[lld] r261651 - [lld] [ELF/AArch64] Fix R_AARCH64_ABS64 in Shared mode
Rafael Espíndola via llvm-commits
llvm-commits at lists.llvm.org
Tue Feb 23 12:24:52 PST 2016
Fixed in r261678.
On 23 February 2016 at 15:04, Rafael Espíndola
<rafael.espindola at gmail.com> wrote:
> At the very least the test is wrong. This symbol foo can be preempted
> and we cannot use a relative relocation.
>
> Cheers,
> Rafael
>
>
> On 23 February 2016 at 11:54, Adhemerval Zanella via llvm-commits
> <llvm-commits at lists.llvm.org> wrote:
>> Author: azanella
>> Date: Tue Feb 23 10:54:40 2016
>> New Revision: 261651
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=261651&view=rev
>> Log:
>> [lld] [ELF/AArch64] Fix R_AARCH64_ABS64 in Shared mode
>>
>> This patch fixes the R_AARCH64_ABS64 relocation when used in shared mode,
>> where it requires a dynamic R_AARCH64_RELATIVE relocation. To correct set
>> the addend on the dynamic relocation (since it will be used by the dynamic
>> linker), a new TargetInfo specific hook was created (getDynRelativeAddend)
>> to get the correct addend based on relocation type.
>>
>> The patch fixes the issues when creating shared library code against
>> {init,fini}_array, where it issues R_AARCH64_ABS64 relocation against
>> local symbols.
>>
>> Added:
>> lld/trunk/test/ELF/aarch64-abs64-dyn.s
>> Modified:
>> lld/trunk/ELF/OutputSections.cpp
>> lld/trunk/ELF/OutputSections.h
>> lld/trunk/ELF/Target.cpp
>> lld/trunk/ELF/Writer.cpp
>>
>> Modified: lld/trunk/ELF/OutputSections.cpp
>> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/OutputSections.cpp?rev=261651&r1=261650&r2=261651&view=diff
>> ==============================================================================
>> --- lld/trunk/ELF/OutputSections.cpp (original)
>> +++ lld/trunk/ELF/OutputSections.cpp Tue Feb 23 10:54:40 2016
>> @@ -253,11 +253,18 @@ template <class ELFT> void RelocationSec
>>
>> if (IsRela) {
>> uintX_t VA = 0;
>> - if (Rel.UseSymVA)
>> + if (Rel.UseSymVA) {
>> VA = Sym->getVA<ELFT>();
>> - else if (Rel.TargetSec)
>> + } else if (Rel.TargetSec) {
>> VA = Rel.TargetSec->getOffset(Rel.OffsetInTargetSec) +
>> Rel.TargetSec->OutSec->getVA();
>> + } else if (!Sym && Rel.OffsetSec) {
>> + // Sym equal to nullptr means the dynamic relocation is against a
>> + // local symbol represented by Rel.SymIndex.
>> + ObjectFile<ELFT> *File = Rel.OffsetSec->getFile();
>> + const Elf_Sym *LocalSym = File->getLocalSymbol(Rel.SymIndex);
>> + VA = getLocalTarget(*File, *LocalSym, 0);
>> + }
>> reinterpret_cast<Elf_Rela *>(P)->r_addend = Rel.Addend + VA;
>> }
>>
>> @@ -862,7 +869,6 @@ elf2::getLocalRelTarget(const ObjectFile
>> const Elf_Rel_Impl<ELFT, IsRela> &RI,
>> typename ELFFile<ELFT>::uintX_t Addend) {
>> typedef typename ELFFile<ELFT>::Elf_Sym Elf_Sym;
>> - typedef typename ELFFile<ELFT>::uintX_t uintX_t;
>>
>> // PPC64 has a special relocation representing the TOC base pointer
>> // that does not have a corresponding symbol.
