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Delete isTlsDynRel.

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It was a badly specified hack for when a tls relocation should be
propagated to the dynamic relocation table.

This replaces it with a not as bad hack of saying that a local dynamic
tls relocation is never preempted.

I will try to remove even that second hack in the next patch.

llvm-svn: 262955
This commit is contained in:
Rafael Espindola 2016-03-08 20:24:36 +00:00
parent 715b04eda6
commit 1f04c44885
7 changed files with 26 additions and 51 deletions
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9
lld/ELF/InputSection.cpp
View File

@ -271,7 +271,7 @@ void InputSectionBase<ELFT>::relocate(uint8_t *Buf, uint8_t *BufEnd,
}
uintX_t SymVA = Body->getVA<ELFT>();
bool CBP = canBePreempted(Body);
bool CBP = canBePreempted(Body, Type);
if (Target->needsPlt<ELFT>(Type, *Body)) {
SymVA = Body->getPltVA<ELFT>();
} else if (Target->needsGot(Type, *Body)) {
@ -284,11 +284,6 @@ void InputSectionBase<ELFT>::relocate(uint8_t *Buf, uint8_t *BufEnd,
SymVA = Body->getGotVA<ELFT>();
if (Body->IsTls)
Type = Target->getTlsGotRel(Type);
} else if (!Target->needsCopyRel<ELFT>(Type, *Body) &&
isa<SharedSymbol<ELFT>>(*Body)) {
continue;
} else if (Target->isTlsDynRel(Type, *Body)) {
continue;
} else if (Target->isSizeRel(Type) && CBP) {
// A SIZE relocation is supposed to set a symbol size, but if a symbol
// can be preempted, the size at runtime may be different than link time.
@ -302,6 +297,8 @@ void InputSectionBase<ELFT>::relocate(uint8_t *Buf, uint8_t *BufEnd,
SymVA = getMipsGpAddr<ELFT>() - AddrLoc + 4;
else if (Body == Config->MipsLocalGp)
SymVA = getMipsGpAddr<ELFT>();
} else if (!Target->needsCopyRel<ELFT>(Type, *Body) && CBP) {
continue;
}
uintX_t Size = Body->getSize<ELFT>();
Target->relocateOne(BufLoc, BufEnd, Type, AddrLoc, SymVA + A, Size + A,

11
lld/ELF/OutputSections.cpp
View File

@ -176,7 +176,7 @@ template <class ELFT> void GotSection<ELFT>::writeTo(uint8_t *Buf) {
// for detailed description:
// ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
// As the first approach, we can just store addresses for all symbols.
if (Config->EMachine != EM_MIPS && canBePreempted(B))
if (Config->EMachine != EM_MIPS && canBePreempted(B, 0))
continue; // The dynamic linker will take care of it.
uintX_t VA = B->getVA<ELFT>();
write<uintX_t, ELFT::TargetEndianness, sizeof(uintX_t)>(Entry, VA);
@ -932,9 +932,16 @@ elf::getLocalRelTarget(const ObjectFile<ELFT> &File,
// Returns true if a symbol can be replaced at load-time by a symbol
// with the same name defined in other ELF executable or DSO.
bool elf::canBePreempted(const SymbolBody *Body) {
bool elf::canBePreempted(const SymbolBody *Body, unsigned Type) {
if (!Body)
return false; // Body is a local symbol.
// FIXME: Both gold and bfd consider that a local dynamic tls relocation to
// a symbol will not be preempted. Is that actually relevant? The compiler
// should not use it if the symbol can be preempted.
if (Target->isTlsLocalDynamicRel(Type))
return false;
if (Body->isShared())
return true;

2
lld/ELF/OutputSections.h
View File

@ -53,7 +53,7 @@ getLocalRelTarget(const ObjectFile<ELFT> &File,
const llvm::object::Elf_Rel_Impl<ELFT, IsRela> &Rel,
typename llvm::object::ELFFile<ELFT>::uintX_t Addend);
bool canBePreempted(const SymbolBody *Body);
bool canBePreempted(const SymbolBody *Body, unsigned Type);
bool isValidCIdentifier(StringRef S);

