diff options
Diffstat (limited to 'llvm/lib/Object/ELF.cpp')
| -rw-r--r-- | llvm/lib/Object/ELF.cpp | 589 |
1 files changed, 589 insertions, 0 deletions
diff --git a/llvm/lib/Object/ELF.cpp b/llvm/lib/Object/ELF.cpp new file mode 100644 index 0000000000000..d491288579df6 --- /dev/null +++ b/llvm/lib/Object/ELF.cpp @@ -0,0 +1,589 @@ +//===- 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/LEB128.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_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; + 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_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; + 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_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 <class ELFT> +Expected<std::vector<typename ELFT::Rela>> +ELFFile<ELFT>::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_Rela Rela; + Rela.r_info = 0; + Rela.r_addend = 0; + Rela.setType(getRelativeRelocationType(), false); + std::vector<Elf_Rela> 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. + Rela.r_offset = Entry; + Relocs.push_back(Rela); + // 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) { + Rela.r_offset = Offset; + Relocs.push_back(Rela); + } + Offset += WordSize; + } + + // Advance base offset by NBits words. + Base += NBits * WordSize; + } + + return Relocs; +} + +template <class ELFT> +Expected<std::vector<typename ELFT::Rela>> +ELFFile<ELFT>::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<ArrayRef<uint8_t>> ContentsOrErr = getSectionContents(Sec); + if (!ContentsOrErr) + return ContentsOrErr.takeError(); + const uint8_t *Cur = ContentsOrErr->begin(); + const uint8_t *End = ContentsOrErr->end(); + if (ContentsOrErr->size() < 4 || Cur[0] != 'A' || Cur[1] != 'P' || + Cur[2] != 'S' || Cur[3] != '2') + return createError("invalid packed relocation header"); + Cur += 4; + + const char *ErrStr = nullptr; + auto ReadSLEB = [&]() -> int64_t { + if (ErrStr) + return 0; + unsigned Len; + int64_t Result = decodeSLEB128(Cur, &Len, End, &ErrStr); + Cur += Len; + return Result; + }; + + uint64_t NumRelocs = ReadSLEB(); + uint64_t Offset = ReadSLEB(); + uint64_t Addend = 0; + + if (ErrStr) + return createError(ErrStr); + + std::vector<Elf_Rela> Relocs; + Relocs.reserve(NumRelocs); + while (NumRelocs) { + uint64_t NumRelocsInGroup = ReadSLEB(); + if (NumRelocsInGroup > NumRelocs) + return createError("relocation group unexpectedly large"); + NumRelocs -= NumRelocsInGroup; + + uint64_t GroupFlags = ReadSLEB(); + 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 = ReadSLEB(); + + uint64_t GroupRInfo; + if (GroupedByInfo) + GroupRInfo = ReadSLEB(); + + if (GroupedByAddend && GroupHasAddend) + Addend += ReadSLEB(); + + if (!GroupHasAddend) + Addend = 0; + + for (uint64_t I = 0; I != NumRelocsInGroup; ++I) { + Elf_Rela R; + Offset += GroupedByOffsetDelta ? GroupOffsetDelta : ReadSLEB(); + R.r_offset = Offset; + R.r_info = GroupedByInfo ? GroupRInfo : ReadSLEB(); + if (GroupHasAddend && !GroupedByAddend) + Addend += ReadSLEB(); + R.r_addend = Addend; + Relocs.push_back(R); + + if (ErrStr) + return createError(ErrStr); + } + + if (ErrStr) + return createError(ErrStr); + } + + return Relocs; +} + +template <class ELFT> +std::string ELFFile<ELFT>::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) DYNAMIC_STRINGIFY_ENUM(name, value) +#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 "<unknown:>0x" + utohexstr(Type, true); + } +} + +template <class ELFT> +std::string ELFFile<ELFT>::getDynamicTagAsString(uint64_t Type) const { + return getDynamicTagAsString(getHeader()->e_machine, Type); +} + +template <class ELFT> +Expected<typename ELFT::DynRange> ELFFile<ELFT>::dynamicEntries() const { + ArrayRef<Elf_Dyn> Dyn; + size_t DynSecSize = 0; + + 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<const Elf_Dyn *>(base() + Phdr.p_offset), + Phdr.p_filesz / sizeof(Elf_Dyn)); + DynSecSize = Phdr.p_filesz; + 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<ArrayRef<Elf_Dyn>> DynOrError = + getSectionContentsAsArray<Elf_Dyn>(&Sec); + if (!DynOrError) + return DynOrError.takeError(); + Dyn = *DynOrError; + DynSecSize = Sec.sh_size; + break; + } + } + + if (!Dyn.data()) + return ArrayRef<Elf_Dyn>(); + } + + if (Dyn.empty()) + // TODO: this error is untested. + return createError("invalid empty dynamic section"); + + if (DynSecSize % sizeof(Elf_Dyn) != 0) + // TODO: this error is untested. + return createError("malformed 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 <class ELFT> +Expected<const uint8_t *> ELFFile<ELFT>::toMappedAddr(uint64_t VAddr) const { + auto ProgramHeadersOrError = program_headers(); + if (!ProgramHeadersOrError) + return ProgramHeadersOrError.takeError(); + + llvm::SmallVector<Elf_Phdr *, 4> LoadSegments; + + for (const Elf_Phdr &Phdr : *ProgramHeadersOrError) + if (Phdr.p_type == ELF::PT_LOAD) + LoadSegments.push_back(const_cast<Elf_Phdr *>(&Phdr)); + + const Elf_Phdr *const *I = + std::upper_bound(LoadSegments.begin(), LoadSegments.end(), VAddr, + [](uint64_t VAddr, const Elf_Phdr_Impl<ELFT> *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)); + return base() + Phdr.p_offset + Delta; +} + +template class llvm::object::ELFFile<ELF32LE>; +template class llvm::object::ELFFile<ELF32BE>; +template class llvm::object::ELFFile<ELF64LE>; +template class llvm::object::ELFFile<ELF64BE>; |