forked from OSchip/llvm-project
1854 lines
68 KiB
C++
1854 lines
68 KiB
C++
//===- InputFiles.cpp -----------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "InputFiles.h"
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#include "Driver.h"
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#include "InputSection.h"
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#include "LinkerScript.h"
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#include "SymbolTable.h"
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#include "Symbols.h"
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#include "SyntheticSections.h"
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#include "lld/Common/DWARF.h"
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#include "lld/Common/ErrorHandler.h"
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#include "lld/Common/Memory.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/CodeGen/Analysis.h"
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#include "llvm/IR/LLVMContext.h"
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#include "llvm/IR/Module.h"
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#include "llvm/LTO/LTO.h"
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#include "llvm/MC/StringTableBuilder.h"
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#include "llvm/Object/ELFObjectFile.h"
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#include "llvm/Support/ARMAttributeParser.h"
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#include "llvm/Support/ARMBuildAttributes.h"
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#include "llvm/Support/Endian.h"
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#include "llvm/Support/Path.h"
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#include "llvm/Support/RISCVAttributeParser.h"
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#include "llvm/Support/TarWriter.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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using namespace llvm::ELF;
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using namespace llvm::object;
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using namespace llvm::sys;
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using namespace llvm::sys::fs;
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using namespace llvm::support::endian;
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using namespace lld;
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using namespace lld::elf;
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bool InputFile::isInGroup;
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uint32_t InputFile::nextGroupId;
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SmallVector<std::unique_ptr<MemoryBuffer>> elf::memoryBuffers;
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SmallVector<ArchiveFile *, 0> elf::archiveFiles;
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SmallVector<BinaryFile *, 0> elf::binaryFiles;
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SmallVector<BitcodeFile *, 0> elf::bitcodeFiles;
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SmallVector<BitcodeFile *, 0> elf::lazyBitcodeFiles;
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SmallVector<ELFFileBase *, 0> elf::objectFiles;
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SmallVector<SharedFile *, 0> elf::sharedFiles;
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std::unique_ptr<TarWriter> elf::tar;
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// Returns "<internal>", "foo.a(bar.o)" or "baz.o".
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std::string lld::toString(const InputFile *f) {
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if (!f)
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return "<internal>";
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if (f->toStringCache.empty()) {
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if (f->archiveName.empty())
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f->toStringCache = f->getName();
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else
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(f->archiveName + "(" + f->getName() + ")").toVector(f->toStringCache);
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}
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return std::string(f->toStringCache);
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}
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static ELFKind getELFKind(MemoryBufferRef mb, StringRef archiveName) {
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unsigned char size;
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unsigned char endian;
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std::tie(size, endian) = getElfArchType(mb.getBuffer());
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auto report = [&](StringRef msg) {
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StringRef filename = mb.getBufferIdentifier();
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if (archiveName.empty())
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fatal(filename + ": " + msg);
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else
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fatal(archiveName + "(" + filename + "): " + msg);
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};
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if (!mb.getBuffer().startswith(ElfMagic))
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report("not an ELF file");
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if (endian != ELFDATA2LSB && endian != ELFDATA2MSB)
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report("corrupted ELF file: invalid data encoding");
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if (size != ELFCLASS32 && size != ELFCLASS64)
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report("corrupted ELF file: invalid file class");
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size_t bufSize = mb.getBuffer().size();
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if ((size == ELFCLASS32 && bufSize < sizeof(Elf32_Ehdr)) ||
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(size == ELFCLASS64 && bufSize < sizeof(Elf64_Ehdr)))
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report("corrupted ELF file: file is too short");
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if (size == ELFCLASS32)
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return (endian == ELFDATA2LSB) ? ELF32LEKind : ELF32BEKind;
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return (endian == ELFDATA2LSB) ? ELF64LEKind : ELF64BEKind;
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}
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InputFile::InputFile(Kind k, MemoryBufferRef m)
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: mb(m), groupId(nextGroupId), fileKind(k) {
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// All files within the same --{start,end}-group get the same group ID.
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// Otherwise, a new file will get a new group ID.
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if (!isInGroup)
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++nextGroupId;
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}
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Optional<MemoryBufferRef> elf::readFile(StringRef path) {
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llvm::TimeTraceScope timeScope("Load input files", path);
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// The --chroot option changes our virtual root directory.
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// This is useful when you are dealing with files created by --reproduce.
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if (!config->chroot.empty() && path.startswith("/"))
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path = saver.save(config->chroot + path);
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log(path);
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config->dependencyFiles.insert(llvm::CachedHashString(path));
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auto mbOrErr = MemoryBuffer::getFile(path, /*IsText=*/false,
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/*RequiresNullTerminator=*/false);
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if (auto ec = mbOrErr.getError()) {
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error("cannot open " + path + ": " + ec.message());
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return None;
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}
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MemoryBufferRef mbref = (*mbOrErr)->getMemBufferRef();
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memoryBuffers.push_back(std::move(*mbOrErr)); // take MB ownership
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if (tar)
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tar->append(relativeToRoot(path), mbref.getBuffer());
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return mbref;
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}
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// All input object files must be for the same architecture
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// (e.g. it does not make sense to link x86 object files with
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// MIPS object files.) This function checks for that error.
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static bool isCompatible(InputFile *file) {
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if (!file->isElf() && !isa<BitcodeFile>(file))
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return true;
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if (file->ekind == config->ekind && file->emachine == config->emachine) {
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if (config->emachine != EM_MIPS)
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return true;
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if (isMipsN32Abi(file) == config->mipsN32Abi)
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return true;
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}
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StringRef target =
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!config->bfdname.empty() ? config->bfdname : config->emulation;
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if (!target.empty()) {
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error(toString(file) + " is incompatible with " + target);
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return false;
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}
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InputFile *existing;
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if (!objectFiles.empty())
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existing = objectFiles[0];
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else if (!sharedFiles.empty())
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existing = sharedFiles[0];
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else if (!bitcodeFiles.empty())
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existing = bitcodeFiles[0];
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else
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llvm_unreachable("Must have -m, OUTPUT_FORMAT or existing input file to "
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"determine target emulation");
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error(toString(file) + " is incompatible with " + toString(existing));
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return false;
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}
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template <class ELFT> static void doParseFile(InputFile *file) {
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if (!isCompatible(file))
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return;
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// Binary file
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if (auto *f = dyn_cast<BinaryFile>(file)) {
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binaryFiles.push_back(f);
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f->parse();
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return;
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}
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// .a file
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if (auto *f = dyn_cast<ArchiveFile>(file)) {
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archiveFiles.push_back(f);
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f->parse();
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return;
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}
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// Lazy object file
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if (file->lazy) {
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if (auto *f = dyn_cast<BitcodeFile>(file)) {
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lazyBitcodeFiles.push_back(f);
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f->parseLazy();
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} else {
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cast<ObjFile<ELFT>>(file)->parseLazy();
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}
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return;
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}
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if (config->trace)
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message(toString(file));
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// .so file
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if (auto *f = dyn_cast<SharedFile>(file)) {
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f->parse<ELFT>();
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return;
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}
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// LLVM bitcode file
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if (auto *f = dyn_cast<BitcodeFile>(file)) {
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bitcodeFiles.push_back(f);
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f->parse<ELFT>();
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return;
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}
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// Regular object file
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objectFiles.push_back(cast<ELFFileBase>(file));
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cast<ObjFile<ELFT>>(file)->parse();
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}
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// Add symbols in File to the symbol table.
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void elf::parseFile(InputFile *file) {
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switch (config->ekind) {
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case ELF32LEKind:
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doParseFile<ELF32LE>(file);
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return;
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case ELF32BEKind:
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doParseFile<ELF32BE>(file);
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return;
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case ELF64LEKind:
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doParseFile<ELF64LE>(file);
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return;
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case ELF64BEKind:
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doParseFile<ELF64BE>(file);
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return;
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default:
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llvm_unreachable("unknown ELFT");
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}
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}
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// Concatenates arguments to construct a string representing an error location.
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static std::string createFileLineMsg(StringRef path, unsigned line) {
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std::string filename = std::string(path::filename(path));
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std::string lineno = ":" + std::to_string(line);
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if (filename == path)
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return filename + lineno;
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return filename + lineno + " (" + path.str() + lineno + ")";
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}
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template <class ELFT>
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static std::string getSrcMsgAux(ObjFile<ELFT> &file, const Symbol &sym,
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InputSectionBase &sec, uint64_t offset) {
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// In DWARF, functions and variables are stored to different places.
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// First, lookup a function for a given offset.
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if (Optional<DILineInfo> info = file.getDILineInfo(&sec, offset))
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return createFileLineMsg(info->FileName, info->Line);
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// If it failed, lookup again as a variable.
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if (Optional<std::pair<std::string, unsigned>> fileLine =
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file.getVariableLoc(sym.getName()))
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return createFileLineMsg(fileLine->first, fileLine->second);
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// File.sourceFile contains STT_FILE symbol, and that is a last resort.
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return std::string(file.sourceFile);
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}
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std::string InputFile::getSrcMsg(const Symbol &sym, InputSectionBase &sec,
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uint64_t offset) {
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if (kind() != ObjKind)
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return "";
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switch (config->ekind) {
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default:
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llvm_unreachable("Invalid kind");
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case ELF32LEKind:
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return getSrcMsgAux(cast<ObjFile<ELF32LE>>(*this), sym, sec, offset);
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case ELF32BEKind:
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return getSrcMsgAux(cast<ObjFile<ELF32BE>>(*this), sym, sec, offset);
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case ELF64LEKind:
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return getSrcMsgAux(cast<ObjFile<ELF64LE>>(*this), sym, sec, offset);
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case ELF64BEKind:
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return getSrcMsgAux(cast<ObjFile<ELF64BE>>(*this), sym, sec, offset);
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}
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}
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StringRef InputFile::getNameForScript() const {
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if (archiveName.empty())
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return getName();
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if (nameForScriptCache.empty())
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nameForScriptCache = (archiveName + Twine(':') + getName()).str();
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return nameForScriptCache;
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}
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template <class ELFT> DWARFCache *ObjFile<ELFT>::getDwarf() {
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llvm::call_once(initDwarf, [this]() {
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dwarf = std::make_unique<DWARFCache>(std::make_unique<DWARFContext>(
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std::make_unique<LLDDwarfObj<ELFT>>(this), "",
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[&](Error err) { warn(getName() + ": " + toString(std::move(err))); },
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[&](Error warning) {
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warn(getName() + ": " + toString(std::move(warning)));
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}));
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});
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return dwarf.get();
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}
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// Returns the pair of file name and line number describing location of data
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// object (variable, array, etc) definition.
