| 1 | // symtab.h -- the gold symbol table -*- C++ -*- |
| 2 | |
| 3 | // Copyright 2006, 2007, 2008 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 | // Symbol_table |
| 24 | // The symbol table. |
| 25 | |
| 26 | #include <string> |
| 27 | #include <utility> |
| 28 | #include <vector> |
| 29 | |
| 30 | #include "elfcpp.h" |
| 31 | #include "parameters.h" |
| 32 | #include "stringpool.h" |
| 33 | #include "object.h" |
| 34 | |
| 35 | #ifndef GOLD_SYMTAB_H |
| 36 | #define GOLD_SYMTAB_H |
| 37 | |
| 38 | namespace gold |
| 39 | { |
| 40 | |
| 41 | class Mapfile; |
| 42 | class Object; |
| 43 | class Relobj; |
| 44 | template<int size, bool big_endian> |
| 45 | class Sized_relobj; |
| 46 | template<int size, bool big_endian> |
| 47 | class Sized_pluginobj; |
| 48 | class Dynobj; |
| 49 | template<int size, bool big_endian> |
| 50 | class Sized_dynobj; |
| 51 | class Versions; |
| 52 | class Version_script_info; |
| 53 | class Input_objects; |
| 54 | class Output_data; |
| 55 | class Output_section; |
| 56 | class Output_segment; |
| 57 | class Output_file; |
| 58 | class Output_symtab_xindex; |
| 59 | |
| 60 | // The base class of an entry in the symbol table. The symbol table |
| 61 | // can have a lot of entries, so we don't want this class to big. |
| 62 | // Size dependent fields can be found in the template class |
| 63 | // Sized_symbol. Targets may support their own derived classes. |
| 64 | |
| 65 | class Symbol |
| 66 | { |
| 67 | public: |
| 68 | // Because we want the class to be small, we don't use any virtual |
| 69 | // functions. But because symbols can be defined in different |
| 70 | // places, we need to classify them. This enum is the different |
| 71 | // sources of symbols we support. |
| 72 | enum Source |
| 73 | { |
| 74 | // Symbol defined in a relocatable or dynamic input file--this is |
| 75 | // the most common case. |
| 76 | FROM_OBJECT, |
| 77 | // Symbol defined in an Output_data, a special section created by |
| 78 | // the target. |
| 79 | IN_OUTPUT_DATA, |
| 80 | // Symbol defined in an Output_segment, with no associated |
| 81 | // section. |
| 82 | IN_OUTPUT_SEGMENT, |
| 83 | // Symbol value is constant. |
| 84 | IS_CONSTANT, |
| 85 | // Symbol is undefined. |
| 86 | IS_UNDEFINED |
| 87 | }; |
| 88 | |
| 89 | // When the source is IN_OUTPUT_SEGMENT, we need to describe what |
| 90 | // the offset means. |
| 91 | enum Segment_offset_base |
| 92 | { |
| 93 | // From the start of the segment. |
| 94 | SEGMENT_START, |
| 95 | // From the end of the segment. |
| 96 | SEGMENT_END, |
| 97 | // From the filesz of the segment--i.e., after the loaded bytes |
| 98 | // but before the bytes which are allocated but zeroed. |
| 99 | SEGMENT_BSS |
| 100 | }; |
| 101 | |
| 102 | // Return the symbol name. |
| 103 | const char* |
| 104 | name() const |
| 105 | { return this->name_; } |
| 106 | |
| 107 | // Return the (ANSI) demangled version of the name, if |
| 108 | // parameters.demangle() is true. Otherwise, return the name. This |
| 109 | // is intended to be used only for logging errors, so it's not |
| 110 | // super-efficient. |
| 111 | std::string |
| 112 | demangled_name() const; |
| 113 | |
| 114 | // Return the symbol version. This will return NULL for an |
| 115 | // unversioned symbol. |
| 116 | const char* |
| 117 | version() const |
| 118 | { return this->version_; } |
| 119 | |
| 120 | // Return whether this version is the default for this symbol name |
| 121 | // (eg, "foo@@V2" is a default version; "foo@V1" is not). Only |
| 122 | // meaningful for versioned symbols. |
| 123 | bool |
| 124 | is_default() const |
| 125 | { |
| 126 | gold_assert(this->version_ != NULL); |
| 127 | return this->is_def_; |
| 128 | } |
| 129 | |
| 130 | // Set that this version is the default for this symbol name. |
| 131 | void |
| 132 | set_is_default() |
| 133 | { this->is_def_ = true; } |
| 134 | |
| 135 | // Return the symbol source. |
| 136 | Source |
| 137 | source() const |
| 138 | { return this->source_; } |
| 139 | |
| 140 | // Return the object with which this symbol is associated. |
| 141 | Object* |
| 142 | object() const |
| 143 | { |
| 144 | gold_assert(this->source_ == FROM_OBJECT); |
| 145 | return this->u_.from_object.object; |
| 146 | } |
| 147 | |
| 148 | // Return the index of the section in the input relocatable or |
| 149 | // dynamic object file. |
| 150 | unsigned int |
| 151 | shndx(bool* is_ordinary) const |
| 152 | { |
| 153 | gold_assert(this->source_ == FROM_OBJECT); |
| 154 | *is_ordinary = this->is_ordinary_shndx_; |
| 155 | return this->u_.from_object.shndx; |
| 156 | } |
| 157 | |
| 158 | // Return the output data section with which this symbol is |
| 159 | // associated, if the symbol was specially defined with respect to |
| 160 | // an output data section. |
| 161 | Output_data* |
| 162 | output_data() const |
| 163 | { |
| 164 | gold_assert(this->source_ == IN_OUTPUT_DATA); |
| 165 | return this->u_.in_output_data.output_data; |
| 166 | } |
| 167 | |
| 168 | // If this symbol was defined with respect to an output data |
| 169 | // section, return whether the value is an offset from end. |
| 170 | bool |
| 171 | offset_is_from_end() const |
| 172 | { |
| 173 | gold_assert(this->source_ == IN_OUTPUT_DATA); |
| 174 | return this->u_.in_output_data.offset_is_from_end; |
| 175 | } |
| 176 | |
| 177 | // Return the output segment with which this symbol is associated, |
| 178 | // if the symbol was specially defined with respect to an output |
| 179 | // segment. |
| 180 | Output_segment* |
| 181 | output_segment() const |
| 182 | { |
| 183 | gold_assert(this->source_ == IN_OUTPUT_SEGMENT); |
| 184 | return this->u_.in_output_segment.output_segment; |
| 185 | } |
| 186 | |
| 187 | // If this symbol was defined with respect to an output segment, |
| 188 | // return the offset base. |
| 189 | Segment_offset_base |
| 190 | offset_base() const |
| 191 | { |
| 192 | gold_assert(this->source_ == IN_OUTPUT_SEGMENT); |
| 193 | return this->u_.in_output_segment.offset_base; |
| 194 | } |
| 195 | |
| 196 | // Return the symbol binding. |
| 197 | elfcpp::STB |
| 198 | binding() const |
| 199 | { return this->binding_; } |
| 200 | |
| 201 | // Return the symbol type. |
| 202 | elfcpp::STT |
| 203 | type() const |
| 204 | { return this->type_; } |
| 205 | |
| 206 | // Return the symbol visibility. |
| 207 | elfcpp::STV |
| 208 | visibility() const |
| 209 | { return this->visibility_; } |
| 210 | |
| 211 | // Return the non-visibility part of the st_other field. |
| 212 | unsigned char |
| 213 | nonvis() const |
| 214 | { return this->nonvis_; } |
| 215 | |
| 216 | // Return whether this symbol is a forwarder. This will never be |
| 217 | // true of a symbol found in the hash table, but may be true of |
| 218 | // symbol pointers attached to object files. |
| 219 | bool |
| 220 | is_forwarder() const |
| 221 | { return this->is_forwarder_; } |
| 222 | |
| 223 | // Mark this symbol as a forwarder. |
| 224 | void |
| 225 | set_forwarder() |
| 226 | { this->is_forwarder_ = true; } |
| 227 | |
| 228 | // Return whether this symbol has an alias in the weak aliases table |
| 229 | // in Symbol_table. |
| 230 | bool |
| 231 | has_alias() const |
| 232 | { return this->has_alias_; } |
| 233 | |
| 234 | // Mark this symbol as having an alias. |
| 235 | void |
| 236 | set_has_alias() |
| 237 | { this->has_alias_ = true; } |
| 238 | |
| 239 | // Return whether this symbol needs an entry in the dynamic symbol |
| 240 | // table. |
| 241 | bool |
| 242 | needs_dynsym_entry() const |
| 243 | { |
| 244 | return (this->needs_dynsym_entry_ |
| 245 | || (this->in_reg() && this->in_dyn())); |
| 246 | } |
| 247 | |
| 248 | // Mark this symbol as needing an entry in the dynamic symbol table. |
| 249 | void |
| 250 | set_needs_dynsym_entry() |
| 251 | { this->needs_dynsym_entry_ = true; } |
| 252 | |
| 253 | // Return whether this symbol should be added to the dynamic symbol |
| 254 | // table. |
| 255 | bool |
| 256 | should_add_dynsym_entry() const; |
| 257 | |
| 258 | // Return whether this symbol has been seen in a regular object. |
