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archived-llvm-mirror/lib/ObjectYAML/ELFEmitter.cpp
Georgii Rymar 0ba63b8a56 [yaml2obj] - Automatically assign sh_addr for allocatable sections. 
I've noticed that it is not convenient to create YAMLs from
binaries (using obj2yaml) that have to be test cases for obj2yaml
later (after applying yaml2obj).

The problem, for example is that obj2yaml emits "DynamicSymbols:"
key instead of .dynsym. It also does not create .dynstr.
And when a YAML document without explicitly defined .dynsym/.dynstr
is given to yaml2obj, we have issues:

1) These sections are placed after non-allocatable sections (I've fixed it in D74756).
2) They have VA == 0. User needs create descriptions for such sections explicitly manually
    to set a VA.

This patch addresses (2). I suggest to let yaml2obj assign virtual addresses by itself.
It makes an output binary to be much closer to "normal" ELF.
(It is still possible to use "Address: 0x0" for a section to get the original behavior
if it is needed)

Differential revision: https://reviews.llvm.org/D74764
2020-02-22 14:43:54 +03:00

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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/StringSet.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/MC/StringTableBuilder.h"
#include "llvm/Object/ELFObjectFile.h"
#include "llvm/ObjectYAML/ELFYAML.h"
#include "llvm/ObjectYAML/yaml2obj.h"
#include "llvm/Support/EndianStream.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`).
namespace {
class ContiguousBlobAccumulator {
const uint64_t InitialOffset;
SmallVector<char, 128> Buf;
raw_svector_ostream OS;
public:
ContiguousBlobAccumulator(uint64_t InitialOffset_)
: InitialOffset(InitialOffset_), Buf(), OS(Buf) {}
template <class Integer>
raw_ostream &getOSAndAlignedOffset(Integer &Offset, unsigned Align) {
Offset = padToAlignment(Align);
return OS;
}
/// \returns The new offset.
uint64_t padToAlignment(unsigned Align) {
if (Align == 0)
Align = 1;
uint64_t CurrentOffset = InitialOffset + OS.tell();
uint64_t AlignedOffset = alignTo(CurrentOffset, Align);
OS.write_zeros(AlignedOffset - CurrentOffset);
return AlignedOffset; // == CurrentOffset;
}
void writeBlobToStream(raw_ostream &Out) { Out << OS.str(); }
};
// 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 {
typedef typename ELFT::Ehdr Elf_Ehdr;
typedef typename ELFT::Phdr Elf_Phdr;
typedef typename ELFT::Shdr Elf_Shdr;
typedef typename ELFT::Sym Elf_Sym;
typedef typename ELFT::Rel Elf_Rel;
typedef typename ELFT::Rela Elf_Rela;
typedef typename ELFT::Relr Elf_Relr;
typedef typename ELFT::Dyn Elf_Dyn;
typedef typename ELFT::uint uintX_t;
enum class SymtabType { Static, Dynamic };
/// The future ".strtab" section.
StringTableBuilder DotStrtab{StringTableBuilder::ELF};
/// The future ".shstrtab" section.
StringTableBuilder DotShStrtab{StringTableBuilder::ELF};
/// The future ".dynstr" section.
