| 1 | // layout.cc -- lay out output file sections for gold |
| 2 | |
| 3 | // Copyright 2006, 2007 Free Software Foundation, Inc. |
| 4 | // Written by Ian Lance Taylor <iant@google.com>. |
| 5 | |
| 6 | // This file is part of gold. |
| 7 | |
| 8 | // This program is free software; you can redistribute it and/or modify |
| 9 | // it under the terms of the GNU General Public License as published by |
| 10 | // the Free Software Foundation; either version 3 of the License, or |
| 11 | // (at your option) any later version. |
| 12 | |
| 13 | // This program is distributed in the hope that it will be useful, |
| 14 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | // GNU General Public License for more details. |
| 17 | |
| 18 | // You should have received a copy of the GNU General Public License |
| 19 | // along with this program; if not, write to the Free Software |
| 20 | // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
| 21 | // MA 02110-1301, USA. |
| 22 | |
| 23 | #include "gold.h" |
| 24 | |
| 25 | #include <cstring> |
| 26 | #include <algorithm> |
| 27 | #include <iostream> |
| 28 | #include <utility> |
| 29 | |
| 30 | #include "parameters.h" |
| 31 | #include "output.h" |
| 32 | #include "symtab.h" |
| 33 | #include "dynobj.h" |
| 34 | #include "ehframe.h" |
| 35 | #include "layout.h" |
| 36 | |
| 37 | namespace gold |
| 38 | { |
| 39 | |
| 40 | // Layout_task_runner methods. |
| 41 | |
| 42 | // Lay out the sections. This is called after all the input objects |
| 43 | // have been read. |
| 44 | |
| 45 | void |
| 46 | Layout_task_runner::run(Workqueue* workqueue) |
| 47 | { |
| 48 | off_t file_size = this->layout_->finalize(this->input_objects_, |
| 49 | this->symtab_); |
| 50 | |
| 51 | // Now we know the final size of the output file and we know where |
| 52 | // each piece of information goes. |
| 53 | Output_file* of = new Output_file(this->options_, |
| 54 | this->input_objects_->target()); |
| 55 | of->open(file_size); |
| 56 | |
| 57 | // Queue up the final set of tasks. |
| 58 | gold::queue_final_tasks(this->options_, this->input_objects_, |
| 59 | this->symtab_, this->layout_, workqueue, of); |
| 60 | } |
| 61 | |
| 62 | // Layout methods. |
| 63 | |
| 64 | Layout::Layout(const General_options& options) |
| 65 | : options_(options), namepool_(), sympool_(), dynpool_(), signatures_(), |
| 66 | section_name_map_(), segment_list_(), section_list_(), |
| 67 | unattached_section_list_(), special_output_list_(), |
| 68 | tls_segment_(NULL), symtab_section_(NULL), |
| 69 | dynsym_section_(NULL), dynamic_section_(NULL), dynamic_data_(NULL), |
| 70 | eh_frame_section_(NULL) |
| 71 | { |
| 72 | // Make space for more than enough segments for a typical file. |
| 73 | // This is just for efficiency--it's OK if we wind up needing more. |
| 74 | this->segment_list_.reserve(12); |
| 75 | |
| 76 | // We expect three unattached Output_data objects: the file header, |
| 77 | // the segment headers, and the section headers. |
| 78 | this->special_output_list_.reserve(3); |
| 79 | } |
| 80 | |
| 81 | // Hash a key we use to look up an output section mapping. |
| 82 | |
| 83 | size_t |
| 84 | Layout::Hash_key::operator()(const Layout::Key& k) const |
| 85 | { |
| 86 | return k.first + k.second.first + k.second.second; |
| 87 | } |
| 88 | |
| 89 | // Whether to include this section in the link. |
| 90 | |
| 91 | template<int size, bool big_endian> |
| 92 | bool |
| 93 | Layout::include_section(Object*, const char*, |
| 94 | const elfcpp::Shdr<size, big_endian>& shdr) |
| 95 | { |
| 96 | // Some section types are never linked. Some are only linked when |
| 97 | // doing a relocateable link. |
| 98 | switch (shdr.get_sh_type()) |
| 99 | { |
| 100 | case elfcpp::SHT_NULL: |
| 101 | case elfcpp::SHT_SYMTAB: |
| 102 | case elfcpp::SHT_DYNSYM: |
| 103 | case elfcpp::SHT_STRTAB: |
| 104 | case elfcpp::SHT_HASH: |
| 105 | case elfcpp::SHT_DYNAMIC: |
| 106 | case elfcpp::SHT_SYMTAB_SHNDX: |
| 107 | return false; |
| 108 | |
| 109 | case elfcpp::SHT_RELA: |
| 110 | case elfcpp::SHT_REL: |
| 111 | case elfcpp::SHT_GROUP: |
| 112 | return parameters->output_is_object(); |
| 113 | |
| 114 | default: |
| 115 | // FIXME: Handle stripping debug sections here. |
| 116 | return true; |
| 117 | } |
| 118 | } |
| 119 | |
| 120 | // Return an output section named NAME, or NULL if there is none. |
| 121 | |
| 122 | Output_section* |
| 123 | Layout::find_output_section(const char* name) const |
| 124 | { |
| 125 | for (Section_name_map::const_iterator p = this->section_name_map_.begin(); |
| 126 | p != this->section_name_map_.end(); |
| 127 | ++p) |
| 128 | if (strcmp(p->second->name(), name) == 0) |
| 129 | return p->second; |
| 130 | return NULL; |
| 131 | } |
| 132 | |
| 133 | // Return an output segment of type TYPE, with segment flags SET set |
| 134 | // and segment flags CLEAR clear. Return NULL if there is none. |
| 135 | |
| 136 | Output_segment* |
| 137 | Layout::find_output_segment(elfcpp::PT type, elfcpp::Elf_Word set, |
| 138 | elfcpp::Elf_Word clear) const |
| 139 | { |
| 140 | for (Segment_list::const_iterator p = this->segment_list_.begin(); |
| 141 | p != this->segment_list_.end(); |
| 142 | ++p) |
| 143 | if (static_cast<elfcpp::PT>((*p)->type()) == type |
| 144 | && ((*p)->flags() & set) == set |
| 145 | && ((*p)->flags() & clear) == 0) |
| 146 | return *p; |
| 147 | return NULL; |
| 148 | } |
| 149 | |
| 150 | // Return the output section to use for section NAME with type TYPE |
| 151 | // and section flags FLAGS. |
| 152 | |
| 153 | Output_section* |
| 154 | Layout::get_output_section(const char* name, Stringpool::Key name_key, |
| 155 | elfcpp::Elf_Word type, elfcpp::Elf_Xword flags) |
| 156 | { |
| 157 | // We should ignore some flags. |
| 158 | flags &= ~ (elfcpp::SHF_INFO_LINK |
| 159 | | elfcpp::SHF_LINK_ORDER |
| 160 | | elfcpp::SHF_GROUP |
| 161 | | elfcpp::SHF_MERGE |
| 162 | | elfcpp::SHF_STRINGS); |
| 163 | |
| 164 | const Key key(name_key, std::make_pair(type, flags)); |
| 165 | const std::pair<Key, Output_section*> v(key, NULL); |
| 166 | std::pair<Section_name_map::iterator, bool> ins( |
| 167 | this->section_name_map_.insert(v)); |
| 168 | |
| 169 | if (!ins.second) |
| 170 | return ins.first->second; |
| 171 | else |
| 172 | { |
| 173 | // This is the first time we've seen this name/type/flags |
| 174 | // combination. |
| 175 | Output_section* os = this->make_output_section(name, type, flags); |
| 176 | ins.first->second = os; |
| 177 | return os; |
| 178 | } |
| 179 | } |
| 180 | |
| 181 | // Return the output section to use for input section SHNDX, with name |
| 182 | // NAME, with header HEADER, from object OBJECT. Set *OFF to the |
| 183 | // offset of this input section without the output section. |
| 184 | |
| 185 | template<int size, bool big_endian> |
| 186 | Output_section* |
| 187 | Layout::layout(Relobj* object, unsigned int shndx, const char* name, |
| 188 | const elfcpp::Shdr<size, big_endian>& shdr, off_t* off) |
| 189 | { |
| 190 | if (!this->include_section(object, name, shdr)) |
| 191 | return NULL; |
| 192 | |
| 193 | // If we are not doing a relocateable link, choose the name to use |
| 194 | // for the output section. |
| 195 | size_t len = strlen(name); |
| 196 | if (!parameters->output_is_object()) |
| 197 | name = Layout::output_section_name(name, &len); |
| 198 | |
| 199 | // FIXME: Handle SHF_OS_NONCONFORMING here. |
| 200 | |
| 201 | // Canonicalize the section name. |
| 202 | Stringpool::Key name_key; |
