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llvm-6502/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
Rafael Espindola efdbec8b0a Simplify the handling of iterators in ObjectFile. 
None of the object file formats reported error on iterator increment. In
retrospect, that is not too surprising: no object format stores symbols or
sections in a linked list or other structure that requires chasing pointers.
As a consequence, all error checking can be done on begin() and end().

This reduces the text segment of bin/llvm-readobj in my machine from 521233 to
518526 bytes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200442 91177308-0d34-0410-b5e6-96231b3b80d8
2014-01-30 02:49:50 +00:00

1445 lines
56 KiB
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//===-- RuntimeDyldELF.cpp - Run-time dynamic linker for MC-JIT -*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Implementation of ELF support for the MC-JIT runtime dynamic linker.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "dyld"
#include "RuntimeDyldELF.h"
#include "JITRegistrar.h"
#include "ObjectImageCommon.h"
#include "llvm/ADT/IntervalMap.h"
#include "llvm/ADT/OwningPtr.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Triple.h"
#include "llvm/ExecutionEngine/ObjectBuffer.h"
#include "llvm/ExecutionEngine/ObjectImage.h"
#include "llvm/Object/ELFObjectFile.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Support/ELF.h"
#include "llvm/Support/MemoryBuffer.h"
using namespace llvm;
using namespace llvm::object;
namespace {
static inline
error_code check(error_code Err) {
if (Err) {
report_fatal_error(Err.message());
}
return Err;
}
template<class ELFT>
class DyldELFObject
: public ELFObjectFile<ELFT> {
LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
typedef Elf_Shdr_Impl<ELFT> Elf_Shdr;
typedef Elf_Sym_Impl<ELFT> Elf_Sym;
typedef
Elf_Rel_Impl<ELFT, false> Elf_Rel;
typedef
Elf_Rel_Impl<ELFT, true> Elf_Rela;
typedef Elf_Ehdr_Impl<ELFT> Elf_Ehdr;
typedef typename ELFDataTypeTypedefHelper<
ELFT>::value_type addr_type;
public:
DyldELFObject(MemoryBuffer *Wrapper, error_code &ec);
void updateSectionAddress(const SectionRef &Sec, uint64_t Addr);
void updateSymbolAddress(const SymbolRef &Sym, uint64_t Addr);
// Methods for type inquiry through isa, cast and dyn_cast
static inline bool classof(const Binary *v) {
return (isa<ELFObjectFile<ELFT> >(v)
&& classof(cast<ELFObjectFile
<ELFT> >(v)));
}
static inline bool classof(
const ELFObjectFile<ELFT> *v) {
return v->isDyldType();
}
};
template<class ELFT>
class ELFObjectImage : public ObjectImageCommon {
protected:
DyldELFObject<ELFT> *DyldObj;
bool Registered;
public:
ELFObjectImage(ObjectBuffer *Input,
DyldELFObject<ELFT> *Obj)
: ObjectImageCommon(Input, Obj),
DyldObj(Obj),
Registered(false) {}
virtual ~ELFObjectImage() {
if (Registered)
deregisterWithDebugger();
}
// Subclasses can override these methods to update the image with loaded
// addresses for sections and common symbols
virtual void updateSectionAddress(const SectionRef &Sec, uint64_t Addr)
{
DyldObj->updateSectionAddress(Sec, Addr);
}
virtual void updateSymbolAddress(const SymbolRef &Sym, uint64_t Addr)
{
DyldObj->updateSymbolAddress(Sym, Addr);
}
virtual void registerWithDebugger()
{
JITRegistrar::getGDBRegistrar().registerObject(*Buffer);
Registered = true;
}
virtual void deregisterWithDebugger()
{
JITRegistrar::getGDBRegistrar().deregisterObject(*Buffer);
}
};
// 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(MemoryBuffer *Wrapper, error_code &ec)
: ELFObjectFile<ELFT>(Wrapper, ec) {
this->isDyldELFObject = true;
}
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);
}
} // namespace
namespace llvm {
void RuntimeDyldELF::registerEHFrames() {
if (!MemMgr)
return;
for (int i = 0, e = UnregisteredEHFrameSections.size(); i != e; ++i) {
SID EHFrameSID = UnregisteredEHFrameSections[i];
uint8_t *EHFrameAddr = Sections[EHFrameSID].Address;
uint64_t EHFrameLoadAddr = Sections[EHFrameSID].LoadAddress;
size_t EHFrameSize = Sections[EHFrameSID].Size;
MemMgr->registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
RegisteredEHFrameSections.push_back(EHFrameSID);
}
UnregisteredEHFrameSections.clear();
}
void RuntimeDyldELF::deregisterEHFrames() {
if (!MemMgr)
return;
for (int i = 0, e = RegisteredEHFrameSections.size(); i != e; ++i) {
SID EHFrameSID = RegisteredEHFrameSections[i];
