Re: [PATCH v2] gdbserver: Clear X86_XSTATE_MPX bits in xcr0 on x32

["H.J. Lu" <hjl.tools@gmail.com>]

On Sat, Mar 23, 2024 at 9:39 AM Andrew Burgess <aburgess@redhat.com> wrote:
>
> Andrew Burgess <aburgess@redhat.com> writes:
>
> > "H.J. Lu" <hjl.tools@gmail.com> writes:
> >
> >> Since MPX isn't available for x32, we should clear X86_XSTATE_MPX bits
> >> on x32.
> >>
> >>      PR server/31511
> >>      * linux-x86-low.cc (x86_linux_read_description): Clear
> >>      X86_XSTATE_MPX bits in xcr0 on x32.
> >> ---
> >>  gdbserver/linux-x86-low.cc | 4 ++++
> >>  1 file changed, 4 insertions(+)
> >>
> >> diff --git a/gdbserver/linux-x86-low.cc b/gdbserver/linux-x86-low.cc
> >> index 3af0a009052..933d1fb012a 100644
> >> --- a/gdbserver/linux-x86-low.cc
> >> +++ b/gdbserver/linux-x86-low.cc
> >> @@ -938,6 +938,10 @@ x86_linux_read_description (void)
> >>        xcr0 = xstateregs[(I386_LINUX_XSAVE_XCR0_OFFSET
> >>                           / sizeof (uint64_t))];
> >>
> >> +      /* No MPX on x32.  */
> >> +      if (machine == EM_X86_64 && !is_elf64)
> >> +        xcr0 &= ~X86_XSTATE_MPX;
> >
> > Hi,
> >
> > I have a series in flight that conflicts with this change:
> >
> >   https://inbox.sourceware.org/gdb-patches/cover.1706801009.git.aburgess@redhat.com
> >
> > And so I'm trying to resolve the conflicts.
>
> OK, I think I may have resolved the conflict.  I'm still unable to test
> x32 ABI, would you mind applying this series:
>
>   https://inbox.sourceware.org/gdb-patches/cover.1711211528.git.aburgess@redhat.com
>
> and checking that your x32 use case still behaves as you expect.  The
> merge of our work occurs in this patch:
>
>   https://inbox.sourceware.org/gdb-patches/a76168beacd9bb79b72ca1a0d26995abd770104c.1711211528.git.aburgess@redhat.com
>
> Also, I invite you to take a look at this additional patch which adds an
> extra assert that relates to your work:
>
>   https://inbox.sourceware.org/gdb-patches/159cadba5ba824579cbc6426cb26f45228eda0a7.1711211528.git.aburgess@redhat.com
>
> Any feedback would be great.
>

I applied the whole patch series from

https://patchwork.sourceware.org/project/gdb/list/?series=32189

Both gdb and gdbserver work on x32.

Thanks.

-- 
H.J.