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template <class ELFT>
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Optional<std::pair<std::string, unsigned>>
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ObjFile<ELFT>::getVariableLoc(StringRef name) {
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return getDwarf()->getVariableLoc(name);
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}
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// Returns source line information for a given offset
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// using DWARF debug info.
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template <class ELFT>
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Optional<DILineInfo> ObjFile<ELFT>::getDILineInfo(InputSectionBase *s,
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uint64_t offset) {
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// Detect SectionIndex for specified section.
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uint64_t sectionIndex = object::SectionedAddress::UndefSection;
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ArrayRef<InputSectionBase *> sections = s->file->getSections();
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for (uint64_t curIndex = 0; curIndex < sections.size(); ++curIndex) {
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if (s == sections[curIndex]) {
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sectionIndex = curIndex;
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break;
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}
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}
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return getDwarf()->getDILineInfo(offset, sectionIndex);
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}
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ELFFileBase::ELFFileBase(Kind k, MemoryBufferRef mb) : InputFile(k, mb) {
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ekind = getELFKind(mb, "");
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switch (ekind) {
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case ELF32LEKind:
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init<ELF32LE>();
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break;
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case ELF32BEKind:
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init<ELF32BE>();
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break;
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case ELF64LEKind:
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init<ELF64LE>();
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break;
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case ELF64BEKind:
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init<ELF64BE>();
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break;
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default:
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llvm_unreachable("getELFKind");
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}
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}
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template <typename Elf_Shdr>
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static const Elf_Shdr *findSection(ArrayRef<Elf_Shdr> sections, uint32_t type) {
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for (const Elf_Shdr &sec : sections)
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if (sec.sh_type == type)
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return &sec;
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return nullptr;
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}
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template <class ELFT> void ELFFileBase::init() {
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using Elf_Shdr = typename ELFT::Shdr;
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using Elf_Sym = typename ELFT::Sym;
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// Initialize trivial attributes.
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const ELFFile<ELFT> &obj = getObj<ELFT>();
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emachine = obj.getHeader().e_machine;
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osabi = obj.getHeader().e_ident[llvm::ELF::EI_OSABI];
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abiVersion = obj.getHeader().e_ident[llvm::ELF::EI_ABIVERSION];
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ArrayRef<Elf_Shdr> sections = CHECK(obj.sections(), this);
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elfShdrs = sections.data();
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numELFShdrs = sections.size();
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// Find a symbol table.
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bool isDSO =
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(identify_magic(mb.getBuffer()) == file_magic::elf_shared_object);
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const Elf_Shdr *symtabSec =
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findSection(sections, isDSO ? SHT_DYNSYM : SHT_SYMTAB);
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if (!symtabSec)
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return;
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// Initialize members corresponding to a symbol table.
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firstGlobal = symtabSec->sh_info;
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ArrayRef<Elf_Sym> eSyms = CHECK(obj.symbols(symtabSec), this);
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if (firstGlobal == 0 || firstGlobal > eSyms.size())
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fatal(toString(this) + ": invalid sh_info in symbol table");
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elfSyms = reinterpret_cast<const void *>(eSyms.data());
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numELFSyms = uint32_t(eSyms.size());
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stringTable = CHECK(obj.getStringTableForSymtab(*symtabSec, sections), this);
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}
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template <class ELFT>
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uint32_t ObjFile<ELFT>::getSectionIndex(const Elf_Sym &sym) const {
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return CHECK(
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this->getObj().getSectionIndex(sym, getELFSyms<ELFT>(), shndxTable),
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this);
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}
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template <class ELFT> void ObjFile<ELFT>::parse(bool ignoreComdats) {
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// Read a section table. justSymbols is usually false.
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if (this->justSymbols)
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initializeJustSymbols();
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else
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initializeSections(ignoreComdats);
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// Read a symbol table.
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initializeSymbols();
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}
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// Sections with SHT_GROUP and comdat bits define comdat section groups.
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// They are identified and deduplicated by group name. This function
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// returns a group name.
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template <class ELFT>
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StringRef ObjFile<ELFT>::getShtGroupSignature(ArrayRef<Elf_Shdr> sections,
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const Elf_Shdr &sec) {
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typename ELFT::SymRange symbols = this->getELFSyms<ELFT>();
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if (sec.sh_info >= symbols.size())
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fatal(toString(this) + ": invalid symbol index");
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const typename ELFT::Sym &sym = symbols[sec.sh_info];
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return CHECK(sym.getName(this->stringTable), this);
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}
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template <class ELFT>
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bool ObjFile<ELFT>::shouldMerge(const Elf_Shdr &sec, StringRef name) {
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// On a regular link we don't merge sections if -O0 (default is -O1). This
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// sometimes makes the linker significantly faster, although the output will
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// be bigger.
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//
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// Doing the same for -r would create a problem as it would combine sections
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// with different sh_entsize. One option would be to just copy every SHF_MERGE
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// section as is to the output. While this would produce a valid ELF file with
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// usable SHF_MERGE sections, tools like (llvm-)?dwarfdump get confused when
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// they see two .debug_str. We could have separate logic for combining
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// SHF_MERGE sections based both on their name and sh_entsize, but that seems
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// to be more trouble than it is worth. Instead, we just use the regular (-O1)
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// logic for -r.
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if (config->optimize == 0 && !config->relocatable)
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return false;
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// A mergeable section with size 0 is useless because they don't have
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// any data to merge. A mergeable string section with size 0 can be
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// argued as invalid because it doesn't end with a null character.
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// We'll avoid a mess by handling them as if they were non-mergeable.
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if (sec.sh_size == 0)
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return false;
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// Check for sh_entsize. The ELF spec is not clear about the zero
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// sh_entsize. It says that "the member [sh_entsize] contains 0 if
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// the section does not hold a table of fixed-size entries". We know
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// that Rust 1.13 produces a string mergeable section with a zero
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// sh_entsize. Here we just accept it rather than being picky about it.
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uint64_t entSize = sec.sh_entsize;
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if (entSize == 0)
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return false;
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if (sec.sh_size % entSize)
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fatal(toString(this) + ":(" + name + "): SHF_MERGE section size (" +
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Twine(sec.sh_size) + ") must be a multiple of sh_entsize (" +
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Twine(entSize) + ")");
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if (sec.sh_flags & SHF_WRITE)
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fatal(toString(this) + ":(" + name +
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"): writable SHF_MERGE section is not supported");
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return true;
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}
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// This is for --just-symbols.
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//
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// --just-symbols is a very minor feature that allows you to link your
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// output against other existing program, so that if you load both your
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// program and the other program into memory, your output can refer the
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// other program's symbols.
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//
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// When the option is given, we link "just symbols". The section table is
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// initialized with null pointers.
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template <class ELFT> void ObjFile<ELFT>::initializeJustSymbols() {
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sections.resize(numELFShdrs);
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}
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|
|
// An ELF object file may contain a `.deplibs` section. If it exists, the
|
|
// section contains a list of library specifiers such as `m` for libm. This
|
|
// function resolves a given name by finding the first matching library checking
|
|
// the various ways that a library can be specified to LLD. This ELF extension
|
|
// is a form of autolinking and is called `dependent libraries`. It is currently
|
|
// unique to LLVM and lld.
|
|
static void addDependentLibrary(StringRef specifier, const InputFile *f) {
|
|
if (!config->dependentLibraries)
|
|
return;
|
|
if (fs::exists(specifier))
|
|
driver->addFile(specifier, /*withLOption=*/false);
|
|
else if (Optional<std::string> s = findFromSearchPaths(specifier))
|
|
driver->addFile(*s, /*withLOption=*/true);
|
|
else if (Optional<std::string> s = searchLibraryBaseName(specifier))
|
|
driver->addFile(*s, /*withLOption=*/true);
|
|
else
|
|
error(toString(f) +
|
|
": unable to find library from dependent library specifier: " +
|
|
specifier);
|
|
}
|
|
|
|
// Record the membership of a section group so that in the garbage collection
|
|
// pass, section group members are kept or discarded as a unit.
|
|
template <class ELFT>
|
|
static void handleSectionGroup(ArrayRef<InputSectionBase *> sections,
|
|
ArrayRef<typename ELFT::Word> entries) {
|
|
bool hasAlloc = false;
|
|
for (uint32_t index : entries.slice(1)) {
|
|
if (index >= sections.size())
|
|
return;
|
|
if (InputSectionBase *s = sections[index])
|
|
if (s != &InputSection::discarded && s->flags & SHF_ALLOC)
|
|
hasAlloc = true;
|
|
}
|
|
|
|
// If any member has the SHF_ALLOC flag, the whole group is subject to garbage
|
|
// collection. See the comment in markLive(). This rule retains .debug_types
|
|
// and .rela.debug_types.
|
|
if (!hasAlloc)
|
|
return;
|
|
|
|
// Connect the members in a circular doubly-linked list via
|
|
// nextInSectionGroup.
|
|
InputSectionBase *head;
|
|
InputSectionBase *prev = nullptr;
|
|
for (uint32_t index : entries.slice(1)) {
|
|
InputSectionBase *s = sections[index];
|
|
if (!s || s == &InputSection::discarded)
|
|
continue;
|
|
if (prev)
|
|
prev->nextInSectionGroup = s;
|
|
else
|
|
head = s;
|
|
prev = s;
|
|
}
|
|
if (prev)
|
|
prev->nextInSectionGroup = head;
|
|
}
|
|
|
|
template <class ELFT>
|
|
void ObjFile<ELFT>::initializeSections(bool ignoreComdats) {
|
|
const ELFFile<ELFT> &obj = this->getObj();
|
|
|
|
ArrayRef<Elf_Shdr> objSections = getELFShdrs<ELFT>();
|
|
StringRef shstrtab = CHECK(obj.getSectionStringTable(objSections), this);
|
|
uint64_t size = objSections.size();
|
|
this->sections.resize(size);
|
|
|
|
std::vector<ArrayRef<Elf_Word>> selectedGroups;
|
|
|
|
for (size_t i = 0, e = objSections.size(); i < e; ++i) {
|
|
if (this->sections[i] == &InputSection::discarded)
|
|
continue;
|
|
const Elf_Shdr &sec = objSections[i];
|
|
|
|
// SHF_EXCLUDE'ed sections are discarded by the linker. However,
|
|
// if -r is given, we'll let the final link discard such sections.
|
|
// This is compatible with GNU.
