[PATCH v4] lib/crypto: blake2s: include as built-in

["Jason A. Donenfeld" <Jason@zx2c4.com>]

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.

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: Herbert Xu <herbert@gondor.apana.org.au>
Cc: linux-crypto@vger.kernel.org
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
Herbert - As mentioned with the vPrev, I intend to take this via the
crng/random.git tree, since it forms a dependency and I'd like to send a
pull early in 5.17 cycle.

Changes v3->v4:
- Keep the generic one for the generic shash implementation.
Changes v2->v3:
- Rather than using lib-y, use obj-y, and retain the kconfig symbols
  for selection.

 arch/arm/crypto/blake2s-core.S    |  8 ++++----
 arch/arm/crypto/blake2s-glue.c    |  6 +++---
 arch/x86/crypto/blake2s-glue.c    | 11 +++++------
 drivers/net/Kconfig               |  1 -
 include/crypto/internal/blake2s.h |  6 +++---
 lib/crypto/Kconfig                | 13 ++-----------
 lib/crypto/Makefile               |  9 ++++-----
 lib/crypto/blake2s-generic.c      |  6 +++++-
 lib/crypto/blake2s.c              |  6 ------
 9 files changed, 26 insertions(+), 40 deletions(-)

diff --git a/arch/arm/crypto/blake2s-core.S b/arch/arm/crypto/blake2s-core.S
index 86345751bbf3..df40e46601f1 100644
--- a/arch/arm/crypto/blake2s-core.S
+++ b/arch/arm/crypto/blake2s-core.S
@@ -167,8 +167,8 @@
 .endm
 
 //
-// void blake2s_compress_arch(struct blake2s_state *state,
-//			      const u8 *block, size_t nblocks, u32 inc);
+// void blake2s_compress(struct blake2s_state *state,
+//			 const u8 *block, size_t nblocks, u32 inc);
 //
 // Only the first three fields of struct blake2s_state are used:
 //	u32 h[8];	(inout)
@@ -176,7 +176,7 @@
 //	u32 f[2];	(in)
 //
 	.align		5
-ENTRY(blake2s_compress_arch)
+ENTRY(blake2s_compress)
 	push		{r0-r2,r4-r11,lr}	// keep this an even number
 
 .Lnext_block:
@@ -303,4 +303,4 @@ ENTRY(blake2s_compress_arch)
 	str		r3, [r12], #4
 	bne		1b
 	b		.Lcopy_block_done
-ENDPROC(blake2s_compress_arch)
+ENDPROC(blake2s_compress)
diff --git a/arch/arm/crypto/blake2s-glue.c b/arch/arm/crypto/blake2s-glue.c
index f2cc1e5fc9ec..09d3a0cabd2c 100644
--- a/arch/arm/crypto/blake2s-glue.c
+++ b/arch/arm/crypto/blake2s-glue.c
@@ -11,17 +11,17 @@
 #include <linux/module.h>
 
 /* defined in blake2s-core.S */
-EXPORT_SYMBOL(blake2s_compress_arch);
+EXPORT_SYMBOL(blake2s_compress);
 
 static int crypto_blake2s_update_arm(struct shash_desc *desc,
 				     const u8 *in, unsigned int inlen)
 {
-	return crypto_blake2s_update(desc, in, inlen, blake2s_compress_arch);
+	return crypto_blake2s_update(desc, in, inlen, blake2s_compress);
 }
 
 static int crypto_blake2s_final_arm(struct shash_desc *desc, u8 *out)
 {
-	return crypto_blake2s_final(desc, out, blake2s_compress_arch);
+	return crypto_blake2s_final(desc, out, blake2s_compress);
 }
 
 #define BLAKE2S_ALG(name, driver_name, digest_size)			\
diff --git a/arch/x86/crypto/blake2s-glue.c b/arch/x86/crypto/blake2s-glue.c
index a40365ab301e..ef91a3167d27 100644
--- a/arch/x86/crypto/blake2s-glue.c
+++ b/arch/x86/crypto/blake2s-glue.c
@@ -28,9 +28,8 @@ asmlinkage void blake2s_compress_avx512(struct blake2s_state *state,
 static __ro_after_init DEFINE_STATIC_KEY_FALSE(blake2s_use_ssse3);
 static __ro_after_init DEFINE_STATIC_KEY_FALSE(blake2s_use_avx512);
 
-void blake2s_compress_arch(struct blake2s_state *state,
-			   const u8 *block, size_t nblocks,
-			   const u32 inc)
+void blake2s_compress(struct blake2s_state *state, const u8 *block,
+		      size_t nblocks, const u32 inc)
 {
 	/* SIMD disables preemption, so relax after processing each page. */
 	BUILD_BUG_ON(SZ_4K / BLAKE2S_BLOCK_SIZE < 8);
@@ -56,17 +55,17 @@ void blake2s_compress_arch(struct blake2s_state *state,
 		block += blocks * BLAKE2S_BLOCK_SIZE;
 	} while (nblocks);
 }
-EXPORT_SYMBOL(blake2s_compress_arch);
+EXPORT_SYMBOL(blake2s_compress);
 
 static int crypto_blake2s_update_x86(struct shash_desc *desc,
 				     const u8 *in, unsigned int inlen)
 {
-	return crypto_blake2s_update(desc, in, inlen, blake2s_compress_arch);
+	return crypto_blake2s_update(desc, in, inlen, blake2s_compress);
 }
 
 static int crypto_blake2s_final_x86(struct shash_desc *desc, u8 *out)
 {
-	return crypto_blake2s_final(desc, out, blake2s_compress_arch);
+	return crypto_blake2s_final(desc, out, blake2s_compress);
 }
 
 #define BLAKE2S_ALG(name, driver_name, digest_size)			\
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 6cccc3dc00bc..b2a4f998c180 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -81,7 +81,6 @@ config WIREGUARD
 	select CRYPTO
 	select CRYPTO_LIB_CURVE25519
 	select CRYPTO_LIB_CHACHA20POLY1305
-	select CRYPTO_LIB_BLAKE2S
 	select CRYPTO_CHACHA20_X86_64 if X86 && 64BIT
 	select CRYPTO_POLY1305_X86_64 if X86 && 64BIT
 	select CRYPTO_BLAKE2S_X86 if X86 && 64BIT
diff --git a/include/crypto/internal/blake2s.h b/include/crypto/internal/blake2s.h
index 8e50d487500f..d39cfa0d333e 100644
--- a/include/crypto/internal/blake2s.h
+++ b/include/crypto/internal/blake2s.h
@@ -11,11 +11,11 @@
 #include <crypto/internal/hash.h>
 #include <linux/string.h>
 
-void blake2s_compress_generic(struct blake2s_state *state,const u8 *block,
+void blake2s_compress_generic(struct blake2s_state *state, const u8 *block,
 			      size_t nblocks, const u32 inc);
 
-void blake2s_compress_arch(struct blake2s_state *state,const u8 *block,
-			   size_t nblocks, const u32 inc);
+void blake2s_compress(struct blake2s_state *state, const u8 *block,
+		      size_t nblocks, const u32 inc);
 
 bool blake2s_selftest(void);
 
diff --git a/lib/crypto/Kconfig b/lib/crypto/Kconfig
index 545ccbddf6a1..0f27976b5038 100644
--- a/lib/crypto/Kconfig
+++ b/lib/crypto/Kconfig
@@ -9,14 +9,14 @@ 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 +24,6 @@ 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
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);
-- 
2.34.1