| 259 | bool |
| 260 | in_reg() const |
| 261 | { return this->in_reg_; } |
| 262 | |
| 263 | // Mark this symbol as having been seen in a regular object. |
| 264 | void |
| 265 | set_in_reg() |
| 266 | { this->in_reg_ = true; } |
| 267 | |
| 268 | // Return whether this symbol has been seen in a dynamic object. |
| 269 | bool |
| 270 | in_dyn() const |
| 271 | { return this->in_dyn_; } |
| 272 | |
| 273 | // Mark this symbol as having been seen in a dynamic object. |
| 274 | void |
| 275 | set_in_dyn() |
| 276 | { this->in_dyn_ = true; } |
| 277 | |
| 278 | // Return whether this symbol has been seen in a real ELF object. |
| 279 | // (IN_REG will return TRUE if the symbol has been seen in either |
| 280 | // a real ELF object or an object claimed by a plugin.) |
| 281 | bool |
| 282 | in_real_elf() const |
| 283 | { return this->in_real_elf_; } |
| 284 | |
| 285 | // Mark this symbol as having been seen in a real ELF object. |
| 286 | void |
| 287 | set_in_real_elf() |
| 288 | { this->in_real_elf_ = true; } |
| 289 | |
| 290 | // Return the index of this symbol in the output file symbol table. |
| 291 | // A value of -1U means that this symbol is not going into the |
| 292 | // output file. This starts out as zero, and is set to a non-zero |
| 293 | // value by Symbol_table::finalize. It is an error to ask for the |
| 294 | // symbol table index before it has been set. |
| 295 | unsigned int |
| 296 | symtab_index() const |
| 297 | { |
| 298 | gold_assert(this->symtab_index_ != 0); |
| 299 | return this->symtab_index_; |
| 300 | } |
| 301 | |
| 302 | // Set the index of the symbol in the output file symbol table. |
| 303 | void |
| 304 | set_symtab_index(unsigned int index) |
| 305 | { |
| 306 | gold_assert(index != 0); |
| 307 | this->symtab_index_ = index; |
| 308 | } |
| 309 | |
| 310 | // Return whether this symbol already has an index in the output |
| 311 | // file symbol table. |
| 312 | bool |
| 313 | has_symtab_index() const |
| 314 | { return this->symtab_index_ != 0; } |
| 315 | |
| 316 | // Return the index of this symbol in the dynamic symbol table. A |
| 317 | // value of -1U means that this symbol is not going into the dynamic |
| 318 | // symbol table. This starts out as zero, and is set to a non-zero |
| 319 | // during Layout::finalize. It is an error to ask for the dynamic |
| 320 | // symbol table index before it has been set. |
| 321 | unsigned int |
| 322 | dynsym_index() const |
| 323 | { |
| 324 | gold_assert(this->dynsym_index_ != 0); |
| 325 | return this->dynsym_index_; |
| 326 | } |
| 327 | |
| 328 | // Set the index of the symbol in the dynamic symbol table. |
| 329 | void |
| 330 | set_dynsym_index(unsigned int index) |
| 331 | { |
| 332 | gold_assert(index != 0); |
| 333 | this->dynsym_index_ = index; |
| 334 | } |
| 335 | |
| 336 | // Return whether this symbol already has an index in the dynamic |
| 337 | // symbol table. |
| 338 | bool |
| 339 | has_dynsym_index() const |
| 340 | { return this->dynsym_index_ != 0; } |
| 341 | |
| 342 | // Return whether this symbol has an entry in the GOT section. |
| 343 | // For a TLS symbol, this GOT entry will hold its tp-relative offset. |
| 344 | bool |
| 345 | has_got_offset(unsigned int got_type) const |
| 346 | { return this->got_offsets_.get_offset(got_type) != -1U; } |
| 347 | |
| 348 | // Return the offset into the GOT section of this symbol. |
| 349 | unsigned int |
| 350 | got_offset(unsigned int got_type) const |
| 351 | { |
| 352 | unsigned int got_offset = this->got_offsets_.get_offset(got_type); |
| 353 | gold_assert(got_offset != -1U); |
| 354 | return got_offset; |
| 355 | } |
| 356 | |
| 357 | // Set the GOT offset of this symbol. |
| 358 | void |
| 359 | set_got_offset(unsigned int got_type, unsigned int got_offset) |
| 360 | { this->got_offsets_.set_offset(got_type, got_offset); } |
| 361 | |
| 362 | // Return whether this symbol has an entry in the PLT section. |
| 363 | bool |
| 364 | has_plt_offset() const |
| 365 | { return this->has_plt_offset_; } |
| 366 | |
| 367 | // Return the offset into the PLT section of this symbol. |
| 368 | unsigned int |
| 369 | plt_offset() const |
| 370 | { |
| 371 | gold_assert(this->has_plt_offset()); |
| 372 | return this->plt_offset_; |
| 373 | } |
| 374 | |
| 375 | // Set the PLT offset of this symbol. |
| 376 | void |
| 377 | set_plt_offset(unsigned int plt_offset) |
| 378 | { |
| 379 | this->has_plt_offset_ = true; |
| 380 | this->plt_offset_ = plt_offset; |
| 381 | } |
| 382 | |
| 383 | // Return whether this dynamic symbol needs a special value in the |
| 384 | // dynamic symbol table. |
| 385 | bool |
| 386 | needs_dynsym_value() const |
| 387 | { return this->needs_dynsym_value_; } |
| 388 | |
| 389 | // Set that this dynamic symbol needs a special value in the dynamic |
| 390 | // symbol table. |
| 391 | void |
| 392 | set_needs_dynsym_value() |
| 393 | { |
| 394 | gold_assert(this->object()->is_dynamic()); |
| 395 | this->needs_dynsym_value_ = true; |
| 396 | } |
| 397 | |
| 398 | // Return true if the final value of this symbol is known at link |
| 399 | // time. |
| 400 | bool |
| 401 | final_value_is_known() const; |
| 402 | |
| 403 | // Return whether this is a defined symbol (not undefined or |
| 404 | // common). |
| 405 | bool |
| 406 | is_defined() const |
| 407 | { |
| 408 | bool is_ordinary; |
| 409 | if (this->source_ != FROM_OBJECT) |
| 410 | return this->source_ != IS_UNDEFINED; |
| 411 | unsigned int shndx = this->shndx(&is_ordinary); |
| 412 | return (is_ordinary |
| 413 | ? shndx != elfcpp::SHN_UNDEF |
| 414 | : shndx != elfcpp::SHN_COMMON); |
| 415 | } |
| 416 | |
| 417 | // Return true if this symbol is from a dynamic object. |
| 418 | bool |
| 419 | is_from_dynobj() const |
| 420 | { |
| 421 | return this->source_ == FROM_OBJECT && this->object()->is_dynamic(); |
| 422 | } |
| 423 | |
| 424 | // Return whether this is an undefined symbol. |
| 425 | bool |
| 426 | is_undefined() const |
| 427 | { |
| 428 | bool is_ordinary; |
| 429 | return ((this->source_ == FROM_OBJECT |
| 430 | && this->shndx(&is_ordinary) == elfcpp::SHN_UNDEF |
| 431 | && is_ordinary) |
| 432 | || this->source_ == IS_UNDEFINED); |
| 433 | } |
| 434 | |
| 435 | // Return whether this is a weak undefined symbol. |
| 436 | bool |
| 437 | is_weak_undefined() const |
| 438 | { return this->is_undefined() && this->binding() == elfcpp::STB_WEAK; } |
| 439 | |
| 440 | // Return whether this is an absolute symbol. |
| 441 | bool |
| 442 | is_absolute() const |
| 443 | { |
| 444 | bool is_ordinary; |
| 445 | return ((this->source_ == FROM_OBJECT |
| 446 | && this->shndx(&is_ordinary) == elfcpp::SHN_ABS |
| 447 | && !is_ordinary) |
| 448 | || this->source_ == IS_CONSTANT); |
| 449 | } |
| 450 | |
| 451 | // Return whether this is a common symbol. |
| 452 | bool |
| 453 | is_common() const |
| 454 | { |
| 455 | bool is_ordinary; |
| 456 | return (this->source_ == FROM_OBJECT |
| 457 | && ((this->shndx(&is_ordinary) == elfcpp::SHN_COMMON |
| 458 | && !is_ordinary) |
| 459 | || this->type_ == elfcpp::STT_COMMON)); |
| 460 | } |
| 461 | |
| 462 | // Return whether this symbol can be seen outside this object. |
| 463 | bool |
| 464 | is_externally_visible() const |
| 465 | { |
| 466 | return (this->visibility_ == elfcpp::STV_DEFAULT |
| 467 | || this->visibility_ == elfcpp::STV_PROTECTED); |
| 468 | } |
| 469 | |
| 470 | // Return true if this symbol can be preempted by a definition in |
| 471 | // another link unit. |
| 472 | bool |
| 473 | is_preemptible() const |
| 474 | { |
| 475 | // It doesn't make sense to ask whether a symbol defined in |
| 476 | // another object is preemptible. |
| 477 | gold_assert(!this->is_from_dynobj()); |
| 478 | |
| 479 | // It doesn't make sense to ask whether an undefined symbol |
| 480 | // is preemptible. |
| 481 | gold_assert(!this->is_undefined()); |
| 482 | |
| 483 | // If a symbol does not have default visibility, it can not be |
| 484 | // seen outside this link unit and therefore is not preemptible. |
| 485 | if (this->visibility_ != elfcpp::STV_DEFAULT) |
| 486 | return false; |
| 487 | |
