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llvm-mirror/lib/ObjectYAML/ELFEmitter.cpp
Alexander Yermolovich d12ae1eaf8 [LLD][LLVM] CG Graph profile using relocations 
Currently when .llvm.call-graph-profile is created by llvm it explicitly encodes the symbol indices. This section is basically a black box for post processing tools. For example, if we run strip -s on the object files the symbol table changes, but indices in that section do not. In non-visible behavior indices point to wrong symbols. The visible behavior indices point outside of Symbol table: "invalid symbol index".

This patch changes the format by using R_*_NONE relocations to indicate the from/to symbols. The Frequency (Weight) will still be in the .llvm.call-graph-profile, but symbol information will be in relocation section. In LLD information from both sections is used to reconstruct call graph profile. Relocations themselves will never be applied.

With this approach post processing tools that handle relocations correctly work for this section also. Tools can add/remove symbols and as long as they handle relocation sections with this approach information stays correct.

Doing a quick experiment with clang-13.
The size went up from 107KB to 322KB, aggregate of all the input sections. Size of clang-13 binary is ~118MB. For users of -fprofile-use/-fprofile-sample-use the size of object files will go up slightly, it will not impact final binary size.

Reviewed By: jhenderson, MaskRay

Differential Revision: https://reviews.llvm.org/D104080
2021-06-24 09:09:33 -07:00

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//===- yaml2elf - Convert YAML to a ELF object file -----------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// The ELF component of yaml2obj.
///
//===----------------------------------------------------------------------===//
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/StringSet.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/MC/StringTableBuilder.h"
#include "llvm/Object/ELFObjectFile.h"
#include "llvm/Object/ELFTypes.h"
#include "llvm/ObjectYAML/DWARFEmitter.h"
#include "llvm/ObjectYAML/DWARFYAML.h"
#include "llvm/ObjectYAML/ELFYAML.h"
#include "llvm/ObjectYAML/yaml2obj.h"
#include "llvm/Support/EndianStream.h"
#include "llvm/Support/Errc.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/LEB128.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/WithColor.h"
#include "llvm/Support/YAMLTraits.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
// This class is used to build up a contiguous binary blob while keeping
// track of an offset in the output (which notionally begins at
// `InitialOffset`).
// The blob might be limited to an arbitrary size. All attempts to write data
// are ignored and the error condition is remembered once the limit is reached.
// Such an approach allows us to simplify the code by delaying error reporting
// and doing it at a convenient time.
namespace {
class ContiguousBlobAccumulator {
const uint64_t InitialOffset;
const uint64_t MaxSize;
SmallVector<char, 128> Buf;
raw_svector_ostream OS;
Error ReachedLimitErr = Error::success();
bool checkLimit(uint64_t Size) {
if (!ReachedLimitErr && getOffset() + Size <= MaxSize)
return true;
if (!ReachedLimitErr)
ReachedLimitErr = createStringError(errc::invalid_argument,
"reached the output size limit");
return false;
}
public:
ContiguousBlobAccumulator(uint64_t BaseOffset, uint64_t SizeLimit)
: InitialOffset(BaseOffset), MaxSize(SizeLimit), OS(Buf) {}
uint64_t tell() const { return OS.tell(); }
uint64_t getOffset() const { return InitialOffset + OS.tell(); }
void writeBlobToStream(raw_ostream &Out) const { Out << OS.str(); }
Error takeLimitError() {
// Request to write 0 bytes to check we did not reach the limit.
checkLimit(0);
return std::move(ReachedLimitErr);
}
/// \returns The new offset.
uint64_t padToAlignment(unsigned Align) {
uint64_t CurrentOffset = getOffset();
if (ReachedLimitErr)
return CurrentOffset;
uint64_t AlignedOffset = alignTo(CurrentOffset, Align == 0 ? 1 : Align);
uint64_t PaddingSize = AlignedOffset - CurrentOffset;
if (!checkLimit(PaddingSize))
return CurrentOffset;
writeZeros(PaddingSize);
return AlignedOffset;
}
raw_ostream *getRawOS(uint64_t Size) {
if (checkLimit(Size))
return &OS;
return nullptr;
}
void writeAsBinary(const yaml::BinaryRef &Bin, uint64_t N = UINT64_MAX) {
if (!checkLimit(Bin.binary_size()))
return;
Bin.writeAsBinary(OS, N);
}
void writeZeros(uint64_t Num) {
if (checkLimit(Num))
OS.write_zeros(Num);
}
void write(const char *Ptr, size_t Size) {
if (checkLimit(Size))
OS.write(Ptr, Size);
}
void write(unsigned char C) {
if (checkLimit(1))
OS.write(C);
}
unsigned writeULEB128(uint64_t Val) {
if (!checkLimit(sizeof(uint64_t)))
return 0;
return encodeULEB128(Val, OS);
}
template <typename T> void write(T Val, support::endianness E) {
if (checkLimit(sizeof(T)))
support::endian::write<T>(OS, Val, E);
}
void updateDataAt(uint64_t Pos, void *Data, size_t Size) {
assert(Pos >= InitialOffset && Pos + Size <= getOffset());
memcpy(&Buf[Pos - InitialOffset], Data, Size);
}
};
// Used to keep track of section and symbol names, so that in the YAML file
// sections and symbols can be referenced by name instead of by index.
class NameToIdxMap {
StringMap<unsigned> Map;
public:
/// \Returns false if name is already present in the map.
bool addName(StringRef Name, unsigned Ndx) {
return Map.insert({Name, Ndx}).second;
}
/// \Returns false if name is not present in the map.
bool lookup(StringRef Name, unsigned &Idx) const {
auto I = Map.find(Name);
if (I == Map.end())
return false;
Idx = I->getValue();
return true;
}
/// Asserts if name is not present in the map.
unsigned get(StringRef Name) const {
unsigned Idx;
if (lookup(Name, Idx))
return Idx;
assert(false && "Expected section not found in index");
return 0;
}
unsigned size() const { return Map.size(); }
};
namespace {
struct Fragment {
uint64_t Offset;
uint64_t Size;
uint32_t Type;
uint64_t AddrAlign;
};
} // namespace
/// "Single point of truth" for the ELF file construction.
/// TODO: This class still has a ways to go before it is truly a "single
/// point of truth".
template <class ELFT> class ELFState {
LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
enum class SymtabType { Static, Dynamic };
/// The future symbol table string section.
StringTableBuilder DotStrtab{StringTableBuilder::ELF};
/// The future section header string table section, if a unique string table
/// is needed. Don't reference this variable direectly: use the
/// ShStrtabStrings member instead.
StringTableBuilder DotShStrtab{StringTableBuilder::ELF};
/// The future dynamic symbol string section.
StringTableBuilder DotDynstr{StringTableBuilder::ELF};
/// The name of the section header string table section. If it is .strtab or
/// .dynstr, the section header strings will be written to the same string
/// table as the static/dynamic symbols respectively. Otherwise a dedicated
/// section will be created with that name.
