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llvm-mirror/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
Yonghong Song 1d0a1ee04d BPF: Add more relocation kinds 
Currently, BPF only contains three relocations:
  R_BPF_NONE   for no relocation
  R_BPF_64_64  for LD_imm64 and normal 64-bit data relocation
  R_BPF_64_32  for call insn and normal 32-bit data relocation

Also .BTF and .BTF.ext sections contain symbols in allocated
program and data sections. These two sections reserved 32bit
space to hold the offset relative to the symbol's section.
When LLVM JIT is used, the LLVM ExecutionEngine RuntimeDyld
may attempt to resolve relocations for .BTF and .BTF.ext,
which we want to prevent. So we used R_BPF_NONE for such relocations.

This all works fine until when we try to do linking of
multiple objects.
  . R_BPF_64_64 handling of LD_imm64 vs. normal 64-bit data
    is different, so lld target->relocate() needs more context
    to do a correct job.
  . The same for R_BPF_64_32. More context is needed for
    lld target->relocate() to differentiate call insn vs.
    normal 32-bit data relocation.
  . Since relocations in .BTF and .BTF.ext are set to R_BPF_NONE,
    they will not be relocated properly when multiple .BTF/.BTF.ext
    sections are merged by lld.

This patch intends to address this issue by adding additional
relocation kinds:
  R_BPF_64_ABS64     for normal 64-bit data relocation
  R_BPF_64_ABS32     for normal 32-bit data relocation
  R_BPF_64_NODYLD32  for .BTF and .BTF.ext style relocations.
The old R_BPF_64_{64,32} semantics:
  R_BPF_64_64        for LD_imm64 relocation
  R_BPF_64_32        for call insn relocation

The existing R_BPF_64_64/R_BPF_64_32 mapping to numeric values
is maintained. They are the most common use cases for
bpf programs and we want to maintain backward compatibility
as much as possible.

ExecutionEngine RuntimeDyld BPF relocations are adjusted as well.
R_BPF_64_{ABS64,ABS32} relocations will be resolved properly and
other relocations will be ignored.
Two tests are added for RuntimeDyld. Not handling R_BPF_64_NODYLD32 in
RuntimeDyldELF.cpp will result in "Relocation type not implemented yet!"
fatal error.

FK_SecRel_4 usages in BPFAsmBackend.cpp and BPFELFObjectWriter.cpp
are removed as they are not triggered in BPF backend.
BPF backend used FK_SecRel_8 for LD_imm64 instruction operands.

Differential Revision: https://reviews.llvm.org/D102712
2021-05-25 08:19:13 -07:00

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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/ADT/Triple.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"
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, support::big>(P, V) : write<T, support::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() {}
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;
}
}
}
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_ABS16: {
uint64_t Result = Value + Addend;
assert(static_cast<int64_t>(Result) >= INT16_MIN && Result < UINT16_MAX);
write(isBE, TargetPtr, static_cast<uint16_t>(Result & 0xffffU));
break;
}
case ELF::R_AARCH64_ABS32: {
uint64_t Result = Value + Addend;
assert(static_cast<int64_t>(Result) >= INT32_MIN && Result < UINT32_MAX);
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_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));
*TargetPtr &= 0xfff8001fU;
// Immediate:15:2 goes in bits 18:5 of TBZ, TBNZ
or32le(TargetPtr, (BranchImm & 0x0FFFFFFC) << 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 ||
!StringRef(Triple::getArchTypePrefix(Arch)).equals("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().equals("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(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);
OS.flush();
report_fatal_error(Buf);
}
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);
OS.flush();
report_fatal_error(Buf);
}
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_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) {
// Craete 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());
uintptr_t StubAlignment = getStubAlignment();
StubAddress =
(BaseAddress + Section.getStubOffset() + StubAlignment - 1) &
-StubAlignment;
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());
uintptr_t StubAlignment = getStubAlignment();
StubAddress =
(BaseAddress + Section->getStubOffset() + StubAlignment - 1) &
-StubAlignment;
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_GOTPC64) {
// 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_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 {
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;
}
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);
}
Error RuntimeDyldELF::finalizeLoad(const ObjectFile &Obj,
ObjSectionToIDMap &SectionMap) {
if (IsMipsO32ABI)
if (!PendingRelocs.empty())
return make_error<RuntimeDyldError>("Can't find matching LO16 reloc");
// 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;
}
}
GOTSectionID = 0;
CurrentGOTIndex = 0;
return Error::success();
}
bool RuntimeDyldELF::isCompatibleFile(const object::ObjectFile &Obj) const {
return Obj.isELF();
}
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)
return RelTy == ELF::R_X86_64_GOTPCREL ||
RelTy == ELF::R_X86_64_GOTPCRELX ||
RelTy == ELF::R_X86_64_GOT64 ||
RelTy == ELF::R_X86_64_REX_GOTPCRELX;
return false;
}
bool RuntimeDyldELF::relocationNeedsStub(const RelocationRef &R) const {
if (Arch != Triple::x86_64)
return true; // Conservative answer
switch (R.getType()) {
default:
return true; // Conservative answer
case ELF::R_X86_64_GOTPCREL:
case ELF::R_X86_64_GOTPCRELX:
case ELF::R_X86_64_REX_GOTPCRELX:
case ELF::R_X86_64_GOTPC64:
case ELF::R_X86_64_GOT64:
case ELF::R_X86_64_GOTOFF64:
case ELF::R_X86_64_PC32:
case ELF::R_X86_64_PC64:
case ELF::R_X86_64_64:
// We know that these reloation types won't need a stub function. This list
// can be extended as needed.
return false;
}
}
} // namespace llvm
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