| 488 | // If this symbol has been forced to be a local symbol by a |
| 489 | // version script, then it is not visible outside this link unit |
| 490 | // and is not preemptible. |
| 491 | if (this->is_forced_local_) |
| 492 | return false; |
| 493 | |
| 494 | // If we are not producing a shared library, then nothing is |
| 495 | // preemptible. |
| 496 | if (!parameters->options().shared()) |
| 497 | return false; |
| 498 | |
| 499 | // If the user used -Bsymbolic, then nothing is preemptible. |
| 500 | if (parameters->options().Bsymbolic()) |
| 501 | return false; |
| 502 | |
| 503 | // If the user used -Bsymbolic-functions, then functions are not |
| 504 | // preemptible. We explicitly check for not being STT_OBJECT, |
| 505 | // rather than for being STT_FUNC, because that is what the GNU |
| 506 | // linker does. |
| 507 | if (this->type() != elfcpp::STT_OBJECT |
| 508 | && parameters->options().Bsymbolic_functions()) |
| 509 | return false; |
| 510 | |
| 511 | // Otherwise the symbol is preemptible. |
| 512 | return true; |
| 513 | } |
| 514 | |
| 515 | // Return true if this symbol is a function that needs a PLT entry. |
| 516 | // If the symbol is defined in a dynamic object or if it is subject |
| 517 | // to pre-emption, we need to make a PLT entry. If we're doing a |
| 518 | // static link, we don't create PLT entries. |
| 519 | bool |
| 520 | needs_plt_entry() const |
| 521 | { |
| 522 | return (!parameters->doing_static_link() |
| 523 | && this->type() == elfcpp::STT_FUNC |
| 524 | && (this->is_from_dynobj() |
| 525 | || this->is_undefined() |
| 526 | || this->is_preemptible())); |
| 527 | } |
| 528 | |
| 529 | // When determining whether a reference to a symbol needs a dynamic |
| 530 | // relocation, we need to know several things about the reference. |
| 531 | // These flags may be or'ed together. |
| 532 | enum Reference_flags |
| 533 | { |
| 534 | // Reference to the symbol's absolute address. |
| 535 | ABSOLUTE_REF = 1, |
| 536 | // A non-PIC reference. |
| 537 | NON_PIC_REF = 2, |
| 538 | // A function call. |
| 539 | FUNCTION_CALL = 4 |
| 540 | }; |
| 541 | |
| 542 | // Given a direct absolute or pc-relative static relocation against |
| 543 | // the global symbol, this function returns whether a dynamic relocation |
| 544 | // is needed. |
| 545 | |
| 546 | bool |
| 547 | needs_dynamic_reloc(int flags) const |
| 548 | { |
| 549 | // No dynamic relocations in a static link! |
| 550 | if (parameters->doing_static_link()) |
| 551 | return false; |
| 552 | |
| 553 | // A reference to a weak undefined symbol from an executable should be |
| 554 | // statically resolved to 0, and does not need a dynamic relocation. |
| 555 | // This matches gnu ld behavior. |
| 556 | if (this->is_weak_undefined() && !parameters->options().shared()) |
| 557 | return false; |
| 558 | |
| 559 | // A reference to an absolute symbol does not need a dynamic relocation. |
| 560 | if (this->is_absolute()) |
| 561 | return false; |
| 562 | |
| 563 | // An absolute reference within a position-independent output file |
| 564 | // will need a dynamic relocation. |
| 565 | if ((flags & ABSOLUTE_REF) |
| 566 | && parameters->options().output_is_position_independent()) |
| 567 | return true; |
| 568 | |
| 569 | // A function call that can branch to a local PLT entry does not need |
| 570 | // a dynamic relocation. A non-pic pc-relative function call in a |
| 571 | // shared library cannot use a PLT entry. |
| 572 | if ((flags & FUNCTION_CALL) |
| 573 | && this->has_plt_offset() |
| 574 | && !((flags & NON_PIC_REF) && parameters->options().shared())) |
| 575 | return false; |
| 576 | |
| 577 | // A reference to any PLT entry in a non-position-independent executable |
| 578 | // does not need a dynamic relocation. |
| 579 | if (!parameters->options().output_is_position_independent() |
| 580 | && this->has_plt_offset()) |
| 581 | return false; |
| 582 | |
| 583 | // A reference to a symbol defined in a dynamic object or to a |
| 584 | // symbol that is preemptible will need a dynamic relocation. |
| 585 | if (this->is_from_dynobj() |
| 586 | || this->is_undefined() |
| 587 | || this->is_preemptible()) |
| 588 | return true; |
| 589 | |
| 590 | // For all other cases, return FALSE. |
| 591 | return false; |
| 592 | } |
| 593 | |
| 594 | // Whether we should use the PLT offset associated with a symbol for |
| 595 | // a relocation. IS_NON_PIC_REFERENCE is true if this is a non-PIC |
| 596 | // reloc--the same set of relocs for which we would pass NON_PIC_REF |
| 597 | // to the needs_dynamic_reloc function. |
| 598 | |
| 599 | bool |
| 600 | use_plt_offset(bool is_non_pic_reference) const |
| 601 | { |
| 602 | // If the symbol doesn't have a PLT offset, then naturally we |
| 603 | // don't want to use it. |
| 604 | if (!this->has_plt_offset()) |
| 605 | return false; |
| 606 | |
| 607 | // If we are going to generate a dynamic relocation, then we will |
| 608 | // wind up using that, so no need to use the PLT entry. |
| 609 | if (this->needs_dynamic_reloc(FUNCTION_CALL |
| 610 | | (is_non_pic_reference |
| 611 | ? NON_PIC_REF |
| 612 | : 0))) |
| 613 | return false; |
| 614 | |
| 615 | // If the symbol is from a dynamic object, we need to use the PLT |
| 616 | // entry. |
| 617 | if (this->is_from_dynobj()) |
| 618 | return true; |
| 619 | |
| 620 | // If we are generating a shared object, and this symbol is |
| 621 | // undefined or preemptible, we need to use the PLT entry. |
| 622 | if (parameters->options().shared() |
| 623 | && (this->is_undefined() || this->is_preemptible())) |
| 624 | return true; |
| 625 | |
| 626 | // If this is a weak undefined symbol, we need to use the PLT |
| 627 | // entry; the symbol may be defined by a library loaded at |
| 628 | // runtime. |
| 629 | if (this->is_weak_undefined()) |
| 630 | return true; |
| 631 | |
| 632 | // Otherwise we can use the regular definition. |
| 633 | return false; |
| 634 | } |
| 635 | |
| 636 | // Given a direct absolute static relocation against |
| 637 | // the global symbol, where a dynamic relocation is needed, this |
| 638 | // function returns whether a relative dynamic relocation can be used. |
| 639 | // The caller must determine separately whether the static relocation |
| 640 | // is compatible with a relative relocation. |
| 641 | |
| 642 | bool |
| 643 | can_use_relative_reloc(bool is_function_call) const |
| 644 | { |
| 645 | // A function call that can branch to a local PLT entry can |
| 646 | // use a RELATIVE relocation. |
| 647 | if (is_function_call && this->has_plt_offset()) |
| 648 | return true; |
| 649 | |
| 650 | // A reference to a symbol defined in a dynamic object or to a |
| 651 | // symbol that is preemptible can not use a RELATIVE relocaiton. |
| 652 | if (this->is_from_dynobj() |
| 653 | || this->is_undefined() |
| 654 | || this->is_preemptible()) |
| 655 | return false; |
| 656 | |
| 657 | // For all other cases, return TRUE. |
| 658 | return true; |
| 659 | } |
| 660 | |
| 661 | // Return the output section where this symbol is defined. Return |
| 662 | // NULL if the symbol has an absolute value. |
| 663 | Output_section* |
| 664 | output_section() const; |
| 665 | |
| 666 | // Set the symbol's output section. This is used for symbols |
| 667 | // defined in scripts. This should only be called after the symbol |
| 668 | // table has been finalized. |
| 669 | void |
| 670 | set_output_section(Output_section*); |
| 671 | |
| 672 | // Return whether there should be a warning for references to this |
| 673 | // symbol. |
| 674 | bool |
| 675 | has_warning() const |
| 676 | { return this->has_warning_; } |
| 677 | |
| 678 | // Mark this symbol as having a warning. |
| 679 | void |
| 680 | set_has_warning() |
| 681 | { this->has_warning_ = true; } |
| 682 | |
| 683 | // Return whether this symbol is defined by a COPY reloc from a |
| 684 | // dynamic object. |
| 685 | bool |
| 686 | is_copied_from_dynobj() const |
| 687 | { return this->is_copied_from_dynobj_; } |
| 688 | |
| 689 | // Mark this symbol as defined by a COPY reloc. |
| 690 | void |
| 691 | set_is_copied_from_dynobj() |