|
|
if ((sec.sh_flags & SHF_EXCLUDE) && !config->relocatable) {
|
|
if (sec.sh_type == SHT_LLVM_CALL_GRAPH_PROFILE)
|
|
cgProfileSectionIndex = i;
|
|
if (sec.sh_type == SHT_LLVM_ADDRSIG) {
|
|
// We ignore the address-significance table if we know that the object
|
|
// file was created by objcopy or ld -r. This is because these tools
|
|
// will reorder the symbols in the symbol table, invalidating the data
|
|
// in the address-significance table, which refers to symbols by index.
|
|
if (sec.sh_link != 0)
|
|
this->addrsigSec = &sec;
|
|
else if (config->icf == ICFLevel::Safe)
|
|
warn(toString(this) +
|
|
": --icf=safe conservatively ignores "
|
|
"SHT_LLVM_ADDRSIG [index " +
|
|
Twine(i) +
|
|
"] with sh_link=0 "
|
|
"(likely created using objcopy or ld -r)");
|
|
}
|
|
this->sections[i] = &InputSection::discarded;
|
|
continue;
|
|
}
|
|
|
|
switch (sec.sh_type) {
|
|
case SHT_GROUP: {
|
|
// De-duplicate section groups by their signatures.
|
|
StringRef signature = getShtGroupSignature(objSections, sec);
|
|
this->sections[i] = &InputSection::discarded;
|
|
|
|
ArrayRef<Elf_Word> entries =
|
|
CHECK(obj.template getSectionContentsAsArray<Elf_Word>(sec), this);
|
|
if (entries.empty())
|
|
fatal(toString(this) + ": empty SHT_GROUP");
|
|
|
|
Elf_Word flag = entries[0];
|
|
if (flag && flag != GRP_COMDAT)
|
|
fatal(toString(this) + ": unsupported SHT_GROUP format");
|
|
|
|
bool keepGroup =
|
|
(flag & GRP_COMDAT) == 0 || ignoreComdats ||
|
|
symtab->comdatGroups.try_emplace(CachedHashStringRef(signature), this)
|
|
.second;
|
|
if (keepGroup) {
|
|
if (config->relocatable)
|
|
this->sections[i] = createInputSection(i, sec, shstrtab);
|
|
selectedGroups.push_back(entries);
|
|
continue;
|
|
}
|
|
|
|
// Otherwise, discard group members.
|
|
for (uint32_t secIndex : entries.slice(1)) {
|
|
if (secIndex >= size)
|
|
fatal(toString(this) +
|
|
": invalid section index in group: " + Twine(secIndex));
|
|
this->sections[secIndex] = &InputSection::discarded;
|
|
}
|
|
break;
|
|
}
|
|
case SHT_SYMTAB_SHNDX:
|
|
shndxTable = CHECK(obj.getSHNDXTable(sec, objSections), this);
|
|
break;
|
|
case SHT_SYMTAB:
|
|
case SHT_STRTAB:
|
|
case SHT_REL:
|
|
case SHT_RELA:
|
|
case SHT_NULL:
|
|
break;
|
|
default:
|
|
this->sections[i] = createInputSection(i, sec, shstrtab);
|
|
}
|
|
}
|
|
|
|
// We have a second loop. It is used to:
|
|
// 1) handle SHF_LINK_ORDER sections.
|
|
// 2) create SHT_REL[A] sections. In some cases the section header index of a
|
|
// relocation section may be smaller than that of the relocated section. In
|
|
// such cases, the relocation section would attempt to reference a target
|
|
// section that has not yet been created. For simplicity, delay creation of
|
|
// relocation sections until now.
|
|
for (size_t i = 0, e = objSections.size(); i < e; ++i) {
|
|
if (this->sections[i] == &InputSection::discarded)
|
|
continue;
|
|
const Elf_Shdr &sec = objSections[i];
|
|
|
|
if (sec.sh_type == SHT_REL || sec.sh_type == SHT_RELA)
|
|
this->sections[i] = createInputSection(i, sec, shstrtab);
|
|
|
|
// A SHF_LINK_ORDER section with sh_link=0 is handled as if it did not have
|
|
// the flag.
|
|
if (!(sec.sh_flags & SHF_LINK_ORDER) || !sec.sh_link)
|
|
continue;
|
|
|
|
InputSectionBase *linkSec = nullptr;
|
|
if (sec.sh_link < this->sections.size())
|
|
linkSec = this->sections[sec.sh_link];
|
|
if (!linkSec)
|
|
fatal(toString(this) + ": invalid sh_link index: " + Twine(sec.sh_link));
|
|
|
|
// A SHF_LINK_ORDER section is discarded if its linked-to section is
|
|
// discarded.
|
|
InputSection *isec = cast<InputSection>(this->sections[i]);
|
|
linkSec->dependentSections.push_back(isec);
|
|
if (!isa<InputSection>(linkSec))
|
|
error("a section " + isec->name +
|
|
" with SHF_LINK_ORDER should not refer a non-regular section: " +
|
|
toString(linkSec));
|
|
}
|
|
|
|
for (ArrayRef<Elf_Word> entries : selectedGroups)
|
|
handleSectionGroup<ELFT>(this->sections, entries);
|
|
}
|
|
|
|
// For ARM only, to set the EF_ARM_ABI_FLOAT_SOFT or EF_ARM_ABI_FLOAT_HARD
|
|
// flag in the ELF Header we need to look at Tag_ABI_VFP_args to find out how
|
|
// the input objects have been compiled.
|
|
static void updateARMVFPArgs(const ARMAttributeParser &attributes,
|
|
const InputFile *f) {
|
|
Optional<unsigned> attr =
|
|
attributes.getAttributeValue(ARMBuildAttrs::ABI_VFP_args);
|
|
if (!attr.hasValue())
|
|
// If an ABI tag isn't present then it is implicitly given the value of 0
|
|
// which maps to ARMBuildAttrs::BaseAAPCS. However many assembler files,
|
|
// including some in glibc that don't use FP args (and should have value 3)
|
|
// don't have the attribute so we do not consider an implicit value of 0
|
|
// as a clash.
|
|
return;
|
|
|
|
unsigned vfpArgs = attr.getValue();
|
|
ARMVFPArgKind arg;
|
|
switch (vfpArgs) {
|
|
case ARMBuildAttrs::BaseAAPCS:
|
|
arg = ARMVFPArgKind::Base;
|
|
break;
|
|
case ARMBuildAttrs::HardFPAAPCS:
|
|
arg = ARMVFPArgKind::VFP;
|
|
break;
|
|
case ARMBuildAttrs::ToolChainFPPCS:
|
|
// Tool chain specific convention that conforms to neither AAPCS variant.
|
|
arg = ARMVFPArgKind::ToolChain;
|
|
break;
|
|
case ARMBuildAttrs::CompatibleFPAAPCS:
|
|
// Object compatible with all conventions.
|
|
return;
|
|
default:
|
|
error(toString(f) + ": unknown Tag_ABI_VFP_args value: " + Twine(vfpArgs));
|
|
return;
|
|
}
|
|
// Follow ld.bfd and error if there is a mix of calling conventions.
|
|
if (config->armVFPArgs != arg && config->armVFPArgs != ARMVFPArgKind::Default)
|
|
error(toString(f) + ": incompatible Tag_ABI_VFP_args");
|
|
else
|
|
config->armVFPArgs = arg;
|
|
}
|
|
|
|
// The ARM support in lld makes some use of instructions that are not available
|
|
// on all ARM architectures. Namely:
|
|
// - Use of BLX instruction for interworking between ARM and Thumb state.
|
|
// - Use of the extended Thumb branch encoding in relocation.
|
|
// - Use of the MOVT/MOVW instructions in Thumb Thunks.
|
|
// The ARM Attributes section contains information about the architecture chosen
|
|
// at compile time. We follow the convention that if at least one input object
|
|
// is compiled with an architecture that supports these features then lld is
|
|
// permitted to use them.
|
|
static void updateSupportedARMFeatures(const ARMAttributeParser &attributes) {
|
|
Optional<unsigned> attr =
|
|
attributes.getAttributeValue(ARMBuildAttrs::CPU_arch);
|
|
if (!attr.hasValue())
|
|
return;
|
|
auto arch = attr.getValue();
|
|
switch (arch) {
|
|
case ARMBuildAttrs::Pre_v4:
|
|
case ARMBuildAttrs::v4:
|
|
case ARMBuildAttrs::v4T:
|
|
// Architectures prior to v5 do not support BLX instruction
|
|
break;
|
|
case ARMBuildAttrs::v5T:
|
|
case ARMBuildAttrs::v5TE:
|
|
case ARMBuildAttrs::v5TEJ:
|
|
case ARMBuildAttrs::v6:
|
|
case ARMBuildAttrs::v6KZ:
|
|
case ARMBuildAttrs::v6K:
|
|
config->armHasBlx = true;
|
|
// Architectures used in pre-Cortex processors do not support
|
|
// The J1 = 1 J2 = 1 Thumb branch range extension, with the exception
|
|
// of Architecture v6T2 (arm1156t2-s and arm1156t2f-s) that do.
|
|
break;
|
|
default:
|
|
// All other Architectures have BLX and extended branch encoding
|
|
config->armHasBlx = true;
|
|
config->armJ1J2BranchEncoding = true;
|
|
if (arch != ARMBuildAttrs::v6_M && arch != ARMBuildAttrs::v6S_M)
|
|
// All Architectures used in Cortex processors with the exception
|
|
// of v6-M and v6S-M have the MOVT and MOVW instructions.
|
|
config->armHasMovtMovw = true;
|
|
break;
|
|
}
|
|
}
|
|
|
|
// If a source file is compiled with x86 hardware-assisted call flow control
|
|
// enabled, the generated object file contains feature flags indicating that
|
|
// fact. This function reads the feature flags and returns it.
|
|
//
|
|
// Essentially we want to read a single 32-bit value in this function, but this
|
|
// function is rather complicated because the value is buried deep inside a
|
|
// .note.gnu.property section.
|
|
//
|
|
// The section consists of one or more NOTE records. Each NOTE record consists
|
|
// of zero or more type-length-value fields. We want to find a field of a
|
|
// certain type. It seems a bit too much to just store a 32-bit value, perhaps
|
|
// the ABI is unnecessarily complicated.
