| 1 | // symtab.h -- the gold symbol table -*- C++ -*- |
| 2 | |
| 3 | // Symbol_table |
| 4 | // The symbol table. |
| 5 | |
| 6 | #include <string> |
| 7 | #include <utility> |
| 8 | #include <vector> |
| 9 | |
| 10 | #include "elfcpp.h" |
| 11 | #include "stringpool.h" |
| 12 | #include "object.h" |
| 13 | |
| 14 | #ifndef GOLD_SYMTAB_H |
| 15 | #define GOLD_SYMTAB_H |
| 16 | |
| 17 | namespace gold |
| 18 | { |
| 19 | |
| 20 | class Object; |
| 21 | class Relobj; |
| 22 | template<int size, bool big_endian> |
| 23 | class Sized_relobj; |
| 24 | class Dynobj; |
| 25 | template<int size, bool big_endian> |
| 26 | class Sized_dynobj; |
| 27 | class Versions; |
| 28 | class Output_data; |
| 29 | class Output_section; |
| 30 | class Output_segment; |
| 31 | class Output_file; |
| 32 | class Target; |
| 33 | |
| 34 | // The base class of an entry in the symbol table. The symbol table |
| 35 | // can have a lot of entries, so we don't want this class to big. |
| 36 | // Size dependent fields can be found in the template class |
| 37 | // Sized_symbol. Targets may support their own derived classes. |
| 38 | |
| 39 | class Symbol |
| 40 | { |
| 41 | public: |
| 42 | // Because we want the class to be small, we don't use any virtual |
| 43 | // functions. But because symbols can be defined in different |
| 44 | // places, we need to classify them. This enum is the different |
| 45 | // sources of symbols we support. |
| 46 | enum Source |
| 47 | { |
| 48 | // Symbol defined in a relocatable or dynamic input file--this is |
| 49 | // the most common case. |
| 50 | FROM_OBJECT, |
| 51 | // Symbol defined in an Output_data, a special section created by |
| 52 | // the target. |
| 53 | IN_OUTPUT_DATA, |
| 54 | // Symbol defined in an Output_segment, with no associated |
| 55 | // section. |
| 56 | IN_OUTPUT_SEGMENT, |
| 57 | // Symbol value is constant. |
| 58 | CONSTANT |
| 59 | }; |
| 60 | |
| 61 | // When the source is IN_OUTPUT_SEGMENT, we need to describe what |
| 62 | // the offset means. |
| 63 | enum Segment_offset_base |
| 64 | { |
| 65 | // From the start of the segment. |
| 66 | SEGMENT_START, |
| 67 | // From the end of the segment. |
| 68 | SEGMENT_END, |
| 69 | // From the filesz of the segment--i.e., after the loaded bytes |
| 70 | // but before the bytes which are allocated but zeroed. |
| 71 | SEGMENT_BSS |
| 72 | }; |
| 73 | |
| 74 | // Return the symbol name. |
| 75 | const char* |
| 76 | name() const |
| 77 | { return this->name_; } |
| 78 | |
| 79 | // Return the symbol version. This will return NULL for an |
| 80 | // unversioned symbol. |
| 81 | const char* |
| 82 | version() const |
| 83 | { return this->version_; } |
| 84 | |
| 85 | // Return the symbol source. |
| 86 | Source |
| 87 | source() const |
| 88 | { return this->source_; } |
| 89 | |
| 90 | // Return the object with which this symbol is associated. |
| 91 | Object* |
| 92 | object() const |
| 93 | { |
| 94 | gold_assert(this->source_ == FROM_OBJECT); |
| 95 | return this->u_.from_object.object; |
| 96 | } |
| 97 | |
| 98 | // Return the index of the section in the input relocatable or |
| 99 | // dynamic object file. |
| 100 | unsigned int |
| 101 | shndx() const |
| 102 | { |
| 103 | gold_assert(this->source_ == FROM_OBJECT); |
| 104 | return this->u_.from_object.shndx; |
| 105 | } |
| 106 | |
| 107 | // Return the output data section with which this symbol is |
| 108 | // associated, if the symbol was specially defined with respect to |
| 109 | // an output data section. |
| 110 | Output_data* |
| 111 | output_data() const |
| 112 | { |
| 113 | gold_assert(this->source_ == IN_OUTPUT_DATA); |
| 114 | return this->u_.in_output_data.output_data; |
| 115 | } |
| 116 | |
| 117 | // If this symbol was defined with respect to an output data |
| 118 | // section, return whether the value is an offset from end. |
| 119 | bool |
| 120 | offset_is_from_end() const |
| 121 | { |
| 122 | gold_assert(this->source_ == IN_OUTPUT_DATA); |
| 123 | return this->u_.in_output_data.offset_is_from_end; |
| 124 | } |
| 125 | |
| 126 | // Return the output segment with which this symbol is associated, |
| 127 | // if the symbol was specially defined with respect to an output |
| 128 | // segment. |
| 129 | Output_segment* |
| 130 | output_segment() const |
| 131 | { |
| 132 | gold_assert(this->source_ == IN_OUTPUT_SEGMENT); |
| 133 | return this->u_.in_output_segment.output_segment; |
| 134 | } |
| 135 | |
| 136 | // If this symbol was defined with respect to an output segment, |
| 137 | // return the offset base. |
| 138 | Segment_offset_base |
| 139 | offset_base() const |
| 140 | { |
| 141 | gold_assert(this->source_ == IN_OUTPUT_SEGMENT); |
| 142 | return this->u_.in_output_segment.offset_base; |
| 143 | } |
| 144 | |
| 145 | // Return the symbol binding. |
| 146 | elfcpp::STB |
| 147 | binding() const |
| 148 | { return this->binding_; } |
| 149 | |
| 150 | // Return the symbol type. |
| 151 | elfcpp::STT |
| 152 | type() const |
| 153 | { return this->type_; } |
| 154 | |