| 692 | { this->is_copied_from_dynobj_ = true; } |
| 693 | |
| 694 | // Return whether this symbol is forced to visibility STB_LOCAL |
| 695 | // by a "local:" entry in a version script. |
| 696 | bool |
| 697 | is_forced_local() const |
| 698 | { return this->is_forced_local_; } |
| 699 | |
| 700 | // Mark this symbol as forced to STB_LOCAL visibility. |
| 701 | void |
| 702 | set_is_forced_local() |
| 703 | { this->is_forced_local_ = true; } |
| 704 | |
| 705 | protected: |
| 706 | // Instances of this class should always be created at a specific |
| 707 | // size. |
| 708 | Symbol() |
| 709 | { memset(this, 0, sizeof *this); } |
| 710 | |
| 711 | // Initialize the general fields. |
| 712 | void |
| 713 | init_fields(const char* name, const char* version, |
| 714 | elfcpp::STT type, elfcpp::STB binding, |
| 715 | elfcpp::STV visibility, unsigned char nonvis); |
| 716 | |
| 717 | // Initialize fields from an ELF symbol in OBJECT. ST_SHNDX is the |
| 718 | // section index, IS_ORDINARY is whether it is a normal section |
| 719 | // index rather than a special code. |
| 720 | template<int size, bool big_endian> |
| 721 | void |
| 722 | init_base_object(const char *name, const char* version, Object* object, |
| 723 | const elfcpp::Sym<size, big_endian>&, unsigned int st_shndx, |
| 724 | bool is_ordinary); |
| 725 | |
| 726 | // Initialize fields for an Output_data. |
| 727 | void |
| 728 | init_base_output_data(const char* name, const char* version, Output_data*, |
| 729 | elfcpp::STT, elfcpp::STB, elfcpp::STV, |
| 730 | unsigned char nonvis, bool offset_is_from_end); |
| 731 | |
| 732 | // Initialize fields for an Output_segment. |
| 733 | void |
| 734 | init_base_output_segment(const char* name, const char* version, |
| 735 | Output_segment* os, elfcpp::STT type, |
| 736 | elfcpp::STB binding, elfcpp::STV visibility, |
| 737 | unsigned char nonvis, |
| 738 | Segment_offset_base offset_base); |
| 739 | |
| 740 | // Initialize fields for a constant. |
| 741 | void |
| 742 | init_base_constant(const char* name, const char* version, elfcpp::STT type, |
| 743 | elfcpp::STB binding, elfcpp::STV visibility, |
| 744 | unsigned char nonvis); |
| 745 | |
| 746 | // Initialize fields for an undefined symbol. |
| 747 | void |
| 748 | init_base_undefined(const char* name, const char* version, elfcpp::STT type, |
| 749 | elfcpp::STB binding, elfcpp::STV visibility, |
| 750 | unsigned char nonvis); |
| 751 | |
| 752 | // Override existing symbol. |
| 753 | template<int size, bool big_endian> |
| 754 | void |
| 755 | override_base(const elfcpp::Sym<size, big_endian>&, unsigned int st_shndx, |
| 756 | bool is_ordinary, Object* object, const char* version); |
| 757 | |
| 758 | // Override existing symbol with a special symbol. |
| 759 | void |
| 760 | override_base_with_special(const Symbol* from); |
| 761 | |
| 762 | // Override symbol version. |
| 763 | void |
| 764 | override_version(const char* version); |
| 765 | |
| 766 | // Allocate a common symbol by giving it a location in the output |
| 767 | // file. |
| 768 | void |
| 769 | allocate_base_common(Output_data*); |
| 770 | |
| 771 | private: |
| 772 | Symbol(const Symbol&); |
| 773 | Symbol& operator=(const Symbol&); |
| 774 | |
| 775 | // Symbol name (expected to point into a Stringpool). |
| 776 | const char* name_; |
| 777 | // Symbol version (expected to point into a Stringpool). This may |
| 778 | // be NULL. |
| 779 | const char* version_; |
| 780 | |
| 781 | union |
| 782 | { |
| 783 | // This struct is used if SOURCE_ == FROM_OBJECT. |
| 784 | struct |
| 785 | { |
| 786 | // Object in which symbol is defined, or in which it was first |
| 787 | // seen. |
| 788 | Object* object; |
| 789 | // Section number in object_ in which symbol is defined. |
| 790 | unsigned int shndx; |
| 791 | } from_object; |
| 792 | |
| 793 | // This struct is used if SOURCE_ == IN_OUTPUT_DATA. |
| 794 | struct |
| 795 | { |
| 796 | // Output_data in which symbol is defined. Before |
| 797 | // Layout::finalize the symbol's value is an offset within the |
| 798 | // Output_data. |
| 799 | Output_data* output_data; |
| 800 | // True if the offset is from the end, false if the offset is |
| 801 | // from the beginning. |
| 802 | bool offset_is_from_end; |
| 803 | } in_output_data; |
| 804 | |
| 805 | // This struct is used if SOURCE_ == IN_OUTPUT_SEGMENT. |
| 806 | struct |
| 807 | { |
| 808 | // Output_segment in which the symbol is defined. Before |
| 809 | // Layout::finalize the symbol's value is an offset. |
| 810 | Output_segment* output_segment; |
| 811 | // The base to use for the offset before Layout::finalize. |
| 812 | Segment_offset_base offset_base; |
| 813 | } in_output_segment; |
| 814 | } u_; |
| 815 | |
| 816 | // The index of this symbol in the output file. If the symbol is |
| 817 | // not going into the output file, this value is -1U. This field |
| 818 | // starts as always holding zero. It is set to a non-zero value by |
| 819 | // Symbol_table::finalize. |
| 820 | unsigned int symtab_index_; |
| 821 | |
| 822 | // The index of this symbol in the dynamic symbol table. If the |
| 823 | // symbol is not going into the dynamic symbol table, this value is |
| 824 | // -1U. This field starts as always holding zero. It is set to a |
| 825 | // non-zero value during Layout::finalize. |
| 826 | unsigned int dynsym_index_; |
| 827 | |
| 828 | // If this symbol has an entry in the GOT section (has_got_offset_ |
| 829 | // is true), this holds the offset from the start of the GOT section. |
| 830 | // A symbol may have more than one GOT offset (e.g., when mixing |
| 831 | // modules compiled with two different TLS models), but will usually |
| 832 | // have at most one. |
| 833 | Got_offset_list got_offsets_; |
| 834 | |
| 835 | // If this symbol has an entry in the PLT section (has_plt_offset_ |
| 836 | // is true), then this is the offset from the start of the PLT |
| 837 | // section. |
| 838 | unsigned int plt_offset_; |
| 839 | |
| 840 | // Symbol type (bits 0 to 3). |
| 841 | elfcpp::STT type_ : 4; |
| 842 | // Symbol binding (bits 4 to 7). |
| 843 | elfcpp::STB binding_ : 4; |
| 844 | // Symbol visibility (bits 8 to 9). |
| 845 | elfcpp::STV visibility_ : 2; |
| 846 | // Rest of symbol st_other field (bits 10 to 15). |
| 847 | unsigned int nonvis_ : 6; |
| 848 | // The type of symbol (bits 16 to 18). |
| 849 | Source source_ : 3; |
| 850 | // True if this symbol always requires special target-specific |
| 851 | // handling (bit 19). |
| 852 | bool is_target_special_ : 1; |
| 853 | // True if this is the default version of the symbol (bit 20). |
| 854 | bool is_def_ : 1; |
| 855 | // True if this symbol really forwards to another symbol. This is |
| 856 | // used when we discover after the fact that two different entries |
| 857 | // in the hash table really refer to the same symbol. This will |
| 858 | // never be set for a symbol found in the hash table, but may be set |
| 859 | // for a symbol found in the list of symbols attached to an Object. |
| 860 | // It forwards to the symbol found in the forwarders_ map of |
| 861 | // Symbol_table (bit 21). |
| 862 | bool is_forwarder_ : 1; |
| 863 | // True if the symbol has an alias in the weak_aliases table in |
| 864 | // Symbol_table (bit 22). |
| 865 | bool has_alias_ : 1; |
| 866 | // True if this symbol needs to be in the dynamic symbol table (bit |
| 867 | // 23). |
| 868 | bool needs_dynsym_entry_ : 1; |
| 869 | // True if we've seen this symbol in a regular object (bit 24). |
| 870 | bool in_reg_ : 1; |
| 871 | // True if we've seen this symbol in a dynamic object (bit 25). |
| 872 | bool in_dyn_ : 1; |
| 873 | // True if the symbol has an entry in the PLT section (bit 26). |
| 874 | bool has_plt_offset_ : 1; |
| 875 | // True if this is a dynamic symbol which needs a special value in |
| 876 | // the dynamic symbol table (bit 27). |
| 877 | bool needs_dynsym_value_ : 1; |
| 878 | // True if there is a warning for this symbol (bit 28). |
| 879 | bool has_warning_ : 1; |
| 880 | // True if we are using a COPY reloc for this symbol, so that the |
