5570ce5cef
The object file format specific derived classes are used in context where the type is statically known. We don't use isa/dyn_cast and we want to eliminate MCSymbol::Kind in the base class.
404 lines
12 KiB
C++
404 lines
12 KiB
C++
//===-- X86ELFObjectWriter.cpp - X86 ELF Writer ---------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "MCTargetDesc/X86FixupKinds.h"
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#include "MCTargetDesc/X86MCAsmInfo.h"
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#include "MCTargetDesc/X86MCTargetDesc.h"
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#include "llvm/BinaryFormat/ELF.h"
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#include "llvm/MC/MCAsmInfo.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCELFObjectWriter.h"
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#include "llvm/MC/MCExpr.h"
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#include "llvm/MC/MCFixup.h"
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#include "llvm/MC/MCObjectWriter.h"
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#include "llvm/MC/MCValue.h"
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#include "llvm/Support/ErrorHandling.h"
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#include <cassert>
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#include <cstdint>
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using namespace llvm;
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namespace {
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enum X86_32RelType { RT32_NONE, RT32_32, RT32_16, RT32_8 };
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enum X86_64RelType { RT64_NONE, RT64_64, RT64_32, RT64_32S, RT64_16, RT64_8 };
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class X86ELFObjectWriter : public MCELFObjectTargetWriter {
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public:
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X86ELFObjectWriter(bool IsELF64, uint8_t OSABI, uint16_t EMachine);
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~X86ELFObjectWriter() override = default;
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protected:
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unsigned getRelocType(const MCFixup &, const MCValue &,
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bool IsPCRel) const override;
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bool needsRelocateWithSymbol(const MCValue &, unsigned Type) const override;
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void checkIs32(SMLoc Loc, X86_64RelType Type) const;
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void checkIs64(SMLoc Loc, X86_64RelType Type) const;
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unsigned getRelocType32(SMLoc Loc, X86::Specifier Specifier,
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X86_32RelType Type, bool IsPCRel,
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MCFixupKind Kind) const;
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unsigned getRelocType64(SMLoc Loc, X86::Specifier Specifier,
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X86_64RelType Type, bool IsPCRel,
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MCFixupKind Kind) const;
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};
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} // end anonymous namespace
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X86ELFObjectWriter::X86ELFObjectWriter(bool IsELF64, uint8_t OSABI,
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uint16_t EMachine)
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: MCELFObjectTargetWriter(IsELF64, OSABI, EMachine,
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// Only i386 and IAMCU use Rel instead of RelA.
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/*HasRelocationAddend*/
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(EMachine != ELF::EM_386) &&
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(EMachine != ELF::EM_IAMCU)) {}
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static X86_64RelType getType64(MCFixupKind Kind, X86::Specifier &Specifier,
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bool &IsPCRel) {
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switch (unsigned(Kind)) {
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default:
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llvm_unreachable("Unimplemented");
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case FK_NONE:
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return RT64_NONE;
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case FK_Data_8:
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return RT64_64;
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case X86::reloc_signed_4byte:
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case X86::reloc_signed_4byte_relax:
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if (Specifier == X86::S_None && !IsPCRel)
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return RT64_32S;
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return RT64_32;
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case X86::reloc_global_offset_table:
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Specifier = X86::S_GOT;
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IsPCRel = true;
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return RT64_32;
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case FK_Data_4:
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case X86::reloc_riprel_4byte:
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case X86::reloc_riprel_4byte_relax:
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case X86::reloc_riprel_4byte_relax_rex:
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case X86::reloc_riprel_4byte_relax_rex2:
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case X86::reloc_riprel_4byte_movq_load:
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case X86::reloc_riprel_4byte_movq_load_rex2:
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case X86::reloc_riprel_4byte_relax_evex:
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return RT64_32;
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case X86::reloc_branch_4byte_pcrel:
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Specifier = X86::S_PLT;
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return RT64_32;
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case FK_Data_2:
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return RT64_16;
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case FK_Data_1:
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return RT64_8;
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}
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}
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void X86ELFObjectWriter::checkIs32(SMLoc Loc, X86_64RelType Type) const {
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if (Type != RT64_32)
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reportError(Loc, "32 bit reloc applied to a field with a different size");
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}
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void X86ELFObjectWriter::checkIs64(SMLoc Loc, X86_64RelType Type) const {
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if (Type != RT64_64)
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reportError(Loc, "64 bit reloc applied to a field with a different size");
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}
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unsigned X86ELFObjectWriter::getRelocType64(SMLoc Loc, X86::Specifier Specifier,
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X86_64RelType Type, bool IsPCRel,
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MCFixupKind Kind) const {
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switch (Specifier) {
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default:
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llvm_unreachable("Unimplemented");
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case X86::S_None:
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case X86::S_ABS8:
