Index: vendor/lld/dist-release_70/COFF/InputFiles.cpp =================================================================== --- vendor/lld/dist-release_70/COFF/InputFiles.cpp (revision 337638) +++ vendor/lld/dist-release_70/COFF/InputFiles.cpp (revision 337639) @@ -1,519 +1,563 @@ //===- InputFiles.cpp -----------------------------------------------------===// // // The LLVM Linker // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// #include "InputFiles.h" #include "Chunks.h" #include "Config.h" #include "Driver.h" #include "SymbolTable.h" #include "Symbols.h" #include "lld/Common/ErrorHandler.h" #include "lld/Common/Memory.h" #include "llvm-c/lto.h" #include "llvm/ADT/SmallVector.h" #include "llvm/ADT/Triple.h" #include "llvm/ADT/Twine.h" #include "llvm/BinaryFormat/COFF.h" #include "llvm/Object/Binary.h" #include "llvm/Object/COFF.h" #include "llvm/Support/Casting.h" #include "llvm/Support/Endian.h" #include "llvm/Support/Error.h" #include "llvm/Support/ErrorOr.h" #include "llvm/Support/FileSystem.h" #include "llvm/Support/Path.h" #include "llvm/Target/TargetOptions.h" #include #include #include using namespace llvm; using namespace llvm::COFF; using namespace llvm::object; using namespace llvm::support::endian; using llvm::Triple; using llvm::support::ulittle32_t; namespace lld { namespace coff { std::vector ObjFile::Instances; std::vector ImportFile::Instances; std::vector BitcodeFile::Instances; /// Checks that Source is compatible with being a weak alias to Target. /// If Source is Undefined and has no weak alias set, makes it a weak /// alias to Target. static void checkAndSetWeakAlias(SymbolTable *Symtab, InputFile *F, Symbol *Source, Symbol *Target) { if (auto *U = dyn_cast(Source)) { if (U->WeakAlias && U->WeakAlias != Target) Symtab->reportDuplicate(Source, F); U->WeakAlias = Target; } } ArchiveFile::ArchiveFile(MemoryBufferRef M) : InputFile(ArchiveKind, M) {} void ArchiveFile::parse() { // Parse a MemoryBufferRef as an archive file. File = CHECK(Archive::create(MB), this); // Read the symbol table to construct Lazy objects. for (const Archive::Symbol &Sym : File->symbols()) Symtab->addLazy(this, Sym); } // Returns a buffer pointing to a member file containing a given symbol. void ArchiveFile::addMember(const Archive::Symbol *Sym) { const Archive::Child &C = CHECK(Sym->getMember(), "could not get the member for symbol " + Sym->getName()); // Return an empty buffer if we have already returned the same buffer. if (!Seen.insert(C.getChildOffset()).second) return; Driver->enqueueArchiveMember(C, Sym->getName(), getName()); } std::vector getArchiveMembers(Archive *File) { std::vector V; Error Err = Error::success(); for (const ErrorOr &COrErr : File->children(Err)) { Archive::Child C = CHECK(COrErr, File->getFileName() + ": could not get the child of the archive"); MemoryBufferRef MBRef = CHECK(C.getMemoryBufferRef(), File->getFileName() + ": could not get the buffer for a child of the archive"); V.push_back(MBRef); } if (Err) fatal(File->getFileName() + ": Archive::children failed: " + toString(std::move(Err))); return V; } void ObjFile::parse() { // Parse a memory buffer as a COFF file. std::unique_ptr Bin = CHECK(createBinary(MB), this); if (auto *Obj = dyn_cast(Bin.get())) { Bin.release(); COFFObj.reset(Obj); } else { fatal(toString(this) + " is not a COFF file"); } // Read section and symbol tables. initializeChunks(); initializeSymbols(); } // We set SectionChunk pointers in the SparseChunks vector to this value // temporarily to mark comdat sections as having an unknown resolution. As we // walk the object file's symbol table, once we visit either a leader symbol or // an associative section definition together with the parent comdat's leader, // we set the pointer to either nullptr (to mark the section as discarded) or a // valid SectionChunk for that section. static SectionChunk *const PendingComdat = reinterpret_cast(1); void ObjFile::initializeChunks() { uint32_t NumSections = COFFObj->getNumberOfSections(); Chunks.reserve(NumSections); SparseChunks.resize(NumSections + 1); for (uint32_t I = 1; I < NumSections + 1; ++I) { const coff_section *Sec; if (auto EC = COFFObj->getSection(I, Sec)) fatal("getSection failed: #" + Twine(I) + ": " + EC.message()); if (Sec->Characteristics & IMAGE_SCN_LNK_COMDAT) SparseChunks[I] = PendingComdat; else SparseChunks[I] = readSection(I, nullptr, ""); } } SectionChunk *ObjFile::readSection(uint32_t SectionNumber, const coff_aux_section_definition *Def, StringRef LeaderName) { const coff_section *Sec; StringRef Name; if (auto EC = COFFObj->getSection(SectionNumber, Sec)) fatal("getSection failed: #" + Twine(SectionNumber) + ": " + EC.message()); if (auto EC = COFFObj->getSectionName(Sec, Name)) fatal("getSectionName failed: #" + Twine(SectionNumber) + ": " + EC.message()); if (Name == ".drectve") { ArrayRef Data; COFFObj->getSectionContents(Sec, Data); Directives = std::string((const char *)Data.data(), Data.size()); return nullptr; } // Object files may have DWARF debug info or MS CodeView debug info // (or both). // // DWARF sections don't need any special handling from the perspective // of the linker; they are just a data section containing relocations. // We can just link them to complete debug info. // // CodeView needs a linker support. We need to interpret and debug // info, and then write it to a separate .pdb file. // Ignore DWARF debug info unless /debug is given. if (!Config->Debug && Name.startswith(".debug_")) return nullptr; if (Sec->Characteristics & llvm::COFF::IMAGE_SCN_LNK_REMOVE) return nullptr; auto *C = make(this, Sec); if (Def) C->Checksum = Def->CheckSum; // CodeView sections are stored to a different vector because they are not // linked in the regular manner. if (C->isCodeView()) DebugChunks.push_back(C); else if (Config->GuardCF != GuardCFLevel::Off && Name == ".gfids$y") GuardFidChunks.push_back(C); else if (Config->GuardCF != GuardCFLevel::Off && Name == ".gljmp$y") GuardLJmpChunks.push_back(C); else if (Name == ".sxdata") SXDataChunks.push_back(C); else if (Config->TailMerge && Sec->NumberOfRelocations == 0 && Name == ".rdata" && LeaderName.startswith("??_C@")) // COFF sections that look like string literal sections (i.e. no // relocations, in .rdata, leader symbol name matches the MSVC name mangling // for string literals) are subject to string tail merging. MergeChunk::addSection(C); else Chunks.push_back(C); return C; } void ObjFile::readAssociativeDefinition( COFFSymbolRef Sym, const coff_aux_section_definition *Def) { - SectionChunk *Parent = SparseChunks[Def->getNumber(Sym.isBigObj())]; + readAssociativeDefinition(Sym, Def, Def->getNumber(Sym.isBigObj())); +} +void ObjFile::readAssociativeDefinition(COFFSymbolRef Sym, + const coff_aux_section_definition *Def, + uint32_t ParentSection) { + SectionChunk *Parent = SparseChunks[ParentSection]; + // If the parent is pending, it probably means that its section definition // appears after us in the symbol table. Leave the associated section as // pending; we will handle it during the second pass in initializeSymbols(). if (Parent == PendingComdat) return; // Check whether the parent is prevailing. If it is, so are we, and we read // the section; otherwise mark it as discarded. int32_t SectionNumber = Sym.getSectionNumber(); if (Parent) { SparseChunks[SectionNumber] = readSection(SectionNumber, Def, ""); if (SparseChunks[SectionNumber]) Parent->addAssociative(SparseChunks[SectionNumber]); } else { SparseChunks[SectionNumber] = nullptr; } } +void ObjFile::recordPrevailingSymbolForMingw( + COFFSymbolRef Sym, DenseMap &PrevailingSectionMap) { + // For comdat symbols in executable sections, where this is the copy + // of the section chunk we actually include instead of discarding it, + // add the symbol to a map to allow using it for implicitly + // associating .[px]data$ sections to it. + int32_t SectionNumber = Sym.getSectionNumber(); + SectionChunk *SC = SparseChunks[SectionNumber]; + if (SC && SC->getOutputCharacteristics() & IMAGE_SCN_MEM_EXECUTE) { + StringRef Name; + COFFObj->getSymbolName(Sym, Name); + PrevailingSectionMap[Name] = SectionNumber; + } +} + +void ObjFile::maybeAssociateSEHForMingw( + COFFSymbolRef Sym, const coff_aux_section_definition *Def, + const DenseMap &PrevailingSectionMap) { + StringRef Name; + COFFObj->getSymbolName(Sym, Name); + if (Name.consume_front(".pdata$") || Name.consume_front(".xdata$")) { + // For MinGW, treat .[px]data$ as implicitly associative to + // the symbol . + auto ParentSym = PrevailingSectionMap.find(Name); + if (ParentSym != PrevailingSectionMap.end()) + readAssociativeDefinition(Sym, Def, ParentSym->second); + } +} + Symbol *ObjFile::createRegular(COFFSymbolRef Sym) { SectionChunk *SC = SparseChunks[Sym.getSectionNumber()]; if (Sym.isExternal()) { StringRef Name; COFFObj->getSymbolName(Sym, Name); if (SC) return Symtab->addRegular(this, Name, Sym.getGeneric(), SC); return Symtab->addUndefined(Name, this, false); } if (SC) return make(this, /*Name*/ "", false, /*IsExternal*/ false, Sym.getGeneric(), SC); return nullptr; } void ObjFile::initializeSymbols() { uint32_t NumSymbols = COFFObj->getNumberOfSymbols(); Symbols.resize(NumSymbols); SmallVector, 8> WeakAliases; std::vector PendingIndexes; PendingIndexes.reserve(NumSymbols); + DenseMap PrevailingSectionMap; std::vector ComdatDefs( COFFObj->getNumberOfSections() + 1); for (uint32_t I = 0; I < NumSymbols; ++I) { COFFSymbolRef COFFSym = check(COFFObj->getSymbol(I)); + bool PrevailingComdat; if (COFFSym.isUndefined()) { Symbols[I] = createUndefined(COFFSym); } else if (COFFSym.isWeakExternal()) { Symbols[I] = createUndefined(COFFSym); uint32_t TagIndex = COFFSym.getAux()->TagIndex; WeakAliases.emplace_back(Symbols[I], TagIndex); - } else if (Optional OptSym = createDefined(COFFSym, ComdatDefs)) { + } else if (Optional OptSym = + createDefined(COFFSym, ComdatDefs, PrevailingComdat)) { Symbols[I] = *OptSym; + if (Config->MinGW && PrevailingComdat) + recordPrevailingSymbolForMingw(COFFSym, PrevailingSectionMap); } else { // createDefined() returns None if a symbol belongs to a section that // was pending at the point when the symbol was read. This can happen in // two cases: // 1) section definition symbol for a comdat leader; // 2) symbol belongs to a comdat section associated with a section whose // section definition symbol appears later in the symbol table. // In both of these cases, we can expect the section to be resolved by // the time we finish visiting the remaining symbols in the symbol // table. So we postpone the handling of this symbol until that time. PendingIndexes.push_back(I); } I += COFFSym.getNumberOfAuxSymbols(); } for (uint32_t I : PendingIndexes) { COFFSymbolRef Sym = check(COFFObj->getSymbol(I)); - if (auto *Def = Sym.getSectionDefinition()) + if (auto *Def = Sym.getSectionDefinition()) { if (Def->Selection == IMAGE_COMDAT_SELECT_ASSOCIATIVE) readAssociativeDefinition(Sym, Def); + else if (Config->MinGW) + maybeAssociateSEHForMingw(Sym, Def, PrevailingSectionMap); + } if (SparseChunks[Sym.getSectionNumber()] == PendingComdat) { StringRef Name; COFFObj->getSymbolName(Sym, Name); log("comdat section " + Name + " without leader and unassociated, discarding"); continue; } Symbols[I] = createRegular(Sym); } for (auto &KV : WeakAliases) { Symbol *Sym = KV.first; uint32_t Idx = KV.second; checkAndSetWeakAlias(Symtab, this, Sym, Symbols[Idx]); } } Symbol *ObjFile::createUndefined(COFFSymbolRef Sym) { StringRef Name; COFFObj->getSymbolName(Sym, Name); return Symtab->addUndefined(Name, this, Sym.isWeakExternal()); } Optional ObjFile::createDefined( COFFSymbolRef Sym, - std::vector &ComdatDefs) { + std::vector &ComdatDefs, + bool &Prevailing) { + Prevailing = false; auto GetName = [&]() { StringRef S; COFFObj->getSymbolName(Sym, S); return S; }; if (Sym.isCommon()) { auto *C = make(Sym); Chunks.push_back(C); return Symtab->addCommon(this, GetName(), Sym.getValue(), Sym.getGeneric(), C); } if (Sym.isAbsolute()) { StringRef Name = GetName(); // Skip special symbols. if (Name == "@comp.id") return nullptr; if (Name == "@feat.00") { Feat00Flags = Sym.getValue(); return nullptr; } if (Sym.isExternal()) return Symtab->addAbsolute(Name, Sym); return make(Name, Sym); } int32_t SectionNumber = Sym.getSectionNumber(); if (SectionNumber == llvm::COFF::IMAGE_SYM_DEBUG) return nullptr; if (llvm::COFF::isReservedSectionNumber(SectionNumber)) fatal(toString(this) + ": " + GetName() + " should not refer to special section " + Twine(SectionNumber)); if ((uint32_t)SectionNumber >= SparseChunks.size()) fatal(toString(this) + ": " + GetName() + " should not refer to non-existent section " + Twine(SectionNumber)); // Handle comdat leader symbols. if (const coff_aux_section_definition *Def = ComdatDefs[SectionNumber]) { ComdatDefs[SectionNumber] = nullptr; Symbol *Leader; - bool Prevailing; if (Sym.isExternal()) { std::tie(Leader, Prevailing) = Symtab->addComdat(this, GetName(), Sym.getGeneric()); } else { Leader = make(this, /*Name*/ "", false, /*IsExternal*/ false, Sym.getGeneric()); Prevailing = true; } if (Prevailing) { SectionChunk *C = readSection(SectionNumber, Def, GetName()); SparseChunks[SectionNumber] = C; C->Sym = cast(Leader); cast(Leader)->Data = &C->Repl; } else { SparseChunks[SectionNumber] = nullptr; } return Leader; } // Read associative section definitions and prepare to handle the comdat // leader symbol by setting the section's ComdatDefs pointer if we encounter a // non-associative comdat. if (SparseChunks[SectionNumber] == PendingComdat) { if (auto *Def = Sym.getSectionDefinition()) { if (Def->Selection == IMAGE_COMDAT_SELECT_ASSOCIATIVE) readAssociativeDefinition(Sym, Def); else ComdatDefs[SectionNumber] = Def; } } if (SparseChunks[SectionNumber] == PendingComdat) return None; return createRegular(Sym); } MachineTypes ObjFile::getMachineType() { if (COFFObj) return static_cast(COFFObj->getMachine()); return IMAGE_FILE_MACHINE_UNKNOWN; } StringRef ltrim1(StringRef S, const char *Chars) { if (!S.empty() && strchr(Chars, S[0])) return S.substr(1); return S; } void ImportFile::parse() { const char *Buf = MB.getBufferStart(); const char *End = MB.getBufferEnd(); const auto *Hdr = reinterpret_cast(Buf); // Check if the total size is valid. if ((size_t)(End - Buf) != (sizeof(*Hdr) + Hdr->SizeOfData)) fatal("broken import library"); // Read names and create an __imp_ symbol. StringRef Name = Saver.save(StringRef(Buf + sizeof(*Hdr))); StringRef ImpName = Saver.save("__imp_" + Name); const char *NameStart = Buf + sizeof(coff_import_header) + Name.size() + 1; DLLName = StringRef(NameStart); StringRef ExtName; switch (Hdr->getNameType()) { case IMPORT_ORDINAL: ExtName = ""; break; case IMPORT_NAME: ExtName = Name; break; case IMPORT_NAME_NOPREFIX: ExtName = ltrim1(Name, "?@_"); break; case IMPORT_NAME_UNDECORATE: ExtName = ltrim1(Name, "?@_"); ExtName = ExtName.substr(0, ExtName.find('@')); break; } this->Hdr = Hdr; ExternalName = ExtName; ImpSym = Symtab->addImportData(ImpName, this); if (Hdr->getType() == llvm::COFF::IMPORT_CONST) static_cast(Symtab->addImportData(Name, this)); // If type is function, we need to create a thunk which jump to an // address pointed by the __imp_ symbol. (This allows you to call // DLL functions just like regular non-DLL functions.) if (Hdr->getType() == llvm::COFF::IMPORT_CODE) ThunkSym = Symtab->addImportThunk( Name, cast_or_null(ImpSym), Hdr->Machine); } void BitcodeFile::parse() { Obj = check(lto::InputFile::create(MemoryBufferRef( MB.getBuffer(), Saver.save(ParentName + MB.getBufferIdentifier())))); std::vector> Comdat(Obj->getComdatTable().size()); for (size_t I = 0; I != Obj->getComdatTable().size(); ++I) Comdat[I] = Symtab->addComdat(this, Saver.save(Obj->getComdatTable()[I])); for (const lto::InputFile::Symbol &ObjSym : Obj->symbols()) { StringRef SymName = Saver.save(ObjSym.getName()); int ComdatIndex = ObjSym.getComdatIndex(); Symbol *Sym; if (ObjSym.isUndefined()) { Sym = Symtab->addUndefined(SymName, this, false); } else if (ObjSym.isCommon()) { Sym = Symtab->addCommon(this, SymName, ObjSym.getCommonSize()); } else if (ObjSym.isWeak() && ObjSym.isIndirect()) { // Weak external. Sym = Symtab->addUndefined(SymName, this, true); std::string Fallback = ObjSym.getCOFFWeakExternalFallback(); Symbol *Alias = Symtab->addUndefined(Saver.save(Fallback)); checkAndSetWeakAlias(Symtab, this, Sym, Alias); } else if (ComdatIndex != -1) { if (SymName == Obj->getComdatTable()[ComdatIndex]) Sym = Comdat[ComdatIndex].first; else if (Comdat[ComdatIndex].second) Sym = Symtab->addRegular(this, SymName); else Sym = Symtab->addUndefined(SymName, this, false); } else { Sym = Symtab->addRegular(this, SymName); } Symbols.push_back(Sym); } Directives = Obj->getCOFFLinkerOpts(); } MachineTypes BitcodeFile::getMachineType() { switch (Triple(Obj->getTargetTriple()).getArch()) { case Triple::x86_64: return AMD64; case Triple::x86: return I386; case Triple::arm: return ARMNT; case Triple::aarch64: return ARM64; default: return IMAGE_FILE_MACHINE_UNKNOWN; } } } // namespace coff } // namespace lld // Returns the last element of a path, which is supposed to be a filename. static StringRef getBasename(StringRef Path) { return sys::path::filename(Path, sys::path::Style::windows); } // Returns a string in the format of "foo.obj" or "foo.obj(bar.lib)". std::string lld::toString(const coff::InputFile *File) { if (!File) return ""; if (File->ParentName.empty()) return File->getName(); return (getBasename(File->ParentName) + "(" + getBasename(File->getName()) + ")") .str(); } Index: vendor/lld/dist-release_70/COFF/InputFiles.h =================================================================== --- vendor/lld/dist-release_70/COFF/InputFiles.h (revision 337638) +++ vendor/lld/dist-release_70/COFF/InputFiles.h (revision 337639) @@ -1,254 +1,269 @@ //===- InputFiles.h ---------------------------------------------*- C++ -*-===// // // The LLVM Linker // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// #ifndef LLD_COFF_INPUT_FILES_H #define LLD_COFF_INPUT_FILES_H #include "Config.h" #include "lld/Common/LLVM.h" #include "llvm/ADT/ArrayRef.h" +#include "llvm/ADT/DenseMap.h" #include "llvm/ADT/DenseSet.h" #include "llvm/LTO/LTO.h" #include "llvm/Object/Archive.h" #include "llvm/Object/COFF.h" #include "llvm/Support/StringSaver.h" #include #include #include namespace llvm { namespace pdb { class DbiModuleDescriptorBuilder; } } namespace lld { namespace coff { std::vector getArchiveMembers(llvm::object::Archive *File); using llvm::COFF::IMAGE_FILE_MACHINE_UNKNOWN; using llvm::COFF::MachineTypes; using llvm::object::Archive; using llvm::object::COFFObjectFile; using llvm::object::COFFSymbolRef; using llvm::object::coff_import_header; using llvm::object::coff_section; class Chunk; class Defined; class DefinedImportData; class DefinedImportThunk; class Lazy; class SectionChunk; class Symbol; class