uint8_t *EHFrameAddr = Sections[EHFrameSID].Address;
uint64_t EHFrameLoadAddr = Sections[EHFrameSID].LoadAddress;
size_t EHFrameSize = Sections[EHFrameSID].Size;
MemMgr->deregisterEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
}
RegisteredEHFrameSections.clear();
}
ObjectImage *RuntimeDyldELF::createObjectImageFromFile(object::ObjectFile *ObjFile) {
if (!ObjFile)
return NULL;
error_code ec;
MemoryBuffer* Buffer = MemoryBuffer::getMemBuffer(ObjFile->getData(),
"",
false);
if (ObjFile->getBytesInAddress() == 4 && ObjFile->isLittleEndian()) {
DyldELFObject<ELFType<support::little, 2, false> > *Obj =
new DyldELFObject<ELFType<support::little, 2, false> >(Buffer, ec);
return new ELFObjectImage<ELFType<support::little, 2, false> >(NULL, Obj);
}
else if (ObjFile->getBytesInAddress() == 4 && !ObjFile->isLittleEndian()) {
DyldELFObject<ELFType<support::big, 2, false> > *Obj =
new DyldELFObject<ELFType<support::big, 2, false> >(Buffer, ec);
return new ELFObjectImage<ELFType<support::big, 2, false> >(NULL, Obj);
}
else if (ObjFile->getBytesInAddress() == 8 && !ObjFile->isLittleEndian()) {
DyldELFObject<ELFType<support::big, 2, true> > *Obj =
new DyldELFObject<ELFType<support::big, 2, true> >(Buffer, ec);
return new ELFObjectImage<ELFType<support::big, 2, true> >(NULL, Obj);
}
else if (ObjFile->getBytesInAddress() == 8 && ObjFile->isLittleEndian()) {
DyldELFObject<ELFType<support::little, 2, true> > *Obj =
new DyldELFObject<ELFType<support::little, 2, true> >(Buffer, ec);
return new ELFObjectImage<ELFType<support::little, 2, true> >(NULL, Obj);
}
else
llvm_unreachable("Unexpected ELF format");
}
ObjectImage *RuntimeDyldELF::createObjectImage(ObjectBuffer *Buffer) {
if (Buffer->getBufferSize() < ELF::EI_NIDENT)
llvm_unreachable("Unexpected ELF object size");
std::pair<unsigned char, unsigned char> Ident = std::make_pair(
(uint8_t)Buffer->getBufferStart()[ELF::EI_CLASS],
(uint8_t)Buffer->getBufferStart()[ELF::EI_DATA]);
error_code ec;
if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2LSB) {
DyldELFObject<ELFType<support::little, 4, false> > *Obj =
new DyldELFObject<ELFType<support::little, 4, false> >(
Buffer->getMemBuffer(), ec);
return new ELFObjectImage<ELFType<support::little, 4, false> >(Buffer, Obj);
}
else if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2MSB) {
DyldELFObject<ELFType<support::big, 4, false> > *Obj =
new DyldELFObject<ELFType<support::big, 4, false> >(
Buffer->getMemBuffer(), ec);
return new ELFObjectImage<ELFType<support::big, 4, false> >(Buffer, Obj);
}
else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2MSB) {
DyldELFObject<ELFType<support::big, 8, true> > *Obj =
new DyldELFObject<ELFType<support::big, 8, true> >(
Buffer->getMemBuffer(), ec);
return new ELFObjectImage<ELFType<support::big, 8, true> >(Buffer, Obj);
}
else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2LSB) {
DyldELFObject<ELFType<support::little, 8, true> > *Obj =
new DyldELFObject<ELFType<support::little, 8, true> >(
Buffer->getMemBuffer(), ec);
return new ELFObjectImage<ELFType<support::little, 8, true> >(Buffer, Obj);
}
else
llvm_unreachable("Unexpected ELF format");
}
RuntimeDyldELF::~RuntimeDyldELF() {
}
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:
llvm_unreachable("Relocation type not implemented yet!");
break;
case ELF::R_X86_64_64: {
uint64_t *Target = reinterpret_cast<uint64_t*>(Section.Address + Offset);
*Target = Value + Addend;
DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend))
<< " at " << format("%p\n",Target));
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);
uint32_t *Target = reinterpret_cast<uint32_t*>(Section.Address + Offset);
*Target = TruncatedAddr;
DEBUG(dbgs() << "Writing " << format("%p", TruncatedAddr)
<< " at " << format("%p\n",Target));
break;
}
case ELF::R_X86_64_GOTPCREL: {
// findGOTEntry returns the 'G + GOT' part of the relocation calculation
// based on the load/target address of the GOT (not the current/local addr).
uint64_t GOTAddr = findGOTEntry(Value, SymOffset);
uint32_t *Target = reinterpret_cast<uint32_t*>(Section.Address + Offset);
uint64_t FinalAddress = Section.LoadAddress + Offset;
// The processRelocationRef method combines the symbol offset and the addend
// and in most cases that's what we want. For this relocation type, we need
// the raw addend, so we subtract the symbol offset to get it.
