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llvm-project/lld/ELF/SyntheticSections.cpp

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//===- SyntheticSections.cpp ----------------------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains linker-synthesized sections. Currently,
// synthetic sections are created either output sections or input sections,
// but we are rewriting code so that all synthetic sections are created as
// input sections.
//
//===----------------------------------------------------------------------===//
#include "SyntheticSections.h"
#include "Config.h"
#include "Error.h"
#include "InputFiles.h"
#include "LinkerScript.h"
#include "Memory.h"
#include "OutputSections.h"
#include "Strings.h"
#include "SymbolTable.h"
#include "Target.h"
#include "Threads.h"
#include "Writer.h"
#include "lld/Config/Version.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/MD5.h"
#include "llvm/Support/RandomNumberGenerator.h"
#include "llvm/Support/SHA1.h"
#include "llvm/Support/xxhash.h"
#include <cstdlib>
using namespace llvm;
using namespace llvm::dwarf;
using namespace llvm::ELF;
using namespace llvm::object;
using namespace llvm::support;
using namespace llvm::support::endian;
using namespace lld;
using namespace lld::elf;
template <class ELFT> static std::vector<DefinedCommon *> getCommonSymbols() {
std::vector<DefinedCommon *> V;
for (Symbol *S : Symtab<ELFT>::X->getSymbols())
if (auto *B = dyn_cast<DefinedCommon>(S->body()))
V.push_back(B);
return V;
}
// Find all common symbols and allocate space for them.
template <class ELFT> InputSection<ELFT> *elf::createCommonSection() {
auto *Ret = make<InputSection<ELFT>>(SHF_ALLOC | SHF_WRITE, SHT_NOBITS, 1,
ArrayRef<uint8_t>(), "COMMON");
Ret->Live = true;
// Sort the common symbols by alignment as an heuristic to pack them better.
std::vector<DefinedCommon *> Syms = getCommonSymbols<ELFT>();
std::stable_sort(Syms.begin(), Syms.end(),
[](const DefinedCommon *A, const DefinedCommon *B) {
return A->Alignment > B->Alignment;
});
// Assign offsets to symbols.
size_t Size = 0;
size_t Alignment = 1;
for (DefinedCommon *Sym : Syms) {
Alignment = std::max<size_t>(Alignment, Sym->Alignment);
Size = alignTo(Size, Sym->Alignment);
// Compute symbol offset relative to beginning of input section.
Sym->Offset = Size;
Size += Sym->Size;
}
Ret->Alignment = Alignment;
Ret->Data = makeArrayRef<uint8_t>(nullptr, Size);
return Ret;
}
// Returns an LLD version string.
static ArrayRef<uint8_t> getVersion() {
// Check LLD_VERSION first for ease of testing.
// You can get consitent output by using the environment variable.
// This is only for testing.
StringRef S = getenv("LLD_VERSION");
if (S.empty())
S = Saver.save(Twine("Linker: ") + getLLDVersion());
// +1 to include the terminating '\0'.
return {(const uint8_t *)S.data(), S.size() + 1};
}
// Creates a .comment section containing LLD version info.
// With this feature, you can identify LLD-generated binaries easily
// by "objdump -s -j .comment <file>".
// The returned object is a mergeable string section.
template <class ELFT> MergeInputSection<ELFT> *elf::createCommentSection() {
typename ELFT::Shdr Hdr = {};
Hdr.sh_flags = SHF_MERGE | SHF_STRINGS;
Hdr.sh_type = SHT_PROGBITS;
Hdr.sh_entsize = 1;
Hdr.sh_addralign = 1;
auto *Ret = make<MergeInputSection<ELFT>>(/*file=*/nullptr, &Hdr, ".comment");
Ret->Data = getVersion();
Ret->splitIntoPieces();
return Ret;
}
// .MIPS.abiflags section.
template <class ELFT>
MipsAbiFlagsSection<ELFT>::MipsAbiFlagsSection(Elf_Mips_ABIFlags Flags)
: SyntheticSection<ELFT>(SHF_ALLOC, SHT_MIPS_ABIFLAGS, 8, ".MIPS.abiflags"),
Flags(Flags) {}
template <class ELFT> void MipsAbiFlagsSection<ELFT>::writeTo(uint8_t *Buf) {
memcpy(Buf, &Flags, sizeof(Flags));
}
template <class ELFT>
MipsAbiFlagsSection<ELFT> *MipsAbiFlagsSection<ELFT>::create() {
Elf_Mips_ABIFlags Flags = {};
bool Create = false;
for (InputSectionBase<ELFT> *Sec : Symtab<ELFT>::X->Sections) {
if (!Sec->Live || Sec->Type != SHT_MIPS_ABIFLAGS)
continue;
Sec->Live = false;
Create = true;
std::string Filename = toString(Sec->getFile());
const size_t Size = Sec->Data.size();
// Older version of BFD (such as the default FreeBSD linker) concatenate
// .MIPS.abiflags instead of merging. To allow for this case (or potential
// zero padding) we ignore everything after the first Elf_Mips_ABIFlags
if (Size < sizeof(Elf_Mips_ABIFlags)) {
error(Filename + ": invalid size of .MIPS.abiflags section: got " +
Twine(Size) + " instead of " + Twine(sizeof(Elf_Mips_ABIFlags)));
return nullptr;
}
auto *S = reinterpret_cast<const Elf_Mips_ABIFlags *>(Sec->Data.data());
if (S->version != 0) {
error(Filename + ": unexpected .MIPS.abiflags version " +
Twine(S->version));
return nullptr;
}
// 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->isa_level);
Flags.isa_rev = std::max(Flags.isa_rev, S->isa_rev);
Flags.isa_ext = std::max(Flags.isa_ext, S->isa_ext);
Flags.gpr_size = std::max(Flags.gpr_size, S->gpr_size);
Flags.cpr1_size = std::max(Flags.cpr1_size, S->cpr1_size);
Flags.cpr2_size = std::max(Flags.cpr2_size, S->cpr2_size);
Flags.ases |= S->ases;
Flags.flags1 |= S->flags1;
Flags.flags2 |= S->flags2;
Flags.fp_abi = elf::getMipsFpAbiFlag(Flags.fp_abi, S->fp_abi, Filename);
};
if (Create)
return make<MipsAbiFlagsSection<ELFT>>(Flags);
return nullptr;
}
// .MIPS.options section.
