| 1 | // i386.cc -- i386 target support for gold. |
| 2 | |
| 3 | // Copyright 2006, 2007 Free Software Foundation, Inc. |
| 4 | // Written by Ian Lance Taylor <iant@google.com>. |
| 5 | |
| 6 | // This file is part of gold. |
| 7 | |
| 8 | // This program is free software; you can redistribute it and/or modify |
| 9 | // it under the terms of the GNU General Public License as published by |
| 10 | // the Free Software Foundation; either version 3 of the License, or |
| 11 | // (at your option) any later version. |
| 12 | |
| 13 | // This program is distributed in the hope that it will be useful, |
| 14 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | // GNU General Public License for more details. |
| 17 | |
| 18 | // You should have received a copy of the GNU General Public License |
| 19 | // along with this program; if not, write to the Free Software |
| 20 | // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
| 21 | // MA 02110-1301, USA. |
| 22 | |
| 23 | #include "gold.h" |
| 24 | |
| 25 | #include <cstring> |
| 26 | |
| 27 | #include "elfcpp.h" |
| 28 | #include "parameters.h" |
| 29 | #include "reloc.h" |
| 30 | #include "i386.h" |
| 31 | #include "object.h" |
| 32 | #include "symtab.h" |
| 33 | #include "layout.h" |
| 34 | #include "output.h" |
| 35 | #include "target.h" |
| 36 | #include "target-reloc.h" |
| 37 | #include "target-select.h" |
| 38 | #include "tls.h" |
| 39 | |
| 40 | namespace |
| 41 | { |
| 42 | |
| 43 | using namespace gold; |
| 44 | |
| 45 | class Output_data_plt_i386; |
| 46 | |
| 47 | // The i386 target class. |
| 48 | // TLS info comes from |
| 49 | // http://people.redhat.com/drepper/tls.pdf |
| 50 | // http://www.lsd.ic.unicamp.br/~oliva/writeups/TLS/RFC-TLSDESC-x86.txt |
| 51 | |
| 52 | class Target_i386 : public Sized_target<32, false> |
| 53 | { |
| 54 | public: |
| 55 | typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section; |
| 56 | |
| 57 | Target_i386() |
| 58 | : Sized_target<32, false>(&i386_info), |
| 59 | got_(NULL), plt_(NULL), got_plt_(NULL), rel_dyn_(NULL), |
| 60 | copy_relocs_(NULL), dynbss_(NULL) |
| 61 | { } |
| 62 | |
| 63 | // Scan the relocations to look for symbol adjustments. |
| 64 | void |
| 65 | scan_relocs(const General_options& options, |
| 66 | Symbol_table* symtab, |
| 67 | Layout* layout, |
| 68 | Sized_relobj<32, false>* object, |
| 69 | unsigned int data_shndx, |
| 70 | unsigned int sh_type, |
| 71 | const unsigned char* prelocs, |
| 72 | size_t reloc_count, |
| 73 | Output_section* output_section, |
| 74 | bool needs_special_offset_handling, |
| 75 | size_t local_symbol_count, |
| 76 | const unsigned char* plocal_symbols); |
| 77 | |
| 78 | // Finalize the sections. |
| 79 | void |
| 80 | do_finalize_sections(Layout*); |
| 81 | |
| 82 | // Return the value to use for a dynamic which requires special |
| 83 | // treatment. |
| 84 | uint64_t |
| 85 | do_dynsym_value(const Symbol*) const; |
| 86 | |
| 87 | // Relocate a section. |
| 88 | void |
| 89 | relocate_section(const Relocate_info<32, false>*, |
| 90 | unsigned int sh_type, |
| 91 | const unsigned char* prelocs, |
| 92 | size_t reloc_count, |
| 93 | Output_section* output_section, |
| 94 | bool needs_special_offset_handling, |
| 95 | unsigned char* view, |
| 96 | elfcpp::Elf_types<32>::Elf_Addr view_address, |
| 97 | off_t view_size); |
| 98 | |
| 99 | // Return a string used to fill a code section with nops. |
| 100 | std::string |
| 101 | do_code_fill(off_t length); |
| 102 | |
| 103 | // Return the size of the GOT section. |
| 104 | off_t |
| 105 | got_size() |
| 106 | { |
| 107 | gold_assert(this->got_ != NULL); |
| 108 | return this->got_->data_size(); |
| 109 | } |
| 110 | |
| 111 | private: |
| 112 | // The class which scans relocations. |
| 113 | struct Scan |
| 114 | { |
| 115 | inline void |
| 116 | local(const General_options& options, Symbol_table* symtab, |
| 117 | Layout* layout, Target_i386* target, |
| 118 | Sized_relobj<32, false>* object, |
| 119 | unsigned int data_shndx, |
| 120 | const elfcpp::Rel<32, false>& reloc, unsigned int r_type, |
| 121 | const elfcpp::Sym<32, false>& lsym); |
| 122 | |
| 123 | inline void |
| 124 | global(const General_options& options, Symbol_table* symtab, |
| 125 | Layout* layout, Target_i386* target, |
| 126 | Sized_relobj<32, false>* object, |
| 127 | unsigned int data_shndx, |
| 128 | const elfcpp::Rel<32, false>& reloc, unsigned int r_type, |
| 129 | Symbol* gsym); |
| 130 | |
| 131 | static void |
| 132 | unsupported_reloc_local(Sized_relobj<32, false>*, unsigned int r_type); |
| 133 | |
| 134 | static void |
| 135 | unsupported_reloc_global(Sized_relobj<32, false>*, unsigned int r_type, |
| 136 | Symbol*); |
| 137 | }; |
| 138 | |
| 139 | // The class which implements relocation. |
| 140 | class Relocate |
| 141 | { |
| 142 | public: |
| 143 | Relocate() |
| 144 | : skip_call_tls_get_addr_(false), |
| 145 | local_dynamic_type_(LOCAL_DYNAMIC_NONE) |
| 146 | { } |
| 147 | |
| 148 | ~Relocate() |
| 149 | { |
| 150 | if (this->skip_call_tls_get_addr_) |
| 151 | { |
| 152 | // FIXME: This needs to specify the location somehow. |
| 153 | gold_error(_("missing expected TLS relocation")); |
| 154 | } |
| 155 | } |
| 156 | |
| 157 | // Return whether the static relocation needs to be applied. |
| 158 | inline bool |
| 159 | should_apply_static_reloc(const Sized_symbol<32>* gsym, |
| 160 | bool is_absolute_ref, |
| 161 | bool is_function_call, |
| 162 | bool is_32bit); |
| 163 | |
| 164 | // Do a relocation. Return false if the caller should not issue |
| 165 | // any warnings about this relocation. |
| 166 | inline bool |
| 167 | relocate(const Relocate_info<32, false>*, Target_i386*, size_t relnum, |
| 168 | const elfcpp::Rel<32, false>&, |
| 169 | unsigned int r_type, const Sized_symbol<32>*, |
| 170 | const Symbol_value<32>*, |
| 171 | unsigned char*, elfcpp::Elf_types<32>::Elf_Addr, |
| 172 | off_t); |
| 173 | |
| 174 | private: |
| 175 | // Do a TLS relocation. |
| 176 | inline void |
| 177 | relocate_tls(const Relocate_info<32, false>*, size_t relnum, |
| 178 | const elfcpp::Rel<32, false>&, |
| 179 | unsigned int r_type, const Sized_symbol<32>*, |
| 180 | const Symbol_value<32>*, |
| 181 | unsigned char*, elfcpp::Elf_types<32>::Elf_Addr, off_t); |
| 182 | |
| 183 | // Do a TLS General-Dynamic to Local-Exec transition. |
| 184 | inline void |
| 185 | tls_gd_to_le(const Relocate_info<32, false>*, size_t relnum, |
| 186 | Output_segment* tls_segment, |
| 187 | const elfcpp::Rel<32, false>&, unsigned int r_type, |
| 188 | elfcpp::Elf_types<32>::Elf_Addr value, |
| 189 | unsigned char* view, |
| 190 | off_t view_size); |
| 191 | |
| 192 | // Do a TLS Local-Dynamic to Local-Exec transition. |
| 193 | inline void |
| 194 | tls_ld_to_le(const Relocate_info<32, false>*, size_t relnum, |
| 195 | Output_segment* tls_segment, |
| 196 | const elfcpp::Rel<32, false>&, unsigned int r_type, |
| 197 | elfcpp::Elf_types<32>::Elf_Addr value, |
| 198 | unsigned char* view, |
| 199 | off_t view_size); |
| 200 | |
| 201 | // Do a TLS Initial-Exec to Local-Exec transition. |
| 202 | static inline void |
| 203 | tls_ie_to_le(const Relocate_info<32, false>*, size_t relnum, |
| 204 | Output_segment* tls_segment, |
| 205 | const elfcpp::Rel<32, false>&, unsigned int r_type, |
| 206 | elfcpp::Elf_types<32>::Elf_Addr value, |
| 207 | unsigned char* view, |
| 208 | off_t view_size); |
| 209 | |
| 210 | // We need to keep track of which type of local dynamic relocation |
| 211 | // we have seen, so that we can optimize R_386_TLS_LDO_32 correctly. |
| 212 | enum Local_dynamic_type |
| 213 | { |
| 214 | LOCAL_DYNAMIC_NONE, |
| 215 | LOCAL_DYNAMIC_SUN, |
| 216 | LOCAL_DYNAMIC_GNU |
| 217 | }; |
| 218 | |
| 219 | // This is set if we should skip the next reloc, which should be a |
| 220 | // PLT32 reloc against ___tls_get_addr. |
| 221 | bool skip_call_tls_get_addr_; |
| 222 | // The type of local dynamic relocation we have seen in the section |
| 223 | // being relocated, if any. |
| 224 | Local_dynamic_type local_dynamic_type_; |
| 225 | }; |
| 226 | |
| 227 | // Adjust TLS relocation type based on the options and whether this |
| 228 | // is a local symbol. |
| 229 | static tls::Tls_optimization |
| 230 | optimize_tls_reloc(bool is_final, int r_type); |
| 231 | |
| 232 | // Get the GOT section, creating it if necessary. |
| 233 | Output_data_got<32, false>* |
| 234 | got_section(Symbol_table*, Layout*); |
| 235 | |
| 236 | // Get the GOT PLT section. |
| 237 | Output_data_space* |
| 238 | got_plt_section() const |
| 239 | { |
| 240 | gold_assert(this->got_plt_ != NULL); |
| 241 | return this->got_plt_; |
| 242 | } |
| 243 | |
| 244 | // Create a PLT entry for a global symbol. |
| 245 | void |
| 246 | make_plt_entry(Symbol_table*, Layout*, Symbol*); |
| 247 | |
| 248 | // Get the PLT section. |
| 249 | const Output_data_plt_i386* |
| 250 | plt_section() const |
| 251 | { |
| 252 | gold_assert(this->plt_ != NULL); |
| 253 | return this->plt_; |
| 254 | } |
| 255 | |
| 256 | // Get the dynamic reloc section, creating it if necessary. |
