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llvm-project/lld/ELF/OutputSections.cpp

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//===- OutputSections.cpp -------------------------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "OutputSections.h"
#include "Config.h"
#include "EhFrame.h"
#include "GdbIndex.h"
#include "LinkerScript.h"
#include "Memory.h"
#include "Strings.h"
#include "SymbolTable.h"
#include "SyntheticSections.h"
#include "Target.h"
#include "lld/Core/Parallel.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Support/MD5.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/SHA1.h"
using namespace llvm;
using namespace llvm::dwarf;
using namespace llvm::object;
using namespace llvm::support::endian;
using namespace llvm::ELF;
using namespace lld;
using namespace lld::elf;
template <class ELFT>
OutputSectionBase<ELFT>::OutputSectionBase(StringRef Name, uint32_t Type,
uintX_t Flags)
: Name(Name) {
memset(&Header, 0, sizeof(Elf_Shdr));
Header.sh_type = Type;
Header.sh_flags = Flags;
Header.sh_addralign = 1;
}
template <class ELFT> uint32_t OutputSectionBase<ELFT>::getPhdrFlags() const {
uintX_t Flags = getFlags();
uint32_t Ret = PF_R;
if (Flags & SHF_WRITE)
Ret |= PF_W;
if (Flags & SHF_EXECINSTR)
Ret |= PF_X;
return Ret;
}
template <class ELFT>
void OutputSectionBase<ELFT>::writeHeaderTo(Elf_Shdr *Shdr) {
*Shdr = Header;
}
template <class ELFT>
GdbIndexSection<ELFT>::GdbIndexSection()
: OutputSectionBase<ELFT>(".gdb_index", SHT_PROGBITS, 0) {}
template <class ELFT> void GdbIndexSection<ELFT>::parseDebugSections() {
std::vector<InputSection<ELFT> *> &IS =
static_cast<OutputSection<ELFT> *>(Out<ELFT>::DebugInfo)->Sections;
for (InputSection<ELFT> *I : IS)
readDwarf(I);
}
template <class ELFT>
void GdbIndexSection<ELFT>::readDwarf(InputSection<ELFT> *I) {
std::vector<std::pair<uintX_t, uintX_t>> CuList = readCuList(I);
CompilationUnits.insert(CompilationUnits.end(), CuList.begin(), CuList.end());
}
template <class ELFT> void GdbIndexSection<ELFT>::finalize() {
parseDebugSections();
// GdbIndex header consist from version fields
// and 5 more fields with different kinds of offsets.
CuTypesOffset = CuListOffset + CompilationUnits.size() * CompilationUnitSize;
this->Header.sh_size = CuTypesOffset;
}
template <class ELFT> void GdbIndexSection<ELFT>::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, CuTypesOffset); // Symbol table offset
write32le(Buf + 20, CuTypesOffset); // Constant pool offset
Buf += 24;
// Write the CU list.
for (std::pair<uintX_t, uintX_t> CU : CompilationUnits) {
write64le(Buf, CU.first);
write64le(Buf + 8, CU.second);
Buf += 16;
}
}
template <class ELFT>
GotPltSection<ELFT>::GotPltSection()
: OutputSectionBase<ELFT>(".got.plt", SHT_PROGBITS, SHF_ALLOC | SHF_WRITE) {
this->Header.sh_addralign = Target->GotPltEntrySize;
}
template <class ELFT> void GotPltSection<ELFT>::addEntry(SymbolBody &Sym) {
Sym.GotPltIndex = Target->GotPltHeaderEntriesNum + Entries.size();
Entries.push_back(&Sym);
}
template <class ELFT> bool GotPltSection<ELFT>::empty() const {
return Entries.empty();
}
template <class ELFT> void GotPltSection<ELFT>::finalize() {
this->Header.sh_size = (Target->GotPltHeaderEntriesNum + Entries.size()) *
Target->GotPltEntrySize;
}
template <class ELFT> void GotPltSection<ELFT>::writeTo(uint8_t *Buf) {
Target->writeGotPltHeader(Buf);
Buf += Target->GotPltHeaderEntriesNum * Target->GotPltEntrySize;
for (const SymbolBody *B : Entries) {
Target->writeGotPlt(Buf, *B);
Buf += sizeof(uintX_t);
}
}
template <class ELFT>
GotSection<ELFT>::GotSection()
: OutputSectionBase<ELFT>(".got", SHT_PROGBITS, SHF_ALLOC | SHF_WRITE) {
if (Config->EMachine == EM_MIPS)
this->Header.sh_flags |= SHF_MIPS_GPREL;
this->Header.sh_addralign = Target->GotEntrySize;
}
template <class ELFT> void GotSection<ELFT>::addEntry(SymbolBody &Sym) {
Sym.GotIndex = Entries.size();
Entries.push_back(&Sym);
}
template <class ELFT>
void GotSection<ELFT>::addMipsEntry(SymbolBody &Sym, uintX_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.
auto *OutSec = cast<DefinedRegular<ELFT>>(&Sym)->Section->OutSec;
MipsOutSections.insert(OutSec);
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 = Entries.size();
Entries.push_back(&Sym);
return;
}
auto AddEntry = [&](SymbolBody &S, uintX_t A, MipsGotEntries &Items) {
if (S.isInGot() && !A)
return;
size_t NewIndex = Items.size();
if (!MipsGotMap.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, MipsGlobal);
Sym.IsInGlobalMipsGot = true;
} else if (Expr == R_MIPS_GOT_OFF32) {
AddEntry(Sym, Addend, MipsLocal32);
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, MipsLocal);
}
}
template <class ELFT> bool GotSection<ELFT>::addDynTlsEntry(SymbolBody &Sym) {
if (Sym.GlobalDynIndex != -1U)
return false;
Sym.GlobalDynIndex = Entries.size();
// Global Dynamic TLS entries take two GOT slots.
Entries.push_back(nullptr);
Entries.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.
template <class ELFT> bool GotSection<ELFT>::addTlsIndex() {
if (TlsIndexOff != uint32_t(-1))
return false;
TlsIndexOff = Entries.size() * sizeof(uintX_t);
Entries.push_back(nullptr);
Entries.push_back(nullptr);
return true;
}
template <class ELFT>
typename GotSection<ELFT>::uintX_t
GotSection<ELFT>::getMipsLocalPageOffset(uintX_t EntryValue) {
// Initialize the entry by the %hi(EntryValue) expression
// but without right-shifting.
EntryValue = (EntryValue + 0x8000) & ~0xffff;
// Take into account MIPS GOT header.
// See comment in the GotSection::writeTo.
size_t NewIndex = MipsLocalGotPos.size() + 2;
auto P = MipsLocalGotPos.insert(std::make_pair(EntryValue, NewIndex));
assert(!P.second || MipsLocalGotPos.size() <= MipsPageEntries);
return (uintX_t)P.first->second * sizeof(uintX_t) - MipsGPOffset;
}
template <class ELFT>
typename GotSection<ELFT>::uintX_t
GotSection<ELFT>::getMipsGotOffset(const SymbolBody &B, uintX_t Addend) const {
// Calculate offset of the GOT entries block: TLS, global, local.
uintX_t GotBlockOff;
if (B.isTls())
GotBlockOff = getMipsTlsOffset();
else if (B.IsInGlobalMipsGot)
GotBlockOff = getMipsLocalEntriesNum() * sizeof(uintX_t);
else if (B.Is32BitMipsGot)
GotBlockOff = (MipsPageEntries + MipsLocal.size()) * sizeof(uintX_t);
else
GotBlockOff = MipsPageEntries * sizeof(uintX_t);
// Calculate index of the GOT entry in the block.
uintX_t GotIndex;
if (B.isInGot())
GotIndex = B.GotIndex;
else {
auto It = MipsGotMap.find({&B, Addend});
assert(It != MipsGotMap.end());
GotIndex = It->second;
}
return GotBlockOff + GotIndex * sizeof(uintX_t) - MipsGPOffset;
}
template <class ELFT>
typename GotSection<ELFT>::uintX_t GotSection<ELFT>::getMipsTlsOffset() const {
return (getMipsLocalEntriesNum() + MipsGlobal.size()) * sizeof(uintX_t);
}
template <class ELFT>
typename GotSection<ELFT>::uintX_t
GotSection<ELFT>::getGlobalDynAddr(const SymbolBody &B) const {
return this->getVA() + B.GlobalDynIndex * sizeof(uintX_t);
}
template <class ELFT>
typename GotSection<ELFT>::uintX_t
GotSection<ELFT>::getGlobalDynOffset(const SymbolBody &B) const {
return B.GlobalDynIndex * sizeof(uintX_t);
}
template <class ELFT>
const SymbolBody *GotSection<ELFT>::getMipsFirstGlobalEntry() const {
return MipsGlobal.empty() ? nullptr : MipsGlobal.front().first;
}
template <class ELFT>
unsigned GotSection<ELFT>::getMipsLocalEntriesNum() const {
return MipsPageEntries + MipsLocal.size() + MipsLocal32.size();
}
template <class ELFT> void GotSection<ELFT>::finalize() {
size_t EntriesNum = Entries.size();
if (Config->EMachine == EM_MIPS) {
// Take into account MIPS GOT header.