template <class ELFT>
MipsOptionsSection<ELFT>::MipsOptionsSection(Elf_Mips_RegInfo Reginfo)
: SyntheticSection<ELFT>(SHF_ALLOC, SHT_MIPS_OPTIONS, 8, ".MIPS.options"),
Reginfo(Reginfo) {}
template <class ELFT> void MipsOptionsSection<ELFT>::writeTo(uint8_t *Buf) {
auto *Options = reinterpret_cast<Elf_Mips_Options *>(Buf);
Options->kind = ODK_REGINFO;
Options->size = getSize();
if (!Config->Relocatable)
Reginfo.ri_gp_value = In<ELFT>::MipsGot->getGp();
memcpy(Buf + sizeof(Elf_Mips_Options), &Reginfo, sizeof(Reginfo));
}
template <class ELFT>
MipsOptionsSection<ELFT> *MipsOptionsSection<ELFT>::create() {
// N64 ABI only.
if (!ELFT::Is64Bits)
return nullptr;
Elf_Mips_RegInfo Reginfo = {};
bool Create = false;
for (InputSectionBase<ELFT> *Sec : Symtab<ELFT>::X->Sections) {
if (!Sec->Live || Sec->Type != SHT_MIPS_OPTIONS)
continue;
Sec->Live = false;
Create = true;
std::string Filename = toString(Sec->getFile());
ArrayRef<uint8_t> D = Sec->Data;
while (!D.empty()) {
if (D.size() < sizeof(Elf_Mips_Options)) {
error(Filename + ": invalid size of .MIPS.options section");
break;
}
auto *Opt = reinterpret_cast<const Elf_Mips_Options *>(D.data());
if (Opt->kind == ODK_REGINFO) {
if (Config->Relocatable && Opt->getRegInfo().ri_gp_value)
error(Filename + ": unsupported non-zero ri_gp_value");
Reginfo.ri_gprmask |= Opt->getRegInfo().ri_gprmask;
Sec->getFile()->MipsGp0 = Opt->getRegInfo().ri_gp_value;
break;
}
if (!Opt->size)
fatal(Filename + ": zero option descriptor size");
D = D.slice(Opt->size);
}
};
if (Create)
return make<MipsOptionsSection<ELFT>>(Reginfo);
return nullptr;
}
// MIPS .reginfo section.
template <class ELFT>
MipsReginfoSection<ELFT>::MipsReginfoSection(Elf_Mips_RegInfo Reginfo)
: SyntheticSection<ELFT>(SHF_ALLOC, SHT_MIPS_REGINFO, 4, ".reginfo"),
Reginfo(Reginfo) {}
template <class ELFT> void MipsReginfoSection<ELFT>::writeTo(uint8_t *Buf) {
if (!Config->Relocatable)
Reginfo.ri_gp_value = In<ELFT>::MipsGot->getGp();
memcpy(Buf, &Reginfo, sizeof(Reginfo));
}
template <class ELFT>
MipsReginfoSection<ELFT> *MipsReginfoSection<ELFT>::create() {
// Section should be alive for O32 and N32 ABIs only.
if (ELFT::Is64Bits)
return nullptr;
Elf_Mips_RegInfo Reginfo = {};
bool Create = false;
for (InputSectionBase<ELFT> *Sec : Symtab<ELFT>::X->Sections) {
if (!Sec->Live || Sec->Type != SHT_MIPS_REGINFO)
continue;
Sec->Live = false;
Create = true;
if (Sec->Data.size() != sizeof(Elf_Mips_RegInfo)) {
error(toString(Sec->getFile()) + ": invalid size of .reginfo section");
return nullptr;
}
auto *R = reinterpret_cast<const Elf_Mips_RegInfo *>(Sec->Data.data());
if (Config->Relocatable && R->ri_gp_value)
error(toString(Sec->getFile()) + ": unsupported non-zero ri_gp_value");
Reginfo.ri_gprmask |= R->ri_gprmask;
Sec->getFile()->MipsGp0 = R->ri_gp_value;
};
if (Create)
return make<MipsReginfoSection<ELFT>>(Reginfo);
return nullptr;
}
template <class ELFT> InputSection<ELFT> *elf::createInterpSection() {
auto *Ret = make<InputSection<ELFT>>(SHF_ALLOC, SHT_PROGBITS, 1,
ArrayRef<uint8_t>(), ".interp");
Ret->Live = true;
// StringSaver guarantees that the returned string ends with '\0'.
