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crypto: convert xts_mult_x to use xts_uint128 type 

Using 64-bit arithmetic increases the performance for xts-aes-128
when built with gcrypt:

  Encrypt: 355 MB/s -> 545 MB/s
  Decrypt: 362 MB/s -> 568 MB/s

Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
This commit is contained in:
Daniel P. Berrangé 2018-10-09 10:55:14 +01:00
parent db217c69f0
commit 7dac0dd674
1 changed files with 28 additions and 12 deletions
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40
crypto/xts.c
View File

@ -24,6 +24,7 @@
*/
#include "qemu/osdep.h"
#include "qemu/bswap.h"
#include "crypto/xts.h"
typedef union {
@ -39,19 +40,34 @@ static inline void xts_uint128_xor(xts_uint128 *D,
D->u[1] = S1->u[1] ^ S2->u[1];
}
static void xts_mult_x(uint8_t *I)
static inline void xts_uint128_cpu_to_les(xts_uint128 *v)
{
int x;
uint8_t t, tt;
cpu_to_le64s(&v->u[0]);
cpu_to_le64s(&v->u[1]);
}
for (x = t = 0; x < 16; x++) {
tt = I[x] >> 7;
I[x] = ((I[x] << 1) | t) & 0xFF;
t = tt;
}
if (tt) {
I[0] ^= 0x87;
static inline void xts_uint128_le_to_cpus(xts_uint128 *v)
{
le64_to_cpus(&v->u[0]);
le64_to_cpus(&v->u[1]);
}
static void xts_mult_x(xts_uint128 *I)
{
uint64_t tt;
xts_uint128_le_to_cpus(I);
tt = I->u[0] >> 63;
I->u[0] <<= 1;
if (I->u[1] >> 63) {
I->u[0] ^= 0x87;
}
I->u[1] <<= 1;
I->u[1] |= tt;
xts_uint128_cpu_to_les(I);
}
@ -79,7 +95,7 @@ static void xts_tweak_encdec(const void *ctx,
xts_uint128_xor(dst, dst, iv);
/* LFSR the tweak */
xts_mult_x(iv->b);
xts_mult_x(iv);
}
@ -134,7 +150,7 @@ void xts_decrypt(const void *datactx,
if (mo > 0) {
xts_uint128 S, D;
memcpy(&CC, &T, XTS_BLOCK_SIZE);
xts_mult_x(CC.b);
xts_mult_x(&CC);
/* PP = tweak decrypt block m-1 */
memcpy(&S, src, XTS_BLOCK_SIZE);