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switch (Type) {
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case RT64_NONE:
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if (Specifier == X86::S_None)
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return ELF::R_X86_64_NONE;
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llvm_unreachable("Unimplemented");
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case RT64_64:
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return IsPCRel ? ELF::R_X86_64_PC64 : ELF::R_X86_64_64;
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case RT64_32:
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return IsPCRel ? ELF::R_X86_64_PC32 : ELF::R_X86_64_32;
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case RT64_32S:
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return ELF::R_X86_64_32S;
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case RT64_16:
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return IsPCRel ? ELF::R_X86_64_PC16 : ELF::R_X86_64_16;
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case RT64_8:
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return IsPCRel ? ELF::R_X86_64_PC8 : ELF::R_X86_64_8;
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}
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llvm_unreachable("unexpected relocation type!");
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case X86::S_GOT:
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switch (Type) {
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case RT64_64:
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return IsPCRel ? ELF::R_X86_64_GOTPC64 : ELF::R_X86_64_GOT64;
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case RT64_32:
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return IsPCRel ? ELF::R_X86_64_GOTPC32 : ELF::R_X86_64_GOT32;
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case RT64_32S:
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case RT64_16:
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case RT64_8:
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case RT64_NONE:
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llvm_unreachable("Unimplemented");
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}
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llvm_unreachable("unexpected relocation type!");
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case X86::S_GOTOFF:
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assert(!IsPCRel);
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if (Type != RT64_64)
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reportError(Loc, "unsupported relocation type");
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return ELF::R_X86_64_GOTOFF64;
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case X86::S_TPOFF:
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assert(!IsPCRel);
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switch (Type) {
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case RT64_64:
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return ELF::R_X86_64_TPOFF64;
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case RT64_32:
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return ELF::R_X86_64_TPOFF32;
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case RT64_32S:
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case RT64_16:
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case RT64_8:
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case RT64_NONE:
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llvm_unreachable("Unimplemented");
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}
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llvm_unreachable("unexpected relocation type!");
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case X86::S_DTPOFF:
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assert(!IsPCRel);
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switch (Type) {
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case RT64_64:
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return ELF::R_X86_64_DTPOFF64;
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case RT64_32:
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return ELF::R_X86_64_DTPOFF32;
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case RT64_32S:
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case RT64_16:
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case RT64_8:
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case RT64_NONE:
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llvm_unreachable("Unimplemented");
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}
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llvm_unreachable("unexpected relocation type!");
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case X86::S_SIZE:
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assert(!IsPCRel);
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switch (Type) {
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case RT64_64:
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return ELF::R_X86_64_SIZE64;
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case RT64_32:
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return ELF::R_X86_64_SIZE32;
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case RT64_32S:
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case RT64_16:
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case RT64_8:
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case RT64_NONE:
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llvm_unreachable("Unimplemented");
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}
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llvm_unreachable("unexpected relocation type!");
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case X86::S_TLSCALL:
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return ELF::R_X86_64_TLSDESC_CALL;
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case X86::S_TLSDESC:
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return ((unsigned)Kind == X86::reloc_riprel_4byte_relax_rex2)
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? ELF::R_X86_64_CODE_4_GOTPC32_TLSDESC
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: ELF::R_X86_64_GOTPC32_TLSDESC;
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case X86::S_TLSGD:
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checkIs32(Loc, Type);
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return ELF::R_X86_64_TLSGD;
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case X86::S_GOTTPOFF:
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checkIs32(Loc, Type);
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if ((unsigned)Kind == X86::reloc_riprel_4byte_movq_load_rex2 ||
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(unsigned)Kind == X86::reloc_riprel_4byte_relax_rex2)
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return ELF::R_X86_64_CODE_4_GOTTPOFF;
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else if ((unsigned)Kind == X86::reloc_riprel_4byte_relax_evex)
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return ELF::R_X86_64_CODE_6_GOTTPOFF;
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return ELF::R_X86_64_GOTTPOFF;
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case X86::S_TLSLD:
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checkIs32(Loc, Type);
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return ELF::R_X86_64_TLSLD;
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case X86::S_PLT:
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checkIs32(Loc, Type);
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return ELF::R_X86_64_PLT32;
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case X86::S_GOTPCREL:
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checkIs32(Loc, Type);
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// Older versions of ld.bfd/ld.gold/lld
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// do not support GOTPCRELX/REX_GOTPCRELX/CODE_4_GOTPCRELX,
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// and we want to keep back-compatibility.
