forked from OSchip/llvm-project
1288 lines
47 KiB
C++
1288 lines
47 KiB
C++
//===- InputSection.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 "InputSection.h"
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#include "Config.h"
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#include "EhFrame.h"
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#include "InputFiles.h"
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#include "LinkerScript.h"
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#include "OutputSections.h"
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#include "Relocations.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 "Target.h"
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#include "Thunks.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/Support/Compiler.h"
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#include "llvm/Support/Compression.h"
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#include "llvm/Support/Endian.h"
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#include "llvm/Support/Threading.h"
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#include "llvm/Support/xxhash.h"
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#include <algorithm>
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#include <mutex>
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#include <set>
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#include <vector>
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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::support;
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using namespace llvm::support::endian;
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using namespace llvm::sys;
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using namespace lld;
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using namespace lld::elf;
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std::vector<InputSectionBase *> elf::InputSections;
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// Returns a string to construct an error message.
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std::string lld::toString(const InputSectionBase *Sec) {
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return (toString(Sec->File) + ":(" + Sec->Name + ")").str();
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}
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template <class ELFT>
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static ArrayRef<uint8_t> getSectionContents(ObjFile<ELFT> &File,
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const typename ELFT::Shdr &Hdr) {
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if (Hdr.sh_type == SHT_NOBITS)
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return makeArrayRef<uint8_t>(nullptr, Hdr.sh_size);
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return check(File.getObj().getSectionContents(&Hdr));
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}
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InputSectionBase::InputSectionBase(InputFile *File, uint64_t Flags,
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uint32_t Type, uint64_t Entsize,
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uint32_t Link, uint32_t Info,
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uint32_t Alignment, ArrayRef<uint8_t> Data,
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StringRef Name, Kind SectionKind)
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: SectionBase(SectionKind, Name, Flags, Entsize, Alignment, Type, Info,
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Link),
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File(File), RawData(Data) {
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// In order to reduce memory allocation, we assume that mergeable
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// sections are smaller than 4 GiB, which is not an unreasonable
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// assumption as of 2017.
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if (SectionKind == SectionBase::Merge && RawData.size() > UINT32_MAX)
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error(toString(this) + ": section too large");
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NumRelocations = 0;
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AreRelocsRela = false;
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Debug = Name.startswith(".debug") || Name.startswith(".zdebug");
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// The ELF spec states that a value of 0 means the section has
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// no alignment constraits.
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uint32_t V = std::max<uint32_t>(Alignment, 1);
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if (!isPowerOf2_64(V))
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fatal(toString(this) + ": sh_addralign is not a power of 2");
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this->Alignment = V;
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// In ELF, each section can be compressed by zlib, and if compressed,
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// section name may be mangled by appending "z" (e.g. ".zdebug_info").
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// If that's the case, demangle section name so that we can handle a
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// section as if it weren't compressed.
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if ((Flags & SHF_COMPRESSED) || Name.startswith(".zdebug")) {
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if (!zlib::isAvailable())
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error(toString(File) + ": contains a compressed section, " +
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"but zlib is not available");
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parseCompressedHeader();
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}
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}
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// Drop SHF_GROUP bit unless we are producing a re-linkable object file.
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// SHF_GROUP is a marker that a section belongs to some comdat group.
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// That flag doesn't make sense in an executable.
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static uint64_t getFlags(uint64_t Flags) {
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Flags &= ~(uint64_t)SHF_INFO_LINK;
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if (!Config->Relocatable)
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Flags &= ~(uint64_t)SHF_GROUP;
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return Flags;
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}
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// GNU assembler 2.24 and LLVM 4.0.0's MC (the newest release as of
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// March 2017) fail to infer section types for sections starting with
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// ".init_array." or ".fini_array.". They set SHT_PROGBITS instead of
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// SHF_INIT_ARRAY. As a result, the following assembler directive
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// creates ".init_array.100" with SHT_PROGBITS, for example.
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//
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// .section .init_array.100, "aw"
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//
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// This function forces SHT_{INIT,FINI}_ARRAY so that we can handle
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// incorrect inputs as if they were correct from the beginning.
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static uint64_t getType(uint64_t Type, StringRef Name) {
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if (Type == SHT_PROGBITS && Name.startswith(".init_array."))
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return SHT_INIT_ARRAY;
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if (Type == SHT_PROGBITS && Name.startswith(".fini_array."))
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return SHT_FINI_ARRAY;
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return Type;
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}
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template <class ELFT>
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InputSectionBase::InputSectionBase(ObjFile<ELFT> &File,
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const typename ELFT::Shdr &Hdr,
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StringRef Name, Kind SectionKind)
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: InputSectionBase(&File, getFlags(Hdr.sh_flags),
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getType(Hdr.sh_type, Name), Hdr.sh_entsize, Hdr.sh_link,
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Hdr.sh_info, Hdr.sh_addralign,
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getSectionContents(File, Hdr), Name, SectionKind) {
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// We reject object files having insanely large alignments even though
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// they are allowed by the spec. I think 4GB is a reasonable limitation.
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// We might want to relax this in the future.
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if (Hdr.sh_addralign > UINT32_MAX)
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fatal(toString(&File) + ": section sh_addralign is too large");
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}
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size_t InputSectionBase::getSize() const {
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if (auto *S = dyn_cast<SyntheticSection>(this))
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return S->getSize();
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if (UncompressedSize >= 0)
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return UncompressedSize;
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return RawData.size();
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}
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void InputSectionBase::uncompress() const {
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size_t Size = UncompressedSize;
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char *UncompressedBuf;
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{
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static std::mutex Mu;
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std::lock_guard<std::mutex> Lock(Mu);
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UncompressedBuf = BAlloc.Allocate<char>(Size);
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}
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if (Error E = zlib::uncompress(toStringRef(RawData), UncompressedBuf, Size))
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fatal(toString(this) +
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": uncompress failed: " + llvm::toString(std::move(E)));
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RawData = makeArrayRef((uint8_t *)UncompressedBuf, Size);
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UncompressedSize = -1;
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}
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uint64_t InputSectionBase::getOffsetInFile() const {
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const uint8_t *FileStart = (const uint8_t *)File->MB.getBufferStart();
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const uint8_t *SecStart = data().begin();
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return SecStart - FileStart;
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}
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uint64_t SectionBase::getOffset(uint64_t Offset) const {
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switch (kind()) {
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case Output: {
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auto *OS = cast<OutputSection>(this);
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// For output sections we treat offset -1 as the end of the section.
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return Offset == uint64_t(-1) ? OS->Size : Offset;
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}
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case Regular:
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case Synthetic:
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return cast<InputSection>(this)->getOffset(Offset);
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case EHFrame:
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// The file crtbeginT.o has relocations pointing to the start of an empty
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// .eh_frame that is known to be the first in the link. It does that to
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// identify the start of the output .eh_frame.
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return Offset;
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case Merge:
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const MergeInputSection *MS = cast<MergeInputSection>(this);
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if (InputSection *IS = MS->getParent())
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return IS->getOffset(MS->getParentOffset(Offset));
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return MS->getParentOffset(Offset);
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}
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llvm_unreachable("invalid section kind");
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}
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uint64_t SectionBase::getVA(uint64_t Offset) const {
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const OutputSection *Out = getOutputSection();
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return (Out ? Out->Addr : 0) + getOffset(Offset);
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}
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OutputSection *SectionBase::getOutputSection() {
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InputSection *Sec;
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if (auto *IS = dyn_cast<InputSection>(this))
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Sec = IS;
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else if (auto *MS = dyn_cast<MergeInputSection>(this))
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Sec = MS->getParent();
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else if (auto *EH = dyn_cast<EhInputSection>(this))
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Sec = EH->getParent();
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else
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return cast<OutputSection>(this);
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return Sec ? Sec->getParent() : nullptr;
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}
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// When a section is compressed, `RawData` consists with a header followed
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// by zlib-compressed data. This function parses a header to initialize
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// `UncompressedSize` member and remove the header from `RawData`.
