| //=--------- MachOLinkGraphBuilder.cpp - MachO LinkGraph builder ----------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // Generic MachO LinkGraph buliding code. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "MachOLinkGraphBuilder.h" |
| |
| #define DEBUG_TYPE "jitlink" |
| |
| static const char *CommonSectionName = "__common"; |
| |
| namespace llvm { |
| namespace jitlink { |
| |
| MachOLinkGraphBuilder::~MachOLinkGraphBuilder() {} |
| |
| Expected<std::unique_ptr<LinkGraph>> MachOLinkGraphBuilder::buildGraph() { |
| |
| // We only operate on relocatable objects. |
| if (!Obj.isRelocatableObject()) |
| return make_error<JITLinkError>("Object is not a relocatable MachO"); |
| |
| if (auto Err = createNormalizedSections()) |
| return std::move(Err); |
| |
| if (auto Err = createNormalizedSymbols()) |
| return std::move(Err); |
| |
| if (auto Err = graphifyRegularSymbols()) |
| return std::move(Err); |
| |
| if (auto Err = graphifySectionsWithCustomParsers()) |
| return std::move(Err); |
| |
| if (auto Err = addRelocations()) |
| return std::move(Err); |
| |
| return std::move(G); |
| } |
| |
| MachOLinkGraphBuilder::MachOLinkGraphBuilder( |
| const object::MachOObjectFile &Obj, Triple TT, |
| LinkGraph::GetEdgeKindNameFunction GetEdgeKindName) |
| : Obj(Obj), |
| G(std::make_unique<LinkGraph>( |
| std::string(Obj.getFileName()), std::move(TT), getPointerSize(Obj), |
| getEndianness(Obj), std::move(GetEdgeKindName))) {} |
| |
| void MachOLinkGraphBuilder::addCustomSectionParser( |
| StringRef SectionName, SectionParserFunction Parser) { |
| assert(!CustomSectionParserFunctions.count(SectionName) && |
| "Custom parser for this section already exists"); |
| CustomSectionParserFunctions[SectionName] = std::move(Parser); |
| } |
| |
| Linkage MachOLinkGraphBuilder::getLinkage(uint16_t Desc) { |
| if ((Desc & MachO::N_WEAK_DEF) || (Desc & MachO::N_WEAK_REF)) |
| return Linkage::Weak; |
| return Linkage::Strong; |
| } |
| |
| Scope MachOLinkGraphBuilder::getScope(StringRef Name, uint8_t Type) { |
| if (Type & MachO::N_EXT) { |
| if ((Type & MachO::N_PEXT) || Name.startswith("l")) |
| return Scope::Hidden; |
| else |
| return Scope::Default; |
| } |
| return Scope::Local; |
| } |
| |
| bool MachOLinkGraphBuilder::isAltEntry(const NormalizedSymbol &NSym) { |
| return NSym.Desc & MachO::N_ALT_ENTRY; |
| } |
| |
| bool MachOLinkGraphBuilder::isDebugSection(const NormalizedSection &NSec) { |
| return (NSec.Flags & MachO::S_ATTR_DEBUG && |
| strcmp(NSec.SegName, "__DWARF") == 0); |
| } |
| |
| bool MachOLinkGraphBuilder::isZeroFillSection(const NormalizedSection &NSec) { |
| switch (NSec.Flags & MachO::SECTION_TYPE) { |
| case MachO::S_ZEROFILL: |
| case MachO::S_GB_ZEROFILL: |
| case MachO::S_THREAD_LOCAL_ZEROFILL: |
| return true; |
| default: |
| return false; |
| } |
| } |
| |
| unsigned |
| MachOLinkGraphBuilder::getPointerSize(const object::MachOObjectFile &Obj) { |
| return Obj.is64Bit() ? 8 : 4; |
| } |
| |
| support::endianness |
| MachOLinkGraphBuilder::getEndianness(const object::MachOObjectFile &Obj) { |
| return Obj.isLittleEndian() ? support::little : support::big; |
| } |
| |
| Section &MachOLinkGraphBuilder::getCommonSection() { |
| if (!CommonSection) |
| CommonSection = |
| &G->createSection(CommonSectionName, MemProt::Read | MemProt::Write); |
