maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

This patch implements basic variant of lazy loading for x86_x64 and for X86 targets. 

What was done:
1) .got.plt section is created for functions that requires PLT. .got.plt has 3 predefined empty entries now that are required for dynamic linker.
Also other new items created are configured to have correct jump to PLT[N].
2) PLT section now has PLT[0] entry, also others ones are configured to support PLT->GOT(.got.plt) calls.
3) Implemented .rel[a].plt sections (based on patch http://reviews.llvm.org/D13569).
4) Fixed plt relocations types (based on patch http://reviews.llvm.org/D13589).

NOTES:
The .plt.got zero entry is still empty now. According to ELF specification it should hold the address of the dynamic structure, referenced with the symbol
_DYNAMIC. The _DYNAMIC entry points to the .dynamic section which contains information used by the ELF interpreter to setup the binary.

Differential Revision: http://reviews.llvm.org/D13651

llvm-svn: 250169
This commit is contained in:
George Rimar 2015-10-13 16:09:55 +00:00
parent 9100439391
commit 9fd8fcb5a4
10 changed files with 338 additions and 93 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

91
lld/ELF/OutputSections.cpp
View File

@ -29,6 +29,43 @@ OutputSectionBase<Is64Bits>::OutputSectionBase(StringRef Name, uint32_t sh_type,
Header.sh_flags = sh_flags;
}
template <class ELFT>
GotPltSection<ELFT>::GotPltSection()
: OutputSectionBase<ELFT::Is64Bits>(".got.plt", llvm::ELF::SHT_PROGBITS,
llvm::ELF::SHF_ALLOC |
llvm::ELF::SHF_WRITE) {
this->Header.sh_addralign = this->getAddrSize();
// .got.plt has 3 reserved entry
Entries.resize(3);
}
template <class ELFT> void GotPltSection<ELFT>::addEntry(SymbolBody *Sym) {
Sym->GotPltIndex = Entries.size();
Entries.push_back(Sym);
}
template <class ELFT> bool GotPltSection<ELFT>::empty() const {
return Entries.size() == 3;
}
template <class ELFT>
typename GotPltSection<ELFT>::uintX_t
GotPltSection<ELFT>::getEntryAddr(const SymbolBody &B) const {
return this->getVA() + B.GotPltIndex * this->getAddrSize();
}
template <class ELFT> void GotPltSection<ELFT>::finalize() {
this->Header.sh_size = Entries.size() * this->getAddrSize();
}
template <class ELFT> void GotPltSection<ELFT>::writeTo(uint8_t *Buf) {
for (const SymbolBody *B : Entries) {
if (B)
Target->writeGotPltEntry(Buf, Out<ELFT>::Plt->getEntryAddr(*B));
Buf += sizeof(uintX_t);
}
}
template <class ELFT>
GotSection<ELFT>::GotSection()
: OutputSectionBase<ELFT::Is64Bits>(".got", llvm::ELF::SHT_PROGBITS,
@ -69,10 +106,13 @@ PltSection<ELFT>::PltSection()
template <class ELFT> void PltSection<ELFT>::writeTo(uint8_t *Buf) {
size_t Off = 0;
// First write PLT[0] entry which is special.
Target->writePltZeroEntry(Buf, Out<ELFT>::GotPlt->getVA(), this->getVA());
Off += Target->getPltZeroEntrySize();
for (const SymbolBody *E : Entries) {
uint64_t Got = Out<ELFT>::Got->getEntryAddr(*E);
uint64_t Got = Out<ELFT>::GotPlt->getEntryAddr(*E);
uint64_t Plt = this->getVA() + Off;
Target->writePltEntry(Buf + Off, Got, Plt);
Target->writePltEntry(Buf + Off, Got, Plt, E->PltIndex);
Off += Target->getPltEntrySize();
}
}
@ -85,19 +125,20 @@ template <class ELFT> void PltSection<ELFT>::addEntry(SymbolBody *Sym) {
template <class ELFT>
typename PltSection<ELFT>::uintX_t
PltSection<ELFT>::getEntryAddr(const SymbolBody &B) const {
return this->getVA() + B.PltIndex * Target->getPltEntrySize();
return this->getVA() + Target->getPltZeroEntrySize() +
B.PltIndex * Target->getPltEntrySize();
}
template <class ELFT>
void PltSection<ELFT>::finalize() {
this->Header.sh_size = Entries.size() * Target->getPltEntrySize();
this->Header.sh_size =
Target->getPltZeroEntrySize() + Entries.size() * Target->getPltEntrySize();
}
template <class ELFT>
RelocationSection<ELFT>::RelocationSection(bool IsRela)
: OutputSectionBase<ELFT::Is64Bits>(IsRela ? ".rela.dyn" : ".rel.dyn",
IsRela ? llvm::ELF::SHT_RELA
: llvm::ELF::SHT_REL,
RelocationSection<ELFT>::RelocationSection(StringRef Name, bool IsRela)
: OutputSectionBase<ELFT::Is64Bits>(Name, IsRela ? llvm::ELF::SHT_RELA
: llvm::ELF::SHT_REL,
llvm::ELF::SHF_ALLOC),
IsRela(IsRela) {
this->Header.sh_entsize = IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
@ -135,10 +176,22 @@ template <class ELFT> void RelocationSection<ELFT>::writeTo(uint8_t *Buf) {
}
if (Body && Target->relocNeedsGot(Type, *Body)) {
P->r_offset = Out<ELFT>::Got->getEntryAddr(*Body);
// Each symbol that needs plt relocation is placed to Plt and GotPlt,
// otherwise to Got.
// Also symbol can be placed both to Got and Plt + GotPlt, for example
// when we take address of function from DSO and also make a call to it.
// So here depending on what type of relocation is we switch from which
// table to take the offset from.
bool NeedsPlt = Target->relocNeedsPlt(Type, *Body);
if (NeedsPlt)
P->r_offset = Out<ELFT>::GotPlt->getEntryAddr(*Body);
else
P->r_offset = Out<ELFT>::Got->getEntryAddr(*Body);
if (CanBePreempted)
P->setSymbolAndType(Body->getDynamicSymbolTableIndex(),
Target->getGotReloc(), IsMips64EL);
NeedsPlt ? Target->getPltReloc()
: Target->getGotReloc(),
IsMips64EL);
} else {
if (IsRela)
Addend += static_cast<const Elf_Rela &>(RI).r_addend;
@ -255,6 +308,12 @@ template <class ELFT> void DynamicSection<ELFT>::finalize() {
++NumEntries; // DT_RELASZ / DT_RELSZ
++NumEntries; // DT_RELAENT / DT_RELENT
}
if (Out<ELFT>::RelaPlt->hasRelocs()) {
++NumEntries; // DT_JMPREL
++NumEntries; // DT_PLTRELSZ
++NumEntries; // DT_PLTGOT
++NumEntries; // DT_PLTREL
}
++NumEntries; // DT_SYMTAB
++NumEntries; // DT_SYMENT
++NumEntries; // DT_STRTAB
@ -323,7 +382,12 @@ template <class ELFT> void DynamicSection<ELFT>::writeTo(uint8_t *Buf) {
WriteVal(IsRela ? DT_RELAENT : DT_RELENT,
IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel));
}
if (Out<ELFT>::RelaPlt->hasRelocs()) {
WritePtr(DT_JMPREL, Out<ELFT>::RelaPlt->getVA());
WriteVal(DT_PLTRELSZ, Out<ELFT>::RelaPlt->getSize());
WritePtr(DT_PLTGOT, Out<ELFT>::Got->getVA());
WriteVal(DT_PLTREL, Out<ELFT>::RelaPlt->isRela() ? DT_RELA : DT_REL);
}
WritePtr(DT_SYMTAB, Out<ELFT>::DynSymTab->getVA());
WritePtr(DT_SYMENT, sizeof(Elf_Sym));
WritePtr(DT_STRTAB, Out<ELFT>::DynStrTab->getVA());
@ -695,6 +759,11 @@ template void OutputSectionBase<false>::writeHeaderTo<support::big>(
template void OutputSectionBase<true>::writeHeaderTo<support::big>(
ELFFile<ELFType<support::big, true>>::Elf_Shdr *SHdr);
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>;

