static std::error_code getRelocationValueString(const ELFObjectFileBase *Obj,
const RelocationRef &RelRef,
SmallVectorImpl<char> &Result) {
DataRefImpl Rel = RelRef.getRawDataRefImpl();
if (auto *ELF32LE = dyn_cast<ELF32LEObjectFile>(Obj))
return getRelocationValueString(ELF32LE, Rel, Result);
if (auto *ELF64LE = dyn_cast<ELF64LEObjectFile>(Obj))
return getRelocationValueString(ELF64LE, Rel, Result);
if (auto *ELF32BE = dyn_cast<ELF32BEObjectFile>(Obj))
return getRelocationValueString(ELF32BE, Rel, Result);
auto *ELF64BE = cast<ELF64BEObjectFile>(Obj);
return getRelocationValueString(ELF64BE, Rel, Result);
}
/// Given a relocation from __compact_unwind, consisting of the RelocationRef
/// and data being relocated, determine the best base Name and Addend to use for
/// display purposes.
///
/// 1. An Extern relocation will directly reference a symbol (and the data is
/// then already an addend), so use that.
/// 2. Otherwise the data is an offset in the object file's layout; try to find
// a symbol before it in the same section, and use the offset from there.
/// 3. Finally, if all that fails, fall back to an offset from the start of the
/// referenced section.
static void findUnwindRelocNameAddend(const MachOObjectFile *Obj,
std::map<uint64_t, SymbolRef> &Symbols,
const RelocationRef &Reloc,
uint64_t Addr,
StringRef &Name, uint64_t &Addend) {
if (Reloc.getSymbol() != Obj->symbol_end()) {
Reloc.getSymbol()->getName(Name);
Addend = Addr;
return;
}
auto RE = Obj->getRelocation(Reloc.getRawDataRefImpl());
SectionRef RelocSection = Obj->getRelocationSection(RE);
uint64_t SectionAddr;
RelocSection.getAddress(SectionAddr);
auto Sym = Symbols.upper_bound(Addr);
if (Sym == Symbols.begin()) {
// The first symbol in the object is after this reference, the best we can
// do is section-relative notation.
RelocSection.getName(Name);
Addend = Addr - SectionAddr;
return;
}
// Go back one so that SymbolAddress <= Addr.
--Sym;
section_iterator SymSection = Obj->section_end();
Sym->second.getSection(SymSection);
if (RelocSection == *SymSection) {
// There's a valid symbol in the same section before this reference.
Sym->second.getName(Name);
Addend = Addr - Sym->first;
return;
}
// There is a symbol before this reference, but it's in a different
// section. Probably not helpful to mention it, so use the section name.
RelocSection.getName(Name);
Addend = Addr - SectionAddr;
}
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);
}
}
static std::error_code getRelocationValueString(const MachOObjectFile *Obj,
const RelocationRef &RelRef,
SmallVectorImpl<char> &Result) {
DataRefImpl Rel = RelRef.getRawDataRefImpl();
MachO::any_relocation_info RE = Obj->getRelocation(Rel);
unsigned Arch = Obj->getArch();
std::string fmtbuf;
raw_string_ostream fmt(fmtbuf);
unsigned Type = Obj->getAnyRelocationType(RE);
bool IsPCRel = Obj->getAnyRelocationPCRel(RE);
// Determine any addends that should be displayed with the relocation.
// These require decoding the relocation type, which is triple-specific.
// X86_64 has entirely custom relocation types.
if (Arch == Triple::x86_64) {
bool isPCRel = Obj->getAnyRelocationPCRel(RE);
switch (Type) {
case MachO::X86_64_RELOC_GOT_LOAD:
case MachO::X86_64_RELOC_GOT: {
printRelocationTargetName(Obj, RE, fmt);
fmt << "@GOT";
if (isPCRel)
fmt << "PCREL";
break;
}
case MachO::X86_64_RELOC_SUBTRACTOR: {
DataRefImpl RelNext = Rel;
Obj->moveRelocationNext(RelNext);
MachO::any_relocation_info RENext = Obj->getRelocation(RelNext);
// X86_64_RELOC_SUBTRACTOR must be followed by a relocation of type
// X86_64_RELOC_UNSIGNED.