StringRef S = Saver.save(Config->DynamicLinker);
Ret->Data = {(const uint8_t *)S.data(), S.size() + 1};
return Ret;
}
static size_t getHashSize() {
switch (Config->BuildId) {
case BuildIdKind::Fast:
return 8;
case BuildIdKind::Md5:
case BuildIdKind::Uuid:
return 16;
case BuildIdKind::Sha1:
return 20;
case BuildIdKind::Hexstring:
return Config->BuildIdVector.size();
default:
llvm_unreachable("unknown BuildIdKind");
}
}
template <class ELFT>
BuildIdSection<ELFT>::BuildIdSection()
: SyntheticSection<ELFT>(SHF_ALLOC, SHT_NOTE, 1, ".note.gnu.build-id"),
HashSize(getHashSize()) {}
template <class ELFT> void BuildIdSection<ELFT>::writeTo(uint8_t *Buf) {
const endianness E = ELFT::TargetEndianness;
write32<E>(Buf, 4); // Name size
write32<E>(Buf + 4, HashSize); // Content size
write32<E>(Buf + 8, NT_GNU_BUILD_ID); // Type
memcpy(Buf + 12, "GNU", 4); // Name string
HashBuf = Buf + 16;
}
// Split one uint8 array into small pieces of uint8 arrays.
static std::vector<ArrayRef<uint8_t>> split(ArrayRef<uint8_t> Arr,
size_t ChunkSize) {
std::vector<ArrayRef<uint8_t>> Ret;
while (Arr.size() > ChunkSize) {
Ret.push_back(Arr.take_front(ChunkSize));
Arr = Arr.drop_front(ChunkSize);
}
if (!Arr.empty())
Ret.push_back(Arr);
return Ret;
}
// Computes a hash value of Data using a given hash function.
// In order to utilize multiple cores, we first split data into 1MB
// chunks, compute a hash for each chunk, and then compute a hash value
// of the hash values.
template <class ELFT>
void BuildIdSection<ELFT>::computeHash(
llvm::ArrayRef<uint8_t> Data,
std::function<void(uint8_t *Dest, ArrayRef<uint8_t> Arr)> HashFn) {
std::vector<ArrayRef<uint8_t>> Chunks = split(Data, 1024 * 1024);
std::vector<uint8_t> Hashes(Chunks.size() * HashSize);
// Compute hash values.
forLoop(0, Chunks.size(),
[&](size_t I) { HashFn(Hashes.data() + I * HashSize, Chunks[I]); });
// Write to the final output buffer.
HashFn(HashBuf, Hashes);
}
template <class ELFT>
void BuildIdSection<ELFT>::writeBuildId(ArrayRef<uint8_t> Buf) {
switch (Config->BuildId) {
case BuildIdKind::Fast:
computeHash(Buf, [](uint8_t *Dest, ArrayRef<uint8_t> Arr) {
write64le(Dest, xxHash64(toStringRef(Arr)));
});
break;
case BuildIdKind::Md5:
computeHash(Buf, [](uint8_t *Dest, ArrayRef<uint8_t> Arr) {
memcpy(Dest, MD5::hash(Arr).data(), 16);
});
break;
case BuildIdKind::Sha1:
computeHash(Buf, [](uint8_t *Dest, ArrayRef<uint8_t> Arr) {
memcpy(Dest, SHA1::hash(Arr).data(), 20);
});
break;
case BuildIdKind::Uuid:
if (getRandomBytes(HashBuf, HashSize))
error("entropy source failure");
break;
case BuildIdKind::Hexstring:
memcpy(HashBuf, Config->BuildIdVector.data(), Config->BuildIdVector.size());
break;
default:
llvm_unreachable("unknown BuildIdKind");
}
}
template <class ELFT>
GotSection<ELFT>::GotSection()
: SyntheticSection<ELFT>(SHF_ALLOC | SHF_WRITE, SHT_PROGBITS,
Target->GotEntrySize, ".got") {}
template <class ELFT> void GotSection<ELFT>::addEntry(SymbolBody &Sym) {
Sym.GotIndex = NumEntries;
++NumEntries;
}
template <class ELFT> bool GotSection<ELFT>::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.
template <class ELFT> bool GotSection<ELFT>::addTlsIndex() {
if (TlsIndexOff != uint32_t(-1))
return false;
TlsIndexOff = NumEntries * sizeof(uintX_t);
NumEntries += 2;
return true;
}
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> void GotSection<ELFT>::finalize() {
Size = NumEntries * sizeof(uintX_t);
}
template <class ELFT> bool GotSection<ELFT>::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;
}
template <class ELFT> void GotSection<ELFT>::writeTo(uint8_t *Buf) {
this->relocate(Buf, Buf + Size);
}
template <class ELFT>
MipsGotSection<ELFT>::MipsGotSection()
: SyntheticSection<ELFT>(SHF_ALLOC | SHF_WRITE | SHF_MIPS_GPREL,
SHT_PROGBITS, Target->GotEntrySize, ".got") {}
template <class ELFT>
void MipsGotSection<ELFT>::addEntry(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.
