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From:   <Ryan.Wanner@microchip.com>
To:     <herbert@gondor.apana.org.au>, <davem@davemloft.net>,
        <nicolas.ferre@microchip.com>, <alexandre.belloni@bootlin.com>,
        <claudiu.beznea@microchip.com>
CC:     <linux-crypto@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>,
        Ryan Wanner <Ryan.Wanner@microchip.com>
Subject: [PATCH 3/4] crypto: atmel-aes - Detecting in-place operations two sg lists
Date:   Tue, 28 Mar 2023 12:56:28 -0700
Message-ID: <74e969a12021b008d12d871d8d4d9162905f3c48.1680019905.git.Ryan.Wanner@microchip.com>
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From: Ryan Wanner <Ryan.Wanner@microchip.com>

Avoiding detecting finely in-place operations with different
scatter lists. Copying the source data for decryption into rctx->lastc
regardless if the operation is in-place or not. This allows in-place
operations with different scatter lists.

This approach takes less resources than parsing both scatter lists to
check if they are equal.

Signed-off-by: Ryan Wanner <Ryan.Wanner@microchip.com>
---
 drivers/crypto/atmel-aes.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/drivers/crypto/atmel-aes.c b/drivers/crypto/atmel-aes.c
index 063394cfa874..08a923c2a0eb 100644
--- a/drivers/crypto/atmel-aes.c
+++ b/drivers/crypto/atmel-aes.c
@@ -493,17 +493,11 @@ static void atmel_aes_set_iv_as_last_ciphertext_block(struct atmel_aes_dev *dd)
 	if (req->cryptlen < ivsize)
 		return;
 
-	if (rctx->mode & AES_FLAGS_ENCRYPT) {
+	if (rctx->mode & AES_FLAGS_ENCRYPT)
 		scatterwalk_map_and_copy(req->iv, req->dst,
 					 req->cryptlen - ivsize, ivsize, 0);
-	} else {
-		if (req->src == req->dst)
-			memcpy(req->iv, rctx->lastc, ivsize);
-		else
-			scatterwalk_map_and_copy(req->iv, req->src,
-						 req->cryptlen - ivsize,
-						 ivsize, 0);
-	}
+	else
+		memcpy(req->iv, rctx->lastc, ivsize);
 }
 
 static inline struct atmel_aes_ctr_ctx *
@@ -1146,7 +1140,7 @@ static int atmel_aes_crypt(struct skcipher_request *req, unsigned long mode)
 	rctx->mode = mode;
 
 	if (opmode != AES_FLAGS_ECB &&
-	    !(mode & AES_FLAGS_ENCRYPT) && req->src == req->dst) {
+	    !(mode & AES_FLAGS_ENCRYPT)) {
 		unsigned int ivsize = crypto_skcipher_ivsize(skcipher);
 
 		if (req->cryptlen >= ivsize)
-- 
2.37.2