| 257 | Reloc_section* |
| 258 | rel_dyn_section(Layout*); |
| 259 | |
| 260 | // Return true if the symbol may need a COPY relocation. |
| 261 | // References from an executable object to non-function symbols |
| 262 | // defined in a dynamic object may need a COPY relocation. |
| 263 | bool |
| 264 | may_need_copy_reloc(Symbol* gsym) |
| 265 | { |
| 266 | return (!parameters->output_is_shared() |
| 267 | && gsym->is_from_dynobj() |
| 268 | && gsym->type() != elfcpp::STT_FUNC); |
| 269 | } |
| 270 | |
| 271 | // Copy a relocation against a global symbol. |
| 272 | void |
| 273 | copy_reloc(const General_options*, Symbol_table*, Layout*, |
| 274 | Sized_relobj<32, false>*, unsigned int, |
| 275 | Symbol*, const elfcpp::Rel<32, false>&); |
| 276 | |
| 277 | // Information about this specific target which we pass to the |
| 278 | // general Target structure. |
| 279 | static const Target::Target_info i386_info; |
| 280 | |
| 281 | // The GOT section. |
| 282 | Output_data_got<32, false>* got_; |
| 283 | // The PLT section. |
| 284 | Output_data_plt_i386* plt_; |
| 285 | // The GOT PLT section. |
| 286 | Output_data_space* got_plt_; |
| 287 | // The dynamic reloc section. |
| 288 | Reloc_section* rel_dyn_; |
| 289 | // Relocs saved to avoid a COPY reloc. |
| 290 | Copy_relocs<32, false>* copy_relocs_; |
| 291 | // Space for variables copied with a COPY reloc. |
| 292 | Output_data_space* dynbss_; |
| 293 | }; |
| 294 | |
| 295 | const Target::Target_info Target_i386::i386_info = |
| 296 | { |
| 297 | 32, // size |
| 298 | false, // is_big_endian |
| 299 | elfcpp::EM_386, // machine_code |
| 300 | false, // has_make_symbol |
| 301 | false, // has_resolve |
| 302 | true, // has_code_fill |
| 303 | true, // is_default_stack_executable |
| 304 | "/usr/lib/libc.so.1", // dynamic_linker |
| 305 | 0x08048000, // default_text_segment_address |
| 306 | 0x1000, // abi_pagesize |
| 307 | 0x1000 // common_pagesize |
| 308 | }; |
| 309 | |
| 310 | // Get the GOT section, creating it if necessary. |
| 311 | |
| 312 | Output_data_got<32, false>* |
| 313 | Target_i386::got_section(Symbol_table* symtab, Layout* layout) |
| 314 | { |
| 315 | if (this->got_ == NULL) |
| 316 | { |
| 317 | gold_assert(symtab != NULL && layout != NULL); |
| 318 | |
| 319 | this->got_ = new Output_data_got<32, false>(); |
| 320 | |
| 321 | layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS, |
| 322 | elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE, |
| 323 | this->got_); |
| 324 | |
| 325 | // The old GNU linker creates a .got.plt section. We just |
| 326 | // create another set of data in the .got section. Note that we |
| 327 | // always create a PLT if we create a GOT, although the PLT |
| 328 | // might be empty. |
| 329 | this->got_plt_ = new Output_data_space(4); |
| 330 | layout->add_output_section_data(".got", elfcpp::SHT_PROGBITS, |
| 331 | elfcpp::SHF_ALLOC | elfcpp::SHF_WRITE, |
| 332 | this->got_plt_); |
| 333 | |
| 334 | // The first three entries are reserved. |
| 335 | this->got_plt_->set_space_size(3 * 4); |
| 336 | |
| 337 | // Define _GLOBAL_OFFSET_TABLE_ at the start of the PLT. |
| 338 | symtab->define_in_output_data(this, "_GLOBAL_OFFSET_TABLE_", NULL, |
| 339 | this->got_plt_, |
| 340 | 0, 0, elfcpp::STT_OBJECT, |
| 341 | elfcpp::STB_LOCAL, |
| 342 | elfcpp::STV_HIDDEN, 0, |
| 343 | false, false); |
| 344 | } |
| 345 | |
| 346 | return this->got_; |
| 347 | } |
| 348 | |
| 349 | // Get the dynamic reloc section, creating it if necessary. |
| 350 | |
| 351 | Target_i386::Reloc_section* |
| 352 | Target_i386::rel_dyn_section(Layout* layout) |
| 353 | { |
| 354 | if (this->rel_dyn_ == NULL) |
| 355 | { |
| 356 | gold_assert(layout != NULL); |
| 357 | this->rel_dyn_ = new Reloc_section(); |
| 358 | layout->add_output_section_data(".rel.dyn", elfcpp::SHT_REL, |
| 359 | elfcpp::SHF_ALLOC, this->rel_dyn_); |
| 360 | } |
| 361 | return this->rel_dyn_; |
| 362 | } |
| 363 | |
| 364 | // A class to handle the PLT data. |
| 365 | |
| 366 | class Output_data_plt_i386 : public Output_section_data |
| 367 | { |
| 368 | public: |
| 369 | typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, false> Reloc_section; |
| 370 | |
| 371 | Output_data_plt_i386(Layout*, Output_data_space*); |
| 372 | |
| 373 | // Add an entry to the PLT. |
| 374 | void |
| 375 | add_entry(Symbol* gsym); |
| 376 | |
| 377 | // Return the .rel.plt section data. |
| 378 | const Reloc_section* |
| 379 | rel_plt() const |
| 380 | { return this->rel_; } |
| 381 | |
| 382 | protected: |
| 383 | void |
| 384 | do_adjust_output_section(Output_section* os); |
| 385 | |
| 386 | private: |
| 387 | // The size of an entry in the PLT. |
| 388 | static const int plt_entry_size = 16; |
| 389 | |
| 390 | // The first entry in the PLT for an executable. |
| 391 | static unsigned char exec_first_plt_entry[plt_entry_size]; |
| 392 | |
| 393 | // The first entry in the PLT for a shared object. |
| 394 | static unsigned char dyn_first_plt_entry[plt_entry_size]; |
| 395 | |
| 396 | // Other entries in the PLT for an executable. |
| 397 | static unsigned char exec_plt_entry[plt_entry_size]; |
| 398 | |
| 399 | // Other entries in the PLT for a shared object. |
| 400 | static unsigned char dyn_plt_entry[plt_entry_size]; |
| 401 | |
| 402 | // Set the final size. |
| 403 | void |
| 404 | do_set_address(uint64_t, off_t) |
| 405 | { this->set_data_size((this->count_ + 1) * plt_entry_size); } |
| 406 | |
| 407 | // Write out the PLT data. |
| 408 | void |
| 409 | do_write(Output_file*); |
| 410 | |
| 411 | // The reloc section. |
| 412 | Reloc_section* rel_; |
| 413 | // The .got.plt section. |
| 414 | Output_data_space* got_plt_; |
| 415 | // The number of PLT entries. |
| 416 | unsigned int count_; |
| 417 | }; |
| 418 | |
| 419 | // Create the PLT section. The ordinary .got section is an argument, |
| 420 | // since we need to refer to the start. We also create our own .got |
| 421 | // section just for PLT entries. |
| 422 | |
| 423 | Output_data_plt_i386::Output_data_plt_i386(Layout* layout, |
| 424 | Output_data_space* got_plt) |
| 425 | : Output_section_data(4), got_plt_(got_plt), count_(0) |
| 426 | { |
| 427 | this->rel_ = new Reloc_section(); |
| 428 | layout->add_output_section_data(".rel.plt", elfcpp::SHT_REL, |
| 429 | elfcpp::SHF_ALLOC, this->rel_); |
| 430 | } |
| 431 | |
| 432 | void |
| 433 | Output_data_plt_i386::do_adjust_output_section(Output_section* os) |
| 434 | { |
| 435 | // UnixWare sets the entsize of .plt to 4, and so does the old GNU |
| 436 | // linker, and so do we. |
| 437 | os->set_entsize(4); |
| 438 | } |
| 439 | |
| 440 | // Add an entry to the PLT. |
| 441 | |
| 442 | void |
| 443 | Output_data_plt_i386::add_entry(Symbol* gsym) |
| 444 | { |
| 445 | gold_assert(!gsym->has_plt_offset()); |
| 446 | |
| 447 | // Note that when setting the PLT offset we skip the initial |
| 448 | // reserved PLT entry. |
| 449 | gsym->set_plt_offset((this->count_ + 1) * plt_entry_size); |
| 450 | |
| 451 | ++this->count_; |
| 452 | |
| 453 | off_t got_offset = this->got_plt_->data_size(); |
| 454 | |
| 455 | // Every PLT entry needs a GOT entry which points back to the PLT |
| 456 | // entry (this will be changed by the dynamic linker, normally |
| 457 | // lazily when the function is called). |
| 458 | this->got_plt_->set_space_size(got_offset + 4); |
| 459 | |
| 460 | // Every PLT entry needs a reloc. |
| 461 | gsym->set_needs_dynsym_entry(); |
| 462 | this->rel_->add_global(gsym, elfcpp::R_386_JUMP_SLOT, this->got_plt_, |
| 463 | got_offset); |
| 464 | |
| 465 | // Note that we don't need to save the symbol. The contents of the |
| 466 | // PLT are independent of which symbols are used. The symbols only |
| 467 | // appear in the relocations. |
| 468 | } |
| 469 | |
| 470 | // The first entry in the PLT for an executable. |
| 471 | |
| 472 | unsigned char Output_data_plt_i386::exec_first_plt_entry[plt_entry_size] = |
| 473 | { |
| 474 | 0xff, 0x35, // pushl contents of memory address |
| 475 | 0, 0, 0, 0, // replaced with address of .got + 4 |
| 476 | 0xff, 0x25, // jmp indirect |
| 477 | 0, 0, 0, 0, // replaced with address of .got + 8 |
| 478 | 0, 0, 0, 0 // unused |
| 479 | }; |
| 480 | |
| 481 | // The first entry in the PLT for a shared object. |
| 482 | |
| 483 | unsigned char Output_data_plt_i386::dyn_first_plt_entry[plt_entry_size] = |
| 484 | { |
| 485 | 0xff, 0xb3, 4, 0, 0, 0, // pushl 4(%ebx) |
| 486 | 0xff, 0xa3, 8, 0, 0, 0, // jmp *8(%ebx) |
| 487 | 0, 0, 0, 0 // unused |
| 488 | }; |
| 489 | |
| 490 | // Subsequent entries in the PLT for an executable. |
| 491 | |
| 492 | unsigned char Output_data_plt_i386::exec_plt_entry[plt_entry_size] = |
| 493 | { |
| 494 | 0xff, 0x25, // jmp indirect |
| 495 | 0, 0, 0, 0, // replaced with address of symbol in .got |
| 496 | 0x68, // pushl immediate |
| 497 | 0, 0, 0, 0, // replaced with offset into relocation table |
| 498 | 0xe9, // jmp relative |
| 499 | 0, 0, 0, 0 // replaced with offset to start of .plt |
| 500 | }; |
| 501 | |
| 502 | // Subsequent entries in the PLT for a shared object. |
