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//===- 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/ADT/StringExtras.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;
case ELF::EM_LOONGARCH:
switch (Type) {
#include "llvm/BinaryFormat/ELFRelocs/LoongArch.def"
default:
break;
}
break;
case ELF::EM_XTENSA:
switch (Type) {
#include "llvm/BinaryFormat/ELFRelocs/Xtensa.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_VE:
return ELF::R_VE_RELATIVE;
case ELF::EM_AMDGPU:
break;
case ELF::EM_BPF:
break;
case ELF::EM_LOONGARCH:
return ELF::R_LARCH_RELATIVE;
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);
STRINGIFY_ENUM_CASE(ELF, SHT_HEXAGON_ATTRIBUTES);
}
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_MSP430:
switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_MSP430_ATTRIBUTES); }
break;
case ELF::EM_RISCV:
switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_RISCV_ATTRIBUTES); }
break;
case ELF::EM_AARCH64:
switch (Type) {
STRINGIFY_ENUM_CASE(ELF, SHT_AARCH64_AUTH_RELR);
STRINGIFY_ENUM_CASE(ELF, SHT_AARCH64_MEMTAG_GLOBALS_DYNAMIC);
STRINGIFY_ENUM_CASE(ELF, SHT_AARCH64_MEMTAG_GLOBALS_STATIC);
}
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_V0);
STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_BB_ADDR_MAP);
STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_OFFLOADING);
STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_LTO);
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>
std::vector<typename ELFT::Rel>
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_Rel Rel;
Rel.r_info = 0;
Rel.setType(getRelativeRelocationType(), false);
std::vector<Elf_Rel> Relocs;
// Word type: uint32_t for Elf32, and uint64_t for Elf64.
using Addr = typename ELFT::uint;
Addr Base = 0;
for (Elf_Relr R : relrs) {
typename ELFT::uint 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 + sizeof(Addr);
} else {
// Odd entry: encodes bitmap for relocations starting at base.
for (Addr Offset = Base; (Entry >>= 1) != 0; Offset += sizeof(Addr))
if ((Entry & 1) != 0) {
Rel.r_offset = Offset;
Relocs.push_back(Rel);
}
Base += (CHAR_BIT * sizeof(Entry) - 1) * sizeof(Addr);
}
}
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();
ArrayRef<uint8_t> 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<Elf_Rela> 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 <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_PPC:
switch (Type) {
#define PPC_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value)
#include "llvm/BinaryFormat/DynamicTags.def"
#undef PPC_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;
case ELF::EM_RISCV:
switch (Type) {
#define RISCV_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value)
#include "llvm/BinaryFormat/DynamicTags.def"
#undef RISCV_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 PPC_DYNAMIC_TAG(name, value)
#define PPC64_DYNAMIC_TAG(name, value)
#define RISCV_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 PPC_DYNAMIC_TAG
#undef PPC64_DYNAMIC_TAG
#undef RISCV_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;
auto ProgramHeadersOrError = program_headers();
if (!ProgramHeadersOrError)
return ProgramHeadersOrError.takeError();
for (const Elf_Phdr &Phdr : *ProgramHeadersOrError) {
if (Phdr.p_type == ELF::PT_DYNAMIC) {
const uint8_t *DynOffset = base() + Phdr.p_offset;
if (DynOffset > end())
return createError(
"dynamic section offset past file size: corrupted ELF");
Dyn = ArrayRef(reinterpret_cast<const Elf_Dyn *>(DynOffset),
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<ArrayRef<Elf_Dyn>> DynOrError =
getSectionContentsAsArray<Elf_Dyn>(Sec);
if (!DynOrError)
return DynOrError.takeError();
Dyn = *DynOrError;
break;
}
}
if (!Dyn.data())
return ArrayRef<Elf_Dyn>();
}
if (Dyn.empty())
return createError("invalid empty dynamic section");
if (Dyn.back().d_tag != ELF::DT_NULL)
return createError("dynamic sections must be DT_NULL terminated");
return Dyn;
}
template <class ELFT>
Expected<const uint8_t *>
ELFFile<ELFT>::toMappedAddr(uint64_t VAddr, WarningHandler WarnHandler) 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));
auto SortPred = [](const Elf_Phdr_Impl<ELFT> *A,
const Elf_Phdr_Impl<ELFT> *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<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));
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;
}
// Helper to extract and decode the next ULEB128 value as unsigned int.