46
lld/ELF/Target.cpp
View File

@ -87,7 +87,6 @@ public:
bool isTlsLocalDynamicRel(uint32_t Type) const override;
bool isTlsGlobalDynamicRel(uint32_t Type) const override;
bool isTlsInitialExecRel(uint32_t Type) const override;
bool isTlsDynRel(uint32_t Type, const SymbolBody &S) const override;
void writeGotPlt(uint8_t *Buf, uint64_t Plt) const override;
void writePltZero(uint8_t *Buf) const override;
void writePlt(uint8_t *Buf, uint64_t GotEntryAddr, uint64_t PltEntryAddr,
@ -123,7 +122,6 @@ public:
bool isTlsLocalDynamicRel(uint32_t Type) const override;
bool isTlsGlobalDynamicRel(uint32_t Type) const override;
bool isTlsInitialExecRel(uint32_t Type) const override;
bool isTlsDynRel(uint32_t Type, const SymbolBody &S) const override;
void writeGotPltHeader(uint8_t *Buf) const override;
void writeGotPlt(uint8_t *Buf, uint64_t Plt) const override;
void writePltZero(uint8_t *Buf) const override;
@ -185,7 +183,6 @@ public:
void writePlt(uint8_t *Buf, uint64_t GotEntryAddr, uint64_t PltEntryAddr,
int32_t Index, unsigned RelOff) const override;
uint32_t getTlsGotRel(uint32_t Type) const override;
bool isTlsDynRel(uint32_t Type, const SymbolBody &S) const override;
bool isRelRelative(uint32_t Type) const override;
bool needsCopyRelImpl(uint32_t Type) const override;
bool needsGot(uint32_t Type, SymbolBody &S) const override;
@ -281,7 +278,7 @@ bool TargetInfo::canRelaxTls(uint32_t Type, const SymbolBody *S) const {
// Initial-Exec relocs can be relaxed to Local-Exec if the symbol is locally
// defined.
if (isTlsInitialExecRel(Type))
return !canBePreempted(S);
return !canBePreempted(S, Type);
return false;
}
@ -304,10 +301,6 @@ bool TargetInfo::needsCopyRel(uint32_t Type, const SymbolBody &S) const {
return mayNeedCopy<ELFT>(S) && needsCopyRelImpl(Type);
}
bool TargetInfo::isTlsDynRel(uint32_t Type, const SymbolBody &S) const {
return false;
}
bool TargetInfo::isGotRelative(uint32_t Type) const { return false; }
bool TargetInfo::isHintRel(uint32_t Type) const { return false; }
bool TargetInfo::isRelRelative(uint32_t Type) const { return true; }
@ -324,7 +317,7 @@ TargetInfo::PltNeed TargetInfo::needsPlt(uint32_t Type,
const SymbolBody &S) const {
if (isGnuIFunc<ELFT>(S))
return Plt_Explicit;
if (canBePreempted(&S) && needsPltImpl(Type))
if (canBePreempted(&S, Type) && needsPltImpl(Type))
return Plt_Explicit;
// This handles a non PIC program call to function in a shared library.
@ -428,15 +421,6 @@ bool X86TargetInfo::isTlsInitialExecRel(uint32_t Type) const {
return Type == R_386_TLS_IE || Type == R_386_TLS_GOTIE;
}
bool X86TargetInfo::isTlsDynRel(uint32_t Type, const SymbolBody &S) const {
if (Type == R_386_TLS_LE || Type == R_386_TLS_LE_32 ||
Type == R_386_TLS_GOTIE)
return Config->Shared;
if (Type == R_386_TLS_IE)
return canBePreempted(&S);
return Type == R_386_TLS_GD;
}
void X86TargetInfo::writePltZero(uint8_t *Buf) const {
// Executable files and shared object files have
// separate procedure linkage tables.
@ -486,7 +470,7 @@ bool X86TargetInfo::needsCopyRelImpl(uint32_t Type) const {
bool X86TargetInfo::needsGot(uint32_t Type, SymbolBody &S) const {
if (S.IsTls && Type == R_386_TLS_GD)
return Target->canRelaxTls(Type, &S) && canBePreempted(&S);
return Target->canRelaxTls(Type, &S) && canBePreempted(&S, Type);
if (Type == R_386_TLS_GOTIE || Type == R_386_TLS_IE)
return !canRelaxTls(Type, &S);
return Type == R_386_GOT32 || needsPlt<ELF32LE>(Type, S);
@ -564,7 +548,7 @@ size_t X86TargetInfo::relaxTls(uint8_t *Loc, uint8_t *BufEnd, uint32_t Type,
const SymbolBody *S) const {
switch (Type) {
case R_386_TLS_GD:
if (canBePreempted(S))
if (canBePreempted(S, Type))
relocateTlsGdToIe(Loc, BufEnd, P, SA);
else
relocateTlsGdToLe(Loc, BufEnd, P, SA);
@ -748,7 +732,7 @@ bool X86_64TargetInfo::refersToGotEntry(uint32_t Type) const {
bool X86_64TargetInfo::needsGot(uint32_t Type, SymbolBody &S) const {
if (Type == R_X86_64_TLSGD)
return Target->canRelaxTls(Type, &S) && canBePreempted(&S);
return Target->canRelaxTls(Type, &S) && canBePreempted(&S, Type);
if (Type == R_X86_64_GOTTPOFF)
return !canRelaxTls(Type, &S);
return refersToGotEntry(Type) || needsPlt<ELF64LE>(Type, S);
@ -774,11 +758,8 @@ bool X86_64TargetInfo::pointsToLocalDynamicGotEntry(uint32_t Type) const {
}
bool X86_64TargetInfo::isTlsLocalDynamicRel(uint32_t Type) const {
return Type == R_X86_64_DTPOFF32 || Type == R_X86_64_TLSLD;
}
bool X86_64TargetInfo::isTlsDynRel(uint32_t Type, const SymbolBody &S) const {
return Type == R_X86_64_GOTTPOFF || Type == R_X86_64_TLSGD;
return Type == R_X86_64_DTPOFF32 || Type == R_X86_64_DTPOFF64 ||
Type == R_X86_64_TLSLD;
}
bool X86_64TargetInfo::needsPltImpl(uint32_t Type) const {
@ -918,7 +899,7 @@ size_t X86_64TargetInfo::relaxTls(uint8_t *Loc, uint8_t *BufEnd, uint32_t Type,
relocateTlsIeToLe(Loc, BufEnd, P, SA);
return 0;
case R_X86_64_TLSGD: {
if (canBePreempted(S))
if (canBePreempted(S, Type))
relocateTlsGdToIe(Loc, BufEnd, P, SA);
else
relocateTlsGdToLe(Loc, BufEnd, P, SA);
@ -1309,15 +1290,6 @@ uint32_t AArch64TargetInfo::getTlsGotRel(uint32_t Type) const {
return Type;
}
bool AArch64TargetInfo::isTlsDynRel(uint32_t Type, const SymbolBody &S) const {
return Type == R_AARCH64_TLSDESC_ADR_PAGE21 ||
Type == R_AARCH64_TLSDESC_LD64_LO12_NC ||
Type == R_AARCH64_TLSDESC_ADD_LO12_NC ||
Type == R_AARCH64_TLSDESC_CALL ||
Type == R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21 ||
Type == R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC;
}
bool AArch64TargetInfo::needsCopyRelImpl(uint32_t Type) const {
switch (Type) {
default:
@ -1494,7 +1466,7 @@ size_t AArch64TargetInfo::relaxTls(uint8_t *Loc, uint8_t *BufEnd, uint32_t Type,
case R_AARCH64_TLSDESC_LD64_LO12_NC:
case R_AARCH64_TLSDESC_ADD_LO12_NC:
case R_AARCH64_TLSDESC_CALL: {
if (canBePreempted(S))
if (canBePreempted(S, Type))
fatal("Unsupported TLS optimization");
uint64_t X = S ? S->getVA<ELF64LE>() : SA;
relocateTlsGdToLe(Type, Loc, BufEnd, P, X);

