Optimize ChaCha20 NEON performance by:
- Implementing the 8-bit rotations using the 'vtbl.8' instruction.
- Streamlining the part that adds the original state and XORs the data.
- Making some other small tweaks.
On ARM Cortex-A7, these optimizations improve ChaCha20 performance from
about 12.08 cycles per byte to about 11.37 -- a 5.9% improvement.
There is a tradeoff involved with the 'vtbl.8' rotation method since
there is at least one CPU (Cortex-A53) where it's not fastest. But it
seems to be a better default; see the added comment. Overall, this
patch reduces Cortex-A53 performance by less than 0.5%.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The 4-way ChaCha20 NEON code implements 16-bit rotates with vrev32.16,
but the one-way code (used on remainder blocks) implements it with
vshl + vsri, which is slower. Switch the one-way code to vrev32.16 too.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This is a straight port to ARM/NEON of the x86 SSE3 implementation
of the ChaCha20 stream cipher. It uses the new skcipher walksize
attribute to process the input in strides of 4x the block size.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch reverts the following commits:
8621caa0d48096667273
I should not have applied them because they had already been
obsoleted by a subsequent patch series. They also cause a build
failure because of the subsequent commit 9ae433bc79.
Fixes: 9ae433bc79 ("crypto: chacha20 - convert generic and...")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This is a straight port to ARM/NEON of the x86 SSE3 implementation
of the ChaCha20 stream cipher.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
