Re: [PATCH v2 3/6] crypto: lib/sha256 - Clear W[] in sha256_update() instead of sha256_transform()

[Eric Biggers]

On Tue, Oct 20, 2020 at 04:39:54PM -0400, Arvind Sankar wrote:
> The temporary W[] array is currently zeroed out once every call to
> sha256_transform(), i.e. once every 64 bytes of input data. Moving it to
> sha256_update() instead so that it is cleared only once per update can
> save about 2-3% of the total time taken to compute the digest, with a
> reasonable memset() implementation, and considerably more (~20%) with a
> bad one (eg the x86 purgatory currently uses a memset() coded in C).
> 
> Signed-off-by: Arvind Sankar <nivedita@xxxxxxxxxxxx>

Looks good,

Reviewed-by: Eric Biggers <ebiggers@xxxxxxxxxx>