Undefined; // The root class of input files. class InputFile { public: enum Kind { ArchiveKind, ObjectKind, ImportKind, BitcodeKind }; Kind kind() const { return FileKind; } virtual ~InputFile() {} // Returns the filename. StringRef getName() const { return MB.getBufferIdentifier(); } // Reads a file (the constructor doesn't do that). virtual void parse() = 0; // Returns the CPU type this file was compiled to. virtual MachineTypes getMachineType() { return IMAGE_FILE_MACHINE_UNKNOWN; } MemoryBufferRef MB; // An archive file name if this file is created from an archive. StringRef ParentName; // Returns .drectve section contents if exist. StringRef getDirectives() { return StringRef(Directives).trim(); } protected: InputFile(Kind K, MemoryBufferRef M) : MB(M), FileKind(K) {} std::string Directives; private: const Kind FileKind; }; // .lib or .a file. class ArchiveFile : public InputFile { public: explicit ArchiveFile(MemoryBufferRef M); static bool classof(const InputFile *F) { return F->kind() == ArchiveKind; } void parse() override; // Enqueues an archive member load for the given symbol. If we've already // enqueued a load for the same archive member, this function does nothing, // which ensures that we don't load the same member more than once. void addMember(const Archive::Symbol *Sym); private: std::unique_ptr File; std::string Filename; llvm::DenseSet Seen; }; // .obj or .o file. This may be a member of an archive file. class ObjFile : public InputFile { public: explicit ObjFile(MemoryBufferRef M) : InputFile(ObjectKind, M) {} static bool classof(const InputFile *F) { return F->kind() == ObjectKind; } void parse() override; MachineTypes getMachineType() override; ArrayRef getChunks() { return Chunks; } ArrayRef getDebugChunks() { return DebugChunks; } ArrayRef getSXDataChunks() { return SXDataChunks; } ArrayRef getGuardFidChunks() { return GuardFidChunks; } ArrayRef getGuardLJmpChunks() { return GuardLJmpChunks; } ArrayRef getSymbols() { return Symbols; } // Returns a Symbol object for the SymbolIndex'th symbol in the // underlying object file. Symbol *getSymbol(uint32_t SymbolIndex) { return Symbols[SymbolIndex]; } // Returns the underying COFF file. COFFObjectFile *getCOFFObj() { return COFFObj.get(); } static std::vector Instances; // Flags in the absolute @feat.00 symbol if it is present. These usually // indicate if an object was compiled with certain security features enabled // like stack guard, safeseh, /guard:cf, or other things. uint32_t Feat00Flags = 0; // True if this object file is compatible with SEH. COFF-specific and // x86-only. COFF spec 5.10.1. The .sxdata section. bool hasSafeSEH() { return Feat00Flags & 0x1; } // True if this file was compiled with /guard:cf. bool hasGuardCF() { return Feat00Flags & 0x800; } // Pointer to the PDB module descriptor builder. Various debug info records // will reference object files by "module index", which is here. Things like // source files and section contributions are also recorded here. Will be null // if we are not producing a PDB. llvm::pdb::DbiModuleDescriptorBuilder *ModuleDBI = nullptr; private: void initializeChunks(); void initializeSymbols(); SectionChunk * readSection(uint32_t SectionNumber, const llvm::object::coff_aux_section_definition *Def, StringRef LeaderName); void readAssociativeDefinition( COFFSymbolRef COFFSym, const llvm::object::coff_aux_section_definition *Def); + void readAssociativeDefinition( + COFFSymbolRef COFFSym, + const llvm::object::coff_aux_section_definition *Def, + uint32_t ParentSection); + + void recordPrevailingSymbolForMingw( + COFFSymbolRef COFFSym, + llvm::DenseMap &PrevailingSectionMap); + + void maybeAssociateSEHForMingw( + COFFSymbolRef Sym, const llvm::object::coff_aux_section_definition *Def, + const llvm::DenseMap &PrevailingSectionMap); + llvm::Optional createDefined(COFFSymbolRef Sym, std::vector - &ComdatDefs); + &ComdatDefs, + bool &PrevailingComdat); Symbol *createRegular(COFFSymbolRef Sym); Symbol *createUndefined(COFFSymbolRef Sym); std::unique_ptr COFFObj; // List of all chunks defined by this file. This includes both section // chunks and non-section chunks for common symbols. std::vector Chunks; // CodeView debug info sections. std::vector DebugChunks; // Chunks containing symbol table indices of exception handlers. Only used for // 32-bit x86. std::vector SXDataChunks; // Chunks containing symbol table indices of address taken symbols and longjmp // targets. These are not linked into the final binary when /guard:cf is set. std::vector GuardFidChunks; std::vector GuardLJmpChunks; // This vector contains the same chunks as Chunks, but they are // indexed such that you can get a SectionChunk by section index. // Nonexistent section indices are filled with null pointers. // (Because section number is 1-based, the first slot is always a // null pointer.) std::vector SparseChunks; // This vector contains a list of all symbols defined or referenced by this // file. They are indexed such that you can get a Symbol by symbol // index. Nonexistent indices (which are occupied by auxiliary // symbols in the real symbol table) are filled with null pointers. std::vector Symbols; }; // This type represents import library members that contain DLL names // and symbols exported from the DLLs. See Microsoft PE/COFF spec. 7 // for details about the format. class ImportFile : public InputFile { public: explicit ImportFile(MemoryBufferRef M) : InputFile(ImportKind, M) {} static bool classof(const InputFile *F) { return F->kind() == ImportKind; } static std::vector Instances; Symbol *ImpSym = nullptr; Symbol *ThunkSym = nullptr; std::string DLLName; private: void parse() override; public: StringRef ExternalName; const coff_import_header *Hdr; Chunk *Location = nullptr; // We want to eliminate dllimported symbols if no one actually refers them. // These "Live" bits are used to keep track of which import library members // are actually in use. // // If the Live bit is turned off by MarkLive, Writer will ignore dllimported // symbols provided by this import library member. We also track whether the // imported symbol is used separately from whether the thunk is used in order // to avoid creating unnecessary thunks. bool Live = !Config->DoGC; bool ThunkLive = !Config->DoGC; }; // Used for LTO. class BitcodeFile : public InputFile { public: explicit BitcodeFile(MemoryBufferRef M) : InputFile(BitcodeKind, M) {} static bool classof(const InputFile *F) { return F->kind() == BitcodeKind; } ArrayRef getSymbols() { return Symbols; } MachineTypes getMachineType() override; static std::vector Instances; std::unique_ptr Obj; private: void parse() override; std::vector Symbols; }; } // namespace coff std::string toString(const coff::InputFile *File); } // namespace lld #endif Index: vendor/lld/dist-release_70/ELF/LinkerScript.cpp =================================================================== --- vendor/lld/dist-release_70/ELF/LinkerScript.cpp (revision 337638) +++ vendor/lld/dist-release_70/ELF/LinkerScript.cpp (revision 337639) @@ -1,1153 +1,1157 @@ //===- LinkerScript.cpp ---------------------------------------------------===// // // The LLVM Linker // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file contains the parser/evaluator of the linker script. // //===----------------------------------------------------------------------===// #include "LinkerScript.h" #include "Config.h" #include "InputSection.h" #include "OutputSections.h" #include "SymbolTable.h" #include "Symbols.h" #include "SyntheticSections.h" #include "Target.h" #include "Writer.h" #include "lld/Common/Memory.h" #include "lld/Common/Strings.h" #include "lld/Common/Threads.h" #include "llvm/ADT/STLExtras.h" #include "llvm/ADT/StringRef.h" #include "llvm/BinaryFormat/ELF.h" #include "llvm/Support/Casting.h" #include "llvm/Support/Endian.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/FileSystem.h" #include "llvm/Support/Path.h" #include #include #include #include #include #include #include #include using namespace llvm; using namespace llvm::ELF; using namespace llvm::object; using namespace llvm::support::endian; using namespace lld; using namespace lld::elf; LinkerScript *elf::Script; static uint64_t getOutputSectionVA(SectionBase *InputSec, StringRef Loc) { if (OutputSection *OS = InputSec->getOutputSection()) return OS->Addr; error(Loc + ": unable to evaluate expression: input section " + InputSec->Name + " has no output section assigned"); return 0; } uint64_t ExprValue::getValue() const { if (Sec) return alignTo(Sec->getOffset(Val) + getOutputSectionVA(Sec, Loc), Alignment); return alignTo(Val, Alignment); } uint64_t ExprValue::getSecAddr() const { if (Sec) return Sec->getOffset(0) + getOutputSectionVA(Sec, Loc); return 0; } uint64_t ExprValue::getSectionOffset() const { // If the alignment is trivial, we don't have to compute the full // value to know the offset. This allows this function to succeed in // cases where the output section is not yet known. if (Alignment == 1 && (!Sec || !Sec->getOutputSection())) return Val; return getValue() - getSecAddr(); } OutputSection *LinkerScript::createOutputSection(StringRef Name, StringRef Location) { OutputSection *&SecRef = NameToOutputSection[Name]; OutputSection *Sec; if (SecRef && SecRef->Location.empty()) { // There was a forward reference. Sec = SecRef; } else { Sec = make(Name, SHT_NOBITS, 0); if (!SecRef) SecRef = Sec; } Sec->Location = Location; return Sec; } OutputSection *LinkerScript::getOrCreateOutputSection(StringRef Name) { OutputSection *&CmdRef = NameToOutputSection[Name]; if (!CmdRef) CmdRef = make(Name, SHT_PROGBITS, 0); return CmdRef; } // Expands the memory region by the specified size. static void expandMemoryRegion(MemoryRegion *MemRegion, uint64_t Size, StringRef RegionName, StringRef SecName) { MemRegion->CurPos += Size; uint64_t NewSize = MemRegion->CurPos - MemRegion->Origin; if (NewSize > MemRegion->Length) error("section '" + SecName + "' will not fit in region '" + RegionName + "': overflowed by " + Twine(NewSize - MemRegion->Length) + " bytes"); } void LinkerScript::expandMemoryRegions(uint64_t Size) { if (Ctx->MemRegion) expandMemoryRegion(Ctx->MemRegion, Size, Ctx->MemRegion->Name, Ctx->OutSec->Name); - if (Ctx->LMARegion) + // Only expand the LMARegion if it is different from MemRegion. + if (Ctx->LMARegion && Ctx->MemRegion != Ctx->LMARegion) expandMemoryRegion(Ctx->LMARegion, Size, Ctx->LMARegion->Name, Ctx->OutSec->Name); } void LinkerScript::expandOutputSection(uint64_t Size) { Ctx->OutSec->Size += Size; expandMemoryRegions(Size); } void LinkerScript::setDot(Expr E, const Twine &Loc, bool InSec) { uint64_t Val = E().getValue(); if (Val < Dot && InSec) error(Loc + ": unable to move location counter backward for: " + Ctx->OutSec->Name); // Update to location counter means update to section size. if (InSec) expandOutputSection(Val - Dot); else expandMemoryRegions(Val - Dot); Dot = Val; } // Used for handling linker symbol assignments, for both finalizing // their values and doing early declarations. Returns true if symbol // should be defined from linker script. static bool shouldDefineSym(SymbolAssignment *Cmd) { if (Cmd->Name == ".") return false; if (!Cmd->Provide) return true; // If a symbol was in PROVIDE(), we need to define it only // when it is a referenced undefined symbol. Symbol *B = Symtab->find(Cmd->Name); if (B && !B->isDefined()) return true; return false; } // This function is called from processSectionCommands, // while we are fixing the output section layout. void LinkerScript::addSymbol(SymbolAssignment *Cmd) { if (!shouldDefineSym(Cmd)) return; // Define a symbol. Symbol *Sym; uint8_t Visibility = Cmd->Hidden ? STV_HIDDEN : STV_DEFAULT; std::tie(Sym, std::ignore) = Symtab->insert(Cmd->Name, /*Type*/ 0, Visibility, /*CanOmitFromDynSym*/ false, /*File*/ nullptr); ExprValue Value = Cmd->Expression(); SectionBase *Sec = Value.isAbsolute() ? nullptr : Value.Sec; // When this function is called, section addresses have not been // fixed yet. So, we may or may not know the value of the RHS // expression. // // For example, if an expression is `x = 42`, we know x is always 42. // However, if an expression is `x = .`, there's no way to know its // value at the moment. // // We want to set symbol values early if we can. This allows us to // use symbols as variables in linker scripts. Doing so allows us to // write expressions like this: `alignment = 16; . = ALIGN(., alignment)`. uint64_t SymValue = Value.Sec ? 0 : Value.getValue(); replaceSymbol(Sym, nullptr, Cmd->Name, STB_GLOBAL, Visibility, STT_NOTYPE, SymValue, 0, Sec); Cmd->Sym = cast(Sym); } // This function is called from LinkerScript::declareSymbols. // It creates a placeholder symbol if needed. static void declareSymbol(SymbolAssignment *Cmd) { if (!shouldDefineSym(Cmd)) return; // We can't calculate final value right now. Symbol *Sym; uint8_t Visibility = Cmd->Hidden ? STV_HIDDEN : STV_DEFAULT; std::tie(Sym, std::ignore) = Symtab->insert(Cmd->Name, /*Type*/ 0, Visibility, /*CanOmitFromDynSym*/ false, /*File*/ nullptr); replaceSymbol(Sym, nullptr, Cmd->Name, STB_GLOBAL, Visibility, STT_NOTYPE, 0, 0, nullptr); Cmd->Sym = cast(Sym); Cmd->Provide = false; } // This method is used to handle INSERT AFTER statement. Here we rebuild // the list of script commands to mix sections inserted into. void LinkerScript::processInsertCommands() { std::vector V; auto Insert = [&](std::vector &From) { V.insert(V.end(), From.begin(), From.end()); From.clear(); }; for (BaseCommand *Base : SectionCommands) { if (auto *OS = dyn_cast(Base)) { Insert(InsertBeforeCommands[OS->Name]); V.push_back(Base); Insert(InsertAfterCommands[OS->Name]); continue; } V.push_back(Base); } for (auto &Cmds : {InsertBeforeCommands, InsertAfterCommands}) for (const std::pair> &P : Cmds) if (!P.second.empty()) error("unable to INSERT AFTER/BEFORE " + P.first + ": section not defined"); SectionCommands = std::move(V); } // Symbols defined in script should not be inlined by LTO. At the same time // we don't know their final values until late stages of link. Here we scan // over symbol assignment commands and create placeholder symbols if needed. void LinkerScript::declareSymbols() { assert(!Ctx); for (BaseCommand *Base : SectionCommands) { if (auto *Cmd = dyn_cast(Base)) { declareSymbol(Cmd); continue; } // If the output section directive has constraints, // we can't say for sure if it is going to be included or not. // Skip such sections for now. Improve the checks if we ever // need symbols from that sections to be declared early. auto *Sec = cast(Base); if (Sec->Constraint != ConstraintKind::NoConstraint) continue; for (BaseCommand *Base2 : Sec->SectionCommands) if (auto *Cmd = dyn_cast(Base2)) declareSymbol(Cmd); } } // This function is called from assignAddresses, while we are // fixing the output section addresses. This function is supposed // to set the final value for a given symbol assignment. void LinkerScript::assignSymbol(SymbolAssignment *Cmd, bool InSec) { if (Cmd->Name == ".") { setDot(Cmd->Expression, Cmd->Location, InSec); return; } if (!Cmd->Sym) return; ExprValue V = Cmd->Expression(); if (V.isAbsolute()) { Cmd->Sym->Section = nullptr; Cmd->Sym->Value = V.getValue(); } else { Cmd->Sym->Section = V.Sec; Cmd->Sym->Value = V.getSectionOffset(); } } static std::string getFilename(InputFile *File) { if (!File) return ""; if (File->ArchiveName.empty()) return File->getName(); return (File->ArchiveName + "(" + File->getName() + ")").str(); } bool LinkerScript::shouldKeep(InputSectionBase *S) { if (KeptSections.empty()) return false; std::string Filename = getFilename(S->File); for (InputSectionDescription *ID : KeptSections) if (ID->FilePat.match(Filename)) for (SectionPattern &P : ID->SectionPatterns) if (P.SectionPat.match(S->Name)) return true; return false; } // A helper function for the SORT() command. static std::function getComparator(SortSectionPolicy K) { switch (K) { case SortSectionPolicy::Alignment: return [](InputSectionBase *A, InputSectionBase *B) { // ">" is not a mistake. Sections with larger alignments are placed // before sections with smaller alignments in order to reduce the // amount of padding necessary. This is compatible with GNU. return A->Alignment > B->Alignment; }; case SortSectionPolicy::Name: return [](InputSectionBase *A, InputSectionBase *B) { return A->Name < B->Name; }; case SortSectionPolicy::Priority: return [](InputSectionBase *A, InputSectionBase *B) { return getPriority(A->Name) < getPriority(B->Name); }; default: llvm_unreachable("unknown sort policy"); } } // A helper function for the SORT() command. static bool matchConstraints(ArrayRef Sections, ConstraintKind Kind) { if (Kind == ConstraintKind::NoConstraint) return true; bool IsRW = llvm::any_of( Sections, [](InputSection *Sec) { return Sec->Flags & SHF_WRITE; }); return (IsRW && Kind == ConstraintKind::ReadWrite) || (!IsRW && Kind == ConstraintKind::ReadOnly); } static void sortSections(MutableArrayRef Vec, SortSectionPolicy K) { if (K != SortSectionPolicy::Default && K != SortSectionPolicy::None) std::stable_sort(Vec.begin(), Vec.end(), getComparator(K)); } // Sort sections as instructed by SORT-family commands and --sort-section // option. Because SORT-family commands can be nested at most two depth // (e.g. SORT_BY_NAME(SORT_BY_ALIGNMENT(.text.