// Returns zero and sets ULEBSizeErr if the ULEB128 value exceeds the unsigned
// int limit.
// Also returns zero if ULEBSizeErr is already in an error state.
// ULEBSizeErr is an out variable if an error occurs.
template <typename IntTy, std::enable_if_t<std::is_unsigned_v<IntTy>, int> = 0>
static IntTy readULEB128As(DataExtractor &Data, DataExtractor::Cursor &Cur,
Error &ULEBSizeErr) {
// 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 > std::numeric_limits<IntTy>::max()) {
ULEBSizeErr = createError("ULEB128 value at offset 0x" +
Twine::utohexstr(Offset) + " exceeds UINT" +
Twine(std::numeric_limits<IntTy>::digits) +
"_MAX (0x" + Twine::utohexstr(Value) + ")");
return 0;
}
return static_cast<IntTy>(Value);
}
template <typename ELFT>
static Expected<std::vector<BBAddrMap>>
decodeBBAddrMapImpl(const ELFFile<ELFT> &EF,
const typename ELFFile<ELFT>::Elf_Shdr &Sec,
const typename ELFFile<ELFT>::Elf_Shdr *RelaSec,
std::vector<PGOAnalysisMap> *PGOAnalyses) {
bool IsRelocatable = EF.getHeader().e_type == ELF::ET_REL;
// This DenseMap maps the offset of each function (the location of the
// reference to the function in the SHT_LLVM_BB_ADDR_MAP section) to the
// addend (the location of the function in the text section).
llvm::DenseMap<uint64_t, uint64_t> FunctionOffsetTranslations;
if (IsRelocatable && RelaSec) {
assert(RelaSec &&
"Can't read a SHT_LLVM_BB_ADDR_MAP section in a relocatable "
"object file without providing a relocation section.");
Expected<typename ELFFile<ELFT>::Elf_Rela_Range> Relas = EF.relas(*RelaSec);
if (!Relas)
return createError("unable to read relocations for section " +
describe(EF, Sec) + ": " +
toString(Relas.takeError()));
for (typename ELFFile<ELFT>::Elf_Rela Rela : *Relas)
FunctionOffsetTranslations[Rela.r_offset] = Rela.r_addend;
}
auto GetAddressForRelocation =
[&](unsigned RelocationOffsetInSection) -> Expected<unsigned> {
auto FOTIterator =
FunctionOffsetTranslations.find(RelocationOffsetInSection);
if (FOTIterator == FunctionOffsetTranslations.end()) {
return createError("failed to get relocation data for offset: " +
Twine::utohexstr(RelocationOffsetInSection) +
" in section " + describe(EF, Sec));
}
return FOTIterator->second;
};
Expected<ArrayRef<uint8_t>> ContentsOrErr = EF.getSectionContents(Sec);
if (!ContentsOrErr)
return ContentsOrErr.takeError();
ArrayRef<uint8_t> Content = *ContentsOrErr;
DataExtractor Data(Content, EF.isLE(), ELFT::Is64Bits ? 8 : 4);
std::vector<BBAddrMap> FunctionEntries;
DataExtractor::Cursor Cur(0);
Error ULEBSizeErr = Error::success();
Error MetadataDecodeErr = Error::success();
// Helper lampda to extract the (possiblly relocatable) address stored at Cur.