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if (!getContext().getTargetOptions()->X86RelaxRelocations)
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return ELF::R_X86_64_GOTPCREL;
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switch (unsigned(Kind)) {
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default:
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return ELF::R_X86_64_GOTPCREL;
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case X86::reloc_riprel_4byte_relax:
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return ELF::R_X86_64_GOTPCRELX;
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case X86::reloc_riprel_4byte_relax_rex:
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case X86::reloc_riprel_4byte_movq_load:
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return ELF::R_X86_64_REX_GOTPCRELX;
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case X86::reloc_riprel_4byte_relax_rex2:
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case X86::reloc_riprel_4byte_movq_load_rex2:
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return ELF::R_X86_64_CODE_4_GOTPCRELX;
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}
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llvm_unreachable("unexpected relocation type!");
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case X86::S_GOTPCREL_NORELAX:
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checkIs32(Loc, Type);
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return ELF::R_X86_64_GOTPCREL;
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case X86::S_PLTOFF:
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checkIs64(Loc, Type);
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return ELF::R_X86_64_PLTOFF64;
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}
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}
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unsigned X86ELFObjectWriter::getRelocType32(SMLoc Loc, X86::Specifier Specifier,
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X86_32RelType Type, bool IsPCRel,
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MCFixupKind Kind) const {
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switch (Specifier) {
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default:
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llvm_unreachable("Unimplemented");
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case X86::S_None:
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case X86::S_ABS8:
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switch (Type) {
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case RT32_NONE:
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if (Specifier == X86::S_None)
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return ELF::R_386_NONE;
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llvm_unreachable("Unimplemented");
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case RT32_32:
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return IsPCRel ? ELF::R_386_PC32 : ELF::R_386_32;
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case RT32_16:
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return IsPCRel ? ELF::R_386_PC16 : ELF::R_386_16;
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case RT32_8:
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return IsPCRel ? ELF::R_386_PC8 : ELF::R_386_8;
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}
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llvm_unreachable("unexpected relocation type!");
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case X86::S_GOT:
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if (Type != RT32_32)
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break;
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if (IsPCRel)
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return ELF::R_386_GOTPC;
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// Older versions of ld.bfd/ld.gold/lld do not support R_386_GOT32X and we
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// want to maintain compatibility.
