| //===-- RuntimeDyldMachO.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 the MC-JIT runtime dynamic linker. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #define DEBUG_TYPE "dyld" |
| #include "RuntimeDyldMachO.h" |
| #include "llvm/ADT/OwningPtr.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include "llvm/ADT/StringRef.h" |
| using namespace llvm; |
| using namespace llvm::object; |
| |
| namespace llvm { |
| |
| static unsigned char *processFDE(unsigned char *P, intptr_t DeltaForText, intptr_t DeltaForEH) { |
| uint32_t Length = *((uint32_t*)P); |
| P += 4; |
| unsigned char *Ret = P + Length; |
| uint32_t Offset = *((uint32_t*)P); |
| if (Offset == 0) // is a CIE |
| return Ret; |
| |
| P += 4; |
| intptr_t FDELocation = *((intptr_t*)P); |
| intptr_t NewLocation = FDELocation - DeltaForText; |
| *((intptr_t*)P) = NewLocation; |
| P += sizeof(intptr_t); |
| |
| // Skip the FDE address range |
| P += sizeof(intptr_t); |
| |
| uint8_t Augmentationsize = *P; |
| P += 1; |
| if (Augmentationsize != 0) { |
| intptr_t LSDA = *((intptr_t*)P); |
| intptr_t NewLSDA = LSDA - DeltaForEH; |
| *((intptr_t*)P) = NewLSDA; |
| } |
| |
| return Ret; |
| } |
| |
| static intptr_t computeDelta(SectionEntry *A, SectionEntry *B) { |
| intptr_t ObjDistance = A->ObjAddress - B->ObjAddress; |
| intptr_t MemDistance = A->LoadAddress - B->LoadAddress; |
| return ObjDistance - MemDistance; |
| } |
| |
| void RuntimeDyldMachO::registerEHFrames() { |
| |
| if (!MemMgr) |
| return; |
| for (int i = 0, e = UnregisteredEHFrameSections.size(); i != e; ++i) { |
| EHFrameRelatedSections &SectionInfo = UnregisteredEHFrameSections[i]; |
| if (SectionInfo.EHFrameSID == RTDYLD_INVALID_SECTION_ID || |
| SectionInfo.TextSID == RTDYLD_INVALID_SECTION_ID) |
| continue; |
| SectionEntry *Text = &Sections[SectionInfo.TextSID]; |
| SectionEntry *EHFrame = &Sections[SectionInfo.EHFrameSID]; |
| SectionEntry *ExceptTab = NULL; |
| if (SectionInfo.ExceptTabSID != RTDYLD_INVALID_SECTION_ID) |
| ExceptTab = &Sections[SectionInfo.ExceptTabSID]; |
| |
| intptr_t DeltaForText = computeDelta(Text, EHFrame); |
| intptr_t DeltaForEH = 0; |
| if (ExceptTab) |
| DeltaForEH = computeDelta(ExceptTab, EHFrame); |
| |
| unsigned char *P = EHFrame->Address; |
| unsigned char *End = P + EHFrame->Size; |
| do { |
| P = processFDE(P, DeltaForText, DeltaForEH); |
| } while(P != End); |
| |
| MemMgr->registerEHFrames(EHFrame->Address, |
| EHFrame->LoadAddress, |
| EHFrame->Size); |
| } |
| UnregisteredEHFrameSections.clear(); |
| } |
| |
| void RuntimeDyldMachO::finalizeLoad(ObjSectionToIDMap &SectionMap) { |
| unsigned EHFrameSID = RTDYLD_INVALID_SECTION_ID; |
| unsigned TextSID = RTDYLD_INVALID_SECTION_ID; |
| unsigned ExceptTabSID = RTDYLD_INVALID_SECTION_ID; |
| 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") |
| EHFrameSID = i->second; |
| else if (Name == "__text") |
| TextSID = i->second; |
| else if (Name == "__gcc_except_tab") |
| ExceptTabSID = i->second; |
| } |
| UnregisteredEHFrameSections.push_back(EHFrameRelatedSections(EHFrameSID, |
| TextSID, |
| ExceptTabSID)); |
| } |
| |
| // 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 RuntimeDyldMachO::resolveRelocation(const RelocationEntry &RE, |