int64_t RealOffset = GOTAddr + Addend - SymOffset - FinalAddress;
assert(RealOffset <= INT32_MAX && RealOffset >= INT32_MIN);
int32_t TruncOffset = (RealOffset & 0xFFFFFFFF);
*Target = TruncOffset;
break;
}
case ELF::R_X86_64_PC32: {
// Get the placeholder value from the generated object since
// a previous relocation attempt may have overwritten the loaded version
uint32_t *Placeholder = reinterpret_cast<uint32_t*>(Section.ObjAddress
+ Offset);
uint32_t *Target = reinterpret_cast<uint32_t*>(Section.Address + Offset);
uint64_t FinalAddress = Section.LoadAddress + Offset;
int64_t RealOffset = *Placeholder + Value + Addend - FinalAddress;
assert(RealOffset <= INT32_MAX && RealOffset >= INT32_MIN);
int32_t TruncOffset = (RealOffset & 0xFFFFFFFF);
*Target = TruncOffset;
break;
}
case ELF::R_X86_64_PC64: {
// Get the placeholder value from the generated object since
// a previous relocation attempt may have overwritten the loaded version
uint64_t *Placeholder = reinterpret_cast<uint64_t*>(Section.ObjAddress
+ Offset);
uint64_t *Target = reinterpret_cast<uint64_t*>(Section.Address + Offset);
uint64_t FinalAddress = Section.LoadAddress + Offset;
*Target = *Placeholder + Value + Addend - FinalAddress;
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: {
// Get the placeholder value from the generated object since
// a previous relocation attempt may have overwritten the loaded version
uint32_t *Placeholder = reinterpret_cast<uint32_t*>(Section.ObjAddress
+ Offset);
uint32_t *Target = reinterpret_cast<uint32_t*>(Section.Address + Offset);
*Target = *Placeholder + Value + Addend;
break;
}
case ELF::R_386_PC32: {
// Get the placeholder value from the generated object since
// a previous relocation attempt may have overwritten the loaded version
uint32_t *Placeholder = reinterpret_cast<uint32_t*>(Section.ObjAddress
+ Offset);
uint32_t *Target = reinterpret_cast<uint32_t*>(Section.Address + Offset);
uint32_t FinalAddress = ((Section.LoadAddress + Offset) & 0xFFFFFFFF);
uint32_t RealOffset = *Placeholder + Value + Addend - FinalAddress;
*Target = RealOffset;
break;
}
default:
// There are other relocation types, but it appears these are the
// only ones currently used by the LLVM ELF object writer
llvm_unreachable("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.Address + Offset);
uint64_t FinalAddress = Section.LoadAddress + Offset;
DEBUG(dbgs() << "resolveAArch64Relocation, LocalAddress: 0x"
<< format("%llx", Section.Address + 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:
llvm_unreachable("Relocation type not implemented yet!");
break;
case ELF::R_AARCH64_ABS64: {
uint64_t *TargetPtr = reinterpret_cast<uint64_t*>(Section.Address + Offset);
*TargetPtr = Value + Addend;
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);
*TargetPtr = static_cast<uint32_t>(Result & 0xffffffffU);
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(-(1LL << 27) <= static_cast<int64_t>(BranchImm) &&
static_cast<int64_t>(BranchImm) < (1LL << 27));
// AArch64 code is emitted with .rela relocations. The data already in any
// bits affected by the relocation on entry is garbage.
*TargetPtr &= 0xfc000000U;
// Immediate goes in bits 25:0 of B and BL.
*TargetPtr |= static_cast<uint32_t>(BranchImm & 0xffffffcU) >> 2;
break;
}
case ELF::R_AARCH64_MOVW_UABS_G3: {
uint64_t Result = Value + Addend;
// AArch64 code is emitted with .rela relocations. The data already in any
// bits affected by the relocation on entry is garbage.
*TargetPtr &= 0xffe0001fU;
// Immediate goes in bits 20:5 of MOVZ/MOVK instruction
*TargetPtr |= Result >> (48 - 5);
// Shift must be "lsl #48", in bits 22:21
assert((*TargetPtr >> 21 & 0x3) == 3 && "invalid shift for relocation");
break;
}
case ELF::R_AARCH64_MOVW_UABS_G2_NC: {
uint64_t Result = Value + Addend;
// AArch64 code is emitted with .rela relocations. The data already in any
// bits affected by the relocation on entry is garbage.
*TargetPtr &= 0xffe0001fU;
// Immediate goes in bits 20:5 of MOVZ/MOVK instruction
*TargetPtr |= ((Result & 0xffff00000000ULL) >> (32 - 5));
// Shift must be "lsl #32", in bits 22:21
assert((*TargetPtr >> 21 & 0x3) == 2 && "invalid shift for relocation");
break;
}
case ELF::R_AARCH64_MOVW_UABS_G1_NC: {
uint64_t Result = Value + Addend;
// AArch64 code is emitted with .rela relocations. The data already in any
// bits affected by the relocation on entry is garbage.
*TargetPtr &= 0xffe0001fU;
// Immediate goes in bits 20:5 of MOVZ/MOVK instruction
*TargetPtr |= ((Result & 0xffff0000U) >> (16 - 5));
// Shift must be "lsl #16", in bits 22:2
assert((*TargetPtr >> 21 & 0x3) == 1 && "invalid shift for relocation");
break;
}
case ELF::R_AARCH64_MOVW_UABS_G0_NC: {
uint64_t Result = Value + Addend;
// AArch64 code is emitted with .rela relocations. The data already in any
// bits affected by the relocation on entry is garbage.
*TargetPtr &= 0xffe0001fU;
// Immediate goes in bits 20:5 of MOVZ/MOVK instruction
*TargetPtr |= ((Result & 0xffffU) << 5);
// Shift must be "lsl #0", in bits 22:21.
assert((*TargetPtr >> 21 & 0x3) == 0 && "invalid shift for relocation");
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 *Placeholder = reinterpret_cast<uint32_t*>(Section.ObjAddress +
Offset);
uint32_t* TargetPtr = (uint32_t*)(Section.Address + Offset);
uint32_t FinalAddress = ((Section.LoadAddress + Offset) & 0xFFFFFFFF);
Value += Addend;
DEBUG(dbgs() << "resolveARMRelocation, LocalAddress: "
<< Section.Address + 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 32bit value to relocation address, taking into account the
// implicit addend encoded in the target.
case ELF::R_ARM_PREL31:
case ELF::R_ARM_TARGET1:
case ELF::R_ARM_ABS32:
*TargetPtr = *Placeholder + 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:
// We are not expecting any other addend in the relocation address.