StringRef SectionHeaderStringTableName = ".shstrtab";
StringTableBuilder *ShStrtabStrings = &DotShStrtab;
NameToIdxMap SN2I;
NameToIdxMap SymN2I;
NameToIdxMap DynSymN2I;
ELFYAML::Object &Doc;
StringSet<> ExcludedSectionHeaders;
uint64_t LocationCounter = 0;
bool HasError = false;
yaml::ErrorHandler ErrHandler;
void reportError(const Twine &Msg);
void reportError(Error Err);
std::vector<Elf_Sym> toELFSymbols(ArrayRef<ELFYAML::Symbol> Symbols,
const StringTableBuilder &Strtab);
unsigned toSectionIndex(StringRef S, StringRef LocSec, StringRef LocSym = "");
unsigned toSymbolIndex(StringRef S, StringRef LocSec, bool IsDynamic);
void buildSectionIndex();
void buildSymbolIndexes();
void initProgramHeaders(std::vector<Elf_Phdr> &PHeaders);
bool initImplicitHeader(ContiguousBlobAccumulator &CBA, Elf_Shdr &Header,
StringRef SecName, ELFYAML::Section *YAMLSec);
void initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
ContiguousBlobAccumulator &CBA);
void initSymtabSectionHeader(Elf_Shdr &SHeader, SymtabType STType,
ContiguousBlobAccumulator &CBA,
ELFYAML::Section *YAMLSec);
void initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
StringTableBuilder &STB,
ContiguousBlobAccumulator &CBA,
ELFYAML::Section *YAMLSec);
void initDWARFSectionHeader(Elf_Shdr &SHeader, StringRef Name,
ContiguousBlobAccumulator &CBA,
ELFYAML::Section *YAMLSec);
void setProgramHeaderLayout(std::vector<Elf_Phdr> &PHeaders,
std::vector<Elf_Shdr> &SHeaders);
std::vector<Fragment>
getPhdrFragments(const ELFYAML::ProgramHeader &Phdr,
ArrayRef<typename ELFT::Shdr> SHeaders);
void finalizeStrings();
void writeELFHeader(raw_ostream &OS);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::NoBitsSection &Section,
ContiguousBlobAccumulator &CBA);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::RawContentSection &Section,
ContiguousBlobAccumulator &CBA);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::RelocationSection &Section,
ContiguousBlobAccumulator &CBA);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::RelrSection &Section,
ContiguousBlobAccumulator &CBA);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::GroupSection &Group,
ContiguousBlobAccumulator &CBA);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::SymtabShndxSection &Shndx,
ContiguousBlobAccumulator &CBA);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::SymverSection &Section,
ContiguousBlobAccumulator &CBA);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::VerneedSection &Section,
ContiguousBlobAccumulator &CBA);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::VerdefSection &Section,
ContiguousBlobAccumulator &CBA);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::ARMIndexTableSection &Section,
ContiguousBlobAccumulator &CBA);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::MipsABIFlags &Section,
ContiguousBlobAccumulator &CBA);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::DynamicSection &Section,
ContiguousBlobAccumulator &CBA);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::StackSizesSection &Section,
ContiguousBlobAccumulator &CBA);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::BBAddrMapSection &Section,
ContiguousBlobAccumulator &CBA);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::HashSection &Section,
ContiguousBlobAccumulator &CBA);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::AddrsigSection &Section,
ContiguousBlobAccumulator &CBA);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::NoteSection &Section,
ContiguousBlobAccumulator &CBA);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::GnuHashSection &Section,
ContiguousBlobAccumulator &CBA);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::LinkerOptionsSection &Section,
ContiguousBlobAccumulator &CBA);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::DependentLibrariesSection &Section,
ContiguousBlobAccumulator &CBA);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::CallGraphProfileSection &Section,
ContiguousBlobAccumulator &CBA);
void writeFill(ELFYAML::Fill &Fill, ContiguousBlobAccumulator &CBA);
ELFState(ELFYAML::Object &D, yaml::ErrorHandler EH);
void assignSectionAddress(Elf_Shdr &SHeader, ELFYAML::Section *YAMLSec);
DenseMap<StringRef, size_t> buildSectionHeaderReorderMap();
BumpPtrAllocator StringAlloc;
uint64_t alignToOffset(ContiguousBlobAccumulator &CBA, uint64_t Align,
llvm::Optional<llvm::yaml::Hex64> Offset);
uint64_t getSectionNameOffset(StringRef Name);
public:
static bool writeELF(raw_ostream &OS, ELFYAML::Object &Doc,
yaml::ErrorHandler EH, uint64_t MaxSize);
};
} // end anonymous namespace
template <class T> static size_t arrayDataSize(ArrayRef<T> A) {
return A.size() * sizeof(T);
}
template <class T> static void writeArrayData(raw_ostream &OS, ArrayRef<T> A) {
OS.write((const char *)A.data(), arrayDataSize(A));
}
template <class T> static void zero(T &Obj) { memset(&Obj, 0, sizeof(Obj)); }
template <class ELFT>
ELFState<ELFT>::ELFState(ELFYAML::Object &D, yaml::ErrorHandler EH)
: Doc(D), ErrHandler(EH) {
// The input may explicitly request to store the section header table strings
// in the same string table as dynamic or static symbol names. Set the
// ShStrtabStrings member accordingly.
if (Doc.Header.SectionHeaderStringTable) {
SectionHeaderStringTableName = *Doc.Header.SectionHeaderStringTable;
if (*Doc.Header.SectionHeaderStringTable == ".strtab")
ShStrtabStrings = &DotStrtab;
else if (*Doc.Header.SectionHeaderStringTable == ".dynstr")
ShStrtabStrings = &DotDynstr;
// Otherwise, the unique table will be used.
}
std::vector<ELFYAML::Section *> Sections = Doc.getSections();
// Insert SHT_NULL section implicitly when it is not defined in YAML.
if (Sections.empty() || Sections.front()->Type != ELF::SHT_NULL)
Doc.Chunks.insert(
Doc.Chunks.begin(),
std::make_unique<ELFYAML::Section>(
ELFYAML::Chunk::ChunkKind::RawContent, /*IsImplicit=*/true));
StringSet<> DocSections;
ELFYAML::SectionHeaderTable *SecHdrTable = nullptr;
for (size_t I = 0; I < Doc.Chunks.size(); ++I) {
const std::unique_ptr<ELFYAML::Chunk> &C = Doc.Chunks[I];
// We might have an explicit section header table declaration.
if (auto S = dyn_cast<ELFYAML::SectionHeaderTable>(C.get())) {
if (SecHdrTable)
reportError("multiple section header tables are not allowed");
SecHdrTable = S;
continue;
}
// We add a technical suffix for each unnamed section/fill. It does not
// affect the output, but allows us to map them by name in the code and
// report better error messages.
if (C->Name.empty()) {
std::string NewName = ELFYAML::appendUniqueSuffix(
/*Name=*/"", "index " + Twine(I));
C->Name = StringRef(NewName).copy(StringAlloc);
assert(ELFYAML::dropUniqueSuffix(C->Name).empty());
}
if (!DocSections.insert(C->Name).second)
reportError("repeated section/fill name: '" + C->Name +
"' at YAML section/fill number " + Twine(I));
}
SmallSetVector<StringRef, 8> ImplicitSections;
if (Doc.DynamicSymbols) {
if (SectionHeaderStringTableName == ".dynsym")
reportError("cannot use '.dynsym' as the section header name table when "
"there are dynamic symbols");
ImplicitSections.insert(".dynsym");
ImplicitSections.insert(".dynstr");
}
if (Doc.Symbols) {
if (SectionHeaderStringTableName == ".symtab")
reportError("cannot use '.symtab' as the section header name table when "
"there are symbols");
ImplicitSections.insert(".symtab");
}
if (Doc.DWARF)
for (StringRef DebugSecName : Doc.DWARF->getNonEmptySectionNames()) {
std::string SecName = ("." + DebugSecName).str();
// TODO: For .debug_str it should be possible to share the string table,
// in the same manner as the symbol string tables.
if (SectionHeaderStringTableName == SecName)
reportError("cannot use '" + SecName +
"' as the section header name table when it is needed for "
"DWARF output");
ImplicitSections.insert(StringRef(SecName).copy(StringAlloc));
}
// TODO: Only create the .strtab here if any symbols have been requested.
ImplicitSections.insert(".strtab");
if (!SecHdrTable || !SecHdrTable->NoHeaders.getValueOr(false))
ImplicitSections.insert(SectionHeaderStringTableName);
// Insert placeholders for implicit sections that are not
// defined explicitly in YAML.
for (StringRef SecName : ImplicitSections) {
if (DocSections.count(SecName))
continue;
std::unique_ptr<ELFYAML::Section> Sec = std::make_unique<ELFYAML::Section>(
ELFYAML::Chunk::ChunkKind::RawContent, true /*IsImplicit*/);
Sec->Name = SecName;
if (SecName == SectionHeaderStringTableName)
Sec->Type = ELF::SHT_STRTAB;
else if (SecName == ".dynsym")
Sec->Type = ELF::SHT_DYNSYM;
else if (SecName == ".symtab")
Sec->Type = ELF::SHT_SYMTAB;
else
Sec->Type = ELF::SHT_STRTAB;
// When the section header table is explicitly defined at the end of the
// sections list, it is reasonable to assume that the user wants to reorder
// section headers, but still wants to place the section header table after
// all sections, like it normally happens. In this case we want to insert
// other implicit sections right before the section header table.
if (Doc.Chunks.back().get() == SecHdrTable)
Doc.Chunks.insert(Doc.Chunks.end() - 1, std::move(Sec));
else
Doc.Chunks.push_back(std::move(Sec));
}
// Insert the section header table implicitly at the end, when it is not
// explicitly defined.