23
lld/ELF/OutputSections.h
View File

@ -116,6 +116,23 @@ private:
std::vector<const SymbolBody *> Entries;
};
template <class ELFT>
class GotPltSection final : public OutputSectionBase<ELFT::Is64Bits> {
typedef OutputSectionBase<ELFT::Is64Bits> Base;
typedef typename Base::uintX_t uintX_t;
public:
GotPltSection();
void finalize() override;
void writeTo(uint8_t *Buf) override;
void addEntry(SymbolBody *Sym);
bool empty() const;
uintX_t getEntryAddr(const SymbolBody &B) const;
private:
std::vector<const SymbolBody *> Entries;
};
template <class ELFT>
class PltSection final : public OutputSectionBase<ELFT::Is64Bits> {
typedef OutputSectionBase<ELFT::Is64Bits> Base;
@ -172,7 +189,7 @@ class RelocationSection final : public OutputSectionBase<ELFT::Is64Bits> {
typedef typename llvm::object::ELFFile<ELFT>::uintX_t uintX_t;
public:
RelocationSection(bool IsRela);
RelocationSection(StringRef Name, bool IsRela);
void addReloc(const DynamicReloc<ELFT> &Reloc) { Relocs.push_back(Reloc); }
void finalize() override;
void writeTo(uint8_t *Buf) override;
@ -284,6 +301,7 @@ private:
// until Writer is initialized.
template <class ELFT> struct Out {
static DynamicSection<ELFT> *Dynamic;
static GotPltSection<ELFT> *GotPlt;
static GotSection<ELFT> *Got;
static HashTableSection<ELFT> *HashTab;
static InterpSection<ELFT::Is64Bits> *Interp;
@ -292,6 +310,7 @@ template <class ELFT> struct Out {
static uint8_t *OpdBuf;
static PltSection<ELFT> *Plt;
static RelocationSection<ELFT> *RelaDyn;
static RelocationSection<ELFT> *RelaPlt;
static StringTableSection<ELFT::Is64Bits> *DynStrTab;
static StringTableSection<ELFT::Is64Bits> *StrTab;
static SymbolTableSection<ELFT> *DynSymTab;
@ -299,6 +318,7 @@ template <class ELFT> struct Out {
};
template <class ELFT> DynamicSection<ELFT> *Out<ELFT>::Dynamic;
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> InterpSection<ELFT::Is64Bits> *Out<ELFT>::Interp;
@ -307,6 +327,7 @@ template <class ELFT> OutputSection<ELFT> *Out<ELFT>::Opd;
template <class ELFT> uint8_t *Out<ELFT>::OpdBuf;
template <class ELFT> PltSection<ELFT> *Out<ELFT>::Plt;
template <class ELFT> RelocationSection<ELFT> *Out<ELFT>::RelaDyn;
template <class ELFT> RelocationSection<ELFT> *Out<ELFT>::RelaPlt;
template <class ELFT> StringTableSection<ELFT::Is64Bits> *Out<ELFT>::DynStrTab;
template <class ELFT> StringTableSection<ELFT::Is64Bits> *Out<ELFT>::StrTab;
template <class ELFT> SymbolTableSection<ELFT> *Out<ELFT>::DynSymTab;

