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//===- lib/ReaderWriter/ELF/ARM/ARMELFWriters.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_ARM_ARM_ELF_WRITERS_H
#define LLD_READER_WRITER_ELF_ARM_ARM_ELF_WRITERS_H
#include "ARMLinkingContext.h"
#include "ARMSymbolTable.h"
#include "llvm/Support/ELF.h"
namespace lld {
namespace elf {
template <class WriterT> class ARMELFWriter : public WriterT {
public:
ARMELFWriter(ARMLinkingContext &ctx, TargetLayout<ELF32LE> &layout);
void finalizeDefaultAtomValues() override;
/// \brief Create symbol table.
unique_bump_ptr<SymbolTable<ELF32LE>> createSymbolTable() override;
// Setup the ELF header.
std::error_code setELFHeader() override;
protected:
static const char *gotSymbol;
static const char *dynamicSymbol;
private:
ARMLinkingContext &_ctx;
TargetLayout<ELF32LE> &_armLayout;
};
template <class WriterT>
const char *ARMELFWriter<WriterT>::gotSymbol = "_GLOBAL_OFFSET_TABLE_";
template <class WriterT>
const char *ARMELFWriter<WriterT>::dynamicSymbol = "_DYNAMIC";
template <class WriterT>
ARMELFWriter<WriterT>::ARMELFWriter(ARMLinkingContext &ctx,
TargetLayout<ELF32LE> &layout)
: WriterT(ctx, layout), _ctx(ctx), _armLayout(layout) {}
template <class WriterT>
void ARMELFWriter<WriterT>::finalizeDefaultAtomValues() {
// Finalize the atom values that are part of the parent.
WriterT::finalizeDefaultAtomValues();
if (auto *gotAtom = _armLayout.findAbsoluteAtom(gotSymbol)) {
if (auto gotpltSection = _armLayout.findOutputSection(".got.plt"))
gotAtom->_virtualAddr = gotpltSection->virtualAddr();
else if (auto gotSection = _armLayout.findOutputSection(".got"))
gotAtom->_virtualAddr = gotSection->virtualAddr();
else
gotAtom->_virtualAddr = 0;
}
if (auto *dynamicAtom = _armLayout.findAbsoluteAtom(dynamicSymbol)) {
if (auto dynamicSection = _armLayout.findOutputSection(".dynamic"))
dynamicAtom->_virtualAddr = dynamicSection->virtualAddr();
else
dynamicAtom->_virtualAddr = 0;
}
// Set required by gcc libc __ehdr_start symbol with pointer to ELF header
if (auto ehdr = _armLayout.findAbsoluteAtom("__ehdr_start"))
ehdr->_virtualAddr = this->_elfHeader->virtualAddr();
// Set required by gcc libc symbols __exidx_start/__exidx_end
this->updateScopeAtomValues("exidx", ".ARM.exidx");
}
template <class WriterT>
unique_bump_ptr<SymbolTable<ELF32LE>>
ARMELFWriter<WriterT>::createSymbolTable() {
return unique_bump_ptr<SymbolTable<ELF32LE>>(new (this->_alloc)
ARMSymbolTable(_ctx));
}
template <class WriterT> std::error_code ARMELFWriter<WriterT>::setELFHeader() {
if (std::error_code ec = WriterT::setELFHeader())
return ec;
// Set ARM-specific flags.
this->_elfHeader->e_flags(llvm::ELF::EF_ARM_EABI_VER5 |
llvm::ELF::EF_ARM_VFP_FLOAT);
StringRef entryName = _ctx.entrySymbolName();
if (const AtomLayout *al = _armLayout.findAtomLayoutByName(entryName)) {
if (const auto *ea = dyn_cast<DefinedAtom>(al->_atom)) {
switch (ea->codeModel()) {
case DefinedAtom::codeNA:
if (al->_virtualAddr & 0x3) {
llvm::report_fatal_error(
"Two least bits must be zero for ARM entry point");
}
break;
case DefinedAtom::codeARMThumb:
// Fixup entry point for Thumb code.
this->_elfHeader->e_entry(al->_virtualAddr | 0x1);
break;
default:
llvm_unreachable("Wrong code model of entry point atom");
}
}
}
return std::error_code();
}
} // namespace elf
} // namespace lld
#endif // LLD_READER_WRITER_ELF_ARM_ARM_ELF_WRITERS_H
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