| 155 | // Return the symbol visibility. |
| 156 | elfcpp::STV |
| 157 | visibility() const |
| 158 | { return this->visibility_; } |
| 159 | |
| 160 | // Return the non-visibility part of the st_other field. |
| 161 | unsigned char |
| 162 | nonvis() const |
| 163 | { return this->nonvis_; } |
| 164 | |
| 165 | // Return whether this symbol is a forwarder. This will never be |
| 166 | // true of a symbol found in the hash table, but may be true of |
| 167 | // symbol pointers attached to object files. |
| 168 | bool |
| 169 | is_forwarder() const |
| 170 | { return this->is_forwarder_; } |
| 171 | |
| 172 | // Mark this symbol as a forwarder. |
| 173 | void |
| 174 | set_forwarder() |
| 175 | { this->is_forwarder_ = true; } |
| 176 | |
| 177 | // Return whether this symbol needs an entry in the dynamic symbol |
| 178 | // table. |
| 179 | bool |
| 180 | needs_dynsym_entry() const |
| 181 | { return this->needs_dynsym_entry_; } |
| 182 | |
| 183 | // Mark this symbol as needing an entry in the dynamic symbol table. |
| 184 | void |
| 185 | set_needs_dynsym_entry() |
| 186 | { this->needs_dynsym_entry_ = true; } |
| 187 | |
| 188 | // Return whether this symbol has been seen in a regular object. |
| 189 | bool |
| 190 | in_reg() const |
| 191 | { return this->in_reg_; } |
| 192 | |
| 193 | // Mark this symbol as having been seen in a regular object. |
| 194 | void |
| 195 | set_in_reg() |
| 196 | { this->in_reg_ = true; } |
| 197 | |
| 198 | // Mark this symbol as having been seen in a dynamic object. |
| 199 | void |
| 200 | set_in_dyn() |
| 201 | { this->in_dyn_ = true; } |
| 202 | |
| 203 | // Return the index of this symbol in the output file symbol table. |
| 204 | // A value of -1U means that this symbol is not going into the |
| 205 | // output file. This starts out as zero, and is set to a non-zero |
| 206 | // value by Symbol_table::finalize. It is an error to ask for the |
| 207 | // symbol table index before it has been set. |
| 208 | unsigned int |
| 209 | symtab_index() const |
| 210 | { |
| 211 | gold_assert(this->symtab_index_ != 0); |
| 212 | return this->symtab_index_; |
| 213 | } |
| 214 | |
| 215 | // Set the index of the symbol in the output file symbol table. |
| 216 | void |
| 217 | set_symtab_index(unsigned int index) |
| 218 | { |
| 219 | gold_assert(index != 0); |
| 220 | this->symtab_index_ = index; |
| 221 | } |
| 222 | |
| 223 | // Return whether this symbol already has an index in the output |
| 224 | // file symbol table. |
| 225 | bool |
| 226 | has_symtab_index() const |
| 227 | { return this->symtab_index_ != 0; } |
| 228 | |
| 229 | // Return the index of this symbol in the dynamic symbol table. A |
| 230 | // value of -1U means that this symbol is not going into the dynamic |
| 231 | // symbol table. This starts out as zero, and is set to a non-zero |
| 232 | // during Layout::finalize. It is an error to ask for the dynamic |
| 233 | // symbol table index before it has been set. |
| 234 | unsigned int |
| 235 | dynsym_index() const |
| 236 | { |
| 237 | gold_assert(this->dynsym_index_ != 0); |
| 238 | return this->dynsym_index_; |
| 239 | } |
| 240 | |
| 241 | // Set the index of the symbol in the dynamic symbol table. |
| 242 | void |
| 243 | set_dynsym_index(unsigned int index) |
| 244 | { |
| 245 | gold_assert(index != 0); |
| 246 | this->dynsym_index_ = index; |
| 247 | } |
| 248 | |
| 249 | // Return whether this symbol already has an index in the dynamic |
| 250 | // symbol table. |
| 251 | bool |
| 252 | has_dynsym_index() const |
| 253 | { return this->dynsym_index_ != 0; } |
| 254 | |
| 255 | // Return whether this symbol has an entry in the GOT section. |
| 256 | bool |
| 257 | has_got_offset() const |
| 258 | { return this->has_got_offset_; } |
| 259 | |
| 260 | // Return the offset into the GOT section of this symbol. |
| 261 | unsigned int |
| 262 | got_offset() const |
| 263 | { |
| 264 | gold_assert(this->has_got_offset()); |
| 265 | return this->got_offset_; |
| 266 | } |
| 267 | |
| 268 | // Set the GOT offset of this symbol. |
| 269 | void |
| 270 | set_got_offset(unsigned int got_offset) |
| 271 | { |
| 272 | this->has_got_offset_ = true; |
| 273 | this->got_offset_ = got_offset; |
| 274 | } |
| 275 | |
| 276 | // Return whether this symbol has an entry in the PLT section. |
| 277 | bool |
| 278 | has_plt_offset() const |
| 279 | { return this->has_plt_offset_; } |
| 280 | |
| 281 | // Return the offset into the PLT section of this symbol. |
| 282 | unsigned int |
| 283 | plt_offset() const |
| 284 | { |
| 285 | gold_assert(this->has_plt_offset()); |
| 286 | return this->plt_offset_; |
| 287 | } |
| 288 | |
| 289 | // Set the PLT offset of this symbol. |
| 290 | void |
| 291 | set_plt_offset(unsigned int plt_offset) |
| 292 | { |
| 293 | this->has_plt_offset_ = true; |
| 294 | this->plt_offset_ = plt_offset; |
| 295 | } |
| 296 | |
| 297 | // Return true if the final value of this symbol is known at link |
| 298 | // time. |
| 299 | bool |
| 300 | final_value_is_known(const General_options* options) const |