| 203 | name = this->namepool_.add(name, len, &name_key); |
| 204 | |
| 205 | // Find the output section. The output section is selected based on |
| 206 | // the section name, type, and flags. |
| 207 | Output_section* os = this->get_output_section(name, name_key, |
| 208 | shdr.get_sh_type(), |
| 209 | shdr.get_sh_flags()); |
| 210 | |
| 211 | // Special GNU handling of sections named .eh_frame. |
| 212 | if (!parameters->output_is_object() |
| 213 | && strcmp(name, ".eh_frame") == 0 |
| 214 | && shdr.get_sh_size() > 0 |
| 215 | && shdr.get_sh_type() == elfcpp::SHT_PROGBITS |
| 216 | && shdr.get_sh_flags() == elfcpp::SHF_ALLOC) |
| 217 | { |
| 218 | this->layout_eh_frame(object, shndx, name, shdr, os, off); |
| 219 | return os; |
| 220 | } |
| 221 | |
| 222 | // FIXME: Handle SHF_LINK_ORDER somewhere. |
| 223 | |
| 224 | *off = os->add_input_section(object, shndx, name, shdr); |
| 225 | |
| 226 | return os; |
| 227 | } |
| 228 | |
| 229 | // Special GNU handling of sections named .eh_frame. They will |
| 230 | // normally hold exception frame data. |
| 231 | |
| 232 | template<int size, bool big_endian> |
| 233 | void |
| 234 | Layout::layout_eh_frame(Relobj* object, |
| 235 | unsigned int shndx, |
| 236 | const char* name, |
| 237 | const elfcpp::Shdr<size, big_endian>& shdr, |
| 238 | Output_section* os, off_t* off) |
| 239 | { |
| 240 | if (this->eh_frame_section_ == NULL) |
| 241 | { |
| 242 | this->eh_frame_section_ = os; |
| 243 | |
| 244 | if (this->options_.create_eh_frame_hdr()) |
| 245 | { |
| 246 | Stringpool::Key hdr_name_key; |
| 247 | const char* hdr_name = this->namepool_.add(".eh_frame_hdr", |
| 248 | &hdr_name_key); |
| 249 | Output_section* hdr_os = |
| 250 | this->get_output_section(hdr_name, hdr_name_key, |
| 251 | elfcpp::SHT_PROGBITS, |
| 252 | elfcpp::SHF_ALLOC); |
| 253 | |
| 254 | Eh_frame_hdr* hdr_posd = new Eh_frame_hdr(os); |
| 255 | hdr_os->add_output_section_data(hdr_posd); |
| 256 | |
| 257 | Output_segment* hdr_oseg = |
| 258 | new Output_segment(elfcpp::PT_GNU_EH_FRAME, elfcpp::PF_R); |
| 259 | this->segment_list_.push_back(hdr_oseg); |
| 260 | hdr_oseg->add_output_section(hdr_os, elfcpp::PF_R); |
| 261 | } |
| 262 | } |
| 263 | |
| 264 | gold_assert(this->eh_frame_section_ == os); |
| 265 | |
| 266 | *off = os->add_input_section(object, shndx, name, shdr); |
| 267 | } |
| 268 | |
| 269 | // Add POSD to an output section using NAME, TYPE, and FLAGS. |
| 270 | |
| 271 | void |
| 272 | Layout::add_output_section_data(const char* name, elfcpp::Elf_Word type, |
| 273 | elfcpp::Elf_Xword flags, |
| 274 | Output_section_data* posd) |
| 275 | { |
| 276 | // Canonicalize the name. |
| 277 | Stringpool::Key name_key; |
| 278 | name = this->namepool_.add(name, &name_key); |
| 279 | |
| 280 | Output_section* os = this->get_output_section(name, name_key, type, flags); |
| 281 | os->add_output_section_data(posd); |
| 282 | } |
| 283 | |
| 284 | // Map section flags to segment flags. |
| 285 | |
| 286 | elfcpp::Elf_Word |
| 287 | Layout::section_flags_to_segment(elfcpp::Elf_Xword flags) |
| 288 | { |
| 289 | elfcpp::Elf_Word ret = elfcpp::PF_R; |
| 290 | if ((flags & elfcpp::SHF_WRITE) != 0) |
| 291 | ret |= elfcpp::PF_W; |
| 292 | if ((flags & elfcpp::SHF_EXECINSTR) != 0) |
| 293 | ret |= elfcpp::PF_X; |
| 294 | return ret; |
| 295 | } |
| 296 | |
| 297 | // Make a new Output_section, and attach it to segments as |
| 298 | // appropriate. |
| 299 | |
| 300 | Output_section* |
| 301 | Layout::make_output_section(const char* name, elfcpp::Elf_Word type, |
| 302 | elfcpp::Elf_Xword flags) |
| 303 | { |
| 304 | Output_section* os = new Output_section(name, type, flags); |
| 305 | this->section_list_.push_back(os); |
| 306 | |
| 307 | if ((flags & elfcpp::SHF_ALLOC) == 0) |
| 308 | this->unattached_section_list_.push_back(os); |
| 309 | else |
| 310 | { |
| 311 | // This output section goes into a PT_LOAD segment. |
| 312 | |
| 313 | elfcpp::Elf_Word seg_flags = Layout::section_flags_to_segment(flags); |
| 314 | |
| 315 | // The only thing we really care about for PT_LOAD segments is |
| 316 | // whether or not they are writable, so that is how we search |
| 317 | // for them. People who need segments sorted on some other |
| 318 | // basis will have to wait until we implement a mechanism for |
| 319 | // them to describe the segments they want. |
| 320 | |
| 321 | Segment_list::const_iterator p; |
| 322 | for (p = this->segment_list_.begin(); |
| 323 | p != this->segment_list_.end(); |
| 324 | ++p) |
| 325 | { |
| 326 | if ((*p)->type() == elfcpp::PT_LOAD |
| 327 | && ((*p)->flags() & elfcpp::PF_W) == (seg_flags & elfcpp::PF_W)) |
| 328 | { |
| 329 | (*p)->add_output_section(os, seg_flags); |
| 330 | break; |
| 331 | } |
| 332 | } |
| 333 | |
| 334 | if (p == this->segment_list_.end()) |
| 335 | { |
| 336 | Output_segment* oseg = new Output_segment(elfcpp::PT_LOAD, |
| 337 | seg_flags); |
| 338 | this->segment_list_.push_back(oseg); |
| 339 | oseg->add_output_section(os, seg_flags); |
| 340 | } |
| 341 | |
| 342 | // If we see a loadable SHT_NOTE section, we create a PT_NOTE |
| 343 | // segment. |
| 344 | if (type == elfcpp::SHT_NOTE) |
| 345 | { |
| 346 | // See if we already have an equivalent PT_NOTE segment. |
| 347 | for (p = this->segment_list_.begin(); |
| 348 | p != segment_list_.end(); |
| 349 | ++p) |
| 350 | { |
| 351 | if ((*p)->type() == elfcpp::PT_NOTE |
| 352 | && (((*p)->flags() & elfcpp::PF_W) |
| 353 | == (seg_flags & elfcpp::PF_W))) |
| 354 | { |
| 355 | (*p)->add_output_section(os, seg_flags); |
| 356 | break; |
| 357 | } |
| 358 | } |
| 359 | |
| 360 | if (p == this->segment_list_.end()) |
| 361 | { |
| 362 | Output_segment* oseg = new Output_segment(elfcpp::PT_NOTE, |
| 363 | seg_flags); |
| 364 | this->segment_list_.push_back(oseg); |
| 365 | oseg->add_output_section(os, seg_flags); |
| 366 | } |
| 367 | } |
| 368 | |
| 369 | // If we see a loadable SHF_TLS section, we create a PT_TLS |
| 370 | // segment. There can only be one such segment. |
| 371 | if ((flags & elfcpp::SHF_TLS) != 0) |
| 372 | { |
| 373 | if (this->tls_segment_ == NULL) |
| 374 | { |
| 375 | this->tls_segment_ = new Output_segment(elfcpp::PT_TLS, |
| 376 | seg_flags); |
| 377 | this->segment_list_.push_back(this->tls_segment_); |
| 378 | } |
| 379 | this->tls_segment_->add_output_section(os, seg_flags); |
| 380 | } |
| 381 | } |
| 382 | |
| 383 | return os; |
| 384 | } |
| 385 | |
| 386 | // Create the dynamic sections which are needed before we read the |
| 387 | // relocs. |
| 388 | |
| 389 | void |
| 390 | Layout::create_initial_dynamic_sections(const Input_objects* input_objects, |
| 391 | Symbol_table* symtab) |
| 392 | { |
| 393 | if (!input_objects->any_dynamic()) |
| 394 | return; |
| 395 | |
| 396 | const char* dynamic_name = this->namepool_.add(".dynamic", NULL); |
| 397 | this->dynamic_section_ = this->make_output_section(dynamic_name, |
| 398 | elfcpp::SHT_DYNAMIC, |
| 399 | (elfcpp::SHF_ALLOC |
| 400 | | elfcpp::SHF_WRITE)); |
| 401 | |
| 402 | symtab->define_in_output_data(input_objects->target(), "_DYNAMIC", NULL, |
| 403 | this->dynamic_section_, 0, 0, |
| 404 | elfcpp::STT_OBJECT, elfcpp::STB_LOCAL, |
| 405 | elfcpp::STV_HIDDEN, 0, false, false); |
| 406 | |
| 407 | this->dynamic_data_ = new Output_data_dynamic(&this->dynpool_); |
| 408 | |
| 409 | this->dynamic_section_->add_output_section_data(this->dynamic_data_); |
| 410 | } |
| 411 | |
| 412 | // For each output section whose name can be represented as C symbol, |