| 503 | |
| 504 | unsigned char Output_data_plt_i386::dyn_plt_entry[plt_entry_size] = |
| 505 | { |
| 506 | 0xff, 0xa3, // jmp *offset(%ebx) |
| 507 | 0, 0, 0, 0, // replaced with offset of symbol in .got |
| 508 | 0x68, // pushl immediate |
| 509 | 0, 0, 0, 0, // replaced with offset into relocation table |
| 510 | 0xe9, // jmp relative |
| 511 | 0, 0, 0, 0 // replaced with offset to start of .plt |
| 512 | }; |
| 513 | |
| 514 | // Write out the PLT. This uses the hand-coded instructions above, |
| 515 | // and adjusts them as needed. This is all specified by the i386 ELF |
| 516 | // Processor Supplement. |
| 517 | |
| 518 | void |
| 519 | Output_data_plt_i386::do_write(Output_file* of) |
| 520 | { |
| 521 | const off_t offset = this->offset(); |
| 522 | const off_t oview_size = this->data_size(); |
| 523 | unsigned char* const oview = of->get_output_view(offset, oview_size); |
| 524 | |
| 525 | const off_t got_file_offset = this->got_plt_->offset(); |
| 526 | const off_t got_size = this->got_plt_->data_size(); |
| 527 | unsigned char* const got_view = of->get_output_view(got_file_offset, |
| 528 | got_size); |
| 529 | |
| 530 | unsigned char* pov = oview; |
| 531 | |
| 532 | elfcpp::Elf_types<32>::Elf_Addr plt_address = this->address(); |
| 533 | elfcpp::Elf_types<32>::Elf_Addr got_address = this->got_plt_->address(); |
| 534 | |
| 535 | if (parameters->output_is_shared()) |
| 536 | memcpy(pov, dyn_first_plt_entry, plt_entry_size); |
| 537 | else |
| 538 | { |
| 539 | memcpy(pov, exec_first_plt_entry, plt_entry_size); |
| 540 | elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_address + 4); |
| 541 | elfcpp::Swap<32, false>::writeval(pov + 8, got_address + 8); |
| 542 | } |
| 543 | pov += plt_entry_size; |
| 544 | |
| 545 | unsigned char* got_pov = got_view; |
| 546 | |
| 547 | memset(got_pov, 0, 12); |
| 548 | got_pov += 12; |
| 549 | |
| 550 | const int rel_size = elfcpp::Elf_sizes<32>::rel_size; |
| 551 | |
| 552 | unsigned int plt_offset = plt_entry_size; |
| 553 | unsigned int plt_rel_offset = 0; |
| 554 | unsigned int got_offset = 12; |
| 555 | const unsigned int count = this->count_; |
| 556 | for (unsigned int i = 0; |
| 557 | i < count; |
| 558 | ++i, |
| 559 | pov += plt_entry_size, |
| 560 | got_pov += 4, |
| 561 | plt_offset += plt_entry_size, |
| 562 | plt_rel_offset += rel_size, |
| 563 | got_offset += 4) |
| 564 | { |
| 565 | // Set and adjust the PLT entry itself. |
| 566 | |
| 567 | if (parameters->output_is_shared()) |
| 568 | { |
| 569 | memcpy(pov, dyn_plt_entry, plt_entry_size); |
| 570 | elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, got_offset); |
| 571 | } |
| 572 | else |
| 573 | { |
| 574 | memcpy(pov, exec_plt_entry, plt_entry_size); |
| 575 | elfcpp::Swap_unaligned<32, false>::writeval(pov + 2, |
| 576 | (got_address |
| 577 | + got_offset)); |
| 578 | } |
| 579 | |
| 580 | elfcpp::Swap_unaligned<32, false>::writeval(pov + 7, plt_rel_offset); |
| 581 | elfcpp::Swap<32, false>::writeval(pov + 12, |
| 582 | - (plt_offset + plt_entry_size)); |
| 583 | |
| 584 | // Set the entry in the GOT. |
| 585 | elfcpp::Swap<32, false>::writeval(got_pov, plt_address + plt_offset + 6); |
| 586 | } |
| 587 | |
| 588 | gold_assert(pov - oview == oview_size); |
| 589 | gold_assert(got_pov - got_view == got_size); |
| 590 | |
| 591 | of->write_output_view(offset, oview_size, oview); |
| 592 | of->write_output_view(got_file_offset, got_size, got_view); |
| 593 | } |
| 594 | |
| 595 | // Create a PLT entry for a global symbol. |
| 596 | |
| 597 | void |
| 598 | Target_i386::make_plt_entry(Symbol_table* symtab, Layout* layout, Symbol* gsym) |
| 599 | { |
| 600 | if (gsym->has_plt_offset()) |
| 601 | return; |
| 602 | |
| 603 | if (this->plt_ == NULL) |
| 604 | { |
| 605 | // Create the GOT sections first. |
| 606 | this->got_section(symtab, layout); |
| 607 | |
| 608 | this->plt_ = new Output_data_plt_i386(layout, this->got_plt_); |
| 609 | layout->add_output_section_data(".plt", elfcpp::SHT_PROGBITS, |
| 610 | (elfcpp::SHF_ALLOC |
| 611 | | elfcpp::SHF_EXECINSTR), |
| 612 | this->plt_); |
| 613 | } |
| 614 | |
| 615 | this->plt_->add_entry(gsym); |
| 616 | } |
| 617 | |
| 618 | // Handle a relocation against a non-function symbol defined in a |
| 619 | // dynamic object. The traditional way to handle this is to generate |
| 620 | // a COPY relocation to copy the variable at runtime from the shared |
| 621 | // object into the executable's data segment. However, this is |
| 622 | // undesirable in general, as if the size of the object changes in the |
| 623 | // dynamic object, the executable will no longer work correctly. If |
| 624 | // this relocation is in a writable section, then we can create a |
| 625 | // dynamic reloc and the dynamic linker will resolve it to the correct |
| 626 | // address at runtime. However, we do not want do that if the |
| 627 | // relocation is in a read-only section, as it would prevent the |
| 628 | // readonly segment from being shared. And if we have to eventually |
| 629 | // generate a COPY reloc, then any dynamic relocations will be |
| 630 | // useless. So this means that if this is a writable section, we need |
| 631 | // to save the relocation until we see whether we have to create a |
| 632 | // COPY relocation for this symbol for any other relocation. |
| 633 | |
| 634 | void |
| 635 | Target_i386::copy_reloc(const General_options* options, |
| 636 | Symbol_table* symtab, |
| 637 | Layout* layout, |
| 638 | Sized_relobj<32, false>* object, |
| 639 | unsigned int data_shndx, Symbol* gsym, |
| 640 | const elfcpp::Rel<32, false>& rel) |
| 641 | { |
| 642 | Sized_symbol<32>* ssym; |
| 643 | ssym = symtab->get_sized_symbol SELECT_SIZE_NAME(32) (gsym |
| 644 | SELECT_SIZE(32)); |
| 645 | |
| 646 | if (!Copy_relocs<32, false>::need_copy_reloc(options, object, |
| 647 | data_shndx, ssym)) |
| 648 | { |
| 649 | // So far we do not need a COPY reloc. Save this relocation. |
| 650 | // If it turns out that we never need a COPY reloc for this |
| 651 | // symbol, then we will emit the relocation. |
| 652 | if (this->copy_relocs_ == NULL) |
| 653 | this->copy_relocs_ = new Copy_relocs<32, false>(); |
| 654 | this->copy_relocs_->save(ssym, object, data_shndx, rel); |
| 655 | } |
| 656 | else |
| 657 | { |
| 658 | // Allocate space for this symbol in the .bss section. |
| 659 | |
| 660 | elfcpp::Elf_types<32>::Elf_WXword symsize = ssym->symsize(); |
| 661 | |
| 662 | // There is no defined way to determine the required alignment |
| 663 | // of the symbol. We pick the alignment based on the size. We |
| 664 | // set an arbitrary maximum of 256. |
| 665 | unsigned int align; |
| 666 | for (align = 1; align < 512; align <<= 1) |
| 667 | if ((symsize & align) != 0) |
| 668 | break; |
| 669 | |
| 670 | if (this->dynbss_ == NULL) |
| 671 | { |
| 672 | this->dynbss_ = new Output_data_space(align); |
| 673 | layout->add_output_section_data(".bss", |
| 674 | elfcpp::SHT_NOBITS, |
| 675 | (elfcpp::SHF_ALLOC |
| 676 | | elfcpp::SHF_WRITE), |
| 677 | this->dynbss_); |
| 678 | } |
| 679 | |
| 680 | Output_data_space* dynbss = this->dynbss_; |
| 681 | |
| 682 | if (align > dynbss->addralign()) |
| 683 | dynbss->set_space_alignment(align); |
| 684 | |
| 685 | off_t dynbss_size = dynbss->data_size(); |
| 686 | dynbss_size = align_address(dynbss_size, align); |
| 687 | off_t offset = dynbss_size; |
| 688 | dynbss->set_space_size(dynbss_size + symsize); |
| 689 | |
| 690 | symtab->define_with_copy_reloc(this, ssym, dynbss, offset); |
| 691 | |
| 692 | // Add the COPY reloc. |
| 693 | Reloc_section* rel_dyn = this->rel_dyn_section(layout); |
| 694 | rel_dyn->add_global(ssym, elfcpp::R_386_COPY, dynbss, offset); |
| 695 | } |
| 696 | } |
| 697 | |
| 698 | // Optimize the TLS relocation type based on what we know about the |
| 699 | // symbol. IS_FINAL is true if the final address of this symbol is |
| 700 | // known at link time. |
| 701 | |
| 702 | tls::Tls_optimization |
| 703 | Target_i386::optimize_tls_reloc(bool is_final, int r_type) |
| 704 | { |
| 705 | // If we are generating a shared library, then we can't do anything |
| 706 | // in the linker. |
| 707 | if (parameters->output_is_shared()) |
| 708 | return tls::TLSOPT_NONE; |
| 709 | |
| 710 | switch (r_type) |
| 711 | { |
| 712 | case elfcpp::R_386_TLS_GD: |
| 713 | case elfcpp::R_386_TLS_GOTDESC: |
| 714 | case elfcpp::R_386_TLS_DESC_CALL: |
| 715 | // These are General-Dynamic which permits fully general TLS |
| 716 | // access. Since we know that we are generating an executable, |
| 717 | // we can convert this to Initial-Exec. If we also know that |
| 718 | // this is a local symbol, we can further switch to Local-Exec. |
| 719 | if (is_final) |
| 720 | return tls::TLSOPT_TO_LE; |
| 721 | return tls::TLSOPT_TO_IE; |
| 722 | |
| 723 | case elfcpp::R_386_TLS_LDM: |
| 724 | // This is Local-Dynamic, which refers to a local symbol in the |
| 725 | // dynamic TLS block. Since we know that we generating an |
| 726 | // executable, we can switch to Local-Exec. |
| 727 | return tls::TLSOPT_TO_LE; |
| 728 | |