|
|
template <class ELFT> static uint32_t readAndFeatures(const InputSection &sec) {
|
|
using Elf_Nhdr = typename ELFT::Nhdr;
|
|
using Elf_Note = typename ELFT::Note;
|
|
|
|
uint32_t featuresSet = 0;
|
|
ArrayRef<uint8_t> data = sec.data();
|
|
auto reportFatal = [&](const uint8_t *place, const char *msg) {
|
|
fatal(toString(sec.file) + ":(" + sec.name + "+0x" +
|
|
Twine::utohexstr(place - sec.data().data()) + "): " + msg);
|
|
};
|
|
while (!data.empty()) {
|
|
// Read one NOTE record.
|
|
auto *nhdr = reinterpret_cast<const Elf_Nhdr *>(data.data());
|
|
if (data.size() < sizeof(Elf_Nhdr) || data.size() < nhdr->getSize())
|
|
reportFatal(data.data(), "data is too short");
|
|
|
|
Elf_Note note(*nhdr);
|
|
if (nhdr->n_type != NT_GNU_PROPERTY_TYPE_0 || note.getName() != "GNU") {
|
|
data = data.slice(nhdr->getSize());
|
|
continue;
|
|
}
|
|
|
|
uint32_t featureAndType = config->emachine == EM_AARCH64
|
|
? GNU_PROPERTY_AARCH64_FEATURE_1_AND
|
|
: GNU_PROPERTY_X86_FEATURE_1_AND;
|
|
|
|
// Read a body of a NOTE record, which consists of type-length-value fields.
|
|
ArrayRef<uint8_t> desc = note.getDesc();
|
|
while (!desc.empty()) {
|
|
const uint8_t *place = desc.data();
|
|
if (desc.size() < 8)
|
|
reportFatal(place, "program property is too short");
|
|
uint32_t type = read32<ELFT::TargetEndianness>(desc.data());
|
|
uint32_t size = read32<ELFT::TargetEndianness>(desc.data() + 4);
|
|
desc = desc.slice(8);
|
|
if (desc.size() < size)
|
|
reportFatal(place, "program property is too short");
|
|
|
|
if (type == featureAndType) {
|
|
// We found a FEATURE_1_AND field. There may be more than one of these
|
|
// in a .note.gnu.property section, for a relocatable object we
|
|
// accumulate the bits set.
|
|
if (size < 4)
|
|
reportFatal(place, "FEATURE_1_AND entry is too short");
|
|
featuresSet |= read32<ELFT::TargetEndianness>(desc.data());
|
|
}
|
|
|
|
// Padding is present in the note descriptor, if necessary.
|
|
desc = desc.slice(alignTo<(ELFT::Is64Bits ? 8 : 4)>(size));
|
|
}
|
|
|
|
// Go to next NOTE record to look for more FEATURE_1_AND descriptions.
|
|
data = data.slice(nhdr->getSize());
|
|
}
|
|
|
|
return featuresSet;
|
|
}
|
|
|
|
template <class ELFT>
|
|
InputSectionBase *ObjFile<ELFT>::getRelocTarget(uint32_t idx, StringRef name,
|
|
const Elf_Shdr &sec) {
|
|
uint32_t info = sec.sh_info;
|
|
if (info < this->sections.size()) {
|
|
InputSectionBase *target = this->sections[info];
|
|
|
|
// Strictly speaking, a relocation section must be included in the
|
|
// group of the section it relocates. However, LLVM 3.3 and earlier
|
|
// would fail to do so, so we gracefully handle that case.
|
|
if (target == &InputSection::discarded)
|
|
return nullptr;
|
|
|
|
if (target != nullptr)
|
|
return target;
|
|
}
|
|
|
|
error(toString(this) + Twine(": relocation section ") + name + " (index " +
|
|
Twine(idx) + ") has invalid sh_info (" + Twine(info) + ")");
|
|
return nullptr;
|
|
}
|
|
|
|
// Create a regular InputSection class that has the same contents
|
|
// as a given section.
|
|
static InputSection *toRegularSection(MergeInputSection *sec) {
|
|
return make<InputSection>(sec->file, sec->flags, sec->type, sec->alignment,
|
|
sec->data(), sec->name);
|
|
}
|
|
|
|
template <class ELFT>
|
|
InputSectionBase *ObjFile<ELFT>::createInputSection(uint32_t idx,
|
|
const Elf_Shdr &sec,
|
|
StringRef shstrtab) {
|
|
StringRef name = CHECK(getObj().getSectionName(sec, shstrtab), this);
|
|
|
|
if (config->emachine == EM_ARM && sec.sh_type == SHT_ARM_ATTRIBUTES) {
|
|
ARMAttributeParser attributes;
|
|
ArrayRef<uint8_t> contents = check(this->getObj().getSectionContents(sec));
|
|
if (Error e = attributes.parse(contents, config->ekind == ELF32LEKind
|
|
? support::little
|
|
: support::big)) {
|
|
auto *isec = make<InputSection>(*this, sec, name);
|
|
warn(toString(isec) + ": " + llvm::toString(std::move(e)));
|
|
} else {
|
|
updateSupportedARMFeatures(attributes);
|
|
updateARMVFPArgs(attributes, this);
|
|
|
|
// FIXME: Retain the first attribute section we see. The eglibc ARM
|
|
// dynamic loaders require the presence of an attribute section for dlopen
|
|
// to work. In a full implementation we would merge all attribute
|
|
// sections.
|
|
if (in.attributes == nullptr) {
|
|
in.attributes = std::make_unique<InputSection>(*this, sec, name);
|
|
return in.attributes.get();
|
|
}
|
|
return &InputSection::discarded;
|
|
}
|
|
}
|
|
|
|
if (config->emachine == EM_RISCV && sec.sh_type == SHT_RISCV_ATTRIBUTES) {
|
|
RISCVAttributeParser attributes;
|
|
ArrayRef<uint8_t> contents = check(this->getObj().getSectionContents(sec));
|
|
if (Error e = attributes.parse(contents, support::little)) {
|
|
auto *isec = make<InputSection>(*this, sec, name);
|
|
warn(toString(isec) + ": " + llvm::toString(std::move(e)));
|
|
} else {
|
|
// FIXME: Validate arch tag contains C if and only if EF_RISCV_RVC is
|
|
// present.
|
|
|
|
// FIXME: Retain the first attribute section we see. Tools such as
|
|
// llvm-objdump make use of the attribute section to determine which
|
|
// standard extensions to enable. In a full implementation we would merge
|
|
// all attribute sections.
|
|
if (in.attributes == nullptr) {
|
|
in.attributes = std::make_unique<InputSection>(*this, sec, name);
|
|
return in.attributes.get();
|
|
}
|
|
return &InputSection::discarded;
|
|
}
|
|
}
|
|
|
|
switch (sec.sh_type) {
|
|
case SHT_LLVM_DEPENDENT_LIBRARIES: {
|
|
if (config->relocatable)
|
|
break;
|
|
ArrayRef<char> data =
|
|
CHECK(this->getObj().template getSectionContentsAsArray<char>(sec), this);
|
|
if (!data.empty() && data.back() != '\0') {
|
|
error(toString(this) +
|
|
": corrupted dependent libraries section (unterminated string): " +
|
|
name);
|
|
return &InputSection::discarded;
|
|
}
|
|
for (const char *d = data.begin(), *e = data.end(); d < e;) {
|
|
StringRef s(d);
|
|
addDependentLibrary(s, this);
|
|
d += s.size() + 1;
|
|
}
|
|
return &InputSection::discarded;
|
|
}
|
|
case SHT_RELA:
|
|
case SHT_REL: {
|
|
// Find a relocation target section and associate this section with that.
|
|
// Target may have been discarded if it is in a different section group
|
|
// and the group is discarded, even though it's a violation of the
|
|
// spec. We handle that situation gracefully by discarding dangling
|
|
// relocation sections.
|
|
InputSectionBase *target = getRelocTarget(idx, name, sec);
|
|
if (!target)
|
|
return nullptr;
|
|
|
|
// ELF spec allows mergeable sections with relocations, but they are
|
|
// rare, and it is in practice hard to merge such sections by contents,
|
|
// because applying relocations at end of linking changes section
|
|
// contents. So, we simply handle such sections as non-mergeable ones.
|
|
// Degrading like this is acceptable because section merging is optional.
|
|
if (auto *ms = dyn_cast<MergeInputSection>(target)) {
|
|
target = toRegularSection(ms);
|
|
this->sections[sec.sh_info] = target;
|
|
}
|
|
|
|
if (target->relSecIdx != 0)
|
|
fatal(toString(this) +
|
|
": multiple relocation sections to one section are not supported");
|
|
target->relSecIdx = idx;
|
|
|
|
// Relocation sections are usually removed from the output, so return
|
|
// `nullptr` for the normal case. However, if -r or --emit-relocs is
|
|
// specified, we need to copy them to the output. (Some post link analysis
|
|
// tools specify --emit-relocs to obtain the information.)
|
|
if (!config->copyRelocs)
|
|
return nullptr;
|
|
InputSection *relocSec = make<InputSection>(*this, sec, name);
|
|
// If the relocated section is discarded (due to /DISCARD/ or
|
|
// --gc-sections), the relocation section should be discarded as well.
|
|
target->dependentSections.push_back(relocSec);
|
|
return relocSec;
|
|
}
|
|
}
|
|
|
|
if (name.startswith(".n")) {
|
|
// The GNU linker uses .note.GNU-stack section as a marker indicating
|
|
// that the code in the object file does not expect that the stack is
|
|
// executable (in terms of NX bit). If all input files have the marker,
|
|
// the GNU linker adds a PT_GNU_STACK segment to tells the loader to
|
|
// make the stack non-executable. Most object files have this section as
|
|
// of 2017.
|
|
//
|
|
// But making the stack non-executable is a norm today for security
|
|
// reasons. Failure to do so may result in a serious security issue.
|
|
// Therefore, we make LLD always add PT_GNU_STACK unless it is
|
|
// explicitly told to do otherwise (by -z execstack). Because the stack
|
|
// executable-ness is controlled solely by command line options,
|
|
// .note.GNU-stack sections are simply ignored.
|
|
if (name == ".note.GNU-stack")
|
|
return &InputSection::discarded;
|
|
|
|
// Object files that use processor features such as Intel Control-Flow
|
|
// Enforcement (CET) or AArch64 Branch Target Identification BTI, use a
|
|
// .note.gnu.property section containing a bitfield of feature bits like the
|
|
// GNU_PROPERTY_X86_FEATURE_1_IBT flag. Read a bitmap containing the flag.
|
|
//
|
|
// Since we merge bitmaps from multiple object files to create a new
|
|
// .note.gnu.property containing a single AND'ed bitmap, we discard an input
|
|
// file's .note.gnu.property section.
