crypto: arm64/ghash - register PMULL variants as separate algos

The arm64 GHASH implementation either uses 8-bit or 64-bit
polynomial multiplication instructions, since the latter are
faster but not mandatory in the architecture.

Since that prevents us from testing both implementations on the
same system, let's expose both implementations to the crypto API,
with the priorities reflecting that the P64 version is the
preferred one if available.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

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

@@ -60,10 +60,6 @@ asmlinkage void pmull_ghash_update_p8(int blocks, u64 dg[], const char *src,
 				      struct ghash_key const *k,
 				      const char *head);
 
-static void (*pmull_ghash_update)(int blocks, u64 dg[], const char *src,
-				  struct ghash_key const *k,
-				  const char *head);
-
 asmlinkage void pmull_gcm_encrypt(int blocks, u64 dg[], u8 dst[],
 				  const u8 src[], struct ghash_key const *k,
 				  u8 ctr[], u32 const rk[], int rounds,
@@ -87,11 +83,15 @@ static int ghash_init(struct shash_desc *desc)
 }
 
 static void ghash_do_update(int blocks, u64 dg[], const char *src,
-			    struct ghash_key *key, const char *head)
+			    struct ghash_key *key, const char *head,
+			    void (*simd_update)(int blocks, u64 dg[],
+						const char *src,
+						struct ghash_key const *k,
+						const char *head))
 {
 	if (likely(may_use_simd())) {
 		kernel_neon_begin();
-		pmull_ghash_update(blocks, dg, src, key, head);
+		simd_update(blocks, dg, src, key, head);
 		kernel_neon_end();
 	} else {
 		be128 dst = { cpu_to_be64(dg[1]), cpu_to_be64(dg[0]) };
@@ -119,8 +119,12 @@ static void ghash_do_update(int blocks, u64 dg[], const char *src,
 /* avoid hogging the CPU for too long */
 #define MAX_BLOCKS	(SZ_64K / GHASH_BLOCK_SIZE)
 
-static int ghash_update(struct shash_desc *desc, const u8 *src,
-			unsigned int len)
+static int __ghash_update(struct shash_desc *desc, const u8 *src,
+			  unsigned int len,
+			  void (*simd_update)(int blocks, u64 dg[],
+					      const char *src,
+					      struct ghash_key const *k,
+					      const char *head))
 {
 	struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);
 	unsigned int partial = ctx->count % GHASH_BLOCK_SIZE;
@@ -146,7 +150,8 @@ static int ghash_update(struct shash_desc *desc, const u8 *src,
 			int chunk = min(blocks, MAX_BLOCKS);
 
 			ghash_do_update(chunk, ctx->digest, src, key,
-					partial ? ctx->buf : NULL);
+					partial ? ctx->buf : NULL,
+					simd_update);
 
 			blocks -= chunk;
 			src += chunk * GHASH_BLOCK_SIZE;
@@ -158,7 +163,39 @@ static int ghash_update(struct shash_desc *desc, const u8 *src,
 	return 0;
 }
 
-static int ghash_final(struct shash_desc *desc, u8 *dst)
+static int ghash_update_p8(struct shash_desc *desc, const u8 *src,
+			   unsigned int len)
+{
+	return __ghash_update(desc, src, len, pmull_ghash_update_p8);
+}
+
+static int ghash_update_p64(struct shash_desc *desc, const u8 *src,
+			    unsigned int len)
+{
+	return __ghash_update(desc, src, len, pmull_ghash_update_p64);
+}
+
+static int ghash_final_p8(struct shash_desc *desc, u8 *dst)
+{
+	struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);
+	unsigned int partial = ctx->count % GHASH_BLOCK_SIZE;
+
+	if (partial) {
+		struct ghash_key *key = crypto_shash_ctx(desc->tfm);
+
+		memset(ctx->buf + partial, 0, GHASH_BLOCK_SIZE - partial);
+
+		ghash_do_update(1, ctx->digest, ctx->buf, key, NULL,
+				pmull_ghash_update_p8);
+	}
+	put_unaligned_be64(ctx->digest[1], dst);
+	put_unaligned_be64(ctx->digest[0], dst + 8);
+
+	*ctx = (struct ghash_desc_ctx){};
+	return 0;
+}
+
+static int ghash_final_p64(struct shash_desc *desc, u8 *dst)
 {
 	struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);
 	unsigned int partial = ctx->count % GHASH_BLOCK_SIZE;
@@ -168,7 +205,8 @@ static int ghash_final(struct shash_desc *desc, u8 *dst)
 
