lib/crypto: s390/sha1: Migrate optimized code into library

Instead of exposing the s390-optimized SHA-1 code via s390-specific
crypto_shash algorithms, instead just implement the sha1_blocks()
library function.  This is much simpler, it makes the SHA-1 library
functions be s390-optimized, and it fixes the longstanding issue where
the s390-optimized SHA-1 code was disabled by default.  SHA-1 still
remains available through crypto_shash, but individual architectures no
longer need to handle it.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250712232329.818226-12-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>

Author: Eric Biggers

arch/s390/configs/debug_defconfig

@@ -804,7 +804,6 @@ CONFIG_CRYPTO_USER_API_HASH=m
 CONFIG_CRYPTO_USER_API_SKCIPHER=m
 CONFIG_CRYPTO_USER_API_RNG=m
 CONFIG_CRYPTO_USER_API_AEAD=m
-CONFIG_CRYPTO_SHA1_S390=m
 CONFIG_CRYPTO_SHA3_256_S390=m
 CONFIG_CRYPTO_SHA3_512_S390=m
 CONFIG_CRYPTO_GHASH_S390=m

arch/s390/configs/defconfig

@@ -791,7 +791,6 @@ CONFIG_CRYPTO_USER_API_HASH=m
 CONFIG_CRYPTO_USER_API_SKCIPHER=m
 CONFIG_CRYPTO_USER_API_RNG=m
 CONFIG_CRYPTO_USER_API_AEAD=m
-CONFIG_CRYPTO_SHA1_S390=m
 CONFIG_CRYPTO_SHA3_256_S390=m
 CONFIG_CRYPTO_SHA3_512_S390=m
 CONFIG_CRYPTO_GHASH_S390=m

arch/s390/crypto/Kconfig

@@ -2,16 +2,6 @@
 
 menu "Accelerated Cryptographic Algorithms for CPU (s390)"
 
-config CRYPTO_SHA1_S390
-	tristate "Hash functions: SHA-1"
-	select CRYPTO_HASH
-	help
-	  SHA-1 secure hash algorithm (FIPS 180)
-
-	  Architecture: s390
-
-	  It is available as of z990.
-
 config CRYPTO_SHA3_256_S390
 	tristate "Hash functions: SHA3-224 and SHA3-256"
 	select CRYPTO_HASH

arch/s390/crypto/Makefile

@@ -3,7 +3,6 @@
 # Cryptographic API
 #
 
-obj-$(CONFIG_CRYPTO_SHA1_S390) += sha1_s390.o sha_common.o
 obj-$(CONFIG_CRYPTO_SHA3_256_S390) += sha3_256_s390.o sha_common.o
 obj-$(CONFIG_CRYPTO_SHA3_512_S390) += sha3_512_s390.o sha_common.o
 obj-$(CONFIG_CRYPTO_DES_S390) += des_s390.o

arch/s390/crypto/sha1_s390.c

@@ -150,6 +150,7 @@ config CRYPTO_LIB_SHA1_ARCH
 	default y if ARM64 && KERNEL_MODE_NEON
 	default y if MIPS && CPU_CAVIUM_OCTEON
 	default y if PPC
+	default y if S390
 
 config CRYPTO_LIB_SHA256
 	tristate

lib/crypto/Kconfig

@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * SHA-1 optimized using the CP Assist for Cryptographic Functions (CPACF)
+ *
+ * Copyright 2025 Google LLC
+ */
+#include <asm/cpacf.h>
+#include <linux/cpufeature.h>
+
+static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_cpacf_sha1);
+
+static void sha1_blocks(struct sha1_block_state *state,
+			const u8 *data, size_t nblocks)
+{
+	if (static_branch_likely(&have_cpacf_sha1))
+		cpacf_kimd(CPACF_KIMD_SHA_1, state, data,
+			   nblocks * SHA1_BLOCK_SIZE);
+	else
+		sha1_blocks_generic(state, data, nblocks);
+}
+
+#define sha1_mod_init_arch sha1_mod_init_arch
+static inline void sha1_mod_init_arch(void)
+{
+	if (cpu_have_feature(S390_CPU_FEATURE_MSA) &&
+	    cpacf_query_func(CPACF_KIMD, CPACF_KIMD_SHA_1))
+		static_branch_enable(&have_cpacf_sha1);
+}