// NOTE: Scattered relocations don't exist on x86_64.
unsigned RType = Obj->getAnyRelocationType(RENext);
if (RType != MachO::X86_64_RELOC_UNSIGNED)
report_fatal_error("Expected X86_64_RELOC_UNSIGNED after "
"X86_64_RELOC_SUBTRACTOR.");
// The X86_64_RELOC_UNSIGNED contains the minuend symbol;
// X86_64_RELOC_SUBTRACTOR contains the subtrahend.
printRelocationTargetName(Obj, RENext, fmt);
fmt << "-";
printRelocationTargetName(Obj, RE, fmt);
break;
}
case MachO::X86_64_RELOC_TLV:
printRelocationTargetName(Obj, RE, fmt);
fmt << "@TLV";
if (isPCRel)
fmt << "P";
break;
case MachO::X86_64_RELOC_SIGNED_1:
printRelocationTargetName(Obj, RE, fmt);
fmt << "-1";
break;
case MachO::X86_64_RELOC_SIGNED_2:
printRelocationTargetName(Obj, RE, fmt);
fmt << "-2";
break;
case MachO::X86_64_RELOC_SIGNED_4:
printRelocationTargetName(Obj, RE, fmt);
fmt << "-4";
break;
default:
printRelocationTargetName(Obj, RE, fmt);
break;
}
// X86 and ARM share some relocation types in common.
} else if (Arch == Triple::x86 || Arch == Triple::arm ||
Arch == Triple::ppc) {
// Generic relocation types...
switch (Type) {
case MachO::GENERIC_RELOC_PAIR: // prints no info
return std::error_code();
case MachO::GENERIC_RELOC_SECTDIFF: {
DataRefImpl RelNext = Rel;
Obj->moveRelocationNext(RelNext);
MachO::any_relocation_info RENext = Obj->getRelocation(RelNext);
// X86 sect diff's must be followed by a relocation of type
// GENERIC_RELOC_PAIR.
unsigned RType = Obj->getAnyRelocationType(RENext);
if (RType != MachO::GENERIC_RELOC_PAIR)
report_fatal_error("Expected GENERIC_RELOC_PAIR after "
"GENERIC_RELOC_SECTDIFF.");
printRelocationTargetName(Obj, RE, fmt);
fmt << "-";
printRelocationTargetName(Obj, RENext, fmt);
break;
}
}
if (Arch == Triple::x86 || Arch == Triple::ppc) {
switch (Type) {
case MachO::GENERIC_RELOC_LOCAL_SECTDIFF: {
DataRefImpl RelNext = Rel;
Obj->moveRelocationNext(RelNext);
MachO::any_relocation_info RENext = Obj->getRelocation(RelNext);
// X86 sect diff's must be followed by a relocation of type
// GENERIC_RELOC_PAIR.
unsigned RType = Obj->getAnyRelocationType(RENext);
if (RType != MachO::GENERIC_RELOC_PAIR)
report_fatal_error("Expected GENERIC_RELOC_PAIR after "
"GENERIC_RELOC_LOCAL_SECTDIFF.");
printRelocationTargetName(Obj, RE, fmt);
fmt << "-";
printRelocationTargetName(Obj, RENext, fmt);
break;
}
case MachO::GENERIC_RELOC_TLV: {
printRelocationTargetName(Obj, RE, fmt);
fmt << "@TLV";
if (IsPCRel)
fmt << "P";
break;
}
default:
printRelocationTargetName(Obj, RE, fmt);
}
} else { // ARM-specific relocations
switch (Type) {
case MachO::ARM_RELOC_HALF:
case MachO::ARM_RELOC_HALF_SECTDIFF: {
// Half relocations steal a bit from the length field to encode
// whether this is an upper16 or a lower16 relocation.
