1 //===- ELF.cpp - ELF object file implementation ---------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include "llvm/Object/ELF.h" 10 #include "llvm/BinaryFormat/ELF.h" 11 #include "llvm/Support/LEB128.h" 12 13 using namespace llvm; 14 using namespace object; 15 16 #define STRINGIFY_ENUM_CASE(ns, name) \ 17 case ns::name: \ 18 return #name; 19 20 #define ELF_RELOC(name, value) STRINGIFY_ENUM_CASE(ELF, name) 21 22 StringRef llvm::object::getELFRelocationTypeName(uint32_t Machine, 23 uint32_t Type) { 24 switch (Machine) { 25 case ELF::EM_X86_64: 26 switch (Type) { 27 #include "llvm/BinaryFormat/ELFRelocs/x86_64.def" 28 default: 29 break; 30 } 31 break; 32 case ELF::EM_386: 33 case ELF::EM_IAMCU: 34 switch (Type) { 35 #include "llvm/BinaryFormat/ELFRelocs/i386.def" 36 default: 37 break; 38 } 39 break; 40 case ELF::EM_MIPS: 41 switch (Type) { 42 #include "llvm/BinaryFormat/ELFRelocs/Mips.def" 43 default: 44 break; 45 } 46 break; 47 case ELF::EM_AARCH64: 48 switch (Type) { 49 #include "llvm/BinaryFormat/ELFRelocs/AArch64.def" 50 default: 51 break; 52 } 53 break; 54 case ELF::EM_ARM: 55 switch (Type) { 56 #include "llvm/BinaryFormat/ELFRelocs/ARM.def" 57 default: 58 break; 59 } 60 break; 61 case ELF::EM_ARC_COMPACT: 62 case ELF::EM_ARC_COMPACT2: 63 switch (Type) { 64 #include "llvm/BinaryFormat/ELFRelocs/ARC.def" 65 default: 66 break; 67 } 68 break; 69 case ELF::EM_AVR: 70 switch (Type) { 71 #include "llvm/BinaryFormat/ELFRelocs/AVR.def" 72 default: 73 break; 74 } 75 break; 76 case ELF::EM_HEXAGON: 77 switch (Type) { 78 #include "llvm/BinaryFormat/ELFRelocs/Hexagon.def" 79 default: 80 break; 81 } 82 break; 83 case ELF::EM_LANAI: 84 switch (Type) { 85 #include "llvm/BinaryFormat/ELFRelocs/Lanai.def" 86 default: 87 break; 88 } 89 break; 90 case ELF::EM_PPC: 91 switch (Type) { 92 #include "llvm/BinaryFormat/ELFRelocs/PowerPC.def" 93 default: 94 break; 95 } 96 break; 97 case ELF::EM_PPC64: 98 switch (Type) { 99 #include "llvm/BinaryFormat/ELFRelocs/PowerPC64.def" 100 default: 101 break; 102 } 103 break; 104 case ELF::EM_RISCV: 105 switch (Type) { 106 #include "llvm/BinaryFormat/ELFRelocs/RISCV.def" 107 default: 108 break; 109 } 110 break; 111 case ELF::EM_S390: 112 switch (Type) { 113 #include "llvm/BinaryFormat/ELFRelocs/SystemZ.def" 114 default: 115 break; 116 } 117 break; 118 case ELF::EM_SPARC: 119 case ELF::EM_SPARC32PLUS: 120 case ELF::EM_SPARCV9: 121 switch (Type) { 122 #include "llvm/BinaryFormat/ELFRelocs/Sparc.def" 123 default: 124 break; 125 } 126 break; 127 case ELF::EM_AMDGPU: 128 switch (Type) { 129 #include "llvm/BinaryFormat/ELFRelocs/AMDGPU.def" 130 default: 131 break; 132 } 133 break; 134 case ELF::EM_BPF: 135 switch (Type) { 136 #include "llvm/BinaryFormat/ELFRelocs/BPF.def" 137 default: 138 break; 139 } 140 break; 141 case ELF::EM_MSP430: 142 switch (Type) { 143 #include "llvm/BinaryFormat/ELFRelocs/MSP430.def" 144 default: 145 break; 146 } 147 break; 148 case ELF::EM_VE: 149 switch (Type) { 