crypto: arm64/gcm-aes-ce - remove non-SIMD fallback path

Now that kernel mode SIMD is guaranteed to be available when executing
in task or softirq context, we no longer need scalar fallbacks to use
when the NEON is unavailable. So get rid of them.
Reviewed-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NArd Biesheuvel <ardb@kernel.org>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

arch/arm64/crypto/ghash-ce-glue.c

@@ -362,7 +362,6 @@ static int gcm_encrypt(struct aead_request *req)
 
 	err = skcipher_walk_aead_encrypt(&walk, req, false);
 
-	if (likely(crypto_simd_usable())) {
 	do {
 		const u8 *src = walk.src.virt.addr;
 		u8 *dst = walk.dst.virt.addr;
@@ -393,53 +392,6 @@ static int gcm_encrypt(struct aead_request *req)
 
 		err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
 	} while (walk.nbytes);
-	} else {
-		while (walk.nbytes >= AES_BLOCK_SIZE) {
-			int blocks = walk.nbytes / AES_BLOCK_SIZE;
-			const u8 *src = walk.src.virt.addr;
-			u8 *dst = walk.dst.virt.addr;
-			int remaining = blocks;
-
-			do {
-				aes_encrypt(&ctx->aes_key, buf, iv);
-				crypto_xor_cpy(dst, src, buf, AES_BLOCK_SIZE);
-				crypto_inc(iv, AES_BLOCK_SIZE);
-
-				dst += AES_BLOCK_SIZE;
-				src += AES_BLOCK_SIZE;
-			} while (--remaining > 0);
-
-			ghash_do_update(blocks, dg, walk.dst.virt.addr,
-					&ctx->ghash_key, NULL);
-
-			err = skcipher_walk_done(&walk,
-						 walk.nbytes % AES_BLOCK_SIZE);
-		}
-
-		/* handle the tail */
-		if (walk.nbytes) {
-			aes_encrypt(&ctx->aes_key, buf, iv);
-
-			crypto_xor_cpy(walk.dst.virt.addr, walk.src.virt.addr,
-				       buf, walk.nbytes);
-
-			memcpy(buf, walk.dst.virt.addr, walk.nbytes);
-			memset(buf + walk.nbytes, 0, sizeof(buf) - walk.nbytes);
-		}
-
-		tag = (u8 *)&lengths;
-		ghash_do_update(1, dg, tag, &ctx->ghash_key,
-				walk.nbytes ? buf : NULL);
-
-		if (walk.nbytes)
-			err = skcipher_walk_done(&walk, 0);
-
-		put_unaligned_be64(dg[1], tag);
-		put_unaligned_be64(dg[0], tag + 8);
-		put_unaligned_be32(1, iv + GCM_IV_SIZE);
-		aes_encrypt(&ctx->aes_key, iv, iv);
-		crypto_xor(tag, iv, AES_BLOCK_SIZE);
-	}
 
 	if (err)
 		return err;
@@ -464,6 +416,7 @@ static int gcm_decrypt(struct aead_request *req)
 	u64 dg[2] = {};
 	be128 lengths;
 	u8 *tag;
+	int ret;
 	int err;
 
 	lengths.a = cpu_to_be64(req->assoclen * 8);
@@ -481,9 +434,6 @@ static int gcm_decrypt(struct aead_request *req)
 
 	err = skcipher_walk_aead_decrypt(&walk, req, false);
 
-	if (likely(crypto_simd_usable())) {
-		int ret;
-
 	do {
 		const u8 *src = walk.src.virt.addr;
 		u8 *dst = walk.dst.virt.addr;
@@ -500,8 +450,7 @@ static int gcm_decrypt(struct aead_request *req)
 		}
 
 		kernel_neon_begin();
-			ret = pmull_gcm_decrypt(nbytes, dst, src,
-						ctx->ghash_key.h,
+		ret = pmull_gcm_decrypt(nbytes, dst, src, ctx->ghash_key.h,
 					dg, iv, ctx->aes_key.key_enc,
 					nrounds, tag, otag, authsize);
 		kernel_neon_end();
@@ -518,64 +467,8 @@ static int gcm_decrypt(struct aead_request *req)
 
 	if (err)
 		return err;
-		if (ret)
-			return -EBADMSG;
-	} else {
-		while (walk.nbytes >= AES_BLOCK_SIZE) {
-			int blocks = walk.nbytes / AES_BLOCK_SIZE;
-			const u8 *src = walk.src.virt.addr;
-			u8 *dst = walk.dst.virt.addr;
-
-			ghash_do_update(blocks, dg, walk.src.virt.addr,
-					&ctx->ghash_key, NULL);
-
-			do {
-				aes_encrypt(&ctx->aes_key, buf, iv);
-				crypto_xor_cpy(dst, src, buf, AES_BLOCK_SIZE);
-				crypto_inc(iv, AES_BLOCK_SIZE);
-
-				dst += AES_BLOCK_SIZE;
-				src += AES_BLOCK_SIZE;
-			} while (--blocks > 0);
-
-			err = skcipher_walk_done(&walk,
-						 walk.nbytes % AES_BLOCK_SIZE);
-		}
-
-		/* handle the tail */
-		if (walk.nbytes) {
-			memcpy(buf, walk.src.virt.addr, walk.nbytes);
-			memset(buf + walk.nbytes, 0, sizeof(buf) - walk.nbytes);
-		}
-
-		tag = (u8 *)&lengths;
-		ghash_do_update(1, dg, tag, &ctx->ghash_key,
-				walk.nbytes ? buf : NULL);
-
-		if (walk.nbytes) {
-			aes_encrypt(&ctx->aes_key, buf, iv);
-
-			crypto_xor_cpy(walk.dst.virt.addr, walk.src.virt.addr,
-				       buf, walk.nbytes);
-
-			err = skcipher_walk_done(&walk, 0);
-		}
-
-		if (err)
-			return err;
-
-		put_unaligned_be64(dg[1], tag);
-		put_unaligned_be64(dg[0], tag + 8);
-		put_unaligned_be32(1, iv + GCM_IV_SIZE);
-		aes_encrypt(&ctx->aes_key, iv, iv);
-		crypto_xor(tag, iv, AES_BLOCK_SIZE);
 
-		if (crypto_memneq(tag, otag, authsize)) {
-			memzero_explicit(tag, AES_BLOCK_SIZE);
-			return -EBADMSG;
-		}
-	}
-	return 0;
+	return ret ? -EBADMSG : 0;
 }
 
 static struct aead_alg gcm_aes_alg = {