| 729 | case elfcpp::R_386_TLS_LDO_32: |
| 730 | // Another type of Local-Dynamic relocation. |
| 731 | return tls::TLSOPT_TO_LE; |
| 732 | |
| 733 | case elfcpp::R_386_TLS_IE: |
| 734 | case elfcpp::R_386_TLS_GOTIE: |
| 735 | case elfcpp::R_386_TLS_IE_32: |
| 736 | // These are Initial-Exec relocs which get the thread offset |
| 737 | // from the GOT. If we know that we are linking against the |
| 738 | // local symbol, we can switch to Local-Exec, which links the |
| 739 | // thread offset into the instruction. |
| 740 | if (is_final) |
| 741 | return tls::TLSOPT_TO_LE; |
| 742 | return tls::TLSOPT_NONE; |
| 743 | |
| 744 | case elfcpp::R_386_TLS_LE: |
| 745 | case elfcpp::R_386_TLS_LE_32: |
| 746 | // When we already have Local-Exec, there is nothing further we |
| 747 | // can do. |
| 748 | return tls::TLSOPT_NONE; |
| 749 | |
| 750 | default: |
| 751 | gold_unreachable(); |
| 752 | } |
| 753 | } |
| 754 | |
| 755 | // Report an unsupported relocation against a local symbol. |
| 756 | |
| 757 | void |
| 758 | Target_i386::Scan::unsupported_reloc_local(Sized_relobj<32, false>* object, |
| 759 | unsigned int r_type) |
| 760 | { |
| 761 | gold_error(_("%s: unsupported reloc %u against local symbol"), |
| 762 | object->name().c_str(), r_type); |
| 763 | } |
| 764 | |
| 765 | // Scan a relocation for a local symbol. |
| 766 | |
| 767 | inline void |
| 768 | Target_i386::Scan::local(const General_options&, |
| 769 | Symbol_table* symtab, |
| 770 | Layout* layout, |
| 771 | Target_i386* target, |
| 772 | Sized_relobj<32, false>* object, |
| 773 | unsigned int data_shndx, |
| 774 | const elfcpp::Rel<32, false>& reloc, |
| 775 | unsigned int r_type, |
| 776 | const elfcpp::Sym<32, false>&) |
| 777 | { |
| 778 | switch (r_type) |
| 779 | { |
| 780 | case elfcpp::R_386_NONE: |
| 781 | case elfcpp::R_386_GNU_VTINHERIT: |
| 782 | case elfcpp::R_386_GNU_VTENTRY: |
| 783 | break; |
| 784 | |
| 785 | case elfcpp::R_386_32: |
| 786 | // If building a shared library (or a position-independent |
| 787 | // executable), we need to create a dynamic relocation for |
| 788 | // this location. The relocation applied at link time will |
| 789 | // apply the link-time value, so we flag the location with |
| 790 | // an R_386_RELATIVE relocation so the dynamic loader can |
| 791 | // relocate it easily. |
| 792 | if (parameters->output_is_position_independent()) |
| 793 | { |
| 794 | Reloc_section* rel_dyn = target->rel_dyn_section(layout); |
| 795 | rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE, data_shndx, |
| 796 | reloc.get_r_offset()); |
| 797 | } |
| 798 | break; |
| 799 | |
| 800 | case elfcpp::R_386_16: |
| 801 | case elfcpp::R_386_8: |
| 802 | // If building a shared library (or a position-independent |
| 803 | // executable), we need to create a dynamic relocation for |
| 804 | // this location. Because the addend needs to remain in the |
| 805 | // data section, we need to be careful not to apply this |
| 806 | // relocation statically. |
| 807 | if (parameters->output_is_position_independent()) |
| 808 | { |
| 809 | Reloc_section* rel_dyn = target->rel_dyn_section(layout); |
| 810 | unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info()); |
| 811 | rel_dyn->add_local(object, r_sym, r_type, data_shndx, |
| 812 | reloc.get_r_offset()); |
| 813 | } |
| 814 | break; |
| 815 | |
| 816 | case elfcpp::R_386_PC32: |
| 817 | case elfcpp::R_386_PC16: |
| 818 | case elfcpp::R_386_PC8: |
| 819 | break; |
| 820 | |
| 821 | case elfcpp::R_386_PLT32: |
| 822 | // Since we know this is a local symbol, we can handle this as a |
| 823 | // PC32 reloc. |
| 824 | break; |
| 825 | |
| 826 | case elfcpp::R_386_GOTOFF: |
| 827 | case elfcpp::R_386_GOTPC: |
| 828 | // We need a GOT section. |
| 829 | target->got_section(symtab, layout); |
| 830 | break; |
| 831 | |
| 832 | case elfcpp::R_386_GOT32: |
| 833 | { |
| 834 | // The symbol requires a GOT entry. |
| 835 | Output_data_got<32, false>* got = target->got_section(symtab, layout); |
| 836 | unsigned int r_sym = elfcpp::elf_r_sym<32>(reloc.get_r_info()); |
| 837 | if (got->add_local(object, r_sym)) |
| 838 | { |
| 839 | // If we are generating a shared object, we need to add a |
| 840 | // dynamic RELATIVE relocation for this symbol. |
| 841 | if (parameters->output_is_position_independent()) |
| 842 | { |
| 843 | Reloc_section* rel_dyn = target->rel_dyn_section(layout); |
| 844 | rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE, |
| 845 | data_shndx, reloc.get_r_offset()); |
| 846 | } |
| 847 | } |
| 848 | } |
| 849 | break; |
| 850 | |
| 851 | // These are relocations which should only be seen by the |
| 852 | // dynamic linker, and should never be seen here. |
| 853 | case elfcpp::R_386_COPY: |
| 854 | case elfcpp::R_386_GLOB_DAT: |
| 855 | case elfcpp::R_386_JUMP_SLOT: |
| 856 | case elfcpp::R_386_RELATIVE: |
| 857 | case elfcpp::R_386_TLS_TPOFF: |
| 858 | case elfcpp::R_386_TLS_DTPMOD32: |
| 859 | case elfcpp::R_386_TLS_DTPOFF32: |
| 860 | case elfcpp::R_386_TLS_TPOFF32: |
| 861 | case elfcpp::R_386_TLS_DESC: |
| 862 | gold_error(_("%s: unexpected reloc %u in object file"), |
| 863 | object->name().c_str(), r_type); |
| 864 | break; |
| 865 | |
| 866 | // These are initial TLS relocs, which are expected when |
| 867 | // linking. |
| 868 | case elfcpp::R_386_TLS_GD: // Global-dynamic |
| 869 | case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url) |
| 870 | case elfcpp::R_386_TLS_DESC_CALL: |
| 871 | case elfcpp::R_386_TLS_LDM: // Local-dynamic |
| 872 | case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic |
| 873 | case elfcpp::R_386_TLS_IE: // Initial-exec |
| 874 | case elfcpp::R_386_TLS_IE_32: |
| 875 | case elfcpp::R_386_TLS_GOTIE: |
| 876 | case elfcpp::R_386_TLS_LE: // Local-exec |
| 877 | case elfcpp::R_386_TLS_LE_32: |
| 878 | { |
| 879 | bool output_is_shared = parameters->output_is_shared(); |
| 880 | const tls::Tls_optimization optimized_type |
| 881 | = Target_i386::optimize_tls_reloc(!output_is_shared, r_type); |
| 882 | switch (r_type) |
| 883 | { |
| 884 | case elfcpp::R_386_TLS_GD: // Global-dynamic |
| 885 | case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva) |
| 886 | case elfcpp::R_386_TLS_DESC_CALL: |
| 887 | // FIXME: If not relaxing to LE, we need to generate |
| 888 | // DTPMOD32 and DTPOFF32 relocs. |
| 889 | if (optimized_type != tls::TLSOPT_TO_LE) |
| 890 | unsupported_reloc_local(object, r_type); |
| 891 | break; |
| 892 | |
| 893 | case elfcpp::R_386_TLS_LDM: // Local-dynamic |
| 894 | // FIXME: If not relaxing to LE, we need to generate a |
| 895 | // DTPMOD32 reloc. |
| 896 | if (optimized_type != tls::TLSOPT_TO_LE) |
| 897 | unsupported_reloc_local(object, r_type); |
| 898 | break; |
| 899 | |
| 900 | case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic |
| 901 | break; |
| 902 | |
| 903 | case elfcpp::R_386_TLS_IE: // Initial-exec |
| 904 | case elfcpp::R_386_TLS_IE_32: |
| 905 | case elfcpp::R_386_TLS_GOTIE: |
| 906 | // FIXME: If not relaxing to LE, we need to generate a |
| 907 | // TPOFF or TPOFF32 reloc. |
| 908 | if (optimized_type != tls::TLSOPT_TO_LE) |
| 909 | unsupported_reloc_local(object, r_type); |
| 910 | break; |
| 911 | |
| 912 | case elfcpp::R_386_TLS_LE: // Local-exec |
| 913 | case elfcpp::R_386_TLS_LE_32: |
| 914 | // FIXME: If generating a shared object, we need to copy |
| 915 | // this relocation into the object. |
| 916 | gold_assert(!output_is_shared); |
| 917 | break; |
| 918 | |
| 919 | default: |
| 920 | gold_unreachable(); |
| 921 | } |
| 922 | } |
| 923 | break; |
| 924 | |
| 925 | case elfcpp::R_386_32PLT: |
| 926 | case elfcpp::R_386_TLS_GD_32: |
| 927 | case elfcpp::R_386_TLS_GD_PUSH: |
| 928 | case elfcpp::R_386_TLS_GD_CALL: |
| 929 | case elfcpp::R_386_TLS_GD_POP: |
| 930 | case elfcpp::R_386_TLS_LDM_32: |
| 931 | case elfcpp::R_386_TLS_LDM_PUSH: |
| 932 | case elfcpp::R_386_TLS_LDM_CALL: |
| 933 | case elfcpp::R_386_TLS_LDM_POP: |
| 934 | case elfcpp::R_386_USED_BY_INTEL_200: |
| 935 | default: |
| 936 | unsupported_reloc_local(object, r_type); |
| 937 | break; |
| 938 | } |
| 939 | } |
| 940 | |
| 941 | // Report an unsupported relocation against a global symbol. |
| 942 | |
| 943 | void |
| 944 | Target_i386::Scan::unsupported_reloc_global(Sized_relobj<32, false>* object, |
| 945 | unsigned int r_type, |
| 946 | Symbol* gsym) |
| 947 | { |
| 948 | gold_error(_("%s: unsupported reloc %u against global symbol %s"), |
| 949 | object->name().c_str(), r_type, gsym->name()); |
| 950 | } |
| 951 | |
| 952 | // Scan a relocation for a global symbol. |
| 953 | |
| 954 | inline void |
| 955 | Target_i386::Scan::global(const General_options& options, |
| 956 | Symbol_table* symtab, |
| 957 | Layout* layout, |
| 958 | Target_i386* target, |
| 959 | Sized_relobj<32, false>* object, |
| 960 | unsigned int data_shndx, |
| 961 | const elfcpp::Rel<32, false>& reloc, |
| 962 | unsigned int r_type, |
| 963 | Symbol* gsym) |
| 964 | { |
| 965 | switch (r_type) |
| 966 | { |
| 967 | case elfcpp::R_386_NONE: |
| 968 | case elfcpp::R_386_GNU_VTINHERIT: |
| 969 | case elfcpp::R_386_GNU_VTENTRY: |
