llvm/lib/Object/ELF.cpp

   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/ADT/StringExtras.h"
  11 #include "llvm/BinaryFormat/ELF.h"
  12 #include "llvm/Support/DataExtractor.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_68K:
  27     switch (Type) {
  28 #include "llvm/BinaryFormat/ELFRelocs/M68k.def"
  29     default:
  30       break;
  31     }
  32     break;
  33   case ELF::EM_X86_64:
  34     switch (Type) {
  35 #include "llvm/BinaryFormat/ELFRelocs/x86_64.def"
  36     default:
  37       break;
  38     }
  39     break;
  40   case ELF::EM_386:
  41   case ELF::EM_IAMCU:
  42     switch (Type) {
  43 #include "llvm/BinaryFormat/ELFRelocs/i386.def"
  44     default:
  45       break;
  46     }
  47     break;
  48   case ELF::EM_MIPS:
  49     switch (Type) {
  50 #include "llvm/BinaryFormat/ELFRelocs/Mips.def"
  51     default:
  52       break;
  53     }
  54     break;
  55   case ELF::EM_AARCH64:
  56     switch (Type) {
  57 #include "llvm/BinaryFormat/ELFRelocs/AArch64.def"
  58     default:
  59       break;
  60     }
  61     break;
  62   case ELF::EM_ARM:
  63     switch (Type) {
  64 #include "llvm/BinaryFormat/ELFRelocs/ARM.def"
  65     default:
  66       break;
  67     }
  68     break;
  69   case ELF::EM_ARC_COMPACT:
  70   case ELF::EM_ARC_COMPACT2:
  71     switch (Type) {
  72 #include "llvm/BinaryFormat/ELFRelocs/ARC.def"
  73     default:
  74       break;
  75     }
  76     break;
  77   case ELF::EM_AVR:
  78     switch (Type) {
  79 #include "llvm/BinaryFormat/ELFRelocs/AVR.def"
  80     default:
  81       break;
  82     }
  83     break;
  84   case ELF::EM_HEXAGON:
  85     switch (Type) {
  86 #include "llvm/BinaryFormat/ELFRelocs/Hexagon.def"
  87     default:
  88       break;
  89     }
  90     break;
  91   case ELF::EM_LANAI:
  92     switch (Type) {
  93 #include "llvm/BinaryFormat/ELFRelocs/Lanai.def"
  94     default:
  95       break;
  96     }
  97     break;
  98   case ELF::EM_PPC:
  99     switch (Type) {
 100 #include "llvm/BinaryFormat/ELFRelocs/PowerPC.def"
 101     default:
 102       break;
 103     }
 104     break;
 105   case ELF::EM_PPC64:
 106     switch (Type) {
 107 #include "llvm/BinaryFormat/ELFRelocs/PowerPC64.def"
 108     default:
 109       break;
 110     }
 111     break;
 112   case ELF::EM_RISCV:
 113     switch (Type) {
 114 #include "llvm/BinaryFormat/ELFRelocs/RISCV.def"
 115     default:
 116       break;
 117     }
 118     break;
 119   case ELF::EM_S390:
 120     switch (Type) {
 121 #include "llvm/BinaryFormat/ELFRelocs/SystemZ.def"
 122     default:
 123       break;
 124     }
 125     break;
 126   case ELF::EM_SPARC:
 127   case ELF::EM_SPARC32PLUS:
 128   case ELF::EM_SPARCV9:
 129     switch (Type) {
 130 #include "llvm/BinaryFormat/ELFRelocs/Sparc.def"
 131     default:
 132       break;
 133     }
 134     break;
 135   case ELF::EM_AMDGPU:
 136     switch (Type) {
 137 #include "llvm/BinaryFormat/ELFRelocs/AMDGPU.def"
 138     default:
 139       break;
 140     }
 141     break;
 142   case ELF::EM_BPF:
 143     switch (Type) {
 144 #include "llvm/BinaryFormat/ELFRelocs/BPF.def"
 145     default:
 146       break;
 147     }
 148     break;
 149   case ELF::EM_MSP430:
 150     switch (Type) {
 151 #include "llvm/BinaryFormat/ELFRelocs/MSP430.def"
 152     default:
 153       break;
 154     }
 155     break;
 156   case ELF::EM_VE:
 157     switch (Type) {
 158 #include "llvm/BinaryFormat/ELFRelocs/VE.def"
 159     default:
 160       break;
 161     }
 162     break;
 163   case ELF::EM_CSKY:
 164     switch (Type) {
 165 #include "llvm/BinaryFormat/ELFRelocs/CSKY.def"
 166     default:
 167       break;
 168     }
 169     break;
 170   case ELF::EM_LOONGARCH:
 171     switch (Type) {
 172 #include "llvm/BinaryFormat/ELFRelocs/LoongArch.def"
 173     default:
 174       break;
 175     }
 176     break;
 177   case ELF::EM_XTENSA:
 178     switch (Type) {
 179 #include "llvm/BinaryFormat/ELFRelocs/Xtensa.def"
 180     default:
 181       break;
 182     }
 183     break;
 184   default:
 185     break;
 186   }
 187   return "Unknown";
 188 }
 189
 190 #undef ELF_RELOC
 191
 192 uint32_t llvm::object::getELFRelativeRelocationType(uint32_t Machine) {
 193   switch (Machine) {
 194   case ELF::EM_X86_64:
 195     return ELF::R_X86_64_RELATIVE;
 196   case ELF::EM_386:
 197   case ELF::EM_IAMCU:
 198     return ELF::R_386_RELATIVE;
 199   case ELF::EM_MIPS:
 200     break;
 201   case ELF::EM_AARCH64:
 202     return ELF::R_AARCH64_RELATIVE;
 203   case ELF::EM_ARM:
 204     return ELF::R_ARM_RELATIVE;
 205   case ELF::EM_ARC_COMPACT:
 206   case ELF::EM_ARC_COMPACT2:
 207     return ELF::R_ARC_RELATIVE;
 208   case ELF::EM_AVR:
 209     break;
 210   case ELF::EM_HEXAGON:
 211     return ELF::R_HEX_RELATIVE;
 212   case ELF::EM_LANAI:
 213     break;
 214   case ELF::EM_PPC:
 215     break;
 216   case ELF::EM_PPC64:
 217     return ELF::R_PPC64_RELATIVE;
 218   case ELF::EM_RISCV:
 219     return ELF::R_RISCV_RELATIVE;
 220   case ELF::EM_S390:
 221     return ELF::R_390_RELATIVE;
 222   case ELF::EM_SPARC:
 223   case ELF::EM_SPARC32PLUS:
 224   case ELF::EM_SPARCV9:
 225     return ELF::R_SPARC_RELATIVE;
 226   case ELF::EM_CSKY:
 227     return ELF::R_CKCORE_RELATIVE;
 228   case ELF::EM_VE:
 229     return ELF::R_VE_RELATIVE;
 230   case ELF::EM_AMDGPU:
 231     break;
 232   case ELF::EM_BPF:
 233     break;
 234   case ELF::EM_LOONGARCH:
 235     return ELF::R_LARCH_RELATIVE;
 236   default:
 237     break;
 238   }
 239   return 0;
 240 }
 241
 242 StringRef llvm::object::getELFSectionTypeName(uint32_t Machine, unsigned Type) {
 243   switch (Machine) {
 244   case ELF::EM_ARM:
 245     switch (Type) {
 246       STRINGIFY_ENUM_CASE(ELF, SHT_ARM_EXIDX);
 247       STRINGIFY_ENUM_CASE(ELF, SHT_ARM_PREEMPTMAP);
 248       STRINGIFY_ENUM_CASE(ELF, SHT_ARM_ATTRIBUTES);
 249       STRINGIFY_ENUM_CASE(ELF, SHT_ARM_DEBUGOVERLAY);
 250       STRINGIFY_ENUM_CASE(ELF, SHT_ARM_OVERLAYSECTION);
 251     }
 252     break;
 253   case ELF::EM_HEXAGON:
 254     switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_HEX_ORDERED); }
 255     break;
 256   case ELF::EM_X86_64:
 257     switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_X86_64_UNWIND); }
 258     break;
 259   case ELF::EM_MIPS:
 260   case ELF::EM_MIPS_RS3_LE:
 261     switch (Type) {
 262       STRINGIFY_ENUM_CASE(ELF, SHT_MIPS_REGINFO);
 263       STRINGIFY_ENUM_CASE(ELF, SHT_MIPS_OPTIONS);
 264       STRINGIFY_ENUM_CASE(ELF, SHT_MIPS_DWARF);
 265       STRINGIFY_ENUM_CASE(ELF, SHT_MIPS_ABIFLAGS);
 266     }
 267     break;
 268   case ELF::EM_MSP430:
 269     switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_MSP430_ATTRIBUTES); }
 270     break;
 271   case ELF::EM_RISCV:
 272     switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_RISCV_ATTRIBUTES); }
 273     break;
 274   case ELF::EM_AARCH64:
 275     switch (Type) {
 276       STRINGIFY_ENUM_CASE(ELF, SHT_AARCH64_MEMTAG_GLOBALS_DYNAMIC);
 277       STRINGIFY_ENUM_CASE(ELF, SHT_AARCH64_MEMTAG_GLOBALS_STATIC);
 278     }
 279   default:
 280     break;
 281   }
 282
 283   switch (Type) {
 284     STRINGIFY_ENUM_CASE(ELF, SHT_NULL);
 285     STRINGIFY_ENUM_CASE(ELF, SHT_PROGBITS);
 286     STRINGIFY_ENUM_CASE(ELF, SHT_SYMTAB);
 287     STRINGIFY_ENUM_CASE(ELF, SHT_STRTAB);
 288     STRINGIFY_ENUM_CASE(ELF, SHT_RELA);
 289     STRINGIFY_ENUM_CASE(ELF, SHT_HASH);
 290     STRINGIFY_ENUM_CASE(ELF, SHT_DYNAMIC);
 291     STRINGIFY_ENUM_CASE(ELF, SHT_NOTE);
 292     STRINGIFY_ENUM_CASE(ELF, SHT_NOBITS);
 293     STRINGIFY_ENUM_CASE(ELF, SHT_REL);
 294     STRINGIFY_ENUM_CASE(ELF, SHT_SHLIB);
 295     STRINGIFY_ENUM_CASE(ELF, SHT_DYNSYM);
 296     STRINGIFY_ENUM_CASE(ELF, SHT_INIT_ARRAY);
 297     STRINGIFY_ENUM_CASE(ELF, SHT_FINI_ARRAY);
 298     STRINGIFY_ENUM_CASE(ELF, SHT_PREINIT_ARRAY);
 299     STRINGIFY_ENUM_CASE(ELF, SHT_GROUP);
 300     STRINGIFY_ENUM_CASE(ELF, SHT_SYMTAB_SHNDX);
 301     STRINGIFY_ENUM_CASE(ELF, SHT_RELR);
 302     STRINGIFY_ENUM_CASE(ELF, SHT_ANDROID_REL);
 303     STRINGIFY_ENUM_CASE(ELF, SHT_ANDROID_RELA);
 304     STRINGIFY_ENUM_CASE(ELF, SHT_ANDROID_RELR);
 305     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_ODRTAB);
 306     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_LINKER_OPTIONS);
 307     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_CALL_GRAPH_PROFILE);
 308     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_ADDRSIG);
 309     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_DEPENDENT_LIBRARIES);
 310     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_SYMPART);
 311     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_PART_EHDR);
 312     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_PART_PHDR);
 313     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_BB_ADDR_MAP_V0);
 314     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_BB_ADDR_MAP);
 315     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_OFFLOADING);
 316     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_LTO);
 317     STRINGIFY_ENUM_CASE(ELF, SHT_GNU_ATTRIBUTES);
 318     STRINGIFY_ENUM_CASE(ELF, SHT_GNU_HASH);
 319     STRINGIFY_ENUM_CASE(ELF, SHT_GNU_verdef);
 320     STRINGIFY_ENUM_CASE(ELF, SHT_GNU_verneed);
 321     STRINGIFY_ENUM_CASE(ELF, SHT_GNU_versym);
 322   default:
 323     return "Unknown";
 324   }
 325 }
 326
 327 template <class ELFT>
 328 std::vector<typename ELFT::Rel>
 329 ELFFile<ELFT>::decode_relrs(Elf_Relr_Range relrs) const {
 330   // This function decodes the contents of an SHT_RELR packed relocation
 331   // section.
 332   //
 333   // Proposal for adding SHT_RELR sections to generic-abi is here:
 334   //   https://groups.google.com/forum/#!topic/generic-abi/bX460iggiKg
 335   //
 336   // The encoded sequence of Elf64_Relr entries in a SHT_RELR section looks
 337   // like [ AAAAAAAA BBBBBBB1 BBBBBBB1 ... AAAAAAAA BBBBBB1 ... ]
 338   //
 339   // i.e. start with an address, followed by any number of bitmaps. The address
 340   // entry encodes 1 relocation. The subsequent bitmap entries encode up to 63
 341   // relocations each, at subsequent offsets following the last address entry.