| 413 | // define __start and __stop symbols for the section. This is a GNU |
| 414 | // extension. |
| 415 | |
| 416 | void |
| 417 | Layout::define_section_symbols(Symbol_table* symtab, const Target* target) |
| 418 | { |
| 419 | for (Section_list::const_iterator p = this->section_list_.begin(); |
| 420 | p != this->section_list_.end(); |
| 421 | ++p) |
| 422 | { |
| 423 | const char* const name = (*p)->name(); |
| 424 | if (name[strspn(name, |
| 425 | ("0123456789" |
| 426 | "ABCDEFGHIJKLMNOPWRSTUVWXYZ" |
| 427 | "abcdefghijklmnopqrstuvwxyz" |
| 428 | "_"))] |
| 429 | == '\0') |
| 430 | { |
| 431 | const std::string name_string(name); |
| 432 | const std::string start_name("__start_" + name_string); |
| 433 | const std::string stop_name("__stop_" + name_string); |
| 434 | |
| 435 | symtab->define_in_output_data(target, |
| 436 | start_name.c_str(), |
| 437 | NULL, // version |
| 438 | *p, |
| 439 | 0, // value |
| 440 | 0, // symsize |
| 441 | elfcpp::STT_NOTYPE, |
| 442 | elfcpp::STB_GLOBAL, |
| 443 | elfcpp::STV_DEFAULT, |
| 444 | 0, // nonvis |
| 445 | false, // offset_is_from_end |
| 446 | false); // only_if_ref |
| 447 | |
| 448 | symtab->define_in_output_data(target, |
| 449 | stop_name.c_str(), |
| 450 | NULL, // version |
| 451 | *p, |
| 452 | 0, // value |
| 453 | 0, // symsize |
| 454 | elfcpp::STT_NOTYPE, |
| 455 | elfcpp::STB_GLOBAL, |
| 456 | elfcpp::STV_DEFAULT, |
| 457 | 0, // nonvis |
| 458 | true, // offset_is_from_end |
| 459 | false); // only_if_ref |
| 460 | } |
| 461 | } |
| 462 | } |
| 463 | |
| 464 | // Find the first read-only PT_LOAD segment, creating one if |
| 465 | // necessary. |
| 466 | |
| 467 | Output_segment* |
| 468 | Layout::find_first_load_seg() |
| 469 | { |
| 470 | for (Segment_list::const_iterator p = this->segment_list_.begin(); |
| 471 | p != this->segment_list_.end(); |
| 472 | ++p) |
| 473 | { |
| 474 | if ((*p)->type() == elfcpp::PT_LOAD |
| 475 | && ((*p)->flags() & elfcpp::PF_R) != 0 |
| 476 | && ((*p)->flags() & elfcpp::PF_W) == 0) |
| 477 | return *p; |
| 478 | } |
| 479 | |
| 480 | Output_segment* load_seg = new Output_segment(elfcpp::PT_LOAD, elfcpp::PF_R); |
| 481 | this->segment_list_.push_back(load_seg); |
| 482 | return load_seg; |
| 483 | } |
| 484 | |
| 485 | // Finalize the layout. When this is called, we have created all the |
| 486 | // output sections and all the output segments which are based on |
| 487 | // input sections. We have several things to do, and we have to do |
| 488 | // them in the right order, so that we get the right results correctly |
| 489 | // and efficiently. |
| 490 | |
| 491 | // 1) Finalize the list of output segments and create the segment |
| 492 | // table header. |
| 493 | |
| 494 | // 2) Finalize the dynamic symbol table and associated sections. |
| 495 | |
| 496 | // 3) Determine the final file offset of all the output segments. |
| 497 | |
| 498 | // 4) Determine the final file offset of all the SHF_ALLOC output |
| 499 | // sections. |
| 500 | |
| 501 | // 5) Create the symbol table sections and the section name table |
| 502 | // section. |
| 503 | |
| 504 | // 6) Finalize the symbol table: set symbol values to their final |
| 505 | // value and make a final determination of which symbols are going |
| 506 | // into the output symbol table. |
| 507 | |
| 508 | // 7) Create the section table header. |
| 509 | |
| 510 | // 8) Determine the final file offset of all the output sections which |
| 511 | // are not SHF_ALLOC, including the section table header. |
| 512 | |
| 513 | // 9) Finalize the ELF file header. |
| 514 | |
| 515 | // This function returns the size of the output file. |
| 516 | |
| 517 | off_t |
| 518 | Layout::finalize(const Input_objects* input_objects, Symbol_table* symtab) |
| 519 | { |
| 520 | Target* const target = input_objects->target(); |
| 521 | |
| 522 | target->finalize_sections(this); |
| 523 | |
| 524 | Output_segment* phdr_seg = NULL; |
| 525 | if (input_objects->any_dynamic()) |
| 526 | { |
| 527 | // There was a dynamic object in the link. We need to create |
| 528 | // some information for the dynamic linker. |
| 529 | |
| 530 | // Create the PT_PHDR segment which will hold the program |
| 531 | // headers. |
| 532 | phdr_seg = new Output_segment(elfcpp::PT_PHDR, elfcpp::PF_R); |
| 533 | this->segment_list_.push_back(phdr_seg); |
| 534 | |
| 535 | // Create the dynamic symbol table, including the hash table. |
| 536 | Output_section* dynstr; |
| 537 | std::vector<Symbol*> dynamic_symbols; |
| 538 | unsigned int local_dynamic_count; |
| 539 | Versions versions; |
| 540 | this->create_dynamic_symtab(target, symtab, &dynstr, |
| 541 | &local_dynamic_count, &dynamic_symbols, |
| 542 | &versions); |
| 543 | |
| 544 | // Create the .interp section to hold the name of the |
| 545 | // interpreter, and put it in a PT_INTERP segment. |
| 546 | this->create_interp(target); |
| 547 | |
| 548 | // Finish the .dynamic section to hold the dynamic data, and put |
| 549 | // it in a PT_DYNAMIC segment. |
| 550 | this->finish_dynamic_section(input_objects, symtab); |
| 551 | |
| 552 | // We should have added everything we need to the dynamic string |
| 553 | // table. |
| 554 | this->dynpool_.set_string_offsets(); |
| 555 | |
| 556 | // Create the version sections. We can't do this until the |
| 557 | // dynamic string table is complete. |
| 558 | this->create_version_sections(&versions, local_dynamic_count, |
| 559 | dynamic_symbols, dynstr); |
| 560 | } |
| 561 | |
| 562 | // FIXME: Handle PT_GNU_STACK. |
| 563 | |
| 564 | Output_segment* load_seg = this->find_first_load_seg(); |
| 565 | |
| 566 | // Lay out the segment headers. |
| 567 | Output_segment_headers* segment_headers; |
| 568 | segment_headers = new Output_segment_headers(this->segment_list_); |
| 569 | load_seg->add_initial_output_data(segment_headers); |
| 570 | this->special_output_list_.push_back(segment_headers); |
| 571 | if (phdr_seg != NULL) |
| 572 | phdr_seg->add_initial_output_data(segment_headers); |
| 573 | |
| 574 | // Lay out the file header. |
| 575 | Output_file_header* file_header; |
| 576 | file_header = new Output_file_header(target, symtab, segment_headers); |
| 577 | load_seg->add_initial_output_data(file_header); |
| 578 | this->special_output_list_.push_back(file_header); |
| 579 | |
| 580 | // We set the output section indexes in set_segment_offsets and |
| 581 | // set_section_offsets. |
| 582 | unsigned int shndx = 1; |
| 583 | |
| 584 | // Set the file offsets of all the segments, and all the sections |
| 585 | // they contain. |
| 586 | off_t off = this->set_segment_offsets(target, load_seg, &shndx); |
| 587 | |
| 588 | // Create the symbol table sections. |
| 589 | this->create_symtab_sections(input_objects, symtab, &off); |
| 590 | |
| 591 | // Create the .shstrtab section. |
| 592 | Output_section* shstrtab_section = this->create_shstrtab(); |
| 593 | |
| 594 | // Set the file offsets of all the sections not associated with |
| 595 | // segments. |
| 596 | off = this->set_section_offsets(off, &shndx); |
| 597 | |
| 598 | // Create the section table header. |
| 599 | Output_section_headers* oshdrs = this->create_shdrs(&off); |
| 600 | |
| 601 | file_header->set_section_info(oshdrs, shstrtab_section); |
| 602 | |
| 603 | // Now we know exactly where everything goes in the output file. |
| 604 | Output_data::layout_complete(); |
| 605 | |
| 606 | return off; |
| 607 | } |
| 608 | |
| 609 | // Return whether SEG1 should be before SEG2 in the output file. This |