*))) and because the command // line option is respected even if a SORT command is given, the exact // behavior we have here is a bit complicated. Here are the rules. // // 1. If two SORT commands are given, --sort-section is ignored. // 2. If one SORT command is given, and if it is not SORT_NONE, // --sort-section is handled as an inner SORT command. // 3. If one SORT command is given, and if it is SORT_NONE, don't sort. // 4. If no SORT command is given, sort according to --sort-section. static void sortInputSections(MutableArrayRef Vec, const SectionPattern &Pat) { if (Pat.SortOuter == SortSectionPolicy::None) return; if (Pat.SortInner == SortSectionPolicy::Default) sortSections(Vec, Config->SortSection); else sortSections(Vec, Pat.SortInner); sortSections(Vec, Pat.SortOuter); } // Compute and remember which sections the InputSectionDescription matches. std::vector LinkerScript::computeInputSections(const InputSectionDescription *Cmd) { std::vector Ret; // Collects all sections that satisfy constraints of Cmd. for (const SectionPattern &Pat : Cmd->SectionPatterns) { size_t SizeBefore = Ret.size(); for (InputSectionBase *Sec : InputSections) { if (!Sec->Live || Sec->Assigned) continue; // For -emit-relocs we have to ignore entries like // .rela.dyn : { *(.rela.data) } // which are common because they are in the default bfd script. // We do not ignore SHT_REL[A] linker-synthesized sections here because // want to support scripts that do custom layout for them. if (auto *IS = dyn_cast(Sec)) if (IS->getRelocatedSection()) continue; std::string Filename = getFilename(Sec->File); if (!Cmd->FilePat.match(Filename) || Pat.ExcludedFilePat.match(Filename) || !Pat.SectionPat.match(Sec->Name)) continue; // It is safe to assume that Sec is an InputSection // because mergeable or EH input sections have already been // handled and eliminated. Ret.push_back(cast(Sec)); Sec->Assigned = true; } sortInputSections(MutableArrayRef(Ret).slice(SizeBefore), Pat); } return Ret; } void LinkerScript::discard(ArrayRef V) { for (InputSection *S : V) { if (S == InX::ShStrTab || S == InX::Dynamic || S == InX::DynSymTab || S == InX::DynStrTab || S == InX::RelaPlt || S == InX::RelaDyn || S == InX::RelrDyn) error("discarding " + S->Name + " section is not allowed"); // You can discard .hash and .gnu.hash sections by linker scripts. Since // they are synthesized sections, we need to handle them differently than // other regular sections. if (S == InX::GnuHashTab) InX::GnuHashTab = nullptr; if (S == InX::HashTab) InX::HashTab = nullptr; S->Assigned = false; S->Live = false; discard(S->DependentSections); } } std::vector LinkerScript::createInputSectionList(OutputSection &OutCmd) { std::vector Ret; for (BaseCommand *Base : OutCmd.SectionCommands) { if (auto *Cmd = dyn_cast(Base)) { Cmd->Sections = computeInputSections(Cmd); Ret.insert(Ret.end(), Cmd->Sections.begin(), Cmd->Sections.end()); } } return Ret; } void LinkerScript::processSectionCommands() { // A symbol can be assigned before any section is mentioned in the linker // script. In an DSO, the symbol values are addresses, so the only important // section values are: // * SHN_UNDEF // * SHN_ABS // * Any value meaning a regular section. // To handle that, create a dummy aether section that fills the void before // the linker scripts switches to another section. It has an index of one // which will map to whatever the first actual section is. Aether = make("", 0, SHF_ALLOC); Aether->SectionIndex = 1; // Ctx captures the local AddressState and makes it accessible deliberately. // This is needed as there are some cases where we cannot just // thread the current state through to a lambda function created by the // script parser. auto Deleter = make_unique(); Ctx = Deleter.get(); Ctx->OutSec = Aether; size_t I = 0; // Add input sections to output sections. for (BaseCommand *Base : SectionCommands) { // Handle symbol assignments outside of any output section. if (auto *Cmd = dyn_cast(Base)) { addSymbol(Cmd); continue; } if (auto *Sec = dyn_cast(Base)) { std::vector V = createInputSectionList(*Sec); // The output section name `/DISCARD/' is special. // Any input section assigned to it is discarded. if (Sec->Name == "/DISCARD/") { discard(V); Sec->SectionCommands.clear(); continue; } // This is for ONLY_IF_RO and ONLY_IF_RW. An output section directive // ".foo : ONLY_IF_R[OW] { ... }" is handled only if all member input // sections satisfy a given constraint. If not, a directive is handled // as if it wasn't present from the beginning. // // Because we'll iterate over SectionCommands many more times, the easy // way to "make it as if it wasn't present" is to make it empty. if (!matchConstraints(V, Sec->Constraint)) { for (InputSectionBase *S : V) S->Assigned = false; Sec->SectionCommands.clear(); continue; } // A directive may contain symbol definitions like this: // ".foo : { ...; bar = .; }". Handle them. for (BaseCommand *Base : Sec->SectionCommands) if (auto *OutCmd = dyn_cast(Base)) addSymbol(OutCmd); // Handle subalign (e.g. ".foo : SUBALIGN(32) { ... }"). If subalign // is given, input sections are aligned to that value, whether the // given value is larger or smaller than the original section alignment. if (Sec->SubalignExpr) { uint32_t Subalign = Sec->SubalignExpr().getValue(); for (InputSectionBase *S : V) S->Alignment = Subalign; } // Add input sections to an output section. for (InputSection *S : V) Sec->addSection(S); Sec->SectionIndex = I++; if (Sec->Noload) Sec->Type = SHT_NOBITS; if (Sec->NonAlloc) Sec->Flags &= ~(uint64_t)SHF_ALLOC; } } Ctx = nullptr; } static OutputSection *findByName(ArrayRef Vec, StringRef Name) { for (BaseCommand *Base : Vec) if (auto *Sec = dyn_cast(Base)) if (Sec->Name == Name) return Sec; return nullptr; } static OutputSection *createSection(InputSectionBase *IS, StringRef OutsecName) { OutputSection *Sec = Script->createOutputSection(OutsecName, ""); Sec->addSection(cast(IS)); return Sec; } static OutputSection *addInputSec(StringMap &Map, InputSectionBase *IS, StringRef OutsecName) { // Sections with SHT_GROUP or SHF_GROUP attributes reach here only when the -r // option is given. A section with SHT_GROUP defines a "section group", and // its members have SHF_GROUP attribute. Usually these flags have already been // stripped by InputFiles.cpp as section groups are processed and uniquified. // However, for the -r option, we want to pass through all section groups // as-is because adding/removing members or merging them with other groups // change their semantics. if (IS->Type == SHT_GROUP || (IS->Flags & SHF_GROUP)) return createSection(IS, OutsecName); // Imagine .zed : { *(.foo) *(.bar) } script. Both foo and bar may have // relocation sections .rela.foo and .rela.bar for example. Most tools do // not allow multiple REL[A] sections for output section. Hence we // should combine these relocation sections into single output. // We skip synthetic sections because it can be .rela.dyn/.rela.plt or any // other REL[A] sections created by linker itself. if (!isa(IS) && (IS->Type == SHT_REL || IS->Type == SHT_RELA)) { auto *Sec = cast(IS); OutputSection *Out = Sec->getRelocatedSection()->getOutputSection(); if (Out->RelocationSection) { Out->RelocationSection->addSection(Sec); return nullptr; } Out->RelocationSection = createSection(IS, OutsecName); return Out->RelocationSection; } // When control reaches here, mergeable sections have already been merged into // synthetic sections. For relocatable case we want to create one output // section per syntetic section so that they have a valid sh_entsize. if (Config->Relocatable && (IS->Flags & SHF_MERGE)) return createSection(IS, OutsecName); // The ELF spec just says // ---------------------------------------------------------------- // In the first phase, input sections that match in name, type and // attribute flags should be concatenated into single sections. // ---------------------------------------------------------------- // // However, it is clear that at least some flags have to be ignored for // section merging. At the very least SHF_GROUP and SHF_COMPRESSED have to be // ignored. We should not have two output .text sections just because one was // in a group and another was not for example. // // It also seems that wording was a late addition and didn't get the // necessary scrutiny. // // Merging sections with different flags is expected by some users. One // reason is that if one file has // // int *const bar __attribute__((section(".foo"))) = (int *)0; // // gcc with -fPIC will produce a read only .foo section. But if another // file has // // int zed; // int *const bar __attribute__((section(".foo"))) = (int *)&zed; // // gcc with -fPIC will produce a read write section. // // Last but not least, when using linker script the merge rules are forced by // the script. Unfortunately, linker scripts are name based. This means that // expressions like *(.foo*) can refer to multiple input sections with // different flags. We cannot put them in different output sections or we // would produce wrong results for // // start = .; *(.foo.*) end = .; *(.bar) // // and a mapping of .foo1 and .bar1 to one section and .foo2 and .bar2 to // another. The problem is that there is no way to layout those output // sections such that the .foo sections are the only thing between the start // and end symbols. // // Given the above issues, we instead merge sections by name and error on // incompatible types and flags. OutputSection *&Sec = Map[OutsecName]; if (Sec) { Sec->addSection(cast(IS)); return nullptr; } Sec = createSection(IS, OutsecName); return Sec; } // Add sections that didn't match any sections command. void LinkerScript::addOrphanSections() { unsigned End = SectionCommands.size(); StringMap Map; std::vector V; auto Add = [&](InputSectionBase *S) { if (!S->Live || S->Parent) return; StringRef Name = getOutputSectionName(S); if (Config->OrphanHandling == OrphanHandlingPolicy::Error) error(toString(S) + " is being placed in '" + Name + "'"); else if (Config->OrphanHandling == OrphanHandlingPolicy::Warn) warn(toString(S) + " is being placed in '" + Name + "'"); if (OutputSection *Sec = findByName(makeArrayRef(SectionCommands).slice(0, End), Name)) { Sec->addSection(cast(S)); return; } if (OutputSection *OS = addInputSec(Map, S, Name)) V.push_back(OS); assert(S->getOutputSection()->SectionIndex == UINT32_MAX); }; // For futher --emit-reloc handling code we need target output section // to be created before we create relocation output section, so we want // to create target sections first. We do not want priority handling // for synthetic sections because them are special. for (InputSectionBase *IS : InputSections) { if (auto *Sec = dyn_cast(IS)) if (InputSectionBase *Rel = Sec->getRelocatedSection()) if (auto *RelIS = dyn_cast_or_null(Rel->Parent)) Add(RelIS); Add(IS); } // If no SECTIONS command was given, we should insert sections commands // before others, so that we can handle scripts which refers them, // for example: "foo = ABSOLUTE(ADDR(.text)));". // When SECTIONS command is present we just add all orphans to the end. if (HasSectionsCommand) SectionCommands.insert(SectionCommands.end(), V.begin(), V.end()); else SectionCommands.insert(SectionCommands.begin(), V.begin(), V.end()); } uint64_t LinkerScript::advance(uint64_t Size, unsigned Alignment) { bool IsTbss = (Ctx->OutSec->Flags & SHF_TLS) && Ctx->OutSec->Type == SHT_NOBITS; uint64_t Start = IsTbss ? Dot + Ctx->ThreadBssOffset : Dot; Start = alignTo(Start, Alignment); uint64_t End = Start + Size; if (IsTbss) Ctx->ThreadBssOffset = End - Dot; else Dot = End; return End; } void LinkerScript::output(InputSection *S) { uint64_t Before = advance(0, 1); uint64_t Pos = advance(S->getSize(), S->Alignment); S->OutSecOff = Pos - S->getSize() - Ctx->OutSec->Addr; // Update output section size after adding each section. This is so that // SIZEOF works correctly in the case below: // .foo { *(.aaa) a = SIZEOF(.foo); *(.bbb) } expandOutputSection(Pos - Before); } void LinkerScript::switchTo(OutputSection *Sec) { Ctx->OutSec = Sec; uint64_t Before = advance(0, 1); Ctx->OutSec->Addr = advance(0, Ctx->OutSec->Alignment); expandMemoryRegions(Ctx->OutSec->Addr - Before); } // This function searches for a memory region to place the given output // section in. If found, a pointer to the appropriate memory region is // returned. Otherwise, a nullptr is returned. MemoryRegion *LinkerScript::findMemoryRegion(OutputSection *Sec) { // If a memory region name was specified in the output section command, // then try to find that region first. if (!Sec->MemoryRegionName.empty()) { if (MemoryRegion *M = MemoryRegions.lookup(Sec->MemoryRegionName)) return M; error("memory region '" + Sec->MemoryRegionName + "' not declared"); return nullptr; } // If at least one memory region is defined, all sections must // belong to some memory region. Otherwise, we don't need to do // anything for memory regions. if (MemoryRegions.empty()) return nullptr; // See if a region can be found by matching section flags. for (auto &Pair : MemoryRegions) { MemoryRegion *M = Pair.second; if ((M->Flags & Sec->Flags) && (M->NegFlags & Sec->Flags) == 0) return M; } // Otherwise, no suitable region was found. if (Sec->Flags & SHF_ALLOC) error("no memory region specified for section '" + Sec->Name + "'"); return nullptr; } +static OutputSection *findFirstSection(PhdrEntry *Load) { + for (OutputSection *Sec : OutputSections) + if (Sec->PtLoad == Load) + return Sec; + return nullptr; +} + // This function assigns offsets to input sections and an output section // for a single sections command (e.g. ".text { *(.text); }"). void LinkerScript::assignOffsets(OutputSection *Sec) { if (!(Sec->Flags & SHF_ALLOC)) Dot = 0; else if (Sec->AddrExpr) setDot(Sec->AddrExpr, Sec->Location, false); Ctx->MemRegion = Sec->MemRegion; Ctx->LMARegion = Sec->LMARegion; if (Ctx->MemRegion) Dot = Ctx->MemRegion->CurPos; switchTo(Sec); if (Sec->LMAExpr) Ctx->LMAOffset = Sec->LMAExpr().getValue() - Dot; if (MemoryRegion *MR = Sec->LMARegion) Ctx->LMAOffset = MR->CurPos - Dot; // If neither AT nor AT> is specified for an allocatable section, the linker // will set the LMA such that the difference between VMA and LMA for the // section is the same as the preceding output section in the same region // https://sourceware.org/binutils/docs-2.20/ld/Output-Section-LMA.html + // This, however, should only be done by the first "non-header" section + // in the segment. if (PhdrEntry *L = Ctx->OutSec->PtLoad) - L->LMAOffset = Ctx->LMAOffset; + if (Sec == findFirstSection(L)) + L->LMAOffset = Ctx->LMAOffset; // We can call this method multiple times during the creation of // thunks and want to start over calculation each time. Sec->Size = 0; // We visited SectionsCommands from processSectionCommands to // layout sections. Now, we visit SectionsCommands again to fix // section offsets. for (BaseCommand *Base : Sec->SectionCommands) { // This handles the assignments to symbol or to the dot. if (auto *Cmd = dyn_cast(Base)) { Cmd->Addr = Dot; assignSymbol(Cmd, true); Cmd->Size = Dot - Cmd->Addr; continue; } // Handle BYTE(), SHORT(), LONG(), or QUAD(). if (auto *Cmd = dyn_cast(Base)) { Cmd->Offset = Dot - Ctx->OutSec->Addr; Dot += Cmd->Size; expandOutputSection(Cmd->Size); continue; } // Handle a single input section description command. // It calculates and assigns the offsets for each section and also // updates the output section size. auto *Cmd = cast(Base); for (InputSection *Sec : Cmd->Sections) { // We tentatively added all synthetic sections at the beginning and // removed empty ones afterwards (because there is no way to know // whether they were going be empty or not other than actually running // linker scripts.) We need to ignore remains of empty sections. if (auto *S = dyn_cast(Sec)) if (S->empty()) continue; if (!Sec->Live) continue; assert(Ctx->OutSec == Sec->getParent()); output(Sec); } } } static bool isDiscardable(OutputSection &Sec) { // We do not remove empty sections that are explicitly // assigned to any segment. if (!Sec.Phdrs.empty()) return false; // We do not want to remove sections that reference symbols in address and // other expressions. We add script symbols as undefined, and want to ensure // all of them are defined in the output, hence have to keep them. if (Sec.ExpressionsUseSymbols) return false; for (BaseCommand *Base : Sec.SectionCommands) { if (auto Cmd = dyn_cast(Base)) // Don't create empty output sections just for unreferenced PROVIDE // symbols. if (Cmd->Name != "." && !Cmd->Sym) continue; if (!isa(*Base)) return false; } return true; } void LinkerScript::adjustSectionsBeforeSorting() { // If the output section contains only symbol assignments, create a // corresponding output section. The issue is what to do with linker script // like ".foo : { symbol = 42; }". One option would be to convert it to // "symbol = 42;". That is, move the symbol out of the empty section // description. That seems to be what bfd does for this simple case. The // problem is that this is not completely general. bfd will give up and // create a dummy section too if there is a ". = . + 1" inside the section // for example. // Given that we want to create the section, we have to worry what impact // it will have on the link. For example, if we just create a section with // 0 for flags, it would change which PT_LOADs are created. // We could remember that particular section is dummy and ignore it in // other parts of the linker, but unfortunately there are quite a few places // that would need to change: // * The program header creation. // * The orphan section placement. // * The address assignment. // The other option is to pick flags that minimize the impact the section // will have on the rest of the linker. That is why we copy the flags from // the previous sections. Only a few flags are needed to keep the impact low. uint64_t Flags = SHF_ALLOC; for (BaseCommand *&Cmd : SectionCommands) { auto *Sec = dyn_cast(Cmd); if (!Sec) continue; // Handle align (e.g. ".foo : ALIGN(16) { ... }"). if (Sec->AlignExpr) Sec->Alignment = std::max(Sec->Alignment, Sec->AlignExpr().getValue()); // A live output section means that some input section was added to it. It // might have been removed (if it was empty synthetic section), but we at // least know the flags. if (Sec->Live) Flags = Sec->Flags; // We do not want to keep any special flags for output section // in case it is empty. bool IsEmpty = getInputSections(Sec).empty(); if (IsEmpty) Sec->Flags = Flags & (SHF_ALLOC | SHF_WRITE | SHF_EXECINSTR); if (IsEmpty && isDiscardable(*Sec)) { Sec->Live = false; Cmd = nullptr; } } // It is common practice to use very generic linker scripts. So for any // given run some of the output sections in the script will be empty. // We could create corresponding empty output sections, but that would // clutter the output. // We instead remove trivially empty sections. The bfd linker seems even // more aggressive at removing them. llvm::erase_if(SectionCommands, [&](BaseCommand *Base) { return !Base; }); } void LinkerScript::adjustSectionsAfterSorting() { // Try and find an appropriate memory region to assign offsets in. for (BaseCommand *Base : SectionCommands) { if (auto *Sec = dyn_cast(Base)) { if (!Sec->LMARegionName.empty()) { if (MemoryRegion *M = MemoryRegions.lookup(Sec->LMARegionName)) Sec->LMARegion = M; else error("memory region '" + Sec->LMARegionName + "' not declared"); } Sec->MemRegion = findMemoryRegion(Sec); } } // If output section command doesn't specify any segments, // and we haven't previously assigned any section to segment, // then we simply assign section to the very first load segment. // Below is an example of such linker script: // PHDRS { seg PT_LOAD; } // SECTIONS { .aaa : { *(.aaa) } } std::vector DefPhdrs; auto FirstPtLoad = llvm::find_if(PhdrsCommands, [](const PhdrsCommand &Cmd) { return Cmd.Type == PT_LOAD; }); if (FirstPtLoad != PhdrsCommands.end()) DefPhdrs.push_back(FirstPtLoad->Name); // Walk the commands and propagate the program headers to commands that don't // explicitly specify them. for (BaseCommand *Base : SectionCommands) { auto *Sec = dyn_cast(Base); if (!Sec) continue; if (Sec->Phdrs.empty()) { // To match the bfd linker script behaviour, only propagate program // headers to sections that are allocated. if (Sec->Flags & SHF_ALLOC) Sec->Phdrs = DefPhdrs; } else { DefPhdrs = Sec->Phdrs; } } -} - -static OutputSection *findFirstSection(PhdrEntry *Load) { - for (OutputSection *Sec : OutputSections) - if (Sec->PtLoad == Load) - return Sec; - return nullptr; } static uint64_t computeBase(uint64_t Min, bool AllocateHeaders) { // If there is no SECTIONS or if the linkerscript is explicit about program // headers, do our best to allocate them. if (!Script->HasSectionsCommand || AllocateHeaders) return 0; // Otherwise only allocate program headers if that would not add a page. return alignDown(Min, Config->MaxPageSize); } // Try to find an address for the file and program headers output sections, // which were unconditionally added to the first PT_LOAD segment earlier. // // When using the default layout, we check if the headers fit below the first // allocated section. When using a linker script, we also check if the headers // are covered by the output section. This allows omitting the headers by not // leaving enough space for them in the linker script; this pattern is common // in embedded systems. // // If there isn't enough space for these sections, we'll remove them from the // PT_LOAD segment, and we'll also remove the PT_PHDR segment. void LinkerScript::allocateHeaders(std::vector &Phdrs) { uint64_t Min = std::numeric_limits::max(); for (OutputSection *Sec : OutputSections) if (Sec->Flags & SHF_ALLOC) Min = std::min(Min, Sec->Addr); auto It = llvm::find_if( Phdrs, [](const PhdrEntry *E) { return E->p_type == PT_LOAD; }); if (It == Phdrs.end()) return; PhdrEntry *FirstPTLoad = *It; bool HasExplicitHeaders = llvm::any_of(PhdrsCommands, [](const PhdrsCommand &Cmd) { return Cmd.HasPhdrs || Cmd.HasFilehdr; }); uint64_t HeaderSize = getHeaderSize(); if (HeaderSize <= Min - computeBase(Min, HasExplicitHeaders)) { Min = alignDown(Min - HeaderSize, Config->MaxPageSize); Out::ElfHeader->Addr = Min; Out::ProgramHeaders->Addr = Min + Out::ElfHeader->Size; return; } // Error if we were explicitly asked to allocate headers. if (HasExplicitHeaders) error("could not allocate headers"); Out::ElfHeader->PtLoad = nullptr; Out::ProgramHeaders->PtLoad = nullptr; FirstPTLoad->FirstSec = findFirstSection(FirstPTLoad); llvm::erase_if(Phdrs, [](const PhdrEntry *E) { return E->p_type == PT_PHDR; }); } LinkerScript::AddressState::AddressState() { for (auto &MRI : Script->MemoryRegions) { MemoryRegion *MR = MRI.second; MR->CurPos = MR->Origin; } } static uint64_t getInitialDot() { // By default linker scripts use an initial value of 0 for '.', // but prefer -image-base if set. if (Script->HasSectionsCommand) return Config->ImageBase ? *Config->ImageBase : 0; uint64_t StartAddr = UINT64_MAX; // The Sections with -T