>> @@ -875,10 +881,22 @@ elf2::getLocalRelTarget(const ObjectFile
>> if (!Sym)
>> fatal("Unsupported relocation without symbol");
>>
>> - InputSectionBase<ELFT> *Section = File.getSection(*Sym);
>> + return getLocalTarget(File, *Sym, Addend);
>> +}
>> +
>> +template <class ELFT>
>> +typename ELFFile<ELFT>::uintX_t
>> +elf2::getLocalTarget(const ObjectFile<ELFT> &File,
>> + const typename ELFFile<ELFT>::Elf_Sym &Sym,
>> + typename ELFFile<ELFT>::uintX_t Addend) {
>> + typedef typename ELFFile<ELFT>::uintX_t uintX_t;
>> +
>> + InputSectionBase<ELFT> *Section = File.getSection(Sym);
>> + if (!Section)
>> + return Addend;
>>
>> - if (Sym->getType() == STT_TLS)
>> - return (Section->OutSec->getVA() + Section->getOffset(*Sym) + Addend) -
>> + if (Sym.getType() == STT_TLS)
>> + return (Section->OutSec->getVA() + Section->getOffset(Sym) + Addend) -
>> Out<ELFT>::TlsPhdr->p_vaddr;
>>
>> // According to the ELF spec reference to a local symbol from outside
>> @@ -888,8 +906,8 @@ elf2::getLocalRelTarget(const ObjectFile
>> if (Section == &InputSection<ELFT>::Discarded || !Section->isLive())
>> return Addend;
>>
>> - uintX_t Offset = Sym->st_value;
>> - if (Sym->getType() == STT_SECTION) {
>> + uintX_t Offset = Sym.st_value;
>> + if (Sym.getType() == STT_SECTION) {
>> Offset += Addend;
>> Addend = 0;
>> }
>> @@ -1647,5 +1665,18 @@ template uint64_t getLocalRelTarget(cons
>> template uint64_t getLocalRelTarget(const ObjectFile<ELF64BE> &,
>> const ELFFile<ELF64BE>::Elf_Rela &,
>> uint64_t);
>> +
>> +template uint32_t getLocalTarget(const ObjectFile<ELF32LE> &,
>> + const ELFFile<ELF32LE>::Elf_Sym &Sym,
>> + uint32_t);
>> +template uint32_t getLocalTarget(const ObjectFile<ELF32BE> &,
>> + const ELFFile<ELF32BE>::Elf_Sym &Sym,
>> + uint32_t);
>> +template uint64_t getLocalTarget(const ObjectFile<ELF64LE> &,
>> + const ELFFile<ELF64LE>::Elf_Sym &Sym,
>> + uint64_t);
>> +template uint64_t getLocalTarget(const ObjectFile<ELF64BE> &,
>> + const ELFFile<ELF64BE>::Elf_Sym &Sym,
>> + uint64_t);
>> }
>> }
>>
>> Modified: lld/trunk/ELF/OutputSections.h
>> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/OutputSections.h?rev=261651&r1=261650&r2=261651&view=diff
>> ==============================================================================
>> --- lld/trunk/ELF/OutputSections.h (original)
>> +++ lld/trunk/ELF/OutputSections.h Tue Feb 23 10:54:40 2016
>> @@ -53,6 +53,12 @@ getLocalRelTarget(const ObjectFile<ELFT>
>> const llvm::object::Elf_Rel_Impl<ELFT, IsRela> &Rel,
>> typename llvm::object::ELFFile<ELFT>::uintX_t Addend);
>>
>> +template <class ELFT>
>> +typename llvm::object::ELFFile<ELFT>::uintX_t
>> +getLocalTarget(const ObjectFile<ELFT> &File,
>> + const typename llvm::object::ELFFile<ELFT>::Elf_Sym &Sym,
>> + typename llvm::object::ELFFile<ELFT>::uintX_t Addend);
>> +
>> bool canBePreempted(const SymbolBody *Body, bool NeedsGot);
>>
>> // This represents a section in an output file.
>> @@ -187,6 +193,7 @@ template <class ELFT> struct DynamicRelo
>> } OKind;
>>
>> SymbolBody *Sym = nullptr;
>> + uint32_t SymIndex = 0;
>> InputSectionBase<ELFT> *OffsetSec = nullptr;
>> uintX_t OffsetInSec = 0;
>> bool UseSymVA = false;
>> @@ -207,6 +214,12 @@ template <class ELFT> struct DynamicRelo
>> OffsetInSec(OffsetInSec), UseSymVA(UseSymVA), Addend(Addend) {}
>>
>> DynamicReloc(uint32_t Type, InputSectionBase<ELFT> *OffsetSec,
>> + uintX_t OffsetInSec, bool UseSymVA, uint32_t SymIndex,
>> + uintX_t Addend)
>> + : Type(Type), OKind(Off_Sec), SymIndex(SymIndex), OffsetSec(OffsetSec),
>> + OffsetInSec(OffsetInSec), UseSymVA(UseSymVA), Addend(Addend) {}
>> +
>> + DynamicReloc(uint32_t Type, InputSectionBase<ELFT> *OffsetSec,
>> uintX_t OffsetInSec, InputSectionBase<ELFT> *TargetSec,
>> uintX_t OffsetInTargetSec, uintX_t Addend)
>> : Type(Type), OKind(Off_Sec), OffsetSec(OffsetSec),
>> @@ -254,6 +267,7 @@ private:
>>
>> template <class ELFT>
>> class RelocationSection final : public OutputSectionBase<ELFT> {
