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[ELF] Convert .got.plt section to input section 

Differential revision: https://reviews.llvm.org/D26349

llvm-svn: 286443
This commit is contained in:
Eugene Leviant 2016-11-10 09:48:29 +00:00
parent d0b9173caa
commit 41ca327b5e
11 changed files with 123 additions and 77 deletions
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17
lld/ELF/InputSection.cpp
View File

@ -14,6 +14,7 @@
#include "InputFiles.h"
#include "LinkerScript.h"
#include "OutputSections.h"
#include "SyntheticSections.h"
#include "Target.h"
#include "Thunks.h"
@ -80,9 +81,13 @@ InputSectionBase<ELFT>::InputSectionBase(elf::ObjectFile<ELFT> *File,
}
template <class ELFT> size_t InputSectionBase<ELFT>::getSize() const {
if (auto *S = dyn_cast<SyntheticSection<ELFT>>(this))
return S->getSize();
if (auto *D = dyn_cast<InputSection<ELFT>>(this))
if (D->getThunksSize() > 0)
return D->getThunkOff() + D->getThunksSize();
return Data.size();
}
@ -95,6 +100,7 @@ template <class ELFT>
typename ELFT::uint InputSectionBase<ELFT>::getOffset(uintX_t Offset) const {
switch (kind()) {
case Regular:
case Synthetic:
return cast<InputSection<ELFT>>(this)->OutSecOff + Offset;
case EHFrame:
// The file crtbeginT.o has relocations pointing to the start of an empty
@ -184,10 +190,10 @@ InputSection<ELFT>::InputSection() : InputSectionBase<ELFT>() {}
template <class ELFT>
InputSection<ELFT>::InputSection(uintX_t Flags, uint32_t Type,
uintX_t Addralign, ArrayRef<uint8_t> Data,
StringRef Name)
StringRef Name, Kind K)
: InputSectionBase<ELFT>(nullptr, Flags, Type,
/*Entsize*/ 0, /*Link*/ 0, /*Info*/ 0, Addralign,
Data, Name, Base::Regular) {}
Data, Name, K) {}
template <class ELFT>
InputSection<ELFT>::InputSection(elf::ObjectFile<ELFT> *F,
@ -196,7 +202,7 @@ InputSection<ELFT>::InputSection(elf::ObjectFile<ELFT> *F,
template <class ELFT>
bool InputSection<ELFT>::classof(const InputSectionData *S) {
return S->kind() == Base::Regular;
return S->kind() == Base::Regular || S->kind() == Base::Synthetic;
}
template <class ELFT>
@ -528,6 +534,11 @@ template <class ELFT> void InputSection<ELFT>::writeTo(uint8_t *Buf) {
return;
}
if (auto *S = dyn_cast<SyntheticSection<ELFT>>(this)) {
S->writeTo(Buf);
return;
}
// Copy section contents from source object file to output file.
ArrayRef<uint8_t> Data = this->Data;
memcpy(Buf + OutSecOff, Data.data(), Data.size());

6
lld/ELF/InputSection.h
View File

@ -39,7 +39,7 @@ class OutputSectionBase;
// section
class InputSectionData {
public:
enum Kind { Regular, EHFrame, Merge };
enum Kind { Regular, EHFrame, Merge, Synthetic, };
// The garbage collector sets sections' Live bits.
// If GC is disabled, all sections are considered live by default.
@ -232,11 +232,13 @@ template <class ELFT> class InputSection : public InputSectionBase<ELFT> {
typedef typename ELFT::Rel Elf_Rel;
typedef typename ELFT::Sym Elf_Sym;
typedef typename ELFT::uint uintX_t;
typedef InputSectionData::Kind Kind;
public:
InputSection();
InputSection(uintX_t Flags, uint32_t Type, uintX_t Addralign,
ArrayRef<uint8_t> Data, StringRef Name);
ArrayRef<uint8_t> Data, StringRef Name,
Kind K = InputSectionData::Regular);
InputSection(ObjectFile<ELFT> *F, const Elf_Shdr *Header, StringRef Name);
static InputSection<ELFT> Discarded;

