| 1 | // reloc.h -- relocate input files for gold -*- C++ -*- |
| 2 | |
| 3 | // Copyright 2006, 2007 Free Software Foundation, Inc. |
| 4 | // Written by Ian Lance Taylor <iant@google.com>. |
| 5 | |
| 6 | // This file is part of gold. |
| 7 | |
| 8 | // This program is free software; you can redistribute it and/or modify |
| 9 | // it under the terms of the GNU General Public License as published by |
| 10 | // the Free Software Foundation; either version 3 of the License, or |
| 11 | // (at your option) any later version. |
| 12 | |
| 13 | // This program is distributed in the hope that it will be useful, |
| 14 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | // GNU General Public License for more details. |
| 17 | |
| 18 | // You should have received a copy of the GNU General Public License |
| 19 | // along with this program; if not, write to the Free Software |
| 20 | // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
| 21 | // MA 02110-1301, USA. |
| 22 | |
| 23 | #ifndef GOLD_RELOC_H |
| 24 | #define GOLD_RELOC_H |
| 25 | |
| 26 | #include <vector> |
| 27 | #include <byteswap.h> |
| 28 | |
| 29 | #include "elfcpp.h" |
| 30 | #include "workqueue.h" |
| 31 | |
| 32 | namespace gold |
| 33 | { |
| 34 | |
| 35 | class General_options; |
| 36 | class Object; |
| 37 | class Relobj; |
| 38 | class Read_relocs_data; |
| 39 | class Symbol; |
| 40 | class Layout; |
| 41 | class Output_section; |
| 42 | |
| 43 | template<int size> |
| 44 | class Sized_symbol; |
| 45 | |
| 46 | template<int size, bool big_endian> |
| 47 | class Sized_relobj; |
| 48 | |
| 49 | template<int size> |
| 50 | class Symbol_value; |
| 51 | |
| 52 | template<int sh_type, bool dynamic, int size, bool big_endian> |
| 53 | class Output_data_reloc; |
| 54 | |
| 55 | // A class to read the relocations for an object file, and then queue |
| 56 | // up a task to see if they require any GOT/PLT/COPY relocations in |
| 57 | // the symbol table. |
| 58 | |
| 59 | class Read_relocs : public Task |
| 60 | { |
| 61 | public: |
| 62 | // SYMTAB_LOCK is used to lock the symbol table. BLOCKER should be |
| 63 | // unblocked when the Scan_relocs task completes. |
| 64 | Read_relocs(const General_options& options, Symbol_table* symtab, |
| 65 | Layout* layout, Relobj* object, Task_token* symtab_lock, |
| 66 | Task_token* blocker) |
| 67 | : options_(options), symtab_(symtab), layout_(layout), object_(object), |
| 68 | symtab_lock_(symtab_lock), blocker_(blocker) |
| 69 | { } |
| 70 | |
| 71 | // The standard Task methods. |
| 72 | |
| 73 | Task_token* |
| 74 | is_runnable(); |
| 75 | |
| 76 | void |
| 77 | locks(Task_locker*); |
| 78 | |
| 79 | void |
| 80 | run(Workqueue*); |
| 81 | |
| 82 | std::string |
| 83 | get_name() const; |
| 84 | |
| 85 | private: |
| 86 | const General_options& options_; |
| 87 | Symbol_table* symtab_; |
| 88 | Layout* layout_; |
| 89 | Relobj* object_; |
| 90 | Task_token* symtab_lock_; |
| 91 | Task_token* blocker_; |
| 92 | }; |
| 93 | |
| 94 | // Scan the relocations for an object to see if they require any |
| 95 | // GOT/PLT/COPY relocations. |
| 96 | |
| 97 | class Scan_relocs : public Task |
| 98 | { |
| 99 | public: |
| 100 | // SYMTAB_LOCK is used to lock the symbol table. BLOCKER should be |
| 101 | // unblocked when the task completes. |
| 102 | Scan_relocs(const General_options& options, Symbol_table* symtab, |