2
lld/ELF/Symbols.h
View File

@ -79,8 +79,10 @@ public:
void setDynamicSymbolTableIndex(unsigned V) { DynamicSymbolTableIndex = V; }
uint32_t GotIndex = -1;
uint32_t GotPltIndex = -1;
uint32_t PltIndex = -1;
bool isInGot() const { return GotIndex != -1U; }
bool isInGotPlt() const { return GotPltIndex != -1U; }
bool isInPlt() const { return PltIndex != -1U; }
// A SymbolBody has a backreference to a Symbol. Originally they are

101
lld/ELF/Target.cpp
View File

@ -55,16 +55,40 @@ X86TargetInfo::X86TargetInfo() {
PCRelReloc = R_386_PC32;
GotReloc = R_386_GLOB_DAT;
GotRefReloc = R_386_GOT32;
PltReloc = R_386_JUMP_SLOT;
PltEntrySize = 16;
VAStart = 0x10000;
}
void X86TargetInfo::writeGotPltEntry(uint8_t *Buf, uint64_t Plt) const {
// Skip 6 bytes of "jmpq *got(%rip)"
write32le(Buf, Plt + 6);
}
void X86TargetInfo::writePltZeroEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const {
const uint8_t PltData[] = {
0xff, 0x35, 0x00, 0x00, 0x00, 0x00, // pushq GOT+8(%rip)
0xff, 0x25, 0x00, 0x00, 0x00, 0x00, // jmp *GOT+16(%rip)
0x00, 0x00, 0x00, 0x00
};
memcpy(Buf, PltData, sizeof(PltData));
write32le(Buf + 2, GotEntryAddr - PltEntryAddr + 2); // GOT+8
write32le(Buf + 8, GotEntryAddr - PltEntryAddr + 4); // GOT+16
};
void X86TargetInfo::writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const {
// jmpl *val; nop; nop
const uint8_t Inst[] = {0xff, 0x25, 0, 0, 0, 0, 0x90, 0x90};
uint64_t PltEntryAddr, int32_t Index) const {
const uint8_t Inst[] = {
0xff, 0x25, 0x00, 0x00, 0x00, 0x00, // jmpq *got(%rip)
0x68, 0x00, 0x00, 0x00, 0x00, // pushq <relocation index>
0xe9, 0x00, 0x00, 0x00, 0x00 // jmpq plt[0]
};
memcpy(Buf, Inst, sizeof(Inst));
assert(isUInt<32>(GotEntryAddr));
write32le(Buf + 2, GotEntryAddr);
write32le(Buf + 2, GotEntryAddr - PltEntryAddr - 6);
write32le(Buf + 7, Index);
write32le(Buf + 12, -Index * PltEntrySize - PltZeroEntrySize - 16);
}
bool X86TargetInfo::relocNeedsGot(uint32_t Type, const SymbolBody &S) const {
@ -109,7 +133,9 @@ X86_64TargetInfo::X86_64TargetInfo() {
PCRelReloc = R_X86_64_PC32;
GotReloc = R_X86_64_GLOB_DAT;
GotRefReloc = R_X86_64_PC32;
PltReloc = R_X86_64_JUMP_SLOT;
RelativeReloc = R_X86_64_RELATIVE;
PltEntrySize = 16;
// On freebsd x86_64 the first page cannot be mmaped.
// On linux that is controled by vm.mmap_min_addr. At least on some x86_64
@ -120,16 +146,35 @@ X86_64TargetInfo::X86_64TargetInfo() {
VAStart = 0x10000;
}
void X86_64TargetInfo::writeGotPltEntry(uint8_t *Buf, uint64_t Plt) const {
// Skip 6 bytes of "jmpq *got(%rip)"
write32le(Buf, Plt + 6);
}
void X86_64TargetInfo::writePltZeroEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const {
const uint8_t PltData[] = {
0xff, 0x35, 0x00, 0x00, 0x00, 0x00, // pushq GOT+8(%rip)
0xff, 0x25, 0x00, 0x00, 0x00, 0x00, // jmp *GOT+16(%rip)
0x0f, 0x1f, 0x40, 0x00 // nopl 0x0(rax)
};
memcpy(Buf, PltData, sizeof(PltData));
write32le(Buf + 2, GotEntryAddr - PltEntryAddr + 2); // GOT+8
write32le(Buf + 8, GotEntryAddr - PltEntryAddr + 4); // GOT+16
}
void X86_64TargetInfo::writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const {
// jmpq *val(%rip); nop; nop
const uint8_t Inst[] = {0xff, 0x25, 0, 0, 0, 0, 0x90, 0x90};
uint64_t PltEntryAddr, int32_t Index) const {
const uint8_t Inst[] = {