| 301 | { |
| 302 | if (options->is_shared()) |
| 303 | return false; |
| 304 | return this->source_ != FROM_OBJECT || !this->object()->is_dynamic(); |
| 305 | } |
| 306 | |
| 307 | // Return whether this is a defined symbol (not undefined or |
| 308 | // common). |
| 309 | bool |
| 310 | is_defined() const |
| 311 | { |
| 312 | return (this->source_ != FROM_OBJECT |
| 313 | || (this->shndx() != elfcpp::SHN_UNDEF |
| 314 | && this->shndx() != elfcpp::SHN_COMMON)); |
| 315 | } |
| 316 | |
| 317 | // Return true if this symbol is from a dynamic object. |
| 318 | bool |
| 319 | is_from_dynobj() const |
| 320 | { |
| 321 | return this->source_ == FROM_OBJECT && this->object()->is_dynamic(); |
| 322 | } |
| 323 | |
| 324 | // Return whether this is an undefined symbol. |
| 325 | bool |
| 326 | is_undefined() const |
| 327 | { |
| 328 | return this->source_ == FROM_OBJECT && this->shndx() == elfcpp::SHN_UNDEF; |
| 329 | } |
| 330 | |
| 331 | // Return whether this is a common symbol. |
| 332 | bool |
| 333 | is_common() const |
| 334 | { |
| 335 | return (this->source_ == FROM_OBJECT |
| 336 | && (this->shndx() == elfcpp::SHN_COMMON |
| 337 | || this->type_ == elfcpp::STT_COMMON)); |
| 338 | } |
| 339 | |
| 340 | // Return whether there should be a warning for references to this |
| 341 | // symbol. |
| 342 | bool |
| 343 | has_warning() const |
| 344 | { return this->has_warning_; } |
| 345 | |
| 346 | // Mark this symbol as having a warning. |
| 347 | void |
| 348 | set_has_warning() |
| 349 | { this->has_warning_ = true; } |
| 350 | |
| 351 | protected: |
| 352 | // Instances of this class should always be created at a specific |
| 353 | // size. |
| 354 | Symbol() |
| 355 | { memset(this, 0, sizeof *this); } |
| 356 | |
| 357 | // Initialize the general fields. |
| 358 | void |
| 359 | init_fields(const char* name, const char* version, |
| 360 | elfcpp::STT type, elfcpp::STB binding, |
| 361 | elfcpp::STV visibility, unsigned char nonvis); |
| 362 | |
| 363 | // Initialize fields from an ELF symbol in OBJECT. |
| 364 | template<int size, bool big_endian> |
| 365 | void |
| 366 | init_base(const char *name, const char* version, Object* object, |
| 367 | const elfcpp::Sym<size, big_endian>&); |
| 368 | |
| 369 | // Initialize fields for an Output_data. |
| 370 | void |
| 371 | init_base(const char* name, Output_data*, elfcpp::STT, elfcpp::STB, |
| 372 | elfcpp::STV, unsigned char nonvis, bool offset_is_from_end); |
| 373 | |
| 374 | // Initialize fields for an Output_segment. |
| 375 | void |
| 376 | init_base(const char* name, Output_segment* os, elfcpp::STT type, |
| 377 | elfcpp::STB binding, elfcpp::STV visibility, |
| 378 | unsigned char nonvis, Segment_offset_base offset_base); |
| 379 | |
| 380 | // Initialize fields for a constant. |
| 381 | void |
| 382 | init_base(const char* name, elfcpp::STT type, elfcpp::STB binding, |
| 383 | elfcpp::STV visibility, unsigned char nonvis); |
| 384 | |
| 385 | // Override existing symbol. |
| 386 | template<int size, bool big_endian> |
| 387 | void |
| 388 | override_base(const elfcpp::Sym<size, big_endian>&, Object* object, |
| 389 | const char* version); |
| 390 | |
| 391 | private: |
| 392 | Symbol(const Symbol&); |
| 393 | Symbol& operator=(const Symbol&); |
| 394 | |
| 395 | // Symbol name (expected to point into a Stringpool). |
| 396 | const char* name_; |
| 397 | // Symbol version (expected to point into a Stringpool). This may |
| 398 | // be NULL. |
| 399 | const char* version_; |
| 400 | |
| 401 | union |
| 402 | { |
| 403 | // This struct is used if SOURCE_ == FROM_OBJECT. |
| 404 | struct |
| 405 | { |
| 406 | // Object in which symbol is defined, or in which it was first |
| 407 | // seen. |
| 408 | Object* object; |
| 409 | // Section number in object_ in which symbol is defined. |
| 410 | unsigned int shndx; |
| 411 | } from_object; |
| 412 | |
| 413 | // This struct is used if SOURCE_ == IN_OUTPUT_DATA. |
| 414 | struct |
| 415 | { |
| 416 | // Output_data in which symbol is defined. Before |
| 417 | // Layout::finalize the symbol's value is an offset within the |
| 418 | // Output_data. |
| 419 | Output_data* output_data; |
| 420 | // True if the offset is from the end, false if the offset is |
| 421 | // from the beginning. |
| 422 | bool offset_is_from_end; |
| 423 | } in_output_data; |
| 424 | |
| 425 | // This struct is used if SOURCE_ == IN_OUTPUT_SEGMENT. |
| 426 | struct |
| 427 | { |
| 428 | // Output_segment in which the symbol is defined. Before |
| 429 | // Layout::finalize the symbol's value is an offset. |
| 430 | Output_segment* output_segment; |
| 431 | // The base to use for the offset before Layout::finalize. |
| 432 | Segment_offset_base offset_base; |
| 433 | } in_output_segment; |
| 434 | } u_; |
| 435 | |
| 436 | // The index of this symbol in the output file. If the symbol is |
| 437 | // not going into the output file, this value is -1U. This field |
| 438 | // starts as always holding zero. It is set to a non-zero value by |
