| //===-- 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 "llvm/ADT/OwningPtr.h" |
| #include "llvm/ADT/StringRef.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include "RuntimeDyldImpl.h" |
| using namespace llvm; |
| using namespace llvm::object; |
| |
| namespace llvm { |
| |
| bool RuntimeDyldMachO:: |
| resolveRelocation(uint8_t *Address, uint8_t *Value, bool isPCRel, |
| unsigned Type, unsigned Size) { |
| // This just dispatches to the proper target specific routine. |
| switch (CPUType) { |
| default: assert(0 && "Unsupported CPU type!"); |
| case mach::CTM_x86_64: |
| return resolveX86_64Relocation((uintptr_t)Address, (uintptr_t)Value, |
| isPCRel, Type, Size); |
| case mach::CTM_ARM: |
| return resolveARMRelocation((uintptr_t)Address, (uintptr_t)Value, |
| isPCRel, Type, Size); |
| } |
| llvm_unreachable(""); |
| } |
| |
| bool RuntimeDyldMachO:: |
| resolveX86_64Relocation(uintptr_t Address, uintptr_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 RuntimeDyldMachO::resolveARMRelocation(uintptr_t Address, uintptr_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: |
| llvm_unreachable("Invalid relocation type!"); |
| 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_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: |
| 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; |
| } |
| |
| bool RuntimeDyldMachO:: |
| loadSegment32(const MachOObject *Obj, |
| const MachOObject::LoadCommandInfo *SegmentLCI, |
| const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) { |
| InMemoryStruct<macho::SegmentLoadCommand> SegmentLC; |
| Obj->ReadSegmentLoadCommand(*SegmentLCI, SegmentLC); |
| if (!SegmentLC) |
| return Error("unable to load segment load command"); |
| |
| for (unsigned SectNum = 0; SectNum != SegmentLC->NumSections; ++SectNum) { |
| InMemoryStruct<macho::Section> Sect; |
| Obj->ReadSection(*SegmentLCI, SectNum, Sect); |
| if (!Sect) |
| return Error("unable to load section: '" + Twine(SectNum) + "'"); |
| |
| // FIXME: For the time being, we're only loading text segments. |
| if (Sect->Flags != 0x80000400) |
| continue; |
| |
| // Address and names of symbols in the section. |
| typedef std::pair<uint64_t, StringRef> SymbolEntry; |
| SmallVector<SymbolEntry, 64> Symbols; |
| // Index of all the names, in this section or not. Used when we're |
| // dealing with relocation entries. |
| 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) + "'"); |
| if (STE->SectionIndex > SegmentLC->NumSections) |
| return Error("invalid section index for symbol: '" + Twine(i) + "'"); |
| // Get the symbol name. |
| StringRef Name = Obj->getStringAtIndex(STE->StringIndex); |
| SymbolNames.push_back(Name); |
| |
| // Just skip symbols not defined in this section. |
| if ((unsigned)STE->SectionIndex - 1 != SectNum) |
| continue; |
| |
| // FIXME: Check the symbol type and flags. |
| if (STE->Type != 0xF) // external, defined in this section. |
| continue; |
| // Flags == 0x8 marks a thumb function for ARM, which is fine as it |
| // doesn't require any special handling here. |
| if (STE->Flags != 0x0 && STE->Flags != 0x8) |
| continue; |
| |
| // Remember the symbol. |
| Symbols.push_back(SymbolEntry(STE->Value, Name)); |
| |
| DEBUG(dbgs() << "Function sym: '" << Name << "' @ " << |
| (Sect->Address + STE->Value) << "\n"); |
| } |
| // Sort the symbols by address, just in case they didn't come in that way. |
| array_pod_sort(Symbols.begin(), Symbols.end()); |
| |
| // If there weren't any functions (odd, but just in case...) |
| if (!Symbols.size()) |
| continue; |
| |
| // Extract the function data. |
| uint8_t *Base = (uint8_t*)Obj->getData(SegmentLC->FileOffset, |
| SegmentLC->FileSize).data(); |
| for (unsigned i = 0, e = Symbols.size() - 1; i != e; ++i) { |
| uint64_t StartOffset = Sect->Address + Symbols[i].first; |
| uint64_t EndOffset = Symbols[i + 1].first - 1; |
| DEBUG(dbgs() << "Extracting function: " << Symbols[i].second |
| << " from [" << StartOffset << ", " << EndOffset << "]\n"); |
| extractFunction(Symbols[i].second, Base + StartOffset, Base + EndOffset); |
| } |
| // The last symbol we do after since the end address is calculated |
| // differently because there is no next symbol to reference. |
| uint64_t StartOffset = Symbols[Symbols.size() - 1].first; |
| uint64_t EndOffset = Sect->Size - 1; |
| DEBUG(dbgs() << "Extracting function: " << Symbols[Symbols.size()-1].second |
| << " from [" << StartOffset << ", " << EndOffset << "]\n"); |
