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//===-- RuntimeDyldELF.cpp - Run-time dynamic linker for MC-JIT -*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// Implementation of ELF support for the MC-JIT runtime dynamic linker.
//
//===----------------------------------------------------------------------===//
#include "RuntimeDyldELF.h"
#include "RuntimeDyldCheckerImpl.h"
#include "Targets/RuntimeDyldELFMips.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/Object/ELFObjectFile.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/TargetParser/Triple.h"
using namespace llvm;
using namespace llvm::object;
using namespace llvm::support::endian;
#define DEBUG_TYPE "dyld"
static void or32le(void *P, int32_t V) { write32le(P, read32le(P) | V); }
static void or32AArch64Imm(void *L, uint64_t Imm) {
or32le(L, (Imm & 0xFFF) << 10);
}
template <class T> static void write(bool isBE, void *P, T V) {
isBE ? write<T, llvm::endianness::big>(P, V)
: write<T, llvm::endianness::little>(P, V);
}
static void write32AArch64Addr(void *L, uint64_t Imm) {
uint32_t ImmLo = (Imm & 0x3) << 29;
uint32_t ImmHi = (Imm & 0x1FFFFC) << 3;
uint64_t Mask = (0x3 << 29) | (0x1FFFFC << 3);
write32le(L, (read32le(L) & ~Mask) | ImmLo | ImmHi);
}
// Return the bits [Start, End] from Val shifted Start bits.
// For instance, getBits(0xF0, 4, 8) returns 0xF.
static uint64_t getBits(uint64_t Val, int Start, int End) {
uint64_t Mask = ((uint64_t)1 << (End + 1 - Start)) - 1;
return (Val >> Start) & Mask;
}
namespace {
template <class ELFT> class DyldELFObject : public ELFObjectFile<ELFT> {
LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
typedef typename ELFT::uint addr_type;
DyldELFObject(ELFObjectFile<ELFT> &&Obj);
public:
static Expected<std::unique_ptr<DyldELFObject>>
create(MemoryBufferRef Wrapper);
void updateSectionAddress(const SectionRef &Sec, uint64_t Addr);
void updateSymbolAddress(const SymbolRef &SymRef, uint64_t Addr);
// Methods for type inquiry through isa, cast and dyn_cast
static bool classof(const Binary *v) {
return (isa<ELFObjectFile<ELFT>>(v) &&
classof(cast<ELFObjectFile<ELFT>>(v)));
}
static bool classof(const ELFObjectFile<ELFT> *v) {
return v->isDyldType();
}
};
// The MemoryBuffer passed into this constructor is just a wrapper around the
// actual memory. Ultimately, the Binary parent class will take ownership of
// this MemoryBuffer object but not the underlying memory.
template <class ELFT>
DyldELFObject<ELFT>::DyldELFObject(ELFObjectFile<ELFT> &&Obj)
: ELFObjectFile<ELFT>(std::move(Obj)) {
this->isDyldELFObject = true;
}
template <class ELFT>
Expected<std::unique_ptr<DyldELFObject<ELFT>>>
DyldELFObject<ELFT>::create(MemoryBufferRef Wrapper) {
auto Obj = ELFObjectFile<ELFT>::create(Wrapper);
if (auto E = Obj.takeError())
return std::move(E);
std::unique_ptr<DyldELFObject<ELFT>> Ret(
new DyldELFObject<ELFT>(std::move(*Obj)));
return std::move(Ret);
}
template <class ELFT>
void DyldELFObject<ELFT>::updateSectionAddress(const SectionRef &Sec,
uint64_t Addr) {
DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
Elf_Shdr *shdr =
const_cast<Elf_Shdr *>(reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
// This assumes the address passed in matches the target address bitness
// The template-based type cast handles everything else.
shdr->sh_addr = static_cast<addr_type>(Addr);
}
template <class ELFT>
void DyldELFObject<ELFT>::updateSymbolAddress(const SymbolRef &SymRef,
uint64_t Addr) {
Elf_Sym *sym = const_cast<Elf_Sym *>(
ELFObjectFile<ELFT>::getSymbol(SymRef.getRawDataRefImpl()));
// This assumes the address passed in matches the target address bitness
// The template-based type cast handles everything else.
sym->st_value = static_cast<addr_type>(Addr);
}
class LoadedELFObjectInfo final
: public LoadedObjectInfoHelper<LoadedELFObjectInfo,
RuntimeDyld::LoadedObjectInfo> {
public:
LoadedELFObjectInfo(RuntimeDyldImpl &RTDyld, ObjSectionToIDMap ObjSecToIDMap)
: LoadedObjectInfoHelper(RTDyld, std::move(ObjSecToIDMap)) {}
OwningBinary<ObjectFile>
getObjectForDebug(const ObjectFile &Obj) const override;
};
template <typename ELFT>
static Expected<std::unique_ptr<DyldELFObject<ELFT>>>
createRTDyldELFObject(MemoryBufferRef Buffer, const ObjectFile &SourceObject,
const LoadedELFObjectInfo &L) {
typedef typename ELFT::Shdr Elf_Shdr;
typedef typename ELFT::uint addr_type;
Expected<std::unique_ptr<DyldELFObject<ELFT>>> ObjOrErr =
DyldELFObject<ELFT>::create(Buffer);
if (Error E = ObjOrErr.takeError())
return std::move(E);
std::unique_ptr<DyldELFObject<ELFT>> Obj = std::move(*ObjOrErr);
// Iterate over all sections in the object.
auto SI = SourceObject.section_begin();
for (const auto &Sec : Obj->sections()) {
Expected<StringRef> NameOrErr = Sec.getName();
if (!NameOrErr) {
consumeError(NameOrErr.takeError());
continue;
}
if (*NameOrErr != "") {
DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
Elf_Shdr *shdr = const_cast<Elf_Shdr *>(
reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
if (uint64_t SecLoadAddr = L.getSectionLoadAddress(*SI)) {
// This assumes that the address passed in matches the target address
// bitness. The template-based type cast handles everything else.
shdr->sh_addr = static_cast<addr_type>(SecLoadAddr);
}
}
++SI;
}
return std::move(Obj);
}
static OwningBinary<ObjectFile>
createELFDebugObject(const ObjectFile &Obj, const LoadedELFObjectInfo &L) {
assert(Obj.isELF() && "Not an ELF object file.");
std::unique_ptr<MemoryBuffer> Buffer =
MemoryBuffer::getMemBufferCopy(Obj.getData(), Obj.getFileName());
Expected<std::unique_ptr<ObjectFile>> DebugObj(nullptr);
handleAllErrors(DebugObj.takeError());
if (Obj.getBytesInAddress() == 4 && Obj.isLittleEndian())
DebugObj =
createRTDyldELFObject<ELF32LE>(Buffer->getMemBufferRef(), Obj, L);
else if (Obj.getBytesInAddress() == 4 && !Obj.isLittleEndian())
DebugObj =
createRTDyldELFObject<ELF32BE>(Buffer->getMemBufferRef(), Obj, L);
else if (Obj.getBytesInAddress() == 8 && !Obj.isLittleEndian())
DebugObj =
createRTDyldELFObject<ELF64BE>(Buffer->getMemBufferRef(), Obj, L);
else if (Obj.getBytesInAddress() == 8 && Obj.isLittleEndian())
DebugObj =
createRTDyldELFObject<ELF64LE>(Buffer->getMemBufferRef(), Obj, L);
else
llvm_unreachable("Unexpected ELF format");
handleAllErrors(DebugObj.takeError());
return OwningBinary<ObjectFile>(std::move(*DebugObj), std::move(Buffer));
}
OwningBinary<ObjectFile>
LoadedELFObjectInfo::getObjectForDebug(const ObjectFile &Obj) const {
return createELFDebugObject(Obj, *this);
}
} // anonymous namespace
namespace llvm {
RuntimeDyldELF::RuntimeDyldELF(RuntimeDyld::MemoryManager &MemMgr,
JITSymbolResolver &Resolver)
: RuntimeDyldImpl(MemMgr, Resolver), GOTSectionID(0), CurrentGOTIndex(0) {}
RuntimeDyldELF::~RuntimeDyldELF() = default;
void RuntimeDyldELF::registerEHFrames() {
for (int i = 0, e = UnregisteredEHFrameSections.size(); i != e; ++i) {
SID EHFrameSID = UnregisteredEHFrameSections[i];
uint8_t *EHFrameAddr = Sections[EHFrameSID].getAddress();
uint64_t EHFrameLoadAddr = Sections[EHFrameSID].getLoadAddress();
size_t EHFrameSize = Sections[EHFrameSID].getSize();
MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
}
UnregisteredEHFrameSections.clear();
}
std::unique_ptr<RuntimeDyldELF>
llvm::RuntimeDyldELF::create(Triple::ArchType Arch,
RuntimeDyld::MemoryManager &MemMgr,
JITSymbolResolver &Resolver) {
switch (Arch) {
default:
return std::make_unique<RuntimeDyldELF>(MemMgr, Resolver);
case Triple::mips:
case Triple::mipsel:
case Triple::mips64:
case Triple::mips64el:
return std::make_unique<RuntimeDyldELFMips>(MemMgr, Resolver);
}
}
std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
RuntimeDyldELF::loadObject(const object::ObjectFile &O) {
if (auto ObjSectionToIDOrErr = loadObjectImpl(O))
return std::make_unique<LoadedELFObjectInfo>(*this, *ObjSectionToIDOrErr);
else {
HasError = true;
raw_string_ostream ErrStream(ErrorStr);
logAllUnhandledErrors(ObjSectionToIDOrErr.takeError(), ErrStream);
return nullptr;
}
}
void RuntimeDyldELF::resolveX86_64Relocation(const SectionEntry &Section,
uint64_t Offset, uint64_t Value,
uint32_t Type, int64_t Addend,
uint64_t SymOffset) {
switch (Type) {
default:
report_fatal_error("Relocation type not implemented yet!");
break;
case ELF::R_X86_64_NONE:
break;
case ELF::R_X86_64_8: {
Value += Addend;
assert((int64_t)Value <= INT8_MAX && (int64_t)Value >= INT8_MIN);
uint8_t TruncatedAddr = (Value & 0xFF);
*Section.getAddressWithOffset(Offset) = TruncatedAddr;
LLVM_DEBUG(dbgs() << "Writing " << format("%p", TruncatedAddr) << " at "
<< format("%p\n", Section.getAddressWithOffset(Offset)));
break;
}
case ELF::R_X86_64_16: {
Value += Addend;
assert((int64_t)Value <= INT16_MAX && (int64_t)Value >= INT16_MIN);
uint16_t TruncatedAddr = (Value & 0xFFFF);
support::ulittle16_t::ref(Section.getAddressWithOffset(Offset)) =
TruncatedAddr;
LLVM_DEBUG(dbgs() << "Writing " << format("%p", TruncatedAddr) << " at "
<< format("%p\n", Section.getAddressWithOffset(Offset)));
break;
}
case ELF::R_X86_64_64: {
support::ulittle64_t::ref(Section.getAddressWithOffset(Offset)) =
Value + Addend;
LLVM_DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at "
<< format("%p\n", Section.getAddressWithOffset(Offset)));
break;
}
case ELF::R_X86_64_32:
case ELF::R_X86_64_32S: {
Value += Addend;
assert((Type == ELF::R_X86_64_32 && (Value <= UINT32_MAX)) ||
(Type == ELF::R_X86_64_32S &&
((int64_t)Value <= INT32_MAX && (int64_t)Value >= INT32_MIN)));
uint32_t TruncatedAddr = (Value & 0xFFFFFFFF);
support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
TruncatedAddr;
LLVM_DEBUG(dbgs() << "Writing " << format("%p", TruncatedAddr) << " at "
<< format("%p\n", Section.getAddressWithOffset(Offset)));
break;
}
case ELF::R_X86_64_PC8: {
uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
int64_t RealOffset = Value + Addend - FinalAddress;
assert(isInt<8>(RealOffset));
int8_t TruncOffset = (RealOffset & 0xFF);
Section.getAddress()[Offset] = TruncOffset;
break;
}
case ELF::R_X86_64_PC32: {
uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
int64_t RealOffset = Value + Addend - FinalAddress;
assert(isInt<32>(RealOffset));
int32_t TruncOffset = (RealOffset & 0xFFFFFFFF);
support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
TruncOffset;
break;
}
case ELF::R_X86_64_PC64: {
uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
int64_t RealOffset = Value + Addend - FinalAddress;
support::ulittle64_t::ref(Section.getAddressWithOffset(Offset)) =
RealOffset;
LLVM_DEBUG(dbgs() << "Writing " << format("%p", RealOffset) << " at "
<< format("%p\n", FinalAddress));
break;
}
case ELF::R_X86_64_GOTOFF64: {
// Compute Value - GOTBase.