// Using 0x000F0FFF because MOVW has its 16 bit immediate split into 2
// non-contiguous fields.
assert((*Placeholder & 0x000F0FFF) == 0);
Value = Value & 0xFFFF;
*TargetPtr = *Placeholder | (Value & 0xFFF);
*TargetPtr |= ((Value >> 12) & 0xF) << 16;
break;
// Write last 16 bit of 32 bit value to the mov instruction.
// Last 4 bit should be shifted.
case ELF::R_ARM_MOVT_ABS:
// We are not expecting any other addend in the relocation address.
// Use 0x000F0FFF for the same reason as R_ARM_MOVW_ABS_NC.
assert((*Placeholder & 0x000F0FFF) == 0);
Value = (Value >> 16) & 0xFFFF;
*TargetPtr = *Placeholder | (Value & 0xFFF);
*TargetPtr |= ((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((*TargetPtr & 0xFFFFFF) == 0xFFFFFE);
*TargetPtr &= 0xFF000000;
*TargetPtr |= RelValue;
break;
}
case ELF::R_ARM_PRIVATE_0:
// This relocation is reserved by the ARM ELF ABI for internal use. We
// appropriate it here to act as an R_ARM_ABS32 without any addend for use
// in the stubs created during JIT (which can't put an addend into the
// original object file).
*TargetPtr = Value;
break;
}
}
void RuntimeDyldELF::resolveMIPSRelocation(const SectionEntry &Section,
uint64_t Offset,
uint32_t Value,
uint32_t Type,
int32_t Addend) {
uint32_t *Placeholder = reinterpret_cast<uint32_t*>(Section.ObjAddress +
Offset);
uint32_t* TargetPtr = (uint32_t*)(Section.Address + Offset);
Value += Addend;
DEBUG(dbgs() << "resolveMipselocation, LocalAddress: "
<< Section.Address + Offset
<< " FinalAddress: "
<< format("%p",Section.LoadAddress + Offset)
<< " Value: " << format("%x",Value)
<< " Type: " << format("%x",Type)
<< " Addend: " << format("%x",Addend)
<< "\n");
switch(Type) {
default:
llvm_unreachable("Not implemented relocation type!");
break;
case ELF::R_MIPS_32:
*TargetPtr = Value + (*Placeholder);
break;
case ELF::R_MIPS_26:
*TargetPtr = ((*Placeholder) & 0xfc000000) | (( Value & 0x0fffffff) >> 2);
break;
case ELF::R_MIPS_HI16:
// Get the higher 16-bits. Also add 1 if bit 15 is 1.
Value += ((*Placeholder) & 0x0000ffff) << 16;
*TargetPtr = ((*Placeholder) & 0xffff0000) |
(((Value + 0x8000) >> 16) & 0xffff);
break;
case ELF::R_MIPS_LO16:
Value += ((*Placeholder) & 0x0000ffff);
*TargetPtr = ((*Placeholder) & 0xffff0000) | (Value & 0xffff);
break;
case ELF::R_MIPS_UNUSED1:
// Similar to ELF::R_ARM_PRIVATE_0, R_MIPS_UNUSED1 and R_MIPS_UNUSED2
// are used for internal JIT purpose. These relocations are similar to
// R_MIPS_HI16 and R_MIPS_LO16, but they do not take any addend into
// account.
*TargetPtr = ((*TargetPtr) & 0xffff0000) |
(((Value + 0x8000) >> 16) & 0xffff);
break;
case ELF::R_MIPS_UNUSED2:
*TargetPtr = ((*TargetPtr) & 0xffff0000) | (Value & 0xffff);
break;
}
}
// Return the .TOC. section address to R_PPC64_TOC relocations.
uint64_t RuntimeDyldELF::findPPC64TOC() const {
// The TOC consists of sections .got, .toc, .tocbss, .plt in that
// order. The TOC starts where the first of these sections starts.
SectionList::const_iterator it = Sections.begin();
SectionList::const_iterator ite = Sections.end();
for (; it != ite; ++it) {
if (it->Name == ".got" ||
it->Name == ".toc" ||
it->Name == ".tocbss" ||
it->Name == ".plt")
break;
}
if (it == ite) {
// 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.
it = Sections.begin();
}
assert (it != ite);
// Per the ppc64-elf-linux ABI, The TOC base is TOC value plus 0x8000
// thus permitting a full 64 Kbytes segment.
return it->LoadAddress + 0x8000;
}
// Returns the sections and offset associated with the ODP entry referenced
// by Symbol.
