forked from OSchip/llvm-project
2401 lines
82 KiB
C++
2401 lines
82 KiB
C++
//===- SyntheticSections.cpp ----------------------------------------------===//
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//
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// The LLVM Linker
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains linker-synthesized sections. Currently,
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// synthetic sections are created either output sections or input sections,
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// but we are rewriting code so that all synthetic sections are created as
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// input sections.
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//
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//===----------------------------------------------------------------------===//
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#include "SyntheticSections.h"
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#include "Config.h"
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#include "Error.h"
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#include "InputFiles.h"
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#include "LinkerScript.h"
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#include "Memory.h"
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#include "OutputSections.h"
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#include "Strings.h"
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#include "SymbolTable.h"
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#include "Target.h"
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#include "Threads.h"
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#include "Writer.h"
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#include "lld/Config/Version.h"
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#include "llvm/BinaryFormat/Dwarf.h"
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#include "llvm/DebugInfo/DWARF/DWARFDebugPubTable.h"
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#include "llvm/Object/Decompressor.h"
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#include "llvm/Object/ELFObjectFile.h"
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#include "llvm/Support/Endian.h"
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#include "llvm/Support/MD5.h"
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#include "llvm/Support/RandomNumberGenerator.h"
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#include "llvm/Support/SHA1.h"
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#include "llvm/Support/xxhash.h"
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#include <cstdlib>
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using namespace llvm;
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using namespace llvm::dwarf;
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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 lld;
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using namespace lld::elf;
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uint64_t SyntheticSection::getVA() const {
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if (OutputSection *Sec = getParent())
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return Sec->Addr + OutSecOff;
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return 0;
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}
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template <class ELFT> static std::vector<DefinedCommon *> getCommonSymbols() {
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std::vector<DefinedCommon *> V;
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for (Symbol *S : Symtab<ELFT>::X->getSymbols())
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if (auto *B = dyn_cast<DefinedCommon>(S->body()))
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V.push_back(B);
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return V;
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}
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// Find all common symbols and allocate space for them.
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template <class ELFT> InputSection *elf::createCommonSection() {
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if (!Config->DefineCommon)
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return nullptr;
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// Sort the common symbols by alignment as an heuristic to pack them better.
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std::vector<DefinedCommon *> Syms = getCommonSymbols<ELFT>();
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if (Syms.empty())
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return nullptr;
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std::stable_sort(Syms.begin(), Syms.end(),
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[](const DefinedCommon *A, const DefinedCommon *B) {
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return A->Alignment > B->Alignment;
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});
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BssSection *Sec = make<BssSection>("COMMON");
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for (DefinedCommon *Sym : Syms)
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Sym->Offset = Sec->reserveSpace(Sym->Size, Sym->Alignment);
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return Sec;
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}
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// Returns an LLD version string.
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static ArrayRef<uint8_t> getVersion() {
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// Check LLD_VERSION first for ease of testing.
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// You can get consitent output by using the environment variable.
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// This is only for testing.
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StringRef S = getenv("LLD_VERSION");
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if (S.empty())
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S = Saver.save(Twine("Linker: ") + getLLDVersion());
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// +1 to include the terminating '\0'.
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return {(const uint8_t *)S.data(), S.size() + 1};
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}
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// Creates a .comment section containing LLD version info.
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// With this feature, you can identify LLD-generated binaries easily
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// by "readelf --string-dump .comment <file>".
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// The returned object is a mergeable string section.
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template <class ELFT> MergeInputSection *elf::createCommentSection() {
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typename ELFT::Shdr Hdr = {};
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Hdr.sh_flags = SHF_MERGE | SHF_STRINGS;
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Hdr.sh_type = SHT_PROGBITS;
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Hdr.sh_entsize = 1;
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Hdr.sh_addralign = 1;
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auto *Ret =
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make<MergeInputSection>((ObjectFile<ELFT> *)nullptr, &Hdr, ".comment");
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Ret->Data = getVersion();
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Ret->splitIntoPieces();
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return Ret;
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}
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// .MIPS.abiflags section.
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template <class ELFT>
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MipsAbiFlagsSection<ELFT>::MipsAbiFlagsSection(Elf_Mips_ABIFlags Flags)
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: SyntheticSection(SHF_ALLOC, SHT_MIPS_ABIFLAGS, 8, ".MIPS.abiflags"),
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Flags(Flags) {
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this->Entsize = sizeof(Elf_Mips_ABIFlags);
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}
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template <class ELFT> void MipsAbiFlagsSection<ELFT>::writeTo(uint8_t *Buf) {
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memcpy(Buf, &Flags, sizeof(Flags));
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}
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template <class ELFT>
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MipsAbiFlagsSection<ELFT> *MipsAbiFlagsSection<ELFT>::create() {
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Elf_Mips_ABIFlags Flags = {};
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bool Create = false;
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for (InputSectionBase *Sec : InputSections) {
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if (Sec->Type != SHT_MIPS_ABIFLAGS)
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continue;
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Sec->Live = false;
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Create = true;
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std::string Filename = toString(Sec->getFile<ELFT>());
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const size_t Size = Sec->Data.size();
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// Older version of BFD (such as the default FreeBSD linker) concatenate
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// .MIPS.abiflags instead of merging. To allow for this case (or potential
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// zero padding) we ignore everything after the first Elf_Mips_ABIFlags
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if (Size < sizeof(Elf_Mips_ABIFlags)) {
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error(Filename + ": invalid size of .MIPS.abiflags section: got " +
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Twine(Size) + " instead of " + Twine(sizeof(Elf_Mips_ABIFlags)));
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return nullptr;
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}
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auto *S = reinterpret_cast<const Elf_Mips_ABIFlags *>(Sec->Data.data());
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if (S->version != 0) {
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error(Filename + ": unexpected .MIPS.abiflags version " +
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Twine(S->version));
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return nullptr;
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}
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// LLD checks ISA compatibility in getMipsEFlags(). Here we just
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// select the highest number of ISA/Rev/Ext.
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Flags.isa_level = std::max(Flags.isa_level, S->isa_level);
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Flags.isa_rev = std::max(Flags.isa_rev, S->isa_rev);
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Flags.isa_ext = std::max(Flags.isa_ext, S->isa_ext);
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Flags.gpr_size = std::max(Flags.gpr_size, S->gpr_size);
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Flags.cpr1_size = std::max(Flags.cpr1_size, S->cpr1_size);
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Flags.cpr2_size = std::max(Flags.cpr2_size, S->cpr2_size);
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Flags.ases |= S->ases;
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Flags.flags1 |= S->flags1;
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Flags.flags2 |= S->flags2;
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Flags.fp_abi = elf::getMipsFpAbiFlag(Flags.fp_abi, S->fp_abi, Filename);
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};
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if (Create)
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return make<MipsAbiFlagsSection<ELFT>>(Flags);
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return nullptr;
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}
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// .MIPS.options section.
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template <class ELFT>
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MipsOptionsSection<ELFT>::MipsOptionsSection(Elf_Mips_RegInfo Reginfo)
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: SyntheticSection(SHF_ALLOC, SHT_MIPS_OPTIONS, 8, ".MIPS.options"),
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Reginfo(Reginfo) {
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this->Entsize = sizeof(Elf_Mips_Options) + sizeof(Elf_Mips_RegInfo);
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}
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template <class ELFT> void MipsOptionsSection<ELFT>::writeTo(uint8_t *Buf) {
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auto *Options = reinterpret_cast<Elf_Mips_Options *>(Buf);
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Options->kind = ODK_REGINFO;
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Options->size = getSize();
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if (!Config->Relocatable)
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Reginfo.ri_gp_value = InX::MipsGot->getGp();
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memcpy(Buf + sizeof(Elf_Mips_Options), &Reginfo, sizeof(Reginfo));
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}
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template <class ELFT>
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MipsOptionsSection<ELFT> *MipsOptionsSection<ELFT>::create() {
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// N64 ABI only.
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if (!ELFT::Is64Bits)
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return nullptr;
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Elf_Mips_RegInfo Reginfo = {};
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bool Create = false;
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for (InputSectionBase *Sec : InputSections) {
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if (Sec->Type != SHT_MIPS_OPTIONS)
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continue;
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Sec->Live = false;
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Create = true;
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std::string Filename = toString(Sec->getFile<ELFT>());
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ArrayRef<uint8_t> D = Sec->Data;
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while (!D.empty()) {
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if (D.size() < sizeof(Elf_Mips_Options)) {
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error(Filename + ": invalid size of .MIPS.options section");
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break;
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}
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auto *Opt = reinterpret_cast<const Elf_Mips_Options *>(D.data());
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if (Opt->kind == ODK_REGINFO) {
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if (Config->Relocatable && Opt->getRegInfo().ri_gp_value)
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error(Filename + ": unsupported non-zero ri_gp_value");
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Reginfo.ri_gprmask |= Opt->getRegInfo().ri_gprmask;
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Sec->getFile<ELFT>()->MipsGp0 = Opt->getRegInfo().ri_gp_value;
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break;
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}
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if (!Opt->size)
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fatal(Filename + ": zero option descriptor size");
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D = D.slice(Opt->size);
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}
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};
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if (Create)
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return make<MipsOptionsSection<ELFT>>(Reginfo);
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return nullptr;
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}
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// MIPS .reginfo section.
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template <class ELFT>
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MipsReginfoSection<ELFT>::MipsReginfoSection(Elf_Mips_RegInfo Reginfo)
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: SyntheticSection(SHF_ALLOC, SHT_MIPS_REGINFO, 4, ".reginfo"),
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Reginfo(Reginfo) {
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this->Entsize = sizeof(Elf_Mips_RegInfo);
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}
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template <class ELFT> void MipsReginfoSection<ELFT>::writeTo(uint8_t *Buf) {
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if (!Config->Relocatable)
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Reginfo.ri_gp_value = InX::MipsGot->getGp();
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memcpy(Buf, &Reginfo, sizeof(Reginfo));
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}
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template <class ELFT>
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MipsReginfoSection<ELFT> *MipsReginfoSection<ELFT>::create() {
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// Section should be alive for O32 and N32 ABIs only.
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if (ELFT::Is64Bits)
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return nullptr;
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Elf_Mips_RegInfo Reginfo = {};
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bool Create = false;
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for (InputSectionBase *Sec : InputSections) {
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if (Sec->Type != SHT_MIPS_REGINFO)
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continue;
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Sec->Live = false;
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Create = true;
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if (Sec->Data.size() != sizeof(Elf_Mips_RegInfo)) {
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error(toString(Sec->getFile<ELFT>()) +
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": invalid size of .reginfo section");
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return nullptr;
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}
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auto *R = reinterpret_cast<const Elf_Mips_RegInfo *>(Sec->Data.data());
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if (Config->Relocatable && R->ri_gp_value)
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error(toString(Sec->getFile<ELFT>()) +
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": unsupported non-zero ri_gp_value");
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Reginfo.ri_gprmask |= R->ri_gprmask;
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Sec->getFile<ELFT>()->MipsGp0 = R->ri_gp_value;
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};
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if (Create)
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return make<MipsReginfoSection<ELFT>>(Reginfo);
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return nullptr;
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}
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InputSection *elf::createInterpSection() {
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// StringSaver guarantees that the returned string ends with '\0'.
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StringRef S = Saver.save(Config->DynamicLinker);
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ArrayRef<uint8_t> Contents = {(const uint8_t *)S.data(), S.size() + 1};
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auto *Sec =
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make<InputSection>(SHF_ALLOC, SHT_PROGBITS, 1, Contents, ".interp");
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Sec->Live = true;
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return Sec;
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}
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SymbolBody *elf::addSyntheticLocal(StringRef Name, uint8_t Type, uint64_t Value,
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uint64_t Size, InputSectionBase *Section) {
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auto *S = make<DefinedRegular>(Name, /*IsLocal*/ true, STV_DEFAULT, Type,
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Value, Size, Section, nullptr);
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if (InX::SymTab)
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InX::SymTab->addSymbol(S);
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return S;
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}
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static size_t getHashSize() {
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switch (Config->BuildId) {
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case BuildIdKind::Fast:
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return 8;
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case BuildIdKind::Md5:
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case BuildIdKind::Uuid:
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return 16;
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case BuildIdKind::Sha1:
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return 20;
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case BuildIdKind::Hexstring:
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return Config->BuildIdVector.size();
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default:
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llvm_unreachable("unknown BuildIdKind");
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}
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}
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BuildIdSection::BuildIdSection()
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: SyntheticSection(SHF_ALLOC, SHT_NOTE, 1, ".note.gnu.build-id"),
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HashSize(getHashSize()) {}
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void BuildIdSection::writeTo(uint8_t *Buf) {
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endianness E = Config->Endianness;
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write32(Buf, 4, E); // Name size
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write32(Buf + 4, HashSize, E); // Content size
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write32(Buf + 8, NT_GNU_BUILD_ID, E); // Type
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memcpy(Buf + 12, "GNU", 4); // Name string
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HashBuf = Buf + 16;
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}
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// Split one uint8 array into small pieces of uint8 arrays.
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static std::vector<ArrayRef<uint8_t>> split(ArrayRef<uint8_t> Arr,
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size_t ChunkSize) {
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std::vector<ArrayRef<uint8_t>> Ret;
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while (Arr.size() > ChunkSize) {
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Ret.push_back(Arr.take_front(ChunkSize));
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Arr = Arr.drop_front(ChunkSize);
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}
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if (!Arr.empty())
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Ret.push_back(Arr);
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return Ret;
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}
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// Computes a hash value of Data using a given hash function.
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// In order to utilize multiple cores, we first split data into 1MB
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// chunks, compute a hash for each chunk, and then compute a hash value
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// of the hash values.
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void BuildIdSection::computeHash(
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llvm::ArrayRef<uint8_t> Data,
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std::function<void(uint8_t *Dest, ArrayRef<uint8_t> Arr)> HashFn) {
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std::vector<ArrayRef<uint8_t>> Chunks = split(Data, 1024 * 1024);
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std::vector<uint8_t> Hashes(Chunks.size() * HashSize);
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// Compute hash values.
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parallelForEachN(0, Chunks.size(), [&](size_t I) {
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HashFn(Hashes.data() + I * HashSize, Chunks[I]);
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});
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// Write to the final output buffer.