have been sorted in order of ascending // address. We must lower StartAddr if the lowest -T
as // calls to setDot() must be monotonically increasing. for (auto &KV : Config->SectionStartMap) StartAddr = std::min(StartAddr, KV.second); return std::min(StartAddr, Target->getImageBase() + elf::getHeaderSize()); } // Here we assign addresses as instructed by linker script SECTIONS // sub-commands. Doing that allows us to use final VA values, so here // we also handle rest commands like symbol assignments and ASSERTs. void LinkerScript::assignAddresses() { Dot = getInitialDot(); auto Deleter = make_unique(); Ctx = Deleter.get(); ErrorOnMissingSection = true; switchTo(Aether); for (BaseCommand *Base : SectionCommands) { if (auto *Cmd = dyn_cast(Base)) { Cmd->Addr = Dot; assignSymbol(Cmd, false); Cmd->Size = Dot - Cmd->Addr; continue; } assignOffsets(cast(Base)); } Ctx = nullptr; } // Creates program headers as instructed by PHDRS linker script command. std::vector LinkerScript::createPhdrs() { std::vector Ret; // Process PHDRS and FILEHDR keywords because they are not // real output sections and cannot be added in the following loop. for (const PhdrsCommand &Cmd : PhdrsCommands) { PhdrEntry *Phdr = make(Cmd.Type, Cmd.Flags ? *Cmd.Flags : PF_R); if (Cmd.HasFilehdr) Phdr->add(Out::ElfHeader); if (Cmd.HasPhdrs) Phdr->add(Out::ProgramHeaders); if (Cmd.LMAExpr) { Phdr->p_paddr = Cmd.LMAExpr().getValue(); Phdr->HasLMA = true; } Ret.push_back(Phdr); } // Add output sections to program headers. for (OutputSection *Sec : OutputSections) { // Assign headers specified by linker script for (size_t Id : getPhdrIndices(Sec)) { Ret[Id]->add(Sec); if (!PhdrsCommands[Id].Flags.hasValue()) Ret[Id]->p_flags |= Sec->getPhdrFlags(); } } return Ret; } // Returns true if we should emit an .interp section. // // We usually do. But if PHDRS commands are given, and // no PT_INTERP is there, there's no place to emit an // .interp, so we don't do that in that case. bool LinkerScript::needsInterpSection() { if (PhdrsCommands.empty()) return true; for (PhdrsCommand &Cmd : PhdrsCommands) if (Cmd.Type == PT_INTERP) return true; return false; } ExprValue LinkerScript::getSymbolValue(StringRef Name, const Twine &Loc) { if (Name == ".") { if (Ctx) return {Ctx->OutSec, false, Dot - Ctx->OutSec->Addr, Loc}; error(Loc + ": unable to get location counter value"); return 0; } if (Symbol *Sym = Symtab->find(Name)) { if (auto *DS = dyn_cast(Sym)) return {DS->Section, false, DS->Value, Loc}; if (isa(Sym)) if (!ErrorOnMissingSection) return {nullptr, false, 0, Loc}; } error(Loc + ": symbol not found: " + Name); return 0; } // Returns the index of the segment named Name. static Optional getPhdrIndex(ArrayRef Vec, StringRef Name) { for (size_t I = 0; I < Vec.size(); ++I) if (Vec[I].Name == Name) return I; return None; } // Returns indices of ELF headers containing specific section. Each index is a // zero based number of ELF header listed within PHDRS {} script block. std::vector LinkerScript::getPhdrIndices(OutputSection *Cmd) { std::vector Ret; for (StringRef S : Cmd->Phdrs) { if (Optional Idx = getPhdrIndex(PhdrsCommands, S)) Ret.push_back(*Idx); else if (S != "NONE") error(Cmd->Location + ": section header '" + S + "' is not listed in PHDRS"); } return Ret; } Index: vendor/lld/dist-release_70/ELF/Writer.cpp =================================================================== --- vendor/lld/dist-release_70/ELF/Writer.cpp (revision 337638) +++ vendor/lld/dist-release_70/ELF/Writer.cpp (revision 337639) @@ -1,2404 +1,2406 @@ //===- Writer.cpp ---------------------------------------------------------===// // // The LLVM Linker // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// #include "Writer.h" #include "AArch64ErrataFix.h" #include "CallGraphSort.h" #include "Config.h" #include "Filesystem.h" #include "LinkerScript.h" #include "MapFile.h" #include "OutputSections.h" #include "Relocations.h" #include "SymbolTable.h" #include "Symbols.h" #include "SyntheticSections.h" #include "Target.h" #include "lld/Common/Memory.h" #include "lld/Common/Strings.h" #include "lld/Common/Threads.h" #include "llvm/ADT/StringMap.h" #include "llvm/ADT/StringSwitch.h" #include using namespace llvm; using namespace llvm::ELF; using namespace llvm::object; using namespace llvm::support; using namespace llvm::support::endian; using namespace lld; using namespace lld::elf; namespace { // The writer writes a SymbolTable result to a file. template class Writer { public: Writer() : Buffer(errorHandler().OutputBuffer) {} typedef typename ELFT::Shdr Elf_Shdr; typedef typename ELFT::Ehdr Elf_Ehdr; typedef typename ELFT::Phdr Elf_Phdr; void run(); private: void copyLocalSymbols(); void addSectionSymbols(); void forEachRelSec(llvm::function_ref Fn); void sortSections(); void resolveShfLinkOrder(); void sortInputSections(); void finalizeSections(); void setReservedSymbolSections(); std::vector createPhdrs(); void removeEmptyPTLoad(); void addPtArmExid(std::vector &Phdrs); void assignFileOffsets(); void assignFileOffsetsBinary(); void setPhdrs(); void checkSections(); void fixSectionAlignments(); void openFile(); void writeTrapInstr(); void writeHeader(); void writeSections(); void writeSectionsBinary(); void writeBuildId(); std::unique_ptr &Buffer; void addRelIpltSymbols(); void addStartEndSymbols(); void addStartStopSymbols(OutputSection *Sec); uint64_t getEntryAddr(); std::vector Phdrs; uint64_t FileSize; uint64_t SectionHeaderOff; }; } // anonymous namespace static bool isSectionPrefix(StringRef Prefix, StringRef Name) { return Name.startswith(Prefix) || Name == Prefix.drop_back(); } StringRef elf::getOutputSectionName(const InputSectionBase *S) { if (Config->Relocatable) return S->Name; // This is for --emit-relocs. If .text.foo is emitted as .text.bar, we want // to emit .rela.text.foo as .rela.text.bar for consistency (this is not // technically required, but not doing it is odd). This code guarantees that. if (auto *IS = dyn_cast(S)) { if (InputSectionBase *Rel = IS->getRelocatedSection()) { OutputSection *Out = Rel->getOutputSection(); if (S->Type == SHT_RELA) return Saver.save(".rela" + Out->Name); return Saver.save(".rel" + Out->Name); } } // This check is for -z keep-text-section-prefix. This option separates text // sections with prefix ".text.hot", ".text.unlikely", ".text.startup" or // ".text.exit". // When enabled, this allows identifying the hot code region (.text.hot) in // the final binary which can be selectively mapped to huge pages or mlocked, // for instance. if (Config->ZKeepTextSectionPrefix) for (StringRef V : {".text.hot.", ".text.unlikely.", ".text.startup.", ".text.exit."}) { if (isSectionPrefix(V, S->Name)) return V.drop_back(); } for (StringRef V : {".text.", ".rodata.", ".data.rel.ro.", ".data.", ".bss.rel.ro.", ".bss.", ".init_array.", ".fini_array.", ".ctors.", ".dtors.", ".tbss.", ".gcc_except_table.", ".tdata.", ".ARM.exidx.", ".ARM.extab."}) { if (isSectionPrefix(V, S->Name)) return V.drop_back(); } // CommonSection is identified as "COMMON" in linker scripts. // By default, it should go to .bss section. if (S->Name == "COMMON") return ".bss"; return S->Name; } static bool needsInterpSection() { return !SharedFiles.empty() && !Config->DynamicLinker.empty() && Script->needsInterpSection(); } template void elf::writeResult() { Writer().run(); } template void Writer::removeEmptyPTLoad() { llvm::erase_if(Phdrs, [&](const PhdrEntry *P) { if (P->p_type != PT_LOAD) return false; if (!P->FirstSec) return true; uint64_t Size = P->LastSec->Addr + P->LastSec->Size - P->FirstSec->Addr; return Size == 0; }); } template static void combineEhFrameSections() { for (InputSectionBase *&S : InputSections) { EhInputSection *ES = dyn_cast(S); if (!ES || !ES->Live) continue; InX::EhFrame->addSection(ES); S = nullptr; } std::vector &V = InputSections; V.erase(std::remove(V.begin(), V.end(), nullptr), V.end()); } static Defined *addOptionalRegular(StringRef Name, SectionBase *Sec, uint64_t Val, uint8_t StOther = STV_HIDDEN, uint8_t Binding = STB_GLOBAL) { Symbol *S = Symtab->find(Name); if (!S || S->isDefined()) return nullptr; Symbol *Sym = Symtab->addRegular(Name, StOther, STT_NOTYPE, Val, /*Size=*/0, Binding, Sec, /*File=*/nullptr); return cast(Sym); } // The linker is expected to define some symbols depending on // the linking result. This function defines such symbols. void elf::addReservedSymbols() { if (Config->EMachine == EM_MIPS) { // Define _gp for MIPS. st_value of _gp symbol will be updated by Writer // so that it points to an absolute address which by default is relative // to GOT. Default offset is 0x7ff0. // See "Global Data Symbols" in Chapter 6 in the following document: // ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf ElfSym::MipsGp = Symtab->addAbsolute("_gp", STV_HIDDEN, STB_GLOBAL); // On MIPS O32 ABI, _gp_disp is a magic symbol designates offset between // start of function and 'gp' pointer into GOT. if (Symtab->find("_gp_disp")) ElfSym::MipsGpDisp = Symtab->addAbsolute("_gp_disp", STV_HIDDEN, STB_GLOBAL); // The __gnu_local_gp is a magic symbol equal to the current value of 'gp' // pointer. This symbol is used in the code generated by .cpload pseudo-op // in case of using -mno-shared option. // https://sourceware.org/ml/binutils/2004-12/msg00094.html if (Symtab->find("__gnu_local_gp")) ElfSym::MipsLocalGp = Symtab->addAbsolute("__gnu_local_gp", STV_HIDDEN, STB_GLOBAL); } // The Power Architecture 64-bit v2 ABI defines a TableOfContents (TOC) which // combines the typical ELF GOT with the small data sections. It commonly // includes .got .toc .sdata .sbss. The .TOC. symbol replaces both // _GLOBAL_OFFSET_TABLE_ and _SDA_BASE_ from the 32-bit ABI. It is used to // represent the TOC base which is offset by 0x8000 bytes from the start of // the .got section. ElfSym::GlobalOffsetTable = addOptionalRegular( (Config->EMachine == EM_PPC64) ? ".TOC." : "_GLOBAL_OFFSET_TABLE_", Out::ElfHeader, Target->GotBaseSymOff); // __ehdr_start is the location of ELF file headers. Note that we define // this symbol unconditionally even when using a linker script, which // differs from the behavior implemented by GNU linker which only define // this symbol if ELF headers are in the memory mapped segment. addOptionalRegular("__ehdr_start", Out::ElfHeader, 0, STV_HIDDEN); // __executable_start is not documented, but the expectation of at // least the Android libc is that it points to the ELF header. addOptionalRegular("__executable_start", Out::ElfHeader, 0, STV_HIDDEN); // __dso_handle symbol is passed to cxa_finalize as a marker to identify // each DSO. The address of the symbol doesn't matter as long as they are // different in different DSOs, so we chose the start address of the DSO. addOptionalRegular("__dso_handle", Out::ElfHeader, 0, STV_HIDDEN); // If linker script do layout we do not need to create any standart symbols. if (Script->HasSectionsCommand) return; auto Add = [](StringRef S, int64_t Pos) { return addOptionalRegular(S, Out::ElfHeader, Pos, STV_DEFAULT); }; ElfSym::Bss = Add("__bss_start", 0); ElfSym::End1 = Add("end", -1); ElfSym::End2 = Add("_end", -1); ElfSym::Etext1 = Add("etext", -1); ElfSym::Etext2 = Add("_etext", -1); ElfSym::Edata1 = Add("edata", -1); ElfSym::Edata2 = Add("_edata", -1); } static OutputSection *findSection(StringRef Name) { for (BaseCommand *Base : Script->SectionCommands) if (auto *Sec = dyn_cast(Base)) if (Sec->Name == Name) return Sec; return nullptr; } // Initialize Out members. template static void createSyntheticSections() { // Initialize all pointers with NULL. This is needed because // you can call lld::elf::main more than once as a library. memset(&Out::First, 0, sizeof(Out)); auto Add = [](InputSectionBase *Sec) { InputSections.push_back(Sec); }; InX::DynStrTab = make(".dynstr", true); InX::Dynamic = make>(); if (Config->AndroidPackDynRelocs) { InX::RelaDyn = make>( Config->IsRela ? ".rela.dyn" : ".rel.dyn"); } else { InX::RelaDyn = make>( Config->IsRela ? ".rela.dyn" : ".rel.dyn", Config->ZCombreloc); } InX::ShStrTab = make(".shstrtab", false); Out::ProgramHeaders = make("", 0, SHF_ALLOC); Out::ProgramHeaders->Alignment = Config->Wordsize; if (needsInterpSection()) { InX::Interp = createInterpSection(); Add(InX::Interp); } else { InX::Interp = nullptr; } if (Config->Strip != StripPolicy::All) { InX::StrTab = make(".strtab", false); InX::SymTab = make>(*InX::StrTab); InX::SymTabShndx = make(); } if (Config->BuildId != BuildIdKind::None) { InX::BuildId = make(); Add(InX::BuildId); } InX::Bss = make(".bss", 0, 1); Add(InX::Bss); // If there is a SECTIONS command and a .data.rel.ro section name use name // .data.rel.ro.bss so that we match in the .data.rel.ro output section. // This makes sure our relro is contiguous. bool HasDataRelRo = Script->HasSectionsCommand && findSection(".data.rel.ro"); InX::BssRelRo = make(HasDataRelRo ? ".data.rel.ro.bss" : ".bss.rel.ro", 0, 1); Add(InX::BssRelRo); // Add MIPS-specific sections. if (Config->EMachine == EM_MIPS) { if (!Config->Shared && Config->HasDynSymTab) { InX::MipsRldMap = make(); Add(InX::MipsRldMap); } if (auto *Sec = MipsAbiFlagsSection::create()) Add(Sec); if (auto *Sec = MipsOptionsSection::create()) Add(Sec); if (auto *Sec = MipsReginfoSection::create()) Add(Sec); } if (Config->HasDynSymTab) { InX::DynSymTab = make>(*InX::DynStrTab); Add(InX::DynSymTab); In::VerSym = make>(); Add(In::VerSym); if (!Config->VersionDefinitions.empty()) { In::VerDef = make>(); Add(In::VerDef); } In::VerNeed = make>(); Add(In::VerNeed); if (Config->GnuHash) { InX::GnuHashTab = make(); Add(InX::GnuHashTab); } if (Config->SysvHash) { InX::HashTab = make(); Add(InX::HashTab); } Add(InX::Dynamic); Add(InX::DynStrTab); Add(InX::RelaDyn); } if (Config->RelrPackDynRelocs) { InX::RelrDyn = make>(); Add(InX::RelrDyn); } // Add .got. MIPS' .got is so different from the other archs, // it has its own class. if (Config->EMachine == EM_MIPS) { InX::MipsGot = make(); Add(InX::MipsGot); } else { InX::Got = make(); Add(InX::Got); } InX::GotPlt = make(); Add(InX::GotPlt); InX::IgotPlt = make(); Add(InX::IgotPlt); if (Config->GdbIndex) { InX::GdbIndex = GdbIndexSection::create(); Add(InX::GdbIndex); } // We always need to add rel[a].plt to output if it has entries. // Even for static linking it can contain R_[*]_IRELATIVE relocations. InX::RelaPlt = make>( Config->IsRela ? ".rela.plt" : ".rel.plt", false /*Sort*/); Add(InX::RelaPlt); // The RelaIplt immediately follows .rel.plt (.rel.dyn for ARM) to ensure // that the IRelative relocations are processed last by the dynamic loader. // We cannot place the iplt section in .rel.dyn when Android relocation // packing is enabled because that would cause a section type mismatch. // However, because the Android dynamic loader reads .rel.plt after .rel.dyn, // we can get the desired behaviour by placing the iplt section in .rel.plt. InX::RelaIplt = make>( (Config->EMachine == EM_ARM && !Config->AndroidPackDynRelocs) ? ".rel.dyn" : InX::RelaPlt->Name, false /*Sort*/); Add(InX::RelaIplt); InX::Plt = make(false); Add(InX::Plt); InX::Iplt = make(true); Add(InX::Iplt); if (!Config->Relocatable) { if (Config->EhFrameHdr) { InX::EhFrameHdr = make(); Add(InX::EhFrameHdr); } InX::EhFrame = make(); Add(InX::EhFrame); } if (InX::SymTab) Add(InX::SymTab); if (InX::SymTabShndx) Add(InX::SymTabShndx); Add(InX::ShStrTab); if (InX::StrTab) Add(InX::StrTab); if (Config->EMachine == EM_ARM && !Config->Relocatable) // Add a sentinel to terminate .ARM.exidx. It helps an unwinder // to find the exact address range of the last entry. Add(make()); } // The main function of the writer. template void Writer::run() { // Create linker-synthesized sections such as .got or .plt. // Such sections are of type input section. createSyntheticSections(); if (!Config->Relocatable) combineEhFrameSections(); // We want to process linker script commands. When SECTIONS command // is given we let it create sections. Script->processSectionCommands(); // Linker scripts controls how input sections are assigned to output sections. // Input sections that were not handled by scripts are called "orphans", and // they are assigned to output sections by the default rule. Process that. Script->addOrphanSections(); if (Config->Discard != DiscardPolicy::All) copyLocalSymbols(); if (Config->CopyRelocs) addSectionSymbols(); // Now that we have a complete set of output sections. This function // completes section contents. For example, we need to add strings // to the string table, and add entries to .got and .plt. // finalizeSections does that. finalizeSections(); if (errorCount()) return; Script->assignAddresses(); // If -compressed-debug-sections is specified, we need to compress // .debug_* sections. Do it right now because it changes the size of // output sections. for (OutputSection *Sec : OutputSections) Sec->maybeCompress(); Script->allocateHeaders(Phdrs); // Remove empty PT_LOAD to avoid causing the dynamic linker to try to mmap a // 0 sized region. This has to be done late since only after assignAddresses // we know the size of the sections. removeEmptyPTLoad(); if (!Config->OFormatBinary) assignFileOffsets(); else assignFileOffsetsBinary(); setPhdrs(); if (Config->Relocatable) { for (OutputSection *Sec : OutputSections) Sec->Addr = 0; } if (Config->CheckSections) checkSections(); // It does not make sense try to open the file if we have error already. if (errorCount()) return; // Write the result down to a file. openFile(); if (errorCount()) return; if (!Config->OFormatBinary) { writeTrapInstr(); writeHeader(); writeSections(); } else { writeSectionsBinary(); } // Backfill .note.gnu.build-id section content. This is done at last // because the content is usually a hash value of the entire output file. writeBuildId(); if (errorCount()) return; // Handle -Map and -cref options. writeMapFile(); writeCrossReferenceTable(); if (errorCount()) return; if (auto E = Buffer->commit()) error("failed to write to the output file: " + toString(std::move(E))); } static bool shouldKeepInSymtab(SectionBase *Sec, StringRef SymName, const Symbol &B) { if (B.isSection()) return false; if (Config->Discard == DiscardPolicy::None) return true; // In ELF assembly .L symbols are normally discarded by the assembler. // If the assembler fails to do so, the linker discards them if // * --discard-locals is used. // * The symbol is in a SHF_MERGE section, which is normally the reason for // the assembler keeping the .L symbol. if (!SymName.startswith(".L") && !SymName.empty()) return true; if (Config->Discard == DiscardPolicy::Locals) return false; return !Sec || !