// See comment in the GotSection::writeTo.
MipsPageEntries += 2;
for (const OutputSectionBase<ELFT> *OutSec : MipsOutSections) {
// Calculate 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.
// Add 0x8000 to the section's size because the page address stored
// in the GOT entry is calculated as (value + 0x8000) & ~0xffff.
MipsPageEntries += (OutSec->getSize() + 0x8000 + 0xfffe) / 0xffff;
}
EntriesNum += getMipsLocalEntriesNum() + MipsGlobal.size();
}
this->Header.sh_size = EntriesNum * sizeof(uintX_t);
}
template <class ELFT>
static void writeUint(uint8_t *Buf, typename ELFT::uint Val) {
typedef typename ELFT::uint uintX_t;
write<uintX_t, ELFT::TargetEndianness, sizeof(uintX_t)>(Buf, Val);
}
template <class ELFT> void GotSection<ELFT>::writeMipsGot(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.
auto *P = reinterpret_cast<typename ELFT::Off *>(Buf);
P[1] = uintX_t(1) << (ELFT::Is64Bits ? 63 : 31);
// Write 'page address' entries to the local part of the GOT.
for (std::pair<uintX_t, size_t> &L : MipsLocalGotPos) {
uint8_t *Entry = Buf + L.second * sizeof(uintX_t);
writeUint<ELFT>(Entry, L.first);
}
Buf += MipsPageEntries * sizeof(uintX_t);
auto AddEntry = [&](const MipsGotEntry &SA) {
uint8_t *Entry = Buf;
Buf += sizeof(uintX_t);
const SymbolBody *Body = SA.first;
uintX_t VA = Body->template getVA<ELFT>(SA.second);
writeUint<ELFT>(Entry, VA);
};
std::for_each(std::begin(MipsLocal), std::end(MipsLocal), AddEntry);
std::for_each(std::begin(MipsLocal32), std::end(MipsLocal32), AddEntry);
std::for_each(std::begin(MipsGlobal), std::end(MipsGlobal), 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<ELFT>(Buf + TlsIndexOff, 1);
for (const SymbolBody *B : Entries) {
if (!B || B->isPreemptible())
continue;
uintX_t VA = B->getVA<ELFT>();
if (B->GotIndex != -1U) {
uint8_t *Entry = Buf + B->GotIndex * sizeof(uintX_t);
writeUint<ELFT>(Entry, VA - 0x7000);
}
if (B->GlobalDynIndex != -1U) {
uint8_t *Entry = Buf + B->GlobalDynIndex * sizeof(uintX_t);
writeUint<ELFT>(Entry, 1);
Entry += sizeof(uintX_t);
writeUint<ELFT>(Entry, VA - 0x8000);
}
}
}
template <class ELFT> void GotSection<ELFT>::writeTo(uint8_t *Buf) {
if (Config->EMachine == EM_MIPS) {
writeMipsGot(Buf);
return;
}
for (const SymbolBody *B : Entries) {
uint8_t *Entry = Buf;
Buf += sizeof(uintX_t);
if (!B)
continue;
if (B->isPreemptible())
continue; // The dynamic linker will take care of it.
uintX_t VA = B->getVA<ELFT>();
writeUint<ELFT>(Entry, VA);
}
}
template <class ELFT>
PltSection<ELFT>::PltSection()
: OutputSectionBase<ELFT>(".plt", SHT_PROGBITS, SHF_ALLOC | SHF_EXECINSTR) {
this->Header.sh_addralign = 16;
}
template <class ELFT> void PltSection<ELFT>::writeTo(uint8_t *Buf) {
// At beginning of PLT, we have code to call the dynamic linker
// to resolve dynsyms at runtime. Write such code.
Target->writePltHeader(Buf);
size_t Off = Target->PltHeaderSize;
for (auto &I : Entries) {
const SymbolBody *B = I.first;
unsigned RelOff = I.second;
uint64_t Got = B->getGotPltVA<ELFT>();
uint64_t Plt = this->getVA() + Off;
Target->writePlt(Buf + Off, Got, Plt, B->PltIndex, RelOff);
Off += Target->PltEntrySize;
}
}
template <class ELFT> void PltSection<ELFT>::addEntry(SymbolBody &Sym) {
Sym.PltIndex = Entries.size();
unsigned RelOff = Out<ELFT>::RelaPlt->getRelocOffset();
Entries.push_back(std::make_pair(&Sym, RelOff));
}
template <class ELFT> void PltSection<ELFT>::finalize() {
this->Header.sh_size =
Target->PltHeaderSize + Entries.size() * Target->PltEntrySize;
}
template <class ELFT>
RelocationSection<ELFT>::RelocationSection(StringRef Name, bool Sort)
: OutputSectionBase<ELFT>(Name, Config->Rela ? SHT_RELA : SHT_REL,
SHF_ALLOC),
Sort(Sort) {
this->Header.sh_entsize = Config->Rela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
this->Header.sh_addralign = sizeof(uintX_t);
}
template <class ELFT>
void RelocationSection<ELFT>::addReloc(const DynamicReloc<ELFT> &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->Mips64EL) == Target->RelativeRel;
bool BIsRel = B.getType(Config->Mips64EL) == Target->RelativeRel;
if (AIsRel != BIsRel)
return AIsRel;
return A.getSymbol(Config->Mips64EL) < B.getSymbol(Config->Mips64EL);
}
template <class ELFT> void RelocationSection<ELFT>::writeTo(uint8_t *Buf) {
uint8_t *BufBegin = Buf;
for (const DynamicReloc<ELFT> &Rel : Relocs) {
auto *P = reinterpret_cast<Elf_Rela *>(Buf);
Buf += Config->Rela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
if (Config->Rela)
P->r_addend = Rel.getAddend();
P->r_offset = Rel.getOffset();
if (Config->EMachine == EM_MIPS && Rel.getOutputSec() == Out<ELFT>::Got)
// 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 += Out<ELFT>::Got->getMipsTlsOffset();
P->setSymbolAndType(Rel.getSymIndex(), Rel.Type, Config->Mips64EL);
}
if (Sort) {
if (Config->Rela)
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->Header.sh_entsize * Relocs.size();
}
template <class ELFT> void RelocationSection<ELFT>::finalize() {
this->Header.sh_link = Out<ELFT>::DynSymTab
? Out<ELFT>::DynSymTab->SectionIndex
: Out<ELFT>::SymTab->SectionIndex;
this->Header.sh_size = Relocs.size() * this->Header.sh_entsize;
}
template <class ELFT>
HashTableSection<ELFT>::HashTableSection()
: OutputSectionBase<ELFT>(".hash", SHT_HASH, SHF_ALLOC) {
this->Header.sh_entsize = sizeof(Elf_Word);
this->Header.sh_addralign = sizeof(Elf_Word);
}
template <class ELFT> void HashTableSection<ELFT>::finalize() {
this->Header.sh_link = Out<ELFT>::DynSymTab->SectionIndex;
unsigned NumEntries = 2; // nbucket and nchain.