|
|
if (name == ".note.gnu.property") {
|
|
this->andFeatures = readAndFeatures<ELFT>(InputSection(*this, sec, name));
|
|
return &InputSection::discarded;
|
|
}
|
|
|
|
// Split stacks is a feature to support a discontiguous stack,
|
|
// commonly used in the programming language Go. For the details,
|
|
// see https://gcc.gnu.org/wiki/SplitStacks. An object file compiled
|
|
// for split stack will include a .note.GNU-split-stack section.
|
|
if (name == ".note.GNU-split-stack") {
|
|
if (config->relocatable) {
|
|
error(
|
|
"cannot mix split-stack and non-split-stack in a relocatable link");
|
|
return &InputSection::discarded;
|
|
}
|
|
this->splitStack = true;
|
|
return &InputSection::discarded;
|
|
}
|
|
|
|
// An object file cmpiled for split stack, but where some of the
|
|
// functions were compiled with the no_split_stack_attribute will
|
|
// include a .note.GNU-no-split-stack section.
|
|
if (name == ".note.GNU-no-split-stack") {
|
|
this->someNoSplitStack = true;
|
|
return &InputSection::discarded;
|
|
}
|
|
|
|
// Strip existing .note.gnu.build-id sections so that the output won't have
|
|
// more than one build-id. This is not usually a problem because input
|
|
// object files normally don't have .build-id sections, but you can create
|
|
// such files by "ld.{bfd,gold,lld} -r --build-id", and we want to guard
|
|
// against it.
|
|
if (name == ".note.gnu.build-id")
|
|
return &InputSection::discarded;
|
|
}
|
|
|
|
// The linkonce feature is a sort of proto-comdat. Some glibc i386 object
|
|
// files contain definitions of symbol "__x86.get_pc_thunk.bx" in linkonce
|
|
// sections. Drop those sections to avoid duplicate symbol errors.
|
|
// FIXME: This is glibc PR20543, we should remove this hack once that has been
|
|
// fixed for a while.
|
|
if (name == ".gnu.linkonce.t.__x86.get_pc_thunk.bx" ||
|
|
name == ".gnu.linkonce.t.__i686.get_pc_thunk.bx")
|
|
return &InputSection::discarded;
|
|
|
|
// The linker merges EH (exception handling) frames and creates a
|
|
// .eh_frame_hdr section for runtime. So we handle them with a special
|
|
// class. For relocatable outputs, they are just passed through.
|
|
if (name == ".eh_frame" && !config->relocatable)
|
|
return make<EhInputSection>(*this, sec, name);
|
|
|
|
if ((sec.sh_flags & SHF_MERGE) && shouldMerge(sec, name))
|
|
return make<MergeInputSection>(*this, sec, name);
|
|
return make<InputSection>(*this, sec, name);
|
|
}
|
|
|
|
// Initialize this->Symbols. this->Symbols is a parallel array as
|
|
// its corresponding ELF symbol table.
|
|
template <class ELFT> void ObjFile<ELFT>::initializeSymbols() {
|
|
ArrayRef<InputSectionBase *> sections(this->sections);
|
|
SymbolTable &symtab = *elf::symtab;
|
|
|
|
ArrayRef<Elf_Sym> eSyms = this->getELFSyms<ELFT>();
|
|
symbols.resize(eSyms.size());
|
|
SymbolUnion *locals =
|
|
firstGlobal == 0
|
|
? nullptr
|
|
: getSpecificAllocSingleton<SymbolUnion>().Allocate(firstGlobal);
|
|
|
|
for (size_t i = 0, end = firstGlobal; i != end; ++i) {
|
|
const Elf_Sym &eSym = eSyms[i];
|
|
uint32_t secIdx = getSectionIndex(eSym);
|
|
if (LLVM_UNLIKELY(secIdx >= sections.size()))
|
|
fatal(toString(this) + ": invalid section index: " + Twine(secIdx));
|
|
if (LLVM_UNLIKELY(eSym.getBinding() != STB_LOCAL))
|
|
error(toString(this) + ": non-local symbol (" + Twine(i) +
|
|
") found at index < .symtab's sh_info (" + Twine(end) + ")");
|
|
|
|
InputSectionBase *sec = sections[secIdx];
|
|
uint8_t type = eSym.getType();
|
|
if (type == STT_FILE)
|
|
sourceFile = CHECK(eSym.getName(stringTable), this);
|
|
if (LLVM_UNLIKELY(stringTable.size() <= eSym.st_name))
|
|
fatal(toString(this) + ": invalid symbol name offset");
|
|
StringRefZ name = stringTable.data() + eSym.st_name;
|
|
|
|
symbols[i] = reinterpret_cast<Symbol *>(locals + i);
|
|
if (eSym.st_shndx == SHN_UNDEF || sec == &InputSection::discarded)
|
|
new (symbols[i]) Undefined(this, name, STB_LOCAL, eSym.st_other, type,
|
|
/*discardedSecIdx=*/secIdx);
|
|
else
|
|
new (symbols[i]) Defined(this, name, STB_LOCAL, eSym.st_other, type,
|
|
eSym.st_value, eSym.st_size, sec);
|
|
}
|
|
|
|
// Some entries have been filled by LazyObjFile.
|
|
for (size_t i = firstGlobal, end = eSyms.size(); i != end; ++i)
|
|
if (!symbols[i])
|
|
symbols[i] = symtab.insert(CHECK(eSyms[i].getName(stringTable), this));
|
|
|
|
// Perform symbol resolution on non-local symbols.
|
|
SmallVector<unsigned, 32> undefineds;
|
|
for (size_t i = firstGlobal, end = eSyms.size(); i != end; ++i) {
|
|
const Elf_Sym &eSym = eSyms[i];
|
|
uint8_t binding = eSym.getBinding();
|
|
if (LLVM_UNLIKELY(binding == STB_LOCAL)) {
|
|
errorOrWarn(toString(this) + ": STB_LOCAL symbol (" + Twine(i) +
|
|
") found at index >= .symtab's sh_info (" +
|
|
Twine(firstGlobal) + ")");
|
|
continue;
|
|
}
|
|
uint32_t secIdx = getSectionIndex(eSym);
|
|
if (LLVM_UNLIKELY(secIdx >= sections.size()))
|
|
fatal(toString(this) + ": invalid section index: " + Twine(secIdx));
|
|
InputSectionBase *sec = sections[secIdx];
|
|
uint8_t stOther = eSym.st_other;
|
|
uint8_t type = eSym.getType();
|
|
uint64_t value = eSym.st_value;
|
|
uint64_t size = eSym.st_size;
|
|
|
|
if (eSym.st_shndx == SHN_UNDEF) {
|
|
undefineds.push_back(i);
|
|
continue;
|
|
}
|
|
|
|
Symbol *sym = symbols[i];
|
|
const StringRef name = sym->getName();
|
|
if (LLVM_UNLIKELY(eSym.st_shndx == SHN_COMMON)) {
|
|
if (value == 0 || value >= UINT32_MAX)
|
|
fatal(toString(this) + ": common symbol '" + name +
|
|
"' has invalid alignment: " + Twine(value));
|
|
hasCommonSyms = true;
|
|
sym->resolve(
|
|
CommonSymbol{this, name, binding, stOther, type, value, size});
|
|
continue;
|
|
}
|
|
|
|
// If a defined symbol is in a discarded section, handle it as if it
|
|
// were an undefined symbol. Such symbol doesn't comply with the
|
|
// standard, but in practice, a .eh_frame often directly refer
|
|
// COMDAT member sections, and if a comdat group is discarded, some
|
|
// defined symbol in a .eh_frame becomes dangling symbols.
|
|
if (sec == &InputSection::discarded) {
|
|
Undefined und{this, name, binding, stOther, type, secIdx};
|
|
// !ArchiveFile::parsed or !LazyObjFile::lazy means that the file
|
|
// containing this object has not finished processing, i.e. this symbol is
|
|
// a result of a lazy symbol extract. We should demote the lazy symbol to
|
|
// an Undefined so that any relocations outside of the group to it will
|
|
// trigger a discarded section error.
|
|
if ((sym->symbolKind == Symbol::LazyArchiveKind &&
|
|
!cast<ArchiveFile>(sym->file)->parsed) ||
|
|
(sym->symbolKind == Symbol::LazyObjectKind && !sym->file->lazy)) {
|
|
sym->replace(und);
|
|
// Prevent LTO from internalizing the symbol in case there is a
|
|
// reference to this symbol from this file.
|
|
sym->isUsedInRegularObj = true;
|
|
} else
|
|
sym->resolve(und);
|
|
continue;
|
|
}
|
|
|
|
// Handle global defined symbols.
|
|
if (binding == STB_GLOBAL || binding == STB_WEAK ||
|
|
binding == STB_GNU_UNIQUE) {
|
|
sym->resolve(
|
|
Defined{this, name, binding, stOther, type, value, size, sec});
|
|
continue;
|
|
}
|
|
|
|
fatal(toString(this) + ": unexpected binding: " + Twine((int)binding));
|
|
}
|
|
|
|
// Undefined symbols (excluding those defined relative to non-prevailing
|
|
// sections) can trigger recursive extract. Process defined symbols first so
|
|
// that the relative order between a defined symbol and an undefined symbol
|
|
// does not change the symbol resolution behavior. In addition, a set of
|
|
// interconnected symbols will all be resolved to the same file, instead of
|
|
// being resolved to different files.
|
|
for (unsigned i : undefineds) {
|
|
const Elf_Sym &eSym = eSyms[i];
|
|
Symbol *sym = symbols[i];
|
|
sym->resolve(Undefined{this, sym->getName(), eSym.getBinding(),
|
|
eSym.st_other, eSym.getType()});
|
|
sym->referenced = true;
|
|
}
|
|
}
|
|
|
|
ArchiveFile::ArchiveFile(std::unique_ptr<Archive> &&file)
|
|
: InputFile(ArchiveKind, file->getMemoryBufferRef()),
|
|
file(std::move(file)) {}
|
|
|
|
void ArchiveFile::parse() {
|
|
SymbolTable &symtab = *elf::symtab;
|
|
for (const Archive::Symbol &sym : file->symbols())
|
|
symtab.addSymbol(LazyArchive{*this, sym});
|
|
|
|
// Inform a future invocation of ObjFile<ELFT>::initializeSymbols() that this
|
|
// archive has been processed.
|
|
parsed = true;
|
|
}
|
|
|
|
// Returns a buffer pointing to a member file containing a given symbol.