(Sec->Flags & SHF_MERGE); } static bool includeInSymtab(const Symbol &B) { if (!B.isLocal() && !B.IsUsedInRegularObj) return false; if (auto *D = dyn_cast(&B)) { // Always include absolute symbols. SectionBase *Sec = D->Section; if (!Sec) return true; Sec = Sec->Repl; // Exclude symbols pointing to garbage-collected sections. if (isa(Sec) && !Sec->Live) return false; if (auto *S = dyn_cast(Sec)) if (!S->getSectionPiece(D->Value)->Live) return false; return true; } return B.Used; } // Local symbols are not in the linker's symbol table. This function scans // each object file's symbol table to copy local symbols to the output. template void Writer::copyLocalSymbols() { if (!InX::SymTab) return; for (InputFile *File : ObjectFiles) { ObjFile *F = cast>(File); for (Symbol *B : F->getLocalSymbols()) { if (!B->isLocal()) fatal(toString(F) + ": broken object: getLocalSymbols returns a non-local symbol"); auto *DR = dyn_cast(B); // No reason to keep local undefined symbol in symtab. if (!DR) continue; if (!includeInSymtab(*B)) continue; SectionBase *Sec = DR->Section; if (!shouldKeepInSymtab(Sec, B->getName(), *B)) continue; InX::SymTab->addSymbol(B); } } } template void Writer::addSectionSymbols() { // Create a section symbol for each output section so that we can represent // relocations that point to the section. If we know that no relocation is // referring to a section (that happens if the section is a synthetic one), we // don't create a section symbol for that section. for (BaseCommand *Base : Script->SectionCommands) { auto *Sec = dyn_cast(Base); if (!Sec) continue; auto I = llvm::find_if(Sec->SectionCommands, [](BaseCommand *Base) { if (auto *ISD = dyn_cast(Base)) return !ISD->Sections.empty(); return false; }); if (I == Sec->SectionCommands.end()) continue; InputSection *IS = cast(*I)->Sections[0]; // Relocations are not using REL[A] section symbols. if (IS->Type == SHT_REL || IS->Type == SHT_RELA) continue; // Unlike other synthetic sections, mergeable output sections contain data // copied from input sections, and there may be a relocation pointing to its // contents if -r or -emit-reloc are given. if (isa(IS) && !(IS->Flags & SHF_MERGE)) continue; auto *Sym = make(IS->File, "", STB_LOCAL, /*StOther=*/0, STT_SECTION, /*Value=*/0, /*Size=*/0, IS); InX::SymTab->addSymbol(Sym); } } // Today's loaders have a feature to make segments read-only after // processing dynamic relocations to enhance security. PT_GNU_RELRO // is defined for that. // // This function returns true if a section needs to be put into a // PT_GNU_RELRO segment. static bool isRelroSection(const OutputSection *Sec) { if (!Config->ZRelro) return false; uint64_t Flags = Sec->Flags; // Non-allocatable or non-writable sections don't need RELRO because // they are not writable or not even mapped to memory in the first place. // RELRO is for sections that are essentially read-only but need to // be writable only at process startup to allow dynamic linker to // apply relocations. if (!(Flags & SHF_ALLOC) || !(Flags & SHF_WRITE)) return false; // Once initialized, TLS data segments are used as data templates // for a thread-local storage. For each new thread, runtime // allocates memory for a TLS and copy templates there. No thread // are supposed to use templates directly. Thus, it can be in RELRO. if (Flags & SHF_TLS) return true; // .init_array, .preinit_array and .fini_array contain pointers to // functions that are executed on process startup or exit. These // pointers are set by the static linker, and they are not expected // to change at runtime. But if you are an attacker, you could do // interesting things by manipulating pointers in .fini_array, for // example. So they are put into RELRO. uint32_t Type = Sec->Type; if (Type == SHT_INIT_ARRAY || Type == SHT_FINI_ARRAY || Type == SHT_PREINIT_ARRAY) return true; // .got contains pointers to external symbols. They are resolved by // the dynamic linker when a module is loaded into memory, and after // that they are not expected to change. So, it can be in RELRO. if (InX::Got && Sec == InX::Got->getParent()) return true; if (Sec->Name.equals(".toc")) return true; // .got.plt contains pointers to external function symbols. They are // by default resolved lazily, so we usually cannot put it into RELRO. // However, if "-z now" is given, the lazy symbol resolution is // disabled, which enables us to put it into RELRO. if (Sec == InX::GotPlt->getParent()) return Config->ZNow; // .dynamic section contains data for the dynamic linker, and // there's no need to write to it at runtime, so it's better to put // it into RELRO. if (Sec == InX::Dynamic->getParent()) return true; // Sections with some special names are put into RELRO. This is a // bit unfortunate because section names shouldn't be significant in // ELF in spirit. But in reality many linker features depend on // magic section names. StringRef S = Sec->Name; return S == ".data.rel.ro" || S == ".bss.rel.ro" || S == ".ctors" || S == ".dtors" || S == ".jcr" || S == ".eh_frame" || S == ".openbsd.randomdata"; } // We compute a rank for each section. The rank indicates where the // section should be placed in the file. Instead of using simple // numbers (0,1,2...), we use a series of flags. One for each decision // point when placing the section. // Using flags has two key properties: // * It is easy to check if a give branch was taken. // * It is easy two see how similar two ranks are (see getRankProximity). enum RankFlags { RF_NOT_ADDR_SET = 1 << 18, RF_NOT_INTERP = 1 << 17, RF_NOT_ALLOC = 1 << 16, RF_WRITE = 1 << 15, RF_EXEC_WRITE = 1 << 14, RF_EXEC = 1 << 13, RF_RODATA = 1 << 12, RF_NON_TLS_BSS = 1 << 11, RF_NON_TLS_BSS_RO = 1 << 10, RF_NOT_TLS = 1 << 9, RF_BSS = 1 << 8, RF_NOTE = 1 << 7, RF_PPC_NOT_TOCBSS = 1 << 6, RF_PPC_TOCL = 1 << 5, RF_PPC_TOC = 1 << 4, RF_PPC_GOT = 1 << 3, RF_PPC_BRANCH_LT = 1 << 2, RF_MIPS_GPREL = 1 << 1, RF_MIPS_NOT_GOT = 1 << 0 }; static unsigned getSectionRank(const OutputSection *Sec) { unsigned Rank = 0; // We want to put section specified by -T option first, so we // can start assigning VA starting from them later. if (Config->SectionStartMap.count(Sec->Name)) return Rank; Rank |= RF_NOT_ADDR_SET; // Put .interp first because some loaders want to see that section // on the first page of the executable file when loaded into memory. if (Sec->Name == ".interp") return Rank; Rank |= RF_NOT_INTERP; // Allocatable sections go first to reduce the total PT_LOAD size and // so debug info doesn't change addresses in actual code. if (!(Sec->Flags & SHF_ALLOC)) return Rank | RF_NOT_ALLOC; // Sort sections based on their access permission in the following // order: R, RX, RWX, RW. This order is based on the following // considerations: // * Read-only sections come first such that they go in the // PT_LOAD covering the program headers at the start of the file. // * Read-only, executable sections come next. // * Writable, executable sections follow such that .plt on // architectures where it needs to be writable will be placed // between .text and .data. // * Writable sections come last, such that .bss lands at the very // end of the last PT_LOAD. bool IsExec = Sec->Flags & SHF_EXECINSTR; bool IsWrite = Sec->Flags & SHF_WRITE; if (IsExec) { if (IsWrite) Rank |= RF_EXEC_WRITE; else Rank |= RF_EXEC; } else if (IsWrite) { Rank |= RF_WRITE; } else if (Sec->Type == SHT_PROGBITS) { // Make non-executable and non-writable PROGBITS sections (e.g .rodata // .eh_frame) closer to .text. They likely contain PC or GOT relative // relocations and there could be relocation overflow if other huge sections // (.dynstr .dynsym) were placed in between. Rank |= RF_RODATA; } // If we got here we know that both A and B are in the same PT_LOAD. bool IsTls = Sec->Flags & SHF_TLS; bool IsNoBits = Sec->Type == SHT_NOBITS; // The first requirement we have is to put (non-TLS) nobits sections last. The // reason is that the only thing the dynamic linker will see about them is a // p_memsz that is larger than p_filesz. Seeing that it zeros the end of the // PT_LOAD, so that has to correspond to the nobits sections. bool IsNonTlsNoBits = IsNoBits && !IsTls; if (IsNonTlsNoBits) Rank |= RF_NON_TLS_BSS; // We place nobits RelRo sections before plain r/w ones, and non-nobits RelRo // sections after r/w ones, so that the RelRo sections are contiguous. bool IsRelRo = isRelroSection(Sec); if (IsNonTlsNoBits && !IsRelRo) Rank |= RF_NON_TLS_BSS_RO; if (!IsNonTlsNoBits && IsRelRo) Rank |= RF_NON_TLS_BSS_RO; // The TLS initialization block needs to be a single contiguous block in a R/W // PT_LOAD, so stick TLS sections directly before the other RelRo R/W // sections. The TLS NOBITS sections are placed here as they don't take up // virtual address space in the PT_LOAD. if (!IsTls) Rank |= RF_NOT_TLS; // Within the TLS initialization block, the non-nobits sections need to appear // first. if (IsNoBits) Rank |= RF_BSS; // We create a NOTE segment for contiguous .note sections, so make // them contigous if there are more than one .note section with the // same attributes. if (Sec->Type == SHT_NOTE) Rank |= RF_NOTE; // Some architectures have additional ordering restrictions for sections // within the same PT_LOAD. if (Config->EMachine == EM_PPC64) { // PPC64 has a number of special SHT_PROGBITS+SHF_ALLOC+SHF_WRITE sections // that we would like to make sure appear is a specific order to maximize // their coverage by a single signed 16-bit offset from the TOC base // pointer. Conversely, the special .tocbss section should be first among // all SHT_NOBITS sections. This will put it next to the loaded special // PPC64 sections (and, thus, within reach of the TOC base pointer). StringRef Name = Sec->Name; if (Name != ".tocbss") Rank |= RF_PPC_NOT_TOCBSS; if (Name == ".toc1") Rank |= RF_PPC_TOCL; if (Name == ".toc") Rank |= RF_PPC_TOC; if (Name == ".got") Rank |= RF_PPC_GOT; if (Name == ".branch_lt") Rank |= RF_PPC_BRANCH_LT; } if (Config->EMachine == EM_MIPS) { // All sections with SHF_MIPS_GPREL flag should be grouped together // because data in these sections is addressable with a gp relative address. if (Sec->Flags & SHF_MIPS_GPREL) Rank |= RF_MIPS_GPREL; if (Sec->Name != ".got") Rank |= RF_MIPS_NOT_GOT; } return Rank; } static bool compareSections(const BaseCommand *ACmd, const BaseCommand *BCmd) { const OutputSection *A = cast(ACmd); const OutputSection *B = cast(BCmd); if (A->SortRank != B->SortRank) return A->SortRank < B->SortRank; if (!(A->SortRank & RF_NOT_ADDR_SET)) return Config->SectionStartMap.lookup(A->Name) < Config->SectionStartMap.lookup(B->Name); return false; } void PhdrEntry::add(OutputSection *Sec) { LastSec = Sec; if (!FirstSec) FirstSec = Sec; p_align = std::max(p_align, Sec->Alignment); if (p_type == PT_LOAD) Sec->PtLoad = this; } // The beginning and the ending of .rel[a].plt section are marked // with __rel[a]_iplt_{start,end} symbols if it is a statically linked // executable. The runtime needs these symbols in order to resolve // all IRELATIVE relocs on startup. For dynamic executables, we don't // need these symbols, since IRELATIVE relocs are resolved through GOT // and PLT. For details, see http://www.airs.com/blog/archives/403. template void Writer::addRelIpltSymbols() { if (needsInterpSection()) return; StringRef S = Config->IsRela ? "__rela_iplt_start" : "__rel_iplt_start"; addOptionalRegular(S, InX::RelaIplt, 0, STV_HIDDEN, STB_WEAK); S = Config->IsRela ? "__rela_iplt_end" : "__rel_iplt_end"; ElfSym::RelaIpltEnd = addOptionalRegular(S, InX::RelaIplt, 0, STV_HIDDEN, STB_WEAK); } template void Writer::forEachRelSec( llvm::function_ref Fn) { // Scan all relocations. Each relocation goes through a series // of tests to determine if it needs special treatment, such as // creating GOT, PLT, copy relocations, etc. // Note that relocations for non-alloc sections are directly // processed by InputSection::relocateNonAlloc. for (InputSectionBase *IS : InputSections) if (IS->Live && isa(IS) && (IS->Flags & SHF_ALLOC)) Fn(*IS); for (EhInputSection *ES : InX::EhFrame->Sections) Fn(*ES); } // This function generates assignments for predefined symbols (e.g. _end or // _etext) and inserts them into the commands sequence to be processed at the // appropriate time. This ensures that the value is going to be correct by the // time any references to these symbols are processed and is equivalent to // defining these symbols explicitly in the linker script. template void Writer::setReservedSymbolSections() { if (ElfSym::GlobalOffsetTable) { // The _GLOBAL_OFFSET_TABLE_ symbol is defined by target convention usually // to the start of the .got or .got.plt section. InputSection *GotSection = InX::GotPlt; if (!Target->GotBaseSymInGotPlt) GotSection = InX::MipsGot ? cast(InX::MipsGot) : cast(InX::Got); ElfSym::GlobalOffsetTable->Section = GotSection; } if (ElfSym::RelaIpltEnd) ElfSym::RelaIpltEnd->Value = InX::RelaIplt->getSize(); PhdrEntry *Last = nullptr; PhdrEntry *LastRO = nullptr; for (PhdrEntry *P : Phdrs) { if (P->p_type != PT_LOAD) continue; Last = P; if (!(P->p_flags & PF_W)) LastRO = P; } if (LastRO) { // _etext is the first location after the last read-only loadable segment. if (ElfSym::Etext1) ElfSym::Etext1->Section = LastRO->LastSec; if (ElfSym::Etext2) ElfSym::Etext2->Section = LastRO->LastSec; } if (Last) { // _edata points to the end of the last mapped initialized section. OutputSection *Edata = nullptr; for (OutputSection *OS : OutputSections) { if (OS->Type != SHT_NOBITS) Edata = OS; if (OS == Last->LastSec) break; } if (ElfSym::Edata1) ElfSym::Edata1->Section = Edata; if (ElfSym::Edata2) ElfSym::Edata2->Section = Edata; // _end is the first location after the uninitialized data region. if (ElfSym::End1) ElfSym::End1->Section = Last->LastSec; if (ElfSym::End2) ElfSym::End2->Section = Last->LastSec; } if (ElfSym::Bss) ElfSym::Bss->Section = findSection(".bss"); // Setup MIPS _gp_disp/__gnu_local_gp symbols which should // be equal to the _gp symbol's value. if (ElfSym::MipsGp) { // Find GP-relative section with the lowest address // and use this address to calculate default _gp value. for (OutputSection *OS : OutputSections) { if (OS->Flags & SHF_MIPS_GPREL) { ElfSym::MipsGp->Section = OS; ElfSym::MipsGp->Value = 0x7ff0; break; } } } } // We want to find how similar two ranks are. // The more branches in getSectionRank that match, the more similar they are. // Since each branch corresponds to a bit flag, we can just use // countLeadingZeros. static int getRankProximityAux(OutputSection *A, OutputSection *B) { return countLeadingZeros(A->SortRank ^ B->SortRank); } static int getRankProximity(OutputSection *A, BaseCommand *B) { if (auto *Sec = dyn_cast(B)) return getRankProximityAux(A, Sec); return -1; } // When placing orphan sections, we want to place them after symbol assignments // so that an orphan after // begin_foo = .; // foo : { *(foo) } // end_foo = .; // doesn't break the intended meaning of the begin/end symbols. // We don't want to go over sections since findOrphanPos is the // one in charge of deciding the order of the sections. // We don't want to go over changes to '.', since doing so in // rx_sec : { *(rx_sec) } // . = ALIGN(0x1000); // /* The RW PT_LOAD starts here*/ // rw_sec : { *(rw_sec) } // would mean that the RW PT_LOAD would become unaligned. static bool shouldSkip(BaseCommand *Cmd) { if (auto *Assign = dyn_cast(Cmd)) return Assign->Name != "."; return false; } // We want to place orphan sections so that they share as much // characteristics with their neighbors as possible. For example, if // both are rw, or both are tls. template static std::vector::iterator findOrphanPos(std::vector::iterator B, std::vector::iterator E) { OutputSection *Sec = cast(*E); // Find the first element that has as close a rank as possible. auto I = std::max_element(B, E, [=](BaseCommand *A, BaseCommand *B) { return getRankProximity(Sec, A) < getRankProximity(Sec, B); }); if (I == E) return E; // Consider all existing sections with the same proximity. int Proximity = getRankProximity(Sec, *I); for (; I != E; ++I) { auto *CurSec = dyn_cast(*I); if (!CurSec) continue; if (getRankProximity(Sec, CurSec) != Proximity || Sec->SortRank < CurSec->SortRank) break; } auto IsOutputSec = [](BaseCommand *Cmd) { return isa(Cmd); }; auto J = std::find_if(llvm::make_reverse_iterator(I), llvm::make_reverse_iterator(B), IsOutputSec); I = J.base(); // As a special case, if the orphan section is the last section, put // it at the very