x86: In ld.so, diagnose missing APX support in APX-only builds

  At this point, this is mainly a tool for testing the early ld.so
CPU compatibility diagnostics: GCC uses the new instructions in most
functions, so it's easy to spot if some of the early code is not
built correctly.  (No such problems were flagged for the current
tree.)

---
 sysdeps/x86/dl-get-cpu-features.c | 5 +++++
 1 file changed, 5 insertions(+)


base-commit: 3a3a4497421422aa854c855cbe5110ca7d598ffc
  

On Thu, Apr 25, 2024 at 5:11 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> At this point, this is mainly a tool for testing the early ld.so
> CPU compatibility diagnostics: GCC uses the new instructions in most
> functions, so it's easy to spot if some of the early code is not
> built correctly.  (No such problems were flagged for the current
> tree.)
>
> ---
>  sysdeps/x86/dl-get-cpu-features.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/sysdeps/x86/dl-get-cpu-features.c b/sysdeps/x86/dl-get-cpu-features.c
> index 4d6c5c59a6..579d02d638 100644
> --- a/sysdeps/x86/dl-get-cpu-features.c
> +++ b/sysdeps/x86/dl-get-cpu-features.c
> @@ -64,6 +64,11 @@ Fatal glibc error: CPU does not support x86-64-v%d\n", 4);
>  #    endif /* ISA level 4 */
>  #   endif /* ISA level 3 */
>  #  endif /* ISA level 2 */
> +# ifdef GCCMACRO__APX_F__
> +      if (!CPU_FEATURE_USABLE_P (cpu_features, APX_F))
> +       _dl_fatal_printf ("\
> +Fatal glibc error: CPU does not support APX\n");
> +# endif
>  # endif /* IS_IN (rtld) */
>      }
>  }
>
> base-commit: 3a3a4497421422aa854c855cbe5110ca7d598ffc
>

LGTM.

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>

BTW, this patch:

https://patchwork.sourceware.org/project/glibc/list/?series=33161

is also required.

Thanks.
  

On Thu, Apr 25, 2024 at 7:50 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Thu, Apr 25, 2024 at 5:11 AM Florian Weimer <fweimer@redhat.com> wrote:
> >
> > At this point, this is mainly a tool for testing the early ld.so
> > CPU compatibility diagnostics: GCC uses the new instructions in most
> > functions, so it's easy to spot if some of the early code is not
> > built correctly.  (No such problems were flagged for the current
> > tree.)
> >
> > ---
> >  sysdeps/x86/dl-get-cpu-features.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/sysdeps/x86/dl-get-cpu-features.c b/sysdeps/x86/dl-get-cpu-features.c
> > index 4d6c5c59a6..579d02d638 100644
> > --- a/sysdeps/x86/dl-get-cpu-features.c
> > +++ b/sysdeps/x86/dl-get-cpu-features.c
> > @@ -64,6 +64,11 @@ Fatal glibc error: CPU does not support x86-64-v%d\n", 4);
> >  #    endif /* ISA level 4 */
> >  #   endif /* ISA level 3 */
> >  #  endif /* ISA level 2 */
> > +# ifdef GCCMACRO__APX_F__
> > +      if (!CPU_FEATURE_USABLE_P (cpu_features, APX_F))
> > +       _dl_fatal_printf ("\
> > +Fatal glibc error: CPU does not support APX\n");
> > +# endif
> >  # endif /* IS_IN (rtld) */
> >      }
> >  }
> >
> > base-commit: 3a3a4497421422aa854c855cbe5110ca7d598ffc
> >
>
> LGTM.
>
> Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
>
> BTW, this patch:
>
> https://patchwork.sourceware.org/project/glibc/list/?series=33161

The v2 patch:

https://patchwork.sourceware.org/project/glibc/list/?series=33162

to keep # in gdb backtrace.

> is also required.
>
> Thanks.
>
> --
> H.J.
  

* H. J. Lu:

> On Thu, Apr 25, 2024 at 5:11 AM Florian Weimer <fweimer@redhat.com> wrote:
>>
>> At this point, this is mainly a tool for testing the early ld.so
>> CPU compatibility diagnostics: GCC uses the new instructions in most
>> functions, so it's easy to spot if some of the early code is not
>> built correctly.  (No such problems were flagged for the current
>> tree.)
>>
>> ---
>>  sysdeps/x86/dl-get-cpu-features.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/sysdeps/x86/dl-get-cpu-features.c b/sysdeps/x86/dl-get-cpu-features.c
>> index 4d6c5c59a6..579d02d638 100644
>> --- a/sysdeps/x86/dl-get-cpu-features.c
>> +++ b/sysdeps/x86/dl-get-cpu-features.c
>> @@ -64,6 +64,11 @@ Fatal glibc error: CPU does not support x86-64-v%d\n", 4);
>>  #    endif /* ISA level 4 */
>>  #   endif /* ISA level 3 */
>>  #  endif /* ISA level 2 */
>> +# ifdef GCCMACRO__APX_F__
>> +      if (!CPU_FEATURE_USABLE_P (cpu_features, APX_F))
>> +       _dl_fatal_printf ("\
>> +Fatal glibc error: CPU does not support APX\n");
>> +# endif
>>  # endif /* IS_IN (rtld) */
>>      }
>>  }
>>
>> base-commit: 3a3a4497421422aa854c855cbe5110ca7d598ffc
>>
>
> LGTM.
>
> Reviewed-by: H.J. Lu <hjl.tools@gmail.com>

Thanks.

> BTW, this patch:
>
> https://patchwork.sourceware.org/project/glibc/list/?series=33161
>
> is also required.

Oh, I didn't test with GLIBC_TUNABLES.  I'm going to remove the
incorrect claim from the commit message.

Florian