|
|
void ArchiveFile::extract(const Archive::Symbol &sym) {
|
|
Archive::Child c =
|
|
CHECK(sym.getMember(), toString(this) +
|
|
": could not get the member for symbol " +
|
|
toELFString(sym));
|
|
|
|
if (!seen.insert(c.getChildOffset()).second)
|
|
return;
|
|
|
|
MemoryBufferRef mb =
|
|
CHECK(c.getMemoryBufferRef(),
|
|
toString(this) +
|
|
": could not get the buffer for the member defining symbol " +
|
|
toELFString(sym));
|
|
|
|
if (tar && c.getParent()->isThin())
|
|
tar->append(relativeToRoot(CHECK(c.getFullName(), this)), mb.getBuffer());
|
|
|
|
InputFile *file = createObjectFile(mb, getName(), c.getChildOffset());
|
|
file->groupId = groupId;
|
|
parseFile(file);
|
|
}
|
|
|
|
// The handling of tentative definitions (COMMON symbols) in archives is murky.
|
|
// A tentative definition will be promoted to a global definition if there are
|
|
// no non-tentative definitions to dominate it. When we hold a tentative
|
|
// definition to a symbol and are inspecting archive members for inclusion
|
|
// there are 2 ways we can proceed:
|
|
//
|
|
// 1) Consider the tentative definition a 'real' definition (ie promotion from
|
|
// tentative to real definition has already happened) and not inspect
|
|
// archive members for Global/Weak definitions to replace the tentative
|
|
// definition. An archive member would only be included if it satisfies some
|
|
// other undefined symbol. This is the behavior Gold uses.
|
|
//
|
|
// 2) Consider the tentative definition as still undefined (ie the promotion to
|
|
// a real definition happens only after all symbol resolution is done).
|
|
// The linker searches archive members for STB_GLOBAL definitions to
|
|
// replace the tentative definition with. This is the behavior used by
|
|
// GNU ld.
|
|
//
|
|
// The second behavior is inherited from SysVR4, which based it on the FORTRAN
|
|
// COMMON BLOCK model. This behavior is needed for proper initialization in old
|
|
// (pre F90) FORTRAN code that is packaged into an archive.
|
|
//
|
|
// The following functions search archive members for definitions to replace
|
|
// tentative definitions (implementing behavior 2).
|
|
static bool isBitcodeNonCommonDef(MemoryBufferRef mb, StringRef symName,
|
|
StringRef archiveName) {
|
|
IRSymtabFile symtabFile = check(readIRSymtab(mb));
|
|
for (const irsymtab::Reader::SymbolRef &sym :
|
|
symtabFile.TheReader.symbols()) {
|
|
if (sym.isGlobal() && sym.getName() == symName)
|
|
return !sym.isUndefined() && !sym.isWeak() && !sym.isCommon();
|
|
}
|
|
return false;
|
|
}
|
|
|
|
template <class ELFT>
|
|
static bool isNonCommonDef(MemoryBufferRef mb, StringRef symName,
|
|
StringRef archiveName) {
|
|
ObjFile<ELFT> *obj = make<ObjFile<ELFT>>(mb, archiveName);
|
|
StringRef stringtable = obj->getStringTable();
|
|
|
|
for (auto sym : obj->template getGlobalELFSyms<ELFT>()) {
|
|
Expected<StringRef> name = sym.getName(stringtable);
|
|
if (name && name.get() == symName)
|
|
return sym.isDefined() && sym.getBinding() == STB_GLOBAL &&
|
|
!sym.isCommon();
|
|
}
|
|
return false;
|
|
}
|
|
|
|
static bool isNonCommonDef(MemoryBufferRef mb, StringRef symName,
|
|
StringRef archiveName) {
|
|
switch (getELFKind(mb, archiveName)) {
|
|
case ELF32LEKind:
|
|
return isNonCommonDef<ELF32LE>(mb, symName, archiveName);
|
|
case ELF32BEKind:
|
|
return isNonCommonDef<ELF32BE>(mb, symName, archiveName);
|
|
case ELF64LEKind:
|
|
return isNonCommonDef<ELF64LE>(mb, symName, archiveName);
|
|
case ELF64BEKind:
|
|
return isNonCommonDef<ELF64BE>(mb, symName, archiveName);
|
|
default:
|
|
llvm_unreachable("getELFKind");
|
|
}
|
|
}
|
|
|
|
bool ArchiveFile::shouldExtractForCommon(const Archive::Symbol &sym) {
|
|
Archive::Child c =
|
|
CHECK(sym.getMember(), toString(this) +
|
|
": could not get the member for symbol " +
|
|
toELFString(sym));
|
|
MemoryBufferRef mb =
|
|
CHECK(c.getMemoryBufferRef(),
|
|
toString(this) +
|
|
": could not get the buffer for the member defining symbol " +
|
|
toELFString(sym));
|
|
|
|
if (isBitcode(mb))
|
|
return isBitcodeNonCommonDef(mb, sym.getName(), getName());
|
|
|
|
return isNonCommonDef(mb, sym.getName(), getName());
|
|
}
|
|
|
|
size_t ArchiveFile::getMemberCount() const {
|
|
size_t count = 0;
|
|
Error err = Error::success();
|
|
for (const Archive::Child &c : file->children(err)) {
|
|
(void)c;
|
|
++count;
|
|
}
|
|
// This function is used by --print-archive-stats=, where an error does not
|
|
// really matter.
|
|
consumeError(std::move(err));
|
|
return count;
|
|
}
|
|
|
|
unsigned SharedFile::vernauxNum;
|
|
|
|
// Parse the version definitions in the object file if present, and return a
|
|
// vector whose nth element contains a pointer to the Elf_Verdef for version
|
|
// identifier n. Version identifiers that are not definitions map to nullptr.
|
|
template <typename ELFT>
|
|
static SmallVector<const void *, 0>
|
|
parseVerdefs(const uint8_t *base, const typename ELFT::Shdr *sec) {
|
|
if (!sec)
|
|
return {};
|
|
|
|
// Build the Verdefs array by following the chain of Elf_Verdef objects
|
|
// from the start of the .gnu.version_d section.
|
|
SmallVector<const void *, 0> verdefs;
|
|
const uint8_t *verdef = base + sec->sh_offset;
|
|
for (unsigned i = 0, e = sec->sh_info; i != e; ++i) {
|
|
auto *curVerdef = reinterpret_cast<const typename ELFT::Verdef *>(verdef);
|
|
verdef += curVerdef->vd_next;
|
|
unsigned verdefIndex = curVerdef->vd_ndx;
|
|
if (verdefIndex >= verdefs.size())
|
|
verdefs.resize(verdefIndex + 1);
|
|
verdefs[verdefIndex] = curVerdef;
|
|
}
|
|
return verdefs;
|
|
}
|
|
|
|
// Parse SHT_GNU_verneed to properly set the name of a versioned undefined
|
|
// symbol. We detect fatal issues which would cause vulnerabilities, but do not
|
|
// implement sophisticated error checking like in llvm-readobj because the value
|
|
// of such diagnostics is low.
|
|
template <typename ELFT>
|
|
std::vector<uint32_t> SharedFile::parseVerneed(const ELFFile<ELFT> &obj,
|
|
const typename ELFT::Shdr *sec) {
|
|
if (!sec)
|
|
return {};
|
|
std::vector<uint32_t> verneeds;
|
|
ArrayRef<uint8_t> data = CHECK(obj.getSectionContents(*sec), this);
|
|
const uint8_t *verneedBuf = data.begin();
|
|
for (unsigned i = 0; i != sec->sh_info; ++i) {
|
|
if (verneedBuf + sizeof(typename ELFT::Verneed) > data.end())
|
|
fatal(toString(this) + " has an invalid Verneed");
|
|
auto *vn = reinterpret_cast<const typename ELFT::Verneed *>(verneedBuf);
|
|
const uint8_t *vernauxBuf = verneedBuf + vn->vn_aux;
|
|
for (unsigned j = 0; j != vn->vn_cnt; ++j) {
|
|
if (vernauxBuf + sizeof(typename ELFT::Vernaux) > data.end())
|
|
fatal(toString(this) + " has an invalid Vernaux");
|
|
auto *aux = reinterpret_cast<const typename ELFT::Vernaux *>(vernauxBuf);
|
|
if (aux->vna_name >= this->stringTable.size())
|
|
fatal(toString(this) + " has a Vernaux with an invalid vna_name");
|
|
uint16_t version = aux->vna_other & VERSYM_VERSION;
|
|
if (version >= verneeds.size())
|
|
verneeds.resize(version + 1);
|
|
verneeds[version] = aux->vna_name;
|
|
vernauxBuf += aux->vna_next;
|
|
}
|
|
verneedBuf += vn->vn_next;
|
|
}
|
|
return verneeds;
|
|
}
|
|
|
|
// We do not usually care about alignments of data in shared object
|
|
// files because the loader takes care of it. However, if we promote a
|
|
// DSO symbol to point to .bss due to copy relocation, we need to keep
|
|
// the original alignment requirements. We infer it in this function.
|
|
template <typename ELFT>
|
|
static uint64_t getAlignment(ArrayRef<typename ELFT::Shdr> sections,
|
|
const typename ELFT::Sym &sym) {
|
|
uint64_t ret = UINT64_MAX;
|
|
if (sym.st_value)
|
|
ret = 1ULL << countTrailingZeros((uint64_t)sym.st_value);
|
|
if (0 < sym.st_shndx && sym.st_shndx < sections.size())
|
|
ret = std::min<uint64_t>(ret, sections[sym.st_shndx].sh_addralign);
|
|
return (ret > UINT32_MAX) ? 0 : ret;
|
|
}
|
|
|
|
// Fully parse the shared object file.
|
|
//
|
|
// This function parses symbol versions. If a DSO has version information,
|
|
// the file has a ".gnu.version_d" section which contains symbol version
|
|
// definitions. Each symbol is associated to one version through a table in
|
|
// ".gnu.version" section. That table is a parallel array for the symbol
|
|
// table, and each table entry contains an index in ".gnu.version_d".
|
|
//
|
|
// The special index 0 is reserved for VERF_NDX_LOCAL and 1 is for
|
|
// VER_NDX_GLOBAL. There's no table entry for these special versions in
|
|
// ".gnu.version_d".
|
|
//
|
|
// The file format for symbol versioning is perhaps a bit more complicated
|
|
// than necessary, but you can easily understand the code if you wrap your
|
|
// head around the data structure described above.
