crypto: lib - create utils module and move __crypto_memneq into it

As requested at
https://lore.kernel.org/r/YtEgzHuuMts0YBCz@gondor.apana.org.au, move
__crypto_memneq into lib/crypto/ and put it under a new tristate.  The
tristate is CRYPTO_LIB_UTILS, and it builds a module libcryptoutils.  As
more crypto library utilities are being added, this creates a single
place for them to go without cluttering up the main lib directory.

The module's main file will be lib/crypto/utils.c.  However, leave
memneq.c as its own file because of its nonstandard license.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/Kconfig

@@ -15,7 +15,7 @@ source "crypto/async_tx/Kconfig"
 #
 menuconfig CRYPTO
 	tristate "Cryptographic API"
-	select LIB_MEMNEQ
+	select CRYPTO_LIB_UTILS
 	help
 	  This option provides the core Cryptographic API.
 

lib/Kconfig

@@ -127,9 +127,6 @@ config TRACE_MMIO_ACCESS
 
 source "lib/crypto/Kconfig"
 
-config LIB_MEMNEQ
-	bool
-
 config CRC_CCITT
 	tristate "CRC-CCITT functions"
 	help

lib/Makefile

@@ -253,7 +253,6 @@ obj-$(CONFIG_DIMLIB) += dim/
 obj-$(CONFIG_SIGNATURE) += digsig.o
 
 lib-$(CONFIG_CLZ_TAB) += clz_tab.o
-lib-$(CONFIG_LIB_MEMNEQ) += memneq.o
 
 obj-$(CONFIG_GENERIC_STRNCPY_FROM_USER) += strncpy_from_user.o
 obj-$(CONFIG_GENERIC_STRNLEN_USER) += strnlen_user.o

lib/crypto/Kconfig

@@ -2,6 +2,9 @@
 
 menu "Crypto library routines"
 
+config CRYPTO_LIB_UTILS
+	tristate
+
 config CRYPTO_LIB_AES
 	tristate
 
@@ -71,7 +74,7 @@ config CRYPTO_LIB_CURVE25519
 	tristate "Curve25519 scalar multiplication library"
 	depends on CRYPTO_ARCH_HAVE_LIB_CURVE25519 || !CRYPTO_ARCH_HAVE_LIB_CURVE25519
 	select CRYPTO_LIB_CURVE25519_GENERIC if CRYPTO_ARCH_HAVE_LIB_CURVE25519=n
-	select LIB_MEMNEQ
+	select CRYPTO_LIB_UTILS
 	help
 	  Enable the Curve25519 library interface. This interface may be
 	  fulfilled by either the generic implementation or an arch-specific

lib/crypto/Makefile

@@ -1,5 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0
 
+obj-$(CONFIG_CRYPTO_LIB_UTILS)			+= libcryptoutils.o
+libcryptoutils-y				:= memneq.o
+
 # chacha is used by the /dev/random driver which is always builtin
 obj-y						+= chacha.o
 obj-$(CONFIG_CRYPTO_LIB_CHACHA_GENERIC)		+= libchacha.o

lib/crypto/memneq.c

@@ -59,8 +59,9 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <crypto/algapi.h>
 #include <asm/unaligned.h>
+#include <crypto/algapi.h>
+#include <linux/module.h>
 
 #ifndef __HAVE_ARCH_CRYPTO_MEMNEQ
 
@@ -174,3 +175,5 @@ noinline unsigned long __crypto_memneq(const void *a, const void *b,
 EXPORT_SYMBOL(__crypto_memneq);
 
 #endif /* __HAVE_ARCH_CRYPTO_MEMNEQ */
+
+MODULE_LICENSE("GPL");