StringTableBuilder DotDynstr{StringTableBuilder::ELF};
NameToIdxMap SN2I;
NameToIdxMap SymN2I;
NameToIdxMap DynSymN2I;
ELFYAML::Object &Doc;
uint64_t LocationCounter = 0;
bool HasError = false;
yaml::ErrorHandler ErrHandler;
void reportError(const Twine &Msg);
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 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(ContiguousBlobAccumulator &CBA, raw_ostream &OS);
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::Group &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::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::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);
public:
static bool writeELF(raw_ostream &OS, ELFYAML::Object &Doc,
yaml::ErrorHandler EH);
};
} // 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) {
std::vector<ELFYAML::Section *> Sections = Doc.getSections();
StringSet<> DocSections;
for (const ELFYAML::Section *Sec : Sections)
if (!Sec->Name.empty())
DocSections.insert(Sec->Name);
// 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));
std::vector<StringRef> ImplicitSections;
if (Doc.DynamicSymbols)
ImplicitSections.insert(ImplicitSections.end(), {".dynsym", ".dynstr"});
if (Doc.Symbols)
ImplicitSections.push_back(".symtab");
ImplicitSections.insert(ImplicitSections.end(), {".strtab", ".shstrtab"});
// 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::Chunk> Sec = std::make_unique<ELFYAML::Section>(
ELFYAML::Chunk::ChunkKind::RawContent, true /*IsImplicit*/);
Sec->Name = SecName;
Doc.Chunks.push_back(std::move(Sec));
}
}
template <class ELFT>
void ELFState<ELFT>::writeELFHeader(ContiguousBlobAccumulator &CBA, 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;
Header.e_machine = Doc.Header.Machine;
Header.e_version = EV_CURRENT;
Header.e_entry = Doc.Header.Entry;
Header.e_phoff = Doc.ProgramHeaders.size() ? sizeof(Header) : 0;
Header.e_flags = Doc.Header.Flags;
Header.e_ehsize = sizeof(Elf_Ehdr);
Header.e_phentsize = Doc.ProgramHeaders.size() ? sizeof(Elf_Phdr) : 0;
Header.e_phnum = Doc.ProgramHeaders.size();
Header.e_shentsize =
Doc.Header.SHEntSize ? (uint16_t)*Doc.Header.SHEntSize : sizeof(Elf_Shdr);
// Immediately following the ELF header and program headers.
// Align the start of the section header and write the ELF header.
uint64_t SHOff;
CBA.getOSAndAlignedOffset(SHOff, sizeof(typename ELFT::uint));
Header.e_shoff =
Doc.Header.SHOff ? typename ELFT::uint(*Doc.Header.SHOff) : SHOff;
Header.e_shnum =
Doc.Header.SHNum ? (uint16_t)*Doc.Header.SHNum : Doc.getSections().size();
Header.e_shstrndx = Doc.Header.SHStrNdx ? (uint16_t)*Doc.Header.SHStrNdx
: SN2I.get(".shstrtab");
OS.write((const char *)&Header, sizeof(Header));
}
template <class ELFT>
void ELFState<ELFT>::initProgramHeaders(std::vector<Elf_Phdr> &PHeaders) {
for (const auto &YamlPhdr : Doc.ProgramHeaders) {
Elf_Phdr 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);
}
}
template <class ELFT>
unsigned ELFState<ELFT>::toSectionIndex(StringRef S, StringRef LocSec,
StringRef LocSym) {
unsigned Index;
if (SN2I.lookup(S, Index) || to_integer(S, Index))
return Index;
assert(LocSec.empty() || LocSym.empty());
if (!LocSym.empty())
reportError("unknown section referenced: '" + S + "' by YAML symbol '" +
LocSym + "'");
else
reportError("unknown section referenced: '" + S + "' by YAML section '" +
LocSec + "'");
return 0;
}
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->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;
}
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 == ".symtab")
initSymtabSectionHeader(Header, SymtabType::Static, CBA, YAMLSec);
else if (SecName == ".strtab")
initStrtabSectionHeader(Header, SecName, DotStrtab, CBA, YAMLSec);
else if (SecName == ".shstrtab")
initStrtabSectionHeader(Header, SecName, DotShStrtab, CBA, YAMLSec);
else if (SecName == ".dynsym")
initSymtabSectionHeader(Header, SymtabType::Dynamic, CBA, YAMLSec);
else if (SecName == ".dynstr")
initStrtabSectionHeader(Header, SecName, DotDynstr, CBA, YAMLSec);
else
return false;
LocationCounter += Header.sh_size;
// Override section fields if requested.
overrideFields<ELFT>(YAMLSec, Header);
return true;
}
StringRef llvm::ELFYAML::dropUniqueSuffix(StringRef S) {
size_t SuffixPos = S.rfind(" [");
if (SuffixPos == StringRef::npos)
return S;
return S.substr(0, SuffixPos);
}
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());
size_t SecNdx = -1;
for (const std::unique_ptr<ELFYAML::Chunk> &D : Doc.Chunks) {
if (auto S = dyn_cast<ELFYAML::Fill>(D.get())) {
writeFill(*S, CBA);
LocationCounter += S->Size;
continue;
}
++SecNdx;
ELFYAML::Section *Sec = cast<ELFYAML::Section>(D.get());
if (SecNdx == 0 && Sec->IsImplicit)
continue;
// 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.