uint64_t GOTBase = 0;
for (const auto &Section : Sections) {
if (Section.getName() == ".got") {
GOTBase = Section.getLoadAddressWithOffset(0);
break;
}
}
assert(GOTBase != 0 && "missing GOT");
int64_t GOTOffset = Value - GOTBase + Addend;
support::ulittle64_t::ref(Section.getAddressWithOffset(Offset)) = GOTOffset;
break;
}
case ELF::R_X86_64_DTPMOD64: {
// We only have one DSO, so the module id is always 1.
support::ulittle64_t::ref(Section.getAddressWithOffset(Offset)) = 1;
break;
}
case ELF::R_X86_64_DTPOFF64:
case ELF::R_X86_64_TPOFF64: {
// DTPOFF64 should resolve to the offset in the TLS block, TPOFF64 to the
// offset in the *initial* TLS block. Since we are statically linking, all
// TLS blocks already exist in the initial block, so resolve both
// relocations equally.
support::ulittle64_t::ref(Section.getAddressWithOffset(Offset)) =
Value + Addend;
break;
}
case ELF::R_X86_64_DTPOFF32:
case ELF::R_X86_64_TPOFF32: {
// As for the (D)TPOFF64 relocations above, both DTPOFF32 and TPOFF32 can
// be resolved equally.
int64_t RealValue = Value + Addend;
assert(RealValue >= INT32_MIN && RealValue <= INT32_MAX);
int32_t TruncValue = RealValue;
support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
TruncValue;
break;
}
}
}
void RuntimeDyldELF::resolveX86Relocation(const SectionEntry &Section,
uint64_t Offset, uint32_t Value,
uint32_t Type, int32_t Addend) {
switch (Type) {
case ELF::R_386_32: {
support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
Value + Addend;
break;
}
// Handle R_386_PLT32 like R_386_PC32 since it should be able to
// reach any 32 bit address.
case ELF::R_386_PLT32:
case ELF::R_386_PC32: {
uint32_t FinalAddress =
Section.getLoadAddressWithOffset(Offset) & 0xFFFFFFFF;
uint32_t RealOffset = Value + Addend - FinalAddress;
support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
RealOffset;
break;
}
default:
// There are other relocation types, but it appears these are the
// only ones currently used by the LLVM ELF object writer
report_fatal_error("Relocation type not implemented yet!");
break;
}
}
void RuntimeDyldELF::resolveAArch64Relocation(const SectionEntry &Section,
uint64_t Offset, uint64_t Value,
uint32_t Type, int64_t Addend) {
uint32_t *TargetPtr =
reinterpret_cast<uint32_t *>(Section.getAddressWithOffset(Offset));
uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
// Data should use target endian. Code should always use little endian.
bool isBE = Arch == Triple::aarch64_be;
LLVM_DEBUG(dbgs() << "resolveAArch64Relocation, LocalAddress: 0x"
<< format("%llx", Section.getAddressWithOffset(Offset))
<< " FinalAddress: 0x" << format("%llx", FinalAddress)
<< " Value: 0x" << format("%llx", Value) << " Type: 0x"
<< format("%x", Type) << " Addend: 0x"
<< format("%llx", Addend) << "\n");
switch (Type) {
default:
report_fatal_error("Relocation type not implemented yet!");
break;
case ELF::R_AARCH64_NONE:
break;
case ELF::R_AARCH64_ABS16: {
uint64_t Result = Value + Addend;
assert(Result == static_cast<uint64_t>(llvm::SignExtend64(Result, 16)) ||
(Result >> 16) == 0);
write(isBE, TargetPtr, static_cast<uint16_t>(Result & 0xffffU));
break;
}
case ELF::R_AARCH64_ABS32: {
uint64_t Result = Value + Addend;
assert(Result == static_cast<uint64_t>(llvm::SignExtend64(Result, 32)) ||
(Result >> 32) == 0);
write(isBE, TargetPtr, static_cast<uint32_t>(Result & 0xffffffffU));
break;
}
case ELF::R_AARCH64_ABS64:
write(isBE, TargetPtr, Value + Addend);
break;
case ELF::R_AARCH64_PLT32: {
uint64_t Result = Value + Addend - FinalAddress;
assert(static_cast<int64_t>(Result) >= INT32_MIN &&
static_cast<int64_t>(Result) <= INT32_MAX);
write(isBE, TargetPtr, static_cast<uint32_t>(Result));
break;
}
case ELF::R_AARCH64_PREL16: {
uint64_t Result = Value + Addend - FinalAddress;
assert(static_cast<int64_t>(Result) >= INT16_MIN &&
static_cast<int64_t>(Result) <= UINT16_MAX);
write(isBE, TargetPtr, static_cast<uint16_t>(Result & 0xffffU));
break;
}
case ELF::R_AARCH64_PREL32: {
uint64_t Result = Value + Addend - FinalAddress;
assert(static_cast<int64_t>(Result) >= INT32_MIN &&
static_cast<int64_t>(Result) <= UINT32_MAX);
write(isBE, TargetPtr, static_cast<uint32_t>(Result & 0xffffffffU));
break;
}
case ELF::R_AARCH64_PREL64:
write(isBE, TargetPtr, Value + Addend - FinalAddress);
break;
case ELF::R_AARCH64_CONDBR19: {
uint64_t BranchImm = Value + Addend - FinalAddress;
assert(isInt<21>(BranchImm));
*TargetPtr &= 0xff00001fU;
// Immediate:20:2 goes in bits 23:5 of Bcc, CBZ, CBNZ
or32le(TargetPtr, (BranchImm & 0x001FFFFC) << 3);
break;
}
case ELF::R_AARCH64_TSTBR14: {
uint64_t BranchImm = Value + Addend - FinalAddress;
assert(isInt<16>(BranchImm));
uint32_t RawInstr = *(support::little32_t *)TargetPtr;
*(support::little32_t *)TargetPtr = RawInstr & 0xfff8001fU;
// Immediate:15:2 goes in bits 18:5 of TBZ, TBNZ
or32le(TargetPtr, (BranchImm & 0x0000FFFC) << 3);
break;
}
case ELF::R_AARCH64_CALL26: // fallthrough
case ELF::R_AARCH64_JUMP26: {
// Operation: S+A-P. Set Call or B immediate value to bits fff_fffc of the
// calculation.
uint64_t BranchImm = Value + Addend - FinalAddress;
// "Check that -2^27 <= result < 2^27".
assert(isInt<28>(BranchImm));
or32le(TargetPtr, (BranchImm & 0x0FFFFFFC) >> 2);
break;
}
case ELF::R_AARCH64_MOVW_UABS_G3:
or32le(TargetPtr, ((Value + Addend) & 0xFFFF000000000000) >> 43);
break;
case ELF::R_AARCH64_MOVW_UABS_G2_NC:
or32le(TargetPtr, ((Value + Addend) & 0xFFFF00000000) >> 27);
break;
case ELF::R_AARCH64_MOVW_UABS_G1_NC:
or32le(TargetPtr, ((Value + Addend) & 0xFFFF0000) >> 11);
break;
case ELF::R_AARCH64_MOVW_UABS_G0_NC:
or32le(TargetPtr, ((Value + Addend) & 0xFFFF) << 5);
break;
case ELF::R_AARCH64_ADR_PREL_PG_HI21: {
// Operation: Page(S+A) - Page(P)
uint64_t Result =
((Value + Addend) & ~0xfffULL) - (FinalAddress & ~0xfffULL);
// Check that -2^32 <= X < 2^32
assert(isInt<33>(Result) && "overflow check failed for relocation");
// Immediate goes in bits 30:29 + 5:23 of ADRP instruction, taken
// from bits 32:12 of X.
write32AArch64Addr(TargetPtr, Result >> 12);
break;
}
case ELF::R_AARCH64_ADD_ABS_LO12_NC:
// Operation: S + A
// Immediate goes in bits 21:10 of LD/ST instruction, taken
// from bits 11:0 of X
or32AArch64Imm(TargetPtr, Value + Addend);
break;
case ELF::R_AARCH64_LDST8_ABS_LO12_NC:
// Operation: S + A
// Immediate goes in bits 21:10 of LD/ST instruction, taken
// from bits 11:0 of X
or32AArch64Imm(TargetPtr, getBits(Value + Addend, 0, 11));
break;
case ELF::R_AARCH64_LDST16_ABS_LO12_NC:
// Operation: S + A
// Immediate goes in bits 21:10 of LD/ST instruction, taken
// from bits 11:1 of X
or32AArch64Imm(TargetPtr, getBits(Value + Addend, 1, 11));
break;
case ELF::R_AARCH64_LDST32_ABS_LO12_NC:
// Operation: S + A
// Immediate goes in bits 21:10 of LD/ST instruction, taken
// from bits 11:2 of X
or32AArch64Imm(TargetPtr, getBits(Value + Addend, 2, 11));
break;
case ELF::R_AARCH64_LDST64_ABS_LO12_NC:
// Operation: S + A
// Immediate goes in bits 21:10 of LD/ST instruction, taken
// from bits 11:3 of X
or32AArch64Imm(TargetPtr, getBits(Value + Addend, 3, 11));
break;
case ELF::R_AARCH64_LDST128_ABS_LO12_NC:
// Operation: S + A
// Immediate goes in bits 21:10 of LD/ST instruction, taken
// from bits 11:4 of X
or32AArch64Imm(TargetPtr, getBits(Value + Addend, 4, 11));
break;
case ELF::R_AARCH64_LD_PREL_LO19: {
// Operation: S + A - P
uint64_t Result = Value + Addend - FinalAddress;
// "Check that -2^20 <= result < 2^20".
assert(isInt<21>(Result));
*TargetPtr &= 0xff00001fU;
// Immediate goes in bits 23:5 of LD imm instruction, taken
// from bits 20:2 of X
*TargetPtr |= ((Result & 0xffc) << (5 - 2));
break;
}
case ELF::R_AARCH64_ADR_PREL_LO21: {
// Operation: S + A - P
uint64_t Result = Value + Addend - FinalAddress;
// "Check that -2^20 <= result < 2^20".
assert(isInt<21>(Result));
*TargetPtr &= 0x9f00001fU;
// Immediate goes in bits 23:5, 30:29 of ADR imm instruction, taken
// from bits 20:0 of X
*TargetPtr |= ((Result & 0xffc) << (5 - 2));
*TargetPtr |= (Result & 0x3) << 29;
break;
}
}
}
void RuntimeDyldELF::resolveARMRelocation(const SectionEntry &Section,
uint64_t Offset, uint32_t Value,
uint32_t Type, int32_t Addend) {
// TODO: Add Thumb relocations.
uint32_t *TargetPtr =
reinterpret_cast<uint32_t *>(Section.getAddressWithOffset(Offset));
uint32_t FinalAddress = Section.getLoadAddressWithOffset(Offset) & 0xFFFFFFFF;
Value += Addend;
LLVM_DEBUG(dbgs() << "resolveARMRelocation, LocalAddress: "
<< Section.getAddressWithOffset(Offset)
<< " FinalAddress: " << format("%p", FinalAddress)
<< " Value: " << format("%x", Value)
<< " Type: " << format("%x", Type)
<< " Addend: " << format("%x", Addend) << "\n");
switch (Type) {
default:
llvm_unreachable("Not implemented relocation type!");
case ELF::R_ARM_NONE:
break;
// Write a 31bit signed offset
case ELF::R_ARM_PREL31:
support::ulittle32_t::ref{TargetPtr} =
(support::ulittle32_t::ref{TargetPtr} & 0x80000000) |
((Value - FinalAddress) & ~0x80000000);
break;
case ELF::R_ARM_TARGET1:
case ELF::R_ARM_ABS32:
support::ulittle32_t::ref{TargetPtr} = Value;
break;
// Write first 16 bit of 32 bit value to the mov instruction.
// Last 4 bit should be shifted.
case ELF::R_ARM_MOVW_ABS_NC:
case ELF::R_ARM_MOVT_ABS:
if (Type == ELF::R_ARM_MOVW_ABS_NC)
Value = Value & 0xFFFF;
else if (Type == ELF::R_ARM_MOVT_ABS)
Value = (Value >> 16) & 0xFFFF;
support::ulittle32_t::ref{TargetPtr} =
(support::ulittle32_t::ref{TargetPtr} & ~0x000F0FFF) | (Value & 0xFFF) |
(((Value >> 12) & 0xF) << 16);
break;
// Write 24 bit relative value to the branch instruction.
case ELF::R_ARM_PC24: // Fall through.
case ELF::R_ARM_CALL: // Fall through.
case ELF::R_ARM_JUMP24:
int32_t RelValue = static_cast<int32_t>(Value - FinalAddress - 8);
RelValue = (RelValue & 0x03FFFFFC) >> 2;
assert((support::ulittle32_t::ref{TargetPtr} & 0xFFFFFF) == 0xFFFFFE);
support::ulittle32_t::ref{TargetPtr} =
(support::ulittle32_t::ref{TargetPtr} & 0xFF000000) | RelValue;
break;
}
}
void RuntimeDyldELF::setMipsABI(const ObjectFile &Obj) {
if (Arch == Triple::UnknownArch ||
Triple::getArchTypePrefix(Arch) != "mips") {
IsMipsO32ABI = false;
IsMipsN32ABI = false;
IsMipsN64ABI = false;
return;
}
if (auto *E = dyn_cast<ELFObjectFileBase>(&Obj)) {
unsigned AbiVariant = E->getPlatformFlags();
IsMipsO32ABI = AbiVariant & ELF::EF_MIPS_ABI_O32;
IsMipsN32ABI = AbiVariant & ELF::EF_MIPS_ABI2;
}
IsMipsN64ABI = Obj.getFileFormatName() == "elf64-mips";
}
// Return the .TOC. section and offset.