PageIndexMap.insert({cast<DefinedRegular<ELFT>>(&Sym)->Section->OutSec, 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, uintX_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);
}
}
template <class ELFT>
bool MipsGotSection<ELFT>::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.
template <class ELFT> bool MipsGotSection<ELFT>::addTlsIndex() {
if (TlsIndexOff != uint32_t(-1))
return false;
TlsIndexOff = TlsEntries.size() * sizeof(uintX_t);
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;
}
template <class ELFT>
typename MipsGotSection<ELFT>::uintX_t
MipsGotSection<ELFT>::getPageEntryOffset(const SymbolBody &B,
uintX_t Addend) const {
const OutputSectionBase *OutSec =
cast<DefinedRegular<ELFT>>(&B)->Section->OutSec;
uintX_t SecAddr = getMipsPageAddr(OutSec->Addr);
uintX_t SymAddr = getMipsPageAddr(B.getVA<ELFT>(Addend));
uintX_t Index = PageIndexMap.lookup(OutSec) + (SymAddr - SecAddr) / 0xffff;
assert(Index < PageEntriesNum);
return (HeaderEntriesNum + Index) * sizeof(uintX_t);
}
template <class ELFT>
typename MipsGotSection<ELFT>::uintX_t
MipsGotSection<ELFT>::getBodyEntryOffset(const SymbolBody &B,
uintX_t Addend) const {
// Calculate offset of the GOT entries block: TLS, global, local.
uintX_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 * sizeof(uintX_t);
}
template <class ELFT>
typename MipsGotSection<ELFT>::uintX_t
MipsGotSection<ELFT>::getTlsOffset() const {
return (getLocalEntriesNum() + GlobalEntries.size()) * sizeof(uintX_t);
}
template <class ELFT>
typename MipsGotSection<ELFT>::uintX_t
MipsGotSection<ELFT>::getGlobalDynOffset(const SymbolBody &B) const {
return B.GlobalDynIndex * sizeof(uintX_t);
}
template <class ELFT>
const SymbolBody *MipsGotSection<ELFT>::getFirstGlobalEntry() const {
return GlobalEntries.empty() ? nullptr : GlobalEntries.front().first;
}
template <class ELFT>
unsigned MipsGotSection<ELFT>::getLocalEntriesNum() const {
return HeaderEntriesNum + PageEntriesNum + LocalEntries.size() +
LocalEntries32.size();
}
template <class ELFT> void MipsGotSection<ELFT>::finalize() {
PageEntriesNum = 0;
for (std::pair<const OutputSectionBase *, 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()) *
sizeof(uintX_t);
}
template <class ELFT> bool MipsGotSection<ELFT>::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;
}
template <class ELFT>
typename MipsGotSection<ELFT>::uintX_t MipsGotSection<ELFT>::getGp() const {
return ElfSym<ELFT>::MipsGp->template getVA<ELFT>(0);
}
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 MipsGotSection<ELFT>::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.
auto *P = reinterpret_cast<typename ELFT::Off *>(Buf);
P[1] = uintX_t(1) << (ELFT::Is64Bits ? 63 : 31);
Buf += HeaderEntriesNum * sizeof(uintX_t);
// Write 'page address' entries to the local part of the GOT.
for (std::pair<const OutputSectionBase *, size_t> &L : PageIndexMap) {
size_t PageCount = getMipsPageCount(L.first->Size);
uintX_t FirstPageAddr = getMipsPageAddr(L.first->Addr);
for (size_t PI = 0; PI < PageCount; ++PI) {
uint8_t *Entry = Buf + (L.second + PI) * sizeof(uintX_t);
writeUint<ELFT>(Entry, FirstPageAddr + PI * 0x10000);
}
}
Buf += PageEntriesNum * sizeof(uintX_t);
auto AddEntry = [&](const GotEntry &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(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<ELFT>(Buf + TlsIndexOff, 1);
for (const SymbolBody *B : TlsEntries) {
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>
GotPltSection<ELFT>::GotPltSection()
: SyntheticSection<ELFT>(SHF_ALLOC | SHF_WRITE, SHT_PROGBITS,
Target->GotPltEntrySize, ".got.plt") {}
template <class ELFT> void GotPltSection<ELFT>::addEntry(SymbolBody &Sym) {
Sym.GotPltIndex = Target->GotPltHeaderEntriesNum + Entries.size();
Entries.push_back(&Sym);
}
template <class ELFT> size_t GotPltSection<ELFT>::getSize() const {
return (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);
}
}
// On ARM the IgotPltSection is part of the GotSection, on other Targets it is
// part of the .got.plt
template <class ELFT>
IgotPltSection<ELFT>::IgotPltSection()
: SyntheticSection<ELFT>(SHF_ALLOC | SHF_WRITE, SHT_PROGBITS,
Target->GotPltEntrySize,
Config->EMachine == EM_ARM ? ".got" : ".got.plt") {
}
template <class ELFT> void IgotPltSection<ELFT>::addEntry(SymbolBody &Sym) {
Sym.IsInIgot = true;
Sym.GotPltIndex = Entries.size();
