caio/clang-p2996
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
Files
7a24dbdfd31511d754be2a931c2fcd2b00a0fb4f
clang-p2996/llvm/tools/yaml2obj/yaml2elf.cpp
James Henderson fd99780c09 [yaml2obj]Re-allow dynamic sections to have raw content 
Recently, support was added to yaml2obj to allow dynamic sections to
have a list of entries, to make it easier to write tests with dynamic
sections. However, this change also removed the ability to provide
custom contents to the dynamic section, making it hard to test
malformed contents (e.g. because the section is not a valid size to
contain an array of entries). This change reinstates this. An error is
emitted if raw content and dynamic entries are both specified.

Reviewed by: grimar, ruiu

Differential Review: https://reviews.llvm.org/D58543

llvm-svn: 354770
2019-02-25 11:02:24 +00:00

936 lines
33 KiB
C++
Raw Blame History

//===- 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 "yaml2obj.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/MC/StringTableBuilder.h"
#include "llvm/Object/ELFObjectFile.h"
#include "llvm/ObjectYAML/ELFYAML.h"
#include "llvm/Support/EndianStream.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;
/// \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);
for (; CurrentOffset != AlignedOffset; ++CurrentOffset)
OS.write('\0');
return AlignedOffset; // == CurrentOffset;
}
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;
}
void writeBlobToStream(raw_ostream &Out) { Out << OS.str(); }
};
} // end anonymous namespace
// 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.
namespace {
class NameToIdxMap {
StringMap<int> Map;
public:
/// \returns true if name is already present in the map.
bool addName(StringRef Name, unsigned i) {
return !Map.insert(std::make_pair(Name, (int)i)).second;
}
/// \returns true if name is not present in the map
bool lookup(StringRef Name, unsigned &Idx) const {
StringMap<int>::const_iterator I = Map.find(Name);
if (I == Map.end())
return true;
Idx = I->getValue();
return false;
}
/// asserts if name is not present in the map
unsigned get(StringRef Name) const {
unsigned Idx = 0;
auto missing = lookup(Name, Idx);
(void)missing;
assert(!missing && "Expected section not found in index");
return Idx;
}
unsigned size() const { return Map.size(); }
};
} // 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));
}
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;
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;
const ELFYAML::Object &Doc;
bool buildSectionIndex();
bool buildSymbolIndex(std::size_t &StartIndex,
const std::vector<ELFYAML::Symbol> &Symbols);
void initELFHeader(Elf_Ehdr &Header);
void initProgramHeaders(std::vector<Elf_Phdr> &PHeaders);
bool initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
ContiguousBlobAccumulator &CBA);
void initSymtabSectionHeader(Elf_Shdr &SHeader, SymtabType STType,
ContiguousBlobAccumulator &CBA);
void initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
StringTableBuilder &STB,
ContiguousBlobAccumulator &CBA);
void setProgramHeaderLayout(std::vector<Elf_Phdr> &PHeaders,
std::vector<Elf_Shdr> &SHeaders);
void addSymbols(const std::vector<ELFYAML::Symbol> &Symbols,
std::vector<Elf_Sym> &Syms, unsigned SymbolBinding,
const StringTableBuilder &Strtab);
void writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::RawContentSection &Section,
ContiguousBlobAccumulator &CBA);
bool writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::RelocationSection &Section,
ContiguousBlobAccumulator &CBA);
bool writeSectionContent(Elf_Shdr &SHeader, const ELFYAML::Group &Group,
ContiguousBlobAccumulator &CBA);