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void InputSectionBase::parseCompressedHeader() {
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using Chdr64 = typename ELF64LE::Chdr;
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using Chdr32 = typename ELF32LE::Chdr;
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// Old-style header
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if (Name.startswith(".zdebug")) {
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if (!toStringRef(RawData).startswith("ZLIB")) {
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error(toString(this) + ": corrupted compressed section header");
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return;
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}
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RawData = RawData.slice(4);
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if (RawData.size() < 8) {
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error(toString(this) + ": corrupted compressed section header");
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return;
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}
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UncompressedSize = read64be(RawData.data());
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RawData = RawData.slice(8);
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// Restore the original section name.
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// (e.g. ".zdebug_info" -> ".debug_info")
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Name = Saver.save("." + Name.substr(2));
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return;
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}
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assert(Flags & SHF_COMPRESSED);
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Flags &= ~(uint64_t)SHF_COMPRESSED;
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// New-style 64-bit header
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if (Config->Is64) {
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if (RawData.size() < sizeof(Chdr64)) {
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error(toString(this) + ": corrupted compressed section");
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return;
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}
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auto *Hdr = reinterpret_cast<const Chdr64 *>(RawData.data());
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if (Hdr->ch_type != ELFCOMPRESS_ZLIB) {
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error(toString(this) + ": unsupported compression type");
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return;
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}
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UncompressedSize = Hdr->ch_size;
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Alignment = std::max<uint32_t>(Hdr->ch_addralign, 1);
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RawData = RawData.slice(sizeof(*Hdr));
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return;
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}
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// New-style 32-bit header
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if (RawData.size() < sizeof(Chdr32)) {
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error(toString(this) + ": corrupted compressed section");
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return;
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}
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auto *Hdr = reinterpret_cast<const Chdr32 *>(RawData.data());
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if (Hdr->ch_type != ELFCOMPRESS_ZLIB) {
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error(toString(this) + ": unsupported compression type");
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return;
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}
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UncompressedSize = Hdr->ch_size;
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Alignment = std::max<uint32_t>(Hdr->ch_addralign, 1);
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RawData = RawData.slice(sizeof(*Hdr));
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}
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InputSection *InputSectionBase::getLinkOrderDep() const {
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assert(Link);
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assert(Flags & SHF_LINK_ORDER);
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return cast<InputSection>(File->getSections()[Link]);
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}
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// Find a function symbol that encloses a given location.
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template <class ELFT>
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Defined *InputSectionBase::getEnclosingFunction(uint64_t Offset) {
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for (Symbol *B : File->getSymbols())
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if (Defined *D = dyn_cast<Defined>(B))
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if (D->Section == this && D->Type == STT_FUNC && D->Value <= Offset &&
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Offset < D->Value + D->Size)
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return D;
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return nullptr;
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}
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// Returns a source location string. Used to construct an error message.
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template <class ELFT>
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std::string InputSectionBase::getLocation(uint64_t Offset) {
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std::string SecAndOffset = (Name + "+0x" + utohexstr(Offset)).str();
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// We don't have file for synthetic sections.
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if (getFile<ELFT>() == nullptr)
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return (Config->OutputFile + ":(" + SecAndOffset + ")")
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.str();
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// First check if we can get desired values from debugging information.
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if (Optional<DILineInfo> Info = getFile<ELFT>()->getDILineInfo(this, Offset))
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return Info->FileName + ":" + std::to_string(Info->Line) + ":(" +
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SecAndOffset + ")";
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// File->SourceFile contains STT_FILE symbol that contains a
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// source file name. If it's missing, we use an object file name.
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std::string SrcFile = getFile<ELFT>()->SourceFile;
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if (SrcFile.empty())
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SrcFile = toString(File);
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if (Defined *D = getEnclosingFunction<ELFT>(Offset))
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return SrcFile + ":(function " + toString(*D) + ": " + SecAndOffset + ")";
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// If there's no symbol, print out the offset in the section.
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return (SrcFile + ":(" + SecAndOffset + ")");
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}
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// This function is intended to be used for constructing an error message.
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// The returned message looks like this:
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//
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// foo.c:42 (/home/alice/possibly/very/long/path/foo.c:42)
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//
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// Returns an empty string if there's no way to get line info.
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std::string InputSectionBase::getSrcMsg(const Symbol &Sym, uint64_t Offset) {
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return File->getSrcMsg(Sym, *this, Offset);
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}
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// Returns a filename string along with an optional section name. This
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// function is intended to be used for constructing an error
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// message. The returned message looks like this:
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//
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// path/to/foo.o:(function bar)
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//
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// or
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//
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// path/to/foo.o:(function bar) in archive path/to/bar.a
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std::string InputSectionBase::getObjMsg(uint64_t Off) {
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std::string Filename = File->getName();
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std::string Archive;
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if (!File->ArchiveName.empty())
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Archive = " in archive " + File->ArchiveName;
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// Find a symbol that encloses a given location.
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for (Symbol *B : File->getSymbols())
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if (auto *D = dyn_cast<Defined>(B))
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if (D->Section == this && D->Value <= Off && Off < D->Value + D->Size)
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return Filename + ":(" + toString(*D) + ")" + Archive;
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// If there's no symbol, print out the offset in the section.
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return (Filename + ":(" + Name + "+0x" + utohexstr(Off) + ")" + Archive)
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.str();
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}
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InputSection InputSection::Discarded(nullptr, 0, 0, 0, ArrayRef<uint8_t>(), "");
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InputSection::InputSection(InputFile *F, uint64_t Flags, uint32_t Type,
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uint32_t Alignment, ArrayRef<uint8_t> Data,
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StringRef Name, Kind K)
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: InputSectionBase(F, Flags, Type,
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/*Entsize*/ 0, /*Link*/ 0, /*Info*/ 0, Alignment, Data,
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Name, K) {}
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template <class ELFT>
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InputSection::InputSection(ObjFile<ELFT> &F, const typename ELFT::Shdr &Header,
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StringRef Name)
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: InputSectionBase(F, Header, Name, InputSectionBase::Regular) {}
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bool InputSection::classof(const SectionBase *S) {
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return S->kind() == SectionBase::Regular ||
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S->kind() == SectionBase::Synthetic;
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}
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OutputSection *InputSection::getParent() const {
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return cast_or_null<OutputSection>(Parent);
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}
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// Copy SHT_GROUP section contents. Used only for the -r option.
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template <class ELFT> void InputSection::copyShtGroup(uint8_t *Buf) {
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// ELFT::Word is the 32-bit integral type in the target endianness.
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using u32 = typename ELFT::Word;
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ArrayRef<u32> From = getDataAs<u32>();
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auto *To = reinterpret_cast<u32 *>(Buf);
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// The first entry is not a section number but a flag.
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*To++ = From[0];
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// Adjust section numbers because section numbers in an input object
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// files are different in the output.