| return *CommonSection; |
| } |
| |
| Error MachOLinkGraphBuilder::createNormalizedSections() { |
| // Build normalized sections. Verifies that section data is in-range (for |
| // sections with content) and that address ranges are non-overlapping. |
| |
| LLVM_DEBUG(dbgs() << "Creating normalized sections...\n"); |
| |
| for (auto &SecRef : Obj.sections()) { |
| NormalizedSection NSec; |
| uint32_t DataOffset = 0; |
| |
| auto SecIndex = Obj.getSectionIndex(SecRef.getRawDataRefImpl()); |
| |
| if (Obj.is64Bit()) { |
| const MachO::section_64 &Sec64 = |
| Obj.getSection64(SecRef.getRawDataRefImpl()); |
| |
| memcpy(&NSec.SectName, &Sec64.sectname, 16); |
| NSec.SectName[16] = '\0'; |
| memcpy(&NSec.SegName, Sec64.segname, 16); |
| NSec.SegName[16] = '\0'; |
| |
| NSec.Address = Sec64.addr; |
| NSec.Size = Sec64.size; |
| NSec.Alignment = 1ULL << Sec64.align; |
| NSec.Flags = Sec64.flags; |
| DataOffset = Sec64.offset; |
| } else { |
| const MachO::section &Sec32 = Obj.getSection(SecRef.getRawDataRefImpl()); |
| |
| memcpy(&NSec.SectName, &Sec32.sectname, 16); |
| NSec.SectName[16] = '\0'; |
| memcpy(&NSec.SegName, Sec32.segname, 16); |
| NSec.SegName[16] = '\0'; |
| |
| NSec.Address = Sec32.addr; |
| NSec.Size = Sec32.size; |
| NSec.Alignment = 1ULL << Sec32.align; |
| NSec.Flags = Sec32.flags; |
| DataOffset = Sec32.offset; |
| } |
| |
| LLVM_DEBUG({ |
| dbgs() << " " << NSec.SegName << "," << NSec.SectName << ": " |
| << formatv("{0:x16}", NSec.Address) << " -- " |
| << formatv("{0:x16}", NSec.Address + NSec.Size) |
| << ", align: " << NSec.Alignment << ", index: " << SecIndex |
| << "\n"; |
| }); |
| |
| // Get the section data if any. |
| if (!isZeroFillSection(NSec)) { |
| if (DataOffset + NSec.Size > Obj.getData().size()) |
| return make_error<JITLinkError>( |
| "Section data extends past end of file"); |
| |
| NSec.Data = Obj.getData().data() + DataOffset; |
| } |
| |
| // Get prot flags. |
| // FIXME: Make sure this test is correct (it's probably missing cases |
| // as-is). |
| MemProt Prot; |
| if (NSec.Flags & MachO::S_ATTR_PURE_INSTRUCTIONS) |
| Prot = MemProt::Read | MemProt::Exec; |
| else |
| Prot = MemProt::Read | MemProt::Write; |
| |
| auto FullyQualifiedName = |
| G->allocateString(StringRef(NSec.SegName) + "," + NSec.SectName); |
| NSec.GraphSection = &G->createSection( |
| StringRef(FullyQualifiedName.data(), FullyQualifiedName.size()), Prot); |
| |
| IndexToSection.insert(std::make_pair(SecIndex, std::move(NSec))); |
| } |
| |
| std::vector<NormalizedSection *> Sections; |
| Sections.reserve(IndexToSection.size()); |
| for (auto &KV : IndexToSection) |
| Sections.push_back(&KV.second); |
| |
| // If we didn't end up creating any sections then bail out. The code below |
| // assumes that we have at least one section. |
| if (Sections.empty()) |
| return Error::success(); |
| |
| llvm::sort(Sections, |
| [](const NormalizedSection *LHS, const NormalizedSection *RHS) { |
| assert(LHS && RHS && "Null section?"); |
| if (LHS->Address != RHS->Address) |
| return LHS->Address < RHS->Address; |
| return LHS->Size < RHS->Size; |
| }); |
| |
| for (unsigned I = 0, E = Sections.size() - 1; I != E; ++I) { |
| auto &Cur = *Sections[I]; |
| auto &Next = *Sections[I + 1]; |
| if (Next.Address < Cur.Address + Cur.Size) |