40
lld/ELF/OutputSections.cpp
View File

@ -108,35 +108,6 @@ template <class ELFT> void GdbIndexSection<ELFT>::writeTo(uint8_t *Buf) {
}
}
template <class ELFT>
GotPltSection<ELFT>::GotPltSection()
: OutputSectionBase(".got.plt", SHT_PROGBITS, SHF_ALLOC | SHF_WRITE) {
this->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->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(".got", SHT_PROGBITS, SHF_ALLOC | SHF_WRITE) {
@ -775,7 +746,7 @@ template <class ELFT> void DynamicSection<ELFT>::finalize() {
Add({DT_JMPREL, Out<ELFT>::RelaPlt});
Add({DT_PLTRELSZ, Out<ELFT>::RelaPlt->Size});
Add({Config->EMachine == EM_MIPS ? DT_MIPS_PLTGOT : DT_PLTGOT,
Out<ELFT>::GotPlt});
In<ELFT>::GotPlt});
Add({DT_PLTREL, uint64_t(Config->Rela ? DT_RELA : DT_REL)});
}
@ -846,6 +817,9 @@ template <class ELFT> void DynamicSection<ELFT>::writeTo(uint8_t *Buf) {
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;
@ -1789,6 +1763,7 @@ OutputSectionFactory<ELFT>::create(const SectionKey<ELFT::Is64Bits> &Key,
uint32_t Type = C->Type;
switch (C->kind()) {
case InputSectionBase<ELFT>::Regular:
case InputSectionBase<ELFT>::Synthetic:
Sec = make<OutputSection<ELFT>>(Key.Name, Type, Flags);
break;
case InputSectionBase<ELFT>::EHFrame:
@ -1845,11 +1820,6 @@ 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>;

26
lld/ELF/OutputSections.h
View File

@ -51,7 +51,6 @@ public:
EHFrameHdr,
GnuHashTable,
Got,
GotPlt,
HashTable,
Merge,
Plt,
@ -211,24 +210,6 @@ private:
void writeMipsGot(uint8_t *Buf);
};
template <class ELFT> class GotPltSection final : public OutputSectionBase {
typedef typename ELFT::uint uintX_t;
public:
GotPltSection();
void finalize() override;
void writeTo(uint8_t *Buf) override;
void addEntry(SymbolBody &Sym);
bool empty() const;
Kind getKind() const override { return GotPlt; }
static bool classof(const OutputSectionBase *B) {
return B->getKind() == GotPlt;
}
private:
std::vector<const SymbolBody *> Entries;
};
template <class ELFT> class PltSection final : public OutputSectionBase {
typedef typename ELFT::uint uintX_t;
@ -603,12 +584,15 @@ template <class ELFT> class DynamicSection final : public OutputSectionBase {
int32_t Tag;
union {
OutputSectionBase *OutSec;
InputSection<ELFT> *InSec;
uint64_t Val;
const SymbolBody *Sym;
};
enum KindT { SecAddr, SecSize, SymAddr, PlainInt } Kind;
enum KindT { SecAddr, SecSize, SymAddr, PlainInt, InSecAddr } Kind;
Entry(int32_t Tag, OutputSectionBase *OutSec, KindT Kind = SecAddr)
: Tag(Tag), OutSec(OutSec), Kind(Kind) {}
Entry(int32_t Tag, InputSection<ELFT> *Sec)
: Tag(Tag), InSec(Sec), Kind(InSecAddr) {}
Entry(int32_t Tag, uint64_t Val) : Tag(Tag), Val(Val), Kind(PlainInt) {}
Entry(int32_t Tag, const SymbolBody *Sym)
: Tag(Tag), Sym(Sym), Kind(SymAddr) {}
@ -677,7 +661,6 @@ template <class ELFT> struct Out {
static EhOutputSection<ELFT> *EhFrame;
static GdbIndexSection<ELFT> *GdbIndex;
static GnuHashTableSection<ELFT> *GnuHashTab;
static GotPltSection<ELFT> *GotPlt;
static GotSection<ELFT> *Got;
static HashTableSection<ELFT> *HashTab;
static OutputSection<ELFT> *Bss;
@ -743,7 +726,6 @@ template <class ELFT> EhFrameHeader<ELFT> *Out<ELFT>::EhFrameHdr;
template <class ELFT> EhOutputSection<ELFT> *Out<ELFT>::EhFrame;
template <class ELFT> GdbIndexSection<ELFT> *Out<ELFT>::GdbIndex;
template <class ELFT> GnuHashTableSection<ELFT> *Out<ELFT>::GnuHashTab;
template <class ELFT> GotPltSection<ELFT> *Out<ELFT>::GotPlt;
template <class ELFT> GotSection<ELFT> *Out<ELFT>::Got;
template <class ELFT> HashTableSection<ELFT> *Out<ELFT>::HashTab;
template <class ELFT> OutputSection<ELFT> *Out<ELFT>::Bss;

