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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 "lld/Common/ErrorHandler.h"
#include "llvm/Object/ELF.h"
namespace lld {
std::string toString(elf::RelType Type);
namespace elf {
class Defined;
class InputFile;
class Symbol;
class TargetInfo {
public:
virtual uint32_t calcEFlags() const { return 0; }
virtual RelType getDynRel(RelType Type) const { return Type; }
virtual void writeGotPltHeader(uint8_t *Buf) const {}
virtual void writeGotHeader(uint8_t *Buf) const {}
virtual void writeGotPlt(uint8_t *Buf, const Symbol &S) const {};
virtual void writeIgotPlt(uint8_t *Buf, const Symbol &S) const;
virtual int64_t getImplicitAddend(const uint8_t *Buf, RelType 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(InputSection &IS) const {}
virtual void addPltSymbols(InputSection &IS, uint64_t Off) const {}
unsigned getPltEntryOffset(unsigned Index) const {
return Index * PltEntrySize + PltHeaderSize;
}
// Returns true if a relocation only uses the low bits of a value such that
// all those bits are 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(RelType Type) const;
// Decide whether a Thunk is needed for the relocation from File
// targeting S.
virtual bool needsThunk(RelExpr Expr, RelType RelocType,
const InputFile *File, uint64_t BranchAddr,
const Symbol &S) const;
// The function with a prologue starting at Loc was compiled with
// -fsplit-stack and it calls a function compiled without. Adjust the prologue
// to do the right thing. See https://gcc.gnu.org/wiki/SplitStacks.
virtual bool adjustPrologueForCrossSplitStack(uint8_t *Loc,
uint8_t *End) const;
// Return true if we can reach Dst from Src with Relocation RelocType
virtual bool inBranchRange(RelType Type, uint64_t Src,
uint64_t Dst) const;
virtual RelExpr getRelExpr(RelType Type, const Symbol &S,
const uint8_t *Loc) const = 0;
virtual void relocateOne(uint8_t *Loc, RelType Type, uint64_t Val) const = 0;
virtual ~TargetInfo();
unsigned TlsGdRelaxSkip = 1;
unsigned PageSize = 4096;
unsigned DefaultMaxPageSize = 4096;
uint64_t getImageBase();
// Offset of _GLOBAL_OFFSET_TABLE_ from base of .got or .got.plt section.
uint64_t GotBaseSymOff = 0;
// True if _GLOBAL_OFFSET_TABLE_ is relative to .got.plt, false if .got.
bool GotBaseSymInGotPlt = true;
// On systems with range extensions we place collections of Thunks at
// regular spacings that enable the majority of branches reach the Thunks.
uint32_t ThunkSectionSpacing = 0;
RelType CopyRel;
RelType GotRel;
RelType PltRel;
RelType RelativeRel;
RelType IRelativeRel;
RelType TlsDescRel;
RelType TlsGotRel;
RelType TlsModuleIndexRel;
RelType 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;
// On PPC ELF V2 abi, the first entry in the .got is the .TOC.
unsigned GotHeaderEntriesNum = 0;
// For TLS variant 1, the TCB is a fixed size specified by the Target.
// For variant 2, the TCB is an unspecified size.
// Set to 0 for variant 2.
unsigned TcbSize = 0;
// Set to the offset (in bytes) that the thread pointer is initialized to
// point to, relative to the start of the thread local storage.
unsigned TlsTpOffset = 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(RelType Type, const uint8_t *Data,
RelExpr Expr) const;
virtual void relaxGot(uint8_t *Loc, uint64_t Val) const;
virtual void relaxTlsGdToIe(uint8_t *Loc, RelType Type, uint64_t Val) const;
virtual void relaxTlsGdToLe(uint8_t *Loc, RelType Type, uint64_t Val) const;
virtual void relaxTlsIeToLe(uint8_t *Loc, RelType Type, uint64_t Val) const;
virtual void relaxTlsLdToLe(uint8_t *Loc, RelType Type, uint64_t Val) const;
protected:
// 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;
};
TargetInfo *getAArch64TargetInfo();
TargetInfo *getAMDGPUTargetInfo();
TargetInfo *getARMTargetInfo();
TargetInfo *getAVRTargetInfo();
TargetInfo *getHexagonTargetInfo();
TargetInfo *getPPC64TargetInfo();
TargetInfo *getPPCTargetInfo();
TargetInfo *getSPARCV9TargetInfo();
TargetInfo *getX32TargetInfo();
TargetInfo *getX86TargetInfo();
TargetInfo *getX86_64TargetInfo();
template <class ELFT> TargetInfo *getMipsTargetInfo();
struct ErrorPlace {
InputSectionBase *IS;
std::string Loc;
};
// Returns input section and corresponding source string for the given location.