1
lld/ELF/Target.h
View File

@ -27,7 +27,6 @@ public:
virtual bool isTlsLocalDynamicRel(uint32_t Type) const;
virtual bool isTlsGlobalDynamicRel(uint32_t Type) const;
virtual uint32_t getDynRel(uint32_t Type) const { return Type; }
virtual bool isTlsDynRel(uint32_t Type, const SymbolBody &S) const;
virtual uint32_t getTlsGotRel(uint32_t Type) const { return TlsGotRel; }
virtual void writeGotHeader(uint8_t *Buf) const {}
virtual void writeGotPltHeader(uint8_t *Buf) const {}

6
lld/ELF/Writer.cpp
View File

@ -281,10 +281,10 @@ static bool handleTlsRelocation(uint32_t Type, SymbolBody *Body,
}
return true;
}
if (!canBePreempted(Body))
if (!canBePreempted(Body, Type))
return true;
}
return !Target->isTlsDynRel(Type, *Body);
return false;
}
// The reason we have to do this early scan is as follows
@ -327,7 +327,7 @@ void Writer<ELFT>::scanRelocs(
if (Body)
Body = Body->repl();
bool CBP = canBePreempted(Body);
bool CBP = canBePreempted(Body, Type);
if (handleTlsRelocation<ELFT>(Type, Body, C, RI))
continue;

2
lld/test/ELF/no-inhibit-exec.s
View File

@ -6,7 +6,7 @@
# CHECK: Disassembly of section .text:
# CHECK-NEXT: _start
# CHECK-NEXT: 11000: e8 fb ef fe ff callq -69637
# CHECK-NEXT: 11000: e8 00 00 00 00 callq 0
# next code will not link without noinhibit-exec flag
# because of undefined symbol _bar