crypto: aes - move sync ctr(aes) to AES library and generic helper

In preparation of duplicating the sync ctr(aes) functionality to modules
under arch/arm, move the helper function from a inline .h file to the
AES library, which is already depended upon by the drivers that use this
fallback.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/arm64/crypto/aes-ctr-fallback.h

-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * Fallback for sync aes(ctr) in contexts where kernel mode NEON
- * is not allowed
- *
- * Copyright (C) 2017 Linaro Ltd <ard.biesheuvel@linaro.org>
- */
-
-#include <crypto/aes.h>
-#include <crypto/internal/skcipher.h>
-
-asmlinkage void __aes_arm64_encrypt(u32 *rk, u8 *out, const u8 *in, int rounds);
-
-static inline int aes_ctr_encrypt_fallback(struct crypto_aes_ctx *ctx,
-					   struct skcipher_request *req)
-{
-	struct skcipher_walk walk;
-	u8 buf[AES_BLOCK_SIZE];
-	int err;
-
-	err = skcipher_walk_virt(&walk, req, true);
-
-	while (walk.nbytes > 0) {
-		u8 *dst = walk.dst.virt.addr;
-		u8 *src = walk.src.virt.addr;
-		int nbytes = walk.nbytes;
-		int tail = 0;
-
-		if (nbytes < walk.total) {
-			nbytes = round_down(nbytes, AES_BLOCK_SIZE);
-			tail = walk.nbytes % AES_BLOCK_SIZE;
-		}
-
-		do {
-			int bsize = min(nbytes, AES_BLOCK_SIZE);
-
-			__aes_arm64_encrypt(ctx->key_enc, buf, walk.iv,
-					    6 + ctx->key_length / 4);
-			crypto_xor_cpy(dst, src, buf, bsize);
-			crypto_inc(walk.iv, AES_BLOCK_SIZE);
-
-			dst += AES_BLOCK_SIZE;
-			src += AES_BLOCK_SIZE;
-			nbytes -= AES_BLOCK_SIZE;
-		} while (nbytes > 0);
-
-		err = skcipher_walk_done(&walk, tail);
-	}
-	return err;
-}

arch/arm64/crypto/aes-glue.c

@@ -9,6 +9,7 @@
 #include <asm/hwcap.h>
 #include <asm/simd.h>
 #include <crypto/aes.h>
+#include <crypto/ctr.h>
 #include <crypto/internal/hash.h>
 #include <crypto/internal/simd.h>
 #include <crypto/internal/skcipher.h>
@@ -18,7 +19,6 @@
 #include <crypto/xts.h>
 
 #include "aes-ce-setkey.h"
-#include "aes-ctr-fallback.h"
 
 #ifdef USE_V8_CRYPTO_EXTENSIONS
 #define MODE			"ce"
@@ -401,13 +401,25 @@ static int ctr_encrypt(struct skcipher_request *req)
 	return err;
 }
 
-static int ctr_encrypt_sync(struct skcipher_request *req)
+static void ctr_encrypt_one(struct crypto_skcipher *tfm, const u8 *src, u8 *dst)
 {
-	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
-	struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
+	const struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
+	unsigned long flags;
 
+	/*
+	 * Temporarily disable interrupts to avoid races where
+	 * cachelines are evicted when the CPU is interrupted
+	 * to do something else.
+	 */
+	local_irq_save(flags);
+	aes_encrypt(ctx, dst, src);
+	local_irq_restore(flags);
+}
+
+static int ctr_encrypt_sync(struct skcipher_request *req)
+{
 	if (!crypto_simd_usable())
-		return aes_ctr_encrypt_fallback(ctx, req);
+		return crypto_ctr_encrypt_walk(req, ctr_encrypt_one);
 
 	return ctr_encrypt(req);
 }

arch/arm64/crypto/aes-neonbs-glue.c

@@ -8,13 +8,12 @@
 #include <asm/neon.h>
 #include <asm/simd.h>
 #include <crypto/aes.h>
+#include <crypto/ctr.h>
 #include <crypto/internal/simd.h>
 #include <crypto/internal/skcipher.h>
 #include <crypto/xts.h>
 #include <linux/module.h>
 
-#include "aes-ctr-fallback.h"
-
 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
 MODULE_LICENSE("GPL v2");
 
@@ -280,13 +279,25 @@ static int aesbs_xts_setkey(struct crypto_skcipher *tfm, const u8 *in_key,
 	return aesbs_setkey(tfm, in_key, key_len);
 }
 
-static int ctr_encrypt_sync(struct skcipher_request *req)
+static void ctr_encrypt_one(struct crypto_skcipher *tfm, const u8 *src, u8 *dst)
 {
-	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 	struct aesbs_ctr_ctx *ctx = crypto_skcipher_ctx(tfm);
+	unsigned long flags;
+
+	/*
+	 * Temporarily disable interrupts to avoid races where
+	 * cachelines are evicted when the CPU is interrupted
+	 * to do something else.
+	 */
+	local_irq_save(flags);
+	aes_encrypt(&ctx->fallback, dst, src);
+	local_irq_restore(flags);
+}
 
+static int ctr_encrypt_sync(struct skcipher_request *req)
+{
 	if (!crypto_simd_usable())
-		return aes_ctr_encrypt_fallback(&ctx->fallback, req);
+		return crypto_ctr_encrypt_walk(req, ctr_encrypt_one);
 
 	return ctr_encrypt(req);
 }