| 103 | Layout* layout, Relobj* object, Read_relocs_data* rd, |
| 104 | Task_token* symtab_lock, Task_token* blocker) |
| 105 | : options_(options), symtab_(symtab), layout_(layout), object_(object), |
| 106 | rd_(rd), symtab_lock_(symtab_lock), blocker_(blocker) |
| 107 | { } |
| 108 | |
| 109 | // The standard Task methods. |
| 110 | |
| 111 | Task_token* |
| 112 | is_runnable(); |
| 113 | |
| 114 | void |
| 115 | locks(Task_locker*); |
| 116 | |
| 117 | void |
| 118 | run(Workqueue*); |
| 119 | |
| 120 | std::string |
| 121 | get_name() const; |
| 122 | |
| 123 | private: |
| 124 | const General_options& options_; |
| 125 | Symbol_table* symtab_; |
| 126 | Layout* layout_; |
| 127 | Relobj* object_; |
| 128 | Read_relocs_data* rd_; |
| 129 | Task_token* symtab_lock_; |
| 130 | Task_token* blocker_; |
| 131 | }; |
| 132 | |
| 133 | // A class to perform all the relocations for an object file. |
| 134 | |
| 135 | class Relocate_task : public Task |
| 136 | { |
| 137 | public: |
| 138 | Relocate_task(const General_options& options, const Symbol_table* symtab, |
| 139 | const Layout* layout, Relobj* object, Output_file* of, |
| 140 | Task_token* input_sections_blocker, |
| 141 | Task_token* output_sections_blocker, Task_token* final_blocker) |
| 142 | : options_(options), symtab_(symtab), layout_(layout), object_(object), |
| 143 | of_(of), input_sections_blocker_(input_sections_blocker), |
| 144 | output_sections_blocker_(output_sections_blocker), |
| 145 | final_blocker_(final_blocker) |
| 146 | { } |
| 147 | |
| 148 | // The standard Task methods. |
| 149 | |
| 150 | Task_token* |
| 151 | is_runnable(); |
| 152 | |
| 153 | void |
| 154 | locks(Task_locker*); |
| 155 | |
| 156 | void |
| 157 | run(Workqueue*); |
| 158 | |
| 159 | std::string |
| 160 | get_name() const; |
| 161 | |
| 162 | private: |
| 163 | const General_options& options_; |
| 164 | const Symbol_table* symtab_; |
| 165 | const Layout* layout_; |
| 166 | Relobj* object_; |
| 167 | Output_file* of_; |
| 168 | Task_token* input_sections_blocker_; |
| 169 | Task_token* output_sections_blocker_; |
| 170 | Task_token* final_blocker_; |
| 171 | }; |
| 172 | |
| 173 | // Standard relocation routines which are used on many targets. Here |
| 174 | // SIZE and BIG_ENDIAN refer to the target, not the relocation type. |
| 175 | |
| 176 | template<int size, bool big_endian> |
| 177 | class Relocate_functions |
| 178 | { |
| 179 | private: |
| 180 | // Do a simple relocation with the addend in the section contents. |
| 181 | // VALSIZE is the size of the value. |
| 182 | template<int valsize> |
| 183 | static inline void |
| 184 | rel(unsigned char* view, |
| 185 | typename elfcpp::Swap<valsize, big_endian>::Valtype value) |
| 186 | { |
| 187 | typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype; |
| 188 | Valtype* wv = reinterpret_cast<Valtype*>(view); |
| 189 | Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv); |
| 190 | elfcpp::Swap<valsize, big_endian>::writeval(wv, x + value); |
| 191 | } |
| 192 | |
| 193 | // Do a simple relocation using a Symbol_value with the addend in |
| 194 | // the section contents. VALSIZE is the size of the value to |
| 195 | // relocate. |
| 196 | template<int valsize> |
| 197 | static inline void |
| 198 | rel(unsigned char* view, |
| 199 | const Sized_relobj<size, big_endian>* object, |