| 970 | break; |
| 971 | |
| 972 | case elfcpp::R_386_32: |
| 973 | case elfcpp::R_386_16: |
| 974 | case elfcpp::R_386_8: |
| 975 | { |
| 976 | // Make a PLT entry if necessary. |
| 977 | if (gsym->needs_plt_entry()) |
| 978 | { |
| 979 | target->make_plt_entry(symtab, layout, gsym); |
| 980 | // Since this is not a PC-relative relocation, we may be |
| 981 | // taking the address of a function. In that case we need to |
| 982 | // set the entry in the dynamic symbol table to the address of |
| 983 | // the PLT entry. |
| 984 | if (gsym->is_from_dynobj()) |
| 985 | gsym->set_needs_dynsym_value(); |
| 986 | } |
| 987 | // Make a dynamic relocation if necessary. |
| 988 | if (gsym->needs_dynamic_reloc(true, false)) |
| 989 | { |
| 990 | if (target->may_need_copy_reloc(gsym)) |
| 991 | { |
| 992 | target->copy_reloc(&options, symtab, layout, object, data_shndx, |
| 993 | gsym, reloc); |
| 994 | } |
| 995 | else if (r_type == elfcpp::R_386_32 |
| 996 | && gsym->can_use_relative_reloc(false)) |
| 997 | { |
| 998 | Reloc_section* rel_dyn = target->rel_dyn_section(layout); |
| 999 | rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE, data_shndx, |
| 1000 | reloc.get_r_offset()); |
| 1001 | } |
| 1002 | else |
| 1003 | { |
| 1004 | Reloc_section* rel_dyn = target->rel_dyn_section(layout); |
| 1005 | rel_dyn->add_global(gsym, r_type, object, data_shndx, |
| 1006 | reloc.get_r_offset()); |
| 1007 | } |
| 1008 | } |
| 1009 | } |
| 1010 | break; |
| 1011 | |
| 1012 | case elfcpp::R_386_PC32: |
| 1013 | case elfcpp::R_386_PC16: |
| 1014 | case elfcpp::R_386_PC8: |
| 1015 | { |
| 1016 | // Make a PLT entry if necessary. |
| 1017 | if (gsym->needs_plt_entry()) |
| 1018 | target->make_plt_entry(symtab, layout, gsym); |
| 1019 | // Make a dynamic relocation if necessary. |
| 1020 | bool is_function_call = (gsym->type() == elfcpp::STT_FUNC); |
| 1021 | if (gsym->needs_dynamic_reloc(false, is_function_call)) |
| 1022 | { |
| 1023 | if (target->may_need_copy_reloc(gsym)) |
| 1024 | { |
| 1025 | target->copy_reloc(&options, symtab, layout, object, data_shndx, |
| 1026 | gsym, reloc); |
| 1027 | } |
| 1028 | else |
| 1029 | { |
| 1030 | Reloc_section* rel_dyn = target->rel_dyn_section(layout); |
| 1031 | rel_dyn->add_global(gsym, r_type, object, data_shndx, |
| 1032 | reloc.get_r_offset()); |
| 1033 | } |
| 1034 | } |
| 1035 | } |
| 1036 | break; |
| 1037 | |
| 1038 | case elfcpp::R_386_GOT32: |
| 1039 | { |
| 1040 | // The symbol requires a GOT entry. |
| 1041 | Output_data_got<32, false>* got = target->got_section(symtab, layout); |
| 1042 | if (got->add_global(gsym)) |
| 1043 | { |
| 1044 | // If this symbol is not fully resolved, we need to add a |
| 1045 | // dynamic relocation for it. |
| 1046 | if (!gsym->final_value_is_known()) |
| 1047 | { |
| 1048 | Reloc_section* rel_dyn = target->rel_dyn_section(layout); |
| 1049 | if (gsym->is_from_dynobj() |
| 1050 | || gsym->is_preemptible()) |
| 1051 | rel_dyn->add_global(gsym, elfcpp::R_386_GLOB_DAT, got, |
| 1052 | gsym->got_offset()); |
| 1053 | else |
| 1054 | { |
| 1055 | rel_dyn->add_local(object, 0, elfcpp::R_386_RELATIVE, |
| 1056 | got, gsym->got_offset()); |
| 1057 | // Make sure we write the link-time value to the GOT. |
| 1058 | gsym->set_needs_value_in_got(); |
| 1059 | } |
| 1060 | } |
| 1061 | } |
| 1062 | } |
| 1063 | break; |
| 1064 | |
| 1065 | case elfcpp::R_386_PLT32: |
| 1066 | // If the symbol is fully resolved, this is just a PC32 reloc. |
| 1067 | // Otherwise we need a PLT entry. |
| 1068 | if (gsym->final_value_is_known()) |
| 1069 | break; |
| 1070 | // If building a shared library, we can also skip the PLT entry |
| 1071 | // if the symbol is defined in the output file and is protected |
| 1072 | // or hidden. |
| 1073 | if (gsym->is_defined() |
| 1074 | && !gsym->is_from_dynobj() |
| 1075 | && !gsym->is_preemptible()) |
| 1076 | break; |
| 1077 | target->make_plt_entry(symtab, layout, gsym); |
| 1078 | break; |
| 1079 | |
| 1080 | case elfcpp::R_386_GOTOFF: |
| 1081 | case elfcpp::R_386_GOTPC: |
| 1082 | // We need a GOT section. |
| 1083 | target->got_section(symtab, layout); |
| 1084 | break; |
| 1085 | |
| 1086 | // These are relocations which should only be seen by the |
| 1087 | // dynamic linker, and should never be seen here. |
| 1088 | case elfcpp::R_386_COPY: |
| 1089 | case elfcpp::R_386_GLOB_DAT: |
| 1090 | case elfcpp::R_386_JUMP_SLOT: |
| 1091 | case elfcpp::R_386_RELATIVE: |
| 1092 | case elfcpp::R_386_TLS_TPOFF: |
| 1093 | case elfcpp::R_386_TLS_DTPMOD32: |
| 1094 | case elfcpp::R_386_TLS_DTPOFF32: |
| 1095 | case elfcpp::R_386_TLS_TPOFF32: |
| 1096 | case elfcpp::R_386_TLS_DESC: |
| 1097 | gold_error(_("%s: unexpected reloc %u in object file"), |
| 1098 | object->name().c_str(), r_type); |
| 1099 | break; |
| 1100 | |
| 1101 | // These are initial tls relocs, which are expected when |
| 1102 | // linking. |
| 1103 | case elfcpp::R_386_TLS_GD: // Global-dynamic |
| 1104 | case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url) |
| 1105 | case elfcpp::R_386_TLS_DESC_CALL: |
| 1106 | case elfcpp::R_386_TLS_LDM: // Local-dynamic |
| 1107 | case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic |
| 1108 | case elfcpp::R_386_TLS_IE: // Initial-exec |
| 1109 | case elfcpp::R_386_TLS_IE_32: |
| 1110 | case elfcpp::R_386_TLS_GOTIE: |
| 1111 | case elfcpp::R_386_TLS_LE: // Local-exec |
| 1112 | case elfcpp::R_386_TLS_LE_32: |
| 1113 | { |
| 1114 | const bool is_final = gsym->final_value_is_known(); |
| 1115 | const tls::Tls_optimization optimized_type |
| 1116 | = Target_i386::optimize_tls_reloc(is_final, r_type); |
| 1117 | switch (r_type) |
| 1118 | { |
| 1119 | case elfcpp::R_386_TLS_GD: // Global-dynamic |
| 1120 | case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (~oliva url) |
| 1121 | case elfcpp::R_386_TLS_DESC_CALL: |
| 1122 | // FIXME: If not relaxing to LE, we need to generate |
| 1123 | // DTPMOD32 and DTPOFF32 relocs. |
| 1124 | if (optimized_type != tls::TLSOPT_TO_LE) |
| 1125 | unsupported_reloc_global(object, r_type, gsym); |
| 1126 | break; |
| 1127 | |
| 1128 | case elfcpp::R_386_TLS_LDM: // Local-dynamic |
| 1129 | // FIXME: If not relaxing to LE, we need to generate a |
| 1130 | // DTPMOD32 reloc. |
| 1131 | if (optimized_type != tls::TLSOPT_TO_LE) |
| 1132 | unsupported_reloc_global(object, r_type, gsym); |
| 1133 | break; |
| 1134 | |
| 1135 | case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic |
| 1136 | break; |
| 1137 | |
| 1138 | case elfcpp::R_386_TLS_IE: // Initial-exec |
| 1139 | case elfcpp::R_386_TLS_IE_32: |
| 1140 | case elfcpp::R_386_TLS_GOTIE: |
| 1141 | // FIXME: If not relaxing to LE, we need to generate a |
| 1142 | // TPOFF or TPOFF32 reloc. |
| 1143 | if (optimized_type != tls::TLSOPT_TO_LE) |
| 1144 | unsupported_reloc_global(object, r_type, gsym); |
| 1145 | break; |
| 1146 | |
| 1147 | case elfcpp::R_386_TLS_LE: // Local-exec |
| 1148 | case elfcpp::R_386_TLS_LE_32: |
| 1149 | // FIXME: If generating a shared object, we need to copy |
| 1150 | // this relocation into the object. |
| 1151 | gold_assert(!parameters->output_is_shared()); |
| 1152 | break; |
| 1153 | |
| 1154 | default: |
| 1155 | gold_unreachable(); |
| 1156 | } |
| 1157 | } |
| 1158 | break; |
| 1159 | |
| 1160 | case elfcpp::R_386_32PLT: |
| 1161 | case elfcpp::R_386_TLS_GD_32: |
| 1162 | case elfcpp::R_386_TLS_GD_PUSH: |
| 1163 | case elfcpp::R_386_TLS_GD_CALL: |
| 1164 | case elfcpp::R_386_TLS_GD_POP: |
| 1165 | case elfcpp::R_386_TLS_LDM_32: |
| 1166 | case elfcpp::R_386_TLS_LDM_PUSH: |
| 1167 | case elfcpp::R_386_TLS_LDM_CALL: |
| 1168 | case elfcpp::R_386_TLS_LDM_POP: |
| 1169 | case elfcpp::R_386_USED_BY_INTEL_200: |
| 1170 | default: |
| 1171 | unsupported_reloc_global(object, r_type, gsym); |
| 1172 | break; |
| 1173 | } |
| 1174 | } |
| 1175 | |
| 1176 | // Scan relocations for a section. |
| 1177 | |
| 1178 | void |
| 1179 | Target_i386::scan_relocs(const General_options& options, |
| 1180 | Symbol_table* symtab, |
| 1181 | Layout* layout, |
| 1182 | Sized_relobj<32, false>* object, |
| 1183 | unsigned int data_shndx, |
| 1184 | unsigned int sh_type, |
| 1185 | const unsigned char* prelocs, |
| 1186 | size_t reloc_count, |
| 1187 | Output_section* output_section, |
| 1188 | bool needs_special_offset_handling, |
| 1189 | size_t local_symbol_count, |
| 1190 | const unsigned char* plocal_symbols) |
| 1191 | { |
| 1192 | if (sh_type == elfcpp::SHT_RELA) |
| 1193 | { |
| 1194 | gold_error(_("%s: unsupported RELA reloc section"), |
| 1195 | object->name().c_str()); |
| 1196 | return; |
| 1197 | } |
| 1198 | |
| 1199 | gold::scan_relocs<32, false, Target_i386, elfcpp::SHT_REL, |
| 1200 | Target_i386::Scan>( |
| 1201 | options, |
| 1202 | symtab, |
| 1203 | layout, |
| 1204 | this, |
| 1205 | object, |
| 1206 | data_shndx, |
| 1207 | prelocs, |
| 1208 | reloc_count, |
| 1209 | output_section, |
| 1210 | needs_special_offset_handling, |
| 1211 | local_symbol_count, |
| 1212 | plocal_symbols); |
| 1213 | } |
| 1214 | |
| 1215 | // Finalize the sections. |
| 1216 | |
| 1217 | void |
