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llvm-project/lld/lib/ReaderWriter/MachO/ArchHandler_x86.cpp

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//===- lib/FileFormat/MachO/ArchHandler_x86.cpp ---------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "ArchHandler.h"
#include "Atoms.h"
#include "MachONormalizedFileBinaryUtils.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/ErrorHandling.h"
using namespace llvm::MachO;
using namespace lld::mach_o::normalized;
namespace lld {
namespace mach_o {
using llvm::support::ulittle16_t;
using llvm::support::ulittle32_t;
using llvm::support::little16_t;
using llvm::support::little32_t;
class ArchHandler_x86 : public ArchHandler {
public:
ArchHandler_x86() = default;
~ArchHandler_x86() override = default;
const Registry::KindStrings *kindStrings() override { return _sKindStrings; }
Reference::KindArch kindArch() override { return Reference::KindArch::x86; }
const StubInfo &stubInfo() override { return _sStubInfo; }
bool isCallSite(const Reference &) override;
bool isNonCallBranch(const Reference &) override {
return false;
}
bool isPointer(const Reference &) override;
bool isPairedReloc(const normalized::Relocation &) override;
bool needsCompactUnwind() override {
return false;
}
Reference::KindValue imageOffsetKind() override {
return invalid;
}
Reference::KindValue imageOffsetKindIndirect() override {
return invalid;
}
Reference::KindValue unwindRefToPersonalityFunctionKind() override {
return invalid;
}
Reference::KindValue unwindRefToCIEKind() override {
return negDelta32;
}
Reference::KindValue unwindRefToFunctionKind() override{
return delta32;
}
Reference::KindValue lazyImmediateLocationKind() override {
return lazyImmediateLocation;
}
Reference::KindValue unwindRefToEhFrameKind() override {
return invalid;
}
Reference::KindValue pointerKind() override {
return invalid;
}
uint32_t dwarfCompactUnwindType() override {
return 0x04000000U;
}
llvm::Error getReferenceInfo(const normalized::Relocation &reloc,
const DefinedAtom *inAtom,
uint32_t offsetInAtom,
uint64_t fixupAddress, bool swap,
FindAtomBySectionAndAddress atomFromAddress,
FindAtomBySymbolIndex atomFromSymbolIndex,
Reference::KindValue *kind,
const lld::Atom **target,
Reference::Addend *addend) override;
llvm::Error
getPairReferenceInfo(const normalized::Relocation &reloc1,
const normalized::Relocation &reloc2,
const DefinedAtom *inAtom,
uint32_t offsetInAtom,
uint64_t fixupAddress, bool swap, bool scatterable,
FindAtomBySectionAndAddress atomFromAddress,
FindAtomBySymbolIndex atomFromSymbolIndex,
Reference::KindValue *kind,
const lld::Atom **target,
Reference::Addend *addend) override;
void generateAtomContent(const DefinedAtom &atom, bool relocatable,
FindAddressForAtom findAddress,
FindAddressForAtom findSectionAddress,
uint64_t imageBaseAddress,
llvm::MutableArrayRef<uint8_t> atomContentBuffer) override;
void appendSectionRelocations(const DefinedAtom &atom,
uint64_t atomSectionOffset,
const Reference &ref,
FindSymbolIndexForAtom symbolIndexForAtom,
FindSectionIndexForAtom sectionIndexForAtom,
FindAddressForAtom addressForAtom,
normalized::Relocations &relocs) override;
bool isDataInCodeTransition(Reference::KindValue refKind) override {
return refKind == modeCode || refKind == modeData;
}
Reference::KindValue dataInCodeTransitionStart(
const MachODefinedAtom &atom) override {
return modeData;
}
Reference::KindValue dataInCodeTransitionEnd(
const MachODefinedAtom &atom) override {
return modeCode;
}
private:
static const Registry::KindStrings _sKindStrings[];
static const StubInfo _sStubInfo;
enum X86Kind : Reference::KindValue {
invalid, /// for error condition
modeCode, /// Content starting at this offset is code.
modeData, /// Content starting at this offset is data.