if (!SecHdrTable)
Doc.Chunks.push_back(
std::make_unique<ELFYAML::SectionHeaderTable>(/*IsImplicit=*/true));
}
template <class ELFT>
void ELFState<ELFT>::writeELFHeader(raw_ostream &OS) {
using namespace llvm::ELF;
Elf_Ehdr Header;
zero(Header);
Header.e_ident[EI_MAG0] = 0x7f;
Header.e_ident[EI_MAG1] = 'E';
Header.e_ident[EI_MAG2] = 'L';
Header.e_ident[EI_MAG3] = 'F';
Header.e_ident[EI_CLASS] = ELFT::Is64Bits ? ELFCLASS64 : ELFCLASS32;
Header.e_ident[EI_DATA] = Doc.Header.Data;
Header.e_ident[EI_VERSION] = EV_CURRENT;
Header.e_ident[EI_OSABI] = Doc.Header.OSABI;
Header.e_ident[EI_ABIVERSION] = Doc.Header.ABIVersion;
Header.e_type = Doc.Header.Type;
if (Doc.Header.Machine)
Header.e_machine = *Doc.Header.Machine;
else
Header.e_machine = EM_NONE;
Header.e_version = EV_CURRENT;
Header.e_entry = Doc.Header.Entry;
Header.e_flags = Doc.Header.Flags;
Header.e_ehsize = sizeof(Elf_Ehdr);
if (Doc.Header.EPhOff)
Header.e_phoff = *Doc.Header.EPhOff;
else if (!Doc.ProgramHeaders.empty())
Header.e_phoff = sizeof(Header);
else
Header.e_phoff = 0;
if (Doc.Header.EPhEntSize)
Header.e_phentsize = *Doc.Header.EPhEntSize;
else if (!Doc.ProgramHeaders.empty())
Header.e_phentsize = sizeof(Elf_Phdr);
else
Header.e_phentsize = 0;
if (Doc.Header.EPhNum)
Header.e_phnum = *Doc.Header.EPhNum;
else if (!Doc.ProgramHeaders.empty())
Header.e_phnum = Doc.ProgramHeaders.size();
else
Header.e_phnum = 0;
Header.e_shentsize = Doc.Header.EShEntSize ? (uint16_t)*Doc.Header.EShEntSize
: sizeof(Elf_Shdr);
const ELFYAML::SectionHeaderTable &SectionHeaders =
Doc.getSectionHeaderTable();
if (Doc.Header.EShOff)
Header.e_shoff = *Doc.Header.EShOff;
else if (SectionHeaders.Offset)
Header.e_shoff = *SectionHeaders.Offset;
else
Header.e_shoff = 0;
if (Doc.Header.EShNum)
Header.e_shnum = *Doc.Header.EShNum;
else
Header.e_shnum = SectionHeaders.getNumHeaders(Doc.getSections().size());
if (Doc.Header.EShStrNdx)
Header.e_shstrndx = *Doc.Header.EShStrNdx;
else if (SectionHeaders.Offset &&
!ExcludedSectionHeaders.count(SectionHeaderStringTableName))
Header.e_shstrndx = SN2I.get(SectionHeaderStringTableName);
else
Header.e_shstrndx = 0;
OS.write((const char *)&Header, sizeof(Header));
}
template <class ELFT>
void ELFState<ELFT>::initProgramHeaders(std::vector<Elf_Phdr> &PHeaders) {
DenseMap<StringRef, ELFYAML::Fill *> NameToFill;
DenseMap<StringRef, size_t> NameToIndex;
for (size_t I = 0, E = Doc.Chunks.size(); I != E; ++I) {
if (auto S = dyn_cast<ELFYAML::Fill>(Doc.Chunks[I].get()))
NameToFill[S->Name] = S;
NameToIndex[Doc.Chunks[I]->Name] = I + 1;
}
std::vector<ELFYAML::Section *> Sections = Doc.getSections();
for (size_t I = 0, E = Doc.ProgramHeaders.size(); I != E; ++I) {
ELFYAML::ProgramHeader &YamlPhdr = Doc.ProgramHeaders[I];
Elf_Phdr Phdr;
zero(Phdr);
Phdr.p_type = YamlPhdr.Type;
Phdr.p_flags = YamlPhdr.Flags;
Phdr.p_vaddr = YamlPhdr.VAddr;
Phdr.p_paddr = YamlPhdr.PAddr;
PHeaders.push_back(Phdr);
if (!YamlPhdr.FirstSec && !YamlPhdr.LastSec)
continue;
// Get the index of the section, or 0 in the case when the section doesn't exist.
size_t First = NameToIndex[*YamlPhdr.FirstSec];
if (!First)
reportError("unknown section or fill referenced: '" + *YamlPhdr.FirstSec +
"' by the 'FirstSec' key of the program header with index " +
Twine(I));
size_t Last = NameToIndex[*YamlPhdr.LastSec];
if (!Last)
reportError("unknown section or fill referenced: '" + *YamlPhdr.LastSec +
"' by the 'LastSec' key of the program header with index " +
Twine(I));
if (!First || !Last)
continue;
if (First > Last)
reportError("program header with index " + Twine(I) +
": the section index of " + *YamlPhdr.FirstSec +
" is greater than the index of " + *YamlPhdr.LastSec);
for (size_t I = First; I <= Last; ++I)
YamlPhdr.Chunks.push_back(Doc.Chunks[I - 1].get());
}
}
template <class ELFT>
unsigned ELFState<ELFT>::toSectionIndex(StringRef S, StringRef LocSec,
StringRef LocSym) {
assert(LocSec.empty() || LocSym.empty());
unsigned Index;
if (!SN2I.lookup(S, Index) && !to_integer(S, Index)) {
if (!LocSym.empty())
reportError("unknown section referenced: '" + S + "' by YAML symbol '" +
LocSym + "'");
else
reportError("unknown section referenced: '" + S + "' by YAML section '" +
LocSec + "'");
return 0;
}
const ELFYAML::SectionHeaderTable &SectionHeaders =
Doc.getSectionHeaderTable();
if (SectionHeaders.IsImplicit ||
(SectionHeaders.NoHeaders && !SectionHeaders.NoHeaders.getValue()) ||
SectionHeaders.isDefault())
return Index;
assert(!SectionHeaders.NoHeaders.getValueOr(false) ||
!SectionHeaders.Sections);
size_t FirstExcluded =
SectionHeaders.Sections ? SectionHeaders.Sections->size() : 0;
if (Index > FirstExcluded) {
if (LocSym.empty())
reportError("unable to link '" + LocSec + "' to excluded section '" + S +
"'");
else
reportError("excluded section referenced: '" + S + "' by symbol '" +
LocSym + "'");
}
return Index;
}
template <class ELFT>
unsigned ELFState<ELFT>::toSymbolIndex(StringRef S, StringRef LocSec,
bool IsDynamic) {
const NameToIdxMap &SymMap = IsDynamic ? DynSymN2I : SymN2I;
unsigned Index;
// Here we try to look up S in the symbol table. If it is not there,
// treat its value as a symbol index.
if (!SymMap.lookup(S, Index) && !to_integer(S, Index)) {
reportError("unknown symbol referenced: '" + S + "' by YAML section '" +
LocSec + "'");
return 0;
}
return Index;
}
template <class ELFT>
static void overrideFields(ELFYAML::Section *From, typename ELFT::Shdr &To) {
if (!From)
return;
if (From->ShAddrAlign)
To.sh_addralign = *From->ShAddrAlign;
if (From->ShFlags)
To.sh_flags = *From->ShFlags;
if (From->ShName)
To.sh_name = *From->ShName;
if (From->ShOffset)
To.sh_offset = *From->ShOffset;
if (From->ShSize)
To.sh_size = *From->ShSize;
if (From->ShType)
To.sh_type = *From->ShType;
}
template <class ELFT>
bool ELFState<ELFT>::initImplicitHeader(ContiguousBlobAccumulator &CBA,
Elf_Shdr &Header, StringRef SecName,
ELFYAML::Section *YAMLSec) {
// Check if the header was already initialized.
if (Header.sh_offset)
return false;
if (SecName == ".strtab")
initStrtabSectionHeader(Header, SecName, DotStrtab, CBA, YAMLSec);
else if (SecName == ".dynstr")
initStrtabSectionHeader(Header, SecName, DotDynstr, CBA, YAMLSec);
else if (SecName == SectionHeaderStringTableName)
initStrtabSectionHeader(Header, SecName, *ShStrtabStrings, CBA, YAMLSec);
else if (SecName == ".symtab")
initSymtabSectionHeader(Header, SymtabType::Static, CBA, YAMLSec);
else if (SecName == ".dynsym")
initSymtabSectionHeader(Header, SymtabType::Dynamic, CBA, YAMLSec);
else if (SecName.startswith(".debug_")) {
// If a ".debug_*" section's type is a preserved one, e.g., SHT_DYNAMIC, we
// will not treat it as a debug section.
if (YAMLSec && !isa<ELFYAML::RawContentSection>(YAMLSec))
return false;
initDWARFSectionHeader(Header, SecName, CBA, YAMLSec);
} else
return false;
LocationCounter += Header.sh_size;
// Override section fields if requested.
overrideFields<ELFT>(YAMLSec, Header);
return true;
}
constexpr char SuffixStart = '(';
constexpr char SuffixEnd = ')';
std::string llvm::ELFYAML::appendUniqueSuffix(StringRef Name,
const Twine &Msg) {
// Do not add a space when a Name is empty.
std::string Ret = Name.empty() ? "" : Name.str() + ' ';
return Ret + (Twine(SuffixStart) + Msg + Twine(SuffixEnd)).str();
}
StringRef llvm::ELFYAML::dropUniqueSuffix(StringRef S) {
if (S.empty() || S.back() != SuffixEnd)
return S;
// A special case for empty names. See appendUniqueSuffix() above.
size_t SuffixPos = S.rfind(SuffixStart);
if (SuffixPos == 0)
return "";
if (SuffixPos == StringRef::npos || S[SuffixPos - 1] != ' ')
return S;
return S.substr(0, SuffixPos - 1);
}
template <class ELFT>
uint64_t ELFState<ELFT>::getSectionNameOffset(StringRef Name) {
// If a section is excluded from section headers, we do not save its name in
// the string table.
if (ExcludedSectionHeaders.count(Name))
return 0;
return ShStrtabStrings->getOffset(Name);
}
static uint64_t writeContent(ContiguousBlobAccumulator &CBA,
const Optional<yaml::BinaryRef> &Content,
const Optional<llvm::yaml::Hex64> &Size) {
size_t ContentSize = 0;
if (Content) {
CBA.writeAsBinary(*Content);
ContentSize = Content->binary_size();
}
if (!Size)
return ContentSize;
CBA.writeZeros(*Size - ContentSize);
return *Size;
}
static StringRef getDefaultLinkSec(unsigned SecType) {
switch (SecType) {
case ELF::SHT_REL:
case ELF::SHT_RELA:
case ELF::SHT_GROUP:
case ELF::SHT_LLVM_CALL_GRAPH_PROFILE:
case ELF::SHT_LLVM_ADDRSIG:
return ".symtab";
case ELF::SHT_GNU_versym:
case ELF::SHT_HASH:
case ELF::SHT_GNU_HASH:
return ".dynsym";
case ELF::SHT_DYNSYM:
case ELF::SHT_GNU_verdef:
case ELF::SHT_GNU_verneed:
return ".dynstr";
case ELF::SHT_SYMTAB:
return ".strtab";
default:
return "";
}
}
template <class ELFT>
void ELFState<ELFT>::initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
ContiguousBlobAccumulator &CBA) {
// Ensure SHN_UNDEF entry is present. An all-zero section header is a
// valid SHN_UNDEF entry since SHT_NULL == 0.