| uint64_t Value) { |
| const SectionEntry &Section = Sections[RE.SectionID]; |
| return resolveRelocation(Section, RE.Offset, Value, RE.RelType, RE.Addend, |
| RE.IsPCRel, RE.Size); |
| } |
| |
| void RuntimeDyldMachO::resolveRelocation(const SectionEntry &Section, |
| uint64_t Offset, |
| uint64_t Value, |
| uint32_t Type, |
| int64_t Addend, |
| bool isPCRel, |
| unsigned LogSize) { |
| uint8_t *LocalAddress = Section.Address + Offset; |
| uint64_t FinalAddress = Section.LoadAddress + Offset; |
| unsigned MachoType = Type; |
| unsigned Size = 1 << LogSize; |
| |
| DEBUG(dbgs() << "resolveRelocation LocalAddress: " |
| << format("%p", LocalAddress) |
| << " FinalAddress: " << format("%p", FinalAddress) |
| << " Value: " << format("%p", Value) |
| << " Addend: " << Addend |
| << " isPCRel: " << isPCRel |
| << " MachoType: " << MachoType |
| << " Size: " << Size |
| << "\n"); |
| |
| // This just dispatches to the proper target specific routine. |
| switch (Arch) { |
| default: llvm_unreachable("Unsupported CPU type!"); |
| case Triple::x86_64: |
| resolveX86_64Relocation(LocalAddress, |
| FinalAddress, |
| (uintptr_t)Value, |
| isPCRel, |
| MachoType, |
| Size, |
| Addend); |
| break; |
| case Triple::x86: |
| resolveI386Relocation(LocalAddress, |
| FinalAddress, |
| (uintptr_t)Value, |
| isPCRel, |
| MachoType, |
| Size, |
| Addend); |
| break; |
| case Triple::arm: // Fall through. |
| case Triple::thumb: |
| resolveARMRelocation(LocalAddress, |
| FinalAddress, |
| (uintptr_t)Value, |
| isPCRel, |
| MachoType, |
| Size, |
| Addend); |
| break; |
| } |
| } |
| |
| bool RuntimeDyldMachO::resolveI386Relocation(uint8_t *LocalAddress, |
| uint64_t FinalAddress, |
| uint64_t Value, |
| bool isPCRel, |
| unsigned Type, |
| unsigned Size, |
| int64_t Addend) { |
| if (isPCRel) |
| Value -= FinalAddress + 4; // see resolveX86_64Relocation |
| |
| switch (Type) { |
| default: |
| llvm_unreachable("Invalid relocation type!"); |
| case MachO::GENERIC_RELOC_VANILLA: { |
| uint8_t *p = LocalAddress; |
| uint64_t ValueToWrite = Value + Addend; |
| for (unsigned i = 0; i < Size; ++i) { |
| *p++ = (uint8_t)(ValueToWrite & 0xff); |
| ValueToWrite >>= 8; |
| } |
| return false; |
| } |
| case MachO::GENERIC_RELOC_SECTDIFF: |
| case MachO::GENERIC_RELOC_LOCAL_SECTDIFF: |
| case MachO::GENERIC_RELOC_PB_LA_PTR: |
| return Error("Relocation type not implemented yet!"); |
| } |
| } |
| |
| bool RuntimeDyldMachO::resolveX86_64Relocation(uint8_t *LocalAddress, |
| uint64_t FinalAddress, |
| uint64_t Value, |
| bool isPCRel, |
| unsigned Type, |
| unsigned Size, |
| int64_t Addend) { |
| // If the relocation is PC-relative, the value to be encoded is the |
| // pointer difference. |
| if (isPCRel) |
| // FIXME: It seems this value needs to be adjusted by 4 for an effective PC |
| // address. Is that expected? Only for branches, perhaps? |
| Value -= FinalAddress + 4; |
| |
| switch(Type) { |
| default: |
| llvm_unreachable("Invalid relocation type!"); |
| case MachO::X86_64_RELOC_SIGNED_1: |
| case MachO::X86_64_RELOC_SIGNED_2: |
| case MachO::X86_64_RELOC_SIGNED_4: |
| case MachO::X86_64_RELOC_SIGNED: |
| case MachO::X86_64_RELOC_UNSIGNED: |
| case MachO::X86_64_RELOC_BRANCH: { |
| Value += Addend; |
