Commit Graph

3 Commits

Author SHA1 Message Date
Ard Biesheuvel
c458c4ada0 crypto: arm64/aes - performance tweak
Shuffle some instructions around in the __hround macro to shave off
0.1 cycles per byte on Cortex-A57.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-02-03 18:16:20 +08:00
Ard Biesheuvel
262ea4f670 crypto: arm64/aes - avoid literals for cross-module symbol references
Using simple adrp/add pairs to refer to the AES lookup tables exposed by
the generic AES driver (which could be loaded far away from this driver
when KASLR is in effect) was unreliable at module load time before commit
41c066f2c4 ("arm64: assembler: make adr_l work in modules under KASLR"),
which is why the AES code used literals instead.

So now we can get rid of the literals, and switch to the adr_l macro.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-02-03 18:16:20 +08:00
Ard Biesheuvel
bed593c0e8 crypto: arm64/aes - add scalar implementation
This adds a scalar implementation of AES, based on the precomputed tables
that are exposed by the generic AES code. Since rotates are cheap on arm64,
this implementation only uses the 4 core tables (of 1 KB each), and avoids
the prerotated ones, reducing the D-cache footprint by 75%.

On Cortex-A57, this code manages 13.0 cycles per byte, which is ~34% faster
than the generic C code. (Note that this is still >13x slower than the code
that uses the optional ARMv8 Crypto Extensions, which manages <1 cycles per
byte.)

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-01-13 00:26:49 +08:00