On Sun, Feb 05, 2017 at 10:06:12AM +0000, Ard Biesheuvel wrote: > 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@xxxxxxxxxx> Patch applied. Thanks. -- Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
