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, 0 insertions, 52 deletions

diff --git a/include/crypto/internal/sha2.h b/include/crypto/internal/sha2.h
deleted file mode 100644
index 7915a3a46bc8..000000000000
--- a/include/crypto/internal/sha2.h
+++ /dev/null
@@ -1,52 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-
-#ifndef _CRYPTO_INTERNAL_SHA2_H
-#define _CRYPTO_INTERNAL_SHA2_H
-
-#include <crypto/sha2.h>
-#include <linux/compiler_attributes.h>
-#include <linux/string.h>
-#include <linux/types.h>
-#include <linux/unaligned.h>
-
-void sha256_blocks_generic(struct sha256_block_state *state,
-			   const u8 *data, size_t nblocks);
-void sha256_blocks_arch(struct sha256_block_state *state,
-			const u8 *data, size_t nblocks);
-
-static __always_inline void sha256_choose_blocks(
-	u32 state[SHA256_STATE_WORDS], const u8 *data, size_t nblocks,
-	bool force_generic, bool force_simd)
-{
-	if (!IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_SHA256) || force_generic)
-		sha256_blocks_generic((struct sha256_block_state *)state, data, nblocks);
-	else
-		sha256_blocks_arch((struct sha256_block_state *)state, data, nblocks);
-}
-
-static __always_inline void sha256_finup(
-	struct crypto_sha256_state *sctx, u8 buf[SHA256_BLOCK_SIZE],
-	size_t len, u8 out[SHA256_DIGEST_SIZE], size_t digest_size,
-	bool force_generic, bool force_simd)
-{
-	const size_t bit_offset = SHA256_BLOCK_SIZE - 8;
-	__be64 *bits = (__be64 *)&buf[bit_offset];
-	int i;
-
-	buf[len++] = 0x80;
-	if (len > bit_offset) {
-		memset(&buf[len], 0, SHA256_BLOCK_SIZE - len);
-		sha256_choose_blocks(sctx->state, buf, 1, force_generic,
-				     force_simd);
-		len = 0;
-	}
-
-	memset(&buf[len], 0, bit_offset - len);
-	*bits = cpu_to_be64(sctx->count << 3);
-	sha256_choose_blocks(sctx->state, buf, 1, force_generic, force_simd);
-
-	for (i = 0; i < digest_size; i += 4)
-		put_unaligned_be32(sctx->state[i / 4], out + i);
-}
-
-#endif /* _CRYPTO_INTERNAL_SHA2_H */