bool writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::SymverSection &Section,
ContiguousBlobAccumulator &CBA);
bool writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::VerneedSection &Section,
ContiguousBlobAccumulator &CBA);
bool writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::VerdefSection &Section,
ContiguousBlobAccumulator &CBA);
bool writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::MipsABIFlags &Section,
ContiguousBlobAccumulator &CBA);
bool writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::DynamicSection &Section,
ContiguousBlobAccumulator &CBA);
bool hasDynamicSymbols() const;
SmallVector<const char *, 5> implicitSectionNames() const;
// - SHT_NULL entry (placed first, i.e. 0'th entry)
// - symbol table (.symtab) (defaults to after last yaml section)
// - string table (.strtab) (defaults to after .symtab)
// - section header string table (.shstrtab) (defaults to after .strtab)
// - dynamic symbol table (.dynsym) (defaults to after .shstrtab)
// - dynamic string table (.dynstr) (defaults to after .dynsym)
unsigned getDotSymTabSecNo() const { return SN2I.get(".symtab"); }
unsigned getDotStrTabSecNo() const { return SN2I.get(".strtab"); }
unsigned getDotShStrTabSecNo() const { return SN2I.get(".shstrtab"); }
unsigned getDotDynSymSecNo() const { return SN2I.get(".dynsym"); }
unsigned getDotDynStrSecNo() const { return SN2I.get(".dynstr"); }
unsigned getSectionCount() const { return SN2I.size() + 1; }
ELFState(const ELFYAML::Object &D) : Doc(D) {}
public:
static int writeELF(raw_ostream &OS, const ELFYAML::Object &Doc);
private:
void finalizeStrings();
};
} // end anonymous namespace
template <class ELFT>
void ELFState<ELFT>::initELFHeader(Elf_Ehdr &Header) {
using namespace llvm::ELF;
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;
bool IsLittleEndian = ELFT::TargetEndianness == support::little;
Header.e_ident[EI_DATA] = IsLittleEndian ? ELFDATA2LSB : ELFDATA2MSB;
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 = sizeof(Header);
Header.e_flags = Doc.Header.Flags;
Header.e_ehsize = sizeof(Elf_Ehdr);
Header.e_phentsize = sizeof(Elf_Phdr);
Header.e_phnum = Doc.ProgramHeaders.size();
Header.e_shentsize = sizeof(Elf_Shdr);
// Immediately following the ELF header and program headers.
Header.e_shoff =
sizeof(Header) + sizeof(Elf_Phdr) * Doc.ProgramHeaders.size();
Header.e_shnum = getSectionCount();
Header.e_shstrndx = getDotShStrTabSecNo();
}
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);
}
}
static bool convertSectionIndex(NameToIdxMap &SN2I, StringRef SecName,
StringRef IndexSrc, unsigned &IndexDest) {
if (SN2I.lookup(IndexSrc, IndexDest) && !to_integer(IndexSrc, IndexDest)) {
WithColor::error() << "Unknown section referenced: '" << IndexSrc
<< "' at YAML section '" << SecName << "'.\n";
return false;
}
return true;
}
template <class ELFT>
bool 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.
Elf_Shdr SHeader;
zero(SHeader);
SHeaders.push_back(SHeader);
for (const auto &Sec : Doc.Sections) {
zero(SHeader);
SHeader.sh_name = DotShStrtab.getOffset(Sec->Name);
SHeader.sh_type = Sec->Type;
SHeader.sh_flags = Sec->Flags;
SHeader.sh_addr = Sec->Address;
SHeader.sh_addralign = Sec->AddressAlign;
if (!Sec->Link.empty()) {
unsigned Index;
if (!convertSectionIndex(SN2I, Sec->Name, Sec->Link, Index))
return false;
SHeader.sh_link = Index;
}
if (auto S = dyn_cast<ELFYAML::RawContentSection>(Sec.get()))
writeSectionContent(SHeader, *S, CBA);
else if (auto S = dyn_cast<ELFYAML::RelocationSection>(Sec.get())) {
if (S->Link.empty())
// For relocation section set link to .symtab by default.