>> + typedef typename llvm::object::ELFFile<ELFT>::Elf_Sym Elf_Sym;
>> typedef typename llvm::object::ELFFile<ELFT>::Elf_Rel Elf_Rel;
>> typedef typename llvm::object::ELFFile<ELFT>::Elf_Rela Elf_Rela;
>> typedef typename llvm::object::ELFFile<ELFT>::uintX_t uintX_t;
>>
>> Modified: lld/trunk/ELF/Target.cpp
>> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Target.cpp?rev=261651&r1=261650&r2=261651&view=diff
>> ==============================================================================
>> --- lld/trunk/ELF/Target.cpp (original)
>> +++ lld/trunk/ELF/Target.cpp Tue Feb 23 10:54:40 2016
>> @@ -182,6 +182,7 @@ public:
>> unsigned getTlsGotRel(unsigned Type) const override;
>> bool isTlsDynRel(unsigned Type, const SymbolBody &S) const override;
>> bool needsCopyRelImpl(uint32_t Type) const override;
>> + bool needsDynRelative(unsigned Type) const override;
>> bool needsGot(uint32_t Type, SymbolBody &S) const override;
>> PltNeed needsPlt(uint32_t Type, const SymbolBody &S) const override;
>> void relocateOne(uint8_t *Loc, uint8_t *BufEnd, uint32_t Type, uint64_t P,
>> @@ -1212,6 +1213,7 @@ void PPC64TargetInfo::relocateOne(uint8_
>>
>> AArch64TargetInfo::AArch64TargetInfo() {
>> CopyRel = R_AARCH64_COPY;
>> + RelativeRel = R_AARCH64_RELATIVE;
>> IRelativeRel = R_AARCH64_IRELATIVE;
>> GotRel = R_AARCH64_GLOB_DAT;
>> PltRel = R_AARCH64_JUMP_SLOT;
>> @@ -1319,6 +1321,10 @@ bool AArch64TargetInfo::needsCopyRelImpl
>> }
>> }
>>
>> +bool AArch64TargetInfo::needsDynRelative(unsigned Type) const {
>> + return Config->Shared && Type == R_AARCH64_ABS64;
>> +}
>> +
>> bool AArch64TargetInfo::needsGot(uint32_t Type, SymbolBody &S) const {
>> switch (Type) {
>> case R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
>>
>> Modified: lld/trunk/ELF/Writer.cpp
>> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp?rev=261651&r1=261650&r2=261651&view=diff
>> ==============================================================================
>> --- lld/trunk/ELF/Writer.cpp (original)
>> +++ lld/trunk/ELF/Writer.cpp Tue Feb 23 10:54:40 2016
>> @@ -311,9 +311,16 @@ void Writer<ELFT>::scanRelocs(
>> if (handleTlsRelocation<ELFT>(Type, Body, C, RI))
>> continue;
>>
>> - if (Target->needsDynRelative(Type))
>> - Out<ELFT>::RelaDyn->addReloc({Target->RelativeRel, &C, RI.r_offset, true,
>> - Body, getAddend<ELFT>(RI)});
>> + if (Target->needsDynRelative(Type)) {
>> + // If Body is null it means the relocation is against a local symbol
>> + // and thus we need to pass the local symbol index instead.
>> + if (Body)
>> + Out<ELFT>::RelaDyn->addReloc({Target->RelativeRel, &C, RI.r_offset, true,
>> + Body, getAddend<ELFT>(RI)});
>> + else
>> + Out<ELFT>::RelaDyn->addReloc({Target->RelativeRel, &C, RI.r_offset, false,
>> + SymIndex, getAddend<ELFT>(RI)});
>> + }
>>
>> // MIPS has a special rule to create GOTs for local symbols.
>> if (Config->EMachine == EM_MIPS && !canBePreempted(Body, true) &&
>>
>> Added: lld/trunk/test/ELF/aarch64-abs64-dyn.s
>> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/aarch64-abs64-dyn.s?rev=261651&view=auto
>> ==============================================================================
>> --- lld/trunk/test/ELF/aarch64-abs64-dyn.s (added)
>> +++ lld/trunk/test/ELF/aarch64-abs64-dyn.s Tue Feb 23 10:54:40 2016
>> @@ -0,0 +1,21 @@
>> +// REQUIRES: aarch64
>> +// RUN: llvm-mc -filetype=obj -triple=aarch64-none-linux %s -o %t.o
>> +
>> +// Creates a R_AARCH64_ABS64 relocation against _foo. It will be used on a
>> +// shared object to check for a dynamic relocation creation.
>> +.globl _foo
>> +_foo:
>> + ret
>> +_foo_init_array:
>> + .xword _foo
>> +
>> +// RUN: ld.lld -shared -o %t.so %t.o
>> +// RUN: llvm-readobj -symbols -dyn-relocations %t.so | FileCheck %s
>> +
>> +// CHECK: Dynamic Relocations {
>> +// CHECK-NEXT: {{.*}} R_AARCH64_RELATIVE - [[FOO_ADDR:[0-9xa-f]+]]
>> +
>> +// CHECK: Symbols [
>> +// CHECK: Symbol {
>> +// CHECK: Name: _foo
>> +// CHECK: Value: [[FOO_ADDR]]
>>
>>
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