crypto: x86/chacha20 - Support partial lengths in 1-block SSSE3 variant

Browse source

Add a length argument to the single block function for SSSE3, so the
block function may XOR only a partial length of the full block. Given
that the setup code is rather cheap, the function does not process more
than one block; this allows us to keep the block function selection in
the C glue code.

The required branching does not negatively affect performance for full
block sizes. The partial XORing uses simple "rep movsb" to copy the
data before and after doing XOR in SSE. This is rather efficient on
modern processors; movsw can be slightly faster, but the additional
complexity is probably not worth it.

Signed-off-by: Martin Willi <martin@strongswan.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

...

This commit is contained in:

Martin Willi 2018-11-11 10:36:25 +01:00 • committed by Herbert Xu

parent 05ba88468b

commit e4e72063d3

2 changed files with 63 additions and 22 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

72

arch/x86/crypto/chacha20-ssse3-x86_64.S

View file

11

arch/x86/crypto/chacha20_glue.c

View file