SHeaders.resize(Doc.getSections().size());
for (const std::unique_ptr<ELFYAML::Chunk> &D : Doc.Chunks) {
if (ELFYAML::Fill *S = dyn_cast<ELFYAML::Fill>(D.get())) {
S->Offset = alignToOffset(CBA, /*Align=*/1, S->Offset);
writeFill(*S, CBA);
LocationCounter += S->Size;
continue;
}
if (ELFYAML::SectionHeaderTable *S =
dyn_cast<ELFYAML::SectionHeaderTable>(D.get())) {
if (S->NoHeaders.getValueOr(false))
continue;
if (!S->Offset)
S->Offset = alignToOffset(CBA, sizeof(typename ELFT::uint),
/*Offset=*/None);
else
S->Offset = alignToOffset(CBA, /*Align=*/1, S->Offset);
uint64_t Size = S->getNumHeaders(SHeaders.size()) * sizeof(Elf_Shdr);
// The full section header information might be not available here, so
// fill the space with zeroes as a placeholder.
CBA.writeZeros(Size);
LocationCounter += Size;
continue;
}
ELFYAML::Section *Sec = cast<ELFYAML::Section>(D.get());
bool IsFirstUndefSection = Sec == Doc.getSections().front();
if (IsFirstUndefSection && Sec->IsImplicit)
continue;
Elf_Shdr &SHeader = SHeaders[SN2I.get(Sec->Name)];
if (Sec->Link) {
SHeader.sh_link = toSectionIndex(*Sec->Link, Sec->Name);
} else {
StringRef LinkSec = getDefaultLinkSec(Sec->Type);
unsigned Link = 0;
if (!LinkSec.empty() && !ExcludedSectionHeaders.count(LinkSec) &&
SN2I.lookup(LinkSec, Link))
SHeader.sh_link = Link;
}
if (Sec->EntSize)
SHeader.sh_entsize = *Sec->EntSize;
else
SHeader.sh_entsize = ELFYAML::getDefaultShEntSize<ELFT>(
Doc.Header.Machine.getValueOr(ELF::EM_NONE), Sec->Type, Sec->Name);
// We have a few sections like string or symbol tables that are usually
// added implicitly to the end. However, if they are explicitly specified
// in the YAML, we need to write them here. This ensures the file offset
// remains correct.
if (initImplicitHeader(CBA, SHeader, Sec->Name,
Sec->IsImplicit ? nullptr : Sec))
continue;
assert(Sec && "It can't be null unless it is an implicit section. But all "
"implicit sections should already have been handled above.");
SHeader.sh_name =
getSectionNameOffset(ELFYAML::dropUniqueSuffix(Sec->Name));
SHeader.sh_type = Sec->Type;
if (Sec->Flags)
SHeader.sh_flags = *Sec->Flags;
SHeader.sh_addralign = Sec->AddressAlign;
// Set the offset for all sections, except the SHN_UNDEF section with index
// 0 when not explicitly requested.
if (!IsFirstUndefSection || Sec->Offset)
SHeader.sh_offset = alignToOffset(CBA, SHeader.sh_addralign, Sec->Offset);
assignSectionAddress(SHeader, Sec);
if (IsFirstUndefSection) {
if (auto RawSec = dyn_cast<ELFYAML::RawContentSection>(Sec)) {
// We do not write any content for special SHN_UNDEF section.
if (RawSec->Size)
SHeader.sh_size = *RawSec->Size;
if (RawSec->Info)
SHeader.sh_info = *RawSec->Info;
}
LocationCounter += SHeader.sh_size;
overrideFields<ELFT>(Sec, SHeader);
continue;
}
if (!isa<ELFYAML::NoBitsSection>(Sec) && (Sec->Content || Sec->Size))
SHeader.sh_size = writeContent(CBA, Sec->Content, Sec->Size);
if (auto S = dyn_cast<ELFYAML::RawContentSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::SymtabShndxSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::RelocationSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::RelrSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::GroupSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::ARMIndexTableSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::MipsABIFlags>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::NoBitsSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::DynamicSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::SymverSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::VerneedSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::VerdefSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::StackSizesSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::HashSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::AddrsigSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::LinkerOptionsSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::NoteSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::GnuHashSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::DependentLibrariesSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::CallGraphProfileSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::BBAddrMapSection>(Sec)) {
writeSectionContent(SHeader, *S, CBA);
} else {
llvm_unreachable("Unknown section type");
}
LocationCounter += SHeader.sh_size;
// Override section fields if requested.
overrideFields<ELFT>(Sec, SHeader);
}
}
template <class ELFT>
void ELFState<ELFT>::assignSectionAddress(Elf_Shdr &SHeader,
ELFYAML::Section *YAMLSec) {
if (YAMLSec && YAMLSec->Address) {
SHeader.sh_addr = *YAMLSec->Address;
LocationCounter = *YAMLSec->Address;
return;
}
// sh_addr represents the address in the memory image of a process. Sections
// in a relocatable object file or non-allocatable sections do not need
// sh_addr assignment.
if (Doc.Header.Type.value == ELF::ET_REL ||
!(SHeader.sh_flags & ELF::SHF_ALLOC))
return;
LocationCounter =
alignTo(LocationCounter, SHeader.sh_addralign ? SHeader.sh_addralign : 1);
SHeader.sh_addr = LocationCounter;
}
static size_t findFirstNonGlobal(ArrayRef<ELFYAML::Symbol> Symbols) {
for (size_t I = 0; I < Symbols.size(); ++I)
if (Symbols[I].Binding.value != ELF::STB_LOCAL)
return I;
return Symbols.size();
}
template <class ELFT>
std::vector<typename ELFT::Sym>
ELFState<ELFT>::toELFSymbols(ArrayRef<ELFYAML::Symbol> Symbols,
const StringTableBuilder &Strtab) {
std::vector<Elf_Sym> Ret;
Ret.resize(Symbols.size() + 1);
size_t I = 0;
for (const ELFYAML::Symbol &Sym : Symbols) {
Elf_Sym &Symbol = Ret[++I];
// If NameIndex, which contains the name offset, is explicitly specified, we
// use it. This is useful for preparing broken objects. Otherwise, we add
// the specified Name to the string table builder to get its offset.
if (Sym.StName)
Symbol.st_name = *Sym.StName;
else if (!Sym.Name.empty())
Symbol.st_name = Strtab.getOffset(ELFYAML::dropUniqueSuffix(Sym.Name));
Symbol.setBindingAndType(Sym.Binding, Sym.Type);
if (Sym.Section)
Symbol.st_shndx = toSectionIndex(*Sym.Section, "", Sym.Name);
else if (Sym.Index)
Symbol.st_shndx = *Sym.Index;
Symbol.st_value = Sym.Value.getValueOr(yaml::Hex64(0));
Symbol.st_other = Sym.Other ? *Sym.Other : 0;
Symbol.st_size = Sym.Size.getValueOr(yaml::Hex64(0));
}
return Ret;
}
template <class ELFT>
void ELFState<ELFT>::initSymtabSectionHeader(Elf_Shdr &SHeader,
SymtabType STType,
ContiguousBlobAccumulator &CBA,
ELFYAML::Section *YAMLSec) {
bool IsStatic = STType == SymtabType::Static;
ArrayRef<ELFYAML::Symbol> Symbols;
if (IsStatic && Doc.Symbols)
Symbols = *Doc.Symbols;
else if (!IsStatic && Doc.DynamicSymbols)
Symbols = *Doc.DynamicSymbols;
ELFYAML::RawContentSection *RawSec =
dyn_cast_or_null<ELFYAML::RawContentSection>(YAMLSec);
if (RawSec && (RawSec->Content || RawSec->Size)) {
bool HasSymbolsDescription =
(IsStatic && Doc.Symbols) || (!IsStatic && Doc.DynamicSymbols);
if (HasSymbolsDescription) {
StringRef Property = (IsStatic ? "`Symbols`" : "`DynamicSymbols`");
if (RawSec->Content)
reportError("cannot specify both `Content` and " + Property +
" for symbol table section '" + RawSec->Name + "'");
if (RawSec->Size)
reportError("cannot specify both `Size` and " + Property +
" for symbol table section '" + RawSec->Name + "'");
return;
}
}
SHeader.sh_name = getSectionNameOffset(IsStatic ? ".symtab" : ".dynsym");
if (YAMLSec)
SHeader.sh_type = YAMLSec->Type;
else
SHeader.sh_type = IsStatic ? ELF::SHT_SYMTAB : ELF::SHT_DYNSYM;
if (YAMLSec && YAMLSec->Flags)
SHeader.sh_flags = *YAMLSec->Flags;
else if (!IsStatic)
SHeader.sh_flags = ELF::SHF_ALLOC;
// If the symbol table section is explicitly described in the YAML
// then we should set the fields requested.
