| //===-- RuntimeDyld.h - 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 "llvm/ADT/OwningPtr.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/ADT/StringMap.h" |
| #include "llvm/ADT/StringRef.h" |
| #include "llvm/ADT/Twine.h" |
| #include "llvm/ExecutionEngine/RuntimeDyld.h" |
| #include "llvm/ExecutionEngine/JITMemoryManager.h" |
| #include "llvm/Object/MachOObject.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/ErrorHandling.h" |
| #include "llvm/Support/Format.h" |
| #include "llvm/Support/Memory.h" |
| #include "llvm/Support/MemoryBuffer.h" |
| #include "llvm/Support/system_error.h" |
| #include "llvm/Support/raw_ostream.h" |
| using namespace llvm; |
| using namespace llvm::object; |
| |
| namespace llvm { |
| class RuntimeDyldImpl { |
| unsigned CPUType; |
| unsigned CPUSubtype; |
| |
| // The JITMemoryManager to load objects into. |
| JITMemoryManager *JMM; |
| |
| // Master symbol table. As modules are loaded and external symbols are |
| // resolved, their addresses are stored here. |
| StringMap<void*> SymbolTable; |
| |
| // FIXME: Should have multiple data blocks, one for each loaded chunk of |
| // compiled code. |
| sys::MemoryBlock Data; |
| |
| bool HasError; |
| std::string ErrorStr; |
| |
| // Set the error state and record an error string. |
| bool Error(const Twine &Msg) { |
| ErrorStr = Msg.str(); |
| HasError = true; |
| return true; |
| } |
| |
| bool resolveRelocation(uint32_t BaseSection, macho::RelocationEntry RE, |
| SmallVectorImpl<void *> &SectionBases, |
| SmallVectorImpl<StringRef> &SymbolNames); |
| bool resolveX86_64Relocation(intptr_t Address, intptr_t Value, bool isPCRel, |
| unsigned Type, unsigned Size); |
| bool resolveARMRelocation(intptr_t Address, intptr_t Value, bool isPCRel, |
| unsigned Type, unsigned Size); |
| |
| bool loadSegment32(const MachOObject *Obj, |
| const MachOObject::LoadCommandInfo *SegmentLCI, |
| const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC); |
| bool loadSegment64(const MachOObject *Obj, |
| const MachOObject::LoadCommandInfo *SegmentLCI, |
| const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC); |
| |
| public: |
| RuntimeDyldImpl(JITMemoryManager *jmm) : JMM(jmm), HasError(false) {} |
| |
| bool loadObject(MemoryBuffer *InputBuffer); |
| |
| void *getSymbolAddress(StringRef Name) { |
| // Use lookup() rather than [] because we don't want to add an entry |
| // if there isn't one already, which the [] operator does. |
| return SymbolTable.lookup(Name); |
| } |
| |
| sys::MemoryBlock getMemoryBlock() { return Data; } |
| |
| // Is the linker in an error state? |
| bool hasError() { return HasError; } |
| |
| // Mark the error condition as handled and continue. |
| void clearError() { HasError = false; } |
| |
| // Get the error message. |
| StringRef getErrorString() { return ErrorStr; } |
| }; |
| |
| // FIXME: Relocations for targets other than x86_64. |
| bool RuntimeDyldImpl:: |
| resolveRelocation(uint32_t BaseSection, macho::RelocationEntry RE, |
| SmallVectorImpl<void *> &SectionBases, |
| SmallVectorImpl<StringRef> &SymbolNames) { |
| // struct relocation_info { |
| // int32_t r_address; |
| // uint32_t r_symbolnum:24, |
| // r_pcrel:1, |
| // r_length:2, |
| // r_extern:1, |
| // r_type:4; |
| // }; |
| uint32_t SymbolNum = RE.Word1 & 0xffffff; // 24-bit value |
| bool isPCRel = (RE.Word1 >> 24) & 1; |
| unsigned Log2Size = (RE.Word1 >> 25) & 3; |
| bool isExtern = (RE.Word1 >> 27) & 1; |
| unsigned Type = (RE.Word1 >> 28) & 0xf; |
| if (RE.Word0 & macho::RF_Scattered) |
| return Error("NOT YET IMPLEMENTED: scattered relocations."); |
| |
| // The address requiring a relocation. |
