloc_generic; |
| 57 | class Output_data_dynamic; |
| 58 | class Output_symtab_xindex; |
| 59 | class Output_reduced_debug_abbrev_section; |
| 60 | class Output_reduced_debug_info_section; |
| 61 | class Eh_frame; |
| 62 | class Gdb_index; |
| 63 | class Target; |
| 64 | struct Timespec; |
| 65 | |
| 66 | // Return TRUE if SECNAME is the name of a compressed debug section. |
| 67 | extern bool |
| 68 | is_compressed_debug_section(const char* secname); |
| 69 | |
| 70 | // Maintain a list of free space within a section, segment, or file. |
| 71 | // Used for incremental update links. |
| 72 | |
| 73 | class Free_list |
| 74 | { |
| 75 | public: |
| 76 | struct Free_list_node |
| 77 | { |
| 78 | Free_list_node(off_t start, off_t end) |
| 79 | : start_(start), end_(end) |
| 80 | { } |
| 81 | off_t start_; |
| 82 | off_t end_; |
| 83 | }; |
| 84 | typedef std::list<Free_list_node>::const_iterator Const_iterator; |
| 85 | |
| 86 | Free_list() |
| 87 | : list_(), last_remove_(list_.begin()), extend_(false), length_(0), |
| 88 | min_hole_(0) |
| 89 | { } |
| 90 | |
| 91 | // Initialize the free list for a section of length LEN. |
| 92 | // If EXTEND is true, free space may be allocated past the end. |
| 93 | void |
| 94 | init(off_t len, bool extend); |
| 95 | |
| 96 | // Set the minimum hole size that is allowed when allocating |
| 97 | // from the free list. |
| 98 | void |
| 99 | set_min_hole_size(off_t min_hole) |
| 100 | { this->min_hole_ = min_hole; } |
| 101 | |
| 102 | // Remove a chunk from the free list. |
| 103 | void |
| 104 | remove(off_t start, off_t end); |
| 105 | |
| 106 | // Allocate a chunk of space from the free list of length LEN, |
| 107 | // with alignment ALIGN, and minimum offset MINOFF. |
| 108 | off_t |
| 109 | allocate(off_t len, uint64_t align, off_t minoff); |
| 110 | |
| 111 | // Return an iterator for the beginning of the free list. |
| 112 | Const_iterator |
| 113 | begin() const |
| 114 | { return this->list_.begin(); } |
| 115 | |
| 116 | // Return an iterator for the end of the free list. |
| 117 | Const_iterator |
| 118 | end() const |
| 119 | { return this->list_.end(); } |
| 120 | |
| 121 | // Dump the free list (for debugging). |
| 122 | void |
| 123 | dump(); |
| 124 | |
| 125 | // Print usage statistics. |
| 126 | static void |
| 127 | print_stats(); |
| 128 | |
| 129 | private: |
| 130 | typedef std::list<Free_list_node>::iterator Iterator; |
| 131 | |
| 132 | // The free list. |
| 133 | std::list<Free_list_node> list_; |
| 134 | |
| 135 | // The last node visited during a remove operation. |
| 136 | Iterator last_remove_; |
| 137 | |
| 138 | // Whether we can extend past the original length. |
| 139 | bool extend_; |
| 140 | |
| 141 | // The total length of the section, segment, or file. |
| 142 | off_t length_; |
| 143 | |
| 144 | // The minimum hole size allowed. When allocating from the free list, |
| 145 | // we must not leave a hole smaller than this. |
| 146 | off_t min_hole_; |
| 147 | |
| 148 | // Statistics: |
| 149 | // The total number of free lists used. |
| 150 | static unsigned int num_lists; |
| 151 | // The total number of free list nodes used. |
| 152 | static unsigned int num_nodes; |
| 153 | // The total number of calls to Free_list::remove. |
| 154 | static unsigned int num_removes; |
| 155 | // The total number of nodes visited during calls to Free_list::remove. |
| 156 | static unsigned int num_remove_visits; |
| 157 | // The total number of calls to Free_list::allocate. |
| 158 | static unsigned int num_allocates; |
| 159 | // The total number of nodes visited during calls to Free_list::allocate. |
| 160 | static unsigned int num_allocate_visits; |
| 161 | }; |
| 162 | |
| 163 | // This task function handles mapping the input sections to output |
| 164 | // sections and laying them out in memory. |
| 165 | |
| 166 | class Layout_task_runner : public Task_function_runner |
| 167 | { |
| 168 | public: |
| 169 | // OPTIONS is the command line options, INPUT_OBJECTS is the list of |
| 170 | // input objects, SYMTAB is the symbol table, LAYOUT is the layout |
| 171 | // object. |
| 172 | Layout_task_runner(const General_options& options, |
| 173 | const Input_objects* input_objects, |
| 174 | Symbol_table* symtab, |
| 175 | Target* target, |
| 176 | Layout* layout, |
| 177 | Mapfile* mapfile) |
| 178 | : options_(options), input_objects_(input_objects), symtab_(symtab), |
| 179 | target_(target), layout_(layout), mapfile_(mapfile) |
| 180 | { } |
| 181 | |
| 182 | // Run the operation. |
| 183 | void |
| 184 | run(Workqueue*, const Task*); |
| 185 | |
| 186 | private: |
| 187 | Layout_task_runner(const Layout_task_runner&); |
| 188 | Layout_task_runner& operator=(const Layout_task_runner&); |
| 189 | |
| 190 | const General_options& options_; |
| 191 | const Input_objects* input_objects_; |
| 192 | Symbol_table* symtab_; |
| 193 | Target* target_; |
| 194 | Layout* layout_; |
| 195 | Mapfile* mapfile_; |
| 196 | }; |
| 197 | |
| 198 | // This class holds information about the comdat group or |
| 199 | // .gnu.linkonce section that will be kept for a given signature. |
| 200 | |
| 201 | class Kept_section |
| 202 | { |
| 203 | private: |
| 204 | // For a comdat group, we build a mapping from the name of each |
| 205 | // section in the group to the section index and the size in object. |
| 206 | // When we discard a group in some other object file, we use this |
| 207 | // map to figure out which kept section the discarded section is |
| 208 | // associated with. We then use that mapping when processing relocs |
| 209 | // against discarded sections. |
| 210 | struct Comdat_section_info |
| 211 | { |
| 212 | // The section index. |
| 213 | unsigned int shndx; |
| 214 | // The section size. |
| 215 | uint64_t size; |
| 216 | |
| 217 | Comdat_section_info(unsigned int a_shndx, uint64_t a_size) |
| 218 | : shndx(a_shndx), size(a_size) |
| 219 | { } |
| 220 | }; |
| 221 | |
| 222 | // Most comdat groups have only one or two sections, so we use a |
| 223 | // std::map rather than an Unordered_map to optimize for that case |
| 224 | // without paying too heavily for groups with more sections. |
| 225 | typedef std::map<std::string, Comdat_section_info> Comdat_group; |
| 226 | |
| 227 | public: |
| 228 | Kept_section() |
| 229 | : object_(NULL), shndx_(0), is_comdat_(false), is_group_name_(false) |
| 230 | { this->u_.linkonce_size = 0; } |
| 231 | |
| 232 | // We need to support copies for the signature map in the Layout |
| 233 | // object, but we should never copy an object after it has been |
| 234 | // marked as a comdat section. |
| 235 | Kept_section(const Kept_section& k) |
| 236 | : object_(k.object_), shndx_(k.shndx_), is_comdat_(false), |
| 237 | is_group_name_(k.is_group_name_) |
| 238 | { |
| 239 | gold_assert(!k.is_comdat_); |
| 240 | this->u_.linkonce_size = 0; |
| 241 | } |
| 242 | |
| 243 | ~Kept_section() |
| 244 | { |
| 245 | if (this->is_comdat_) |
| 246 | delete this->u_.group_sections; |
| 247 | } |
| 248 | |
| 249 | // The object where this section lives. |
| 250 | Relobj* |
| 251 | object() const |
| 252 | { return this->object_; } |
| 253 | |
| 254 | // Set the object. |
| 255 | void |
| 256 | set_object(Relobj* object) |
| 257 | { |
| 258 | gold_assert(this->object_ == NULL); |
| 259 | this->object_ = object; |
| 260 | } |
| 261 | |
| 262 | // The section index. |
| 263 | unsigned int |
| 264 | shndx() const |
| 265 | { return this->shndx_; } |
| 266 | |
| 267 | // Set the section index. |
| 268 | void |
| 269 | set_shndx(unsigned int shndx) |
| 270 | { |
| 271 | gold_assert(this->shndx_ == 0); |
| 272 | this->shndx_ = shndx; |