// Kinds found in mach-o .o files:
branch32, /// ex: call _foo
branch16, /// ex: callw _foo
abs32, /// ex: movl _foo, %eax
funcRel32, /// ex: movl _foo-L1(%eax), %eax
pointer32, /// ex: .long _foo
delta32, /// ex: .long _foo - .
negDelta32, /// ex: .long . - _foo
// Kinds introduced by Passes:
lazyPointer, /// Location contains a lazy pointer.
lazyImmediateLocation, /// Location contains immediate value used in stub.
};
static bool useExternalRelocationTo(const Atom &target);
void applyFixupFinal(const Reference &ref, uint8_t *location,
uint64_t fixupAddress, uint64_t targetAddress,
uint64_t inAtomAddress);
void applyFixupRelocatable(const Reference &ref, uint8_t *location,
uint64_t fixupAddress,
uint64_t targetAddress,
uint64_t inAtomAddress);
};
//===----------------------------------------------------------------------===//
// ArchHandler_x86
//===----------------------------------------------------------------------===//
const Registry::KindStrings ArchHandler_x86::_sKindStrings[] = {
LLD_KIND_STRING_ENTRY(invalid),
LLD_KIND_STRING_ENTRY(modeCode),
LLD_KIND_STRING_ENTRY(modeData),
LLD_KIND_STRING_ENTRY(branch32),
LLD_KIND_STRING_ENTRY(branch16),
LLD_KIND_STRING_ENTRY(abs32),
LLD_KIND_STRING_ENTRY(funcRel32),
LLD_KIND_STRING_ENTRY(pointer32),
LLD_KIND_STRING_ENTRY(delta32),
LLD_KIND_STRING_ENTRY(negDelta32),
LLD_KIND_STRING_ENTRY(lazyPointer),
LLD_KIND_STRING_ENTRY(lazyImmediateLocation),
LLD_KIND_STRING_END
};
const ArchHandler::StubInfo ArchHandler_x86::_sStubInfo = {
"dyld_stub_binder",
// Lazy pointer references
{ Reference::KindArch::x86, pointer32, 0, 0 },
{ Reference::KindArch::x86, lazyPointer, 0, 0 },
// GOT pointer to dyld_stub_binder
{ Reference::KindArch::x86, pointer32, 0, 0 },
// x86 code alignment
1,
// Stub size and code
6,
{ 0xff, 0x25, 0x00, 0x00, 0x00, 0x00 }, // jmp *lazyPointer
{ Reference::KindArch::x86, abs32, 2, 0 },
{ false, 0, 0, 0 },
// Stub Helper size and code
10,
{ 0x68, 0x00, 0x00, 0x00, 0x00, // pushl $lazy-info-offset
0xE9, 0x00, 0x00, 0x00, 0x00 }, // jmp helperhelper
{ Reference::KindArch::x86, lazyImmediateLocation, 1, 0 },
{ Reference::KindArch::x86, branch32, 6, 0 },
// Stub helper image cache content type
DefinedAtom::typeNonLazyPointer,
// Stub Helper-Common size and code
12,
// Stub helper alignment
2,
{ 0x68, 0x00, 0x00, 0x00, 0x00, // pushl $dyld_ImageLoaderCache
0xFF, 0x25, 0x00, 0x00, 0x00, 0x00, // jmp *_fast_lazy_bind
0x90 }, // nop
{ Reference::KindArch::x86, abs32, 1, 0 },
{ false, 0, 0, 0 },
{ Reference::KindArch::x86, abs32, 7, 0 },
{ false, 0, 0, 0 }
};
bool ArchHandler_x86::isCallSite(const Reference &ref) {
return (ref.kindValue() == branch32);
}
bool ArchHandler_x86::isPointer(const Reference &ref) {
return (ref.kindValue() == pointer32);
}
bool ArchHandler_x86::isPairedReloc(const Relocation &reloc) {
if (!reloc.scattered)
return false;
return (reloc.type == GENERIC_RELOC_LOCAL_SECTDIFF) ||
(reloc.type == GENERIC_RELOC_SECTDIFF);
}
llvm::Error