| 439 | // Symbol_table::finalize. |
| 440 | unsigned int symtab_index_; |
| 441 | |
| 442 | // The index of this symbol in the dynamic symbol table. If the |
| 443 | // symbol is not going into the dynamic symbol table, this value is |
| 444 | // -1U. This field starts as always holding zero. It is set to a |
| 445 | // non-zero value during Layout::finalize. |
| 446 | unsigned int dynsym_index_; |
| 447 | |
| 448 | // If this symbol has an entry in the GOT section (has_got_offset_ |
| 449 | // is true), this is the offset from the start of the GOT section. |
| 450 | unsigned int got_offset_; |
| 451 | |
| 452 | // If this symbol has an entry in the PLT section (has_plt_offset_ |
| 453 | // is true), then this is the offset from the start of the PLT |
| 454 | // section. |
| 455 | unsigned int plt_offset_; |
| 456 | |
| 457 | // Symbol type. |
| 458 | elfcpp::STT type_ : 4; |
| 459 | // Symbol binding. |
| 460 | elfcpp::STB binding_ : 4; |
| 461 | // Symbol visibility. |
| 462 | elfcpp::STV visibility_ : 2; |
| 463 | // Rest of symbol st_other field. |
| 464 | unsigned int nonvis_ : 6; |
| 465 | // The type of symbol. |
| 466 | Source source_ : 3; |
| 467 | // True if this symbol always requires special target-specific |
| 468 | // handling. |
| 469 | bool is_target_special_ : 1; |
| 470 | // True if this is the default version of the symbol. |
| 471 | bool is_def_ : 1; |
| 472 | // True if this symbol really forwards to another symbol. This is |
| 473 | // used when we discover after the fact that two different entries |
| 474 | // in the hash table really refer to the same symbol. This will |
| 475 | // never be set for a symbol found in the hash table, but may be set |
| 476 | // for a symbol found in the list of symbols attached to an Object. |
| 477 | // It forwards to the symbol found in the forwarders_ map of |
| 478 | // Symbol_table. |
| 479 | bool is_forwarder_ : 1; |
| 480 | // True if this symbol needs to be in the dynamic symbol table. |
| 481 | bool needs_dynsym_entry_ : 1; |
| 482 | // True if we've seen this symbol in a regular object. |
| 483 | bool in_reg_ : 1; |
| 484 | // True if we've seen this symbol in a dynamic object. |
| 485 | bool in_dyn_ : 1; |
| 486 | // True if the symbol has an entry in the GOT section. |
| 487 | bool has_got_offset_ : 1; |
| 488 | // True if the symbol has an entry in the PLT section. |
| 489 | bool has_plt_offset_ : 1; |
| 490 | // True if there is a warning for this symbol. |
| 491 | bool has_warning_ : 1; |
| 492 | }; |
| 493 | |
| 494 | // The parts of a symbol which are size specific. Using a template |
| 495 | // derived class like this helps us use less space on a 32-bit system. |
| 496 | |
| 497 | template<int size> |
| 498 | class Sized_symbol : public Symbol |
| 499 | { |
| 500 | public: |
| 501 | typedef typename elfcpp::Elf_types<size>::Elf_Addr Value_type; |
| 502 | typedef typename elfcpp::Elf_types<size>::Elf_WXword Size_type; |
| 503 | |
| 504 | Sized_symbol() |
| 505 | { } |
| 506 | |
| 507 | // Initialize fields from an ELF symbol in OBJECT. |
| 508 | template<bool big_endian> |
| 509 | void |
| 510 | init(const char *name, const char* version, Object* object, |
| 511 | const elfcpp::Sym<size, big_endian>&); |
| 512 | |
| 513 | // Initialize fields for an Output_data. |
| 514 | void |
| 515 | init(const char* name, Output_data*, Value_type value, Size_type symsize, |
| 516 | elfcpp::STT, elfcpp::STB, elfcpp::STV, unsigned char nonvis, |
| 517 | bool offset_is_from_end); |
| 518 | |
| 519 | // Initialize fields for an Output_segment. |
| 520 | void |
| 521 | init(const char* name, Output_segment*, Value_type value, Size_type symsize, |
| 522 | elfcpp::STT, elfcpp::STB, elfcpp::STV, unsigned char nonvis, |
| 523 | Segment_offset_base offset_base); |
| 524 | |
| 525 | // Initialize fields for a constant. |
| 526 | void |
| 527 | init(const char* name, Value_type value, Size_type symsize, |
| 528 | elfcpp::STT, elfcpp::STB, elfcpp::STV, unsigned char nonvis); |
| 529 | |
| 530 | // Override existing symbol. |
| 531 | template<bool big_endian> |
| 532 | void |
| 533 | override(const elfcpp::Sym<size, big_endian>&, Object* object, |
| 534 | const char* version); |
| 535 | |
| 536 | // Return the symbol's value. |
| 537 | Value_type |
| 538 | value() const |
| 539 | { return this->value_; } |
| 540 | |
| 541 | // Return the symbol's size (we can't call this 'size' because that |
| 542 | // is a template parameter). |
| 543 | Size_type |
| 544 | symsize() const |
| 545 | { return this->symsize_; } |
| 546 | |
| 547 | // Set the symbol size. This is used when resolving common symbols. |
| 548 | void |
| 549 | set_symsize(Size_type symsize) |
| 550 | { this->symsize_ = symsize; } |
| 551 | |
| 552 | // Set the symbol value. This is called when we store the final |
| 553 | // values of the symbols into the symbol table. |
| 554 | void |
| 555 | set_value(Value_type value) |
| 556 | { this->value_ = value; } |
| 557 | |
| 558 | private: |
| 559 | Sized_symbol(const Sized_symbol&); |
