As it turns out, checking the TIF_NEED_RESCHED flag after each
iteration results in a significant performance regression (~10%)
when running fast algorithms (i.e., ones that use special instructions
and operate in the < 4 cycles per byte range) on in-order cores with
comparatively slow memory accesses such as the Cortex-A53.
Given the speed of these ciphers, and the fact that the page based
nature of the AEAD scatterwalk API guarantees that the core NEON
transform is never invoked with more than a single page's worth of
input, we can estimate the worst case duration of any resulting
scheduling blackout: on a 1 GHz Cortex-A53 running with 64k pages,
processing a page's worth of input at 4 cycles per byte results in
a delay of ~250 us, which is a reasonable upper bound.
So let's remove the yield checks from the fused AES-CCM and AES-GCM
routines entirely.
This reverts commit 7b67ae4d5c and
partially reverts commit 7c50136a8a.
Fixes: 7c50136a8a ("crypto: arm64/aes-ghash - yield NEON after every ...")
Fixes: 7b67ae4d5c ("crypto: arm64/aes-ccm - yield NEON after every ...")
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Avoid excessive scheduling delays under a preemptible kernel by
yielding the NEON after every block of input.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
In order to be able to reuse the generic AES code as a fallback for
situations where the NEON may not be used, update the key handling
to match the byte order of the generic code: it stores round keys
as sequences of 32-bit quantities rather than streams of bytes, and
so our code needs to be updated to reflect that.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The AES-CCM implementation that uses ARMv8 Crypto Extensions instructions
refers to the AES round keys as pairs of 64-bit quantities, which causes
failures when building the code for big endian. In addition, it byte swaps
the input counter unconditionally, while this is only required for little
endian builds. So fix both issues.
Fixes: 12ac3efe74 ("arm64/crypto: use crypto instructions to generate AES key schedule")
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This changes the AES core transform implementations to issue aese/aesmc
(and aesd/aesimc) in pairs. This enables a micro-architectural optimization
in recent Cortex-A5x cores that improves performance by 50-90%.
Measured performance in cycles per byte (Cortex-A57):
CBC enc CBC dec CTR
before 3.64 1.34 1.32
after 1.95 0.85 0.93
Note that this results in a ~5% performance decrease for older cores.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This patch adds support for the AES-CCM encryption algorithm for CPUs that
have support for the AES part of the ARM v8 Crypto Extensions.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Ard Biesheuvel