crypto: s390/sha256 - implement library instead of shash

Instead of providing crypto_shash algorithms for the arch-optimized
SHA-256 code, instead implement the SHA-256 library.  This is much
simpler, it makes the SHA-256 library functions be arch-optimized, and
it fixes the longstanding issue where the arch-optimized SHA-256 was
disabled by default.  SHA-256 still remains available through
crypto_shash, but individual architectures no longer need to handle it.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/s390/configs/debug_defconfig

@@ -795,7 +795,6 @@ CONFIG_CRYPTO_USER_API_RNG=m
 CONFIG_CRYPTO_USER_API_AEAD=m
 CONFIG_CRYPTO_SHA512_S390=m
 CONFIG_CRYPTO_SHA1_S390=m
-CONFIG_CRYPTO_SHA256_S390=m
 CONFIG_CRYPTO_SHA3_256_S390=m
 CONFIG_CRYPTO_SHA3_512_S390=m
 CONFIG_CRYPTO_GHASH_S390=m

arch/s390/configs/defconfig

@@ -782,7 +782,6 @@ CONFIG_CRYPTO_USER_API_RNG=m
 CONFIG_CRYPTO_USER_API_AEAD=m
 CONFIG_CRYPTO_SHA512_S390=m
 CONFIG_CRYPTO_SHA1_S390=m
-CONFIG_CRYPTO_SHA256_S390=m
 CONFIG_CRYPTO_SHA3_256_S390=m
 CONFIG_CRYPTO_SHA3_512_S390=m
 CONFIG_CRYPTO_GHASH_S390=m

arch/s390/crypto/Kconfig

@@ -22,16 +22,6 @@ config CRYPTO_SHA1_S390
 
 	  It is available as of z990.
 
-config CRYPTO_SHA256_S390
-	tristate "Hash functions: SHA-224 and SHA-256"
-	select CRYPTO_HASH
-	help
-	  SHA-224 and SHA-256 secure hash algorithms (FIPS 180)
-
-	  Architecture: s390
-
-	  It is available as of z9.
-
 config CRYPTO_SHA3_256_S390
 	tristate "Hash functions: SHA3-224 and SHA3-256"
 	select CRYPTO_HASH

arch/s390/crypto/Makefile

@@ -4,7 +4,6 @@
 #
 
 obj-$(CONFIG_CRYPTO_SHA1_S390) += sha1_s390.o sha_common.o
-obj-$(CONFIG_CRYPTO_SHA256_S390) += sha256_s390.o sha_common.o
 obj-$(CONFIG_CRYPTO_SHA512_S390) += sha512_s390.o sha_common.o
 obj-$(CONFIG_CRYPTO_SHA3_256_S390) += sha3_256_s390.o sha_common.o
 obj-$(CONFIG_CRYPTO_SHA3_512_S390) += sha3_512_s390.o sha_common.o

