[PATCH] crypto/arm: accelerated SHA-512 using ARM generic ASM and NEON

[Ard Biesheuvel]

On 29 March 2015 at 16:07, Andy Polyakov <appro at openssl.org> wrote:
>> This updates the SHA-512 NEON module with the faster and more
>> versatile implementation from the OpenSSL project. It consists
>> of both a NEON and a generic ASM version of the core SHA-512
>> transform, where the NEON version reverts to the ASM version
>> when invoked in non-process context.
>>
>> Performance relative to the generic implementation (measured
>> using tcrypt.ko mode=306 sec=1 running on a Cortex-A57 under
>> KVM):
>>
>>       input size      block size      asm     neon    old neon
>>
>>       8192            8192            1.51    3.51    2.69
>
> One should keep in mind that improvement coefficients vary greatly from
> platform to platform. Normally you *should* observe higher coefficients
> in asm column and *can* observe smaller differences between "neon" and
> "old neon". BTW, 1.51 is unexpectedly low, I wonder which compiler
> version stands for 1.0?

This was Linaro GCC 4.9

> Nor can I replicate difference between "neon"
> and "old neon", I get smaller difference, 17%, on Cortex-A57. Well, I'm
> comparing in user-land, but it shouldn't be that significant at large
> blocks...
>

That is a bit surprising, indeed. The primary difference is that this
executes under a 32-bit kernel, whereas your testing uses 32-bit
OpenSSL under a 64-bit kernel in 32-bit compatibility mode. I can't
really explain how that should make a difference at all, but it's
worth to be noted.


>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
>> ---
>>
>> This should get the same treatment as Sami's sha56 version: I would like
>> to wait until the OpenSSL source file hits the upstream repository so that
>> I can refer to its sha1 hash in the commit log.
>
> Update is committed as
> http://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=b1a5d1c652086257930a1f62ae51c9cdee654b2c.
> Note that the file I've initially sent privately was a little bit off.
> Sorry about that. But that little bit is just a commentary update that
> adds performance result for Cortex-A15. So that kernel patch as
> originally posted is 100% functionally equivalent.
>

Thanks.