Elf_Shdr &SHeader = SHeaders[SecNdx];
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 =
DotShStrtab.getOffset(ELFYAML::dropUniqueSuffix(Sec->Name));
SHeader.sh_type = Sec->Type;
if (Sec->Flags)
SHeader.sh_flags = *Sec->Flags;
SHeader.sh_addralign = Sec->AddressAlign;
assignSectionAddress(SHeader, Sec);
if (!Sec->Link.empty())
SHeader.sh_link = toSectionIndex(Sec->Link, Sec->Name);
if (SecNdx == 0) {
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;
}
if (Sec->EntSize)
SHeader.sh_entsize = *Sec->EntSize;
} else 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::Group>(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)) {
SHeader.sh_entsize = 0;
SHeader.sh_size = S->Size;
// SHT_NOBITS section does not have content
// so just to setup the section offset.
CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
} 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 {
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();
}
static uint64_t writeContent(raw_ostream &OS,
const Optional<yaml::BinaryRef> &Content,
const Optional<llvm::yaml::Hex64> &Size) {
size_t ContentSize = 0;
if (Content) {
Content->writeAsBinary(OS);
ContentSize = Content->binary_size();
}
if (!Size)
return ContentSize;
OS.write_zeros(*Size - ContentSize);
return *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.empty())
Symbol.st_shndx = toSectionIndex(Sym.Section, "", Sym.Name);
else if (Sym.Index)
Symbol.st_shndx = *Sym.Index;
Symbol.st_value = Sym.Value;
Symbol.st_other = Sym.Other ? *Sym.Other : 0;
Symbol.st_size = Sym.Size;
}
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;
}
}
zero(SHeader);
SHeader.sh_name = DotShStrtab.getOffset(IsStatic ? ".symtab" : ".dynsym");
if (YAMLSec)
SHeader.sh_type = YAMLSec->Type;
else
SHeader.sh_type = IsStatic ? ELF::SHT_SYMTAB : ELF::SHT_DYNSYM;
if (RawSec && !RawSec->Link.empty()) {
// If the Link field is explicitly defined in the document,
// we should use it.
SHeader.sh_link = toSectionIndex(RawSec->Link, RawSec->Name);
} else {
// When we describe the .dynsym section in the document explicitly, it is
// allowed to omit the "DynamicSymbols" tag. In this case .dynstr is not
// added implicitly and we should be able to leave the Link zeroed if
// .dynstr is not defined.
unsigned Link = 0;
if (IsStatic)
Link = SN2I.get(".strtab");
else
SN2I.lookup(".dynstr", Link);
SHeader.sh_link = Link;
}
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_entsize = (YAMLSec && YAMLSec->EntSize)
? (uint64_t)(*YAMLSec->EntSize)
: sizeof(Elf_Sym);
SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 8;
assignSectionAddress(SHeader, YAMLSec);
auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
if (RawSec && (RawSec->Content || RawSec->Size)) {
assert(Symbols.empty());
SHeader.sh_size = writeContent(OS, RawSec->Content, RawSec->Size);
return;
}
std::vector<Elf_Sym> Syms =
toELFSymbols(Symbols, IsStatic ? DotStrtab : DotDynstr);
writeArrayData(OS, makeArrayRef(Syms));
SHeader.sh_size = arrayDataSize(makeArrayRef(Syms));
}
template <class ELFT>
void ELFState<ELFT>::initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
StringTableBuilder &STB,
ContiguousBlobAccumulator &CBA,
ELFYAML::Section *YAMLSec) {
zero(SHeader);
SHeader.sh_name = DotShStrtab.getOffset(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);
auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
if (RawSec && (RawSec->Content || RawSec->Size)) {
SHeader.sh_size = writeContent(OS, RawSec->Content, RawSec->Size);
} else {
STB.write(OS);
SHeader.sh_size = STB.getSize();
}
if (YAMLSec && YAMLSec->EntSize)
SHeader.sh_entsize = *YAMLSec->EntSize;
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;
// If the section is explicitly described in the YAML
// then we want to use its section address.