| extractFunction(Symbols[Symbols.size()-1].second, |
| Base + StartOffset, Base + EndOffset); |
| |
| // Now extract the relocation information for each function and process it. |
| for (unsigned j = 0; j != Sect->NumRelocationTableEntries; ++j) { |
| InMemoryStruct<macho::RelocationEntry> RE; |
| Obj->ReadRelocationEntry(Sect->RelocationTableOffset, j, RE); |
| if (RE->Word0 & macho::RF_Scattered) |
| return Error("NOT YET IMPLEMENTED: scattered relocations."); |
| // Word0 of the relocation is the offset into the section where the |
| // relocation should be applied. We need to translate that into an |
| // offset into a function since that's our atom. |
| uint32_t Offset = RE->Word0; |
| // Look for the function containing the address. This is used for JIT |
| // code, so the number of functions in section is almost always going |
| // to be very small (usually just one), so until we have use cases |
| // where that's not true, just use a trivial linear search. |
| unsigned SymbolNum; |
| unsigned NumSymbols = Symbols.size(); |
| assert(NumSymbols > 0 && Symbols[0].first <= Offset && |
| "No symbol containing relocation!"); |
| for (SymbolNum = 0; SymbolNum < NumSymbols - 1; ++SymbolNum) |
| if (Symbols[SymbolNum + 1].first > Offset) |
| break; |
| // Adjust the offset to be relative to the symbol. |
| Offset -= Symbols[SymbolNum].first; |
| // Get the name of the symbol containing the relocation. |
| StringRef TargetName = SymbolNames[SymbolNum]; |
| |
| bool isExtern = (RE->Word1 >> 27) & 1; |
| // Figure out the source symbol 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]). |
| // FIXME: Some targets (ARM) use internal relocations even for |
| // externally visible symbols, if the definition is in the same |
| // file as the reference. We need to convert those back to by-name |
| // references. We can resolve the address based on the section |
| // offset and see if we have a symbol at that address. If we do, |
| // use that; otherwise, puke. |
| if (!isExtern) |
| return Error("Internal relocations not supported."); |
| uint32_t SourceNum = RE->Word1 & 0xffffff; // 24-bit value |
| StringRef SourceName = SymbolNames[SourceNum]; |
| |
| // FIXME: Get the relocation addend from the target address. |
| |
| // Now store the relocation information. Associate it with the source |
| // symbol. |
| Relocations[SourceName].push_back(RelocationEntry(TargetName, |
| Offset, |
| RE->Word1, |
| 0 /*Addend*/)); |
| DEBUG(dbgs() << "Relocation at '" << TargetName << "' + " << Offset |
| << " from '" << SourceName << "(Word1: " |
| << format("0x%x", RE->Word1) << ")\n"); |
| } |
| } |
| return false; |
| } |
| |
| |
| bool RuntimeDyldMachO:: |
| 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"); |
| |
| for (unsigned SectNum = 0; SectNum != Segment64LC->NumSections; ++SectNum) { |
| InMemoryStruct<macho::Section64> Sect; |
| Obj->ReadSection64(*SegmentLCI, SectNum, Sect); |
| if (!Sect) |
| return Error("unable to load section: '" + Twine(SectNum) + "'"); |
| |
| // FIXME: For the time being, we're only loading text segments. |
| if (Sect->Flags != 0x80000400) |
| continue; |
| |
| // Address and names of symbols in the section. |
| typedef std::pair<uint64_t, StringRef> SymbolEntry; |
| SmallVector<SymbolEntry, 64> Symbols; |
| // Index of all the names, in this section or not. Used when we're |
| // dealing with relocation entries. |
| 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) + "'"); |
| if (STE->SectionIndex > Segment64LC->NumSections) |
| return Error("invalid section index for symbol: '" + Twine(i) + "'"); |
| // Get the symbol name. |
| StringRef Name = Obj->getStringAtIndex(STE->StringIndex); |
| SymbolNames.push_back(Name); |
| |
| // Just skip symbols not defined in this section. |
| if ((unsigned)STE->SectionIndex - 1 != SectNum) |
| continue; |
| |
| // FIXME: Check the symbol type and flags. |
| if (STE->Type != 0xF) // external, defined in this section. |
| continue; |
| if (STE->Flags != 0x0) |
| continue; |
| |
| // Remember the symbol. |
| Symbols.push_back(SymbolEntry(STE->Value, Name)); |
| |
| DEBUG(dbgs() << "Function sym: '" << Name << "' @ " << |
| (Sect->Address + STE->Value) << "\n"); |
| } |
| // Sort the symbols by address, just in case they didn't come in that way. |
| array_pod_sort(Symbols.begin(), Symbols.end()); |
| |
| // If there weren't any functions (odd, but just in case...) |
| if (!Symbols.size()) |
| continue; |
| |