ArchHandler_x86::getReferenceInfo(const Relocation &reloc,
const DefinedAtom *inAtom,
uint32_t offsetInAtom,
uint64_t fixupAddress, bool swap,
FindAtomBySectionAndAddress atomFromAddress,
FindAtomBySymbolIndex atomFromSymbolIndex,
Reference::KindValue *kind,
const lld::Atom **target,
Reference::Addend *addend) {
DefinedAtom::ContentPermissions perms;
const uint8_t *fixupContent = &inAtom->rawContent()[offsetInAtom];
uint64_t targetAddress;
switch (relocPattern(reloc)) {
case GENERIC_RELOC_VANILLA | rPcRel | rExtern | rLength4:
// ex: call _foo (and _foo undefined)
*kind = branch32;
if (auto ec = atomFromSymbolIndex(reloc.symbol, target))
return ec;
*addend = fixupAddress + 4 + (int32_t)*(const little32_t *)fixupContent;
break;
case GENERIC_RELOC_VANILLA | rPcRel | rLength4:
// ex: call _foo (and _foo defined)
*kind = branch32;
targetAddress =
fixupAddress + 4 + (int32_t) * (const little32_t *)fixupContent;
return atomFromAddress(reloc.symbol, targetAddress, target, addend);
break;
case GENERIC_RELOC_VANILLA | rScattered | rPcRel | rLength4:
// ex: call _foo+n (and _foo defined)
*kind = branch32;
targetAddress =
fixupAddress + 4 + (int32_t) * (const little32_t *)fixupContent;
if (auto ec = atomFromAddress(0, reloc.value, target, addend))
return ec;
*addend = targetAddress - reloc.value;
break;
case GENERIC_RELOC_VANILLA | rPcRel | rExtern | rLength2:
// ex: callw _foo (and _foo undefined)
*kind = branch16;
if (auto ec = atomFromSymbolIndex(reloc.symbol, target))
return ec;
*addend = fixupAddress + 2 + (int16_t)*(const little16_t *)fixupContent;
break;
case GENERIC_RELOC_VANILLA | rPcRel | rLength2:
// ex: callw _foo (and _foo defined)
*kind = branch16;
targetAddress =
fixupAddress + 2 + (int16_t) * (const little16_t *)fixupContent;
return atomFromAddress(reloc.symbol, targetAddress, target, addend);
break;
case GENERIC_RELOC_VANILLA | rScattered | rPcRel | rLength2:
// ex: callw _foo+n (and _foo defined)
*kind = branch16;
targetAddress =
fixupAddress + 2 + (int16_t) * (const little16_t *)fixupContent;
if (auto ec = atomFromAddress(0, reloc.value, target, addend))
return ec;
*addend = targetAddress - reloc.value;
break;
case GENERIC_RELOC_VANILLA | rExtern | rLength4:
// ex: movl _foo, %eax (and _foo undefined)
// ex: .long _foo (and _foo undefined)
perms = inAtom->permissions();
*kind =
((perms & DefinedAtom::permR_X) == DefinedAtom::permR_X) ? abs32
: pointer32;
if (auto ec = atomFromSymbolIndex(reloc.symbol, target))
return ec;
*addend = *(const ulittle32_t *)fixupContent;
break;
case GENERIC_RELOC_VANILLA | rLength4:
// ex: movl _foo, %eax (and _foo defined)
// ex: .long _foo (and _foo defined)
perms = inAtom->permissions();
*kind =
((perms & DefinedAtom::permR_X) == DefinedAtom::permR_X) ? abs32
: pointer32;
targetAddress = *(const ulittle32_t *)fixupContent;
return atomFromAddress(reloc.symbol, targetAddress, target, addend);
break;
case GENERIC_RELOC_VANILLA | rScattered | rLength4:
// ex: .long _foo+n (and _foo defined)