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ArrayRef<InputSectionBase *> Sections = File->getSections();
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for (uint32_t Idx : From.slice(1))
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*To++ = Sections[Idx]->getOutputSection()->SectionIndex;
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}
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InputSectionBase *InputSection::getRelocatedSection() const {
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if (!File || (Type != SHT_RELA && Type != SHT_REL))
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return nullptr;
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ArrayRef<InputSectionBase *> Sections = File->getSections();
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return Sections[Info];
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}
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// This is used for -r and --emit-relocs. We can't use memcpy to copy
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// relocations because we need to update symbol table offset and section index
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// for each relocation. So we copy relocations one by one.
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template <class ELFT, class RelTy>
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void InputSection::copyRelocations(uint8_t *Buf, ArrayRef<RelTy> Rels) {
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InputSectionBase *Sec = getRelocatedSection();
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for (const RelTy &Rel : Rels) {
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RelType Type = Rel.getType(Config->IsMips64EL);
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Symbol &Sym = getFile<ELFT>()->getRelocTargetSym(Rel);
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auto *P = reinterpret_cast<typename ELFT::Rela *>(Buf);
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Buf += sizeof(RelTy);
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if (RelTy::IsRela)
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P->r_addend = getAddend<ELFT>(Rel);
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// Output section VA is zero for -r, so r_offset is an offset within the
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// section, but for --emit-relocs it is an virtual address.
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P->r_offset = Sec->getVA(Rel.r_offset);
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P->setSymbolAndType(In.SymTab->getSymbolIndex(&Sym), Type,
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Config->IsMips64EL);
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if (Sym.Type == STT_SECTION) {
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// We combine multiple section symbols into only one per
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// section. This means we have to update the addend. That is
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// trivial for Elf_Rela, but for Elf_Rel we have to write to the
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// section data. We do that by adding to the Relocation vector.
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// .eh_frame is horribly special and can reference discarded sections. To
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// avoid having to parse and recreate .eh_frame, we just replace any
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// relocation in it pointing to discarded sections with R_*_NONE, which
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// hopefully creates a frame that is ignored at runtime.
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auto *D = dyn_cast<Defined>(&Sym);
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if (!D) {
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error("STT_SECTION symbol should be defined");
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continue;
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}
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SectionBase *Section = D->Section->Repl;
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if (!Section->Live) {
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P->setSymbolAndType(0, 0, false);
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continue;
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}
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int64_t Addend = getAddend<ELFT>(Rel);
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const uint8_t *BufLoc = Sec->data().begin() + Rel.r_offset;
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if (!RelTy::IsRela)
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Addend = Target->getImplicitAddend(BufLoc, Type);
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if (Config->EMachine == EM_MIPS && Config->Relocatable &&
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Target->getRelExpr(Type, Sym, BufLoc) == R_MIPS_GOTREL) {
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// Some MIPS relocations depend on "gp" value. By default,
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// this value has 0x7ff0 offset from a .got section. But
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// relocatable files produced by a complier or a linker
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// might redefine this default value and we must use it
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// for a calculation of the relocation result. When we
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// generate EXE or DSO it's trivial. Generating a relocatable
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// output is more difficult case because the linker does
|
|
// not calculate relocations in this mode and loses
|
|
// individual "gp" values used by each input object file.
|
|
// As a workaround we add the "gp" value to the relocation
|
|
// addend and save it back to the file.
|
|
Addend += Sec->getFile<ELFT>()->MipsGp0;
|
|
}
|
|
|
|
if (RelTy::IsRela)
|
|
P->r_addend = Sym.getVA(Addend) - Section->getOutputSection()->Addr;
|
|
else if (Config->Relocatable)
|
|
Sec->Relocations.push_back({R_ABS, Type, Rel.r_offset, Addend, &Sym});
|
|
}
|
|
}
|
|
}
|
|
|
|
// The ARM and AArch64 ABI handle pc-relative relocations to undefined weak
|
|
// references specially. The general rule is that the value of the symbol in
|
|
// this context is the address of the place P. A further special case is that
|
|
// branch relocations to an undefined weak reference resolve to the next
|
|
// instruction.
|
|
static uint32_t getARMUndefinedRelativeWeakVA(RelType Type, uint32_t A,
|
|
uint32_t P) {
|
|
switch (Type) {
|
|
// Unresolved branch relocations to weak references resolve to next
|
|
// instruction, this will be either 2 or 4 bytes on from P.
|
|
case R_ARM_THM_JUMP11:
|
|
return P + 2 + A;
|
|
case R_ARM_CALL:
|
|
case R_ARM_JUMP24:
|
|
case R_ARM_PC24:
|
|
case R_ARM_PLT32:
|
|
case R_ARM_PREL31:
|
|
case R_ARM_THM_JUMP19:
|
|
case R_ARM_THM_JUMP24:
|
|
return P + 4 + A;
|
|
case R_ARM_THM_CALL:
|
|
// We don't want an interworking BLX to ARM
|
|
return P + 5 + A;
|
|
// Unresolved non branch pc-relative relocations
|
|
// R_ARM_TARGET2 which can be resolved relatively is not present as it never
|
|
// targets a weak-reference.
|
|
case R_ARM_MOVW_PREL_NC:
|
|
case R_ARM_MOVT_PREL:
|
|
case R_ARM_REL32:
|
|
case R_ARM_THM_MOVW_PREL_NC:
|
|
case R_ARM_THM_MOVT_PREL:
|
|
return P + A;
|
|
}
|
|
llvm_unreachable("ARM pc-relative relocation expected\n");
|
|
}
|
|
|
|
// The comment above getARMUndefinedRelativeWeakVA applies to this function.
|
|
static uint64_t getAArch64UndefinedRelativeWeakVA(uint64_t Type, uint64_t A,
|
|
uint64_t P) {
|
|
switch (Type) {
|
|
// Unresolved branch relocations to weak references resolve to next
|
|
// instruction, this is 4 bytes on from P.
|
|
case R_AARCH64_CALL26:
|
|
case R_AARCH64_CONDBR19:
|
|
case R_AARCH64_JUMP26:
|
|
case R_AARCH64_TSTBR14:
|
|
return P + 4 + A;
|
|
// Unresolved non branch pc-relative relocations
|
|
case R_AARCH64_PREL16:
|
|
case R_AARCH64_PREL32:
|
|
case R_AARCH64_PREL64:
|
|
case R_AARCH64_ADR_PREL_LO21:
|
|
case R_AARCH64_LD_PREL_LO19:
|
|
return P + A;
|
|
}
|
|
llvm_unreachable("AArch64 pc-relative relocation expected\n");
|
|
}
|
|
|
|
// ARM SBREL relocations are of the form S + A - B where B is the static base
|
|
// The ARM ABI defines base to be "addressing origin of the output segment
|
|
// defining the symbol S". We defined the "addressing origin"/static base to be
|
|
// the base of the PT_LOAD segment containing the Sym.
|
|
// The procedure call standard only defines a Read Write Position Independent
|
|
// RWPI variant so in practice we should expect the static base to be the base
|
|
// of the RW segment.
|
|
static uint64_t getARMStaticBase(const Symbol &Sym) {
|
|
OutputSection *OS = Sym.getOutputSection();
|
|
if (!OS || !OS->PtLoad || !OS->PtLoad->FirstSec)
|
|
fatal("SBREL relocation to " + Sym.getName() + " without static base");
|
|
return OS->PtLoad->FirstSec->Addr;
|
|
}
|
|
|
|
// For R_RISCV_PC_INDIRECT (R_RISCV_PCREL_LO12_{I,S}), the symbol actually
|
|
// points the corresponding R_RISCV_PCREL_HI20 relocation, and the target VA
|
|
// is calculated using PCREL_HI20's symbol.
