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llvm-6502/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
Akira Hatanaka ade047463f Runtime dynamic linker for MCJIT should support MIPS BigEndian architecture. 
This small change adds support for that. It will make all MCJIT tests pass
in make-check on BigEndian platforms.

Patch by Petar Jovanovic.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169178 91177308-0d34-0410-b5e6-96231b3b80d8
2012-12-03 23:12:19 +00:00

837 lines
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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/ELF.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Support/ELF.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<support::endianness target_endianness, bool is64Bits>
class DyldELFObject : public ELFObjectFile<target_endianness, is64Bits> {
LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
typedef Elf_Shdr_Impl<target_endianness, is64Bits> Elf_Shdr;
typedef Elf_Sym_Impl<target_endianness, is64Bits> Elf_Sym;
typedef Elf_Rel_Impl<target_endianness, is64Bits, false> Elf_Rel;
typedef Elf_Rel_Impl<target_endianness, is64Bits, true> Elf_Rela;
typedef Elf_Ehdr_Impl<target_endianness, is64Bits> Elf_Ehdr;
typedef typename ELFDataTypeTypedefHelper<
target_endianness, is64Bits>::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<target_endianness, is64Bits> >(v)
&& classof(cast<ELFObjectFile<target_endianness, is64Bits> >(v)));
}
static inline bool classof(
const ELFObjectFile<target_endianness, is64Bits> *v) {
return v->isDyldType();
}
};
template<support::endianness target_endianness, bool is64Bits>
class ELFObjectImage : public ObjectImageCommon {
protected:
DyldELFObject<target_endianness, is64Bits> *DyldObj;
bool Registered;
public:
ELFObjectImage(ObjectBuffer *Input,
DyldELFObject<target_endianness, is64Bits> *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<support::endianness target_endianness, bool is64Bits>
DyldELFObject<target_endianness, is64Bits>::DyldELFObject(MemoryBuffer *Wrapper,
error_code &ec)
: ELFObjectFile<target_endianness, is64Bits>(Wrapper, ec) {
this->isDyldELFObject = true;
}
template<support::endianness target_endianness, bool is64Bits>
void DyldELFObject<target_endianness, is64Bits>::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<support::endianness target_endianness, bool is64Bits>
void DyldELFObject<target_endianness, is64Bits>::updateSymbolAddress(
const SymbolRef &SymRef,
uint64_t Addr) {
Elf_Sym *sym = const_cast<Elf_Sym*>(
ELFObjectFile<target_endianness, is64Bits>::
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 {
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<support::little, false> *Obj =
new DyldELFObject<support::little, false>(Buffer->getMemBuffer(), ec);
return new ELFObjectImage<support::little, false>(Buffer, Obj);
}
else if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2MSB) {
DyldELFObject<support::big, false> *Obj =
new DyldELFObject<support::big, false>(Buffer->getMemBuffer(), ec);
return new ELFObjectImage<support::big, false>(Buffer, Obj);
}
else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2MSB) {
DyldELFObject<support::big, true> *Obj =
new DyldELFObject<support::big, true>(Buffer->getMemBuffer(), ec);
return new ELFObjectImage<support::big, true>(Buffer, Obj);
}
else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2LSB) {
DyldELFObject<support::little, true> *Obj =
new DyldELFObject<support::little, true>(Buffer->getMemBuffer(), ec);
return new ELFObjectImage<support::little, 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) {
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_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;
}
}
}
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::resolveARMRelocation(const SectionEntry &Section,
uint64_t Offset,
uint32_t Value,
uint32_t Type,
int32_t Addend) {
// TODO: Add Thumb relocations.
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!");
// Write a 32bit value to relocation address, taking into account the
// implicit addend encoded in the target.
case ELF::R_ARM_TARGET1 :
case ELF::R_ARM_ABS32 :
*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 :
// 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((*TargetPtr & 0x000F0FFF) == 0);
Value = Value & 0xFFFF;
*TargetPtr |= 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((*TargetPtr & 0x000F0FFF) == 0);
Value = (Value >> 16) & 0xFFFF;
*TargetPtr |= 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;
*TargetPtr &= 0xFF000000;
*TargetPtr |= RelValue;
break;
}
}
void RuntimeDyldELF::resolveMIPSRelocation(const SectionEntry &Section,
uint64_t Offset,
uint32_t Value,
uint32_t Type,
int32_t Addend) {
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 + (*TargetPtr);
break;
case ELF::R_MIPS_26:
*TargetPtr = ((*TargetPtr) & 0xfc000000) | (( Value & 0x0fffffff) >> 2);
break;
case ELF::R_MIPS_HI16:
// Get the higher 16-bits. Also add 1 if bit 15 is 1.
