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Revert r297813 "[ELF] - Make Bss and BssRelRo sections to be synthetic (#3)." 

I suppose it is the reason of BB fail:
http://lab.llvm.org:8011/builders/clang-cmake-aarch64-lld/builds/921

https://bugs.llvm.org/show_bug.cgi?id=32167

llvm-svn: 297933
This commit is contained in:
George Rimar 2017-03-16 08:44:53 +00:00
parent da59ffae91
commit 47bed8c9f7
7 changed files with 57 additions and 50 deletions
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2
lld/ELF/OutputSections.cpp
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@ -31,6 +31,8 @@ using namespace lld;
using namespace lld::elf;
uint8_t Out::First;
OutputSection *Out::Bss;
OutputSection *Out::BssRelRo;
OutputSection *Out::Opd;
uint8_t *Out::OpdBuf;
PhdrEntry *Out::TlsPhdr;

13
lld/ELF/Relocations.cpp
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@ -479,20 +479,23 @@ template <class ELFT> static void addCopyRelSymbol(SharedSymbol *SS) {
// See if this symbol is in a read-only segment. If so, preserve the symbol's
// memory protection by reserving space in the .bss.rel.ro section.
bool IsReadOnly = isReadOnly<ELFT>(SS);
BssSection *Sec = IsReadOnly ? In<ELFT>::BssRelRo : In<ELFT>::Bss;
uintX_t Off = Sec->reserveSpace(SS->getAlignment<ELFT>(), SymSize);
OutputSection *OSec = IsReadOnly ? Out::BssRelRo : Out::Bss;
// Create a SyntheticSection in Out to hold the .bss and the Copy Reloc.
auto *ISec =
make<CopyRelSection<ELFT>>(IsReadOnly, SS->getAlignment<ELFT>(), SymSize);
OSec->addSection(ISec);
// Look through the DSO's dynamic symbol table for aliases and create a
// dynamic symbol for each one. This causes the copy relocation to correctly
// interpose any aliases.
for (SharedSymbol *Sym : getSymbolsAt<ELFT>(SS)) {
Sym->NeedsCopy = true;
Sym->CopyRelSec = Sec;
Sym->CopyRelSecOff = Off;
Sym->Section = ISec;
Sym->symbol()->IsUsedInRegularObj = true;
}
In<ELFT>::RelaDyn->addReloc({Target->CopyRel, Sec, Off, false, SS, 0});
In<ELFT>::RelaDyn->addReloc({Target->CopyRel, ISec, 0, false, SS, 0});
}
template <class ELFT>

5
lld/ELF/Symbols.cpp
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@ -106,8 +106,7 @@ static typename ELFT::uint getSymVA(const SymbolBody &Body, int64_t &Addend) {
case SymbolBody::SharedKind: {
auto &SS = cast<SharedSymbol>(Body);
if (SS.NeedsCopy)
return SS.CopyRelSec->OutSec->Addr + SS.CopyRelSec->OutSecOff +
SS.CopyRelSecOff;
return SS.Section->OutSec->Addr + SS.Section->OutSecOff;
if (SS.NeedsPltAddr)
return Body.getPltVA<ELFT>();
return 0;
@ -208,7 +207,7 @@ template <class ELFT> OutputSection *SymbolBody::getOutputSection() const {
if (auto *S = dyn_cast<SharedSymbol>(this)) {
if (S->NeedsCopy)
return S->CopyRelSec->OutSec;
return S->Section->OutSec;
return nullptr;
}

5
lld/ELF/Symbols.h
View File

@ -238,9 +238,8 @@ public:
// This field is a pointer to the symbol's version definition.
const void *Verdef;
// CopyRelSec and CopyRelSecOff are significant only when NeedsCopy is true.
InputSection *CopyRelSec;
size_t CopyRelSecOff;
// Section is significant only when NeedsCopy is true.
InputSection *Section = nullptr;
private:
template <class ELFT> const typename ELFT::Sym &getSym() const {