| intptr_t Address = (intptr_t)SectionBases[BaseSection] + RE.Word0; |
| |
| // Figure out the target address of the relocation. If isExtern is true, |
| // this relocation references the symbol table, otherwise it references |
| // a section in the same object, numbered from 1 through NumSections |
| // (SectionBases is [0, NumSections-1]). |
| intptr_t Value; |
| if (isExtern) { |
| StringRef Name = SymbolNames[SymbolNum]; |
| if (SymbolTable.lookup(Name)) { |
| // The symbol is in our symbol table, so we can resolve it directly. |
| Value = (intptr_t)SymbolTable[Name]; |
| } else { |
| return Error("NOT YET IMPLEMENTED: relocations to pre-compiled code."); |
| } |
| DEBUG(dbgs() << "Resolve relocation(" << Type << ") from '" << Name |
| << "' to " << format("0x%x", Address) << ".\n"); |
| } else { |
| // For non-external relocations, the SymbolNum is actual a section number |
| // as described above. |
| Value = (intptr_t)SectionBases[SymbolNum - 1]; |
| } |
| |
| unsigned Size = 1 << Log2Size; |
| switch (CPUType) { |
| default: assert(0 && "Unsupported CPU type!"); |
| case mach::CTM_x86_64: |
| return resolveX86_64Relocation(Address, Value, isPCRel, Type, Size); |
| case mach::CTM_ARM: |
| return resolveARMRelocation(Address, Value, isPCRel, Type, Size); |
| } |
| llvm_unreachable(""); |
| } |
| |
| bool RuntimeDyldImpl::resolveX86_64Relocation(intptr_t Address, intptr_t Value, |
| bool isPCRel, unsigned Type, |
| unsigned Size) { |
| // 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 -= Address + 4; |
| |
| switch(Type) { |
| default: |
| llvm_unreachable("Invalid relocation type!"); |
| case macho::RIT_X86_64_Unsigned: |
| case macho::RIT_X86_64_Branch: { |
| // 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*)Address; |
| for (unsigned i = 0; i < Size; ++i) { |
| *p++ = (uint8_t)Value; |
| Value >>= 8; |
| } |
| return false; |
| } |
| case macho::RIT_X86_64_Signed: |
| case macho::RIT_X86_64_GOTLoad: |
| case macho::RIT_X86_64_GOT: |
| case macho::RIT_X86_64_Subtractor: |
| case macho::RIT_X86_64_Signed1: |
| case macho::RIT_X86_64_Signed2: |
| case macho::RIT_X86_64_Signed4: |
| case macho::RIT_X86_64_TLV: |
| return Error("Relocation type not implemented yet!"); |
| } |
| return false; |
| } |
| |
| bool RuntimeDyldImpl::resolveARMRelocation(intptr_t Address, intptr_t Value, |
| bool isPCRel, unsigned Type, |
| unsigned Size) { |
| // If the relocation is PC-relative, the value to be encoded is the |
| // pointer difference. |
| if (isPCRel) { |
| Value -= Address; |
| // 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: |
| case macho::RIT_Vanilla: { |
| llvm_unreachable("Invalid relocation type!"); |
| // 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*)Address; |
| for (unsigned i = 0; i < Size; ++i) { |
| *p++ = (uint8_t)Value; |
| Value >>= 8; |
| } |
| break; |
| } |
| case macho::RIT_Pair: |
| case macho::RIT_Difference: |
| case macho::RIT_ARM_LocalDifference: |
| case macho::RIT_ARM_PreboundLazyPointer: |
| 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*)Address; |
| // 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: |
| return Error("Relocation type not implemented yet!"); |
| } |
| return false; |
| } |
| |
| bool RuntimeDyldImpl:: |
| loadSegment32(const MachOObject *Obj, |
| const MachOObject::LoadCommandInfo *SegmentLCI, |
| const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) { |
| InMemoryStruct<macho::SegmentLoadCommand> Segment32LC; |
| Obj->ReadSegmentLoadCommand(*SegmentLCI, Segment32LC); |
| if (!Segment32LC) |
| return Error("unable to load segment load command"); |
| |
