On Tue, Jan 19, 2021 at 5:51 AM Adhemerval Zanella via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
>
>
> On 18/01/2021 13:24, Szabolcs Nagy via Libc-alpha wrote:
> > From: "H.J. Lu" <hjl.tools@gmail.com>
> >
> > In static PIE, set the default _dl_sysinfo in _dl_aux_init, instead of
> > using the RELATIVE relocation to intialize it.
> >
> > This is needed for fixing bug 27072 on x86.
> > ---
> >  elf/dl-support.c | 12 +++++++++++-
> >  1 file changed, 11 insertions(+), 1 deletion(-)
> >
> > diff --git a/elf/dl-support.c b/elf/dl-support.c
> > index 384080dd80..5acd59290f 100644
> > --- a/elf/dl-support.c
> > +++ b/elf/dl-support.c
> > @@ -200,7 +200,12 @@ struct dl_scope_free_list *_dl_scope_free_list;
> >
> >  #ifdef NEED_DL_SYSINFO
> >  /* Needed for improved syscall handling on at least x86/Linux.  */
> > -uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
> > +uintptr_t _dl_sysinfo
> > +/* NB: Avoid RELATIVE relocation in static PIE.  */
> > +# ifndef BUILD_PIE_DEFAULT
> > +  = DL_SYSINFO_DEFAULT
> > +# endif
> > +;
> >  #endif
> >  #ifdef NEED_DL_SYSINFO_DSO
> >  /* Address of the ELF headers in the vsyscall page.  */
> > @@ -238,6 +243,11 @@ _dl_aux_init (ElfW(auxv_t) *av)
> >    uid_t uid = 0;
> >    gid_t gid = 0;
> >
> > +#if defined NEED_DL_SYSINFO && BUILD_PIE_DEFAULT
> > +  /* NB: Avoid RELATIVE relocation in static PIE.  */
> > +  GL(dl_sysinfo) = DL_SYSINFO_DEFAULT;
> > +#endif
> > +
>
> Couldn't we make it the default instead?
>
> >    _dl_auxv = av;
> >    for (; av->a_type != AT_NULL; ++av)
> >      switch (av->a_type)
> >

Like this?

-- 
H.J.