Error RuntimeDyldELF::findPPC64TOCSection(const ELFObjectFileBase &Obj,
ObjSectionToIDMap &LocalSections,
RelocationValueRef &Rel) {
// Set a default SectionID in case we do not find a TOC section below.
// This may happen for references to TOC base base (sym@toc, .odp
// relocation) without a .toc directive. In this case just use the
// first section (which is usually the .odp) since the code won't
// reference the .toc base directly.
Rel.SymbolName = nullptr;
Rel.SectionID = 0;
// The TOC consists of sections .got, .toc, .tocbss, .plt in that
// order. The TOC starts where the first of these sections starts.
for (auto &Section : Obj.sections()) {
Expected<StringRef> NameOrErr = Section.getName();
if (!NameOrErr)
return NameOrErr.takeError();
StringRef SectionName = *NameOrErr;
if (SectionName == ".got"
|| SectionName == ".toc"
|| SectionName == ".tocbss"
|| SectionName == ".plt") {
if (auto SectionIDOrErr =
findOrEmitSection(Obj, Section, false, LocalSections))
Rel.SectionID = *SectionIDOrErr;
else
return SectionIDOrErr.takeError();
break;
}
}
// Per the ppc64-elf-linux ABI, The TOC base is TOC value plus 0x8000
// thus permitting a full 64 Kbytes segment.
Rel.Addend = 0x8000;
return Error::success();
}
// Returns the sections and offset associated with the ODP entry referenced
// by Symbol.
Error RuntimeDyldELF::findOPDEntrySection(const ELFObjectFileBase &Obj,
ObjSectionToIDMap &LocalSections,
RelocationValueRef &Rel) {
// Get the ELF symbol value (st_value) to compare with Relocation offset in
// .opd entries
for (section_iterator si = Obj.section_begin(), se = Obj.section_end();
si != se; ++si) {
Expected<section_iterator> RelSecOrErr = si->getRelocatedSection();
if (!RelSecOrErr)
report_fatal_error(Twine(toString(RelSecOrErr.takeError())));
section_iterator RelSecI = *RelSecOrErr;
if (RelSecI == Obj.section_end())
continue;
Expected<StringRef> NameOrErr = RelSecI->getName();
if (!NameOrErr)
return NameOrErr.takeError();
StringRef RelSectionName = *NameOrErr;
if (RelSectionName != ".opd")
continue;
for (elf_relocation_iterator i = si->relocation_begin(),
e = si->relocation_end();
i != e;) {
// The R_PPC64_ADDR64 relocation indicates the first field
// of a .opd entry
uint64_t TypeFunc = i->getType();
if (TypeFunc != ELF::R_PPC64_ADDR64) {
++i;
continue;
}
uint64_t TargetSymbolOffset = i->getOffset();
symbol_iterator TargetSymbol = i->getSymbol();
int64_t Addend;
if (auto AddendOrErr = i->getAddend())
Addend = *AddendOrErr;
else
return AddendOrErr.takeError();
++i;
if (i == e)
break;
// Just check if following relocation is a R_PPC64_TOC
uint64_t TypeTOC = i->getType();
if (TypeTOC != ELF::R_PPC64_TOC)
continue;
// Finally compares the Symbol value and the target symbol offset
// to check if this .opd entry refers to the symbol the relocation
// points to.
if (Rel.Addend != (int64_t)TargetSymbolOffset)
continue;
section_iterator TSI = Obj.section_end();
if (auto TSIOrErr = TargetSymbol->getSection())
TSI = *TSIOrErr;
else
return TSIOrErr.takeError();
assert(TSI != Obj.section_end() && "TSI should refer to a valid section");
bool IsCode = TSI->isText();
if (auto SectionIDOrErr = findOrEmitSection(Obj, *TSI, IsCode,
LocalSections))
Rel.SectionID = *SectionIDOrErr;
else
return SectionIDOrErr.takeError();
Rel.Addend = (intptr_t)Addend;
return Error::success();
}
}
llvm_unreachable("Attempting to get address of ODP entry!");
}
// Relocation masks following the #lo(value), #hi(value), #ha(value),
// #higher(value), #highera(value), #highest(value), and #highesta(value)
// macros defined in section 4.5.1. Relocation Types of the PPC-elf64abi
// document.
static inline uint16_t applyPPClo(uint64_t value) { return value & 0xffff; }
static inline uint16_t applyPPChi(uint64_t value) {
return (value >> 16) & 0xffff;
}
static inline uint16_t applyPPCha (uint64_t value) {
return ((value + 0x8000) >> 16) & 0xffff;
}
static inline uint16_t applyPPChigher(uint64_t value) {
return (value >> 32) & 0xffff;
}
static inline uint16_t applyPPChighera (uint64_t value) {
return ((value + 0x8000) >> 32) & 0xffff;
}
static inline uint16_t applyPPChighest(uint64_t value) {
return (value >> 48) & 0xffff;
}
static inline uint16_t applyPPChighesta (uint64_t value) {
return ((value + 0x8000) >> 48) & 0xffff;
}
void RuntimeDyldELF::resolvePPC32Relocation(const SectionEntry &Section,
uint64_t Offset, uint64_t Value,
uint32_t Type, int64_t Addend) {
uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
switch (Type) {
default:
report_fatal_error("Relocation type not implemented yet!");
break;
case ELF::R_PPC_ADDR16_LO:
writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
break;
case ELF::R_PPC_ADDR16_HI:
writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
break;
case ELF::R_PPC_ADDR16_HA:
writeInt16BE(LocalAddress, applyPPCha(Value + Addend));
break;
}
}
void RuntimeDyldELF::resolvePPC64Relocation(const SectionEntry &Section,
uint64_t Offset, uint64_t Value,
uint32_t Type, int64_t Addend) {
uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
switch (Type) {
default:
report_fatal_error("Relocation type not implemented yet!");
break;
case ELF::R_PPC64_ADDR16:
writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
break;
case ELF::R_PPC64_ADDR16_DS:
writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
break;
case ELF::R_PPC64_ADDR16_LO:
writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
break;
case ELF::R_PPC64_ADDR16_LO_DS:
writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
break;
case ELF::R_PPC64_ADDR16_HI:
case ELF::R_PPC64_ADDR16_HIGH:
writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
break;
case ELF::R_PPC64_ADDR16_HA:
case ELF::R_PPC64_ADDR16_HIGHA:
writeInt16BE(LocalAddress, applyPPCha(Value + Addend));
break;
case ELF::R_PPC64_ADDR16_HIGHER:
writeInt16BE(LocalAddress, applyPPChigher(Value + Addend));
break;
case ELF::R_PPC64_ADDR16_HIGHERA:
writeInt16BE(LocalAddress, applyPPChighera(Value + Addend));
break;
case ELF::R_PPC64_ADDR16_HIGHEST:
writeInt16BE(LocalAddress, applyPPChighest(Value + Addend));
break;
case ELF::R_PPC64_ADDR16_HIGHESTA:
writeInt16BE(LocalAddress, applyPPChighesta(Value + Addend));
break;
case ELF::R_PPC64_ADDR14: {
assert(((Value + Addend) & 3) == 0);
// Preserve the AA/LK bits in the branch instruction
uint8_t aalk = *(LocalAddress + 3);
writeInt16BE(LocalAddress + 2, (aalk & 3) | ((Value + Addend) & 0xfffc));
} break;
case ELF::R_PPC64_REL16_LO: {
uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
uint64_t Delta = Value - FinalAddress + Addend;
writeInt16BE(LocalAddress, applyPPClo(Delta));
} break;
case ELF::R_PPC64_REL16_HI: {
uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
uint64_t Delta = Value - FinalAddress + Addend;
writeInt16BE(LocalAddress, applyPPChi(Delta));
} break;
case ELF::R_PPC64_REL16_HA: {
uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
uint64_t Delta = Value - FinalAddress + Addend;
writeInt16BE(LocalAddress, applyPPCha(Delta));
} break;
case ELF::R_PPC64_ADDR32: {
int64_t Result = static_cast<int64_t>(Value + Addend);
if (SignExtend64<32>(Result) != Result)
llvm_unreachable("Relocation R_PPC64_ADDR32 overflow");
writeInt32BE(LocalAddress, Result);
} break;
case ELF::R_PPC64_REL24: {
uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
int64_t delta = static_cast<int64_t>(Value - FinalAddress + Addend);
if (SignExtend64<26>(delta) != delta)
llvm_unreachable("Relocation R_PPC64_REL24 overflow");
// We preserve bits other than LI field, i.e. PO and AA/LK fields.
uint32_t Inst = readBytesUnaligned(LocalAddress, 4);
writeInt32BE(LocalAddress, (Inst & 0xFC000003) | (delta & 0x03FFFFFC));
} break;
case ELF::R_PPC64_REL32: {
uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
int64_t delta = static_cast<int64_t>(Value - FinalAddress + Addend);
if (SignExtend64<32>(delta) != delta)
llvm_unreachable("Relocation R_PPC64_REL32 overflow");
writeInt32BE(LocalAddress, delta);
} break;
case ELF::R_PPC64_REL64: {
uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
uint64_t Delta = Value - FinalAddress + Addend;
writeInt64BE(LocalAddress, Delta);
} break;
case ELF::R_PPC64_ADDR64:
writeInt64BE(LocalAddress, Value + Addend);
break;
}
}
void RuntimeDyldELF::resolveSystemZRelocation(const SectionEntry &Section,
uint64_t Offset, uint64_t Value,
uint32_t Type, int64_t Addend) {
uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
switch (Type) {
default:
report_fatal_error("Relocation type not implemented yet!");
break;
case ELF::R_390_PC16DBL:
case ELF::R_390_PLT16DBL: {
int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
assert(int16_t(Delta / 2) * 2 == Delta && "R_390_PC16DBL overflow");
writeInt16BE(LocalAddress, Delta / 2);
break;
}
case ELF::R_390_PC32DBL:
case ELF::R_390_PLT32DBL: {
int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
assert(int32_t(Delta / 2) * 2 == Delta && "R_390_PC32DBL overflow");
writeInt32BE(LocalAddress, Delta / 2);
break;
}
case ELF::R_390_PC16: {
int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
assert(int16_t(Delta) == Delta && "R_390_PC16 overflow");
writeInt16BE(LocalAddress, Delta);
break;
}
case ELF::R_390_PC32: {
int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
assert(int32_t(Delta) == Delta && "R_390_PC32 overflow");
writeInt32BE(LocalAddress, Delta);
break;
}
case ELF::R_390_PC64: {
int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
writeInt64BE(LocalAddress, Delta);
break;
}
case ELF::R_390_8:
*LocalAddress = (uint8_t)(Value + Addend);
break;
case ELF::R_390_16:
writeInt16BE(LocalAddress, Value + Addend);
break;
case ELF::R_390_32:
writeInt32BE(LocalAddress, Value + Addend);
break;
case ELF::R_390_64:
writeInt64BE(LocalAddress, Value + Addend);
break;
}
}
void RuntimeDyldELF::resolveBPFRelocation(const SectionEntry &Section,
uint64_t Offset, uint64_t Value,
uint32_t Type, int64_t Addend) {
bool isBE = Arch == Triple::bpfeb;
switch (Type) {
default:
report_fatal_error("Relocation type not implemented yet!");
break;
case ELF::R_BPF_NONE:
case ELF::R_BPF_64_64:
case ELF::R_BPF_64_32:
case ELF::R_BPF_64_NODYLD32:
break;
case ELF::R_BPF_64_ABS64: {
write(isBE, Section.getAddressWithOffset(Offset), Value + Addend);
LLVM_DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at "
<< format("%p\n", Section.getAddressWithOffset(Offset)));
break;
}
case ELF::R_BPF_64_ABS32: {
Value += Addend;
assert(Value <= UINT32_MAX);
write(isBE, Section.getAddressWithOffset(Offset), static_cast<uint32_t>(Value));
LLVM_DEBUG(dbgs() << "Writing " << format("%p", Value) << " at "
<< format("%p\n", Section.getAddressWithOffset(Offset)));
break;
}
}
}
// The target location for the relocation is described by RE.SectionID and
// RE.Offset. RE.SectionID can be used to find the SectionEntry. Each
// SectionEntry has three members describing its location.