| 200 | const Symbol_value<size>* psymval) |
| 201 | { |
| 202 | typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype; |
| 203 | Valtype* wv = reinterpret_cast<Valtype*>(view); |
| 204 | Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv); |
| 205 | x = psymval->value(object, x); |
| 206 | elfcpp::Swap<valsize, big_endian>::writeval(wv, x); |
| 207 | } |
| 208 | |
| 209 | // Do a simple relocation with the addend in the relocation. |
| 210 | // VALSIZE is the size of the value. |
| 211 | template<int valsize> |
| 212 | static inline void |
| 213 | rela(unsigned char* view, |
| 214 | typename elfcpp::Swap<valsize, big_endian>::Valtype value, |
| 215 | typename elfcpp::Swap<valsize, big_endian>::Valtype addend) |
| 216 | { |
| 217 | typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype; |
| 218 | Valtype* wv = reinterpret_cast<Valtype*>(view); |
| 219 | elfcpp::Swap<valsize, big_endian>::writeval(wv, value + addend); |
| 220 | } |
| 221 | |
| 222 | // Do a simple relocation using a symbol value with the addend in |
| 223 | // the relocation. VALSIZE is the size of the value. |
| 224 | template<int valsize> |
| 225 | static inline void |
| 226 | rela(unsigned char* view, |
| 227 | const Sized_relobj<size, big_endian>* object, |
| 228 | const Symbol_value<size>* psymval, |
| 229 | typename elfcpp::Swap<valsize, big_endian>::Valtype addend) |
| 230 | { |
| 231 | typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype; |
| 232 | Valtype* wv = reinterpret_cast<Valtype*>(view); |
| 233 | Valtype x = psymval->value(object, addend); |
| 234 | elfcpp::Swap<valsize, big_endian>::writeval(wv, x); |
| 235 | } |
| 236 | |
| 237 | // Do a simple PC relative relocation with the addend in the section |
| 238 | // contents. VALSIZE is the size of the value. |
| 239 | template<int valsize> |
| 240 | static inline void |
| 241 | pcrel(unsigned char* view, |
| 242 | typename elfcpp::Swap<valsize, big_endian>::Valtype value, |
| 243 | typename elfcpp::Elf_types<size>::Elf_Addr address) |
| 244 | { |
| 245 | typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype; |
| 246 | Valtype* wv = reinterpret_cast<Valtype*>(view); |
| 247 | Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv); |
| 248 | elfcpp::Swap<valsize, big_endian>::writeval(wv, x + value - address); |
| 249 | } |
| 250 | |
| 251 | // Do a simple PC relative relocation with a Symbol_value with the |
| 252 | // addend in the section contents. VALSIZE is the size of the |
| 253 | // value. |
| 254 | template<int valsize> |
| 255 | static inline void |
| 256 | pcrel(unsigned char* view, |
| 257 | const Sized_relobj<size, big_endian>* object, |
| 258 | const Symbol_value<size>* psymval, |
| 259 | typename elfcpp::Elf_types<size>::Elf_Addr address) |
| 260 | { |
| 261 | typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype; |
| 262 | Valtype* wv = reinterpret_cast<Valtype*>(view); |
| 263 | Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv); |
| 264 | x = psymval->value(object, x); |
| 265 | elfcpp::Swap<valsize, big_endian>::writeval(wv, x - address); |
| 266 | } |
| 267 | |
| 268 | // Do a simple PC relative relocation with the addend in the |
| 269 | // relocation. VALSIZE is the size of the value. |
| 270 | template<int valsize> |
| 271 | static inline void |
| 272 | pcrela(unsigned char* view, |