|
|
template <class ELFT> void SharedFile::parse() {
|
|
using Elf_Dyn = typename ELFT::Dyn;
|
|
using Elf_Shdr = typename ELFT::Shdr;
|
|
using Elf_Sym = typename ELFT::Sym;
|
|
using Elf_Verdef = typename ELFT::Verdef;
|
|
using Elf_Versym = typename ELFT::Versym;
|
|
|
|
ArrayRef<Elf_Dyn> dynamicTags;
|
|
const ELFFile<ELFT> obj = this->getObj<ELFT>();
|
|
ArrayRef<Elf_Shdr> sections = getELFShdrs<ELFT>();
|
|
|
|
const Elf_Shdr *versymSec = nullptr;
|
|
const Elf_Shdr *verdefSec = nullptr;
|
|
const Elf_Shdr *verneedSec = nullptr;
|
|
|
|
// Search for .dynsym, .dynamic, .symtab, .gnu.version and .gnu.version_d.
|
|
for (const Elf_Shdr &sec : sections) {
|
|
switch (sec.sh_type) {
|
|
default:
|
|
continue;
|
|
case SHT_DYNAMIC:
|
|
dynamicTags =
|
|
CHECK(obj.template getSectionContentsAsArray<Elf_Dyn>(sec), this);
|
|
break;
|
|
case SHT_GNU_versym:
|
|
versymSec = &sec;
|
|
break;
|
|
case SHT_GNU_verdef:
|
|
verdefSec = &sec;
|
|
break;
|
|
case SHT_GNU_verneed:
|
|
verneedSec = &sec;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (versymSec && numELFSyms == 0) {
|
|
error("SHT_GNU_versym should be associated with symbol table");
|
|
return;
|
|
}
|
|
|
|
// Search for a DT_SONAME tag to initialize this->soName.
|
|
for (const Elf_Dyn &dyn : dynamicTags) {
|
|
if (dyn.d_tag == DT_NEEDED) {
|
|
uint64_t val = dyn.getVal();
|
|
if (val >= this->stringTable.size())
|
|
fatal(toString(this) + ": invalid DT_NEEDED entry");
|
|
dtNeeded.push_back(this->stringTable.data() + val);
|
|
} else if (dyn.d_tag == DT_SONAME) {
|
|
uint64_t val = dyn.getVal();
|
|
if (val >= this->stringTable.size())
|
|
fatal(toString(this) + ": invalid DT_SONAME entry");
|
|
soName = this->stringTable.data() + val;
|
|
}
|
|
}
|
|
|
|
// DSOs are uniquified not by filename but by soname.
|
|
DenseMap<StringRef, SharedFile *>::iterator it;
|
|
bool wasInserted;
|
|
std::tie(it, wasInserted) = symtab->soNames.try_emplace(soName, this);
|
|
|
|
// If a DSO appears more than once on the command line with and without
|
|
// --as-needed, --no-as-needed takes precedence over --as-needed because a
|
|
// user can add an extra DSO with --no-as-needed to force it to be added to
|
|
// the dependency list.
|
|
it->second->isNeeded |= isNeeded;
|
|
if (!wasInserted)
|
|
return;
|
|
|
|
sharedFiles.push_back(this);
|
|
|
|
verdefs = parseVerdefs<ELFT>(obj.base(), verdefSec);
|
|
std::vector<uint32_t> verneeds = parseVerneed<ELFT>(obj, verneedSec);
|
|
|
|
// Parse ".gnu.version" section which is a parallel array for the symbol
|
|
// table. If a given file doesn't have a ".gnu.version" section, we use
|
|
// VER_NDX_GLOBAL.
|
|
size_t size = numELFSyms - firstGlobal;
|
|
std::vector<uint16_t> versyms(size, VER_NDX_GLOBAL);
|
|
if (versymSec) {
|
|
ArrayRef<Elf_Versym> versym =
|
|
CHECK(obj.template getSectionContentsAsArray<Elf_Versym>(*versymSec),
|
|
this)
|
|
.slice(firstGlobal);
|
|
for (size_t i = 0; i < size; ++i)
|
|
versyms[i] = versym[i].vs_index;
|
|
}
|
|
|
|
// System libraries can have a lot of symbols with versions. Using a
|
|
// fixed buffer for computing the versions name (foo@ver) can save a
|
|
// lot of allocations.
|
|
SmallString<0> versionedNameBuffer;
|
|
|
|
// Add symbols to the symbol table.
|
|
SymbolTable &symtab = *elf::symtab;
|
|
ArrayRef<Elf_Sym> syms = this->getGlobalELFSyms<ELFT>();
|
|
for (size_t i = 0, e = syms.size(); i != e; ++i) {
|
|
const Elf_Sym &sym = syms[i];
|
|
|
|
// ELF spec requires that all local symbols precede weak or global
|
|
// symbols in each symbol table, and the index of first non-local symbol
|
|
// is stored to sh_info. If a local symbol appears after some non-local
|
|
// symbol, that's a violation of the spec.
|
|
StringRef name = CHECK(sym.getName(stringTable), this);
|
|
if (sym.getBinding() == STB_LOCAL) {
|
|
warn("found local symbol '" + name +
|
|
"' in global part of symbol table in file " + toString(this));
|
|
continue;
|
|
}
|
|
|
|
uint16_t idx = versyms[i] & ~VERSYM_HIDDEN;
|
|
if (sym.isUndefined()) {
|
|
// For unversioned undefined symbols, VER_NDX_GLOBAL makes more sense but
|
|
// as of binutils 2.34, GNU ld produces VER_NDX_LOCAL.
|
|
if (idx != VER_NDX_LOCAL && idx != VER_NDX_GLOBAL) {
|
|
if (idx >= verneeds.size()) {
|
|
error("corrupt input file: version need index " + Twine(idx) +
|
|
" for symbol " + name + " is out of bounds\n>>> defined in " +
|
|
toString(this));
|
|
continue;
|
|
}
|
|
StringRef verName = stringTable.data() + verneeds[idx];
|
|
versionedNameBuffer.clear();
|
|
name =
|
|
saver.save((name + "@" + verName).toStringRef(versionedNameBuffer));
|
|
}
|
|
Symbol *s = symtab.addSymbol(
|
|
Undefined{this, name, sym.getBinding(), sym.st_other, sym.getType()});
|
|
s->exportDynamic = true;
|
|
if (s->isUndefined() && sym.getBinding() != STB_WEAK &&
|
|
config->unresolvedSymbolsInShlib != UnresolvedPolicy::Ignore)
|
|
requiredSymbols.push_back(s);
|
|
continue;
|
|
}
|
|
|
|
// MIPS BFD linker puts _gp_disp symbol into DSO files and incorrectly
|
|
// assigns VER_NDX_LOCAL to this section global symbol. Here is a
|
|
// workaround for this bug.
|
|
if (config->emachine == EM_MIPS && idx == VER_NDX_LOCAL &&
|
|
name == "_gp_disp")
|
|
continue;
|
|
|
|
uint32_t alignment = getAlignment<ELFT>(sections, sym);
|
|
if (!(versyms[i] & VERSYM_HIDDEN)) {
|
|
symtab.addSymbol(SharedSymbol{*this, name, sym.getBinding(), sym.st_other,
|
|
sym.getType(), sym.st_value, sym.st_size,
|
|
alignment, idx});
|
|
}
|
|
|
|
// Also add the symbol with the versioned name to handle undefined symbols
|
|
// with explicit versions.
|
|
if (idx == VER_NDX_GLOBAL)
|
|
continue;
|
|
|
|
if (idx >= verdefs.size() || idx == VER_NDX_LOCAL) {
|
|
error("corrupt input file: version definition index " + Twine(idx) +
|
|
" for symbol " + name + " is out of bounds\n>>> defined in " +
|
|
toString(this));
|
|
continue;
|
|
}
|
|
|
|
StringRef verName =
|
|
stringTable.data() +
|
|
reinterpret_cast<const Elf_Verdef *>(verdefs[idx])->getAux()->vda_name;
|
|
versionedNameBuffer.clear();
|
|
name = (name + "@" + verName).toStringRef(versionedNameBuffer);
|
|
symtab.addSymbol(SharedSymbol{*this, saver.save(name), sym.getBinding(),
|
|
sym.st_other, sym.getType(), sym.st_value,
|
|
sym.st_size, alignment, idx});
|
|
}
|
|
}
|
|
|
|
static ELFKind getBitcodeELFKind(const Triple &t) {
|
|
if (t.isLittleEndian())
|
|
return t.isArch64Bit() ? ELF64LEKind : ELF32LEKind;
|
|
return t.isArch64Bit() ? ELF64BEKind : ELF32BEKind;
|
|
}
|
|
|
|
static uint16_t getBitcodeMachineKind(StringRef path, const Triple &t) {
|
|
switch (t.getArch()) {
|
|
case Triple::aarch64:
|
|
case Triple::aarch64_be:
|
|
return EM_AARCH64;
|
|
case Triple::amdgcn:
|
|
case Triple::r600:
|
|
return EM_AMDGPU;
|
|
case Triple::arm:
|
|
case Triple::thumb:
|
|
return EM_ARM;
|
|
case Triple::avr:
|
|
return EM_AVR;
|
|
case Triple::hexagon:
|
|
return EM_HEXAGON;
|
|
case Triple::mips:
|
|
case Triple::mipsel:
|
|
case Triple::mips64:
|
|
case Triple::mips64el:
|
|
return EM_MIPS;
|
|
case Triple::msp430:
|
|
return EM_MSP430;
|
|
case Triple::ppc:
|
|
case Triple::ppcle:
|
|
return EM_PPC;
|
|
case Triple::ppc64:
|
|
case Triple::ppc64le:
|
|
return EM_PPC64;
|
|
case Triple::riscv32:
|
|
case Triple::riscv64:
|
|
return EM_RISCV;
|
|
case Triple::x86:
|
|
return t.isOSIAMCU() ? EM_IAMCU : EM_386;
|
|
case Triple::x86_64:
|
|
return EM_X86_64;
|
|
default:
|
|
error(path + ": could not infer e_machine from bitcode target triple " +
|
|
t.str());
|
|
return EM_NONE;
|
|
}
|
|
}
|
|
|
|
static uint8_t getOsAbi(const Triple &t) {
|
|
switch (t.getOS()) {
|
|
case Triple::AMDHSA:
|
|
return ELF::ELFOSABI_AMDGPU_HSA;
|
|
case Triple::AMDPAL:
|
|
return ELF::ELFOSABI_AMDGPU_PAL;
|
|
case Triple::Mesa3D:
|
|
return ELF::ELFOSABI_AMDGPU_MESA3D;
|
|
default:
|
|
return ELF::ELFOSABI_NONE;
|
|
}
|
|
}
|
|
|
|
BitcodeFile::BitcodeFile(MemoryBufferRef mb, StringRef archiveName,
|
|
uint64_t offsetInArchive, bool lazy)
|
|
: InputFile(BitcodeKind, mb) {
|
|
this->archiveName = archiveName;
|
|
this->lazy = lazy;
|
|
|
|
std::string path = mb.getBufferIdentifier().str();
|
|
if (config->thinLTOIndexOnly)
|
|
path = replaceThinLTOSuffix(mb.getBufferIdentifier());
|
|
|
|
// ThinLTO assumes that all MemoryBufferRefs given to it have a unique
|
|
// name. If two archives define two members with the same name, this
|
|
// causes a collision which result in only one of the objects being taken
|
|
// into consideration at LTO time (which very likely causes undefined
|
|
// symbols later in the link stage). So we append file offset to make
|
|
// filename unique.