| 610 | // is based entirely on the segment type and flags. When this is |
| 611 | // called the segment addresses has normally not yet been set. |
| 612 | |
| 613 | bool |
| 614 | Layout::segment_precedes(const Output_segment* seg1, |
| 615 | const Output_segment* seg2) |
| 616 | { |
| 617 | elfcpp::Elf_Word type1 = seg1->type(); |
| 618 | elfcpp::Elf_Word type2 = seg2->type(); |
| 619 | |
| 620 | // The single PT_PHDR segment is required to precede any loadable |
| 621 | // segment. We simply make it always first. |
| 622 | if (type1 == elfcpp::PT_PHDR) |
| 623 | { |
| 624 | gold_assert(type2 != elfcpp::PT_PHDR); |
| 625 | return true; |
| 626 | } |
| 627 | if (type2 == elfcpp::PT_PHDR) |
| 628 | return false; |
| 629 | |
| 630 | // The single PT_INTERP segment is required to precede any loadable |
| 631 | // segment. We simply make it always second. |
| 632 | if (type1 == elfcpp::PT_INTERP) |
| 633 | { |
| 634 | gold_assert(type2 != elfcpp::PT_INTERP); |
| 635 | return true; |
| 636 | } |
| 637 | if (type2 == elfcpp::PT_INTERP) |
| 638 | return false; |
| 639 | |
| 640 | // We then put PT_LOAD segments before any other segments. |
| 641 | if (type1 == elfcpp::PT_LOAD && type2 != elfcpp::PT_LOAD) |
| 642 | return true; |
| 643 | if (type2 == elfcpp::PT_LOAD && type1 != elfcpp::PT_LOAD) |
| 644 | return false; |
| 645 | |
| 646 | // We put the PT_TLS segment last, because that is where the dynamic |
| 647 | // linker expects to find it (this is just for efficiency; other |
| 648 | // positions would also work correctly). |
| 649 | if (type1 == elfcpp::PT_TLS && type2 != elfcpp::PT_TLS) |
| 650 | return false; |
| 651 | if (type2 == elfcpp::PT_TLS && type1 != elfcpp::PT_TLS) |
| 652 | return true; |
| 653 | |
| 654 | const elfcpp::Elf_Word flags1 = seg1->flags(); |
| 655 | const elfcpp::Elf_Word flags2 = seg2->flags(); |
| 656 | |
| 657 | // The order of non-PT_LOAD segments is unimportant. We simply sort |
| 658 | // by the numeric segment type and flags values. There should not |
| 659 | // be more than one segment with the same type and flags. |
| 660 | if (type1 != elfcpp::PT_LOAD) |
| 661 | { |
| 662 | if (type1 != type2) |
| 663 | return type1 < type2; |
| 664 | gold_assert(flags1 != flags2); |
| 665 | return flags1 < flags2; |
| 666 | } |
| 667 | |
| 668 | // We sort PT_LOAD segments based on the flags. Readonly segments |
| 669 | // come before writable segments. Then executable segments come |
| 670 | // before non-executable segments. Then the unlikely case of a |
| 671 | // non-readable segment comes before the normal case of a readable |
| 672 | // segment. If there are multiple segments with the same type and |
| 673 | // flags, we require that the address be set, and we sort by |
| 674 | // virtual address and then physical address. |
| 675 | if ((flags1 & elfcpp::PF_W) != (flags2 & elfcpp::PF_W)) |
| 676 | return (flags1 & elfcpp::PF_W) == 0; |
| 677 | if ((flags1 & elfcpp::PF_X) != (flags2 & elfcpp::PF_X)) |
| 678 | return (flags1 & elfcpp::PF_X) != 0; |
| 679 | if ((flags1 & elfcpp::PF_R) != (flags2 & elfcpp::PF_R)) |
| 680 | return (flags1 & elfcpp::PF_R) == 0; |
| 681 | |
| 682 | uint64_t vaddr1 = seg1->vaddr(); |
| 683 | uint64_t vaddr2 = seg2->vaddr(); |
| 684 | if (vaddr1 != vaddr2) |
| 685 | return vaddr1 < vaddr2; |
| 686 | |
| 687 | uint64_t paddr1 = seg1->paddr(); |
| 688 | uint64_t paddr2 = seg2->paddr(); |
| 689 | gold_assert(paddr1 != paddr2); |
| 690 | return paddr1 < paddr2; |
| 691 | } |
| 692 | |
| 693 | // Set the file offsets of all the segments, and all the sections they |
| 694 | // contain. They have all been created. LOAD_SEG must be be laid out |
| 695 | // first. Return the offset of the data to follow. |
| 696 | |
| 697 | off_t |
| 698 | Layout::set_segment_offsets(const Target* target, Output_segment* load_seg, |
| 699 | unsigned int *pshndx) |
| 700 | { |
| 701 | // Sort them into the final order. |
| 702 | std::sort(this->segment_list_.begin(), this->segment_list_.end(), |
| 703 | Layout::Compare_segments()); |
| 704 | |
| 705 | // Find the PT_LOAD segments, and set their addresses and offsets |
| 706 | // and their section's addresses and offsets. |
| 707 | uint64_t addr = target->text_segment_address(); |
| 708 | off_t off = 0; |
| 709 | bool was_readonly = false; |
| 710 | for (Segment_list::iterator p = this->segment_list_.begin(); |
| 711 | p != this->segment_list_.end(); |
| 712 | ++p) |
| 713 | { |
| 714 | if ((*p)->type() == elfcpp::PT_LOAD) |
| 715 | { |
| 716 | if (load_seg != NULL && load_seg != *p) |
| 717 | gold_unreachable(); |
| 718 | load_seg = NULL; |
| 719 | |
| 720 | // If the last segment was readonly, and this one is not, |
| 721 | // then skip the address forward one page, maintaining the |
| 722 | // same position within the page. This lets us store both |
| 723 | // segments overlapping on a single page in the file, but |
| 724 | // the loader will put them on different pages in memory. |
| 725 | |
| 726 | uint64_t orig_addr = addr; |
| 727 | uint64_t orig_off = off; |
| 728 | |
| 729 | uint64_t aligned_addr = addr; |
| 730 | uint64_t abi_pagesize = target->abi_pagesize(); |
| 731 | |
| 732 | // FIXME: This should depend on the -n and -N options. |
| 733 | (*p)->set_minimum_addralign(target->common_pagesize()); |
| 734 | |
| 735 | if (was_readonly && ((*p)->flags() & elfcpp::PF_W) != 0) |
| 736 | { |
| 737 | uint64_t align = (*p)->addralign(); |
| 738 | |
| 739 | addr = align_address(addr, align); |
| 740 | aligned_addr = addr; |
| 741 | if ((addr & (abi_pagesize - 1)) != 0) |
| 742 | addr = addr + abi_pagesize; |
| 743 | } |
| 744 | |
| 745 | unsigned int shndx_hold = *pshndx; |
| 746 | off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1)); |
| 747 | uint64_t new_addr = (*p)->set_section_addresses(addr, &off, pshndx); |
| 748 | |
| 749 | // Now that we know the size of this segment, we may be able |
| 750 | // to save a page in memory, at the cost of wasting some |
| 751 | // file space, by instead aligning to the start of a new |
| 752 | // page. Here we use the real machine page size rather than |
| 753 | // the ABI mandated page size. |
| 754 | |
| 755 | if (aligned_addr != addr) |
| 756 | { |
| 757 | uint64_t common_pagesize = target->common_pagesize(); |
| 758 | uint64_t first_off = (common_pagesize |
| 759 | - (aligned_addr |
| 760 | & (common_pagesize - 1))); |
| 761 | uint64_t last_off = new_addr & (common_pagesize - 1); |
| 762 | if (first_off > 0 |
| 763 | && last_off > 0 |
| 764 | && ((aligned_addr & ~ (common_pagesize - 1)) |
| 765 | != (new_addr & ~ (common_pagesize - 1))) |
| 766 | && first_off + last_off <= common_pagesize) |
| 767 | { |
| 768 | *pshndx = shndx_hold; |
| 769 | addr = align_address(aligned_addr, common_pagesize); |
| 770 | off = orig_off + ((addr - orig_addr) & (abi_pagesize - 1)); |
| 771 | new_addr = (*p)->set_section_addresses(addr, &off, pshndx); |
| 772 | } |
| 773 | } |
| 774 | |
| 775 | addr = new_addr; |
| 776 | |
| 777 | if (((*p)->flags() & elfcpp::PF_W) == 0) |
| 778 | was_readonly = true; |
| 779 | } |
| 780 | } |
| 781 | |
| 782 | // Handle the non-PT_LOAD segments, setting their offsets from their |
| 783 | // section's offsets. |
| 784 | for (Segment_list::iterator p = this->segment_list_.begin(); |
| 785 | p != this->segment_list_.end(); |
| 786 | ++p) |
| 787 | { |
| 788 | if ((*p)->type() != elfcpp::PT_LOAD) |
| 789 | (*p)->set_offset(); |
| 790 | } |
| 791 | |
| 792 | return off; |
| 793 | } |
| 794 | |