| 273 | typename elfcpp::Swap<valsize, big_endian>::Valtype value, |
| 274 | typename elfcpp::Swap<valsize, big_endian>::Valtype addend, |
| 275 | typename elfcpp::Elf_types<size>::Elf_Addr address) |
| 276 | { |
| 277 | typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype; |
| 278 | Valtype* wv = reinterpret_cast<Valtype*>(view); |
| 279 | elfcpp::Swap<valsize, big_endian>::writeval(wv, value + addend - address); |
| 280 | } |
| 281 | |
| 282 | // Do a simple PC relative relocation with a Symbol_value with the |
| 283 | // addend in the relocation. VALSIZE is the size of the value. |
| 284 | template<int valsize> |
| 285 | static inline void |
| 286 | pcrela(unsigned char* view, |
| 287 | const Sized_relobj<size, big_endian>* object, |
| 288 | const Symbol_value<size>* psymval, |
| 289 | typename elfcpp::Swap<valsize, big_endian>::Valtype addend, |
| 290 | typename elfcpp::Elf_types<size>::Elf_Addr address) |
| 291 | { |
| 292 | typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype; |
| 293 | Valtype* wv = reinterpret_cast<Valtype*>(view); |
| 294 | Valtype x = psymval->value(object, addend); |
| 295 | elfcpp::Swap<valsize, big_endian>::writeval(wv, x - address); |
| 296 | } |
| 297 | |
| 298 | typedef Relocate_functions<size, big_endian> This; |
| 299 | |
| 300 | public: |
| 301 | // Do a simple 8-bit REL relocation with the addend in the section |
| 302 | // contents. |
| 303 | static inline void |
| 304 | rel8(unsigned char* view, unsigned char value) |
| 305 | { This::template rel<8>(view, value); } |
| 306 | |
| 307 | static inline void |
| 308 | rel8(unsigned char* view, |
| 309 | const Sized_relobj<size, big_endian>* object, |
| 310 | const Symbol_value<size>* psymval) |
| 311 | { This::template rel<8>(view, object, psymval); } |
| 312 | |
| 313 | // Do an 8-bit RELA relocation with the addend in the relocation. |
| 314 | static inline void |
| 315 | rela8(unsigned char* view, unsigned char value, unsigned char addend) |
| 316 | { This::template rela<8>(view, value, addend); } |
| 317 | |
| 318 | static inline void |
| 319 | rela8(unsigned char* view, |
| 320 | const Sized_relobj<size, big_endian>* object, |
| 321 | const Symbol_value<size>* psymval, |
| 322 | unsigned char addend) |
| 323 | { This::template rela<8>(view, object, psymval, addend); } |
| 324 | |
| 325 | // Do a simple 8-bit PC relative relocation with the addend in the |
| 326 | // section contents. |
| 327 | static inline void |
| 328 | pcrel8(unsigned char* view, unsigned char value, |
| 329 | typename elfcpp::Elf_types<size>::Elf_Addr address) |
| 330 | { This::template pcrel<8>(view, value, address); } |
| 331 | |
| 332 | static inline void |
| 333 | pcrel8(unsigned char* view, |
| 334 | const Sized_relobj<size, big_endian>* object, |
| 335 | const Symbol_value<size>* psymval, |
| 336 | typename elfcpp::Elf_types<size>::Elf_Addr address) |
| 337 | { This::template pcrel<8>(view, object, psymval, address); } |
| 338 | |
| 339 | // Do a simple 8-bit PC relative RELA relocation with the addend in |
| 340 | // the reloc. |
| 341 | static inline void |
| 342 | pcrela8(unsigned char* view, unsigned char value, unsigned char addend, |
| 343 | typename elfcpp::Elf_types<size>::Elf_Addr address) |
| 344 | { This::template pcrela<8>(view, value, addend, address); } |
| 345 | |
| 346 | static inline void |