// SectionEntry::Address is the address at which the section has been loaded
// into memory in the current (host) process. SectionEntry::LoadAddress is the
// address that the section will have in the target process.
// SectionEntry::ObjAddress is the address of the bits for this section in the
// original emitted object image (also in the current address space).
//
// Relocations will be applied as if the section were loaded at
// SectionEntry::LoadAddress, but they will be applied at an address based
// on SectionEntry::Address. SectionEntry::ObjAddress will be used to refer to
// Target memory contents if they are required for value calculations.
//
// The Value parameter here is the load address of the symbol for the
// relocation to be applied. For relocations which refer to symbols in the
// current object Value will be the LoadAddress of the section in which
// the symbol resides (RE.Addend provides additional information about the
// symbol location). For external symbols, Value will be the address of the
// symbol in the target address space.
void RuntimeDyldELF::resolveRelocation(const RelocationEntry &RE,
uint64_t Value) {
const SectionEntry &Section = Sections[RE.SectionID];
return resolveRelocation(Section, RE.Offset, Value, RE.RelType, RE.Addend,
RE.SymOffset, RE.SectionID);
}
void RuntimeDyldELF::resolveRelocation(const SectionEntry &Section,
uint64_t Offset, uint64_t Value,
uint32_t Type, int64_t Addend,
uint64_t SymOffset, SID SectionID) {
switch (Arch) {
case Triple::x86_64:
resolveX86_64Relocation(Section, Offset, Value, Type, Addend, SymOffset);
break;
case Triple::x86:
resolveX86Relocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
(uint32_t)(Addend & 0xffffffffL));
break;
case Triple::aarch64:
case Triple::aarch64_be:
resolveAArch64Relocation(Section, Offset, Value, Type, Addend);
break;
case Triple::arm: // Fall through.
case Triple::armeb:
case Triple::thumb:
case Triple::thumbeb:
resolveARMRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
(uint32_t)(Addend & 0xffffffffL));
break;
case Triple::ppc: // Fall through.
case Triple::ppcle:
resolvePPC32Relocation(Section, Offset, Value, Type, Addend);
break;
case Triple::ppc64: // Fall through.
case Triple::ppc64le:
resolvePPC64Relocation(Section, Offset, Value, Type, Addend);
break;
case Triple::systemz:
resolveSystemZRelocation(Section, Offset, Value, Type, Addend);
break;
case Triple::bpfel:
case Triple::bpfeb:
resolveBPFRelocation(Section, Offset, Value, Type, Addend);
break;
default:
llvm_unreachable("Unsupported CPU type!");
}
}
void *RuntimeDyldELF::computePlaceholderAddress(unsigned SectionID, uint64_t Offset) const {
return (void *)(Sections[SectionID].getObjAddress() + Offset);
}
void RuntimeDyldELF::processSimpleRelocation(unsigned SectionID, uint64_t Offset, unsigned RelType, RelocationValueRef Value) {
RelocationEntry RE(SectionID, Offset, RelType, Value.Addend, Value.Offset);
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
}
uint32_t RuntimeDyldELF::getMatchingLoRelocation(uint32_t RelType,
bool IsLocal) const {
switch (RelType) {
case ELF::R_MICROMIPS_GOT16:
if (IsLocal)
return ELF::R_MICROMIPS_LO16;
break;
case ELF::R_MICROMIPS_HI16:
return ELF::R_MICROMIPS_LO16;
case ELF::R_MIPS_GOT16:
if (IsLocal)
return ELF::R_MIPS_LO16;
break;
case ELF::R_MIPS_HI16:
return ELF::R_MIPS_LO16;
case ELF::R_MIPS_PCHI16:
return ELF::R_MIPS_PCLO16;
default:
break;
}
return ELF::R_MIPS_NONE;
}
// Sometimes we don't need to create thunk for a branch.
// This typically happens when branch target is located
// in the same object file. In such case target is either
// a weak symbol or symbol in a different executable section.
// This function checks if branch target is located in the
// same object file and if distance between source and target
// fits R_AARCH64_CALL26 relocation. If both conditions are
// met, it emits direct jump to the target and returns true.
// Otherwise false is returned and thunk is created.
bool RuntimeDyldELF::resolveAArch64ShortBranch(
unsigned SectionID, relocation_iterator RelI,
const RelocationValueRef &Value) {
uint64_t Address;
if (Value.SymbolName) {
auto Loc = GlobalSymbolTable.find(Value.SymbolName);
// Don't create direct branch for external symbols.
if (Loc == GlobalSymbolTable.end())
return false;
const auto &SymInfo = Loc->second;
Address =
uint64_t(Sections[SymInfo.getSectionID()].getLoadAddressWithOffset(
SymInfo.getOffset()));
} else {
Address = uint64_t(Sections[Value.SectionID].getLoadAddress());
}
uint64_t Offset = RelI->getOffset();
uint64_t SourceAddress = Sections[SectionID].getLoadAddressWithOffset(Offset);
// R_AARCH64_CALL26 requires immediate to be in range -2^27 <= imm < 2^27
// If distance between source and target is out of range then we should
// create thunk.
if (!isInt<28>(Address + Value.Addend - SourceAddress))
return false;
resolveRelocation(Sections[SectionID], Offset, Address, RelI->getType(),
Value.Addend);
return true;
}
void RuntimeDyldELF::resolveAArch64Branch(unsigned SectionID,
const RelocationValueRef &Value,
relocation_iterator RelI,
StubMap &Stubs) {
LLVM_DEBUG(dbgs() << "\t\tThis is an AArch64 branch relocation.");
SectionEntry &Section = Sections[SectionID];
uint64_t Offset = RelI->getOffset();
unsigned RelType = RelI->getType();
// Look for an existing stub.
StubMap::const_iterator i = Stubs.find(Value);
if (i != Stubs.end()) {
resolveRelocation(Section, Offset,
(uint64_t)Section.getAddressWithOffset(i->second),
RelType, 0);
LLVM_DEBUG(dbgs() << " Stub function found\n");
} else if (!resolveAArch64ShortBranch(SectionID, RelI, Value)) {
// Create a new stub function.
LLVM_DEBUG(dbgs() << " Create a new stub function\n");
Stubs[Value] = Section.getStubOffset();
uint8_t *StubTargetAddr = createStubFunction(
Section.getAddressWithOffset(Section.getStubOffset()));
RelocationEntry REmovz_g3(SectionID, StubTargetAddr - Section.getAddress(),
ELF::R_AARCH64_MOVW_UABS_G3, Value.Addend);
RelocationEntry REmovk_g2(SectionID,
StubTargetAddr - Section.getAddress() + 4,
ELF::R_AARCH64_MOVW_UABS_G2_NC, Value.Addend);
RelocationEntry REmovk_g1(SectionID,
StubTargetAddr - Section.getAddress() + 8,
ELF::R_AARCH64_MOVW_UABS_G1_NC, Value.Addend);
RelocationEntry REmovk_g0(SectionID,
StubTargetAddr - Section.getAddress() + 12,
ELF::R_AARCH64_MOVW_UABS_G0_NC, Value.Addend);
if (Value.SymbolName) {
addRelocationForSymbol(REmovz_g3, Value.SymbolName);
addRelocationForSymbol(REmovk_g2, Value.SymbolName);
addRelocationForSymbol(REmovk_g1, Value.SymbolName);
addRelocationForSymbol(REmovk_g0, Value.SymbolName);
} else {
addRelocationForSection(REmovz_g3, Value.SectionID);
addRelocationForSection(REmovk_g2, Value.SectionID);
addRelocationForSection(REmovk_g1, Value.SectionID);
addRelocationForSection(REmovk_g0, Value.SectionID);
}
resolveRelocation(Section, Offset,
reinterpret_cast<uint64_t>(Section.getAddressWithOffset(
Section.getStubOffset())),
RelType, 0);
Section.advanceStubOffset(getMaxStubSize());
}
}
Expected<relocation_iterator>
RuntimeDyldELF::processRelocationRef(
unsigned SectionID, relocation_iterator RelI, const ObjectFile &O,
ObjSectionToIDMap &ObjSectionToID, StubMap &Stubs) {
const auto &Obj = cast<ELFObjectFileBase>(O);
uint64_t RelType = RelI->getType();
int64_t Addend = 0;
if (Expected<int64_t> AddendOrErr = ELFRelocationRef(*RelI).getAddend())
Addend = *AddendOrErr;
else
consumeError(AddendOrErr.takeError());
elf_symbol_iterator Symbol = RelI->getSymbol();
// Obtain the symbol name which is referenced in the relocation
StringRef TargetName;
if (Symbol != Obj.symbol_end()) {
if (auto TargetNameOrErr = Symbol->getName())
TargetName = *TargetNameOrErr;
else
return TargetNameOrErr.takeError();
}
LLVM_DEBUG(dbgs() << "\t\tRelType: " << RelType << " Addend: " << Addend
<< " TargetName: " << TargetName << "\n");
RelocationValueRef Value;
// First search for the symbol in the local symbol table
SymbolRef::Type SymType = SymbolRef::ST_Unknown;
// Search for the symbol in the global symbol table
RTDyldSymbolTable::const_iterator gsi = GlobalSymbolTable.end();
if (Symbol != Obj.symbol_end()) {
gsi = GlobalSymbolTable.find(TargetName.data());
Expected<SymbolRef::Type> SymTypeOrErr = Symbol->getType();
if (!SymTypeOrErr) {
std::string Buf;
raw_string_ostream OS(Buf);
logAllUnhandledErrors(SymTypeOrErr.takeError(), OS);
report_fatal_error(Twine(OS.str()));
}
SymType = *SymTypeOrErr;
}
if (gsi != GlobalSymbolTable.end()) {
const auto &SymInfo = gsi->second;
Value.SectionID = SymInfo.getSectionID();
Value.Offset = SymInfo.getOffset();
Value.Addend = SymInfo.getOffset() + Addend;
} else {
switch (SymType) {
case SymbolRef::ST_Debug: {
// TODO: Now ELF SymbolRef::ST_Debug = STT_SECTION, it's not obviously
// and can be changed by another developers. Maybe best way is add
// a new symbol type ST_Section to SymbolRef and use it.
auto SectionOrErr = Symbol->getSection();
if (!SectionOrErr) {
std::string Buf;
raw_string_ostream OS(Buf);
logAllUnhandledErrors(SectionOrErr.takeError(), OS);
report_fatal_error(Twine(OS.str()));
}
section_iterator si = *SectionOrErr;
if (si == Obj.section_end())
llvm_unreachable("Symbol section not found, bad object file format!");
LLVM_DEBUG(dbgs() << "\t\tThis is section symbol\n");
bool isCode = si->isText();
if (auto SectionIDOrErr = findOrEmitSection(Obj, (*si), isCode,
ObjSectionToID))
Value.SectionID = *SectionIDOrErr;
else
return SectionIDOrErr.takeError();
Value.Addend = Addend;
break;
}
case SymbolRef::ST_Data:
case SymbolRef::ST_Function:
case SymbolRef::ST_Other:
case SymbolRef::ST_Unknown: {
Value.SymbolName = TargetName.data();
Value.Addend = Addend;
// Absolute relocations will have a zero symbol ID (STN_UNDEF), which
// will manifest here as a NULL symbol name.
// We can set this as a valid (but empty) symbol name, and rely
// on addRelocationForSymbol to handle this.
if (!Value.SymbolName)
Value.SymbolName = "";
break;
}
default:
llvm_unreachable("Unresolved symbol type!");
break;
}
}
uint64_t Offset = RelI->getOffset();
LLVM_DEBUG(dbgs() << "\t\tSectionID: " << SectionID << " Offset: " << Offset
<< "\n");
if ((Arch == Triple::aarch64 || Arch == Triple::aarch64_be)) {
if ((RelType == ELF::R_AARCH64_CALL26 ||
RelType == ELF::R_AARCH64_JUMP26) &&
MemMgr.allowStubAllocation()) {
resolveAArch64Branch(SectionID, Value, RelI, Stubs);
} else if (RelType == ELF::R_AARCH64_ADR_GOT_PAGE) {
// Create new GOT entry or find existing one. If GOT entry is
// to be created, then we also emit ABS64 relocation for it.
uint64_t GOTOffset = findOrAllocGOTEntry(Value, ELF::R_AARCH64_ABS64);
resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
ELF::R_AARCH64_ADR_PREL_PG_HI21);
} else if (RelType == ELF::R_AARCH64_LD64_GOT_LO12_NC) {
uint64_t GOTOffset = findOrAllocGOTEntry(Value, ELF::R_AARCH64_ABS64);
resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
ELF::R_AARCH64_LDST64_ABS_LO12_NC);
} else {
processSimpleRelocation(SectionID, Offset, RelType, Value);
}
} else if (Arch == Triple::arm) {
if (RelType == ELF::R_ARM_PC24 || RelType == ELF::R_ARM_CALL ||
RelType == ELF::R_ARM_JUMP24) {
// This is an ARM branch relocation, need to use a stub function.