| 881 | // real definition lives in a dynamic object (bit 29). |
| 882 | bool is_copied_from_dynobj_ : 1; |
| 883 | // True if this symbol was forced to local visibility by a version |
| 884 | // script (bit 30). |
| 885 | bool is_forced_local_ : 1; |
| 886 | // True if the field u_.from_object.shndx is an ordinary section |
| 887 | // index, not one of the special codes from SHN_LORESERVE to |
| 888 | // SHN_HIRESERVE (bit 31). |
| 889 | bool is_ordinary_shndx_ : 1; |
| 890 | // True if we've seen this symbol in a real ELF object. |
| 891 | bool in_real_elf_ : 1; |
| 892 | }; |
| 893 | |
| 894 | // The parts of a symbol which are size specific. Using a template |
| 895 | // derived class like this helps us use less space on a 32-bit system. |
| 896 | |
| 897 | template<int size> |
| 898 | class Sized_symbol : public Symbol |
| 899 | { |
| 900 | public: |
| 901 | typedef typename elfcpp::Elf_types<size>::Elf_Addr Value_type; |
| 902 | typedef typename elfcpp::Elf_types<size>::Elf_WXword Size_type; |
| 903 | |
| 904 | Sized_symbol() |
| 905 | { } |
| 906 | |
| 907 | // Initialize fields from an ELF symbol in OBJECT. ST_SHNDX is the |
| 908 | // section index, IS_ORDINARY is whether it is a normal section |
| 909 | // index rather than a special code. |
| 910 | template<bool big_endian> |
| 911 | void |
| 912 | init_object(const char *name, const char* version, Object* object, |
| 913 | const elfcpp::Sym<size, big_endian>&, unsigned int st_shndx, |
| 914 | bool is_ordinary); |
| 915 | |
| 916 | // Initialize fields for an Output_data. |
| 917 | void |
| 918 | init_output_data(const char* name, const char* version, Output_data*, |
| 919 | Value_type value, Size_type symsize, elfcpp::STT, |
| 920 | elfcpp::STB, elfcpp::STV, unsigned char nonvis, |
| 921 | bool offset_is_from_end); |
| 922 | |
| 923 | // Initialize fields for an Output_segment. |
| 924 | void |
| 925 | init_output_segment(const char* name, const char* version, Output_segment*, |
| 926 | Value_type value, Size_type symsize, elfcpp::STT, |
| 927 | elfcpp::STB, elfcpp::STV, unsigned char nonvis, |
| 928 | Segment_offset_base offset_base); |
| 929 | |
| 930 | // Initialize fields for a constant. |
| 931 | void |
| 932 | init_constant(const char* name, const char* version, Value_type value, |
| 933 | Size_type symsize, elfcpp::STT, elfcpp::STB, elfcpp::STV, |
| 934 | unsigned char nonvis); |
| 935 | |
| 936 | // Initialize fields for an undefined symbol. |
| 937 | void |
| 938 | init_undefined(const char* name, const char* version, elfcpp::STT, |
| 939 | elfcpp::STB, elfcpp::STV, unsigned char nonvis); |
| 940 | |
| 941 | // Override existing symbol. |
| 942 | template<bool big_endian> |
| 943 | void |
| 944 | override(const elfcpp::Sym<size, big_endian>&, unsigned int st_shndx, |
| 945 | bool is_ordinary, Object* object, const char* version); |
| 946 | |
| 947 | // Override existing symbol with a special symbol. |
| 948 | void |
| 949 | override_with_special(const Sized_symbol<size>*); |
| 950 | |
| 951 | // Return the symbol's value. |
| 952 | Value_type |
| 953 | value() const |
| 954 | { return this->value_; } |
| 955 | |
| 956 | // Return the symbol's size (we can't call this 'size' because that |
| 957 | // is a template parameter). |
| 958 | Size_type |
| 959 | symsize() const |
| 960 | { return this->symsize_; } |
| 961 | |
| 962 | // Set the symbol size. This is used when resolving common symbols. |
| 963 | void |
| 964 | set_symsize(Size_type symsize) |
| 965 | { this->symsize_ = symsize; } |
| 966 | |
| 967 | // Set the symbol value. This is called when we store the final |
| 968 | // values of the symbols into the symbol table. |
| 969 | void |
| 970 | set_value(Value_type value) |
| 971 | { this->value_ = value; } |
| 972 | |
| 973 | // Allocate a common symbol by giving it a location in the output |
| 974 | // file. |
| 975 | void |
| 976 | allocate_common(Output_data*, Value_type value); |
| 977 | |
| 978 | private: |
| 979 | Sized_symbol(const Sized_symbol&); |
| 980 | Sized_symbol& operator=(const Sized_symbol&); |
| 981 | |
| 982 | // Symbol value. Before Layout::finalize this is the offset in the |
| 983 | // input section. This is set to the final value during |
| 984 | // Layout::finalize. |
| 985 | Value_type value_; |
| 986 | // Symbol size. |
| 987 | Size_type symsize_; |
| 988 | }; |
| 989 | |
| 990 | // A struct describing a symbol defined by the linker, where the value |
| 991 | // of the symbol is defined based on an output section. This is used |
| 992 | // for symbols defined by the linker, like "_init_array_start". |
| 993 | |
| 994 | struct Define_symbol_in_section |
| 995 | { |
| 996 | // The symbol name. |
| 997 | const char* name; |
| 998 | // The name of the output section with which this symbol should be |
| 999 | // associated. If there is no output section with that name, the |
| 1000 | // symbol will be defined as zero. |
| 1001 | const char* output_section; |
| 1002 | // The offset of the symbol within the output section. This is an |
| 1003 | // offset from the start of the output section, unless start_at_end |
| 1004 | // is true, in which case this is an offset from the end of the |
| 1005 | // output section. |
| 1006 | uint64_t value; |
| 1007 | // The size of the symbol. |
| 1008 | uint64_t size; |
| 1009 | // The symbol type. |
| 1010 | elfcpp::STT type; |
| 1011 | // The symbol binding. |
| 1012 | elfcpp::STB binding; |
| 1013 | // The symbol visibility. |
| 1014 | elfcpp::STV visibility; |
| 1015 | // The rest of the st_other field. |
| 1016 | unsigned char nonvis; |
| 1017 | // If true, the value field is an offset from the end of the output |
| 1018 | // section. |
| 1019 | bool offset_is_from_end; |
| 1020 | // If true, this symbol is defined only if we see a reference to it. |
| 1021 | bool only_if_ref; |
| 1022 | }; |
| 1023 | |
| 1024 | // A struct describing a symbol defined by the linker, where the value |
| 1025 | // of the symbol is defined based on a segment. This is used for |
| 1026 | // symbols defined by the linker, like "_end". We describe the |
| 1027 | // segment with which the symbol should be associated by its |
| 1028 | // characteristics. If no segment meets these characteristics, the |
| 1029 | // symbol will be defined as zero. If there is more than one segment |
| 1030 | // which meets these characteristics, we will use the first one. |
| 1031 | |
| 1032 | struct Define_symbol_in_segment |
| 1033 | { |
| 1034 | // The symbol name. |
| 1035 | const char* name; |
| 1036 | // The segment type where the symbol should be defined, typically |
| 1037 | // PT_LOAD. |
| 1038 | elfcpp::PT segment_type; |
| 1039 | // Bitmask of segment flags which must be set. |
| 1040 | elfcpp::PF segment_flags_set; |
| 1041 | // Bitmask of segment flags which must be clear. |
| 1042 | elfcpp::PF segment_flags_clear; |
| 1043 | // The offset of the symbol within the segment. The offset is |
| 1044 | // calculated from the position set by offset_base. |
| 1045 | uint64_t value; |
| 1046 | // The size of the symbol. |
| 1047 | uint64_t size; |
| 1048 | // The symbol type. |
| 1049 | elfcpp::STT type; |
| 1050 | // The symbol binding. |
| 1051 | elfcpp::STB binding; |
| 1052 | // The symbol visibility. |
| 1053 | elfcpp::STV visibility; |
| 1054 | // The rest of the st_other field. |
| 1055 | unsigned char nonvis; |
| 1056 | // The base from which we compute the offset. |
| 1057 | Symbol::Segment_offset_base offset_base; |
| 1058 | // If true, this symbol is defined only if we see a reference to it. |
| 1059 | bool only_if_ref; |
| 1060 | }; |
| 1061 | |
| 1062 | // This class manages warnings. Warnings are a GNU extension. When |
| 1063 | // we see a section named .gnu.warning.SYM in an object file, and if |
| 1064 | // we wind using the definition of SYM from that object file, then we |
| 1065 | // will issue a warning for any relocation against SYM from a |
| 1066 | // different object file. The text of the warning is the contents of |
| 1067 | // the section. This is not precisely the definition used by the old |