void RuntimeDyldELF::findOPDEntrySection(ObjectImage &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.begin_sections(), se = Obj.end_sections();
si != se; ++si) {
section_iterator RelSecI = si->getRelocatedSection();
if (RelSecI == Obj.end_sections())
continue;
StringRef RelSectionName;
check(RelSecI->getName(RelSectionName));
if (RelSectionName != ".opd")
continue;
for (relocation_iterator i = si->begin_relocations(),
e = si->end_relocations(); i != e;) {
// The R_PPC64_ADDR64 relocation indicates the first field
// of a .opd entry
uint64_t TypeFunc;
check(i->getType(TypeFunc));
if (TypeFunc != ELF::R_PPC64_ADDR64) {
++i;
continue;
}
uint64_t TargetSymbolOffset;
symbol_iterator TargetSymbol = i->getSymbol();
check(i->getOffset(TargetSymbolOffset));
int64_t Addend;
check(getELFRelocationAddend(*i, Addend));
++i;
if (i == e)
break;
// Just check if following relocation is a R_PPC64_TOC
uint64_t TypeTOC;
check(i->getType(TypeTOC));
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.end_sections());
check(TargetSymbol->getSection(tsi));
Rel.SectionID = findOrEmitSection(Obj, (*tsi), true, LocalSections);
Rel.Addend = (intptr_t)Addend;
return;
}
}
llvm_unreachable("Attempting to get address of ODP entry!");
}
// Relocation masks following the #lo(value), #hi(value), #higher(value),
// and #highest(value) macros defined in section 4.5.1. Relocation Types
// in 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 applyPPChigher (uint64_t value)
{
return (value >> 32) & 0xffff;
}
static inline
uint16_t applyPPChighest (uint64_t value)
{
return (value >> 48) & 0xffff;
}
void RuntimeDyldELF::resolvePPC64Relocation(const SectionEntry &Section,
uint64_t Offset,
uint64_t Value,
uint32_t Type,
int64_t Addend) {
uint8_t* LocalAddress = Section.Address + Offset;
switch (Type) {
default:
llvm_unreachable("Relocation type not implemented yet!");
break;
case ELF::R_PPC64_ADDR16_LO :
writeInt16BE(LocalAddress, applyPPClo (Value + Addend));
break;
case ELF::R_PPC64_ADDR16_HI :
writeInt16BE(LocalAddress, applyPPChi (Value + Addend));
break;
case ELF::R_PPC64_ADDR16_HIGHER :
writeInt16BE(LocalAddress, applyPPChigher (Value + Addend));
break;
case ELF::R_PPC64_ADDR16_HIGHEST :
writeInt16BE(LocalAddress, applyPPChighest (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_ADDR32 : {
int32_t Result = static_cast<int32_t>(Value + Addend);
if (SignExtend32<32>(Result) != Result)
llvm_unreachable("Relocation R_PPC64_ADDR32 overflow");
writeInt32BE(LocalAddress, Result);
} break;
case ELF::R_PPC64_REL24 : {
uint64_t FinalAddress = (Section.LoadAddress + Offset);
int32_t delta = static_cast<int32_t>(Value - FinalAddress + Addend);
if (SignExtend32<24>(delta) != delta)
llvm_unreachable("Relocation R_PPC64_REL24 overflow");
// Generates a 'bl <address>' instruction
writeInt32BE(LocalAddress, 0x48000001 | (delta & 0x03FFFFFC));
} break;
case ELF::R_PPC64_REL32 : {
uint64_t FinalAddress = (Section.LoadAddress + Offset);
int32_t delta = static_cast<int32_t>(Value - FinalAddress + Addend);
if (SignExtend32<32>(delta) != delta)
llvm_unreachable("Relocation R_PPC64_REL32 overflow");
writeInt32BE(LocalAddress, delta);
} break;
case ELF::R_PPC64_REL64: {
uint64_t FinalAddress = (Section.LoadAddress + Offset);
uint64_t Delta = Value - FinalAddress + Addend;
writeInt64BE(LocalAddress, Delta);
} break;
case ELF::R_PPC64_ADDR64 :
writeInt64BE(LocalAddress, Value + Addend);
break;
case ELF::R_PPC64_TOC :
writeInt64BE(LocalAddress, findPPC64TOC());
break;
case ELF::R_PPC64_TOC16 : {
uint64_t TOCStart = findPPC64TOC();
Value = applyPPClo((Value + Addend) - TOCStart);
writeInt16BE(LocalAddress, applyPPClo(Value));
} break;
case ELF::R_PPC64_TOC16_DS : {
uint64_t TOCStart = findPPC64TOC();
Value = ((Value + Addend) - TOCStart);
writeInt16BE(LocalAddress, applyPPClo(Value));
} break;
}
}
void RuntimeDyldELF::resolveSystemZRelocation(const SectionEntry &Section,
uint64_t Offset,
uint64_t Value,
uint32_t Type,
int64_t Addend) {
uint8_t *LocalAddress = Section.Address + Offset;
switch (Type) {
default:
llvm_unreachable("Relocation type not implemented yet!");
break;
case ELF::R_390_PC16DBL:
case ELF::R_390_PLT16DBL: {
int64_t Delta = (Value + Addend) - (Section.LoadAddress + 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.LoadAddress + Offset);
assert(int32_t(Delta / 2) * 2 == Delta && "R_390_PC32DBL overflow");
writeInt32BE(LocalAddress, Delta / 2);
break;
}
case ELF::R_390_PC32: {
int64_t Delta = (Value + Addend) - (Section.LoadAddress + Offset);
assert(int32_t(Delta) == Delta && "R_390_PC32 overflow");
writeInt32BE(LocalAddress, Delta);
break;
}
case ELF::R_390_64:
writeInt64BE(LocalAddress, Value + Addend);
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);
}
void RuntimeDyldELF::resolveRelocation(const SectionEntry &Section,
uint64_t Offset,
uint64_t Value,
uint32_t Type,
int64_t Addend,
uint64_t SymOffset) {
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:
resolveAArch64Relocation(Section, Offset, Value, Type, Addend);
break;
case Triple::arm: // Fall through.
case Triple::thumb:
resolveARMRelocation(Section, Offset,
(uint32_t)(Value & 0xffffffffL), Type,
(uint32_t)(Addend & 0xffffffffL));
break;
case Triple::mips: // Fall through.