7
lld/ELF/Relocations.cpp
View File

@ -44,10 +44,11 @@
#include "Relocations.h"
#include "Config.h"
#include "OutputSections.h"
#include "Strings.h"
#include "SymbolTable.h"
#include "SyntheticSections.h"
#include "Target.h"
#include "Thunks.h"
#include "Strings.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/raw_ostream.h"
@ -743,8 +744,8 @@ static void scanRelocs(InputSectionBase<ELFT> &C, ArrayRef<RelTy> Rels) {
else
Rel = Target->PltRel;
Out<ELFT>::GotPlt->addEntry(Body);
Out<ELFT>::RelaPlt->addReloc({Rel, Out<ELFT>::GotPlt,
In<ELFT>::GotPlt->addEntry(Body);
Out<ELFT>::RelaPlt->addReloc({Rel, In<ELFT>::GotPlt,
Body.getGotPltOffset<ELFT>(), !Preemptible,
&Body, 0});
continue;

2
lld/ELF/Symbols.cpp
View File

@ -159,7 +159,7 @@ template <class ELFT> typename ELFT::uint SymbolBody::getGotOffset() const {
}
template <class ELFT> typename ELFT::uint SymbolBody::getGotPltVA() const {
return Out<ELFT>::GotPlt->Addr + getGotPltOffset<ELFT>();
return In<ELFT>::GotPlt->getVA() + getGotPltOffset<ELFT>();
}
template <class ELFT> typename ELFT::uint SymbolBody::getGotPltOffset() const {

35
lld/ELF/SyntheticSections.cpp
View File

@ -313,6 +313,36 @@ void BuildIdHexstring<ELFT>::writeBuildId(MutableArrayRef<uint8_t> Buf) {
Config->BuildIdVector.size());
}
template <class ELFT>
GotPltSection<ELFT>::GotPltSection()
: SyntheticSection<ELFT>(SHF_ALLOC | SHF_WRITE, SHT_PROGBITS,
Target->GotPltEntrySize, ".got.plt") {
this->Live = true;
}
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> 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);
}
}
template InputSection<ELF32LE> *elf::createCommonSection();
template InputSection<ELF32BE> *elf::createCommonSection();
template InputSection<ELF64LE> *elf::createCommonSection();
@ -367,3 +397,8 @@ template class elf::BuildIdHexstring<ELF32LE>;
template class elf::BuildIdHexstring<ELF32BE>;
template class elf::BuildIdHexstring<ELF64LE>;
template class elf::BuildIdHexstring<ELF64BE>;
template class elf::GotPltSection<ELF32LE>;
template class elf::GotPltSection<ELF32BE>;
template class elf::GotPltSection<ELF64LE>;
template class elf::GotPltSection<ELF64BE>;