| 273 | } |
| 274 | |
| 275 | // Whether this is a comdat group. |
| 276 | bool |
| 277 | is_comdat() const |
| 278 | { return this->is_comdat_; } |
| 279 | |
| 280 | // Set that this is a comdat group. |
| 281 | void |
| 282 | set_is_comdat() |
| 283 | { |
| 284 | gold_assert(!this->is_comdat_); |
| 285 | this->is_comdat_ = true; |
| 286 | this->u_.group_sections = new Comdat_group(); |
| 287 | } |
| 288 | |
| 289 | // Whether this is associated with the name of a group or section |
| 290 | // rather than the symbol name derived from a linkonce section. |
| 291 | bool |
| 292 | is_group_name() const |
| 293 | { return this->is_group_name_; } |
| 294 | |
| 295 | // Note that this represents a comdat group rather than a single |
| 296 | // linkonce section. |
| 297 | void |
| 298 | set_is_group_name() |
| 299 | { this->is_group_name_ = true; } |
| 300 | |
| 301 | // Add a section to the group list. |
| 302 | void |
| 303 | add_comdat_section(const std::string& name, unsigned int shndx, |
| 304 | uint64_t size) |
| 305 | { |
| 306 | gold_assert(this->is_comdat_); |
| 307 | Comdat_section_info sinfo(shndx, size); |
| 308 | this->u_.group_sections->insert(std::make_pair(name, sinfo)); |
| 309 | } |
| 310 | |
| 311 | // Look for a section name in the group list, and return whether it |
| 312 | // was found. If found, returns the section index and size. |
| 313 | bool |
| 314 | find_comdat_section(const std::string& name, unsigned int* pshndx, |
| 315 | uint64_t* psize) const |
| 316 | { |
| 317 | gold_assert(this->is_comdat_); |
| 318 | Comdat_group::const_iterator p = this->u_.group_sections->find(name); |
| 319 | if (p == this->u_.group_sections->end()) |
| 320 | return false; |
| 321 | *pshndx = p->second.shndx; |
| 322 | *psize = p->second.size; |
| 323 | return true; |
| 324 | } |
| 325 | |
| 326 | // If there is only one section in the group list, return true, and |
| 327 | // return the section index and size. |
| 328 | bool |
| 329 | find_single_comdat_section(unsigned int* pshndx, uint64_t* psize) const |
| 330 | { |
| 331 | gold_assert(this->is_comdat_); |
| 332 | if (this->u_.group_sections->size() != 1) |
| 333 | return false; |
| 334 | Comdat_group::const_iterator p = this->u_.group_sections->begin(); |
| 335 | *pshndx = p->second.shndx; |
| 336 | *psize = p->second.size; |
| 337 | return true; |
| 338 | } |
| 339 | |
| 340 | // Return the size of a linkonce section. |
| 341 | uint64_t |
| 342 | linkonce_size() const |
| 343 | { |
| 344 | gold_assert(!this->is_comdat_); |
| 345 | return this->u_.linkonce_size; |
| 346 | } |
| 347 | |
| 348 | // Set the size of a linkonce section. |
| 349 | void |
| 350 | set_linkonce_size(uint64_t size) |
| 351 | { |
| 352 | gold_assert(!this->is_comdat_); |
| 353 | this->u_.linkonce_size = size; |
| 354 | } |
| 355 | |
| 356 | private: |
| 357 | // No assignment. |
| 358 | Kept_section& operator=(const Kept_section&); |
| 359 | |
| 360 | // The object containing the comdat group or .gnu.linkonce section. |
| 361 | Relobj* object_; |
| 362 | // Index of the group section for comdats and the section itself for |
| 363 | // .gnu.linkonce. |
| 364 | unsigned int shndx_; |
| 365 | // True if this is for a comdat group rather than a .gnu.linkonce |
| 366 | // section. |
| 367 | bool is_comdat_; |
| 368 | // The Kept_sections are values of a mapping, that maps names to |
| 369 | // them. This field is true if this struct is associated with the |
| 370 | // name of a comdat or .gnu.linkonce, false if it is associated with |
| 371 | // the name of a symbol obtained from the .gnu.linkonce.* name |
| 372 | // through some heuristics. |
| 373 | bool is_group_name_; |
| 374 | union |
| 375 | { |
| 376 | // If the is_comdat_ field is true, this holds a map from names of |
| 377 | // the sections in the group to section indexes in object_ and to |
| 378 | // section sizes. |
| 379 | Comdat_group* group_sections; |
| 380 | // If the is_comdat_ field is false, this holds the size of the |
| 381 | // single section. |
| 382 | uint64_t linkonce_size; |
| 383 | } u_; |
| 384 | }; |
| 385 | |
| 386 | // The ordering for output sections. This controls how output |
| 387 | // sections are ordered within a PT_LOAD output segment. |
| 388 | |
| 389 | enum Output_section_order |
| 390 | { |
| 391 | // Unspecified. Used for non-load segments. Also used for the file |
| 392 | // and segment headers. |
| 393 | ORDER_INVALID, |
| 394 | |
| 395 | // The PT_INTERP section should come first, so that the dynamic |
| 396 | // linker can pick it up quickly. |
| 397 | ORDER_INTERP, |
| 398 | |
| 399 | // Loadable read-only note sections come next so that the PT_NOTE |
| 400 | // segment is on the first page of the executable. |
| 401 | ORDER_RO_NOTE, |
| 402 | |
| 403 | // Put read-only sections used by the dynamic linker early in the |
| 404 | // executable to minimize paging. |
| 405 | ORDER_DYNAMIC_LINKER, |
| 406 | |
| 407 | // Put reloc sections used by the dynamic linker after other |
| 408 | // sections used by the dynamic linker; otherwise, objcopy and strip |
| 409 | // get confused. |
| 410 | ORDER_DYNAMIC_RELOCS, |
| 411 | |
| 412 | // Put the PLT reloc section after the other dynamic relocs; |
| 413 | // otherwise, prelink gets confused. |
| 414 | ORDER_DYNAMIC_PLT_RELOCS, |
| 415 | |
| 416 | // The .init section. |
| 417 | ORDER_INIT, |
| 418 | |
| 419 | // The PLT. |
| 420 | ORDER_PLT, |
| 421 | |
| 422 | // The regular text sections. |
| 423 | ORDER_TEXT, |
| 424 | |
| 425 | // The .fini section. |
| 426 | ORDER_FINI, |
| 427 | |
| 428 | // The read-only sections. |
| 429 | ORDER_READONLY, |
| 430 | |
| 431 | // The exception frame sections. |
| 432 | ORDER_EHFRAME, |
| 433 | |
| 434 | // The TLS sections come first in the data section. |
| 435 | ORDER_TLS_DATA, |
| 436 | ORDER_TLS_BSS, |
| 437 | |
| 438 | // Local RELRO (read-only after relocation) sections come before |
| 439 | // non-local RELRO sections. This data will be fully resolved by |
| 440 | // the prelinker. |
| 441 | ORDER_RELRO_LOCAL, |
| 442 | |
| 443 | // Non-local RELRO sections are grouped together after local RELRO |
| 444 | // sections. All RELRO sections must be adjacent so that they can |
| 445 | // all be put into a PT_GNU_RELRO segment. |
| 446 | ORDER_RELRO, |
| 447 | |
| 448 | // We permit marking exactly one output section as the last RELRO |
| 449 | // section. We do this so that the read-only GOT can be adjacent to |
| 450 | // the writable GOT. |
| 451 | ORDER_RELRO_LAST, |
| 452 | |
| 453 | // Similarly, we permit marking exactly one output section as the |
| 454 | // first non-RELRO section. |
| 455 | ORDER_NON_RELRO_FIRST, |
| 456 | |
| 457 | // The regular data sections come after the RELRO sections. |
| 458 | ORDER_DATA, |
| 459 | |
| 460 | // Large data sections normally go in large data segments. |
| 461 | ORDER_LARGE_DATA, |
| 462 | |
| 463 | // Group writable notes so that we can have a single PT_NOTE |
| 464 | // segment. |
| 465 | ORDER_RW_NOTE, |
| 466 | |
| 467 | // The small data sections must be at the end of the data sections, |
| 468 | // so that they can be adjacent to the small BSS sections. |
| 469 | ORDER_SMALL_DATA, |
| 470 | |
| 471 | // The BSS sections start here. |
| 472 | |
| 473 | // The small BSS sections must be at the start of the BSS sections, |
| 474 | // so that they can be adjacent to the small data sections. |
| 475 | ORDER_SMALL_BSS, |
| 476 | |
| 477 | // The regular BSS sections. |
| 478 | ORDER_BSS, |
| 479 | |
| 480 | // The large BSS sections come after the other BSS sections. |
| 481 | ORDER_LARGE_BSS, |
| 482 | |
| 483 | // Maximum value. |
| 484 | ORDER_MAX |