assignSectionAddress(SHeader, YAMLSec);
}
template <class ELFT> void ELFState<ELFT>::reportError(const Twine &Msg) {
ErrHandler(Msg);
HasError = true;
}
template <class ELFT>
std::vector<Fragment>
ELFState<ELFT>::getPhdrFragments(const ELFYAML::ProgramHeader &Phdr,
ArrayRef<typename ELFT::Shdr> SHeaders) {
DenseMap<StringRef, ELFYAML::Fill *> NameToFill;
for (const std::unique_ptr<ELFYAML::Chunk> &D : Doc.Chunks)
if (auto S = dyn_cast<ELFYAML::Fill>(D.get()))
NameToFill[S->Name] = S;
std::vector<Fragment> Ret;
for (const ELFYAML::SectionName &SecName : Phdr.Sections) {
unsigned Index;
if (SN2I.lookup(SecName.Section, Index)) {
const typename ELFT::Shdr &H = SHeaders[Index];
Ret.push_back({H.sh_offset, H.sh_size, H.sh_type, H.sh_addralign});
continue;
}
if (ELFYAML::Fill *Fill = NameToFill.lookup(SecName.Section)) {
Ret.push_back({Fill->ShOffset, Fill->Size, llvm::ELF::SHT_PROGBITS,
/*ShAddrAlign=*/1});
continue;
}
reportError("unknown section or fill referenced: '" + SecName.Section +
"' by program header");
}
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 (YamlPhdr.Offset) {
PHeader.p_offset = *YamlPhdr.Offset;
} else {
if (YamlPhdr.Sections.size())
PHeader.p_offset = UINT32_MAX;
else
PHeader.p_offset = 0;
// Find the minimum offset for the program header.
for (const Fragment &F : Fragments)
PHeader.p_offset = std::min((uint64_t)PHeader.p_offset, F.Offset);
}
// Find the maximum offset of the end of a section in order to set p_filesz
// and p_memsz. When setting p_filesz, trailing SHT_NOBITS sections are not
// counted.
uint64_t FileOffset = PHeader.p_offset, MemOffset = PHeader.p_offset;
for (const Fragment &F : Fragments) {
uint64_t End = F.Offset + F.Size;
MemOffset = std::max(MemOffset, End);
if (F.Type != llvm::ELF::SHT_NOBITS)
FileOffset = std::max(FileOffset, End);
}
// Set the file size and the memory size if not set explicitly.
PHeader.p_filesz = YamlPhdr.FileSize ? uint64_t(*YamlPhdr.FileSize)
: FileOffset - PHeader.p_offset;
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);
}
}
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(
Elf_Shdr &SHeader, const ELFYAML::RawContentSection &Section,
ContiguousBlobAccumulator &CBA) {
raw_ostream &OS =
CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
if (Section.EntSize)
SHeader.sh_entsize = *Section.EntSize;
if (Section.Info)
SHeader.sh_info = *Section.Info;
}
static bool isMips64EL(const ELFYAML::Object &Doc) {
return Doc.Header.Machine == ELFYAML::ELF_EM(llvm::ELF::EM_MIPS) &&
Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64) &&
Doc.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");
bool IsRela = Section.Type == llvm::ELF::SHT_RELA;
if (Section.EntSize)
SHeader.sh_entsize = *Section.EntSize;
else
SHeader.sh_entsize = IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
SHeader.sh_size = (IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel)) *
Section.Relocations.size();
// For relocation section set link to .symtab by default.