|
|
//
|
|
// This function returns the R_RISCV_PCREL_HI20 relocation from
|
|
// R_RISCV_PCREL_LO12's symbol and addend.
|
|
static Relocation *getRISCVPCRelHi20(const Symbol *Sym, uint64_t Addend) {
|
|
const Defined *D = cast<Defined>(Sym);
|
|
InputSection *IS = cast<InputSection>(D->Section);
|
|
|
|
if (Addend != 0)
|
|
warn("Non-zero addend in R_RISCV_PCREL_LO12 relocation to " +
|
|
IS->getObjMsg(D->Value) + " is ignored");
|
|
|
|
// Relocations are sorted by offset, so we can use std::equal_range to do
|
|
// binary search.
|
|
Relocation R;
|
|
R.Offset = D->Value;
|
|
auto Range =
|
|
std::equal_range(IS->Relocations.begin(), IS->Relocations.end(), R,
|
|
[](const Relocation &LHS, const Relocation &RHS) {
|
|
return LHS.Offset < RHS.Offset;
|
|
});
|
|
|
|
for (auto It = Range.first; It != Range.second; ++It)
|
|
if (It->Expr == R_PC)
|
|
return &*It;
|
|
|
|
error("R_RISCV_PCREL_LO12 relocation points to " + IS->getObjMsg(D->Value) +
|
|
" without an associated R_RISCV_PCREL_HI20 relocation");
|
|
return nullptr;
|
|
}
|
|
|
|
// A TLS symbol's virtual address is relative to the TLS segment. Add a
|
|
// target-specific adjustment to produce a thread-pointer-relative offset.
|
|
static int64_t getTlsTpOffset() {
|
|
switch (Config->EMachine) {
|
|
case EM_ARM:
|
|
case EM_AARCH64:
|
|
// Variant 1. The thread pointer points to a TCB with a fixed 2-word size,
|
|
// followed by a variable amount of alignment padding, followed by the TLS
|
|
// segment.
|
|
//
|
|
// NB: While the ARM/AArch64 ABI formally has a 2-word TCB size, lld
|
|
// effectively increases the TCB size to 8 words for Android compatibility.
|
|
// It accomplishes this by increasing the segment's alignment.
|
|
return alignTo(Config->Wordsize * 2, Out::TlsPhdr->p_align);
|
|
case EM_386:
|
|
case EM_X86_64:
|
|
// Variant 2. The TLS segment is located just before the thread pointer.
|
|
return -Out::TlsPhdr->p_memsz;
|
|
case EM_PPC64:
|
|
// The thread pointer points to a fixed offset from the start of the
|
|
// executable's TLS segment. An offset of 0x7000 allows a signed 16-bit
|
|
// offset to reach 0x1000 of TCB/thread-library data and 0xf000 of the
|
|
// program's TLS segment.
|
|
return -0x7000;
|
|
default:
|
|
llvm_unreachable("unhandled Config->EMachine");
|
|
}
|
|
}
|
|
|
|
static uint64_t getRelocTargetVA(const InputFile *File, RelType Type, int64_t A,
|
|
uint64_t P, const Symbol &Sym, RelExpr Expr) {
|
|
switch (Expr) {
|
|
case R_ABS:
|
|
case R_DTPREL:
|
|
case R_RELAX_TLS_LD_TO_LE_ABS:
|
|
case R_RELAX_GOT_PC_NOPIC:
|
|
return Sym.getVA(A);
|
|
case R_ADDEND:
|
|
return A;
|
|
case R_ARM_SBREL:
|
|
return Sym.getVA(A) - getARMStaticBase(Sym);
|
|
case R_GOT:
|
|
case R_RELAX_TLS_GD_TO_IE_ABS:
|
|
return Sym.getGotVA() + A;
|
|
case R_GOTONLY_PC:
|
|
return In.Got->getVA() + A - P;
|
|
case R_GOTPLTONLY_PC:
|
|
return In.GotPlt->getVA() + A - P;
|
|
case R_GOTREL:
|
|
return Sym.getVA(A) - In.Got->getVA();
|
|
case R_GOTPLTREL:
|
|
return Sym.getVA(A) - In.GotPlt->getVA();
|
|
case R_GOTPLT:
|
|
case R_RELAX_TLS_GD_TO_IE_GOTPLT:
|
|
return Sym.getGotVA() + A - In.GotPlt->getVA();
|
|
case R_TLSLD_GOT_OFF:
|
|
case R_GOT_OFF:
|
|
case R_RELAX_TLS_GD_TO_IE_GOT_OFF:
|
|
return Sym.getGotOffset() + A;
|
|
case R_AARCH64_GOT_PAGE_PC:
|
|
case R_AARCH64_RELAX_TLS_GD_TO_IE_PAGE_PC:
|
|
return getAArch64Page(Sym.getGotVA() + A) - getAArch64Page(P);
|
|
case R_GOT_PC:
|
|
case R_RELAX_TLS_GD_TO_IE:
|
|
return Sym.getGotVA() + A - P;
|
|
case R_HEXAGON_GOT:
|
|
return Sym.getGotVA() - In.GotPlt->getVA();
|
|
case R_MIPS_GOTREL:
|
|
return Sym.getVA(A) - In.MipsGot->getGp(File);
|
|
case R_MIPS_GOT_GP:
|
|
return In.MipsGot->getGp(File) + A;
|
|
case R_MIPS_GOT_GP_PC: {
|
|
// R_MIPS_LO16 expression has R_MIPS_GOT_GP_PC type iif the target
|
|
// is _gp_disp symbol. In that case we should use the following
|
|
// formula for calculation "AHL + GP - P + 4". For details see p. 4-19 at
|
|
// ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
|
|
// microMIPS variants of these relocations use slightly different
|
|
// expressions: AHL + GP - P + 3 for %lo() and AHL + GP - P - 1 for %hi()
|
|
// to correctly handle less-sugnificant bit of the microMIPS symbol.
|
|
uint64_t V = In.MipsGot->getGp(File) + A - P;
|
|
if (Type == R_MIPS_LO16 || Type == R_MICROMIPS_LO16)
|
|
V += 4;
|
|
if (Type == R_MICROMIPS_LO16 || Type == R_MICROMIPS_HI16)
|
|
V -= 1;
|
|
return V;
|
|
}
|
|
case R_MIPS_GOT_LOCAL_PAGE:
|
|
// If relocation against MIPS local symbol requires GOT entry, this entry
|
|
// should be initialized by 'page address'. This address is high 16-bits
|
|
// of sum the symbol's value and the addend.
|
|
return In.MipsGot->getVA() + In.MipsGot->getPageEntryOffset(File, Sym, A) -
|
|
In.MipsGot->getGp(File);
|
|
case R_MIPS_GOT_OFF:
|
|
case R_MIPS_GOT_OFF32:
|
|
// In case of MIPS if a GOT relocation has non-zero addend this addend
|
|
// should be applied to the GOT entry content not to the GOT entry offset.
|
|
// That is why we use separate expression type.