| 485 | }; |
| 486 | |
| 487 | // This class handles the details of laying out input sections. |
| 488 | |
| 489 | class Layout |
| 490 | { |
| 491 | public: |
| 492 | Layout(int number_of_input_files, Script_options*); |
| 493 | |
| 494 | ~Layout() |
| 495 | { |
| 496 | delete this->relaxation_debug_check_; |
| 497 | delete this->segment_states_; |
| 498 | } |
| 499 | |
| 500 | // For incremental links, record the base file to be modified. |
| 501 | void |
| 502 | set_incremental_base(Incremental_binary* base); |
| 503 | |
| 504 | Incremental_binary* |
| 505 | incremental_base() |
| 506 | { return this->incremental_base_; } |
| 507 | |
| 508 | // For incremental links, record the initial fixed layout of a section |
| 509 | // from the base file, and return a pointer to the Output_section. |
| 510 | template<int size, bool big_endian> |
| 511 | Output_section* |
| 512 | init_fixed_output_section(const char*, elfcpp::Shdr<size, big_endian>&); |
| 513 | |
| 514 | // Given an input section SHNDX, named NAME, with data in SHDR, from |
| 515 | // the object file OBJECT, return the output section where this |
| 516 | // input section should go. RELOC_SHNDX is the index of a |
| 517 | // relocation section which applies to this section, or 0 if none, |
| 518 | // or -1U if more than one. RELOC_TYPE is the type of the |
| 519 | // relocation section if there is one. Set *OFFSET to the offset |
| 520 | // within the output section. |
| 521 | template<int size, bool big_endian> |
| 522 | Output_section* |
| 523 | layout(Sized_relobj_file<size, big_endian> *object, unsigned int shndx, |
| 524 | const char* name, const elfcpp::Shdr<size, big_endian>& shdr, |
| 525 | unsigned int reloc_shndx, unsigned int reloc_type, off_t* offset); |
| 526 | |
| 527 | std::map<Section_id, unsigned int>* |
| 528 | get_section_order_map() |
| 529 | { return &this->section_order_map_; } |
| 530 | |
| 531 | // Struct to store segment info when mapping some input sections to |
| 532 | // unique segments using linker plugins. Mapping an input section to |
| 533 | // a unique segment is done by first placing such input sections in |
| 534 | // unique output sections and then mapping the output section to a |
| 535 | // unique segment. NAME is the name of the output section. FLAGS |
| 536 | // and ALIGN are the extra flags and alignment of the segment. |
| 537 | struct Unique_segment_info |
| 538 | { |
| 539 | // Identifier for the segment. ELF segments dont have names. This |
| 540 | // is used as the name of the output section mapped to the segment. |
| 541 | const char* name; |
| 542 | // Additional segment flags. |
| 543 | uint64_t flags; |
| 544 | // Segment alignment. |
| 545 | uint64_t align; |
| 546 | }; |
| 547 | |
| 548 | // Mapping from input section to segment. |
| 549 | typedef std::map<Const_section_id, Unique_segment_info*> |
| 550 | Section_segment_map; |
| 551 | |
| 552 | // Maps section SECN to SEGMENT s. |
| 553 | void |
| 554 | insert_section_segment_map(Const_section_id secn, Unique_segment_info *s); |
| 555 | |
| 556 | // Some input sections require special ordering, for compatibility |
| 557 | // with GNU ld. Given the name of an input section, return -1 if it |
| 558 | // does not require special ordering. Otherwise, return the index |
| 559 | // by which it should be ordered compared to other input sections |
| 560 | // that require special ordering. |
| 561 | static int |
| 562 | special_ordering_of_input_section(const char* name); |
| 563 | |
| 564 | bool |
| 565 | is_section_ordering_specified() |
| 566 | { return this->section_ordering_specified_; } |
| 567 | |
| 568 | void |
| 569 | set_section_ordering_specified() |
| 570 | { this->section_ordering_specified_ = true; } |
| 571 | |
| 572 | bool |
| 573 | is_unique_segment_for_sections_specified() const |
| 574 | { return this->unique_segment_for_sections_specified_; } |
| 575 | |
| 576 | void |
| 577 | set_unique_segment_for_sections_specified() |
| 578 | { this->unique_segment_for_sections_specified_ = true; } |
| 579 | |
| 580 | // For incremental updates, allocate a block of memory from the |
| 581 | // free list. Find a block starting at or after MINOFF. |
| 582 | off_t |
| 583 | allocate(off_t len, uint64_t align, off_t minoff) |
| 584 | { return this->free_list_.allocate(len, align, minoff); } |
| 585 | |
| 586 | unsigned int |
| 587 | find_section_order_index(const std::string&); |
| 588 | |
| 589 | // Read the sequence of input sections from the file specified with |
| 590 | // linker option --section-ordering-file. |
| 591 | void |
| 592 | read_layout_from_file(); |
| 593 | |
| 594 | // Layout an input reloc section when doing a relocatable link. The |
| 595 | // section is RELOC_SHNDX in OBJECT, with data in SHDR. |
| 596 | // DATA_SECTION is the reloc section to which it refers. RR is the |
| 597 | // relocatable information. |
| 598 | template<int size, bool big_endian> |
| 599 | Output_section* |
| 600 | layout_reloc(Sized_relobj_file<size, big_endian>* object, |
| 601 | unsigned int reloc_shndx, |
| 602 | const elfcpp::Shdr<size, big_endian>& shdr, |
| 603 | Output_section* data_section, |
| 604 | Relocatable_relocs* rr); |
| 605 | |
| 606 | // Layout a group section when doing a relocatable link. |
| 607 | template<int size, bool big_endian> |
| 608 | void |
| 609 | layout_group(Symbol_table* symtab, |
| 610 | Sized_relobj_file<size, big_endian>* object, |
| 611 | unsigned int group_shndx, |
| 612 | const char* group_section_name, |
| 613 | const char* signature, |
| 614 | const elfcpp::Shdr<size, big_endian>& shdr, |
| 615 | elfcpp::Elf_Word flags, |
| 616 | std::vector<unsigned int>* shndxes); |
| 617 | |
| 618 | // Like layout, only for exception frame sections. OBJECT is an |
| 619 | // object file. SYMBOLS is the contents of the symbol table |
| 620 | // section, with size SYMBOLS_SIZE. SYMBOL_NAMES is the contents of |
| 621 | // the symbol name section, with size SYMBOL_NAMES_SIZE. SHNDX is a |
| 622 | // .eh_frame section in OBJECT. SHDR is the section header. |
| 623 | // RELOC_SHNDX is the index of a relocation section which applies to |
| 624 | // this section, or 0 if none, or -1U if more than one. RELOC_TYPE |
| 625 | // is the type of the relocation section if there is one. This |
| 626 | // returns the output section, and sets *OFFSET to the offset. |
| 627 | template<int size, bool big_endian> |
| 628 | Output_section* |
| 629 | layout_eh_frame(Sized_relobj_file<size, big_endian>* object, |
| 630 | const unsigned char* symbols, |
| 631 | off_t symbols_size, |
| 632 | const unsigned char* symbol_names, |
| 633 | off_t symbol_names_size, |
| 634 | unsigned int shndx, |
| 635 | const elfcpp::Shdr<size, big_endian>& shdr, |
| 636 | unsigned int reloc_shndx, unsigned int reloc_type, |
| 637 | off_t* offset); |
| 638 | |
| 639 | // Add .eh_frame information for a PLT. The FDE must start with a |
| 640 | // 4-byte PC-relative reference to the start of the PLT, followed by |
| 641 | // a 4-byte size of PLT. |
| 642 | void |
| 643 | add_eh_frame_for_plt(Output_data* plt, const unsigned char* cie_data, |
| 644 | size_t cie_length, const unsigned char* fde_data, |
| 645 | size_t fde_length); |
| 646 | |
| 647 | // Scan a .debug_info or .debug_types section, and add summary |
| 648 | // information to the .gdb_index section. |
| 649 | template<int size, bool big_endian> |
| 650 | void |
| 651 | add_to_gdb_index(bool is_type_unit, |
| 652 | Sized_relobj<size, big_endian>* object, |
| 653 | const unsigned char* symbols, |
| 654 | off_t symbols_size, |
| 655 | unsigned int shndx, |
| 656 | unsigned int reloc_shndx, |
| 657 | unsigned int reloc_type); |
