| //===-- 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 { |
| |
| void RuntimeDyldMachO::resolveRelocation(const SectionEntry &Section, |
| uint64_t Offset, |
| uint64_t Value, |
| uint32_t Type, |
| int64_t Addend) { |
| uint8_t *LocalAddress = Section.Address + Offset; |
| uint64_t FinalAddress = Section.LoadAddress + Offset; |
| bool isPCRel = (Type >> 24) & 1; |
| unsigned MachoType = (Type >> 28) & 0xf; |
| unsigned Size = 1 << ((Type >> 25) & 3); |
| |
| 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::RIT_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::RIT_Difference: |
| case macho::RIT_Generic_LocalDifference: |
| case macho::RIT_Generic_PreboundLazyPointer: |
| 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::RIT_X86_64_Signed1: |
| case macho::RIT_X86_64_Signed2: |
| case macho::RIT_X86_64_Signed4: |
| case macho::RIT_X86_64_Signed: |
| case macho::RIT_X86_64_Unsigned: |
| case macho::RIT_X86_64_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::RIT_X86_64_GOTLoad: |
| case macho::RIT_X86_64_GOT: |
| case macho::RIT_X86_64_Subtractor: |
| case macho::RIT_X86_64_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::RIT_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::RIT_ARM_Branch24Bit: { |
| // 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::RIT_ARM_ThumbBranch22Bit: |
| case macho::RIT_ARM_ThumbBranch32Bit: |
| case macho::RIT_ARM_Half: |
| case macho::RIT_ARM_HalfDifference: |
| case macho::RIT_Pair: |
| case macho::RIT_Difference: |
| case macho::RIT_ARM_LocalDifference: |
| case macho::RIT_ARM_PreboundLazyPointer: |
| return Error("Relocation type not implemented yet!"); |
| } |
| return false; |
| } |
| |
| 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); |
| } |
| } |
| |
| |
| 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 |