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HashFn(HashBuf, Hashes);
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}
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BssSection::BssSection(StringRef Name)
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: SyntheticSection(SHF_ALLOC | SHF_WRITE, SHT_NOBITS, 0, Name) {}
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size_t BssSection::reserveSpace(uint64_t Size, uint32_t Alignment) {
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if (OutputSection *Sec = getParent())
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Sec->updateAlignment(Alignment);
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this->Size = alignTo(this->Size, Alignment) + Size;
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this->Alignment = std::max(this->Alignment, Alignment);
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return this->Size - Size;
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}
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void BuildIdSection::writeBuildId(ArrayRef<uint8_t> Buf) {
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switch (Config->BuildId) {
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case BuildIdKind::Fast:
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computeHash(Buf, [](uint8_t *Dest, ArrayRef<uint8_t> Arr) {
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write64le(Dest, xxHash64(toStringRef(Arr)));
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});
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break;
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case BuildIdKind::Md5:
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computeHash(Buf, [](uint8_t *Dest, ArrayRef<uint8_t> Arr) {
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memcpy(Dest, MD5::hash(Arr).data(), 16);
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});
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break;
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case BuildIdKind::Sha1:
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computeHash(Buf, [](uint8_t *Dest, ArrayRef<uint8_t> Arr) {
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memcpy(Dest, SHA1::hash(Arr).data(), 20);
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});
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break;
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case BuildIdKind::Uuid:
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if (getRandomBytes(HashBuf, HashSize))
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error("entropy source failure");
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break;
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case BuildIdKind::Hexstring:
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memcpy(HashBuf, Config->BuildIdVector.data(), Config->BuildIdVector.size());
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break;
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default:
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llvm_unreachable("unknown BuildIdKind");
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}
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}
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template <class ELFT>
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EhFrameSection<ELFT>::EhFrameSection()
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: SyntheticSection(SHF_ALLOC, SHT_PROGBITS, 1, ".eh_frame") {}
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// Search for an existing CIE record or create a new one.
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// CIE records from input object files are uniquified by their contents
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// and where their relocations point to.
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template <class ELFT>
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template <class RelTy>
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CieRecord *EhFrameSection<ELFT>::addCie(EhSectionPiece &Piece,
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ArrayRef<RelTy> Rels) {
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auto *Sec = cast<EhInputSection>(Piece.ID);
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const endianness E = ELFT::TargetEndianness;
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if (read32<E>(Piece.data().data() + 4) != 0)
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fatal(toString(Sec) + ": CIE expected at beginning of .eh_frame");
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SymbolBody *Personality = nullptr;
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unsigned FirstRelI = Piece.FirstRelocation;
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if (FirstRelI != (unsigned)-1)
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Personality =
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&Sec->template getFile<ELFT>()->getRelocTargetSym(Rels[FirstRelI]);
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// Search for an existing CIE by CIE contents/relocation target pair.
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CieRecord *Cie = &CieMap[{Piece.data(), Personality}];
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// If not found, create a new one.
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if (Cie->Piece == nullptr) {
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Cie->Piece = &Piece;
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Cies.push_back(Cie);
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}
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return Cie;
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}
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// There is one FDE per function. Returns true if a given FDE
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// points to a live function.
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template <class ELFT>
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template <class RelTy>
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bool EhFrameSection<ELFT>::isFdeLive(EhSectionPiece &Piece,
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ArrayRef<RelTy> Rels) {
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auto *Sec = cast<EhInputSection>(Piece.ID);
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unsigned FirstRelI = Piece.FirstRelocation;
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if (FirstRelI == (unsigned)-1)
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return false;
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const RelTy &Rel = Rels[FirstRelI];
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SymbolBody &B = Sec->template getFile<ELFT>()->getRelocTargetSym(Rel);
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auto *D = dyn_cast<DefinedRegular>(&B);
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if (!D || !D->Section)
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return false;
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auto *Target =
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cast<InputSectionBase>(cast<InputSectionBase>(D->Section)->Repl);
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return Target && Target->Live;
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}
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// .eh_frame is a sequence of CIE or FDE records. In general, there
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// is one CIE record per input object file which is followed by
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// a list of FDEs. This function searches an existing CIE or create a new
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// one and associates FDEs to the CIE.
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template <class ELFT>
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template <class RelTy>
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void EhFrameSection<ELFT>::addSectionAux(EhInputSection *Sec,
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ArrayRef<RelTy> Rels) {
|
|
const endianness E = ELFT::TargetEndianness;
|
|
|
|
DenseMap<size_t, CieRecord *> OffsetToCie;
|
|
for (EhSectionPiece &Piece : Sec->Pieces) {
|
|
// The empty record is the end marker.
|
|
if (Piece.size() == 4)
|
|
return;
|
|
|
|
size_t Offset = Piece.InputOff;
|
|
uint32_t ID = read32<E>(Piece.data().data() + 4);
|
|
if (ID == 0) {
|
|
OffsetToCie[Offset] = addCie(Piece, Rels);
|
|
continue;
|
|
}
|
|
|
|
uint32_t CieOffset = Offset + 4 - ID;
|
|
CieRecord *Cie = OffsetToCie[CieOffset];
|
|
if (!Cie)
|
|
fatal(toString(Sec) + ": invalid CIE reference");
|
|
|
|
if (!isFdeLive(Piece, Rels))
|
|
continue;
|
|
Cie->FdePieces.push_back(&Piece);
|
|
NumFdes++;
|
|
}
|
|
}
|
|
|
|
template <class ELFT>
|
|
void EhFrameSection<ELFT>::addSection(InputSectionBase *C) {
|
|
auto *Sec = cast<EhInputSection>(C);
|
|
Sec->Parent = this;
|
|
updateAlignment(Sec->Alignment);
|
|
Sections.push_back(Sec);
|
|
for (auto *DS : Sec->DependentSections)
|
|
DependentSections.push_back(DS);
|
|
|
|
// .eh_frame is a sequence of CIE or FDE records. This function
|
|
// splits it into pieces so that we can call
|
|
// SplitInputSection::getSectionPiece on the section.
|
|
Sec->split<ELFT>();
|
|
if (Sec->Pieces.empty())
|
|
return;
|
|
|
|
if (Sec->NumRelocations) {
|
|
if (Sec->AreRelocsRela)
|
|
addSectionAux(Sec, Sec->template relas<ELFT>());
|
|
else
|
|
addSectionAux(Sec, Sec->template rels<ELFT>());
|
|
return;
|
|
}
|
|
addSectionAux(Sec, makeArrayRef<Elf_Rela>(nullptr, nullptr));
|
|
}
|
|
|
|
template <class ELFT>
|
|
static void writeCieFde(uint8_t *Buf, ArrayRef<uint8_t> D) {
|
|
memcpy(Buf, D.data(), D.size());
|
|
|
|
// Fix the size field. -4 since size does not include the size field itself.
|
|
const endianness E = ELFT::TargetEndianness;
|
|
write32<E>(Buf, alignTo(D.size(), sizeof(typename ELFT::uint)) - 4);
|
|
}
|
|
|
|
template <class ELFT> void EhFrameSection<ELFT>::finalizeContents() {
|
|
if (this->Size)
|
|
return; // Already finalized.
|
|
|
|
size_t Off = 0;
|
|
for (CieRecord *Cie : Cies) {
|
|
Cie->Piece->OutputOff = Off;
|
|
Off += alignTo(Cie->Piece->size(), Config->Wordsize);
|
|
|
|
for (EhSectionPiece *Fde : Cie->FdePieces) {
|
|
Fde->OutputOff = Off;
|
|
Off += alignTo(Fde->size(), Config->Wordsize);
|
|
}
|
|
}
|
|
|
|
// The LSB standard does not allow a .eh_frame section with zero
|
|
// Call Frame Information records. Therefore add a CIE record length
|
|
// 0 as a terminator if this .eh_frame section is empty.
|
|
if (Off == 0)
|
|
Off = 4;
|
|
|
|
this->Size = Off;
|
|
}
|
|
|
|
template <class ELFT> static uint64_t readFdeAddr(uint8_t *Buf, int Size) {
|
|
const endianness E = ELFT::TargetEndianness;
|
|
switch (Size) {
|
|
case DW_EH_PE_udata2:
|
|
return read16<E>(Buf);
|
|
case DW_EH_PE_udata4:
|
|
return read32<E>(Buf);
|
|
case DW_EH_PE_udata8:
|
|
return read64<E>(Buf);
|
|
case DW_EH_PE_absptr:
|
|
if (ELFT::Is64Bits)
|
|
return read64<E>(Buf);
|
|
return read32<E>(Buf);
|
|
}
|
|
fatal("unknown FDE size encoding");
|
|
}
|
|
|
|
// Returns the VA to which a given FDE (on a mmap'ed buffer) is applied to.
|
|
// We need it to create .eh_frame_hdr section.
|
|
template <class ELFT>
|
|
uint64_t EhFrameSection<ELFT>::getFdePc(uint8_t *Buf, size_t FdeOff,
|
|
uint8_t Enc) {
|
|
// The starting address to which this FDE applies is
|
|
// stored at FDE + 8 byte.
|
|
size_t Off = FdeOff + 8;
|
|
uint64_t Addr = readFdeAddr<ELFT>(Buf + Off, Enc & 0x7);
|
|
if ((Enc & 0x70) == DW_EH_PE_absptr)
|
|
return Addr;
|
|
if ((Enc & 0x70) == DW_EH_PE_pcrel)
|
|
return Addr + getParent()->Addr + Off;
|
|
fatal("unknown FDE size relative encoding");
|
|
}
|
|
|
|
template <class ELFT> void EhFrameSection<ELFT>::writeTo(uint8_t *Buf) {
|
|
const endianness E = ELFT::TargetEndianness;
|
|
for (CieRecord *Cie : Cies) {
|
|
size_t CieOffset = Cie->Piece->OutputOff;
|
|
writeCieFde<ELFT>(Buf + CieOffset, Cie->Piece->data());
|
|
|
|
for (EhSectionPiece *Fde : Cie->FdePieces) {
|
|
size_t Off = Fde->OutputOff;
|
|
writeCieFde<ELFT>(Buf + Off, Fde->data());
|
|
|
|
// FDE's second word should have the offset to an associated CIE.
|
|
// Write it.
|
|
write32<E>(Buf + Off + 4, Off + 4 - CieOffset);
|
|
}
|
|
}
|
|
|
|
for (EhInputSection *S : Sections)
|
|
S->relocateAlloc(Buf, nullptr);
|
|
|
|
// Construct .eh_frame_hdr. .eh_frame_hdr is a binary search table
|
|
// to get a FDE from an address to which FDE is applied. So here
|
|
// we obtain two addresses and pass them to EhFrameHdr object.
|
|
if (In<ELFT>::EhFrameHdr) {
|
|
for (CieRecord *Cie : Cies) {
|
|
uint8_t Enc = getFdeEncoding<ELFT>(Cie->Piece);
|
|
for (SectionPiece *Fde : Cie->FdePieces) {
|
|
uint64_t Pc = getFdePc(Buf, Fde->OutputOff, Enc);
|
|
uint64_t FdeVA = getParent()->Addr + Fde->OutputOff;
|
|
In<ELFT>::EhFrameHdr->addFde(Pc, FdeVA);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
GotSection::GotSection()
|
|
: SyntheticSection(SHF_ALLOC | SHF_WRITE, SHT_PROGBITS,
|
|
Target->GotEntrySize, ".got") {}
|
|
|
|
void GotSection::addEntry(SymbolBody &Sym) {
|
|
Sym.GotIndex = NumEntries;
|
|
++NumEntries;
|
|
}
|
|
|
|
bool GotSection::addDynTlsEntry(SymbolBody &Sym) {
|
|
if (Sym.GlobalDynIndex != -1U)
|
|
return false;
|
|
Sym.GlobalDynIndex = NumEntries;
|
|
// Global Dynamic TLS entries take two GOT slots.
|
|
NumEntries += 2;
|
|
return true;
|
|
}
|
|
|
|
// Reserves TLS entries for a TLS module ID and a TLS block offset.
|
|
// In total it takes two GOT slots.
|
|
bool GotSection::addTlsIndex() {
|
|
if (TlsIndexOff != uint32_t(-1))
|
|
return false;
|
|
TlsIndexOff = NumEntries * Config->Wordsize;
|
|
NumEntries += 2;
|
|
return true;
|
|
}
|
|
|
|
uint64_t GotSection::getGlobalDynAddr(const SymbolBody &B) const {
|
|
return this->getVA() + B.GlobalDynIndex * Config->Wordsize;
|
|
}
|
|
|
|
uint64_t GotSection::getGlobalDynOffset(const SymbolBody &B) const {
|
|
return B.GlobalDynIndex * Config->Wordsize;
|
|
}
|
|
|
|
void GotSection::finalizeContents() { Size = NumEntries * Config->Wordsize; }
|
|
|
|
bool GotSection::empty() const {
|
|
// If we have a relocation that is relative to GOT (such as GOTOFFREL),
|
|
// we need to emit a GOT even if it's empty.
|
|
return NumEntries == 0 && !HasGotOffRel;
|
|
}
|
|
|
|
void GotSection::writeTo(uint8_t *Buf) { relocateAlloc(Buf, Buf + Size); }
|
|
|
|
MipsGotSection::MipsGotSection()
|
|
: SyntheticSection(SHF_ALLOC | SHF_WRITE | SHF_MIPS_GPREL, SHT_PROGBITS, 16,
|
|
".got") {}
|
|
|
|
void MipsGotSection::addEntry(SymbolBody &Sym, int64_t Addend, RelExpr Expr) {
|
|
// For "true" local symbols which can be referenced from the same module
|
|
// only compiler creates two instructions for address loading:
|
|
//
|
|
// lw $8, 0($gp) # R_MIPS_GOT16
|
|
// addi $8, $8, 0 # R_MIPS_LO16
|
|
//
|
|
// The first instruction loads high 16 bits of the symbol address while
|
|
// the second adds an offset. That allows to reduce number of required
|
|
// GOT entries because only one global offset table entry is necessary
|
|
// for every 64 KBytes of local data. So for local symbols we need to
|
|
// allocate number of GOT entries to hold all required "page" addresses.
|
|
//
|
|
// All global symbols (hidden and regular) considered by compiler uniformly.
|
|
// It always generates a single `lw` instruction and R_MIPS_GOT16 relocation
|
|
// to load address of the symbol. So for each such symbol we need to
|
|
// allocate dedicated GOT entry to store its address.