 		memset(ctx->buf + partial, 0, GHASH_BLOCK_SIZE - partial);
 
-		ghash_do_update(1, ctx->digest, ctx->buf, key, NULL);
+		ghash_do_update(1, ctx->digest, ctx->buf, key, NULL,
+				pmull_ghash_update_p64);
 	}
 	put_unaligned_be64(ctx->digest[1], dst);
 	put_unaligned_be64(ctx->digest[0], dst + 8);
@@ -224,7 +262,21 @@ static int ghash_setkey(struct crypto_shash *tfm,
 	return __ghash_setkey(key, inkey, keylen);
 }
 
-static struct shash_alg ghash_alg = {
+static struct shash_alg ghash_alg[] = {{
+	.base.cra_name		= "ghash",
+	.base.cra_driver_name	= "ghash-neon",
+	.base.cra_priority	= 100,
+	.base.cra_blocksize	= GHASH_BLOCK_SIZE,
+	.base.cra_ctxsize	= sizeof(struct ghash_key),
+	.base.cra_module	= THIS_MODULE,
+
+	.digestsize		= GHASH_DIGEST_SIZE,
+	.init			= ghash_init,
+	.update			= ghash_update_p8,
+	.final			= ghash_final_p8,
+	.setkey			= ghash_setkey,
+	.descsize		= sizeof(struct ghash_desc_ctx),
+}, {
 	.base.cra_name		= "ghash",
 	.base.cra_driver_name	= "ghash-ce",
 	.base.cra_priority	= 200,
@@ -234,11 +286,11 @@ static struct shash_alg ghash_alg = {
 
 	.digestsize		= GHASH_DIGEST_SIZE,
 	.init			= ghash_init,
-	.update			= ghash_update,
-	.final			= ghash_final,
+	.update			= ghash_update_p64,
+	.final			= ghash_final_p64,
 	.setkey			= ghash_setkey,
 	.descsize		= sizeof(struct ghash_desc_ctx),
-};
+}};
 
 static int num_rounds(struct crypto_aes_ctx *ctx)
 {
@@ -301,7 +353,8 @@ static void gcm_update_mac(u64 dg[], const u8 *src, int count, u8 buf[],
 		int blocks = count / GHASH_BLOCK_SIZE;
 
 		ghash_do_update(blocks, dg, src, &ctx->ghash_key,
-				*buf_count ? buf : NULL);
+				*buf_count ? buf : NULL,
+				pmull_ghash_update_p64);
 
 		src += blocks * GHASH_BLOCK_SIZE;
 		count %= GHASH_BLOCK_SIZE;
@@ -345,7 +398,8 @@ static void gcm_calculate_auth_mac(struct aead_request *req, u64 dg[])
 
 	if (buf_count) {
 		memset(&buf[buf_count], 0, GHASH_BLOCK_SIZE - buf_count);
-		ghash_do_update(1, dg, buf, &ctx->ghash_key, NULL);
+		ghash_do_update(1, dg, buf, &ctx->ghash_key, NULL,
+				pmull_ghash_update_p64);
 	}
 }
 
@@ -358,7 +412,8 @@ static void gcm_final(struct aead_request *req, struct gcm_aes_ctx *ctx,
 	lengths.a = cpu_to_be64(req->assoclen * 8);
 	lengths.b = cpu_to_be64(cryptlen * 8);
 