case Triple::mipsel:
resolveMIPSRelocation(Section, Offset,
(uint32_t)(Value & 0xffffffffL), Type,
(uint32_t)(Addend & 0xffffffffL));
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;
default: llvm_unreachable("Unsupported CPU type!");
}
}
void RuntimeDyldELF::processRelocationRef(unsigned SectionID,
RelocationRef RelI,
ObjectImage &Obj,
ObjSectionToIDMap &ObjSectionToID,
const SymbolTableMap &Symbols,
StubMap &Stubs) {
uint64_t RelType;
Check(RelI.getType(RelType));
int64_t Addend;
Check(getELFRelocationAddend(RelI, Addend));
symbol_iterator Symbol = RelI.getSymbol();
// Obtain the symbol name which is referenced in the relocation
StringRef TargetName;
if (Symbol != Obj.end_symbols())
Symbol->getName(TargetName);
DEBUG(dbgs() << "\t\tRelType: " << RelType
<< " Addend: " << Addend
<< " TargetName: " << TargetName
<< "\n");
RelocationValueRef Value;
// First search for the symbol in the local symbol table
SymbolTableMap::const_iterator lsi = Symbols.end();
SymbolRef::Type SymType = SymbolRef::ST_Unknown;
if (Symbol != Obj.end_symbols()) {
lsi = Symbols.find(TargetName.data());
Symbol->getType(SymType);
}
if (lsi != Symbols.end()) {
Value.SectionID = lsi->second.first;
Value.Offset = lsi->second.second;
Value.Addend = lsi->second.second + Addend;
} else {
// Search for the symbol in the global symbol table
SymbolTableMap::const_iterator gsi = GlobalSymbolTable.end();
if (Symbol != Obj.end_symbols())
gsi = GlobalSymbolTable.find(TargetName.data());
if (gsi != GlobalSymbolTable.end()) {
Value.SectionID = gsi->second.first;
Value.Offset = gsi->second.second;
Value.Addend = gsi->second.second + 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.
section_iterator si(Obj.end_sections());
Symbol->getSection(si);
if (si == Obj.end_sections())
llvm_unreachable("Symbol section not found, bad object file format!");
DEBUG(dbgs() << "\t\tThis is section symbol\n");
// Default to 'true' in case isText fails (though it never does).
bool isCode = true;
si->isText(isCode);
Value.SectionID = findOrEmitSection(Obj,
(*si),
isCode,
ObjSectionToID);
Value.Addend = Addend;
break;
}
case SymbolRef::ST_Data:
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;
Check(RelI.getOffset(Offset));
DEBUG(dbgs() << "\t\tSectionID: " << SectionID
<< " Offset: " << Offset
<< "\n");
if (Arch == Triple::aarch64 &&
(RelType == ELF::R_AARCH64_CALL26 ||
RelType == ELF::R_AARCH64_JUMP26)) {
// This is an AArch64 branch relocation, need to use a stub function.
DEBUG(dbgs() << "\t\tThis is an AArch64 branch relocation.");
SectionEntry &Section = Sections[SectionID];
// Look for an existing stub.
StubMap::const_iterator i = Stubs.find(Value);
if (i != Stubs.end()) {
resolveRelocation(Section, Offset,
(uint64_t)Section.Address + i->second, RelType, 0);
DEBUG(dbgs() << " Stub function found\n");
} else {
// Create a new stub function.
DEBUG(dbgs() << " Create a new stub function\n");
Stubs[Value] = Section.StubOffset;
uint8_t *StubTargetAddr = createStubFunction(Section.Address +
Section.StubOffset);
RelocationEntry REmovz_g3(SectionID,
StubTargetAddr - Section.Address,
ELF::R_AARCH64_MOVW_UABS_G3, Value.Addend);
RelocationEntry REmovk_g2(SectionID,
StubTargetAddr - Section.Address + 4,
ELF::R_AARCH64_MOVW_UABS_G2_NC, Value.Addend);
RelocationEntry REmovk_g1(SectionID,
StubTargetAddr - Section.Address + 8,
ELF::R_AARCH64_MOVW_UABS_G1_NC, Value.Addend);
RelocationEntry REmovk_g0(SectionID,
StubTargetAddr - Section.Address + 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,
(uint64_t)Section.Address + Section.StubOffset,
RelType, 0);
Section.StubOffset += getMaxStubSize();
}
} else if (Arch == Triple::arm &&
(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.
DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.");
SectionEntry &Section = Sections[SectionID];
// Look for an existing stub.
StubMap::const_iterator i = Stubs.find(Value);
if (i != Stubs.end()) {
resolveRelocation(Section, Offset,
(uint64_t)Section.Address + i->second, RelType, 0);
DEBUG(dbgs() << " Stub function found\n");
} else {
// Create a new stub function.
DEBUG(dbgs() << " Create a new stub function\n");
Stubs[Value] = Section.StubOffset;
uint8_t *StubTargetAddr = createStubFunction(Section.Address +
Section.StubOffset);
RelocationEntry RE(SectionID, StubTargetAddr - Section.Address,
ELF::R_ARM_PRIVATE_0, Value.Addend);
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
resolveRelocation(Section, Offset,
(uint64_t)Section.Address + Section.StubOffset,
RelType, 0);
Section.StubOffset += getMaxStubSize();
}
} else if ((Arch == Triple::mipsel || Arch == Triple::mips) &&
RelType == ELF::R_MIPS_26) {
// This is an Mips branch relocation, need to use a stub function.
DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
SectionEntry &Section = Sections[SectionID];
uint8_t *Target = Section.Address + Offset;
uint32_t *TargetAddress = (uint32_t *)Target;
// Extract the addend from the instruction.
uint32_t Addend = ((*TargetAddress) & 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);
DEBUG(dbgs() << " Stub function found\n");
} else {
// Create a new stub function.
DEBUG(dbgs() << " Create a new stub function\n");
Stubs[Value] = Section.StubOffset;
uint8_t *StubTargetAddr = createStubFunction(Section.Address +
Section.StubOffset);
// Creating Hi and Lo relocations for the filled stub instructions.
RelocationEntry REHi(SectionID,
StubTargetAddr - Section.Address,
ELF::R_MIPS_UNUSED1, Value.Addend);
RelocationEntry RELo(SectionID,
StubTargetAddr - Section.Address + 4,
ELF::R_MIPS_UNUSED2, 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.StubOffset);
addRelocationForSection(RE, SectionID);
Section.StubOffset += getMaxStubSize();
}
} else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
if (RelType == ELF::R_PPC64_REL24) {
// A PPC branch relocation will need a stub function if the target is
// an external symbol (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.Address + Offset;
bool RangeOverflow = false;
if (SymType != SymbolRef::ST_Unknown) {
// A function call may points to the .opd entry, so the final symbol value
// in calculated based in the relocation values in .opd section.
findOPDEntrySection(Obj, ObjSectionToID, Value);
uint8_t *RelocTarget = Sections[Value.SectionID].Address + Value.Addend;
int32_t delta = static_cast<int32_t>(Target - RelocTarget);
// If it is within 24-bits branch range, just set the branch target
if (SignExtend32<24>(delta) == delta) {
RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
} else {
RangeOverflow = true;
}
}
if (SymType == SymbolRef::ST_Unknown || RangeOverflow == true) {
// It is an external symbol (SymbolRef::ST_Unknown) or within a range
// larger than 24-bits.
StubMap::const_iterator i = Stubs.find(Value);
if (i != Stubs.end()) {
// Symbol function stub already created, just relocate to it
resolveRelocation(Section, Offset,
(uint64_t)Section.Address + i->second, RelType, 0);
DEBUG(dbgs() << " Stub function found\n");
} else {
// Create a new stub function.
DEBUG(dbgs() << " Create a new stub function\n");
Stubs[Value] = Section.StubOffset;
uint8_t *StubTargetAddr = createStubFunction(Section.Address +
Section.StubOffset);
RelocationEntry RE(SectionID, StubTargetAddr - Section.Address,
ELF::R_PPC64_ADDR64, Value.Addend);
// Generates the 64-bits address loads as exemplified in section
// 4.5.1 in PPC64 ELF ABI.
RelocationEntry REhst(SectionID,
StubTargetAddr - Section.Address + 2,
ELF::R_PPC64_ADDR16_HIGHEST, Value.Addend);
RelocationEntry REhr(SectionID,
StubTargetAddr - Section.Address + 6,
ELF::R_PPC64_ADDR16_HIGHER, Value.Addend);
RelocationEntry REh(SectionID,
StubTargetAddr - Section.Address + 14,
ELF::R_PPC64_ADDR16_HI, Value.Addend);
RelocationEntry REl(SectionID,
StubTargetAddr - Section.Address + 18,
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,
(uint64_t)Section.Address + Section.StubOffset,
RelType, 0);
if (SymType == SymbolRef::ST_Unknown)
// Restore the TOC for external calls
writeInt32BE(Target+4, 0xE8410028); // ld r2,40(r1)
Section.StubOffset += getMaxStubSize();
}
}
} else {
RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
// Extra check to avoid relocation againt empty symbols (usually
// the R_PPC64_TOC).
if (SymType != SymbolRef::ST_Unknown && TargetName.empty())
Value.SymbolName = NULL;
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.
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.Address) + i->second;
DEBUG(dbgs() << " Stub function found\n");
} else {
// Create a new stub function.
DEBUG(dbgs() << " Create a new stub function\n");
uintptr_t BaseAddress = uintptr_t(Section.Address);
uintptr_t StubAlignment = getStubAlignment();
StubAddress = (BaseAddress + Section.StubOffset +
StubAlignment - 1) & -StubAlignment;
unsigned StubOffset = StubAddress - BaseAddress;
Stubs[Value] = StubOffset;
createStubFunction((uint8_t *)StubAddress);
RelocationEntry RE(SectionID, StubOffset + 8,
ELF::R_390_64, Value.Addend - Addend);
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
Section.StubOffset = StubOffset + 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 && 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) {
// 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.Address) + i->second;
DEBUG(dbgs() << " Stub function found\n");
} else {
// Create a new stub function (equivalent to a PLT entry).
DEBUG(dbgs() << " Create a new stub function\n");
uintptr_t BaseAddress = uintptr_t(Section.Address);
uintptr_t StubAlignment = getStubAlignment();
StubAddress = (BaseAddress + Section.StubOffset +
StubAlignment - 1) & -StubAlignment;
unsigned StubOffset = StubAddress - BaseAddress;
Stubs[Value] = StubOffset;
createStubFunction((uint8_t *)StubAddress);
// Create a GOT entry for the external function.
GOTEntries.push_back(Value);
// Make our stub function a relative call to the GOT entry.