| 658 | |
| 659 | // Handle a GNU stack note. This is called once per input object |
| 660 | // file. SEEN_GNU_STACK is true if the object file has a |
| 661 | // .note.GNU-stack section. GNU_STACK_FLAGS is the section flags |
| 662 | // from that section if there was one. |
| 663 | void |
| 664 | layout_gnu_stack(bool seen_gnu_stack, uint64_t gnu_stack_flags, |
| 665 | const Object*); |
| 666 | |
| 667 | // Add an Output_section_data to the layout. This is used for |
| 668 | // special sections like the GOT section. ORDER is where the |
| 669 | // section should wind up in the output segment. IS_RELRO is true |
| 670 | // for relro sections. |
| 671 | Output_section* |
| 672 | add_output_section_data(const char* name, elfcpp::Elf_Word type, |
| 673 | elfcpp::Elf_Xword flags, |
| 674 | Output_section_data*, Output_section_order order, |
| 675 | bool is_relro); |
| 676 | |
| 677 | // Increase the size of the relro segment by this much. |
| 678 | void |
| 679 | increase_relro(unsigned int s) |
| 680 | { this->increase_relro_ += s; } |
| 681 | |
| 682 | // Create dynamic sections if necessary. |
| 683 | void |
| 684 | create_initial_dynamic_sections(Symbol_table*); |
| 685 | |
| 686 | // Define __start and __stop symbols for output sections. |
| 687 | void |
| 688 | define_section_symbols(Symbol_table*); |
| 689 | |
| 690 | // Create automatic note sections. |
| 691 | void |
| 692 | create_notes(); |
| 693 | |
| 694 | // Create sections for linker scripts. |
| 695 | void |
| 696 | create_script_sections() |
| 697 | { this->script_options_->create_script_sections(this); } |
| 698 | |
| 699 | // Define symbols from any linker script. |
| 700 | void |
| 701 | define_script_symbols(Symbol_table* symtab) |
| 702 | { this->script_options_->add_symbols_to_table(symtab); } |
| 703 | |
| 704 | // Define symbols for group signatures. |
| 705 | void |
| 706 | define_group_signatures(Symbol_table*); |
| 707 | |
| 708 | // Return the Stringpool used for symbol names. |
| 709 | const Stringpool* |
| 710 | sympool() const |
| 711 | { return &this->sympool_; } |
| 712 | |
| 713 | // Return the Stringpool used for dynamic symbol names and dynamic |
| 714 | // tags. |
| 715 | const Stringpool* |
| 716 | dynpool() const |
| 717 | { return &this->dynpool_; } |
| 718 | |
| 719 | // Return the .dynamic output section. This is only valid after the |
| 720 | // layout has been finalized. |
| 721 | Output_section* |
| 722 | dynamic_section() const |
| 723 | { return this->dynamic_section_; } |
| 724 | |
| 725 | // Return the symtab_xindex section used to hold large section |
| 726 | // indexes for the normal symbol table. |
| 727 | Output_symtab_xindex* |
| 728 | symtab_xindex() const |
| 729 | { return this->symtab_xindex_; } |
| 730 | |
| 731 | // Return the dynsym_xindex section used to hold large section |
| 732 | // indexes for the dynamic symbol table. |
| 733 | Output_symtab_xindex* |
| 734 | dynsym_xindex() const |
| 735 | { return this->dynsym_xindex_; } |
| 736 | |
| 737 | // Return whether a section is a .gnu.linkonce section, given the |
| 738 | // section name. |
| 739 | static inline bool |
| 740 | is_linkonce(const char* name) |
| 741 | { return strncmp(name, ".gnu.linkonce", sizeof(".gnu.linkonce") - 1) == 0; } |
| 742 | |
| 743 | // Whether we have added an input section. |
| 744 | bool |
| 745 | have_added_input_section() const |
| 746 | { return this->have_added_input_section_; } |
| 747 | |
| 748 | // Return true if a section is a debugging section. |
| 749 | static inline bool |
| 750 | is_debug_info_section(const char* name) |
| 751 | { |
| 752 | // Debugging sections can only be recognized by name. |
| 753 | return (strncmp(name, ".debug", sizeof(".debug") - 1) == 0 |
| 754 | || strncmp(name, ".zdebug", sizeof(".zdebug") - 1) == 0 |
| 755 | || strncmp(name, ".gnu.linkonce.wi.", |
| 756 | sizeof(".gnu.linkonce.wi.") - 1) == 0 |
| 757 | || strncmp(name, ".line", sizeof(".line") - 1) == 0 |
| 758 | || strncmp(name, ".stab", sizeof(".stab") - 1) == 0); |
| 759 | } |
| 760 | |
| 761 | // Return true if RELOBJ is an input file whose base name matches |
| 762 | // FILE_NAME. The base name must have an extension of ".o", and |
| 763 | // must be exactly FILE_NAME.o or FILE_NAME, one character, ".o". |
| 764 | static bool |
| 765 | match_file_name(const Relobj* relobj, const char* file_name); |
| 766 | |
| 767 | // Return whether section SHNDX in RELOBJ is a .ctors/.dtors section |
| 768 | // with more than one word being mapped to a .init_array/.fini_array |
| 769 | // section. |
| 770 | bool |
| 771 | is_ctors_in_init_array(Relobj* relobj, unsigned int shndx) const; |
| 772 | |
| 773 | // Check if a comdat group or .gnu.linkonce section with the given |
| 774 | // NAME is selected for the link. If there is already a section, |
| 775 | // *KEPT_SECTION is set to point to the signature and the function |
| 776 | // returns false. Otherwise, OBJECT, SHNDX,IS_COMDAT, and |
| 777 | // IS_GROUP_NAME are recorded for this NAME in the layout object, |
| 778 | // *KEPT_SECTION is set to the internal copy and the function return |
| 779 | // false. |
| 780 | bool |
| 781 | find_or_add_kept_section(const std::string& name, Relobj* object, |
| 782 | unsigned int shndx, bool is_comdat, |
| 783 | bool is_group_name, Kept_section** kept_section); |
| 784 | |
| 785 | // Finalize the layout after all the input sections have been added. |
| 786 | off_t |
| 787 | finalize(const Input_objects*, Symbol_table*, Target*, const Task*); |
| 788 | |
| 789 | // Return whether any sections require postprocessing. |
| 790 | bool |
| 791 | any_postprocessing_sections() const |
| 792 | { return this->any_postprocessing_sections_; } |
| 793 | |
| 794 | // Return the size of the output file. |
| 795 | off_t |
| 796 | output_file_size() const |
| 797 | { return this->output_file_size_; } |
| 798 | |
| 799 | // Return the TLS segment. This will return NULL if there isn't |
| 800 | // one. |
| 801 | Output_segment* |
| 802 | tls_segment() const |
| 803 | { return this->tls_segment_; } |
| 804 | |
| 805 | // Return the normal symbol table. |
| 806 | Output_section* |
| 807 | symtab_section() const |
| 808 | { |
| 809 | gold_assert(this->symtab_section_ != NULL); |
| 810 | return this->symtab_section_; |
| 811 | } |
| 812 | |
| 813 | // Return the file offset of the normal symbol table. |
| 814 | off_t |
| 815 | symtab_section_offset() const; |
| 816 | |
| 817 | // Return the section index of the normal symbol tabl.e |
| 818 | unsigned int |
| 819 | symtab_section_shndx() const; |
| 820 | |
| 821 | // Return the dynamic symbol table. |
| 822 | Output_section* |
| 823 | dynsym_section() const |
| 824 | { |
| 825 | gold_assert(this->dynsym_section_ != NULL); |
| 826 | return this->dynsym_section_; |
| 827 | } |
| 828 | |
| 829 | // Return the dynamic tags. |
| 830 | Output_data_dynamic* |
| 831 | dynamic_data() const |
| 832 | { return this->dynamic_data_; } |
| 833 | |
| 834 | // Write out the output sections. |
| 835 | void |
| 836 | write_output_sections(Output_file* of) const; |
| 837 | |
| 838 | // Write out data not associated with an input file or the symbol |
| 839 | // table. |
| 840 | void |
| 841 | write_data(const Symbol_table*, Output_file*) const; |
| 842 | |
| 843 | // Write out output sections which can not be written until all the |
| 844 | // input sections are complete. |
| 845 | void |
| 846 | write_sections_after_input_sections(Output_file* of); |
| 847 | |
| 848 | // Return an output section named NAME, or NULL if there is none. |
| 849 | Output_section* |
| 850 | find_output_section(const char* name) const; |
| 851 | |