| 347 | pcrela8(unsigned char* view, |
| 348 | const Sized_relobj<size, big_endian>* object, |
| 349 | const Symbol_value<size>* psymval, |
| 350 | unsigned char addend, |
| 351 | typename elfcpp::Elf_types<size>::Elf_Addr address) |
| 352 | { This::template pcrela<8>(view, object, psymval, addend, address); } |
| 353 | |
| 354 | // Do a simple 16-bit REL relocation with the addend in the section |
| 355 | // contents. |
| 356 | static inline void |
| 357 | rel16(unsigned char* view, elfcpp::Elf_Half value) |
| 358 | { This::template rel<16>(view, value); } |
| 359 | |
| 360 | static inline void |
| 361 | rel16(unsigned char* view, |
| 362 | const Sized_relobj<size, big_endian>* object, |
| 363 | const Symbol_value<size>* psymval) |
| 364 | { This::template rel<16>(view, object, psymval); } |
| 365 | |
| 366 | // Do an 16-bit RELA relocation with the addend in the relocation. |
| 367 | static inline void |
| 368 | rela16(unsigned char* view, elfcpp::Elf_Half value, elfcpp::Elf_Half addend) |
| 369 | { This::template rela<16>(view, value, addend); } |
| 370 | |
| 371 | static inline void |
| 372 | rela16(unsigned char* view, |
| 373 | const Sized_relobj<size, big_endian>* object, |
| 374 | const Symbol_value<size>* psymval, |
| 375 | elfcpp::Elf_Half addend) |
| 376 | { This::template rela<16>(view, object, psymval, addend); } |
| 377 | |
| 378 | // Do a simple 16-bit PC relative REL relocation with the addend in |
| 379 | // the section contents. |
| 380 | static inline void |
| 381 | pcrel16(unsigned char* view, elfcpp::Elf_Half value, |
| 382 | typename elfcpp::Elf_types<size>::Elf_Addr address) |
| 383 | { This::template pcrel<16>(view, value, address); } |
| 384 | |
| 385 | static inline void |
| 386 | pcrel16(unsigned char* view, |
| 387 | const Sized_relobj<size, big_endian>* object, |
| 388 | const Symbol_value<size>* psymval, |
| 389 | typename elfcpp::Elf_types<size>::Elf_Addr address) |
| 390 | { This::template pcrel<16>(view, object, psymval, address); } |
| 391 | |
| 392 | // Do a simple 16-bit PC relative RELA relocation with the addend in |
| 393 | // the reloc. |
| 394 | static inline void |
| 395 | pcrela16(unsigned char* view, elfcpp::Elf_Half value, |
| 396 | elfcpp::Elf_Half addend, |
| 397 | typename elfcpp::Elf_types<size>::Elf_Addr address) |
| 398 | { This::template pcrela<16>(view, value, addend, address); } |
| 399 | |
| 400 | static inline void |
| 401 | pcrela16(unsigned char* view, |
| 402 | const Sized_relobj<size, big_endian>* object, |
| 403 | const Symbol_value<size>* psymval, |
| 404 | elfcpp::Elf_Half addend, |
| 405 | typename elfcpp::Elf_types<size>::Elf_Addr address) |
| 406 | { This::template pcrela<16>(view, object, psymval, addend, address); } |
| 407 | |
| 408 | // Do a simple 32-bit REL relocation with the addend in the section |
| 409 | // contents. |
| 410 | static inline void |
| 411 | rel32(unsigned char* view, elfcpp::Elf_Word value) |
| 412 | { This::template rel<32>(view, value); } |
| 413 | |
| 414 | static inline void |
| 415 | rel32(unsigned char* view, |
| 416 | const Sized_relobj<size, big_endian>* object, |
| 417 | const Symbol_value<size>* psymval) |
| 418 | { This::template rel<32>(view, object, psymval); } |
| 419 | |
| 420 | // Do an 32-bit RELA relocation with the addend in the relocation. |
| 421 | static inline void |