NumEntries += Out<ELFT>::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 += Out<ELFT>::DynSymTab->getNumSymbols();
this->Header.sh_size = NumEntries * sizeof(Elf_Word);
}
template <class ELFT> void HashTableSection<ELFT>::writeTo(uint8_t *Buf) {
unsigned NumSymbols = Out<ELFT>::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 : Out<ELFT>::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;
}
}
static uint32_t hashGnu(StringRef Name) {
uint32_t H = 5381;
for (uint8_t C : Name)
H = (H << 5) + H + C;
return H;
}
template <class ELFT>
GnuHashTableSection<ELFT>::GnuHashTableSection()
: OutputSectionBase<ELFT>(".gnu.hash", SHT_GNU_HASH, SHF_ALLOC) {
this->Header.sh_entsize = ELFT::Is64Bits ? 0 : 4;
this->Header.sh_addralign = sizeof(uintX_t);
}
template <class ELFT>
unsigned GnuHashTableSection<ELFT>::calcNBuckets(unsigned NumHashed) {
if (!NumHashed)
return 0;
// These values are prime numbers which are not greater than 2^(N-1) + 1.
// In result, for any particular NumHashed we return a prime number
// which is not greater than NumHashed.
static const unsigned Primes[] = {
1, 1, 3, 3, 7, 13, 31, 61, 127, 251,
509, 1021, 2039, 4093, 8191, 16381, 32749, 65521, 131071};
return Primes[std::min<unsigned>(Log2_32_Ceil(NumHashed),
array_lengthof(Primes) - 1)];
}
// Bloom filter estimation: at least 8 bits for each hashed symbol.
// GNU Hash table requirement: it should be a power of 2,
// the minimum value is 1, even for an empty table.
// Expected results for a 32-bit target:
// calcMaskWords(0..4) = 1
// calcMaskWords(5..8) = 2
// calcMaskWords(9..16) = 4
// For a 64-bit target:
// calcMaskWords(0..8) = 1
// calcMaskWords(9..16) = 2
// calcMaskWords(17..32) = 4
template <class ELFT>
unsigned GnuHashTableSection<ELFT>::calcMaskWords(unsigned NumHashed) {
if (!NumHashed)
return 1;
return NextPowerOf2((NumHashed - 1) / sizeof(Elf_Off));
}
template <class ELFT> void GnuHashTableSection<ELFT>::finalize() {
unsigned NumHashed = Symbols.size();
NBuckets = calcNBuckets(NumHashed);
MaskWords = calcMaskWords(NumHashed);
// Second hash shift estimation: just predefined values.
Shift2 = ELFT::Is64Bits ? 6 : 5;
this->Header.sh_link = Out<ELFT>::DynSymTab->SectionIndex;
this->Header.sh_size = sizeof(Elf_Word) * 4 // Header
+ sizeof(Elf_Off) * MaskWords // Bloom Filter
+ sizeof(Elf_Word) * NBuckets // Hash Buckets
+ sizeof(Elf_Word) * NumHashed; // Hash Values
}
template <class ELFT> void GnuHashTableSection<ELFT>::writeTo(uint8_t *Buf) {
writeHeader(Buf);
if (Symbols.empty())
return;
writeBloomFilter(Buf);
writeHashTable(Buf);
}
template <class ELFT>
void GnuHashTableSection<ELFT>::writeHeader(uint8_t *&Buf) {
auto *P = reinterpret_cast<Elf_Word *>(Buf);
*P++ = NBuckets;
*P++ = Out<ELFT>::DynSymTab->getNumSymbols() - Symbols.size();
*P++ = MaskWords;
*P++ = Shift2;
Buf = reinterpret_cast<uint8_t *>(P);
}
template <class ELFT>
void GnuHashTableSection<ELFT>::writeBloomFilter(uint8_t *&Buf) {
unsigned C = sizeof(Elf_Off) * 8;
auto *Masks = reinterpret_cast<Elf_Off *>(Buf);
for (const SymbolData &Sym : Symbols) {
size_t Pos = (Sym.Hash / C) & (MaskWords - 1);
uintX_t V = (uintX_t(1) << (Sym.Hash % C)) |
(uintX_t(1) << ((Sym.Hash >> Shift2) % C));
Masks[Pos] |= V;
}
Buf += sizeof(Elf_Off) * MaskWords;
}
template <class ELFT>
void GnuHashTableSection<ELFT>::writeHashTable(uint8_t *Buf) {
Elf_Word *Buckets = reinterpret_cast<Elf_Word *>(Buf);
Elf_Word *Values = Buckets + NBuckets;
int PrevBucket = -1;
int I = 0;
for (const SymbolData &Sym : Symbols) {
int Bucket = Sym.Hash % NBuckets;
assert(PrevBucket <= Bucket);
if (Bucket != PrevBucket) {
Buckets[Bucket] = Sym.Body->DynsymIndex;
PrevBucket = Bucket;
if (I > 0)
Values[I - 1] |= 1;
}
Values[I] = Sym.Hash & ~1;
++I;
}
if (I > 0)
Values[I - 1] |= 1;
}
// 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.
template <class ELFT>
void GnuHashTableSection<ELFT>::addSymbols(std::vector<SymbolTableEntry> &V) {
// Ideally this will just be 'auto' but GCC 6.1 is not able
// to deduce it 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 (auto I = Mid, E = V.end(); I != E; ++I) {
SymbolBody *B = I->Symbol;
size_t StrOff = I->StrTabOffset;
Symbols.push_back({B, StrOff, hashGnu(B->getName())});
}
unsigned NBuckets = calcNBuckets(Symbols.size());
std::stable_sort(Symbols.begin(), Symbols.end(),
[&](const SymbolData &L, const SymbolData &R) {
return L.Hash % NBuckets < R.Hash % NBuckets;
});
V.erase(Mid, V.end());
for (const SymbolData &Sym : Symbols)
V.push_back({Sym.Body, Sym.STName});
}
// 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()
: OutputSectionBase<ELFT>(".dynamic", SHT_DYNAMIC, SHF_ALLOC | SHF_WRITE) {
Elf_Shdr &Header = this->Header;
Header.sh_addralign = sizeof(uintX_t);
Header.sh_entsize = ELFT::Is64Bits ? 16 : 8;
// .dynamic section is not writable on MIPS.
// 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)
Header.sh_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, Out<ELFT>::DynStrTab->addString(S)});
if (!Config->RPath.empty())
Add({Config->EnableNewDtags ? DT_RUNPATH : DT_RPATH,
Out<ELFT>::DynStrTab->addString(Config->RPath)});
for (SharedFile<ELFT> *F : Symtab<ELFT>::X->getSharedFiles())
if (F->isNeeded())
Add({DT_NEEDED, Out<ELFT>::DynStrTab->addString(F->getSoName())});
if (!Config->SoName.empty())
Add({DT_SONAME, Out<ELFT>::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->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});
if (!Config->Entry.empty())
Add({DT_DEBUG, (uint64_t)0});
}
// Add remaining entries to complete .dynamic contents.
template <class ELFT> void DynamicSection<ELFT>::finalize() {
if (this->Header.sh_size)
return; // Already finalized.