|
|
return In.MipsGot->getVA() + In.MipsGot->getSymEntryOffset(File, Sym, A) -
|
|
In.MipsGot->getGp(File);
|
|
case R_MIPS_TLSGD:
|
|
return In.MipsGot->getVA() + In.MipsGot->getGlobalDynOffset(File, Sym) -
|
|
In.MipsGot->getGp(File);
|
|
case R_MIPS_TLSLD:
|
|
return In.MipsGot->getVA() + In.MipsGot->getTlsIndexOffset(File) -
|
|
In.MipsGot->getGp(File);
|
|
case R_AARCH64_PAGE_PC: {
|
|
uint64_t Val = Sym.isUndefWeak() ? P + A : Sym.getVA(A);
|
|
return getAArch64Page(Val) - getAArch64Page(P);
|
|
}
|
|
case R_RISCV_PC_INDIRECT: {
|
|
if (const Relocation *HiRel = getRISCVPCRelHi20(&Sym, A))
|
|
return getRelocTargetVA(File, HiRel->Type, HiRel->Addend, Sym.getVA(),
|
|
*HiRel->Sym, HiRel->Expr);
|
|
return 0;
|
|
}
|
|
case R_PC: {
|
|
uint64_t Dest;
|
|
if (Sym.isUndefWeak()) {
|
|
// On ARM and AArch64 a branch to an undefined weak resolves to the
|
|
// next instruction, otherwise the place.
|
|
if (Config->EMachine == EM_ARM)
|
|
Dest = getARMUndefinedRelativeWeakVA(Type, A, P);
|
|
else if (Config->EMachine == EM_AARCH64)
|
|
Dest = getAArch64UndefinedRelativeWeakVA(Type, A, P);
|
|
else
|
|
Dest = Sym.getVA(A);
|
|
} else {
|
|
Dest = Sym.getVA(A);
|
|
}
|
|
return Dest - P;
|
|
}
|
|
case R_PLT:
|
|
return Sym.getPltVA() + A;
|
|
case R_PLT_PC:
|
|
case R_PPC_CALL_PLT:
|
|
return Sym.getPltVA() + A - P;
|
|
case R_PPC_CALL: {
|
|
uint64_t SymVA = Sym.getVA(A);
|
|
// If we have an undefined weak symbol, we might get here with a symbol
|
|
// address of zero. That could overflow, but the code must be unreachable,
|
|
// so don't bother doing anything at all.
|
|
if (!SymVA)
|
|
return 0;
|
|
|
|
// PPC64 V2 ABI describes two entry points to a function. The global entry
|
|
// point is used for calls where the caller and callee (may) have different
|
|
// TOC base pointers and r2 needs to be modified to hold the TOC base for
|
|
// the callee. For local calls the caller and callee share the same
|
|
// TOC base and so the TOC pointer initialization code should be skipped by
|
|
// branching to the local entry point.
|
|
return SymVA - P + getPPC64GlobalEntryToLocalEntryOffset(Sym.StOther);
|
|
}
|
|
case R_PPC_TOC:
|
|
return getPPC64TocBase() + A;
|
|
case R_RELAX_GOT_PC:
|
|
return Sym.getVA(A) - P;
|
|
case R_RELAX_TLS_GD_TO_LE:
|
|
case R_RELAX_TLS_IE_TO_LE:
|
|
case R_RELAX_TLS_LD_TO_LE:
|
|
case R_TLS:
|
|
// A weak undefined TLS symbol resolves to the base of the TLS
|
|
// block, i.e. gets a value of zero. If we pass --gc-sections to
|
|
// lld and .tbss is not referenced, it gets reclaimed and we don't
|
|
// create a TLS program header. Therefore, we resolve this
|
|
// statically to zero.
|
|
if (Sym.isTls() && Sym.isUndefWeak())
|
|
return 0;
|
|
return Sym.getVA(A) + getTlsTpOffset();
|
|
case R_RELAX_TLS_GD_TO_LE_NEG:
|
|
case R_NEG_TLS:
|
|
return Out::TlsPhdr->p_memsz - Sym.getVA(A);
|
|
case R_SIZE:
|
|
return Sym.getSize() + A;
|
|
case R_TLSDESC:
|
|
return In.Got->getGlobalDynAddr(Sym) + A;
|
|
case R_AARCH64_TLSDESC_PAGE:
|
|
return getAArch64Page(In.Got->getGlobalDynAddr(Sym) + A) -
|
|
getAArch64Page(P);
|
|
case R_TLSGD_GOT:
|
|
return In.Got->getGlobalDynOffset(Sym) + A;
|
|
case R_TLSGD_GOTPLT:
|
|
return In.Got->getVA() + In.Got->getGlobalDynOffset(Sym) + A - In.GotPlt->getVA();
|
|
case R_TLSGD_PC:
|
|
return In.Got->getGlobalDynAddr(Sym) + A - P;
|
|
case R_TLSLD_GOTPLT:
|
|
return In.Got->getVA() + In.Got->getTlsIndexOff() + A - In.GotPlt->getVA();
|
|
case R_TLSLD_GOT:
|
|
return In.Got->getTlsIndexOff() + A;
|
|
case R_TLSLD_PC:
|
|
return In.Got->getTlsIndexVA() + A - P;
|
|
default:
|
|
llvm_unreachable("invalid expression");
|
|
}
|
|
}
|
|
|
|
// This function applies relocations to sections without SHF_ALLOC bit.
|
|
// Such sections are never mapped to memory at runtime. Debug sections are
|
|
// an example. Relocations in non-alloc sections are much easier to
|
|
// handle than in allocated sections because it will never need complex
|
|
// treatement such as GOT or PLT (because at runtime no one refers them).
|
|
// So, we handle relocations for non-alloc sections directly in this
|
|
// function as a performance optimization.
|
|
template <class ELFT, class RelTy>
|
|
void InputSection::relocateNonAlloc(uint8_t *Buf, ArrayRef<RelTy> Rels) {
|
|
const unsigned Bits = sizeof(typename ELFT::uint) * 8;
|
|
|
|
for (const RelTy &Rel : Rels) {
|
|
RelType Type = Rel.getType(Config->IsMips64EL);
|
|
|
|
// GCC 8.0 or earlier have a bug that they emit R_386_GOTPC relocations
|
|
// against _GLOBAL_OFFSET_TABLE_ for .debug_info. The bug has been fixed
|
|
// in 2017 (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82630), but we
|
|
// need to keep this bug-compatible code for a while.
|
|
if (Config->EMachine == EM_386 && Type == R_386_GOTPC)
|
|
continue;
|
|
|
|
uint64_t Offset = getOffset(Rel.r_offset);
|
|
uint8_t *BufLoc = Buf + Offset;
|
|
int64_t Addend = getAddend<ELFT>(Rel);
|
|
if (!RelTy::IsRela)
|
|
Addend += Target->getImplicitAddend(BufLoc, Type);
|
|
|
|
Symbol &Sym = getFile<ELFT>()->getRelocTargetSym(Rel);
|
|
RelExpr Expr = Target->getRelExpr(Type, Sym, BufLoc);
|
|
if (Expr == R_NONE)
|
|
continue;
|
|
|
|
if (Expr != R_ABS && Expr != R_DTPREL) {
|
|
std::string Msg = getLocation<ELFT>(Offset) +
|
|
": has non-ABS relocation " + toString(Type) +
|
|
" against symbol '" + toString(Sym) + "'";
|
|
if (Expr != R_PC) {
|
|
error(Msg);
|
|
return;
|
|
}
|
|
|
|
// If the control reaches here, we found a PC-relative relocation in a
|
|
// non-ALLOC section. Since non-ALLOC section is not loaded into memory
|
|
// at runtime, the notion of PC-relative doesn't make sense here. So,
|
|
// this is a usage error. However, GNU linkers historically accept such
|
|
// relocations without any errors and relocate them as if they were at
|
|
// address 0. For bug-compatibilty, we accept them with warnings. We
|
|
// know Steel Bank Common Lisp as of 2018 have this bug.