0xff, 0x25, 0x00, 0x00, 0x00, 0x00, // jmpq *got(%rip)
0x68, 0x00, 0x00, 0x00, 0x00, // pushq <relocation index>
0xe9, 0x00, 0x00, 0x00, 0x00 // jmpq plt[0]
};
memcpy(Buf, Inst, sizeof(Inst));
uint64_t NextPC = PltEntryAddr + 6;
int64_t Delta = GotEntryAddr - NextPC;
assert(isInt<32>(Delta));
write32le(Buf + 2, Delta);
write32le(Buf + 2, GotEntryAddr - PltEntryAddr - 6);
write32le(Buf + 7, Index);
write32le(Buf + 12, -Index * PltEntrySize - PltZeroEntrySize - 16);
}
bool X86_64TargetInfo::relocNeedsGot(uint32_t Type, const SymbolBody &S) const {
@ -241,7 +286,9 @@ PPC64TargetInfo::PPC64TargetInfo() {
GotReloc = R_PPC64_GLOB_DAT;
GotRefReloc = R_PPC64_REL64;
RelativeReloc = R_PPC64_RELATIVE;
// PltReloc = FIXME
PltEntrySize = 32;
PltZeroEntrySize = 0; //FIXME
// We need 64K pages (at least under glibc/Linux, the loader won't
// set different permissions on a finer granularity than that).
@ -267,8 +314,12 @@ static uint64_t getPPC64TocBase() {
return TocVA + 0x8000;
}
void PPC64TargetInfo::writeGotPltEntry(uint8_t *Buf, uint64_t Plt) const {}
void PPC64TargetInfo::writePltZeroEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const {};
void PPC64TargetInfo::writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const {
uint64_t PltEntryAddr, int32_t Index) const {
uint64_t Off = GotEntryAddr - getPPC64TocBase();
// FIXME: What we should do, in theory, is get the offset of the function
@ -457,11 +508,16 @@ void PPC64TargetInfo::relocateOne(uint8_t *Buf, uint8_t *BufEnd,
PPCTargetInfo::PPCTargetInfo() {
// PCRelReloc = FIXME
// GotReloc = FIXME
// PltReloc = FIXME
PageSize = 65536;
VAStart = 0x10000000;
}
void PPCTargetInfo::writeGotPltEntry(uint8_t *Buf, uint64_t Plt) const {}
void PPCTargetInfo::writePltZeroEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const {};
void PPCTargetInfo::writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const {}
uint64_t PltEntryAddr, int32_t Index) const {}
bool PPCTargetInfo::relocNeedsGot(uint32_t Type, const SymbolBody &S) const {
return false;
}
@ -475,10 +531,16 @@ void PPCTargetInfo::relocateOne(uint8_t *Buf, uint8_t *BufEnd,
AArch64TargetInfo::AArch64TargetInfo() {
// PCRelReloc = FIXME
// GotReloc = FIXME
// PltReloc = FIXME
VAStart = 0x400000;
}
void AArch64TargetInfo::writeGotPltEntry(uint8_t *Buf, uint64_t Plt) const {}
void AArch64TargetInfo::writePltZeroEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const {};
void AArch64TargetInfo::writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const {}
uint64_t PltEntryAddr,
int32_t Index) const {}
bool AArch64TargetInfo::relocNeedsGot(uint32_t Type,
const SymbolBody &S) const {
return false;
@ -553,12 +615,19 @@ void AArch64TargetInfo::relocateOne(uint8_t *Buf, uint8_t *BufEnd,
MipsTargetInfo::MipsTargetInfo() {
// PCRelReloc = FIXME
// GotReloc = FIXME
// PltReloc = FIXME
PageSize = 65536;
VAStart = 0x400000;
}
void MipsTargetInfo::writeGotPltEntry(uint8_t *Buf, uint64_t Plt) const {}
void MipsTargetInfo::writePltZeroEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const {}
void MipsTargetInfo::writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const {}
uint64_t PltEntryAddr, int32_t Index) const {
}
bool MipsTargetInfo::relocNeedsGot(uint32_t Type, const SymbolBody &S) const {
return false;