| // Map the segment into memory. |
| std::string ErrorStr; |
| Data = sys::Memory::AllocateRWX(Segment32LC->VMSize, 0, &ErrorStr); |
| if (!Data.base()) |
| return Error("unable to allocate memory block: '" + ErrorStr + "'"); |
| memcpy(Data.base(), Obj->getData(Segment32LC->FileOffset, |
| Segment32LC->FileSize).data(), |
| Segment32LC->FileSize); |
| memset((char*)Data.base() + Segment32LC->FileSize, 0, |
| Segment32LC->VMSize - Segment32LC->FileSize); |
| |
| // Bind the section indices to addresses and record the relocations we |
| // need to resolve. |
| typedef std::pair<uint32_t, macho::RelocationEntry> RelocationMap; |
| SmallVector<RelocationMap, 64> Relocations; |
| |
| SmallVector<void *, 16> SectionBases; |
| for (unsigned i = 0; i != Segment32LC->NumSections; ++i) { |
| InMemoryStruct<macho::Section> Sect; |
| Obj->ReadSection(*SegmentLCI, i, Sect); |
| if (!Sect) |
| return Error("unable to load section: '" + Twine(i) + "'"); |
| |
| // Remember any relocations the section has so we can resolve them later. |
| for (unsigned j = 0; j != Sect->NumRelocationTableEntries; ++j) { |
| InMemoryStruct<macho::RelocationEntry> RE; |
| Obj->ReadRelocationEntry(Sect->RelocationTableOffset, j, RE); |
| Relocations.push_back(RelocationMap(j, *RE)); |
| } |
| |
| // FIXME: Improve check. |
| // if (Sect->Flags != 0x80000400) |
| // return Error("unsupported section type!"); |
| |
| SectionBases.push_back((char*) Data.base() + Sect->Address); |
| } |
| |
| // Bind all the symbols to address. Keep a record of the names for use |
| // by relocation resolution. |
| SmallVector<StringRef, 64> SymbolNames; |
| for (unsigned i = 0; i != SymtabLC->NumSymbolTableEntries; ++i) { |
| InMemoryStruct<macho::SymbolTableEntry> STE; |
| Obj->ReadSymbolTableEntry(SymtabLC->SymbolTableOffset, i, STE); |
| if (!STE) |
| return Error("unable to read symbol: '" + Twine(i) + "'"); |
| // Get the symbol name. |
| StringRef Name = Obj->getStringAtIndex(STE->StringIndex); |
| SymbolNames.push_back(Name); |
| |
| // Just skip undefined symbols. They'll be loaded from whatever |
| // module they come from (or system dylib) when we resolve relocations |
| // involving them. |
| if (STE->SectionIndex == 0) |
| continue; |
| |
| unsigned Index = STE->SectionIndex - 1; |
| if (Index >= Segment32LC->NumSections) |
| return Error("invalid section index for symbol: '" + Twine() + "'"); |
| |
| // Get the section base address. |
| void *SectionBase = SectionBases[Index]; |
| |
| // Get the symbol address. |
| void *Address = (char*) SectionBase + STE->Value; |
| |
| // FIXME: Check the symbol type and flags. |
| if (STE->Type != 0xF) |
| return Error("unexpected symbol type!"); |
| if (STE->Flags != 0x0) |
| return Error("unexpected symbol type!"); |
| |
| DEBUG(dbgs() << "Symbol: '" << Name << "' @ " << Address << "\n"); |
| |
| SymbolTable[Name] = Address; |
| } |
| |
| // Now resolve any relocations. |
| for (unsigned i = 0, e = Relocations.size(); i != e; ++i) { |
| if (resolveRelocation(Relocations[i].first, Relocations[i].second, |
| SectionBases, SymbolNames)) |
| return true; |
| } |
| |
| // We've loaded the section; now mark the functions in it as executable. |
| // FIXME: We really should use the JITMemoryManager for this. |
| sys::Memory::setRangeExecutable(Data.base(), Data.size()); |
| |
| return false; |
| } |
| |
| |
| bool RuntimeDyldImpl:: |
| loadSegment64(const MachOObject *Obj, |
| const MachOObject::LoadCommandInfo *SegmentLCI, |
| const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) { |
| InMemoryStruct<macho::Segment64LoadCommand> Segment64LC; |
| Obj->ReadSegment64LoadCommand(*SegmentLCI, Segment64LC); |
