linux-kernel - [PATCH 3/3] crypto: x86/aesni - Perform address alignment early for XTS mode

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Date:   Mon, 25 Sep 2023 08:17:52 -0700
From:   "Chang S. Bae" <chang.seok.bae@...el.com>
To:     linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org
Cc:     herbert@...dor.apana.org.au, davem@...emloft.net,
        ebiggers@...nel.org, x86@...nel.org, chang.seok.bae@...el.com
Subject: [PATCH 3/3] crypto: x86/aesni - Perform address alignment early for XTS mode

Currently, the alignment of each field in struct aesni_xts_ctx occurs
right before every access. However, it's possible to perform this
alignment ahead of time.

Introduce a helper function that converts struct crypto_skcipher *tfm
to struct aesni_xts_ctx *ctx and returns an aligned address. Utilize
this helper function at the beginning of each XTS function and then
eliminate redundant alignment code.

Suggested-by: Eric Biggers <ebiggers@...nel.org>
Signed-off-by: Chang S. Bae <chang.seok.bae@...el.com>
Cc: linux-crypto@...r.kernel.org
Cc: x86@...nel.org
Cc: linux-kernel@...r.kernel.org
Link: https://lore.kernel.org/all/ZFWQ4sZEVu%2FLHq+Q@gmail.com/
---
 arch/x86/crypto/aesni-intel_glue.c | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/arch/x86/crypto/aesni-intel_glue.c b/arch/x86/crypto/aesni-intel_glue.c
index 412a99e914a6..b344652510a3 100644
--- a/arch/x86/crypto/aesni-intel_glue.c
+++ b/arch/x86/crypto/aesni-intel_glue.c
@@ -223,6 +223,11 @@ static inline struct crypto_aes_ctx *aes_ctx(void *raw_ctx)
 	return (struct crypto_aes_ctx *)aes_align_addr(raw_ctx);
 }
 
+static inline struct aesni_xts_ctx *aes_xts_ctx(struct crypto_skcipher *tfm)
+{
+	return (struct aesni_xts_ctx *)aes_align_addr(crypto_skcipher_ctx(tfm));
+}
+
 static int aes_set_key_common(struct crypto_aes_ctx *ctx,
 			      const u8 *in_key, unsigned int key_len)
 {
@@ -875,7 +880,7 @@ static int helper_rfc4106_decrypt(struct aead_request *req)
 static int xts_aesni_setkey(struct crypto_skcipher *tfm, const u8 *key,
 			    unsigned int keylen)
 {
-	struct aesni_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
+	struct aesni_xts_ctx *ctx = aes_xts_ctx(tfm);
 	int err;
 
 	err = xts_verify_key(tfm, key, keylen);
@@ -885,18 +890,18 @@ static int xts_aesni_setkey(struct crypto_skcipher *tfm, const u8 *key,
 	keylen /= 2;
 
 	/* first half of xts-key is for crypt */
-	err = aes_set_key_common(aes_ctx(&ctx->crypt_ctx), key, keylen);
+	err = aes_set_key_common(&ctx->crypt_ctx, key, keylen);
 	if (err)
 		return err;
 
 	/* second half of xts-key is for tweak */
-	return aes_set_key_common(aes_ctx(&ctx->tweak_ctx), key + keylen, keylen);
+	return aes_set_key_common(&ctx->tweak_ctx, key + keylen, keylen);
 }
 
 static int xts_crypt(struct skcipher_request *req, bool encrypt)
 {
 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
-	struct aesni_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
+	struct aesni_xts_ctx *ctx = aes_xts_ctx(tfm);
 	int tail = req->cryptlen % AES_BLOCK_SIZE;
 	struct skcipher_request subreq;
 	struct skcipher_walk walk;
@@ -932,7 +937,7 @@ static int xts_crypt(struct skcipher_request *req, bool encrypt)
 	kernel_fpu_begin();
 
 	/* calculate first value of T */
-	aesni_enc(aes_ctx(&ctx->tweak_ctx), walk.iv, walk.iv);
+	aesni_enc(&ctx->tweak_ctx, walk.iv, walk.iv);
 
 	while (walk.nbytes > 0) {
 		int nbytes = walk.nbytes;
@@ -941,11 +946,11 @@ static int xts_crypt(struct skcipher_request *req, bool encrypt)
 			nbytes &= ~(AES_BLOCK_SIZE - 1);
 
 		if (encrypt)
-			aesni_xts_encrypt(aes_ctx(&ctx->crypt_ctx),
+			aesni_xts_encrypt(&ctx->crypt_ctx,
 					  walk.dst.virt.addr, walk.src.virt.addr,
 					  nbytes, walk.iv);
 		else
-			aesni_xts_decrypt(aes_ctx(&ctx->crypt_ctx),
+			aesni_xts_decrypt(&ctx->crypt_ctx,
 					  walk.dst.virt.addr, walk.src.virt.addr,
 					  nbytes, walk.iv);
 		kernel_fpu_end();
@@ -973,11 +978,11 @@ static int xts_crypt(struct skcipher_request *req, bool encrypt)
 
 		kernel_fpu_begin();
 		if (encrypt)
-			aesni_xts_encrypt(aes_ctx(&ctx->crypt_ctx),
+			aesni_xts_encrypt(&ctx->crypt_ctx,
 					  walk.dst.virt.addr, walk.src.virt.addr,
 					  walk.nbytes, walk.iv);
 		else
-			aesni_xts_decrypt(aes_ctx(&ctx->crypt_ctx),
+			aesni_xts_decrypt(&ctx->crypt_ctx,
 					  walk.dst.virt.addr, walk.src.virt.addr,
 					  walk.nbytes, walk.iv);
 		kernel_fpu_end();
-- 
2.34.1