150 #include "llvm/BinaryFormat/ELFRelocs/VE.def" 151 default: 152 break; 153 } 154 break; 155 default: 156 break; 157 } 158 return "Unknown"; 159 } 160 161 #undef ELF_RELOC 162 163 uint32_t llvm::object::getELFRelativeRelocationType(uint32_t Machine) { 164 switch (Machine) { 165 case ELF::EM_X86_64: 166 return ELF::R_X86_64_RELATIVE; 167 case ELF::EM_386: 168 case ELF::EM_IAMCU: 169 return ELF::R_386_RELATIVE; 170 case ELF::EM_MIPS: 171 break; 172 case ELF::EM_AARCH64: 173 return ELF::R_AARCH64_RELATIVE; 174 case ELF::EM_ARM: 175 return ELF::R_ARM_RELATIVE; 176 case ELF::EM_ARC_COMPACT: 177 case ELF::EM_ARC_COMPACT2: 178 return ELF::R_ARC_RELATIVE; 179 case ELF::EM_AVR: 180 break; 181 case ELF::EM_HEXAGON: 182 return ELF::R_HEX_RELATIVE; 183 case ELF::EM_LANAI: 184 break; 185 case ELF::EM_PPC: 186 break; 187 case ELF::EM_PPC64: 188 return ELF::R_PPC64_RELATIVE; 189 case ELF::EM_RISCV: 190 return ELF::R_RISCV_RELATIVE; 191 case ELF::EM_S390: 192 return ELF::R_390_RELATIVE; 193 case ELF::EM_SPARC: 194 case ELF::EM_SPARC32PLUS: 195 case ELF::EM_SPARCV9: 196 return ELF::R_SPARC_RELATIVE; 197 case ELF::EM_AMDGPU: 198 break; 199 case ELF::EM_BPF: 200 break; 201 default: 202 break; 203 } 204 return 0; 205 } 206 207 StringRef llvm::object::getELFSectionTypeName(uint32_t Machine, unsigned Type) { 208 switch (Machine) { 209 case ELF::EM_ARM: 210 switch (Type) { 211 STRINGIFY_ENUM_CASE(ELF, SHT_ARM_EXIDX); 212 STRINGIFY_ENUM_CASE(ELF, SHT_ARM_PREEMPTMAP); 213 STRINGIFY_ENUM_CASE(ELF, SHT_ARM_ATTRIBUTES); 214 STRINGIFY_ENUM_CASE(ELF, SHT_ARM_DEBUGOVERLAY); 215 STRINGIFY_ENUM_CASE(ELF, SHT_ARM_OVERLAYSECTION); 216 } 217 break; 218 case ELF::EM_HEXAGON: 219 switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_HEX_ORDERED); } 220 break; 221 case ELF::EM_X86_64: 222 switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_X86_64_UNWIND); } 223 break; 224 case ELF::EM_MIPS: 225 case ELF::EM_MIPS_RS3_LE: 226 switch (Type) { 227 STRINGIFY_ENUM_CASE(ELF, SHT_MIPS_REGINFO); 228 STRINGIFY_ENUM_CASE(ELF, SHT_MIPS_OPTIONS); 229 STRINGIFY_ENUM_CASE(ELF, SHT_MIPS_DWARF); 230 STRINGIFY_ENUM_CASE(ELF, SHT_MIPS_ABIFLAGS); 231 } 232 break; 233 case ELF::EM_RISCV: 234 switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_RISCV_ATTRIBUTES); } 235 break; 236 default: 237 break; 238 } 239 240 switch (Type) { 241 STRINGIFY_ENUM_CASE(ELF, SHT_NULL); 242 STRINGIFY_ENUM_CASE(ELF, SHT_PROGBITS); 243 STRINGIFY_ENUM_CASE(ELF, SHT_SYMTAB); 244 STRINGIFY_ENUM_CASE(ELF, SHT_STRTAB); 245 STRINGIFY_ENUM_CASE(ELF, SHT_RELA); 246 STRINGIFY_ENUM_CASE(ELF, SHT_HASH); 247 STRINGIFY_ENUM_CASE(ELF, SHT_DYNAMIC); 248 STRINGIFY_ENUM_CASE(ELF, SHT_NOTE); 249 STRINGIFY_ENUM_CASE(ELF, SHT_NOBITS); 250 STRINGIFY_ENUM_CASE(ELF, SHT_REL); 251 STRINGIFY_ENUM_CASE(ELF, SHT_SHLIB); 252 STRINGIFY_ENUM_CASE(ELF, SHT_DYNSYM); 253 STRINGIFY_ENUM_CASE(ELF, SHT_INIT_ARRAY); 254 STRINGIFY_ENUM_CASE(ELF, SHT_FINI_ARRAY); 255 STRINGIFY_ENUM_CASE(ELF, SHT_PREINIT_ARRAY); 