Entries.push_back(&Sym);
}
template <class ELFT> size_t IgotPltSection<ELFT>::getSize() const {
return Entries.size() * Target->GotPltEntrySize;
}
template <class ELFT> void IgotPltSection<ELFT>::writeTo(uint8_t *Buf) {
for (const SymbolBody *B : Entries) {
Target->writeIgotPlt(Buf, *B);
Buf += sizeof(uintX_t);
}
}
template <class ELFT>
StringTableSection<ELFT>::StringTableSection(StringRef Name, bool Dynamic)
: SyntheticSection<ELFT>(Dynamic ? (uintX_t)SHF_ALLOC : 0, SHT_STRTAB, 1,
Name),
Dynamic(Dynamic) {}
// 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->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;
}
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;
}
}
// 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<ELFT>(SHF_ALLOC | SHF_WRITE, SHT_DYNAMIC,
sizeof(uintX_t), ".dynamic") {
this->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)
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, In<ELFT>::DynStrTab->addString(S)});
if (!Config->RPath.empty())
add({Config->EnableNewDtags ? DT_RUNPATH : DT_RPATH,
In<ELFT>::DynStrTab->addString(Config->RPath)});
for (SharedFile<ELFT> *F : Symtab<ELFT>::X->getSharedFiles())
if (F->isNeeded())
add({DT_NEEDED, In<ELFT>::DynStrTab->addString(F->getSoName())});
if (!Config->SoName.empty())
add({DT_SONAME, In<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->Shared && !Config->Relocatable)
add({DT_DEBUG, (uint64_t)0});
}
// Add remaining entries to complete .dynamic contents.
template <class ELFT> void DynamicSection<ELFT>::finalize() {
if (this->Size)
return; // Already finalized.
this->Link = In<ELFT>::DynStrTab->OutSec->SectionIndex;
if (In<ELFT>::RelaDyn->OutSec->Size > 0) {
bool IsRela = Config->Rela;
add({IsRela ? DT_RELA : DT_REL, In<ELFT>::RelaDyn});
add({IsRela ? DT_RELASZ : DT_RELSZ, In<ELFT>::RelaDyn->OutSec->Size});
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 = In<ELFT>::RelaDyn->getRelativeRelocCount();
if (Config->ZCombreloc && NumRelativeRels)
add({IsRela ? DT_RELACOUNT : DT_RELCOUNT, NumRelativeRels});
}
}
if (In<ELFT>::RelaPlt->OutSec->Size > 0) {
add({DT_JMPREL, In<ELFT>::RelaPlt});
add({DT_PLTRELSZ, In<ELFT>::RelaPlt->OutSec->Size});
add({Config->EMachine == EM_MIPS ? DT_MIPS_PLTGOT : DT_PLTGOT,
In<ELFT>::GotPlt});
add({DT_PLTREL, uint64_t(Config->Rela ? DT_RELA : DT_REL)});
}
add({DT_SYMTAB, In<ELFT>::DynSymTab});
add({DT_SYMENT, sizeof(Elf_Sym)});
add({DT_STRTAB, In<ELFT>::DynStrTab});
add({DT_STRSZ, In<ELFT>::DynStrTab->getSize()});
if (In<ELFT>::GnuHashTab)
add({DT_GNU_HASH, In<ELFT>::GnuHashTab});
if (In<ELFT>::HashTab)
add({DT_HASH, In<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 = 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, In<ELFT>::DynSymTab->getNumSymbols()});
add({DT_MIPS_LOCAL_GOTNO, In<ELFT>::MipsGot->getLocalEntriesNum()});
if (const SymbolBody *B = In<ELFT>::MipsGot->getFirstGlobalEntry())
add({DT_MIPS_GOTSYM, B->DynsymIndex});
else
add({DT_MIPS_GOTSYM, In<ELFT>::DynSymTab->getNumSymbols()});
add({DT_PLTGOT, In<ELFT>::MipsGot});
if (In<ELFT>::MipsRldMap)
add({DT_MIPS_RLD_MAP, In<ELFT>::MipsRldMap});
}
this->OutSec->Entsize = this->Entsize;
this->OutSec->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->OutSec->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->template getVA<ELFT>();
break;
case Entry::PlainInt:
P->d_un.d_val = E.Val;
break;
}
++P;
}
}
template <class ELFT>
typename ELFT::uint DynamicReloc<ELFT>::getOffset() const {
if (OutputSec)
return OutputSec->Addr + OffsetInSec;
return InputSec->OutSec->Addr + 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>
RelocationSection<ELFT>::RelocationSection(StringRef Name, bool Sort)
: SyntheticSection<ELFT>(SHF_ALLOC, Config->Rela ? SHT_RELA : SHT_REL,
sizeof(uintX_t), Name),
Sort(Sort) {
this->Entsize = Config->Rela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
}
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.getInputSec() == In<ELFT>::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 += In<ELFT>::MipsGot->getTlsOffset();
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->Entsize * Relocs.size();
}
template <class ELFT> void RelocationSection<ELFT>::finalize() {
this->Link = In<ELFT>::DynSymTab ? In<ELFT>::DynSymTab->OutSec->SectionIndex
: In<ELFT>::SymTab->OutSec->SectionIndex;
// Set required output section properties.