this->Header.sh_link = Out<ELFT>::DynStrTab->SectionIndex;
if (Out<ELFT>::RelaDyn->hasRelocs()) {
bool IsRela = Config->Rela;
Add({IsRela ? DT_RELA : DT_REL, Out<ELFT>::RelaDyn});
Add({IsRela ? DT_RELASZ : DT_RELSZ, Out<ELFT>::RelaDyn->getSize()});
Add({IsRela ? DT_RELAENT : DT_RELENT,
uintX_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 = Out<ELFT>::RelaDyn->getRelativeRelocCount();
if (Config->ZCombreloc && NumRelativeRels)
Add({IsRela ? DT_RELACOUNT : DT_RELCOUNT, NumRelativeRels});
}
}
if (Out<ELFT>::RelaPlt && Out<ELFT>::RelaPlt->hasRelocs()) {
Add({DT_JMPREL, Out<ELFT>::RelaPlt});
Add({DT_PLTRELSZ, Out<ELFT>::RelaPlt->getSize()});
Add({Config->EMachine == EM_MIPS ? DT_MIPS_PLTGOT : DT_PLTGOT,
Out<ELFT>::GotPlt});
Add({DT_PLTREL, uint64_t(Config->Rela ? DT_RELA : DT_REL)});
}
Add({DT_SYMTAB, Out<ELFT>::DynSymTab});
Add({DT_SYMENT, sizeof(Elf_Sym)});
Add({DT_STRTAB, Out<ELFT>::DynStrTab});
Add({DT_STRSZ, Out<ELFT>::DynStrTab->getSize()});
if (Out<ELFT>::GnuHashTab)
Add({DT_GNU_HASH, Out<ELFT>::GnuHashTab});
if (Out<ELFT>::HashTab)
Add({DT_HASH, Out<ELFT>::HashTab});
if (Out<ELFT>::PreinitArray) {
Add({DT_PREINIT_ARRAY, Out<ELFT>::PreinitArray});
Add({DT_PREINIT_ARRAYSZ, Out<ELFT>::PreinitArray, Entry::SecSize});
}
if (Out<ELFT>::InitArray) {
Add({DT_INIT_ARRAY, Out<ELFT>::InitArray});
Add({DT_INIT_ARRAYSZ, Out<ELFT>::InitArray, Entry::SecSize});
}
if (Out<ELFT>::FiniArray) {
Add({DT_FINI_ARRAY, Out<ELFT>::FiniArray});
Add({DT_FINI_ARRAYSZ, Out<ELFT>::FiniArray, Entry::SecSize});
}
if (SymbolBody *B = Symtab<ELFT>::X->find(Config->Init))
Add({DT_INIT, B});
if (SymbolBody *B = Symtab<ELFT>::X->find(Config->Fini))
Add({DT_FINI, B});
bool HasVerNeed = Out<ELFT>::VerNeed->getNeedNum() != 0;
if (HasVerNeed || Out<ELFT>::VerDef)
Add({DT_VERSYM, Out<ELFT>::VerSym});
if (Out<ELFT>::VerDef) {
Add({DT_VERDEF, Out<ELFT>::VerDef});
Add({DT_VERDEFNUM, getVerDefNum()});
}
if (HasVerNeed) {
Add({DT_VERNEED, Out<ELFT>::VerNeed});
Add({DT_VERNEEDNUM, Out<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, Out<ELFT>::DynSymTab->getNumSymbols()});
Add({DT_MIPS_LOCAL_GOTNO, Out<ELFT>::Got->getMipsLocalEntriesNum()});
if (const SymbolBody *B = Out<ELFT>::Got->getMipsFirstGlobalEntry())
Add({DT_MIPS_GOTSYM, B->DynsymIndex});
else
Add({DT_MIPS_GOTSYM, Out<ELFT>::DynSymTab->getNumSymbols()});
Add({DT_PLTGOT, Out<ELFT>::Got});
if (Out<ELFT>::MipsRldMap)
Add({DT_MIPS_RLD_MAP, Out<ELFT>::MipsRldMap});
}
// +1 for DT_NULL
this->Header.sh_size = (Entries.size() + 1) * this->Header.sh_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->getVA();
break;
case Entry::SecSize:
P->d_un.d_val = E.OutSec->getSize();
break;
case Entry::SymAddr:
P->d_un.d_ptr = E.Sym->template getVA<ELFT>();
break;
case Entry::PlainInt:
P->d_un.d_val = E.Val;
break;
}
++P;
}
}
template <class ELFT>
EhFrameHeader<ELFT>::EhFrameHeader()
: OutputSectionBase<ELFT>(".eh_frame_hdr", SHT_PROGBITS, SHF_ALLOC) {}
// .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, Out<ELFT>::EhFrame->getVA() - this->getVA() - 4);
write32<E>(Buf + 8, Fdes.size());
Buf += 12;
uintX_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> void EhFrameHeader<ELFT>::finalize() {
// .eh_frame_hdr has a 12 bytes header followed by an array of FDEs.
this->Header.sh_size = 12 + Out<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>
OutputSection<ELFT>::OutputSection(StringRef Name, uint32_t Type, uintX_t Flags)
: OutputSectionBase<ELFT>(Name, Type, Flags) {
if (Type == SHT_RELA)
this->Header.sh_entsize = sizeof(Elf_Rela);
else if (Type == SHT_REL)
this->Header.sh_entsize = sizeof(Elf_Rel);
}
template <class ELFT> void OutputSection<ELFT>::finalize() {
uint32_t Type = this->Header.sh_type;
if (this->Header.sh_flags & SHF_LINK_ORDER) {
if (!Config->Relocatable) {
// SHF_LINK_ORDER only has meaning in relocatable objects
this->Header.sh_flags &= ~SHF_LINK_ORDER;
}
else if (!this->Sections.empty()) {
// When doing a relocatable link we must preserve the link order
// dependency of sections with the SHF_LINK_ORDER flag. The dependency
// is indicated by the sh_link field. We need to translate the
// InputSection sh_link to the OutputSection sh_link, all InputSections
// in the OutputSection have the same dependency.
if (auto *D = this->Sections.front()->getLinkOrderDep())
this->Header.sh_link = D->OutSec->SectionIndex;
}
}
if (Type != SHT_RELA && Type != SHT_REL)
return;
this->Header.sh_link = Out<ELFT>::SymTab->SectionIndex;
// sh_info for SHT_REL[A] sections should contain the section header index of
// the section to which the relocation applies.
InputSectionBase<ELFT> *S = Sections[0]->getRelocatedSection();
this->Header.sh_info = S->OutSec->SectionIndex;
}
template <class ELFT>
void OutputSection<ELFT>::addSection(InputSectionBase<ELFT> *C) {
assert(C->Live);
auto *S = cast<InputSection<ELFT>>(C);
Sections.push_back(S);
S->OutSec = this;
this->updateAlignment(S->Alignment);
// Keep sh_entsize value of the input section to be able to perform merging
// later during a final linking using the generated relocatable object.
if (Config->Relocatable && (S->Flags & SHF_MERGE))
this->Header.sh_entsize = S->Entsize;
}
// This function is called after we sort input sections
// and scan relocations to setup sections' offsets.
template <class ELFT> void OutputSection<ELFT>::assignOffsets() {
uintX_t Off = this->Header.sh_size;
for (InputSection<ELFT> *S : Sections) {
Off = alignTo(Off, S->Alignment);
S->OutSecOff = Off;
Off += S->getSize();
}
this->Header.sh_size = Off;
}
// Sorts input sections by section name suffixes, so that .foo.N comes
// before .foo.M if N < M. Used to sort .{init,fini}_array.N sections.
// We want to keep the original order if the priorities are the same
// because the compiler keeps the original initialization order in a
// translation unit and we need to respect that.
// For more detail, read the section of the GCC's manual about init_priority.
template <class ELFT> void OutputSection<ELFT>::sortInitFini() {
// Sort sections by priority.
typedef std::pair<int, InputSection<ELFT> *> Pair;
auto Comp = [](const Pair &A, const Pair &B) { return A.first < B.first; };
std::vector<Pair> V;
for (InputSection<ELFT> *S : Sections)
V.push_back({getPriority(S->Name), S});
std::stable_sort(V.begin(), V.end(), Comp);
Sections.clear();
for (Pair &P : V)
Sections.push_back(P.second);
}
// Returns true if S matches /Filename.?\.o$/.
static bool isCrtBeginEnd(StringRef S, StringRef Filename) {
if (!S.endswith(".o"))
return false;
S = S.drop_back(2);
if (S.endswith(Filename))
return true;
return !S.empty() && S.drop_back().endswith(Filename);
}
static bool isCrtbegin(StringRef S) { return isCrtBeginEnd(S, "crtbegin"); }
static bool isCrtend(StringRef S) { return isCrtBeginEnd(S, "crtend"); }
// .ctors and .dtors are sorted by this priority from highest to lowest.
//
// 1. The section was contained in crtbegin (crtbegin contains
// some sentinel value in its .ctors and .dtors so that the runtime
// can find the beginning of the sections.)
//
// 2. The section has an optional priority value in the form of ".ctors.N"
// or ".dtors.N" where N is a number. Unlike .{init,fini}_array,
// they are compared as string rather than number.
//
// 3. The section is just ".ctors" or ".dtors".
//
// 4. The section was contained in crtend, which contains an end marker.
//
// In an ideal world, we don't need this function because .init_array and
// .ctors are duplicate features (and .init_array is newer.) However, there
// are too many real-world use cases of .ctors, so we had no choice to
// support that with this rather ad-hoc semantics.
template <class ELFT>
static bool compCtors(const InputSection<ELFT> *A,
const InputSection<ELFT> *B) {
bool BeginA = isCrtbegin(A->getFile()->getName());
bool BeginB = isCrtbegin(B->getFile()->getName());
if (BeginA != BeginB)
return BeginA;
bool EndA = isCrtend(A->getFile()->getName());
bool EndB = isCrtend(B->getFile()->getName());
if (EndA != EndB)
return EndB;
StringRef X = A->Name;
StringRef Y = B->Name;
assert(X.startswith(".ctors") || X.startswith(".dtors"));
assert(Y.startswith(".ctors") || Y.startswith(".dtors"));
X = X.substr(6);
Y = Y.substr(6);
if (X.empty() && Y.empty())
return false;
return X < Y;
}
// Sorts input sections by the special rules for .ctors and .dtors.
