crypto: arm64/sha1-ce - add non-SIMD generic fallback

The arm64 kernel will shortly disallow nested kernel mode NEON, so
add a fallback to scalar C code that can be invoked in that case.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/arm64/crypto/Kconfig

@@ -18,8 +18,9 @@ config CRYPTO_SHA512_ARM64
 
 config CRYPTO_SHA1_ARM64_CE
 	tristate "SHA-1 digest algorithm (ARMv8 Crypto Extensions)"
-	depends on ARM64 && KERNEL_MODE_NEON
+	depends on KERNEL_MODE_NEON
 	select CRYPTO_HASH
+	select CRYPTO_SHA1
 
 config CRYPTO_SHA2_ARM64_CE
 	tristate "SHA-224/SHA-256 digest algorithm (ARMv8 Crypto Extensions)"

arch/arm64/crypto/sha1-ce-glue.c

 /*
  * sha1-ce-glue.c - SHA-1 secure hash using ARMv8 Crypto Extensions
  *
- * Copyright (C) 2014 Linaro Ltd <ard.biesheuvel@linaro.org>
+ * Copyright (C) 2014 - 2017 Linaro Ltd <ard.biesheuvel@linaro.org>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -9,6 +9,7 @@
  */
 
 #include <asm/neon.h>
+#include <asm/simd.h>
 #include <asm/unaligned.h>
 #include <crypto/internal/hash.h>
 #include <crypto/sha.h>
@@ -37,8 +38,11 @@ static int sha1_ce_update(struct shash_desc *desc, const u8 *data,
 {
 	struct sha1_ce_state *sctx = shash_desc_ctx(desc);
 
+	if (!may_use_simd())
+		return crypto_sha1_update(desc, data, len);
+
 	sctx->finalize = 0;
-	kernel_neon_begin_partial(16);
+	kernel_neon_begin();
 	sha1_base_do_update(desc, data, len,
 			    (sha1_block_fn *)sha1_ce_transform);
 	kernel_neon_end();
@@ -52,13 +56,16 @@ static int sha1_ce_finup(struct shash_desc *desc, const u8 *data,
 	struct sha1_ce_state *sctx = shash_desc_ctx(desc);
 	bool finalize = !sctx->sst.count && !(len % SHA1_BLOCK_SIZE);
 
+	if (!may_use_simd())
+		return crypto_sha1_finup(desc, data, len, out);
+
 	/*
 	 * Allow the asm code to perform the finalization if there is no
 	 * partial data and the input is a round multiple of the block size.
 	 */
 	sctx->finalize = finalize;
 
-	kernel_neon_begin_partial(16);
+	kernel_neon_begin();
 	sha1_base_do_update(desc, data, len,
 			    (sha1_block_fn *)sha1_ce_transform);
 	if (!finalize)
@@ -71,8 +78,11 @@ static int sha1_ce_final(struct shash_desc *desc, u8 *out)
 {
 	struct sha1_ce_state *sctx = shash_desc_ctx(desc);
 
+	if (!may_use_simd())
+		return crypto_sha1_finup(desc, NULL, 0, out);
+
 	sctx->finalize = 0;
-	kernel_neon_begin_partial(16);
+	kernel_neon_begin();
 	sha1_base_do_finalize(desc, (sha1_block_fn *)sha1_ce_transform);
 	kernel_neon_end();
 	return sha1_base_finish(desc, out);