Re: [PATCH] i386: Change offset of __private_ss to 0x30

[Florian Weimer <fweimer at redhat dot com>]

On 05/30/2018 06:47 PM, H.J. Lu wrote:
> On Wed, May 30, 2018 at 9:43 AM, Florian Weimer <fweimer@redhat.com> wrote:
> > On 05/30/2018 04:49 PM, H.J. Lu wrote:
> > > diff --git a/sysdeps/i386/nptl/tls.h b/sysdeps/i386/nptl/tls.h
> > > index 6c36e58e9c..afb71ce431 100644
> > > --- a/sysdeps/i386/nptl/tls.h
> > > +++ b/sysdeps/i386/nptl/tls.h
> > > @@ -43,11 +43,16 @@ typedef struct
> > >      int gscope_flag;
> > >      int __glibc_reserved1;
> > >      /* Reservation of some values for the TM ABI.  */
> > > -  void *__private_tm[4];
> > > +  void *__private_tm[3];
> > >      /* GCC split stack support.  */
> > >      void *__private_ss;
> > > +  void *__glibc_reserved2;
> > >    } tcbhead_t;
> >
> >
> > What's the state of TM in GCC?  Has it already been removed?
>
> libitm has its own issue:
>
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85988
>
> Fortunately, only the first 2 elements in __private_tm are used by
> libitm.

Looks like the reuse of the TM fields was actually deliberate:

  <https://sourceware.org/bugzilla/show_bug.cgi?id=10686>

But the offsets are still wrong.

The question still remains whether we still need libitm.

Thanks,
Florian