tree ea7b3f03c3af0d1e818d588ac2a8e99c391b0826
parent dd597fb33ff0d2a158d7dd098be6dc849b7c2bcc
author Ard Biesheuvel <ard.biesheuvel@linaro.org> 1536590475 +0200
committer Herbert Xu <herbert@gondor.apana.org.au> 1537507490 +0800

crypto: arm64/aes-blk - improve XTS mask handling

The Crypto Extension instantiation of the aes-modes.S collection of
skciphers uses only 15 NEON registers for the round key array, whereas
the pure NEON flavor uses 16 NEON registers for the AES S-box.

This means we have a spare register available that we can use to hold
the XTS mask vector, removing the need to reload it at every iteration
of the inner loop.

Since the pure NEON version does not permit this optimization, tweak
the macros so we can factor out this functionality. Also, replace the
literal load with a short sequence to compose the mask vector.

On Cortex-A53, this results in a ~4% speedup.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>