| 422 | rela32(unsigned char* view, elfcpp::Elf_Word value, elfcpp::Elf_Word addend) |
| 423 | { This::template rela<32>(view, value, addend); } |
| 424 | |
| 425 | static inline void |
| 426 | rela32(unsigned char* view, |
| 427 | const Sized_relobj<size, big_endian>* object, |
| 428 | const Symbol_value<size>* psymval, |
| 429 | elfcpp::Elf_Word addend) |
| 430 | { This::template rela<32>(view, object, psymval, addend); } |
| 431 | |
| 432 | // Do a simple 32-bit PC relative REL relocation with the addend in |
| 433 | // the section contents. |
| 434 | static inline void |
| 435 | pcrel32(unsigned char* view, elfcpp::Elf_Word value, |
| 436 | typename elfcpp::Elf_types<size>::Elf_Addr address) |
| 437 | { This::template pcrel<32>(view, value, address); } |
| 438 | |
| 439 | static inline void |
| 440 | pcrel32(unsigned char* view, |
| 441 | const Sized_relobj<size, big_endian>* object, |
| 442 | const Symbol_value<size>* psymval, |
| 443 | typename elfcpp::Elf_types<size>::Elf_Addr address) |
| 444 | { This::template pcrel<32>(view, object, psymval, address); } |
| 445 | |
| 446 | // Do a simple 32-bit PC relative RELA relocation with the addend in |
| 447 | // the relocation. |
| 448 | static inline void |
| 449 | pcrela32(unsigned char* view, elfcpp::Elf_Word value, |
| 450 | elfcpp::Elf_Word addend, |
| 451 | typename elfcpp::Elf_types<size>::Elf_Addr address) |
| 452 | { This::template pcrela<32>(view, value, addend, address); } |
| 453 | |
| 454 | static inline void |
| 455 | pcrela32(unsigned char* view, |
| 456 | const Sized_relobj<size, big_endian>* object, |
| 457 | const Symbol_value<size>* psymval, |
| 458 | elfcpp::Elf_Word addend, |
| 459 | typename elfcpp::Elf_types<size>::Elf_Addr address) |
| 460 | { This::template pcrela<32>(view, object, psymval, addend, address); } |
| 461 | |
| 462 | // Do a simple 64-bit REL relocation with the addend in the section |
| 463 | // contents. |
| 464 | static inline void |
| 465 | rel64(unsigned char* view, elfcpp::Elf_Xword value) |
| 466 | { This::template rel<64>(view, value); } |
| 467 | |
| 468 | static inline void |
| 469 | rel64(unsigned char* view, |
| 470 | const Sized_relobj<size, big_endian>* object, |
| 471 | const Symbol_value<size>* psymval) |
| 472 | { This::template rel<64>(view, object, psymval); } |
| 473 | |
| 474 | // Do a 64-bit RELA relocation with the addend in the relocation. |
| 475 | static inline void |
| 476 | rela64(unsigned char* view, elfcpp::Elf_Xword value, |
| 477 | elfcpp::Elf_Xword addend) |
| 478 | { This::template rela<64>(view, value, addend); } |
| 479 | |
| 480 | static inline void |
| 481 | rela64(unsigned char* view, |
| 482 | const Sized_relobj<size, big_endian>* object, |
| 483 | const Symbol_value<size>* psymval, |
| 484 | elfcpp::Elf_Xword addend) |
| 485 | { This::template rela<64>(view, object, psymval, addend); } |
| 486 | |
| 487 | // Do a simple 64-bit PC relative REL relocation with the addend in |
| 488 | // the section contents. |
| 489 | static inline void |
| 490 | pcrel64(unsigned char* view, elfcpp::Elf_Xword value, |
| 491 | typename elfcpp::Elf_types<size>::Elf_Addr address) |
| 492 | { This::template pcrel<64>(view, value, address); } |
| 493 | |
| 494 | static inline void |
| 495 | pcrel64(unsigned char* view, |
| 496 | const Sized_relobj<size, big_endian>* object, |
| 497 | const Symbol_value<size>* psymval, |
