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>
diff --git a/arch/arm64/crypto/Kconfig b/arch/arm64/crypto/Kconfig
index 0bf0f53..0826f8e 100644
--- a/arch/arm64/crypto/Kconfig
+++ b/arch/arm64/crypto/Kconfig
@@ -41,6 +41,10 @@
depends on KERNEL_MODE_NEON && CRC32
select CRYPTO_HASH
+config CRYPTO_AES_ARM64
+ tristate "AES core cipher using scalar instructions"
+ select CRYPTO_AES
+
config CRYPTO_AES_ARM64_CE
tristate "AES core cipher using ARMv8 Crypto Extensions"
depends on ARM64 && KERNEL_MODE_NEON