V2 [PATCH] elf: Check multiple definition when defining hidden version

[H.J. Lu]

On Wed, Dec 2, 2020 at 12:05 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Wed, Dec 2, 2020 at 6:51 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > When defining a hidden version from the nondefault version of the symbol,
> > check if there is already a definition to avoid multiple definitions:
> >
> > [hjl@gnu-cfl-2 pr26978]$ gcc -o y main.o libbar.so -Wl,-R,.
> > /usr/local/bin/ld: libbar.so:(*IND*+0x0): multiple definition of `foo@v1'; libbar.so:(.text+0x0): first defined here
> > collect2: error: ld returned 1 exit status
> > [hjl@gnu-cfl-2 pr26978]$ readelf --dyn-syms libbar.so
> >
> > Symbol table '.dynsym' contains 5 entries:
> >    Num:    Value          Size Type    Bind   Vis      Ndx Name
> >      0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
> >      1: 0000000000001000     0 OBJECT  GLOBAL DEFAULT    7 foo@v1
> >      2: 0000000000001001     0 OBJECT  WEAK   DEFAULT    7 foo@@v1
> >      3: 0000000000001000     0 OBJECT  GLOBAL DEFAULT    7 foo_v1
> >      4: 0000000000000000     0 OBJECT  GLOBAL DEFAULT  ABS v1
> > [hjl@gnu-cfl-2 pr26978]$
> >
> > bfd/
> >
> >         PR ld/26978
> >         * elflink.c (_bfd_elf_add_default_symbol): Check if there is
> >         already a definition before defining an indirection.
> >
> > ld/
> >
> >         PR ld/26978
> >         * testsuite/ld-elf/pr26978.ver: New file.
> >         * testsuite/ld-elf/pr26978a.d: Likewise.
> >         * testsuite/ld-elf/pr26978a.s: Likewise.
> >         * testsuite/ld-elf/pr26978b.d: Likewise.
> >         * testsuite/ld-elf/pr26978b.s: Likewise.
> > ---
> >  bfd/elflink.c                   | 13 +++++++++++++
> >  ld/testsuite/ld-elf/pr26978.ver |  1 +
> >  ld/testsuite/ld-elf/pr26978a.d  |  6 ++++++
> >  ld/testsuite/ld-elf/pr26978a.s  |  7 +++++++
> >  ld/testsuite/ld-elf/pr26978b.d  |  6 ++++++
> >  ld/testsuite/ld-elf/pr26978b.s  |  6 ++++++
> >  6 files changed, 39 insertions(+)
> >  create mode 100644 ld/testsuite/ld-elf/pr26978.ver
> >  create mode 100644 ld/testsuite/ld-elf/pr26978a.d
> >  create mode 100644 ld/testsuite/ld-elf/pr26978a.s
> >  create mode 100644 ld/testsuite/ld-elf/pr26978b.d
> >  create mode 100644 ld/testsuite/ld-elf/pr26978b.s
> >
> > diff --git a/bfd/elflink.c b/bfd/elflink.c
> > index 512c5044b3..65dc106656 100644
> > --- a/bfd/elflink.c
> > +++ b/bfd/elflink.c
> > @@ -2077,6 +2077,19 @@ _bfd_elf_add_default_symbol (bfd *abfd,
> >                               &type_change_ok, &size_change_ok, &matched))
> >      return FALSE;
> >
> > +  /* Check if there is already a definition before defining an
> > +     indirection.  */
> > +  if ((hi->root.type == bfd_link_hash_defined
> > +       || hi->root.type == bfd_link_hash_defweak)
> > +      && (hi->def_regular || ELF_COMMON_DEF_P (hi)))
> > +    {
> > +      /* Handle a multiple definition.  */
> > +      (*info->callbacks->multiple_definition) (info, &hi->root,
> > +                                              abfd, sec,
> > +                                              hi->root.u.def.value);
> > +      return TRUE;
> > +    }
> > +
> >    if (skip)
> >      return TRUE;
> >
>
> This failed to build glibc.
>

Here is the updated patch with

+  /* Check if there is already a regular definition before defining an
+     indirection from the nondefault version of the symbol in a regular
+     object.  */
+  if ((abfd->flags & DYNAMIC) == 0
+      && (hi->root.type == bfd_link_hash_defined
+   || hi->root.type == bfd_link_hash_defweak)
+      && (hi->def_regular || ELF_COMMON_DEF_P (hi)))
+    {
+      /* Handle a multiple definition.  */
+      (*info->callbacks->multiple_definition) (info, &hi->root,
+        abfd, sec,
+        hi->root.u.def.value);
+      return TRUE;
+    }
+

OK for master branch?

-- 
H.J.
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