lib/crypto: arm/nh: Migrate optimized code into library

Migrate the arm32 NEON implementation of NH into lib/crypto/.  This
makes the nh() function be optimized on arm32 kernels.

Note: this temporarily makes the adiantum template not utilize the arm32
optimized NH code.  This is resolved in a later commit that converts the
adiantum template to use nh() instead of "nhpoly1305".

Link: https://lore.kernel.org/r/20251211011846.8179-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>

7 files changed, 35 insertions, 92 deletions

diff --git a/arch/arm/crypto/Kconfig b/arch/arm/crypto/Kconfig
index f30d743df264..3eb5071bea14 100644
--- a/arch/arm/crypto/Kconfig
+++ b/arch/arm/crypto/Kconfig
@@ -23,16 +23,6 @@ config CRYPTO_GHASH_ARM_CE
 	  that is part of the ARMv8 Crypto Extensions, or a slower variant that
 	  uses the vmull.p8 instruction that is part of the basic NEON ISA.
 
-config CRYPTO_NHPOLY1305_NEON
-	tristate "Hash functions: NHPoly1305 (NEON)"
-	depends on KERNEL_MODE_NEON
-	select CRYPTO_NHPOLY1305
-	help
-	  NHPoly1305 hash function (Adiantum)
-
-	  Architecture: arm using:
-	  - NEON (Advanced SIMD) extensions
-
 config CRYPTO_AES_ARM
 	tristate "Ciphers: AES"
 	select CRYPTO_ALGAPI
diff --git a/arch/arm/crypto/Makefile b/arch/arm/crypto/Makefile
index 86dd43313dbf..d6683e9d4992 100644
--- a/arch/arm/crypto/Makefile
+++ b/arch/arm/crypto/Makefile
@@ -5,7 +5,6 @@
 
 obj-$(CONFIG_CRYPTO_AES_ARM) += aes-arm.o
 obj-$(CONFIG_CRYPTO_AES_ARM_BS) += aes-arm-bs.o
-obj-$(CONFIG_CRYPTO_NHPOLY1305_NEON) += nhpoly1305-neon.o
 
 obj-$(CONFIG_CRYPTO_AES_ARM_CE) += aes-arm-ce.o
 obj-$(CONFIG_CRYPTO_GHASH_ARM_CE) += ghash-arm-ce.o
@@ -14,4 +13,3 @@ aes-arm-y	:= aes-cipher-core.o aes-cipher-glue.o
 aes-arm-bs-y	:= aes-neonbs-core.o aes-neonbs-glue.o
 aes-arm-ce-y	:= aes-ce-core.o aes-ce-glue.o
 ghash-arm-ce-y	:= ghash-ce-core.o ghash-ce-glue.o
-nhpoly1305-neon-y := nh-neon-core.o nhpoly1305-neon-glue.o
diff --git a/arch/arm/crypto/nhpoly1305-neon-glue.c b/arch/arm/crypto/nhpoly1305-neon-glue.c
deleted file mode 100644
index 62cf7ccdde73..000000000000
--- a/arch/arm/crypto/nhpoly1305-neon-glue.c
+++ /dev/null
@@ -1,80 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * NHPoly1305 - ε-almost-∆-universal hash function for Adiantum
- * (NEON accelerated version)
- *
- * Copyright 2018 Google LLC
- */
-
-#include <asm/neon.h>
-#include <asm/simd.h>
-#include <crypto/internal/hash.h>
-#include <crypto/internal/simd.h>
-#include <crypto/nhpoly1305.h>
-#include <linux/module.h>
-
-asmlinkage void nh_neon(const u32 *key, const u8 *message, size_t message_len,
-			__le64 hash[NH_NUM_PASSES]);
-
-static int nhpoly1305_neon_update(struct shash_desc *desc,
-				  const u8 *src, unsigned int srclen)
-{
-	if (srclen < 64 || !crypto_simd_usable())
-		return crypto_nhpoly1305_update(desc, src, srclen);
-
-	do {
-		unsigned int n = min_t(unsigned int, srclen, SZ_4K);
-
-		kernel_neon_begin();
-		crypto_nhpoly1305_update_helper(desc, src, n, nh_neon);
-		kernel_neon_end();
-		src += n;
-		srclen -= n;
-	} while (srclen);
-	return 0;
-}
-
-static int nhpoly1305_neon_digest(struct shash_desc *desc,
-				  const u8 *src, unsigned int srclen, u8 *out)
-{
-	return crypto_nhpoly1305_init(desc) ?:
-	       nhpoly1305_neon_update(desc, src, srclen) ?:
-	       crypto_nhpoly1305_final(desc, out);
-}
-
-static struct shash_alg nhpoly1305_alg = {
-	.base.cra_name		= "nhpoly1305",
-	.base.cra_driver_name	= "nhpoly1305-neon",
-	.base.cra_priority	= 200,
-	.base.cra_ctxsize	= sizeof(struct nhpoly1305_key),
-	.base.cra_module	= THIS_MODULE,
-	.digestsize		= POLY1305_DIGEST_SIZE,
-	.init			= crypto_nhpoly1305_init,
-	.update			= nhpoly1305_neon_update,
-	.final			= crypto_nhpoly1305_final,
-	.digest			= nhpoly1305_neon_digest,
-	.setkey			= crypto_nhpoly1305_setkey,
-	.descsize		= sizeof(struct nhpoly1305_state),
-};
-
-static int __init nhpoly1305_mod_init(void)
-{
-	if (!(elf_hwcap & HWCAP_NEON))
-		return -ENODEV;
-
-	return crypto_register_shash(&nhpoly1305_alg);
-}
-
-static void __exit nhpoly1305_mod_exit(void)
-{
-	crypto_unregister_shash(&nhpoly1305_alg);
-}
-
-module_init(nhpoly1305_mod_init);
-module_exit(nhpoly1305_mod_exit);
-
-MODULE_DESCRIPTION("NHPoly1305 ε-almost-∆-universal hash function (NEON-accelerated)");
-MODULE_LICENSE("GPL v2");
-MODULE_AUTHOR("Eric Biggers <ebiggers@google.com>");
-MODULE_ALIAS_CRYPTO("nhpoly1305");
-MODULE_ALIAS_CRYPTO("nhpoly1305-neon");
diff --git a/lib/crypto/Kconfig b/lib/crypto/Kconfig
index f14c9f5974d8..c6ee7ca77632 100644
--- a/lib/crypto/Kconfig
+++ b/lib/crypto/Kconfig
@@ -117,6 +117,7 @@ config CRYPTO_LIB_NH
 config CRYPTO_LIB_NH_ARCH
 	bool
 	depends on CRYPTO_LIB_NH && !UML
+	default y if ARM && KERNEL_MODE_NEON
 