|
|
warn(Msg);
|
|
Target->relocateOne(BufLoc, Type,
|
|
SignExtend64<Bits>(Sym.getVA(Addend - Offset)));
|
|
continue;
|
|
}
|
|
|
|
if (Sym.isTls() && !Out::TlsPhdr)
|
|
Target->relocateOne(BufLoc, Type, 0);
|
|
else
|
|
Target->relocateOne(BufLoc, Type, SignExtend64<Bits>(Sym.getVA(Addend)));
|
|
}
|
|
}
|
|
|
|
// This is used when '-r' is given.
|
|
// For REL targets, InputSection::copyRelocations() may store artificial
|
|
// relocations aimed to update addends. They are handled in relocateAlloc()
|
|
// for allocatable sections, and this function does the same for
|
|
// non-allocatable sections, such as sections with debug information.
|
|
static void relocateNonAllocForRelocatable(InputSection *Sec, uint8_t *Buf) {
|
|
const unsigned Bits = Config->Is64 ? 64 : 32;
|
|
|
|
for (const Relocation &Rel : Sec->Relocations) {
|
|
// InputSection::copyRelocations() adds only R_ABS relocations.
|
|
assert(Rel.Expr == R_ABS);
|
|
uint8_t *BufLoc = Buf + Rel.Offset + Sec->OutSecOff;
|
|
uint64_t TargetVA = SignExtend64(Rel.Sym->getVA(Rel.Addend), Bits);
|
|
Target->relocateOne(BufLoc, Rel.Type, TargetVA);
|
|
}
|
|
}
|
|
|
|
template <class ELFT>
|
|
void InputSectionBase::relocate(uint8_t *Buf, uint8_t *BufEnd) {
|
|
if (Flags & SHF_EXECINSTR)
|
|
adjustSplitStackFunctionPrologues<ELFT>(Buf, BufEnd);
|
|
|
|
if (Flags & SHF_ALLOC) {
|
|
relocateAlloc(Buf, BufEnd);
|
|
return;
|
|
}
|
|
|
|
auto *Sec = cast<InputSection>(this);
|
|
if (Config->Relocatable)
|
|
relocateNonAllocForRelocatable(Sec, Buf);
|
|
else if (Sec->AreRelocsRela)
|
|
Sec->relocateNonAlloc<ELFT>(Buf, Sec->template relas<ELFT>());
|
|
else
|
|
Sec->relocateNonAlloc<ELFT>(Buf, Sec->template rels<ELFT>());
|
|
}
|
|
|
|
void InputSectionBase::relocateAlloc(uint8_t *Buf, uint8_t *BufEnd) {
|
|
assert(Flags & SHF_ALLOC);
|
|
const unsigned Bits = Config->Wordsize * 8;
|
|
|
|
for (const Relocation &Rel : Relocations) {
|
|
uint64_t Offset = Rel.Offset;
|
|
if (auto *Sec = dyn_cast<InputSection>(this))
|
|
Offset += Sec->OutSecOff;
|
|
uint8_t *BufLoc = Buf + Offset;
|
|
RelType Type = Rel.Type;
|
|
|
|
uint64_t AddrLoc = getOutputSection()->Addr + Offset;
|
|
RelExpr Expr = Rel.Expr;
|
|
uint64_t TargetVA = SignExtend64(
|
|
getRelocTargetVA(File, Type, Rel.Addend, AddrLoc, *Rel.Sym, Expr),
|
|
Bits);
|
|
|
|
switch (Expr) {
|
|
case R_RELAX_GOT_PC:
|
|
case R_RELAX_GOT_PC_NOPIC:
|
|
Target->relaxGot(BufLoc, TargetVA);
|
|
break;
|
|
case R_RELAX_TLS_IE_TO_LE:
|
|
Target->relaxTlsIeToLe(BufLoc, Type, TargetVA);
|
|
break;
|
|
case R_RELAX_TLS_LD_TO_LE:
|
|
case R_RELAX_TLS_LD_TO_LE_ABS:
|
|
Target->relaxTlsLdToLe(BufLoc, Type, TargetVA);
|
|
break;
|
|
case R_RELAX_TLS_GD_TO_LE:
|
|
case R_RELAX_TLS_GD_TO_LE_NEG:
|
|
Target->relaxTlsGdToLe(BufLoc, Type, TargetVA);
|
|
break;
|
|
case R_AARCH64_RELAX_TLS_GD_TO_IE_PAGE_PC:
|
|
case R_RELAX_TLS_GD_TO_IE:
|
|
case R_RELAX_TLS_GD_TO_IE_ABS:
|
|
case R_RELAX_TLS_GD_TO_IE_GOT_OFF:
|
|
case R_RELAX_TLS_GD_TO_IE_GOTPLT:
|
|
Target->relaxTlsGdToIe(BufLoc, Type, TargetVA);
|
|
break;
|
|
case R_PPC_CALL:
|
|
// If this is a call to __tls_get_addr, it may be part of a TLS
|
|
// sequence that has been relaxed and turned into a nop. In this
|
|
// case, we don't want to handle it as a call.
|
|
if (read32(BufLoc) == 0x60000000) // nop
|
|
break;
|
|
|
|
// Patch a nop (0x60000000) to a ld.
|
|
if (Rel.Sym->NeedsTocRestore) {
|
|
if (BufLoc + 8 > BufEnd || read32(BufLoc + 4) != 0x60000000) {
|
|
error(getErrorLocation(BufLoc) + "call lacks nop, can't restore toc");
|
|
break;
|
|
}
|
|
write32(BufLoc + 4, 0xe8410018); // ld %r2, 24(%r1)
|
|
}
|
|
Target->relocateOne(BufLoc, Type, TargetVA);
|
|
break;
|
|
default:
|
|
Target->relocateOne(BufLoc, Type, TargetVA);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
// For each function-defining prologue, find any calls to __morestack,
|
|
// and replace them with calls to __morestack_non_split.
|
|
static void switchMorestackCallsToMorestackNonSplit(
|
|
DenseSet<Defined *> &Prologues, std::vector<Relocation *> &MorestackCalls) {
|
|
|
|
// If the target adjusted a function's prologue, all calls to
|
|
// __morestack inside that function should be switched to
|
|
// __morestack_non_split.
|
|
Symbol *MoreStackNonSplit = Symtab->find("__morestack_non_split");
|
|
if (!MoreStackNonSplit) {
|
|
error("Mixing split-stack objects requires a definition of "
|
|
"__morestack_non_split");
|
|
return;
|
|
}
|
|
|
|
// Sort both collections to compare addresses efficiently.
|
|
llvm::sort(MorestackCalls, [](const Relocation *L, const Relocation *R) {
|
|
return L->Offset < R->Offset;
|
|
});
|
|
std::vector<Defined *> Functions(Prologues.begin(), Prologues.end());
|
|
llvm::sort(Functions, [](const Defined *L, const Defined *R) {
|
|
return L->Value < R->Value;
|
|
});
|
|
|
|
auto It = MorestackCalls.begin();
|
|
for (Defined *F : Functions) {
|
|
// Find the first call to __morestack within the function.
|
|
while (It != MorestackCalls.end() && (*It)->Offset < F->Value)
|
|
++It;
|
|
// Adjust all calls inside the function.