|
|
//
|
|
// If a symbol is preemptible we need help of dynamic linker to get its
|
|
// final address. The corresponding GOT entries are allocated in the
|
|
// "global" part of GOT. Entries for non preemptible global symbol allocated
|
|
// in the "local" part of GOT.
|
|
//
|
|
// See "Global Offset Table" in Chapter 5:
|
|
// ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
|
|
if (Expr == R_MIPS_GOT_LOCAL_PAGE) {
|
|
// At this point we do not know final symbol value so to reduce number
|
|
// of allocated GOT entries do the following trick. Save all output
|
|
// sections referenced by GOT relocations. Then later in the `finalize`
|
|
// method calculate number of "pages" required to cover all saved output
|
|
// section and allocate appropriate number of GOT entries.
|
|
PageIndexMap.insert({Sym.getOutputSection(), 0});
|
|
return;
|
|
}
|
|
if (Sym.isTls()) {
|
|
// GOT entries created for MIPS TLS relocations behave like
|
|
// almost GOT entries from other ABIs. They go to the end
|
|
// of the global offset table.
|
|
Sym.GotIndex = TlsEntries.size();
|
|
TlsEntries.push_back(&Sym);
|
|
return;
|
|
}
|
|
auto AddEntry = [&](SymbolBody &S, uint64_t A, GotEntries &Items) {
|
|
if (S.isInGot() && !A)
|
|
return;
|
|
size_t NewIndex = Items.size();
|
|
if (!EntryIndexMap.insert({{&S, A}, NewIndex}).second)
|
|
return;
|
|
Items.emplace_back(&S, A);
|
|
if (!A)
|
|
S.GotIndex = NewIndex;
|
|
};
|
|
if (Sym.isPreemptible()) {
|
|
// Ignore addends for preemptible symbols. They got single GOT entry anyway.
|
|
AddEntry(Sym, 0, GlobalEntries);
|
|
Sym.IsInGlobalMipsGot = true;
|
|
} else if (Expr == R_MIPS_GOT_OFF32) {
|
|
AddEntry(Sym, Addend, LocalEntries32);
|
|
Sym.Is32BitMipsGot = true;
|
|
} else {
|
|
// Hold local GOT entries accessed via a 16-bit index separately.
|
|
// That allows to write them in the beginning of the GOT and keep
|
|
// their indexes as less as possible to escape relocation's overflow.
|
|
AddEntry(Sym, Addend, LocalEntries);
|
|
}
|
|
}
|
|
|
|
bool MipsGotSection::addDynTlsEntry(SymbolBody &Sym) {
|
|
if (Sym.GlobalDynIndex != -1U)
|
|
return false;
|
|
Sym.GlobalDynIndex = TlsEntries.size();
|
|
// Global Dynamic TLS entries take two GOT slots.
|
|
TlsEntries.push_back(nullptr);
|
|
TlsEntries.push_back(&Sym);
|
|
return true;
|
|
}
|
|
|
|
// Reserves TLS entries for a TLS module ID and a TLS block offset.
|
|
// In total it takes two GOT slots.
|
|
bool MipsGotSection::addTlsIndex() {
|
|
if (TlsIndexOff != uint32_t(-1))
|
|
return false;
|
|
TlsIndexOff = TlsEntries.size() * Config->Wordsize;
|
|
TlsEntries.push_back(nullptr);
|
|
TlsEntries.push_back(nullptr);
|
|
return true;
|
|
}
|
|
|
|
static uint64_t getMipsPageAddr(uint64_t Addr) {
|
|
return (Addr + 0x8000) & ~0xffff;
|
|
}
|
|
|
|
static uint64_t getMipsPageCount(uint64_t Size) {
|
|
return (Size + 0xfffe) / 0xffff + 1;
|
|
}
|
|
|
|
uint64_t MipsGotSection::getPageEntryOffset(const SymbolBody &B,
|
|
int64_t Addend) const {
|
|
const OutputSection *OutSec = B.getOutputSection();
|
|
uint64_t SecAddr = getMipsPageAddr(OutSec->Addr);
|
|
uint64_t SymAddr = getMipsPageAddr(B.getVA(Addend));
|
|
uint64_t Index = PageIndexMap.lookup(OutSec) + (SymAddr - SecAddr) / 0xffff;
|
|
assert(Index < PageEntriesNum);
|
|
return (HeaderEntriesNum + Index) * Config->Wordsize;
|
|
}
|
|
|
|
uint64_t MipsGotSection::getBodyEntryOffset(const SymbolBody &B,
|
|
int64_t Addend) const {
|
|
// Calculate offset of the GOT entries block: TLS, global, local.
|
|
uint64_t Index = HeaderEntriesNum + PageEntriesNum;
|
|
if (B.isTls())
|
|
Index += LocalEntries.size() + LocalEntries32.size() + GlobalEntries.size();
|
|
else if (B.IsInGlobalMipsGot)
|
|
Index += LocalEntries.size() + LocalEntries32.size();
|
|
else if (B.Is32BitMipsGot)
|
|
Index += LocalEntries.size();
|
|
// Calculate offset of the GOT entry in the block.
|
|
if (B.isInGot())
|
|
Index += B.GotIndex;
|
|
else {
|
|
auto It = EntryIndexMap.find({&B, Addend});
|
|
assert(It != EntryIndexMap.end());
|
|
Index += It->second;
|
|
}
|
|
return Index * Config->Wordsize;
|
|
}
|
|
|
|
uint64_t MipsGotSection::getTlsOffset() const {
|
|
return (getLocalEntriesNum() + GlobalEntries.size()) * Config->Wordsize;
|
|
}
|
|
|
|
uint64_t MipsGotSection::getGlobalDynOffset(const SymbolBody &B) const {
|
|
return B.GlobalDynIndex * Config->Wordsize;
|
|
}
|
|
|
|
const SymbolBody *MipsGotSection::getFirstGlobalEntry() const {
|
|
return GlobalEntries.empty() ? nullptr : GlobalEntries.front().first;
|
|
}
|
|
|
|
unsigned MipsGotSection::getLocalEntriesNum() const {
|
|
return HeaderEntriesNum + PageEntriesNum + LocalEntries.size() +
|
|
LocalEntries32.size();
|
|
}
|
|
|
|
void MipsGotSection::finalizeContents() {
|
|
updateAllocSize();
|
|
}
|
|
|
|
void MipsGotSection::updateAllocSize() {
|
|
PageEntriesNum = 0;
|
|
for (std::pair<const OutputSection *, size_t> &P : PageIndexMap) {
|
|
// For each output section referenced by GOT page relocations calculate
|
|
// and save into PageIndexMap an upper bound of MIPS GOT entries required
|
|
// to store page addresses of local symbols. We assume the worst case -
|
|
// each 64kb page of the output section has at least one GOT relocation
|
|
// against it. And take in account the case when the section intersects
|
|
// page boundaries.
|
|
P.second = PageEntriesNum;
|
|
PageEntriesNum += getMipsPageCount(P.first->Size);
|
|
}
|
|
Size = (getLocalEntriesNum() + GlobalEntries.size() + TlsEntries.size()) *
|
|
Config->Wordsize;
|
|
}
|
|
|
|
bool MipsGotSection::empty() const {
|
|
// We add the .got section to the result for dynamic MIPS target because
|
|
// its address and properties are mentioned in the .dynamic section.
|
|
return Config->Relocatable;
|
|
}
|
|
|
|
uint64_t MipsGotSection::getGp() const {
|
|
return ElfSym::MipsGp->getVA(0);
|
|
}
|
|
|
|
static uint64_t readUint(uint8_t *Buf) {
|
|
if (Config->Is64)
|
|
return read64(Buf, Config->Endianness);
|
|
return read32(Buf, Config->Endianness);
|
|
}
|
|
|
|
static void writeUint(uint8_t *Buf, uint64_t Val) {
|
|
if (Config->Is64)
|
|
write64(Buf, Val, Config->Endianness);
|
|
else
|
|
write32(Buf, Val, Config->Endianness);
|
|
}
|
|
|
|
void MipsGotSection::writeTo(uint8_t *Buf) {
|
|
// Set the MSB of the second GOT slot. This is not required by any
|
|
// MIPS ABI documentation, though.
|
|
//
|
|
// There is a comment in glibc saying that "The MSB of got[1] of a
|
|
// gnu object is set to identify gnu objects," and in GNU gold it
|
|
// says "the second entry will be used by some runtime loaders".
|
|
// But how this field is being used is unclear.
|
|
//
|
|
// We are not really willing to mimic other linkers behaviors
|
|
// without understanding why they do that, but because all files
|
|
// generated by GNU tools have this special GOT value, and because
|
|
// we've been doing this for years, it is probably a safe bet to
|
|
// keep doing this for now. We really need to revisit this to see
|
|
// if we had to do this.
|
|
writeUint(Buf + Config->Wordsize, (uint64_t)1 << (Config->Wordsize * 8 - 1));
|
|
Buf += HeaderEntriesNum * Config->Wordsize;
|
|
// Write 'page address' entries to the local part of the GOT.
|
|
for (std::pair<const OutputSection *, size_t> &L : PageIndexMap) {
|
|
size_t PageCount = getMipsPageCount(L.first->Size);
|
|
uint64_t FirstPageAddr = getMipsPageAddr(L.first->Addr);
|
|
for (size_t PI = 0; PI < PageCount; ++PI) {
|
|
uint8_t *Entry = Buf + (L.second + PI) * Config->Wordsize;
|
|
writeUint(Entry, FirstPageAddr + PI * 0x10000);
|
|
}
|
|
}
|
|
Buf += PageEntriesNum * Config->Wordsize;
|
|
auto AddEntry = [&](const GotEntry &SA) {
|
|
uint8_t *Entry = Buf;
|
|
Buf += Config->Wordsize;
|
|
const SymbolBody *Body = SA.first;
|
|
uint64_t VA = Body->getVA(SA.second);
|
|
writeUint(Entry, VA);
|
|
};
|
|
std::for_each(std::begin(LocalEntries), std::end(LocalEntries), AddEntry);
|
|
std::for_each(std::begin(LocalEntries32), std::end(LocalEntries32), AddEntry);
|
|
std::for_each(std::begin(GlobalEntries), std::end(GlobalEntries), AddEntry);
|
|
// Initialize TLS-related GOT entries. If the entry has a corresponding
|
|
// dynamic relocations, leave it initialized by zero. Write down adjusted
|
|
// TLS symbol's values otherwise. To calculate the adjustments use offsets
|
|
// for thread-local storage.
|
|
// https://www.linux-mips.org/wiki/NPTL
|
|
if (TlsIndexOff != -1U && !Config->Pic)
|
|
writeUint(Buf + TlsIndexOff, 1);
|
|
for (const SymbolBody *B : TlsEntries) {
|
|
if (!B || B->isPreemptible())
|
|
continue;
|
|
uint64_t VA = B->getVA();
|
|
if (B->GotIndex != -1U) {
|
|
uint8_t *Entry = Buf + B->GotIndex * Config->Wordsize;
|
|
writeUint(Entry, VA - 0x7000);
|
|
}
|
|
if (B->GlobalDynIndex != -1U) {
|
|
uint8_t *Entry = Buf + B->GlobalDynIndex * Config->Wordsize;
|
|
writeUint(Entry, 1);
|
|
Entry += Config->Wordsize;
|
|
writeUint(Entry, VA - 0x8000);
|
|
}
|
|
}
|
|
}
|
|
|
|
GotPltSection::GotPltSection()
|
|
: SyntheticSection(SHF_ALLOC | SHF_WRITE, SHT_PROGBITS,
|
|
Target->GotPltEntrySize, ".got.plt") {}
|
|
|
|
void GotPltSection::addEntry(SymbolBody &Sym) {
|
|
Sym.GotPltIndex = Target->GotPltHeaderEntriesNum + Entries.size();
|
|
Entries.push_back(&Sym);
|
|
}
|
|
|
|
size_t GotPltSection::getSize() const {
|
|
return (Target->GotPltHeaderEntriesNum + Entries.size()) *
|
|
Target->GotPltEntrySize;
|
|
}
|
|
|
|
void GotPltSection::writeTo(uint8_t *Buf) {
|
|
Target->writeGotPltHeader(Buf);
|
|
Buf += Target->GotPltHeaderEntriesNum * Target->GotPltEntrySize;
|
|
for (const SymbolBody *B : Entries) {
|
|
Target->writeGotPlt(Buf, *B);
|
|
Buf += Config->Wordsize;
|
|
}
|
|
}
|
|
|
|
// On ARM the IgotPltSection is part of the GotSection, on other Targets it is
|
|
// part of the .got.plt
|
|
IgotPltSection::IgotPltSection()
|
|
: SyntheticSection(SHF_ALLOC | SHF_WRITE, SHT_PROGBITS,
|
|
Target->GotPltEntrySize,
|
|
Config->EMachine == EM_ARM ? ".got" : ".got.plt") {}
|
|
|
|
void IgotPltSection::addEntry(SymbolBody &Sym) {
|
|
Sym.IsInIgot = true;
|
|
Sym.GotPltIndex = Entries.size();
|
|
Entries.push_back(&Sym);
|
|
}
|
|
|
|
size_t IgotPltSection::getSize() const {
|
|
return Entries.size() * Target->GotPltEntrySize;
|
|
}
|
|
|
|
void IgotPltSection::writeTo(uint8_t *Buf) {
|
|
for (const SymbolBody *B : Entries) {
|
|
Target->writeIgotPlt(Buf, *B);
|
|
Buf += Config->Wordsize;
|
|
}
|
|
}
|
|
|
|
StringTableSection::StringTableSection(StringRef Name, bool Dynamic)
|
|
: SyntheticSection(Dynamic ? (uint64_t)SHF_ALLOC : 0, SHT_STRTAB, 1, Name),
|
|
Dynamic(Dynamic) {
|
|
// ELF string tables start with a NUL byte.
|
|
addString("");
|
|
}
|
|
|
|
// Adds a string to the string table. If HashIt is true we hash and check for
|
|
// duplicates. It is optional because the name of global symbols are already
|
|
// uniqued and hashing them again has a big cost for a small value: uniquing
|
|
// them with some other string that happens to be the same.