perms = inAtom->permissions();
*kind =
((perms & DefinedAtom::permR_X) == DefinedAtom::permR_X) ? abs32
: pointer32;
if (auto ec = atomFromAddress(0, reloc.value, target, addend))
return ec;
*addend = *(const ulittle32_t *)fixupContent - reloc.value;
break;
default:
return llvm::make_error<GenericError>("unsupported i386 relocation type");
}
return llvm::Error::success();
}
llvm::Error
ArchHandler_x86::getPairReferenceInfo(const normalized::Relocation &reloc1,
const normalized::Relocation &reloc2,
const DefinedAtom *inAtom,
uint32_t offsetInAtom,
uint64_t fixupAddress, bool swap,
bool scatterable,
FindAtomBySectionAndAddress atomFromAddr,
FindAtomBySymbolIndex atomFromSymbolIndex,
Reference::KindValue *kind,
const lld::Atom **target,
Reference::Addend *addend) {
const uint8_t *fixupContent = &inAtom->rawContent()[offsetInAtom];
DefinedAtom::ContentPermissions perms = inAtom->permissions();
uint32_t fromAddress;
uint32_t toAddress;
uint32_t value;
const lld::Atom *fromTarget;
Reference::Addend offsetInTo;
Reference::Addend offsetInFrom;
switch (relocPattern(reloc1) << 16 | relocPattern(reloc2)) {
case ((GENERIC_RELOC_SECTDIFF | rScattered | rLength4) << 16 |
GENERIC_RELOC_PAIR | rScattered | rLength4):
case ((GENERIC_RELOC_LOCAL_SECTDIFF | rScattered | rLength4) << 16 |
GENERIC_RELOC_PAIR | rScattered | rLength4):
toAddress = reloc1.value;
fromAddress = reloc2.value;
value = *(const little32_t *)fixupContent;
if (auto ec = atomFromAddr(0, toAddress, target, &offsetInTo))
return ec;
if (auto ec = atomFromAddr(0, fromAddress, &fromTarget, &offsetInFrom))
return ec;
if (fromTarget != inAtom) {
if (*target != inAtom)
return llvm::make_error<GenericError>(
"SECTDIFF relocation where neither target is in atom");
*kind = negDelta32;
*addend = toAddress - value - fromAddress;
*target = fromTarget;
} else {
if ((perms & DefinedAtom::permR_X) == DefinedAtom::permR_X) {
// SECTDIFF relocations are used in i386 codegen where the function
// prolog does a CALL to the next instruction which POPs the return
// address into EBX which becomes the pic-base register. The POP
// instruction is label the used for the subtrahend in expressions.
// The funcRel32 kind represents the 32-bit delta to some symbol from
// the start of the function (atom) containing the funcRel32.
*kind = funcRel32;
uint32_t ta = fromAddress + value - toAddress;
*addend = ta - offsetInFrom;
} else {
*kind = delta32;
*addend = fromAddress + value - toAddress;
}
}
return llvm::Error::success();
break;
default:
return llvm::make_error<GenericError>("unsupported i386 relocation type");
}
}
void ArchHandler_x86::generateAtomContent(const DefinedAtom &atom,
bool relocatable,
FindAddressForAtom findAddress,
FindAddressForAtom findSectionAddress,
uint64_t imageBaseAddress,
llvm::MutableArrayRef<uint8_t> atomContentBuffer) {
// Copy raw bytes.
std::copy(atom.rawContent().begin(), atom.rawContent().end(),
atomContentBuffer.begin());
// Apply fix-ups.