| 560 | Sized_symbol& operator=(const Sized_symbol&); |
| 561 | |
| 562 | // Symbol value. Before Layout::finalize this is the offset in the |
| 563 | // input section. This is set to the final value during |
| 564 | // Layout::finalize. |
| 565 | Value_type value_; |
| 566 | // Symbol size. |
| 567 | Size_type symsize_; |
| 568 | }; |
| 569 | |
| 570 | // A struct describing a symbol defined by the linker, where the value |
| 571 | // of the symbol is defined based on an output section. This is used |
| 572 | // for symbols defined by the linker, like "_init_array_start". |
| 573 | |
| 574 | struct Define_symbol_in_section |
| 575 | { |
| 576 | // The symbol name. |
| 577 | const char* name; |
| 578 | // The name of the output section with which this symbol should be |
| 579 | // associated. If there is no output section with that name, the |
| 580 | // symbol will be defined as zero. |
| 581 | const char* output_section; |
| 582 | // The offset of the symbol within the output section. This is an |
| 583 | // offset from the start of the output section, unless start_at_end |
| 584 | // is true, in which case this is an offset from the end of the |
| 585 | // output section. |
| 586 | uint64_t value; |
| 587 | // The size of the symbol. |
| 588 | uint64_t size; |
| 589 | // The symbol type. |
| 590 | elfcpp::STT type; |
| 591 | // The symbol binding. |
| 592 | elfcpp::STB binding; |
| 593 | // The symbol visibility. |
| 594 | elfcpp::STV visibility; |
| 595 | // The rest of the st_other field. |
| 596 | unsigned char nonvis; |
| 597 | // If true, the value field is an offset from the end of the output |
| 598 | // section. |
| 599 | bool offset_is_from_end; |
| 600 | // If true, this symbol is defined only if we see a reference to it. |
| 601 | bool only_if_ref; |
| 602 | }; |
| 603 | |
| 604 | // A struct describing a symbol defined by the linker, where the value |
| 605 | // of the symbol is defined based on a segment. This is used for |
| 606 | // symbols defined by the linker, like "_end". We describe the |
| 607 | // segment with which the symbol should be associated by its |
| 608 | // characteristics. If no segment meets these characteristics, the |
| 609 | // symbol will be defined as zero. If there is more than one segment |
| 610 | // which meets these characteristics, we will use the first one. |
| 611 | |
| 612 | struct Define_symbol_in_segment |
| 613 | { |
| 614 | // The symbol name. |
| 615 | const char* name; |
| 616 | // The segment type where the symbol should be defined, typically |
| 617 | // PT_LOAD. |
| 618 | elfcpp::PT segment_type; |
| 619 | // Bitmask of segment flags which must be set. |
| 620 | elfcpp::PF segment_flags_set; |
| 621 | // Bitmask of segment flags which must be clear. |
| 622 | elfcpp::PF segment_flags_clear; |
| 623 | // The offset of the symbol within the segment. The offset is |
| 624 | // calculated from the position set by offset_base. |
| 625 | uint64_t value; |
| 626 | // The size of the symbol. |
| 627 | uint64_t size; |
| 628 | // The symbol type. |
| 629 | elfcpp::STT type; |
| 630 | // The symbol binding. |
| 631 | elfcpp::STB binding; |
| 632 | // The symbol visibility. |
| 633 | elfcpp::STV visibility; |
| 634 | // The rest of the st_other field. |
| 635 | unsigned char nonvis; |
| 636 | // The base from which we compute the offset. |
| 637 | Symbol::Segment_offset_base offset_base; |
| 638 | // If true, this symbol is defined only if we see a reference to it. |
| 639 | bool only_if_ref; |
| 640 | }; |
| 641 | |
| 642 | // This class manages warnings. Warnings are a GNU extension. When |
| 643 | // we see a section named .gnu.warning.SYM in an object file, and if |
| 644 | // we wind using the definition of SYM from that object file, then we |
| 645 | // will issue a warning for any relocation against SYM from a |
| 646 | // different object file. The text of the warning is the contents of |
| 647 | // the section. This is not precisely the definition used by the old |
| 648 | // GNU linker; the old GNU linker treated an occurrence of |
| 649 | // .gnu.warning.SYM as defining a warning symbol. A warning symbol |
| 650 | // would trigger a warning on any reference. However, it was |
| 651 | // inconsistent in that a warning in a dynamic object only triggered |
| 652 | // if there was no definition in a regular object. This linker is |
| 653 | // different in that we only issue a warning if we use the symbol |
| 654 | // definition from the same object file as the warning section. |
| 655 | |
| 656 | class Warnings |
| 657 | { |
| 658 | public: |
| 659 | Warnings() |
| 660 | : warnings_() |
| 661 | { } |
| 662 | |
| 663 | // Add a warning for symbol NAME in section SHNDX in object OBJ. |
| 664 | void |
| 665 | add_warning(Symbol_table* symtab, const char* name, Object* obj, |
| 666 | unsigned int shndx); |
| 667 | |
| 668 | // For each symbol for which we should give a warning, make a note |
| 669 | // on the symbol. |
| 670 | void |
| 671 | note_warnings(Symbol_table* symtab); |
| 672 | |