LLVM_DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.\n");
SectionEntry &Section = Sections[SectionID];
// Look for an existing stub.
StubMap::const_iterator i = Stubs.find(Value);
if (i != Stubs.end()) {
resolveRelocation(
Section, Offset,
reinterpret_cast<uint64_t>(Section.getAddressWithOffset(i->second)),
RelType, 0);
LLVM_DEBUG(dbgs() << " Stub function found\n");
} else {
// Create a new stub function.
LLVM_DEBUG(dbgs() << " Create a new stub function\n");
Stubs[Value] = Section.getStubOffset();
uint8_t *StubTargetAddr = createStubFunction(
Section.getAddressWithOffset(Section.getStubOffset()));
RelocationEntry RE(SectionID, StubTargetAddr - Section.getAddress(),
ELF::R_ARM_ABS32, Value.Addend);
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
resolveRelocation(Section, Offset, reinterpret_cast<uint64_t>(
Section.getAddressWithOffset(
Section.getStubOffset())),
RelType, 0);
Section.advanceStubOffset(getMaxStubSize());
}
} else {
uint32_t *Placeholder =
reinterpret_cast<uint32_t*>(computePlaceholderAddress(SectionID, Offset));
if (RelType == ELF::R_ARM_PREL31 || RelType == ELF::R_ARM_TARGET1 ||
RelType == ELF::R_ARM_ABS32) {
Value.Addend += *Placeholder;
} else if (RelType == ELF::R_ARM_MOVW_ABS_NC || RelType == ELF::R_ARM_MOVT_ABS) {
// See ELF for ARM documentation
Value.Addend += (int16_t)((*Placeholder & 0xFFF) | (((*Placeholder >> 16) & 0xF) << 12));
}
processSimpleRelocation(SectionID, Offset, RelType, Value);
}
} else if (IsMipsO32ABI) {
uint8_t *Placeholder = reinterpret_cast<uint8_t *>(
computePlaceholderAddress(SectionID, Offset));
uint32_t Opcode = readBytesUnaligned(Placeholder, 4);
if (RelType == ELF::R_MIPS_26) {
// This is an Mips branch relocation, need to use a stub function.
LLVM_DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
SectionEntry &Section = Sections[SectionID];
// Extract the addend from the instruction.
// We shift up by two since the Value will be down shifted again
// when applying the relocation.
uint32_t Addend = (Opcode & 0x03ffffff) << 2;
Value.Addend += Addend;
// Look up for existing stub.
StubMap::const_iterator i = Stubs.find(Value);
if (i != Stubs.end()) {
RelocationEntry RE(SectionID, Offset, RelType, i->second);
addRelocationForSection(RE, SectionID);
LLVM_DEBUG(dbgs() << " Stub function found\n");
} else {
// Create a new stub function.
LLVM_DEBUG(dbgs() << " Create a new stub function\n");
Stubs[Value] = Section.getStubOffset();
unsigned AbiVariant = Obj.getPlatformFlags();
uint8_t *StubTargetAddr = createStubFunction(
Section.getAddressWithOffset(Section.getStubOffset()), AbiVariant);
// Creating Hi and Lo relocations for the filled stub instructions.
RelocationEntry REHi(SectionID, StubTargetAddr - Section.getAddress(),
ELF::R_MIPS_HI16, Value.Addend);
RelocationEntry RELo(SectionID,
StubTargetAddr - Section.getAddress() + 4,
ELF::R_MIPS_LO16, Value.Addend);
if (Value.SymbolName) {
addRelocationForSymbol(REHi, Value.SymbolName);
addRelocationForSymbol(RELo, Value.SymbolName);
} else {
addRelocationForSection(REHi, Value.SectionID);
addRelocationForSection(RELo, Value.SectionID);
}
RelocationEntry RE(SectionID, Offset, RelType, Section.getStubOffset());
addRelocationForSection(RE, SectionID);
Section.advanceStubOffset(getMaxStubSize());
}
} else if (RelType == ELF::R_MIPS_HI16 || RelType == ELF::R_MIPS_PCHI16) {
int64_t Addend = (Opcode & 0x0000ffff) << 16;
RelocationEntry RE(SectionID, Offset, RelType, Addend);
PendingRelocs.push_back(std::make_pair(Value, RE));
} else if (RelType == ELF::R_MIPS_LO16 || RelType == ELF::R_MIPS_PCLO16) {
int64_t Addend = Value.Addend + SignExtend32<16>(Opcode & 0x0000ffff);
for (auto I = PendingRelocs.begin(); I != PendingRelocs.end();) {
const RelocationValueRef &MatchingValue = I->first;
RelocationEntry &Reloc = I->second;
if (MatchingValue == Value &&
RelType == getMatchingLoRelocation(Reloc.RelType) &&
SectionID == Reloc.SectionID) {
Reloc.Addend += Addend;
if (Value.SymbolName)
addRelocationForSymbol(Reloc, Value.SymbolName);
else
addRelocationForSection(Reloc, Value.SectionID);
I = PendingRelocs.erase(I);
} else
++I;
}
RelocationEntry RE(SectionID, Offset, RelType, Addend);
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
} else {
if (RelType == ELF::R_MIPS_32)
Value.Addend += Opcode;
else if (RelType == ELF::R_MIPS_PC16)
Value.Addend += SignExtend32<18>((Opcode & 0x0000ffff) << 2);
else if (RelType == ELF::R_MIPS_PC19_S2)
Value.Addend += SignExtend32<21>((Opcode & 0x0007ffff) << 2);
else if (RelType == ELF::R_MIPS_PC21_S2)
Value.Addend += SignExtend32<23>((Opcode & 0x001fffff) << 2);
else if (RelType == ELF::R_MIPS_PC26_S2)
Value.Addend += SignExtend32<28>((Opcode & 0x03ffffff) << 2);
processSimpleRelocation(SectionID, Offset, RelType, Value);
}
} else if (IsMipsN32ABI || IsMipsN64ABI) {
uint32_t r_type = RelType & 0xff;
RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
if (r_type == ELF::R_MIPS_CALL16 || r_type == ELF::R_MIPS_GOT_PAGE
|| r_type == ELF::R_MIPS_GOT_DISP) {
StringMap<uint64_t>::iterator i = GOTSymbolOffsets.find(TargetName);
if (i != GOTSymbolOffsets.end())
RE.SymOffset = i->second;
else {
RE.SymOffset = allocateGOTEntries(1);
GOTSymbolOffsets[TargetName] = RE.SymOffset;
}
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
} else if (RelType == ELF::R_MIPS_26) {
// This is an Mips branch relocation, need to use a stub function.
LLVM_DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
SectionEntry &Section = Sections[SectionID];
// Look up for existing stub.
StubMap::const_iterator i = Stubs.find(Value);
if (i != Stubs.end()) {
RelocationEntry RE(SectionID, Offset, RelType, i->second);
addRelocationForSection(RE, SectionID);
LLVM_DEBUG(dbgs() << " Stub function found\n");
} else {
// Create a new stub function.
LLVM_DEBUG(dbgs() << " Create a new stub function\n");
Stubs[Value] = Section.getStubOffset();
unsigned AbiVariant = Obj.getPlatformFlags();
uint8_t *StubTargetAddr = createStubFunction(
Section.getAddressWithOffset(Section.getStubOffset()), AbiVariant);
if (IsMipsN32ABI) {
// Creating Hi and Lo relocations for the filled stub instructions.
RelocationEntry REHi(SectionID, StubTargetAddr - Section.getAddress(),
ELF::R_MIPS_HI16, Value.Addend);
RelocationEntry RELo(SectionID,
StubTargetAddr - Section.getAddress() + 4,
ELF::R_MIPS_LO16, Value.Addend);
if (Value.SymbolName) {
addRelocationForSymbol(REHi, Value.SymbolName);
addRelocationForSymbol(RELo, Value.SymbolName);
} else {
addRelocationForSection(REHi, Value.SectionID);
addRelocationForSection(RELo, Value.SectionID);
}
} else {
// Creating Highest, Higher, Hi and Lo relocations for the filled stub
// instructions.
RelocationEntry REHighest(SectionID,
StubTargetAddr - Section.getAddress(),
ELF::R_MIPS_HIGHEST, Value.Addend);
RelocationEntry REHigher(SectionID,
StubTargetAddr - Section.getAddress() + 4,
ELF::R_MIPS_HIGHER, Value.Addend);
RelocationEntry REHi(SectionID,
StubTargetAddr - Section.getAddress() + 12,
ELF::R_MIPS_HI16, Value.Addend);
RelocationEntry RELo(SectionID,
StubTargetAddr - Section.getAddress() + 20,
ELF::R_MIPS_LO16, Value.Addend);
if (Value.SymbolName) {
addRelocationForSymbol(REHighest, Value.SymbolName);
addRelocationForSymbol(REHigher, Value.SymbolName);
addRelocationForSymbol(REHi, Value.SymbolName);
addRelocationForSymbol(RELo, Value.SymbolName);
} else {
addRelocationForSection(REHighest, Value.SectionID);
addRelocationForSection(REHigher, Value.SectionID);
addRelocationForSection(REHi, Value.SectionID);
addRelocationForSection(RELo, Value.SectionID);
}
}
RelocationEntry RE(SectionID, Offset, RelType, Section.getStubOffset());
addRelocationForSection(RE, SectionID);
Section.advanceStubOffset(getMaxStubSize());
}
} else {
processSimpleRelocation(SectionID, Offset, RelType, Value);
}
} else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
if (RelType == ELF::R_PPC64_REL24) {
// Determine ABI variant in use for this object.
unsigned AbiVariant = Obj.getPlatformFlags();
AbiVariant &= ELF::EF_PPC64_ABI;
// A PPC branch relocation will need a stub function if the target is
// an external symbol (either Value.SymbolName is set, or SymType is
// Symbol::ST_Unknown) or if the target address is not within the
// signed 24-bits branch address.
SectionEntry &Section = Sections[SectionID];
uint8_t *Target = Section.getAddressWithOffset(Offset);
bool RangeOverflow = false;
bool IsExtern = Value.SymbolName || SymType == SymbolRef::ST_Unknown;
if (!IsExtern) {
if (AbiVariant != 2) {
// In the ELFv1 ABI, a function call may point to the .opd entry,
// so the final symbol value is calculated based on the relocation
// values in the .opd section.
if (auto Err = findOPDEntrySection(Obj, ObjSectionToID, Value))
return std::move(Err);
} else {
// In the ELFv2 ABI, a function symbol may provide a local entry
// point, which must be used for direct calls.
if (Value.SectionID == SectionID){
uint8_t SymOther = Symbol->getOther();
Value.Addend += ELF::decodePPC64LocalEntryOffset(SymOther);
}
}
uint8_t *RelocTarget =
Sections[Value.SectionID].getAddressWithOffset(Value.Addend);
int64_t delta = static_cast<int64_t>(Target - RelocTarget);
// If it is within 26-bits branch range, just set the branch target
if (SignExtend64<26>(delta) != delta) {
RangeOverflow = true;
} else if ((AbiVariant != 2) ||
(AbiVariant == 2 && Value.SectionID == SectionID)) {
RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
addRelocationForSection(RE, Value.SectionID);
}
}
if (IsExtern || (AbiVariant == 2 && Value.SectionID != SectionID) ||
RangeOverflow) {
// It is an external symbol (either Value.SymbolName is set, or
// SymType is SymbolRef::ST_Unknown) or out of range.
StubMap::const_iterator i = Stubs.find(Value);
if (i != Stubs.end()) {
// Symbol function stub already created, just relocate to it
resolveRelocation(Section, Offset,
reinterpret_cast<uint64_t>(
Section.getAddressWithOffset(i->second)),
RelType, 0);
LLVM_DEBUG(dbgs() << " Stub function found\n");
} else {
// Create a new stub function.