for (const Reference *ref : atom) {
uint32_t offset = ref->offsetInAtom();
const Atom *target = ref->target();
uint64_t targetAddress = 0;
if (isa<DefinedAtom>(target))
targetAddress = findAddress(*target);
uint64_t atomAddress = findAddress(atom);
uint64_t fixupAddress = atomAddress + offset;
if (relocatable) {
applyFixupRelocatable(*ref, &atomContentBuffer[offset],
fixupAddress, targetAddress,
atomAddress);
} else {
applyFixupFinal(*ref, &atomContentBuffer[offset],
fixupAddress, targetAddress,
atomAddress);
}
}
}
void ArchHandler_x86::applyFixupFinal(const Reference &ref, uint8_t *loc,
uint64_t fixupAddress,
uint64_t targetAddress,
uint64_t inAtomAddress) {
if (ref.kindNamespace() != Reference::KindNamespace::mach_o)
return;
assert(ref.kindArch() == Reference::KindArch::x86);
ulittle32_t *loc32 = reinterpret_cast<ulittle32_t *>(loc);
switch (static_cast<X86Kind>(ref.kindValue())) {
case branch32:
*loc32 = (targetAddress - (fixupAddress + 4)) + ref.addend();
break;
case branch16:
*loc32 = (targetAddress - (fixupAddress + 2)) + ref.addend();
break;
case pointer32:
case abs32:
*loc32 = targetAddress + ref.addend();
break;
case funcRel32:
*loc32 = targetAddress - inAtomAddress + ref.addend();
break;
case delta32:
*loc32 = targetAddress - fixupAddress + ref.addend();
break;
case negDelta32:
*loc32 = fixupAddress - targetAddress + ref.addend();
break;
case modeCode:
case modeData:
case lazyPointer:
// do nothing
break;
case lazyImmediateLocation:
*loc32 = ref.addend();
break;
case invalid:
llvm_unreachable("invalid x86 Reference Kind");
break;
}
}
void ArchHandler_x86::applyFixupRelocatable(const Reference &ref,
uint8_t *loc,
uint64_t fixupAddress,
uint64_t targetAddress,
uint64_t inAtomAddress) {
if (ref.kindNamespace() != Reference::KindNamespace::mach_o)
return;
assert(ref.kindArch() == Reference::KindArch::x86);
bool useExternalReloc = useExternalRelocationTo(*ref.target());
ulittle16_t *loc16 = reinterpret_cast<ulittle16_t *>(loc);
ulittle32_t *loc32 = reinterpret_cast<ulittle32_t *>(loc);
switch (static_cast<X86Kind>(ref.kindValue())) {
case branch32:
if (useExternalReloc)
*loc32 = ref.addend() - (fixupAddress + 4);
else
*loc32 =(targetAddress - (fixupAddress+4)) + ref.addend();
break;
case branch16:
if (useExternalReloc)
*loc16 = ref.addend() - (fixupAddress + 2);
else
*loc16 = (targetAddress - (fixupAddress+2)) + ref.addend();
break;
case pointer32:
case abs32:
*loc32 = targetAddress + ref.addend();
break;
case funcRel32:
*loc32 = targetAddress - inAtomAddress + ref.addend(); // FIXME
break;
case delta32:
*loc32 = targetAddress - fixupAddress + ref.addend();
break;
case negDelta32:
*loc32 = fixupAddress - targetAddress + ref.addend();
break;
case modeCode:
case modeData:
case lazyPointer:
case lazyImmediateLocation:
// do nothing
break;
case invalid:
llvm_unreachable("invalid x86 Reference Kind");
break;
}
}
bool ArchHandler_x86::useExternalRelocationTo(const Atom &target) {
// Undefined symbols are referenced via external relocations.
if (isa<UndefinedAtom>(&target))
return true;
if (const DefinedAtom *defAtom = dyn_cast<DefinedAtom>(&target)) {
switch (defAtom->merge()) {
case DefinedAtom::mergeAsTentative:
// Tentative definitions are referenced via external relocations.
return true;
case DefinedAtom::mergeAsWeak:
case DefinedAtom::mergeAsWeakAndAddressUsed:
// Global weak-defs are referenced via external relocations.
return (defAtom->scope() == DefinedAtom::scopeGlobal);
default:
break;
}
}
// Everything else is reference via an internal relocation.