|
|
while (It != MorestackCalls.end() && (*It)->Offset < F->Value + F->Size) {
|
|
(*It)->Sym = MoreStackNonSplit;
|
|
++It;
|
|
}
|
|
}
|
|
}
|
|
|
|
static bool enclosingPrologueAttempted(uint64_t Offset,
|
|
const DenseSet<Defined *> &Prologues) {
|
|
for (Defined *F : Prologues)
|
|
if (F->Value <= Offset && Offset < F->Value + F->Size)
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
// If a function compiled for split stack calls a function not
|
|
// compiled for split stack, then the caller needs its prologue
|
|
// adjusted to ensure that the called function will have enough stack
|
|
// available. Find those functions, and adjust their prologues.
|
|
template <class ELFT>
|
|
void InputSectionBase::adjustSplitStackFunctionPrologues(uint8_t *Buf,
|
|
uint8_t *End) {
|
|
if (!getFile<ELFT>()->SplitStack)
|
|
return;
|
|
DenseSet<Defined *> Prologues;
|
|
std::vector<Relocation *> MorestackCalls;
|
|
|
|
for (Relocation &Rel : Relocations) {
|
|
// Local symbols can't possibly be cross-calls, and should have been
|
|
// resolved long before this line.
|
|
if (Rel.Sym->isLocal())
|
|
continue;
|
|
|
|
// Ignore calls into the split-stack api.
|
|
if (Rel.Sym->getName().startswith("__morestack")) {
|
|
if (Rel.Sym->getName().equals("__morestack"))
|
|
MorestackCalls.push_back(&Rel);
|
|
continue;
|
|
}
|
|
|
|
// A relocation to non-function isn't relevant. Sometimes
|
|
// __morestack is not marked as a function, so this check comes
|
|
// after the name check.
|
|
if (Rel.Sym->Type != STT_FUNC)
|
|
continue;
|
|
|
|
// If the callee's-file was compiled with split stack, nothing to do. In
|
|
// this context, a "Defined" symbol is one "defined by the binary currently
|
|
// being produced". So an "undefined" symbol might be provided by a shared
|
|
// library. It is not possible to tell how such symbols were compiled, so be
|
|
// conservative.
|
|
if (Defined *D = dyn_cast<Defined>(Rel.Sym))
|
|
if (InputSection *IS = cast_or_null<InputSection>(D->Section))
|
|
if (!IS || !IS->getFile<ELFT>() || IS->getFile<ELFT>()->SplitStack)
|
|
continue;
|
|
|
|
if (enclosingPrologueAttempted(Rel.Offset, Prologues))
|
|
continue;
|
|
|
|
if (Defined *F = getEnclosingFunction<ELFT>(Rel.Offset)) {
|
|
Prologues.insert(F);
|
|
if (Target->adjustPrologueForCrossSplitStack(Buf + getOffset(F->Value),
|
|
End, F->StOther))
|
|
continue;
|
|
if (!getFile<ELFT>()->SomeNoSplitStack)
|
|
error(lld::toString(this) + ": " + F->getName() +
|
|
" (with -fsplit-stack) calls " + Rel.Sym->getName() +
|
|
" (without -fsplit-stack), but couldn't adjust its prologue");
|
|
}
|
|
}
|
|
|
|
if (Target->NeedsMoreStackNonSplit)
|
|
switchMorestackCallsToMorestackNonSplit(Prologues, MorestackCalls);
|
|
}
|
|
|
|
template <class ELFT> void InputSection::writeTo(uint8_t *Buf) {
|
|
if (Type == SHT_NOBITS)
|
|
return;
|
|
|
|
if (auto *S = dyn_cast<SyntheticSection>(this)) {
|
|
S->writeTo(Buf + OutSecOff);
|
|
return;
|
|
}
|
|
|
|
// If -r or --emit-relocs is given, then an InputSection
|
|
// may be a relocation section.
|
|
if (Type == SHT_RELA) {
|
|
copyRelocations<ELFT>(Buf + OutSecOff, getDataAs<typename ELFT::Rela>());
|
|
return;
|
|
}
|
|
if (Type == SHT_REL) {
|
|
copyRelocations<ELFT>(Buf + OutSecOff, getDataAs<typename ELFT::Rel>());
|
|
return;
|
|
}
|
|
|
|
// If -r is given, we may have a SHT_GROUP section.
|
|
if (Type == SHT_GROUP) {
|
|
copyShtGroup<ELFT>(Buf + OutSecOff);
|
|
return;
|
|
}
|
|
|
|
// If this is a compressed section, uncompress section contents directly
|
|
// to the buffer.
|
|
if (UncompressedSize >= 0) {
|
|
size_t Size = UncompressedSize;
|
|
if (Error E = zlib::uncompress(toStringRef(RawData),
|
|
(char *)(Buf + OutSecOff), Size))
|
|
fatal(toString(this) +
|
|
": uncompress failed: " + llvm::toString(std::move(E)));
|
|
uint8_t *BufEnd = Buf + OutSecOff + Size;
|
|
relocate<ELFT>(Buf, BufEnd);
|
|
return;
|
|
}
|
|
|
|
// Copy section contents from source object file to output file
|
|
// and then apply relocations.
|
|
memcpy(Buf + OutSecOff, data().data(), data().size());
|
|
uint8_t *BufEnd = Buf + OutSecOff + data().size();
|
|
relocate<ELFT>(Buf, BufEnd);
|
|
}
|
|
|
|
void InputSection::replace(InputSection *Other) {
|
|
Alignment = std::max(Alignment, Other->Alignment);
|
|
Other->Repl = Repl;
|
|
Other->Live = false;
|
|
}
|
|
|
|
template <class ELFT>
|
|
EhInputSection::EhInputSection(ObjFile<ELFT> &F,
|
|
const typename ELFT::Shdr &Header,
|
|
StringRef Name)
|
|
: InputSectionBase(F, Header, Name, InputSectionBase::EHFrame) {}
|
|
|
|
SyntheticSection *EhInputSection::getParent() const {
|
|
return cast_or_null<SyntheticSection>(Parent);
|
|
}
|
|
|
|
// Returns the index of the first relocation that points to a region between
|
|
// Begin and Begin+Size.
|
|
template <class IntTy, class RelTy>
|
|
static unsigned getReloc(IntTy Begin, IntTy Size, const ArrayRef<RelTy> &Rels,
|
|
unsigned &RelocI) {
|
|
// Start search from RelocI for fast access. That works because the
|
|
// relocations are sorted in .eh_frame.
|
|
for (unsigned N = Rels.size(); RelocI < N; ++RelocI) {
|
|
const RelTy &Rel = Rels[RelocI];
|
|
if (Rel.r_offset < Begin)
|
|
continue;
|
|
|
|
if (Rel.r_offset < Begin + Size)
|
|
return RelocI;
|
|
return -1;
|
|
}
|
|
return -1;
|
|
}
|
|
|
|
// .eh_frame is a sequence of CIE or FDE records.
|
|
// This function splits an input section into records and returns them.
|
|
template <class ELFT> void EhInputSection::split() {
|
|
if (AreRelocsRela)
|
|
split<ELFT>(relas<ELFT>());
|
|
else
|
|
split<ELFT>(rels<ELFT>());
|
|
}
|
|
|
|
template <class ELFT, class RelTy>
|
|
void EhInputSection::split(ArrayRef<RelTy> Rels) {
|
|
unsigned RelI = 0;
|
|
for (size_t Off = 0, End = data().size(); Off != End;) {
|
|
size_t Size = readEhRecordSize(this, Off);
|
|
Pieces.emplace_back(Off, this, Size, getReloc(Off, Size, Rels, RelI));
|
|
// The empty record is the end marker.
