[RFC PATCH 06/20] crypto: x86/poly1305 - expose existing driver as poly1305 library

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

Implement the init/update/final Poly1305 library routines in the
accelerated SIMD driver for x86 so they are accessible to users of
the Poly1305 library interface.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 arch/x86/crypto/poly1305_glue.c | 60 +++++++++++++++-----
 crypto/Kconfig                  |  2 +
 2 files changed, 48 insertions(+), 14 deletions(-)

diff --git a/arch/x86/crypto/poly1305_glue.c b/arch/x86/crypto/poly1305_glue.c
index b43b93c95e79..d3cc92996f58 100644
--- a/arch/x86/crypto/poly1305_glue.c
+++ b/arch/x86/crypto/poly1305_glue.c
@@ -85,18 +85,11 @@ static unsigned int poly1305_simd_blocks(struct poly1305_desc_ctx *dctx,
 	return srclen;
 }
 
-static int poly1305_simd_update(struct shash_desc *desc,
-				const u8 *src, unsigned int srclen)
+static int poly1305_simd_do_update(struct poly1305_desc_ctx *dctx,
+				   const u8 *src, unsigned int srclen)
 {
-	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
 	unsigned int bytes;
 
-	/* kernel_fpu_begin/end is costly, use fallback for small updates */
-	if (srclen <= 288 || !crypto_simd_usable())
-		return crypto_poly1305_update(desc, src, srclen);
-
-	kernel_fpu_begin();
-
 	if (unlikely(dctx->buflen)) {
 		bytes = min(srclen, POLY1305_BLOCK_SIZE - dctx->buflen);
 		memcpy(dctx->buf + dctx->buflen, src, bytes);
@@ -117,8 +110,6 @@ static int poly1305_simd_update(struct shash_desc *desc,
 		srclen = bytes;
 	}
 
-	kernel_fpu_end();
-
 	if (unlikely(srclen)) {
 		dctx->buflen = srclen;
 		memcpy(dctx->buf, src, srclen);
@@ -127,6 +118,47 @@ static int poly1305_simd_update(struct shash_desc *desc,
 	return 0;
 }
 
+static int poly1305_simd_update(struct shash_desc *desc,
+				const u8 *src, unsigned int srclen)
+{
+	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
+	int ret;
+
+	/* kernel_fpu_begin/end is costly, use fallback for small updates */
+	if (srclen <= 288 || !crypto_simd_usable())
+		return crypto_poly1305_update(desc, src, srclen);
+
+	kernel_fpu_begin();
+	ret = poly1305_simd_do_update(dctx, src, srclen);
+	kernel_fpu_end();
+
+	return ret;
+}
+
+void poly1305_init(struct poly1305_desc_ctx *desc, const u8 *key)
+{
+	poly1305_init_generic(desc, key);
+}
+EXPORT_SYMBOL(poly1305_init);
+
+void poly1305_update(struct poly1305_desc_ctx *dctx, const u8 *src,
+		     unsigned int nbytes)
+{
+	if (nbytes <= 288 || !crypto_simd_usable())
+		return poly1305_update_generic(dctx, src, nbytes);
+
+	kernel_fpu_begin();
+	poly1305_simd_do_update(dctx, src, nbytes);
+	kernel_fpu_end();
+}
+EXPORT_SYMBOL(poly1305_update);
+
+void poly1305_final(struct poly1305_desc_ctx *desc, u8 *digest)
+{
+	poly1305_final_generic(desc, digest);
+}
+EXPORT_SYMBOL(poly1305_final);
+
 static struct shash_alg alg = {
 	.digestsize	= POLY1305_DIGEST_SIZE,
 	.init		= crypto_poly1305_init,
@@ -151,9 +183,9 @@ static int __init poly1305_simd_mod_init(void)
 			    boot_cpu_has(X86_FEATURE_AVX) &&
 			    boot_cpu_has(X86_FEATURE_AVX2) &&
 			    cpu_has_xfeatures(XFEATURE_MASK_SSE | XFEATURE_MASK_YMM, NULL);
-	alg.descsize = sizeof(struct poly1305_desc_ctx) + 5 * sizeof(u32);
-	if (poly1305_use_avx2)
-		alg.descsize += 10 * sizeof(u32);
+	alg.descsize = sizeof(struct poly1305_desc_ctx);
+	if (!poly1305_use_avx2)
+		alg.descsize -= 10 * sizeof(u32);
 
 	return crypto_register_shash(&alg);
 }
diff --git a/crypto/Kconfig b/crypto/Kconfig
index f40e8dca57d1..6a952a61675b 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -659,6 +659,7 @@ config CRYPTO_ARCH_HAVE_LIB_POLY1305
 
 config CRYPTO_LIB_POLY1305_RSIZE
 	int
+	default 4 if X86_64
 	default 1
 
 config CRYPTO_LIB_POLY1305
@@ -680,6 +681,7 @@ config CRYPTO_POLY1305_X86_64
 	tristate "Poly1305 authenticator algorithm (x86_64/SSE2/AVX2)"
 	depends on X86 && 64BIT
 	select CRYPTO_POLY1305
+	select CRYPTO_ARCH_HAVE_LIB_POLY1305
 	help
 	  Poly1305 authenticator algorithm, RFC7539.
 
-- 
2.17.1