21
lld/ELF/SyntheticSections.cpp
View File

@ -376,14 +376,12 @@ void BuildIdSection<ELFT>::computeHash(
HashFn(HashBuf, Hashes);
}
BssSection::BssSection(StringRef Name)
: SyntheticSection(SHF_ALLOC | SHF_WRITE, SHT_NOBITS, 0, Name) {}
size_t BssSection::reserveSpace(uint32_t Alignment, size_t Size) {
OutSec->updateAlignment(Alignment);
this->Size = alignTo(this->Size, Alignment) + Size;
return this->Size - Size;
}
template <class ELFT>
CopyRelSection<ELFT>::CopyRelSection(bool ReadOnly, uint32_t Alignment,
size_t S)
: SyntheticSection(SHF_ALLOC, SHT_NOBITS, Alignment,
ReadOnly ? ".bss.rel.ro" : ".bss"),
Size(S) {}
template <class ELFT>
void BuildIdSection<ELFT>::writeBuildId(ArrayRef<uint8_t> Buf) {
@ -2264,8 +2262,6 @@ InputSection *ThunkSection<ELFT>::getTargetInputSection() const {
}
InputSection *InX::ARMAttributes;
BssSection *InX::Bss;
BssSection *InX::BssRelRo;
InputSection *InX::Common;
StringTableSection *InX::DynStrTab;
InputSection *InX::Interp;
@ -2318,6 +2314,11 @@ template class elf::BuildIdSection<ELF32BE>;
template class elf::BuildIdSection<ELF64LE>;
template class elf::BuildIdSection<ELF64BE>;
template class elf::CopyRelSection<ELF32LE>;
template class elf::CopyRelSection<ELF32BE>;
template class elf::CopyRelSection<ELF64LE>;
template class elf::CopyRelSection<ELF64BE>;
template class elf::GotSection<ELF32LE>;
template class elf::GotSection<ELF32BE>;
template class elf::GotSection<ELF64LE>;

18
lld/ELF/SyntheticSections.h
View File

@ -153,19 +153,15 @@ private:
uint8_t *HashBuf;
};
// BssSection is used to reserve space for copy relocations. We create two
// instances of this class for .bss and .bss.rel.ro. .bss is used for writable
// symbols, and .bss.rel.ro is used for read-only symbols.
class BssSection final : public SyntheticSection {
// For each copy relocation, we create an instance of this class to
// reserve space in .bss or .bss.rel.ro.
template <class ELFT> class CopyRelSection final : public SyntheticSection {
public:
BssSection(StringRef Name);
CopyRelSection(bool ReadOnly, uint32_t Alignment, size_t Size);
void writeTo(uint8_t *) override {}
bool empty() const override { return getSize() == 0; }
size_t reserveSpace(uint32_t Alignment, size_t Size);
size_t getSize() const override { return Size; }
private:
size_t Size = 0;
size_t getSize() const override { return Size; }
size_t Size;
};
template <class ELFT> class MipsGotSection final : public SyntheticSection {
@ -760,8 +756,6 @@ SymbolBody *addSyntheticLocal(StringRef Name, uint8_t Type, uint64_t Value,
// Linker generated sections which can be used as inputs.
struct InX {
static InputSection *ARMAttributes;
static BssSection *Bss;
static BssSection *BssRelRo;
static InputSection *Common;
static StringTableSection *DynStrTab;
static InputSection *Interp;