SHeader.sh_link = getDotSymTabSecNo();
unsigned Index;
if (!convertSectionIndex(SN2I, S->Name, S->RelocatableSec, Index))
return false;
SHeader.sh_info = Index;
if (!writeSectionContent(SHeader, *S, CBA))
return false;
} else if (auto S = dyn_cast<ELFYAML::Group>(Sec.get())) {
unsigned SymIdx;
if (SymN2I.lookup(S->Signature, SymIdx) &&
!to_integer(S->Signature, SymIdx)) {
WithColor::error() << "Unknown symbol referenced: '" << S->Signature
<< "' at YAML section '" << S->Name << "'.\n";
return false;
}
SHeader.sh_info = SymIdx;
if (!writeSectionContent(SHeader, *S, CBA))
return false;
} else if (auto S = dyn_cast<ELFYAML::MipsABIFlags>(Sec.get())) {
if (!writeSectionContent(SHeader, *S, CBA))
return false;
} else if (auto S = dyn_cast<ELFYAML::NoBitsSection>(Sec.get())) {
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.get())) {
if (!writeSectionContent(SHeader, *S, CBA))
return false;
} else if (auto S = dyn_cast<ELFYAML::SymverSection>(Sec.get())) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::VerneedSection>(Sec.get())) {
writeSectionContent(SHeader, *S, CBA);
} else if (auto S = dyn_cast<ELFYAML::VerdefSection>(Sec.get())) {
writeSectionContent(SHeader, *S, CBA);
} else
llvm_unreachable("Unknown section type");
SHeaders.push_back(SHeader);
}
return true;
}
template <class ELFT>
void ELFState<ELFT>::initSymtabSectionHeader(Elf_Shdr &SHeader,
SymtabType STType,
ContiguousBlobAccumulator &CBA) {
zero(SHeader);
bool IsStatic = STType == SymtabType::Static;
SHeader.sh_name = DotShStrtab.getOffset(IsStatic ? ".symtab" : ".dynsym");
SHeader.sh_type = IsStatic ? ELF::SHT_SYMTAB : ELF::SHT_DYNSYM;
SHeader.sh_link = IsStatic ? getDotStrTabSecNo() : getDotDynStrSecNo();
const auto &Symbols = IsStatic ? Doc.Symbols : Doc.DynamicSymbols;
auto &Strtab = IsStatic ? DotStrtab : DotDynstr;
// One greater than symbol table index of the last local symbol.
SHeader.sh_info = Symbols.Local.size() + 1;
SHeader.sh_entsize = sizeof(Elf_Sym);
SHeader.sh_addralign = 8;
// If .dynsym section is explicitly described in the YAML
// then we want to use its section address.
if (!IsStatic) {
// Take section index and ignore the SHT_NULL section.
unsigned SecNdx = getDotDynSymSecNo() - 1;
if (SecNdx < Doc.Sections.size())
SHeader.sh_addr = Doc.Sections[SecNdx]->Address;
}
std::vector<Elf_Sym> Syms;
{
// Ensure STN_UNDEF is present
Elf_Sym Sym;
zero(Sym);
Syms.push_back(Sym);
}
addSymbols(Symbols.Local, Syms, ELF::STB_LOCAL, Strtab);
addSymbols(Symbols.Global, Syms, ELF::STB_GLOBAL, Strtab);
addSymbols(Symbols.Weak, Syms, ELF::STB_WEAK, Strtab);
writeArrayData(
CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign),
makeArrayRef(Syms));
SHeader.sh_size = arrayDataSize(makeArrayRef(Syms));
}
template <class ELFT>
void ELFState<ELFT>::initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
StringTableBuilder &STB,
ContiguousBlobAccumulator &CBA) {
zero(SHeader);
SHeader.sh_name = DotShStrtab.getOffset(Name);
SHeader.sh_type = ELF::SHT_STRTAB;
STB.write(CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign));
SHeader.sh_size = STB.getSize();
SHeader.sh_addralign = 1;
// If .dynstr section is explicitly described in the YAML
// then we want to use its section address.
if (Name == ".dynstr") {
// Take section index and ignore the SHT_NULL section.
unsigned SecNdx = getDotDynStrSecNo() - 1;
if (SecNdx < Doc.Sections.size())
SHeader.sh_addr = Doc.Sections[SecNdx]->Address;
}
}
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) {
auto &PHeader = PHeaders[PhdrIdx++];
if (YamlPhdr.Sections.size())
PHeader.p_offset = UINT32_MAX;
else
PHeader.p_offset = 0;
// Find the minimum offset for the program header.
for (auto SecName : YamlPhdr.Sections) {
uint32_t Index = 0;
SN2I.lookup(SecName.Section, Index);
const auto &SHeader = SHeaders[Index];
PHeader.p_offset = std::min(PHeader.p_offset, SHeader.sh_offset);
}
// Find the maximum offset of the end of a section in order to set p_filesz.
