//===- X86LDBackend.h -----------------------------------------------------===//
//
// The MCLinker Project
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef X86_LDBACKEND_H
#define X86_LDBACKEND_H
#include "X86ELFDynamic.h"
#include "X86GOT.h"
#include "X86GOTPLT.h"
#include "X86PLT.h"
#include <mcld/LD/LDSection.h>
#include <mcld/Target/GNULDBackend.h>
#include <mcld/Target/OutputRelocSection.h>
namespace mcld {
class LinkerConfig;
class GNUInfo;
//===----------------------------------------------------------------------===//
/// X86GNULDBackend - linker backend of X86 target of GNU ELF format
///
class X86GNULDBackend : public GNULDBackend
{
public:
/** \enum ReservedEntryType
* \brief The reserved entry type of reserved space in ResolveInfo.
*
* This is used for sacnRelocation to record what kinds of entries are
* reserved for this resolved symbol
*
* In X86, there are three kinds of entries, GOT, PLT, and dynamic reloction.
* GOT may needs a corresponding relocation to relocate itself, so we
* separate GOT to two situations: GOT and GOTRel. Besides, for the same
* symbol, there might be two kinds of entries reserved for different location.
* For example, reference to the same symbol, one may use GOT and the other may
* use dynamic relocation.
*
* bit: 3 2 1 0
* | PLT | GOTRel | GOT | Rel |
*
* value Name - Description
*
* 0000 None - no reserved entry
* 0001 ReserveRel - reserve an dynamic relocation entry
* 0010 ReserveGOT - reserve an GOT entry
* 0011 GOTandRel - For different relocation, we've reserved GOT and
* Rel for different location.
* 0100 GOTRel - reserve an GOT entry and the corresponding Dyncamic
* relocation entry which relocate this GOT entry
* 0101 GOTRelandRel - For different relocation, we've reserved GOTRel
* and relocation entry for different location.
* 1000 ReservePLT - reserve an PLT entry and the corresponding GOT,
* Dynamic relocation entries
* 1001 PLTandRel - For different relocation, we've reserved PLT and
* Rel for different location.
*/
enum ReservedEntryType {
None = 0,
ReserveRel = 1,
ReserveGOT = 2,
GOTandRel = 3,
GOTRel = 4,
GOTRelandRel = 5,
ReservePLT = 8,
PLTandRel = 9
};
public:
X86GNULDBackend(const LinkerConfig& pConfig,
GNUInfo* pInfo,
Relocation::Type pCopyRel);
~X86GNULDBackend();
uint32_t machine() const;
X86PLT& getPLT();
const X86PLT& getPLT() const;
/// preLayout - Backend can do any needed modification before layout
void doPreLayout(IRBuilder& pBuilder);
/// postLayout -Backend can do any needed modification after layout
void doPostLayout(Module& pModule, IRBuilder& pBuilder);
/// dynamic - the dynamic section of the target machine.
/// Use co-variant return type to return its own dynamic section.
X86ELFDynamic& dynamic();
/// dynamic - the dynamic section of the target machine.
/// Use co-variant return type to return its own dynamic section.
const X86ELFDynamic& dynamic() const;
/// emitSectionData - write out the section data into the memory region.
/// When writers get a LDSection whose kind is LDFileFormat::Target, writers
/// call back target backend to emit the data.
///
/// Backends handle the target-special tables (plt, gp,...) by themselves.
/// Backend can put the data of the tables in MCSectionData directly
/// - LDSection.getSectionData can get the section data.
/// Or, backend can put the data into special data structure
/// - backend can maintain its own map<LDSection, table> to get the table
/// from given LDSection.
///
/// @param pSection - the given LDSection
/// @param pLayout - for comouting the size of fragment
/// @param pRegion - the region to write out data
/// @return the size of the table in the file.
uint64_t emitSectionData(const LDSection& pSection,
MemoryRegion& pRegion) const;
/// initRelocator - create and initialize Relocator.
virtual bool initRelocator() = 0;
/// getRelocator - return relocator.
Relocator* getRelocator();
virtual void initTargetSections(Module& pModule, ObjectBuilder& pBuilder) = 0;
void initTargetSymbols(IRBuilder& pBuilder, Module& pModule);
/// scanRelocation - determine the empty entries are needed or not and create
/// the empty entries if needed.
/// For X86, following entries are check to create:
/// - GOT entry (for .got and .got.plt sections)
/// - PLT entry (for .plt section)
/// - dynamin relocation entries (for .rel.plt and .rel.dyn sections)
void scanRelocation(Relocation& pReloc,
IRBuilder& pBuilder,
Module& pModule,
LDSection& pSection);
OutputRelocSection& getRelDyn();
const OutputRelocSection& getRelDyn() const;
OutputRelocSection& getRelPLT();
const OutputRelocSection& getRelPLT() const;
/// getTargetSectionOrder - compute the layout order of X86 target sections
unsigned int getTargetSectionOrder(const LDSection& pSectHdr) const;
/// finalizeTargetSymbols - finalize the symbol value
bool finalizeTargetSymbols();
/// getPointerRel - get pointer relocation type.