this->OutSec->Link = this->Link;
this->OutSec->Entsize = this->Entsize;
}
template <class ELFT>
SymbolTableSection<ELFT>::SymbolTableSection(
StringTableSection<ELFT> &StrTabSec)
: SyntheticSection<ELFT>(StrTabSec.isDynamic() ? (uintX_t)SHF_ALLOC : 0,
StrTabSec.isDynamic() ? SHT_DYNSYM : SHT_SYMTAB,
sizeof(uintX_t),
StrTabSec.isDynamic() ? ".dynsym" : ".symtab"),
StrTabSec(StrTabSec) {
this->Entsize = sizeof(Elf_Sym);
}
// 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() {
this->OutSec->Link = this->Link = StrTabSec.OutSec->SectionIndex;
this->OutSec->Info = this->Info = NumLocals + 1;
this->OutSec->Entsize = this->Entsize;
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 (In<ELFT>::GnuHashTab)
// NB: It also sorts Symbols to meet the GNU hash table requirements.
In<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 *OutSec = Section->OutSec;
ESym->st_shndx = OutSec->SectionIndex;
ESym->st_value = OutSec->Addr + 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 *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 *
SymbolTableSection<ELFT>::getOutputSection(SymbolBody *Sym) {
switch (Sym->kind()) {
case SymbolBody::DefinedSyntheticKind:
return cast<DefinedSynthetic>(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>
GnuHashTableSection<ELFT>::GnuHashTableSection()
: SyntheticSection<ELFT>(SHF_ALLOC, SHT_GNU_HASH, sizeof(uintX_t),
".gnu.hash") {
this->Entsize = ELFT::Is64Bits ? 0 : 4;
}
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->OutSec->Entsize = this->Entsize;
this->OutSec->Link = this->Link = In<ELFT>::DynSymTab->OutSec->SectionIndex;
this->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++ = In<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;
}
static uint32_t hashGnu(StringRef Name) {
uint32_t H = 5381;
for (uint8_t C : Name)
H = (H << 5) + H + C;
return H;
}
// 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});
}
template <class ELFT>
HashTableSection<ELFT>::HashTableSection()
: SyntheticSection<ELFT>(SHF_ALLOC, SHT_HASH, sizeof(Elf_Word), ".hash") {
this->Entsize = sizeof(Elf_Word);
}
template <class ELFT> void HashTableSection<ELFT>::finalize() {
this->OutSec->Link = this->Link = In<ELFT>::DynSymTab->OutSec->SectionIndex;
this->OutSec->Entsize = this->Entsize;
unsigned NumEntries = 2; // nbucket and nchain.
NumEntries += In<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 += In<ELFT>::DynSymTab->getNumSymbols();
this->Size = NumEntries * sizeof(Elf_Word);
}
template <class ELFT> void HashTableSection<ELFT>::writeTo(uint8_t *Buf) {
unsigned NumSymbols = In<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 : In<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;
}
}
template <class ELFT>
PltSection<ELFT>::PltSection()
: SyntheticSection<ELFT>(SHF_ALLOC | SHF_EXECINSTR, SHT_PROGBITS, 16,
".plt") {}
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 = In<ELFT>::RelaPlt->getRelocOffset();
Entries.push_back(std::make_pair(&Sym, RelOff));
}
template <class ELFT> size_t PltSection<ELFT>::getSize() const {
return Target->PltHeaderSize + Entries.size() * Target->PltEntrySize;
}
template <class ELFT>
IpltSection<ELFT>::IpltSection()
: SyntheticSection<ELFT>(SHF_ALLOC | SHF_EXECINSTR, SHT_PROGBITS, 16,
".plt") {}
template <class ELFT> void IpltSection<ELFT>::writeTo(uint8_t *Buf) {
// The IRelative relocations do not support lazy binding so no header is
// needed
size_t Off = 0;
for (auto &I : Entries) {
const SymbolBody *B = I.first;
unsigned RelOff = I.second + In<ELFT>::Plt->getSize();
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 IpltSection<ELFT>::addEntry(SymbolBody &Sym) {
Sym.PltIndex = Entries.size();
Sym.IsInIplt = true;
unsigned RelOff = In<ELFT>::RelaIplt->getRelocOffset();
Entries.push_back(std::make_pair(&Sym, RelOff));
}
template <class ELFT> size_t IpltSection<ELFT>::getSize() const {
return Entries.size() * Target->PltEntrySize;
}
template <class ELFT>
GdbIndexSection<ELFT>::GdbIndexSection()
: SyntheticSection<ELFT>(0, SHT_PROGBITS, 1, ".gdb_index"),
StringPool(llvm::StringTableBuilder::ELF) {}
template <class ELFT> void GdbIndexSection<ELFT>::parseDebugSections() {
for (InputSectionBase<ELFT> *S : Symtab<ELFT>::X->Sections)
if (InputSection<ELFT> *IS = dyn_cast<InputSection<ELFT>>(S))
if (IS->OutSec && IS->Name == ".debug_info")
readDwarf(IS);
}
// 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;
}
template <class ELFT>
void GdbIndexSection<ELFT>::readDwarf(InputSection<ELFT> *I) {
GdbIndexBuilder<ELFT> Builder(I);
if (ErrorCount)
return;
size_t CuId = CompilationUnits.size();
std::vector<std::pair<uintX_t, uintX_t>> CuList = Builder.readCUList();