| 1218 | Target_i386::do_finalize_sections(Layout* layout) |
| 1219 | { |
| 1220 | // Fill in some more dynamic tags. |
| 1221 | Output_data_dynamic* const odyn = layout->dynamic_data(); |
| 1222 | if (odyn != NULL) |
| 1223 | { |
| 1224 | if (this->got_plt_ != NULL) |
| 1225 | odyn->add_section_address(elfcpp::DT_PLTGOT, this->got_plt_); |
| 1226 | |
| 1227 | if (this->plt_ != NULL) |
| 1228 | { |
| 1229 | const Output_data* od = this->plt_->rel_plt(); |
| 1230 | odyn->add_section_size(elfcpp::DT_PLTRELSZ, od); |
| 1231 | odyn->add_section_address(elfcpp::DT_JMPREL, od); |
| 1232 | odyn->add_constant(elfcpp::DT_PLTREL, elfcpp::DT_REL); |
| 1233 | } |
| 1234 | |
| 1235 | if (this->rel_dyn_ != NULL) |
| 1236 | { |
| 1237 | const Output_data* od = this->rel_dyn_; |
| 1238 | odyn->add_section_address(elfcpp::DT_REL, od); |
| 1239 | odyn->add_section_size(elfcpp::DT_RELSZ, od); |
| 1240 | odyn->add_constant(elfcpp::DT_RELENT, |
| 1241 | elfcpp::Elf_sizes<32>::rel_size); |
| 1242 | } |
| 1243 | |
| 1244 | if (!parameters->output_is_shared()) |
| 1245 | { |
| 1246 | // The value of the DT_DEBUG tag is filled in by the dynamic |
| 1247 | // linker at run time, and used by the debugger. |
| 1248 | odyn->add_constant(elfcpp::DT_DEBUG, 0); |
| 1249 | } |
| 1250 | } |
| 1251 | |
| 1252 | // Emit any relocs we saved in an attempt to avoid generating COPY |
| 1253 | // relocs. |
| 1254 | if (this->copy_relocs_ == NULL) |
| 1255 | return; |
| 1256 | if (this->copy_relocs_->any_to_emit()) |
| 1257 | { |
| 1258 | Reloc_section* rel_dyn = this->rel_dyn_section(layout); |
| 1259 | this->copy_relocs_->emit(rel_dyn); |
| 1260 | } |
| 1261 | delete this->copy_relocs_; |
| 1262 | this->copy_relocs_ = NULL; |
| 1263 | } |
| 1264 | |
| 1265 | // Return whether a direct absolute static relocation needs to be applied. |
| 1266 | // In cases where Scan::local() or Scan::global() has created |
| 1267 | // a dynamic relocation other than R_386_RELATIVE, the addend |
| 1268 | // of the relocation is carried in the data, and we must not |
| 1269 | // apply the static relocation. |
| 1270 | |
| 1271 | inline bool |
| 1272 | Target_i386::Relocate::should_apply_static_reloc(const Sized_symbol<32>* gsym, |
| 1273 | bool is_absolute_ref, |
| 1274 | bool is_function_call, |
| 1275 | bool is_32bit) |
| 1276 | { |
| 1277 | // For local symbols, we will have created a non-RELATIVE dynamic |
| 1278 | // relocation only if (a) the output is position independent, |
| 1279 | // (b) the relocation is absolute (not pc- or segment-relative), and |
| 1280 | // (c) the relocation is not 32 bits wide. |
| 1281 | if (gsym == NULL) |
| 1282 | return !(parameters->output_is_position_independent() |
| 1283 | && is_absolute_ref |
| 1284 | && !is_32bit); |
| 1285 | |
| 1286 | // For global symbols, we use the same helper routines used in the scan pass. |
| 1287 | return !(gsym->needs_dynamic_reloc(is_absolute_ref, is_function_call) |
| 1288 | && !gsym->can_use_relative_reloc(is_function_call)); |
| 1289 | } |
| 1290 | |
| 1291 | // Perform a relocation. |
| 1292 | |
| 1293 | inline bool |
| 1294 | Target_i386::Relocate::relocate(const Relocate_info<32, false>* relinfo, |
| 1295 | Target_i386* target, |
| 1296 | size_t relnum, |
| 1297 | const elfcpp::Rel<32, false>& rel, |
| 1298 | unsigned int r_type, |
| 1299 | const Sized_symbol<32>* gsym, |
| 1300 | const Symbol_value<32>* psymval, |
| 1301 | unsigned char* view, |
| 1302 | elfcpp::Elf_types<32>::Elf_Addr address, |
| 1303 | off_t view_size) |
| 1304 | { |
| 1305 | if (this->skip_call_tls_get_addr_) |
| 1306 | { |
| 1307 | if (r_type != elfcpp::R_386_PLT32 |
| 1308 | || gsym == NULL |
| 1309 | || strcmp(gsym->name(), "___tls_get_addr") != 0) |
| 1310 | gold_error_at_location(relinfo, relnum, rel.get_r_offset(), |
| 1311 | _("missing expected TLS relocation")); |
| 1312 | else |
| 1313 | { |
| 1314 | this->skip_call_tls_get_addr_ = false; |
| 1315 | return false; |
| 1316 | } |
| 1317 | } |
| 1318 | |
| 1319 | // Pick the value to use for symbols defined in shared objects. |
| 1320 | Symbol_value<32> symval; |
| 1321 | if (gsym != NULL |
| 1322 | && (gsym->is_from_dynobj() |
| 1323 | || (parameters->output_is_shared() |
| 1324 | && gsym->is_preemptible())) |
| 1325 | && gsym->has_plt_offset()) |
| 1326 | { |
| 1327 | symval.set_output_value(target->plt_section()->address() |
| 1328 | + gsym->plt_offset()); |
| 1329 | psymval = &symval; |
| 1330 | } |
| 1331 | |
| 1332 | const Sized_relobj<32, false>* object = relinfo->object; |
| 1333 | |
| 1334 | // Get the GOT offset if needed. |
| 1335 | // The GOT pointer points to the end of the GOT section. |
| 1336 | // We need to subtract the size of the GOT section to get |
| 1337 | // the actual offset to use in the relocation. |
| 1338 | bool have_got_offset = false; |
| 1339 | unsigned int got_offset = 0; |
| 1340 | switch (r_type) |
| 1341 | { |
| 1342 | case elfcpp::R_386_GOT32: |
| 1343 | if (gsym != NULL) |
| 1344 | { |
| 1345 | gold_assert(gsym->has_got_offset()); |
| 1346 | got_offset = gsym->got_offset() - target->got_size(); |
| 1347 | } |
| 1348 | else |
| 1349 | { |
| 1350 | unsigned int r_sym = elfcpp::elf_r_sym<32>(rel.get_r_info()); |
| 1351 | got_offset = object->local_got_offset(r_sym) - target->got_size(); |
| 1352 | } |
| 1353 | have_got_offset = true; |
| 1354 | break; |
| 1355 | |
| 1356 | default: |
| 1357 | break; |
| 1358 | } |
| 1359 | |
| 1360 | switch (r_type) |
| 1361 | { |
| 1362 | case elfcpp::R_386_NONE: |
| 1363 | case elfcpp::R_386_GNU_VTINHERIT: |
| 1364 | case elfcpp::R_386_GNU_VTENTRY: |
| 1365 | break; |
| 1366 | |
| 1367 | case elfcpp::R_386_32: |
| 1368 | if (should_apply_static_reloc(gsym, true, false, true)) |
| 1369 | Relocate_functions<32, false>::rel32(view, object, psymval); |
| 1370 | break; |
| 1371 | |
| 1372 | case elfcpp::R_386_PC32: |
| 1373 | { |
| 1374 | bool is_function_call = (gsym != NULL |
| 1375 | && gsym->type() == elfcpp::STT_FUNC); |
| 1376 | if (should_apply_static_reloc(gsym, false, is_function_call, true)) |
| 1377 | Relocate_functions<32, false>::pcrel32(view, object, psymval, address); |
| 1378 | } |
| 1379 | break; |
| 1380 | |
| 1381 | case elfcpp::R_386_16: |
| 1382 | if (should_apply_static_reloc(gsym, true, false, false)) |
| 1383 | Relocate_functions<32, false>::rel16(view, object, psymval); |
| 1384 | break; |
| 1385 | |
| 1386 | case elfcpp::R_386_PC16: |
| 1387 | { |
| 1388 | bool is_function_call = (gsym != NULL |
| 1389 | && gsym->type() == elfcpp::STT_FUNC); |
| 1390 | if (should_apply_static_reloc(gsym, false, is_function_call, false)) |
| 1391 | Relocate_functions<32, false>::pcrel32(view, object, psymval, address); |
| 1392 | } |
| 1393 | break; |
| 1394 | |
| 1395 | case elfcpp::R_386_8: |
| 1396 | if (should_apply_static_reloc(gsym, true, false, false)) |
| 1397 | Relocate_functions<32, false>::rel8(view, object, psymval); |
| 1398 | break; |
| 1399 | |
| 1400 | case elfcpp::R_386_PC8: |
| 1401 | { |
| 1402 | bool is_function_call = (gsym != NULL |
| 1403 | && gsym->type() == elfcpp::STT_FUNC); |
| 1404 | if (should_apply_static_reloc(gsym, false, is_function_call, false)) |
| 1405 | Relocate_functions<32, false>::pcrel32(view, object, psymval, address); |
| 1406 | } |
| 1407 | break; |
| 1408 | |
| 1409 | case elfcpp::R_386_PLT32: |
| 1410 | gold_assert(gsym == NULL |
| 1411 | || gsym->has_plt_offset() |
| 1412 | || gsym->final_value_is_known()); |
| 1413 | Relocate_functions<32, false>::pcrel32(view, object, psymval, address); |
| 1414 | break; |
| 1415 | |
| 1416 | case elfcpp::R_386_GOT32: |
| 1417 | gold_assert(have_got_offset); |
| 1418 | Relocate_functions<32, false>::rel32(view, got_offset); |
| 1419 | break; |
| 1420 | |
| 1421 | case elfcpp::R_386_GOTOFF: |
| 1422 | { |
| 1423 | elfcpp::Elf_types<32>::Elf_Addr value; |
| 1424 | value = (psymval->value(object, 0) |
| 1425 | - target->got_plt_section()->address()); |
| 1426 | Relocate_functions<32, false>::rel32(view, value); |
| 1427 | } |
| 1428 | break; |
| 1429 | |
| 1430 | case elfcpp::R_386_GOTPC: |
| 1431 | { |
| 1432 | elfcpp::Elf_types<32>::Elf_Addr value; |
| 1433 | value = target->got_plt_section()->address(); |
| 1434 | Relocate_functions<32, false>::pcrel32(view, value, address); |
| 1435 | } |
| 1436 | break; |
| 1437 | |
| 1438 | case elfcpp::R_386_COPY: |
| 1439 | case elfcpp::R_386_GLOB_DAT: |
| 1440 | case elfcpp::R_386_JUMP_SLOT: |
| 1441 | case elfcpp::R_386_RELATIVE: |
| 1442 | // These are outstanding tls relocs, which are unexpected when |
| 1443 | // linking. |
| 1444 | case elfcpp::R_386_TLS_TPOFF: |
| 1445 | case elfcpp::R_386_TLS_DTPMOD32: |
| 1446 | case elfcpp::R_386_TLS_DTPOFF32: |
| 1447 | case elfcpp::R_386_TLS_TPOFF32: |
| 1448 | case elfcpp::R_386_TLS_DESC: |
| 1449 | gold_error_at_location(relinfo, relnum, rel.get_r_offset(), |
| 1450 | _("unexpected reloc %u in object file"), |
| 1451 | r_type); |
| 1452 | break; |
| 1453 | |
| 1454 | // These are initial tls relocs, which are expected when |
| 1455 | // linking. |
| 1456 | case elfcpp::R_386_TLS_GD: // Global-dynamic |