| 795 | // Set the file offset of all the sections not associated with a |
| 796 | // segment. |
| 797 | |
| 798 | off_t |
| 799 | Layout::set_section_offsets(off_t off, unsigned int* pshndx) |
| 800 | { |
| 801 | for (Section_list::iterator p = this->unattached_section_list_.begin(); |
| 802 | p != this->unattached_section_list_.end(); |
| 803 | ++p) |
| 804 | { |
| 805 | (*p)->set_out_shndx(*pshndx); |
| 806 | ++*pshndx; |
| 807 | if ((*p)->offset() != -1) |
| 808 | continue; |
| 809 | off = align_address(off, (*p)->addralign()); |
| 810 | (*p)->set_address(0, off); |
| 811 | off += (*p)->data_size(); |
| 812 | } |
| 813 | return off; |
| 814 | } |
| 815 | |
| 816 | // Create the symbol table sections. Here we also set the final |
| 817 | // values of the symbols. At this point all the loadable sections are |
| 818 | // fully laid out. |
| 819 | |
| 820 | void |
| 821 | Layout::create_symtab_sections(const Input_objects* input_objects, |
| 822 | Symbol_table* symtab, |
| 823 | off_t* poff) |
| 824 | { |
| 825 | int symsize; |
| 826 | unsigned int align; |
| 827 | if (parameters->get_size() == 32) |
| 828 | { |
| 829 | symsize = elfcpp::Elf_sizes<32>::sym_size; |
| 830 | align = 4; |
| 831 | } |
| 832 | else if (parameters->get_size() == 64) |
| 833 | { |
| 834 | symsize = elfcpp::Elf_sizes<64>::sym_size; |
| 835 | align = 8; |
| 836 | } |
| 837 | else |
| 838 | gold_unreachable(); |
| 839 | |
| 840 | off_t off = *poff; |
| 841 | off = align_address(off, align); |
| 842 | off_t startoff = off; |
| 843 | |
| 844 | // Save space for the dummy symbol at the start of the section. We |
| 845 | // never bother to write this out--it will just be left as zero. |
| 846 | off += symsize; |
| 847 | unsigned int local_symbol_index = 1; |
| 848 | |
| 849 | // Add STT_SECTION symbols for each Output section which needs one. |
| 850 | for (Section_list::iterator p = this->section_list_.begin(); |
| 851 | p != this->section_list_.end(); |
| 852 | ++p) |
| 853 | { |
| 854 | if (!(*p)->needs_symtab_index()) |
| 855 | (*p)->set_symtab_index(-1U); |
| 856 | else |
| 857 | { |
| 858 | (*p)->set_symtab_index(local_symbol_index); |
| 859 | ++local_symbol_index; |
| 860 | off += symsize; |
| 861 | } |
| 862 | } |
| 863 | |
| 864 | for (Input_objects::Relobj_iterator p = input_objects->relobj_begin(); |
| 865 | p != input_objects->relobj_end(); |
| 866 | ++p) |
| 867 | { |
| 868 | Task_lock_obj<Object> tlo(**p); |
| 869 | unsigned int index = (*p)->finalize_local_symbols(local_symbol_index, |
| 870 | off, |
| 871 | &this->sympool_); |
| 872 | off += (index - local_symbol_index) * symsize; |
| 873 | local_symbol_index = index; |
| 874 | } |
| 875 | |
| 876 | unsigned int local_symcount = local_symbol_index; |
| 877 | gold_assert(local_symcount * symsize == off - startoff); |
| 878 | |
| 879 | off_t dynoff; |
| 880 | size_t dyn_global_index; |
| 881 | size_t dyncount; |
| 882 | if (this->dynsym_section_ == NULL) |
| 883 | { |
| 884 | dynoff = 0; |
| 885 | dyn_global_index = 0; |
| 886 | dyncount = 0; |
| 887 | } |
| 888 | else |
| 889 | { |
| 890 | dyn_global_index = this->dynsym_section_->info(); |
| 891 | off_t locsize = dyn_global_index * this->dynsym_section_->entsize(); |
| 892 | dynoff = this->dynsym_section_->offset() + locsize; |
| 893 | dyncount = (this->dynsym_section_->data_size() - locsize) / symsize; |
| 894 | gold_assert(dyncount * symsize |
| 895 | == this->dynsym_section_->data_size() - locsize); |
| 896 | } |
| 897 | |
| 898 | off = symtab->finalize(local_symcount, off, dynoff, dyn_global_index, |
| 899 | dyncount, &this->sympool_); |
| 900 | |
| 901 | this->sympool_.set_string_offsets(); |
| 902 | |
| 903 | const char* symtab_name = this->namepool_.add(".symtab", NULL); |
| 904 | Output_section* osymtab = this->make_output_section(symtab_name, |
| 905 | elfcpp::SHT_SYMTAB, |
| 906 | 0); |
| 907 | this->symtab_section_ = osymtab; |
| 908 | |
| 909 | Output_section_data* pos = new Output_data_space(off - startoff, |
| 910 | align); |
| 911 | osymtab->add_output_section_data(pos); |
| 912 | |
| 913 | const char* strtab_name = this->namepool_.add(".strtab", NULL); |
| 914 | Output_section* ostrtab = this->make_output_section(strtab_name, |
| 915 | elfcpp::SHT_STRTAB, |
| 916 | 0); |
| 917 | |
| 918 | Output_section_data* pstr = new Output_data_strtab(&this->sympool_); |
| 919 | ostrtab->add_output_section_data(pstr); |
| 920 | |
| 921 | osymtab->set_address(0, startoff); |
| 922 | osymtab->set_link_section(ostrtab); |
| 923 | osymtab->set_info(local_symcount); |
| 924 | osymtab->set_entsize(symsize); |
| 925 | |
| 926 | *poff = off; |
| 927 | } |
| 928 | |
| 929 | // Create the .shstrtab section, which holds the names of the |
| 930 | // sections. At the time this is called, we have created all the |
| 931 | // output sections except .shstrtab itself. |
| 932 | |
| 933 | Output_section* |
| 934 | Layout::create_shstrtab() |
| 935 | { |
| 936 | // FIXME: We don't need to create a .shstrtab section if we are |
| 937 | // stripping everything. |
| 938 | |
| 939 | const char* name = this->namepool_.add(".shstrtab", NULL); |
| 940 | |
| 941 | this->namepool_.set_string_offsets(); |
| 942 | |
| 943 | Output_section* os = this->make_output_section(name, elfcpp::SHT_STRTAB, 0); |
| 944 | |
| 945 | Output_section_data* posd = new Output_data_strtab(&this->namepool_); |
| 946 | os->add_output_section_data(posd); |
| 947 | |
| 948 | return os; |
| 949 | } |
| 950 | |
| 951 | // Create the section headers. SIZE is 32 or 64. OFF is the file |
| 952 | // offset. |
| 953 | |
| 954 | Output_section_headers* |
| 955 | Layout::create_shdrs(off_t* poff) |
| 956 | { |
| 957 | Output_section_headers* oshdrs; |
| 958 | oshdrs = new Output_section_headers(this, |
| 959 | &this->segment_list_, |
| 960 | &this->unattached_section_list_, |
| 961 | &this->namepool_); |
| 962 | off_t off = align_address(*poff, oshdrs->addralign()); |
| 963 | oshdrs->set_address(0, off); |
| 964 | off += oshdrs->data_size(); |
| 965 | *poff = off; |
| 966 | this->special_output_list_.push_back(oshdrs); |
| 967 | return oshdrs; |
| 968 | } |
| 969 | |
| 970 | // Create the dynamic symbol table. |
| 971 | |
| 972 | void |
| 973 | Layout::create_dynamic_symtab(const Target* target, Symbol_table* symtab, |
| 974 | Output_section **pdynstr, |
| 975 | unsigned int* plocal_dynamic_count, |
| 976 | std::vector<Symbol*>* pdynamic_symbols, |
| 977 | Versions* pversions) |
| 978 | { |
| 979 | // Count all the symbols in the dynamic symbol table, and set the |
| 980 | // dynamic symbol indexes. |
| 981 | |
| 982 | // Skip symbol 0, which is always all zeroes. |
| 983 | unsigned int index = 1; |
| 984 | |
| 985 | // Add STT_SECTION symbols for each Output section which needs one. |
| 986 | for (Section_list::iterator p = this->section_list_.begin(); |
| 987 | p != this->section_list_.end(); |
| 988 | ++p) |
| 989 | { |
| 990 | if (!(*p)->needs_dynsym_index()) |
| 991 | (*p)->set_dynsym_index(-1U); |
| 992 | else |
| 993 | { |
| 994 | (*p)->set_dynsym_index(index); |
| 995 | ++index; |
| 996 | } |
| 997 | } |
| 998 | |
| 999 | // FIXME: Some targets apparently require local symbols in the |
| 1000 | // dynamic symbol table. Here is where we will have to count them, |
| 1001 | // and set the dynamic symbol indexes, and add the names to |
| 1002 | // this->dynpool_. |
| 1003 | |
| 1004 | unsigned int local_symcount = index; |
| 1005 | *plocal_dynamic_count = local_symcount; |
| 1006 | |
| 1007 | // FIXME: We have to tell set_dynsym_indexes whether the |