| return make_error<JITLinkError>( |
| "Address range for section " + |
| formatv("\"{0}/{1}\" [ {2:x16} -- {3:x16} ] ", Cur.SegName, |
| Cur.SectName, Cur.Address, Cur.Address + Cur.Size) + |
| "overlaps section \"" + Next.SegName + "/" + Next.SectName + "\"" + |
| formatv("\"{0}/{1}\" [ {2:x16} -- {3:x16} ] ", Next.SegName, |
| Next.SectName, Next.Address, Next.Address + Next.Size)); |
| } |
| |
| return Error::success(); |
| } |
| |
| Error MachOLinkGraphBuilder::createNormalizedSymbols() { |
| LLVM_DEBUG(dbgs() << "Creating normalized symbols...\n"); |
| |
| for (auto &SymRef : Obj.symbols()) { |
| |
| unsigned SymbolIndex = Obj.getSymbolIndex(SymRef.getRawDataRefImpl()); |
| uint64_t Value; |
| uint32_t NStrX; |
| uint8_t Type; |
| uint8_t Sect; |
| uint16_t Desc; |
| |
| if (Obj.is64Bit()) { |
| const MachO::nlist_64 &NL64 = |
| Obj.getSymbol64TableEntry(SymRef.getRawDataRefImpl()); |
| Value = NL64.n_value; |
| NStrX = NL64.n_strx; |
| Type = NL64.n_type; |
| Sect = NL64.n_sect; |
| Desc = NL64.n_desc; |
| } else { |
| const MachO::nlist &NL32 = |
| Obj.getSymbolTableEntry(SymRef.getRawDataRefImpl()); |
| Value = NL32.n_value; |
| NStrX = NL32.n_strx; |
| Type = NL32.n_type; |
| Sect = NL32.n_sect; |
| Desc = NL32.n_desc; |
| } |
| |
| // Skip stabs. |
| // FIXME: Are there other symbols we should be skipping? |
| if (Type & MachO::N_STAB) |
| continue; |
| |
| Optional<StringRef> Name; |
| if (NStrX) { |
| if (auto NameOrErr = SymRef.getName()) |
| Name = *NameOrErr; |
| else |
| return NameOrErr.takeError(); |
| } |
| |
| LLVM_DEBUG({ |
| dbgs() << " "; |
| if (!Name) |
| dbgs() << "<anonymous symbol>"; |
| else |
| dbgs() << *Name; |
| dbgs() << ": value = " << formatv("{0:x16}", Value) |
| << ", type = " << formatv("{0:x2}", Type) |
| << ", desc = " << formatv("{0:x4}", Desc) << ", sect = "; |
| if (Sect) |
| dbgs() << static_cast<unsigned>(Sect - 1); |
| else |
| dbgs() << "none"; |
| dbgs() << "\n"; |
| }); |
| |
| // If this symbol has a section, verify that the addresses line up. |
| if (Sect != 0) { |
| auto NSec = findSectionByIndex(Sect - 1); |
| if (!NSec) |
| return NSec.takeError(); |
| |
| if (Value < NSec->Address || Value > NSec->Address + NSec->Size) |
| return make_error<JITLinkError>("Address " + formatv("{0:x}", Value) + |
| " for symbol " + *Name + |
| " does not fall within section"); |
| |
| if (!NSec->GraphSection) { |
| LLVM_DEBUG({ |
| dbgs() << " Skipping: Symbol is in section " << NSec->SegName << "/" |
| << NSec->SectName |
| << " which has no associated graph section.\n"; |
| }); |
| continue; |
| } |
| } |
| |
| IndexToSymbol[SymbolIndex] = |
| &createNormalizedSymbol(*Name, Value, Type, Sect, Desc, |
| getLinkage(Desc), getScope(*Name, Type)); |
| } |
| |
| return Error::success(); |
| } |
| |
| void MachOLinkGraphBuilder::addSectionStartSymAndBlock( |
| unsigned SecIndex, Section &GraphSec, uint64_t Address, const char *Data, |
| uint64_t Size, uint32_t Alignment, bool IsLive) { |
| Block &B = |
| Data ? G->createContentBlock(GraphSec, ArrayRef<char>(Data, Size), |
| Address, Alignment, 0) |
| : G->createZeroFillBlock(GraphSec, Size, Address, Alignment, 0); |
| auto &Sym = G->addAnonymousSymbol(B, 0, Size, false, IsLive); |
| auto SecI = IndexToSection.find(SecIndex); |