end, past any other commands. // This matches bfd's behavior and is convenient when the linker script fully // specifies the start of the file, but doesn't care about the end (the non // alloc sections for example). auto NextSec = std::find_if(I, E, IsOutputSec); if (NextSec == E) return E; while (I != E && shouldSkip(*I)) ++I; return I; } // Builds section order for handling --symbol-ordering-file. static DenseMap buildSectionOrder() { DenseMap SectionOrder; // Use the rarely used option -call-graph-ordering-file to sort sections. if (!Config->CallGraphProfile.empty()) return computeCallGraphProfileOrder(); if (Config->SymbolOrderingFile.empty()) return SectionOrder; struct SymbolOrderEntry { int Priority; bool Present; }; // Build a map from symbols to their priorities. Symbols that didn't // appear in the symbol ordering file have the lowest priority 0. // All explicitly mentioned symbols have negative (higher) priorities. DenseMap SymbolOrder; int Priority = -Config->SymbolOrderingFile.size(); for (StringRef S : Config->SymbolOrderingFile) SymbolOrder.insert({S, {Priority++, false}}); // Build a map from sections to their priorities. auto AddSym = [&](Symbol &Sym) { auto It = SymbolOrder.find(Sym.getName()); if (It == SymbolOrder.end()) return; SymbolOrderEntry &Ent = It->second; Ent.Present = true; warnUnorderableSymbol(&Sym); if (auto *D = dyn_cast(&Sym)) { if (auto *Sec = dyn_cast_or_null(D->Section)) { int &Priority = SectionOrder[cast(Sec->Repl)]; Priority = std::min(Priority, Ent.Priority); } } }; // We want both global and local symbols. We get the global ones from the // symbol table and iterate the object files for the local ones. for (Symbol *Sym : Symtab->getSymbols()) if (!Sym->isLazy()) AddSym(*Sym); for (InputFile *File : ObjectFiles) for (Symbol *Sym : File->getSymbols()) if (Sym->isLocal()) AddSym(*Sym); if (Config->WarnSymbolOrdering) for (auto OrderEntry : SymbolOrder) if (!OrderEntry.second.Present) warn("symbol ordering file: no such symbol: " + OrderEntry.first); return SectionOrder; } // Sorts the sections in ISD according to the provided section order. static void sortISDBySectionOrder(InputSectionDescription *ISD, const DenseMap &Order) { std::vector UnorderedSections; std::vector> OrderedSections; uint64_t UnorderedSize = 0; for (InputSection *IS : ISD->Sections) { auto I = Order.find(IS); if (I == Order.end()) { UnorderedSections.push_back(IS); UnorderedSize += IS->getSize(); continue; } OrderedSections.push_back({IS, I->second}); } llvm::sort( OrderedSections.begin(), OrderedSections.end(), [&](std::pair A, std::pair B) { return A.second < B.second; }); // Find an insertion point for the ordered section list in the unordered // section list. On targets with limited-range branches, this is the mid-point // of the unordered section list. This decreases the likelihood that a range // extension thunk will be needed to enter or exit the ordered region. If the // ordered section list is a list of hot functions, we can generally expect // the ordered functions to be called more often than the unordered functions, // making it more likely that any particular call will be within range, and // therefore reducing the number of thunks required. // // For example, imagine that you have 8MB of hot code and 32MB of cold code. // If the layout is: // // 8MB hot // 32MB cold // // only the first 8-16MB of the cold code (depending on which hot function it // is actually calling) can call the hot code without a range extension thunk. // However, if we use this layout: // // 16MB cold // 8MB hot // 16MB cold // // both the last 8-16MB of the first block of cold code and the first 8-16MB // of the second block of cold code can call the hot code without a thunk. So // we effectively double the amount of code that could potentially call into // the hot code without a thunk. size_t InsPt = 0; if (Target->ThunkSectionSpacing && !OrderedSections.empty()) { uint64_t UnorderedPos = 0; for (; InsPt != UnorderedSections.size(); ++InsPt) { UnorderedPos += UnorderedSections[InsPt]->getSize(); if (UnorderedPos > UnorderedSize / 2) break; } } ISD->Sections.clear(); for (InputSection *IS : makeArrayRef(UnorderedSections).slice(0, InsPt)) ISD->Sections.push_back(IS); for (std::pair P : OrderedSections) ISD->Sections.push_back(P.first); for (InputSection *IS : makeArrayRef(UnorderedSections).slice(InsPt)) ISD->Sections.push_back(IS); } static void sortSection(OutputSection *Sec, const DenseMap &Order) { StringRef Name = Sec->Name; // Sort input sections by section name suffixes for // __attribute__((init_priority(N))). if (Name == ".init_array" || Name == ".fini_array") { if (!Script->HasSectionsCommand) Sec->sortInitFini(); return; } // Sort input sections by the special rule for .ctors and .dtors. if (Name == ".ctors" || Name == ".dtors") { if (!Script->HasSectionsCommand) Sec->sortCtorsDtors(); return; } // Never sort these. if (Name == ".init" || Name == ".fini") return; // Sort input sections by priority using the list provided // by --symbol-ordering-file. if (!Order.empty()) for (BaseCommand *B : Sec->SectionCommands) if (auto *ISD = dyn_cast(B)) sortISDBySectionOrder(ISD, Order); } // If no layout was provided by linker script, we want to apply default // sorting for special input sections. This also handles --symbol-ordering-file. template void Writer::sortInputSections() { // Build the order once since it is expensive. DenseMap Order = buildSectionOrder(); for (BaseCommand *Base : Script->SectionCommands) if (auto *Sec = dyn_cast(Base)) sortSection(Sec, Order); } template void Writer::sortSections() { Script->adjustSectionsBeforeSorting(); // Don't sort if using -r. It is not necessary and we want to preserve the // relative order for SHF_LINK_ORDER sections. if (Config->Relocatable) return; sortInputSections(); for (BaseCommand *Base : Script->SectionCommands) { auto *OS = dyn_cast(Base); if (!OS) continue; OS->SortRank = getSectionRank(OS); // We want to assign rude approximation values to OutSecOff fields // to know the relative order of the input sections. We use it for // sorting SHF_LINK_ORDER sections. See resolveShfLinkOrder(). uint64_t I = 0; for (InputSection *Sec : getInputSections(OS)) Sec->OutSecOff = I++; } if (!Script->HasSectionsCommand) { // We know that all the OutputSections are contiguous in this case. auto IsSection = [](BaseCommand *Base) { return isa(Base); }; std::stable_sort( llvm::find_if(Script->SectionCommands, IsSection), llvm::find_if(llvm::reverse(Script->SectionCommands), IsSection).base(), compareSections); return; } // Orphan sections are sections present in the input files which are // not explicitly placed into the output file by the linker script. // // The sections in the linker script are already in the correct // order. We have to figuere out where to insert the orphan // sections. // // The order of the sections in the script is arbitrary and may not agree with // compareSections. This means that we cannot easily define a strict weak // ordering. To see why, consider a comparison of a section in the script and // one not in the script. We have a two simple options: // * Make them equivalent (a is not less than b, and b is not less than a). // The problem is then that equivalence has to be transitive and we can // have sections a, b and c with only b in a script and a less than c // which breaks this property. // * Use compareSectionsNonScript. Given that the script order doesn't have // to match, we can end up with sections a, b, c, d where b and c are in the // script and c is compareSectionsNonScript less than b. In which case d // can be equivalent to c, a to b and d < a. As a concrete example: // .a (rx) # not in script // .b (rx) # in script // .c (ro) # in script // .d (ro) # not in script // // The way we define an order then is: // * Sort only the orphan sections. They are in the end right now. // * Move each orphan section to its preferred position. We try // to put each section in the last position where it can share // a PT_LOAD. // // There is some ambiguity as to where exactly a new entry should be // inserted, because Commands contains not only output section // commands but also other types of commands such as symbol assignment // expressions. There's no correct answer here due to the lack of the // formal specification of the linker script. We use heuristics to // determine whether a new output command should be added before or // after another commands. For the details, look at shouldSkip // function. auto I = Script->SectionCommands.begin(); auto E = Script->SectionCommands.end(); auto NonScriptI = std::find_if(I, E, [](BaseCommand *Base) { if (auto *Sec = dyn_cast(Base)) return Sec->SectionIndex == UINT32_MAX; return false; }); // Sort the orphan sections. std::stable_sort(NonScriptI, E, compareSections); // As a horrible special case, skip the first . assignment if it is before any // section. We do this because it is common to set a load address by starting // the script with ". = 0xabcd" and the expectation is that every section is // after that. auto FirstSectionOrDotAssignment = std::find_if(I, E, [](BaseCommand *Cmd) { return !shouldSkip(Cmd); }); if (FirstSectionOrDotAssignment != E && isa(**FirstSectionOrDotAssignment)) ++FirstSectionOrDotAssignment; I = FirstSectionOrDotAssignment; while (NonScriptI != E) { auto Pos = findOrphanPos(I, NonScriptI); OutputSection *Orphan = cast(*NonScriptI); // As an optimization, find all sections with the same sort rank // and insert them with one rotate. unsigned Rank = Orphan->SortRank; auto End = std::find_if(NonScriptI + 1, E, [=](BaseCommand *Cmd) { return cast(Cmd)->SortRank != Rank; }); std::rotate(Pos, NonScriptI, End); NonScriptI = End; } Script->adjustSectionsAfterSorting(); } static bool compareByFilePosition(InputSection *A, InputSection *B) { // Synthetic, i. e. a sentinel section, should go last. if (A->kind() == InputSectionBase::Synthetic || B->kind() == InputSectionBase::Synthetic) return A->kind() != InputSectionBase::Synthetic; InputSection *LA = A->getLinkOrderDep(); InputSection *LB = B->getLinkOrderDep(); OutputSection *AOut = LA->getParent(); OutputSection *BOut = LB->getParent(); if (AOut != BOut) return AOut->SectionIndex < BOut->SectionIndex; return LA->OutSecOff < LB->OutSecOff; } // This function is used by the --merge-exidx-entries to detect duplicate // .ARM.exidx sections. It is Arm only. // // The .ARM.exidx section is of the form: // | PREL31 offset to function | Unwind instructions for function | // where the unwind instructions are either a small number of unwind // instructions inlined into the table entry, the special CANT_UNWIND value of // 0x1 or a PREL31 offset into a .ARM.extab Section that contains unwind // instructions. // // We return true if all the unwind instructions in the .ARM.exidx entries of // Cur can be merged into the last entry of Prev. static bool isDuplicateArmExidxSec(InputSection *Prev, InputSection *Cur) { // References to .ARM.Extab Sections have bit 31 clear and are not the // special EXIDX_CANTUNWIND bit-pattern. auto IsExtabRef = [](uint32_t Unwind) { return (Unwind & 0x80000000) == 0 && Unwind != 0x1; }; struct ExidxEntry { ulittle32_t Fn; ulittle32_t Unwind; }; // Get the last table Entry from the previous .ARM.exidx section. const ExidxEntry &PrevEntry = Prev->getDataAs().back(); if (IsExtabRef(PrevEntry.Unwind)) return false; // We consider the unwind instructions of an .ARM.exidx table entry // a duplicate if the previous unwind instructions if: // - Both are the special EXIDX_CANTUNWIND. // - Both are the same inline unwind instructions. // We do not attempt to follow and check links into .ARM.extab tables as // consecutive identical entries are rare and the effort to check that they // are identical is high. for (const ExidxEntry Entry : Cur->getDataAs()) if (IsExtabRef(Entry.Unwind) || Entry.Unwind != PrevEntry.Unwind) return false; // All table entries in this .ARM.exidx Section can be merged into the // previous Section. return true; } template void Writer::resolveShfLinkOrder() { for (OutputSection *Sec : OutputSections) { if (!(Sec->Flags & SHF_LINK_ORDER)) continue; // Link order may be distributed across several InputSectionDescriptions // but sort must consider them all at once. std::vector ScriptSections; std::vector Sections; for (BaseCommand *Base : Sec->SectionCommands) { if (auto *ISD = dyn_cast(Base)) { for (InputSection *&IS : ISD->Sections) { ScriptSections.push_back(&IS); Sections.push_back(IS); } } } std::stable_sort(Sections.begin(), Sections.end(), compareByFilePosition); if (!Config->Relocatable && Config->EMachine == EM_ARM && Sec->Type == SHT_ARM_EXIDX) { if (auto *Sentinel = dyn_cast(Sections.back())) { assert(Sections.size() >= 2 && "We should create a sentinel section only if there are " "alive regular exidx sections."); // The last executable section is required to fill the sentinel. // Remember it here so that we don't have to find it again. Sentinel->Highest = Sections[Sections.size() - 2]->getLinkOrderDep(); } if (Config->MergeArmExidx) { // The EHABI for the Arm Architecture permits consecutive identical // table entries to be merged. We use a simple implementation that // removes a .ARM.exidx Input Section if it can be merged into the // previous one. This does not require any rewriting of InputSection // contents but misses opportunities for fine grained deduplication // where only a subset of the InputSection contents can be merged. size_t Prev = 0; // The last one is a sentinel entry which should not be removed. for (size_t I = 1; I < Sections.size() - 1; ++I) { if (isDuplicateArmExidxSec(Sections[Prev], Sections[I])) Sections[I] = nullptr; else Prev = I; } } } for (int I = 0, N = Sections.size(); I < N; ++I) *ScriptSections[I] = Sections[I]; // Remove the Sections we marked as duplicate earlier. for (BaseCommand *Base : Sec->SectionCommands) if (auto *ISD = dyn_cast(Base)) llvm::erase_if(ISD->Sections, [](InputSection *IS) { return !IS; }); } } static void applySynthetic(const std::vector &Sections, llvm::function_ref Fn) { for (SyntheticSection *SS : Sections) if (SS && SS->getParent() && !SS->empty()) Fn(SS); } // In order to allow users to manipulate linker-synthesized sections, // we had to add synthetic sections to the input section list early, // even before we make decisions whether they are needed. This allows // users to write scripts like this: ".mygot : { .got }". // // Doing it has an unintended side effects. If it turns out that we // don't need a .got (for example) at all because there's no // relocation that needs a .got, we don't want to emit .got. // // To deal with the above problem, this function is called after // scanRelocations is called to remove synthetic sections that turn // out to be empty. static void removeUnusedSyntheticSections() { // All input synthetic sections that can be empty are placed after // all regular ones. We iterate over them all and exit at first // non-synthetic. for (InputSectionBase *S : llvm::reverse(InputSections)) { SyntheticSection *SS = dyn_cast(S); if (!SS) return; OutputSection *OS = SS->getParent(); if (!OS || !SS->empty()) continue; // If we reach here, then SS is an unused synthetic section and we want to // remove it from corresponding input section description of output section. for (BaseCommand *B : OS->SectionCommands) if (auto *ISD = dyn_cast(B)) llvm::erase_if(ISD->Sections, [=](InputSection *IS) { return IS == SS; }); } } // Returns true if a symbol can be replaced at load-time by a symbol // with the same name defined in other ELF executable or DSO. static bool computeIsPreemptible(const Symbol &B) { assert(!B.isLocal()); // Only symbols that appear in dynsym can be preempted. if (!B.includeInDynsym()) return false; // Only default visibility symbols can be preempted. if (B.Visibility != STV_DEFAULT) return false; // At this point copy relocations have not been created yet, so any // symbol that is not defined locally is preemptible. if (!B.isDefined()) return true; // If we have a dynamic list it specifies which local symbols are preemptible. if (Config->HasDynamicList) return false; if (!Config->Shared) return false; // -Bsymbolic means that definitions are not preempted. if (Config->Bsymbolic || (Config->BsymbolicFunctions && B.isFunc())) return false; return true; } // Create output section objects and add them to OutputSections. template void Writer::finalizeSections() { Out::DebugInfo = findSection(".debug_info"); Out::PreinitArray = findSection(".preinit_array"); Out::InitArray = findSection(".init_array"); Out::FiniArray = findSection(".fini_array"); // The linker needs to define SECNAME_start, SECNAME_end and SECNAME_stop // symbols for sections, so that the runtime can get the start and end // addresses of each section by section name. Add such symbols. if (!Config->Relocatable) { addStartEndSymbols(); for (BaseCommand *Base : Script->SectionCommands) if (auto *Sec = dyn_cast(Base)) addStartStopSymbols(Sec); } // Add _DYNAMIC symbol. Unlike GNU gold, our _DYNAMIC symbol has no type. // It should be okay as no one seems to care about the type. // Even the author of gold doesn't remember why gold behaves that way. // https://sourceware.org/ml/binutils/2002-03/msg00360.html if (InX::DynSymTab) Symtab->addRegular("_DYNAMIC", STV_HIDDEN, STT_NOTYPE, 0 /*Value*/, /*Size=*/0, STB_WEAK, InX::Dynamic, /*File=*/nullptr); // Define __rel[a]_iplt_{start,end} symbols if needed. addRelIpltSymbols(); // This responsible for splitting up .eh_frame section into // pieces. The relocation scan uses those pieces, so this has to be // earlier. applySynthetic({InX::EhFrame}, [](SyntheticSection *SS) { SS->finalizeContents(); }); for (Symbol *S : Symtab->getSymbols()) S->IsPreemptible |= computeIsPreemptible(*S); // Scan relocations. This must be done after every symbol is declared so that // we can correctly decide if a dynamic relocation is needed. if (!Config->Relocatable) forEachRelSec(scanRelocations); if (InX::Plt && !InX::Plt->empty()) InX::Plt->addSymbols(); if (InX::Iplt && !InX::Iplt->empty()) InX::Iplt->addSymbols(); // Now that we have defined all possible global symbols including linker- // synthesized ones. Visit all symbols to give the finishing touches. for (Symbol *Sym : Symtab->getSymbols()) { if (!includeInSymtab(*Sym)) continue; if (InX::SymTab) InX::SymTab->addSymbol(Sym); if (InX::DynSymTab && Sym->includeInDynsym()) { InX::DynSymTab->addSymbol(Sym); if (auto *File = dyn_cast_or_null>(Sym->File)) if (File->IsNeeded && !Sym->isUndefined()) In::VerNeed->addSymbol(Sym); } } // Do not proceed if there was an undefined symbol. if (errorCount()) return; if (InX::MipsGot) InX::MipsGot->build(); removeUnusedSyntheticSections(); sortSections(); // Now that we have the final list, create a list of all the // OutputSections for convenience. for (BaseCommand *Base : Script->SectionCommands) if (auto *Sec = dyn_cast(Base)) OutputSections.push_back(Sec); // Ensure data sections are not mixed with executable sections when // -execute-only is used. if (Config->ExecuteOnly) for (OutputSection *OS : OutputSections) if (OS->Flags & SHF_EXECINSTR) for (InputSection *IS : getInputSections(OS)) if (!