auto ExtractAddress = [&]() -> Expected<typename ELFFile<ELFT>::uintX_t> {
uint64_t RelocationOffsetInSection = Cur.tell();
auto Address =
static_cast<typename ELFFile<ELFT>::uintX_t>(Data.getAddress(Cur));
if (!Cur)
return Cur.takeError();
if (!IsRelocatable)
return Address;
assert(Address == 0);
Expected<unsigned> AddressOrErr =
GetAddressForRelocation(RelocationOffsetInSection);
if (!AddressOrErr)
return AddressOrErr.takeError();
return *AddressOrErr;
};
uint8_t Version = 0;
uint8_t Feature = 0;
BBAddrMap::Features FeatEnable{};
while (!ULEBSizeErr && !MetadataDecodeErr && Cur &&
Cur.tell() < Content.size()) {
if (Sec.sh_type == ELF::SHT_LLVM_BB_ADDR_MAP) {
Version = Data.getU8(Cur);
if (!Cur)
break;
if (Version > 2)
return createError("unsupported SHT_LLVM_BB_ADDR_MAP version: " +
Twine(static_cast<int>(Version)));
Feature = Data.getU8(Cur); // Feature byte
if (!Cur)
break;
auto FeatEnableOrErr = BBAddrMap::Features::decode(Feature);
if (!FeatEnableOrErr)
return FeatEnableOrErr.takeError();
FeatEnable = *FeatEnableOrErr;
if (Feature != 0 && Version < 2 && Cur)
return createError(
"version should be >= 2 for SHT_LLVM_BB_ADDR_MAP when "
"PGO features are enabled: version = " +
Twine(static_cast<int>(Version)) +
" feature = " + Twine(static_cast<int>(Feature)));
}
uint32_t NumBlocksInBBRange = 0;
uint32_t NumBBRanges = 1;
typename ELFFile<ELFT>::uintX_t RangeBaseAddress = 0;
std::vector<BBAddrMap::BBEntry> BBEntries;
if (FeatEnable.MultiBBRange) {
NumBBRanges = readULEB128As<uint32_t>(Data, Cur, ULEBSizeErr);
if (!Cur || ULEBSizeErr)
break;
if (!NumBBRanges)
return createError("invalid zero number of BB ranges at offset " +
Twine::utohexstr(Cur.tell()) + " in " +
describe(EF, Sec));
} else {
auto AddressOrErr = ExtractAddress();
if (!AddressOrErr)
return AddressOrErr.takeError();
RangeBaseAddress = *AddressOrErr;
NumBlocksInBBRange = readULEB128As<uint32_t>(Data, Cur, ULEBSizeErr);
}
std::vector<BBAddrMap::BBRangeEntry> BBRangeEntries;
uint32_t TotalNumBlocks = 0;
for (uint32_t BBRangeIndex = 0; BBRangeIndex < NumBBRanges;
++BBRangeIndex) {
uint32_t PrevBBEndOffset = 0;
if (FeatEnable.MultiBBRange) {
auto AddressOrErr = ExtractAddress();
if (!AddressOrErr)
return AddressOrErr.takeError();
RangeBaseAddress = *AddressOrErr;
NumBlocksInBBRange = readULEB128As<uint32_t>(Data, Cur, ULEBSizeErr);
}
for (uint32_t BlockIndex = 0; !MetadataDecodeErr && !ULEBSizeErr && Cur &&
(BlockIndex < NumBlocksInBBRange);
++BlockIndex) {
uint32_t ID = Version >= 2
? readULEB128As<uint32_t>(Data, Cur, ULEBSizeErr)
: BlockIndex;
uint32_t Offset = readULEB128As<uint32_t>(Data, Cur, ULEBSizeErr);
uint32_t Size = readULEB128As<uint32_t>(Data, Cur, ULEBSizeErr);
uint32_t MD = readULEB128As<uint32_t>(Data, Cur, ULEBSizeErr);
if (Version >= 1) {
// Offset is calculated relative to the end of the previous BB.