| 852 | // Return an output segment of type TYPE, with segment flags SET set |
| 853 | // and segment flags CLEAR clear. Return NULL if there is none. |
| 854 | Output_segment* |
| 855 | find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set, |
| 856 | elfcpp::Elf_Word clear) const; |
| 857 | |
| 858 | // Return the number of segments we expect to produce. |
| 859 | size_t |
| 860 | expected_segment_count() const; |
| 861 | |
| 862 | // Set a flag to indicate that an object file uses the static TLS model. |
| 863 | void |
| 864 | set_has_static_tls() |
| 865 | { this->has_static_tls_ = true; } |
| 866 | |
| 867 | // Return true if any object file uses the static TLS model. |
| 868 | bool |
| 869 | has_static_tls() const |
| 870 | { return this->has_static_tls_; } |
| 871 | |
| 872 | // Return the options which may be set by a linker script. |
| 873 | Script_options* |
| 874 | script_options() |
| 875 | { return this->script_options_; } |
| 876 | |
| 877 | const Script_options* |
| 878 | script_options() const |
| 879 | { return this->script_options_; } |
| 880 | |
| 881 | // Return the object managing inputs in incremental build. NULL in |
| 882 | // non-incremental builds. |
| 883 | Incremental_inputs* |
| 884 | incremental_inputs() const |
| 885 | { return this->incremental_inputs_; } |
| 886 | |
| 887 | // For the target-specific code to add dynamic tags which are common |
| 888 | // to most targets. |
| 889 | void |
| 890 | add_target_dynamic_tags(bool use_rel, const Output_data* plt_got, |
| 891 | const Output_data* plt_rel, |
| 892 | const Output_data_reloc_generic* dyn_rel, |
| 893 | bool add_debug, bool dynrel_includes_plt); |
| 894 | |
| 895 | // If a treehash is necessary to compute the build ID, then queue |
| 896 | // the necessary tasks and return a blocker that will unblock when |
| 897 | // they finish. Otherwise return BUILD_ID_BLOCKER. |
| 898 | Task_token* |
| 899 | queue_build_id_tasks(Workqueue* workqueue, Task_token* build_id_blocker, |
| 900 | Output_file* of); |
| 901 | |
| 902 | // Compute and write out the build ID if needed. |
| 903 | void |
| 904 | write_build_id(Output_file*) const; |
| 905 | |
| 906 | // Rewrite output file in binary format. |
| 907 | void |
| 908 | write_binary(Output_file* in) const; |
| 909 | |
| 910 | // Print output sections to the map file. |
| 911 | void |
| 912 | print_to_mapfile(Mapfile*) const; |
| 913 | |
| 914 | // Dump statistical information to stderr. |
| 915 | void |
| 916 | print_stats() const; |
| 917 | |
| 918 | // A list of segments. |
| 919 | |
| 920 | typedef std::vector<Output_segment*> Segment_list; |
| 921 | |
| 922 | // A list of sections. |
| 923 | |
| 924 | typedef std::vector<Output_section*> Section_list; |
| 925 | |
| 926 | // The list of information to write out which is not attached to |
| 927 | // either a section or a segment. |
| 928 | typedef std::vector<Output_data*> Data_list; |
| 929 | |
| 930 | // Store the allocated sections into the section list. This is used |
| 931 | // by the linker script code. |
| 932 | void |
| 933 | get_allocated_sections(Section_list*) const; |
| 934 | |
| 935 | // Store the executable sections into the section list. |
| 936 | void |
| 937 | get_executable_sections(Section_list*) const; |
| 938 | |
| 939 | // Make a section for a linker script to hold data. |
| 940 | Output_section* |
| 941 | make_output_section_for_script(const char* name, |
| 942 | Script_sections::Section_type section_type); |
| 943 | |
| 944 | // Make a segment. This is used by the linker script code. |
| 945 | Output_segment* |
| 946 | make_output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags); |
| 947 | |
| 948 | // Return the number of segments. |
| 949 | size_t |
| 950 | segment_count() const |
| 951 | { return this->segment_list_.size(); } |
| 952 | |
| 953 | // Map from section flags to segment flags. |
| 954 | static elfcpp::Elf_Word |
| 955 | section_flags_to_segment(elfcpp::Elf_Xword flags); |
| 956 | |
| 957 | // Attach sections to segments. |
| 958 | void |
| 959 | attach_sections_to_segments(const Target*); |
| 960 | |
| 961 | // For relaxation clean up, we need to know output section data created |
| 962 | // from a linker script. |
| 963 | void |
| 964 | new_output_section_data_from_script(Output_section_data* posd) |
| 965 | { |
| 966 | if (this->record_output_section_data_from_script_) |
| 967 | this->script_output_section_data_list_.push_back(posd); |
| 968 | } |
| 969 | |
| 970 | // Return section list. |
| 971 | const Section_list& |
| 972 | section_list() const |
| 973 | { return this->section_list_; } |
| 974 | |
| 975 | // Returns TRUE iff NAME (an input section from RELOBJ) will |
| 976 | // be mapped to an output section that should be KEPT. |
| 977 | bool |
| 978 | keep_input_section(const Relobj*, const char*); |
| 979 | |
| 980 | // Add a special output object that will be recreated afresh |
| 981 | // if there is another relaxation iteration. |
| 982 | void |
| 983 | add_relax_output(Output_data* data) |
| 984 | { this->relax_output_list_.push_back(data); } |
| 985 | |
| 986 | // Clear out (and free) everything added by add_relax_output. |
| 987 | void |
| 988 | reset_relax_output(); |
| 989 | |
| 990 | private: |
| 991 | Layout(const Layout&); |
| 992 | Layout& operator=(const Layout&); |
| 993 | |
| 994 | // Mapping from input section names to output section names. |
| 995 | struct Section_name_mapping |
| 996 | { |
| 997 | const char* from; |
| 998 | int fromlen; |
| 999 | const char* to; |
| 1000 | int tolen; |
| 1001 | }; |
| 1002 | static const Section_name_mapping section_name_mapping[]; |
| 1003 | static const int section_name_mapping_count; |
| 1004 | |
| 1005 | // During a relocatable link, a list of group sections and |
| 1006 | // signatures. |
| 1007 | struct Group_signature |
| 1008 | { |
| 1009 | // The group section. |
| 1010 | Output_section* section; |
| 1011 | // The signature. |
| 1012 | const char* signature; |
| 1013 | |
| 1014 | Group_signature() |
| 1015 | : section(NULL), signature(NULL) |
| 1016 | { } |
| 1017 | |
| 1018 | Group_signature(Output_section* sectiona, const char* signaturea) |
| 1019 | : section(sectiona), signature(signaturea) |
| 1020 | { } |
| 1021 | }; |
| 1022 | typedef std::vector<Group_signature> Group_signatures; |
| 1023 | |
| 1024 | // Create a note section, filling in the header. |
| 1025 | Output_section* |
| 1026 | create_note(const char* name, int note_type, const char* section_name, |
| 1027 | size_t descsz, bool allocate, size_t* trailing_padding); |
| 1028 | |
| 1029 | // Create a note section for gold version. |
| 1030 | void |
| 1031 | create_gold_note(); |
| 1032 | |
| 1033 | // Record whether the stack must be executable. |
| 1034 | void |
| 1035 | create_executable_stack_info(); |
| 1036 | |
| 1037 | // Create a build ID note if needed. |
| 1038 | void |
| 1039 | create_build_id(); |
| 1040 | |
| 1041 | // Link .stab and .stabstr sections. |
| 1042 | void |
| 1043 | link_stabs_sections(); |
| 1044 | |
| 1045 | // Create .gnu_incremental_inputs and .gnu_incremental_strtab sections needed |
| 1046 | // for the next run of incremental linking to check what has changed. |
| 1047 | void |
| 1048 | create_incremental_info_sections(Symbol_table*); |
| 1049 | |
| 1050 | // Find the first read-only PT_LOAD segment, creating one if |
| 1051 | // necessary. |
| 1052 | Output_segment* |
| 1053 | find_first_load_seg(const Target*); |
| 1054 | |
| 1055 | // Count the local symbols in the regular symbol table and the dynamic |
| 1056 | // symbol table, and build the respective string pools. |
| 1057 | void |
