lib/crypto: blake2s: include as built-in

In preparation for using blake2s in the RNG, we change the way that it
is wired-in to the build system. Instead of using ifdefs to select the
right symbol, we use weak symbols. And because ARM doesn't need the
generic implementation, we make the generic one default only if an arch
library doesn't need it already, and then have arch libraries that do
need it opt-in. So that the arch libraries can remain tristate rather
than bool, we then split the shash part from the glue code.

Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: linux-kbuild@vger.kernel.org
Cc: linux-crypto@vger.kernel.org
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

4 files changed, 15 insertions, 29 deletions

diff --git a/lib/crypto/Kconfig b/lib/crypto/Kconfig
index 545ccbddf6a1..8620f38e117c 100644
--- a/lib/crypto/Kconfig
+++ b/lib/crypto/Kconfig
@@ -1,7 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
 
-comment "Crypto library routines"
-
 config CRYPTO_LIB_AES
 	tristate
 
@@ -9,14 +7,14 @@ config CRYPTO_LIB_ARC4
 	tristate
 
 config CRYPTO_ARCH_HAVE_LIB_BLAKE2S
-	tristate
+	bool
 	help
 	  Declares whether the architecture provides an arch-specific
 	  accelerated implementation of the Blake2s library interface,
 	  either builtin or as a module.
 
 config CRYPTO_LIB_BLAKE2S_GENERIC
-	tristate
+	def_bool !CRYPTO_ARCH_HAVE_LIB_BLAKE2S
 	help
 	  This symbol can be depended upon by arch implementations of the
 	  Blake2s library interface that require the generic code as a
@@ -24,15 +22,6 @@ config CRYPTO_LIB_BLAKE2S_GENERIC
 	  implementation is enabled, this implementation serves the users
 	  of CRYPTO_LIB_BLAKE2S.
 
-config CRYPTO_LIB_BLAKE2S
-	tristate "BLAKE2s hash function library"
-	depends on CRYPTO_ARCH_HAVE_LIB_BLAKE2S || !CRYPTO_ARCH_HAVE_LIB_BLAKE2S
-	select CRYPTO_LIB_BLAKE2S_GENERIC if CRYPTO_ARCH_HAVE_LIB_BLAKE2S=n
-	help
-	  Enable the Blake2s library interface. This interface may be fulfilled
-	  by either the generic implementation or an arch-specific one, if one
-	  is available and enabled.
-
 config CRYPTO_ARCH_HAVE_LIB_CHACHA
 	tristate
 	help
@@ -51,7 +40,7 @@ config CRYPTO_LIB_CHACHA_GENERIC
 	  of CRYPTO_LIB_CHACHA.
 
 config CRYPTO_LIB_CHACHA
-	tristate "ChaCha library interface"
+	tristate
 	depends on CRYPTO_ARCH_HAVE_LIB_CHACHA || !CRYPTO_ARCH_HAVE_LIB_CHACHA
 	select CRYPTO_LIB_CHACHA_GENERIC if CRYPTO_ARCH_HAVE_LIB_CHACHA=n
 	help
@@ -76,7 +65,7 @@ config CRYPTO_LIB_CURVE25519_GENERIC
 	  of CRYPTO_LIB_CURVE25519.
 
 config CRYPTO_LIB_CURVE25519
-	tristate "Curve25519 scalar multiplication library"
+	tristate
 	depends on CRYPTO_ARCH_HAVE_LIB_CURVE25519 || !CRYPTO_ARCH_HAVE_LIB_CURVE25519
 	select CRYPTO_LIB_CURVE25519_GENERIC if CRYPTO_ARCH_HAVE_LIB_CURVE25519=n
 	help
@@ -111,7 +100,7 @@ config CRYPTO_LIB_POLY1305_GENERIC
 	  of CRYPTO_LIB_POLY1305.
 
 config CRYPTO_LIB_POLY1305
-	tristate "Poly1305 library interface"
+	tristate
 	depends on CRYPTO_ARCH_HAVE_LIB_POLY1305 || !CRYPTO_ARCH_HAVE_LIB_POLY1305
 	select CRYPTO_LIB_POLY1305_GENERIC if CRYPTO_ARCH_HAVE_LIB_POLY1305=n
 	help
@@ -120,7 +109,7 @@ config CRYPTO_LIB_POLY1305
 	  is available and enabled.
 
 config CRYPTO_LIB_CHACHA20POLY1305
-	tristate "ChaCha20-Poly1305 AEAD support (8-byte nonce library version)"
+	tristate
 	depends on CRYPTO_ARCH_HAVE_LIB_CHACHA || !CRYPTO_ARCH_HAVE_LIB_CHACHA
 	depends on CRYPTO_ARCH_HAVE_LIB_POLY1305 || !CRYPTO_ARCH_HAVE_LIB_POLY1305
 	select CRYPTO_LIB_CHACHA
diff --git a/lib/crypto/Makefile b/lib/crypto/Makefile
index 73205ed269ba..ed43a41f2dcc 100644
--- a/lib/crypto/Makefile
+++ b/lib/crypto/Makefile
@@ -10,11 +10,10 @@ libaes-y					:= aes.o
 obj-$(CONFIG_CRYPTO_LIB_ARC4)			+= libarc4.o
 libarc4-y					:= arc4.o
 
-obj-$(CONFIG_CRYPTO_LIB_BLAKE2S_GENERIC)	+= libblake2s-generic.o
-libblake2s-generic-y				+= blake2s-generic.o
-
-obj-$(CONFIG_CRYPTO_LIB_BLAKE2S)		+= libblake2s.o
-libblake2s-y					+= blake2s.o
+# blake2s is used by the /dev/random driver which is always builtin
+obj-y						+= libblake2s.o
+libblake2s-y					:= blake2s.o
+libblake2s-$(CONFIG_CRYPTO_LIB_BLAKE2S_GENERIC)	+= blake2s-generic.o
 
 obj-$(CONFIG_CRYPTO_LIB_CHACHA20POLY1305)	+= libchacha20poly1305.o
 libchacha20poly1305-y				+= chacha20poly1305.o
diff --git a/lib/crypto/blake2s-generic.c b/lib/crypto/blake2s-generic.c
index 04ff8df24513..75ccb3e633e6 100644
--- a/lib/crypto/blake2s-generic.c
+++ b/lib/crypto/blake2s-generic.c
@@ -37,7 +37,11 @@ static inline void blake2s_increment_counter(struct blake2s_state *state,
 	state->t[1] += (state->t[0] < inc);
 }
 
-void blake2s_compress_generic(struct blake2s_state *state,const u8 *block,
+void blake2s_compress(struct blake2s_state *state, const u8 *block,
+		      size_t nblocks, const u32 inc)
+		      __weak __alias(blake2s_compress_generic);
+
+void blake2s_compress_generic(struct blake2s_state *state, const u8 *block,
 			      size_t nblocks, const u32 inc)
 {
 	u32 m[16];
diff --git a/lib/crypto/blake2s.c b/lib/crypto/blake2s.c
index 4055aa593ec4..93f2ae051370 100644
--- a/lib/crypto/blake2s.c
+++ b/lib/crypto/blake2s.c
@@ -16,12 +16,6 @@
 #include <linux/init.h>
 #include <linux/bug.h>
 
-#if IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_BLAKE2S)
-#  define blake2s_compress blake2s_compress_arch
-#else
-#  define blake2s_compress blake2s_compress_generic
-#endif
-
 void blake2s_update(struct blake2s_state *state, const u8 *in, size_t inlen)
 {
 	__blake2s_update(state, in, inlen, blake2s_compress);