| assert(SecI != IndexToSection.end() && "SecIndex invalid"); |
| auto &NSec = SecI->second; |
| assert(!NSec.CanonicalSymbols.count(Sym.getAddress()) && |
| "Anonymous block start symbol clashes with existing symbol address"); |
| NSec.CanonicalSymbols[Sym.getAddress()] = &Sym; |
| } |
| |
| Error MachOLinkGraphBuilder::graphifyRegularSymbols() { |
| |
| LLVM_DEBUG(dbgs() << "Creating graph symbols...\n"); |
| |
| /// We only have 256 section indexes: Use a vector rather than a map. |
| std::vector<std::vector<NormalizedSymbol *>> SecIndexToSymbols; |
| SecIndexToSymbols.resize(256); |
| |
| // Create commons, externs, and absolutes, and partition all other symbols by |
| // section. |
| for (auto &KV : IndexToSymbol) { |
| auto &NSym = *KV.second; |
| |
| switch (NSym.Type & MachO::N_TYPE) { |
| case MachO::N_UNDF: |
| if (NSym.Value) { |
| if (!NSym.Name) |
| return make_error<JITLinkError>("Anonymous common symbol at index " + |
| Twine(KV.first)); |
| NSym.GraphSymbol = &G->addCommonSymbol( |
| *NSym.Name, NSym.S, getCommonSection(), 0, NSym.Value, |
| 1ull << MachO::GET_COMM_ALIGN(NSym.Desc), |
| NSym.Desc & MachO::N_NO_DEAD_STRIP); |
| } else { |
| if (!NSym.Name) |
| return make_error<JITLinkError>("Anonymous external symbol at " |
| "index " + |
| Twine(KV.first)); |
| NSym.GraphSymbol = &G->addExternalSymbol( |
| *NSym.Name, 0, |
| NSym.Desc & MachO::N_WEAK_REF ? Linkage::Weak : Linkage::Strong); |
| } |
| break; |
| case MachO::N_ABS: |
| if (!NSym.Name) |
| return make_error<JITLinkError>("Anonymous absolute symbol at index " + |
| Twine(KV.first)); |
| NSym.GraphSymbol = &G->addAbsoluteSymbol( |
| *NSym.Name, NSym.Value, 0, Linkage::Strong, Scope::Default, |
| NSym.Desc & MachO::N_NO_DEAD_STRIP); |
| break; |
| case MachO::N_SECT: |
| SecIndexToSymbols[NSym.Sect - 1].push_back(&NSym); |
| break; |
| case MachO::N_PBUD: |
| return make_error<JITLinkError>( |
| "Unupported N_PBUD symbol " + |
| (NSym.Name ? ("\"" + *NSym.Name + "\"") : Twine("<anon>")) + |
| " at index " + Twine(KV.first)); |
| case MachO::N_INDR: |
| return make_error<JITLinkError>( |
| "Unupported N_INDR symbol " + |
| (NSym.Name ? ("\"" + *NSym.Name + "\"") : Twine("<anon>")) + |
| " at index " + Twine(KV.first)); |
| default: |
| return make_error<JITLinkError>( |
| "Unrecognized symbol type " + Twine(NSym.Type & MachO::N_TYPE) + |
| " for symbol " + |
| (NSym.Name ? ("\"" + *NSym.Name + "\"") : Twine("<anon>")) + |
| " at index " + Twine(KV.first)); |
| } |
| } |
| |
| // Loop over sections performing regular graphification for those that |
| // don't have custom parsers. |
| for (auto &KV : IndexToSection) { |
| auto SecIndex = KV.first; |
| auto &NSec = KV.second; |
| |
| if (!NSec.GraphSection) { |
| LLVM_DEBUG({ |
| dbgs() << " " << NSec.SegName << "/" << NSec.SectName |
| << " has no graph section. Skipping.\n"; |
| }); |
| continue; |
| } |
| |
| // Skip sections with custom parsers. |
| if (CustomSectionParserFunctions.count(NSec.GraphSection->getName())) { |
| LLVM_DEBUG({ |
| dbgs() << " Skipping section " << NSec.GraphSection->getName() |
| << " as it has a custom parser.\n"; |
| }); |
| continue; |
| } else if ((NSec.Flags & MachO::SECTION_TYPE) == |
| MachO::S_CSTRING_LITERALS) { |
| if (auto Err = graphifyCStringSection( |
| NSec, std::move(SecIndexToSymbols[SecIndex]))) |