| 1068 | // GNU linker; the old GNU linker treated an occurrence of |
| 1069 | // .gnu.warning.SYM as defining a warning symbol. A warning symbol |
| 1070 | // would trigger a warning on any reference. However, it was |
| 1071 | // inconsistent in that a warning in a dynamic object only triggered |
| 1072 | // if there was no definition in a regular object. This linker is |
| 1073 | // different in that we only issue a warning if we use the symbol |
| 1074 | // definition from the same object file as the warning section. |
| 1075 | |
| 1076 | class Warnings |
| 1077 | { |
| 1078 | public: |
| 1079 | Warnings() |
| 1080 | : warnings_() |
| 1081 | { } |
| 1082 | |
| 1083 | // Add a warning for symbol NAME in object OBJ. WARNING is the text |
| 1084 | // of the warning. |
| 1085 | void |
| 1086 | add_warning(Symbol_table* symtab, const char* name, Object* obj, |
| 1087 | const std::string& warning); |
| 1088 | |
| 1089 | // For each symbol for which we should give a warning, make a note |
| 1090 | // on the symbol. |
| 1091 | void |
| 1092 | note_warnings(Symbol_table* symtab); |
| 1093 | |
| 1094 | // Issue a warning for a reference to SYM at RELINFO's location. |
| 1095 | template<int size, bool big_endian> |
| 1096 | void |
| 1097 | issue_warning(const Symbol* sym, const Relocate_info<size, big_endian>*, |
| 1098 | size_t relnum, off_t reloffset) const; |
| 1099 | |
| 1100 | private: |
| 1101 | Warnings(const Warnings&); |
| 1102 | Warnings& operator=(const Warnings&); |
| 1103 | |
| 1104 | // What we need to know to get the warning text. |
| 1105 | struct Warning_location |
| 1106 | { |
| 1107 | // The object the warning is in. |
| 1108 | Object* object; |
| 1109 | // The warning text. |
| 1110 | std::string text; |
| 1111 | |
| 1112 | Warning_location() |
| 1113 | : object(NULL), text() |
| 1114 | { } |
| 1115 | |
| 1116 | void |
| 1117 | set(Object* o, const std::string& t) |
| 1118 | { |
| 1119 | this->object = o; |
| 1120 | this->text = t; |
| 1121 | } |
| 1122 | }; |
| 1123 | |
| 1124 | // A mapping from warning symbol names (canonicalized in |
| 1125 | // Symbol_table's namepool_ field) to warning information. |
| 1126 | typedef Unordered_map<const char*, Warning_location> Warning_table; |
| 1127 | |
| 1128 | Warning_table warnings_; |
| 1129 | }; |
| 1130 | |
| 1131 | // The main linker symbol table. |
| 1132 | |
| 1133 | class Symbol_table |
| 1134 | { |
| 1135 | public: |
| 1136 | // COUNT is an estimate of how many symbosl will be inserted in the |
| 1137 | // symbol table. It's ok to put 0 if you don't know; a correct |
| 1138 | // guess will just save some CPU by reducing hashtable resizes. |
| 1139 | Symbol_table(unsigned int count, const Version_script_info& version_script); |
| 1140 | |
| 1141 | ~Symbol_table(); |
| 1142 | |
| 1143 | // Add COUNT external symbols from the relocatable object RELOBJ to |
| 1144 | // the symbol table. SYMS is the symbols, SYMNDX_OFFSET is the |
| 1145 | // offset in the symbol table of the first symbol, SYM_NAMES is |
| 1146 | // their names, SYM_NAME_SIZE is the size of SYM_NAMES. This sets |
| 1147 | // SYMPOINTERS to point to the symbols in the symbol table. It sets |
| 1148 | // *DEFINED to the number of defined symbols. |
| 1149 | template<int size, bool big_endian> |
| 1150 | void |
| 1151 | add_from_relobj(Sized_relobj<size, big_endian>* relobj, |
| 1152 | const unsigned char* syms, size_t count, |
| 1153 | size_t symndx_offset, const char* sym_names, |
| 1154 | size_t sym_name_size, |
| 1155 | typename Sized_relobj<size, big_endian>::Symbols*, |
| 1156 | size_t* defined); |
| 1157 | |
| 1158 | // Add one external symbol from the plugin object OBJ to the symbol table. |
| 1159 | // Returns a pointer to the resolved symbol in the symbol table. |
| 1160 | template<int size, bool big_endian> |
| 1161 | Symbol* |
| 1162 | add_from_pluginobj(Sized_pluginobj<size, big_endian>* obj, |
| 1163 | const char* name, const char* ver, |
| 1164 | elfcpp::Sym<size, big_endian>* sym); |
| 1165 | |
| 1166 | // Add COUNT dynamic symbols from the dynamic object DYNOBJ to the |
| 1167 | // symbol table. SYMS is the symbols. SYM_NAMES is their names. |
| 1168 | // SYM_NAME_SIZE is the size of SYM_NAMES. The other parameters are |
| 1169 | // symbol version data. |
| 1170 | template<int size, bool big_endian> |
| 1171 | void |
| 1172 | add_from_dynobj(Sized_dynobj<size, big_endian>* dynobj, |
| 1173 | const unsigned char* syms, size_t count, |
| 1174 | const char* sym_names, size_t sym_name_size, |
| 1175 | const unsigned char* versym, size_t versym_size, |
| 1176 | const std::vector<const char*>*, |
| 1177 | typename Sized_relobj<size, big_endian>::Symbols*, |
| 1178 | size_t* defined); |
| 1179 | |
| 1180 | // Define a special symbol based on an Output_data. It is a |
| 1181 | // multiple definition error if this symbol is already defined. |
| 1182 | Symbol* |
| 1183 | define_in_output_data(const char* name, const char* version, |
| 1184 | Output_data*, uint64_t value, uint64_t symsize, |
| 1185 | elfcpp::STT type, elfcpp::STB binding, |
| 1186 | elfcpp::STV visibility, unsigned char nonvis, |
| 1187 | bool offset_is_from_end, bool only_if_ref); |
| 1188 | |
| 1189 | // Define a special symbol based on an Output_segment. It is a |
| 1190 | // multiple definition error if this symbol is already defined. |
| 1191 | Symbol* |
| 1192 | define_in_output_segment(const char* name, const char* version, |
| 1193 | Output_segment*, uint64_t value, uint64_t symsize, |
| 1194 | elfcpp::STT type, elfcpp::STB binding, |
| 1195 | elfcpp::STV visibility, unsigned char nonvis, |
| 1196 | Symbol::Segment_offset_base, bool only_if_ref); |
| 1197 | |
| 1198 | // Define a special symbol with a constant value. It is a multiple |
| 1199 | // definition error if this symbol is already defined. |
| 1200 | Symbol* |
| 1201 | define_as_constant(const char* name, const char* version, |
| 1202 | uint64_t value, uint64_t symsize, elfcpp::STT type, |
| 1203 | elfcpp::STB binding, elfcpp::STV visibility, |
| 1204 | unsigned char nonvis, bool only_if_ref, |
| 1205 | bool force_override); |
| 1206 | |
| 1207 | // Define a set of symbols in output sections. If ONLY_IF_REF is |
| 1208 | // true, only define them if they are referenced. |
| 1209 | void |
| 1210 | define_symbols(const Layout*, int count, const Define_symbol_in_section*, |
| 1211 | bool only_if_ref); |
| 1212 | |
| 1213 | // Define a set of symbols in output segments. If ONLY_IF_REF is |
| 1214 | // true, only defined them if they are referenced. |
| 1215 | void |
| 1216 | define_symbols(const Layout*, int count, const Define_symbol_in_segment*, |
| 1217 | bool only_if_ref); |
| 1218 | |
| 1219 | // Define SYM using a COPY reloc. POSD is the Output_data where the |
| 1220 | // symbol should be defined--typically a .dyn.bss section. VALUE is |
| 1221 | // the offset within POSD. |
| 1222 | template<int size> |
| 1223 | void |
| 1224 | define_with_copy_reloc(Sized_symbol<size>* sym, Output_data* posd, |
| 1225 | typename elfcpp::Elf_types<size>::Elf_Addr); |
| 1226 | |
| 1227 | // Look up a symbol. |
| 1228 | Symbol* |
| 1229 | lookup(const char*, const char* version = NULL) const; |
| 1230 | |
| 1231 | // Return the real symbol associated with the forwarder symbol FROM. |
| 1232 | Symbol* |
| 1233 | resolve_forwards(const Symbol* from) const; |
| 1234 | |
| 1235 | // Return the sized version of a symbol in this table. |
| 1236 | template<int size> |
| 1237 | Sized_symbol<size>* |
| 1238 | get_sized_symbol(Symbol*) const; |
| 1239 | |
| 1240 | template<int size> |
| 1241 | const Sized_symbol<size>* |
| 1242 | get_sized_symbol(const Symbol*) const; |
| 1243 | |
| 1244 | // Return the count of undefined symbols seen. |
| 1245 | int |
| 1246 | saw_undefined() const |
| 1247 | { return this->saw_undefined_; } |
| 1248 | |
| 1249 | // Allocate the common symbols |
| 1250 | void |
| 1251 | allocate_commons(Layout*, Mapfile*); |
| 1252 | |
| 1253 | // Add a warning for symbol NAME in object OBJ. WARNING is the text |
| 1254 | // of the warning. |
| 1255 | void |
| 1256 | add_warning(const char* name, Object* obj, const std::string& warning) |