// Unfortunately, the rules are different from the one for .{init,fini}_array.
// Read the comment above.
template <class ELFT> void OutputSection<ELFT>::sortCtorsDtors() {
std::stable_sort(Sections.begin(), Sections.end(), compCtors<ELFT>);
}
static void fill(uint8_t *Buf, size_t Size, ArrayRef<uint8_t> A) {
size_t I = 0;
for (; I + A.size() < Size; I += A.size())
memcpy(Buf + I, A.data(), A.size());
memcpy(Buf + I, A.data(), Size - I);
}
template <class ELFT> void OutputSection<ELFT>::writeTo(uint8_t *Buf) {
ArrayRef<uint8_t> Filler = Script<ELFT>::X->getFiller(this->Name);
if (!Filler.empty())
fill(Buf, this->getSize(), Filler);
if (Config->Threads) {
parallel_for_each(Sections.begin(), Sections.end(),
[=](InputSection<ELFT> *C) { C->writeTo(Buf); });
} else {
for (InputSection<ELFT> *C : Sections)
C->writeTo(Buf);
}
// Linker scripts may have BYTE()-family commands with which you
// can write arbitrary bytes to the output. Process them if any.
Script<ELFT>::X->writeDataBytes(this->Name, Buf);
}
template <class ELFT>
EhOutputSection<ELFT>::EhOutputSection()
: OutputSectionBase<ELFT>(".eh_frame", SHT_PROGBITS, SHF_ALLOC) {}
// Search for an existing CIE record or create a new one.
// CIE records from input object files are uniquified by their contents
// and where their relocations point to.
template <class ELFT>
template <class RelTy>
CieRecord *EhOutputSection<ELFT>::addCie(EhSectionPiece &Piece,
EhInputSection<ELFT> *Sec,
ArrayRef<RelTy> Rels) {
const endianness E = ELFT::TargetEndianness;
if (read32<E>(Piece.data().data() + 4) != 0)
fatal("CIE expected at beginning of .eh_frame: " + Sec->Name);
SymbolBody *Personality = nullptr;
unsigned FirstRelI = Piece.FirstRelocation;
if (FirstRelI != (unsigned)-1)
Personality = &Sec->getFile()->getRelocTargetSym(Rels[FirstRelI]);
// Search for an existing CIE by CIE contents/relocation target pair.
CieRecord *Cie = &CieMap[{Piece.data(), Personality}];
// If not found, create a new one.
if (Cie->Piece == nullptr) {
Cie->Piece = &Piece;
Cies.push_back(Cie);
}
return Cie;
}
// There is one FDE per function. Returns true if a given FDE
// points to a live function.
template <class ELFT>
template <class RelTy>
bool EhOutputSection<ELFT>::isFdeLive(EhSectionPiece &Piece,
EhInputSection<ELFT> *Sec,
ArrayRef<RelTy> Rels) {
unsigned FirstRelI = Piece.FirstRelocation;
if (FirstRelI == (unsigned)-1)
fatal("FDE doesn't reference another section");
const RelTy &Rel = Rels[FirstRelI];
SymbolBody &B = Sec->getFile()->getRelocTargetSym(Rel);
auto *D = dyn_cast<DefinedRegular<ELFT>>(&B);
if (!D || !D->Section)
return false;
InputSectionBase<ELFT> *Target = D->Section->Repl;
return Target && Target->Live;
}
// .eh_frame is a sequence of CIE or FDE records. In general, there
// is one CIE record per input object file which is followed by
// a list of FDEs. This function searches an existing CIE or create a new
// one and associates FDEs to the CIE.
template <class ELFT>
template <class RelTy>
void EhOutputSection<ELFT>::addSectionAux(EhInputSection<ELFT> *Sec,
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, Sec, Rels);
continue;
}
uint32_t CieOffset = Offset + 4 - ID;
CieRecord *Cie = OffsetToCie[CieOffset];
if (!Cie)
fatal("invalid CIE reference");
if (!isFdeLive(Piece, Sec, Rels))
continue;
Cie->FdePieces.push_back(&Piece);
NumFdes++;
}
}
template <class ELFT>
void EhOutputSection<ELFT>::addSection(InputSectionBase<ELFT> *C) {
auto *Sec = cast<EhInputSection<ELFT>>(C);
Sec->OutSec = this;
this->updateAlignment(Sec->Alignment);
Sections.push_back(Sec);
// .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();
if (Sec->Pieces.empty())
return;
if (const Elf_Shdr *RelSec = Sec->RelocSection) {
ELFFile<ELFT> Obj = Sec->getFile()->getObj();
if (RelSec->sh_type == SHT_RELA)
addSectionAux(Sec, check(Obj.relas(RelSec)));
else
addSectionAux(Sec, check(Obj.rels(RelSec)));
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 EhOutputSection<ELFT>::finalize() {
if (this->Header.sh_size)
return; // Already finalized.
size_t Off = 0;
for (CieRecord *Cie : Cies) {
Cie->Piece->OutputOff = Off;
Off += alignTo(Cie->Piece->size(), sizeof(uintX_t));
for (EhSectionPiece *Fde : Cie->FdePieces) {
Fde->OutputOff = Off;
Off += alignTo(Fde->size(), sizeof(uintX_t));
}
}
this->Header.sh_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>
typename ELFT::uint EhOutputSection<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 + this->getVA() + Off;
fatal("unknown FDE size relative encoding");
}
template <class ELFT> void EhOutputSection<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<ELFT> *S : Sections)
S->relocate(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 (Out<ELFT>::EhFrameHdr) {
for (CieRecord *Cie : Cies) {
uint8_t Enc = getFdeEncoding<ELFT>(Cie->Piece->data());
for (SectionPiece *Fde : Cie->FdePieces) {
uintX_t Pc = getFdePc(Buf, Fde->OutputOff, Enc);
uintX_t FdeVA = this->getVA() + Fde->OutputOff;
Out<ELFT>::EhFrameHdr->addFde(Pc, FdeVA);
}
}
}
}
template <class ELFT>
MergeOutputSection<ELFT>::MergeOutputSection(StringRef Name, uint32_t Type,
uintX_t Flags, uintX_t Alignment)
: OutputSectionBase<ELFT>(Name, Type, Flags),
Builder(StringTableBuilder::RAW, Alignment) {}
template <class ELFT> void MergeOutputSection<ELFT>::writeTo(uint8_t *Buf) {
Builder.write(Buf);
}
template <class ELFT>
void MergeOutputSection<ELFT>::addSection(InputSectionBase<ELFT> *C) {
auto *Sec = cast<MergeInputSection<ELFT>>(C);
Sec->OutSec = this;
this->updateAlignment(Sec->Alignment);
this->Header.sh_entsize = Sec->Entsize;
Sections.push_back(Sec);
auto HashI = Sec->Hashes.begin();
for (auto I = Sec->Pieces.begin(), E = Sec->Pieces.end(); I != E; ++I) {
SectionPiece &Piece = *I;
uint32_t Hash = *HashI;
++HashI;
if (!Piece.Live)
continue;
StringRef Data = toStringRef(Sec->getData(I));
CachedHashStringRef V(Data, Hash);
uintX_t OutputOffset = Builder.add(V);
if (!shouldTailMerge())
Piece.OutputOff = OutputOffset;
}
}
template <class ELFT>
unsigned MergeOutputSection<ELFT>::getOffset(CachedHashStringRef Val) {
return Builder.getOffset(Val);
}
template <class ELFT> bool MergeOutputSection<ELFT>::shouldTailMerge() const {
return Config->Optimize >= 2 && this->Header.sh_flags & SHF_STRINGS;
}
template <class ELFT> void MergeOutputSection<ELFT>::finalize() {
if (shouldTailMerge())
Builder.finalize();
else
Builder.finalizeInOrder();
this->Header.sh_size = Builder.getSize();
}
template <class ELFT> void MergeOutputSection<ELFT>::finalizePieces() {
for (MergeInputSection<ELFT> *Sec : Sections)
Sec->finalizePieces();
}
template <class ELFT>
StringTableSection<ELFT>::StringTableSection(StringRef Name, bool Dynamic)
: OutputSectionBase<ELFT>(Name, SHT_STRTAB,
Dynamic ? (uintX_t)SHF_ALLOC : 0),
Dynamic(Dynamic) {
// ELF string tables start with a NUL byte, so 1.
this->setSize(1);
}
// 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.
template <class ELFT>
unsigned StringTableSection<ELFT>::addString(StringRef S, bool HashIt) {
if (HashIt) {
auto R = StringMap.insert(std::make_pair(S, this->getSize()));
if (!R.second)
return R.first->second;
}
unsigned Ret = this->getSize();
this->setSize(this->getSize() + S.size() + 1);
Strings.push_back(S);
return Ret;
}
template <class ELFT> void StringTableSection<ELFT>::writeTo(uint8_t *Buf) {
// ELF string tables start with NUL byte, so advance the pointer by one.