| return Err; |
| continue; |
| } else |
| LLVM_DEBUG({ |
| dbgs() << " Graphifying regular section " |
| << NSec.GraphSection->getName() << "...\n"; |
| }); |
| |
| bool SectionIsNoDeadStrip = NSec.Flags & MachO::S_ATTR_NO_DEAD_STRIP; |
| bool SectionIsText = NSec.Flags & MachO::S_ATTR_PURE_INSTRUCTIONS; |
| |
| auto &SecNSymStack = SecIndexToSymbols[SecIndex]; |
| |
| // If this section is non-empty but there are no symbols covering it then |
| // create one block and anonymous symbol to cover the entire section. |
| if (SecNSymStack.empty()) { |
| if (NSec.Size > 0) { |
| LLVM_DEBUG({ |
| dbgs() << " Section non-empty, but contains no symbols. " |
| "Creating anonymous block to cover " |
| << formatv("{0:x16}", NSec.Address) << " -- " |
| << formatv("{0:x16}", NSec.Address + NSec.Size) << "\n"; |
| }); |
| addSectionStartSymAndBlock(SecIndex, *NSec.GraphSection, NSec.Address, |
| NSec.Data, NSec.Size, NSec.Alignment, |
| SectionIsNoDeadStrip); |
| } else |
| LLVM_DEBUG({ |
| dbgs() << " Section empty and contains no symbols. Skipping.\n"; |
| }); |
| continue; |
| } |
| |
| // Sort the symbol stack in by address, alt-entry status, scope, and name. |
| // We sort in reverse order so that symbols will be visited in the right |
| // order when we pop off the stack below. |
| llvm::sort(SecNSymStack, [](const NormalizedSymbol *LHS, |
| const NormalizedSymbol *RHS) { |
| if (LHS->Value != RHS->Value) |
| return LHS->Value > RHS->Value; |
| if (isAltEntry(*LHS) != isAltEntry(*RHS)) |
| return isAltEntry(*RHS); |
| if (LHS->S != RHS->S) |
| return static_cast<uint8_t>(LHS->S) < static_cast<uint8_t>(RHS->S); |
| return LHS->Name < RHS->Name; |
| }); |
| |
| // The first symbol in a section can not be an alt-entry symbol. |
| if (!SecNSymStack.empty() && isAltEntry(*SecNSymStack.back())) |
| return make_error<JITLinkError>( |
| "First symbol in " + NSec.GraphSection->getName() + " is alt-entry"); |
| |
| // If the section is non-empty but there is no symbol covering the start |
| // address then add an anonymous one. |
| if (SecNSymStack.back()->Value != NSec.Address) { |
| auto AnonBlockSize = SecNSymStack.back()->Value - NSec.Address; |
| LLVM_DEBUG({ |
| dbgs() << " Section start not covered by symbol. " |
| << "Creating anonymous block to cover [ " |
| << formatv("{0:x16}", NSec.Address) << " -- " |
| << formatv("{0:x16}", NSec.Address + AnonBlockSize) << " ]\n"; |
| }); |
| addSectionStartSymAndBlock(SecIndex, *NSec.GraphSection, NSec.Address, |
| NSec.Data, AnonBlockSize, NSec.Alignment, |
| SectionIsNoDeadStrip); |
| } |
| |
| // Visit section symbols in order by popping off the reverse-sorted stack, |
| // building blocks for each alt-entry chain and creating symbols as we go. |
| while (!SecNSymStack.empty()) { |
| SmallVector<NormalizedSymbol *, 8> BlockSyms; |
| |
| BlockSyms.push_back(SecNSymStack.back()); |
| SecNSymStack.pop_back(); |
| while (!SecNSymStack.empty() && |
| (isAltEntry(*SecNSymStack.back()) || |
| SecNSymStack.back()->Value == BlockSyms.back()->Value)) { |
| BlockSyms.push_back(SecNSymStack.back()); |
| SecNSymStack.pop_back(); |
| } |
| |
| // BlockNSyms now contains the block symbols in reverse canonical order. |
| JITTargetAddress BlockStart = BlockSyms.front()->Value; |