SHeader.sh_info = (RawSec && RawSec->Info) ? (unsigned)(*RawSec->Info)
: findFirstNonGlobal(Symbols) + 1;
SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 8;
assignSectionAddress(SHeader, YAMLSec);
SHeader.sh_offset =
alignToOffset(CBA, SHeader.sh_addralign, RawSec ? RawSec->Offset : None);
if (RawSec && (RawSec->Content || RawSec->Size)) {
assert(Symbols.empty());
SHeader.sh_size = writeContent(CBA, RawSec->Content, RawSec->Size);
return;
}
std::vector<Elf_Sym> Syms =
toELFSymbols(Symbols, IsStatic ? DotStrtab : DotDynstr);
SHeader.sh_size = Syms.size() * sizeof(Elf_Sym);
CBA.write((const char *)Syms.data(), SHeader.sh_size);
}
template <class ELFT>
void ELFState<ELFT>::initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
StringTableBuilder &STB,
ContiguousBlobAccumulator &CBA,
ELFYAML::Section *YAMLSec) {
SHeader.sh_name = getSectionNameOffset(ELFYAML::dropUniqueSuffix(Name));
SHeader.sh_type = YAMLSec ? YAMLSec->Type : ELF::SHT_STRTAB;
SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 1;
ELFYAML::RawContentSection *RawSec =
dyn_cast_or_null<ELFYAML::RawContentSection>(YAMLSec);
SHeader.sh_offset = alignToOffset(CBA, SHeader.sh_addralign,
YAMLSec ? YAMLSec->Offset : None);
if (RawSec && (RawSec->Content || RawSec->Size)) {
SHeader.sh_size = writeContent(CBA, RawSec->Content, RawSec->Size);
} else {
if (raw_ostream *OS = CBA.getRawOS(STB.getSize()))
STB.write(*OS);
SHeader.sh_size = STB.getSize();
}
if (RawSec && RawSec->Info)
SHeader.sh_info = *RawSec->Info;
if (YAMLSec && YAMLSec->Flags)
SHeader.sh_flags = *YAMLSec->Flags;
else if (Name == ".dynstr")
SHeader.sh_flags = ELF::SHF_ALLOC;
assignSectionAddress(SHeader, YAMLSec);
}
static bool shouldEmitDWARF(DWARFYAML::Data &DWARF, StringRef Name) {
SetVector<StringRef> DebugSecNames = DWARF.getNonEmptySectionNames();
return Name.consume_front(".") && DebugSecNames.count(Name);
}
template <class ELFT>
Expected<uint64_t> emitDWARF(typename ELFT::Shdr &SHeader, StringRef Name,
const DWARFYAML::Data &DWARF,
ContiguousBlobAccumulator &CBA) {
// We are unable to predict the size of debug data, so we request to write 0
// bytes. This should always return us an output stream unless CBA is already
// in an error state.
raw_ostream *OS = CBA.getRawOS(0);
if (!OS)
return 0;
uint64_t BeginOffset = CBA.tell();
auto EmitFunc = DWARFYAML::getDWARFEmitterByName(Name.substr(1));
if (Error Err = EmitFunc(*OS, DWARF))
return std::move(Err);
return CBA.tell() - BeginOffset;
}
template <class ELFT>
void ELFState<ELFT>::initDWARFSectionHeader(Elf_Shdr &SHeader, StringRef Name,
ContiguousBlobAccumulator &CBA,
ELFYAML::Section *YAMLSec) {
SHeader.sh_name = getSectionNameOffset(ELFYAML::dropUniqueSuffix(Name));
SHeader.sh_type = YAMLSec ? YAMLSec->Type : ELF::SHT_PROGBITS;
SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 1;
SHeader.sh_offset = alignToOffset(CBA, SHeader.sh_addralign,
YAMLSec ? YAMLSec->Offset : None);
ELFYAML::RawContentSection *RawSec =
dyn_cast_or_null<ELFYAML::RawContentSection>(YAMLSec);
if (Doc.DWARF && shouldEmitDWARF(*Doc.DWARF, Name)) {
if (RawSec && (RawSec->Content || RawSec->Size))
reportError("cannot specify section '" + Name +
"' contents in the 'DWARF' entry and the 'Content' "
"or 'Size' in the 'Sections' entry at the same time");
else {
if (Expected<uint64_t> ShSizeOrErr =
emitDWARF<ELFT>(SHeader, Name, *Doc.DWARF, CBA))
SHeader.sh_size = *ShSizeOrErr;
else
reportError(ShSizeOrErr.takeError());
}
} else if (RawSec)
SHeader.sh_size = writeContent(CBA, RawSec->Content, RawSec->Size);
else
llvm_unreachable("debug sections can only be initialized via the 'DWARF' "
"entry or a RawContentSection");
if (RawSec && RawSec->Info)
SHeader.sh_info = *RawSec->Info;
if (YAMLSec && YAMLSec->Flags)
SHeader.sh_flags = *YAMLSec->Flags;
else if (Name == ".debug_str")
SHeader.sh_flags = ELF::SHF_MERGE | ELF::SHF_STRINGS;
assignSectionAddress(SHeader, YAMLSec);
}
template <class ELFT> void ELFState<ELFT>::reportError(const Twine &Msg) {
ErrHandler(Msg);
HasError = true;
}
template <class ELFT> void ELFState<ELFT>::reportError(Error Err) {
handleAllErrors(std::move(Err), [&](const ErrorInfoBase &Err) {
reportError(Err.message());
});
}
template <class ELFT>
std::vector<Fragment>
ELFState<ELFT>::getPhdrFragments(const ELFYAML::ProgramHeader &Phdr,
ArrayRef<Elf_Shdr> SHeaders) {
std::vector<Fragment> Ret;
for (const ELFYAML::Chunk *C : Phdr.Chunks) {
if (const ELFYAML::Fill *F = dyn_cast<ELFYAML::Fill>(C)) {
Ret.push_back({*F->Offset, F->Size, llvm::ELF::SHT_PROGBITS,
/*ShAddrAlign=*/1});
continue;
}
const ELFYAML::Section *S = cast<ELFYAML::Section>(C);
const Elf_Shdr &H = SHeaders[SN2I.get(S->Name)];
Ret.push_back({H.sh_offset, H.sh_size, H.sh_type, H.sh_addralign});
}
return Ret;
}
template <class ELFT>
void ELFState<ELFT>::setProgramHeaderLayout(std::vector<Elf_Phdr> &PHeaders,
std::vector<Elf_Shdr> &SHeaders) {
uint32_t PhdrIdx = 0;
for (auto &YamlPhdr : Doc.ProgramHeaders) {
Elf_Phdr &PHeader = PHeaders[PhdrIdx++];
std::vector<Fragment> Fragments = getPhdrFragments(YamlPhdr, SHeaders);
if (!llvm::is_sorted(Fragments, [](const Fragment &A, const Fragment &B) {
return A.Offset < B.Offset;
}))
reportError("sections in the program header with index " +
Twine(PhdrIdx) + " are not sorted by their file offset");
if (YamlPhdr.Offset) {
if (!Fragments.empty() && *YamlPhdr.Offset > Fragments.front().Offset)
reportError("'Offset' for segment with index " + Twine(PhdrIdx) +
" must be less than or equal to the minimum file offset of "
"all included sections (0x" +
Twine::utohexstr(Fragments.front().Offset) + ")");
PHeader.p_offset = *YamlPhdr.Offset;
} else if (!Fragments.empty()) {
PHeader.p_offset = Fragments.front().Offset;
}
// Set the file size if not set explicitly.
if (YamlPhdr.FileSize) {
PHeader.p_filesz = *YamlPhdr.FileSize;
} else if (!Fragments.empty()) {
uint64_t FileSize = Fragments.back().Offset - PHeader.p_offset;
// SHT_NOBITS sections occupy no physical space in a file, we should not
// take their sizes into account when calculating the file size of a
// segment.
if (Fragments.back().Type != llvm::ELF::SHT_NOBITS)
FileSize += Fragments.back().Size;
PHeader.p_filesz = FileSize;
}
// Find the maximum offset of the end of a section in order to set p_memsz.
uint64_t MemOffset = PHeader.p_offset;
for (const Fragment &F : Fragments)
MemOffset = std::max(MemOffset, F.Offset + F.Size);
// Set the memory size if not set explicitly.
PHeader.p_memsz = YamlPhdr.MemSize ? uint64_t(*YamlPhdr.MemSize)
: MemOffset - PHeader.p_offset;
if (YamlPhdr.Align) {
PHeader.p_align = *YamlPhdr.Align;
} else {
// Set the alignment of the segment to be the maximum alignment of the
// sections so that by default the segment has a valid and sensible
// alignment.