++Buf;
for (StringRef S : Strings) {
memcpy(Buf, S.data(), S.size());
Buf += S.size() + 1;
}
}
template <class ELFT>
typename ELFT::uint DynamicReloc<ELFT>::getOffset() const {
if (OutputSec)
return OutputSec->getVA() + OffsetInSec;
return InputSec->OutSec->getVA() + InputSec->getOffset(OffsetInSec);
}
template <class ELFT>
typename ELFT::uint DynamicReloc<ELFT>::getAddend() const {
if (UseSymVA)
return Sym->getVA<ELFT>(Addend);
return Addend;
}
template <class ELFT> uint32_t DynamicReloc<ELFT>::getSymIndex() const {
if (Sym && !UseSymVA)
return Sym->DynsymIndex;
return 0;
}
template <class ELFT>
SymbolTableSection<ELFT>::SymbolTableSection(
StringTableSection<ELFT> &StrTabSec)
: OutputSectionBase<ELFT>(StrTabSec.isDynamic() ? ".dynsym" : ".symtab",
StrTabSec.isDynamic() ? SHT_DYNSYM : SHT_SYMTAB,
StrTabSec.isDynamic() ? (uintX_t)SHF_ALLOC : 0),
StrTabSec(StrTabSec) {
this->Header.sh_entsize = sizeof(Elf_Sym);
this->Header.sh_addralign = sizeof(uintX_t);
}
// 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 SymbolBody *L, const SymbolBody *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->IsInGlobalMipsGot;
bool RIsInLocalGot = !R->IsInGlobalMipsGot;
if (LIsInLocalGot || RIsInLocalGot)
return !RIsInLocalGot;
return L->GotIndex < R->GotIndex;
}
static uint8_t getSymbolBinding(SymbolBody *Body) {
Symbol *S = Body->symbol();
if (Config->Relocatable)
return S->Binding;
uint8_t Visibility = S->Visibility;
if (Visibility != STV_DEFAULT && Visibility != STV_PROTECTED)
return STB_LOCAL;
if (Config->NoGnuUnique && S->Binding == STB_GNU_UNIQUE)
return STB_GLOBAL;
return S->Binding;
}
template <class ELFT> void SymbolTableSection<ELFT>::finalize() {
if (this->Header.sh_size)
return; // Already finalized.
this->Header.sh_size = getNumSymbols() * sizeof(Elf_Sym);
this->Header.sh_link = StrTabSec.SectionIndex;
this->Header.sh_info = NumLocals + 1;
if (Config->Relocatable) {
size_t I = NumLocals;
for (const SymbolTableEntry &S : Symbols)
S.Symbol->DynsymIndex = ++I;
return;
}
if (!StrTabSec.isDynamic()) {
std::stable_sort(Symbols.begin(), Symbols.end(),
[](const SymbolTableEntry &L, const SymbolTableEntry &R) {
return getSymbolBinding(L.Symbol) == STB_LOCAL &&
getSymbolBinding(R.Symbol) != STB_LOCAL;
});
return;
}
if (Out<ELFT>::GnuHashTab)
// NB: It also sorts Symbols to meet the GNU hash table requirements.
Out<ELFT>::GnuHashTab->addSymbols(Symbols);
else if (Config->EMachine == EM_MIPS)
std::stable_sort(Symbols.begin(), Symbols.end(),
[](const SymbolTableEntry &L, const SymbolTableEntry &R) {
return sortMipsSymbols(L.Symbol, R.Symbol);
});
size_t I = 0;
for (const SymbolTableEntry &S : Symbols)
S.Symbol->DynsymIndex = ++I;
}
template <class ELFT> void SymbolTableSection<ELFT>::addSymbol(SymbolBody *B) {
Symbols.push_back({B, StrTabSec.addString(B->getName(), false)});
}
template <class ELFT> void SymbolTableSection<ELFT>::writeTo(uint8_t *Buf) {
Buf += sizeof(Elf_Sym);
// All symbols with STB_LOCAL binding precede the weak and global symbols.
// .dynsym only contains global symbols.
if (Config->Discard != DiscardPolicy::All && !StrTabSec.isDynamic())
writeLocalSymbols(Buf);
writeGlobalSymbols(Buf);
}
template <class ELFT>
void SymbolTableSection<ELFT>::writeLocalSymbols(uint8_t *&Buf) {
// Iterate over all input object files to copy their local symbols
// to the output symbol table pointed by Buf.
for (ObjectFile<ELFT> *File : Symtab<ELFT>::X->getObjectFiles()) {
for (const std::pair<const DefinedRegular<ELFT> *, size_t> &P :
File->KeptLocalSyms) {
const DefinedRegular<ELFT> &Body = *P.first;
InputSectionBase<ELFT> *Section = Body.Section;
auto *ESym = reinterpret_cast<Elf_Sym *>(Buf);
if (!Section) {
ESym->st_shndx = SHN_ABS;
ESym->st_value = Body.Value;
} else {
const OutputSectionBase<ELFT> *OutSec = Section->OutSec;
ESym->st_shndx = OutSec->SectionIndex;
ESym->st_value = OutSec->getVA() + Section->getOffset(Body);
}
ESym->st_name = P.second;
ESym->st_size = Body.template getSize<ELFT>();
ESym->setBindingAndType(STB_LOCAL, Body.Type);
Buf += sizeof(*ESym);
}
}
}
template <class ELFT>
void SymbolTableSection<ELFT>::writeGlobalSymbols(uint8_t *Buf) {
// Write the internal symbol table contents to the output symbol table
// pointed by Buf.
auto *ESym = reinterpret_cast<Elf_Sym *>(Buf);
for (const SymbolTableEntry &S : Symbols) {
SymbolBody *Body = S.Symbol;
size_t StrOff = S.StrTabOffset;
uint8_t Type = Body->Type;
uintX_t Size = Body->getSize<ELFT>();
ESym->setBindingAndType(getSymbolBinding(Body), Type);
ESym->st_size = Size;
ESym->st_name = StrOff;
ESym->setVisibility(Body->symbol()->Visibility);
ESym->st_value = Body->getVA<ELFT>();
if (const OutputSectionBase<ELFT> *OutSec = getOutputSection(Body))
ESym->st_shndx = OutSec->SectionIndex;
else if (isa<DefinedRegular<ELFT>>(Body))
ESym->st_shndx = SHN_ABS;
if (Config->EMachine == EM_MIPS) {
// 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 (Body->isInPlt() && Body->NeedsCopyOrPltAddr)
ESym->st_other |= STO_MIPS_PLT;
if (Config->Relocatable) {
auto *D = dyn_cast<DefinedRegular<ELFT>>(Body);
if (D && D->isMipsPIC())
ESym->st_other |= STO_MIPS_PIC;
}
}
++ESym;
}
}
template <class ELFT>
const OutputSectionBase<ELFT> *
SymbolTableSection<ELFT>::getOutputSection(SymbolBody *Sym) {
switch (Sym->kind()) {
case SymbolBody::DefinedSyntheticKind:
return cast<DefinedSynthetic<ELFT>>(Sym)->Section;
case SymbolBody::DefinedRegularKind: {
auto &D = cast<DefinedRegular<ELFT>>(*Sym);
if (D.Section)
return D.Section->OutSec;
break;
}
case SymbolBody::DefinedCommonKind:
return In<ELFT>::Common->OutSec;
case SymbolBody::SharedKind:
if (cast<SharedSymbol<ELFT>>(Sym)->needsCopy())
return Out<ELFT>::Bss;
break;
case SymbolBody::UndefinedKind:
case SymbolBody::LazyArchiveKind:
case SymbolBody::LazyObjectKind:
break;
}
return nullptr;
}
template <class ELFT>
VersionDefinitionSection<ELFT>::VersionDefinitionSection()
: OutputSectionBase<ELFT>(".gnu.version_d", SHT_GNU_verdef, SHF_ALLOC) {
this->Header.sh_addralign = sizeof(uint32_t);
}
static StringRef getFileDefName() {
if (!Config->SoName.empty())
return Config->SoName;
return Config->OutputFile;
}
template <class ELFT> void VersionDefinitionSection<ELFT>::finalize() {
FileDefNameOff = Out<ELFT>::DynStrTab->addString(getFileDefName());
for (VersionDefinition &V : Config->VersionDefinitions)
V.NameOff = Out<ELFT>::DynStrTab->addString(V.Name);
this->Header.sh_size =
(sizeof(Elf_Verdef) + sizeof(Elf_Verdaux)) * getVerDefNum();
this->Header.sh_link = Out<ELFT>::DynStrTab->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
this->Header.sh_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>
VersionTableSection<ELFT>::VersionTableSection()
: OutputSectionBase<ELFT>(".gnu.version", SHT_GNU_versym, SHF_ALLOC) {
this->Header.sh_addralign = sizeof(uint16_t);
}
template <class ELFT> void VersionTableSection<ELFT>::finalize() {
this->Header.sh_size =
sizeof(Elf_Versym) * (Out<ELFT>::DynSymTab->getSymbols().size() + 1);
this->Header.sh_entsize = sizeof(Elf_Versym);
// 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.
