crypto: x86 - add more optimized XTS-mode for serpent-avx

This patch adds AVX optimized XTS-mode helper functions/macros and converts
serpent-avx to use the new facilities. Benefits are slightly improved speed
and reduced stack usage as use of temporary IV-array is avoided.

tcrypt results, with Intel i5-2450M:
        enc     dec
16B     1.00x   1.00x
64B     1.00x   1.00x
256B    1.04x   1.06x
1024B   1.09x   1.09x
8192B   1.10x   1.09x

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 96 insertions, 1 deletions

diff --git a/arch/x86/crypto/glue_helper.c b/arch/x86/crypto/glue_helper.c
index 22ce4f683e55..432f1d76ceb8 100644
--- a/arch/x86/crypto/glue_helper.c
+++ b/arch/x86/crypto/glue_helper.c
@@ -1,7 +1,7 @@
 /*
  * Shared glue code for 128bit block ciphers
  *
- * Copyright (c) 2012 Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
+ * Copyright © 2012-2013 Jussi Kivilinna <jussi.kivilinna@iki.fi>
  *
  * CBC & ECB parts based on code (crypto/cbc.c,ecb.c) by:
  *   Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
@@ -304,4 +304,99 @@ int glue_ctr_crypt_128bit(const struct common_glue_ctx *gctx,
 }
 EXPORT_SYMBOL_GPL(glue_ctr_crypt_128bit);
 
+static unsigned int __glue_xts_crypt_128bit(const struct common_glue_ctx *gctx,
+                                            void *ctx,
+                                            struct blkcipher_desc *desc,
+                                            struct blkcipher_walk *walk)
+{
+        const unsigned int bsize = 128 / 8;
+        unsigned int nbytes = walk->nbytes;
+        u128 *src = (u128 *)walk->src.virt.addr;
+        u128 *dst = (u128 *)walk->dst.virt.addr;
+        unsigned int num_blocks, func_bytes;
+        unsigned int i;
+
+        /* Process multi-block batch */
+        for (i = 0; i < gctx->num_funcs; i++) {
+                num_blocks = gctx->funcs[i].num_blocks;
+                func_bytes = bsize * num_blocks;
+
+                if (nbytes >= func_bytes) {
+                        do {
+                                gctx->funcs[i].fn_u.xts(ctx, dst, src,
+                                                        (le128 *)walk->iv);
+
+                                src += num_blocks;
+                                dst += num_blocks;
+                                nbytes -= func_bytes;
+                        } while (nbytes >= func_bytes);
+
+                        if (nbytes < bsize)
+                                goto done;
+                }
+        }
+
+done:
+        return nbytes;
+}
+
+/* for implementations implementing faster XTS IV generator */
+int glue_xts_crypt_128bit(const struct common_glue_ctx *gctx,
+                          struct blkcipher_desc *desc, struct scatterlist *dst,
+                          struct scatterlist *src, unsigned int nbytes,
+                          void (*tweak_fn)(void *ctx, u8 *dst, const u8 *src),
+                          void *tweak_ctx, void *crypt_ctx)
+{
+        const unsigned int bsize = 128 / 8;
+        bool fpu_enabled = false;
+        struct blkcipher_walk walk;
+        int err;
+
+        blkcipher_walk_init(&walk, dst, src, nbytes);
+
+        err = blkcipher_walk_virt(desc, &walk);
+        nbytes = walk.nbytes;
+        if (!nbytes)
+                return err;
+
+        /* set minimum length to bsize, for tweak_fn */
+        fpu_enabled = glue_fpu_begin(bsize, gctx->fpu_blocks_limit,
+                                     desc, fpu_enabled,
+                                     nbytes < bsize ? bsize : nbytes);
+
+        /* calculate first value of T */
+        tweak_fn(tweak_ctx, walk.iv, walk.iv);
+
+        while (nbytes) {
+                nbytes = __glue_xts_crypt_128bit(gctx, crypt_ctx, desc, &walk);
+
+                err = blkcipher_walk_done(desc, &walk, nbytes);
+                nbytes = walk.nbytes;
+        }
+
+        glue_fpu_end(fpu_enabled);
+
+        return err;
+}
+EXPORT_SYMBOL_GPL(glue_xts_crypt_128bit);
+
+void glue_xts_crypt_128bit_one(void *ctx, u128 *dst, const u128 *src, le128 *iv,
+                               common_glue_func_t fn)
+{
+        le128 ivblk = *iv;
+
+        /* generate next IV */
+        le128_gf128mul_x_ble(iv, &ivblk);
+
+        /* CC <- T xor C */
+        u128_xor(dst, src, (u128 *)&ivblk);
+
+        /* PP <- D(Key2,CC) */
+        fn(ctx, (u8 *)dst, (u8 *)dst);
+
+        /* P <- T xor PP */
+        u128_xor(dst, dst, (u128 *)&ivblk);
+}
+EXPORT_SYMBOL_GPL(glue_xts_crypt_128bit_one);
+
 MODULE_LICENSE("GPL");