(IS->Flags & SHF_EXECINSTR)) error("-execute-only does not support intermingling data and code"); // Prefer command line supplied address over other constraints. for (OutputSection *Sec : OutputSections) { auto I = Config->SectionStartMap.find(Sec->Name); if (I != Config->SectionStartMap.end()) Sec->AddrExpr = [=] { return I->second; }; } // This is a bit of a hack. A value of 0 means undef, so we set it // to 1 to make __ehdr_start defined. The section number is not // particularly relevant. Out::ElfHeader->SectionIndex = 1; unsigned I = 1; for (OutputSection *Sec : OutputSections) { Sec->SectionIndex = I++; Sec->ShName = InX::ShStrTab->addString(Sec->Name); } // Binary and relocatable output does not have PHDRS. // The headers have to be created before finalize as that can influence the // image base and the dynamic section on mips includes the image base. if (!Config->Relocatable && !Config->OFormatBinary) { Phdrs = Script->hasPhdrsCommands() ? Script->createPhdrs() : createPhdrs(); addPtArmExid(Phdrs); Out::ProgramHeaders->Size = sizeof(Elf_Phdr) * Phdrs.size(); } // Some symbols are defined in term of program headers. Now that we // have the headers, we can find out which sections they point to. setReservedSymbolSections(); // Dynamic section must be the last one in this list and dynamic // symbol table section (DynSymTab) must be the first one. applySynthetic( {InX::DynSymTab, InX::Bss, InX::BssRelRo, InX::GnuHashTab, InX::HashTab, InX::SymTab, InX::SymTabShndx, InX::ShStrTab, InX::StrTab, In::VerDef, InX::DynStrTab, InX::Got, InX::MipsGot, InX::IgotPlt, InX::GotPlt, InX::RelaDyn, InX::RelrDyn, InX::RelaIplt, InX::RelaPlt, InX::Plt, InX::Iplt, InX::EhFrameHdr, In::VerSym, In::VerNeed, InX::Dynamic}, [](SyntheticSection *SS) { SS->finalizeContents(); }); if (!Script->HasSectionsCommand && !Config->Relocatable) fixSectionAlignments(); // After link order processing .ARM.exidx sections can be deduplicated, which // needs to be resolved before any other address dependent operation. resolveShfLinkOrder(); // Some architectures need to generate content that depends on the address // of InputSections. For example some architectures use small displacements // for jump instructions that is the linker's responsibility for creating // range extension thunks for. As the generation of the content may also // alter InputSection addresses we must converge to a fixed point. if (Target->NeedsThunks || Config->AndroidPackDynRelocs || Config->RelrPackDynRelocs) { ThunkCreator TC; AArch64Err843419Patcher A64P; bool Changed; do { Script->assignAddresses(); Changed = false; if (Target->NeedsThunks) Changed |= TC.createThunks(OutputSections); if (Config->FixCortexA53Errata843419) { if (Changed) Script->assignAddresses(); Changed |= A64P.createFixes(); } if (InX::MipsGot) InX::MipsGot->updateAllocSize(); Changed |= InX::RelaDyn->updateAllocSize(); if (InX::RelrDyn) Changed |= InX::RelrDyn->updateAllocSize(); } while (Changed); } // createThunks may have added local symbols to the static symbol table applySynthetic({InX::SymTab}, [](SyntheticSection *SS) { SS->postThunkContents(); }); // Fill other section headers. The dynamic table is finalized // at the end because some tags like RELSZ depend on result // of finalizing other sections. for (OutputSection *Sec : OutputSections) Sec->finalize(); } // The linker is expected to define SECNAME_start and SECNAME_end // symbols for a few sections. This function defines them. template void Writer::addStartEndSymbols() { // If a section does not exist, there's ambiguity as to how we // define _start and _end symbols for an init/fini section. Since // the loader assume that the symbols are always defined, we need to // always define them. But what value? The loader iterates over all // pointers between _start and _end to run global ctors/dtors, so if // the section is empty, their symbol values don't actually matter // as long as _start and _end point to the same location. // // That said, we don't want to set the symbols to 0 (which is // probably the simplest value) because that could cause some // program to fail to link due to relocation overflow, if their // program text is above 2 GiB. We use the address of the .text // section instead to prevent that failure. OutputSection *Default = findSection(".text"); if (!Default) Default = Out::ElfHeader; auto Define = [=](StringRef Start, StringRef End, OutputSection *OS) { if (OS) { addOptionalRegular(Start, OS, 0); addOptionalRegular(End, OS, -1); } else { addOptionalRegular(Start, Default, 0); addOptionalRegular(End, Default, 0); } }; Define("__preinit_array_start", "__preinit_array_end", Out::PreinitArray); Define("__init_array_start", "__init_array_end", Out::InitArray); Define("__fini_array_start", "__fini_array_end", Out::FiniArray); if (OutputSection *Sec = findSection(".ARM.exidx")) Define("__exidx_start", "__exidx_end", Sec); } // If a section name is valid as a C identifier (which is rare because of // the leading '.'), linkers are expected to define __start_ and // __stop_ symbols. They are at beginning and end of the section, // respectively. This is not requested by the ELF standard, but GNU ld and // gold provide the feature, and used by many programs. template void Writer::addStartStopSymbols(OutputSection *Sec) { StringRef S = Sec->Name; if (!isValidCIdentifier(S)) return; addOptionalRegular(Saver.save("__start_" + S), Sec, 0, STV_PROTECTED); addOptionalRegular(Saver.save("__stop_" + S), Sec, -1, STV_PROTECTED); } static bool needsPtLoad(OutputSection *Sec) { if (!(Sec->Flags & SHF_ALLOC) || Sec->Noload) return false; // Don't allocate VA space for TLS NOBITS sections. The PT_TLS PHDR is // responsible for allocating space for them, not the PT_LOAD that // contains the TLS initialization image. if (Sec->Flags & SHF_TLS && Sec->Type == SHT_NOBITS) return false; return true; } // Linker scripts are responsible for aligning addresses. Unfortunately, most // linker scripts are designed for creating two PT_LOADs only, one RX and one // RW. This means that there is no alignment in the RO to RX transition and we // cannot create a PT_LOAD there. static uint64_t computeFlags(uint64_t Flags) { if (Config->Omagic) return PF_R | PF_W | PF_X; if (Config->ExecuteOnly && (Flags & PF_X)) return Flags & ~PF_R; if (Config->SingleRoRx && !(Flags & PF_W)) return Flags | PF_X; return Flags; } // Decide which program headers to create and which sections to include in each // one. template std::vector Writer::createPhdrs() { std::vector Ret; auto AddHdr = [&](unsigned Type, unsigned Flags) -> PhdrEntry * { Ret.push_back(make(Type, Flags)); return Ret.back(); }; // The first phdr entry is PT_PHDR which describes the program header itself. AddHdr(PT_PHDR, PF_R)->add(Out::ProgramHeaders); // PT_INTERP must be the second entry if exists. if (OutputSection *Cmd = findSection(".interp")) AddHdr(PT_INTERP, Cmd->getPhdrFlags())->add(Cmd); // Add the first PT_LOAD segment for regular output sections. uint64_t Flags = computeFlags(PF_R); PhdrEntry *Load = AddHdr(PT_LOAD, Flags); // Add the headers. We will remove them if they don't fit. Load->add(Out::ElfHeader); Load->add(Out::ProgramHeaders); for (OutputSection *Sec : OutputSections) { if (!(Sec->Flags & SHF_ALLOC)) break; if (!needsPtLoad(Sec)) continue; // Segments are contiguous memory regions that has the same attributes // (e.g. executable or writable). There is one phdr for each segment. // Therefore, we need to create a new phdr when the next section has - // different flags or is loaded at a discontiguous address using AT linker - // script command. At the same time, we don't want to create a separate - // load segment for the headers, even if the first output section has - // an AT attribute. + // different flags or is loaded at a discontiguous address or memory + // region using AT or AT> linker script command, respectively. At the same + // time, we don't want to create a separate load segment for the headers, + // even if the first output section has an AT or AT> attribute. uint64_t NewFlags = computeFlags(Sec->getPhdrFlags()); - if ((Sec->LMAExpr && Load->LastSec != Out::ProgramHeaders) || + if (((Sec->LMAExpr || + (Sec->LMARegion && (Sec->LMARegion != Load->FirstSec->LMARegion))) && + Load->LastSec != Out::ProgramHeaders) || Sec->MemRegion != Load->FirstSec->MemRegion || Flags != NewFlags) { Load = AddHdr(PT_LOAD, NewFlags); Flags = NewFlags; } Load->add(Sec); } // Add a TLS segment if any. PhdrEntry *TlsHdr = make(PT_TLS, PF_R); for (OutputSection *Sec : OutputSections) if (Sec->Flags & SHF_TLS) TlsHdr->add(Sec); if (TlsHdr->FirstSec) Ret.push_back(TlsHdr); // Add an entry for .dynamic. if (InX::DynSymTab) AddHdr(PT_DYNAMIC, InX::Dynamic->getParent()->getPhdrFlags()) ->add(InX::Dynamic->getParent()); // PT_GNU_RELRO includes all sections that should be marked as // read-only by dynamic linker after proccessing relocations. // Current dynamic loaders only support one PT_GNU_RELRO PHDR, give // an error message if more than one PT_GNU_RELRO PHDR is required. PhdrEntry *RelRo = make(PT_GNU_RELRO, PF_R); bool InRelroPhdr = false; bool IsRelroFinished = false; for (OutputSection *Sec : OutputSections) { if (!needsPtLoad(Sec)) continue; if (isRelroSection(Sec)) { InRelroPhdr = true; if (!IsRelroFinished) RelRo->add(Sec); else error("section: " + Sec->Name + " is not contiguous with other relro" + " sections"); } else if (InRelroPhdr) { InRelroPhdr = false; IsRelroFinished = true; } } if (RelRo->FirstSec) Ret.push_back(RelRo); // PT_GNU_EH_FRAME is a special section pointing on .eh_frame_hdr. if (!InX::EhFrame->empty() && InX::EhFrameHdr && InX::EhFrame->getParent() && InX::EhFrameHdr->getParent()) AddHdr(PT_GNU_EH_FRAME, InX::EhFrameHdr->getParent()->getPhdrFlags()) ->add(InX::EhFrameHdr->getParent()); // PT_OPENBSD_RANDOMIZE is an OpenBSD-specific feature. That makes // the dynamic linker fill the segment with random data. if (OutputSection *Cmd = findSection(".openbsd.randomdata")) AddHdr(PT_OPENBSD_RANDOMIZE, Cmd->getPhdrFlags())->add(Cmd); // PT_GNU_STACK is a special section to tell the loader to make the // pages for the stack non-executable. If you really want an executable // stack, you can pass -z execstack, but that's not recommended for // security reasons. unsigned Perm = PF_R | PF_W; if (Config->ZExecstack) Perm |= PF_X; AddHdr(PT_GNU_STACK, Perm)->p_memsz = Config->ZStackSize; // PT_OPENBSD_WXNEEDED is a OpenBSD-specific header to mark the executable // is expected to perform W^X violations, such as calling mprotect(2) or // mmap(2) with PROT_WRITE | PROT_EXEC, which is prohibited by default on // OpenBSD. if (Config->ZWxneeded) AddHdr(PT_OPENBSD_WXNEEDED, PF_X); // Create one PT_NOTE per a group of contiguous .note sections. PhdrEntry *Note = nullptr; for (OutputSection *Sec : OutputSections) { if (Sec->Type == SHT_NOTE && (Sec->Flags & SHF_ALLOC)) { if (!Note || Sec->LMAExpr) Note = AddHdr(PT_NOTE, PF_R); Note->add(Sec); } else { Note = nullptr; } } return Ret; } template void Writer::addPtArmExid(std::vector &Phdrs) { if (Config->EMachine != EM_ARM) return; auto I = llvm::find_if(OutputSections, [](OutputSection *Cmd) { return Cmd->Type == SHT_ARM_EXIDX; }); if (I == OutputSections.end()) return; // PT_ARM_EXIDX is the ARM EHABI equivalent of PT_GNU_EH_FRAME PhdrEntry *ARMExidx = make(PT_ARM_EXIDX, PF_R); ARMExidx->add(*I); Phdrs.push_back(ARMExidx); } // The first section of each PT_LOAD, the first section in PT_GNU_RELRO and the // first section after PT_GNU_RELRO have to be page aligned so that the dynamic // linker can set the permissions. template void Writer::fixSectionAlignments() { auto PageAlign = [](OutputSection *Cmd) { if (Cmd && !Cmd->AddrExpr) Cmd->AddrExpr = [=] { return alignTo(Script->getDot(), Config->MaxPageSize); }; }; for (const PhdrEntry *P : Phdrs) if (P->p_type == PT_LOAD && P->FirstSec) PageAlign(P->FirstSec); for (const PhdrEntry *P : Phdrs) { if (P->p_type != PT_GNU_RELRO) continue; if (P->FirstSec) PageAlign(P->FirstSec); // Find the first section after PT_GNU_RELRO. If it is in a PT_LOAD we // have to align it to a page. auto End = OutputSections.end(); auto I = std::find(OutputSections.begin(), End, P->LastSec); if (I == End || (I + 1) == End) continue; OutputSection *Cmd = (*(I + 1)); if (needsPtLoad(Cmd)) PageAlign(Cmd); } } // Adjusts the file alignment for a given output section and returns // its new file offset. The file offset must be the same with its // virtual address (modulo the page size) so that the loader can load // executables without any address adjustment. static uint64_t getFileAlignment(uint64_t Off, OutputSection *Cmd) { OutputSection *First = Cmd->PtLoad ? Cmd->PtLoad->FirstSec : nullptr; // The first section in a PT_LOAD has to have congruent offset and address // module the page size. if (Cmd == First) return alignTo(Off, std::max(Cmd->Alignment, Config->MaxPageSize), Cmd->Addr); // For SHT_NOBITS we don't want the alignment of the section to impact the // offset of the sections that follow. Since nothing seems to care about the // sh_offset of the SHT_NOBITS section itself, just ignore it. if (Cmd->Type == SHT_NOBITS) return Off; // If the section is not in a PT_LOAD, we just have to align it. if (!Cmd->PtLoad) return alignTo(Off, Cmd->Alignment); // If two sections share the same PT_LOAD the file offset is calculated // using this formula: Off2 = Off1 + (VA2 - VA1). return First->Offset + Cmd->Addr - First->Addr; } static uint64_t setOffset(OutputSection *Cmd, uint64_t Off) { Off = getFileAlignment(Off, Cmd); Cmd->Offset = Off; // For SHT_NOBITS we should not count the size. if (Cmd->Type == SHT_NOBITS) return Off; return Off + Cmd->Size; } template void Writer::assignFileOffsetsBinary() { uint64_t Off = 0; for (OutputSection *Sec : OutputSections) if (Sec->Flags & SHF_ALLOC) Off = setOffset(Sec, Off); FileSize = alignTo(Off, Config->Wordsize); } static std::string rangeToString(uint64_t Addr, uint64_t Len) { if (Len == 0) return ""; return "[0x" + utohexstr(Addr) + ", 0x" + utohexstr(Addr + Len - 1) + "]"; } // Assign file offsets to output sections. template void Writer::assignFileOffsets() { uint64_t Off = 0; Off = setOffset(Out::ElfHeader, Off); Off = setOffset(Out::ProgramHeaders, Off); PhdrEntry *LastRX = nullptr; for (PhdrEntry *P : Phdrs) if (P->p_type == PT_LOAD && (P->p_flags & PF_X)) LastRX = P; for (OutputSection *Sec : OutputSections) { Off = setOffset(Sec, Off); if (Script->HasSectionsCommand) continue; // If this is a last section of the last executable segment and that // segment is the last loadable segment, align the offset of the // following section to avoid loading non-segments parts of the file. if (LastRX && LastRX->LastSec == Sec) Off = alignTo(Off, Target->PageSize); } SectionHeaderOff = alignTo(Off, Config->Wordsize); FileSize = SectionHeaderOff + (OutputSections.size() + 1) * sizeof(Elf_Shdr); // Our logic assumes that sections have rising VA within the same segment. // With use of linker scripts it is possible to violate this rule and get file // offset overlaps or overflows. That should never happen with a valid script // which does not move the location counter backwards and usually scripts do // not do that. Unfortunately, there are apps in the wild, for example, Linux // kernel, which control segment distribution explicitly and move the counter // backwards, so we have to allow doing that to support linking them. We // perform non-critical checks for overlaps in checkSectionOverlap(), but here // we want to prevent file size overflows because it would crash the linker. for (OutputSection *Sec : OutputSections) { if (Sec->Type == SHT_NOBITS) continue; if ((Sec->Offset > FileSize) || (Sec->Offset + Sec->Size > FileSize)) error("unable to place section " + Sec->Name + " at file offset " + rangeToString(Sec->Offset, Sec->Offset + Sec->Size) + "; check your linker script for overflows"); } } // Finalize the program headers. We call this function after we assign // file offsets and VAs to all sections. template void Writer::setPhdrs() { for (PhdrEntry *P : Phdrs) { OutputSection *First = P->FirstSec; OutputSection *Last = P->LastSec; if (First) { P->p_filesz = Last->Offset - First->Offset; if (Last->Type != SHT_NOBITS) P->p_filesz += Last->Size; P->p_memsz = Last->Addr + Last->Size - First->Addr; P->p_offset = First->Offset; P->p_vaddr = First->Addr; if (!P->HasLMA) P->p_paddr = First->getLMA(); } if (P->p_type == PT_LOAD) P->p_align = std::max(P->p_align, Config->MaxPageSize); else if (P->p_type == PT_GNU_RELRO) { P->p_align = 1; // The glibc dynamic loader rounds the size down, so we need to round up // to protect the last page. This is a no-op on FreeBSD which always // rounds up. P->p_memsz = alignTo(P->p_memsz, Target->PageSize); } // The TLS pointer goes after PT_TLS. At least glibc will align it, // so round up the size to make sure the offsets are correct. if (P->p_type == PT_TLS) { Out::TlsPhdr = P; if (P->p_memsz) P->p_memsz = alignTo(P->p_memsz, P->p_align); } } } // A helper struct for checkSectionOverlap. namespace { struct SectionOffset { OutputSection *Sec; uint64_t Offset; }; } // namespace // Check whether sections overlap for a specific address range (file offsets, // load and virtual adresses). static void checkOverlap(StringRef Name, std::vector &Sections, bool IsVirtualAddr) { llvm::sort(Sections.begin(), Sections.end(), [=](const SectionOffset &A, const SectionOffset &B) { return A.Offset < B.Offset; }); // Finding overlap is easy given a vector is sorted by start position. // If an element starts before the end of the previous element, they overlap. for (size_t I = 1, End = Sections.size(); I < End; ++I) { SectionOffset A = Sections[I - 1]; SectionOffset B = Sections[I]; if (B.Offset >= A.Offset + A.Sec->Size) continue; // If both sections are in OVERLAY we allow the overlapping of virtual // addresses, because it is what OVERLAY was designed for. if (IsVirtualAddr && A.Sec->InOverlay && B.Sec->InOverlay) continue; errorOrWarn("section " + A.Sec->Name + " " + Name + " range overlaps with " + B.Sec->Name + "\n>>> " + A.Sec->Name + " range is " + rangeToString(A.Offset, A.Sec->Size) + "\n>>> " + B.Sec->Name + " range is " + rangeToString(B.Offset, B.Sec->Size)); } } // Check for overlapping sections and address overflows. // // In this function we check that none of the output sections have overlapping // file offsets. For SHF_ALLOC sections we also check that the load address // ranges and the virtual address ranges don't overlap template void Writer::checkSections() { // First, check that section's VAs fit in available address space for target. for (OutputSection *OS : OutputSections) if ((OS->Addr + OS->Size < OS->Addr) || (!ELFT::Is64Bits && OS->Addr + OS->Size > UINT32_MAX)) errorOrWarn("section " + OS->Name + " at 0x" + utohexstr(OS->Addr) + " of size 0x" + utohexstr(OS->Size) + " exceeds available address space"); // Check for overlapping file offsets. In this case we need to skip any // section marked as SHT_NOBITS. These sections don't actually occupy space in // the file so Sec->Offset + Sec->Size can overlap with others. If --oformat // binary is specified only add SHF_ALLOC sections are added to the output // file so we skip any non-allocated sections in that case. std::vector FileOffs; for (OutputSection *Sec : OutputSections) if (0 < Sec->Size && Sec->Type != SHT_NOBITS && (!Config->OFormatBinary || (Sec->Flags & SHF_ALLOC))) FileOffs.push_back({Sec, Sec->Offset}); checkOverlap("file", FileOffs, false); // When linking with -r there is no need to check for overlapping virtual/load // addresses since those addresses will only be assigned when the final // executable/shared object is created. if (Config->Relocatable) return; // Checking for overlapping virtual and load addresses only needs to take // into account SHF_ALLOC sections since others will not be loaded. // Furthermore, we also need to skip SHF_TLS sections since these will be // mapped to other addresses at runtime and can therefore have overlapping // ranges in the file. std::vector VMAs; for (OutputSection *Sec : OutputSections) if (0 < Sec->Size && (Sec->Flags & SHF_ALLOC) && !