LLVM_DEBUG(dbgs() << " Create a new stub function\n");
Stubs[Value] = Section.getStubOffset();
uint8_t *StubTargetAddr = createStubFunction(
Section.getAddressWithOffset(Section.getStubOffset()),
AbiVariant);
RelocationEntry RE(SectionID, StubTargetAddr - Section.getAddress(),
ELF::R_PPC64_ADDR64, Value.Addend);
// Generates the 64-bits address loads as exemplified in section
// 4.5.1 in PPC64 ELF ABI. Note that the relocations need to
// apply to the low part of the instructions, so we have to update
// the offset according to the target endianness.
uint64_t StubRelocOffset = StubTargetAddr - Section.getAddress();
if (!IsTargetLittleEndian)
StubRelocOffset += 2;
RelocationEntry REhst(SectionID, StubRelocOffset + 0,
ELF::R_PPC64_ADDR16_HIGHEST, Value.Addend);
RelocationEntry REhr(SectionID, StubRelocOffset + 4,
ELF::R_PPC64_ADDR16_HIGHER, Value.Addend);
RelocationEntry REh(SectionID, StubRelocOffset + 12,
ELF::R_PPC64_ADDR16_HI, Value.Addend);
RelocationEntry REl(SectionID, StubRelocOffset + 16,
ELF::R_PPC64_ADDR16_LO, Value.Addend);
if (Value.SymbolName) {
addRelocationForSymbol(REhst, Value.SymbolName);
addRelocationForSymbol(REhr, Value.SymbolName);
addRelocationForSymbol(REh, Value.SymbolName);
addRelocationForSymbol(REl, Value.SymbolName);
} else {
addRelocationForSection(REhst, Value.SectionID);
addRelocationForSection(REhr, Value.SectionID);
addRelocationForSection(REh, Value.SectionID);
addRelocationForSection(REl, Value.SectionID);
}
resolveRelocation(Section, Offset, reinterpret_cast<uint64_t>(
Section.getAddressWithOffset(
Section.getStubOffset())),
RelType, 0);
Section.advanceStubOffset(getMaxStubSize());
}
if (IsExtern || (AbiVariant == 2 && Value.SectionID != SectionID)) {
// Restore the TOC for external calls
if (AbiVariant == 2)
writeInt32BE(Target + 4, 0xE8410018); // ld r2,24(r1)
else
writeInt32BE(Target + 4, 0xE8410028); // ld r2,40(r1)
}
}
} else if (RelType == ELF::R_PPC64_TOC16 ||
RelType == ELF::R_PPC64_TOC16_DS ||
RelType == ELF::R_PPC64_TOC16_LO ||
RelType == ELF::R_PPC64_TOC16_LO_DS ||
RelType == ELF::R_PPC64_TOC16_HI ||
RelType == ELF::R_PPC64_TOC16_HA) {
// These relocations are supposed to subtract the TOC address from
// the final value. This does not fit cleanly into the RuntimeDyld
// scheme, since there may be *two* sections involved in determining
// the relocation value (the section of the symbol referred to by the
// relocation, and the TOC section associated with the current module).
//
// Fortunately, these relocations are currently only ever generated
// referring to symbols that themselves reside in the TOC, which means
// that the two sections are actually the same. Thus they cancel out
// and we can immediately resolve the relocation right now.
switch (RelType) {
case ELF::R_PPC64_TOC16: RelType = ELF::R_PPC64_ADDR16; break;
case ELF::R_PPC64_TOC16_DS: RelType = ELF::R_PPC64_ADDR16_DS; break;
case ELF::R_PPC64_TOC16_LO: RelType = ELF::R_PPC64_ADDR16_LO; break;
case ELF::R_PPC64_TOC16_LO_DS: RelType = ELF::R_PPC64_ADDR16_LO_DS; break;
case ELF::R_PPC64_TOC16_HI: RelType = ELF::R_PPC64_ADDR16_HI; break;
case ELF::R_PPC64_TOC16_HA: RelType = ELF::R_PPC64_ADDR16_HA; break;
default: llvm_unreachable("Wrong relocation type.");
}
RelocationValueRef TOCValue;
if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, TOCValue))
return std::move(Err);
if (Value.SymbolName || Value.SectionID != TOCValue.SectionID)
llvm_unreachable("Unsupported TOC relocation.");
Value.Addend -= TOCValue.Addend;
resolveRelocation(Sections[SectionID], Offset, Value.Addend, RelType, 0);
} else {
// There are two ways to refer to the TOC address directly: either
// via a ELF::R_PPC64_TOC relocation (where both symbol and addend are
// ignored), or via any relocation that refers to the magic ".TOC."
// symbols (in which case the addend is respected).
if (RelType == ELF::R_PPC64_TOC) {
RelType = ELF::R_PPC64_ADDR64;
if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, Value))
return std::move(Err);
} else if (TargetName == ".TOC.") {
if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, Value))
return std::move(Err);
Value.Addend += Addend;
}
RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
}
} else if (Arch == Triple::systemz &&
(RelType == ELF::R_390_PLT32DBL || RelType == ELF::R_390_GOTENT)) {
// Create function stubs for both PLT and GOT references, regardless of
// whether the GOT reference is to data or code. The stub contains the
// full address of the symbol, as needed by GOT references, and the
// executable part only adds an overhead of 8 bytes.
//
// We could try to conserve space by allocating the code and data
// parts of the stub separately. However, as things stand, we allocate
// a stub for every relocation, so using a GOT in JIT code should be
// no less space efficient than using an explicit constant pool.
LLVM_DEBUG(dbgs() << "\t\tThis is a SystemZ indirect relocation.");
SectionEntry &Section = Sections[SectionID];
// Look for an existing stub.
StubMap::const_iterator i = Stubs.find(Value);
uintptr_t StubAddress;
if (i != Stubs.end()) {
StubAddress = uintptr_t(Section.getAddressWithOffset(i->second));
LLVM_DEBUG(dbgs() << " Stub function found\n");
} else {
// Create a new stub function.
LLVM_DEBUG(dbgs() << " Create a new stub function\n");
uintptr_t BaseAddress = uintptr_t(Section.getAddress());
StubAddress =
alignTo(BaseAddress + Section.getStubOffset(), getStubAlignment());
unsigned StubOffset = StubAddress - BaseAddress;
Stubs[Value] = StubOffset;
createStubFunction((uint8_t *)StubAddress);
RelocationEntry RE(SectionID, StubOffset + 8, ELF::R_390_64,
Value.Offset);
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
Section.advanceStubOffset(getMaxStubSize());
}
if (RelType == ELF::R_390_GOTENT)
resolveRelocation(Section, Offset, StubAddress + 8, ELF::R_390_PC32DBL,
Addend);
else
resolveRelocation(Section, Offset, StubAddress, RelType, Addend);
} else if (Arch == Triple::x86_64) {
if (RelType == ELF::R_X86_64_PLT32) {
// The way the PLT relocations normally work is that the linker allocates
// the
// PLT and this relocation makes a PC-relative call into the PLT. The PLT
// entry will then jump to an address provided by the GOT. On first call,
// the
// GOT address will point back into PLT code that resolves the symbol. After
// the first call, the GOT entry points to the actual function.
//
// For local functions we're ignoring all of that here and just replacing
// the PLT32 relocation type with PC32, which will translate the relocation
// into a PC-relative call directly to the function. For external symbols we
// can't be sure the function will be within 2^32 bytes of the call site, so
// we need to create a stub, which calls into the GOT. This case is
// equivalent to the usual PLT implementation except that we use the stub
// mechanism in RuntimeDyld (which puts stubs at the end of the section)
// rather than allocating a PLT section.
if (Value.SymbolName && MemMgr.allowStubAllocation()) {
// This is a call to an external function.
// Look for an existing stub.
SectionEntry *Section = &Sections[SectionID];
StubMap::const_iterator i = Stubs.find(Value);
uintptr_t StubAddress;
if (i != Stubs.end()) {
StubAddress = uintptr_t(Section->getAddress()) + i->second;
LLVM_DEBUG(dbgs() << " Stub function found\n");
} else {
// Create a new stub function (equivalent to a PLT entry).
LLVM_DEBUG(dbgs() << " Create a new stub function\n");
uintptr_t BaseAddress = uintptr_t(Section->getAddress());
StubAddress = alignTo(BaseAddress + Section->getStubOffset(),
getStubAlignment());
unsigned StubOffset = StubAddress - BaseAddress;
Stubs[Value] = StubOffset;
createStubFunction((uint8_t *)StubAddress);
// Bump our stub offset counter
Section->advanceStubOffset(getMaxStubSize());
// Allocate a GOT Entry
uint64_t GOTOffset = allocateGOTEntries(1);
// This potentially creates a new Section which potentially
// invalidates the Section pointer, so reload it.
Section = &Sections[SectionID];
// The load of the GOT address has an addend of -4
resolveGOTOffsetRelocation(SectionID, StubOffset + 2, GOTOffset - 4,
ELF::R_X86_64_PC32);
// Fill in the value of the symbol we're targeting into the GOT
addRelocationForSymbol(
computeGOTOffsetRE(GOTOffset, 0, ELF::R_X86_64_64),
Value.SymbolName);
}
// Make the target call a call into the stub table.
resolveRelocation(*Section, Offset, StubAddress, ELF::R_X86_64_PC32,
Addend);
} else {
Value.Addend += support::ulittle32_t::ref(
computePlaceholderAddress(SectionID, Offset));
processSimpleRelocation(SectionID, Offset, ELF::R_X86_64_PC32, Value);
}
} else if (RelType == ELF::R_X86_64_GOTPCREL ||
RelType == ELF::R_X86_64_GOTPCRELX ||
RelType == ELF::R_X86_64_REX_GOTPCRELX) {
uint64_t GOTOffset = allocateGOTEntries(1);
resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
ELF::R_X86_64_PC32);
// Fill in the value of the symbol we're targeting into the GOT
RelocationEntry RE =
computeGOTOffsetRE(GOTOffset, Value.Offset, ELF::R_X86_64_64);
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
} else if (RelType == ELF::R_X86_64_GOT64) {
// Fill in a 64-bit GOT offset.
uint64_t GOTOffset = allocateGOTEntries(1);
resolveRelocation(Sections[SectionID], Offset, GOTOffset,
ELF::R_X86_64_64, 0);
// Fill in the value of the symbol we're targeting into the GOT
RelocationEntry RE =
computeGOTOffsetRE(GOTOffset, Value.Offset, ELF::R_X86_64_64);
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
} else if (RelType == ELF::R_X86_64_GOTPC32) {
// Materialize the address of the base of the GOT relative to the PC.
// This doesn't create a GOT entry, but it does mean we need a GOT
// section.
(void)allocateGOTEntries(0);
resolveGOTOffsetRelocation(SectionID, Offset, Addend, ELF::R_X86_64_PC32);
} else if (RelType == ELF::R_X86_64_GOTPC64) {
(void)allocateGOTEntries(0);
resolveGOTOffsetRelocation(SectionID, Offset, Addend, ELF::R_X86_64_PC64);
} else if (RelType == ELF::R_X86_64_GOTOFF64) {
// GOTOFF relocations ultimately require a section difference relocation.
(void)allocateGOTEntries(0);
processSimpleRelocation(SectionID, Offset, RelType, Value);
} else if (RelType == ELF::R_X86_64_PC32) {
Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
processSimpleRelocation(SectionID, Offset, RelType, Value);
} else if (RelType == ELF::R_X86_64_PC64) {
Value.Addend += support::ulittle64_t::ref(computePlaceholderAddress(SectionID, Offset));
processSimpleRelocation(SectionID, Offset, RelType, Value);
} else if (RelType == ELF::R_X86_64_GOTTPOFF) {
processX86_64GOTTPOFFRelocation(SectionID, Offset, Value, Addend);
} else if (RelType == ELF::R_X86_64_TLSGD ||
RelType == ELF::R_X86_64_TLSLD) {
// The next relocation must be the relocation for __tls_get_addr.
++RelI;
auto &GetAddrRelocation = *RelI;
processX86_64TLSRelocation(SectionID, Offset, RelType, Value, Addend,
GetAddrRelocation);
} else {
processSimpleRelocation(SectionID, Offset, RelType, Value);
}
} else {
if (Arch == Triple::x86) {
Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
}
processSimpleRelocation(SectionID, Offset, RelType, Value);
}
return ++RelI;
}
void RuntimeDyldELF::processX86_64GOTTPOFFRelocation(unsigned SectionID,
uint64_t Offset,
RelocationValueRef Value,
int64_t Addend) {
// Use the approach from "x86-64 Linker Optimizations" from the TLS spec
// to replace the GOTTPOFF relocation with a TPOFF relocation. The spec
// only mentions one optimization even though there are two different
// code sequences for the Initial Exec TLS Model. We match the code to
// find out which one was used.