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if (!getContext().getTargetOptions()->X86RelaxRelocations)
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return ELF::R_386_GOT32;
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return Kind == X86::reloc_signed_4byte_relax ? ELF::R_386_GOT32X
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: ELF::R_386_GOT32;
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case X86::S_GOTOFF:
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assert(!IsPCRel);
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if (Type != RT32_32)
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break;
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return ELF::R_386_GOTOFF;
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case X86::S_TLSCALL:
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return ELF::R_386_TLS_DESC_CALL;
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case X86::S_TLSDESC:
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return ELF::R_386_TLS_GOTDESC;
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case X86::S_TPOFF:
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if (Type != RT32_32)
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break;
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assert(!IsPCRel);
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return ELF::R_386_TLS_LE_32;
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case X86::S_DTPOFF:
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if (Type != RT32_32)
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break;
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assert(!IsPCRel);
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return ELF::R_386_TLS_LDO_32;
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case X86::S_TLSGD:
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if (Type != RT32_32)
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break;
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assert(!IsPCRel);
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return ELF::R_386_TLS_GD;
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case X86::S_GOTTPOFF:
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if (Type != RT32_32)
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break;
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assert(!IsPCRel);
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return ELF::R_386_TLS_IE_32;
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case X86::S_PLT:
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if (Type != RT32_32)
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break;
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return ELF::R_386_PLT32;
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case X86::S_INDNTPOFF:
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if (Type != RT32_32)
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break;
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assert(!IsPCRel);
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return ELF::R_386_TLS_IE;
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case X86::S_NTPOFF:
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if (Type != RT32_32)
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break;
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assert(!IsPCRel);
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return ELF::R_386_TLS_LE;
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case X86::S_GOTNTPOFF:
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if (Type != RT32_32)
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break;
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assert(!IsPCRel);
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return ELF::R_386_TLS_GOTIE;
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case X86::S_TLSLDM:
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if (Type != RT32_32)
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break;
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assert(!IsPCRel);
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return ELF::R_386_TLS_LDM;
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}
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reportError(Loc, "unsupported relocation type");
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return ELF::R_386_NONE;
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}
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unsigned X86ELFObjectWriter::getRelocType(const MCFixup &Fixup,
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const MCValue &Target,
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bool IsPCRel) const {
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MCFixupKind Kind = Fixup.getKind();
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auto Specifier = X86::Specifier(Target.getSpecifier());
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switch (Specifier) {
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case X86::S_GOTTPOFF:
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case X86::S_INDNTPOFF:
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case X86::S_NTPOFF:
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case X86::S_GOTNTPOFF:
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case X86::S_TLSCALL:
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case X86::S_TLSDESC:
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case X86::S_TLSGD:
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case X86::S_TLSLD:
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case X86::S_TLSLDM:
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case X86::S_TPOFF:
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case X86::S_DTPOFF:
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if (auto *S = const_cast<MCSymbol *>(Target.getAddSym()))
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static_cast<MCSymbolELF *>(S)->setType(ELF::STT_TLS);
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break;
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default:
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break;
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}
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X86_64RelType Type = getType64(Kind, Specifier, IsPCRel);
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if (getEMachine() == ELF::EM_X86_64)
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return getRelocType64(Fixup.getLoc(), Specifier, Type, IsPCRel, Kind);
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assert((getEMachine() == ELF::EM_386 || getEMachine() == ELF::EM_IAMCU) &&
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"Unsupported ELF machine type.");
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X86_32RelType RelType = RT32_NONE;
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switch (Type) {
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case RT64_NONE:
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break;
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case RT64_64:
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reportError(Fixup.getLoc(), "unsupported relocation type");
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return ELF::R_386_NONE;
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case RT64_32:
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case RT64_32S:
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RelType = RT32_32;
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break;
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case RT64_16:
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RelType = RT32_16;
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break;
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case RT64_8:
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RelType = RT32_8;
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break;
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}
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return getRelocType32(Fixup.getLoc(), Specifier, RelType, IsPCRel, Kind);
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}
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bool X86ELFObjectWriter::needsRelocateWithSymbol(const MCValue &V,
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unsigned Type) const {
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switch (V.getSpecifier()) {
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case X86::S_GOT:
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case X86::S_PLT:
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case X86::S_GOTPCREL:
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case X86::S_GOTPCREL_NORELAX:
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return true;
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default:
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return false;
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}
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}
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std::unique_ptr<MCObjectTargetWriter>
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llvm::createX86ELFObjectWriter(bool IsELF64, uint8_t OSABI, uint16_t EMachine) {
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return std::make_unique<X86ELFObjectWriter>(IsELF64, OSABI, EMachine);
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}
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