| 673 | // Issue a warning for a reference to SYM at LOCATION. |
| 674 | void |
| 675 | issue_warning(const Symbol* sym, const std::string& location) const; |
| 676 | |
| 677 | private: |
| 678 | Warnings(const Warnings&); |
| 679 | Warnings& operator=(const Warnings&); |
| 680 | |
| 681 | // What we need to know to get the warning text. |
| 682 | struct Warning_location |
| 683 | { |
| 684 | // The object the warning is in. |
| 685 | Object* object; |
| 686 | // The index of the warning section. |
| 687 | unsigned int shndx; |
| 688 | // The warning text if we have already loaded it. |
| 689 | std::string text; |
| 690 | |
| 691 | Warning_location() |
| 692 | : object(NULL), shndx(0), text() |
| 693 | { } |
| 694 | |
| 695 | void |
| 696 | set(Object* o, unsigned int s) |
| 697 | { |
| 698 | this->object = o; |
| 699 | this->shndx = s; |
| 700 | } |
| 701 | |
| 702 | void |
| 703 | set_text(const char* t, off_t l) |
| 704 | { this->text.assign(t, l); } |
| 705 | }; |
| 706 | |
| 707 | // A mapping from warning symbol names (canonicalized in |
| 708 | // Symbol_table's namepool_ field) to |
| 709 | typedef Unordered_map<const char*, Warning_location> Warning_table; |
| 710 | |
| 711 | Warning_table warnings_; |
| 712 | }; |
| 713 | |
| 714 | // The main linker symbol table. |
| 715 | |
| 716 | class Symbol_table |
| 717 | { |
| 718 | public: |
| 719 | Symbol_table(); |
| 720 | |
| 721 | ~Symbol_table(); |
| 722 | |
| 723 | // Add COUNT external symbols from the relocatable object RELOBJ to |
| 724 | // the symbol table. SYMS is the symbols, SYM_NAMES is their names, |
| 725 | // SYM_NAME_SIZE is the size of SYM_NAMES. This sets SYMPOINTERS to |
| 726 | // point to the symbols in the symbol table. |
| 727 | template<int size, bool big_endian> |
| 728 | void |
| 729 | add_from_relobj(Sized_relobj<size, big_endian>* relobj, |
| 730 | const unsigned char* syms, size_t count, |
| 731 | const char* sym_names, size_t sym_name_size, |
| 732 | Symbol** sympointers); |
| 733 | |
| 734 | // Add COUNT dynamic symbols from the dynamic object DYNOBJ to the |
| 735 | // symbol table. SYMS is the symbols. SYM_NAMES is their names. |
| 736 | // SYM_NAME_SIZE is the size of SYM_NAMES. The other parameters are |
| 737 | // symbol version data. |
| 738 | template<int size, bool big_endian> |
| 739 | void |
| 740 | add_from_dynobj(Sized_dynobj<size, big_endian>* dynobj, |
| 741 | const unsigned char* syms, size_t count, |
| 742 | const char* sym_names, size_t sym_name_size, |
| 743 | const unsigned char* versym, size_t versym_size, |
| 744 | const std::vector<const char*>*); |
| 745 | |
| 746 | // Define a special symbol based on an Output_data. It is a |
| 747 | // multiple definition error if this symbol is already defined. |
| 748 | Symbol* |
| 749 | define_in_output_data(const Target*, const char* name, const char* version, |
| 750 | Output_data*, uint64_t value, uint64_t symsize, |
| 751 | elfcpp::STT type, elfcpp::STB binding, |
| 752 | elfcpp::STV visibility, unsigned char nonvis, |
| 753 | bool offset_is_from_end, bool only_if_ref); |
| 754 | |
| 755 | // Define a special symbol based on an Output_segment. It is a |
| 756 | // multiple definition error if this symbol is already defined. |
| 757 | Symbol* |
| 758 | define_in_output_segment(const Target*, const char* name, |
| 759 | const char* version, Output_segment*, |
| 760 | uint64_t value, uint64_t symsize, |
| 761 | elfcpp::STT type, elfcpp::STB binding, |
| 762 | elfcpp::STV visibility, unsigned char nonvis, |
| 763 | Symbol::Segment_offset_base, bool only_if_ref); |
| 764 | |
| 765 | // Define a special symbol with a constant value. It is a multiple |
| 766 | // definition error if this symbol is already defined. |
| 767 | Symbol* |
| 768 | define_as_constant(const Target*, const char* name, const char* version, |
| 769 | uint64_t value, uint64_t symsize, elfcpp::STT type, |
| 770 | elfcpp::STB binding, elfcpp::STV visibility, |
| 771 | unsigned char nonvis, bool only_if_ref); |
| 772 | |
| 773 | // Define a set of symbols in output sections. |
| 774 | void |
| 775 | define_symbols(const Layout*, const Target*, int count, |
| 776 | const Define_symbol_in_section*); |
| 777 | |
| 778 | // Define a set of symbols in output segments. |
| 779 | void |
| 780 | define_symbols(const Layout*, const Target*, int count, |
| 781 | const Define_symbol_in_segment*); |
| 782 | |
| 783 | // Look up a symbol. |
| 784 | Symbol* |
| 785 | lookup(const char*, const char* version = NULL) const; |
| 786 | |
| 787 | // Return the real symbol associated with the forwarder symbol FROM. |
| 788 | Symbol* |
| 789 | resolve_forwards(const Symbol* from) const; |
| 790 | |
| 791 | // Return the bitsize (32 or 64) of the symbols in the table. |
| 792 | int |
| 793 | get_size() const |
| 794 | { return this->size_; } |
| 795 | |
| 796 | // Return the sized version of a symbol in this table. |
| 797 | template<int size> |
| 798 | Sized_symbol<size>* |
| 799 | get_sized_symbol(Symbol* ACCEPT_SIZE) const; |
| 800 | |
| 801 | template<int size> |