| if (!Segment64LC) |
| return Error("unable to load segment load command"); |
| |
| // Map the segment into memory. |
| std::string ErrorStr; |
| Data = sys::Memory::AllocateRWX(Segment64LC->VMSize, 0, &ErrorStr); |
| if (!Data.base()) |
| return Error("unable to allocate memory block: '" + ErrorStr + "'"); |
| memcpy(Data.base(), Obj->getData(Segment64LC->FileOffset, |
| Segment64LC->FileSize).data(), |
| Segment64LC->FileSize); |
| memset((char*)Data.base() + Segment64LC->FileSize, 0, |
| Segment64LC->VMSize - Segment64LC->FileSize); |
| |
| // Bind the section indices to addresses and record the relocations we |
| // need to resolve. |
| typedef std::pair<uint32_t, macho::RelocationEntry> RelocationMap; |
| SmallVector<RelocationMap, 64> Relocations; |
| |
| SmallVector<void *, 16> SectionBases; |
| for (unsigned i = 0; i != Segment64LC->NumSections; ++i) { |
| InMemoryStruct<macho::Section64> Sect; |
| Obj->ReadSection64(*SegmentLCI, i, Sect); |
| if (!Sect) |
| return Error("unable to load section: '" + Twine(i) + "'"); |
| |
| // Remember any relocations the section has so we can resolve them later. |
| for (unsigned j = 0; j != Sect->NumRelocationTableEntries; ++j) { |
| InMemoryStruct<macho::RelocationEntry> RE; |
| Obj->ReadRelocationEntry(Sect->RelocationTableOffset, j, RE); |
| Relocations.push_back(RelocationMap(j, *RE)); |
| } |
| |
| // FIXME: Improve check. |
| if (Sect->Flags != 0x80000400) |
| return Error("unsupported section type!"); |
| |
| SectionBases.push_back((char*) Data.base() + Sect->Address); |
| } |
| |
| // Bind all the symbols to address. Keep a record of the names for use |
| // by relocation resolution. |
| SmallVector<StringRef, 64> SymbolNames; |
| for (unsigned i = 0; i != SymtabLC->NumSymbolTableEntries; ++i) { |
| InMemoryStruct<macho::Symbol64TableEntry> STE; |
| Obj->ReadSymbol64TableEntry(SymtabLC->SymbolTableOffset, i, STE); |
| if (!STE) |
| return Error("unable to read symbol: '" + Twine(i) + "'"); |
| // Get the symbol name. |
| StringRef Name = Obj->getStringAtIndex(STE->StringIndex); |
| SymbolNames.push_back(Name); |
| |
| // Just skip undefined symbols. They'll be loaded from whatever |
| // module they come from (or system dylib) when we resolve relocations |
| // involving them. |
| if (STE->SectionIndex == 0) |
| continue; |
| |
| unsigned Index = STE->SectionIndex - 1; |
| if (Index >= Segment64LC->NumSections) |
| return Error("invalid section index for symbol: '" + Twine() + "'"); |
| |
| // Get the section base address. |
| void *SectionBase = SectionBases[Index]; |
| |
| // Get the symbol address. |
| void *Address = (char*) SectionBase + STE->Value; |
| |
| // FIXME: Check the symbol type and flags. |
| if (STE->Type != 0xF) |
| return Error("unexpected symbol type!"); |
| if (STE->Flags != 0x0) |
| return Error("unexpected symbol type!"); |
| |
| DEBUG(dbgs() << "Symbol: '" << Name << "' @ " << Address << "\n"); |
| SymbolTable[Name] = Address; |
| } |
| |
| // Now resolve any relocations. |
| for (unsigned i = 0, e = Relocations.size(); i != e; ++i) { |
| if (resolveRelocation(Relocations[i].first, Relocations[i].second, |
| SectionBases, SymbolNames)) |
| return true; |
| } |
| |
| // We've loaded the section; now mark the functions in it as executable. |
| // FIXME: We really should use the JITMemoryManager for this. |
| sys::Memory::setRangeExecutable(Data.base(), Data.size()); |
| |
| return false; |
| } |
| |
| bool RuntimeDyldImpl::loadObject(MemoryBuffer *InputBuffer) { |
| // If the linker is in an error state, don't do anything. |
| if (hasError()) |
| return true; |
| // Load the Mach-O wrapper object. |