Offset += PrevBBEndOffset;
PrevBBEndOffset = Offset + Size;
}
Expected<BBAddrMap::BBEntry::Metadata> MetadataOrErr =
BBAddrMap::BBEntry::Metadata::decode(MD);
if (!MetadataOrErr) {
MetadataDecodeErr = MetadataOrErr.takeError();
break;
}
BBEntries.push_back({ID, Offset, Size, *MetadataOrErr});
}
TotalNumBlocks += BBEntries.size();
BBRangeEntries.push_back({RangeBaseAddress, std::move(BBEntries)});
}
FunctionEntries.push_back({std::move(BBRangeEntries)});
if (PGOAnalyses || FeatEnable.hasPGOAnalysis()) {
// Function entry count
uint64_t FuncEntryCount =
FeatEnable.FuncEntryCount
? readULEB128As<uint64_t>(Data, Cur, ULEBSizeErr)
: 0;
std::vector<PGOAnalysisMap::PGOBBEntry> PGOBBEntries;
for (uint32_t BlockIndex = 0;
FeatEnable.hasPGOAnalysisBBData() && !MetadataDecodeErr &&
!ULEBSizeErr && Cur && (BlockIndex < TotalNumBlocks);
++BlockIndex) {
// Block frequency
uint64_t BBF = FeatEnable.BBFreq
? readULEB128As<uint64_t>(Data, Cur, ULEBSizeErr)
: 0;
// Branch probability
llvm::SmallVector<PGOAnalysisMap::PGOBBEntry::SuccessorEntry, 2>
Successors;
if (FeatEnable.BrProb) {
auto SuccCount = readULEB128As<uint64_t>(Data, Cur, ULEBSizeErr);
for (uint64_t I = 0; I < SuccCount; ++I) {
uint32_t BBID = readULEB128As<uint32_t>(Data, Cur, ULEBSizeErr);
uint32_t BrProb = readULEB128As<uint32_t>(Data, Cur, ULEBSizeErr);
if (PGOAnalyses)
Successors.push_back({BBID, BranchProbability::getRaw(BrProb)});
}
}
if (PGOAnalyses)
PGOBBEntries.push_back({BlockFrequency(BBF), std::move(Successors)});
}
if (PGOAnalyses)
PGOAnalyses->push_back(
{FuncEntryCount, std::move(PGOBBEntries), FeatEnable});
}
}
// Either Cur is in the error state, or we have an error in ULEBSizeErr or
// MetadataDecodeErr (but not both), but we join all errors here to be safe.
if (!Cur || ULEBSizeErr || MetadataDecodeErr)
return joinErrors(joinErrors(Cur.takeError(), std::move(ULEBSizeErr)),
std::move(MetadataDecodeErr));
return FunctionEntries;
}
template <class ELFT>
Expected<std::vector<BBAddrMap>>
ELFFile<ELFT>::decodeBBAddrMap(const Elf_Shdr &Sec, const Elf_Shdr *RelaSec,
std::vector<PGOAnalysisMap> *PGOAnalyses) const {
size_t OriginalPGOSize = PGOAnalyses ? PGOAnalyses->size() : 0;
auto AddrMapsOrErr = decodeBBAddrMapImpl(*this, Sec, RelaSec, PGOAnalyses);
// remove new analyses when an error occurs
if (!AddrMapsOrErr && PGOAnalyses)
PGOAnalyses->resize(OriginalPGOSize);
return std::move(AddrMapsOrErr);
}
template <class ELFT>
Expected<
MapVector<const typename ELFT::Shdr *, const typename ELFT::Shdr *>>
ELFFile<ELFT>::getSectionAndRelocations(
std::function<Expected<bool>(const Elf_Shdr &)> IsMatch) const {
MapVector<const Elf_Shdr *, const Elf_Shdr *> SecToRelocMap;
Error Errors = Error::success();
for (const Elf_Shdr &Sec : cantFail(this->sections())) {
Expected<bool> DoesSectionMatch = IsMatch(Sec);
if (!DoesSectionMatch) {
Errors = joinErrors(std::move(Errors), DoesSectionMatch.takeError());
continue;
}
if (*DoesSectionMatch) {
if (SecToRelocMap.insert(std::make_pair(&Sec, (const Elf_Shdr *)nullptr))
.second)
continue;
}
if (Sec.sh_type != ELF::SHT_RELA && Sec.sh_type != ELF::SHT_REL)
continue;
Expected<const Elf_Shdr *> RelSecOrErr = this->getSection(Sec.sh_info);
if (!RelSecOrErr) {
Errors = joinErrors(std::move(Errors),
createError(describe(*this, Sec) +
": failed to get a relocated section: " +
toString(RelSecOrErr.takeError())));
continue;
}
const Elf_Shdr *ContentsSec = *RelSecOrErr;
Expected<bool> DoesRelTargetMatch = IsMatch(*ContentsSec);
if (!DoesRelTargetMatch) {
Errors = joinErrors(std::move(Errors), DoesRelTargetMatch.takeError());
continue;
}
if (*DoesRelTargetMatch)
SecToRelocMap[ContentsSec] = &Sec;
}
if(Errors)
return std::move(Errors);
return SecToRelocMap;
}
template class llvm::object::ELFFile<ELF32LE>;
template class llvm::object::ELFFile<ELF32BE>;
template class llvm::object::ELFFile<ELF64LE>;
template class llvm::object::ELFFile<ELF64BE>;