| 802 | const Sized_symbol<size>* |
| 803 | get_sized_symbol(const Symbol* ACCEPT_SIZE) const; |
| 804 | |
| 805 | // Return the count of undefined symbols seen. |
| 806 | int |
| 807 | saw_undefined() const |
| 808 | { return this->saw_undefined_; } |
| 809 | |
| 810 | // Allocate the common symbols |
| 811 | void |
| 812 | allocate_commons(const General_options&, Layout*); |
| 813 | |
| 814 | // Add a warning for symbol NAME in section SHNDX in object OBJ. |
| 815 | void |
| 816 | add_warning(const char* name, Object* obj, unsigned int shndx) |
| 817 | { this->warnings_.add_warning(this, name, obj, shndx); } |
| 818 | |
| 819 | // Canonicalize a symbol name for use in the hash table. |
| 820 | const char* |
| 821 | canonicalize_name(const char* name) |
| 822 | { return this->namepool_.add(name, NULL); } |
| 823 | |
| 824 | // Possibly issue a warning for a reference to SYM at LOCATION which |
| 825 | // is in OBJ. |
| 826 | void |
| 827 | issue_warning(const Symbol* sym, const std::string& location) const |
| 828 | { this->warnings_.issue_warning(sym, location); } |
| 829 | |
| 830 | // Set the dynamic symbol indexes. INDEX is the index of the first |
| 831 | // global dynamic symbol. Pointers to the symbols are stored into |
| 832 | // the vector. The names are stored into the Stringpool. This |
| 833 | // returns an updated dynamic symbol index. |
| 834 | unsigned int |
| 835 | set_dynsym_indexes(const General_options*, const Target*, unsigned int index, |
| 836 | std::vector<Symbol*>*, Stringpool*, Versions*); |
| 837 | |
| 838 | // Finalize the symbol table after we have set the final addresses |
| 839 | // of all the input sections. This sets the final symbol indexes, |
| 840 | // values and adds the names to *POOL. INDEX is the index of the |
| 841 | // first global symbol. OFF is the file offset of the global symbol |
| 842 | // table, DYNOFF is the offset of the globals in the dynamic symbol |
| 843 | // table, DYN_GLOBAL_INDEX is the index of the first global dynamic |
| 844 | // symbol, and DYNCOUNT is the number of global dynamic symbols. |
| 845 | // This records the parameters, and returns the new file offset. |
| 846 | off_t |
| 847 | finalize(unsigned int index, off_t off, off_t dynoff, |
| 848 | size_t dyn_global_index, size_t dyncount, Stringpool* pool); |
| 849 | |
| 850 | // Write out the global symbols. |
| 851 | void |
| 852 | write_globals(const Target*, const Stringpool*, const Stringpool*, |
| 853 | Output_file*) const; |
| 854 | |
| 855 | // Write out a section symbol. Return the updated offset. |
| 856 | void |
| 857 | write_section_symbol(const Target*, const Output_section*, Output_file*, |
| 858 | off_t) const; |
| 859 | |
| 860 | private: |
| 861 | Symbol_table(const Symbol_table&); |
| 862 | Symbol_table& operator=(const Symbol_table&); |
| 863 | |
| 864 | // Set the size (32 or 64) of the symbols in the table. |
| 865 | void |
| 866 | set_size(int size) |
| 867 | { this->size_ = size; } |
| 868 | |
| 869 | // Make FROM a forwarder symbol to TO. |
| 870 | void |
| 871 | make_forwarder(Symbol* from, Symbol* to); |
| 872 | |
| 873 | // Add a symbol. |
| 874 | template<int size, bool big_endian> |
| 875 | Symbol* |
| 876 | add_from_object(Object*, const char *name, Stringpool::Key name_key, |
| 877 | const char *version, Stringpool::Key version_key, |
| 878 | bool def, const elfcpp::Sym<size, big_endian>& sym); |
| 879 | |
| 880 | // Resolve symbols. |
| 881 | template<int size, bool big_endian> |
| 882 | static void |
| 883 | resolve(Sized_symbol<size>* to, |
| 884 | const elfcpp::Sym<size, big_endian>& sym, |
| 885 | Object*, const char* version); |
| 886 | |
| 887 | template<int size, bool big_endian> |
| 888 | static void |
| 889 | resolve(Sized_symbol<size>* to, const Sized_symbol<size>* from, |
| 890 | const char* version ACCEPT_SIZE_ENDIAN); |
| 891 | |
| 892 | // Define a special symbol. |
| 893 | template<int size, bool big_endian> |
| 894 | Sized_symbol<size>* |
| 895 | define_special_symbol(const Target* target, const char* name, |
| 896 | const char* version, bool only_if_ref |
| 897 | ACCEPT_SIZE_ENDIAN); |
| 898 | |
| 899 | // Define a symbol in an Output_data, sized version. |
| 900 | template<int size> |
| 901 | Sized_symbol<size>* |
| 902 | do_define_in_output_data(const Target*, const char* name, |
| 903 | const char* version, Output_data*, |
| 904 | typename elfcpp::Elf_types<size>::Elf_Addr value, |
| 905 | typename elfcpp::Elf_types<size>::Elf_WXword ssize, |
| 906 | elfcpp::STT type, elfcpp::STB binding, |
| 907 | elfcpp::STV visibility, unsigned char nonvis, |
| 908 | bool offset_is_from_end, bool only_if_ref); |
| 909 | |
| 910 | // Define a symbol in an Output_segment, sized version. |
| 911 | template<int size> |
| 912 | Sized_symbol<size>* |
| 913 | do_define_in_output_segment( |
| 914 | const Target*, const char* name, const char* version, Output_segment* os, |
| 915 | typename elfcpp::Elf_types<size>::Elf_Addr value, |
| 916 | typename elfcpp::Elf_types<size>::Elf_WXword ssize, |