| 1008 | // -E/--export-dynamic option was used. |
| 1009 | index = symtab->set_dynsym_indexes(&this->options_, target, index, |
| 1010 | pdynamic_symbols, &this->dynpool_, |
| 1011 | pversions); |
| 1012 | |
| 1013 | int symsize; |
| 1014 | unsigned int align; |
| 1015 | const int size = parameters->get_size(); |
| 1016 | if (size == 32) |
| 1017 | { |
| 1018 | symsize = elfcpp::Elf_sizes<32>::sym_size; |
| 1019 | align = 4; |
| 1020 | } |
| 1021 | else if (size == 64) |
| 1022 | { |
| 1023 | symsize = elfcpp::Elf_sizes<64>::sym_size; |
| 1024 | align = 8; |
| 1025 | } |
| 1026 | else |
| 1027 | gold_unreachable(); |
| 1028 | |
| 1029 | // Create the dynamic symbol table section. |
| 1030 | |
| 1031 | const char* dynsym_name = this->namepool_.add(".dynsym", NULL); |
| 1032 | Output_section* dynsym = this->make_output_section(dynsym_name, |
| 1033 | elfcpp::SHT_DYNSYM, |
| 1034 | elfcpp::SHF_ALLOC); |
| 1035 | |
| 1036 | Output_section_data* odata = new Output_data_space(index * symsize, |
| 1037 | align); |
| 1038 | dynsym->add_output_section_data(odata); |
| 1039 | |
| 1040 | dynsym->set_info(local_symcount); |
| 1041 | dynsym->set_entsize(symsize); |
| 1042 | dynsym->set_addralign(align); |
| 1043 | |
| 1044 | this->dynsym_section_ = dynsym; |
| 1045 | |
| 1046 | Output_data_dynamic* const odyn = this->dynamic_data_; |
| 1047 | odyn->add_section_address(elfcpp::DT_SYMTAB, dynsym); |
| 1048 | odyn->add_constant(elfcpp::DT_SYMENT, symsize); |
| 1049 | |
| 1050 | // Create the dynamic string table section. |
| 1051 | |
| 1052 | const char* dynstr_name = this->namepool_.add(".dynstr", NULL); |
| 1053 | Output_section* dynstr = this->make_output_section(dynstr_name, |
| 1054 | elfcpp::SHT_STRTAB, |
| 1055 | elfcpp::SHF_ALLOC); |
| 1056 | |
| 1057 | Output_section_data* strdata = new Output_data_strtab(&this->dynpool_); |
| 1058 | dynstr->add_output_section_data(strdata); |
| 1059 | |
| 1060 | dynsym->set_link_section(dynstr); |
| 1061 | this->dynamic_section_->set_link_section(dynstr); |
| 1062 | |
| 1063 | odyn->add_section_address(elfcpp::DT_STRTAB, dynstr); |
| 1064 | odyn->add_section_size(elfcpp::DT_STRSZ, dynstr); |
| 1065 | |
| 1066 | *pdynstr = dynstr; |
| 1067 | |
| 1068 | // Create the hash tables. |
| 1069 | |
| 1070 | // FIXME: We need an option to create a GNU hash table. |
| 1071 | |
| 1072 | unsigned char* phash; |
| 1073 | unsigned int hashlen; |
| 1074 | Dynobj::create_elf_hash_table(*pdynamic_symbols, local_symcount, |
| 1075 | &phash, &hashlen); |
| 1076 | |
| 1077 | const char* hash_name = this->namepool_.add(".hash", NULL); |
| 1078 | Output_section* hashsec = this->make_output_section(hash_name, |
| 1079 | elfcpp::SHT_HASH, |
| 1080 | elfcpp::SHF_ALLOC); |
| 1081 | |
| 1082 | Output_section_data* hashdata = new Output_data_const_buffer(phash, |
| 1083 | hashlen, |
| 1084 | align); |
| 1085 | hashsec->add_output_section_data(hashdata); |
| 1086 | |
| 1087 | hashsec->set_link_section(dynsym); |
| 1088 | hashsec->set_entsize(4); |
| 1089 | |
| 1090 | odyn->add_section_address(elfcpp::DT_HASH, hashsec); |
| 1091 | } |
| 1092 | |
| 1093 | // Create the version sections. |
| 1094 | |
| 1095 | void |
| 1096 | Layout::create_version_sections(const Versions* versions, |
| 1097 | unsigned int local_symcount, |
| 1098 | const std::vector<Symbol*>& dynamic_symbols, |
| 1099 | const Output_section* dynstr) |
| 1100 | { |
| 1101 | if (!versions->any_defs() && !versions->any_needs()) |
| 1102 | return; |
| 1103 | |
| 1104 | if (parameters->get_size() == 32) |
| 1105 | { |
| 1106 | if (parameters->is_big_endian()) |
| 1107 | { |
| 1108 | #ifdef HAVE_TARGET_32_BIG |
| 1109 | this->sized_create_version_sections |
| 1110 | SELECT_SIZE_ENDIAN_NAME(32, true)( |
| 1111 | versions, local_symcount, dynamic_symbols, dynstr |
| 1112 | SELECT_SIZE_ENDIAN(32, true)); |
| 1113 | #else |
| 1114 | gold_unreachable(); |
| 1115 | #endif |
| 1116 | } |
| 1117 | else |
| 1118 | { |
| 1119 | #ifdef HAVE_TARGET_32_LITTLE |
| 1120 | this->sized_create_version_sections |
| 1121 | SELECT_SIZE_ENDIAN_NAME(32, false)( |
| 1122 | versions, local_symcount, dynamic_symbols, dynstr |
| 1123 | SELECT_SIZE_ENDIAN(32, false)); |
| 1124 | #else |
| 1125 | gold_unreachable(); |
| 1126 | #endif |
| 1127 | } |
| 1128 | } |
| 1129 | else if (parameters->get_size() == 64) |
| 1130 | { |
| 1131 | if (parameters->is_big_endian()) |
| 1132 | { |
| 1133 | #ifdef HAVE_TARGET_64_BIG |
| 1134 | this->sized_create_version_sections |
| 1135 | SELECT_SIZE_ENDIAN_NAME(64, true)( |
| 1136 | versions, local_symcount, dynamic_symbols, dynstr |
| 1137 | SELECT_SIZE_ENDIAN(64, true)); |
| 1138 | #else |
| 1139 | gold_unreachable(); |
| 1140 | #endif |
| 1141 | } |
| 1142 | else |
| 1143 | { |
| 1144 | #ifdef HAVE_TARGET_64_LITTLE |
| 1145 | this->sized_create_version_sections |
| 1146 | SELECT_SIZE_ENDIAN_NAME(64, false)( |
| 1147 | versions, local_symcount, dynamic_symbols, dynstr |
| 1148 | SELECT_SIZE_ENDIAN(64, false)); |
| 1149 | #else |
| 1150 | gold_unreachable(); |
| 1151 | #endif |
| 1152 | } |
| 1153 | } |
| 1154 | else |
| 1155 | gold_unreachable(); |
| 1156 | } |
| 1157 | |
| 1158 | // Create the version sections, sized version. |
| 1159 | |
| 1160 | template<int size, bool big_endian> |
| 1161 | void |
| 1162 | Layout::sized_create_version_sections( |
| 1163 | const Versions* versions, |
| 1164 | unsigned int local_symcount, |
| 1165 | const std::vector<Symbol*>& dynamic_symbols, |
| 1166 | const Output_section* dynstr |
| 1167 | ACCEPT_SIZE_ENDIAN) |
| 1168 | { |
| 1169 | const char* vname = this->namepool_.add(".gnu.version", NULL); |
| 1170 | Output_section* vsec = this->make_output_section(vname, |
| 1171 | elfcpp::SHT_GNU_versym, |
| 1172 | elfcpp::SHF_ALLOC); |
| 1173 | |
| 1174 | unsigned char* vbuf; |
| 1175 | unsigned int vsize; |
| 1176 | versions->symbol_section_contents SELECT_SIZE_ENDIAN_NAME(size, big_endian)( |
| 1177 | &this->dynpool_, local_symcount, dynamic_symbols, &vbuf, &vsize |
| 1178 | SELECT_SIZE_ENDIAN(size, big_endian)); |
| 1179 | |
| 1180 | Output_section_data* vdata = new Output_data_const_buffer(vbuf, vsize, 2); |
| 1181 | |
| 1182 | vsec->add_output_section_data(vdata); |
| 1183 | vsec->set_entsize(2); |
| 1184 | vsec->set_link_section(this->dynsym_section_); |
| 1185 | |
| 1186 | Output_data_dynamic* const odyn = this->dynamic_data_; |
| 1187 | odyn->add_section_address(elfcpp::DT_VERSYM, vsec); |
| 1188 | |
| 1189 | if (versions->any_defs()) |
| 1190 | { |
| 1191 | const char* vdname = this->namepool_.add(".gnu.version_d", NULL); |
| 1192 | Output_section *vdsec; |
| 1193 | vdsec = this->make_output_section(vdname, elfcpp::SHT_GNU_verdef, |
| 1194 | elfcpp::SHF_ALLOC); |
| 1195 | |
| 1196 | unsigned char* vdbuf; |
| 1197 | unsigned int vdsize; |
| 1198 | unsigned int vdentries; |
| 1199 | versions->def_section_contents SELECT_SIZE_ENDIAN_NAME(size, big_endian)( |
| 1200 | &this->dynpool_, &vdbuf, &vdsize, &vdentries |
| 1201 | SELECT_SIZE_ENDIAN(size, big_endian)); |
| 1202 | |
| 1203 | Output_section_data* vddata = new Output_data_const_buffer(vdbuf, |
| 1204 | vdsize, |
| 1205 | 4); |
| 1206 | |
| 1207 | vdsec->add_output_section_data(vddata); |
| 1208 | vdsec->set_link_section(dynstr); |
| 1209 | vdsec->set_info(vdentries); |
| 1210 | |
| 1211 | odyn->add_section_address(elfcpp::DT_VERDEF, vdsec); |
| 1212 | odyn->add_constant(elfcpp::DT_VERDEFNUM, vdentries); |
| 1213 | } |
| 1214 | |
| 1215 | if (versions->any_needs()) |
| 1216 | { |