| 498 | typename elfcpp::Elf_types<size>::Elf_Addr address) |
| 499 | { This::template pcrel<64>(view, object, psymval, address); } |
| 500 | |
| 501 | // Do a simple 64-bit PC relative RELA relocation with the addend in |
| 502 | // the relocation. |
| 503 | static inline void |
| 504 | pcrela64(unsigned char* view, elfcpp::Elf_Xword value, |
| 505 | elfcpp::Elf_Xword addend, |
| 506 | typename elfcpp::Elf_types<size>::Elf_Addr address) |
| 507 | { This::template pcrela<64>(view, value, addend, address); } |
| 508 | |
| 509 | static inline void |
| 510 | pcrela64(unsigned char* view, |
| 511 | const Sized_relobj<size, big_endian>* object, |
| 512 | const Symbol_value<size>* psymval, |
| 513 | elfcpp::Elf_Xword addend, |
| 514 | typename elfcpp::Elf_types<size>::Elf_Addr address) |
| 515 | { This::template pcrela<64>(view, object, psymval, addend, address); } |
| 516 | }; |
| 517 | |
| 518 | // We try to avoid COPY relocations when possible. A COPY relocation |
| 519 | // may be required when an executable refers to a variable defined in |
| 520 | // a shared library. COPY relocations are problematic because they |
| 521 | // tie the executable to the exact size of the variable in the shared |
| 522 | // library. We can avoid them if all the references to the variable |
| 523 | // are in a writeable section. In that case we can simply use dynamic |
| 524 | // relocations. However, when scanning relocs, we don't know when we |
| 525 | // see the relocation whether we will be forced to use a COPY |
| 526 | // relocation or not. So we have to save the relocation during the |
| 527 | // reloc scanning, and then emit it as a dynamic relocation if |
| 528 | // necessary. This class implements that. It is used by the target |
| 529 | // specific code. |
| 530 | |
| 531 | template<int size, bool big_endian> |
| 532 | class Copy_relocs |
| 533 | { |
| 534 | public: |
| 535 | Copy_relocs() |
| 536 | : entries_() |
| 537 | { } |
| 538 | |
| 539 | // Return whether we need a COPY reloc for a reloc against GSYM, |
| 540 | // which is being applied to section SHNDX in OBJECT. |
| 541 | static bool |
| 542 | need_copy_reloc(const General_options*, Relobj* object, unsigned int shndx, |
| 543 | Sized_symbol<size>* gsym); |
| 544 | |
| 545 | // Save a Rel against SYM for possible emission later. SHNDX is the |
| 546 | // index of the section to which the reloc is being applied. |
| 547 | void |
| 548 | save(Symbol* sym, Relobj*, unsigned int shndx, |
| 549 | Output_section* output_section, const elfcpp::Rel<size, big_endian>&); |
| 550 | |
| 551 | // Save a Rela against SYM for possible emission later. |
| 552 | void |
| 553 | save(Symbol* sym, Relobj*, unsigned int shndx, |
| 554 | Output_section* output_section, const elfcpp::Rela<size, big_endian>&); |
| 555 | |
| 556 | // Return whether there are any relocs to emit. This also discards |
| 557 | // entries which need not be emitted. |
| 558 | bool |
| 559 | any_to_emit(); |
| 560 | |
| 561 | // Emit relocs for each symbol which did not get a COPY reloc (i.e., |
| 562 | // is still defined in the dynamic object). |
| 563 | template<int sh_type> |
| 564 | void |
| 565 | emit(Output_data_reloc<sh_type, true, size, big_endian>*); |
| 566 | |
| 567 | private: |
| 568 | typedef typename elfcpp::Elf_types<size>::Elf_Addr Address; |
| 569 | typedef typename elfcpp::Elf_types<size>::Elf_Addr Addend; |