| 1058 | count_local_symbols(const Task*, const Input_objects*); |
| 1059 | |
| 1060 | // Create the output sections for the symbol table. |
| 1061 | void |
| 1062 | create_symtab_sections(const Input_objects*, Symbol_table*, |
| 1063 | unsigned int, off_t*); |
| 1064 | |
| 1065 | // Create the .shstrtab section. |
| 1066 | Output_section* |
| 1067 | create_shstrtab(); |
| 1068 | |
| 1069 | // Create the section header table. |
| 1070 | void |
| 1071 | create_shdrs(const Output_section* shstrtab_section, off_t*); |
| 1072 | |
| 1073 | // Create the dynamic symbol table. |
| 1074 | void |
| 1075 | create_dynamic_symtab(const Input_objects*, Symbol_table*, |
| 1076 | Output_section** pdynstr, |
| 1077 | unsigned int* plocal_dynamic_count, |
| 1078 | std::vector<Symbol*>* pdynamic_symbols, |
| 1079 | Versions* versions); |
| 1080 | |
| 1081 | // Assign offsets to each local portion of the dynamic symbol table. |
| 1082 | void |
| 1083 | assign_local_dynsym_offsets(const Input_objects*); |
| 1084 | |
| 1085 | // Finish the .dynamic section and PT_DYNAMIC segment. |
| 1086 | void |
| 1087 | finish_dynamic_section(const Input_objects*, const Symbol_table*); |
| 1088 | |
| 1089 | // Set the size of the _DYNAMIC symbol. |
| 1090 | void |
| 1091 | set_dynamic_symbol_size(const Symbol_table*); |
| 1092 | |
| 1093 | // Create the .interp section and PT_INTERP segment. |
| 1094 | void |
| 1095 | create_interp(const Target* target); |
| 1096 | |
| 1097 | // Create the version sections. |
| 1098 | void |
| 1099 | create_version_sections(const Versions*, |
| 1100 | const Symbol_table*, |
| 1101 | unsigned int local_symcount, |
| 1102 | const std::vector<Symbol*>& dynamic_symbols, |
| 1103 | const Output_section* dynstr); |
| 1104 | |
| 1105 | template<int size, bool big_endian> |
| 1106 | void |
| 1107 | sized_create_version_sections(const Versions* versions, |
| 1108 | const Symbol_table*, |
| 1109 | unsigned int local_symcount, |
| 1110 | const std::vector<Symbol*>& dynamic_symbols, |
| 1111 | const Output_section* dynstr); |
| 1112 | |
| 1113 | // Return whether to include this section in the link. |
| 1114 | template<int size, bool big_endian> |
| 1115 | bool |
| 1116 | include_section(Sized_relobj_file<size, big_endian>* object, const char* name, |
| 1117 | const elfcpp::Shdr<size, big_endian>&); |
| 1118 | |
| 1119 | // Return the output section name to use given an input section |
| 1120 | // name. Set *PLEN to the length of the name. *PLEN must be |
| 1121 | // initialized to the length of NAME. |
| 1122 | static const char* |
| 1123 | output_section_name(const Relobj*, const char* name, size_t* plen); |
| 1124 | |
| 1125 | // Return the number of allocated output sections. |
| 1126 | size_t |
| 1127 | allocated_output_section_count() const; |
| 1128 | |
| 1129 | // Return the output section for NAME, TYPE and FLAGS. |
| 1130 | Output_section* |
| 1131 | get_output_section(const char* name, Stringpool::Key name_key, |
| 1132 | elfcpp::Elf_Word type, elfcpp::Elf_Xword flags, |
| 1133 | Output_section_order order, bool is_relro); |
| 1134 | |
| 1135 | // Clear the input section flags that should not be copied to the |
| 1136 | // output section. |
| 1137 | elfcpp::Elf_Xword |
| 1138 | get_output_section_flags (elfcpp::Elf_Xword input_section_flags); |
| 1139 | |
| 1140 | // Choose the output section for NAME in RELOBJ. |
| 1141 | Output_section* |
| 1142 | choose_output_section(const Relobj* relobj, const char* name, |
| 1143 | elfcpp::Elf_Word type, elfcpp::Elf_Xword flags, |
| 1144 | bool is_input_section, Output_section_order order, |
| 1145 | bool is_relro); |
| 1146 | |
| 1147 | // Create a new Output_section. |
| 1148 | Output_section* |
| 1149 | make_output_section(const char* name, elfcpp::Elf_Word type, |
| 1150 | elfcpp::Elf_Xword flags, Output_section_order order, |
| 1151 | bool is_relro); |
| 1152 | |
| 1153 | // Attach a section to a segment. |
| 1154 | void |
| 1155 | attach_section_to_segment(const Target*, Output_section*); |
| 1156 | |
| 1157 | // Get section order. |
| 1158 | Output_section_order |
| 1159 | default_section_order(Output_section*, bool is_relro_local); |
| 1160 | |
| 1161 | // Attach an allocated section to a segment. |
| 1162 | void |
| 1163 | attach_allocated_section_to_segment(const Target*, Output_section*); |
| 1164 | |
| 1165 | // Make the .eh_frame section. |
| 1166 | Output_section* |
| 1167 | make_eh_frame_section(const Relobj*); |
| 1168 | |
| 1169 | // Set the final file offsets of all the segments. |
| 1170 | off_t |
| 1171 | set_segment_offsets(const Target*, Output_segment*, unsigned int* pshndx); |
| 1172 | |
| 1173 | // Set the file offsets of the sections when doing a relocatable |
| 1174 | // link. |
| 1175 | off_t |
| 1176 | set_relocatable_section_offsets(Output_data*, unsigned int* pshndx); |
| 1177 | |
| 1178 | // Set the final file offsets of all the sections not associated |
| 1179 | // with a segment. We set section offsets in three passes: the |
| 1180 | // first handles all allocated sections, the second sections that |
| 1181 | // require postprocessing, and the last the late-bound STRTAB |
| 1182 | // sections (probably only shstrtab, which is the one we care about |
| 1183 | // because it holds section names). |
| 1184 | enum Section_offset_pass |
| 1185 | { |
| 1186 | BEFORE_INPUT_SECTIONS_PASS, |
| 1187 | POSTPROCESSING_SECTIONS_PASS, |
| 1188 | STRTAB_AFTER_POSTPROCESSING_SECTIONS_PASS |
| 1189 | }; |
| 1190 | off_t |
| 1191 | set_section_offsets(off_t, Section_offset_pass pass); |
| 1192 | |
| 1193 | // Set the final section indexes of all the sections not associated |
| 1194 | // with a segment. Returns the next unused index. |
| 1195 | unsigned int |
| 1196 | set_section_indexes(unsigned int pshndx); |
| 1197 | |
| 1198 | // Set the section addresses when using a script. |
| 1199 | Output_segment* |
| 1200 | set_section_addresses_from_script(Symbol_table*); |
| 1201 | |
| 1202 | // Find appropriate places or orphan sections in a script. |
| 1203 | void |
| 1204 | place_orphan_sections_in_script(); |
| 1205 | |
| 1206 | // Return whether SEG1 comes before SEG2 in the output file. |
| 1207 | bool |
| 1208 | segment_precedes(const Output_segment* seg1, const Output_segment* seg2); |
| 1209 | |
| 1210 | // Use to save and restore segments during relaxation. |
| 1211 | typedef Unordered_map<const Output_segment*, const Output_segment*> |
| 1212 | Segment_states; |
| 1213 | |
| 1214 | // Save states of current output segments. |
| 1215 | void |
| 1216 | save_segments(Segment_states*); |
| 1217 | |
| 1218 | // Restore output segment states. |
| 1219 | void |
| 1220 | restore_segments(const Segment_states*); |
| 1221 | |
| 1222 | // Clean up after relaxation so that it is possible to lay out the |
| 1223 | // sections and segments again. |
| 1224 | void |
| 1225 | clean_up_after_relaxation(); |
| 1226 | |
| 1227 | // Doing preparation work for relaxation. This is factored out to make |
| 1228 | // Layout::finalized a bit smaller and easier to read. |
| 1229 | void |
| 1230 | prepare_for_relaxation(); |
| 1231 | |
| 1232 | // Main body of the relaxation loop, which lays out the section. |
| 1233 | off_t |
| 1234 | relaxation_loop_body(int, Target*, Symbol_table*, Output_segment**, |
| 1235 | Output_segment*, Output_segment_headers*, |
| 1236 | Output_file_header*, unsigned int*); |
| 1237 | |
| 1238 | // A mapping used for kept comdats/.gnu.linkonce group signatures. |
| 1239 | typedef Unordered_map<std::string, Kept_section> Signatures; |
| 1240 | |
| 1241 | // Mapping from input section name/type/flags to output section. We |
| 1242 | // use canonicalized strings here. |