 342   //
 343   // The bitmap entries must have 1 in the least significant bit. The assumption
 344   // here is that an address cannot have 1 in lsb. Odd addresses are not
 345   // supported.
 346   //
 347   // Excluding the least significant bit in the bitmap, each non-zero bit in
 348   // the bitmap represents a relocation to be applied to a corresponding machine
 349   // word that follows the base address word. The second least significant bit
 350   // represents the machine word immediately following the initial address, and
 351   // each bit that follows represents the next word, in linear order. As such,
 352   // a single bitmap can encode up to 31 relocations in a 32-bit object, and
 353   // 63 relocations in a 64-bit object.
 354   //
 355   // This encoding has a couple of interesting properties:
 356   // 1. Looking at any entry, it is clear whether it's an address or a bitmap:
 357   //    even means address, odd means bitmap.
 358   // 2. Just a simple list of addresses is a valid encoding.
 359
 360   Elf_Rel Rel;
 361   Rel.r_info = 0;
 362   Rel.setType(getRelativeRelocationType(), false);
 363   std::vector<Elf_Rel> Relocs;
 364
 365   // Word type: uint32_t for Elf32, and uint64_t for Elf64.
 366   using Addr = typename ELFT::uint;
 367
 368   Addr Base = 0;
 369   for (Elf_Relr R : relrs) {
 370     typename ELFT::uint Entry = R;
 371     if ((Entry & 1) == 0) {
 372       // Even entry: encodes the offset for next relocation.
 373       Rel.r_offset = Entry;
 374       Relocs.push_back(Rel);
 375       // Set base offset for subsequent bitmap entries.
 376       Base = Entry + sizeof(Addr);
 377     } else {
 378       // Odd entry: encodes bitmap for relocations starting at base.
 379       for (Addr Offset = Base; (Entry >>= 1) != 0; Offset += sizeof(Addr))
 380         if ((Entry & 1) != 0) {
 381           Rel.r_offset = Offset;
 382           Relocs.push_back(Rel);
 383         }
 384       Base += (CHAR_BIT * sizeof(Entry) - 1) * sizeof(Addr);
 385     }
 386   }
 387
 388   return Relocs;
 389 }
 390
 391 template <class ELFT>
 392 Expected<std::vector<typename ELFT::Rela>>
 393 ELFFile<ELFT>::android_relas(const Elf_Shdr &Sec) const {
 394   // This function reads relocations in Android's packed relocation format,
 395   // which is based on SLEB128 and delta encoding.
 396   Expected<ArrayRef<uint8_t>> ContentsOrErr = getSectionContents(Sec);
 397   if (!ContentsOrErr)
 398     return ContentsOrErr.takeError();
 399   ArrayRef<uint8_t> Content = *ContentsOrErr;
 400   if (Content.size() < 4 || Content[0] != 'A' || Content[1] != 'P' ||
 401       Content[2] != 'S' || Content[3] != '2')
 402     return createError("invalid packed relocation header");
 403   DataExtractor Data(Content, isLE(), ELFT::Is64Bits ? 8 : 4);
 404   DataExtractor::Cursor Cur(/*Offset=*/4);
 405
 406   uint64_t NumRelocs = Data.getSLEB128(Cur);
 407   uint64_t Offset = Data.getSLEB128(Cur);
 408   uint64_t Addend = 0;
 409
 410   if (!Cur)
 411     return std::move(Cur.takeError());
 412
 413   std::vector<Elf_Rela> Relocs;
 414   Relocs.reserve(NumRelocs);
 415   while (NumRelocs) {
 416     uint64_t NumRelocsInGroup = Data.getSLEB128(Cur);
 417     if (!Cur)
 418       return std::move(Cur.takeError());
 419     if (NumRelocsInGroup > NumRelocs)
 420       return createError("relocation group unexpectedly large");
 421     NumRelocs -= NumRelocsInGroup;
 422
 423     uint64_t GroupFlags = Data.getSLEB128(Cur);
 424     bool GroupedByInfo = GroupFlags & ELF::RELOCATION_GROUPED_BY_INFO_FLAG;