| 570 | |
| 571 | // This POD class holds the entries we are saving. |
| 572 | class Copy_reloc_entry |
| 573 | { |
| 574 | public: |
| 575 | Copy_reloc_entry(Symbol* sym, unsigned int reloc_type, |
| 576 | Relobj* relobj, unsigned int shndx, |
| 577 | Output_section* output_section, |
| 578 | Address address, Addend addend) |
| 579 | : sym_(sym), reloc_type_(reloc_type), relobj_(relobj), |
| 580 | shndx_(shndx), output_section_(output_section), |
| 581 | address_(address), addend_(addend) |
| 582 | { } |
| 583 | |
| 584 | // Return whether we should emit this reloc. If we should not |
| 585 | // emit, we clear it. |
| 586 | bool |
| 587 | should_emit(); |
| 588 | |
| 589 | // Emit this reloc. |
| 590 | |
| 591 | void |
| 592 | emit(Output_data_reloc<elfcpp::SHT_REL, true, size, big_endian>*); |
| 593 | |
| 594 | void |
| 595 | emit(Output_data_reloc<elfcpp::SHT_RELA, true, size, big_endian>*); |
| 596 | |
| 597 | private: |
| 598 | Symbol* sym_; |
| 599 | unsigned int reloc_type_; |
| 600 | Relobj* relobj_; |
| 601 | unsigned int shndx_; |
| 602 | Output_section* output_section_; |
| 603 | Address address_; |
| 604 | Addend addend_; |
| 605 | }; |
| 606 | |
| 607 | // A list of relocs to be saved. |
| 608 | typedef std::vector<Copy_reloc_entry> Copy_reloc_entries; |
| 609 | |
| 610 | // The list of relocs we are saving. |
| 611 | Copy_reloc_entries entries_; |
| 612 | }; |
| 613 | |
| 614 | // Track relocations while reading a section. This lets you ask for |
| 615 | // the relocation at a certain offset, and see how relocs occur |
| 616 | // between points of interest. |
| 617 | |
| 618 | template<int size, bool big_endian> |
| 619 | class Track_relocs |
| 620 | { |
| 621 | public: |
| 622 | Track_relocs() |
| 623 | : prelocs_(NULL), len_(0), pos_(0), reloc_size_(0) |
| 624 | { } |
| 625 | |
| 626 | // Initialize the Track_relocs object. OBJECT is the object holding |
| 627 | // the reloc section, RELOC_SHNDX is the section index of the reloc |
| 628 | // section, and RELOC_TYPE is the type of the reloc section |
| 629 | // (elfcpp::SHT_REL or elfcpp::SHT_RELA). This returns false if |
| 630 | // something went wrong. |
| 631 | bool |
| 632 | initialize(Object* object, unsigned int reloc_shndx, |
| 633 | unsigned int reloc_type); |
| 634 | |
| 635 | // Return the offset in the data section to which the next reloc |
| 636 | // applies. THis returns -1 if there is no next reloc. |
| 637 | off_t |
| 638 | next_offset() const; |
| 639 | |
| 640 | // Return the symbol index of the next reloc. This returns -1U if |
| 641 | // there is no next reloc. |
| 642 | unsigned int |
| 643 | next_symndx() const; |
| 644 | |
| 645 | // Advance to OFFSET within the data section, and return the number |
| 646 | // of relocs which would be skipped. |
| 647 | int |
| 648 | advance(off_t offset); |
| 649 | |
| 650 | private: |
| 651 | // The contents of the input object's reloc section. |
| 652 | const unsigned char* prelocs_; |
| 653 | // The length of the reloc section. |
| 654 | section_size_type len_; |
| 655 | // Our current position in the reloc section. |
| 656 | section_size_type pos_; |
| 657 | // The size of the relocs in the section. |
| 658 | int reloc_size_; |
| 659 | }; |
| 660 | |
| 661 | } // End namespace gold. |
| 662 | |
| 663 | #endif // !defined(GOLD_RELOC_H) |