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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2017-02-05 10:06:12 +0000
committerHerbert Xu <herbert@gondor.apana.org.au>2017-02-11 17:52:28 +0800
commitdb91af0fbe20474cec33263e28d15f5e6b45ebc9 (patch)
tree22ff7970897903b0418cef78a2aeb59907f5b554 /crypto/cmac.c
parent7d6e9105026788c497f0ab32fa16c82f4ab5ff61 (diff)
downloadlwn-db91af0fbe20474cec33263e28d15f5e6b45ebc9.tar.gz
lwn-db91af0fbe20474cec33263e28d15f5e6b45ebc9.zip
crypto: algapi - make crypto_xor() and crypto_inc() alignment agnostic
Instead of unconditionally forcing 4 byte alignment for all generic chaining modes that rely on crypto_xor() or crypto_inc() (which may result in unnecessary copying of data when the underlying hardware can perform unaligned accesses efficiently), make those functions deal with unaligned input explicitly, but only if the Kconfig symbol HAVE_EFFICIENT_UNALIGNED_ACCESS is set. This will allow us to drop the alignmasks from the CBC, CMAC, CTR, CTS, PCBC and SEQIV drivers. For crypto_inc(), this simply involves making the 4-byte stride conditional on HAVE_EFFICIENT_UNALIGNED_ACCESS being set, given that it typically operates on 16 byte buffers. For crypto_xor(), an algorithm is implemented that simply runs through the input using the largest strides possible if unaligned accesses are allowed. If they are not, an optimal sequence of memory accesses is emitted that takes the relative alignment of the input buffers into account, e.g., if the relative misalignment of dst and src is 4 bytes, the entire xor operation will be completed using 4 byte loads and stores (modulo unaligned bits at the start and end). Note that all expressions involving misalign are simply eliminated by the compiler when HAVE_EFFICIENT_UNALIGNED_ACCESS is defined. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto/cmac.c')
-rw-r--r--crypto/cmac.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/crypto/cmac.c b/crypto/cmac.c
index 04080dca8f0c..16301f52858c 100644
--- a/crypto/cmac.c
+++ b/crypto/cmac.c
@@ -260,8 +260,7 @@ static int cmac_create(struct crypto_template *tmpl, struct rtattr **tb)
if (err)
goto out_free_inst;
- /* We access the data as u32s when xoring. */
- alignmask = alg->cra_alignmask | (__alignof__(u32) - 1);
+ alignmask = alg->cra_alignmask;
inst->alg.base.cra_alignmask = alignmask;
inst->alg.base.cra_priority = alg->cra_priority;
inst->alg.base.cra_blocksize = alg->cra_blocksize;