lib/crypto: arm/blake2b: Migrate optimized code into library

Migrate the arm-optimized BLAKE2b code from arch/arm/crypto/ to
lib/crypto/arm/.  This makes the BLAKE2b library able to use it, and it
also simplifies the code because it's easier to integrate with the
library than crypto_shash.

This temporarily makes the arm-optimized BLAKE2b code unavailable via
crypto_shash.  A later commit reimplements the blake2b-* crypto_shash
algorithms on top of the BLAKE2b library API, making it available again.

Note that as per the lib/crypto/ convention, the optimized code is now
enabled by default.  So, this also fixes the longstanding issue where
the optimized BLAKE2b code was not enabled by default.

To see the diff from arch/arm/crypto/blake2b-neon-glue.c to
lib/crypto/arm/blake2b.h, view this commit with 'git show -M10'.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20251018043106.375964-8-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>

1 files changed, 41 insertions, 0 deletions

diff --git a/lib/crypto/arm/blake2b.h b/lib/crypto/arm/blake2b.h
new file mode 100644
index 000000000000..1b9154d119db
--- /dev/null
+++ b/lib/crypto/arm/blake2b.h
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * BLAKE2b digest algorithm, NEON accelerated
+ *
+ * Copyright 2020 Google LLC
+ */
+
+#include <asm/neon.h>
+#include <asm/simd.h>
+
+static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_neon);
+
+asmlinkage void blake2b_compress_neon(struct blake2b_ctx *ctx,
+				      const u8 *data, size_t nblocks, u32 inc);
+
+static void blake2b_compress(struct blake2b_ctx *ctx,
+			     const u8 *data, size_t nblocks, u32 inc)
+{
+	if (!static_branch_likely(&have_neon) || !may_use_simd()) {
+		blake2b_compress_generic(ctx, data, nblocks, inc);
+		return;
+	}
+	do {
+		const size_t blocks = min_t(size_t, nblocks,
+					    SZ_4K / BLAKE2B_BLOCK_SIZE);
+
+		kernel_neon_begin();
+		blake2b_compress_neon(ctx, data, blocks, inc);
+		kernel_neon_end();
+
+		data += blocks * BLAKE2B_BLOCK_SIZE;
+		nblocks -= blocks;
+	} while (nblocks);
+}
+
+#define blake2b_mod_init_arch blake2b_mod_init_arch
+static void blake2b_mod_init_arch(void)
+{
+	if (elf_hwcap & HWCAP_NEON)
+		static_branch_enable(&have_neon);
+}