-	ghash_do_update(1, dg, (void *)&lengths, &ctx->ghash_key, NULL);
+	ghash_do_update(1, dg, (void *)&lengths, &ctx->ghash_key, NULL,
+			pmull_ghash_update_p64);
 
 	put_unaligned_be64(dg[1], mac);
 	put_unaligned_be64(dg[0], mac + 8);
@@ -434,7 +489,7 @@ static int gcm_encrypt(struct aead_request *req)
 
 			ghash_do_update(walk.nbytes / AES_BLOCK_SIZE, dg,
 					walk.dst.virt.addr, &ctx->ghash_key,
-					NULL);
+					NULL, pmull_ghash_update_p64);
 
 			err = skcipher_walk_done(&walk,
 						 walk.nbytes % (2 * AES_BLOCK_SIZE));
@@ -469,7 +524,8 @@ static int gcm_encrypt(struct aead_request *req)
 
 		memcpy(buf, dst, nbytes);
 		memset(buf + nbytes, 0, GHASH_BLOCK_SIZE - nbytes);
-		ghash_do_update(!!nbytes, dg, buf, &ctx->ghash_key, head);
+		ghash_do_update(!!nbytes, dg, buf, &ctx->ghash_key, head,
+				pmull_ghash_update_p64);
 
 		err = skcipher_walk_done(&walk, 0);
 	}
@@ -558,7 +614,8 @@ static int gcm_decrypt(struct aead_request *req)
 			u8 *src = walk.src.virt.addr;
 
 			ghash_do_update(blocks, dg, walk.src.virt.addr,
-					&ctx->ghash_key, NULL);
+					&ctx->ghash_key, NULL,
+					pmull_ghash_update_p64);
 
 			do {
 				__aes_arm64_encrypt(ctx->aes_key.key_enc,
@@ -602,7 +659,8 @@ static int gcm_decrypt(struct aead_request *req)
 
 		memcpy(buf, src, nbytes);
 		memset(buf + nbytes, 0, GHASH_BLOCK_SIZE - nbytes);
-		ghash_do_update(!!nbytes, dg, buf, &ctx->ghash_key, head);
+		ghash_do_update(!!nbytes, dg, buf, &ctx->ghash_key, head,
+				pmull_ghash_update_p64);
 
 		crypto_xor_cpy(walk.dst.virt.addr, walk.src.virt.addr, iv,
 			       walk.nbytes);
@@ -650,26 +708,30 @@ static int __init ghash_ce_mod_init(void)
 		return -ENODEV;
 
 	if (elf_hwcap & HWCAP_PMULL)
-		pmull_ghash_update = pmull_ghash_update_p64;
-
+		ret = crypto_register_shashes(ghash_alg,
+					      ARRAY_SIZE(ghash_alg));
 	else
-		pmull_ghash_update = pmull_ghash_update_p8;
+		/* only register the first array element */
+		ret = crypto_register_shash(ghash_alg);
 
-	ret = crypto_register_shash(&ghash_alg);
 	if (ret)
 		return ret;
 
 	if (elf_hwcap & HWCAP_PMULL) {
 		ret = crypto_register_aead(&gcm_aes_alg);
 		if (ret)
-			crypto_unregister_shash(&ghash_alg);
+			crypto_unregister_shashes(ghash_alg,
+						  ARRAY_SIZE(ghash_alg));
 	}
 	return ret;
 }
 
 static void __exit ghash_ce_mod_exit(void)
 {
-	crypto_unregister_shash(&ghash_alg);
+	if (elf_hwcap & HWCAP_PMULL)
+		crypto_unregister_shashes(ghash_alg, ARRAY_SIZE(ghash_alg));
+	else
+		crypto_unregister_shash(ghash_alg);
 	crypto_unregister_aead(&gcm_aes_alg);
 }