ErrorPlace getErrorPlace(const uint8_t *Loc);
static inline std::string getErrorLocation(const uint8_t *Loc) {
return getErrorPlace(Loc).Loc;
}
uint64_t getPPC64TocBase();
uint64_t getAArch64Page(uint64_t Expr);
extern TargetInfo *Target;
TargetInfo *getTarget();
template <class ELFT> bool isMipsPIC(const Defined *Sym);
static inline void reportRangeError(uint8_t *Loc, RelType Type, const Twine &V,
int64_t Min, uint64_t Max) {
ErrorPlace ErrPlace = getErrorPlace(Loc);
StringRef Hint;
if (ErrPlace.IS && ErrPlace.IS->Name.startswith(".debug"))
Hint = "; consider recompiling with -fdebug-types-section to reduce size "
"of debug sections";
error(ErrPlace.Loc + "relocation " + lld::toString(Type) +
" out of range: " + V.str() + " is not in [" + Twine(Min).str() + ", " +
Twine(Max).str() + "]" + Hint);
}
// Sign-extend Nth bit all the way to MSB.
inline int64_t signExtend(uint64_t V, int N) {
return int64_t(V << (64 - N)) >> (64 - N);
}
// Make sure that V can be represented as an N bit signed integer.
inline void checkInt(uint8_t *Loc, int64_t V, int N, RelType Type) {
if (V != signExtend(V, N))
reportRangeError(Loc, Type, Twine(V), llvm::minIntN(N), llvm::maxIntN(N));
}
// Make sure that V can be represented as an N bit unsigned integer.
inline void checkUInt(uint8_t *Loc, uint64_t V, int N, RelType Type) {
if ((V >> N) != 0)
reportRangeError(Loc, Type, Twine(V), 0, llvm::maxUIntN(N));
}
// Make sure that V can be represented as an N bit signed or unsigned integer.
inline void checkIntUInt(uint8_t *Loc, uint64_t V, int N, RelType Type) {
// For the error message we should cast V to a signed integer so that error
// messages show a small negative value rather than an extremely large one
if (V != (uint64_t)signExtend(V, N) && (V >> N) != 0)
reportRangeError(Loc, Type, Twine((int64_t)V), llvm::minIntN(N),
llvm::maxIntN(N));
}
inline void checkAlignment(uint8_t *Loc, uint64_t V, int N, RelType Type) {
if ((V & (N - 1)) != 0)
error(getErrorLocation(Loc) + "improper alignment for relocation " +
lld::toString(Type) + ": 0x" + llvm::utohexstr(V) +
" is not aligned to " + Twine(N) + " bytes");
}
// Endianness-aware read/write.
inline uint16_t read16(const void *P) {
return llvm::support::endian::read16(P, Config->Endianness);
}
inline uint32_t read32(const void *P) {
return llvm::support::endian::read32(P, Config->Endianness);
}
inline uint64_t read64(const void *P) {
return llvm::support::endian::read64(P, Config->Endianness);
}
inline void write16(void *P, uint16_t V) {
llvm::support::endian::write16(P, V, Config->Endianness);
}
inline void write32(void *P, uint32_t V) {
llvm::support::endian::write32(P, V, Config->Endianness);
}
inline void write64(void *P, uint64_t V) {
llvm::support::endian::write64(P, V, Config->Endianness);
}
} // namespace elf
} // namespace lld
#endif