PHeader.p_align = 1;
for (const Fragment &F : Fragments)
PHeader.p_align = std::max((uint64_t)PHeader.p_align, F.AddrAlign);
}
}
}
bool llvm::ELFYAML::shouldAllocateFileSpace(
ArrayRef<ELFYAML::ProgramHeader> Phdrs, const ELFYAML::NoBitsSection &S) {
for (const ELFYAML::ProgramHeader &PH : Phdrs) {
auto It = llvm::find_if(
PH.Chunks, [&](ELFYAML::Chunk *C) { return C->Name == S.Name; });
if (std::any_of(It, PH.Chunks.end(), [](ELFYAML::Chunk *C) {
return (isa<ELFYAML::Fill>(C) ||
cast<ELFYAML::Section>(C)->Type != ELF::SHT_NOBITS);
}))
return true;
}
return false;
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::NoBitsSection &S,
ContiguousBlobAccumulator &CBA) {
if (!S.Size)
return;
SHeader.sh_size = *S.Size;
// When a nobits section is followed by a non-nobits section or fill
// in the same segment, we allocate the file space for it. This behavior
// matches linkers.
if (shouldAllocateFileSpace(Doc.ProgramHeaders, S))
CBA.writeZeros(*S.Size);
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(
Elf_Shdr &SHeader, const ELFYAML::RawContentSection &Section,
ContiguousBlobAccumulator &CBA) {
if (Section.Info)
SHeader.sh_info = *Section.Info;
}
static bool isMips64EL(const ELFYAML::Object &Obj) {
return Obj.getMachine() == llvm::ELF::EM_MIPS &&
Obj.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64) &&
Obj.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(
Elf_Shdr &SHeader, const ELFYAML::RelocationSection &Section,
ContiguousBlobAccumulator &CBA) {
assert((Section.Type == llvm::ELF::SHT_REL ||
Section.Type == llvm::ELF::SHT_RELA) &&
"Section type is not SHT_REL nor SHT_RELA");
if (!Section.RelocatableSec.empty())
SHeader.sh_info = toSectionIndex(Section.RelocatableSec, Section.Name);
if (!Section.Relocations)
return;
const bool IsRela = Section.Type == llvm::ELF::SHT_RELA;
for (const ELFYAML::Relocation &Rel : *Section.Relocations) {
const bool IsDynamic = Section.Link && (*Section.Link == ".dynsym");
unsigned SymIdx =
Rel.Symbol ? toSymbolIndex(*Rel.Symbol, Section.Name, IsDynamic) : 0;
if (IsRela) {
Elf_Rela REntry;
zero(REntry);
REntry.r_offset = Rel.Offset;
REntry.r_addend = Rel.Addend;
REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
CBA.write((const char *)&REntry, sizeof(REntry));
} else {
Elf_Rel REntry;
zero(REntry);
REntry.r_offset = Rel.Offset;
REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
CBA.write((const char *)&REntry, sizeof(REntry));
}
}
SHeader.sh_size = (IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel)) *
Section.Relocations->size();
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::RelrSection &Section,
ContiguousBlobAccumulator &CBA) {
if (!Section.Entries)
return;
for (llvm::yaml::Hex64 E : *Section.Entries) {
if (!ELFT::Is64Bits && E > UINT32_MAX)
reportError(Section.Name + ": the value is too large for 32-bits: 0x" +
Twine::utohexstr(E));
CBA.write<uintX_t>(E, ELFT::TargetEndianness);
}
SHeader.sh_size = sizeof(uintX_t) * Section.Entries->size();
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(
Elf_Shdr &SHeader, const ELFYAML::SymtabShndxSection &Shndx,
ContiguousBlobAccumulator &CBA) {
if (Shndx.Content || Shndx.Size) {
SHeader.sh_size = writeContent(CBA, Shndx.Content, Shndx.Size);
return;
}
if (!Shndx.Entries)
return;
for (uint32_t E : *Shndx.Entries)
CBA.write<uint32_t>(E, ELFT::TargetEndianness);
SHeader.sh_size = Shndx.Entries->size() * SHeader.sh_entsize;
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::GroupSection &Section,
ContiguousBlobAccumulator &CBA) {
assert(Section.Type == llvm::ELF::SHT_GROUP &&
"Section type is not SHT_GROUP");
if (Section.Signature)
SHeader.sh_info =
toSymbolIndex(*Section.Signature, Section.Name, /*IsDynamic=*/false);
if (!Section.Members)
return;
for (const ELFYAML::SectionOrType &Member : *Section.Members) {
unsigned int SectionIndex = 0;
if (Member.sectionNameOrType == "GRP_COMDAT")
SectionIndex = llvm::ELF::GRP_COMDAT;
else
SectionIndex = toSectionIndex(Member.sectionNameOrType, Section.Name);
CBA.write<uint32_t>(SectionIndex, ELFT::TargetEndianness);
}
SHeader.sh_size = SHeader.sh_entsize * Section.Members->size();
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::SymverSection &Section,
ContiguousBlobAccumulator &CBA) {
if (!Section.Entries)
return;
for (uint16_t Version : *Section.Entries)
CBA.write<uint16_t>(Version, ELFT::TargetEndianness);
SHeader.sh_size = Section.Entries->size() * SHeader.sh_entsize;
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(
Elf_Shdr &SHeader, const ELFYAML::StackSizesSection &Section,
ContiguousBlobAccumulator &CBA) {
if (!Section.Entries)
return;
if (!Section.Entries)
return;
for (const ELFYAML::StackSizeEntry &E : *Section.Entries) {
CBA.write<uintX_t>(E.Address, ELFT::TargetEndianness);
SHeader.sh_size += sizeof(uintX_t) + CBA.writeULEB128(E.Size);
}
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(
Elf_Shdr &SHeader, const ELFYAML::BBAddrMapSection &Section,
ContiguousBlobAccumulator &CBA) {
if (!Section.Entries)
return;
for (const ELFYAML::BBAddrMapEntry &E : *Section.Entries) {
// Write the address of the function.
CBA.write<uintX_t>(E.Address, ELFT::TargetEndianness);
// Write number of BBEntries (number of basic blocks in the function). This
// is overridden by the 'NumBlocks' YAML field when specified.
uint64_t NumBlocks =
E.NumBlocks.getValueOr(E.BBEntries ? E.BBEntries->size() : 0);
SHeader.sh_size += sizeof(uintX_t) + CBA.writeULEB128(NumBlocks);
// Write all BBEntries.
if (!E.BBEntries)
continue;
for (const ELFYAML::BBAddrMapEntry::BBEntry &BBE : *E.BBEntries)
SHeader.sh_size += CBA.writeULEB128(BBE.AddressOffset) +
CBA.writeULEB128(BBE.Size) +
CBA.writeULEB128(BBE.Metadata);
}
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(
Elf_Shdr &SHeader, const ELFYAML::LinkerOptionsSection &Section,
ContiguousBlobAccumulator &CBA) {
if (!Section.Options)
return;
for (const ELFYAML::LinkerOption &LO : *Section.Options) {
CBA.write(LO.Key.data(), LO.Key.size());
CBA.write('\0');
CBA.write(LO.Value.data(), LO.Value.size());
CBA.write('\0');
SHeader.sh_size += (LO.Key.size() + LO.Value.size() + 2);
}
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(
Elf_Shdr &SHeader, const ELFYAML::DependentLibrariesSection &Section,
ContiguousBlobAccumulator &CBA) {
if (!Section.Libs)
return;
for (StringRef Lib : *Section.Libs) {
CBA.write(Lib.data(), Lib.size());
CBA.write('\0');
SHeader.sh_size += Lib.size() + 1;
}
}
template <class ELFT>
uint64_t
ELFState<ELFT>::alignToOffset(ContiguousBlobAccumulator &CBA, uint64_t Align,
llvm::Optional<llvm::yaml::Hex64> Offset) {
uint64_t CurrentOffset = CBA.getOffset();
uint64_t AlignedOffset;
if (Offset) {
if ((uint64_t)*Offset < CurrentOffset) {
reportError("the 'Offset' value (0x" +
Twine::utohexstr((uint64_t)*Offset) + ") goes backward");
return CurrentOffset;
}
// We ignore an alignment when an explicit offset has been requested.