256 STRINGIFY_ENUM_CASE(ELF, SHT_GROUP); 257 STRINGIFY_ENUM_CASE(ELF, SHT_SYMTAB_SHNDX); 258 STRINGIFY_ENUM_CASE(ELF, SHT_RELR); 259 STRINGIFY_ENUM_CASE(ELF, SHT_ANDROID_REL); 260 STRINGIFY_ENUM_CASE(ELF, SHT_ANDROID_RELA); 261 STRINGIFY_ENUM_CASE(ELF, SHT_ANDROID_RELR); 262 STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_ODRTAB); 263 STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_LINKER_OPTIONS); 264 STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_CALL_GRAPH_PROFILE); 265 STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_ADDRSIG); 266 STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_DEPENDENT_LIBRARIES); 267 STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_SYMPART); 268 STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_PART_EHDR); 269 STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_PART_PHDR); 270 STRINGIFY_ENUM_CASE(ELF, SHT_GNU_ATTRIBUTES); 271 STRINGIFY_ENUM_CASE(ELF, SHT_GNU_HASH); 272 STRINGIFY_ENUM_CASE(ELF, SHT_GNU_verdef); 273 STRINGIFY_ENUM_CASE(ELF, SHT_GNU_verneed); 274 STRINGIFY_ENUM_CASE(ELF, SHT_GNU_versym); 275 default: 276 return "Unknown"; 277 } 278 } 279 280 template <class ELFT> 281 Expected<std::vector<typename ELFT::Rela>> 282 ELFFile<ELFT>::decode_relrs(Elf_Relr_Range relrs) const { 283 // This function decodes the contents of an SHT_RELR packed relocation 284 // section. 285 // 286 // Proposal for adding SHT_RELR sections to generic-abi is here: 287 // https://groups.google.com/forum/#!topic/generic-abi/bX460iggiKg 288 // 289 // The encoded sequence of Elf64_Relr entries in a SHT_RELR section looks 290 // like [ AAAAAAAA BBBBBBB1 BBBBBBB1 ... AAAAAAAA BBBBBB1 ... ] 291 // 292 // i.e. start with an address, followed by any number of bitmaps. The address 293 // entry encodes 1 relocation. The subsequent bitmap entries encode up to 63 294 // relocations each, at subsequent offsets following the last address entry. 295 // 296 // The bitmap entries must have 1 in the least significant bit. The assumption 297 // here is that an address cannot have 1 in lsb. Odd addresses are not 298 // supported. 299 // 300 // Excluding the least significant bit in the bitmap, each non-zero bit in 301 // the bitmap represents a relocation to be applied to a corresponding machine 302 // word that follows the base address word. The second least significant bit 303 // represents the machine word immediately following the initial address, and 304 // each bit that follows represents the next word, in linear order. As such, 305 // a single bitmap can encode up to 31 relocations in a 32-bit object, and 306 // 63 relocations in a 64-bit object. 307 // 308 // This encoding has a couple of interesting properties: 309 // 1. Looking at any entry, it is clear whether it's an address or a bitmap: 310 // even means address, odd means bitmap. 311 // 2. Just a simple list of addresses is a valid encoding. 