| 1257 | { this->warnings_.add_warning(this, name, obj, warning); } |
| 1258 | |
| 1259 | // Canonicalize a symbol name for use in the hash table. |
| 1260 | const char* |
| 1261 | canonicalize_name(const char* name) |
| 1262 | { return this->namepool_.add(name, true, NULL); } |
| 1263 | |
| 1264 | // Possibly issue a warning for a reference to SYM at LOCATION which |
| 1265 | // is in OBJ. |
| 1266 | template<int size, bool big_endian> |
| 1267 | void |
| 1268 | issue_warning(const Symbol* sym, |
| 1269 | const Relocate_info<size, big_endian>* relinfo, |
| 1270 | size_t relnum, off_t reloffset) const |
| 1271 | { this->warnings_.issue_warning(sym, relinfo, relnum, reloffset); } |
| 1272 | |
| 1273 | // Check candidate_odr_violations_ to find symbols with the same name |
| 1274 | // but apparently different definitions (different source-file/line-no). |
| 1275 | void |
| 1276 | detect_odr_violations(const Task*, const char* output_file_name) const; |
| 1277 | |
| 1278 | // Add any undefined symbols named on the command line to the symbol |
| 1279 | // table. |
| 1280 | void |
| 1281 | add_undefined_symbols_from_command_line(); |
| 1282 | |
| 1283 | // SYM is defined using a COPY reloc. Return the dynamic object |
| 1284 | // where the original definition was found. |
| 1285 | Dynobj* |
| 1286 | get_copy_source(const Symbol* sym) const; |
| 1287 | |
| 1288 | // Set the dynamic symbol indexes. INDEX is the index of the first |
| 1289 | // global dynamic symbol. Pointers to the symbols are stored into |
| 1290 | // the vector. The names are stored into the Stringpool. This |
| 1291 | // returns an updated dynamic symbol index. |
| 1292 | unsigned int |
| 1293 | set_dynsym_indexes(unsigned int index, std::vector<Symbol*>*, |
| 1294 | Stringpool*, Versions*); |
| 1295 | |
| 1296 | // Finalize the symbol table after we have set the final addresses |
| 1297 | // of all the input sections. This sets the final symbol indexes, |
| 1298 | // values and adds the names to *POOL. *PLOCAL_SYMCOUNT is the |
| 1299 | // index of the first global symbol. OFF is the file offset of the |
| 1300 | // global symbol table, DYNOFF is the offset of the globals in the |
| 1301 | // dynamic symbol table, DYN_GLOBAL_INDEX is the index of the first |
| 1302 | // global dynamic symbol, and DYNCOUNT is the number of global |
| 1303 | // dynamic symbols. This records the parameters, and returns the |
| 1304 | // new file offset. It updates *PLOCAL_SYMCOUNT if it created any |
| 1305 | // local symbols. |
| 1306 | off_t |
| 1307 | finalize(off_t off, off_t dynoff, size_t dyn_global_index, size_t dyncount, |
| 1308 | Stringpool* pool, unsigned int *plocal_symcount); |
| 1309 | |
| 1310 | // Write out the global symbols. |
| 1311 | void |
| 1312 | write_globals(const Input_objects*, const Stringpool*, const Stringpool*, |
| 1313 | Output_symtab_xindex*, Output_symtab_xindex*, |
| 1314 | Output_file*) const; |
| 1315 | |
| 1316 | // Write out a section symbol. Return the updated offset. |
| 1317 | void |
| 1318 | write_section_symbol(const Output_section*, Output_symtab_xindex*, |
| 1319 | Output_file*, off_t) const; |
| 1320 | |
| 1321 | // Dump statistical information to stderr. |
| 1322 | void |
| 1323 | print_stats() const; |
| 1324 | |
| 1325 | // Return the version script information. |
| 1326 | const Version_script_info& |
| 1327 | version_script() const |
| 1328 | { return version_script_; } |
| 1329 | |
| 1330 | private: |
| 1331 | Symbol_table(const Symbol_table&); |
| 1332 | Symbol_table& operator=(const Symbol_table&); |
| 1333 | |
| 1334 | // The type of the list of common symbols. |
| 1335 | typedef std::vector<Symbol*> Commons_type; |
| 1336 | |
| 1337 | // Make FROM a forwarder symbol to TO. |
| 1338 | void |
| 1339 | make_forwarder(Symbol* from, Symbol* to); |
| 1340 | |
| 1341 | // Add a symbol. |
| 1342 | template<int size, bool big_endian> |
| 1343 | Sized_symbol<size>* |
| 1344 | add_from_object(Object*, const char *name, Stringpool::Key name_key, |
| 1345 | const char *version, Stringpool::Key version_key, |
| 1346 | bool def, const elfcpp::Sym<size, big_endian>& sym, |
| 1347 | unsigned int st_shndx, bool is_ordinary, |
| 1348 | unsigned int orig_st_shndx); |
| 1349 | |
| 1350 | // Resolve symbols. |
| 1351 | template<int size, bool big_endian> |
| 1352 | void |
| 1353 | resolve(Sized_symbol<size>* to, |
| 1354 | const elfcpp::Sym<size, big_endian>& sym, |
| 1355 | unsigned int st_shndx, bool is_ordinary, |
| 1356 | unsigned int orig_st_shndx, |
| 1357 | Object*, const char* version); |
| 1358 | |
| 1359 | template<int size, bool big_endian> |
| 1360 | void |
| 1361 | resolve(Sized_symbol<size>* to, const Sized_symbol<size>* from); |
| 1362 | |
| 1363 | // Record that a symbol is forced to be local by a version script. |
| 1364 | void |
| 1365 | force_local(Symbol*); |
| 1366 | |
| 1367 | // Adjust NAME and *NAME_KEY for wrapping. |
| 1368 | const char* |
| 1369 | wrap_symbol(Object* object, const char*, Stringpool::Key* name_key); |
| 1370 | |
| 1371 | // Whether we should override a symbol, based on flags in |
| 1372 | // resolve.cc. |
| 1373 | static bool |
| 1374 | should_override(const Symbol*, unsigned int, Object*, bool*); |
| 1375 | |
| 1376 | // Override a symbol. |
| 1377 | template<int size, bool big_endian> |
| 1378 | void |
| 1379 | override(Sized_symbol<size>* tosym, |
| 1380 | const elfcpp::Sym<size, big_endian>& fromsym, |
| 1381 | unsigned int st_shndx, bool is_ordinary, |
| 1382 | Object* object, const char* version); |
| 1383 | |
| 1384 | // Whether we should override a symbol with a special symbol which |
| 1385 | // is automatically defined by the linker. |
| 1386 | static bool |
| 1387 | should_override_with_special(const Symbol*); |
| 1388 | |
| 1389 | // Override a symbol with a special symbol. |
| 1390 | template<int size> |
| 1391 | void |
| 1392 | override_with_special(Sized_symbol<size>* tosym, |
| 1393 | const Sized_symbol<size>* fromsym); |
| 1394 | |
| 1395 | // Record all weak alias sets for a dynamic object. |
| 1396 | template<int size> |
| 1397 | void |
| 1398 | record_weak_aliases(std::vector<Sized_symbol<size>*>*); |
| 1399 | |
| 1400 | // Define a special symbol. |
| 1401 | template<int size, bool big_endian> |
| 1402 | Sized_symbol<size>* |
| 1403 | define_special_symbol(const char** pname, const char** pversion, |
| 1404 | bool only_if_ref, Sized_symbol<size>** poldsym); |
| 1405 | |
| 1406 | // Define a symbol in an Output_data, sized version. |
| 1407 | template<int size> |
| 1408 | Sized_symbol<size>* |
| 1409 | do_define_in_output_data(const char* name, const char* version, Output_data*, |
| 1410 | typename elfcpp::Elf_types<size>::Elf_Addr value, |
| 1411 | typename elfcpp::Elf_types<size>::Elf_WXword ssize, |
| 1412 | elfcpp::STT type, elfcpp::STB binding, |
| 1413 | elfcpp::STV visibility, unsigned char nonvis, |
| 1414 | bool offset_is_from_end, bool only_if_ref); |
| 1415 | |
| 1416 | // Define a symbol in an Output_segment, sized version. |
| 1417 | template<int size> |
| 1418 | Sized_symbol<size>* |
| 1419 | do_define_in_output_segment( |
| 1420 | const char* name, const char* version, Output_segment* os, |
| 1421 | typename elfcpp::Elf_types<size>::Elf_Addr value, |
| 1422 | typename elfcpp::Elf_types<size>::Elf_WXword ssize, |
| 1423 | elfcpp::STT type, elfcpp::STB binding, |
| 1424 | elfcpp::STV visibility, unsigned char nonvis, |
| 1425 | Symbol::Segment_offset_base offset_base, bool only_if_ref); |
| 1426 | |
| 1427 | // Define a symbol as a constant, sized version. |
| 1428 | template<int size> |
| 1429 | Sized_symbol<size>* |
| 1430 | do_define_as_constant( |
| 1431 | const char* name, const char* version, |
| 1432 | typename elfcpp::Elf_types<size>::Elf_Addr value, |
| 1433 | typename elfcpp::Elf_types<size>::Elf_WXword ssize, |
| 1434 | elfcpp::STT type, elfcpp::STB binding, |
| 1435 | elfcpp::STV visibility, unsigned char nonvis, |
| 1436 | bool only_if_ref, bool force_override); |
| 1437 | |
| 1438 | // Add any undefined symbols named on the command line to the symbol |