| 917 | elfcpp::STT type, elfcpp::STB binding, |
| 918 | elfcpp::STV visibility, unsigned char nonvis, |
| 919 | Symbol::Segment_offset_base offset_base, bool only_if_ref); |
| 920 | |
| 921 | // Define a symbol as a constant, sized version. |
| 922 | template<int size> |
| 923 | Sized_symbol<size>* |
| 924 | do_define_as_constant( |
| 925 | const Target*, const char* name, const char* version, |
| 926 | typename elfcpp::Elf_types<size>::Elf_Addr value, |
| 927 | typename elfcpp::Elf_types<size>::Elf_WXword ssize, |
| 928 | elfcpp::STT type, elfcpp::STB binding, |
| 929 | elfcpp::STV visibility, unsigned char nonvis, |
| 930 | bool only_if_ref); |
| 931 | |
| 932 | // Allocate the common symbols, sized version. |
| 933 | template<int size> |
| 934 | void |
| 935 | do_allocate_commons(const General_options&, Layout*); |
| 936 | |
| 937 | // Finalize symbols specialized for size. |
| 938 | template<int size> |
| 939 | off_t |
| 940 | sized_finalize(unsigned int, off_t, Stringpool*); |
| 941 | |
| 942 | // Write globals specialized for size and endianness. |
| 943 | template<int size, bool big_endian> |
| 944 | void |
| 945 | sized_write_globals(const Target*, const Stringpool*, const Stringpool*, |
| 946 | Output_file*) const; |
| 947 | |
| 948 | // Write out a symbol to P. |
| 949 | template<int size, bool big_endian> |
| 950 | void |
| 951 | sized_write_symbol(Sized_symbol<size>*, unsigned int shndx, |
| 952 | const Stringpool*, unsigned char* p |
| 953 | ACCEPT_SIZE_ENDIAN) const; |
| 954 | |
| 955 | // Write out a section symbol, specialized for size and endianness. |
| 956 | template<int size, bool big_endian> |
| 957 | void |
| 958 | sized_write_section_symbol(const Output_section*, Output_file*, off_t) const; |
| 959 | |
| 960 | // The type of the symbol hash table. |
| 961 | |
| 962 | typedef std::pair<Stringpool::Key, Stringpool::Key> Symbol_table_key; |
| 963 | |
| 964 | struct Symbol_table_hash |
| 965 | { |
| 966 | size_t |
| 967 | operator()(const Symbol_table_key&) const; |
| 968 | }; |
| 969 | |
| 970 | struct Symbol_table_eq |
| 971 | { |
| 972 | bool |
| 973 | operator()(const Symbol_table_key&, const Symbol_table_key&) const; |
| 974 | }; |
| 975 | |
| 976 | typedef Unordered_map<Symbol_table_key, Symbol*, Symbol_table_hash, |
| 977 | Symbol_table_eq> Symbol_table_type; |
| 978 | |
| 979 | // The type of the list of common symbols. |
| 980 | |
| 981 | typedef std::vector<Symbol*> Commons_type; |
| 982 | |
| 983 | // The size of the symbols in the symbol table (32 or 64). |
| 984 | int size_; |
| 985 | |
| 986 | // We increment this every time we see a new undefined symbol, for |
| 987 | // use in archive groups. |
| 988 | int saw_undefined_; |
| 989 | |
| 990 | // The index of the first global symbol in the output file. |
| 991 | unsigned int first_global_index_; |
| 992 | |
| 993 | // The file offset within the output symtab section where we should |
| 994 | // write the table. |
| 995 | off_t offset_; |
| 996 | |
| 997 | // The number of global symbols we want to write out. |
| 998 | size_t output_count_; |
| 999 | |
| 1000 | // The file offset of the global dynamic symbols, or 0 if none. |
| 1001 | off_t dynamic_offset_; |
| 1002 | |
| 1003 | // The index of the first global dynamic symbol. |
| 1004 | unsigned int first_dynamic_global_index_; |
| 1005 | |
| 1006 | // The number of global dynamic symbols, or 0 if none. |
| 1007 | off_t dynamic_count_; |
| 1008 | |
| 1009 | // The symbol hash table. |
| 1010 | Symbol_table_type table_; |
| 1011 | |
| 1012 | // A pool of symbol names. This is used for all global symbols. |
| 1013 | // Entries in the hash table point into this pool. |
| 1014 | Stringpool namepool_; |
| 1015 | |
| 1016 | // Forwarding symbols. |
| 1017 | Unordered_map<const Symbol*, Symbol*> forwarders_; |
| 1018 | |
| 1019 | // We don't expect there to be very many common symbols, so we keep |
| 1020 | // a list of them. When we find a common symbol we add it to this |
| 1021 | // list. It is possible that by the time we process the list the |
| 1022 | // symbol is no longer a common symbol. It may also have become a |
| 1023 | // forwarder. |
| 1024 | Commons_type commons_; |
| 1025 | |
| 1026 | // Manage symbol warnings. |
| 1027 | Warnings warnings_; |
| 1028 | }; |
| 1029 | |
| 1030 | // We inline get_sized_symbol for efficiency. |
| 1031 | |
| 1032 | template<int size> |
| 1033 | Sized_symbol<size>* |
| 1034 | Symbol_table::get_sized_symbol(Symbol* sym ACCEPT_SIZE) const |
| 1035 | { |
| 1036 | gold_assert(size == this->get_size()); |
| 1037 | return static_cast<Sized_symbol<size>*>(sym); |
| 1038 | } |
| 1039 | |
| 1040 | template<int size> |
| 1041 | const Sized_symbol<size>* |
| 1042 | Symbol_table::get_sized_symbol(const Symbol* sym ACCEPT_SIZE) const |
| 1043 | { |
| 1044 | gold_assert(size == this->get_size()); |
| 1045 | return static_cast<const Sized_symbol<size>*>(sym); |
| 1046 | } |
| 1047 | |
| 1048 | } // End namespace gold. |
| 1049 | |
| 1050 | #endif // !defined(GOLD_SYMTAB_H) |