| 1243 | |
| 1244 | typedef std::pair<Stringpool::Key, |
| 1245 | std::pair<elfcpp::Elf_Word, elfcpp::Elf_Xword> > Key; |
| 1246 | |
| 1247 | struct Hash_key |
| 1248 | { |
| 1249 | size_t |
| 1250 | operator()(const Key& k) const; |
| 1251 | }; |
| 1252 | |
| 1253 | typedef Unordered_map<Key, Output_section*, Hash_key> Section_name_map; |
| 1254 | |
| 1255 | // A comparison class for segments. |
| 1256 | |
| 1257 | class Compare_segments |
| 1258 | { |
| 1259 | public: |
| 1260 | Compare_segments(Layout* layout) |
| 1261 | : layout_(layout) |
| 1262 | { } |
| 1263 | |
| 1264 | bool |
| 1265 | operator()(const Output_segment* seg1, const Output_segment* seg2) |
| 1266 | { return this->layout_->segment_precedes(seg1, seg2); } |
| 1267 | |
| 1268 | private: |
| 1269 | Layout* layout_; |
| 1270 | }; |
| 1271 | |
| 1272 | typedef std::vector<Output_section_data*> Output_section_data_list; |
| 1273 | |
| 1274 | // Debug checker class. |
| 1275 | class Relaxation_debug_check |
| 1276 | { |
| 1277 | public: |
| 1278 | Relaxation_debug_check() |
| 1279 | : section_infos_() |
| 1280 | { } |
| 1281 | |
| 1282 | // Check that sections and special data are in reset states. |
| 1283 | void |
| 1284 | check_output_data_for_reset_values(const Layout::Section_list&, |
| 1285 | const Layout::Data_list& special_outputs, |
| 1286 | const Layout::Data_list& relax_outputs); |
| 1287 | |
| 1288 | // Record information of a section list. |
| 1289 | void |
| 1290 | read_sections(const Layout::Section_list&); |
| 1291 | |
| 1292 | // Verify a section list with recorded information. |
| 1293 | void |
| 1294 | verify_sections(const Layout::Section_list&); |
| 1295 | |
| 1296 | private: |
| 1297 | // Information we care about a section. |
| 1298 | struct Section_info |
| 1299 | { |
| 1300 | // Output section described by this. |
| 1301 | Output_section* output_section; |
| 1302 | // Load address. |
| 1303 | uint64_t address; |
| 1304 | // Data size. |
| 1305 | off_t data_size; |
| 1306 | // File offset. |
| 1307 | off_t offset; |
| 1308 | }; |
| 1309 | |
| 1310 | // Section information. |
| 1311 | std::vector<Section_info> section_infos_; |
| 1312 | }; |
| 1313 | |
| 1314 | // The number of input files, for sizing tables. |
| 1315 | int number_of_input_files_; |
| 1316 | // Information set by scripts or by command line options. |
| 1317 | Script_options* script_options_; |
| 1318 | // The output section names. |
| 1319 | Stringpool namepool_; |
| 1320 | // The output symbol names. |
| 1321 | Stringpool sympool_; |
| 1322 | // The dynamic strings, if needed. |
| 1323 | Stringpool dynpool_; |
| 1324 | // The list of group sections and linkonce sections which we have seen. |
| 1325 | Signatures signatures_; |
| 1326 | // The mapping from input section name/type/flags to output sections. |
| 1327 | Section_name_map section_name_map_; |
| 1328 | // The list of output segments. |
| 1329 | Segment_list segment_list_; |
| 1330 | // The list of output sections. |
| 1331 | Section_list section_list_; |
| 1332 | // The list of output sections which are not attached to any output |
| 1333 | // segment. |
| 1334 | Section_list unattached_section_list_; |
| 1335 | // The list of unattached Output_data objects which require special |
| 1336 | // handling because they are not Output_sections. |
| 1337 | Data_list special_output_list_; |
| 1338 | // Like special_output_list_, but cleared and recreated on each |
| 1339 | // iteration of relaxation. |
| 1340 | Data_list relax_output_list_; |
| 1341 | // The section headers. |
| 1342 | Output_section_headers* section_headers_; |
| 1343 | // A pointer to the PT_TLS segment if there is one. |
| 1344 | Output_segment* tls_segment_; |
| 1345 | // A pointer to the PT_GNU_RELRO segment if there is one. |
| 1346 | Output_segment* relro_segment_; |
| 1347 | // A pointer to the PT_INTERP segment if there is one. |
| 1348 | Output_segment* interp_segment_; |
| 1349 | // A backend may increase the size of the PT_GNU_RELRO segment if |
| 1350 | // there is one. This is the amount to increase it by. |
| 1351 | unsigned int increase_relro_; |
| 1352 | // The SHT_SYMTAB output section. |
| 1353 | Output_section* symtab_section_; |
| 1354 | // The SHT_SYMTAB_SHNDX for the regular symbol table if there is one. |
| 1355 | Output_symtab_xindex* symtab_xindex_; |
| 1356 | // The SHT_DYNSYM output section if there is one. |
| 1357 | Output_section* dynsym_section_; |
| 1358 | // The SHT_SYMTAB_SHNDX for the dynamic symbol table if there is one. |
| 1359 | Output_symtab_xindex* dynsym_xindex_; |
| 1360 | // The SHT_DYNAMIC output section if there is one. |
| 1361 | Output_section* dynamic_section_; |
| 1362 | // The _DYNAMIC symbol if there is one. |
| 1363 | Symbol* dynamic_symbol_; |
| 1364 | // The dynamic data which goes into dynamic_section_. |
| 1365 | Output_data_dynamic* dynamic_data_; |
| 1366 | // The exception frame output section if there is one. |
| 1367 | Output_section* eh_frame_section_; |
| 1368 | // The exception frame data for eh_frame_section_. |
| 1369 | Eh_frame* eh_frame_data_; |
| 1370 | // Whether we have added eh_frame_data_ to the .eh_frame section. |
| 1371 | bool added_eh_frame_data_; |
| 1372 | // The exception frame header output section if there is one. |
| 1373 | Output_section* eh_frame_hdr_section_; |
| 1374 | // The data for the .gdb_index section. |
| 1375 | Gdb_index* gdb_index_data_; |
| 1376 | // The space for the build ID checksum if there is one. |
| 1377 | Output_section_data* build_id_note_; |
| 1378 | // Temporary storage for tree hash of build ID. |
| 1379 | unsigned char* array_of_hashes_; |
| 1380 | // Size of array_of_hashes_ (in bytes). |
| 1381 | size_t size_of_array_of_hashes_; |
| 1382 | // Input view for computing tree hash of build ID. Freed in write_build_id(). |
| 1383 | const unsigned char* input_view_; |
| 1384 | // The output section containing dwarf abbreviations |
| 1385 | Output_reduced_debug_abbrev_section* debug_abbrev_; |
| 1386 | // The output section containing the dwarf debug info tree |
| 1387 | Output_reduced_debug_info_section* debug_info_; |
| 1388 | // A list of group sections and their signatures. |
| 1389 | Group_signatures group_signatures_; |
| 1390 | // The size of the output file. |
| 1391 | off_t output_file_size_; |
| 1392 | // Whether we have added an input section to an output section. |
| 1393 | bool have_added_input_section_; |
| 1394 | // Whether we have attached the sections to the segments. |
| 1395 | bool sections_are_attached_; |
| 1396 | // Whether we have seen an object file marked to require an |
| 1397 | // executable stack. |
| 1398 | bool input_requires_executable_stack_; |
| 1399 | // Whether we have seen at least one object file with an executable |
| 1400 | // stack marker. |
| 1401 | bool input_with_gnu_stack_note_; |
| 1402 | // Whether we have seen at least one object file without an |
| 1403 | // executable stack marker. |
| 1404 | bool input_without_gnu_stack_note_; |
| 1405 | // Whether we have seen an object file that uses the static TLS model. |
| 1406 | bool has_static_tls_; |
| 1407 | // Whether any sections require postprocessing. |
| 1408 | bool any_postprocessing_sections_; |
| 1409 | // Whether we have resized the signatures_ hash table. |
| 1410 | bool resized_signatures_; |
| 1411 | // Whether we have created a .stab*str output section. |
| 1412 | bool have_stabstr_section_; |
| 1413 | // True if the input sections in the output sections should be sorted |
| 1414 | // as specified in a section ordering file. |
| 1415 | bool section_ordering_specified_; |
| 1416 | // True if some input sections need to be mapped to a unique segment, |