PHeader.p_filesz = 0;
for (auto SecName : YamlPhdr.Sections) {
uint32_t Index = 0;
SN2I.lookup(SecName.Section, Index);
const auto &SHeader = SHeaders[Index];
uint64_t EndOfSection;
if (SHeader.sh_type == llvm::ELF::SHT_NOBITS)
EndOfSection = SHeader.sh_offset;
else
EndOfSection = SHeader.sh_offset + SHeader.sh_size;
uint64_t EndOfSegment = PHeader.p_offset + PHeader.p_filesz;
EndOfSegment = std::max(EndOfSegment, EndOfSection);
PHeader.p_filesz = EndOfSegment - PHeader.p_offset;
}
// Find the memory size by adding the size of sections at the end of the
// segment. These should be empty (size of zero) and NOBITS sections.
PHeader.p_memsz = PHeader.p_filesz;
for (auto SecName : YamlPhdr.Sections) {
uint32_t Index = 0;
SN2I.lookup(SecName.Section, Index);
const auto &SHeader = SHeaders[Index];
if (SHeader.sh_offset == PHeader.p_offset + PHeader.p_filesz)
PHeader.p_memsz += SHeader.sh_size;
}
// Set the alignment of the segment to be the same as the maximum alignment
// of the sections with the same offset so that by default the segment
// has a valid and sensible alignment.
if (YamlPhdr.Align) {
PHeader.p_align = *YamlPhdr.Align;
} else {
PHeader.p_align = 1;
for (auto SecName : YamlPhdr.Sections) {
uint32_t Index = 0;
SN2I.lookup(SecName.Section, Index);
const auto &SHeader = SHeaders[Index];
if (SHeader.sh_offset == PHeader.p_offset)
PHeader.p_align = std::max(PHeader.p_align, SHeader.sh_addralign);
}
}
}
}
template <class ELFT>
void ELFState<ELFT>::addSymbols(const std::vector<ELFYAML::Symbol> &Symbols,
std::vector<Elf_Sym> &Syms,
unsigned SymbolBinding,
const StringTableBuilder &Strtab) {
for (const auto &Sym : Symbols) {
Elf_Sym Symbol;
zero(Symbol);
if (!Sym.Name.empty())
Symbol.st_name = Strtab.getOffset(Sym.Name);
Symbol.setBindingAndType(SymbolBinding, Sym.Type);
if (!Sym.Section.empty()) {
unsigned Index;
if (SN2I.lookup(Sym.Section, Index)) {
WithColor::error() << "Unknown section referenced: '" << Sym.Section
<< "' by YAML symbol " << Sym.Name << ".\n";
exit(1);
}
Symbol.st_shndx = Index;
} else if (Sym.Index) {
Symbol.st_shndx = *Sym.Index;
}
// else Symbol.st_shndex == SHN_UNDEF (== 0), since it was zero'd earlier.
Symbol.st_value = Sym.Value;
Symbol.st_other = Sym.Other;
Symbol.st_size = Sym.Size;
Syms.push_back(Symbol);
}
}
template <class ELFT>
void
ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::RawContentSection &Section,
ContiguousBlobAccumulator &CBA) {
assert(Section.Size >= Section.Content.binary_size() &&
"Section size and section content are inconsistent");
raw_ostream &OS =
CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
Section.Content.writeAsBinary(OS);
for (auto i = Section.Content.binary_size(); i < Section.Size; ++i)
OS.write(0);
if (Section.EntSize)
SHeader.sh_entsize = *Section.EntSize;
else if (Section.Type == llvm::ELF::SHT_RELR)
SHeader.sh_entsize = sizeof(Elf_Relr);
else
SHeader.sh_entsize = 0;
SHeader.sh_size = Section.Size;
}
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>
bool
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;
SHeader.sh_entsize = IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
SHeader.sh_size = SHeader.sh_entsize * Section.Relocations.size();
auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
for (const auto &Rel : Section.Relocations) {
unsigned SymIdx = 0;
// Some special relocation, R_ARM_v4BX for instance, does not have
// an external reference. So it ignores the return value of lookup()
// here.
