RelocationValueRef RuntimeDyldMachO::getRelocationValueRef(
ObjectImage &ObjImg, const relocation_iterator &RI,
const RelocationEntry &RE, ObjSectionToIDMap &ObjSectionToID,
const SymbolTableMap &Symbols) {
const MachOObjectFile &Obj =
static_cast<const MachOObjectFile &>(*ObjImg.getObjectFile());
MachO::any_relocation_info RelInfo =
Obj.getRelocation(RI->getRawDataRefImpl());
RelocationValueRef Value;
bool IsExternal = Obj.getPlainRelocationExternal(RelInfo);
if (IsExternal) {
symbol_iterator Symbol = RI->getSymbol();
StringRef TargetName;
Symbol->getName(TargetName);
SymbolTableMap::const_iterator SI = Symbols.find(TargetName.data());
if (SI != Symbols.end()) {
Value.SectionID = SI->second.first;
Value.Addend = SI->second.second + RE.Addend;
} else {
SI = GlobalSymbolTable.find(TargetName.data());
if (SI != GlobalSymbolTable.end()) {
Value.SectionID = SI->second.first;
Value.Addend = SI->second.second + RE.Addend;
} else {
Value.SymbolName = TargetName.data();
Value.Addend = RE.Addend;
}
}
} else {
SectionRef Sec = Obj.getRelocationSection(RelInfo);
bool IsCode = false;
Sec.isText(IsCode);
Value.SectionID = findOrEmitSection(ObjImg, Sec, IsCode, ObjSectionToID);
uint64_t Addr;
Sec.getAddress(Addr);
Value.Addend = RE.Addend - Addr;
}
return Value;
}
void RuntimeDyldMachO::processRelocationRef(unsigned SectionID,
RelocationRef RelI,
ObjectImage &Obj,
ObjSectionToIDMap &ObjSectionToID,
const SymbolTableMap &Symbols,
StubMap &Stubs) {
const ObjectFile *OF = Obj.getObjectFile();
const MachOObjectFile *MachO = static_cast<const MachOObjectFile*>(OF);
MachO::any_relocation_info RE= MachO->getRelocation(RelI.getRawDataRefImpl());
uint32_t RelType = MachO->getAnyRelocationType(RE);
// FIXME: Properly handle scattered relocations.
// For now, optimistically skip these: they can often be ignored, as
// the static linker will already have applied the relocation, and it
// only needs to be reapplied if symbols move relative to one another.
// Note: This will fail horribly where the relocations *do* need to be
// applied, but that was already the case.
if (MachO->isRelocationScattered(RE))
return;
RelocationValueRef Value;
SectionEntry &Section = Sections[SectionID];
bool isExtern = MachO->getPlainRelocationExternal(RE);
bool IsPCRel = MachO->getAnyRelocationPCRel(RE);
unsigned Size = MachO->getAnyRelocationLength(RE);
uint64_t Offset;
RelI.getOffset(Offset);
uint8_t *LocalAddress = Section.Address + Offset;
unsigned NumBytes = 1 << Size;
uint64_t Addend = 0;
memcpy(&Addend, LocalAddress, NumBytes);
if (isExtern) {
// Obtain the symbol name which is referenced in the relocation
symbol_iterator Symbol = RelI.getSymbol();
StringRef TargetName;
Symbol->getName(TargetName);
// First search for the symbol in the local symbol table
SymbolTableMap::const_iterator lsi = Symbols.find(TargetName.data());
if (lsi != Symbols.end()) {
Value.SectionID = lsi->second.first;
Value.Addend = lsi->second.second + Addend;
} 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 + Addend;
} else {
Value.SymbolName = TargetName.data();
Value.Addend = Addend;
}
}
} else {
SectionRef Sec = MachO->getRelocationSection(RE);
bool IsCode = false;
Sec.isText(IsCode);
Value.SectionID = findOrEmitSection(Obj, Sec, IsCode, ObjSectionToID);
uint64_t Addr;
Sec.getAddress(Addr);
Value.Addend = Addend - Addr;
if (IsPCRel)
Value.Addend += Offset + NumBytes;
}
if (Arch == Triple::x86_64 && (RelType == MachO::X86_64_RELOC_GOT ||
RelType == MachO::X86_64_RELOC_GOT_LOAD)) {
assert(IsPCRel);
assert(Size == 2);
StubMap::const_iterator i = Stubs.find(Value);
uint8_t *Addr;
if (i != Stubs.end()) {
Addr = Section.Address + i->second;
} else {
Stubs[Value] = Section.StubOffset;
uint8_t *GOTEntry = Section.Address + Section.StubOffset;
RelocationEntry RE(SectionID, Section.StubOffset,
MachO::X86_64_RELOC_UNSIGNED, 0, false, 3);
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
Section.StubOffset += 8;
Addr = GOTEntry;
}
resolveRelocation(Section, Offset, (uint64_t)Addr,
MachO::X86_64_RELOC_UNSIGNED, Value.Addend, true, 2);
} else if (Arch == Triple::arm &&
(RelType & 0xf) == MachO::ARM_RELOC_BR24) {
// This is an ARM branch relocation, need to use a stub function.