|
|
unsigned StringTableSection::addString(StringRef S, bool HashIt) {
|
|
if (HashIt) {
|
|
auto R = StringMap.insert(std::make_pair(S, this->Size));
|
|
if (!R.second)
|
|
return R.first->second;
|
|
}
|
|
unsigned Ret = this->Size;
|
|
this->Size = this->Size + S.size() + 1;
|
|
Strings.push_back(S);
|
|
return Ret;
|
|
}
|
|
|
|
void StringTableSection::writeTo(uint8_t *Buf) {
|
|
for (StringRef S : Strings) {
|
|
memcpy(Buf, S.data(), S.size());
|
|
Buf += S.size() + 1;
|
|
}
|
|
}
|
|
|
|
// Returns the number of version definition entries. Because the first entry
|
|
// is for the version definition itself, it is the number of versioned symbols
|
|
// plus one. Note that we don't support multiple versions yet.
|
|
static unsigned getVerDefNum() { return Config->VersionDefinitions.size() + 1; }
|
|
|
|
template <class ELFT>
|
|
DynamicSection<ELFT>::DynamicSection()
|
|
: SyntheticSection(SHF_ALLOC | SHF_WRITE, SHT_DYNAMIC, Config->Wordsize,
|
|
".dynamic") {
|
|
this->Entsize = ELFT::Is64Bits ? 16 : 8;
|
|
|
|
// .dynamic section is not writable on MIPS and on Fuchsia OS
|
|
// which passes -z rodynamic.
|
|
// See "Special Section" in Chapter 4 in the following document:
|
|
// ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
|
|
if (Config->EMachine == EM_MIPS || Config->ZRodynamic)
|
|
this->Flags = SHF_ALLOC;
|
|
|
|
addEntries();
|
|
}
|
|
|
|
// There are some dynamic entries that don't depend on other sections.
|
|
// Such entries can be set early.
|
|
template <class ELFT> void DynamicSection<ELFT>::addEntries() {
|
|
// Add strings to .dynstr early so that .dynstr's size will be
|
|
// fixed early.
|
|
for (StringRef S : Config->AuxiliaryList)
|
|
add({DT_AUXILIARY, InX::DynStrTab->addString(S)});
|
|
if (!Config->Rpath.empty())
|
|
add({Config->EnableNewDtags ? DT_RUNPATH : DT_RPATH,
|
|
InX::DynStrTab->addString(Config->Rpath)});
|
|
for (SharedFile<ELFT> *F : Symtab<ELFT>::X->getSharedFiles())
|
|
if (F->isNeeded())
|
|
add({DT_NEEDED, InX::DynStrTab->addString(F->SoName)});
|
|
if (!Config->SoName.empty())
|
|
add({DT_SONAME, InX::DynStrTab->addString(Config->SoName)});
|
|
|
|
// Set DT_FLAGS and DT_FLAGS_1.
|
|
uint32_t DtFlags = 0;
|
|
uint32_t DtFlags1 = 0;
|
|
if (Config->Bsymbolic)
|
|
DtFlags |= DF_SYMBOLIC;
|
|
if (Config->ZNodelete)
|
|
DtFlags1 |= DF_1_NODELETE;
|
|
if (Config->ZNodlopen)
|
|
DtFlags1 |= DF_1_NOOPEN;
|
|
if (Config->ZNow) {
|
|
DtFlags |= DF_BIND_NOW;
|
|
DtFlags1 |= DF_1_NOW;
|
|
}
|
|
if (Config->ZOrigin) {
|
|
DtFlags |= DF_ORIGIN;
|
|
DtFlags1 |= DF_1_ORIGIN;
|
|
}
|
|
|
|
if (DtFlags)
|
|
add({DT_FLAGS, DtFlags});
|
|
if (DtFlags1)
|
|
add({DT_FLAGS_1, DtFlags1});
|
|
|
|
// DT_DEBUG is a pointer to debug informaion used by debuggers at runtime. We
|
|
// need it for each process, so we don't write it for DSOs. The loader writes
|
|
// the pointer into this entry.
|
|
//
|
|
// DT_DEBUG is the only .dynamic entry that needs to be written to. Some
|
|
// systems (currently only Fuchsia OS) provide other means to give the
|
|
// debugger this information. Such systems may choose make .dynamic read-only.
|
|
// If the target is such a system (used -z rodynamic) don't write DT_DEBUG.
|
|
if (!Config->Shared && !Config->Relocatable && !Config->ZRodynamic)
|
|
add({DT_DEBUG, (uint64_t)0});
|
|
}
|
|
|
|
// Add remaining entries to complete .dynamic contents.
|
|
template <class ELFT> void DynamicSection<ELFT>::finalizeContents() {
|
|
if (this->Size)
|
|
return; // Already finalized.
|
|
|
|
this->Link = InX::DynStrTab->getParent()->SectionIndex;
|
|
if (In<ELFT>::RelaDyn->getParent()->Size > 0) {
|
|
bool IsRela = Config->IsRela;
|
|
add({IsRela ? DT_RELA : DT_REL, In<ELFT>::RelaDyn});
|
|
add({IsRela ? DT_RELASZ : DT_RELSZ, In<ELFT>::RelaDyn->getParent()->Size});
|
|
add({IsRela ? DT_RELAENT : DT_RELENT,
|
|
uint64_t(IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel))});
|
|
|
|
// MIPS dynamic loader does not support RELCOUNT tag.
|
|
// The problem is in the tight relation between dynamic
|
|
// relocations and GOT. So do not emit this tag on MIPS.
|
|
if (Config->EMachine != EM_MIPS) {
|
|
size_t NumRelativeRels = In<ELFT>::RelaDyn->getRelativeRelocCount();
|
|
if (Config->ZCombreloc && NumRelativeRels)
|
|
add({IsRela ? DT_RELACOUNT : DT_RELCOUNT, NumRelativeRels});
|
|
}
|
|
}
|
|
if (In<ELFT>::RelaPlt->getParent()->Size > 0) {
|
|
add({DT_JMPREL, In<ELFT>::RelaPlt});
|
|
add({DT_PLTRELSZ, In<ELFT>::RelaPlt->getParent()->Size});
|
|
add({Config->EMachine == EM_MIPS ? DT_MIPS_PLTGOT : DT_PLTGOT,
|
|
InX::GotPlt});
|
|
add({DT_PLTREL, uint64_t(Config->IsRela ? DT_RELA : DT_REL)});
|
|
}
|
|
|
|
add({DT_SYMTAB, InX::DynSymTab});
|
|
add({DT_SYMENT, sizeof(Elf_Sym)});
|
|
add({DT_STRTAB, InX::DynStrTab});
|
|
add({DT_STRSZ, InX::DynStrTab->getSize()});
|
|
if (!Config->ZText)
|
|
add({DT_TEXTREL, (uint64_t)0});
|
|
if (InX::GnuHashTab)
|
|
add({DT_GNU_HASH, InX::GnuHashTab});
|
|
if (In<ELFT>::HashTab)
|
|
add({DT_HASH, In<ELFT>::HashTab});
|
|
|
|
if (Out::PreinitArray) {
|
|
add({DT_PREINIT_ARRAY, Out::PreinitArray});
|
|
add({DT_PREINIT_ARRAYSZ, Out::PreinitArray, Entry::SecSize});
|
|
}
|
|
if (Out::InitArray) {
|
|
add({DT_INIT_ARRAY, Out::InitArray});
|
|
add({DT_INIT_ARRAYSZ, Out::InitArray, Entry::SecSize});
|
|
}
|
|
if (Out::FiniArray) {
|
|
add({DT_FINI_ARRAY, Out::FiniArray});
|
|
add({DT_FINI_ARRAYSZ, Out::FiniArray, Entry::SecSize});
|
|
}
|
|
|
|
if (SymbolBody *B = Symtab<ELFT>::X->findInCurrentDSO(Config->Init))
|
|
add({DT_INIT, B});
|
|
if (SymbolBody *B = Symtab<ELFT>::X->findInCurrentDSO(Config->Fini))
|
|
add({DT_FINI, B});
|
|
|
|
bool HasVerNeed = In<ELFT>::VerNeed->getNeedNum() != 0;
|
|
if (HasVerNeed || In<ELFT>::VerDef)
|
|
add({DT_VERSYM, In<ELFT>::VerSym});
|
|
if (In<ELFT>::VerDef) {
|
|
add({DT_VERDEF, In<ELFT>::VerDef});
|
|
add({DT_VERDEFNUM, getVerDefNum()});
|
|
}
|
|
if (HasVerNeed) {
|
|
add({DT_VERNEED, In<ELFT>::VerNeed});
|
|
add({DT_VERNEEDNUM, In<ELFT>::VerNeed->getNeedNum()});
|
|
}
|
|
|
|
if (Config->EMachine == EM_MIPS) {
|
|
add({DT_MIPS_RLD_VERSION, 1});
|
|
add({DT_MIPS_FLAGS, RHF_NOTPOT});
|
|
add({DT_MIPS_BASE_ADDRESS, Config->ImageBase});
|
|
add({DT_MIPS_SYMTABNO, InX::DynSymTab->getNumSymbols()});
|
|
add({DT_MIPS_LOCAL_GOTNO, InX::MipsGot->getLocalEntriesNum()});
|
|
if (const SymbolBody *B = InX::MipsGot->getFirstGlobalEntry())
|
|
add({DT_MIPS_GOTSYM, B->DynsymIndex});
|
|
else
|
|
add({DT_MIPS_GOTSYM, InX::DynSymTab->getNumSymbols()});
|
|
add({DT_PLTGOT, InX::MipsGot});
|
|
if (InX::MipsRldMap)
|
|
add({DT_MIPS_RLD_MAP, InX::MipsRldMap});
|
|
}
|
|
|
|
getParent()->Link = this->Link;
|
|
|
|
// +1 for DT_NULL
|
|
this->Size = (Entries.size() + 1) * this->Entsize;
|
|
}
|
|
|
|
template <class ELFT> void DynamicSection<ELFT>::writeTo(uint8_t *Buf) {
|
|
auto *P = reinterpret_cast<Elf_Dyn *>(Buf);
|
|
|
|
for (const Entry &E : Entries) {
|
|
P->d_tag = E.Tag;
|
|
switch (E.Kind) {
|
|
case Entry::SecAddr:
|
|
P->d_un.d_ptr = E.OutSec->Addr;
|
|
break;
|
|
case Entry::InSecAddr:
|
|
P->d_un.d_ptr = E.InSec->getParent()->Addr + E.InSec->OutSecOff;
|
|
break;
|
|
case Entry::SecSize:
|
|
P->d_un.d_val = E.OutSec->Size;
|
|
break;
|
|
case Entry::SymAddr:
|
|
P->d_un.d_ptr = E.Sym->getVA();
|
|
break;
|
|
case Entry::PlainInt:
|
|
P->d_un.d_val = E.Val;
|
|
break;
|
|
}
|
|
++P;
|
|
}
|
|
}
|
|
|
|
uint64_t DynamicReloc::getOffset() const {
|
|
return InputSec->getOutputSection()->Addr + InputSec->getOffset(OffsetInSec);
|
|
}
|
|
|
|
int64_t DynamicReloc::getAddend() const {
|
|
if (UseSymVA)
|
|
return Sym->getVA(Addend);
|
|
return Addend;
|
|
}
|
|
|
|
uint32_t DynamicReloc::getSymIndex() const {
|
|
if (Sym && !UseSymVA)
|
|
return Sym->DynsymIndex;
|
|
return 0;
|
|
}
|
|
|
|
template <class ELFT>
|
|
RelocationSection<ELFT>::RelocationSection(StringRef Name, bool Sort)
|
|
: SyntheticSection(SHF_ALLOC, Config->IsRela ? SHT_RELA : SHT_REL,
|
|
Config->Wordsize, Name),
|
|
Sort(Sort) {
|
|
this->Entsize = Config->IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
|
|
}
|
|
|
|
template <class ELFT>
|
|
void RelocationSection<ELFT>::addReloc(const DynamicReloc &Reloc) {
|
|
if (Reloc.Type == Target->RelativeRel)
|
|
++NumRelativeRelocs;
|
|
Relocs.push_back(Reloc);
|
|
}
|
|
|
|
template <class ELFT, class RelTy>
|
|
static bool compRelocations(const RelTy &A, const RelTy &B) {
|
|
bool AIsRel = A.getType(Config->IsMips64EL) == Target->RelativeRel;
|
|
bool BIsRel = B.getType(Config->IsMips64EL) == Target->RelativeRel;
|
|
if (AIsRel != BIsRel)
|
|
return AIsRel;
|
|
|
|
return A.getSymbol(Config->IsMips64EL) < B.getSymbol(Config->IsMips64EL);
|
|
}
|
|
|
|
template <class ELFT> void RelocationSection<ELFT>::writeTo(uint8_t *Buf) {
|
|
uint8_t *BufBegin = Buf;
|
|
for (const DynamicReloc &Rel : Relocs) {
|
|
auto *P = reinterpret_cast<Elf_Rela *>(Buf);
|
|
Buf += Config->IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
|
|
|
|
if (Config->IsRela)
|
|
P->r_addend = Rel.getAddend();
|
|
P->r_offset = Rel.getOffset();
|
|
if (Config->EMachine == EM_MIPS && Rel.getInputSec() == InX::MipsGot)
|
|
// Dynamic relocation against MIPS GOT section make deal TLS entries
|
|
// allocated in the end of the GOT. We need to adjust the offset to take
|
|
// in account 'local' and 'global' GOT entries.
|
|
P->r_offset += InX::MipsGot->getTlsOffset();
|
|
P->setSymbolAndType(Rel.getSymIndex(), Rel.Type, Config->IsMips64EL);
|
|
}
|
|
|
|
if (Sort) {
|
|
if (Config->IsRela)
|
|
std::stable_sort((Elf_Rela *)BufBegin,
|
|
(Elf_Rela *)BufBegin + Relocs.size(),
|
|
compRelocations<ELFT, Elf_Rela>);
|
|
else
|
|
std::stable_sort((Elf_Rel *)BufBegin, (Elf_Rel *)BufBegin + Relocs.size(),
|
|
compRelocations<ELFT, Elf_Rel>);
|
|
}
|
|
}
|
|
|
|
template <class ELFT> unsigned RelocationSection<ELFT>::getRelocOffset() {
|
|
return this->Entsize * Relocs.size();
|
|
}
|
|
|
|
template <class ELFT> void RelocationSection<ELFT>::finalizeContents() {
|
|
this->Link = InX::DynSymTab ? InX::DynSymTab->getParent()->SectionIndex
|
|
: InX::SymTab->getParent()->SectionIndex;
|
|
|
|
// Set required output section properties.