40
lld/ELF/Target.h
View File

@ -24,11 +24,16 @@ public:
uint64_t getVAStart() const { return VAStart; }
unsigned getPCRelReloc() const { return PCRelReloc; }
unsigned getGotReloc() const { return GotReloc; }
unsigned getPltReloc() const { return PltReloc; }
unsigned getGotRefReloc() const { return GotRefReloc; }
unsigned getRelativeReloc() const { return RelativeReloc; }
unsigned getPltZeroEntrySize() const { return PltZeroEntrySize; }
unsigned getPltEntrySize() const { return PltEntrySize; }
virtual void writeGotPltEntry(uint8_t *Buf, uint64_t Plt) const = 0;
virtual void writePltZeroEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const = 0;
virtual void writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const = 0;
uint64_t PltEntryAddr, int32_t Index) const = 0;
virtual bool isRelRelative(uint32_t Type) const;
virtual bool relocNeedsGot(uint32_t Type, const SymbolBody &S) const = 0;
virtual bool relocPointsToGot(uint32_t Type) const;
@ -45,15 +50,21 @@ protected:
unsigned PCRelReloc;
unsigned GotRefReloc;
unsigned GotReloc;
unsigned PltReloc;
unsigned RelativeReloc;
unsigned PltEntrySize = 8;
unsigned PltZeroEntrySize = 16;
llvm::StringRef DefaultEntry = "_start";
};
class X86TargetInfo final : public TargetInfo {
public:
X86TargetInfo();
void writeGotPltEntry(uint8_t *Buf, uint64_t Plt) const override;
void writePltZeroEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const override;
void writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const override;
uint64_t PltEntryAddr, int32_t Index) const override;
bool relocNeedsGot(uint32_t Type, const SymbolBody &S) const override;
bool relocPointsToGot(uint32_t Type) const override;
bool relocNeedsPlt(uint32_t Type, const SymbolBody &S) const override;
@ -65,8 +76,11 @@ public:
class X86_64TargetInfo final : public TargetInfo {
public:
X86_64TargetInfo();
void writeGotPltEntry(uint8_t *Buf, uint64_t Plt) const override;
void writePltZeroEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const override;
void writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const override;
uint64_t PltEntryAddr, int32_t Index) const override;
bool relocNeedsGot(uint32_t Type, const SymbolBody &S) const override;
bool relocNeedsPlt(uint32_t Type, const SymbolBody &S) const override;
void relocateOne(uint8_t *Buf, uint8_t *BufEnd, const void *RelP,
@ -78,8 +92,11 @@ public:
class PPC64TargetInfo final : public TargetInfo {
public:
PPC64TargetInfo();
void writeGotPltEntry(uint8_t *Buf, uint64_t Plt) const override;
void writePltZeroEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const override;
void writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const override;
uint64_t PltEntryAddr, int32_t Index) const override;
bool relocNeedsGot(uint32_t Type, const SymbolBody &S) const override;
bool relocNeedsPlt(uint32_t Type, const SymbolBody &S) const override;
void relocateOne(uint8_t *Buf, uint8_t *BufEnd, const void *RelP,
@ -91,8 +108,11 @@ public:
class PPCTargetInfo final : public TargetInfo {
public:
PPCTargetInfo();
void writeGotPltEntry(uint8_t *Buf, uint64_t Plt) const override;
void writePltZeroEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const override;
void writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const override;
uint64_t PltEntryAddr, int32_t Index) const override;
bool relocNeedsGot(uint32_t Type, const SymbolBody &S) const override;
bool relocNeedsPlt(uint32_t Type, const SymbolBody &S) const override;
void relocateOne(uint8_t *Buf, uint8_t *BufEnd, const void *RelP,
@ -103,8 +123,11 @@ public:
class AArch64TargetInfo final : public TargetInfo {
public:
AArch64TargetInfo();
void writeGotPltEntry(uint8_t *Buf, uint64_t Plt) const override;
void writePltZeroEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const override;
void writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const override;
uint64_t PltEntryAddr, int32_t Index) const override;
bool relocNeedsGot(uint32_t Type, const SymbolBody &S) const override;
bool relocNeedsPlt(uint32_t Type, const SymbolBody &S) const override;
void relocateOne(uint8_t *Buf, uint8_t *BufEnd, const void *RelP,
@ -115,8 +138,11 @@ public:
class MipsTargetInfo final : public TargetInfo {
public:
MipsTargetInfo();
void writeGotPltEntry(uint8_t *Buf, uint64_t Plt) const override;
void writePltZeroEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const override;
void writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
uint64_t PltEntryAddr) const override;
uint64_t PltEntryAddr, int32_t Index) const override;
bool relocNeedsGot(uint32_t Type, const SymbolBody &S) const override;
bool relocNeedsPlt(uint32_t Type, const SymbolBody &S) const override;
void relocateOne(uint8_t *Buf, uint8_t *BufEnd, const void *RelP,