this->Header.sh_link = Out<ELFT>::DynSymTab->SectionIndex;
}
template <class ELFT> void VersionTableSection<ELFT>::writeTo(uint8_t *Buf) {
auto *OutVersym = reinterpret_cast<Elf_Versym *>(Buf) + 1;
for (const SymbolTableEntry &S : Out<ELFT>::DynSymTab->getSymbols()) {
OutVersym->vs_index = S.Symbol->symbol()->VersionId;
++OutVersym;
}
}
template <class ELFT>
VersionNeedSection<ELFT>::VersionNeedSection()
: OutputSectionBase<ELFT>(".gnu.version_r", SHT_GNU_verneed, SHF_ALLOC) {
this->Header.sh_addralign = sizeof(uint32_t);
// 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<ELFT> *SS) {
if (!SS->Verdef) {
SS->symbol()->VersionId = VER_NDX_GLOBAL;
return;
}
SharedFile<ELFT> *F = 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 (F->VerdefMap.empty())
Needed.push_back({F, Out<ELFT>::DynStrTab->addString(F->getSoName())});
typename SharedFile<ELFT>::NeededVer &NV = F->VerdefMap[SS->Verdef];
// 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 = Out<ELFT>::DynStrTab->addString(
SS->file()->getStringTable().data() + SS->Verdef->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>::finalize() {
this->Header.sh_link = Out<ELFT>::DynStrTab->SectionIndex;
this->Header.sh_info = Needed.size();
unsigned Size = Needed.size() * sizeof(Elf_Verneed);
for (std::pair<SharedFile<ELFT> *, size_t> &P : Needed)
Size += P.first->VerdefMap.size() * sizeof(Elf_Vernaux);
this->Header.sh_size = Size;
}
template <class ELFT>
MipsReginfoOutputSection<ELFT>::MipsReginfoOutputSection()
: OutputSectionBase<ELFT>(".reginfo", SHT_MIPS_REGINFO, SHF_ALLOC) {
this->Header.sh_addralign = 4;
this->Header.sh_entsize = sizeof(Elf_Mips_RegInfo);
this->Header.sh_size = sizeof(Elf_Mips_RegInfo);
}
template <class ELFT>
void MipsReginfoOutputSection<ELFT>::writeTo(uint8_t *Buf) {
auto *R = reinterpret_cast<Elf_Mips_RegInfo *>(Buf);
if (Config->Relocatable)
R->ri_gp_value = 0;
else
R->ri_gp_value = Out<ELFT>::Got->getVA() + MipsGPOffset;
R->ri_gprmask = GprMask;
}
template <class ELFT>
void MipsReginfoOutputSection<ELFT>::addSection(InputSectionBase<ELFT> *C) {
// Copy input object file's .reginfo gprmask to output.
auto *S = cast<MipsReginfoInputSection<ELFT>>(C);
GprMask |= S->Reginfo->ri_gprmask;
S->OutSec = this;
}
template <class ELFT>
MipsOptionsOutputSection<ELFT>::MipsOptionsOutputSection()
: OutputSectionBase<ELFT>(".MIPS.options", SHT_MIPS_OPTIONS,
SHF_ALLOC | SHF_MIPS_NOSTRIP) {
this->Header.sh_addralign = 8;
this->Header.sh_entsize = 1;
this->Header.sh_size = sizeof(Elf_Mips_Options) + sizeof(Elf_Mips_RegInfo);
}
template <class ELFT>
void MipsOptionsOutputSection<ELFT>::writeTo(uint8_t *Buf) {
auto *Opt = reinterpret_cast<Elf_Mips_Options *>(Buf);
Opt->kind = ODK_REGINFO;
Opt->size = this->Header.sh_size;
Opt->section = 0;
Opt->info = 0;
auto *Reg = reinterpret_cast<Elf_Mips_RegInfo *>(Buf + sizeof(*Opt));
if (Config->Relocatable)
Reg->ri_gp_value = 0;
else
Reg->ri_gp_value = Out<ELFT>::Got->getVA() + MipsGPOffset;
Reg->ri_gprmask = GprMask;
}
template <class ELFT>
void MipsOptionsOutputSection<ELFT>::addSection(InputSectionBase<ELFT> *C) {
auto *S = cast<MipsOptionsInputSection<ELFT>>(C);
if (S->Reginfo)
GprMask |= S->Reginfo->ri_gprmask;
S->OutSec = this;
}
template <class ELFT>
MipsAbiFlagsOutputSection<ELFT>::MipsAbiFlagsOutputSection()
: OutputSectionBase<ELFT>(".MIPS.abiflags", SHT_MIPS_ABIFLAGS, SHF_ALLOC) {
this->Header.sh_addralign = 8;
this->Header.sh_entsize = sizeof(Elf_Mips_ABIFlags);
this->Header.sh_size = sizeof(Elf_Mips_ABIFlags);
memset(&Flags, 0, sizeof(Flags));
}
template <class ELFT>
void MipsAbiFlagsOutputSection<ELFT>::writeTo(uint8_t *Buf) {
memcpy(Buf, &Flags, sizeof(Flags));
}
template <class ELFT>
void MipsAbiFlagsOutputSection<ELFT>::addSection(InputSectionBase<ELFT> *C) {
// Check compatibility and merge fields from input .MIPS.abiflags
// to the output one.
auto *S = cast<MipsAbiFlagsInputSection<ELFT>>(C);
S->OutSec = this;
if (S->Flags->version != 0) {
error(getFilename(S->getFile()) + ": unexpected .MIPS.abiflags version " +
Twine(S->Flags->version));
return;
}
// LLD checks ISA compatibility in getMipsEFlags(). Here we just
// select the highest number of ISA/Rev/Ext.
Flags.isa_level = std::max(Flags.isa_level, S->Flags->isa_level);
Flags.isa_rev = std::max(Flags.isa_rev, S->Flags->isa_rev);
Flags.isa_ext = std::max(Flags.isa_ext, S->Flags->isa_ext);
Flags.gpr_size = std::max(Flags.gpr_size, S->Flags->gpr_size);
Flags.cpr1_size = std::max(Flags.cpr1_size, S->Flags->cpr1_size);
Flags.cpr2_size = std::max(Flags.cpr2_size, S->Flags->cpr2_size);
Flags.ases |= S->Flags->ases;
Flags.flags1 |= S->Flags->flags1;
Flags.flags2 |= S->Flags->flags2;
Flags.fp_abi = elf::getMipsFpAbiFlag(Flags.fp_abi, S->Flags->fp_abi,
getFilename(S->getFile()));
}
template <class ELFT>
static typename ELFT::uint getOutFlags(InputSectionBase<ELFT> *S) {
return S->Flags & ~SHF_GROUP & ~SHF_COMPRESSED;
}
template <class ELFT>
static SectionKey<ELFT::Is64Bits> createKey(InputSectionBase<ELFT> *C,
StringRef OutsecName) {
typedef typename ELFT::uint uintX_t;
uintX_t Flags = getOutFlags(C);
// For SHF_MERGE we create different output sections for each alignment.