arch/s390/crypto/sha256_s390.c

@@ -1,144 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0+
-/*
- * Cryptographic API.
- *
- * s390 implementation of the SHA256 and SHA224 Secure Hash Algorithm.
- *
- * s390 Version:
- *   Copyright IBM Corp. 2005, 2011
- *   Author(s): Jan Glauber (jang@de.ibm.com)
- */
-#include <asm/cpacf.h>
-#include <crypto/internal/hash.h>
-#include <crypto/sha2.h>
-#include <linux/cpufeature.h>
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/string.h>
-
-#include "sha.h"
-
-static int s390_sha256_init(struct shash_desc *desc)
-{
-	struct s390_sha_ctx *sctx = shash_desc_ctx(desc);
-
-	sctx->state[0] = SHA256_H0;
-	sctx->state[1] = SHA256_H1;
-	sctx->state[2] = SHA256_H2;
-	sctx->state[3] = SHA256_H3;
-	sctx->state[4] = SHA256_H4;
-	sctx->state[5] = SHA256_H5;
-	sctx->state[6] = SHA256_H6;
-	sctx->state[7] = SHA256_H7;
-	sctx->count = 0;
-	sctx->func = CPACF_KIMD_SHA_256;
-
-	return 0;
-}
-
-static int sha256_export(struct shash_desc *desc, void *out)
-{
-	struct s390_sha_ctx *sctx = shash_desc_ctx(desc);
-	struct crypto_sha256_state *octx = out;
-
-	octx->count = sctx->count;
-	memcpy(octx->state, sctx->state, sizeof(octx->state));
-	return 0;
-}
-
-static int sha256_import(struct shash_desc *desc, const void *in)
-{
-	struct s390_sha_ctx *sctx = shash_desc_ctx(desc);
-	const struct crypto_sha256_state *ictx = in;
-
-	sctx->count = ictx->count;
-	memcpy(sctx->state, ictx->state, sizeof(ictx->state));
-	sctx->func = CPACF_KIMD_SHA_256;
-	return 0;
-}
-
-static struct shash_alg sha256_alg = {
-	.digestsize	=	SHA256_DIGEST_SIZE,
-	.init		=	s390_sha256_init,
-	.update		=	s390_sha_update_blocks,
-	.finup		=	s390_sha_finup,
-	.export		=	sha256_export,
-	.import		=	sha256_import,
-	.descsize	=	S390_SHA_CTX_SIZE,
-	.statesize	=	sizeof(struct crypto_sha256_state),
-	.base		=	{
-		.cra_name	=	"sha256",
-		.cra_driver_name=	"sha256-s390",
-		.cra_priority	=	300,
-		.cra_flags	=	CRYPTO_AHASH_ALG_BLOCK_ONLY,
-		.cra_blocksize	=	SHA256_BLOCK_SIZE,
-		.cra_module	=	THIS_MODULE,
-	}
-};
-
-static int s390_sha224_init(struct shash_desc *desc)
-{
-	struct s390_sha_ctx *sctx = shash_desc_ctx(desc);
-
-	sctx->state[0] = SHA224_H0;
-	sctx->state[1] = SHA224_H1;
-	sctx->state[2] = SHA224_H2;
-	sctx->state[3] = SHA224_H3;
-	sctx->state[4] = SHA224_H4;
-	sctx->state[5] = SHA224_H5;
-	sctx->state[6] = SHA224_H6;
-	sctx->state[7] = SHA224_H7;
-	sctx->count = 0;
-	sctx->func = CPACF_KIMD_SHA_256;
-
-	return 0;
-}
-
-static struct shash_alg sha224_alg = {
-	.digestsize	=	SHA224_DIGEST_SIZE,
-	.init		=	s390_sha224_init,
-	.update		=	s390_sha_update_blocks,
-	.finup		=	s390_sha_finup,
-	.export		=	sha256_export,
-	.import		=	sha256_import,
-	.descsize	=	S390_SHA_CTX_SIZE,
-	.statesize	=	sizeof(struct crypto_sha256_state),
-	.base		=	{
-		.cra_name	=	"sha224",
-		.cra_driver_name=	"sha224-s390",
-		.cra_priority	=	300,
-		.cra_flags	=	CRYPTO_AHASH_ALG_BLOCK_ONLY,
-		.cra_blocksize	=	SHA224_BLOCK_SIZE,
-		.cra_module	=	THIS_MODULE,
-	}
-};
-
-static int __init sha256_s390_init(void)
-{
-	int ret;
-
-	if (!cpacf_query_func(CPACF_KIMD, CPACF_KIMD_SHA_256))
-		return -ENODEV;
-	ret = crypto_register_shash(&sha256_alg);
-	if (ret < 0)
-		goto out;
-	ret = crypto_register_shash(&sha224_alg);
-	if (ret < 0)
-		crypto_unregister_shash(&sha256_alg);
-out:
-	return ret;
-}
-
-static void __exit sha256_s390_fini(void)
-{
-	crypto_unregister_shash(&sha224_alg);
-	crypto_unregister_shash(&sha256_alg);
-}
-
-module_cpu_feature_match(S390_CPU_FEATURE_MSA, sha256_s390_init);
-module_exit(sha256_s390_fini);
-
-MODULE_ALIAS_CRYPTO("sha256");
-MODULE_ALIAS_CRYPTO("sha224");
-MODULE_LICENSE("GPL");
-MODULE_DESCRIPTION("SHA256 and SHA224 Secure Hash Algorithm");

arch/s390/lib/crypto/Kconfig

@@ -5,3 +5,9 @@ config CRYPTO_CHACHA_S390
 	default CRYPTO_LIB_CHACHA
 	select CRYPTO_LIB_CHACHA_GENERIC
 	select CRYPTO_ARCH_HAVE_LIB_CHACHA
+
+config CRYPTO_SHA256_S390
+	tristate
+	default CRYPTO_LIB_SHA256
+	select CRYPTO_ARCH_HAVE_LIB_SHA256
+	select CRYPTO_LIB_SHA256_GENERIC

arch/s390/lib/crypto/Makefile

@@ -2,3 +2,5 @@
 
 obj-$(CONFIG_CRYPTO_CHACHA_S390) += chacha_s390.o
 chacha_s390-y := chacha-glue.o chacha-s390.o
+
+obj-$(CONFIG_CRYPTO_SHA256_S390) += sha256.o

arch/s390/lib/crypto/sha256.c

@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * SHA-256 optimized using the CP Assist for Cryptographic Functions (CPACF)
+ *
+ * Copyright 2025 Google LLC
+ */
+#include <asm/cpacf.h>
+#include <crypto/internal/sha2.h>
+#include <linux/cpufeature.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_cpacf_sha256);
+
+void sha256_blocks_arch(u32 state[SHA256_STATE_WORDS],
+			const u8 *data, size_t nblocks)
+{
+	if (static_branch_likely(&have_cpacf_sha256))
+		cpacf_kimd(CPACF_KIMD_SHA_256, state, data,
+			   nblocks * SHA256_BLOCK_SIZE);
+	else
+		sha256_blocks_generic(state, data, nblocks);
+}
+EXPORT_SYMBOL(sha256_blocks_arch);
+
+bool sha256_is_arch_optimized(void)
+{
+	return static_key_enabled(&have_cpacf_sha256);
+}
+EXPORT_SYMBOL(sha256_is_arch_optimized);
+
+static int __init sha256_s390_mod_init(void)
+{
+	if (cpu_have_feature(S390_CPU_FEATURE_MSA) &&
+	    cpacf_query_func(CPACF_KIMD, CPACF_KIMD_SHA_256))
+		static_branch_enable(&have_cpacf_sha256);
+	return 0;
+}
+arch_initcall(sha256_s390_mod_init);
+
+static void __exit sha256_s390_mod_exit(void)
+{
+}
+module_exit(sha256_s390_mod_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("SHA-256 using the CP Assist for Cryptographic Functions (CPACF)");