if (Rel.Symbol)
SymN2I.lookup(*Rel.Symbol, SymIdx);
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));
}
}
return true;
}
template <class ELFT>
bool 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");
SHeader.sh_entsize = 4;
SHeader.sh_size = SHeader.sh_entsize * Section.Members.size();
raw_ostream &OS =
CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
for (auto member : Section.Members) {
unsigned int sectionIndex = 0;
if (member.sectionNameOrType == "GRP_COMDAT")
sectionIndex = llvm::ELF::GRP_COMDAT;
else if (!convertSectionIndex(SN2I, Section.Name, member.sectionNameOrType,
sectionIndex))
return false;
support::endian::write<uint32_t>(OS, sectionIndex, ELFT::TargetEndianness);
}
return true;
}
template <class ELFT>
bool 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 = 2;
SHeader.sh_size = Section.Entries.size() * SHeader.sh_entsize;
return true;
}
template <class ELFT>
bool 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);
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);
SHeader.sh_info = Section.Info;
return true;
}
template <class ELFT>
bool 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);
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);
SHeader.sh_info = Section.Info;
return true;
}
template <class ELFT>
bool 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));
return true;
}
template <class ELFT>
bool ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
const ELFYAML::DynamicSection &Section,
ContiguousBlobAccumulator &CBA) {
typedef typename ELFT::uint uintX_t;
assert(Section.Type == llvm::ELF::SHT_DYNAMIC &&
"Section type is not SHT_DYNAMIC");
if (!Section.Entries.empty() && Section.Content) {
WithColor::error()
<< "Cannot specify both raw content and explicit entries "
"for dynamic section '"
<< Section.Name << "'.\n";
return false;
}
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);
return true;
}
template <class ELFT> bool ELFState<ELFT>::buildSectionIndex() {
for (unsigned i = 0, e = Doc.Sections.size(); i != e; ++i) {
StringRef Name = Doc.Sections[i]->Name;
DotShStrtab.add(Name);
// "+ 1" to take into account the SHT_NULL entry.
if (SN2I.addName(Name, i + 1)) {
WithColor::error() << "Repeated section name: '" << Name
<< "' at YAML section number " << i << ".\n";
return false;
}
}
auto SecNo = 1 + Doc.Sections.size();
// Add special sections after input sections, if necessary.
for (const auto &Name : implicitSectionNames())
if (!SN2I.addName(Name, SecNo)) {
// Account for this section, since it wasn't in the Doc
++SecNo;
DotShStrtab.add(Name);
}
DotShStrtab.finalize();
return true;
}
template <class ELFT>
bool
ELFState<ELFT>::buildSymbolIndex(std::size_t &StartIndex,
const std::vector<ELFYAML::Symbol> &Symbols) {
for (const auto &Sym : Symbols) {
++StartIndex;
if (Sym.Name.empty())
continue;
if (SymN2I.addName(Sym.Name, StartIndex)) {
WithColor::error() << "Repeated symbol name: '" << Sym.Name << "'.\n";
return false;
}
}
return true;
}
template <class ELFT> void ELFState<ELFT>::finalizeStrings() {
auto AddSymbols = [](StringTableBuilder &StrTab,
const ELFYAML::LocalGlobalWeakSymbols &Symbols) {
for (const auto &Sym : Symbols.Local)
StrTab.add(Sym.Name);
for (const auto &Sym : Symbols.Global)
StrTab.add(Sym.Name);
for (const auto &Sym : Symbols.Weak)
StrTab.add(Sym.Name);
};
// Add the regular symbol names to .strtab section.
AddSymbols(DotStrtab, Doc.Symbols);
DotStrtab.finalize();
if (!hasDynamicSymbols())
return;
// Add the dynamic symbol names to .dynstr section.