 425     bool GroupedByOffsetDelta = GroupFlags & ELF::RELOCATION_GROUPED_BY_OFFSET_DELTA_FLAG;
 426     bool GroupedByAddend = GroupFlags & ELF::RELOCATION_GROUPED_BY_ADDEND_FLAG;
 427     bool GroupHasAddend = GroupFlags & ELF::RELOCATION_GROUP_HAS_ADDEND_FLAG;
 428
 429     uint64_t GroupOffsetDelta;
 430     if (GroupedByOffsetDelta)
 431       GroupOffsetDelta = Data.getSLEB128(Cur);
 432
 433     uint64_t GroupRInfo;
 434     if (GroupedByInfo)
 435       GroupRInfo = Data.getSLEB128(Cur);
 436
 437     if (GroupedByAddend && GroupHasAddend)
 438       Addend += Data.getSLEB128(Cur);
 439
 440     if (!GroupHasAddend)
 441       Addend = 0;
 442
 443     for (uint64_t I = 0; Cur && I != NumRelocsInGroup; ++I) {
 444       Elf_Rela R;
 445       Offset += GroupedByOffsetDelta ? GroupOffsetDelta : Data.getSLEB128(Cur);
 446       R.r_offset = Offset;
 447       R.r_info = GroupedByInfo ? GroupRInfo : Data.getSLEB128(Cur);
 448       if (GroupHasAddend && !GroupedByAddend)
 449         Addend += Data.getSLEB128(Cur);
 450       R.r_addend = Addend;
 451       Relocs.push_back(R);
 452     }
 453     if (!Cur)
 454       return std::move(Cur.takeError());
 455   }
 456
 457   return Relocs;
 458 }
 459
 460 template <class ELFT>
 461 std::string ELFFile<ELFT>::getDynamicTagAsString(unsigned Arch,
 462                                                  uint64_t Type) const {
 463 #define DYNAMIC_STRINGIFY_ENUM(tag, value)                                     \
 464   case value:                                                                  \
 465     return #tag;
 466
 467 #define DYNAMIC_TAG(n, v)
 468   switch (Arch) {
 469   case ELF::EM_AARCH64:
 470     switch (Type) {
 471 #define AARCH64_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value)
 472 #include "llvm/BinaryFormat/DynamicTags.def"
 473 #undef AARCH64_DYNAMIC_TAG
 474     }
 475     break;
 476
 477   case ELF::EM_HEXAGON:
 478     switch (Type) {
 479 #define HEXAGON_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value)
 480 #include "llvm/BinaryFormat/DynamicTags.def"
 481 #undef HEXAGON_DYNAMIC_TAG
 482     }
 483     break;
 484
 485   case ELF::EM_MIPS:
 486     switch (Type) {
 487 #define MIPS_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value)
 488 #include "llvm/BinaryFormat/DynamicTags.def"
 489 #undef MIPS_DYNAMIC_TAG
 490     }
 491     break;
 492
 493   case ELF::EM_PPC:
 494     switch (Type) {
 495 #define PPC_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value)
 496 #include "llvm/BinaryFormat/DynamicTags.def"
 497 #undef PPC_DYNAMIC_TAG
 498     }
 499     break;
 500
 501   case ELF::EM_PPC64:
 502     switch (Type) {
 503 #define PPC64_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value)
 504 #include "llvm/BinaryFormat/DynamicTags.def"
 505 #undef PPC64_DYNAMIC_TAG
 506     }
 507     break;
 508
 509   case ELF::EM_RISCV:
 510     switch (Type) {
 511 #define RISCV_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value)
 512 #include "llvm/BinaryFormat/DynamicTags.def"
 513 #undef RISCV_DYNAMIC_TAG
 514     }
 515     break;
 516   }
 517 #undef DYNAMIC_TAG
 518   switch (Type) {
 519 // Now handle all dynamic tags except the architecture specific ones
 520 #define AARCH64_DYNAMIC_TAG(name, value)
 521 #define MIPS_DYNAMIC_TAG(name, value)
 522 #define HEXAGON_DYNAMIC_TAG(name, value)
 523 #define PPC_DYNAMIC_TAG(name, value)
 524 #define PPC64_DYNAMIC_TAG(name, value)
 525 #define RISCV_DYNAMIC_TAG(name, value)
 526 // Also ignore marker tags such as DT_HIOS (maps to DT_VERNEEDNUM), etc.