CompilationUnits.insert(CompilationUnits.end(), CuList.begin(), CuList.end());
std::vector<AddressEntry<ELFT>> AddrArea = Builder.readAddressArea(CuId);
AddressArea.insert(AddressArea.end(), AddrArea.begin(), AddrArea.end());
std::vector<std::pair<StringRef, uint8_t>> NamesAndTypes =
Builder.readPubNamesAndTypes();
for (std::pair<StringRef, uint8_t> &Pair : NamesAndTypes) {
uint32_t Hash = hash(Pair.first);
size_t Offset = StringPool.add(Pair.first);
bool IsNew;
GdbSymbol *Sym;
std::tie(IsNew, Sym) = SymbolTable.add(Hash, Offset);
if (IsNew) {
Sym->CuVectorIndex = CuVectors.size();
CuVectors.push_back({{CuId, Pair.second}});
continue;
}
std::vector<std::pair<uint32_t, uint8_t>> &CuVec =
CuVectors[Sym->CuVectorIndex];
CuVec.push_back({CuId, Pair.second});
}
}
template <class ELFT> void GdbIndexSection<ELFT>::finalize() {
if (Finalized)
return;
Finalized = true;
parseDebugSections();
// GdbIndex header consist from version fields
// and 5 more fields with different kinds of offsets.
CuTypesOffset = CuListOffset + CompilationUnits.size() * CompilationUnitSize;
SymTabOffset = CuTypesOffset + AddressArea.size() * AddressEntrySize;
ConstantPoolOffset =
SymTabOffset + SymbolTable.getCapacity() * SymTabEntrySize;
for (std::vector<std::pair<uint32_t, uint8_t>> &CuVec : CuVectors) {
CuVectorsOffset.push_back(CuVectorsSize);
CuVectorsSize += OffsetTypeSize * (CuVec.size() + 1);
}
StringPoolOffset = ConstantPoolOffset + CuVectorsSize;
StringPool.finalizeInOrder();
}
template <class ELFT> size_t GdbIndexSection<ELFT>::getSize() const {
const_cast<GdbIndexSection<ELFT> *>(this)->finalize();
return StringPoolOffset + StringPool.getSize();
}
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, SymTabOffset); // Symbol table offset.
write32le(Buf + 20, ConstantPoolOffset); // 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;
}
// Write the address area.
for (AddressEntry<ELFT> &E : AddressArea) {
uintX_t BaseAddr = E.Section->OutSec->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::vector<std::pair<uint32_t, uint8_t>> &CuVec : CuVectors) {
write32le(Buf, CuVec.size());
Buf += 4;
for (std::pair<uint32_t, uint8_t> &P : CuVec) {
uint32_t Index = P.first;
uint8_t Flags = P.second;
Index |= Flags << 24;
write32le(Buf, Index);
Buf += 4;
}
}
StringPool.write(Buf);
}
template <class ELFT> bool GdbIndexSection<ELFT>::empty() const {
return !Out<ELFT>::DebugInfo;
}
template <class ELFT>
EhFrameHeader<ELFT>::EhFrameHeader()
: SyntheticSection<ELFT>(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, Out<ELFT>::EhFrame->Addr - 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> size_t EhFrameHeader<ELFT>::getSize() const {
// .eh_frame_hdr has a 12 bytes header followed by an array of FDEs.
return 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> bool EhFrameHeader<ELFT>::empty() const {
return Out<ELFT>::EhFrame->empty();
}
template <class ELFT>
VersionDefinitionSection<ELFT>::VersionDefinitionSection()
: SyntheticSection<ELFT>(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>::finalize() {
FileDefNameOff = In<ELFT>::DynStrTab->addString(getFileDefName());
for (VersionDefinition &V : Config->VersionDefinitions)
V.NameOff = In<ELFT>::DynStrTab->addString(V.Name);
this->OutSec->Link = this->Link = In<ELFT>::DynStrTab->OutSec->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->OutSec->Info = this->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<ELFT>(SHF_ALLOC, SHT_GNU_versym, sizeof(uint16_t),
".gnu.version") {}
template <class ELFT> void VersionTableSection<ELFT>::finalize() {
this->OutSec->Entsize = this->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->OutSec->Link = this->Link = In<ELFT>::DynSymTab->OutSec->SectionIndex;
}
template <class ELFT> size_t VersionTableSection<ELFT>::getSize() const {
return sizeof(Elf_Versym) * (In<ELFT>::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 : In<ELFT>::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<ELFT>(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<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, In<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 = In<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->OutSec->Link = this->Link = In<ELFT>::DynStrTab->OutSec->SectionIndex;
this->OutSec->Info = this->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;
}
template <class ELFT>
MipsRldMapSection<ELFT>::MipsRldMapSection()
: SyntheticSection<ELFT>(SHF_ALLOC | SHF_WRITE, SHT_PROGBITS,
sizeof(typename ELFT::uint), ".rld_map") {}
template <class ELFT> void MipsRldMapSection<ELFT>::writeTo(uint8_t *Buf) {
// Apply filler from linker script.