// A possible TLS code sequence and its replacement
struct CodeSequence {
// The expected code sequence
ArrayRef<uint8_t> ExpectedCodeSequence;
// The negative offset of the GOTTPOFF relocation to the beginning of
// the sequence
uint64_t TLSSequenceOffset;
// The new code sequence
ArrayRef<uint8_t> NewCodeSequence;
// The offset of the new TPOFF relocation
uint64_t TpoffRelocationOffset;
};
std::array<CodeSequence, 2> CodeSequences;
// Initial Exec Code Model Sequence
{
static const std::initializer_list<uint8_t> ExpectedCodeSequenceList = {
0x64, 0x48, 0x8b, 0x04, 0x25, 0x00, 0x00, 0x00,
0x00, // mov %fs:0, %rax
0x48, 0x03, 0x05, 0x00, 0x00, 0x00, 0x00 // add x@gotpoff(%rip),
// %rax
};
CodeSequences[0].ExpectedCodeSequence =
ArrayRef<uint8_t>(ExpectedCodeSequenceList);
CodeSequences[0].TLSSequenceOffset = 12;
static const std::initializer_list<uint8_t> NewCodeSequenceList = {
0x64, 0x48, 0x8b, 0x04, 0x25, 0x00, 0x00, 0x00, 0x00, // mov %fs:0, %rax
0x48, 0x8d, 0x80, 0x00, 0x00, 0x00, 0x00 // lea x@tpoff(%rax), %rax
};
CodeSequences[0].NewCodeSequence = ArrayRef<uint8_t>(NewCodeSequenceList);
CodeSequences[0].TpoffRelocationOffset = 12;
}
// Initial Exec Code Model Sequence, II
{
static const std::initializer_list<uint8_t> ExpectedCodeSequenceList = {
0x48, 0x8b, 0x05, 0x00, 0x00, 0x00, 0x00, // mov x@gotpoff(%rip), %rax
0x64, 0x48, 0x8b, 0x00, 0x00, 0x00, 0x00 // mov %fs:(%rax), %rax
};
CodeSequences[1].ExpectedCodeSequence =
ArrayRef<uint8_t>(ExpectedCodeSequenceList);
CodeSequences[1].TLSSequenceOffset = 3;
static const std::initializer_list<uint8_t> NewCodeSequenceList = {
0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00, // 6 byte nop
0x64, 0x8b, 0x04, 0x25, 0x00, 0x00, 0x00, 0x00, // mov %fs:x@tpoff, %rax
};
CodeSequences[1].NewCodeSequence = ArrayRef<uint8_t>(NewCodeSequenceList);
CodeSequences[1].TpoffRelocationOffset = 10;
}
bool Resolved = false;
auto &Section = Sections[SectionID];
for (const auto &C : CodeSequences) {
assert(C.ExpectedCodeSequence.size() == C.NewCodeSequence.size() &&
"Old and new code sequences must have the same size");
if (Offset < C.TLSSequenceOffset ||
(Offset - C.TLSSequenceOffset + C.NewCodeSequence.size()) >
Section.getSize()) {
// This can't be a matching sequence as it doesn't fit in the current
// section
continue;
}
auto TLSSequenceStartOffset = Offset - C.TLSSequenceOffset;
auto *TLSSequence = Section.getAddressWithOffset(TLSSequenceStartOffset);
if (ArrayRef<uint8_t>(TLSSequence, C.ExpectedCodeSequence.size()) !=
C.ExpectedCodeSequence) {
continue;
}
memcpy(TLSSequence, C.NewCodeSequence.data(), C.NewCodeSequence.size());
// The original GOTTPOFF relocation has an addend as it is PC relative,
// so it needs to be corrected. The TPOFF32 relocation is used as an
// absolute value (which is an offset from %fs:0), so remove the addend
// again.
RelocationEntry RE(SectionID,
TLSSequenceStartOffset + C.TpoffRelocationOffset,
ELF::R_X86_64_TPOFF32, Value.Addend - Addend);
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
Resolved = true;
break;
}
if (!Resolved) {
// The GOTTPOFF relocation was not used in one of the sequences
// described in the spec, so we can't optimize it to a TPOFF
// relocation.
uint64_t GOTOffset = allocateGOTEntries(1);
resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
ELF::R_X86_64_PC32);
RelocationEntry RE =
computeGOTOffsetRE(GOTOffset, Value.Offset, ELF::R_X86_64_TPOFF64);
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
}
}
void RuntimeDyldELF::processX86_64TLSRelocation(
unsigned SectionID, uint64_t Offset, uint64_t RelType,
RelocationValueRef Value, int64_t Addend,
const RelocationRef &GetAddrRelocation) {
// Since we are statically linking and have no additional DSOs, we can resolve
// the relocation directly without using __tls_get_addr.
// Use the approach from "x86-64 Linker Optimizations" from the TLS spec
// to replace it with the Local Exec relocation variant.
// Find out whether the code was compiled with the large or small memory
// model. For this we look at the next relocation which is the relocation
// for the __tls_get_addr function. If it's a 32 bit relocation, it's the
// small code model, with a 64 bit relocation it's the large code model.
bool IsSmallCodeModel;
// Is the relocation for the __tls_get_addr a PC-relative GOT relocation?
bool IsGOTPCRel = false;
switch (GetAddrRelocation.getType()) {
case ELF::R_X86_64_GOTPCREL:
case ELF::R_X86_64_REX_GOTPCRELX:
case ELF::R_X86_64_GOTPCRELX:
IsGOTPCRel = true;
[[fallthrough]];
case ELF::R_X86_64_PLT32:
IsSmallCodeModel = true;
break;
case ELF::R_X86_64_PLTOFF64:
IsSmallCodeModel = false;
break;
default:
report_fatal_error(
"invalid TLS relocations for General/Local Dynamic TLS Model: "
"expected PLT or GOT relocation for __tls_get_addr function");
}
// The negative offset to the start of the TLS code sequence relative to
// the offset of the TLSGD/TLSLD relocation
uint64_t TLSSequenceOffset;
// The expected start of the code sequence
ArrayRef<uint8_t> ExpectedCodeSequence;
// The new TLS code sequence that will replace the existing code
ArrayRef<uint8_t> NewCodeSequence;
if (RelType == ELF::R_X86_64_TLSGD) {
// The offset of the new TPOFF32 relocation (offset starting from the
// beginning of the whole TLS sequence)
uint64_t TpoffRelocOffset;
if (IsSmallCodeModel) {
if (!IsGOTPCRel) {
static const std::initializer_list<uint8_t> CodeSequence = {
0x66, // data16 (no-op prefix)
0x48, 0x8d, 0x3d, 0x00, 0x00,
0x00, 0x00, // lea <disp32>(%rip), %rdi
0x66, 0x66, // two data16 prefixes
0x48, // rex64 (no-op prefix)
0xe8, 0x00, 0x00, 0x00, 0x00 // call __tls_get_addr@plt
};
ExpectedCodeSequence = ArrayRef<uint8_t>(CodeSequence);
TLSSequenceOffset = 4;
} else {
// This code sequence is not described in the TLS spec but gcc
// generates it sometimes.
static const std::initializer_list<uint8_t> CodeSequence = {
0x66, // data16 (no-op prefix)
0x48, 0x8d, 0x3d, 0x00, 0x00,
0x00, 0x00, // lea <disp32>(%rip), %rdi
0x66, // data16 prefix (no-op prefix)
0x48, // rex64 (no-op prefix)
0xff, 0x15, 0x00, 0x00, 0x00,
0x00 // call *__tls_get_addr@gotpcrel(%rip)
};
ExpectedCodeSequence = ArrayRef<uint8_t>(CodeSequence);
TLSSequenceOffset = 4;
}
// The replacement code for the small code model. It's the same for
// both sequences.
static const std::initializer_list<uint8_t> SmallSequence = {
0x64, 0x48, 0x8b, 0x04, 0x25, 0x00, 0x00, 0x00,
0x00, // mov %fs:0, %rax
0x48, 0x8d, 0x80, 0x00, 0x00, 0x00, 0x00 // lea x@tpoff(%rax),
// %rax
};
NewCodeSequence = ArrayRef<uint8_t>(SmallSequence);
TpoffRelocOffset = 12;
} else {
static const std::initializer_list<uint8_t> CodeSequence = {
0x48, 0x8d, 0x3d, 0x00, 0x00, 0x00, 0x00, // lea <disp32>(%rip),
// %rdi
0x48, 0xb8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, // movabs $__tls_get_addr@pltoff, %rax
0x48, 0x01, 0xd8, // add %rbx, %rax
0xff, 0xd0 // call *%rax
};
ExpectedCodeSequence = ArrayRef<uint8_t>(CodeSequence);
TLSSequenceOffset = 3;
// The replacement code for the large code model
static const std::initializer_list<uint8_t> LargeSequence = {
0x64, 0x48, 0x8b, 0x04, 0x25, 0x00, 0x00, 0x00,
0x00, // mov %fs:0, %rax
0x48, 0x8d, 0x80, 0x00, 0x00, 0x00, 0x00, // lea x@tpoff(%rax),
// %rax
0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00 // nopw 0x0(%rax,%rax,1)
};
NewCodeSequence = ArrayRef<uint8_t>(LargeSequence);
TpoffRelocOffset = 12;
}
// The TLSGD/TLSLD relocations are PC-relative, so they have an addend.
// The new TPOFF32 relocations is used as an absolute offset from
// %fs:0, so remove the TLSGD/TLSLD addend again.
RelocationEntry RE(SectionID, Offset - TLSSequenceOffset + TpoffRelocOffset,
ELF::R_X86_64_TPOFF32, Value.Addend - Addend);
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
} else if (RelType == ELF::R_X86_64_TLSLD) {
if (IsSmallCodeModel) {
if (!IsGOTPCRel) {
static const std::initializer_list<uint8_t> CodeSequence = {
0x48, 0x8d, 0x3d, 0x00, 0x00, 0x00, // leaq <disp32>(%rip), %rdi
0x00, 0xe8, 0x00, 0x00, 0x00, 0x00 // call __tls_get_addr@plt
};
ExpectedCodeSequence = ArrayRef<uint8_t>(CodeSequence);
TLSSequenceOffset = 3;
// The replacement code for the small code model
static const std::initializer_list<uint8_t> SmallSequence = {
0x66, 0x66, 0x66, // three data16 prefixes (no-op)
0x64, 0x48, 0x8b, 0x04, 0x25,
0x00, 0x00, 0x00, 0x00 // mov %fs:0, %rax
};
NewCodeSequence = ArrayRef<uint8_t>(SmallSequence);
} else {
// This code sequence is not described in the TLS spec but gcc
// generates it sometimes.
static const std::initializer_list<uint8_t> CodeSequence = {
0x48, 0x8d, 0x3d, 0x00,
0x00, 0x00, 0x00, // leaq <disp32>(%rip), %rdi
0xff, 0x15, 0x00, 0x00,
0x00, 0x00 // call
// *__tls_get_addr@gotpcrel(%rip)
};
ExpectedCodeSequence = ArrayRef<uint8_t>(CodeSequence);
TLSSequenceOffset = 3;
// The replacement is code is just like above but it needs to be
// one byte longer.
static const std::initializer_list<uint8_t> SmallSequence = {
0x0f, 0x1f, 0x40, 0x00, // 4 byte nop
0x64, 0x48, 0x8b, 0x04, 0x25,
0x00, 0x00, 0x00, 0x00 // mov %fs:0, %rax
};
NewCodeSequence = ArrayRef<uint8_t>(SmallSequence);
}
} else {
// This is the same sequence as for the TLSGD sequence with the large
// memory model above
static const std::initializer_list<uint8_t> CodeSequence = {
0x48, 0x8d, 0x3d, 0x00, 0x00, 0x00, 0x00, // lea <disp32>(%rip),
// %rdi
0x48, 0xb8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x48, // movabs $__tls_get_addr@pltoff, %rax
0x01, 0xd8, // add %rbx, %rax
0xff, 0xd0 // call *%rax
};
ExpectedCodeSequence = ArrayRef<uint8_t>(CodeSequence);
TLSSequenceOffset = 3;
// The replacement code for the large code model
static const std::initializer_list<uint8_t> LargeSequence = {
0x66, 0x66, 0x66, // three data16 prefixes (no-op)
0x66, 0x66, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00,
0x00, // 10 byte nop
0x64, 0x48, 0x8b, 0x04, 0x25, 0x00, 0x00, 0x00, 0x00 // mov %fs:0,%rax
};
NewCodeSequence = ArrayRef<uint8_t>(LargeSequence);
}
} else {
llvm_unreachable("both TLS relocations handled above");
}
assert(ExpectedCodeSequence.size() == NewCodeSequence.size() &&
"Old and new code sequences must have the same size");
auto &Section = Sections[SectionID];
if (Offset < TLSSequenceOffset ||
(Offset - TLSSequenceOffset + NewCodeSequence.size()) >
Section.getSize()) {
report_fatal_error("unexpected end of section in TLS sequence");
}
auto *TLSSequence = Section.getAddressWithOffset(Offset - TLSSequenceOffset);
if (ArrayRef<uint8_t>(TLSSequence, ExpectedCodeSequence.size()) !=
ExpectedCodeSequence) {
report_fatal_error(
"invalid TLS sequence for Global/Local Dynamic TLS Model");
}
memcpy(TLSSequence, NewCodeSequence.data(), NewCodeSequence.size());
}
size_t RuntimeDyldELF::getGOTEntrySize() {
// We don't use the GOT in all of these cases, but it's essentially free
// to put them all here.