312 313 Elf_Rela Rela; 314 Rela.r_info = 0; 315 Rela.r_addend = 0; 316 Rela.setType(getRelativeRelocationType(), false); 317 std::vector<Elf_Rela> Relocs; 318 319 // Word type: uint32_t for Elf32, and uint64_t for Elf64. 320 typedef typename ELFT::uint Word; 321 322 // Word size in number of bytes. 323 const size_t WordSize = sizeof(Word); 324 325 // Number of bits used for the relocation offsets bitmap. 326 // These many relative relocations can be encoded in a single entry. 327 const size_t NBits = 8*WordSize - 1; 328 329 Word Base = 0; 330 for (const Elf_Relr &R : relrs) { 331 Word Entry = R; 332 if ((Entry&1) == 0) { 333 // Even entry: encodes the offset for next relocation. 334 Rela.r_offset = Entry; 335 Relocs.push_back(Rela); 336 // Set base offset for subsequent bitmap entries. 337 Base = Entry + WordSize; 338 continue; 339 } 340 341 // Odd entry: encodes bitmap for relocations starting at base. 342 Word Offset = Base; 343 while (Entry != 0) { 344 Entry >>= 1; 345 if ((Entry&1) != 0) { 346 Rela.r_offset = Offset; 347 Relocs.push_back(Rela); 348 } 349 Offset += WordSize; 350 } 351 352 // Advance base offset by NBits words. 353 Base += NBits * WordSize; 354 } 355 356 return Relocs; 357 } 358 359 template <class ELFT> 360 Expected<std::vector<typename ELFT::Rela>> 361 ELFFile<ELFT>::android_relas(const Elf_Shdr *Sec) const { 362 // This function reads relocations in Android's packed relocation format, 363 // which is based on SLEB128 and delta encoding. 364 Expected<ArrayRef<uint8_t>> ContentsOrErr = getSectionContents(Sec); 365 if (!ContentsOrErr) 366 return ContentsOrErr.takeError(); 367 const uint8_t *Cur = ContentsOrErr->begin(); 368 const uint8_t *End = ContentsOrErr->end(); 369 if (ContentsOrErr->size() < 4 || Cur[0] != 'A' || Cur[1] != 'P' || 370 Cur[2] != 'S' || Cur[3] != '2') 371 return createError("invalid packed relocation header"); 372 Cur += 4; 373 374 const char *ErrStr = nullptr; 375 auto ReadSLEB = [&]() -> int64_t { 376 if (ErrStr) 377 return 0; 378 unsigned Len; 379 int64_t Result = decodeSLEB128(Cur, &Len, End, &ErrStr); 380 Cur += Len; 381 return Result; 382 }; 383 384 uint64_t NumRelocs = ReadSLEB(); 385 uint64_t Offset = ReadSLEB(); 386 uint64_t Addend = 0; 387 388 if (ErrStr) 389 return createError(ErrStr); 390 391 std::vector<Elf_Rela> Relocs; 392 Relocs.reserve(NumRelocs); 393 while (NumRelocs) { 394 uint64_t NumRelocsInGroup = ReadSLEB(); 395 if (NumRelocsInGroup > NumRelocs) 396 return createError("relocation group unexpectedly large"); 397 NumRelocs -= NumRelocsInGroup; 398 399 uint64_t GroupFlags = ReadSLEB(); 400 bool GroupedByInfo = GroupFlags & ELF::RELOCATION_GROUPED_BY_INFO_FLAG; 401 bool GroupedByOffsetDelta = GroupFlags & ELF::RELOCATION_GROUPED_BY_OFFSET_DELTA_FLAG; 402 bool GroupedByAddend = GroupFlags & ELF::RELOCATION_GROUPED_BY_ADDEND_FLAG; 403 bool GroupHasAddend = GroupFlags & ELF::RELOCATION_GROUP_HAS_ADDEND_FLAG; 404 405 uint64_t GroupOffsetDelta; 406 if (GroupedByOffsetDelta) 407 GroupOffsetDelta = ReadSLEB(); 408 409 uint64_t