|
|
getParent()->Link = this->Link;
|
|
}
|
|
|
|
SymbolTableBaseSection::SymbolTableBaseSection(StringTableSection &StrTabSec)
|
|
: SyntheticSection(StrTabSec.isDynamic() ? (uint64_t)SHF_ALLOC : 0,
|
|
StrTabSec.isDynamic() ? SHT_DYNSYM : SHT_SYMTAB,
|
|
Config->Wordsize,
|
|
StrTabSec.isDynamic() ? ".dynsym" : ".symtab"),
|
|
StrTabSec(StrTabSec) {}
|
|
|
|
// Orders symbols according to their positions in the GOT,
|
|
// in compliance with MIPS ABI rules.
|
|
// See "Global Offset Table" in Chapter 5 in the following document
|
|
// for detailed description:
|
|
// ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
|
|
static bool sortMipsSymbols(const SymbolTableEntry &L,
|
|
const SymbolTableEntry &R) {
|
|
// Sort entries related to non-local preemptible symbols by GOT indexes.
|
|
// All other entries go to the first part of GOT in arbitrary order.
|
|
bool LIsInLocalGot = !L.Symbol->IsInGlobalMipsGot;
|
|
bool RIsInLocalGot = !R.Symbol->IsInGlobalMipsGot;
|
|
if (LIsInLocalGot || RIsInLocalGot)
|
|
return !RIsInLocalGot;
|
|
return L.Symbol->GotIndex < R.Symbol->GotIndex;
|
|
}
|
|
|
|
// Finalize a symbol table. The ELF spec requires that all local
|
|
// symbols precede global symbols, so we sort symbol entries in this
|
|
// function. (For .dynsym, we don't do that because symbols for
|
|
// dynamic linking are inherently all globals.)
|
|
void SymbolTableBaseSection::finalizeContents() {
|
|
getParent()->Link = StrTabSec.getParent()->SectionIndex;
|
|
|
|
// If it is a .dynsym, there should be no local symbols, but we need
|
|
// to do a few things for the dynamic linker.
|
|
if (this->Type == SHT_DYNSYM) {
|
|
// Section's Info field has the index of the first non-local symbol.
|
|
// Because the first symbol entry is a null entry, 1 is the first.
|
|
getParent()->Info = 1;
|
|
|
|
if (InX::GnuHashTab) {
|
|
// NB: It also sorts Symbols to meet the GNU hash table requirements.
|
|
InX::GnuHashTab->addSymbols(Symbols);
|
|
} else if (Config->EMachine == EM_MIPS) {
|
|
std::stable_sort(Symbols.begin(), Symbols.end(), sortMipsSymbols);
|
|
}
|
|
|
|
size_t I = 0;
|
|
for (const SymbolTableEntry &S : Symbols)
|
|
S.Symbol->DynsymIndex = ++I;
|
|
return;
|
|
}
|
|
}
|
|
|
|
void SymbolTableBaseSection::postThunkContents() {
|
|
if (this->Type == SHT_DYNSYM)
|
|
return;
|
|
// move all local symbols before global symbols.
|
|
auto It = std::stable_partition(
|
|
Symbols.begin(), Symbols.end(), [](const SymbolTableEntry &S) {
|
|
return S.Symbol->isLocal() ||
|
|
S.Symbol->symbol()->computeBinding() == STB_LOCAL;
|
|
});
|
|
size_t NumLocals = It - Symbols.begin();
|
|
getParent()->Info = NumLocals + 1;
|
|
}
|
|
|
|
void SymbolTableBaseSection::addSymbol(SymbolBody *B) {
|
|
// Adding a local symbol to a .dynsym is a bug.
|
|
assert(this->Type != SHT_DYNSYM || !B->isLocal());
|
|
|
|
bool HashIt = B->isLocal();
|
|
Symbols.push_back({B, StrTabSec.addString(B->getName(), HashIt)});
|
|
}
|
|
|
|
size_t SymbolTableBaseSection::getSymbolIndex(SymbolBody *Body) {
|
|
auto I = llvm::find_if(Symbols, [&](const SymbolTableEntry &E) {
|
|
if (E.Symbol == Body)
|
|
return true;
|
|
// This is used for -r, so we have to handle multiple section
|
|
// symbols being combined.
|
|
if (Body->Type == STT_SECTION && E.Symbol->Type == STT_SECTION)
|
|
return Body->getOutputSection() == E.Symbol->getOutputSection();
|
|
return false;
|
|
});
|
|
if (I == Symbols.end())
|
|
return 0;
|
|
return I - Symbols.begin() + 1;
|
|
}
|
|
|
|
template <class ELFT>
|
|
SymbolTableSection<ELFT>::SymbolTableSection(StringTableSection &StrTabSec)
|
|
: SymbolTableBaseSection(StrTabSec) {
|
|
this->Entsize = sizeof(Elf_Sym);
|
|
}
|
|
|
|
// Write the internal symbol table contents to the output symbol table.
|
|
template <class ELFT> void SymbolTableSection<ELFT>::writeTo(uint8_t *Buf) {
|
|
// The first entry is a null entry as per the ELF spec.
|
|
Buf += sizeof(Elf_Sym);
|
|
|
|
auto *ESym = reinterpret_cast<Elf_Sym *>(Buf);
|
|
|
|
for (SymbolTableEntry &Ent : Symbols) {
|
|
SymbolBody *Body = Ent.Symbol;
|
|
|
|
// Set st_info and st_other.
|
|
if (Body->isLocal()) {
|
|
ESym->setBindingAndType(STB_LOCAL, Body->Type);
|
|
} else {
|
|
ESym->setBindingAndType(Body->symbol()->computeBinding(), Body->Type);
|
|
ESym->setVisibility(Body->symbol()->Visibility);
|
|
}
|
|
|
|
ESym->st_name = Ent.StrTabOffset;
|
|
ESym->st_size = Body->getSize<ELFT>();
|
|
|
|
// Set a section index.
|
|
if (const OutputSection *OutSec = Body->getOutputSection())
|
|
ESym->st_shndx = OutSec->SectionIndex;
|
|
else if (isa<DefinedRegular>(Body))
|
|
ESym->st_shndx = SHN_ABS;
|
|
else if (isa<DefinedCommon>(Body))
|
|
ESym->st_shndx = SHN_COMMON;
|
|
|
|
// st_value is usually an address of a symbol, but that has a
|
|
// special meaining for uninstantiated common symbols (this can
|
|
// occur if -r is given).
|
|
if (!Config->DefineCommon && isa<DefinedCommon>(Body))
|
|
ESym->st_value = cast<DefinedCommon>(Body)->Alignment;
|
|
else
|
|
ESym->st_value = Body->getVA();
|
|
|
|
++ESym;
|
|
}
|
|
|
|
// On MIPS we need to mark symbol which has a PLT entry and requires
|
|
// pointer equality by STO_MIPS_PLT flag. That is necessary to help
|
|
// dynamic linker distinguish such symbols and MIPS lazy-binding stubs.
|
|
// https://sourceware.org/ml/binutils/2008-07/txt00000.txt
|
|
if (Config->EMachine == EM_MIPS) {
|
|
auto *ESym = reinterpret_cast<Elf_Sym *>(Buf);
|
|
|
|
for (SymbolTableEntry &Ent : Symbols) {
|
|
SymbolBody *Body = Ent.Symbol;
|
|
if (Body->isInPlt() && Body->NeedsPltAddr)
|
|
ESym->st_other |= STO_MIPS_PLT;
|
|
|
|
if (Config->Relocatable)
|
|
if (auto *D = dyn_cast<DefinedRegular>(Body))
|
|
if (D->isMipsPIC<ELFT>())
|
|
ESym->st_other |= STO_MIPS_PIC;
|
|
++ESym;
|
|
}
|
|
}
|
|
}
|
|
|
|
// .hash and .gnu.hash sections contain on-disk hash tables that map
|
|
// symbol names to their dynamic symbol table indices. Their purpose
|
|
// is to help the dynamic linker resolve symbols quickly. If ELF files
|
|
// don't have them, the dynamic linker has to do linear search on all
|
|
// dynamic symbols, which makes programs slower. Therefore, a .hash
|
|
// section is added to a DSO by default. A .gnu.hash is added if you
|
|
// give the -hash-style=gnu or -hash-style=both option.
|
|
//
|
|
// The Unix semantics of resolving dynamic symbols is somewhat expensive.
|
|
// Each ELF file has a list of DSOs that the ELF file depends on and a
|
|
// list of dynamic symbols that need to be resolved from any of the
|
|
// DSOs. That means resolving all dynamic symbols takes O(m)*O(n)
|
|
// where m is the number of DSOs and n is the number of dynamic
|
|
// symbols. For modern large programs, both m and n are large. So
|
|
// making each step faster by using hash tables substiantially
|
|
// improves time to load programs.
|
|
//
|
|
// (Note that this is not the only way to design the shared library.
|
|
// For instance, the Windows DLL takes a different approach. On
|
|
// Windows, each dynamic symbol has a name of DLL from which the symbol
|
|
// has to be resolved. That makes the cost of symbol resolution O(n).
|
|
// This disables some hacky techniques you can use on Unix such as
|
|
// LD_PRELOAD, but this is arguably better semantics than the Unix ones.)
|
|
//
|
|
// Due to historical reasons, we have two different hash tables, .hash
|
|
// and .gnu.hash. They are for the same purpose, and .gnu.hash is a new
|
|
// and better version of .hash. .hash is just an on-disk hash table, but
|
|
// .gnu.hash has a bloom filter in addition to a hash table to skip
|
|
// DSOs very quickly. If you are sure that your dynamic linker knows
|
|
// about .gnu.hash, you want to specify -hash-style=gnu. Otherwise, a
|
|
// safe bet is to specify -hash-style=both for backward compatibilty.
|
|
GnuHashTableSection::GnuHashTableSection()
|
|
: SyntheticSection(SHF_ALLOC, SHT_GNU_HASH, Config->Wordsize, ".gnu.hash") {
|
|
}
|
|
|
|
void GnuHashTableSection::finalizeContents() {
|
|
getParent()->Link = InX::DynSymTab->getParent()->SectionIndex;
|
|
|
|
// Computes bloom filter size in word size. We want to allocate 8
|
|
// bits for each symbol. It must be a power of two.
|
|
if (Symbols.empty())
|
|
MaskWords = 1;
|
|
else
|
|
MaskWords = NextPowerOf2((Symbols.size() - 1) / Config->Wordsize);
|
|
|
|
Size = 16; // Header
|
|
Size += Config->Wordsize * MaskWords; // Bloom filter
|
|
Size += NBuckets * 4; // Hash buckets
|
|
Size += Symbols.size() * 4; // Hash values
|
|
}
|
|
|
|
void GnuHashTableSection::writeTo(uint8_t *Buf) {
|
|
// Write a header.
|
|
write32(Buf, NBuckets, Config->Endianness);
|
|
write32(Buf + 4, InX::DynSymTab->getNumSymbols() - Symbols.size(),
|
|
Config->Endianness);
|
|
write32(Buf + 8, MaskWords, Config->Endianness);
|
|
write32(Buf + 12, getShift2(), Config->Endianness);
|
|
Buf += 16;
|
|
|
|
// Write a bloom filter and a hash table.
|
|
writeBloomFilter(Buf);
|
|
Buf += Config->Wordsize * MaskWords;
|
|
writeHashTable(Buf);
|
|
}
|
|
|
|
// This function writes a 2-bit bloom filter. This bloom filter alone
|
|
// usually filters out 80% or more of all symbol lookups [1].
|
|
// The dynamic linker uses the hash table only when a symbol is not
|
|
// filtered out by a bloom filter.
|
|
//
|
|
// [1] Ulrich Drepper (2011), "How To Write Shared Libraries" (Ver. 4.1.2),
|
|
// p.9, https://www.akkadia.org/drepper/dsohowto.pdf
|
|
void GnuHashTableSection::writeBloomFilter(uint8_t *Buf) {
|
|
const unsigned C = Config->Wordsize * 8;
|
|
for (const Entry &Sym : Symbols) {
|
|
size_t I = (Sym.Hash / C) & (MaskWords - 1);
|
|
uint64_t Val = readUint(Buf + I * Config->Wordsize);
|
|
Val |= uint64_t(1) << (Sym.Hash % C);
|
|
Val |= uint64_t(1) << ((Sym.Hash >> getShift2()) % C);
|
|
writeUint(Buf + I * Config->Wordsize, Val);
|
|
}
|
|
}
|
|
|
|
void GnuHashTableSection::writeHashTable(uint8_t *Buf) {
|
|
// Group symbols by hash value.
|
|
std::vector<std::vector<Entry>> Syms(NBuckets);
|
|
for (const Entry &Ent : Symbols)
|
|
Syms[Ent.Hash % NBuckets].push_back(Ent);
|
|
|
|
// Write hash buckets. Hash buckets contain indices in the following
|
|
// hash value table.
|
|
uint32_t *Buckets = reinterpret_cast<uint32_t *>(Buf);
|
|
for (size_t I = 0; I < NBuckets; ++I)
|
|
if (!Syms[I].empty())
|
|
write32(Buckets + I, Syms[I][0].Body->DynsymIndex, Config->Endianness);
|
|
|
|
// Write a hash value table. It represents a sequence of chains that
|
|
// share the same hash modulo value. The last element of each chain
|
|
// is terminated by LSB 1.
|
|
uint32_t *Values = Buckets + NBuckets;
|
|
size_t I = 0;
|
|
for (std::vector<Entry> &Vec : Syms) {
|
|
if (Vec.empty())
|
|
continue;
|
|
for (const Entry &Ent : makeArrayRef(Vec).drop_back())
|
|
write32(Values + I++, Ent.Hash & ~1, Config->Endianness);
|
|
write32(Values + I++, Vec.back().Hash | 1, Config->Endianness);
|
|
}
|
|
}
|
|
|
|
static uint32_t hashGnu(StringRef Name) {
|
|
uint32_t H = 5381;
|
|
for (uint8_t C : Name)
|
|
H = (H << 5) + H + C;
|
|
return H;
|
|
}
|
|
|
|
// Returns a number of hash buckets to accomodate given number of elements.