20
lld/ELF/Writer.cpp
View File

@ -98,6 +98,8 @@ template <class ELFT> void lld::elf2::writeResult(SymbolTable<ELFT> *Symtab) {
Out<ELFT>::Bss = &Bss;
GotSection<ELFT> Got;
Out<ELFT>::Got = &Got;
GotPltSection<ELFT> GotPlt;
Out<ELFT>::GotPlt = &GotPlt;
PltSection<ELFT> Plt;
Out<ELFT>::Plt = &Plt;
SymbolTableSection<ELFT> SymTab(*Symtab, *Out<ELFT>::StrTab);
@ -106,8 +108,11 @@ template <class ELFT> void lld::elf2::writeResult(SymbolTable<ELFT> *Symtab) {
Out<ELFT>::DynSymTab = &DynSymTab;
HashTableSection<ELFT> HashTab;
Out<ELFT>::HashTab = &HashTab;
RelocationSection<ELFT> RelaDyn(Symtab->shouldUseRela());
bool IsRela = Symtab->shouldUseRela();
RelocationSection<ELFT> RelaDyn(IsRela ? ".rela.dyn" : ".rel.dyn", IsRela);
Out<ELFT>::RelaDyn = &RelaDyn;
RelocationSection<ELFT> RelaPlt(IsRela ? ".rela.plt" : ".rel.plt", IsRela);
Out<ELFT>::RelaPlt = &RelaPlt;
DynamicSection<ELFT> Dynamic(*Symtab);
Out<ELFT>::Dynamic = &Dynamic;
@ -187,8 +192,8 @@ void Writer<ELFT>::scanRelocs(
if (Body->isInPlt())
continue;
Out<ELFT>::Plt->addEntry(Body);
}
if (Target->relocNeedsGot(Type, *Body)) {
Out<ELFT>::GotPlt->addEntry(Body);
} else if (Target->relocNeedsGot(Type, *Body)) {
if (Body->isInGot())
continue;
Out<ELFT>::Got->addEntry(Body);
@ -200,7 +205,10 @@ void Writer<ELFT>::scanRelocs(
continue;
if (CBP)
Body->setUsedInDynamicReloc();
Out<ELFT>::RelaDyn->addReloc({C, RI});
if (Body && Target->relocNeedsPlt(Type, *Body))
Out<ELFT>::RelaPlt->addReloc({ C, RI });
else
Out<ELFT>::RelaDyn->addReloc({ C, RI });
}
}
@ -447,9 +455,13 @@ template <class ELFT> void Writer<ELFT>::createSections() {
OutputSections.push_back(Out<ELFT>::DynStrTab);
if (Out<ELFT>::RelaDyn->hasRelocs())
OutputSections.push_back(Out<ELFT>::RelaDyn);
if (Out<ELFT>::RelaPlt->hasRelocs())
OutputSections.push_back(Out<ELFT>::RelaPlt);
}
if (!Out<ELFT>::Got->empty())
OutputSections.push_back(Out<ELFT>::Got);
if (!Out<ELFT>::GotPlt->empty())
OutputSections.push_back(Out<ELFT>::GotPlt);
if (!Out<ELFT>::Plt->empty())
OutputSections.push_back(Out<ELFT>::Plt);

61
lld/test/elf2/plt-i686.s
View File

@ -14,42 +14,63 @@
// CHECK-NEXT: ]
// CHECK-NEXT: Address: 0x11010
// CHECK-NEXT: Offset:
// CHECK-NEXT: Size: 16
// CHECK-NEXT: Size: 48
// CHECK-NEXT: Link: 0
// CHECK-NEXT: Info: 0
// CHECK-NEXT: AddressAlignment: 16
// CHECK: Name: .got.plt
// CHECK-NEXT: Type: SHT_PROGBITS
// CHECK-NEXT: Flags [
// CHECK-NEXT: SHF_ALLOC
// CHECK-NEXT: SHF_WRITE
// CHECK-NEXT: ]
// CHECK-NEXT: Address: 0x12058
// CHECK-NEXT: Offset: 0x2058
// CHECK-NEXT: Size: 20
// CHECK-NEXT: Link: 0
// CHECK-NEXT: Info: 0
// CHECK-NEXT: AddressAlignment: 4
// CHECK-NEXT: EntrySize: 0
// CHECK: Relocations [
// CHECK-NEXT: Section ({{.*}}) .rel.dyn {
// CHECK-NEXT: 0x12050 R_386_GLOB_DAT bar 0x0
// CHECK-NEXT: 0x12054 R_386_GLOB_DAT zed 0x0
// CHECK-NEXT: Section ({{.*}}) .rel.plt {
// CHECK-NEXT: 0x12064 R_386_JUMP_SLOT bar 0x0
// CHECK-NEXT: 0x12068 R_386_JUMP_SLOT zed 0x0
// CHECK-NEXT: }
// CHECK-NEXT: ]
// Unfortunately FileCheck can't do math, so we have to check for explicit
// values:
// 0x11010 - (0x11000 + 1) - 4 = 11
// 0x11010 - (0x11005 + 1) - 4 = 2
// 0x11018 - (0x1100a + 1) - 4 = 9
// 16 is the size of PLT[0]
// (0x11010 + 16) - (0x11000 + 1) - 4 = 27
// (0x11010 + 16) - (0x11005 + 1) - 4 = 22
// (0x11020 + 16) - (0x1100a + 1) - 4 = 33
// DISASM: _start:
// DISASM-NEXT: 11000: e9 0b 00 00 00 jmp 11
// DISASM-NEXT: 11005: e9 06 00 00 00 jmp 6
// DISASM-NEXT: 1100a: e9 09 00 00 00 jmp 9
// 0x12050 = 73808
// 0x12054 = 73812
// DISASM-NEXT: 11000: e9 1b 00 00 00 jmp 27
// DISASM-NEXT: 11005: e9 16 00 00 00 jmp 22
// DISASM-NEXT: 1100a: e9 21 00 00 00 jmp 33
// 0x12064 - 0x11020 - 6 = 4158
// 0x12068 - 0x11030 - 6 = 4146
// 0x11010 - 0x1102b - 5 = -32
// 0x11010 - 0x1103b - 5 = -48
// DISASM: Disassembly of section .plt:
// DISASM-NEXT: .plt:
// DISASM-NEXT: 11010: ff 25 {{.*}} jmpl *73808
// DISASM-NEXT: 11016: 90 nop
// DISASM-NEXT: 11017: 90 nop
// DISASM-NEXT: 11018: ff 25 {{.*}} jmpl *73812
// DISASM-NEXT: 1101e: 90 nop
// DISASM-NEXT: 1101f: 90 nop
// DISASM-NEXT: 11010: ff 35 4a 10 00 00 pushl 4170
// DISASM-NEXT: 11016: ff 25 4c 10 00 00 jmpl *4172
// DISASM-NEXT: 1101c: 00 00 addb %al, (%eax)
// DISASM-NEXT: 1101e: 00 00 addb %al, (%eax)
// DISASM-NEXT: 11020: ff 25 3e 10 00 00 jmpl *4158
// DISASM-NEXT: 11026: 68 00 00 00 00 pushl $0
// DISASM-NEXT: 1102b: e9 e0 ff ff ff jmp -32
// DISASM-NEXT: 11030: ff 25 32 10 00 00 jmpl *4146
// DISASM-NEXT: 11036: 68 01 00 00 00 pushl $1
// DISASM-NEXT: 1103b: e9 d0 ff ff ff jmp -48
.global _start
_start:
jmp bar@PLT