| 1417 | // after being mapped to a unique Output_section. |
| 1418 | bool unique_segment_for_sections_specified_; |
| 1419 | // In incremental build, holds information check the inputs and build the |
| 1420 | // .gnu_incremental_inputs section. |
| 1421 | Incremental_inputs* incremental_inputs_; |
| 1422 | // Whether we record output section data created in script |
| 1423 | bool record_output_section_data_from_script_; |
| 1424 | // List of output data that needs to be removed at relaxation clean up. |
| 1425 | Output_section_data_list script_output_section_data_list_; |
| 1426 | // Structure to save segment states before entering the relaxation loop. |
| 1427 | Segment_states* segment_states_; |
| 1428 | // A relaxation debug checker. We only create one when in debugging mode. |
| 1429 | Relaxation_debug_check* relaxation_debug_check_; |
| 1430 | // Plugins specify section_ordering using this map. This is set in |
| 1431 | // update_section_order in plugin.cc |
| 1432 | std::map<Section_id, unsigned int> section_order_map_; |
| 1433 | // This maps an input section to a unique segment. This is done by first |
| 1434 | // placing such input sections in unique output sections and then mapping |
| 1435 | // the output section to a unique segment. Unique_segment_info stores |
| 1436 | // any additional flags and alignment of the new segment. |
| 1437 | Section_segment_map section_segment_map_; |
| 1438 | // Hash a pattern to its position in the section ordering file. |
| 1439 | Unordered_map<std::string, unsigned int> input_section_position_; |
| 1440 | // Vector of glob only patterns in the section_ordering file. |
| 1441 | std::vector<std::string> input_section_glob_; |
| 1442 | // For incremental links, the base file to be modified. |
| 1443 | Incremental_binary* incremental_base_; |
| 1444 | // For incremental links, a list of free space within the file. |
| 1445 | Free_list free_list_; |
| 1446 | }; |
| 1447 | |
| 1448 | // This task handles writing out data in output sections which is not |
| 1449 | // part of an input section, or which requires special handling. When |
| 1450 | // this is done, it unblocks both output_sections_blocker and |
| 1451 | // final_blocker. |
| 1452 | |
| 1453 | class Write_sections_task : public Task |
| 1454 | { |
| 1455 | public: |
| 1456 | Write_sections_task(const Layout* layout, Output_file* of, |
| 1457 | Task_token* output_sections_blocker, |
| 1458 | Task_token* final_blocker) |
| 1459 | : layout_(layout), of_(of), |
| 1460 | output_sections_blocker_(output_sections_blocker), |
| 1461 | final_blocker_(final_blocker) |
| 1462 | { } |
| 1463 | |
| 1464 | // The standard Task methods. |
| 1465 | |
| 1466 | Task_token* |
| 1467 | is_runnable(); |
| 1468 | |
| 1469 | void |
| 1470 | locks(Task_locker*); |
| 1471 | |
| 1472 | void |
| 1473 | run(Workqueue*); |
| 1474 | |
| 1475 | std::string |
| 1476 | get_name() const |
| 1477 | { return "Write_sections_task"; } |
| 1478 | |
| 1479 | private: |
| 1480 | class Write_sections_locker; |
| 1481 | |
| 1482 | const Layout* layout_; |
| 1483 | Output_file* of_; |
| 1484 | Task_token* output_sections_blocker_; |
| 1485 | Task_token* final_blocker_; |
| 1486 | }; |
| 1487 | |
| 1488 | // This task handles writing out data which is not part of a section |
| 1489 | // or segment. |
| 1490 | |
| 1491 | class Write_data_task : public Task |
| 1492 | { |
| 1493 | public: |
| 1494 | Write_data_task(const Layout* layout, const Symbol_table* symtab, |
| 1495 | Output_file* of, Task_token* final_blocker) |
| 1496 | : layout_(layout), symtab_(symtab), of_(of), final_blocker_(final_blocker) |
| 1497 | { } |
| 1498 | |
| 1499 | // The standard Task methods. |
| 1500 | |
| 1501 | Task_token* |
| 1502 | is_runnable(); |
| 1503 | |
| 1504 | void |
| 1505 | locks(Task_locker*); |
| 1506 | |
| 1507 | void |
| 1508 | run(Workqueue*); |
| 1509 | |
| 1510 | std::string |
| 1511 | get_name() const |
| 1512 | { return "Write_data_task"; } |
| 1513 | |
| 1514 | private: |
| 1515 | const Layout* layout_; |
| 1516 | const Symbol_table* symtab_; |
| 1517 | Output_file* of_; |
| 1518 | Task_token* final_blocker_; |
| 1519 | }; |
| 1520 | |
| 1521 | // This task handles writing out the global symbols. |
| 1522 | |
| 1523 | class Write_symbols_task : public Task |
| 1524 | { |
| 1525 | public: |
| 1526 | Write_symbols_task(const Layout* layout, const Symbol_table* symtab, |
| 1527 | const Input_objects* /*input_objects*/, |
| 1528 | const Stringpool* sympool, const Stringpool* dynpool, |
| 1529 | Output_file* of, Task_token* final_blocker) |
| 1530 | : layout_(layout), symtab_(symtab), |
| 1531 | sympool_(sympool), dynpool_(dynpool), of_(of), |
| 1532 | final_blocker_(final_blocker) |
| 1533 | { } |
| 1534 | |
| 1535 | // The standard Task methods. |
| 1536 | |
| 1537 | Task_token* |
| 1538 | is_runnable(); |
| 1539 | |
| 1540 | void |
| 1541 | locks(Task_locker*); |
| 1542 | |
| 1543 | void |
| 1544 | run(Workqueue*); |
| 1545 | |
| 1546 | std::string |
| 1547 | get_name() const |
| 1548 | { return "Write_symbols_task"; } |
| 1549 | |
| 1550 | private: |
| 1551 | const Layout* layout_; |
| 1552 | const Symbol_table* symtab_; |
| 1553 | const Stringpool* sympool_; |
| 1554 | const Stringpool* dynpool_; |
| 1555 | Output_file* of_; |
| 1556 | Task_token* final_blocker_; |
| 1557 | }; |
| 1558 | |
| 1559 | // This task handles writing out data in output sections which can't |
| 1560 | // be written out until all the input sections have been handled. |
| 1561 | // This is for sections whose contents is based on the contents of |
| 1562 | // other output sections. |
| 1563 | |
| 1564 | class Write_after_input_sections_task : public Task |
| 1565 | { |
| 1566 | public: |
| 1567 | Write_after_input_sections_task(Layout* layout, Output_file* of, |
| 1568 | Task_token* input_sections_blocker, |
| 1569 | Task_token* final_blocker) |
| 1570 | : layout_(layout), of_(of), |
| 1571 | input_sections_blocker_(input_sections_blocker), |
| 1572 | final_blocker_(final_blocker) |
| 1573 | { } |
| 1574 | |
| 1575 | // The standard Task methods. |
| 1576 | |
| 1577 | Task_token* |
| 1578 | is_runnable(); |
| 1579 | |
| 1580 | void |
| 1581 | locks(Task_locker*); |
| 1582 | |
| 1583 | void |
| 1584 | run(Workqueue*); |
| 1585 | |
| 1586 | std::string |
| 1587 | get_name() const |
| 1588 | { return "Write_after_input_sections_task"; } |
| 1589 | |
| 1590 | private: |
| 1591 | Layout* layout_; |
| 1592 | Output_file* of_; |
| 1593 | Task_token* input_sections_blocker_; |
| 1594 | Task_token* final_blocker_; |
| 1595 | }; |
| 1596 | |
| 1597 | // This task function handles closing the file. |
| 1598 | |
| 1599 | class Close_task_runner : public Task_function_runner |
| 1600 | { |
| 1601 | public: |
| 1602 | Close_task_runner(const General_options* options, const Layout* layout, |
| 1603 | Output_file* of) |
| 1604 | : options_(options), layout_(layout), of_(of) |
| 1605 | { } |
| 1606 | |
| 1607 | // Run the operation. |
| 1608 | void |
| 1609 | run(Workqueue*, const Task*); |
| 1610 | |
| 1611 | private: |
| 1612 | const General_options* options_; |
| 1613 | const Layout* layout_; |
| 1614 | Output_file* of_; |
| 1615 | }; |
| 1616 | |
| 1617 | // A small helper function to align an address. |
| 1618 | |
| 1619 | inline uint64_t |
| 1620 | align_address(uint64_t address, uint64_t addralign) |
| 1621 | { |
| 1622 | if (addralign != 0) |
| 1623 | address = (address + addralign - 1) &~ (addralign - 1); |
| 1624 | return address; |
| 1625 | } |
| 1626 | |
| 1627 | } // End namespace gold. |
| 1628 | |
| 1629 | #endif // !defined(GOLD_LAYOUT_H) |