|
|
StringRef name =
|
|
archiveName.empty()
|
|
? saver.save(path)
|
|
: saver.save(archiveName + "(" + path::filename(path) + " at " +
|
|
utostr(offsetInArchive) + ")");
|
|
MemoryBufferRef mbref(mb.getBuffer(), name);
|
|
|
|
obj = CHECK(lto::InputFile::create(mbref), this);
|
|
|
|
Triple t(obj->getTargetTriple());
|
|
ekind = getBitcodeELFKind(t);
|
|
emachine = getBitcodeMachineKind(mb.getBufferIdentifier(), t);
|
|
osabi = getOsAbi(t);
|
|
}
|
|
|
|
static uint8_t mapVisibility(GlobalValue::VisibilityTypes gvVisibility) {
|
|
switch (gvVisibility) {
|
|
case GlobalValue::DefaultVisibility:
|
|
return STV_DEFAULT;
|
|
case GlobalValue::HiddenVisibility:
|
|
return STV_HIDDEN;
|
|
case GlobalValue::ProtectedVisibility:
|
|
return STV_PROTECTED;
|
|
}
|
|
llvm_unreachable("unknown visibility");
|
|
}
|
|
|
|
template <class ELFT>
|
|
static void
|
|
createBitcodeSymbol(Symbol *&sym, const std::vector<bool> &keptComdats,
|
|
const lto::InputFile::Symbol &objSym, BitcodeFile &f) {
|
|
uint8_t binding = objSym.isWeak() ? STB_WEAK : STB_GLOBAL;
|
|
uint8_t type = objSym.isTLS() ? STT_TLS : STT_NOTYPE;
|
|
uint8_t visibility = mapVisibility(objSym.getVisibility());
|
|
bool canOmitFromDynSym = objSym.canBeOmittedFromSymbolTable();
|
|
|
|
StringRef name;
|
|
if (sym) {
|
|
name = sym->getName();
|
|
} else {
|
|
name = saver.save(objSym.getName());
|
|
sym = symtab->insert(name);
|
|
}
|
|
|
|
int c = objSym.getComdatIndex();
|
|
if (objSym.isUndefined() || (c != -1 && !keptComdats[c])) {
|
|
Undefined newSym(&f, name, binding, visibility, type);
|
|
if (canOmitFromDynSym)
|
|
newSym.exportDynamic = false;
|
|
sym->resolve(newSym);
|
|
sym->referenced = true;
|
|
return;
|
|
}
|
|
|
|
if (objSym.isCommon()) {
|
|
sym->resolve(CommonSymbol{&f, name, binding, visibility, STT_OBJECT,
|
|
objSym.getCommonAlignment(),
|
|
objSym.getCommonSize()});
|
|
} else {
|
|
Defined newSym(&f, name, binding, visibility, type, 0, 0, nullptr);
|
|
if (canOmitFromDynSym)
|
|
newSym.exportDynamic = false;
|
|
sym->resolve(newSym);
|
|
}
|
|
}
|
|
|
|
template <class ELFT> void BitcodeFile::parse() {
|
|
std::vector<bool> keptComdats;
|
|
for (std::pair<StringRef, Comdat::SelectionKind> s : obj->getComdatTable()) {
|
|
keptComdats.push_back(
|
|
s.second == Comdat::NoDeduplicate ||
|
|
symtab->comdatGroups.try_emplace(CachedHashStringRef(s.first), this)
|
|
.second);
|
|
}
|
|
|
|
symbols.resize(obj->symbols().size());
|
|
for (auto it : llvm::enumerate(obj->symbols())) {
|
|
Symbol *&sym = symbols[it.index()];
|
|
createBitcodeSymbol<ELFT>(sym, keptComdats, it.value(), *this);
|
|
}
|
|
|
|
for (auto l : obj->getDependentLibraries())
|
|
addDependentLibrary(l, this);
|
|
}
|
|
|
|
void BitcodeFile::parseLazy() {
|
|
SymbolTable &symtab = *elf::symtab;
|
|
symbols.resize(obj->symbols().size());
|
|
for (auto it : llvm::enumerate(obj->symbols()))
|
|
if (!it.value().isUndefined())
|
|
symbols[it.index()] =
|
|
symtab.addSymbol(LazyObject{*this, saver.save(it.value().getName())});
|
|
}
|
|
|
|
void BinaryFile::parse() {
|
|
ArrayRef<uint8_t> data = arrayRefFromStringRef(mb.getBuffer());
|
|
auto *section = make<InputSection>(this, SHF_ALLOC | SHF_WRITE, SHT_PROGBITS,
|
|
8, data, ".data");
|
|
sections.push_back(section);
|
|
|
|
// For each input file foo that is embedded to a result as a binary
|
|
// blob, we define _binary_foo_{start,end,size} symbols, so that
|
|
// user programs can access blobs by name. Non-alphanumeric
|
|
// characters in a filename are replaced with underscore.
|
|
std::string s = "_binary_" + mb.getBufferIdentifier().str();
|
|
for (size_t i = 0; i < s.size(); ++i)
|
|
if (!isAlnum(s[i]))
|
|
s[i] = '_';
|
|
|
|
symtab->addSymbol(Defined{nullptr, saver.save(s + "_start"), STB_GLOBAL,
|
|
STV_DEFAULT, STT_OBJECT, 0, 0, section});
|
|
symtab->addSymbol(Defined{nullptr, saver.save(s + "_end"), STB_GLOBAL,
|
|
STV_DEFAULT, STT_OBJECT, data.size(), 0, section});
|
|
symtab->addSymbol(Defined{nullptr, saver.save(s + "_size"), STB_GLOBAL,
|
|
STV_DEFAULT, STT_OBJECT, data.size(), 0, nullptr});
|
|
}
|
|
|
|
InputFile *elf::createObjectFile(MemoryBufferRef mb, StringRef archiveName,
|
|
uint64_t offsetInArchive) {
|
|
if (isBitcode(mb))
|
|
return make<BitcodeFile>(mb, archiveName, offsetInArchive, /*lazy=*/false);
|
|
|
|
switch (getELFKind(mb, archiveName)) {
|
|
case ELF32LEKind:
|
|
return make<ObjFile<ELF32LE>>(mb, archiveName);
|
|
case ELF32BEKind:
|
|
return make<ObjFile<ELF32BE>>(mb, archiveName);
|
|
case ELF64LEKind:
|
|
return make<ObjFile<ELF64LE>>(mb, archiveName);
|
|
case ELF64BEKind:
|
|
return make<ObjFile<ELF64BE>>(mb, archiveName);
|
|
default:
|
|
llvm_unreachable("getELFKind");
|
|
}
|
|
}
|
|
|
|
InputFile *elf::createLazyFile(MemoryBufferRef mb, StringRef archiveName,
|
|
uint64_t offsetInArchive) {
|
|
if (isBitcode(mb))
|
|
return make<BitcodeFile>(mb, archiveName, offsetInArchive, /*lazy=*/true);
|
|
|
|
auto *file =
|
|
cast<ELFFileBase>(createObjectFile(mb, archiveName, offsetInArchive));
|
|
file->lazy = true;
|
|
return file;
|
|
}
|
|
|
|
template <class ELFT> void ObjFile<ELFT>::parseLazy() {
|
|
const ArrayRef<typename ELFT::Sym> eSyms = this->getELFSyms<ELFT>();
|
|
SymbolTable &symtab = *elf::symtab;
|
|
|
|
symbols.resize(eSyms.size());
|
|
for (size_t i = firstGlobal, end = eSyms.size(); i != end; ++i)
|
|
if (eSyms[i].st_shndx != SHN_UNDEF)
|
|
symbols[i] = symtab.insert(CHECK(eSyms[i].getName(stringTable), this));
|
|
|
|
// Replace existing symbols with LazyObject symbols.
|
|
//
|
|
// resolve() may trigger this->extract() if an existing symbol is an undefined
|
|
// symbol. If that happens, this function has served its purpose, and we can
|
|
// exit from the loop early.
|
|
for (Symbol *sym : makeArrayRef(symbols).slice(firstGlobal))
|
|
if (sym) {
|
|
sym->resolve(LazyObject{*this, sym->getName()});
|
|
if (!lazy)
|
|
return;
|
|
}
|
|
}
|
|
|
|
bool InputFile::shouldExtractForCommon(StringRef name) {
|
|
if (isBitcode(mb))
|
|
return isBitcodeNonCommonDef(mb, name, archiveName);
|
|
|
|
return isNonCommonDef(mb, name, archiveName);
|
|
}
|
|
|
|
std::string elf::replaceThinLTOSuffix(StringRef path) {
|
|
StringRef suffix = config->thinLTOObjectSuffixReplace.first;
|
|
StringRef repl = config->thinLTOObjectSuffixReplace.second;
|
|
|
|
if (path.consume_back(suffix))
|
|
return (path + repl).str();
|
|
return std::string(path);
|
|
}
|
|
|
|
template void BitcodeFile::parse<ELF32LE>();
|
|
template void BitcodeFile::parse<ELF32BE>();
|
|
template void BitcodeFile::parse<ELF64LE>();
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template void BitcodeFile::parse<ELF64BE>();
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template class elf::ObjFile<ELF32LE>;
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template class elf::ObjFile<ELF32BE>;
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template class elf::ObjFile<ELF64LE>;
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template class elf::ObjFile<ELF64BE>;
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template void SharedFile::parse<ELF32LE>();
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template void SharedFile::parse<ELF32BE>();
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template void SharedFile::parse<ELF64LE>();
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template void SharedFile::parse<ELF64BE>();
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