 527 #define DYNAMIC_TAG_MARKER(name, value)
 528 #define DYNAMIC_TAG(name, value) case value: return #name;
 529 #include "llvm/BinaryFormat/DynamicTags.def"
 530 #undef DYNAMIC_TAG
 531 #undef AARCH64_DYNAMIC_TAG
 532 #undef MIPS_DYNAMIC_TAG
 533 #undef HEXAGON_DYNAMIC_TAG
 534 #undef PPC_DYNAMIC_TAG
 535 #undef PPC64_DYNAMIC_TAG
 536 #undef RISCV_DYNAMIC_TAG
 537 #undef DYNAMIC_TAG_MARKER
 538 #undef DYNAMIC_STRINGIFY_ENUM
 539   default:
 540     return "<unknown:>0x" + utohexstr(Type, true);
 541   }
 542 }
 543
 544 template <class ELFT>
 545 std::string ELFFile<ELFT>::getDynamicTagAsString(uint64_t Type) const {
 546   return getDynamicTagAsString(getHeader().e_machine, Type);
 547 }
 548
 549 template <class ELFT>
 550 Expected<typename ELFT::DynRange> ELFFile<ELFT>::dynamicEntries() const {
 551   ArrayRef<Elf_Dyn> Dyn;
 552
 553   auto ProgramHeadersOrError = program_headers();
 554   if (!ProgramHeadersOrError)
 555     return ProgramHeadersOrError.takeError();
 556
 557   for (const Elf_Phdr &Phdr : *ProgramHeadersOrError) {
 558     if (Phdr.p_type == ELF::PT_DYNAMIC) {
 559       Dyn = ArrayRef(reinterpret_cast<const Elf_Dyn *>(base() + Phdr.p_offset),
 560                      Phdr.p_filesz / sizeof(Elf_Dyn));
 561       break;
 562     }
 563   }
 564
 565   // If we can't find the dynamic section in the program headers, we just fall
 566   // back on the sections.
 567   if (Dyn.empty()) {
 568     auto SectionsOrError = sections();
 569     if (!SectionsOrError)
 570       return SectionsOrError.takeError();
 571
 572     for (const Elf_Shdr &Sec : *SectionsOrError) {
 573       if (Sec.sh_type == ELF::SHT_DYNAMIC) {
 574         Expected<ArrayRef<Elf_Dyn>> DynOrError =
 575             getSectionContentsAsArray<Elf_Dyn>(Sec);
 576         if (!DynOrError)
 577           return DynOrError.takeError();
 578         Dyn = *DynOrError;
 579         break;
 580       }
 581     }
 582
 583     if (!Dyn.data())
 584       return ArrayRef<Elf_Dyn>();
 585   }
 586
 587   if (Dyn.empty())
 588     return createError("invalid empty dynamic section");
 589
 590   if (Dyn.back().d_tag != ELF::DT_NULL)
 591     return createError("dynamic sections must be DT_NULL terminated");
 592
 593   return Dyn;
 594 }
 595
 596 template <class ELFT>
 597 Expected<const uint8_t *>
 598 ELFFile<ELFT>::toMappedAddr(uint64_t VAddr, WarningHandler WarnHandler) const {
 599   auto ProgramHeadersOrError = program_headers();
 600   if (!ProgramHeadersOrError)
 601     return ProgramHeadersOrError.takeError();
 602
 603   llvm::SmallVector<Elf_Phdr *, 4> LoadSegments;
 604
 605   for (const Elf_Phdr &Phdr : *ProgramHeadersOrError)
 606     if (Phdr.p_type == ELF::PT_LOAD)
 607       LoadSegments.push_back(const_cast<Elf_Phdr *>(&Phdr));
 608
 609   auto SortPred = [](const Elf_Phdr_Impl<ELFT> *A,
 610                      const Elf_Phdr_Impl<ELFT> *B) {
 611     return A->p_vaddr < B->p_vaddr;
 612   };
 613   if (!llvm::is_sorted(LoadSegments, SortPred)) {
 614     if (Error E =
 615             WarnHandler("loadable segments are unsorted by virtual address"))
 616       return std::move(E);
 617     llvm::stable_sort(LoadSegments, SortPred);
 618   }
 619
 620   const Elf_Phdr *const *I = llvm::upper_bound(
 621       LoadSegments, VAddr, [](uint64_t VAddr, const Elf_Phdr_Impl<ELFT> *Phdr) {
 622         return VAddr < Phdr->p_vaddr;
 623       });
 624
 625   if (I == LoadSegments.begin())
 626     return createError("virtual address is not in any segment: 0x" +
 627                        Twine::utohexstr(VAddr));
 628   --I;
 629   const Elf_Phdr &Phdr = **I;
 630   uint64_t Delta = VAddr - Phdr.p_vaddr;
 631   if (Delta >= Phdr.p_filesz)
 632     return createError("virtual address is not in any segment: 0x" +
 633                        Twine::utohexstr(VAddr));
 634
 635   uint64_t Offset = Phdr.p_offset + Delta;
 636   if (Offset >= getBufSize())
 637     return createError("can't map virtual address 0x" +
 638                        Twine::utohexstr(VAddr) + " to the segment with index " +
 639                        Twine(&Phdr - (*ProgramHeadersOrError).data() + 1) +
 640                        ": the segment ends at 0x" +
 641                        Twine::utohexstr(Phdr.p_offset + Phdr.p_filesz) +
 642                        ", which is greater than the file size (0x" +
 643                        Twine::utohexstr(getBufSize()) + ")");
 644
 645   return base() + Offset;
 646 }
 647
 648 template <class ELFT>
 649 Expected<std::vector<BBAddrMap>>
 650 ELFFile<ELFT>::decodeBBAddrMap(const Elf_Shdr &Sec,
 651                                const Elf_Shdr *RelaSec) const {
 652   bool IsRelocatable = getHeader().e_type == ELF::ET_REL;
 653
 654   // This DenseMap maps the offset of each function (the location of the
 655   // reference to the function in the SHT_LLVM_BB_ADDR_MAP section) to the
 656   // addend (the location of the function in the text section).