| JITTargetAddress BlockEnd = SecNSymStack.empty() |
| ? NSec.Address + NSec.Size |
| : SecNSymStack.back()->Value; |
| JITTargetAddress BlockOffset = BlockStart - NSec.Address; |
| JITTargetAddress BlockSize = BlockEnd - BlockStart; |
| |
| LLVM_DEBUG({ |
| dbgs() << " Creating block for " << formatv("{0:x16}", BlockStart) |
| << " -- " << formatv("{0:x16}", BlockEnd) << ": " |
| << NSec.GraphSection->getName() << " + " |
| << formatv("{0:x16}", BlockOffset) << " with " |
| << BlockSyms.size() << " symbol(s)...\n"; |
| }); |
| |
| Block &B = |
| NSec.Data |
| ? G->createContentBlock( |
| *NSec.GraphSection, |
| ArrayRef<char>(NSec.Data + BlockOffset, BlockSize), |
| BlockStart, NSec.Alignment, BlockStart % NSec.Alignment) |
| : G->createZeroFillBlock(*NSec.GraphSection, BlockSize, |
| BlockStart, NSec.Alignment, |
| BlockStart % NSec.Alignment); |
| |
| Optional<JITTargetAddress> LastCanonicalAddr; |
| JITTargetAddress SymEnd = BlockEnd; |
| while (!BlockSyms.empty()) { |
| auto &NSym = *BlockSyms.back(); |
| BlockSyms.pop_back(); |
| |
| bool SymLive = |
| (NSym.Desc & MachO::N_NO_DEAD_STRIP) || SectionIsNoDeadStrip; |
| |
| auto &Sym = createStandardGraphSymbol(NSym, B, SymEnd - NSym.Value, |
| SectionIsText, SymLive, |
| LastCanonicalAddr != NSym.Value); |
| |
| if (LastCanonicalAddr != Sym.getAddress()) { |
| if (LastCanonicalAddr) |
| SymEnd = *LastCanonicalAddr; |
| LastCanonicalAddr = Sym.getAddress(); |
| } |
| } |
| } |
| } |
| |
| return Error::success(); |
| } |
| |
| Symbol &MachOLinkGraphBuilder::createStandardGraphSymbol(NormalizedSymbol &NSym, |
| Block &B, size_t Size, |
| bool IsText, |
| bool IsNoDeadStrip, |
| bool IsCanonical) { |
| |
| LLVM_DEBUG({ |
| dbgs() << " " << formatv("{0:x16}", NSym.Value) << " -- " |
| << formatv("{0:x16}", NSym.Value + Size) << ": "; |
| if (!NSym.Name) |
| dbgs() << "<anonymous symbol>"; |
| else |
| dbgs() << NSym.Name; |
| if (IsText) |
| dbgs() << " [text]"; |
| if (IsNoDeadStrip) |
| dbgs() << " [no-dead-strip]"; |
| if (!IsCanonical) |
| dbgs() << " [non-canonical]"; |
| dbgs() << "\n"; |
| }); |
| |
| auto &Sym = NSym.Name ? G->addDefinedSymbol(B, NSym.Value - B.getAddress(), |
| *NSym.Name, Size, NSym.L, NSym.S, |
| IsText, IsNoDeadStrip) |
| : G->addAnonymousSymbol(B, NSym.Value - B.getAddress(), |
| Size, IsText, IsNoDeadStrip); |
| NSym.GraphSymbol = &Sym; |
| |
| if (IsCanonical) |
| setCanonicalSymbol(getSectionByIndex(NSym.Sect - 1), Sym); |
| |
| return Sym; |
| } |
| |
| Error MachOLinkGraphBuilder::graphifySectionsWithCustomParsers() { |
| // Graphify special sections. |
| for (auto &KV : IndexToSection) { |
| auto &NSec = KV.second; |
| |
| // Skip non-graph sections. |
| if (!NSec.GraphSection) |
| continue; |
| |
| auto HI = CustomSectionParserFunctions.find(NSec.GraphSection->getName()); |
| if (HI != CustomSectionParserFunctions.end()) { |
| auto &Parse = HI->second; |
| if (auto Err = Parse(NSec)) |
| return Err; |
| } |
| } |
| |
| return Error::success(); |
| } |
| |
| Error MachOLinkGraphBuilder::graphifyCStringSection( |
| NormalizedSection &NSec, std::vector<NormalizedSymbol *> NSyms) { |
| assert(NSec.GraphSection && "C string literal section missing graph section"); |
| assert(NSec.Data && "C string literal section has no data"); |
| |
| LLVM_DEBUG({ |