|
|
// We want to choose a moderate number that is not too small (which
|
|
// causes too many hash collisions) and not too large (which wastes
|
|
// disk space.)
|
|
//
|
|
// We return a prime number because it (is believed to) achieve good
|
|
// hash distribution.
|
|
static size_t getBucketSize(size_t NumSymbols) {
|
|
// List of largest prime numbers that are not greater than 2^n + 1.
|
|
for (size_t N : {131071, 65521, 32749, 16381, 8191, 4093, 2039, 1021, 509,
|
|
251, 127, 61, 31, 13, 7, 3, 1})
|
|
if (N <= NumSymbols)
|
|
return N;
|
|
return 0;
|
|
}
|
|
|
|
// Add symbols to this symbol hash table. Note that this function
|
|
// destructively sort a given vector -- which is needed because
|
|
// GNU-style hash table places some sorting requirements.
|
|
void GnuHashTableSection::addSymbols(std::vector<SymbolTableEntry> &V) {
|
|
// We cannot use 'auto' for Mid because GCC 6.1 cannot deduce
|
|
// its type correctly.
|
|
std::vector<SymbolTableEntry>::iterator Mid =
|
|
std::stable_partition(V.begin(), V.end(), [](const SymbolTableEntry &S) {
|
|
return S.Symbol->isUndefined();
|
|
});
|
|
if (Mid == V.end())
|
|
return;
|
|
|
|
for (SymbolTableEntry &Ent : llvm::make_range(Mid, V.end())) {
|
|
SymbolBody *B = Ent.Symbol;
|
|
Symbols.push_back({B, Ent.StrTabOffset, hashGnu(B->getName())});
|
|
}
|
|
|
|
NBuckets = getBucketSize(Symbols.size());
|
|
std::stable_sort(Symbols.begin(), Symbols.end(),
|
|
[&](const Entry &L, const Entry &R) {
|
|
return L.Hash % NBuckets < R.Hash % NBuckets;
|
|
});
|
|
|
|
V.erase(Mid, V.end());
|
|
for (const Entry &Ent : Symbols)
|
|
V.push_back({Ent.Body, Ent.StrTabOffset});
|
|
}
|
|
|
|
template <class ELFT>
|
|
HashTableSection<ELFT>::HashTableSection()
|
|
: SyntheticSection(SHF_ALLOC, SHT_HASH, 4, ".hash") {
|
|
this->Entsize = 4;
|
|
}
|
|
|
|
template <class ELFT> void HashTableSection<ELFT>::finalizeContents() {
|
|
getParent()->Link = InX::DynSymTab->getParent()->SectionIndex;
|
|
|
|
unsigned NumEntries = 2; // nbucket and nchain.
|
|
NumEntries += InX::DynSymTab->getNumSymbols(); // The chain entries.
|
|
|
|
// Create as many buckets as there are symbols.
|
|
// FIXME: This is simplistic. We can try to optimize it, but implementing
|
|
// support for SHT_GNU_HASH is probably even more profitable.
|
|
NumEntries += InX::DynSymTab->getNumSymbols();
|
|
this->Size = NumEntries * 4;
|
|
}
|
|
|
|
template <class ELFT> void HashTableSection<ELFT>::writeTo(uint8_t *Buf) {
|
|
// A 32-bit integer type in the target endianness.
|
|
typedef typename ELFT::Word Elf_Word;
|
|
|
|
unsigned NumSymbols = InX::DynSymTab->getNumSymbols();
|
|
|
|
auto *P = reinterpret_cast<Elf_Word *>(Buf);
|
|
*P++ = NumSymbols; // nbucket
|
|
*P++ = NumSymbols; // nchain
|
|
|
|
Elf_Word *Buckets = P;
|
|
Elf_Word *Chains = P + NumSymbols;
|
|
|
|
for (const SymbolTableEntry &S : InX::DynSymTab->getSymbols()) {
|
|
SymbolBody *Body = S.Symbol;
|
|
StringRef Name = Body->getName();
|
|
unsigned I = Body->DynsymIndex;
|
|
uint32_t Hash = hashSysV(Name) % NumSymbols;
|
|
Chains[I] = Buckets[Hash];
|
|
Buckets[Hash] = I;
|
|
}
|
|
}
|
|
|
|
PltSection::PltSection(size_t S)
|
|
: SyntheticSection(SHF_ALLOC | SHF_EXECINSTR, SHT_PROGBITS, 16, ".plt"),
|
|
HeaderSize(S) {}
|
|
|
|
void PltSection::writeTo(uint8_t *Buf) {
|
|
// At beginning of PLT but not the IPLT, we have code to call the dynamic
|
|
// linker to resolve dynsyms at runtime. Write such code.
|
|
if (HeaderSize != 0)
|
|
Target->writePltHeader(Buf);
|
|
size_t Off = HeaderSize;
|
|
// The IPlt is immediately after the Plt, account for this in RelOff
|
|
unsigned PltOff = getPltRelocOff();
|
|
|
|
for (auto &I : Entries) {
|
|
const SymbolBody *B = I.first;
|
|
unsigned RelOff = I.second + PltOff;
|
|
uint64_t Got = B->getGotPltVA();
|
|
uint64_t Plt = this->getVA() + Off;
|
|
Target->writePlt(Buf + Off, Got, Plt, B->PltIndex, RelOff);
|
|
Off += Target->PltEntrySize;
|
|
}
|
|
}
|
|
|
|
template <class ELFT> void PltSection::addEntry(SymbolBody &Sym) {
|
|
Sym.PltIndex = Entries.size();
|
|
RelocationSection<ELFT> *PltRelocSection = In<ELFT>::RelaPlt;
|
|
if (HeaderSize == 0) {
|
|
PltRelocSection = In<ELFT>::RelaIplt;
|
|
Sym.IsInIplt = true;
|
|
}
|
|
unsigned RelOff = PltRelocSection->getRelocOffset();
|
|
Entries.push_back(std::make_pair(&Sym, RelOff));
|
|
}
|
|
|
|
size_t PltSection::getSize() const {
|
|
return HeaderSize + Entries.size() * Target->PltEntrySize;
|
|
}
|
|
|
|
// Some architectures such as additional symbols in the PLT section. For
|
|
// example ARM uses mapping symbols to aid disassembly
|
|
void PltSection::addSymbols() {
|
|
// The PLT may have symbols defined for the Header, the IPLT has no header
|
|
if (HeaderSize != 0)
|
|
Target->addPltHeaderSymbols(this);
|
|
size_t Off = HeaderSize;
|
|
for (size_t I = 0; I < Entries.size(); ++I) {
|
|
Target->addPltSymbols(this, Off);
|
|
Off += Target->PltEntrySize;
|
|
}
|
|
}
|
|
|
|
unsigned PltSection::getPltRelocOff() const {
|
|
return (HeaderSize == 0) ? InX::Plt->getSize() : 0;
|
|
}
|
|
|
|
GdbIndexSection::GdbIndexSection()
|
|
: SyntheticSection(0, SHT_PROGBITS, 1, ".gdb_index"),
|
|
StringPool(llvm::StringTableBuilder::ELF) {}
|
|
|
|
// Iterative hash function for symbol's name is described in .gdb_index format
|
|
// specification. Note that we use one for version 5 to 7 here, it is different
|
|
// for version 4.
|
|
static uint32_t hash(StringRef Str) {
|
|
uint32_t R = 0;
|
|
for (uint8_t C : Str)
|
|
R = R * 67 + tolower(C) - 113;
|
|
return R;
|
|
}
|
|
|
|
static std::vector<CompilationUnitEntry> readCuList(DWARFContext &Dwarf,
|
|
InputSection *Sec) {
|
|
std::vector<CompilationUnitEntry> Ret;
|
|
for (std::unique_ptr<DWARFCompileUnit> &CU : Dwarf.compile_units())
|
|
Ret.push_back({Sec->OutSecOff + CU->getOffset(), CU->getLength() + 4});
|
|
return Ret;
|
|
}
|
|
|
|
static std::vector<AddressEntry> readAddressArea(DWARFContext &Dwarf,
|
|
InputSection *Sec) {
|
|
std::vector<AddressEntry> Ret;
|
|
|
|
uint32_t CurrentCu = 0;
|
|
for (std::unique_ptr<DWARFCompileUnit> &CU : Dwarf.compile_units()) {
|
|
DWARFAddressRangesVector Ranges;
|
|
CU->collectAddressRanges(Ranges);
|
|
|
|
ArrayRef<InputSectionBase *> Sections = Sec->File->getSections();
|
|
for (DWARFAddressRange &R : Ranges) {
|
|
InputSectionBase *S = Sections[R.SectionIndex];
|
|
if (!S || S == &InputSection::Discarded || !S->Live)
|
|
continue;
|
|
// Range list with zero size has no effect.
|
|
if (R.LowPC == R.HighPC)
|
|
continue;
|
|
Ret.push_back({cast<InputSection>(S), R.LowPC, R.HighPC, CurrentCu});
|
|
}
|
|
++CurrentCu;
|
|
}
|
|
return Ret;
|
|
}
|
|
|
|
static std::vector<NameTypeEntry> readPubNamesAndTypes(DWARFContext &Dwarf,
|
|
bool IsLE) {
|
|
StringRef Data[] = {Dwarf.getGnuPubNamesSection(),
|
|
Dwarf.getGnuPubTypesSection()};
|
|
|
|
std::vector<NameTypeEntry> Ret;
|
|
for (StringRef D : Data) {
|
|
DWARFDebugPubTable PubTable(D, IsLE, true);
|
|
for (const DWARFDebugPubTable::Set &Set : PubTable.getData())
|
|
for (const DWARFDebugPubTable::Entry &Ent : Set.Entries)
|
|
Ret.push_back({Ent.Name, Ent.Descriptor.toBits()});
|
|
}
|
|
return Ret;
|
|
}
|
|
|
|
static std::vector<InputSection *> getDebugInfoSections() {
|
|
std::vector<InputSection *> Ret;
|
|
for (InputSectionBase *S : InputSections)
|
|
if (InputSection *IS = dyn_cast<InputSection>(S))
|
|
if (IS->getParent() && IS->Name == ".debug_info")
|
|
Ret.push_back(IS);
|
|
return Ret;
|
|
}
|
|
|
|
void GdbIndexSection::buildIndex() {
|
|
std::vector<InputSection *> V = getDebugInfoSections();
|
|
if (V.empty())
|
|
return;
|
|
|
|
for (InputSection *Sec : V)
|
|
Chunks.push_back(readDwarf(Sec));
|
|
|
|
uint32_t CuId = 0;
|
|
for (GdbIndexChunk &D : Chunks) {
|
|
for (AddressEntry &E : D.AddressArea)
|
|
E.CuIndex += CuId;
|
|
|
|
// Populate constant pool area.
|
|
for (NameTypeEntry &NameType : D.NamesAndTypes) {
|
|
uint32_t Hash = hash(NameType.Name);
|
|
size_t Offset = StringPool.add(NameType.Name);
|
|
|
|
bool IsNew;
|
|
GdbSymbol *Sym;
|
|
std::tie(IsNew, Sym) = SymbolTable.add(Hash, Offset);
|
|
if (IsNew) {
|
|
Sym->CuVectorIndex = CuVectors.size();
|
|
CuVectors.resize(CuVectors.size() + 1);
|
|
}
|
|
|
|
CuVectors[Sym->CuVectorIndex].insert(CuId | (NameType.Type << 24));
|
|
}
|
|
|
|
CuId += D.CompilationUnits.size();
|
|
}
|
|
}
|
|
|
|
GdbIndexChunk GdbIndexSection::readDwarf(InputSection *Sec) {
|
|
Expected<std::unique_ptr<object::ObjectFile>> Obj =
|
|
object::ObjectFile::createObjectFile(Sec->File->MB);
|
|
if (!Obj) {
|
|
error(toString(Sec->File) + ": error creating DWARF context");
|
|
return {};
|
|
}
|
|
|
|
DWARFContextInMemory Dwarf(*Obj.get());
|
|
|
|
GdbIndexChunk Ret;
|
|
Ret.CompilationUnits = readCuList(Dwarf, Sec);
|
|
Ret.AddressArea = readAddressArea(Dwarf, Sec);
|
|
Ret.NamesAndTypes = readPubNamesAndTypes(Dwarf, Config->IsLE);
|
|
return Ret;
|
|
}
|
|
|
|
static size_t getCuSize(std::vector<GdbIndexChunk> &C) {
|
|
size_t Ret = 0;
|
|
for (GdbIndexChunk &D : C)
|
|
Ret += D.CompilationUnits.size();
|
|
return Ret;
|
|
}
|
|
|
|
static size_t getAddressAreaSize(std::vector<GdbIndexChunk> &C) {
|
|
size_t Ret = 0;
|
|
for (GdbIndexChunk &D : C)
|
|
Ret += D.AddressArea.size();
|
|
return Ret;
|
|
}
|
|
|
|
void GdbIndexSection::finalizeContents() {
|
|
if (Finalized)
|
|
return;
|
|
Finalized = true;
|
|
|
|
buildIndex();
|
|
|
|
SymbolTable.finalizeContents();
|
|
|
|
// GdbIndex header consist from version fields
|
|
// and 5 more fields with different kinds of offsets.
|
|
CuTypesOffset = CuListOffset + getCuSize(Chunks) * CompilationUnitSize;
|
|
SymTabOffset = CuTypesOffset + getAddressAreaSize(Chunks) * AddressEntrySize;
|
|
|
|
ConstantPoolOffset =
|
|
SymTabOffset + SymbolTable.getCapacity() * SymTabEntrySize;
|
|
|
|
for (std::set<uint32_t> &CuVec : CuVectors) {
|
|
CuVectorsOffset.push_back(CuVectorsSize);
|
|
CuVectorsSize += OffsetTypeSize * (CuVec.size() + 1);
|
|
}
|
|
StringPoolOffset = ConstantPoolOffset + CuVectorsSize;
|
|
|
|
StringPool.finalizeInOrder();
|
|
}
|
|
|
|
size_t GdbIndexSection::getSize() const {
|
|
const_cast<GdbIndexSection *>(this)->finalizeContents();
|
|
return StringPoolOffset + StringPool.getSize();
|
|
}
|
|
|
|
void GdbIndexSection::writeTo(uint8_t *Buf) {
|
|
write32le(Buf, 7); // Write version.
