lib/crypto: sha256: Consolidate into single module

Consolidate the CPU-based SHA-256 code into a single module, following
what I did with SHA-512:

- Each arch now provides a header file lib/crypto/$(SRCARCH)/sha256.h,
  replacing lib/crypto/$(SRCARCH)/sha256.c.  The header defines
  sha256_blocks() and optionally sha256_mod_init_arch().  It is included
  by lib/crypto/sha256.c, and thus the code gets built into the single
  libsha256 module, with proper inlining and dead code elimination.

- sha256_blocks_generic() is moved from lib/crypto/sha256-generic.c into
  lib/crypto/sha256.c.  It's now a static function marked with
  __maybe_unused, so the compiler automatically eliminates it in any
  cases where it's not used.

- Whether arch-optimized SHA-256 is buildable is now controlled
  centrally by lib/crypto/Kconfig instead of by
  lib/crypto/$(SRCARCH)/Kconfig.  The conditions for enabling it remain
  the same as before, and it remains enabled by default.

- Any additional arch-specific translation units for the optimized
  SHA-256 code (such as assembly files) are now compiled by
  lib/crypto/Makefile instead of lib/crypto/$(SRCARCH)/Makefile.

Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250630160645.3198-13-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>

1 files changed, 58 insertions, 0 deletions

diff --git a/lib/crypto/mips/sha256.h b/lib/crypto/mips/sha256.h
new file mode 100644
index 000000000000..ccccfd131634
--- /dev/null
+++ b/lib/crypto/mips/sha256.h
@@ -0,0 +1,58 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * SHA-256 Secure Hash Algorithm.
+ *
+ * Adapted for OCTEON by Aaro Koskinen <aaro.koskinen@iki.fi>.
+ *
+ * Based on crypto/sha256_generic.c, which is:
+ *
+ * Copyright (c) Jean-Luc Cooke <jlcooke@certainkey.com>
+ * Copyright (c) Andrew McDonald <andrew@mcdonald.org.uk>
+ * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
+ * SHA224 Support Copyright 2007 Intel Corporation <jonathan.lynch@intel.com>
+ */
+
+#include <asm/octeon/crypto.h>
+#include <asm/octeon/octeon.h>
+
+/*
+ * We pass everything as 64-bit. OCTEON can handle misaligned data.
+ */
+
+static void sha256_blocks(struct sha256_block_state *state,
+			  const u8 *data, size_t nblocks)
+{
+	struct octeon_cop2_state cop2_state;
+	u64 *state64 = (u64 *)state;
+	unsigned long flags;
+
+	if (!octeon_has_crypto())
+		return sha256_blocks_generic(state, data, nblocks);
+
+	flags = octeon_crypto_enable(&cop2_state);
+	write_octeon_64bit_hash_dword(state64[0], 0);
+	write_octeon_64bit_hash_dword(state64[1], 1);
+	write_octeon_64bit_hash_dword(state64[2], 2);
+	write_octeon_64bit_hash_dword(state64[3], 3);
+
+	do {
+		const u64 *block = (const u64 *)data;
+
+		write_octeon_64bit_block_dword(block[0], 0);
+		write_octeon_64bit_block_dword(block[1], 1);
+		write_octeon_64bit_block_dword(block[2], 2);
+		write_octeon_64bit_block_dword(block[3], 3);
+		write_octeon_64bit_block_dword(block[4], 4);
+		write_octeon_64bit_block_dword(block[5], 5);
+		write_octeon_64bit_block_dword(block[6], 6);
+		octeon_sha256_start(block[7]);
+
+		data += SHA256_BLOCK_SIZE;
+	} while (--nblocks);
+
+	state64[0] = read_octeon_64bit_hash_dword(0);
+	state64[1] = read_octeon_64bit_hash_dword(1);
+	state64[2] = read_octeon_64bit_hash_dword(2);
+	state64[3] = read_octeon_64bit_hash_dword(3);
+	octeon_crypto_disable(&cop2_state, flags);
+}