GroupRInfo; 410 if (GroupedByInfo) 411 GroupRInfo = ReadSLEB(); 412 413 if (GroupedByAddend && GroupHasAddend) 414 Addend += ReadSLEB(); 415 416 if (!GroupHasAddend) 417 Addend = 0; 418 419 for (uint64_t I = 0; I != NumRelocsInGroup; ++I) { 420 Elf_Rela R; 421 Offset += GroupedByOffsetDelta ? GroupOffsetDelta : ReadSLEB(); 422 R.r_offset = Offset; 423 R.r_info = GroupedByInfo ? GroupRInfo : ReadSLEB(); 424 if (GroupHasAddend && !GroupedByAddend) 425 Addend += ReadSLEB(); 426 R.r_addend = Addend; 427 Relocs.push_back(R); 428 429 if (ErrStr) 430 return createError(ErrStr); 431 } 432 433 if (ErrStr) 434 return createError(ErrStr); 435 } 436 437 return Relocs; 438 } 439 440 template <class ELFT> 441 std::string ELFFile<ELFT>::getDynamicTagAsString(unsigned Arch, 442 uint64_t Type) const { 443 #define DYNAMIC_STRINGIFY_ENUM(tag, value) \ 444 case value: \ 445 return #tag; 446 447 #define DYNAMIC_TAG(n, v) 448 switch (Arch) { 449 case ELF::EM_AARCH64: 450 switch (Type) { 451 #define AARCH64_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value) 452 #include "llvm/BinaryFormat/DynamicTags.def" 453 #undef AARCH64_DYNAMIC_TAG 454 } 455 break; 456 457 case ELF::EM_HEXAGON: 458 switch (Type) { 459 #define HEXAGON_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value) 460 #include "llvm/BinaryFormat/DynamicTags.def" 461 #undef HEXAGON_DYNAMIC_TAG 462 } 463 break; 464 465 case ELF::EM_MIPS: 466 switch (Type) { 467 #define MIPS_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value) 468 #include "llvm/BinaryFormat/DynamicTags.def" 469 #undef MIPS_DYNAMIC_TAG 470 } 471 break; 472 473 case ELF::EM_PPC64: 474 switch (Type) { 475 #define PPC64_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value) 476 #include "llvm/BinaryFormat/DynamicTags.def" 477 #undef PPC64_DYNAMIC_TAG 478 } 479 break; 480 } 481 #undef DYNAMIC_TAG 482 switch (Type) { 483 // Now handle all dynamic tags except the architecture specific ones 484 #define AARCH64_DYNAMIC_TAG(name, value) 485 #define MIPS_DYNAMIC_TAG(name, value) 486 #define HEXAGON_DYNAMIC_TAG(name, value) 487 #define PPC64_DYNAMIC_TAG(name, value) 488 // Also ignore marker tags such as DT_HIOS (maps to DT_VERNEEDNUM), etc. 489 #define DYNAMIC_TAG_MARKER(name, value) 490 #define DYNAMIC_TAG(name, value) case value: return #name; 491 #include "llvm/BinaryFormat/DynamicTags.def" 492 #undef DYNAMIC_TAG 493 #undef AARCH64_DYNAMIC_TAG 494 #undef MIPS_DYNAMIC_TAG 495 #undef HEXAGON_DYNAMIC_TAG 496 #undef PPC64_DYNAMIC_TAG 497 #undef DYNAMIC_TAG_MARKER 498 #undef DYNAMIC_STRINGIFY_ENUM 499 default: 500 return "<unknown:>0x" + utohexstr(Type, true); 501 } 502 } 503 504 template <class ELFT> 505 std::string ELFFile<ELFT>::getDynamicTagAsString(uint64_t Type) const { 506 return getDynamicTagAsString(getHeader()->e_machine, Type); 507 } 508 509 template <class ELFT> 510 Expected<typename ELFT::DynRange> ELFFile<ELFT>::dynamicEntries() const { 511 ArrayRef<Elf_Dyn> Dyn; 512 513 auto