Re: [PATCH] PR ld/18720: Properly merge hidden versioned symbol

[Mike Frysinger <vapier at gentoo dot org>]

On 01 Feb 2016 12:47, H.J. Lu wrote:
> On Mon, Feb 1, 2016 at 12:22 PM, Mike Frysinger <vapier@gentoo.org> wrote:
> > On 01 Aug 2015 07:07, H.J. Lu wrote:
> >> On Sun, Jul 26, 2015 at 03:15:50PM -0700, H.J. Lu wrote:
> >> > The non-default versioned symbol can only be merged with the versioned
> >> > symbol with the same symbol version.  _bfd_elf_merge_symbol should
> >> > check the symbol version before merging the new non-default versioned
> >> > symbol with the existing symbol.  _bfd_elf_link_hash_copy_indirect can't
> >> > copy any references to the non-default versioned symbol.   We need to
> >> > bind a symbol locally when linking executable if it is locally defined,
> >> > non-default versioned, not referenced by shared library and not exported.
> >> > ---
> >> > bfd/
> >> >
> >> >     PR ld/18720
> >> >     * elf-bfd.h (elf_link_hash_entry): Add nondeflt_version.
> >> >     * elflink.c (_bfd_elf_merge_symbol): Add a parameter to indicate
> >> >     if the new symbol matches the existing one.  The new non-default
> >> >     versioned symbol symbol matches the existing symbol if they have
> >> >     the same symbol version. Update the existing symbol only if they
> >> >     match.
> >> >     (_bfd_elf_add_default_symbol): Update call to
> >> >     _bfd_elf_merge_symbol.
> >> >     (elf_link_add_object_symbols): Override a definition only if the
> >> >     new symbol matches the existing one.
> >> >     (_bfd_elf_link_hash_copy_indirect): Don't copy any references to
> >> >     the non-default versioned symbol.
> >> >     (elf_link_output_extsym): Bind a symbol locally when linking
> >> >     executable if it is locally defined, non-default versioned, not
> >> >     referenced by shared library and not exported.
> >>
> >> Here is the upated patch which uses the existing "hidden" field in
> >> elf_link_hash_entry.  Any objections, comments?
> >
> > this breaks asan.  simple test case:
> > $ echo 'main() { fork(); }' > test.c
> > $ gcc -fsanitize=address -c test.c
> > $ gcc -fsanitize=address test.o
> > ld: /usr/lib/gcc/x86_64-pc-linux-gnu/5.3.0/libasan.so: undefined reference to symbol 'fork@GLIBC_2.2.5'
> > /lib64/libpthread.so.0: error adding symbols: DSO missing from command line
> > collect2: error: ld returned 1 exit status
> >
> > i'm guessing this will also break any library that links against pthread
> > but the main app itself doesn't.
> 
> Please open a binutils bug.

done:
https://sourceware.org/bugzilla/show_bug.cgi?id=19553
-mike

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