unsigned Link = 0;
if (Section.Link.empty() && SN2I.lookup(".symtab", Link))
SHeader.sh_link = Link;
if (!Section.RelocatableSec.empty())
SHeader.sh_info = toSectionIndex(Section.RelocatableSec, Section.Name);
auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
for (const auto &Rel : Section.Relocations) {
unsigned SymIdx = Rel.Symbol ? toSymbolIndex(*Rel.Symbol, Section.Name,
Section.Link == ".dynsym")
: 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));
OS.write((const char *)&REntry, sizeof(REntry));
} else {
Elf_Rel REntry;
zero(REntry);
REntry.r_offset = Rel.Offset;
REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
OS.write((const char *)&REntry, sizeof(REntry));
}
}
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::RelrSection &Section,
ContiguousBlobAccumulator &CBA) {
raw_ostream &OS =
CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
SHeader.sh_entsize =
Section.EntSize ? uint64_t(*Section.EntSize) : sizeof(Elf_Relr);
if (Section.Content) {
SHeader.sh_size = writeContent(OS, Section.Content, None);
return;
}
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));
support::endian::write<uintX_t>(OS, 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) {
raw_ostream &OS =
CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
for (uint32_t E : Shndx.Entries)
support::endian::write<uint32_t>(OS, E, ELFT::TargetEndianness);
SHeader.sh_entsize = Shndx.EntSize ? (uint64_t)*Shndx.EntSize : 4;
SHeader.sh_size = Shndx.Entries.size() * SHeader.sh_entsize;
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::Group &Section,
ContiguousBlobAccumulator &CBA) {
assert(Section.Type == llvm::ELF::SHT_GROUP &&
"Section type is not SHT_GROUP");
unsigned Link = 0;
if (Section.Link.empty() && SN2I.lookup(".symtab", Link))
SHeader.sh_link = Link;
SHeader.sh_entsize = 4;
SHeader.sh_size = SHeader.sh_entsize * Section.Members.size();
if (Section.Signature)
SHeader.sh_info =
toSymbolIndex(*Section.Signature, Section.Name, /*IsDynamic=*/false);
raw_ostream &OS =
CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
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);
support::endian::write<uint32_t>(OS, SectionIndex, ELFT::TargetEndianness);
}
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::SymverSection &Section,
ContiguousBlobAccumulator &CBA) {
raw_ostream &OS =
CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
for (uint16_t Version : Section.Entries)
support::endian::write<uint16_t>(OS, Version, ELFT::TargetEndianness);
SHeader.sh_entsize = Section.EntSize ? (uint64_t)*Section.EntSize : 2;
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) {
raw_ostream &OS =
CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
if (Section.Content || Section.Size) {
SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
return;
}
for (const ELFYAML::StackSizeEntry &E : *Section.Entries) {
support::endian::write<uintX_t>(OS, E.Address, ELFT::TargetEndianness);
SHeader.sh_size += sizeof(uintX_t) + encodeULEB128(E.Size, OS);
}
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(
Elf_Shdr &SHeader, const ELFYAML::LinkerOptionsSection &Section,
ContiguousBlobAccumulator &CBA) {
raw_ostream &OS =
CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
if (Section.Content) {
SHeader.sh_size = writeContent(OS, Section.Content, None);
return;
}
if (!Section.Options)
return;
for (const ELFYAML::LinkerOption &LO : *Section.Options) {
OS.write(LO.Key.data(), LO.Key.size());
OS.write('\0');
OS.write(LO.Value.data(), LO.Value.size());
OS.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) {
raw_ostream &OS =
CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
if (Section.Content) {
SHeader.sh_size = writeContent(OS, Section.Content, None);
return;
}
if (!Section.Libs)
return;
for (StringRef Lib : *Section.Libs) {
OS.write(Lib.data(), Lib.size());
OS.write('\0');
SHeader.sh_size += Lib.size() + 1;
}
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(
Elf_Shdr &SHeader, const ELFYAML::CallGraphProfileSection &Section,
ContiguousBlobAccumulator &CBA) {
raw_ostream &OS =
CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
if (Section.EntSize)
SHeader.sh_entsize = *Section.EntSize;
else
SHeader.sh_entsize = 16;
unsigned Link = 0;
if (Section.Link.empty() && SN2I.lookup(".symtab", Link))
SHeader.sh_link = Link;
if (Section.Content) {
SHeader.sh_size = writeContent(OS, Section.Content, None);
return;
}
if (!Section.Entries)
return;
for (const ELFYAML::CallGraphEntry &E : *Section.Entries) {
unsigned From = toSymbolIndex(E.From, Section.Name, /*IsDynamic=*/false);
unsigned To = toSymbolIndex(E.To, Section.Name, /*IsDynamic=*/false);
support::endian::write<uint32_t>(OS, From, ELFT::TargetEndianness);
support::endian::write<uint32_t>(OS, To, ELFT::TargetEndianness);
support::endian::write<uint64_t>(OS, E.Weight, ELFT::TargetEndianness);
SHeader.sh_size += 16;
}
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::HashSection &Section,
ContiguousBlobAccumulator &CBA) {
raw_ostream &OS =
CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
unsigned Link = 0;
if (Section.Link.empty() && SN2I.lookup(".dynsym", Link))