 657   llvm::DenseMap<uint64_t, uint64_t> FunctionOffsetTranslations;
 658   if (IsRelocatable && RelaSec) {
 659     assert(RelaSec &&
 660            "Can't read a SHT_LLVM_BB_ADDR_MAP section in a relocatable "
 661            "object file without providing a relocation section.");
 662     Expected<Elf_Rela_Range> Relas = this->relas(*RelaSec);
 663     if (!Relas)
 664       return createError("unable to read relocations for section " +
 665                          describe(*this, Sec) + ": " +
 666                          toString(Relas.takeError()));
 667     for (Elf_Rela Rela : *Relas)
 668       FunctionOffsetTranslations[Rela.r_offset] = Rela.r_addend;
 669   }
 670   Expected<ArrayRef<uint8_t>> ContentsOrErr = getSectionContents(Sec);
 671   if (!ContentsOrErr)
 672     return ContentsOrErr.takeError();
 673   ArrayRef<uint8_t> Content = *ContentsOrErr;
 674   DataExtractor Data(Content, isLE(), ELFT::Is64Bits ? 8 : 4);
 675   std::vector<BBAddrMap> FunctionEntries;
 676
 677   DataExtractor::Cursor Cur(0);
 678   Error ULEBSizeErr = Error::success();
 679   Error MetadataDecodeErr = Error::success();
 680   // Helper to extract and decode the next ULEB128 value as uint32_t.
 681   // Returns zero and sets ULEBSizeErr if the ULEB128 value exceeds the uint32_t
 682   // limit.
 683   // Also returns zero if ULEBSizeErr is already in an error state.
 684   auto ReadULEB128AsUInt32 = [&Data, &Cur, &ULEBSizeErr]() -> uint32_t {
 685     // Bail out and do not extract data if ULEBSizeErr is already set.
 686     if (ULEBSizeErr)
 687       return 0;
 688     uint64_t Offset = Cur.tell();
 689     uint64_t Value = Data.getULEB128(Cur);
 690     if (Value > UINT32_MAX) {
 691       ULEBSizeErr = createError(
 692           "ULEB128 value at offset 0x" + Twine::utohexstr(Offset) +
 693           " exceeds UINT32_MAX (0x" + Twine::utohexstr(Value) + ")");
 694       return 0;
 695     }
 696     return static_cast<uint32_t>(Value);
 697   };
 698
 699   uint8_t Version = 0;
 700   while (!ULEBSizeErr && !MetadataDecodeErr && Cur &&
 701          Cur.tell() < Content.size()) {
 702     if (Sec.sh_type == ELF::SHT_LLVM_BB_ADDR_MAP) {
 703       Version = Data.getU8(Cur);
 704       if (!Cur)
 705         break;
 706       if (Version > 2)
 707         return createError("unsupported SHT_LLVM_BB_ADDR_MAP version: " +
 708                            Twine(static_cast<int>(Version)));
 709       Data.getU8(Cur); // Feature byte
 710     }
 711     uint64_t SectionOffset = Cur.tell();
 712     uintX_t Address = static_cast<uintX_t>(Data.getAddress(Cur));
 713     if (!Cur)
 714       return Cur.takeError();
 715     if (IsRelocatable) {
 716       assert(Address == 0);
 717       auto FOTIterator = FunctionOffsetTranslations.find(SectionOffset);
 718       if (FOTIterator == FunctionOffsetTranslations.end()) {
 719         return createError("failed to get relocation data for offset: " +
 720                            Twine::utohexstr(SectionOffset) + " in section " +
 721                            describe(*this, Sec));
 722       }
 723       Address = FOTIterator->second;
 724     }
 725     uint32_t NumBlocks = ReadULEB128AsUInt32();
 726     std::vector<BBAddrMap::BBEntry> BBEntries;
 727     uint32_t PrevBBEndOffset = 0;
 728     for (uint32_t BlockIndex = 0;
 729          !MetadataDecodeErr && !ULEBSizeErr && Cur && (BlockIndex < NumBlocks);
 730          ++BlockIndex) {
 731       uint32_t ID = Version >= 2 ? ReadULEB128AsUInt32() : BlockIndex;
 732       uint32_t Offset = ReadULEB128AsUInt32();
 733       uint32_t Size = ReadULEB128AsUInt32();
 734       uint32_t MD = ReadULEB128AsUInt32();
 735       if (Version >= 1) {
 736         // Offset is calculated relative to the end of the previous BB.
