//===- ELF.cpp - ELF object file implementation ---------------------------===// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// #include "llvm/Object/ELF.h" #include "llvm/BinaryFormat/ELF.h" #include "llvm/Support/DataExtractor.h" using namespace llvm; using namespace object; #define STRINGIFY_ENUM_CASE(ns, name) \ case ns::name: \ return #name; #define ELF_RELOC(name, value) STRINGIFY_ENUM_CASE(ELF, name) StringRef llvm::object::getELFRelocationTypeName(uint32_t Machine, uint32_t Type) { switch (Machine) { case ELF::EM_68K: switch (Type) { #include "llvm/BinaryFormat/ELFRelocs/M68k.def" default: break; } break; case ELF::EM_X86_64: switch (Type) { #include "llvm/BinaryFormat/ELFRelocs/x86_64.def" default: break; } break; case ELF::EM_386: case ELF::EM_IAMCU: switch (Type) { #include "llvm/BinaryFormat/ELFRelocs/i386.def" default: break; } break; case ELF::EM_MIPS: switch (Type) { #include "llvm/BinaryFormat/ELFRelocs/Mips.def" default: break; } break; case ELF::EM_AARCH64: switch (Type) { #include "llvm/BinaryFormat/ELFRelocs/AArch64.def" default: break; } break; case ELF::EM_ARM: switch (Type) { #include "llvm/BinaryFormat/ELFRelocs/ARM.def" default: break; } break; case ELF::EM_ARC_COMPACT: case ELF::EM_ARC_COMPACT2: switch (Type) { #include "llvm/BinaryFormat/ELFRelocs/ARC.def" default: break; } break; case ELF::EM_AVR: switch (Type) { #include "llvm/BinaryFormat/ELFRelocs/AVR.def" default: break; } break; case ELF::EM_HEXAGON: switch (Type) { #include "llvm/BinaryFormat/ELFRelocs/Hexagon.def" default: break; } break; case ELF::EM_LANAI: switch (Type) { #include "llvm/BinaryFormat/ELFRelocs/Lanai.def" default: break; } break; case ELF::EM_PPC: switch (Type) { #include "llvm/BinaryFormat/ELFRelocs/PowerPC.def" default: break; } break; case ELF::EM_PPC64: switch (Type) { #include "llvm/BinaryFormat/ELFRelocs/PowerPC64.def" default: break; } break; case ELF::EM_RISCV: switch (Type) { #include "llvm/BinaryFormat/ELFRelocs/RISCV.def" default: break; } break; case ELF::EM_S390: switch (Type) { #include "llvm/BinaryFormat/ELFRelocs/SystemZ.def" default: break; } break; case ELF::EM_SPARC: case ELF::EM_SPARC32PLUS: case ELF::EM_SPARCV9: switch (Type) { #include "llvm/BinaryFormat/ELFRelocs/Sparc.def" default: break; } break; case ELF::EM_AMDGPU: switch (Type) { #include "llvm/BinaryFormat/ELFRelocs/AMDGPU.def" default: break; } break; case ELF::EM_BPF: switch (Type) { #include "llvm/BinaryFormat/ELFRelocs/BPF.def" default: break; } break; case ELF::EM_MSP430: switch (Type) { #include "llvm/BinaryFormat/ELFRelocs/MSP430.def" default: break; } break; case ELF::EM_VE: switch (Type) { #include "llvm/BinaryFormat/ELFRelocs/VE.def" default: break; } break; case ELF::EM_CSKY: switch (Type) { #include "llvm/BinaryFormat/ELFRelocs/CSKY.def" default: break; } break; default: break; } return "Unknown"; } #undef ELF_RELOC uint32_t llvm::object::getELFRelativeRelocationType(uint32_t Machine) { switch (Machine) { case ELF::EM_X86_64: return ELF::R_X86_64_RELATIVE; case ELF::EM_386: case ELF::EM_IAMCU: return ELF::R_386_RELATIVE; case ELF::EM_MIPS: break; case ELF::EM_AARCH64: return ELF::R_AARCH64_RELATIVE; case ELF::EM_ARM: return ELF::R_ARM_RELATIVE; case ELF::EM_ARC_COMPACT: case ELF::EM_ARC_COMPACT2: return ELF::R_ARC_RELATIVE; case ELF::EM_AVR: break; case ELF::EM_HEXAGON: return ELF::R_HEX_RELATIVE; case ELF::EM_LANAI: break; case ELF::EM_PPC: break; case ELF::EM_PPC64: return ELF::R_PPC64_RELATIVE; case ELF::EM_RISCV: return ELF::R_RISCV_RELATIVE; case