| 1439 | // table, sized version. |
| 1440 | template<int size> |
| 1441 | void |
| 1442 | do_add_undefined_symbols_from_command_line(); |
| 1443 | |
| 1444 | // Allocate the common symbols, sized version. |
| 1445 | template<int size> |
| 1446 | void |
| 1447 | do_allocate_commons(Layout*, Mapfile*); |
| 1448 | |
| 1449 | // Allocate the common symbols from one list. |
| 1450 | template<int size> |
| 1451 | void |
| 1452 | do_allocate_commons_list(Layout*, bool is_tls, Commons_type*, Mapfile*); |
| 1453 | |
| 1454 | // Implement detect_odr_violations. |
| 1455 | template<int size, bool big_endian> |
| 1456 | void |
| 1457 | sized_detect_odr_violations() const; |
| 1458 | |
| 1459 | // Finalize symbols specialized for size. |
| 1460 | template<int size> |
| 1461 | off_t |
| 1462 | sized_finalize(off_t, Stringpool*, unsigned int*); |
| 1463 | |
| 1464 | // Finalize a symbol. Return whether it should be added to the |
| 1465 | // symbol table. |
| 1466 | template<int size> |
| 1467 | bool |
| 1468 | sized_finalize_symbol(Symbol*); |
| 1469 | |
| 1470 | // Add a symbol the final symtab by setting its index. |
| 1471 | template<int size> |
| 1472 | void |
| 1473 | add_to_final_symtab(Symbol*, Stringpool*, unsigned int* pindex, off_t* poff); |
| 1474 | |
| 1475 | // Write globals specialized for size and endianness. |
| 1476 | template<int size, bool big_endian> |
| 1477 | void |
| 1478 | sized_write_globals(const Input_objects*, const Stringpool*, |
| 1479 | const Stringpool*, Output_symtab_xindex*, |
| 1480 | Output_symtab_xindex*, Output_file*) const; |
| 1481 | |
| 1482 | // Write out a symbol to P. |
| 1483 | template<int size, bool big_endian> |
| 1484 | void |
| 1485 | sized_write_symbol(Sized_symbol<size>*, |
| 1486 | typename elfcpp::Elf_types<size>::Elf_Addr value, |
| 1487 | unsigned int shndx, |
| 1488 | const Stringpool*, unsigned char* p) const; |
| 1489 | |
| 1490 | // Possibly warn about an undefined symbol from a dynamic object. |
| 1491 | void |
| 1492 | warn_about_undefined_dynobj_symbol(const Input_objects*, Symbol*) const; |
| 1493 | |
| 1494 | // Write out a section symbol, specialized for size and endianness. |
| 1495 | template<int size, bool big_endian> |
| 1496 | void |
| 1497 | sized_write_section_symbol(const Output_section*, Output_symtab_xindex*, |
| 1498 | Output_file*, off_t) const; |
| 1499 | |
| 1500 | // The type of the symbol hash table. |
| 1501 | |
| 1502 | typedef std::pair<Stringpool::Key, Stringpool::Key> Symbol_table_key; |
| 1503 | |
| 1504 | struct Symbol_table_hash |
| 1505 | { |
| 1506 | size_t |
| 1507 | operator()(const Symbol_table_key&) const; |
| 1508 | }; |
| 1509 | |
| 1510 | struct Symbol_table_eq |
| 1511 | { |
| 1512 | bool |
| 1513 | operator()(const Symbol_table_key&, const Symbol_table_key&) const; |
| 1514 | }; |
| 1515 | |
| 1516 | typedef Unordered_map<Symbol_table_key, Symbol*, Symbol_table_hash, |
| 1517 | Symbol_table_eq> Symbol_table_type; |
| 1518 | |
| 1519 | // The type of the list of symbols which have been forced local. |
| 1520 | typedef std::vector<Symbol*> Forced_locals; |
| 1521 | |
| 1522 | // A map from symbols with COPY relocs to the dynamic objects where |
| 1523 | // they are defined. |
| 1524 | typedef Unordered_map<const Symbol*, Dynobj*> Copied_symbol_dynobjs; |
| 1525 | |
| 1526 | // A map from symbol name (as a pointer into the namepool) to all |
| 1527 | // the locations the symbols is (weakly) defined (and certain other |
| 1528 | // conditions are met). This map will be used later to detect |
| 1529 | // possible One Definition Rule (ODR) violations. |
| 1530 | struct Symbol_location |
| 1531 | { |
| 1532 | Object* object; // Object where the symbol is defined. |
| 1533 | unsigned int shndx; // Section-in-object where the symbol is defined. |
| 1534 | off_t offset; // Offset-in-section where the symbol is defined. |
| 1535 | bool operator==(const Symbol_location& that) const |
| 1536 | { |
| 1537 | return (this->object == that.object |
| 1538 | && this->shndx == that.shndx |
| 1539 | && this->offset == that.offset); |
| 1540 | } |
| 1541 | }; |
| 1542 | |
| 1543 | struct Symbol_location_hash |
| 1544 | { |
| 1545 | size_t operator()(const Symbol_location& loc) const |
| 1546 | { return reinterpret_cast<uintptr_t>(loc.object) ^ loc.offset ^ loc.shndx; } |
| 1547 | }; |
| 1548 | |
| 1549 | typedef Unordered_map<const char*, |
| 1550 | Unordered_set<Symbol_location, Symbol_location_hash> > |
| 1551 | Odr_map; |
| 1552 | |
| 1553 | // We increment this every time we see a new undefined symbol, for |
| 1554 | // use in archive groups. |
| 1555 | int saw_undefined_; |
| 1556 | // The index of the first global symbol in the output file. |
| 1557 | unsigned int first_global_index_; |
| 1558 | // The file offset within the output symtab section where we should |
| 1559 | // write the table. |
| 1560 | off_t offset_; |
| 1561 | // The number of global symbols we want to write out. |
| 1562 | unsigned int output_count_; |
| 1563 | // The file offset of the global dynamic symbols, or 0 if none. |
| 1564 | off_t dynamic_offset_; |
| 1565 | // The index of the first global dynamic symbol. |
| 1566 | unsigned int first_dynamic_global_index_; |
| 1567 | // The number of global dynamic symbols, or 0 if none. |
| 1568 | unsigned int dynamic_count_; |
| 1569 | // The symbol hash table. |
| 1570 | Symbol_table_type table_; |
| 1571 | // A pool of symbol names. This is used for all global symbols. |
| 1572 | // Entries in the hash table point into this pool. |
| 1573 | Stringpool namepool_; |
| 1574 | // Forwarding symbols. |
| 1575 | Unordered_map<const Symbol*, Symbol*> forwarders_; |
| 1576 | // Weak aliases. A symbol in this list points to the next alias. |
| 1577 | // The aliases point to each other in a circular list. |
| 1578 | Unordered_map<Symbol*, Symbol*> weak_aliases_; |
| 1579 | // We don't expect there to be very many common symbols, so we keep |
| 1580 | // a list of them. When we find a common symbol we add it to this |
| 1581 | // list. It is possible that by the time we process the list the |
| 1582 | // symbol is no longer a common symbol. It may also have become a |
| 1583 | // forwarder. |
| 1584 | Commons_type commons_; |
| 1585 | // This is like the commons_ field, except that it holds TLS common |
| 1586 | // symbols. |
| 1587 | Commons_type tls_commons_; |
| 1588 | // A list of symbols which have been forced to be local. We don't |
| 1589 | // expect there to be very many of them, so we keep a list of them |
| 1590 | // rather than walking the whole table to find them. |
| 1591 | Forced_locals forced_locals_; |
| 1592 | // Manage symbol warnings. |
| 1593 | Warnings warnings_; |
| 1594 | // Manage potential One Definition Rule (ODR) violations. |
| 1595 | Odr_map candidate_odr_violations_; |
| 1596 | |
| 1597 | // When we emit a COPY reloc for a symbol, we define it in an |
| 1598 | // Output_data. When it's time to emit version information for it, |
| 1599 | // we need to know the dynamic object in which we found the original |
| 1600 | // definition. This maps symbols with COPY relocs to the dynamic |
| 1601 | // object where they were defined. |
| 1602 | Copied_symbol_dynobjs copied_symbol_dynobjs_; |
| 1603 | // Information parsed from the version script, if any. |
| 1604 | const Version_script_info& version_script_; |
| 1605 | }; |
| 1606 | |
| 1607 | // We inline get_sized_symbol for efficiency. |
| 1608 | |
| 1609 | template<int size> |
| 1610 | Sized_symbol<size>* |
| 1611 | Symbol_table::get_sized_symbol(Symbol* sym) const |
| 1612 | { |
| 1613 | gold_assert(size == parameters->target().get_size()); |
| 1614 | return static_cast<Sized_symbol<size>*>(sym); |
| 1615 | } |
| 1616 | |
| 1617 | template<int size> |
| 1618 | const Sized_symbol<size>* |
| 1619 | Symbol_table::get_sized_symbol(const Symbol* sym) const |
| 1620 | { |
| 1621 | gold_assert(size == parameters->target().get_size()); |
| 1622 | return static_cast<const Sized_symbol<size>*>(sym); |
| 1623 | } |
| 1624 | |
| 1625 | } // End namespace gold. |
| 1626 | |
| 1627 | #endif // !defined(GOLD_SYMTAB_H) |