|
|
if (Size == 4)
|
|
break;
|
|
Off += Size;
|
|
}
|
|
}
|
|
|
|
static size_t findNull(StringRef S, size_t EntSize) {
|
|
// Optimize the common case.
|
|
if (EntSize == 1)
|
|
return S.find(0);
|
|
|
|
for (unsigned I = 0, N = S.size(); I != N; I += EntSize) {
|
|
const char *B = S.begin() + I;
|
|
if (std::all_of(B, B + EntSize, [](char C) { return C == 0; }))
|
|
return I;
|
|
}
|
|
return StringRef::npos;
|
|
}
|
|
|
|
SyntheticSection *MergeInputSection::getParent() const {
|
|
return cast_or_null<SyntheticSection>(Parent);
|
|
}
|
|
|
|
// Split SHF_STRINGS section. Such section is a sequence of
|
|
// null-terminated strings.
|
|
void MergeInputSection::splitStrings(ArrayRef<uint8_t> Data, size_t EntSize) {
|
|
size_t Off = 0;
|
|
bool IsAlloc = Flags & SHF_ALLOC;
|
|
StringRef S = toStringRef(Data);
|
|
|
|
while (!S.empty()) {
|
|
size_t End = findNull(S, EntSize);
|
|
if (End == StringRef::npos)
|
|
fatal(toString(this) + ": string is not null terminated");
|
|
size_t Size = End + EntSize;
|
|
|
|
Pieces.emplace_back(Off, xxHash64(S.substr(0, Size)), !IsAlloc);
|
|
S = S.substr(Size);
|
|
Off += Size;
|
|
}
|
|
}
|
|
|
|
// Split non-SHF_STRINGS section. Such section is a sequence of
|
|
// fixed size records.
|
|
void MergeInputSection::splitNonStrings(ArrayRef<uint8_t> Data,
|
|
size_t EntSize) {
|
|
size_t Size = Data.size();
|
|
assert((Size % EntSize) == 0);
|
|
bool IsAlloc = Flags & SHF_ALLOC;
|
|
|
|
for (size_t I = 0; I != Size; I += EntSize)
|
|
Pieces.emplace_back(I, xxHash64(Data.slice(I, EntSize)), !IsAlloc);
|
|
}
|
|
|
|
template <class ELFT>
|
|
MergeInputSection::MergeInputSection(ObjFile<ELFT> &F,
|
|
const typename ELFT::Shdr &Header,
|
|
StringRef Name)
|
|
: InputSectionBase(F, Header, Name, InputSectionBase::Merge) {}
|
|
|
|
MergeInputSection::MergeInputSection(uint64_t Flags, uint32_t Type,
|
|
uint64_t Entsize, ArrayRef<uint8_t> Data,
|
|
StringRef Name)
|
|
: InputSectionBase(nullptr, Flags, Type, Entsize, /*Link*/ 0, /*Info*/ 0,
|
|
/*Alignment*/ Entsize, Data, Name, SectionBase::Merge) {}
|
|
|
|
// This function is called after we obtain a complete list of input sections
|
|
// that need to be linked. This is responsible to split section contents
|
|
// into small chunks for further processing.
|
|
//
|
|
// Note that this function is called from parallelForEach. This must be
|
|
// thread-safe (i.e. no memory allocation from the pools).
|
|
void MergeInputSection::splitIntoPieces() {
|
|
assert(Pieces.empty());
|
|
|
|
if (Flags & SHF_STRINGS)
|
|
splitStrings(data(), Entsize);
|
|
else
|
|
splitNonStrings(data(), Entsize);
|
|
}
|
|
|
|
SectionPiece *MergeInputSection::getSectionPiece(uint64_t Offset) {
|
|
if (this->data().size() <= Offset)
|
|
fatal(toString(this) + ": offset is outside the section");
|
|
|
|
// If Offset is not at beginning of a section piece, it is not in the map.
|
|
// In that case we need to do a binary search of the original section piece vector.
|
|
auto It = llvm::bsearch(Pieces,
|
|
[=](SectionPiece P) { return Offset < P.InputOff; });
|
|
return &It[-1];
|
|
}
|
|
|
|
// Returns the offset in an output section for a given input offset.
|
|
// Because contents of a mergeable section is not contiguous in output,
|
|
// it is not just an addition to a base output offset.
|
|
uint64_t MergeInputSection::getParentOffset(uint64_t Offset) const {
|
|
// If Offset is not at beginning of a section piece, it is not in the map.
|
|
// In that case we need to search from the original section piece vector.
|
|
const SectionPiece &Piece =
|
|
*(const_cast<MergeInputSection *>(this)->getSectionPiece (Offset));
|
|
uint64_t Addend = Offset - Piece.InputOff;
|
|
return Piece.OutputOff + Addend;
|
|
}
|
|
|
|
template InputSection::InputSection(ObjFile<ELF32LE> &, const ELF32LE::Shdr &,
|
|
StringRef);
|
|
template InputSection::InputSection(ObjFile<ELF32BE> &, const ELF32BE::Shdr &,
|
|
StringRef);
|
|
template InputSection::InputSection(ObjFile<ELF64LE> &, const ELF64LE::Shdr &,
|
|
StringRef);
|
|
template InputSection::InputSection(ObjFile<ELF64BE> &, const ELF64BE::Shdr &,
|
|
StringRef);
|
|
|
|
template std::string InputSectionBase::getLocation<ELF32LE>(uint64_t);
|
|
template std::string InputSectionBase::getLocation<ELF32BE>(uint64_t);
|
|
template std::string InputSectionBase::getLocation<ELF64LE>(uint64_t);
|
|
template std::string InputSectionBase::getLocation<ELF64BE>(uint64_t);
|
|
|
|
template void InputSection::writeTo<ELF32LE>(uint8_t *);
|
|
template void InputSection::writeTo<ELF32BE>(uint8_t *);
|
|
template void InputSection::writeTo<ELF64LE>(uint8_t *);
|
|
template void InputSection::writeTo<ELF64BE>(uint8_t *);
|
|
|
|
template MergeInputSection::MergeInputSection(ObjFile<ELF32LE> &,
|
|
const ELF32LE::Shdr &, StringRef);
|
|
template MergeInputSection::MergeInputSection(ObjFile<ELF32BE> &,
|
|
const ELF32BE::Shdr &, StringRef);
|
|
template MergeInputSection::MergeInputSection(ObjFile<ELF64LE> &,
|
|
const ELF64LE::Shdr &, StringRef);
|
|
template MergeInputSection::MergeInputSection(ObjFile<ELF64BE> &,
|
|
const ELF64BE::Shdr &, StringRef);
|
|
|
|
template EhInputSection::EhInputSection(ObjFile<ELF32LE> &,
|
|
const ELF32LE::Shdr &, StringRef);
|
|
template EhInputSection::EhInputSection(ObjFile<ELF32BE> &,
|
|
const ELF32BE::Shdr &, StringRef);
|
|
template EhInputSection::EhInputSection(ObjFile<ELF64LE> &,
|
|
const ELF64LE::Shdr &, StringRef);
|
|
template EhInputSection::EhInputSection(ObjFile<ELF64BE> &,
|
|
const ELF64BE::Shdr &, StringRef);
|
|
|
|
template void EhInputSection::split<ELF32LE>();
|
|
template void EhInputSection::split<ELF32BE>();
|
|
template void EhInputSection::split<ELF64LE>();
|
|
template void EhInputSection::split<ELF64BE>();
|