| 1457 | case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url) |
| 1458 | case elfcpp::R_386_TLS_DESC_CALL: |
| 1459 | case elfcpp::R_386_TLS_LDM: // Local-dynamic |
| 1460 | case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic |
| 1461 | case elfcpp::R_386_TLS_IE: // Initial-exec |
| 1462 | case elfcpp::R_386_TLS_IE_32: |
| 1463 | case elfcpp::R_386_TLS_GOTIE: |
| 1464 | case elfcpp::R_386_TLS_LE: // Local-exec |
| 1465 | case elfcpp::R_386_TLS_LE_32: |
| 1466 | this->relocate_tls(relinfo, relnum, rel, r_type, gsym, psymval, view, |
| 1467 | address, view_size); |
| 1468 | break; |
| 1469 | |
| 1470 | case elfcpp::R_386_32PLT: |
| 1471 | case elfcpp::R_386_TLS_GD_32: |
| 1472 | case elfcpp::R_386_TLS_GD_PUSH: |
| 1473 | case elfcpp::R_386_TLS_GD_CALL: |
| 1474 | case elfcpp::R_386_TLS_GD_POP: |
| 1475 | case elfcpp::R_386_TLS_LDM_32: |
| 1476 | case elfcpp::R_386_TLS_LDM_PUSH: |
| 1477 | case elfcpp::R_386_TLS_LDM_CALL: |
| 1478 | case elfcpp::R_386_TLS_LDM_POP: |
| 1479 | case elfcpp::R_386_USED_BY_INTEL_200: |
| 1480 | default: |
| 1481 | gold_error_at_location(relinfo, relnum, rel.get_r_offset(), |
| 1482 | _("unsupported reloc %u"), |
| 1483 | r_type); |
| 1484 | break; |
| 1485 | } |
| 1486 | |
| 1487 | return true; |
| 1488 | } |
| 1489 | |
| 1490 | // Perform a TLS relocation. |
| 1491 | |
| 1492 | inline void |
| 1493 | Target_i386::Relocate::relocate_tls(const Relocate_info<32, false>* relinfo, |
| 1494 | size_t relnum, |
| 1495 | const elfcpp::Rel<32, false>& rel, |
| 1496 | unsigned int r_type, |
| 1497 | const Sized_symbol<32>* gsym, |
| 1498 | const Symbol_value<32>* psymval, |
| 1499 | unsigned char* view, |
| 1500 | elfcpp::Elf_types<32>::Elf_Addr, |
| 1501 | off_t view_size) |
| 1502 | { |
| 1503 | Output_segment* tls_segment = relinfo->layout->tls_segment(); |
| 1504 | if (tls_segment == NULL) |
| 1505 | { |
| 1506 | gold_error_at_location(relinfo, relnum, rel.get_r_offset(), |
| 1507 | _("TLS reloc but no TLS segment")); |
| 1508 | return; |
| 1509 | } |
| 1510 | |
| 1511 | elfcpp::Elf_types<32>::Elf_Addr value = psymval->value(relinfo->object, 0); |
| 1512 | |
| 1513 | const bool is_final = (gsym == NULL |
| 1514 | ? !parameters->output_is_position_independent() |
| 1515 | : gsym->final_value_is_known()); |
| 1516 | const tls::Tls_optimization optimized_type |
| 1517 | = Target_i386::optimize_tls_reloc(is_final, r_type); |
| 1518 | switch (r_type) |
| 1519 | { |
| 1520 | case elfcpp::R_386_TLS_GD: // Global-dynamic |
| 1521 | if (optimized_type == tls::TLSOPT_TO_LE) |
| 1522 | { |
| 1523 | this->tls_gd_to_le(relinfo, relnum, tls_segment, |
| 1524 | rel, r_type, value, view, |
| 1525 | view_size); |
| 1526 | break; |
| 1527 | } |
| 1528 | gold_error_at_location(relinfo, relnum, rel.get_r_offset(), |
| 1529 | _("unsupported reloc %u"), |
| 1530 | r_type); |
| 1531 | break; |
| 1532 | |
| 1533 | case elfcpp::R_386_TLS_GOTDESC: // Global-dynamic (from ~oliva url) |
| 1534 | case elfcpp::R_386_TLS_DESC_CALL: |
| 1535 | gold_error_at_location(relinfo, relnum, rel.get_r_offset(), |
| 1536 | _("unsupported reloc %u"), |
| 1537 | r_type); |
| 1538 | break; |
| 1539 | |
| 1540 | case elfcpp::R_386_TLS_LDM: // Local-dynamic |
| 1541 | if (this->local_dynamic_type_ == LOCAL_DYNAMIC_SUN) |
| 1542 | { |
| 1543 | gold_error_at_location(relinfo, relnum, rel.get_r_offset(), |
| 1544 | _("both SUN and GNU model " |
| 1545 | "TLS relocations")); |
| 1546 | break; |
| 1547 | } |
| 1548 | this->local_dynamic_type_ = LOCAL_DYNAMIC_GNU; |
| 1549 | if (optimized_type == tls::TLSOPT_TO_LE) |
| 1550 | { |
| 1551 | this->tls_ld_to_le(relinfo, relnum, tls_segment, rel, r_type, |
| 1552 | value, view, view_size); |
| 1553 | break; |
| 1554 | } |
| 1555 | gold_error_at_location(relinfo, relnum, rel.get_r_offset(), |
| 1556 | _("unsupported reloc %u"), |
| 1557 | r_type); |
| 1558 | break; |
| 1559 | |
| 1560 | case elfcpp::R_386_TLS_LDO_32: // Alternate local-dynamic |
| 1561 | // This reloc can appear in debugging sections, in which case we |
| 1562 | // won't see the TLS_LDM reloc. The local_dynamic_type field |
| 1563 | // tells us this. |
| 1564 | if (optimized_type != tls::TLSOPT_TO_LE |
| 1565 | || this->local_dynamic_type_ == LOCAL_DYNAMIC_NONE) |
| 1566 | value = value - tls_segment->vaddr(); |
| 1567 | else if (this->local_dynamic_type_ == LOCAL_DYNAMIC_GNU) |
| 1568 | value = value - (tls_segment->vaddr() + tls_segment->memsz()); |
| 1569 | else |
| 1570 | value = tls_segment->vaddr() + tls_segment->memsz() - value; |
| 1571 | Relocate_functions<32, false>::rel32(view, value); |
| 1572 | break; |
| 1573 | |
| 1574 | case elfcpp::R_386_TLS_IE: // Initial-exec |
| 1575 | case elfcpp::R_386_TLS_GOTIE: |
| 1576 | case elfcpp::R_386_TLS_IE_32: |
| 1577 | if (optimized_type == tls::TLSOPT_TO_LE) |
| 1578 | { |
| 1579 | Target_i386::Relocate::tls_ie_to_le(relinfo, relnum, tls_segment, |
| 1580 | rel, r_type, value, view, |
| 1581 | view_size); |
| 1582 | break; |
| 1583 | } |
| 1584 | gold_error_at_location(relinfo, relnum, rel.get_r_offset(), |
| 1585 | _("unsupported reloc %u"), |
| 1586 | r_type); |
| 1587 | break; |
| 1588 | |
| 1589 | case elfcpp::R_386_TLS_LE: // Local-exec |
| 1590 | value = value - (tls_segment->vaddr() + tls_segment->memsz()); |
| 1591 | Relocate_functions<32, false>::rel32(view, value); |
| 1592 | break; |
| 1593 | |
| 1594 | case elfcpp::R_386_TLS_LE_32: |
| 1595 | value = tls_segment->vaddr() + tls_segment->memsz() - value; |
| 1596 | Relocate_functions<32, false>::rel32(view, value); |
| 1597 | break; |
| 1598 | } |
| 1599 | } |
| 1600 | |
| 1601 | // Do a relocation in which we convert a TLS General-Dynamic to a |
| 1602 | // Local-Exec. |
| 1603 | |
| 1604 | inline void |
| 1605 | Target_i386::Relocate::tls_gd_to_le(const Relocate_info<32, false>* relinfo, |
| 1606 | size_t relnum, |
| 1607 | Output_segment* tls_segment, |
| 1608 | const elfcpp::Rel<32, false>& rel, |
| 1609 | unsigned int, |
| 1610 | elfcpp::Elf_types<32>::Elf_Addr value, |
| 1611 | unsigned char* view, |
| 1612 | off_t view_size) |
| 1613 | { |
| 1614 | // leal foo(,%reg,1),%eax; call ___tls_get_addr |
| 1615 | // ==> movl %gs:0,%eax; subl $foo@tpoff,%eax |
| 1616 | // leal foo(%reg),%eax; call ___tls_get_addr |
| 1617 | // ==> movl %gs:0,%eax; subl $foo@tpoff,%eax |
| 1618 | |
| 1619 | tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2); |
| 1620 | tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9); |
| 1621 | |
| 1622 | unsigned char op1 = view[-1]; |
| 1623 | unsigned char op2 = view[-2]; |
| 1624 | |
| 1625 | tls::check_tls(relinfo, relnum, rel.get_r_offset(), |
| 1626 | op2 == 0x8d || op2 == 0x04); |
| 1627 | tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8); |
| 1628 | |
| 1629 | int roff = 5; |
| 1630 | |
| 1631 | if (op2 == 0x04) |
| 1632 | { |
| 1633 | tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -3); |
| 1634 | tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[-3] == 0x8d); |
| 1635 | tls::check_tls(relinfo, relnum, rel.get_r_offset(), |
| 1636 | ((op1 & 0xc7) == 0x05 && op1 != (4 << 3))); |
| 1637 | memcpy(view - 3, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12); |
| 1638 | } |
| 1639 | else |
| 1640 | { |
| 1641 | tls::check_tls(relinfo, relnum, rel.get_r_offset(), |
| 1642 | (op1 & 0xf8) == 0x80 && (op1 & 7) != 4); |
| 1643 | if (static_cast<off_t>(rel.get_r_offset() + 9) < view_size |
| 1644 | && view[9] == 0x90) |
| 1645 | { |
| 1646 | // There is a trailing nop. Use the size byte subl. |
| 1647 | memcpy(view - 2, "\x65\xa1\0\0\0\0\x81\xe8\0\0\0", 12); |
| 1648 | roff = 6; |
| 1649 | } |
| 1650 | else |
| 1651 | { |
| 1652 | // Use the five byte subl. |
| 1653 | memcpy(view - 2, "\x65\xa1\0\0\0\0\x2d\0\0\0", 11); |
| 1654 | } |
| 1655 | } |
| 1656 | |
| 1657 | value = tls_segment->vaddr() + tls_segment->memsz() - value; |
| 1658 | Relocate_functions<32, false>::rel32(view + roff, value); |
| 1659 | |
| 1660 | // The next reloc should be a PLT32 reloc against __tls_get_addr. |
| 1661 | // We can skip it. |
| 1662 | this->skip_call_tls_get_addr_ = true; |
| 1663 | } |
| 1664 | |
| 1665 | // Do a relocation in which we convert a TLS Local-Dynamic to a |
| 1666 | // Local-Exec. |
| 1667 | |
| 1668 | inline void |
| 1669 | Target_i386::Relocate::tls_ld_to_le(const Relocate_info<32, false>* relinfo, |
| 1670 | size_t relnum, |
| 1671 | Output_segment*, |
| 1672 | const elfcpp::Rel<32, false>& rel, |
| 1673 | unsigned int, |
| 1674 | elfcpp::Elf_types<32>::Elf_Addr, |
| 1675 | unsigned char* view, |
| 1676 | off_t view_size) |
| 1677 | { |
| 1678 | // leal foo(%reg), %eax; call ___tls_get_addr |
| 1679 | // ==> movl %gs:0,%eax; nop; leal 0(%esi,1),%esi |
| 1680 | |
| 1681 | tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2); |
| 1682 | tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 9); |
| 1683 | |
| 1684 | // FIXME: Does this test really always pass? |
| 1685 | tls::check_tls(relinfo, relnum, rel.get_r_offset(), |
| 1686 | view[-2] == 0x8d && view[-1] == 0x83); |
| 1687 | |
| 1688 | tls::check_tls(relinfo, relnum, rel.get_r_offset(), view[4] == 0xe8); |