45
lld/test/elf2/plt.s
View File

@ -14,42 +14,49 @@
// CHECK-NEXT: ]
// CHECK-NEXT: Address: 0x1020
// CHECK-NEXT: Offset:
// CHECK-NEXT: Size: 24
// CHECK-NEXT: Size: 64
// CHECK-NEXT: Link: 0
// CHECK-NEXT: Info: 0
// CHECK-NEXT: AddressAlignment: 16
// CHECK: Relocations [
// CHECK-NEXT: Section ({{.*}}) .rela.dyn {
// CHECK-NEXT: 0x20A0 R_X86_64_GLOB_DAT bar 0x0
// CHECK-NEXT: 0x20A8 R_X86_64_GLOB_DAT zed 0x0
// CHECK-NEXT: 0x20B0 R_X86_64_GLOB_DAT _start 0x0
// CHECK-NEXT: Section ({{.*}}) .rela.plt {
// CHECK-NEXT: 0x20C8 R_X86_64_JUMP_SLOT bar 0x0
// CHECK-NEXT: 0x20D0 R_X86_64_JUMP_SLOT zed 0x0
// CHECK-NEXT: 0x20D8 R_X86_64_JUMP_SLOT _start 0x0
// CHECK-NEXT: }
// CHECK-NEXT: ]
// Unfortunately FileCheck can't do math, so we have to check for explicit
// values:
// 0x11020 - (0x11000 + 1) - 4 = 27
// 0x11020 - (0x11005 + 1) - 4 = 22
// 0x11028 - (0x1100a + 1) - 4 = 25
// 0x1030 - (0x1000 + 5) = 43
// 0x1030 - (0x1005 + 5) = 38
// 0x1040 - (0x100a + 5) = 49
// DISASM: _start:
// DISASM-NEXT: 1000: e9 {{.*}} jmp 27
// DISASM-NEXT: 1005: e9 {{.*}} jmp 22
// DISASM-NEXT: 100a: e9 {{.*}} jmp 25
// DISASM-NEXT: 1000: e9 {{.*}} jmp 43
// DISASM-NEXT: 1005: e9 {{.*}} jmp 38
// DISASM-NEXT: 100a: e9 {{.*}} jmp 49
// 0x120A0 - 0x11026 = 4218
// 0x120A8 - 0x1102e = 4218
// 0x20C8 - 0x1036 = 4242
// 0x20D0 - 0x1046 = 4234
// DISASM: Disassembly of section .plt:
// DISASM-NEXT: .plt:
// DISASM-NEXT: 1020: ff 25 {{.*}} jmpq *4218(%rip)
// DISASM-NEXT: 1026: 90 nop
// DISASM-NEXT: 1027: 90 nop
// DISASM-NEXT: 1028: ff 25 {{.*}} jmpq *4218(%rip)
// DISASM-NEXT: 102e: 90 nop
// DISASM-NEXT: 102f: 90 nop
// DISASM-NEXT: 1020: ff 35 92 10 00 00 pushq 4242(%rip)
// DISASM-NEXT: 1026: ff 25 94 10 00 00 jmpq *4244(%rip)
// DISASM-NEXT: 102c: 0f 1f 40 00 nopl (%rax)
// DISASM-NEXT: 1030: ff 25 92 10 00 00 jmpq *4242(%rip)
// DISASM-NEXT: 1036: 68 00 00 00 00 pushq $0
// DISASM-NEXT: 103b: e9 e0 ff ff ff jmp -32 <bar+1020>
// DISASM-NEXT: 1040: ff 25 8a 10 00 00 jmpq *4234(%rip)
// DISASM-NEXT: 1046: 68 01 00 00 00 pushq $1
// DISASM-NEXT: 104b: e9 d0 ff ff ff jmp -48 <bar+1020>
// DISASM-NEXT: 1050: ff 25 82 10 00 00 jmpq *4226(%rip)
// DISASM-NEXT: 1056: 68 02 00 00 00 pushq $2
// DISASM-NEXT: 105b: e9 c0 ff ff ff jmp -64 <bar+1020>
.global _start
_start:

13
lld/test/elf2/relocation-i686.s
View File

@ -47,7 +47,7 @@ movl bar@GOT, %eax
// ADDR-NEXT: ]
// ADDR-NEXT: Address: 0x11030
// ADDR-NEXT: Offset: 0x1030
// ADDR-NEXT: Size: 8
// ADDR-NEXT: Size: 32
// ADDR: Name: .got
// ADDR-NEXT: Type: SHT_PROGBITS
@ -55,24 +55,25 @@ movl bar@GOT, %eax
// ADDR-NEXT: SHF_ALLOC
// ADDR-NEXT: SHF_WRITE
// ADDR-NEXT: ]
// ADDR-NEXT: Address: 0x12050
// ADDR-NEXT: Address: 0x12070
.section .R_386_GOTPC,"ax",@progbits
R_386_GOTPC:
movl $_GLOBAL_OFFSET_TABLE_, %eax
// 0x12050 - 0x11014 = 4156
// 0x12070 - 0x11014 = 4188
// CHECK: Disassembly of section .R_386_GOTPC:
// CHECK-NEXT: R_386_GOTPC:
// CHECK-NEXT: 11014: {{.*}} movl $4156, %eax
// CHECK-NEXT: 11014: {{.*}} movl $4188, %eax
.section .dynamic_reloc, "ax",@progbits
call bar
// 0x11030 - (0x11019 + 5) = 18
// (0x11030 + 16) - (0x11019 + 5) = 34
// 16 - is a size of PLT[0]
// CHECK: Disassembly of section .dynamic_reloc:
// CHECK-NEXT: .dynamic_reloc:
// CHECK-NEXT: 11019: e8 12 00 00 00 calll 18
// CHECK-NEXT: 11019: e8 22 00 00 00 calll 34
.section .R_386_GOT32,"ax",@progbits
.global R_386_GOT32

35
lld/test/elf2/relocation.s
View File

@ -14,23 +14,39 @@
// SEC-NEXT: ]
// SEC-NEXT: Address: 0x11020
// SEC-NEXT: Offset: 0x1020
// SEC-NEXT: Size: 8
// SEC-NEXT: Size: 32
// SEC: Name: .got
// SEC: Name: .got
// SEC-NEXT: Type: SHT_PROGBITS
// SEC-NEXT: Flags [
// SEC-NEXT: SHF_ALLOC
// SEC-NEXT: SHF_WRITE
// SEC-NEXT: ]
// SEC-NEXT: Address: 0x120A0
// SEC-NEXT: Address: 0x120E0
// SEC-NEXT: Offset:
// SEC-NEXT: Size: 16
// SEC-NEXT: Size: 8
// SEC-NEXT: Link: 0
// SEC-NEXT: Info: 0
// SEC-NEXT: AddressAlignment: 8
// SEC-NEXT: EntrySize: 0
// SEC-NEXT: }
// SEC: Name: .got.plt
// SEC-NEXT: Type: SHT_PROGBITS
// SEC-NEXT: Flags [
// SEC-NEXT: SHF_ALLOC
// SEC-NEXT: SHF_WRITE
// SEC-NEXT: ]
// SEC-NEXT: Address: 0x120E8
// SEC-NEXT: Offset: 0x20E8
// SEC-NEXT: Size: 32
// SEC-NEXT: Link: 0
// SEC-NEXT: Info: 0
// SEC-NEXT: AddressAlignment: 8
// SEC-NEXT: EntrySize: 0
// SEC-NEXT: }
.section .text,"ax",@progbits,unique,1
.global _start
_start:
@ -75,10 +91,11 @@ R_X86_64_32S:
.global R_X86_64_PC32
R_X86_64_PC32:
call bar
// 0x11020 - (0x11017 + 5) = 4
// (0x11020 + 16) - (0x11017 + 5) = 20
// 16 - is a size of PLT[0]
// CHECK: Disassembly of section .R_X86_64_PC32:
// CHECK-NEXT: R_X86_64_PC32:
// CHECK-NEXT: 11017: e8 04 00 00 00 callq 4
// CHECK-NEXT: 11017: e8 14 00 00 00 callq 20
.section .R_X86_64_64,"a",@progbits
.global R_X86_64_64
@ -93,7 +110,7 @@ R_X86_64_64:
R_X86_64_GOTPCREL:
.long zed@gotpcrel
// 0x120A8 - 0x10160 = 8008
// 8008 = 0x481f0000 in little endian
// 0x120E0 - 0x10160 = 8064
// 8064 = 0x801f0000 in little endian
// CHECK: Contents of section .R_X86_64_GOTPCREL
// CHECK-NEXT: 10160 481f0000
// CHECK-NEXT: 10160 801f0000