size_t Result = 0;
switch (Arch) {
case Triple::x86_64:
case Triple::aarch64:
case Triple::aarch64_be:
case Triple::ppc64:
case Triple::ppc64le:
case Triple::systemz:
Result = sizeof(uint64_t);
break;
case Triple::x86:
case Triple::arm:
case Triple::thumb:
Result = sizeof(uint32_t);
break;
case Triple::mips:
case Triple::mipsel:
case Triple::mips64:
case Triple::mips64el:
if (IsMipsO32ABI || IsMipsN32ABI)
Result = sizeof(uint32_t);
else if (IsMipsN64ABI)
Result = sizeof(uint64_t);
else
llvm_unreachable("Mips ABI not handled");
break;
default:
llvm_unreachable("Unsupported CPU type!");
}
return Result;
}
uint64_t RuntimeDyldELF::allocateGOTEntries(unsigned no) {
if (GOTSectionID == 0) {
GOTSectionID = Sections.size();
// Reserve a section id. We'll allocate the section later
// once we know the total size
Sections.push_back(SectionEntry(".got", nullptr, 0, 0, 0));
}
uint64_t StartOffset = CurrentGOTIndex * getGOTEntrySize();
CurrentGOTIndex += no;
return StartOffset;
}
uint64_t RuntimeDyldELF::findOrAllocGOTEntry(const RelocationValueRef &Value,
unsigned GOTRelType) {
auto E = GOTOffsetMap.insert({Value, 0});
if (E.second) {
uint64_t GOTOffset = allocateGOTEntries(1);
// Create relocation for newly created GOT entry
RelocationEntry RE =
computeGOTOffsetRE(GOTOffset, Value.Offset, GOTRelType);
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
E.first->second = GOTOffset;
}
return E.first->second;
}
void RuntimeDyldELF::resolveGOTOffsetRelocation(unsigned SectionID,
uint64_t Offset,
uint64_t GOTOffset,
uint32_t Type) {
// Fill in the relative address of the GOT Entry into the stub
RelocationEntry GOTRE(SectionID, Offset, Type, GOTOffset);
addRelocationForSection(GOTRE, GOTSectionID);
}
RelocationEntry RuntimeDyldELF::computeGOTOffsetRE(uint64_t GOTOffset,
uint64_t SymbolOffset,
uint32_t Type) {
return RelocationEntry(GOTSectionID, GOTOffset, Type, SymbolOffset);
}
void RuntimeDyldELF::processNewSymbol(const SymbolRef &ObjSymbol, SymbolTableEntry& Symbol) {
// This should never return an error as `processNewSymbol` wouldn't have been
// called if getFlags() returned an error before.
auto ObjSymbolFlags = cantFail(ObjSymbol.getFlags());
if (ObjSymbolFlags & SymbolRef::SF_Indirect) {
if (IFuncStubSectionID == 0) {
// Create a dummy section for the ifunc stubs. It will be actually
// allocated in finalizeLoad() below.
IFuncStubSectionID = Sections.size();
Sections.push_back(
SectionEntry(".text.__llvm_IFuncStubs", nullptr, 0, 0, 0));
// First 64B are reserverd for the IFunc resolver
IFuncStubOffset = 64;
}
IFuncStubs.push_back(IFuncStub{IFuncStubOffset, Symbol});
// Modify the symbol so that it points to the ifunc stub instead of to the
// resolver function.
Symbol = SymbolTableEntry(IFuncStubSectionID, IFuncStubOffset,
Symbol.getFlags());
IFuncStubOffset += getMaxIFuncStubSize();
}
}
Error RuntimeDyldELF::finalizeLoad(const ObjectFile &Obj,
ObjSectionToIDMap &SectionMap) {
if (IsMipsO32ABI)
if (!PendingRelocs.empty())
return make_error<RuntimeDyldError>("Can't find matching LO16 reloc");
// Create the IFunc stubs if necessary. This must be done before processing
// the GOT entries, as the IFunc stubs may create some.
if (IFuncStubSectionID != 0) {
uint8_t *IFuncStubsAddr = MemMgr.allocateCodeSection(
IFuncStubOffset, 1, IFuncStubSectionID, ".text.__llvm_IFuncStubs");
if (!IFuncStubsAddr)
return make_error<RuntimeDyldError>(
"Unable to allocate memory for IFunc stubs!");
Sections[IFuncStubSectionID] =
SectionEntry(".text.__llvm_IFuncStubs", IFuncStubsAddr, IFuncStubOffset,
IFuncStubOffset, 0);
createIFuncResolver(IFuncStubsAddr);
LLVM_DEBUG(dbgs() << "Creating IFunc stubs SectionID: "
<< IFuncStubSectionID << " Addr: "
<< Sections[IFuncStubSectionID].getAddress() << '\n');
for (auto &IFuncStub : IFuncStubs) {
auto &Symbol = IFuncStub.OriginalSymbol;
LLVM_DEBUG(dbgs() << "\tSectionID: " << Symbol.getSectionID()
<< " Offset: " << format("%p", Symbol.getOffset())
<< " IFuncStubOffset: "
<< format("%p\n", IFuncStub.StubOffset));
createIFuncStub(IFuncStubSectionID, 0, IFuncStub.StubOffset,
Symbol.getSectionID(), Symbol.getOffset());
}
IFuncStubSectionID = 0;
IFuncStubOffset = 0;
IFuncStubs.clear();
}
// If necessary, allocate the global offset table
if (GOTSectionID != 0) {
// Allocate memory for the section
size_t TotalSize = CurrentGOTIndex * getGOTEntrySize();
uint8_t *Addr = MemMgr.allocateDataSection(TotalSize, getGOTEntrySize(),
GOTSectionID, ".got", false);
if (!Addr)
return make_error<RuntimeDyldError>("Unable to allocate memory for GOT!");
Sections[GOTSectionID] =
SectionEntry(".got", Addr, TotalSize, TotalSize, 0);
// For now, initialize all GOT entries to zero. We'll fill them in as
// needed when GOT-based relocations are applied.
memset(Addr, 0, TotalSize);
if (IsMipsN32ABI || IsMipsN64ABI) {
// To correctly resolve Mips GOT relocations, we need a mapping from
// object's sections to GOTs.
for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
SI != SE; ++SI) {
if (SI->relocation_begin() != SI->relocation_end()) {
Expected<section_iterator> RelSecOrErr = SI->getRelocatedSection();
if (!RelSecOrErr)
return make_error<RuntimeDyldError>(
toString(RelSecOrErr.takeError()));
section_iterator RelocatedSection = *RelSecOrErr;
ObjSectionToIDMap::iterator i = SectionMap.find(*RelocatedSection);
assert(i != SectionMap.end());
SectionToGOTMap[i->second] = GOTSectionID;
}
}
GOTSymbolOffsets.clear();
}
}
// Look for and record the EH frame section.
ObjSectionToIDMap::iterator i, e;
for (i = SectionMap.begin(), e = SectionMap.end(); i != e; ++i) {
const SectionRef &Section = i->first;
StringRef Name;
Expected<StringRef> NameOrErr = Section.getName();
if (NameOrErr)
Name = *NameOrErr;
else
consumeError(NameOrErr.takeError());
if (Name == ".eh_frame") {
UnregisteredEHFrameSections.push_back(i->second);
break;
}
}
GOTOffsetMap.clear();
GOTSectionID = 0;
CurrentGOTIndex = 0;
return Error::success();
}
bool RuntimeDyldELF::isCompatibleFile(const object::ObjectFile &Obj) const {
return Obj.isELF();
}
void RuntimeDyldELF::createIFuncResolver(uint8_t *Addr) const {
if (Arch == Triple::x86_64) {
// The adddres of the GOT1 entry is in %r11, the GOT2 entry is in %r11+8
// (see createIFuncStub() for details)
// The following code first saves all registers that contain the original
// function arguments as those registers are not saved by the resolver
// function. %r11 is saved as well so that the GOT2 entry can be updated
// afterwards. Then it calls the actual IFunc resolver function whose
// address is stored in GOT2. After the resolver function returns, all
// saved registers are restored and the return value is written to GOT1.
// Finally, jump to the now resolved function.
// clang-format off
const uint8_t StubCode[] = {
0x57, // push %rdi
0x56, // push %rsi
0x52, // push %rdx
0x51, // push %rcx
0x41, 0x50, // push %r8
0x41, 0x51, // push %r9
0x41, 0x53, // push %r11
0x41, 0xff, 0x53, 0x08, // call *0x8(%r11)
0x41, 0x5b, // pop %r11
0x41, 0x59, // pop %r9
0x41, 0x58, // pop %r8
0x59, // pop %rcx
0x5a, // pop %rdx
0x5e, // pop %rsi
0x5f, // pop %rdi
0x49, 0x89, 0x03, // mov %rax,(%r11)
0xff, 0xe0 // jmp *%rax
};
// clang-format on
static_assert(sizeof(StubCode) <= 64,
"maximum size of the IFunc resolver is 64B");
memcpy(Addr, StubCode, sizeof(StubCode));
} else {
report_fatal_error(
"IFunc resolver is not supported for target architecture");
}
}
void RuntimeDyldELF::createIFuncStub(unsigned IFuncStubSectionID,
uint64_t IFuncResolverOffset,
uint64_t IFuncStubOffset,
unsigned IFuncSectionID,
uint64_t IFuncOffset) {
auto &IFuncStubSection = Sections[IFuncStubSectionID];
auto *Addr = IFuncStubSection.getAddressWithOffset(IFuncStubOffset);
if (Arch == Triple::x86_64) {
// The first instruction loads a PC-relative address into %r11 which is a
// GOT entry for this stub. This initially contains the address to the
// IFunc resolver. We can use %r11 here as it's caller saved but not used
// to pass any arguments. In fact, x86_64 ABI even suggests using %r11 for
// code in the PLT. The IFunc resolver will use %r11 to update the GOT
// entry.
//
// The next instruction just jumps to the address contained in the GOT
// entry. As mentioned above, we do this two-step jump by first setting
// %r11 so that the IFunc resolver has access to it.
//
// The IFunc resolver of course also needs to know the actual address of
// the actual IFunc resolver function. This will be stored in a GOT entry
// right next to the first one for this stub. So, the IFunc resolver will
// be able to call it with %r11+8.
//
// In total, two adjacent GOT entries (+relocation) and one additional
// relocation are required:
// GOT1: Address of the IFunc resolver.
// GOT2: Address of the IFunc resolver function.
// IFuncStubOffset+3: 32-bit PC-relative address of GOT1.
uint64_t GOT1 = allocateGOTEntries(2);
uint64_t GOT2 = GOT1 + getGOTEntrySize();
RelocationEntry RE1(GOTSectionID, GOT1, ELF::R_X86_64_64,
IFuncResolverOffset, {});
addRelocationForSection(RE1, IFuncStubSectionID);
RelocationEntry RE2(GOTSectionID, GOT2, ELF::R_X86_64_64, IFuncOffset, {});
addRelocationForSection(RE2, IFuncSectionID);
const uint8_t StubCode[] = {
0x4c, 0x8d, 0x1d, 0x00, 0x00, 0x00, 0x00, // leaq 0x0(%rip),%r11
0x41, 0xff, 0x23 // jmpq *(%r11)
};
assert(sizeof(StubCode) <= getMaxIFuncStubSize() &&
"IFunc stub size must not exceed getMaxIFuncStubSize()");
memcpy(Addr, StubCode, sizeof(StubCode));
// The PC-relative value starts 4 bytes from the end of the leaq
// instruction, so the addend is -4.
resolveGOTOffsetRelocation(IFuncStubSectionID, IFuncStubOffset + 3,
GOT1 - 4, ELF::R_X86_64_PC32);
} else {
report_fatal_error("IFunc stub is not supported for target architecture");
}
}
unsigned RuntimeDyldELF::getMaxIFuncStubSize() const {
if (Arch == Triple::x86_64) {
return 10;
}
return 0;
}
bool RuntimeDyldELF::relocationNeedsGot(const RelocationRef &R) const {
unsigned RelTy = R.getType();
if (Arch == Triple::aarch64 || Arch == Triple::aarch64_be)
return RelTy == ELF::R_AARCH64_ADR_GOT_PAGE ||
RelTy == ELF::R_AARCH64_LD64_GOT_LO12_NC;
if (Arch == Triple::x86_64)