ELF::EM_S390: return ELF::R_390_RELATIVE; case ELF::EM_SPARC: case ELF::EM_SPARC32PLUS: case ELF::EM_SPARCV9: return ELF::R_SPARC_RELATIVE; case ELF::EM_CSKY: return ELF::R_CKCORE_RELATIVE; case ELF::EM_AMDGPU: break; case ELF::EM_BPF: break; default: break; } return 0; } StringRef llvm::object::getELFSectionTypeName(uint32_t Machine, unsigned Type) { switch (Machine) { case ELF::EM_ARM: switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_ARM_EXIDX); STRINGIFY_ENUM_CASE(ELF, SHT_ARM_PREEMPTMAP); STRINGIFY_ENUM_CASE(ELF, SHT_ARM_ATTRIBUTES); STRINGIFY_ENUM_CASE(ELF, SHT_ARM_DEBUGOVERLAY); STRINGIFY_ENUM_CASE(ELF, SHT_ARM_OVERLAYSECTION); } break; case ELF::EM_HEXAGON: switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_HEX_ORDERED); } break; case ELF::EM_X86_64: switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_X86_64_UNWIND); } break; case ELF::EM_MIPS: case ELF::EM_MIPS_RS3_LE: switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_MIPS_REGINFO); STRINGIFY_ENUM_CASE(ELF, SHT_MIPS_OPTIONS); STRINGIFY_ENUM_CASE(ELF, SHT_MIPS_DWARF); STRINGIFY_ENUM_CASE(ELF, SHT_MIPS_ABIFLAGS); } break; case ELF::EM_RISCV: switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_RISCV_ATTRIBUTES); } break; default: break; } switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_NULL); STRINGIFY_ENUM_CASE(ELF, SHT_PROGBITS); STRINGIFY_ENUM_CASE(ELF, SHT_SYMTAB); STRINGIFY_ENUM_CASE(ELF, SHT_STRTAB); STRINGIFY_ENUM_CASE(ELF, SHT_RELA); STRINGIFY_ENUM_CASE(ELF, SHT_HASH); STRINGIFY_ENUM_CASE(ELF, SHT_DYNAMIC); STRINGIFY_ENUM_CASE(ELF, SHT_NOTE); STRINGIFY_ENUM_CASE(ELF, SHT_NOBITS); STRINGIFY_ENUM_CASE(ELF, SHT_REL); STRINGIFY_ENUM_CASE(ELF, SHT_SHLIB); STRINGIFY_ENUM_CASE(ELF, SHT_DYNSYM); STRINGIFY_ENUM_CASE(ELF, SHT_INIT_ARRAY); STRINGIFY_ENUM_CASE(ELF, SHT_FINI_ARRAY); STRINGIFY_ENUM_CASE(ELF, SHT_PREINIT_ARRAY); STRINGIFY_ENUM_CASE(ELF, SHT_GROUP); STRINGIFY_ENUM_CASE(ELF, SHT_SYMTAB_SHNDX); STRINGIFY_ENUM_CASE(ELF, SHT_RELR); STRINGIFY_ENUM_CASE(ELF, SHT_ANDROID_REL); STRINGIFY_ENUM_CASE(ELF, SHT_ANDROID_RELA); STRINGIFY_ENUM_CASE(ELF, SHT_ANDROID_RELR); STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_ODRTAB); STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_LINKER_OPTIONS); STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_CALL_GRAPH_PROFILE); STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_ADDRSIG); STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_DEPENDENT_LIBRARIES); STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_SYMPART); STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_PART_EHDR); STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_PART_PHDR); STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_BB_ADDR_MAP); STRINGIFY_ENUM_CASE(ELF, SHT_GNU_ATTRIBUTES); STRINGIFY_ENUM_CASE(ELF, SHT_GNU_HASH); STRINGIFY_ENUM_CASE(ELF, SHT_GNU_verdef); STRINGIFY_ENUM_CASE(ELF, SHT_GNU_verneed); STRINGIFY_ENUM_CASE(ELF, SHT_GNU_versym); default: return "Unknown"; } } template std::vector ELFFile::decode_relrs(Elf_Relr_Range relrs) const { // This function decodes the contents of an SHT_RELR packed relocation // section. // // Proposal for adding SHT_RELR sections to generic-abi is here: // https://groups.google.com/forum/#!topic/generic-abi/bX460iggiKg // // The encoded sequence of Elf64_Relr entries in a SHT_RELR section looks // like [ AAAAAAAA BBBBBBB1 BBBBBBB1 ... AAAAAAAA BBBBBB1 ... ] // // i.e. start with an address, followed by any number of bitmaps. The address // entry encodes 1 relocation. The subsequent bitmap entries encode up to 63 // relocations each, at subsequent offsets following the last address entry. // // The bitmap entries must have 1 in the least significant bit. The assumption // here is that an address cannot have 1 in lsb. Odd addresses are not // supported. // // Excluding the least significant bit in the bitmap, each non-zero bit in // the bitmap represents a relocation to be applied to a corresponding machine // word that follows the base address word. The second least significant bit // represents the machine word immediately following the initial address, and // each bit that follows represents the next word, in linear order. As such, // a single bitmap can encode up to 31 relocations in a 32-bit object, and // 63 relocations in a 64-bit object. // // This encoding has a couple of interesting properties: // 1. Looking at any entry, it is clear whether it's an address or a bitmap: // even means address, odd means bitmap. // 2. Just a simple list of addresses is a valid encoding. Elf_Rel Rel; Rel.r_info = 0; Rel.setType(getRelativeRelocationType(), false); std::vector Relocs; // Word type: uint32_t for Elf32, and uint64_t for Elf64. typedef typename ELFT::uint Word; // Word size in number of bytes. const size_t WordSize = sizeof(Word); // Number of bits used for the relocation offsets bitmap. // These many relative relocations can be encoded in a single entry. const size_t NBits = 8*WordSize - 1; Word Base = 0; for (const Elf_Relr &R : relrs) { Word Entry = R; if ((Entry&1) == 0) { // Even entry: encodes the offset for next relocation. Rel.r_offset = Entry; Relocs.push_back(Rel); // Set base offset for subsequent bitmap entries. Base = Entry + WordSize; continue; } // Odd entry: encodes bitmap for relocations starting at base. Word Offset = Base; while (Entry != 0) { Entry >>= 1; if ((Entry&1) != 0) { Rel.r_offset = Offset; Relocs.push_back(Rel); } Offset += WordSize; } // Advance base offset by NBits words. Base += NBits * WordSize; } return Relocs; } template Expected> ELFFile::android_relas(const Elf_Shdr &Sec) const { // This function reads relocations in Android's packed relocation format, // which is based on SLEB128 and delta encoding. Expected> ContentsOrErr = getSectionContents(Sec); if (!ContentsOrErr) return ContentsOrErr.takeError(); ArrayRef Content = *ContentsOrErr; if (Content.size() < 4 || Content[0] != 'A' || Content[1] != 'P' || Content[2] != 'S' || Content[3] != '2') return createError("invalid packed relocation header"); DataExtractor Data(Content, isLE(), ELFT::Is64Bits ? 8 : 4); DataExtractor::Cursor Cur(/*Offset=*/4); uint64_t NumRelocs = Data.getSLEB128(Cur); uint64_t Offset = Data.getSLEB128(Cur); uint64_t Addend = 0; if (!Cur) return std::move(Cur.takeError()); std::vector Relocs; Relocs.reserve(NumRelocs); while (NumRelocs) { uint64_t NumRelocsInGroup = Data.getSLEB128(Cur); if (!Cur) return std::move(Cur.takeError()); if (NumRelocsInGroup > NumRelocs) return createError("relocation group unexpectedly large"); NumRelocs -= NumRelocsInGroup; uint64_t GroupFlags = Data.getSLEB128(Cur); bool GroupedByInfo = GroupFlags & ELF::RELOCATION_GROUPED_BY_INFO_FLAG; bool GroupedByOffsetDelta = GroupFlags & ELF::RELOCATION_GROUPED_BY_OFFSET_DELTA_FLAG; bool GroupedByAddend = GroupFlags & ELF::RELOCATION_GROUPED_BY_ADDEND_FLAG; bool GroupHasAddend = GroupFlags & ELF::RELOCATION_GROUP_HAS_ADDEND_FLAG; uint64_t GroupOffsetDelta; if (GroupedByOffsetDelta) GroupOffsetDelta = Data.getSLEB128(Cur); uint64_t GroupRInfo; if (GroupedByInfo) GroupRInfo = Data.getSLEB128(Cur); if (GroupedByAddend && GroupHasAddend) Addend += Data.getSLEB128(Cur); if (!GroupHasAddend) Addend = 0; for (uint64_t I = 0; Cur && I != NumRelocsInGroup; ++I) { Elf_Rela R; Offset += GroupedByOffsetDelta ? GroupOffsetDelta : Data.getSLEB128(Cur); R.r_offset = Offset; R.r_info = GroupedByInfo ? GroupRInfo : Data.getSLEB128(Cur); if (GroupHasAddend && !GroupedByAddend) Addend += Data.getSLEB128(Cur); R.r_addend = Addend; Relocs.push_back(R); } if (!Cur) return std::move(Cur.takeError()); } return Relocs; } template std::string ELFFile::getDynamicTagAsString(unsigned Arch, uint64_t Type) const { #define DYNAMIC_STRINGIFY_ENUM(tag, value) \ case value: \ return #tag; #define DYNAMIC_TAG(n, v) switch (Arch) { case ELF::EM_AARCH64: switch (Type) { #define AARCH64_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value) #include "llvm/BinaryFormat/DynamicTags.def" #undef AARCH64_DYNAMIC_TAG } break; case ELF::EM_HEXAGON: switch (Type) { #define HEXAGON_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value) #include "llvm/BinaryFormat/DynamicTags.def" #undef HEXAGON_DYNAMIC_TAG } break; case ELF::EM_MIPS: switch (Type) { #define MIPS_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value) #include "llvm/BinaryFormat/DynamicTags.def" #undef MIPS_DYNAMIC_TAG } break; case ELF::EM_PPC64: switch (Type) { #define PPC64_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value) #include "llvm/BinaryFormat/DynamicTags.def" #undef PPC64_DYNAMIC_TAG } break; } #undef DYNAMIC_TAG switch (Type) { // Now handle all dynamic tags except the architecture specific ones #define AARCH64_DYNAMIC_TAG(name, value) #define MIPS_DYNAMIC_TAG(name, value) #define HEXAGON_DYNAMIC_TAG(name, value) #define PPC64_DYNAMIC_TAG(name, value) // Also ignore marker tags such as DT_HIOS (maps to DT_VERNEEDNUM), etc. #define DYNAMIC_TAG_MARKER(name, value) #define DYNAMIC_TAG(name, value) case value: return #name; #include "llvm/BinaryFormat/DynamicTags.def" #undef DYNAMIC_TAG #undef AARCH64_DYNAMIC_TAG #undef MIPS_DYNAMIC_TAG #undef HEXAGON_DYNAMIC_TAG #undef PPC64_DYNAMIC_TAG #undef DYNAMIC_TAG_MARKER #undef DYNAMIC_STRINGIFY_ENUM default: return "0x" + utohexstr(Type, true); } } template std::string ELFFile::getDynamicTagAsString(uint64_t Type) const { return getDynamicTagAsString(getHeader().e_machine, Type); } template Expected ELFFile::dynamicEntries() const { ArrayRef Dyn; auto ProgramHeadersOrError = program_headers(); if (!ProgramHeadersOrError) return ProgramHeadersOrError.takeError(); for (const Elf_Phdr &Phdr : *ProgramHeadersOrError) { if (Phdr.p_type == ELF::PT_DYNAMIC) { Dyn = makeArrayRef( reinterpret_cast(base() + Phdr.p_offset), Phdr.p_filesz / sizeof(Elf_Dyn)); break; } } // If we can't find the dynamic section in the program headers, we just fall // back on the sections. if (Dyn.empty()) { auto SectionsOrError = sections(); if (!SectionsOrError) return SectionsOrError.takeError(); for (const Elf_Shdr &Sec : *SectionsOrError) { if (Sec.sh_type == ELF::SHT_DYNAMIC) { Expected> DynOrError = getSectionContentsAsArray(Sec); if (!DynOrError) return DynOrError.takeError(); Dyn = *DynOrError; break; } } if (!Dyn.data()) return ArrayRef(); } if (Dyn.empty()) // TODO: this error is untested. return createError("invalid empty dynamic section"); if (Dyn.back().d_tag != ELF::DT_NULL) // TODO: this error is untested. return createError("dynamic sections must