This patch adds a x86_64/avx assembler implementation of the Serpent block
cipher. The implementation is very similar to the sse2 implementation and
processes eight blocks in parallel. Because of the new non-destructive three
operand syntax all move-instructions can be removed and therefore a little
performance increase is provided.

Patch has been tested with tcrypt and automated filesystem tests.

Tcrypt benchmark results:

Intel Core i5-2500 CPU (fam:6, model:42, step:7)

serpent-avx-x86_64 vs. serpent-sse2-x86_64
128bit key:                                             (lrw:256bit)    (xts:256bit)
size    ecb-enc ecb-dec cbc-enc cbc-dec ctr-enc ctr-dec lrw-enc lrw-dec xts-enc xts-dec
16B     1.03x   1.01x   1.01x   1.01x   1.00x   1.00x   1.00x   1.00x   1.00x   1.01x
64B     1.00x   1.00x   1.00x   1.00x   1.00x   0.99x   1.00x   1.01x   1.00x   1.00x
256B    1.05x   1.03x   1.00x   1.02x   1.05x   1.06x   1.05x   1.02x   1.05x   1.02x
1024B   1.05x   1.02x   1.00x   1.02x   1.05x   1.06x   1.05x   1.03x   1.05x   1.02x
8192B   1.05x   1.02x   1.00x   1.02x   1.06x   1.06x   1.04x   1.03x   1.04x   1.02x

256bit key:                                             (lrw:384bit)    (xts:512bit)
size    ecb-enc ecb-dec cbc-enc cbc-dec ctr-enc ctr-dec lrw-enc lrw-dec xts-enc xts-dec
16B     1.01x   1.00x   1.01x   1.01x   1.00x   1.00x   0.99x   1.03x   1.01x   1.01x
64B     1.00x   1.00x   1.00x   1.00x   1.00x   1.00x   1.00x   1.01x   1.00x   1.02x
256B    1.05x   1.02x   1.00x   1.02x   1.05x   1.02x   1.04x   1.05x   1.05x   1.02x
1024B   1.06x   1.02x   1.00x   1.02x   1.07x   1.06x   1.05x   1.04x   1.05x   1.02x
8192B   1.05x   1.02x   1.00x   1.02x   1.06x   1.06x   1.04x   1.05x   1.05x   1.02x

serpent-avx-x86_64 vs aes-asm (8kB block):
         128bit  256bit
ecb-enc  1.26x   1.73x
ecb-dec  1.20x   1.64x
cbc-enc  0.33x   0.45x
cbc-dec  1.24x   1.67x
ctr-enc  1.32x   1.76x
ctr-dec  1.32x   1.76x
lrw-enc  1.20x   1.60x
lrw-dec  1.15x   1.54x
xts-enc  1.22x   1.64x
xts-dec  1.17x   1.57x
Signed-off-by: Johannes Goetzfried <Johannes.Goetzfried@informatik.stud.uni-erlangen.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>