 737         Offset += PrevBBEndOffset;
 738         PrevBBEndOffset = Offset + Size;
 739       }
 740       Expected<BBAddrMap::BBEntry::Metadata> MetadataOrErr =
 741           BBAddrMap::BBEntry::Metadata::decode(MD);
 742       if (!MetadataOrErr) {
 743         MetadataDecodeErr = MetadataOrErr.takeError();
 744         break;
 745       }
 746       BBEntries.push_back({ID, Offset, Size, *MetadataOrErr});
 747     }
 748     FunctionEntries.push_back({Address, std::move(BBEntries)});
 749   }
 750   // Either Cur is in the error state, or we have an error in ULEBSizeErr or
 751   // MetadataDecodeErr (but not both), but we join all errors here to be safe.
 752   if (!Cur || ULEBSizeErr || MetadataDecodeErr)
 753     return joinErrors(joinErrors(Cur.takeError(), std::move(ULEBSizeErr)),
 754                       std::move(MetadataDecodeErr));
 755   return FunctionEntries;
 756 }
 757
 758 template <class ELFT>
 759 Expected<
 760     MapVector<const typename ELFT::Shdr *, const typename ELFT::Shdr *>>
 761 ELFFile<ELFT>::getSectionAndRelocations(
 762     std::function<Expected<bool>(const Elf_Shdr &)> IsMatch) const {
 763   MapVector<const Elf_Shdr *, const Elf_Shdr *> SecToRelocMap;
 764   Error Errors = Error::success();
 765   for (const Elf_Shdr &Sec : cantFail(this->sections())) {
 766     Expected<bool> DoesSectionMatch = IsMatch(Sec);
 767     if (!DoesSectionMatch) {
 768       Errors = joinErrors(std::move(Errors), DoesSectionMatch.takeError());
 769       continue;
 770     }
 771     if (*DoesSectionMatch) {
 772       if (SecToRelocMap.insert(std::make_pair(&Sec, (const Elf_Shdr *)nullptr))
 773               .second)
 774         continue;
 775     }
 776
 777     if (Sec.sh_type != ELF::SHT_RELA && Sec.sh_type != ELF::SHT_REL)
 778       continue;
 779
 780     Expected<const Elf_Shdr *> RelSecOrErr = this->getSection(Sec.sh_info);
 781     if (!RelSecOrErr) {
 782       Errors = joinErrors(std::move(Errors),
 783                           createError(describe(*this, Sec) +
 784                                       ": failed to get a relocated section: " +
 785                                       toString(RelSecOrErr.takeError())));
 786       continue;
 787     }
 788     const Elf_Shdr *ContentsSec = *RelSecOrErr;
 789     Expected<bool> DoesRelTargetMatch = IsMatch(*ContentsSec);
 790     if (!DoesRelTargetMatch) {
 791       Errors = joinErrors(std::move(Errors), DoesRelTargetMatch.takeError());
 792       continue;
 793     }
 794     if (*DoesRelTargetMatch)
 795       SecToRelocMap[ContentsSec] = &Sec;
 796   }
 797   if(Errors)
 798     return std::move(Errors);
 799   return SecToRelocMap;
 800 }
 801
 802 template class llvm::object::ELFFile<ELF32LE>;
 803 template class llvm::object::ELFFile<ELF32BE>;
 804 template class llvm::object::ELFFile<ELF64LE>;
 805 template class llvm::object::ELFFile<ELF64BE>;