38
lld/ELF/SyntheticSections.h
View File

@ -58,6 +58,26 @@ private:
Elf_Mips_RegInfo Reginfo = {};
};
template <class ELFT> class SyntheticSection : public InputSection<ELFT> {
typedef typename ELFT::uint uintX_t;
public:
SyntheticSection(uintX_t Flags, uint32_t Type, uintX_t Addralign,
StringRef Name)
: InputSection<ELFT>(Flags, Type, Addralign, ArrayRef<uint8_t>(), Name,
InputSectionData::Synthetic) {}
virtual void writeTo(uint8_t *Buf) {}
virtual size_t getSize() const { return this->Data.size(); }
static bool classof(const InputSectionData *D) {
return D->kind() == InputSectionData::Synthetic;
}
protected:
~SyntheticSection() = default;
};
// .note.gnu.build-id section.
template <class ELFT> class BuildIdSection : public InputSection<ELFT> {
public:
@ -109,6 +129,22 @@ public:
void writeBuildId(llvm::MutableArrayRef<uint8_t>) override;
};
template <class ELFT>
class GotPltSection final : public SyntheticSection<ELFT> {
typedef typename ELFT::uint uintX_t;
public:
GotPltSection();
void addEntry(SymbolBody &Sym);
bool empty() const;
size_t getSize() const override;
void writeTo(uint8_t *Buf) override;
uintX_t getVA() { return this->OutSec->Addr + this->OutSecOff; }
private:
std::vector<const SymbolBody *> Entries;
};
template <class ELFT> InputSection<ELFT> *createCommonSection();
template <class ELFT> InputSection<ELFT> *createInterpSection();
@ -116,6 +152,7 @@ template <class ELFT> InputSection<ELFT> *createInterpSection();
template <class ELFT> struct In {
static BuildIdSection<ELFT> *BuildId;
static InputSection<ELFT> *Common;
static GotPltSection<ELFT> *GotPlt;
static InputSection<ELFT> *Interp;
static MipsAbiFlagsSection<ELFT> *MipsAbiFlags;
static MipsOptionsSection<ELFT> *MipsOptions;
@ -124,6 +161,7 @@ template <class ELFT> struct In {
template <class ELFT> BuildIdSection<ELFT> *In<ELFT>::BuildId;
template <class ELFT> InputSection<ELFT> *In<ELFT>::Common;
template <class ELFT> GotPltSection<ELFT> *In<ELFT>::GotPlt;
template <class ELFT> InputSection<ELFT> *In<ELFT>::Interp;
template <class ELFT> MipsAbiFlagsSection<ELFT> *In<ELFT>::MipsAbiFlags;
template <class ELFT> MipsOptionsSection<ELFT> *In<ELFT>::MipsOptions;

13
lld/ELF/Target.cpp
View File

@ -29,6 +29,7 @@
#include "InputFiles.h"
#include "OutputSections.h"
#include "Symbols.h"
#include "SyntheticSections.h"
#include "Thunks.h"
#include "Writer.h"
@ -403,7 +404,7 @@ void X86TargetInfo::writePltHeader(uint8_t *Buf) const {
0x90, 0x90, 0x90, 0x90 // nop; nop; nop; nop
};
memcpy(Buf, PltData, sizeof(PltData));
uint32_t Got = Out<ELF32LE>::GotPlt->Addr;
uint32_t Got = In<ELF32LE>::GotPlt->getVA();
write32le(Buf + 2, Got + 4);
write32le(Buf + 8, Got + 8);
}
@ -420,7 +421,7 @@ void X86TargetInfo::writePlt(uint8_t *Buf, uint64_t GotEntryAddr,
// jmp *foo@GOT(%ebx) or jmp *foo_in_GOT
Buf[1] = Config->Pic ? 0xa3 : 0x25;
uint32_t Got = Out<ELF32LE>::GotPlt->Addr;
uint32_t Got = In<ELF32LE>::GotPlt->getVA();
write32le(Buf + 2, Config->Shared ? GotEntryAddr - Got : GotEntryAddr);
write32le(Buf + 7, RelOff);
write32le(Buf + 12, -Index * PltEntrySize - PltHeaderSize - 16);
@ -613,7 +614,7 @@ void X86_64TargetInfo<ELFT>::writePltHeader(uint8_t *Buf) const {
0x0f, 0x1f, 0x40, 0x00 // nopl 0x0(rax)
};
memcpy(Buf, PltData, sizeof(PltData));
uint64_t Got = Out<ELFT>::GotPlt->Addr;
uint64_t Got = In<ELFT>::GotPlt->getVA();
uint64_t Plt = Out<ELFT>::Plt->Addr;
write32le(Buf + 2, Got - Plt + 2); // GOT+8
write32le(Buf + 8, Got - Plt + 4); // GOT+16
@ -1274,7 +1275,7 @@ void AArch64TargetInfo::writePltHeader(uint8_t *Buf) const {
};
memcpy(Buf, PltData, sizeof(PltData));
uint64_t Got = Out<ELF64LE>::GotPlt->Addr;
uint64_t Got = In<ELF64LE>::GotPlt->getVA();
uint64_t Plt = Out<ELF64LE>::Plt->Addr;
relocateOne(Buf + 4, R_AARCH64_ADR_PREL_PG_HI21,
getAArch64Page(Got + 16) - getAArch64Page(Plt + 4));
@ -1628,7 +1629,7 @@ void ARMTargetInfo::writePltHeader(uint8_t *Buf) const {
0x00, 0x00, 0x00, 0x00, // L2: .word &(.got.plt) - L1 - 8
};
memcpy(Buf, PltData, sizeof(PltData));
uint64_t GotPlt = Out<ELF32LE>::GotPlt->Addr;
uint64_t GotPlt = In<ELF32LE>::GotPlt->getVA();
uint64_t L1 = Out<ELF32LE>::Plt->Addr + 8;
write32le(Buf + 16, GotPlt - L1 - 8);
}
@ -2063,7 +2064,7 @@ void MipsTargetInfo<ELFT>::writePltHeader(uint8_t *Buf) const {
write32<E>(Buf + 20, 0x0018c082); // srl $24, $24, 2
write32<E>(Buf + 24, 0x0320f809); // jalr $25
write32<E>(Buf + 28, 0x2718fffe); // subu $24, $24, 2
uint64_t Got = Out<ELFT>::GotPlt->Addr;
uint64_t Got = In<ELFT>::GotPlt->getVA();
writeMipsHi16<E>(Buf, Got);
writeMipsLo16<E>(Buf + 4, Got);
writeMipsLo16<E>(Buf + 8, Got);