|
|
write32le(Buf + 4, CuListOffset); // CU list offset.
|
|
write32le(Buf + 8, CuTypesOffset); // Types CU list offset.
|
|
write32le(Buf + 12, CuTypesOffset); // Address area offset.
|
|
write32le(Buf + 16, SymTabOffset); // Symbol table offset.
|
|
write32le(Buf + 20, ConstantPoolOffset); // Constant pool offset.
|
|
Buf += 24;
|
|
|
|
// Write the CU list.
|
|
for (GdbIndexChunk &D : Chunks) {
|
|
for (CompilationUnitEntry &Cu : D.CompilationUnits) {
|
|
write64le(Buf, Cu.CuOffset);
|
|
write64le(Buf + 8, Cu.CuLength);
|
|
Buf += 16;
|
|
}
|
|
}
|
|
|
|
// Write the address area.
|
|
for (GdbIndexChunk &D : Chunks) {
|
|
for (AddressEntry &E : D.AddressArea) {
|
|
uint64_t BaseAddr =
|
|
E.Section->getParent()->Addr + E.Section->getOffset(0);
|
|
write64le(Buf, BaseAddr + E.LowAddress);
|
|
write64le(Buf + 8, BaseAddr + E.HighAddress);
|
|
write32le(Buf + 16, E.CuIndex);
|
|
Buf += 20;
|
|
}
|
|
}
|
|
|
|
// Write the symbol table.
|
|
for (size_t I = 0; I < SymbolTable.getCapacity(); ++I) {
|
|
GdbSymbol *Sym = SymbolTable.getSymbol(I);
|
|
if (Sym) {
|
|
size_t NameOffset =
|
|
Sym->NameOffset + StringPoolOffset - ConstantPoolOffset;
|
|
size_t CuVectorOffset = CuVectorsOffset[Sym->CuVectorIndex];
|
|
write32le(Buf, NameOffset);
|
|
write32le(Buf + 4, CuVectorOffset);
|
|
}
|
|
Buf += 8;
|
|
}
|
|
|
|
// Write the CU vectors into the constant pool.
|
|
for (std::set<uint32_t> &CuVec : CuVectors) {
|
|
write32le(Buf, CuVec.size());
|
|
Buf += 4;
|
|
for (uint32_t Val : CuVec) {
|
|
write32le(Buf, Val);
|
|
Buf += 4;
|
|
}
|
|
}
|
|
|
|
StringPool.write(Buf);
|
|
}
|
|
|
|
bool GdbIndexSection::empty() const {
|
|
return !Out::DebugInfo;
|
|
}
|
|
|
|
template <class ELFT>
|
|
EhFrameHeader<ELFT>::EhFrameHeader()
|
|
: SyntheticSection(SHF_ALLOC, SHT_PROGBITS, 1, ".eh_frame_hdr") {}
|
|
|
|
// .eh_frame_hdr contains a binary search table of pointers to FDEs.
|
|
// Each entry of the search table consists of two values,
|
|
// the starting PC from where FDEs covers, and the FDE's address.
|
|
// It is sorted by PC.
|
|
template <class ELFT> void EhFrameHeader<ELFT>::writeTo(uint8_t *Buf) {
|
|
const endianness E = ELFT::TargetEndianness;
|
|
|
|
// Sort the FDE list by their PC and uniqueify. Usually there is only
|
|
// one FDE for a PC (i.e. function), but if ICF merges two functions
|
|
// into one, there can be more than one FDEs pointing to the address.
|
|
auto Less = [](const FdeData &A, const FdeData &B) { return A.Pc < B.Pc; };
|
|
std::stable_sort(Fdes.begin(), Fdes.end(), Less);
|
|
auto Eq = [](const FdeData &A, const FdeData &B) { return A.Pc == B.Pc; };
|
|
Fdes.erase(std::unique(Fdes.begin(), Fdes.end(), Eq), Fdes.end());
|
|
|
|
Buf[0] = 1;
|
|
Buf[1] = DW_EH_PE_pcrel | DW_EH_PE_sdata4;
|
|
Buf[2] = DW_EH_PE_udata4;
|
|
Buf[3] = DW_EH_PE_datarel | DW_EH_PE_sdata4;
|
|
write32<E>(Buf + 4, In<ELFT>::EhFrame->getParent()->Addr - this->getVA() - 4);
|
|
write32<E>(Buf + 8, Fdes.size());
|
|
Buf += 12;
|
|
|
|
uint64_t VA = this->getVA();
|
|
for (FdeData &Fde : Fdes) {
|
|
write32<E>(Buf, Fde.Pc - VA);
|
|
write32<E>(Buf + 4, Fde.FdeVA - VA);
|
|
Buf += 8;
|
|
}
|
|
}
|
|
|
|
template <class ELFT> size_t EhFrameHeader<ELFT>::getSize() const {
|
|
// .eh_frame_hdr has a 12 bytes header followed by an array of FDEs.
|
|
return 12 + In<ELFT>::EhFrame->NumFdes * 8;
|
|
}
|
|
|
|
template <class ELFT>
|
|
void EhFrameHeader<ELFT>::addFde(uint32_t Pc, uint32_t FdeVA) {
|
|
Fdes.push_back({Pc, FdeVA});
|
|
}
|
|
|
|
template <class ELFT> bool EhFrameHeader<ELFT>::empty() const {
|
|
return In<ELFT>::EhFrame->empty();
|
|
}
|
|
|
|
template <class ELFT>
|
|
VersionDefinitionSection<ELFT>::VersionDefinitionSection()
|
|
: SyntheticSection(SHF_ALLOC, SHT_GNU_verdef, sizeof(uint32_t),
|
|
".gnu.version_d") {}
|
|
|
|
static StringRef getFileDefName() {
|
|
if (!Config->SoName.empty())
|
|
return Config->SoName;
|
|
return Config->OutputFile;
|
|
}
|
|
|
|
template <class ELFT> void VersionDefinitionSection<ELFT>::finalizeContents() {
|
|
FileDefNameOff = InX::DynStrTab->addString(getFileDefName());
|
|
for (VersionDefinition &V : Config->VersionDefinitions)
|
|
V.NameOff = InX::DynStrTab->addString(V.Name);
|
|
|
|
getParent()->Link = InX::DynStrTab->getParent()->SectionIndex;
|
|
|
|
// sh_info should be set to the number of definitions. This fact is missed in
|
|
// documentation, but confirmed by binutils community:
|
|
// https://sourceware.org/ml/binutils/2014-11/msg00355.html
|
|
getParent()->Info = getVerDefNum();
|
|
}
|
|
|
|
template <class ELFT>
|
|
void VersionDefinitionSection<ELFT>::writeOne(uint8_t *Buf, uint32_t Index,
|
|
StringRef Name, size_t NameOff) {
|
|
auto *Verdef = reinterpret_cast<Elf_Verdef *>(Buf);
|
|
Verdef->vd_version = 1;
|
|
Verdef->vd_cnt = 1;
|
|
Verdef->vd_aux = sizeof(Elf_Verdef);
|
|
Verdef->vd_next = sizeof(Elf_Verdef) + sizeof(Elf_Verdaux);
|
|
Verdef->vd_flags = (Index == 1 ? VER_FLG_BASE : 0);
|
|
Verdef->vd_ndx = Index;
|
|
Verdef->vd_hash = hashSysV(Name);
|
|
|
|
auto *Verdaux = reinterpret_cast<Elf_Verdaux *>(Buf + sizeof(Elf_Verdef));
|
|
Verdaux->vda_name = NameOff;
|
|
Verdaux->vda_next = 0;
|
|
}
|
|
|
|
template <class ELFT>
|
|
void VersionDefinitionSection<ELFT>::writeTo(uint8_t *Buf) {
|
|
writeOne(Buf, 1, getFileDefName(), FileDefNameOff);
|
|
|
|
for (VersionDefinition &V : Config->VersionDefinitions) {
|
|
Buf += sizeof(Elf_Verdef) + sizeof(Elf_Verdaux);
|
|
writeOne(Buf, V.Id, V.Name, V.NameOff);
|
|
}
|
|
|
|
// Need to terminate the last version definition.
|
|
Elf_Verdef *Verdef = reinterpret_cast<Elf_Verdef *>(Buf);
|
|
Verdef->vd_next = 0;
|
|
}
|
|
|
|
template <class ELFT> size_t VersionDefinitionSection<ELFT>::getSize() const {
|
|
return (sizeof(Elf_Verdef) + sizeof(Elf_Verdaux)) * getVerDefNum();
|
|
}
|
|
|
|
template <class ELFT>
|
|
VersionTableSection<ELFT>::VersionTableSection()
|
|
: SyntheticSection(SHF_ALLOC, SHT_GNU_versym, sizeof(uint16_t),
|
|
".gnu.version") {
|
|
this->Entsize = sizeof(Elf_Versym);
|
|
}
|
|
|
|
template <class ELFT> void VersionTableSection<ELFT>::finalizeContents() {
|
|
// At the moment of june 2016 GNU docs does not mention that sh_link field
|
|
// should be set, but Sun docs do. Also readelf relies on this field.
|
|
getParent()->Link = InX::DynSymTab->getParent()->SectionIndex;
|
|
}
|
|
|
|
template <class ELFT> size_t VersionTableSection<ELFT>::getSize() const {
|
|
return sizeof(Elf_Versym) * (InX::DynSymTab->getSymbols().size() + 1);
|
|
}
|
|
|
|
template <class ELFT> void VersionTableSection<ELFT>::writeTo(uint8_t *Buf) {
|
|
auto *OutVersym = reinterpret_cast<Elf_Versym *>(Buf) + 1;
|
|
for (const SymbolTableEntry &S : InX::DynSymTab->getSymbols()) {
|
|
OutVersym->vs_index = S.Symbol->symbol()->VersionId;
|
|
++OutVersym;
|
|
}
|
|
}
|
|
|
|
template <class ELFT> bool VersionTableSection<ELFT>::empty() const {
|
|
return !In<ELFT>::VerDef && In<ELFT>::VerNeed->empty();
|
|
}
|
|
|
|
template <class ELFT>
|
|
VersionNeedSection<ELFT>::VersionNeedSection()
|
|
: SyntheticSection(SHF_ALLOC, SHT_GNU_verneed, sizeof(uint32_t),
|
|
".gnu.version_r") {
|
|
// Identifiers in verneed section start at 2 because 0 and 1 are reserved
|
|
// for VER_NDX_LOCAL and VER_NDX_GLOBAL.
|
|
// First identifiers are reserved by verdef section if it exist.
|
|
NextIndex = getVerDefNum() + 1;
|
|
}
|
|
|
|
template <class ELFT>
|
|
void VersionNeedSection<ELFT>::addSymbol(SharedSymbol *SS) {
|
|
auto *Ver = reinterpret_cast<const typename ELFT::Verdef *>(SS->Verdef);
|
|
if (!Ver) {
|
|
SS->symbol()->VersionId = VER_NDX_GLOBAL;
|
|
return;
|
|
}
|
|
|
|
auto *File = cast<SharedFile<ELFT>>(SS->File);
|
|
|
|
// If we don't already know that we need an Elf_Verneed for this DSO, prepare
|
|
// to create one by adding it to our needed list and creating a dynstr entry
|
|
// for the soname.
|
|
if (File->VerdefMap.empty())
|
|
Needed.push_back({File, InX::DynStrTab->addString(File->SoName)});
|
|
typename SharedFile<ELFT>::NeededVer &NV = File->VerdefMap[Ver];
|
|
// If we don't already know that we need an Elf_Vernaux for this Elf_Verdef,
|
|
// prepare to create one by allocating a version identifier and creating a
|
|
// dynstr entry for the version name.
|
|
if (NV.Index == 0) {
|
|
NV.StrTab = InX::DynStrTab->addString(File->getStringTable().data() +
|
|
Ver->getAux()->vda_name);
|
|
NV.Index = NextIndex++;
|
|
}
|
|
SS->symbol()->VersionId = NV.Index;
|
|
}
|
|
|
|
template <class ELFT> void VersionNeedSection<ELFT>::writeTo(uint8_t *Buf) {
|
|
// The Elf_Verneeds need to appear first, followed by the Elf_Vernauxs.
|
|
auto *Verneed = reinterpret_cast<Elf_Verneed *>(Buf);
|
|
auto *Vernaux = reinterpret_cast<Elf_Vernaux *>(Verneed + Needed.size());
|
|
|
|
for (std::pair<SharedFile<ELFT> *, size_t> &P : Needed) {
|
|
// Create an Elf_Verneed for this DSO.
|
|
Verneed->vn_version = 1;
|
|
Verneed->vn_cnt = P.first->VerdefMap.size();
|
|
Verneed->vn_file = P.second;
|
|
Verneed->vn_aux =
|
|
reinterpret_cast<char *>(Vernaux) - reinterpret_cast<char *>(Verneed);
|
|
Verneed->vn_next = sizeof(Elf_Verneed);
|
|
++Verneed;
|
|
|
|
// Create the Elf_Vernauxs for this Elf_Verneed. The loop iterates over
|
|
// VerdefMap, which will only contain references to needed version
|
|
// definitions. Each Elf_Vernaux is based on the information contained in
|
|
// the Elf_Verdef in the source DSO. This loop iterates over a std::map of
|
|
// pointers, but is deterministic because the pointers refer to Elf_Verdef
|
|
// data structures within a single input file.