AddSymbols(DotDynstr, Doc.DynamicSymbols);
// SHT_GNU_verdef and SHT_GNU_verneed sections might also
// add strings to .dynstr section.
for (const std::unique_ptr<ELFYAML::Section> &Sec : Doc.Sections) {
if (auto VerNeed = dyn_cast<ELFYAML::VerneedSection>(Sec.get())) {
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.get())) {
for (const ELFYAML::VerdefEntry &E : VerDef->Entries)
for (StringRef Name : E.VerNames)
DotDynstr.add(Name);
}
}
DotDynstr.finalize();
}
template <class ELFT>
int ELFState<ELFT>::writeELF(raw_ostream &OS, const ELFYAML::Object &Doc) {
ELFState<ELFT> State(Doc);
// 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();
if (!State.buildSectionIndex())
return 1;
std::size_t StartSymIndex = 0;
if (!State.buildSymbolIndex(StartSymIndex, Doc.Symbols.Local) ||
!State.buildSymbolIndex(StartSymIndex, Doc.Symbols.Global) ||
!State.buildSymbolIndex(StartSymIndex, Doc.Symbols.Weak))
return 1;
Elf_Ehdr Header;
State.initELFHeader(Header);
// TODO: Flesh out section header support.
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 = Header.e_ehsize +
Header.e_phentsize * Header.e_phnum +
Header.e_shentsize * Header.e_shnum;
ContiguousBlobAccumulator CBA(SectionContentBeginOffset);
std::vector<Elf_Shdr> SHeaders;
if(!State.initSectionHeaders(SHeaders, CBA))
return 1;
// Populate SHeaders with implicit sections not present in the Doc
for (const auto &Name : State.implicitSectionNames())
if (State.SN2I.get(Name) >= SHeaders.size())
SHeaders.push_back({});
// Initialize the implicit sections
auto Index = State.SN2I.get(".symtab");
State.initSymtabSectionHeader(SHeaders[Index], SymtabType::Static, CBA);
Index = State.SN2I.get(".strtab");
State.initStrtabSectionHeader(SHeaders[Index], ".strtab", State.DotStrtab, CBA);
Index = State.SN2I.get(".shstrtab");
State.initStrtabSectionHeader(SHeaders[Index], ".shstrtab", State.DotShStrtab, CBA);
if (State.hasDynamicSymbols()) {
Index = State.SN2I.get(".dynsym");
State.initSymtabSectionHeader(SHeaders[Index], SymtabType::Dynamic, CBA);
SHeaders[Index].sh_flags |= ELF::SHF_ALLOC;
Index = State.SN2I.get(".dynstr");
State.initStrtabSectionHeader(SHeaders[Index], ".dynstr", State.DotDynstr, CBA);
SHeaders[Index].sh_flags |= ELF::SHF_ALLOC;
}
// Now we can decide segment offsets
State.setProgramHeaderLayout(PHeaders, SHeaders);
OS.write((const char *)&Header, sizeof(Header));
writeArrayData(OS, makeArrayRef(PHeaders));
writeArrayData(OS, makeArrayRef(SHeaders));
CBA.writeBlobToStream(OS);
return 0;
}
template <class ELFT> bool ELFState<ELFT>::hasDynamicSymbols() const {
return Doc.DynamicSymbols.Global.size() > 0 ||
Doc.DynamicSymbols.Weak.size() > 0 ||
Doc.DynamicSymbols.Local.size() > 0;
}
template <class ELFT>
SmallVector<const char *, 5> ELFState<ELFT>::implicitSectionNames() const {
if (!hasDynamicSymbols())
return {".symtab", ".strtab", ".shstrtab"};
return {".symtab", ".strtab", ".shstrtab", ".dynsym", ".dynstr"};
}
static bool is64Bit(const ELFYAML::Object &Doc) {
return Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64);
}
static bool isLittleEndian(const ELFYAML::Object &Doc) {
return Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
}
int yaml2elf(llvm::ELFYAML::Object &Doc, raw_ostream &Out) {
if (is64Bit(Doc)) {
if (isLittleEndian(Doc))
return ELFState<object::ELF64LE>::writeELF(Out, Doc);
else
return ELFState<object::ELF64BE>::writeELF(Out, Doc);
} else {
if (isLittleEndian(Doc))
return ELFState<object::ELF32LE>::writeELF(Out, Doc);
else
return ELFState<object::ELF32BE>::writeELF(Out, Doc);
}
}
Reference in New Issue View Git Blame Copy Permalink