| 1217 | const char* vnname = this->namepool_.add(".gnu.version_r", NULL); |
| 1218 | Output_section* vnsec; |
| 1219 | vnsec = this->make_output_section(vnname, elfcpp::SHT_GNU_verneed, |
| 1220 | elfcpp::SHF_ALLOC); |
| 1221 | |
| 1222 | unsigned char* vnbuf; |
| 1223 | unsigned int vnsize; |
| 1224 | unsigned int vnentries; |
| 1225 | versions->need_section_contents SELECT_SIZE_ENDIAN_NAME(size, big_endian) |
| 1226 | (&this->dynpool_, &vnbuf, &vnsize, &vnentries |
| 1227 | SELECT_SIZE_ENDIAN(size, big_endian)); |
| 1228 | |
| 1229 | Output_section_data* vndata = new Output_data_const_buffer(vnbuf, |
| 1230 | vnsize, |
| 1231 | 4); |
| 1232 | |
| 1233 | vnsec->add_output_section_data(vndata); |
| 1234 | vnsec->set_link_section(dynstr); |
| 1235 | vnsec->set_info(vnentries); |
| 1236 | |
| 1237 | odyn->add_section_address(elfcpp::DT_VERNEED, vnsec); |
| 1238 | odyn->add_constant(elfcpp::DT_VERNEEDNUM, vnentries); |
| 1239 | } |
| 1240 | } |
| 1241 | |
| 1242 | // Create the .interp section and PT_INTERP segment. |
| 1243 | |
| 1244 | void |
| 1245 | Layout::create_interp(const Target* target) |
| 1246 | { |
| 1247 | const char* interp = this->options_.dynamic_linker(); |
| 1248 | if (interp == NULL) |
| 1249 | { |
| 1250 | interp = target->dynamic_linker(); |
| 1251 | gold_assert(interp != NULL); |
| 1252 | } |
| 1253 | |
| 1254 | size_t len = strlen(interp) + 1; |
| 1255 | |
| 1256 | Output_section_data* odata = new Output_data_const(interp, len, 1); |
| 1257 | |
| 1258 | const char* interp_name = this->namepool_.add(".interp", NULL); |
| 1259 | Output_section* osec = this->make_output_section(interp_name, |
| 1260 | elfcpp::SHT_PROGBITS, |
| 1261 | elfcpp::SHF_ALLOC); |
| 1262 | osec->add_output_section_data(odata); |
| 1263 | |
| 1264 | Output_segment* oseg = new Output_segment(elfcpp::PT_INTERP, elfcpp::PF_R); |
| 1265 | this->segment_list_.push_back(oseg); |
| 1266 | oseg->add_initial_output_section(osec, elfcpp::PF_R); |
| 1267 | } |
| 1268 | |
| 1269 | // Finish the .dynamic section and PT_DYNAMIC segment. |
| 1270 | |
| 1271 | void |
| 1272 | Layout::finish_dynamic_section(const Input_objects* input_objects, |
| 1273 | const Symbol_table* symtab) |
| 1274 | { |
| 1275 | Output_segment* oseg = new Output_segment(elfcpp::PT_DYNAMIC, |
| 1276 | elfcpp::PF_R | elfcpp::PF_W); |
| 1277 | this->segment_list_.push_back(oseg); |
| 1278 | oseg->add_initial_output_section(this->dynamic_section_, |
| 1279 | elfcpp::PF_R | elfcpp::PF_W); |
| 1280 | |
| 1281 | Output_data_dynamic* const odyn = this->dynamic_data_; |
| 1282 | |
| 1283 | for (Input_objects::Dynobj_iterator p = input_objects->dynobj_begin(); |
| 1284 | p != input_objects->dynobj_end(); |
| 1285 | ++p) |
| 1286 | { |
| 1287 | // FIXME: Handle --as-needed. |
| 1288 | odyn->add_string(elfcpp::DT_NEEDED, (*p)->soname()); |
| 1289 | } |
| 1290 | |
| 1291 | // FIXME: Support --init and --fini. |
| 1292 | Symbol* sym = symtab->lookup("_init"); |
| 1293 | if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj()) |
| 1294 | odyn->add_symbol(elfcpp::DT_INIT, sym); |
| 1295 | |
| 1296 | sym = symtab->lookup("_fini"); |
| 1297 | if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj()) |
| 1298 | odyn->add_symbol(elfcpp::DT_FINI, sym); |
| 1299 | |
| 1300 | // FIXME: Support DT_INIT_ARRAY and DT_FINI_ARRAY. |
| 1301 | |
| 1302 | // Add a DT_RPATH entry if needed. |
| 1303 | const General_options::Dir_list& rpath(this->options_.rpath()); |
| 1304 | if (!rpath.empty()) |
| 1305 | { |
| 1306 | std::string rpath_val; |
| 1307 | for (General_options::Dir_list::const_iterator p = rpath.begin(); |
| 1308 | p != rpath.end(); |
| 1309 | ++p) |
| 1310 | { |
| 1311 | if (rpath_val.empty()) |
| 1312 | rpath_val = *p; |
| 1313 | else |
| 1314 | { |
| 1315 | // Eliminate duplicates. |
| 1316 | General_options::Dir_list::const_iterator q; |
| 1317 | for (q = rpath.begin(); q != p; ++q) |
| 1318 | if (strcmp(*q, *p) == 0) |
| 1319 | break; |
| 1320 | if (q == p) |
| 1321 | { |
| 1322 | rpath_val += ':'; |
| 1323 | rpath_val += *p; |
| 1324 | } |
| 1325 | } |
| 1326 | } |
| 1327 | |
| 1328 | odyn->add_string(elfcpp::DT_RPATH, rpath_val); |
| 1329 | } |
| 1330 | } |
| 1331 | |
| 1332 | // The mapping of .gnu.linkonce section names to real section names. |
| 1333 | |
| 1334 | #define MAPPING_INIT(f, t) { f, sizeof(f) - 1, t, sizeof(t) - 1 } |
| 1335 | const Layout::Linkonce_mapping Layout::linkonce_mapping[] = |
| 1336 | { |
| 1337 | MAPPING_INIT("d.rel.ro", ".data.rel.ro"), // Must be before "d". |
| 1338 | MAPPING_INIT("t", ".text"), |
| 1339 | MAPPING_INIT("r", ".rodata"), |
| 1340 | MAPPING_INIT("d", ".data"), |
| 1341 | MAPPING_INIT("b", ".bss"), |
| 1342 | MAPPING_INIT("s", ".sdata"), |
| 1343 | MAPPING_INIT("sb", ".sbss"), |
| 1344 | MAPPING_INIT("s2", ".sdata2"), |
| 1345 | MAPPING_INIT("sb2", ".sbss2"), |
| 1346 | MAPPING_INIT("wi", ".debug_info"), |
| 1347 | MAPPING_INIT("td", ".tdata"), |
| 1348 | MAPPING_INIT("tb", ".tbss"), |
| 1349 | MAPPING_INIT("lr", ".lrodata"), |
| 1350 | MAPPING_INIT("l", ".ldata"), |
| 1351 | MAPPING_INIT("lb", ".lbss"), |
| 1352 | }; |
| 1353 | #undef MAPPING_INIT |
| 1354 | |
| 1355 | const int Layout::linkonce_mapping_count = |
| 1356 | sizeof(Layout::linkonce_mapping) / sizeof(Layout::linkonce_mapping[0]); |
| 1357 | |
| 1358 | // Return the name of the output section to use for a .gnu.linkonce |
| 1359 | // section. This is based on the default ELF linker script of the old |
| 1360 | // GNU linker. For example, we map a name like ".gnu.linkonce.t.foo" |
| 1361 | // to ".text". Set *PLEN to the length of the name. *PLEN is |
| 1362 | // initialized to the length of NAME. |
| 1363 | |
| 1364 | const char* |
| 1365 | Layout::linkonce_output_name(const char* name, size_t *plen) |
| 1366 | { |
| 1367 | const char* s = name + sizeof(".gnu.linkonce") - 1; |
| 1368 | if (*s != '.') |
| 1369 | return name; |
| 1370 | ++s; |
| 1371 | const Linkonce_mapping* plm = linkonce_mapping; |
| 1372 | for (int i = 0; i < linkonce_mapping_count; ++i, ++plm) |
| 1373 | { |
| 1374 | if (strncmp(s, plm->from, plm->fromlen) == 0 && s[plm->fromlen] == '.') |
| 1375 | { |
| 1376 | *plen = plm->tolen; |
| 1377 | return plm->to; |
| 1378 | } |
| 1379 | } |
| 1380 | return name; |
| 1381 | } |
| 1382 | |
| 1383 | // Choose the output section name to use given an input section name. |
| 1384 | // Set *PLEN to the length of the name. *PLEN is initialized to the |
| 1385 | // length of NAME. |
| 1386 | |
| 1387 | const char* |
| 1388 | Layout::output_section_name(const char* name, size_t* plen) |
| 1389 | { |
| 1390 | if (Layout::is_linkonce(name)) |
| 1391 | { |
| 1392 | // .gnu.linkonce sections are laid out as though they were named |
| 1393 | // for the sections are placed into. |
| 1394 | return Layout::linkonce_output_name(name, plen); |
| 1395 | } |
| 1396 | |
| 1397 | // If the section name has no '.', or only an initial '.', we use |
| 1398 | // the name unchanged (i.e., ".text" is unchanged). |
| 1399 | |
| 1400 | // Otherwise, if the section name does not include ".rel", we drop |
| 1401 | // the last '.' and everything that follows (i.e., ".text.XXX" |
| 1402 | // becomes ".text"). |
| 1403 | |
| 1404 | // Otherwise, if the section name has zero or one '.' after the |
| 1405 | // ".rel", we use the name unchanged (i.e., ".rel.text" is |
| 1406 | // unchanged). |
| 1407 | |
| 1408 | // Otherwise, we drop the last '.' and everything that follows |
| 1409 | // (i.e., ".rel.text.XXX" becomes ".rel.text"). |
| 1410 | |