Value += ((*TargetPtr) & 0x0000ffff) << 16;
*TargetPtr = ((*TargetPtr) & 0xffff0000) |
(((Value + 0x8000) >> 16) & 0xffff);
break;
case ELF::R_MIPS_LO16:
Value += ((*TargetPtr) & 0x0000ffff);
*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
error_code err;
for (section_iterator si = Obj.begin_sections(),
se = Obj.end_sections(); si != se; si.increment(err)) {
StringRef SectionName;
check(si->getName(SectionName));
if (SectionName != ".opd")
continue;
for (relocation_iterator i = si->begin_relocations(),
e = si->end_relocations(); i != e;) {
check(err);
// 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.increment(err);
continue;
}
SymbolRef TargetSymbol;
uint64_t TargetSymbolOffset;
int64_t TargetAdditionalInfo;
check(i->getSymbol(TargetSymbol));
check(i->getOffset(TargetSymbolOffset));
check(i->getAdditionalInfo(TargetAdditionalInfo));
i = i.increment(err);
if (i == e)
break;
check(err);
// 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 != (intptr_t)TargetSymbolOffset)
continue;
section_iterator tsi(Obj.end_sections());
check(TargetSymbol.getSection(tsi));
Rel.SectionID = findOrEmitSection(Obj, (*tsi), true, LocalSections);
Rel.Addend = (intptr_t)TargetAdditionalInfo;
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_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_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::resolveRelocation(const SectionEntry &Section,
uint64_t Offset,
uint64_t Value,
uint32_t Type,
int64_t Addend) {
switch (Arch) {
case Triple::x86_64:
resolveX86_64Relocation(Section, Offset, Value, Type, Addend);
break;
case Triple::x86:
resolveX86Relocation(Section, Offset,
(uint32_t)(Value & 0xffffffffL), Type,
(uint32_t)(Addend & 0xffffffffL));
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:
resolvePPC64Relocation(Section, Offset, Value, Type, Addend);
break;
default: llvm_unreachable("Unsupported CPU type!");
}
}
void RuntimeDyldELF::processRelocationRef(const ObjRelocationInfo &Rel,
ObjectImage &Obj,
ObjSectionToIDMap &ObjSectionToID,
const SymbolTableMap &Symbols,
StubMap &Stubs) {
uint32_t RelType = (uint32_t)(Rel.Type & 0xffffffffL);
intptr_t Addend = (intptr_t)Rel.AdditionalInfo;
const SymbolRef &Symbol = Rel.Symbol;
// Obtain the symbol name which is referenced in the relocation
StringRef TargetName;
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.find(TargetName.data());
SymbolRef::Type SymType;
Symbol.getType(SymType);
if (lsi != Symbols.end()) {
Value.SectionID = lsi->second.first;
Value.Addend = lsi->second.second;
} else {
// Search for the symbol in the global symbol table
SymbolTableMap::const_iterator gsi =
GlobalSymbolTable.find(TargetName.data());
if (gsi != GlobalSymbolTable.end()) {
Value.SectionID = gsi->second.first;
Value.Addend = gsi->second.second;
} 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_Unknown: {
Value.SymbolName = TargetName.data();
Value.Addend = Addend;
break;
}
default:
llvm_unreachable("Unresolved symbol type!");
break;
}
}
}
DEBUG(dbgs() << "\t\tRel.SectionID: " << Rel.SectionID
<< " Rel.Offset: " << Rel.Offset
<< "\n");
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[Rel.SectionID];
// Look for an existing stub.
StubMap::const_iterator i = Stubs.find(Value);
if (i != Stubs.end()) {
resolveRelocation(Section, Rel.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(Rel.SectionID, StubTargetAddr - Section.Address,
ELF::R_ARM_ABS32, Value.Addend);
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
resolveRelocation(Section, Rel.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[Rel.SectionID];
uint8_t *Target = Section.Address + Rel.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()) {
resolveRelocation(Section, Rel.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);
// Creating Hi and Lo relocations for the filled stub instructions.
RelocationEntry REHi(Rel.SectionID,
StubTargetAddr - Section.Address,
ELF::R_MIPS_HI16, Value.Addend);
RelocationEntry RELo(Rel.SectionID,
StubTargetAddr - Section.Address + 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);
}
resolveRelocation(Section, Rel.Offset,
(uint64_t)Section.Address + Section.StubOffset,
RelType, 0);
Section.StubOffset += getMaxStubSize();
}
} else if (Arch == Triple::ppc64) {
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[Rel.SectionID];
uint8_t *Target = Section.Address + Rel.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(Rel.SectionID, Rel.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, Rel.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(Rel.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(Rel.SectionID,
StubTargetAddr - Section.Address + 2,
ELF::R_PPC64_ADDR16_HIGHEST, Value.Addend);
RelocationEntry REhr(Rel.SectionID,
StubTargetAddr - Section.Address + 6,
ELF::R_PPC64_ADDR16_HIGHER, Value.Addend);
RelocationEntry REh(Rel.SectionID,
StubTargetAddr - Section.Address + 14,
ELF::R_PPC64_ADDR16_HI, Value.Addend);
RelocationEntry REl(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, Rel.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(Rel.SectionID, Rel.Offset, RelType, Value.Addend);
// Extra check to avoid relocation againt empty symbols (usually
// the R_PPC64_TOC).
if (Value.SymbolName && !TargetName.empty())
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
}
} else {
RelocationEntry RE(Rel.SectionID, Rel.Offset, RelType, Value.Addend);
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
}
}
unsigned RuntimeDyldELF::getCommonSymbolAlignment(const SymbolRef &Sym) {
// In ELF, the value of an SHN_COMMON symbol is its alignment requirement.
uint64_t Align;
Check(Sym.getValue(Align));
return Align;
}
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;
}
} // namespace llvm
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