SHeader.sh_link = Link;
if (Section.Content || Section.Size) {
SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
return;
}
support::endian::write<uint32_t>(OS, Section.Bucket->size(),
ELFT::TargetEndianness);
support::endian::write<uint32_t>(OS, Section.Chain->size(),
ELFT::TargetEndianness);
for (uint32_t Val : *Section.Bucket)
support::endian::write<uint32_t>(OS, Val, ELFT::TargetEndianness);
for (uint32_t Val : *Section.Chain)
support::endian::write<uint32_t>(OS, 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) {
typedef typename ELFT::Verdef Elf_Verdef;
typedef typename ELFT::Verdaux Elf_Verdaux;
raw_ostream &OS =
CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
SHeader.sh_info = Section.Info;
if (Section.Content) {
SHeader.sh_size = writeContent(OS, Section.Content, None);
return;
}
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;
VerDef.vd_flags = E.Flags;
VerDef.vd_ndx = E.VersionNdx;
VerDef.vd_hash = E.Hash;
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);
OS.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);
OS.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) {
typedef typename ELFT::Verneed Elf_Verneed;
typedef typename ELFT::Vernaux Elf_Vernaux;
auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
SHeader.sh_info = Section.Info;
if (Section.Content) {
SHeader.sh_size = writeContent(OS, Section.Content, None);
return;
}
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);
OS.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);
OS.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::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_entsize = sizeof(Flags);
SHeader.sh_size = SHeader.sh_entsize;
auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
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;
OS.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.empty() && Section.Content)
reportError("cannot specify both raw content and explicit entries "
"for dynamic section '" +
Section.Name + "'");
if (Section.Content)
SHeader.sh_size = Section.Content->binary_size();
else
SHeader.sh_size = 2 * sizeof(uintX_t) * Section.Entries.size();
if (Section.EntSize)
SHeader.sh_entsize = *Section.EntSize;
else
SHeader.sh_entsize = sizeof(Elf_Dyn);
raw_ostream &OS =
CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
for (const ELFYAML::DynamicEntry &DE : Section.Entries) {
support::endian::write<uintX_t>(OS, DE.Tag, ELFT::TargetEndianness);
support::endian::write<uintX_t>(OS, DE.Val, ELFT::TargetEndianness);
}
if (Section.Content)
Section.Content->writeAsBinary(OS);
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::AddrsigSection &Section,
ContiguousBlobAccumulator &CBA) {
raw_ostream &OS =
CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
unsigned Link = 0;
if (Section.Link.empty() && SN2I.lookup(".symtab", Link))
SHeader.sh_link = Link;
if (Section.Content || Section.Size) {
SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
return;
}
for (StringRef Sym : *Section.Symbols)
SHeader.sh_size += encodeULEB128(
toSymbolIndex(Sym, Section.Name, /*IsDynamic=*/false), OS);
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::NoteSection &Section,
ContiguousBlobAccumulator &CBA) {
raw_ostream &OS =
CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
uint64_t Offset = OS.tell();
if (Section.Content || Section.Size) {
SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
return;
}
for (const ELFYAML::NoteEntry &NE : *Section.Notes) {
// Write name size.
if (NE.Name.empty())
support::endian::write<uint32_t>(OS, 0, ELFT::TargetEndianness);
else
support::endian::write<uint32_t>(OS, NE.Name.size() + 1,
ELFT::TargetEndianness);
// Write description size.
if (NE.Desc.binary_size() == 0)
support::endian::write<uint32_t>(OS, 0, ELFT::TargetEndianness);
else
support::endian::write<uint32_t>(OS, NE.Desc.binary_size(),
ELFT::TargetEndianness);
// Write type.
support::endian::write<uint32_t>(OS, NE.Type, ELFT::TargetEndianness);
// Write name, null terminator and padding.
if (!NE.Name.empty()) {
support::endian::write<uint8_t>(OS, arrayRefFromStringRef(NE.Name),
ELFT::TargetEndianness);
support::endian::write<uint8_t>(OS, 0, ELFT::TargetEndianness);
CBA.padToAlignment(4);
}
// Write description and padding.
if (NE.Desc.binary_size() != 0) {
NE.Desc.writeAsBinary(OS);
CBA.padToAlignment(4);
}
}
SHeader.sh_size = OS.tell() - Offset;
}
template <class ELFT>
void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::GnuHashSection &Section,
ContiguousBlobAccumulator &CBA) {
raw_ostream &OS =
CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
unsigned Link = 0;
if (Section.Link.empty() && SN2I.lookup(".dynsym", Link))
SHeader.sh_link = Link;
if (Section.Content) {
SHeader.sh_size = writeContent(OS, Section.Content, None);
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)
support::endian::write<uint32_t>(OS, *Section.Header->NBuckets,
ELFT::TargetEndianness);
else
support::endian::write<uint32_t>(OS, Section.HashBuckets->size(),
ELFT::TargetEndianness);
// Write the index of the first symbol in the dynamic symbol table accessible
// via the hash table.