AlignedOffset = *Offset;
} else {
AlignedOffset = alignTo(CurrentOffset, std::max(Align, (uint64_t)1));
}
CBA.writeZeros(AlignedOffset - CurrentOffset);
return AlignedOffset;
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(
Elf_Shdr &SHeader, const ELFYAML::CallGraphProfileSection &Section,
ContiguousBlobAccumulator &CBA) {
if (!Section.Entries)
return;
for (const ELFYAML::CallGraphEntryWeight &E : *Section.Entries) {
CBA.write<uint64_t>(E.Weight, ELFT::TargetEndianness);
SHeader.sh_size += sizeof(object::Elf_CGProfile_Impl<ELFT>);
}
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::HashSection &Section,
ContiguousBlobAccumulator &CBA) {
if (!Section.Bucket)
return;
if (!Section.Bucket)
return;
CBA.write<uint32_t>(
Section.NBucket.getValueOr(llvm::yaml::Hex64(Section.Bucket->size())),
ELFT::TargetEndianness);
CBA.write<uint32_t>(
Section.NChain.getValueOr(llvm::yaml::Hex64(Section.Chain->size())),
ELFT::TargetEndianness);
for (uint32_t Val : *Section.Bucket)
CBA.write<uint32_t>(Val, ELFT::TargetEndianness);
for (uint32_t Val : *Section.Chain)
CBA.write<uint32_t>(Val, ELFT::TargetEndianness);
SHeader.sh_size = (2 + Section.Bucket->size() + Section.Chain->size()) * 4;
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::VerdefSection &Section,
ContiguousBlobAccumulator &CBA) {
if (Section.Info)
SHeader.sh_info = *Section.Info;
else if (Section.Entries)
SHeader.sh_info = Section.Entries->size();
if (!Section.Entries)
return;
uint64_t AuxCnt = 0;
for (size_t I = 0; I < Section.Entries->size(); ++I) {
const ELFYAML::VerdefEntry &E = (*Section.Entries)[I];
Elf_Verdef VerDef;
VerDef.vd_version = E.Version.getValueOr(1);
VerDef.vd_flags = E.Flags.getValueOr(0);
VerDef.vd_ndx = E.VersionNdx.getValueOr(0);
VerDef.vd_hash = E.Hash.getValueOr(0);
VerDef.vd_aux = sizeof(Elf_Verdef);
VerDef.vd_cnt = E.VerNames.size();
if (I == Section.Entries->size() - 1)
VerDef.vd_next = 0;
else
VerDef.vd_next =
sizeof(Elf_Verdef) + E.VerNames.size() * sizeof(Elf_Verdaux);
CBA.write((const char *)&VerDef, sizeof(Elf_Verdef));
for (size_t J = 0; J < E.VerNames.size(); ++J, ++AuxCnt) {
Elf_Verdaux VernAux;
VernAux.vda_name = DotDynstr.getOffset(E.VerNames[J]);
if (J == E.VerNames.size() - 1)
VernAux.vda_next = 0;
else
VernAux.vda_next = sizeof(Elf_Verdaux);
CBA.write((const char *)&VernAux, sizeof(Elf_Verdaux));
}
}
SHeader.sh_size = Section.Entries->size() * sizeof(Elf_Verdef) +
AuxCnt * sizeof(Elf_Verdaux);
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::VerneedSection &Section,
ContiguousBlobAccumulator &CBA) {
if (Section.Info)
SHeader.sh_info = *Section.Info;
else if (Section.VerneedV)
SHeader.sh_info = Section.VerneedV->size();
if (!Section.VerneedV)
return;
uint64_t AuxCnt = 0;
for (size_t I = 0; I < Section.VerneedV->size(); ++I) {
const ELFYAML::VerneedEntry &VE = (*Section.VerneedV)[I];
Elf_Verneed VerNeed;
VerNeed.vn_version = VE.Version;
VerNeed.vn_file = DotDynstr.getOffset(VE.File);
if (I == Section.VerneedV->size() - 1)
VerNeed.vn_next = 0;
else
VerNeed.vn_next =
sizeof(Elf_Verneed) + VE.AuxV.size() * sizeof(Elf_Vernaux);
VerNeed.vn_cnt = VE.AuxV.size();
VerNeed.vn_aux = sizeof(Elf_Verneed);
CBA.write((const char *)&VerNeed, sizeof(Elf_Verneed));
for (size_t J = 0; J < VE.AuxV.size(); ++J, ++AuxCnt) {
const ELFYAML::VernauxEntry &VAuxE = VE.AuxV[J];
Elf_Vernaux VernAux;
VernAux.vna_hash = VAuxE.Hash;
VernAux.vna_flags = VAuxE.Flags;
VernAux.vna_other = VAuxE.Other;
VernAux.vna_name = DotDynstr.getOffset(VAuxE.Name);
if (J == VE.AuxV.size() - 1)
VernAux.vna_next = 0;
else
VernAux.vna_next = sizeof(Elf_Vernaux);
CBA.write((const char *)&VernAux, sizeof(Elf_Vernaux));
}
}
SHeader.sh_size = Section.VerneedV->size() * sizeof(Elf_Verneed) +
AuxCnt * sizeof(Elf_Vernaux);
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(
Elf_Shdr &SHeader, const ELFYAML::ARMIndexTableSection &Section,
ContiguousBlobAccumulator &CBA) {
if (!Section.Entries)
return;
for (const ELFYAML::ARMIndexTableEntry &E : *Section.Entries) {
CBA.write<uint32_t>(E.Offset, ELFT::TargetEndianness);
CBA.write<uint32_t>(E.Value, ELFT::TargetEndianness);
}
SHeader.sh_size = Section.Entries->size() * 8;
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::MipsABIFlags &Section,
ContiguousBlobAccumulator &CBA) {
assert(Section.Type == llvm::ELF::SHT_MIPS_ABIFLAGS &&
"Section type is not SHT_MIPS_ABIFLAGS");
object::Elf_Mips_ABIFlags<ELFT> Flags;
zero(Flags);
SHeader.sh_size = SHeader.sh_entsize;
Flags.version = Section.Version;
Flags.isa_level = Section.ISALevel;
Flags.isa_rev = Section.ISARevision;
Flags.gpr_size = Section.GPRSize;
Flags.cpr1_size = Section.CPR1Size;
Flags.cpr2_size = Section.CPR2Size;
Flags.fp_abi = Section.FpABI;
Flags.isa_ext = Section.ISAExtension;
Flags.ases = Section.ASEs;
Flags.flags1 = Section.Flags1;
Flags.flags2 = Section.Flags2;
CBA.write((const char *)&Flags, sizeof(Flags));
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::DynamicSection &Section,
ContiguousBlobAccumulator &CBA) {
assert(Section.Type == llvm::ELF::SHT_DYNAMIC &&
"Section type is not SHT_DYNAMIC");
if (!Section.Entries)
return;
for (const ELFYAML::DynamicEntry &DE : *Section.Entries) {
CBA.write<uintX_t>(DE.Tag, ELFT::TargetEndianness);
CBA.write<uintX_t>(DE.Val, ELFT::TargetEndianness);
}
SHeader.sh_size = 2 * sizeof(uintX_t) * Section.Entries->size();
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::AddrsigSection &Section,
ContiguousBlobAccumulator &CBA) {
if (!Section.Symbols)
return;
if (!Section.Symbols)
return;
for (StringRef Sym : *Section.Symbols)
SHeader.sh_size +=
CBA.writeULEB128(toSymbolIndex(Sym, Section.Name, /*IsDynamic=*/false));
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::NoteSection &Section,
ContiguousBlobAccumulator &CBA) {
if (!Section.Notes)
return;
uint64_t Offset = CBA.tell();
for (const ELFYAML::NoteEntry &NE : *Section.Notes) {
// Write name size.
if (NE.Name.empty())
CBA.write<uint32_t>(0, ELFT::TargetEndianness);
else
CBA.write<uint32_t>(NE.Name.size() + 1, ELFT::TargetEndianness);
// Write description size.
if (NE.Desc.binary_size() == 0)
CBA.write<uint32_t>(0, ELFT::TargetEndianness);
else
CBA.write<uint32_t>(NE.Desc.binary_size(), ELFT::TargetEndianness);
// Write type.
CBA.write<uint32_t>(NE.Type, ELFT::TargetEndianness);
// Write name, null terminator and padding.
if (!NE.Name.empty()) {
CBA.write(NE.Name.data(), NE.Name.size());
CBA.write('\0');
CBA.padToAlignment(4);
}
// Write description and padding.
if (NE.Desc.binary_size() != 0) {
CBA.writeAsBinary(NE.Desc);
CBA.padToAlignment(4);
}
}
SHeader.sh_size = CBA.tell() - Offset;
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::GnuHashSection &Section,
ContiguousBlobAccumulator &CBA) {
if (!Section.HashBuckets)
return;
if (!Section.Header)
return;
// We write the header first, starting with the hash buckets count. Normally
// it is the number of entries in HashBuckets, but the "NBuckets" property can
// be used to override this field, which is useful for producing broken
// objects.
if (Section.Header->NBuckets)
CBA.write<uint32_t>(*Section.Header->NBuckets, ELFT::TargetEndianness);
else
CBA.write<uint32_t>(Section.HashBuckets->size(), ELFT::TargetEndianness);
// Write the index of the first symbol in the dynamic symbol table accessible
// via the hash table.
CBA.write<uint32_t>(Section.Header->SymNdx, ELFT::TargetEndianness);
// Write the number of words in the Bloom filter. As above, the "MaskWords"
// property can be used to set this field to any value.
if (Section.Header->MaskWords)
CBA.write<uint32_t>(*Section.Header->MaskWords, ELFT::TargetEndianness);
else
CBA.write<uint32_t>(Section.BloomFilter->size(), ELFT::TargetEndianness);
// Write the shift constant used by the Bloom filter.