ProgramHeadersOrError = program_headers(); 514 if (!ProgramHeadersOrError) 515 return ProgramHeadersOrError.takeError(); 516 517 for (const Elf_Phdr &Phdr : *ProgramHeadersOrError) { 518 if (Phdr.p_type == ELF::PT_DYNAMIC) { 519 Dyn = makeArrayRef( 520 reinterpret_cast<const Elf_Dyn *>(base() + Phdr.p_offset), 521 Phdr.p_filesz / sizeof(Elf_Dyn)); 522 break; 523 } 524 } 525 526 // If we can't find the dynamic section in the program headers, we just fall 527 // back on the sections. 528 if (Dyn.empty()) { 529 auto SectionsOrError = sections(); 530 if (!SectionsOrError) 531 return SectionsOrError.takeError(); 532 533 for (const Elf_Shdr &Sec : *SectionsOrError) { 534 if (Sec.sh_type == ELF::SHT_DYNAMIC) { 535 Expected<ArrayRef<Elf_Dyn>> DynOrError = 536 getSectionContentsAsArray<Elf_Dyn>(&Sec); 537 if (!DynOrError) 538 return DynOrError.takeError(); 539 Dyn = *DynOrError; 540 break; 541 } 542 } 543 544 if (!Dyn.data()) 545 return ArrayRef<Elf_Dyn>(); 546 } 547 548 if (Dyn.empty()) 549 // TODO: this error is untested. 550 return createError("invalid empty dynamic section"); 551 552 if (Dyn.back().d_tag != ELF::DT_NULL) 553 // TODO: this error is untested. 554 return createError("dynamic sections must be DT_NULL terminated"); 555 556 return Dyn; 557 } 558 559 template <class ELFT> 560 Expected<const uint8_t *> ELFFile<ELFT>::toMappedAddr(uint64_t VAddr) const { 561 auto ProgramHeadersOrError = program_headers(); 562 if (!ProgramHeadersOrError) 563 return ProgramHeadersOrError.takeError(); 564 565 llvm::SmallVector<Elf_Phdr *, 4> LoadSegments; 566 567 for (const Elf_Phdr &Phdr : *ProgramHeadersOrError) 568 if (Phdr.p_type == ELF::PT_LOAD) 569 LoadSegments.push_back(const_cast<Elf_Phdr *>(&Phdr)); 570 571 const Elf_Phdr *const *I = 572 std::upper_bound(LoadSegments.begin(), LoadSegments.end(), VAddr, 573 [](uint64_t VAddr, const Elf_Phdr_Impl<ELFT> *Phdr) { 574 return VAddr < Phdr->p_vaddr; 575 }); 576 577 if (I == LoadSegments.begin()) 578 return createError("virtual address is not in any segment: 0x" + 579 Twine::utohexstr(VAddr)); 580 --I; 581 const Elf_Phdr &Phdr = **I; 582 uint64_t Delta = VAddr - Phdr.p_vaddr; 583 if (Delta >= Phdr.p_filesz) 584 return createError("virtual address is not in any segment: 0x" + 585 Twine::utohexstr(VAddr)); 586 587 uint64_t Offset = Phdr.p_offset + Delta; 588 if (Offset >= getBufSize()) 589 return createError("can't map virtual address 0x" + 590 Twine::utohexstr(VAddr) + " to the segment with index " + 591 Twine(&Phdr - (*ProgramHeadersOrError).data() + 1) + 592 ": the segment ends at 0x" + 593 Twine::utohexstr(Phdr.p_offset + Phdr.p_filesz) + 594 ", which is greater than the file size (0x" + 595 Twine::utohexstr(getBufSize()) + ")"); 596 597 return base() + Offset; 598 } 599 600 template class llvm::object::ELFFile<ELF32LE>; 601 template class llvm::object::ELFFile<ELF32BE>; 602 template class llvm::object::ELFFile<ELF64LE>; 603 template class llvm::object::ELFFile<ELF64BE>; 604