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