return false;
}
void ArchHandler_x86::appendSectionRelocations(
const DefinedAtom &atom,
uint64_t atomSectionOffset,
const Reference &ref,
FindSymbolIndexForAtom symbolIndexForAtom,
FindSectionIndexForAtom sectionIndexForAtom,
FindAddressForAtom addressForAtom,
normalized::Relocations &relocs) {
if (ref.kindNamespace() != Reference::KindNamespace::mach_o)
return;
assert(ref.kindArch() == Reference::KindArch::x86);
uint32_t sectionOffset = atomSectionOffset + ref.offsetInAtom();
bool useExternalReloc = useExternalRelocationTo(*ref.target());
switch (static_cast<X86Kind>(ref.kindValue())) {
case modeCode:
case modeData:
break;
case branch32:
if (useExternalReloc) {
appendReloc(relocs, sectionOffset, symbolIndexForAtom(*ref.target()), 0,
GENERIC_RELOC_VANILLA | rExtern | rPcRel | rLength4);
} else {
if (ref.addend() != 0)
appendReloc(relocs, sectionOffset, 0, addressForAtom(*ref.target()),
GENERIC_RELOC_VANILLA | rScattered | rPcRel | rLength4);
else
appendReloc(relocs, sectionOffset, sectionIndexForAtom(*ref.target()),0,
GENERIC_RELOC_VANILLA | rPcRel | rLength4);
}
break;
case branch16:
if (useExternalReloc) {
appendReloc(relocs, sectionOffset, symbolIndexForAtom(*ref.target()), 0,
GENERIC_RELOC_VANILLA | rExtern | rPcRel | rLength2);
} else {
if (ref.addend() != 0)
appendReloc(relocs, sectionOffset, 0, addressForAtom(*ref.target()),
GENERIC_RELOC_VANILLA | rScattered | rPcRel | rLength2);
else
appendReloc(relocs, sectionOffset, sectionIndexForAtom(*ref.target()),0,
GENERIC_RELOC_VANILLA | rPcRel | rLength2);
}
break;
case pointer32:
case abs32:
if (useExternalReloc)
appendReloc(relocs, sectionOffset, symbolIndexForAtom(*ref.target()), 0,
GENERIC_RELOC_VANILLA | rExtern | rLength4);
else {
if (ref.addend() != 0)
appendReloc(relocs, sectionOffset, 0, addressForAtom(*ref.target()),
GENERIC_RELOC_VANILLA | rScattered | rLength4);
else
appendReloc(relocs, sectionOffset, sectionIndexForAtom(*ref.target()), 0,
GENERIC_RELOC_VANILLA | rLength4);
}
break;
case funcRel32:
appendReloc(relocs, sectionOffset, 0, addressForAtom(*ref.target()),
GENERIC_RELOC_SECTDIFF | rScattered | rLength4);
appendReloc(relocs, sectionOffset, 0, addressForAtom(atom) - ref.addend(),
GENERIC_RELOC_PAIR | rScattered | rLength4);
break;
case delta32:
appendReloc(relocs, sectionOffset, 0, addressForAtom(*ref.target()),
GENERIC_RELOC_SECTDIFF | rScattered | rLength4);
appendReloc(relocs, sectionOffset, 0, addressForAtom(atom) +
ref.offsetInAtom(),
GENERIC_RELOC_PAIR | rScattered | rLength4);
break;
case negDelta32:
appendReloc(relocs, sectionOffset, 0, addressForAtom(atom) +
ref.offsetInAtom(),
GENERIC_RELOC_SECTDIFF | rScattered | rLength4);
appendReloc(relocs, sectionOffset, 0, addressForAtom(*ref.target()),
GENERIC_RELOC_PAIR | rScattered | rLength4);
break;
case lazyPointer:
case lazyImmediateLocation:
llvm_unreachable("lazy reference kind implies Stubs pass was run");
break;
case invalid:
llvm_unreachable("unknown x86 Reference Kind");
break;
}
}
std::unique_ptr<mach_o::ArchHandler> ArchHandler::create_x86() {
return std::unique_ptr<mach_o::ArchHandler>(new ArchHandler_x86());
}
} // namespace mach_o
} // namespace lld
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