2
lld/ELF/Target.h
View File

@ -82,7 +82,7 @@ public:
uint32_t TlsModuleIndexRel;
uint32_t TlsOffsetRel;
unsigned GotEntrySize;
unsigned GotPltEntrySize;
unsigned GotPltEntrySize = 0;
unsigned PltEntrySize;
unsigned PltHeaderSize;

14
lld/ELF/Writer.cpp
View File

@ -248,7 +248,6 @@ template <class ELFT> void Writer<ELFT>::createSyntheticSections() {
if (Config->GdbIndex)
Out<ELFT>::GdbIndex = make<GdbIndexSection<ELFT>>();
Out<ELFT>::GotPlt = make<GotPltSection<ELFT>>();
Out<ELFT>::RelaPlt = make<RelocationSection<ELFT>>(
Config->Rela ? ".rela.plt" : ".rel.plt", false /*Sort*/);
if (Config->Strip != StripPolicy::All) {
@ -312,6 +311,8 @@ template <class ELFT> void Writer<ELFT>::createSyntheticSections() {
Symtab<ELFT>::X->Sections.push_back(RegSec);
}
}
In<ELFT>::GotPlt = make<GotPltSection<ELFT>>();
}
template <class ELFT>
@ -423,7 +424,7 @@ template <class ELFT> bool elf::isRelroSection(const OutputSectionBase *Sec) {
if (Type == SHT_INIT_ARRAY || Type == SHT_FINI_ARRAY ||
Type == SHT_PREINIT_ARRAY)
return true;
if (Sec == Out<ELFT>::GotPlt)
if (Sec == In<ELFT>::GotPlt->OutSec)
return Config->ZNow;
if (Sec == Out<ELFT>::Dynamic || Sec == Out<ELFT>::Got)
return true;
@ -893,6 +894,13 @@ template <class ELFT> void Writer<ELFT>::finalizeSections() {
// This function adds linker-created Out<ELFT>::* sections.
addPredefinedSections();
// We fill .got.plt section in scanRelocs(). This is the
// reason we don't add it earlier in createSections().
if (!In<ELFT>::GotPlt->empty()) {
addInputSec(In<ELFT>::GotPlt);
In<ELFT>::GotPlt->OutSec->assignOffsets();
}
sortSections();
unsigned I = 1;
@ -976,8 +984,6 @@ template <class ELFT> void Writer<ELFT>::addPredefinedSections() {
if (needsGot())
Add(Out<ELFT>::Got);
if (Out<ELFT>::GotPlt && !Out<ELFT>::GotPlt->empty())
Add(Out<ELFT>::GotPlt);
if (!Out<ELFT>::Plt->empty())
Add(Out<ELFT>::Plt);
if (!Out<ELFT>::EhFrame->empty())