linux-kernel - [PATCH v2] poly1305: generic C can be faster on chips with slow unaligned access

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Date:   Mon,  7 Nov 2016 20:12:53 +0100
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        Martin Willi <martin@...ongswan.org>,
        Eric Biggers <ebiggers@...gle.com>,
        René van Dorst <opensource@...rst.com>
Cc:     "Jason A. Donenfeld" <Jason@...c4.com>
Subject: [PATCH v2] poly1305: generic C can be faster on chips with slow unaligned access

By using the unaligned access helpers, we drastically improve
performance on small MIPS routers that have to go through the exception
fix-up handler for these unaligned accesses.

Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
---
 crypto/poly1305_generic.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/crypto/poly1305_generic.c b/crypto/poly1305_generic.c
index 2df9835d..0b86f4e 100644
--- a/crypto/poly1305_generic.c
+++ b/crypto/poly1305_generic.c
@@ -66,9 +66,9 @@ static void poly1305_setrkey(struct poly1305_desc_ctx *dctx, const u8 *key)
 {
 	/* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
 	dctx->r[0] = (le32_to_cpuvp(key +  0) >> 0) & 0x3ffffff;
-	dctx->r[1] = (le32_to_cpuvp(key +  3) >> 2) & 0x3ffff03;
-	dctx->r[2] = (le32_to_cpuvp(key +  6) >> 4) & 0x3ffc0ff;
-	dctx->r[3] = (le32_to_cpuvp(key +  9) >> 6) & 0x3f03fff;
+	dctx->r[1] = (get_unaligned_le32(key +  3) >> 2) & 0x3ffff03;
+	dctx->r[2] = (get_unaligned_le32(key +  6) >> 4) & 0x3ffc0ff;
+	dctx->r[3] = (get_unaligned_le32(key +  9) >> 6) & 0x3f03fff;
 	dctx->r[4] = (le32_to_cpuvp(key + 12) >> 8) & 0x00fffff;
 }
 
@@ -138,9 +138,9 @@ static unsigned int poly1305_blocks(struct poly1305_desc_ctx *dctx,
 
 		/* h += m[i] */
 		h0 += (le32_to_cpuvp(src +  0) >> 0) & 0x3ffffff;
-		h1 += (le32_to_cpuvp(src +  3) >> 2) & 0x3ffffff;
-		h2 += (le32_to_cpuvp(src +  6) >> 4) & 0x3ffffff;
-		h3 += (le32_to_cpuvp(src +  9) >> 6) & 0x3ffffff;
+		h1 += (get_unaligned_le32(src +  3) >> 2) & 0x3ffffff;
+		h2 += (get_unaligned_le32(src +  6) >> 4) & 0x3ffffff;
+		h3 += (get_unaligned_le32(src +  9) >> 6) & 0x3ffffff;
 		h4 += (le32_to_cpuvp(src + 12) >> 8) | hibit;
 
 		/* h *= r */
-- 
2.10.2