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//===- Target.h -------------------------------------------------*- C++ -*-===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef LLD_ELF_TARGET_H
#define LLD_ELF_TARGET_H
#include "InputSection.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Object/ELF.h"
#include <memory>
namespace lld {
namespace elf {
class InputFile;
class SymbolBody;
class TargetInfo {
public:
virtual bool isPicRel(uint32_t Type) const { return true; }
virtual uint32_t getDynRel(uint32_t Type) const { return Type; }
virtual void writeGotPltHeader(uint8_t *Buf) const {}
virtual void writeGotPlt(uint8_t *Buf, const SymbolBody &S) const {};
virtual void writeIgotPlt(uint8_t *Buf, const SymbolBody &S) const;
virtual int64_t getImplicitAddend(const uint8_t *Buf, uint32_t Type) const;
// If lazy binding is supported, the first entry of the PLT has code
// to call the dynamic linker to resolve PLT entries the first time
// they are called. This function writes that code.
virtual void writePltHeader(uint8_t *Buf) const {}
virtual void writePlt(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr, int32_t Index,
unsigned RelOff) const {}
virtual void addPltHeaderSymbols(InputSectionBase *IS) const {}
virtual void addPltSymbols(InputSectionBase *IS, uint64_t Off) const {}
// Returns true if a relocation only uses the low bits of a value such that
// all those bits are in in the same page. For example, if the relocation
// only uses the low 12 bits in a system with 4k pages. If this is true, the
// bits will always have the same value at runtime and we don't have to emit
// a dynamic relocation.
virtual bool usesOnlyLowPageBits(uint32_t Type) const;
// Decide whether a Thunk is needed for the relocation from File
// targeting S.
virtual bool needsThunk(RelExpr Expr, uint32_t RelocType,
const InputFile *File, const SymbolBody &S) const;
virtual RelExpr getRelExpr(uint32_t Type, const SymbolBody &S,
const uint8_t *Loc) const = 0;
virtual void relocateOne(uint8_t *Loc, uint32_t Type, uint64_t Val) const = 0;
virtual ~TargetInfo();
unsigned TlsGdRelaxSkip = 1;
unsigned PageSize = 4096;
unsigned DefaultMaxPageSize = 4096;
// On FreeBSD x86_64 the first page cannot be mmaped.
// On Linux that is controled by vm.mmap_min_addr. At least on some x86_64
// installs that is 65536, so the first 15 pages cannot be used.
// Given that, the smallest value that can be used in here is 0x10000.
uint64_t DefaultImageBase = 0x10000;
uint32_t CopyRel;
uint32_t GotRel;
uint32_t PltRel;
uint32_t RelativeRel;
uint32_t IRelativeRel;
uint32_t TlsDescRel;
uint32_t TlsGotRel;
uint32_t TlsModuleIndexRel;
uint32_t TlsOffsetRel;
unsigned GotEntrySize = 0;
unsigned GotPltEntrySize = 0;
unsigned PltEntrySize;
unsigned PltHeaderSize;
// At least on x86_64 positions 1 and 2 are used by the first plt entry
// to support lazy loading.
unsigned GotPltHeaderEntriesNum = 3;
// Set to 0 for variant 2
unsigned TcbSize = 0;
bool NeedsThunks = false;
// A 4-byte field corresponding to one or more trap instructions, used to pad
// executable OutputSections.
uint32_t TrapInstr = 0;
virtual RelExpr adjustRelaxExpr(uint32_t Type, const uint8_t *Data,
RelExpr Expr) const;
virtual void relaxGot(uint8_t *Loc, uint64_t Val) const;
virtual void relaxTlsGdToIe(uint8_t *Loc, uint32_t Type, uint64_t Val) const;
virtual void relaxTlsGdToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const;
virtual void relaxTlsIeToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const;
virtual void relaxTlsLdToLe(uint8_t *Loc, uint32_t Type, uint64_t Val) const;
};
uint64_t getPPC64TocBase();
uint64_t getAArch64Page(uint64_t Expr);
extern TargetInfo *Target;
TargetInfo *createTarget();
}
std::string toString(uint32_t RelType);
}
#endif