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//===- lib/ReaderWriter/ELF/Mips/MipsTargetHandler.h ----------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef LLD_READER_WRITER_ELF_MIPS_TARGET_HANDLER_H
#define LLD_READER_WRITER_ELF_MIPS_TARGET_HANDLER_H
#include "DefaultTargetHandler.h"
#include "MipsELFReader.h"
#include "MipsLinkingContext.h"
#include "MipsRelocationHandler.h"
#include "MipsSectionChunks.h"
#include "TargetLayout.h"
#include "llvm/ADT/DenseSet.h"
namespace lld {
namespace elf {
/// \brief TargetLayout for Mips
template <class ELFType>
class MipsTargetLayout final : public TargetLayout<ELFType> {
public:
MipsTargetLayout(const MipsLinkingContext &ctx)
: TargetLayout<ELFType>(ctx),
_gotSection(new (_alloc) MipsGOTSection<ELFType>(ctx)),
_pltSection(new (_alloc) MipsPLTSection<ELFType>(ctx)) {}
const MipsGOTSection<ELFType> &getGOTSection() const { return *_gotSection; }
const MipsPLTSection<ELFType> &getPLTSection() const { return *_pltSection; }
AtomSection<ELFType> *
createSection(StringRef name, int32_t type,
DefinedAtom::ContentPermissions permissions,
Layout::SectionOrder order) override {
if (type == DefinedAtom::typeGOT && name == ".got")
return _gotSection;
if (type == DefinedAtom::typeStub && name == ".plt")
return _pltSection;
return DefaultLayout<ELFType>::createSection(name, type, permissions,
order);
}
StringRef getSectionName(const DefinedAtom *da) const override {
return llvm::StringSwitch<StringRef>(da->customSectionName())
.StartsWith(".ctors", ".ctors")
.StartsWith(".dtors", ".dtors")
.Default(TargetLayout<ELFType>::getSectionName(da));
}
Layout::SegmentType getSegmentType(Section<ELFType> *section) const override {
switch (section->order()) {
case DefaultLayout<ELFType>::ORDER_CTORS:
case DefaultLayout<ELFType>::ORDER_DTORS:
return llvm::ELF::PT_LOAD;
default:
return TargetLayout<ELFType>::getSegmentType(section);
}
}
ErrorOr<const lld::AtomLayout &> addAtom(const Atom *atom) override {
// Maintain:
// 1. Set of shared library atoms referenced by regular defined atoms.
// 2. Set of shared library atoms have corresponding R_MIPS_COPY copies.
if (const auto *da = dyn_cast<DefinedAtom>(atom))
for (const Reference *ref : *da) {
if (ref->kindNamespace() == lld::Reference::KindNamespace::ELF) {
assert(ref->kindArch() == Reference::KindArch::Mips);
if (ref->kindValue() == llvm::ELF::R_MIPS_COPY)
_copiedDynSymNames.insert(atom->name());
}
}
return TargetLayout<ELFType>::addAtom(atom);
}
bool isCopied(const SharedLibraryAtom *sla) const {
return _copiedDynSymNames.count(sla->name());
}
/// \brief GP offset relative to .got section.
uint64_t getGPOffset() const { return 0x7FF0; }
/// \brief Get '_gp' symbol atom layout.
AtomLayout *getGP() {
if (!_gpAtom.hasValue()) {
auto atom = this->findAbsoluteAtom("_gp");
_gpAtom = atom != this->absoluteAtoms().end() ? *atom : nullptr;
}
return *_gpAtom;
}
/// \brief Get '_gp_disp' symbol atom layout.
AtomLayout *getGPDisp() {
if (!_gpDispAtom.hasValue()) {
auto atom = this->findAbsoluteAtom("_gp_disp");
_gpDispAtom = atom != this->absoluteAtoms().end() ? *atom : nullptr;
}
return *_gpDispAtom;
}
private:
llvm::BumpPtrAllocator _alloc;
MipsGOTSection<ELFType> *_gotSection;
MipsPLTSection<ELFType> *_pltSection;
llvm::Optional<AtomLayout *> _gpAtom;
llvm::Optional<AtomLayout *> _gpDispAtom;
llvm::StringSet<> _copiedDynSymNames;
};
/// \brief Mips Runtime file.
template <class ELFType>
class MipsRuntimeFile final : public CRuntimeFile<ELFType> {
public:
MipsRuntimeFile(const MipsLinkingContext &ctx)
: CRuntimeFile<ELFType>(ctx, "Mips runtime file") {}
};
/// \brief TargetHandler for Mips
class MipsTargetHandler final : public DefaultTargetHandler<Mips32ElELFType> {
public:
MipsTargetHandler(MipsLinkingContext &ctx);
MipsTargetLayout<Mips32ElELFType> &getTargetLayout() override {
return *_targetLayout;
}
std::unique_ptr<Reader> getObjReader(bool atomizeStrings) override {
return std::unique_ptr<Reader>(new MipsELFObjectReader(atomizeStrings));
}
const MipsTargetRelocationHandler &getRelocationHandler() const override {
return *_relocationHandler;
}
std::unique_ptr<Writer> getWriter() override;
void registerRelocationNames(Registry ®istry) override;
private:
static const Registry::KindStrings kindStrings[];
MipsLinkingContext &_ctx;
std::unique_ptr<MipsRuntimeFile<Mips32ElELFType>> _runtimeFile;
std::unique_ptr<MipsTargetLayout<Mips32ElELFType>> _targetLayout;
std::unique_ptr<MipsTargetRelocationHandler> _relocationHandler;
};
template <class ELFT>
class MipsDynamicSymbolTable : public DynamicSymbolTable<ELFT> {
public:
MipsDynamicSymbolTable(const MipsLinkingContext &ctx,
MipsTargetLayout<ELFT> &layout)
: DynamicSymbolTable<ELFT>(ctx, layout, ".dynsym",
DefaultLayout<ELFT>::ORDER_DYNAMIC_SYMBOLS),
_targetLayout(layout) {}
void sortSymbols() override {
typedef typename DynamicSymbolTable<ELFT>::SymbolEntry SymbolEntry;
std::stable_sort(this->_symbolTable.begin(), this->_symbolTable.end(),
[this](const SymbolEntry &A, const SymbolEntry &B) {
if (A._symbol.getBinding() != STB_GLOBAL &&
B._symbol.getBinding() != STB_GLOBAL)
return A._symbol.getBinding() < B._symbol.getBinding();
return _targetLayout.getGOTSection().compare(A._atom, B._atom);
});
}
void finalize() override {
const auto &pltSection = _targetLayout.getPLTSection();
// Under some conditions a dynamic symbol table record should hold a symbol
// value of the corresponding PLT entry. For details look at the PLT entry
// creation code in the class MipsRelocationPass. Let's update atomLayout
// fields for such symbols.
for (auto &ste : this->_symbolTable) {
if (!ste._atom || ste._atomLayout)
continue;
auto *layout = pltSection.findPLTLayout(ste._atom);
if (layout) {
ste._symbol.st_value = layout->_virtualAddr;
ste._symbol.st_other |= ELF::STO_MIPS_PLT;
}
}
DynamicSymbolTable<Mips32ElELFType>::finalize();
}
private:
MipsTargetLayout<ELFT> &_targetLayout;
};
} // end namespace elf
} // end namespace lld
#endif
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