| // Mask in the target value a byte at a time (we don't have an alignment |
| // guarantee for the target address, so this is safest). |
| uint8_t *p = (uint8_t*)LocalAddress; |
| for (unsigned i = 0; i < Size; ++i) { |
| *p++ = (uint8_t)Value; |
| Value >>= 8; |
| } |
| return false; |
| } |
| case MachO::X86_64_RELOC_GOT_LOAD: |
| case MachO::X86_64_RELOC_GOT: |
| case MachO::X86_64_RELOC_SUBTRACTOR: |
| case MachO::X86_64_RELOC_TLV: |
| return Error("Relocation type not implemented yet!"); |
| } |
| } |
| |
| bool RuntimeDyldMachO::resolveARMRelocation(uint8_t *LocalAddress, |
| uint64_t FinalAddress, |
| uint64_t Value, |
| bool isPCRel, |
| unsigned Type, |
| unsigned Size, |
| int64_t Addend) { |
| // If the relocation is PC-relative, the value to be encoded is the |
| // pointer difference. |
| if (isPCRel) { |
| Value -= FinalAddress; |
| // ARM PCRel relocations have an effective-PC offset of two instructions |
| // (four bytes in Thumb mode, 8 bytes in ARM mode). |
| // FIXME: For now, assume ARM mode. |
| Value -= 8; |
| } |
| |
| switch(Type) { |
| default: |
| llvm_unreachable("Invalid relocation type!"); |
| case MachO::ARM_RELOC_VANILLA: { |
| // Mask in the target value a byte at a time (we don't have an alignment |
| // guarantee for the target address, so this is safest). |
| uint8_t *p = (uint8_t*)LocalAddress; |
| for (unsigned i = 0; i < Size; ++i) { |
| *p++ = (uint8_t)Value; |
| Value >>= 8; |
| } |
| break; |
| } |
| case MachO::ARM_RELOC_BR24: { |
| // Mask the value into the target address. We know instructions are |
| // 32-bit aligned, so we can do it all at once. |
| uint32_t *p = (uint32_t*)LocalAddress; |
| // The low two bits of the value are not encoded. |
| Value >>= 2; |
| // Mask the value to 24 bits. |
| Value &= 0xffffff; |
| // FIXME: If the destination is a Thumb function (and the instruction |
| // is a non-predicated BL instruction), we need to change it to a BLX |
| // instruction instead. |
| |
| // Insert the value into the instruction. |
| *p = (*p & ~0xffffff) | Value; |
| break; |
| } |
| case MachO::ARM_THUMB_RELOC_BR22: |
| case MachO::ARM_THUMB_32BIT_BRANCH: |
| case MachO::ARM_RELOC_HALF: |
| case MachO::ARM_RELOC_HALF_SECTDIFF: |
| case MachO::ARM_RELOC_PAIR: |
| case MachO::ARM_RELOC_SECTDIFF: |
| case MachO::ARM_RELOC_LOCAL_SECTDIFF: |
| case MachO::ARM_RELOC_PB_LA_PTR: |
| return Error("Relocation type not implemented yet!"); |
| } |
| return false; |
| } |
| |
| 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); |
| Value.SectionID = findOrEmitSection(Obj, Sec, true, ObjSectionToID); |
| uint64_t Addr; |
| Sec.getAddress(Addr); |
| Value.Addend = Addend - Addr; |
| } |
| |
| 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); |
| } |
| } |
| |
| |
| bool RuntimeDyldMachO::isCompatibleFormat( |
| const ObjectBuffer *InputBuffer) const { |
| if (InputBuffer->getBufferSize() < 4) |
| return false; |
| StringRef Magic(InputBuffer->getBufferStart(), 4); |
| if (Magic == "\xFE\xED\xFA\xCE") return true; |
| if (Magic == "\xCE\xFA\xED\xFE") return true; |
| if (Magic == "\xFE\xED\xFA\xCF") return true; |
| if (Magic == "\xCF\xFA\xED\xFE") return true; |
| return false; |
| } |
| |
| } // end namespace llvm |