CBA.write<uint32_t>(Section.Header->Shift2, ELFT::TargetEndianness);
// We've finished writing the header. Now write the Bloom filter.
for (llvm::yaml::Hex64 Val : *Section.BloomFilter)
CBA.write<uintX_t>(Val, ELFT::TargetEndianness);
// Write an array of hash buckets.
for (llvm::yaml::Hex32 Val : *Section.HashBuckets)
CBA.write<uint32_t>(Val, ELFT::TargetEndianness);
// Write an array of hash values.
for (llvm::yaml::Hex32 Val : *Section.HashValues)
CBA.write<uint32_t>(Val, ELFT::TargetEndianness);
SHeader.sh_size = 16 /*Header size*/ +
Section.BloomFilter->size() * sizeof(typename ELFT::uint) +
Section.HashBuckets->size() * 4 +
Section.HashValues->size() * 4;
}
template <class ELFT>
void ELFState<ELFT>::writeFill(ELFYAML::Fill &Fill,
ContiguousBlobAccumulator &CBA) {
size_t PatternSize = Fill.Pattern ? Fill.Pattern->binary_size() : 0;
if (!PatternSize) {
CBA.writeZeros(Fill.Size);
return;
}
// Fill the content with the specified pattern.
uint64_t Written = 0;
for (; Written + PatternSize <= Fill.Size; Written += PatternSize)
CBA.writeAsBinary(*Fill.Pattern);
CBA.writeAsBinary(*Fill.Pattern, Fill.Size - Written);
}
template <class ELFT>
DenseMap<StringRef, size_t> ELFState<ELFT>::buildSectionHeaderReorderMap() {
const ELFYAML::SectionHeaderTable &SectionHeaders =
Doc.getSectionHeaderTable();
if (SectionHeaders.IsImplicit || SectionHeaders.NoHeaders ||
SectionHeaders.isDefault())
return DenseMap<StringRef, size_t>();
DenseMap<StringRef, size_t> Ret;
size_t SecNdx = 0;
StringSet<> Seen;
auto AddSection = [&](const ELFYAML::SectionHeader &Hdr) {
if (!Ret.try_emplace(Hdr.Name, ++SecNdx).second)
reportError("repeated section name: '" + Hdr.Name +
"' in the section header description");
Seen.insert(Hdr.Name);
};
if (SectionHeaders.Sections)
for (const ELFYAML::SectionHeader &Hdr : *SectionHeaders.Sections)
AddSection(Hdr);
if (SectionHeaders.Excluded)
for (const ELFYAML::SectionHeader &Hdr : *SectionHeaders.Excluded)
AddSection(Hdr);
for (const ELFYAML::Section *S : Doc.getSections()) {
// Ignore special first SHT_NULL section.
if (S == Doc.getSections().front())
continue;
if (!Seen.count(S->Name))
reportError("section '" + S->Name +
"' should be present in the 'Sections' or 'Excluded' lists");
Seen.erase(S->Name);
}
for (const auto &It : Seen)
reportError("section header contains undefined section '" + It.getKey() +
"'");
return Ret;
}
template <class ELFT> void ELFState<ELFT>::buildSectionIndex() {
// A YAML description can have an explicit section header declaration that
// allows to change the order of section headers.
DenseMap<StringRef, size_t> ReorderMap = buildSectionHeaderReorderMap();
if (HasError)
return;
// Build excluded section headers map.
std::vector<ELFYAML::Section *> Sections = Doc.getSections();
const ELFYAML::SectionHeaderTable &SectionHeaders =
Doc.getSectionHeaderTable();
if (SectionHeaders.Excluded)
for (const ELFYAML::SectionHeader &Hdr : *SectionHeaders.Excluded)
if (!ExcludedSectionHeaders.insert(Hdr.Name).second)
llvm_unreachable("buildSectionIndex() failed");
if (SectionHeaders.NoHeaders.getValueOr(false))
for (const ELFYAML::Section *S : Sections)
if (!ExcludedSectionHeaders.insert(S->Name).second)
llvm_unreachable("buildSectionIndex() failed");
size_t SecNdx = -1;
for (const ELFYAML::Section *S : Sections) {
++SecNdx;
size_t Index = ReorderMap.empty() ? SecNdx : ReorderMap.lookup(S->Name);
if (!SN2I.addName(S->Name, Index))
llvm_unreachable("buildSectionIndex() failed");
if (!ExcludedSectionHeaders.count(S->Name))
ShStrtabStrings->add(ELFYAML::dropUniqueSuffix(S->Name));
}
}
template <class ELFT> void ELFState<ELFT>::buildSymbolIndexes() {
auto Build = [this](ArrayRef<ELFYAML::Symbol> V, NameToIdxMap &Map) {
for (size_t I = 0, S = V.size(); I < S; ++I) {
const ELFYAML::Symbol &Sym = V[I];
if (!Sym.Name.empty() && !Map.addName(Sym.Name, I + 1))
reportError("repeated symbol name: '" + Sym.Name + "'");
}
};
if (Doc.Symbols)
Build(*Doc.Symbols, SymN2I);
if (Doc.DynamicSymbols)
Build(*Doc.DynamicSymbols, DynSymN2I);
}
template <class ELFT> void ELFState<ELFT>::finalizeStrings() {
// Add the regular symbol names to .strtab section.
if (Doc.Symbols)
for (const ELFYAML::Symbol &Sym : *Doc.Symbols)
DotStrtab.add(ELFYAML::dropUniqueSuffix(Sym.Name));
DotStrtab.finalize();
// Add the dynamic symbol names to .dynstr section.
if (Doc.DynamicSymbols)
for (const ELFYAML::Symbol &Sym : *Doc.DynamicSymbols)
DotDynstr.add(ELFYAML::dropUniqueSuffix(Sym.Name));
// SHT_GNU_verdef and SHT_GNU_verneed sections might also
// add strings to .dynstr section.
for (const ELFYAML::Chunk *Sec : Doc.getSections()) {
if (auto VerNeed = dyn_cast<ELFYAML::VerneedSection>(Sec)) {
if (VerNeed->VerneedV) {
for (const ELFYAML::VerneedEntry &VE : *VerNeed->VerneedV) {
DotDynstr.add(VE.File);
for (const ELFYAML::VernauxEntry &Aux : VE.AuxV)
DotDynstr.add(Aux.Name);
}
}
} else if (auto VerDef = dyn_cast<ELFYAML::VerdefSection>(Sec)) {
if (VerDef->Entries)
for (const ELFYAML::VerdefEntry &E : *VerDef->Entries)
for (StringRef Name : E.VerNames)
DotDynstr.add(Name);
}
}
DotDynstr.finalize();
// Don't finalize the section header string table a second time if it has
// already been finalized due to being one of the symbol string tables.
if (ShStrtabStrings != &DotStrtab && ShStrtabStrings != &DotDynstr)
ShStrtabStrings->finalize();
}
template <class ELFT>
bool ELFState<ELFT>::writeELF(raw_ostream &OS, ELFYAML::Object &Doc,
yaml::ErrorHandler EH, uint64_t MaxSize) {
ELFState<ELFT> State(Doc, EH);
if (State.HasError)
return false;
// Build the section index, which adds sections to the section header string
// table first, so that we can finalize the section header string table.
State.buildSectionIndex();
State.buildSymbolIndexes();
// Finalize section header string table and the .strtab and .dynstr sections.
// We do this early because we want to finalize the string table builders
// before writing the content of the sections that might want to use them.
State.finalizeStrings();
if (State.HasError)
return false;
std::vector<Elf_Phdr> PHeaders;
State.initProgramHeaders(PHeaders);
// XXX: This offset is tightly coupled with the order that we write
// things to `OS`.
const size_t SectionContentBeginOffset =
sizeof(Elf_Ehdr) + sizeof(Elf_Phdr) * Doc.ProgramHeaders.size();
// It is quite easy to accidentally create output with yaml2obj that is larger
// than intended, for example, due to an issue in the YAML description.
// We limit the maximum allowed output size, but also provide a command line
// option to change this limitation.
ContiguousBlobAccumulator CBA(SectionContentBeginOffset, MaxSize);
std::vector<Elf_Shdr> SHeaders;
State.initSectionHeaders(SHeaders, CBA);
// Now we can decide segment offsets.
State.setProgramHeaderLayout(PHeaders, SHeaders);
bool ReachedLimit = CBA.getOffset() > MaxSize;
if (Error E = CBA.takeLimitError()) {
// We report a custom error message instead below.
consumeError(std::move(E));
ReachedLimit = true;
}
if (ReachedLimit)
State.reportError(
"the desired output size is greater than permitted. Use the "
"--max-size option to change the limit");
if (State.HasError)
return false;
State.writeELFHeader(OS);
writeArrayData(OS, makeArrayRef(PHeaders));
const ELFYAML::SectionHeaderTable &SHT = Doc.getSectionHeaderTable();
if (!SHT.NoHeaders.getValueOr(false))
CBA.updateDataAt(*SHT.Offset, SHeaders.data(),
SHT.getNumHeaders(SHeaders.size()) * sizeof(Elf_Shdr));
CBA.writeBlobToStream(OS);
return true;
}
namespace llvm {
namespace yaml {
bool yaml2elf(llvm::ELFYAML::Object &Doc, raw_ostream &Out, ErrorHandler EH,
uint64_t MaxSize) {
bool IsLE = Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
bool Is64Bit = Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64);
if (Is64Bit) {
if (IsLE)
return ELFState<object::ELF64LE>::writeELF(Out, Doc, EH, MaxSize);
return ELFState<object::ELF64BE>::writeELF(Out, Doc, EH, MaxSize);
}
if (IsLE)
return ELFState<object::ELF32LE>::writeELF(Out, Doc, EH, MaxSize);
return ELFState<object::ELF32BE>::writeELF(Out, Doc, EH, MaxSize);
}
} // namespace yaml
} // namespace llvm
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