bool isUpper = Obj->getAnyRelocationLength(RE) >> 1;
if (isUpper)
fmt << ":upper16:(";
else
fmt << ":lower16:(";
printRelocationTargetName(Obj, RE, fmt);
DataRefImpl RelNext = Rel;
Obj->moveRelocationNext(RelNext);
MachO::any_relocation_info RENext = Obj->getRelocation(RelNext);
// ARM half relocs must be followed by a relocation of type
// ARM_RELOC_PAIR.
unsigned RType = Obj->getAnyRelocationType(RENext);
if (RType != MachO::ARM_RELOC_PAIR)
report_fatal_error("Expected ARM_RELOC_PAIR after "
"ARM_RELOC_HALF");
// NOTE: The half of the target virtual address is stashed in the
// address field of the secondary relocation, but we can't reverse
// engineer the constant offset from it without decoding the movw/movt
// instruction to find the other half in its immediate field.
// ARM_RELOC_HALF_SECTDIFF encodes the second section in the
// symbol/section pointer of the follow-on relocation.
if (Type == MachO::ARM_RELOC_HALF_SECTDIFF) {
fmt << "-";
printRelocationTargetName(Obj, RENext, fmt);
}
fmt << ")";
break;
}
default: { printRelocationTargetName(Obj, RE, fmt); }
}
}
} else
static Error getRelocationValueString(const ELFObjectFile<ELFT> *Obj,
const RelocationRef &RelRef,
SmallVectorImpl<char> &Result) {
const ELFFile<ELFT> &EF = *Obj->getELFFile();
DataRefImpl Rel = RelRef.getRawDataRefImpl();
auto SecOrErr = EF.getSection(Rel.d.a);
if (!SecOrErr)
return SecOrErr.takeError();
int64_t Addend = 0;
// If there is no Symbol associated with the relocation, we set the undef
// boolean value to 'true'. This will prevent us from calling functions that
// requires the relocation to be associated with a symbol.
//
// In SHT_REL case we would need to read the addend from section data.
// GNU objdump does not do that and we just follow for simplicity atm.
bool Undef = false;
if ((*SecOrErr)->sh_type == ELF::SHT_RELA) {
const typename ELFT::Rela *ERela = Obj->getRela(Rel);
Addend = ERela->r_addend;
Undef = ERela->getSymbol(false) == 0;
} else if ((*SecOrErr)->sh_type != ELF::SHT_REL) {
return make_error<BinaryError>();
}
// Default scheme is to print Target, as well as "+ <addend>" for nonzero
// addend. Should be acceptable for all normal purposes.
std::string FmtBuf;
raw_string_ostream Fmt(FmtBuf);
if (!Undef) {
symbol_iterator SI = RelRef.getSymbol();
const typename ELFT::Sym *Sym = Obj->getSymbol(SI->getRawDataRefImpl());
if (Sym->getType() == ELF::STT_SECTION) {
Expected<section_iterator> SymSI = SI->getSection();
if (!SymSI)
return SymSI.takeError();
const typename ELFT::Shdr *SymSec =
Obj->getSection((*SymSI)->getRawDataRefImpl());
auto SecName = EF.getSectionName(SymSec);
if (!SecName)
return SecName.takeError();
Fmt << *SecName;
} else {
Expected<StringRef> SymName = SI->getName();
if (!SymName)
return SymName.takeError();
if (Demangle)
Fmt << demangle(*SymName);
else
Fmt << *SymName;
}
} else {
Fmt << "*ABS*";
}
if (Addend != 0)
Fmt << (Addend < 0 ? "" : "+") << Addend;
Fmt.flush();
Result.append(FmtBuf.begin(), FmtBuf.end());
return Error::success();
}