|
|
for (auto &NV : P.first->VerdefMap) {
|
|
Vernaux->vna_hash = NV.first->vd_hash;
|
|
Vernaux->vna_flags = 0;
|
|
Vernaux->vna_other = NV.second.Index;
|
|
Vernaux->vna_name = NV.second.StrTab;
|
|
Vernaux->vna_next = sizeof(Elf_Vernaux);
|
|
++Vernaux;
|
|
}
|
|
|
|
Vernaux[-1].vna_next = 0;
|
|
}
|
|
Verneed[-1].vn_next = 0;
|
|
}
|
|
|
|
template <class ELFT> void VersionNeedSection<ELFT>::finalizeContents() {
|
|
getParent()->Link = InX::DynStrTab->getParent()->SectionIndex;
|
|
getParent()->Info = Needed.size();
|
|
}
|
|
|
|
template <class ELFT> size_t VersionNeedSection<ELFT>::getSize() const {
|
|
unsigned Size = Needed.size() * sizeof(Elf_Verneed);
|
|
for (const std::pair<SharedFile<ELFT> *, size_t> &P : Needed)
|
|
Size += P.first->VerdefMap.size() * sizeof(Elf_Vernaux);
|
|
return Size;
|
|
}
|
|
|
|
template <class ELFT> bool VersionNeedSection<ELFT>::empty() const {
|
|
return getNeedNum() == 0;
|
|
}
|
|
|
|
MergeSyntheticSection::MergeSyntheticSection(StringRef Name, uint32_t Type,
|
|
uint64_t Flags, uint32_t Alignment)
|
|
: SyntheticSection(Flags, Type, Alignment, Name),
|
|
Builder(StringTableBuilder::RAW, Alignment) {}
|
|
|
|
void MergeSyntheticSection::addSection(MergeInputSection *MS) {
|
|
MS->Parent = this;
|
|
Sections.push_back(MS);
|
|
}
|
|
|
|
void MergeSyntheticSection::writeTo(uint8_t *Buf) { Builder.write(Buf); }
|
|
|
|
bool MergeSyntheticSection::shouldTailMerge() const {
|
|
return (this->Flags & SHF_STRINGS) && Config->Optimize >= 2;
|
|
}
|
|
|
|
void MergeSyntheticSection::finalizeTailMerge() {
|
|
// Add all string pieces to the string table builder to create section
|
|
// contents.
|
|
for (MergeInputSection *Sec : Sections)
|
|
for (size_t I = 0, E = Sec->Pieces.size(); I != E; ++I)
|
|
if (Sec->Pieces[I].Live)
|
|
Builder.add(Sec->getData(I));
|
|
|
|
// Fix the string table content. After this, the contents will never change.
|
|
Builder.finalize();
|
|
|
|
// finalize() fixed tail-optimized strings, so we can now get
|
|
// offsets of strings. Get an offset for each string and save it
|
|
// to a corresponding StringPiece for easy access.
|
|
for (MergeInputSection *Sec : Sections)
|
|
for (size_t I = 0, E = Sec->Pieces.size(); I != E; ++I)
|
|
if (Sec->Pieces[I].Live)
|
|
Sec->Pieces[I].OutputOff = Builder.getOffset(Sec->getData(I));
|
|
}
|
|
|
|
void MergeSyntheticSection::finalizeNoTailMerge() {
|
|
// Add all string pieces to the string table builder to create section
|
|
// contents. Because we are not tail-optimizing, offsets of strings are
|
|
// fixed when they are added to the builder (string table builder contains
|
|
// a hash table from strings to offsets).
|
|
for (MergeInputSection *Sec : Sections)
|
|
for (size_t I = 0, E = Sec->Pieces.size(); I != E; ++I)
|
|
if (Sec->Pieces[I].Live)
|
|
Sec->Pieces[I].OutputOff = Builder.add(Sec->getData(I));
|
|
|
|
Builder.finalizeInOrder();
|
|
}
|
|
|
|
void MergeSyntheticSection::finalizeContents() {
|
|
if (shouldTailMerge())
|
|
finalizeTailMerge();
|
|
else
|
|
finalizeNoTailMerge();
|
|
}
|
|
|
|
size_t MergeSyntheticSection::getSize() const {
|
|
return Builder.getSize();
|
|
}
|
|
|
|
// This function decompresses compressed sections and scans over the input
|
|
// sections to create mergeable synthetic sections. It removes
|
|
// MergeInputSections from the input section array and adds new synthetic
|
|
// sections at the location of the first input section that it replaces. It then
|
|
// finalizes each synthetic section in order to compute an output offset for
|
|
// each piece of each input section.
|
|
void elf::decompressAndMergeSections() {
|
|
// splitIntoPieces needs to be called on each MergeInputSection before calling
|
|
// finalizeContents(). Do that first.
|
|
parallelForEach(InputSections.begin(), InputSections.end(),
|
|
[](InputSectionBase *S) {
|
|
if (!S->Live)
|
|
return;
|
|
if (Decompressor::isCompressedELFSection(S->Flags, S->Name))
|
|
S->uncompress();
|
|
if (auto *MS = dyn_cast<MergeInputSection>(S))
|
|
MS->splitIntoPieces();
|
|
});
|
|
|
|
std::vector<MergeSyntheticSection *> MergeSections;
|
|
for (InputSectionBase *&S : InputSections) {
|
|
MergeInputSection *MS = dyn_cast<MergeInputSection>(S);
|
|
if (!MS)
|
|
continue;
|
|
|
|
// We do not want to handle sections that are not alive, so just remove
|
|
// them instead of trying to merge.
|
|
if (!MS->Live)
|
|
continue;
|
|
|
|
StringRef OutsecName = getOutputSectionName(MS->Name);
|
|
uint64_t Flags = MS->Flags & ~(uint64_t)SHF_GROUP;
|
|
uint32_t Alignment = std::max<uint32_t>(MS->Alignment, MS->Entsize);
|
|
|
|
auto I = llvm::find_if(MergeSections, [=](MergeSyntheticSection *Sec) {
|
|
return Sec->Name == OutsecName && Sec->Flags == Flags &&
|
|
Sec->Alignment == Alignment;
|
|
});
|
|
if (I == MergeSections.end()) {
|
|
MergeSyntheticSection *Syn =
|
|
make<MergeSyntheticSection>(OutsecName, MS->Type, Flags, Alignment);
|
|
MergeSections.push_back(Syn);
|
|
I = std::prev(MergeSections.end());
|
|
S = Syn;
|
|
} else {
|
|
S = nullptr;
|
|
}
|
|
(*I)->addSection(MS);
|
|
}
|
|
for (auto *MS : MergeSections)
|
|
MS->finalizeContents();
|
|
|
|
std::vector<InputSectionBase *> &V = InputSections;
|
|
V.erase(std::remove(V.begin(), V.end(), nullptr), V.end());
|
|
}
|
|
|
|
MipsRldMapSection::MipsRldMapSection()
|
|
: SyntheticSection(SHF_ALLOC | SHF_WRITE, SHT_PROGBITS, Config->Wordsize,
|
|
".rld_map") {}
|
|
|
|
ARMExidxSentinelSection::ARMExidxSentinelSection()
|
|
: SyntheticSection(SHF_ALLOC | SHF_LINK_ORDER, SHT_ARM_EXIDX,
|
|
Config->Wordsize, ".ARM.exidx") {}
|
|
|
|
// Write a terminating sentinel entry to the end of the .ARM.exidx table.
|
|
// This section will have been sorted last in the .ARM.exidx table.
|
|
// This table entry will have the form:
|
|
// | PREL31 upper bound of code that has exception tables | EXIDX_CANTUNWIND |
|
|
// The sentinel must have the PREL31 value of an address higher than any
|
|
// address described by any other table entry.
|
|
void ARMExidxSentinelSection::writeTo(uint8_t *Buf) {
|
|
// The Sections are sorted in order of ascending PREL31 address with the
|
|
// sentinel last. We need to find the InputSection that precedes the
|
|
// sentinel. By construction the Sentinel is in the last
|
|
// InputSectionDescription as the InputSection that precedes it.
|
|
OutputSectionCommand *C = Script->getCmd(getParent());
|
|
auto ISD = std::find_if(C->Commands.rbegin(), C->Commands.rend(),
|
|
[](const BaseCommand *Base) {
|
|
return isa<InputSectionDescription>(Base);
|
|
});
|
|
auto L = cast<InputSectionDescription>(*ISD);
|
|
InputSection *Highest = L->Sections[L->Sections.size() - 2];
|
|
InputSection *LS = Highest->getLinkOrderDep();
|
|
uint64_t S = LS->getParent()->Addr + LS->getOffset(LS->getSize());
|
|
uint64_t P = getVA();
|
|
Target->relocateOne(Buf, R_ARM_PREL31, S - P);
|
|
write32le(Buf + 4, 0x1);
|
|
}
|
|
|
|
ThunkSection::ThunkSection(OutputSection *OS, uint64_t Off)
|
|
: SyntheticSection(SHF_ALLOC | SHF_EXECINSTR, SHT_PROGBITS,
|
|
Config->Wordsize, ".text.thunk") {
|
|
this->Parent = OS;
|
|
this->OutSecOff = Off;
|
|
}
|
|
|
|
void ThunkSection::addThunk(Thunk *T) {
|
|
uint64_t Off = alignTo(Size, T->alignment);
|
|
T->Offset = Off;
|
|
Thunks.push_back(T);
|
|
T->addSymbols(*this);
|
|
Size = Off + T->size();
|
|
}
|
|
|
|
void ThunkSection::writeTo(uint8_t *Buf) {
|
|
for (const Thunk *T : Thunks)
|
|
T->writeTo(Buf + T->Offset, *this);
|
|
}
|
|
|
|
InputSection *ThunkSection::getTargetInputSection() const {
|
|
const Thunk *T = Thunks.front();
|
|
return T->getTargetInputSection();
|
|
}
|
|
|
|
InputSection *InX::ARMAttributes;
|
|
BssSection *InX::Bss;
|
|
BssSection *InX::BssRelRo;
|
|
BuildIdSection *InX::BuildId;
|
|
InputSection *InX::Common;
|
|
SyntheticSection *InX::Dynamic;
|
|
StringTableSection *InX::DynStrTab;
|
|
SymbolTableBaseSection *InX::DynSymTab;
|
|
InputSection *InX::Interp;
|
|
GdbIndexSection *InX::GdbIndex;
|
|
GotSection *InX::Got;
|
|
GotPltSection *InX::GotPlt;
|
|
GnuHashTableSection *InX::GnuHashTab;
|
|
IgotPltSection *InX::IgotPlt;
|
|
MipsGotSection *InX::MipsGot;
|
|
MipsRldMapSection *InX::MipsRldMap;
|
|
PltSection *InX::Plt;
|
|
PltSection *InX::Iplt;
|
|
StringTableSection *InX::ShStrTab;
|
|
StringTableSection *InX::StrTab;
|
|
SymbolTableBaseSection *InX::SymTab;
|
|
|
|
template void PltSection::addEntry<ELF32LE>(SymbolBody &Sym);
|
|
template void PltSection::addEntry<ELF32BE>(SymbolBody &Sym);
|
|
template void PltSection::addEntry<ELF64LE>(SymbolBody &Sym);
|
|
template void PltSection::addEntry<ELF64BE>(SymbolBody &Sym);
|
|
|
|
template InputSection *elf::createCommonSection<ELF32LE>();
|
|
template InputSection *elf::createCommonSection<ELF32BE>();
|
|
template InputSection *elf::createCommonSection<ELF64LE>();
|
|
template InputSection *elf::createCommonSection<ELF64BE>();
|
|
|
|
template MergeInputSection *elf::createCommentSection<ELF32LE>();
|
|
template MergeInputSection *elf::createCommentSection<ELF32BE>();
|
|
template MergeInputSection *elf::createCommentSection<ELF64LE>();
|
|
template MergeInputSection *elf::createCommentSection<ELF64BE>();
|
|
|
|
template class elf::MipsAbiFlagsSection<ELF32LE>;
|
|
template class elf::MipsAbiFlagsSection<ELF32BE>;
|
|
template class elf::MipsAbiFlagsSection<ELF64LE>;
|
|
template class elf::MipsAbiFlagsSection<ELF64BE>;
|
|
|
|
template class elf::MipsOptionsSection<ELF32LE>;
|
|
template class elf::MipsOptionsSection<ELF32BE>;
|
|
template class elf::MipsOptionsSection<ELF64LE>;
|
|
template class elf::MipsOptionsSection<ELF64BE>;
|
|
|
|
template class elf::MipsReginfoSection<ELF32LE>;
|
|
template class elf::MipsReginfoSection<ELF32BE>;
|
|
template class elf::MipsReginfoSection<ELF64LE>;
|
|
template class elf::MipsReginfoSection<ELF64BE>;
|
|
|
|
template class elf::DynamicSection<ELF32LE>;
|
|
template class elf::DynamicSection<ELF32BE>;
|
|
template class elf::DynamicSection<ELF64LE>;
|
|
template class elf::DynamicSection<ELF64BE>;
|
|
|
|
template class elf::RelocationSection<ELF32LE>;
|
|
template class elf::RelocationSection<ELF32BE>;
|
|
template class elf::RelocationSection<ELF64LE>;
|
|
template class elf::RelocationSection<ELF64BE>;
|
|
|
|
template class elf::SymbolTableSection<ELF32LE>;
|
|
template class elf::SymbolTableSection<ELF32BE>;
|
|
template class elf::SymbolTableSection<ELF64LE>;
|
|
template class elf::SymbolTableSection<ELF64BE>;
|
|
|
|
template class elf::HashTableSection<ELF32LE>;
|
|
template class elf::HashTableSection<ELF32BE>;
|
|
template class elf::HashTableSection<ELF64LE>;
|
|
template class elf::HashTableSection<ELF64BE>;
|
|
|
|
template class elf::EhFrameHeader<ELF32LE>;
|
|
template class elf::EhFrameHeader<ELF32BE>;
|
|
template class elf::EhFrameHeader<ELF64LE>;
|
|
template class elf::EhFrameHeader<ELF64BE>;
|
|
|
|
template class elf::VersionTableSection<ELF32LE>;
|
|
template class elf::VersionTableSection<ELF32BE>;
|
|
template class elf::VersionTableSection<ELF64LE>;
|
|
template class elf::VersionTableSection<ELF64BE>;
|
|
|
|
template class elf::VersionNeedSection<ELF32LE>;
|
|
template class elf::VersionNeedSection<ELF32BE>;
|
|
template class elf::VersionNeedSection<ELF64LE>;
|
|
template class elf::VersionNeedSection<ELF64BE>;
|
|
|
|
template class elf::VersionDefinitionSection<ELF32LE>;
|
|
template class elf::VersionDefinitionSection<ELF32BE>;
|
|
template class elf::VersionDefinitionSection<ELF64LE>;
|
|
template class elf::VersionDefinitionSection<ELF64BE>;
|
|
|
|
template class elf::EhFrameSection<ELF32LE>;
|
|
template class elf::EhFrameSection<ELF32BE>;
|
|
template class elf::EhFrameSection<ELF64LE>;
|
|
template class elf::EhFrameSection<ELF64BE>;
|