| dbgs() << " Graphifying C-string literal section " |
| << NSec.GraphSection->getName() << "\n"; |
| }); |
| |
| if (NSec.Data[NSec.Size - 1] != '\0') |
| return make_error<JITLinkError>("C string literal section " + |
| NSec.GraphSection->getName() + |
| " does not end with null terminator"); |
| |
| /// Sort into reverse order to use as a stack. |
| llvm::sort(NSyms, |
| [](const NormalizedSymbol *LHS, const NormalizedSymbol *RHS) { |
| if (LHS->Value != RHS->Value) |
| return LHS->Value > RHS->Value; |
| if (LHS->L != RHS->L) |
| return LHS->L > RHS->L; |
| if (LHS->S != RHS->S) |
| return LHS->S > RHS->S; |
| if (RHS->Name) { |
| if (!LHS->Name) |
| return true; |
| return *LHS->Name > *RHS->Name; |
| } |
| return false; |
| }); |
| |
| bool SectionIsNoDeadStrip = NSec.Flags & MachO::S_ATTR_NO_DEAD_STRIP; |
| bool SectionIsText = NSec.Flags & MachO::S_ATTR_PURE_INSTRUCTIONS; |
| JITTargetAddress BlockStart = 0; |
| |
| // Scan section for null characters. |
| for (size_t I = 0; I != NSec.Size; ++I) |
| if (NSec.Data[I] == '\0') { |
| JITTargetAddress BlockEnd = I + 1; |
| size_t BlockSize = BlockEnd - BlockStart; |
| // Create a block for this null terminated string. |
| auto &B = G->createContentBlock(*NSec.GraphSection, |
| {NSec.Data + BlockStart, BlockSize}, |
| NSec.Address + BlockStart, 1, 0); |
| |
| LLVM_DEBUG({ |
| dbgs() << " Created block " << formatv("{0:x}", B.getAddress()) |
| << " -- " << formatv("{0:x}", B.getAddress() + B.getSize()) |
| << " for \"" << StringRef(B.getContent().data()) << "\"\n"; |
| }); |
| |
| // If there's no symbol at the start of this block then create one. |
| if (NSyms.empty() || NSyms.back()->Value != B.getAddress()) { |
| auto &S = G->addAnonymousSymbol(B, 0, BlockSize, false, false); |
| setCanonicalSymbol(NSec, S); |
| LLVM_DEBUG({ |
| dbgs() << " Adding anonymous symbol for c-string block " |
| << formatv("{0:x16} -- {1:x16}", S.getAddress(), |
| S.getAddress() + BlockSize) |
| << "\n"; |
| }); |
| } |
| |
| // Process any remaining symbols that point into this block. |
| JITTargetAddress LastCanonicalAddr = B.getAddress() + BlockEnd; |
| while (!NSyms.empty() && |
| NSyms.back()->Value < (B.getAddress() + BlockSize)) { |
| auto &NSym = *NSyms.back(); |
| size_t SymSize = (B.getAddress() + BlockSize) - NSyms.back()->Value; |
| bool SymLive = |
| (NSym.Desc & MachO::N_NO_DEAD_STRIP) || SectionIsNoDeadStrip; |
| |
| bool IsCanonical = false; |
| if (LastCanonicalAddr != NSym.Value) { |
| IsCanonical = true; |
| LastCanonicalAddr = NSym.Value; |
| } |
| |
| createStandardGraphSymbol(NSym, B, SymSize, SectionIsText, SymLive, |
| IsCanonical); |
| |
| NSyms.pop_back(); |
| } |
| |
| BlockStart += BlockSize; |
| } |
| |
| return Error::success(); |
| } |
| |
| Error CompactUnwindSplitter::operator()(LinkGraph &G) { |
| auto *CUSec = G.findSectionByName(CompactUnwindSectionName); |
| if (!CUSec) |
| return Error::success(); |
| |
| if (!G.getTargetTriple().isOSBinFormatMachO()) |
| return make_error<JITLinkError>( |
| "Error linking " + G.getName() + |
| ": compact unwind splitting not supported on non-macho target " + |
| G.getTargetTriple().str()); |
| |
| unsigned CURecordSize = 0; |
| unsigned PersonalityEdgeOffset = 0; |
| unsigned LSDAEdgeOffset = 0; |
| switch (G.getTargetTriple().getArch()) { |
| case Triple::aarch64: |