| 1689 | |
| 1690 | memcpy(view - 2, "\x65\xa1\0\0\0\0\x90\x8d\x74\x26\0", 11); |
| 1691 | |
| 1692 | // The next reloc should be a PLT32 reloc against __tls_get_addr. |
| 1693 | // We can skip it. |
| 1694 | this->skip_call_tls_get_addr_ = true; |
| 1695 | } |
| 1696 | |
| 1697 | // Do a relocation in which we convert a TLS Initial-Exec to a |
| 1698 | // Local-Exec. |
| 1699 | |
| 1700 | inline void |
| 1701 | Target_i386::Relocate::tls_ie_to_le(const Relocate_info<32, false>* relinfo, |
| 1702 | size_t relnum, |
| 1703 | Output_segment* tls_segment, |
| 1704 | const elfcpp::Rel<32, false>& rel, |
| 1705 | unsigned int r_type, |
| 1706 | elfcpp::Elf_types<32>::Elf_Addr value, |
| 1707 | unsigned char* view, |
| 1708 | off_t view_size) |
| 1709 | { |
| 1710 | // We have to actually change the instructions, which means that we |
| 1711 | // need to examine the opcodes to figure out which instruction we |
| 1712 | // are looking at. |
| 1713 | if (r_type == elfcpp::R_386_TLS_IE) |
| 1714 | { |
| 1715 | // movl %gs:XX,%eax ==> movl $YY,%eax |
| 1716 | // movl %gs:XX,%reg ==> movl $YY,%reg |
| 1717 | // addl %gs:XX,%reg ==> addl $YY,%reg |
| 1718 | tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -1); |
| 1719 | tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4); |
| 1720 | |
| 1721 | unsigned char op1 = view[-1]; |
| 1722 | if (op1 == 0xa1) |
| 1723 | { |
| 1724 | // movl XX,%eax ==> movl $YY,%eax |
| 1725 | view[-1] = 0xb8; |
| 1726 | } |
| 1727 | else |
| 1728 | { |
| 1729 | tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2); |
| 1730 | |
| 1731 | unsigned char op2 = view[-2]; |
| 1732 | if (op2 == 0x8b) |
| 1733 | { |
| 1734 | // movl XX,%reg ==> movl $YY,%reg |
| 1735 | tls::check_tls(relinfo, relnum, rel.get_r_offset(), |
| 1736 | (op1 & 0xc7) == 0x05); |
| 1737 | view[-2] = 0xc7; |
| 1738 | view[-1] = 0xc0 | ((op1 >> 3) & 7); |
| 1739 | } |
| 1740 | else if (op2 == 0x03) |
| 1741 | { |
| 1742 | // addl XX,%reg ==> addl $YY,%reg |
| 1743 | tls::check_tls(relinfo, relnum, rel.get_r_offset(), |
| 1744 | (op1 & 0xc7) == 0x05); |
| 1745 | view[-2] = 0x81; |
| 1746 | view[-1] = 0xc0 | ((op1 >> 3) & 7); |
| 1747 | } |
| 1748 | else |
| 1749 | tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0); |
| 1750 | } |
| 1751 | } |
| 1752 | else |
| 1753 | { |
| 1754 | // subl %gs:XX(%reg1),%reg2 ==> subl $YY,%reg2 |
| 1755 | // movl %gs:XX(%reg1),%reg2 ==> movl $YY,%reg2 |
| 1756 | // addl %gs:XX(%reg1),%reg2 ==> addl $YY,$reg2 |
| 1757 | tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, -2); |
| 1758 | tls::check_range(relinfo, relnum, rel.get_r_offset(), view_size, 4); |
| 1759 | |
| 1760 | unsigned char op1 = view[-1]; |
| 1761 | unsigned char op2 = view[-2]; |
| 1762 | tls::check_tls(relinfo, relnum, rel.get_r_offset(), |
| 1763 | (op1 & 0xc0) == 0x80 && (op1 & 7) != 4); |
| 1764 | if (op2 == 0x8b) |
| 1765 | { |
| 1766 | // movl %gs:XX(%reg1),%reg2 ==> movl $YY,%reg2 |
| 1767 | view[-2] = 0xc7; |
| 1768 | view[-1] = 0xc0 | ((op1 >> 3) & 7); |
| 1769 | } |
| 1770 | else if (op2 == 0x2b) |
| 1771 | { |
| 1772 | // subl %gs:XX(%reg1),%reg2 ==> subl $YY,%reg2 |
| 1773 | view[-2] = 0x81; |
| 1774 | view[-1] = 0xe8 | ((op1 >> 3) & 7); |
| 1775 | } |
| 1776 | else if (op2 == 0x03) |
| 1777 | { |
| 1778 | // addl %gs:XX(%reg1),%reg2 ==> addl $YY,$reg2 |
| 1779 | view[-2] = 0x81; |
| 1780 | view[-1] = 0xc0 | ((op1 >> 3) & 7); |
| 1781 | } |
| 1782 | else |
| 1783 | tls::check_tls(relinfo, relnum, rel.get_r_offset(), 0); |
| 1784 | } |
| 1785 | |
| 1786 | value = tls_segment->vaddr() + tls_segment->memsz() - value; |
| 1787 | if (r_type == elfcpp::R_386_TLS_IE || r_type == elfcpp::R_386_TLS_GOTIE) |
| 1788 | value = - value; |
| 1789 | |
| 1790 | Relocate_functions<32, false>::rel32(view, value); |
| 1791 | } |
| 1792 | |
| 1793 | // Relocate section data. |
| 1794 | |
| 1795 | void |
| 1796 | Target_i386::relocate_section(const Relocate_info<32, false>* relinfo, |
| 1797 | unsigned int sh_type, |
| 1798 | const unsigned char* prelocs, |
| 1799 | size_t reloc_count, |
| 1800 | Output_section* output_section, |
| 1801 | bool needs_special_offset_handling, |
| 1802 | unsigned char* view, |
| 1803 | elfcpp::Elf_types<32>::Elf_Addr address, |
| 1804 | off_t view_size) |
| 1805 | { |
| 1806 | gold_assert(sh_type == elfcpp::SHT_REL); |
| 1807 | |
| 1808 | gold::relocate_section<32, false, Target_i386, elfcpp::SHT_REL, |
| 1809 | Target_i386::Relocate>( |
| 1810 | relinfo, |
| 1811 | this, |
| 1812 | prelocs, |
| 1813 | reloc_count, |
| 1814 | output_section, |
| 1815 | needs_special_offset_handling, |
| 1816 | view, |
| 1817 | address, |
| 1818 | view_size); |
| 1819 | } |
| 1820 | |
| 1821 | // Return the value to use for a dynamic which requires special |
| 1822 | // treatment. This is how we support equality comparisons of function |
| 1823 | // pointers across shared library boundaries, as described in the |
| 1824 | // processor specific ABI supplement. |
| 1825 | |
| 1826 | uint64_t |
| 1827 | Target_i386::do_dynsym_value(const Symbol* gsym) const |
| 1828 | { |
| 1829 | gold_assert(gsym->is_from_dynobj() && gsym->has_plt_offset()); |
| 1830 | return this->plt_section()->address() + gsym->plt_offset(); |
| 1831 | } |
| 1832 | |
| 1833 | // Return a string used to fill a code section with nops to take up |
| 1834 | // the specified length. |
| 1835 | |
| 1836 | std::string |
| 1837 | Target_i386::do_code_fill(off_t length) |
| 1838 | { |
| 1839 | if (length >= 16) |
| 1840 | { |
| 1841 | // Build a jmp instruction to skip over the bytes. |
| 1842 | unsigned char jmp[5]; |
| 1843 | jmp[0] = 0xe9; |
| 1844 | elfcpp::Swap_unaligned<32, false>::writeval(jmp + 1, length - 5); |
| 1845 | return (std::string(reinterpret_cast<char*>(&jmp[0]), 5) |
| 1846 | + std::string(length - 5, '\0')); |
| 1847 | } |
| 1848 | |
| 1849 | // Nop sequences of various lengths. |
| 1850 | const char nop1[1] = { 0x90 }; // nop |
| 1851 | const char nop2[2] = { 0x66, 0x90 }; // xchg %ax %ax |
| 1852 | const char nop3[3] = { 0x8d, 0x76, 0x00 }; // leal 0(%esi),%esi |
| 1853 | const char nop4[4] = { 0x8d, 0x74, 0x26, 0x00}; // leal 0(%esi,1),%esi |
| 1854 | const char nop5[5] = { 0x90, 0x8d, 0x74, 0x26, // nop |
| 1855 | 0x00 }; // leal 0(%esi,1),%esi |
| 1856 | const char nop6[6] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi |
| 1857 | 0x00, 0x00 }; |
| 1858 | const char nop7[7] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi |
| 1859 | 0x00, 0x00, 0x00 }; |
| 1860 | const char nop8[8] = { 0x90, 0x8d, 0xb4, 0x26, // nop |
| 1861 | 0x00, 0x00, 0x00, 0x00 }; // leal 0L(%esi,1),%esi |
| 1862 | const char nop9[9] = { 0x89, 0xf6, 0x8d, 0xbc, // movl %esi,%esi |
| 1863 | 0x27, 0x00, 0x00, 0x00, // leal 0L(%edi,1),%edi |
| 1864 | 0x00 }; |
| 1865 | const char nop10[10] = { 0x8d, 0x76, 0x00, 0x8d, // leal 0(%esi),%esi |
| 1866 | 0xbc, 0x27, 0x00, 0x00, // leal 0L(%edi,1),%edi |
| 1867 | 0x00, 0x00 }; |
| 1868 | const char nop11[11] = { 0x8d, 0x74, 0x26, 0x00, // leal 0(%esi,1),%esi |
| 1869 | 0x8d, 0xbc, 0x27, 0x00, // leal 0L(%edi,1),%edi |
| 1870 | 0x00, 0x00, 0x00 }; |
| 1871 | const char nop12[12] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi |
| 1872 | 0x00, 0x00, 0x8d, 0xbf, // leal 0L(%edi),%edi |
| 1873 | 0x00, 0x00, 0x00, 0x00 }; |
| 1874 | const char nop13[13] = { 0x8d, 0xb6, 0x00, 0x00, // leal 0L(%esi),%esi |
| 1875 | 0x00, 0x00, 0x8d, 0xbc, // leal 0L(%edi,1),%edi |
| 1876 | 0x27, 0x00, 0x00, 0x00, |
| 1877 | 0x00 }; |
| 1878 | const char nop14[14] = { 0x8d, 0xb4, 0x26, 0x00, // leal 0L(%esi,1),%esi |
| 1879 | 0x00, 0x00, 0x00, 0x8d, // leal 0L(%edi,1),%edi |
| 1880 | 0xbc, 0x27, 0x00, 0x00, |
| 1881 | 0x00, 0x00 }; |
| 1882 | const char nop15[15] = { 0xeb, 0x0d, 0x90, 0x90, // jmp .+15 |
| 1883 | 0x90, 0x90, 0x90, 0x90, // nop,nop,nop,... |
| 1884 | 0x90, 0x90, 0x90, 0x90, |
| 1885 | 0x90, 0x90, 0x90 }; |
| 1886 | |
| 1887 | const char* nops[16] = { |
| 1888 | NULL, |
| 1889 | nop1, nop2, nop3, nop4, nop5, nop6, nop7, |
| 1890 | nop8, nop9, nop10, nop11, nop12, nop13, nop14, nop15 |
| 1891 | }; |
| 1892 | |
| 1893 | return std::string(nops[length], length); |
| 1894 | } |
| 1895 | |
| 1896 | // The selector for i386 object files. |
| 1897 | |
| 1898 | class Target_selector_i386 : public Target_selector |
| 1899 | { |
| 1900 | public: |
| 1901 | Target_selector_i386() |
| 1902 | : Target_selector(elfcpp::EM_386, 32, false) |
| 1903 | { } |
| 1904 | |
| 1905 | Target* |
| 1906 | recognize(int machine, int osabi, int abiversion); |
| 1907 | |
| 1908 | private: |
| 1909 | Target_i386* target_; |
| 1910 | }; |
| 1911 | |
| 1912 | // Recognize an i386 object file when we already know that the machine |
| 1913 | // number is EM_386. |
| 1914 | |
| 1915 | Target* |
| 1916 | Target_selector_i386::recognize(int, int, int) |
| 1917 | { |
| 1918 | if (this->target_ == NULL) |
| 1919 | this->target_ = new Target_i386(); |
| 1920 | return this->target_; |
| 1921 | } |
| 1922 | |
| 1923 | Target_selector_i386 target_selector_i386; |
| 1924 | |
| 1925 | } // End anonymous namespace. |