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>

3 files changed, 3 insertions, 19 deletions

diff --git a/lib/crypto/powerpc/Kconfig b/lib/crypto/powerpc/Kconfig
index 3f9e1bbd9905..2eaeb7665a6a 100644
--- a/lib/crypto/powerpc/Kconfig
+++ b/lib/crypto/powerpc/Kconfig
@@ -14,9 +14,3 @@ config CRYPTO_POLY1305_P10
 	default CRYPTO_LIB_POLY1305
 	select CRYPTO_ARCH_HAVE_LIB_POLY1305
 	select CRYPTO_LIB_POLY1305_GENERIC
-
-config CRYPTO_SHA256_PPC_SPE
-	tristate
-	depends on SPE
-	default CRYPTO_LIB_SHA256
-	select CRYPTO_ARCH_HAVE_LIB_SHA256
diff --git a/lib/crypto/powerpc/Makefile b/lib/crypto/powerpc/Makefile
index 27f231f8e334..5709ae14258a 100644
--- a/lib/crypto/powerpc/Makefile
+++ b/lib/crypto/powerpc/Makefile
@@ -5,6 +5,3 @@ chacha-p10-crypto-y := chacha-p10-glue.o chacha-p10le-8x.o
 
 obj-$(CONFIG_CRYPTO_POLY1305_P10) += poly1305-p10-crypto.o
 poly1305-p10-crypto-y := poly1305-p10-glue.o poly1305-p10le_64.o
-
-obj-$(CONFIG_CRYPTO_SHA256_PPC_SPE) += sha256-ppc-spe.o
-sha256-ppc-spe-y := sha256.o sha256-spe-asm.o
diff --git a/lib/crypto/powerpc/sha256.c b/lib/crypto/powerpc/sha256.h
index 14b8adcdcfc2..50d355441c7e 100644
--- a/lib/crypto/powerpc/sha256.c
+++ b/lib/crypto/powerpc/sha256.h
@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
+/* SPDX-License-Identifier: GPL-2.0-or-later */
 /*
  * SHA-256 Secure Hash Algorithm, SPE optimized
  *
@@ -9,9 +9,6 @@
  */
 
 #include <asm/switch_to.h>
-#include <crypto/internal/sha2.h>
-#include <linux/kernel.h>
-#include <linux/module.h>
 #include <linux/preempt.h>
 
 /*
@@ -43,8 +40,8 @@ static void spe_end(void)
 	preempt_enable();
 }
 
-void sha256_blocks_arch(struct sha256_block_state *state,
-			const u8 *data, size_t nblocks)
+static void sha256_blocks(struct sha256_block_state *state,
+			  const u8 *data, size_t nblocks)
 {
 	do {
 		/* cut input data into smaller blocks */
@@ -59,7 +56,3 @@ void sha256_blocks_arch(struct sha256_block_state *state,
 		nblocks -= unit;
 	} while (nblocks);
 }
-EXPORT_SYMBOL_GPL(sha256_blocks_arch);
-
-MODULE_LICENSE("GPL");
-MODULE_DESCRIPTION("SHA-256 Secure Hash Algorithm, SPE optimized");