| case Triple::x86_64: |
| // 64-bit compact-unwind record format: |
| // Range start: 8 bytes. |
| // Range size: 4 bytes. |
| // CU encoding: 4 bytes. |
| // Personality: 8 bytes. |
| // LSDA: 8 bytes. |
| CURecordSize = 32; |
| PersonalityEdgeOffset = 16; |
| LSDAEdgeOffset = 24; |
| break; |
| default: |
| return make_error<JITLinkError>( |
| "Error linking " + G.getName() + |
| ": compact unwind splitting not supported on " + |
| G.getTargetTriple().getArchName()); |
| } |
| |
| std::vector<Block *> OriginalBlocks(CUSec->blocks().begin(), |
| CUSec->blocks().end()); |
| LLVM_DEBUG({ |
| dbgs() << "In " << G.getName() << " splitting compact unwind section " |
| << CompactUnwindSectionName << " containing " |
| << OriginalBlocks.size() << " initial blocks...\n"; |
| }); |
| |
| while (!OriginalBlocks.empty()) { |
| auto *B = OriginalBlocks.back(); |
| OriginalBlocks.pop_back(); |
| |
| if (B->getSize() == 0) { |
| LLVM_DEBUG({ |
| dbgs() << " Skipping empty block at " |
| << formatv("{0:x16}", B->getAddress()) << "\n"; |
| }); |
| continue; |
| } |
| |
| LLVM_DEBUG({ |
| dbgs() << " Splitting block at " << formatv("{0:x16}", B->getAddress()) |
| << " into " << (B->getSize() / CURecordSize) |
| << " compact unwind record(s)\n"; |
| }); |
| |
| if (B->getSize() % CURecordSize) |
| return make_error<JITLinkError>( |
| "Error splitting compact unwind record in " + G.getName() + |
| ": block at " + formatv("{0:x}", B->getAddress()) + " has size " + |
| formatv("{0:x}", B->getSize()) + |
| " (not a multiple of CU record size of " + |
| formatv("{0:x}", CURecordSize) + ")"); |
| |
| unsigned NumBlocks = B->getSize() / CURecordSize; |
| LinkGraph::SplitBlockCache C; |
| |
| for (unsigned I = 0; I != NumBlocks; ++I) { |
| auto &CURec = G.splitBlock(*B, CURecordSize, &C); |
| bool AddedKeepAlive = false; |
| |
| for (auto &E : CURec.edges()) { |
| if (E.getOffset() == 0) { |
| LLVM_DEBUG({ |
| dbgs() << " Updating compact unwind record at " |
| << formatv("{0:x16}", CURec.getAddress()) << " to point to " |
| << (E.getTarget().hasName() ? E.getTarget().getName() |
| : StringRef()) |
| << " (at " << formatv("{0:x16}", E.getTarget().getAddress()) |
| << ")\n"; |
| }); |
| |
| if (E.getTarget().isExternal()) |
| return make_error<JITLinkError>( |
| "Error adding keep-alive edge for compact unwind record at " + |
| formatv("{0:x}", CURec.getAddress()) + ": target " + |
| E.getTarget().getName() + " is an external symbol"); |
| auto &TgtBlock = E.getTarget().getBlock(); |
| auto &CURecSym = |
| G.addAnonymousSymbol(CURec, 0, CURecordSize, 0, false); |
| TgtBlock.addEdge(Edge::KeepAlive, 0, CURecSym, 0); |
| AddedKeepAlive = true; |
| } else if (E.getOffset() != PersonalityEdgeOffset && |
| E.getOffset() != LSDAEdgeOffset) |
| return make_error<JITLinkError>("Unexpected edge at offset " + |
| formatv("{0:x}", E.getOffset()) + |
| " in compact unwind record at " + |
| formatv("{0:x}", CURec.getAddress())); |
| } |
| |
| if (!AddedKeepAlive) |
| return make_error<JITLinkError>( |
| "Error adding keep-alive edge for compact unwind record at " + |
| formatv("{0:x}", CURec.getAddress()) + |
| ": no outgoing target edge at offset 0"); |
| } |
| } |
| return Error::success(); |
| } |
| |
| } // end namespace jitlink |
| } // end namespace llvm |