// Look up for existing stub.
StubMap::const_iterator i = Stubs.find(Value);
if (i != Stubs.end())
resolveRelocation(Section, Offset,
(uint64_t)Section.Address + i->second,
RelType, 0, IsPCRel, Size);
else {
// Create a new stub function.
Stubs[Value] = Section.StubOffset;
uint8_t *StubTargetAddr = createStubFunction(Section.Address +
Section.StubOffset);
RelocationEntry RE(SectionID, StubTargetAddr - Section.Address,
MachO::GENERIC_RELOC_VANILLA, 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, IsPCRel, Size);
Section.StubOffset += getMaxStubSize();
}
} else {
RelocationEntry RE(SectionID, Offset, RelType, Value.Addend,
IsPCRel, Size);
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
}
}
void RuntimeDyldMachO::processRelocationRef(const ObjRelocationInfo &Rel,
ObjectImage &Obj,
ObjSectionToIDMap &ObjSectionToID,
const SymbolTableMap &Symbols,
StubMap &Stubs) {
uint32_t RelType = (uint32_t) (Rel.Type & 0xffffffffL);
RelocationValueRef Value;
SectionEntry &Section = Sections[Rel.SectionID];
bool isExtern = (RelType >> 27) & 1;
if (isExtern) {
// Obtain the symbol name which is referenced in the relocation
StringRef TargetName;
const SymbolRef &Symbol = Rel.Symbol;
Symbol.getName(TargetName);
// First search for the symbol in the local symbol table
SymbolTableMap::const_iterator lsi = Symbols.find(TargetName.data());
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
Value.SymbolName = TargetName.data();
}
} else {
error_code err;
uint8_t sectionIndex = static_cast<uint8_t>(RelType & 0xFF);
section_iterator si = Obj.begin_sections(),
se = Obj.end_sections();
for (uint8_t i = 1; i < sectionIndex; i++) {
error_code err;
si.increment(err);
if (si == se)
break;
}
assert(si != se && "No section containing relocation!");
Value.SectionID = findOrEmitSection(Obj, *si, true, ObjSectionToID);
Value.Addend = 0;
// FIXME: The size and type of the relocation determines if we can
// encode an Addend in the target location itself, and if so, how many
// bytes we should read in order to get it. We don't yet support doing
// that, and just assuming it's sizeof(intptr_t) is blatantly wrong.
//Value.Addend = *(const intptr_t *)Target;
if (Value.Addend) {
// The MachO addend is an offset from the current section. We need it
// to be an offset from the destination section
Value.Addend += Section.ObjAddress - Sections[Value.SectionID].ObjAddress;
}
}
if (Arch == Triple::arm && (RelType & 0xf) == macho::RIT_ARM_Branch24Bit) {
// This is an ARM branch relocation, need to use a stub function.
// 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);
else {
// Create a new stub function.
Stubs[Value] = Section.StubOffset;
uint8_t *StubTargetAddr = createStubFunction(Section.Address +
Section.StubOffset);
RelocationEntry RE(Rel.SectionID, StubTargetAddr - Section.Address,
macho::RIT_Vanilla, 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 {
RelocationEntry RE(Rel.SectionID, Rel.Offset, RelType, Value.Addend);
if (Value.SymbolName)
addRelocationForSymbol(RE, Value.SymbolName);
else
addRelocationForSection(RE, Value.SectionID);
}
}