| 1411 | const char* s = name; |
| 1412 | if (*s == '.') |
| 1413 | ++s; |
| 1414 | const char* sdot = strchr(s, '.'); |
| 1415 | if (sdot == NULL) |
| 1416 | return name; |
| 1417 | |
| 1418 | const char* srel = strstr(s, ".rel"); |
| 1419 | if (srel == NULL) |
| 1420 | { |
| 1421 | *plen = sdot - name; |
| 1422 | return name; |
| 1423 | } |
| 1424 | |
| 1425 | sdot = strchr(srel + 1, '.'); |
| 1426 | if (sdot == NULL) |
| 1427 | return name; |
| 1428 | sdot = strchr(sdot + 1, '.'); |
| 1429 | if (sdot == NULL) |
| 1430 | return name; |
| 1431 | |
| 1432 | *plen = sdot - name; |
| 1433 | return name; |
| 1434 | } |
| 1435 | |
| 1436 | // Record the signature of a comdat section, and return whether to |
| 1437 | // include it in the link. If GROUP is true, this is a regular |
| 1438 | // section group. If GROUP is false, this is a group signature |
| 1439 | // derived from the name of a linkonce section. We want linkonce |
| 1440 | // signatures and group signatures to block each other, but we don't |
| 1441 | // want a linkonce signature to block another linkonce signature. |
| 1442 | |
| 1443 | bool |
| 1444 | Layout::add_comdat(const char* signature, bool group) |
| 1445 | { |
| 1446 | std::string sig(signature); |
| 1447 | std::pair<Signatures::iterator, bool> ins( |
| 1448 | this->signatures_.insert(std::make_pair(sig, group))); |
| 1449 | |
| 1450 | if (ins.second) |
| 1451 | { |
| 1452 | // This is the first time we've seen this signature. |
| 1453 | return true; |
| 1454 | } |
| 1455 | |
| 1456 | if (ins.first->second) |
| 1457 | { |
| 1458 | // We've already seen a real section group with this signature. |
| 1459 | return false; |
| 1460 | } |
| 1461 | else if (group) |
| 1462 | { |
| 1463 | // This is a real section group, and we've already seen a |
| 1464 | // linkonce section with this signature. Record that we've seen |
| 1465 | // a section group, and don't include this section group. |
| 1466 | ins.first->second = true; |
| 1467 | return false; |
| 1468 | } |
| 1469 | else |
| 1470 | { |
| 1471 | // We've already seen a linkonce section and this is a linkonce |
| 1472 | // section. These don't block each other--this may be the same |
| 1473 | // symbol name with different section types. |
| 1474 | return true; |
| 1475 | } |
| 1476 | } |
| 1477 | |
| 1478 | // Write out data not associated with a section or the symbol table. |
| 1479 | |
| 1480 | void |
| 1481 | Layout::write_data(const Symbol_table* symtab, Output_file* of) const |
| 1482 | { |
| 1483 | const Output_section* symtab_section = this->symtab_section_; |
| 1484 | for (Section_list::const_iterator p = this->section_list_.begin(); |
| 1485 | p != this->section_list_.end(); |
| 1486 | ++p) |
| 1487 | { |
| 1488 | if ((*p)->needs_symtab_index()) |
| 1489 | { |
| 1490 | gold_assert(symtab_section != NULL); |
| 1491 | unsigned int index = (*p)->symtab_index(); |
| 1492 | gold_assert(index > 0 && index != -1U); |
| 1493 | off_t off = (symtab_section->offset() |
| 1494 | + index * symtab_section->entsize()); |
| 1495 | symtab->write_section_symbol(*p, of, off); |
| 1496 | } |
| 1497 | } |
| 1498 | |
| 1499 | const Output_section* dynsym_section = this->dynsym_section_; |
| 1500 | for (Section_list::const_iterator p = this->section_list_.begin(); |
| 1501 | p != this->section_list_.end(); |
| 1502 | ++p) |
| 1503 | { |
| 1504 | if ((*p)->needs_dynsym_index()) |
| 1505 | { |
| 1506 | gold_assert(dynsym_section != NULL); |
| 1507 | unsigned int index = (*p)->dynsym_index(); |
| 1508 | gold_assert(index > 0 && index != -1U); |
| 1509 | off_t off = (dynsym_section->offset() |
| 1510 | + index * dynsym_section->entsize()); |
| 1511 | symtab->write_section_symbol(*p, of, off); |
| 1512 | } |
| 1513 | } |
| 1514 | |
| 1515 | // Write out the Output_sections. Most won't have anything to |
| 1516 | // write, since most of the data will come from input sections which |
| 1517 | // are handled elsewhere. But some Output_sections do have |
| 1518 | // Output_data. |
| 1519 | for (Section_list::const_iterator p = this->section_list_.begin(); |
| 1520 | p != this->section_list_.end(); |
| 1521 | ++p) |
| 1522 | (*p)->write(of); |
| 1523 | |
| 1524 | // Write out the Output_data which are not in an Output_section. |
| 1525 | for (Data_list::const_iterator p = this->special_output_list_.begin(); |
| 1526 | p != this->special_output_list_.end(); |
| 1527 | ++p) |
| 1528 | (*p)->write(of); |
| 1529 | } |
| 1530 | |
| 1531 | // Write_data_task methods. |
| 1532 | |
| 1533 | // We can always run this task. |
| 1534 | |
| 1535 | Task::Is_runnable_type |
| 1536 | Write_data_task::is_runnable(Workqueue*) |
| 1537 | { |
| 1538 | return IS_RUNNABLE; |
| 1539 | } |
| 1540 | |
| 1541 | // We need to unlock FINAL_BLOCKER when finished. |
| 1542 | |
| 1543 | Task_locker* |
| 1544 | Write_data_task::locks(Workqueue* workqueue) |
| 1545 | { |
| 1546 | return new Task_locker_block(*this->final_blocker_, workqueue); |
| 1547 | } |
| 1548 | |
| 1549 | // Run the task--write out the data. |
| 1550 | |
| 1551 | void |
| 1552 | Write_data_task::run(Workqueue*) |
| 1553 | { |
| 1554 | this->layout_->write_data(this->symtab_, this->of_); |
| 1555 | } |
| 1556 | |
| 1557 | // Write_symbols_task methods. |
| 1558 | |
| 1559 | // We can always run this task. |
| 1560 | |
| 1561 | Task::Is_runnable_type |
| 1562 | Write_symbols_task::is_runnable(Workqueue*) |
| 1563 | { |
| 1564 | return IS_RUNNABLE; |
| 1565 | } |
| 1566 | |
| 1567 | // We need to unlock FINAL_BLOCKER when finished. |
| 1568 | |
| 1569 | Task_locker* |
| 1570 | Write_symbols_task::locks(Workqueue* workqueue) |
| 1571 | { |
| 1572 | return new Task_locker_block(*this->final_blocker_, workqueue); |
| 1573 | } |
| 1574 | |
| 1575 | // Run the task--write out the symbols. |
| 1576 | |
| 1577 | void |
| 1578 | Write_symbols_task::run(Workqueue*) |
| 1579 | { |
| 1580 | this->symtab_->write_globals(this->target_, this->sympool_, this->dynpool_, |
| 1581 | this->of_); |
| 1582 | } |
| 1583 | |
| 1584 | // Close_task_runner methods. |
| 1585 | |
| 1586 | // Run the task--close the file. |
| 1587 | |
| 1588 | void |
| 1589 | Close_task_runner::run(Workqueue*) |
| 1590 | { |
| 1591 | this->of_->close(); |
| 1592 | } |
| 1593 | |
| 1594 | // Instantiate the templates we need. We could use the configure |
| 1595 | // script to restrict this to only the ones for implemented targets. |
| 1596 | |
| 1597 | #ifdef HAVE_TARGET_32_LITTLE |
| 1598 | template |
| 1599 | Output_section* |
| 1600 | Layout::layout<32, false>(Relobj* object, unsigned int shndx, const char* name, |
| 1601 | const elfcpp::Shdr<32, false>& shdr, off_t*); |
| 1602 | #endif |
| 1603 | |
| 1604 | #ifdef HAVE_TARGET_32_BIG |
| 1605 | template |
| 1606 | Output_section* |
| 1607 | Layout::layout<32, true>(Relobj* object, unsigned int shndx, const char* name, |
| 1608 | const elfcpp::Shdr<32, true>& shdr, off_t*); |
| 1609 | #endif |
| 1610 | |
| 1611 | #ifdef HAVE_TARGET_64_LITTLE |
| 1612 | template |
| 1613 | Output_section* |
| 1614 | Layout::layout<64, false>(Relobj* object, unsigned int shndx, const char* name, |
| 1615 | const elfcpp::Shdr<64, false>& shdr, off_t*); |
| 1616 | #endif |
| 1617 | |
| 1618 | #ifdef HAVE_TARGET_64_BIG |
| 1619 | template |
| 1620 | Output_section* |
| 1621 | Layout::layout<64, true>(Relobj* object, unsigned int shndx, const char* name, |
| 1622 | const elfcpp::Shdr<64, true>& shdr, off_t*); |
| 1623 | #endif |
| 1624 | |
| 1625 | |
| 1626 | } // End namespace gold. |