Re: [RFC V1 1/7] x86: Probe assembler capabilities for VAES and VPLCMULQDQ support

[Dey, Megha]

Hi Ard,

On 1/16/2021 8:54 AM, Ard Biesheuvel wrote:
> On Fri, 18 Dec 2020 at 22:07, Megha Dey <megha.dey@xxxxxxxxx> wrote:
> > This is a preparatory patch to introduce the optimized crypto algorithms
> > using AVX512 instructions which would require VAES and VPLCMULQDQ support.
> >
> > Check for VAES and VPCLMULQDQ assembler support using AVX512 registers.
> >
> > Cc: x86@xxxxxxxxxx
> > Signed-off-by: Megha Dey <megha.dey@xxxxxxxxx>
> > ---
> >   arch/x86/Kconfig.assembler | 10 ++++++++++
> >   1 file changed, 10 insertions(+)
> >
> > diff --git a/arch/x86/Kconfig.assembler b/arch/x86/Kconfig.assembler
> > index 26b8c08..9ea0bc8 100644
> > --- a/arch/x86/Kconfig.assembler
> > +++ b/arch/x86/Kconfig.assembler
> > @@ -1,6 +1,16 @@
> >   # SPDX-License-Identifier: GPL-2.0
> >   # Copyright (C) 2020 Jason A. Donenfeld <Jason@xxxxxxxxx>. All Rights Reserved.
> >
> > +config AS_VAES_AVX512
> > +       def_bool $(as-instr,vaesenc %zmm0$(comma)%zmm1$(comma)%zmm1) && 64BIT
> Is the '&& 64BIT' necessary here, but not below?
>
> In any case, better to use a separate 'depends on' line, for legibility

yeah , I think the '&& 64 BIT' is not required. I will remove it in the 
next version.

-Megha

> > +       help
> > +         Supported by binutils >= 2.30 and LLVM integrated assembler
> > +
> > +config AS_VPCLMULQDQ
> > +       def_bool $(as-instr,vpclmulqdq \$0$(comma)%zmm2$(comma)%zmm6$(comma)%zmm4)
> > +       help
> > +         Supported by binutils >= 2.30 and LLVM integrated assembler
> > +
> >   config AS_AVX512
> >          def_bool $(as-instr,vpmovm2b %k1$(comma)%zmm5)
> >          help
> > --
> > 2.7.4