uint64_t Filler = Script<ELFT>::X->getFiller(this->Name);
Filler = (Filler << 32) | Filler;
memcpy(Buf, &Filler, getSize());
}
template <class ELFT>
ARMExidxSentinelSection<ELFT>::ARMExidxSentinelSection()
: SyntheticSection<ELFT>(SHF_ALLOC | SHF_LINK_ORDER, SHT_ARM_EXIDX,
sizeof(typename ELFT::uint), ".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 |
template <class ELFT>
void ARMExidxSentinelSection<ELFT>::writeTo(uint8_t *Buf) {
// Get the InputSection before us, we are by definition last
auto RI = cast<OutputSection<ELFT>>(this->OutSec)->Sections.rbegin();
InputSection<ELFT> *LE = *(++RI);
InputSection<ELFT> *LC = cast<InputSection<ELFT>>(LE->getLinkOrderDep());
uint64_t S = LC->OutSec->Addr + LC->getOffset(LC->getSize());
uint64_t P = this->getVA();
Target->relocateOne(Buf, R_ARM_PREL31, S - P);
write32le(Buf + 4, 0x1);
}
template InputSection<ELF32LE> *elf::createCommonSection();
template InputSection<ELF32BE> *elf::createCommonSection();
template InputSection<ELF64LE> *elf::createCommonSection();
template InputSection<ELF64BE> *elf::createCommonSection();
template InputSection<ELF32LE> *elf::createInterpSection();
template InputSection<ELF32BE> *elf::createInterpSection();
template InputSection<ELF64LE> *elf::createInterpSection();
template InputSection<ELF64BE> *elf::createInterpSection();
template MergeInputSection<ELF32LE> *elf::createCommentSection();
template MergeInputSection<ELF32BE> *elf::createCommentSection();
template MergeInputSection<ELF64LE> *elf::createCommentSection();
template MergeInputSection<ELF64BE> *elf::createCommentSection();
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::BuildIdSection<ELF32LE>;
template class elf::BuildIdSection<ELF32BE>;
template class elf::BuildIdSection<ELF64LE>;
template class elf::BuildIdSection<ELF64BE>;
template class elf::GotSection<ELF32LE>;
template class elf::GotSection<ELF32BE>;
template class elf::GotSection<ELF64LE>;
template class elf::GotSection<ELF64BE>;
template class elf::MipsGotSection<ELF32LE>;
template class elf::MipsGotSection<ELF32BE>;
template class elf::MipsGotSection<ELF64LE>;
template class elf::MipsGotSection<ELF64BE>;
template class elf::GotPltSection<ELF32LE>;
template class elf::GotPltSection<ELF32BE>;
template class elf::GotPltSection<ELF64LE>;
template class elf::GotPltSection<ELF64BE>;
template class elf::IgotPltSection<ELF32LE>;
template class elf::IgotPltSection<ELF32BE>;
template class elf::IgotPltSection<ELF64LE>;
template class elf::IgotPltSection<ELF64BE>;
template class elf::StringTableSection<ELF32LE>;
template class elf::StringTableSection<ELF32BE>;
template class elf::StringTableSection<ELF64LE>;
template class elf::StringTableSection<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::GnuHashTableSection<ELF32LE>;
template class elf::GnuHashTableSection<ELF32BE>;
template class elf::GnuHashTableSection<ELF64LE>;
template class elf::GnuHashTableSection<ELF64BE>;
template class elf::HashTableSection<ELF32LE>;
template class elf::HashTableSection<ELF32BE>;
template class elf::HashTableSection<ELF64LE>;
template class elf::HashTableSection<ELF64BE>;
template class elf::PltSection<ELF32LE>;
template class elf::PltSection<ELF32BE>;
template class elf::PltSection<ELF64LE>;
template class elf::PltSection<ELF64BE>;
template class elf::IpltSection<ELF32LE>;
template class elf::IpltSection<ELF32BE>;
template class elf::IpltSection<ELF64LE>;
template class elf::IpltSection<ELF64BE>;
template class elf::GdbIndexSection<ELF32LE>;
template class elf::GdbIndexSection<ELF32BE>;
template class elf::GdbIndexSection<ELF64LE>;
template class elf::GdbIndexSection<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::MipsRldMapSection<ELF32LE>;
template class elf::MipsRldMapSection<ELF32BE>;
template class elf::MipsRldMapSection<ELF64LE>;
template class elf::MipsRldMapSection<ELF64BE>;
template class elf::ARMExidxSentinelSection<ELF32LE>;
template class elf::ARMExidxSentinelSection<ELF32BE>;
template class elf::ARMExidxSentinelSection<ELF64LE>;
template class elf::ARMExidxSentinelSection<ELF64BE>;
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