crypto: lib/poly1305 - Build main library on LIB_POLY1305 and split generic code out

Split the lib poly1305 code just as was done with sha256. Make
the main library code conditional on LIB_POLY1305 instead of
LIB_POLY1305_GENERIC.

Reported-by: Giovanni Cabiddu <[e-mail]>
Fixes: 10a6d72ea355 ("crypto: lib/poly1305 - Use block-only interface")
Signed-off-by: Herbert Xu <[e-mail]>

lib/crypto/Makefile

···
 obj-$(CONFIG_CRYPTO_LIB_DES)			+= libdes.o
 libdes-y					:= des.o
 
-obj-$(CONFIG_CRYPTO_LIB_POLY1305_GENERIC)	+= libpoly1305.o
-libpoly1305-y					:= poly1305-donna32.o
-libpoly1305-$(CONFIG_ARCH_SUPPORTS_INT128)	:= poly1305-donna64.o
+obj-$(CONFIG_CRYPTO_LIB_POLY1305)		+= libpoly1305.o
 libpoly1305-y					+= poly1305.o
+
+obj-$(CONFIG_CRYPTO_LIB_POLY1305_GENERIC)	+= libpoly1305-generic.o
+libpoly1305-generic-y				:= poly1305-donna32.o
+libpoly1305-generic-$(CONFIG_ARCH_SUPPORTS_INT128) := poly1305-donna64.o
+libpoly1305-generic-y				+= poly1305-generic.o
 
 obj-$(CONFIG_CRYPTO_LIB_SHA1)			+= libsha1.o
 libsha1-y					:= sha1.o

lib/crypto/poly1305-generic.c

···
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Poly1305 authenticator algorithm, RFC7539
+ *
+ * Copyright (C) 2015 Martin Willi
+ *
+ * Based on public domain code by Andrew Moon and Daniel J. Bernstein.
+ */
+
+#include <crypto/internal/poly1305.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+void poly1305_block_init_generic(struct poly1305_block_state *desc,
+				 const u8 raw_key[POLY1305_BLOCK_SIZE])
+{
+	poly1305_core_init(&desc->h);
+	poly1305_core_setkey(&desc->core_r, raw_key);
+}
+EXPORT_SYMBOL_GPL(poly1305_block_init_generic);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Martin Willi <[e-mail]>");
+MODULE_DESCRIPTION("Poly1305 algorithm (generic implementation)");

lib/crypto/poly1305.c

···
 #include <linux/string.h>
 #include <linux/unaligned.h>
 
-void poly1305_block_init_generic(struct poly1305_block_state *desc,
-				 const u8 raw_key[POLY1305_BLOCK_SIZE])
-{
-	poly1305_core_init(&desc->h);
-	poly1305_core_setkey(&desc->core_r, raw_key);
-}
-EXPORT_SYMBOL_GPL(poly1305_block_init_generic);
-
 void poly1305_init(struct poly1305_desc_ctx *desc,
 		   const u8 key[POLY1305_KEY_SIZE])
 {