 config CRYPTO_LIB_POLY1305
 	tristate
diff --git a/lib/crypto/Makefile b/lib/crypto/Makefile
index 929b84568809..6dae7e182847 100644
--- a/lib/crypto/Makefile
+++ b/lib/crypto/Makefile
@@ -135,6 +135,7 @@ obj-$(CONFIG_CRYPTO_LIB_NH) += libnh.o
 libnh-y := nh.o
 ifeq ($(CONFIG_CRYPTO_LIB_NH_ARCH),y)
 CFLAGS_nh.o += -I$(src)/$(SRCARCH)
+libnh-$(CONFIG_ARM) += arm/nh-neon-core.o
 endif
 
 ################################################################################
diff --git a/arch/arm/crypto/nh-neon-core.S b/lib/crypto/arm/nh-neon-core.S
index 01620a0782ca..01620a0782ca 100644
--- a/arch/arm/crypto/nh-neon-core.S
+++ b/lib/crypto/arm/nh-neon-core.S
diff --git a/lib/crypto/arm/nh.h b/lib/crypto/arm/nh.h
new file mode 100644
index 000000000000..c9f39d819336
--- /dev/null
+++ b/lib/crypto/arm/nh.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * ARM32 accelerated implementation of NH
+ *
+ * Copyright 2018 Google LLC
+ */
+
+#include <asm/neon.h>
+#include <asm/simd.h>
+
+static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_neon);
+
+asmlinkage void nh_neon(const u32 *key, const u8 *message, size_t message_len,
+			__le64 hash[NH_NUM_PASSES]);
+
+static bool nh_arch(const u32 *key, const u8 *message, size_t message_len,
+		    __le64 hash[NH_NUM_PASSES])
+{
+	if (static_branch_likely(&have_neon) && message_len >= 64 &&
+	    may_use_simd()) {
+		scoped_ksimd()
+			nh_neon(key, message, message_len, hash);
+		return true;
+	}
+	return false;
+}
+
+#define nh_mod_init_arch nh_mod_init_arch
+static void nh_mod_init_arch(void)
+{
+	if (elf_hwcap & HWCAP_NEON)
+		static_branch_enable(&have_neon);
+}