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