(Sec->Flags & SHF_TLS)) VMAs.push_back({Sec, Sec->Addr}); checkOverlap("virtual address", VMAs, true); // Finally, check that the load addresses don't overlap. This will usually be // the same as the virtual addresses but can be different when using a linker // script with AT(). std::vector LMAs; for (OutputSection *Sec : OutputSections) if (0 < Sec->Size && (Sec->Flags & SHF_ALLOC) && !(Sec->Flags & SHF_TLS)) LMAs.push_back({Sec, Sec->getLMA()}); checkOverlap("load address", LMAs, false); } // The entry point address is chosen in the following ways. // // 1. the '-e' entry command-line option; // 2. the ENTRY(symbol) command in a linker control script; // 3. the value of the symbol _start, if present; // 4. the number represented by the entry symbol, if it is a number; // 5. the address of the first byte of the .text section, if present; // 6. the address 0. template uint64_t Writer::getEntryAddr() { // Case 1, 2 or 3 if (Symbol *B = Symtab->find(Config->Entry)) return B->getVA(); // Case 4 uint64_t Addr; if (to_integer(Config->Entry, Addr)) return Addr; // Case 5 if (OutputSection *Sec = findSection(".text")) { if (Config->WarnMissingEntry) warn("cannot find entry symbol " + Config->Entry + "; defaulting to 0x" + utohexstr(Sec->Addr)); return Sec->Addr; } // Case 6 if (Config->WarnMissingEntry) warn("cannot find entry symbol " + Config->Entry + "; not setting start address"); return 0; } static uint16_t getELFType() { if (Config->Pic) return ET_DYN; if (Config->Relocatable) return ET_REL; return ET_EXEC; } static uint8_t getAbiVersion() { // MIPS non-PIC executable gets ABI version 1. if (Config->EMachine == EM_MIPS && getELFType() == ET_EXEC && (Config->EFlags & (EF_MIPS_PIC | EF_MIPS_CPIC)) == EF_MIPS_CPIC) return 1; return 0; } template void Writer::writeHeader() { uint8_t *Buf = Buffer->getBufferStart(); // For executable segments, the trap instructions are written before writing // the header. Setting Elf header bytes to zero ensures that any unused bytes // in header are zero-cleared, instead of having trap instructions. memset(Buf, 0, sizeof(Elf_Ehdr)); memcpy(Buf, "\177ELF", 4); // Write the ELF header. auto *EHdr = reinterpret_cast(Buf); EHdr->e_ident[EI_CLASS] = Config->Is64 ? ELFCLASS64 : ELFCLASS32; EHdr->e_ident[EI_DATA] = Config->IsLE ? ELFDATA2LSB : ELFDATA2MSB; EHdr->e_ident[EI_VERSION] = EV_CURRENT; EHdr->e_ident[EI_OSABI] = Config->OSABI; EHdr->e_ident[EI_ABIVERSION] = getAbiVersion(); EHdr->e_type = getELFType(); EHdr->e_machine = Config->EMachine; EHdr->e_version = EV_CURRENT; EHdr->e_entry = getEntryAddr(); EHdr->e_shoff = SectionHeaderOff; EHdr->e_flags = Config->EFlags; EHdr->e_ehsize = sizeof(Elf_Ehdr); EHdr->e_phnum = Phdrs.size(); EHdr->e_shentsize = sizeof(Elf_Shdr); if (!Config->Relocatable) { EHdr->e_phoff = sizeof(Elf_Ehdr); EHdr->e_phentsize = sizeof(Elf_Phdr); } // Write the program header table. auto *HBuf = reinterpret_cast(Buf + EHdr->e_phoff); for (PhdrEntry *P : Phdrs) { HBuf->p_type = P->p_type; HBuf->p_flags = P->p_flags; HBuf->p_offset = P->p_offset; HBuf->p_vaddr = P->p_vaddr; HBuf->p_paddr = P->p_paddr; HBuf->p_filesz = P->p_filesz; HBuf->p_memsz = P->p_memsz; HBuf->p_align = P->p_align; ++HBuf; } // Write the section header table. // // The ELF header can only store numbers up to SHN_LORESERVE in the e_shnum // and e_shstrndx fields. When the value of one of these fields exceeds // SHN_LORESERVE ELF requires us to put sentinel values in the ELF header and // use fields in the section header at index 0 to store // the value. The sentinel values and fields are: // e_shnum = 0, SHdrs[0].sh_size = number of sections. // e_shstrndx = SHN_XINDEX, SHdrs[0].sh_link = .shstrtab section index. auto *SHdrs = reinterpret_cast(Buf + EHdr->e_shoff); size_t Num = OutputSections.size() + 1; if (Num >= SHN_LORESERVE) SHdrs->sh_size = Num; else EHdr->e_shnum = Num; uint32_t StrTabIndex = InX::ShStrTab->getParent()->SectionIndex; if (StrTabIndex >= SHN_LORESERVE) { SHdrs->sh_link = StrTabIndex; EHdr->e_shstrndx = SHN_XINDEX; } else { EHdr->e_shstrndx = StrTabIndex; } for (OutputSection *Sec : OutputSections) Sec->writeHeaderTo(++SHdrs); } // Open a result file. template void Writer::openFile() { if (!Config->Is64 && FileSize > UINT32_MAX) { error("output file too large: " + Twine(FileSize) + " bytes"); return; } unlinkAsync(Config->OutputFile); unsigned Flags = 0; if (!Config->Relocatable) Flags = FileOutputBuffer::F_executable; Expected> BufferOrErr = FileOutputBuffer::create(Config->OutputFile, FileSize, Flags); if (!BufferOrErr) error("failed to open " + Config->OutputFile + ": " + llvm::toString(BufferOrErr.takeError())); else Buffer = std::move(*BufferOrErr); } template void Writer::writeSectionsBinary() { uint8_t *Buf = Buffer->getBufferStart(); for (OutputSection *Sec : OutputSections) if (Sec->Flags & SHF_ALLOC) Sec->writeTo(Buf + Sec->Offset); } static void fillTrap(uint8_t *I, uint8_t *End) { for (; I + 4 <= End; I += 4) memcpy(I, &Target->TrapInstr, 4); } // Fill the last page of executable segments with trap instructions // instead of leaving them as zero. Even though it is not required by any // standard, it is in general a good thing to do for security reasons. // // We'll leave other pages in segments as-is because the rest will be // overwritten by output sections. template void Writer::writeTrapInstr() { if (Script->HasSectionsCommand) return; // Fill the last page. uint8_t *Buf = Buffer->getBufferStart(); for (PhdrEntry *P : Phdrs) if (P->p_type == PT_LOAD && (P->p_flags & PF_X)) fillTrap(Buf + alignDown(P->p_offset + P->p_filesz, Target->PageSize), Buf + alignTo(P->p_offset + P->p_filesz, Target->PageSize)); // Round up the file size of the last segment to the page boundary iff it is // an executable segment to ensure that other tools don't accidentally // trim the instruction padding (e.g. when stripping the file). PhdrEntry *Last = nullptr; for (PhdrEntry *P : Phdrs) if (P->p_type == PT_LOAD) Last = P; if (Last && (Last->p_flags & PF_X)) Last->p_memsz = Last->p_filesz = alignTo(Last->p_filesz, Target->PageSize); } // Write section contents to a mmap'ed file. template void Writer::writeSections() { uint8_t *Buf = Buffer->getBufferStart(); OutputSection *EhFrameHdr = nullptr; if (InX::EhFrameHdr && !InX::EhFrameHdr->empty()) EhFrameHdr = InX::EhFrameHdr->getParent(); // In -r or -emit-relocs mode, write the relocation sections first as in // ELf_Rel targets we might find out that we need to modify the relocated // section while doing it. for (OutputSection *Sec : OutputSections) if (Sec->Type == SHT_REL || Sec->Type == SHT_RELA) Sec->writeTo(Buf + Sec->Offset); for (OutputSection *Sec : OutputSections) if (Sec != EhFrameHdr && Sec->Type != SHT_REL && Sec->Type != SHT_RELA) Sec->writeTo(Buf + Sec->Offset); // The .eh_frame_hdr depends on .eh_frame section contents, therefore // it should be written after .eh_frame is written. if (EhFrameHdr) EhFrameHdr->writeTo(Buf + EhFrameHdr->Offset); } template void Writer::writeBuildId() { if (!InX::BuildId || !InX::BuildId->getParent()) return; // Compute a hash of all sections of the output file. uint8_t *Start = Buffer->getBufferStart(); uint8_t *End = Start + FileSize; InX::BuildId->writeBuildId({Start, End}); } template void elf::writeResult(); template void elf::writeResult(); template void elf::writeResult(); template void elf::writeResult(); Index: vendor/lld/dist-release_70/test/COFF/Inputs/associative-comdat-mingw-2.s =================================================================== --- vendor/lld/dist-release_70/test/COFF/Inputs/associative-comdat-mingw-2.s (nonexistent) +++ vendor/lld/dist-release_70/test/COFF/Inputs/associative-comdat-mingw-2.s (revision 337639) @@ -0,0 +1,34 @@ + .section .xdata$foo,"dr" + .linkonce discard + .p2align 3 + .long 42 + + .section .xdata$bar,"dr" + .linkonce discard + .p2align 3 + .long 43 + + .section .xdata$baz,"dr" + .linkonce discard + .p2align 3 + .long 44 + + .def foo; + .scl 2; + .type 32; + .endef + .section .text$foo,"xr",discard,foo + .globl foo + .p2align 4 +foo: + ret + + .def bar; + .scl 2; + .type 32; + .endef + .section .text$bar,"xr",discard,bar + .globl bar + .p2align 4 +bar: + ret Property changes on: vendor/lld/dist-release_70/test/COFF/Inputs/associative-comdat-mingw-2.s ___________________________________________________________________ Added: svn:eol-style ## -0,0 +1 ## +native \ No newline at end of property Added: svn:keywords ## -0,0 +1 ## +FreeBSD=%H \ No newline at end of property Added: svn:mime-type ## -0,0 +1 ## +text/plain \ No newline at end of property Index: vendor/lld/dist-release_70/test/COFF/associative-comdat-mingw.s =================================================================== --- vendor/lld/dist-release_70/test/COFF/associative-comdat-mingw.s (nonexistent) +++ vendor/lld/dist-release_70/test/COFF/associative-comdat-mingw.s (revision 337639) @@ -0,0 +1,73 @@ +# REQUIRES: x86 + +# RUN: llvm-mc -triple=x86_64-windows-gnu %s -filetype=obj -o %t1.obj +# RUN: llvm-mc -triple=x86_64-windows-gnu %S/Inputs/associative-comdat-mingw-2.s -filetype=obj -o %t2.obj + +# RUN: lld-link -lldmingw -entry:main %t1.obj %t2.obj -out:%t.gc.exe -verbose +# RUN: llvm-readobj -sections %t.gc.exe | FileCheck %s + +# CHECK: Sections [ +# CHECK: Section { +# CHECK: Number: 2 +# CHECK-LABEL: Name: .rdata (2E 72 64 61 74 61 00 00) +# This is the critical check to show that only *one* definition of +# .xdata$foo was retained. This *must* be 4. +# Make sure that no other .xdata sections get included, which would +# increase the size here. +# CHECK-NEXT: VirtualSize: 0x4 + + .text + .def main; + .scl 2; + .type 32; + .endef + .globl main + .p2align 4, 0x90 +main: + call foo + retq + +# Defines .text$foo (which has a leader symbol and is referenced like +# normally), and .xdata$foo (which lacks a leader symbol, which normally +# would be declared associative to the symbol foo). +# .xdata$foo should be implicitly treated as associative to foo and brought +# in, while .xdata$bar, implicitly associative to bar, not included, and +# .xdata$baz not included since there's no symbol baz. + +# GNU binutils ld doesn't do this at all, but always includes all .xdata/.pdata +# comdat sections, even if --gc-sections is used. + + .section .xdata$foo,"dr" + .linkonce discard + .p2align 3 + .long 42 + + .section .xdata$bar,"dr" + .linkonce discard + .p2align 3 + .long 43 + + .section .xdata$baz,"dr" + .linkonce discard + .p2align 3 + .long 44 + + .def foo; + .scl 2; + .type 32; + .endef + .section .text$foo,"xr",discard,foo + .globl foo + .p2align 4 +foo: + ret + + .def bar; + .scl 2; + .type 32; + .endef + .section .text$bar,"xr",discard,bar + .globl bar + .p2align 4 +bar: + ret Property changes on: vendor/lld/dist-release_70/test/COFF/associative-comdat-mingw.s ___________________________________________________________________ Added: svn:eol-style ## -0,0 +1 ## +native \ No newline at end of property Added: svn:keywords ## -0,0 +1 ## +FreeBSD=%H \ No newline at end of property Added: svn:mime-type ## -0,0 +1 ## +text/plain \ No newline at end of property Index: vendor/lld/dist-release_70/test/ELF/linkerscript/Inputs/at6.s =================================================================== --- vendor/lld/dist-release_70/test/ELF/linkerscript/Inputs/at6.s (nonexistent) +++ vendor/lld/dist-release_70/test/ELF/linkerscript/Inputs/at6.s (revision 337639) @@ -0,0 +1,11 @@ +.global _start +.text +_start: +nop + +.section .sec1,"aw",@progbits +.long 1 + +.section .sec2,"aw",@progbits +.long 2 + Property changes on: vendor/lld/dist-release_70/test/ELF/linkerscript/Inputs/at6.s ___________________________________________________________________ Added: svn:eol-style ## -0,0 +1 ## +native \ No newline at end of property Added: svn:keywords ## -0,0 +1 ## +FreeBSD=%H \ No newline at end of property Added: svn:mime-type ## -0,0 +1 ## +text/plain \ No newline at end of property Index: vendor/lld/dist-release_70/test/ELF/linkerscript/Inputs/at7.s =================================================================== --- vendor/lld/dist-release_70/test/ELF/linkerscript/Inputs/at7.s (nonexistent) +++ vendor/lld/dist-release_70/test/ELF/linkerscript/Inputs/at7.s (revision 337639) @@ -0,0 +1,7 @@ +.global _start +.text +_start: +nop + +.section .sec, "aw" +.word 4 Property changes on: vendor/lld/dist-release_70/test/ELF/linkerscript/Inputs/at7.s ___________________________________________________________________ Added: svn:eol-style ## -0,0 +1 ## +native \ No newline at end of property Added: svn:keywords ## -0,0 +1 ## +FreeBSD=%H \ No newline at end of property Added: svn:mime-type ## -0,0 +1 ## +text/plain \ No newline at end of property Index: vendor/lld/dist-release_70/test/ELF/linkerscript/Inputs/at8.s =================================================================== --- vendor/lld/dist-release_70/test/ELF/linkerscript/Inputs/at8.s (nonexistent) +++ vendor/lld/dist-release_70/test/ELF/linkerscript/Inputs/at8.s (revision 337639) @@ -0,0 +1,8 @@ +.section .sec1,"aw",@progbits +.quad 1 + +.section .sec2,"aw",@progbits +.quad 2 + +.section .sec3,"aw",@progbits +.quad 3 Property changes on: vendor/lld/dist-release_70/test/ELF/linkerscript/Inputs/at8.s ___________________________________________________________________ Added: svn:eol-style ## -0,0 +1 ## +native \ No newline at end of property Added: svn:keywords ## -0,0 +1 ## +FreeBSD=%H \ No newline at end of property Added: svn:mime-type ## -0,0 +1 ## +text/plain \ No newline at end of property Index: vendor/lld/dist-release_70/test/ELF/linkerscript/at6.test =================================================================== --- vendor/lld/dist-release_70/test/ELF/linkerscript/at6.test (nonexistent) +++ vendor/lld/dist-release_70/test/ELF/linkerscript/at6.test (revision 337639) @@ -0,0 +1,30 @@ +# REQUIRES: x86 +# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/at6.s -o %t.o +# RUN: ld.lld %t.o --script %s -o %t +# RUN: llvm-readelf -sections -program-headers %t | FileCheck %s + +MEMORY { + FLASH : ORIGIN = 0x08000000, LENGTH = 0x100 + RAM : ORIGIN = 0x20000000, LENGTH = 0x200 +} + +SECTIONS { + .text : { *(.text) } > FLASH + .sec1 : { *(.sec1) } > RAM + .sec2 : { *(.sec2) } > RAM AT > FLASH +} + +# Make sure we create a separate PT_LOAD entry for .sec2. Previously, +# it was added to the PT_LOAD entry of .sec1 + +# CHECK: Name Type Address Off +# CHECK: .text PROGBITS 0000000008000000 001000 +# CHECK: .sec1 PROGBITS 0000000020000000 002000 +# CHECK: .sec2 PROGBITS 0000000020000004 002004 + +# CHECK: Program Headers: +# CHECK: Type Offset VirtAddr PhysAddr +# CHECK-NEXT: LOAD 0x001000 0x0000000008000000 0x0000000008000000 +# CHECK-NEXT: LOAD 0x002000 0x0000000020000000 0x0000000020000000 +# CHECK-NEXT: LOAD 0x002004 0x0000000020000004 0x0000000008000001 +# CHECK-NOT: LOAD Index: vendor/lld/dist-release_70/test/ELF/linkerscript/at7.test =================================================================== --- vendor/lld/dist-release_70/test/ELF/linkerscript/at7.test (nonexistent) +++ vendor/lld/dist-release_70/test/ELF/linkerscript/at7.test (revision 337639) @@ -0,0 +1,28 @@ +# REQUIRES: x86 +# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/at7.s -o %t.o +# RUN: ld.lld %t.o --script %s -o %t +# RUN: llvm-readelf -sections -program-headers %t | FileCheck %s + +MEMORY { + RAM : ORIGIN = 0x20000000, LENGTH = 0x200 +} + +SECTIONS { + .text : { *(.text) } > RAM AT> RAM + .sec : { *(.sec) } > RAM +} + +# Make sure the memory for the .text section is only reserved once. +# Previously, the location counter for both MemRegion and LMARegion +# was increased unconditionally. + + +# CHECK: Name Type Address Off +# CHECK: .text PROGBITS 0000000020000000 001000 +# CHECK: .sec PROGBITS 0000000020000001 001001 + +# CHECK: Program Headers: +# CHECK: Type Offset VirtAddr PhysAddr +# CHECK-NEXT: LOAD 0x001000 0x0000000020000000 0x0000000020000000 +# CHECK-NEXT: LOAD 0x001001 0x0000000020000001 0x0000000020000001 +# CHECK-NOT: LOAD Index: vendor/lld/dist-release_70/test/ELF/linkerscript/at8.test =================================================================== --- vendor/lld/dist-release_70/test/ELF/linkerscript/at8.test (nonexistent) +++ vendor/lld/dist-release_70/test/ELF/linkerscript/at8.test (revision 337639) @@ -0,0 +1,31 @@ +# REQUIRES: x86 +# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/at8.s -o %t.o +# RUN: ld.lld %t.o --script %s -o %t +# RUN: llvm-readelf -sections -program-headers %t | FileCheck %s + +MEMORY { + FLASH : ORIGIN = 0x08000000, LENGTH = 0x100 + RAM : ORIGIN = 0x20000000, LENGTH = 0x200 +} + +SECTIONS { + .text : { *(.text) } > FLASH + .sec1 : { *(.sec1) } > RAM AT > FLASH + .sec2 : { *(.sec2) } > RAM + .sec3 : { *(.sec3) } > RAM AT > FLASH +} + +# Make sure we do not issue a load-address overlap error +# Previously, .sec3 would overwrite the LMAOffset in the +# PT_LOAD header. + +# CHECK: Name Type Address Off +# CHECK: .text PROGBITS 0000000008000000 001000 +# CHECK: .sec1 PROGBITS 0000000020000000 001000 +# CHECK: .sec2 PROGBITS 0000000020000008 001008 +# CHECK: .sec3 PROGBITS 0000000020000010 001010 + +# CHECK: Program Headers: +# CHECK: Type Offset VirtAddr PhysAddr +# CHECK-NEXT: LOAD 0x001000 0x0000000020000000 0x0000000008000000 +# CHECK-NOT: LOAD