43
lld/ELF/Writer.cpp
View File

@ -111,8 +111,8 @@ StringRef elf::getOutputSectionName(StringRef Name) {
}
for (StringRef V :
{".text.", ".rodata.", ".data.rel.ro.", ".data.", ".bss.rel.ro.",
".bss.", ".init_array.", ".fini_array.", ".ctors.", ".dtors.", ".tbss.",
{".text.", ".rodata.", ".data.rel.ro.", ".data.", ".bss.",
".init_array.", ".fini_array.", ".ctors.", ".dtors.", ".tbss.",
".gcc_except_table.", ".tdata.", ".ARM.exidx."}) {
StringRef Prefix = V.drop_back();
if (Name.startswith(V) || Name == Prefix)
@ -327,6 +327,11 @@ template <class ELFT> void Writer<ELFT>::createSyntheticSections() {
auto Add = [](InputSectionBase *Sec) { InputSections.push_back(Sec); };
// Create singleton output sections.
Out::Bss = make<OutputSection>(".bss", SHT_NOBITS, SHF_ALLOC | SHF_WRITE);
Out::BssRelRo =
make<OutputSection>(".bss.rel.ro", SHT_NOBITS, SHF_ALLOC | SHF_WRITE);
In<ELFT>::DynStrTab = make<StringTableSection>(".dynstr", true);
In<ELFT>::Dynamic = make<DynamicSection<ELFT>>();
In<ELFT>::RelaDyn = make<RelocationSection<ELFT>>(
@ -364,11 +369,6 @@ template <class ELFT> void Writer<ELFT>::createSyntheticSections() {
Add(Common);
}
In<ELFT>::Bss = make<BssSection>(".bss");
Add(In<ELFT>::Bss);
In<ELFT>::BssRelRo = make<BssSection>(".bss.rel.ro");
Add(In<ELFT>::BssRelRo);
// Add MIPS-specific sections.
bool HasDynSymTab =
!Symtab<ELFT>::X->getSharedFiles().empty() || Config->pic() ||
@ -618,7 +618,7 @@ template <class ELFT> bool elf::isRelroSection(const OutputSection *Sec) {
return true;
if (In<ELFT>::Got && Sec == In<ELFT>::Got->OutSec)
return true;
if (Sec == In<ELFT>::BssRelRo->OutSec)
if (Sec == Out::BssRelRo)
return true;
StringRef S = Sec->Name;
@ -1168,15 +1168,14 @@ template <class ELFT> void Writer<ELFT>::finalizeSections() {
// Dynamic section must be the last one in this list and dynamic
// symbol table section (DynSymTab) must be the first one.
applySynthetic<ELFT>(
{In<ELFT>::DynSymTab, In<ELFT>::Bss, In<ELFT>::BssRelRo,
In<ELFT>::GnuHashTab, In<ELFT>::HashTab, In<ELFT>::SymTab,
In<ELFT>::ShStrTab, In<ELFT>::StrTab, In<ELFT>::VerDef,
In<ELFT>::DynStrTab, In<ELFT>::GdbIndex, In<ELFT>::Got,
In<ELFT>::MipsGot, In<ELFT>::IgotPlt, In<ELFT>::GotPlt,
In<ELFT>::RelaDyn, In<ELFT>::RelaIplt, In<ELFT>::RelaPlt,
In<ELFT>::Plt, In<ELFT>::Iplt, In<ELFT>::Plt,
In<ELFT>::EhFrameHdr, In<ELFT>::VerSym, In<ELFT>::VerNeed,
In<ELFT>::Dynamic},
{In<ELFT>::DynSymTab, In<ELFT>::GnuHashTab, In<ELFT>::HashTab,
In<ELFT>::SymTab, In<ELFT>::ShStrTab, In<ELFT>::StrTab,
In<ELFT>::VerDef, In<ELFT>::DynStrTab, In<ELFT>::GdbIndex,
In<ELFT>::Got, In<ELFT>::MipsGot, In<ELFT>::IgotPlt,
In<ELFT>::GotPlt, In<ELFT>::RelaDyn, In<ELFT>::RelaIplt,
In<ELFT>::RelaPlt, In<ELFT>::Plt, In<ELFT>::Iplt,
In<ELFT>::Plt, In<ELFT>::EhFrameHdr, In<ELFT>::VerSym,
In<ELFT>::VerNeed, In<ELFT>::Dynamic},
[](SyntheticSection *SS) { SS->finalizeContents(); });
// Some architectures use small displacements for jump instructions.
@ -1205,6 +1204,16 @@ template <class ELFT> void Writer<ELFT>::finalizeSections() {
}
template <class ELFT> void Writer<ELFT>::addPredefinedSections() {
// Add BSS sections.
auto Add = [=](OutputSection *Sec) {
if (!Sec->Sections.empty()) {
Sec->assignOffsets<ELFT>();
OutputSections.push_back(Sec);
}
};
Add(Out::Bss);
Add(Out::BssRelRo);
// ARM ABI requires .ARM.exidx to be terminated by some piece of data.
// We have the terminater synthetic section class. Add that at the end.
auto *OS = dyn_cast_or_null<OutputSection>(findSection(".ARM.exidx"));