// This makes each output section simple and keeps a single level mapping from
// input to output.
// In case of relocatable object generation we do not try to perform merging
// and treat SHF_MERGE sections as regular ones, but also create different
// output sections for them to allow merging at final linking stage.
uintX_t Alignment = 0;
if (isa<MergeInputSection<ELFT>>(C) ||
(Config->Relocatable && (C->Flags & SHF_MERGE)))
Alignment = std::max<uintX_t>(C->Alignment, C->Entsize);
return SectionKey<ELFT::Is64Bits>{OutsecName, C->Type, Flags, Alignment};
}
template <class ELFT>
std::pair<OutputSectionBase<ELFT> *, bool>
OutputSectionFactory<ELFT>::create(InputSectionBase<ELFT> *C,
StringRef OutsecName) {
SectionKey<ELFT::Is64Bits> Key = createKey(C, OutsecName);
return create(Key, C);
}
template <class ELFT>
std::pair<OutputSectionBase<ELFT> *, bool>
OutputSectionFactory<ELFT>::create(const SectionKey<ELFT::Is64Bits> &Key,
InputSectionBase<ELFT> *C) {
uintX_t Flags = getOutFlags(C);
OutputSectionBase<ELFT> *&Sec = Map[Key];
if (Sec) {
Sec->updateFlags(Flags);
return {Sec, false};
}
uint32_t Type = C->Type;
switch (C->kind()) {
case InputSectionBase<ELFT>::Regular:
Sec = make<OutputSection<ELFT>>(Key.Name, Type, Flags);
break;
case InputSectionBase<ELFT>::EHFrame:
return {Out<ELFT>::EhFrame, false};
case InputSectionBase<ELFT>::Merge:
Sec = make<MergeOutputSection<ELFT>>(Key.Name, Type, Flags, Key.Alignment);
break;
case InputSectionBase<ELFT>::MipsReginfo:
Sec = make<MipsReginfoOutputSection<ELFT>>();
break;
case InputSectionBase<ELFT>::MipsOptions:
Sec = make<MipsOptionsOutputSection<ELFT>>();
break;
case InputSectionBase<ELFT>::MipsAbiFlags:
Sec = make<MipsAbiFlagsOutputSection<ELFT>>();
break;
}
return {Sec, true};
}
template <bool Is64Bits>
typename lld::elf::SectionKey<Is64Bits>
DenseMapInfo<lld::elf::SectionKey<Is64Bits>>::getEmptyKey() {
return SectionKey<Is64Bits>{DenseMapInfo<StringRef>::getEmptyKey(), 0, 0, 0};
}
template <bool Is64Bits>
typename lld::elf::SectionKey<Is64Bits>
DenseMapInfo<lld::elf::SectionKey<Is64Bits>>::getTombstoneKey() {
return SectionKey<Is64Bits>{DenseMapInfo<StringRef>::getTombstoneKey(), 0, 0,
0};
}
template <bool Is64Bits>
unsigned
DenseMapInfo<lld::elf::SectionKey<Is64Bits>>::getHashValue(const Key &Val) {
return hash_combine(Val.Name, Val.Type, Val.Flags, Val.Alignment);
}
template <bool Is64Bits>
bool DenseMapInfo<lld::elf::SectionKey<Is64Bits>>::isEqual(const Key &LHS,
const Key &RHS) {
return DenseMapInfo<StringRef>::isEqual(LHS.Name, RHS.Name) &&
LHS.Type == RHS.Type && LHS.Flags == RHS.Flags &&
LHS.Alignment == RHS.Alignment;
}
namespace llvm {
template struct DenseMapInfo<SectionKey<true>>;
template struct DenseMapInfo<SectionKey<false>>;
}
namespace lld {
namespace elf {
template class OutputSectionBase<ELF32LE>;
template class OutputSectionBase<ELF32BE>;
template class OutputSectionBase<ELF64LE>;
template class OutputSectionBase<ELF64BE>;
template class EhFrameHeader<ELF32LE>;
template class EhFrameHeader<ELF32BE>;
template class EhFrameHeader<ELF64LE>;
template class EhFrameHeader<ELF64BE>;
template class GotPltSection<ELF32LE>;
template class GotPltSection<ELF32BE>;
template class GotPltSection<ELF64LE>;
template class GotPltSection<ELF64BE>;
template class GotSection<ELF32LE>;
template class GotSection<ELF32BE>;
template class GotSection<ELF64LE>;
template class GotSection<ELF64BE>;
template class PltSection<ELF32LE>;
template class PltSection<ELF32BE>;
template class PltSection<ELF64LE>;
template class PltSection<ELF64BE>;
template class RelocationSection<ELF32LE>;
template class RelocationSection<ELF32BE>;
template class RelocationSection<ELF64LE>;
template class RelocationSection<ELF64BE>;
template class GnuHashTableSection<ELF32LE>;
template class GnuHashTableSection<ELF32BE>;
template class GnuHashTableSection<ELF64LE>;
template class GnuHashTableSection<ELF64BE>;
template class HashTableSection<ELF32LE>;
template class HashTableSection<ELF32BE>;
template class HashTableSection<ELF64LE>;
template class HashTableSection<ELF64BE>;
template class DynamicSection<ELF32LE>;
template class DynamicSection<ELF32BE>;
template class DynamicSection<ELF64LE>;
template class DynamicSection<ELF64BE>;
template class OutputSection<ELF32LE>;
template class OutputSection<ELF32BE>;
template class OutputSection<ELF64LE>;
template class OutputSection<ELF64BE>;
template class EhOutputSection<ELF32LE>;
template class EhOutputSection<ELF32BE>;
template class EhOutputSection<ELF64LE>;
template class EhOutputSection<ELF64BE>;
template class MipsReginfoOutputSection<ELF32LE>;
template class MipsReginfoOutputSection<ELF32BE>;
template class MipsReginfoOutputSection<ELF64LE>;
template class MipsReginfoOutputSection<ELF64BE>;
template class MipsOptionsOutputSection<ELF32LE>;
template class MipsOptionsOutputSection<ELF32BE>;
template class MipsOptionsOutputSection<ELF64LE>;
template class MipsOptionsOutputSection<ELF64BE>;
template class MipsAbiFlagsOutputSection<ELF32LE>;
template class MipsAbiFlagsOutputSection<ELF32BE>;
template class MipsAbiFlagsOutputSection<ELF64LE>;
template class MipsAbiFlagsOutputSection<ELF64BE>;
template class MergeOutputSection<ELF32LE>;
template class MergeOutputSection<ELF32BE>;
template class MergeOutputSection<ELF64LE>;
template class MergeOutputSection<ELF64BE>;
template class StringTableSection<ELF32LE>;
template class StringTableSection<ELF32BE>;
template class StringTableSection<ELF64LE>;
template class StringTableSection<ELF64BE>;
template class SymbolTableSection<ELF32LE>;
template class SymbolTableSection<ELF32BE>;
template class SymbolTableSection<ELF64LE>;
template class SymbolTableSection<ELF64BE>;
template class VersionTableSection<ELF32LE>;
template class VersionTableSection<ELF32BE>;
template class VersionTableSection<ELF64LE>;
template class VersionTableSection<ELF64BE>;
template class VersionNeedSection<ELF32LE>;
template class VersionNeedSection<ELF32BE>;
template class VersionNeedSection<ELF64LE>;
template class VersionNeedSection<ELF64BE>;
template class VersionDefinitionSection<ELF32LE>;
template class VersionDefinitionSection<ELF32BE>;
template class VersionDefinitionSection<ELF64LE>;
template class VersionDefinitionSection<ELF64BE>;
template class GdbIndexSection<ELF32LE>;
template class GdbIndexSection<ELF32BE>;
template class GdbIndexSection<ELF64LE>;
template class GdbIndexSection<ELF64BE>;
template class OutputSectionFactory<ELF32LE>;
template class OutputSectionFactory<ELF32BE>;
template class OutputSectionFactory<ELF64LE>;
template class OutputSectionFactory<ELF64BE>;
}
}
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