| // Extract the function data. |
| uint8_t *Base = (uint8_t*)Obj->getData(Segment64LC->FileOffset, |
| Segment64LC->FileSize).data(); |
| for (unsigned i = 0, e = Symbols.size() - 1; i != e; ++i) { |
| uint64_t StartOffset = Sect->Address + Symbols[i].first; |
| uint64_t EndOffset = Symbols[i + 1].first - 1; |
| DEBUG(dbgs() << "Extracting function: " << Symbols[i].second |
| << " from [" << StartOffset << ", " << EndOffset << "]\n"); |
| extractFunction(Symbols[i].second, Base + StartOffset, Base + EndOffset); |
| } |
| // The last symbol we do after since the end address is calculated |
| // differently because there is no next symbol to reference. |
| uint64_t StartOffset = Symbols[Symbols.size() - 1].first; |
| uint64_t EndOffset = Sect->Size - 1; |
| DEBUG(dbgs() << "Extracting function: " << Symbols[Symbols.size()-1].second |
| << " from [" << StartOffset << ", " << EndOffset << "]\n"); |
| extractFunction(Symbols[Symbols.size()-1].second, |
| Base + StartOffset, Base + EndOffset); |
| |
| // Now extract the relocation information for each function and process it. |
| for (unsigned j = 0; j != Sect->NumRelocationTableEntries; ++j) { |
| InMemoryStruct<macho::RelocationEntry> RE; |
| Obj->ReadRelocationEntry(Sect->RelocationTableOffset, j, RE); |
| if (RE->Word0 & macho::RF_Scattered) |
| return Error("NOT YET IMPLEMENTED: scattered relocations."); |
| // Word0 of the relocation is the offset into the section where the |
| // relocation should be applied. We need to translate that into an |
| // offset into a function since that's our atom. |
| uint32_t Offset = RE->Word0; |
| // Look for the function containing the address. This is used for JIT |
| // code, so the number of functions in section is almost always going |
| // to be very small (usually just one), so until we have use cases |
| // where that's not true, just use a trivial linear search. |
| unsigned SymbolNum; |
| unsigned NumSymbols = Symbols.size(); |
| assert(NumSymbols > 0 && Symbols[0].first <= Offset && |
| "No symbol containing relocation!"); |
| for (SymbolNum = 0; SymbolNum < NumSymbols - 1; ++SymbolNum) |
| if (Symbols[SymbolNum + 1].first > Offset) |
| break; |
| // Adjust the offset to be relative to the symbol. |
| Offset -= Symbols[SymbolNum].first; |
| // Get the name of the symbol containing the relocation. |
| StringRef TargetName = SymbolNames[SymbolNum]; |
| |
| bool isExtern = (RE->Word1 >> 27) & 1; |
| // Figure out the source symbol 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]). |
| if (!isExtern) |
| return Error("Internal relocations not supported."); |
| uint32_t SourceNum = RE->Word1 & 0xffffff; // 24-bit value |
| StringRef SourceName = SymbolNames[SourceNum]; |
| |
| // FIXME: Get the relocation addend from the target address. |
| |
| // Now store the relocation information. Associate it with the source |
| // symbol. |
| Relocations[SourceName].push_back(RelocationEntry(TargetName, |
| Offset, |
| RE->Word1, |
| 0 /*Addend*/)); |
| DEBUG(dbgs() << "Relocation at '" << TargetName << "' + " << Offset |
| << " from '" << SourceName << "(Word1: " |
| << format("0x%x", RE->Word1) << ")\n"); |
| } |
| } |
| return false; |
| } |
| |
| bool RuntimeDyldMachO::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; |
| } |
| |
| // Assign an address to a symbol name and resolve all the relocations |
| // associated with it. |
| void RuntimeDyldMachO::reassignSymbolAddress(StringRef Name, uint8_t *Addr) { |
| // Assign the address in our symbol table. |
| SymbolTable[Name] = Addr; |
| |
| RelocationList &Relocs = Relocations[Name]; |
| for (unsigned i = 0, e = Relocs.size(); i != e; ++i) { |
| RelocationEntry &RE = Relocs[i]; |
| uint8_t *Target = SymbolTable[RE.Target] + RE.Offset; |
| bool isPCRel = (RE.Data >> 24) & 1; |
| unsigned Type = (RE.Data >> 28) & 0xf; |
| unsigned Size = 1 << ((RE.Data >> 25) & 3); |
| |
| DEBUG(dbgs() << "Resolving relocation at '" << RE.Target |
| << "' + " << RE.Offset << " (" << format("%p", Target) << ")" |
| << " from '" << Name << " (" << format("%p", Addr) << ")" |
| << "(" << (isPCRel ? "pcrel" : "absolute") |
| << ", type: " << Type << ", Size: " << Size << ").\n"); |
| |
| resolveRelocation(Target, Addr, isPCRel, Type, Size); |
| RE.isResolved = true; |
| } |
| } |
| |
| bool RuntimeDyldMachO::isKnownFormat(const MemoryBuffer *InputBuffer) { |
| StringRef Magic = InputBuffer->getBuffer().slice(0, 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 |