RelocationEntry RE(SectionID, StubOffset + 2,
ELF::R_X86_64_GOTPCREL, -4);
addRelocationForSymbol(RE, Value.SymbolName);
// Bump our stub offset counter
Section.StubOffset = StubOffset + getMaxStubSize();
}
// Make the target call a call into the stub table.
resolveRelocation(Section, Offset, StubAddress,
ELF::R_X86_64_PC32, Addend);
} else {
RelocationEntry RE(SectionID, Offset, ELF::R_X86_64_PC32, Value.Addend,
Value.Offset);
addRelocationForSection(RE, Value.SectionID);
}
} else {
if (Arch == Triple::x86_64 && RelType == ELF::R_X86_64_GOTPCREL) {
GOTEntries.push_back(Value);
}
RelocationEntry RE(SectionID, Offset, RelType, Value.Addend, Value.Offset);
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
}
}
void RuntimeDyldELF::updateGOTEntries(StringRef Name, uint64_t Addr) {
SmallVectorImpl<std::pair<SID, GOTRelocations> >::iterator it;
SmallVectorImpl<std::pair<SID, GOTRelocations> >::iterator end = GOTs.end();
for (it = GOTs.begin(); it != end; ++it) {
GOTRelocations &GOTEntries = it->second;
for (int i = 0, e = GOTEntries.size(); i != e; ++i) {
if (GOTEntries[i].SymbolName != 0 && GOTEntries[i].SymbolName == Name) {
GOTEntries[i].Offset = Addr;
}
}
}
}
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::ppc64:
case Triple::ppc64le:
case Triple::systemz:
Result = sizeof(uint64_t);
break;
case Triple::x86:
case Triple::arm:
case Triple::thumb:
case Triple::mips:
case Triple::mipsel:
Result = sizeof(uint32_t);
break;
default: llvm_unreachable("Unsupported CPU type!");
}
return Result;
}
uint64_t RuntimeDyldELF::findGOTEntry(uint64_t LoadAddress,
uint64_t Offset) {
const size_t GOTEntrySize = getGOTEntrySize();
SmallVectorImpl<std::pair<SID, GOTRelocations> >::const_iterator it;
SmallVectorImpl<std::pair<SID, GOTRelocations> >::const_iterator end = GOTs.end();
int GOTIndex = -1;
for (it = GOTs.begin(); it != end; ++it) {
SID GOTSectionID = it->first;
const GOTRelocations &GOTEntries = it->second;
// Find the matching entry in our vector.
uint64_t SymbolOffset = 0;
for (int i = 0, e = GOTEntries.size(); i != e; ++i) {
if (GOTEntries[i].SymbolName == 0) {
if (getSectionLoadAddress(GOTEntries[i].SectionID) == LoadAddress &&
GOTEntries[i].Offset == Offset) {
GOTIndex = i;
SymbolOffset = GOTEntries[i].Offset;
break;
}
} else {
// GOT entries for external symbols use the addend as the address when
// the external symbol has been resolved.
if (GOTEntries[i].Offset == LoadAddress) {
GOTIndex = i;
// Don't use the Addend here. The relocation handler will use it.
break;
}
}
}
if (GOTIndex != -1) {
if (GOTEntrySize == sizeof(uint64_t)) {
uint64_t *LocalGOTAddr = (uint64_t*)getSectionAddress(GOTSectionID);
// Fill in this entry with the address of the symbol being referenced.
LocalGOTAddr[GOTIndex] = LoadAddress + SymbolOffset;
} else {
uint32_t *LocalGOTAddr = (uint32_t*)getSectionAddress(GOTSectionID);
// Fill in this entry with the address of the symbol being referenced.
LocalGOTAddr[GOTIndex] = (uint32_t)(LoadAddress + SymbolOffset);
}
// Calculate the load address of this entry
return getSectionLoadAddress(GOTSectionID) + (GOTIndex * GOTEntrySize);
}
}
assert(GOTIndex != -1 && "Unable to find requested GOT entry.");
return 0;
}
void RuntimeDyldELF::finalizeLoad(ObjSectionToIDMap &SectionMap) {
// If necessary, allocate the global offset table
if (MemMgr) {
// Allocate the GOT if necessary
size_t numGOTEntries = GOTEntries.size();
if (numGOTEntries != 0) {
// Allocate memory for the section
unsigned SectionID = Sections.size();
size_t TotalSize = numGOTEntries * getGOTEntrySize();
uint8_t *Addr = MemMgr->allocateDataSection(TotalSize, getGOTEntrySize(),
SectionID, ".got", false);
if (!Addr)
report_fatal_error("Unable to allocate memory for GOT!");
GOTs.push_back(std::make_pair(SectionID, GOTEntries));
Sections.push_back(SectionEntry(".got", Addr, 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);
}
}
else {
report_fatal_error("Unable to allocate memory for GOT!");
}
// 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;
Section.getName(Name);
if (Name == ".eh_frame") {
UnregisteredEHFrameSections.push_back(i->second);
break;
}
}
}
bool RuntimeDyldELF::isCompatibleFormat(const ObjectBuffer *Buffer) const {
if (Buffer->getBufferSize() < strlen(ELF::ElfMagic))
return false;
return (memcmp(Buffer->getBufferStart(), ELF::ElfMagic, strlen(ELF::ElfMagic))) == 0;
}
bool RuntimeDyldELF::isCompatibleFile(const object::ObjectFile *Obj) const {
return Obj->isELF();
}
} // namespace llvm
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