be DT_NULL terminated"); return Dyn; } template Expected ELFFile::toMappedAddr(uint64_t VAddr, WarningHandler WarnHandler) const { auto ProgramHeadersOrError = program_headers(); if (!ProgramHeadersOrError) return ProgramHeadersOrError.takeError(); llvm::SmallVector LoadSegments; for (const Elf_Phdr &Phdr : *ProgramHeadersOrError) if (Phdr.p_type == ELF::PT_LOAD) LoadSegments.push_back(const_cast(&Phdr)); auto SortPred = [](const Elf_Phdr_Impl *A, const Elf_Phdr_Impl *B) { return A->p_vaddr < B->p_vaddr; }; if (!llvm::is_sorted(LoadSegments, SortPred)) { if (Error E = WarnHandler("loadable segments are unsorted by virtual address")) return std::move(E); llvm::stable_sort(LoadSegments, SortPred); } const Elf_Phdr *const *I = llvm::upper_bound( LoadSegments, VAddr, [](uint64_t VAddr, const Elf_Phdr_Impl *Phdr) { return VAddr < Phdr->p_vaddr; }); if (I == LoadSegments.begin()) return createError("virtual address is not in any segment: 0x" + Twine::utohexstr(VAddr)); --I; const Elf_Phdr &Phdr = **I; uint64_t Delta = VAddr - Phdr.p_vaddr; if (Delta >= Phdr.p_filesz) return createError("virtual address is not in any segment: 0x" + Twine::utohexstr(VAddr)); uint64_t Offset = Phdr.p_offset + Delta; if (Offset >= getBufSize()) return createError("can't map virtual address 0x" + Twine::utohexstr(VAddr) + " to the segment with index " + Twine(&Phdr - (*ProgramHeadersOrError).data() + 1) + ": the segment ends at 0x" + Twine::utohexstr(Phdr.p_offset + Phdr.p_filesz) + ", which is greater than the file size (0x" + Twine::utohexstr(getBufSize()) + ")"); return base() + Offset; } template Expected> ELFFile::decodeBBAddrMap(const Elf_Shdr &Sec) const { Expected> ContentsOrErr = getSectionContents(Sec); if (!ContentsOrErr) return ContentsOrErr.takeError(); ArrayRef Content = *ContentsOrErr; DataExtractor Data(Content, isLE(), ELFT::Is64Bits ? 8 : 4); std::vector FunctionEntries; DataExtractor::Cursor Cur(0); Error ULEBSizeErr = Error::success(); // Helper to extract and decode the next ULEB128 value as uint32_t. // Returns zero and sets ULEBSizeErr if the ULEB128 value exceeds the uint32_t // limit. // Also returns zero if ULEBSizeErr is already in an error state. auto ReadULEB128AsUInt32 = [&Data, &Cur, &ULEBSizeErr]() -> uint32_t { // Bail out and do not extract data if ULEBSizeErr is already set. if (ULEBSizeErr) return 0; uint64_t Offset = Cur.tell(); uint64_t Value = Data.getULEB128(Cur); if (Value > UINT32_MAX) { ULEBSizeErr = createError( "ULEB128 value at offset 0x" + Twine::utohexstr(Offset) + " exceeds UINT32_MAX (0x" + Twine::utohexstr(Value) + ")"); return 0; } return static_cast(Value); }; while (!ULEBSizeErr && Cur && Cur.tell() < Content.size()) { uintX_t Address = static_cast(Data.getAddress(Cur)); uint32_t NumBlocks = ReadULEB128AsUInt32(); std::vector BBEntries; for (uint32_t BlockID = 0; !ULEBSizeErr && Cur && (BlockID < NumBlocks); ++BlockID) { uint32_t Offset = ReadULEB128AsUInt32(); uint32_t Size = ReadULEB128AsUInt32(); uint32_t Metadata = ReadULEB128AsUInt32(); BBEntries.push_back({Offset, Size, Metadata}); } FunctionEntries.push_back({Address, BBEntries}); } // Either Cur is in the error state, or ULEBSizeError is set (not both), but // we join the two errors here to be safe. if (!Cur || ULEBSizeErr) return joinErrors(Cur.takeError(), std::move(ULEBSizeErr)); return FunctionEntries; } template class llvm::object::ELFFile; template class llvm::object::ELFFile; template class llvm::object::ELFFile; template class llvm::object::ELFFile;