[CRYPTO] Add alignmask for low-level cipher implementations

The VIA Padlock device requires the input and output buffers to
be aligned on 16-byte boundaries.  This patch adds the alignmask
attribute for low-level cipher implementations to indicate their
alignment requirements.

The mid-level crypt() function will copy the input/output buffers
if they are not aligned correctly before they are passed to the
low-level implementation.

Strictly speaking, some of the software implementations require
the buffers to be aligned on 4-byte boundaries as they do 32-bit
loads.  However, it is not clear whether it is better to copy
the buffers or pay the penalty for unaligned loads/stores.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/crypto.h b/include/linux/crypto.h
index 26ce01c25745..ac9d49beecd3 100644
--- a/include/linux/crypto.h
+++ b/include/linux/crypto.h
@@ -124,6 +124,7 @@ struct crypto_alg {
         u32 cra_flags;
         unsigned int cra_blocksize;
         unsigned int cra_ctxsize;
+        unsigned int cra_alignmask;
         const char cra_name[CRYPTO_MAX_ALG_NAME];
 
         union {