support::endian::write<uint32_t>(OS, 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)
support::endian::write<uint32_t>(OS, *Section.Header->MaskWords,
ELFT::TargetEndianness);
else
support::endian::write<uint32_t>(OS, Section.BloomFilter->size(),
ELFT::TargetEndianness);
// Write the shift constant used by the Bloom filter.
support::endian::write<uint32_t>(OS, Section.Header->Shift2,
ELFT::TargetEndianness);
// We've finished writing the header. Now write the Bloom filter.
for (llvm::yaml::Hex64 Val : *Section.BloomFilter)
support::endian::write<typename ELFT::uint>(OS, Val,
ELFT::TargetEndianness);
// Write an array of hash buckets.
for (llvm::yaml::Hex32 Val : *Section.HashBuckets)
support::endian::write<uint32_t>(OS, Val, ELFT::TargetEndianness);
// Write an array of hash values.
for (llvm::yaml::Hex32 Val : *Section.HashValues)
support::endian::write<uint32_t>(OS, 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) {
raw_ostream &OS = CBA.getOSAndAlignedOffset(Fill.ShOffset, /*Align=*/1);
size_t PatternSize = Fill.Pattern ? Fill.Pattern->binary_size() : 0;
if (!PatternSize) {
OS.write_zeros(Fill.Size);
return;
}
// Fill the content with the specified pattern.
uint64_t Written = 0;
for (; Written + PatternSize <= Fill.Size; Written += PatternSize)
Fill.Pattern->writeAsBinary(OS);
Fill.Pattern->writeAsBinary(OS, Fill.Size - Written);
}
template <class ELFT> void ELFState<ELFT>::buildSectionIndex() {
size_t SecNdx = -1;
StringSet<> Seen;
for (size_t I = 0; I < Doc.Chunks.size(); ++I) {
const std::unique_ptr<ELFYAML::Chunk> &C = Doc.Chunks[I];
bool IsSection = isa<ELFYAML::Section>(C.get());
if (IsSection)
++SecNdx;
if (C->Name.empty())
continue;
if (!Seen.insert(C->Name).second)
reportError("repeated section/fill name: '" + C->Name +
"' at YAML section/fill number " + Twine(I));
if (!IsSection || HasError)
continue;
if (!SN2I.addName(C->Name, SecNdx))
llvm_unreachable("buildSectionIndex() failed");
DotShStrtab.add(ELFYAML::dropUniqueSuffix(C->Name));
}
DotShStrtab.finalize();
}
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();
}
template <class ELFT>
bool ELFState<ELFT>::writeELF(raw_ostream &OS, ELFYAML::Object &Doc,
yaml::ErrorHandler EH) {
ELFState<ELFT> State(Doc, EH);
// Finalize .strtab and .dynstr sections. We do that early because want to
// finalize the string table builders before writing the content of the
// sections that might want to use them.
State.finalizeStrings();
State.buildSectionIndex();
if (State.HasError)
return false;
State.buildSymbolIndexes();
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();
ContiguousBlobAccumulator CBA(SectionContentBeginOffset);
std::vector<Elf_Shdr> SHeaders;
State.initSectionHeaders(SHeaders, CBA);
// Now we can decide segment offsets.
State.setProgramHeaderLayout(PHeaders, SHeaders);
if (State.HasError)
return false;
State.writeELFHeader(CBA, OS);
writeArrayData(OS, makeArrayRef(PHeaders));
CBA.writeBlobToStream(OS);
writeArrayData(OS, makeArrayRef(SHeaders));
return true;
}
namespace llvm {
namespace yaml {
bool yaml2elf(llvm::ELFYAML::Object &Doc, raw_ostream &Out, ErrorHandler EH) {
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);
return ELFState<object::ELF64BE>::writeELF(Out, Doc, EH);
}
if (IsLE)
return ELFState<object::ELF32LE>::writeELF(Out, Doc, EH);
return ELFState<object::ELF32BE>::writeELF(Out, Doc, EH);
}
} // namespace yaml
} // namespace llvm
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