[lld] r291944 - Don't add DT_INIT/DT_FINI for undef and shared symbols.

[Rui Ueyama via llvm-commits]

Please go ahead.

On Wed, Jan 18, 2017 at 10:53 AM, Rafael Avila de Espindola <
rafael.espindola at gmail.com> wrote:

>
> This should probably be ported to 4.0. I can take care of porting it if
> it is OK.
>
> Cheers,
> Rafael
>
> Rafael Espindola via llvm-commits <llvm-commits at lists.llvm.org> writes:
>
> > Author: rafael
> > Date: Fri Jan 13 13:18:11 2017
> > New Revision: 291944
> >
> > URL: http://llvm.org/viewvc/llvm-project?rev=291944&view=rev
> > Log:
> > Don't add DT_INIT/DT_FINI for undef and shared symbols.
> >
> > The freebsd dynamic linker doesn't check if the value is null (and it
> > is reasonable for it to do that). That means that producing a .so with
> > a null DT_INIT/DT_FINI causes the base address to be called.
> >
> > This should fix the libreoffice build.
> >
> > Modified:
> >     lld/trunk/ELF/SymbolTable.cpp
> >     lld/trunk/ELF/SymbolTable.h
> >     lld/trunk/ELF/SyntheticSections.cpp
> >     lld/trunk/test/ELF/init-fini.s
> >
> > Modified: lld/trunk/ELF/SymbolTable.cpp
> > URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/
> SymbolTable.cpp?rev=291944&r1=291943&r2=291944&view=diff
> > ============================================================
> ==================
> > --- lld/trunk/ELF/SymbolTable.cpp (original)
> > +++ lld/trunk/ELF/SymbolTable.cpp Fri Jan 13 13:18:11 2017
> > @@ -468,6 +468,14 @@ template <class ELFT> SymbolBody *Symbol
> >  }
> >
> >  template <class ELFT>
> > +SymbolBody *SymbolTable<ELFT>::findDefined(StringRef Name) {
> > +  if (SymbolBody *S = find(Name))
> > +    if (S->isDefined() && !S->isShared())
> > +      return S;
> > +  return nullptr;
> > +}
> > +
> > +template <class ELFT>
> >  void SymbolTable<ELFT>::addLazyArchive(ArchiveFile *F,
> >                                         const object::Archive::Symbol
> Sym) {
> >    Symbol *S;
> >
> > Modified: lld/trunk/ELF/SymbolTable.h
> > URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/
> SymbolTable.h?rev=291944&r1=291943&r2=291944&view=diff
> > ============================================================
> ==================
> > --- lld/trunk/ELF/SymbolTable.h (original)
> > +++ lld/trunk/ELF/SymbolTable.h Fri Jan 13 13:18:11 2017
> > @@ -82,6 +82,7 @@ public:
> >    void scanVersionScript();
> >
> >    SymbolBody *find(StringRef Name);
> > +  SymbolBody *findDefined(StringRef Name);
> >
> >    void trace(StringRef Name);
> >    void wrap(StringRef Name);
> >
> > Modified: lld/trunk/ELF/SyntheticSections.cpp
> > URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/
> SyntheticSections.cpp?rev=291944&r1=291943&r2=291944&view=diff
> > ============================================================
> ==================
> > --- lld/trunk/ELF/SyntheticSections.cpp (original)
> > +++ lld/trunk/ELF/SyntheticSections.cpp Fri Jan 13 13:18:11 2017
> > @@ -883,9 +883,9 @@ template <class ELFT> void DynamicSectio
> >      add({DT_FINI_ARRAYSZ, Out<ELFT>::FiniArray, Entry::SecSize});
> >    }
> >
> > -  if (SymbolBody *B = Symtab<ELFT>::X->find(Config->Init))
> > +  if (SymbolBody *B = Symtab<ELFT>::X->findDefined(Config->Init))
> >      add({DT_INIT, B});
> > -  if (SymbolBody *B = Symtab<ELFT>::X->find(Config->Fini))
> > +  if (SymbolBody *B = Symtab<ELFT>::X->findDefined(Config->Fini))
> >      add({DT_FINI, B});
> >
> >    bool HasVerNeed = In<ELFT>::VerNeed->getNeedNum() != 0;
> >
> > Modified: lld/trunk/test/ELF/init-fini.s
> > URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/
> init-fini.s?rev=291944&r1=291943&r2=291944&view=diff
> > ============================================================
> ==================
> > --- lld/trunk/test/ELF/init-fini.s (original)
> > +++ lld/trunk/test/ELF/init-fini.s Fri Jan 13 13:18:11 2017
> > @@ -17,11 +17,22 @@
> >  // RUN: ld.lld -shared %t -o %t2 -init=_foo -fini=_bar
> >  // RUN: llvm-readobj -dynamic-table %t2 | FileCheck --check-prefix=OVR
> %s
> >
> > -// Should add a dynamic table entry even if a given symbol stay
> undefined
> > +// Don't add an entry for undef. The freebsd dynamic linker doesn't
> > +// check if the value is null. If it is, it will just call the
> > +// load address.
> >  // RUN: ld.lld -shared %t -o %t2 -init=_undef -fini=_undef
> >  // RUN: llvm-readobj -dynamic-table %t2 | FileCheck
> --check-prefix=UNDEF %s
> > -// UNDEF: INIT 0x0
> > -// UNDEF: FINI 0x0
> > +// UNDEF-NOT: INIT
> > +// UNDEF-NOT: FINI
> > +
> > +// Don't add an entry for shared. For the same reason as undef.
> > +// RUN: ld.lld -shared %t -o %t.so
> > +// RUN: echo > %t.s
> > +// RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %t.s -o %t2.o
> > +// RUN: ld.lld -shared %t2.o %t.so -o %t2
> > +// RUN: llvm-readobj -dynamic-table %t2 | FileCheck
> --check-prefix=SHARED %s
> > +// SHARED-NOT: INIT
> > +// SHARED-NOT: FINI
> >
> >  // Should not add new entries to the symbol table
> >  // and should not require given symbols to be resolved
> >
> >
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>
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