[PATCH 2/4] arm64: cpufeature: add feature for CRC32 instructions

Will Deacon will.deacon at arm.com
Tue Sep 4 02:38:45 PDT 2018


On Tue, Sep 04, 2018 at 11:18:55AM +0800, Herbert Xu wrote:
> On Tue, Aug 28, 2018 at 08:43:35PM +0200, Ard Biesheuvel wrote:
> > On 28 August 2018 at 19:01, Will Deacon <will.deacon at arm.com> wrote:
> > > On Mon, Aug 27, 2018 at 01:02:43PM +0200, Ard Biesheuvel wrote:
> > >> Add a CRC32 feature bit and wire it up to the CPU id register so we
> > >> will be able to use alternatives patching for CRC32 operations.
> > >>
> > >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
> > >> ---
> > >>  arch/arm64/include/asm/cpucaps.h | 3 ++-
> > >>  arch/arm64/kernel/cpufeature.c   | 9 +++++++++
> > >>  2 files changed, 11 insertions(+), 1 deletion(-)
> > >
> > > Acked-by: Will Deacon <will.deacon at arm.com>
> > >
> > > With the minor caveat below...
> > >
> > >> diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
> > >> index ae1f70450fb2..9932aca9704b 100644
> > >> --- a/arch/arm64/include/asm/cpucaps.h
> > >> +++ b/arch/arm64/include/asm/cpucaps.h
> > >> @@ -51,7 +51,8 @@
> > >>  #define ARM64_SSBD                           30
> > >>  #define ARM64_MISMATCHED_CACHE_TYPE          31
> > >>  #define ARM64_HAS_STAGE2_FWB                 32
> > >> +#define ARM64_HAS_CRC32                              33
> > >>
> > >> -#define ARM64_NCAPS                          33
> > >> +#define ARM64_NCAPS                          34
> > >
> > >
> > > ... if this goes via crypto, you'll almost certainly get a (trivial)
> > > conflict with arm64, since these numbers get bumped all the time.
> > >
> > 
> > I think the first three patches should go through the arm64 tree. The
> > last one just removes the now redundant crc32 SIMD driver, and Herbert
> > could pick that up separately, i.e., it should be totally independent.
> 
> Yes let's do that.

Okey doke! In which case, please can we have your Ack on the first patch?

Cheers,

Will



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