Relocation::Type getPointerRel()
{ return m_PointerRel; }
private:
virtual void scanLocalReloc(Relocation& pReloc,
IRBuilder& pBuilder,
Module& pModule,
LDSection& pSection) = 0;
virtual void scanGlobalReloc(Relocation& pReloc,
IRBuilder& pBuilder,
Module& pModule,
LDSection& pSection) = 0;
protected:
/// addCopyReloc - add a copy relocation into .rel.dyn for pSym
/// @param pSym - A resolved copy symbol that defined in BSS section
void addCopyReloc(ResolveInfo& pSym);
/// defineSymbolforCopyReloc - allocate a space in BSS section and
/// and force define the copy of pSym to BSS section
/// @return the output LDSymbol of the copy symbol
LDSymbol& defineSymbolforCopyReloc(IRBuilder& pLinker,
const ResolveInfo& pSym);
void defineGOTSymbol(IRBuilder& pBuilder, Fragment&);
protected:
/// getRelEntrySize - the size in BYTE of rel type relocation
size_t getRelEntrySize()
{ return m_RelEntrySize; }
/// getRelEntrySize - the size in BYTE of rela type relocation
size_t getRelaEntrySize()
{ return m_RelaEntrySize; }
private:
/// doCreateProgramHdrs - backend can implement this function to create the
/// target-dependent segments
void doCreateProgramHdrs(Module& pModule);
virtual void setGOTSectionSize(IRBuilder& pBuilder) = 0;
virtual uint64_t emitGOTSectionData(MemoryRegion& pRegion) const = 0;
virtual uint64_t emitGOTPLTSectionData(MemoryRegion& pRegion,
const ELFFileFormat* FileFormat) const = 0;
virtual void setRelDynSize() = 0;
virtual void setRelPLTSize() = 0;
protected:
Relocator* m_pRelocator;
X86PLT* m_pPLT;
/// m_RelDyn - dynamic relocation table of .rel.dyn
OutputRelocSection* m_pRelDyn;
/// m_RelPLT - dynamic relocation table of .rel.plt
OutputRelocSection* m_pRelPLT;
X86ELFDynamic* m_pDynamic;
LDSymbol* m_pGOTSymbol;
size_t m_RelEntrySize;
size_t m_RelaEntrySize;
Relocation::Type m_CopyRel;
Relocation::Type m_PointerRel;
};
//
//===----------------------------------------------------------------------===//
/// X86_32GNULDBackend - linker backend of X86-32 target of GNU ELF format
///
class X86_32GNULDBackend : public X86GNULDBackend
{
public:
X86_32GNULDBackend(const LinkerConfig& pConfig, GNUInfo* pInfo);
~X86_32GNULDBackend();
void initTargetSections(Module& pModule, ObjectBuilder& pBuilder);
X86_32GOT& getGOT();
const X86_32GOT& getGOT() const;
X86_32GOTPLT& getGOTPLT();
const X86_32GOTPLT& getGOTPLT() const;
X86_32GOTEntry& getTLSModuleID();
private:
void scanLocalReloc(Relocation& pReloc,
IRBuilder& pBuilder,
Module& pModule,
LDSection& pSection);
void scanGlobalReloc(Relocation& pReloc,
IRBuilder& pBuilder,
Module& pModule,
LDSection& pSection);
/// initRelocator - create and initialize Relocator.
bool initRelocator();
/// ----- tls optimization ----- ///
/// convert R_386_TLS_IE to R_386_TLS_LE
void convertTLSIEtoLE(Relocation& pReloc, LDSection& pSection);
void setGOTSectionSize(IRBuilder& pBuilder);
uint64_t emitGOTSectionData(MemoryRegion& pRegion) const;
uint64_t emitGOTPLTSectionData(MemoryRegion& pRegion,
const ELFFileFormat* FileFormat) const;
void setRelDynSize();
void setRelPLTSize();
private:
X86_32GOT* m_pGOT;
X86_32GOTPLT* m_pGOTPLT;
};
//
//===----------------------------------------------------------------------===//
/// X86_64GNULDBackend - linker backend of X86-64 target of GNU ELF format
///
class X86_64GNULDBackend : public X86GNULDBackend
{
public:
X86_64GNULDBackend(const LinkerConfig& pConfig, GNUInfo* pInfo);
~X86_64GNULDBackend();
void initTargetSections(Module& pModule, ObjectBuilder& pBuilder);
X86_64GOT& getGOT();
const X86_64GOT& getGOT() const;
X86_64GOTPLT& getGOTPLT();
const X86_64GOTPLT& getGOTPLT() const;
private:
void scanLocalReloc(Relocation& pReloc,
IRBuilder& pBuilder,
Module& pModule,
LDSection& pSection);
void scanGlobalReloc(Relocation& pReloc,
IRBuilder& pBuilder,
Module& pModule,
LDSection& pSection);
/// initRelocator - create and initialize Relocator.
bool initRelocator();
void setGOTSectionSize(IRBuilder& pBuilder);
uint64_t emitGOTSectionData(MemoryRegion& pRegion) const;
uint64_t emitGOTPLTSectionData(MemoryRegion& pRegion,
const ELFFileFormat* FileFormat) const;
void setRelDynSize();
void setRelPLTSize();
private:
X86_64GOT* m_pGOT;
X86_64GOTPLT* m_pGOTPLT;
};
} // namespace of mcld
#endif