| std::string ErrorStr; |
| OwningPtr<MachOObject> Obj( |
| MachOObject::LoadFromBuffer(InputBuffer, &ErrorStr)); |
| if (!Obj) |
| return Error("unable to load object: '" + ErrorStr + "'"); |
| |
| // Get the CPU type information from the header. |
| const macho::Header &Header = Obj->getHeader(); |
| |
| // FIXME: Error checking that the loaded object is compatible with |
| // the system we're running on. |
| CPUType = Header.CPUType; |
| CPUSubtype = Header.CPUSubtype; |
| |
| // Validate that the load commands match what we expect. |
| const MachOObject::LoadCommandInfo *SegmentLCI = 0, *SymtabLCI = 0, |
| *DysymtabLCI = 0; |
| for (unsigned i = 0; i != Header.NumLoadCommands; ++i) { |
| const MachOObject::LoadCommandInfo &LCI = Obj->getLoadCommandInfo(i); |
| switch (LCI.Command.Type) { |
| case macho::LCT_Segment: |
| case macho::LCT_Segment64: |
| if (SegmentLCI) |
| return Error("unexpected input object (multiple segments)"); |
| SegmentLCI = &LCI; |
| break; |
| case macho::LCT_Symtab: |
| if (SymtabLCI) |
| return Error("unexpected input object (multiple symbol tables)"); |
| SymtabLCI = &LCI; |
| break; |
| case macho::LCT_Dysymtab: |
| if (DysymtabLCI) |
| return Error("unexpected input object (multiple symbol tables)"); |
| DysymtabLCI = &LCI; |
| break; |
| default: |
| return Error("unexpected input object (unexpected load command"); |
| } |
| } |
| |
| if (!SymtabLCI) |
| return Error("no symbol table found in object"); |
| if (!SegmentLCI) |
| return Error("no symbol table found in object"); |
| |
| // Read and register the symbol table data. |
| InMemoryStruct<macho::SymtabLoadCommand> SymtabLC; |
| Obj->ReadSymtabLoadCommand(*SymtabLCI, SymtabLC); |
| if (!SymtabLC) |
| return Error("unable to load symbol table load command"); |
| Obj->RegisterStringTable(*SymtabLC); |
| |
| // Read the dynamic link-edit information, if present (not present in static |
| // objects). |
| if (DysymtabLCI) { |
| InMemoryStruct<macho::DysymtabLoadCommand> DysymtabLC; |
| Obj->ReadDysymtabLoadCommand(*DysymtabLCI, DysymtabLC); |
| if (!DysymtabLC) |
| return Error("unable to load dynamic link-exit load command"); |
| |
| // FIXME: We don't support anything interesting yet. |
| // if (DysymtabLC->LocalSymbolsIndex != 0) |
| // return Error("NOT YET IMPLEMENTED: local symbol entries"); |
| // if (DysymtabLC->ExternalSymbolsIndex != 0) |
| // return Error("NOT YET IMPLEMENTED: non-external symbol entries"); |
| // if (DysymtabLC->UndefinedSymbolsIndex != SymtabLC->NumSymbolTableEntries) |
| // return Error("NOT YET IMPLEMENTED: undefined symbol entries"); |
| } |
| |
| // Load the segment load command. |
| if (SegmentLCI->Command.Type == macho::LCT_Segment) { |
| if (loadSegment32(Obj.get(), SegmentLCI, SymtabLC)) |
| return true; |
| } else { |
| if (loadSegment64(Obj.get(), SegmentLCI, SymtabLC)) |
| return true; |
| } |
| |
| return false; |
| } |
| |
| |
| //===----------------------------------------------------------------------===// |
| // RuntimeDyld class implementation |
| RuntimeDyld::RuntimeDyld(JITMemoryManager *JMM) { |
| Dyld = new RuntimeDyldImpl(JMM); |
| } |
| |
| RuntimeDyld::~RuntimeDyld() { |
| delete Dyld; |
| } |
| |
| bool RuntimeDyld::loadObject(MemoryBuffer *InputBuffer) { |
| return Dyld->loadObject(InputBuffer); |
| } |
| |
| void *RuntimeDyld::getSymbolAddress(StringRef Name) { |
| return Dyld->getSymbolAddress(Name); |
| } |
| |
| sys::MemoryBlock RuntimeDyld::getMemoryBlock() { |
| return Dyld->getMemoryBlock(); |
| } |
| |
| StringRef RuntimeDyld::getErrorString() { |
| return Dyld->getErrorString(); |
| } |
| |
| } // end namespace llvm |