diff --git a/arch/x86/crypto/poly1305_glue.c b/arch/x86/crypto/poly1305_glue.c
index f012b7e28ad1d..88cc01506c84a 100644
--- a/arch/x86/crypto/poly1305_glue.c
+++ b/arch/x86/crypto/poly1305_glue.c
@@ -83,35 +83,37 @@ static unsigned int poly1305_simd_blocks(struct poly1305_desc_ctx *dctx,
 	if (poly1305_use_avx2 && srclen >= POLY1305_BLOCK_SIZE * 4) {
 		if (unlikely(!sctx->wset)) {
 			if (!sctx->uset) {
-				memcpy(sctx->u, dctx->r, sizeof(sctx->u));
-				poly1305_simd_mult(sctx->u, dctx->r);
+				memcpy(sctx->u, dctx->r.r, sizeof(sctx->u));
+				poly1305_simd_mult(sctx->u, dctx->r.r);
 				sctx->uset = true;
 			}
 			memcpy(sctx->u + 5, sctx->u, sizeof(sctx->u));
-			poly1305_simd_mult(sctx->u + 5, dctx->r);
+			poly1305_simd_mult(sctx->u + 5, dctx->r.r);
 			memcpy(sctx->u + 10, sctx->u + 5, sizeof(sctx->u));
-			poly1305_simd_mult(sctx->u + 10, dctx->r);
+			poly1305_simd_mult(sctx->u + 10, dctx->r.r);
 			sctx->wset = true;
 		}
 		blocks = srclen / (POLY1305_BLOCK_SIZE * 4);
-		poly1305_4block_avx2(dctx->h, src, dctx->r, blocks, sctx->u);
+		poly1305_4block_avx2(dctx->h.h, src, dctx->r.r, blocks,
+				     sctx->u);
 		src += POLY1305_BLOCK_SIZE * 4 * blocks;
 		srclen -= POLY1305_BLOCK_SIZE * 4 * blocks;
 	}
 #endif
 	if (likely(srclen >= POLY1305_BLOCK_SIZE * 2)) {
 		if (unlikely(!sctx->uset)) {
-			memcpy(sctx->u, dctx->r, sizeof(sctx->u));
-			poly1305_simd_mult(sctx->u, dctx->r);
+			memcpy(sctx->u, dctx->r.r, sizeof(sctx->u));
+			poly1305_simd_mult(sctx->u, dctx->r.r);
 			sctx->uset = true;
 		}
 		blocks = srclen / (POLY1305_BLOCK_SIZE * 2);
-		poly1305_2block_sse2(dctx->h, src, dctx->r, blocks, sctx->u);
+		poly1305_2block_sse2(dctx->h.h, src, dctx->r.r, blocks,
+				     sctx->u);
 		src += POLY1305_BLOCK_SIZE * 2 * blocks;
 		srclen -= POLY1305_BLOCK_SIZE * 2 * blocks;
 	}
 	if (srclen >= POLY1305_BLOCK_SIZE) {
-		poly1305_block_sse2(dctx->h, src, dctx->r, 1);
+		poly1305_block_sse2(dctx->h.h, src, dctx->r.r, 1);
 		srclen -= POLY1305_BLOCK_SIZE;
 	}
 	return srclen;
diff --git a/crypto/poly1305_generic.c b/crypto/poly1305_generic.c
index 47d3a6b83931e..2a06874204e87 100644
--- a/crypto/poly1305_generic.c
+++ b/crypto/poly1305_generic.c
@@ -38,7 +38,7 @@ int crypto_poly1305_init(struct shash_desc *desc)
 {
 	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
 
-	memset(dctx->h, 0, sizeof(dctx->h));
+	poly1305_core_init(&dctx->h);
 	dctx->buflen = 0;
 	dctx->rset = false;
 	dctx->sset = false;
@@ -47,23 +47,16 @@ int crypto_poly1305_init(struct shash_desc *desc)
 }
 EXPORT_SYMBOL_GPL(crypto_poly1305_init);
 
-static void poly1305_setrkey(struct poly1305_desc_ctx *dctx, const u8 *key)
+void poly1305_core_setkey(struct poly1305_key *key, const u8 *raw_key)
 {
 	/* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
-	dctx->r[0] = (get_unaligned_le32(key +  0) >> 0) & 0x3ffffff;
-	dctx->r[1] = (get_unaligned_le32(key +  3) >> 2) & 0x3ffff03;
-	dctx->r[2] = (get_unaligned_le32(key +  6) >> 4) & 0x3ffc0ff;
-	dctx->r[3] = (get_unaligned_le32(key +  9) >> 6) & 0x3f03fff;
-	dctx->r[4] = (get_unaligned_le32(key + 12) >> 8) & 0x00fffff;
-}
-
-static void poly1305_setskey(struct poly1305_desc_ctx *dctx, const u8 *key)
-{
-	dctx->s[0] = get_unaligned_le32(key +  0);
-	dctx->s[1] = get_unaligned_le32(key +  4);
-	dctx->s[2] = get_unaligned_le32(key +  8);
-	dctx->s[3] = get_unaligned_le32(key + 12);
+	key->r[0] = (get_unaligned_le32(raw_key +  0) >> 0) & 0x3ffffff;
+	key->r[1] = (get_unaligned_le32(raw_key +  3) >> 2) & 0x3ffff03;
+	key->r[2] = (get_unaligned_le32(raw_key +  6) >> 4) & 0x3ffc0ff;
+	key->r[3] = (get_unaligned_le32(raw_key +  9) >> 6) & 0x3f03fff;
+	key->r[4] = (get_unaligned_le32(raw_key + 12) >> 8) & 0x00fffff;
 }
+EXPORT_SYMBOL_GPL(poly1305_core_setkey);
 
 /*
  * Poly1305 requires a unique key for each tag, which implies that we can't set
@@ -75,13 +68,16 @@ unsigned int crypto_poly1305_setdesckey(struct poly1305_desc_ctx *dctx,
 {
 	if (!dctx->sset) {
 		if (!dctx->rset && srclen >= POLY1305_BLOCK_SIZE) {
-			poly1305_setrkey(dctx, src);
+			poly1305_core_setkey(&dctx->r, src);
 			src += POLY1305_BLOCK_SIZE;
 			srclen -= POLY1305_BLOCK_SIZE;
 			dctx->rset = true;
 		}
 		if (srclen >= POLY1305_BLOCK_SIZE) {
-			poly1305_setskey(dctx, src);
+			dctx->s[0] = get_unaligned_le32(src +  0);
+			dctx->s[1] = get_unaligned_le32(src +  4);
+			dctx->s[2] = get_unaligned_le32(src +  8);
+			dctx->s[3] = get_unaligned_le32(src + 12);
 			src += POLY1305_BLOCK_SIZE;
 			srclen -= POLY1305_BLOCK_SIZE;
 			dctx->sset = true;
@@ -91,41 +87,37 @@ unsigned int crypto_poly1305_setdesckey(struct poly1305_desc_ctx *dctx,
 }
 EXPORT_SYMBOL_GPL(crypto_poly1305_setdesckey);
 
-static unsigned int poly1305_blocks(struct poly1305_desc_ctx *dctx,
-				    const u8 *src, unsigned int srclen,
-				    u32 hibit)
+static void poly1305_blocks_internal(struct poly1305_state *state,
+				     const struct poly1305_key *key,
+				     const void *src, unsigned int nblocks,
+				     u32 hibit)
 {
 	u32 r0, r1, r2, r3, r4;
 	u32 s1, s2, s3, s4;
 	u32 h0, h1, h2, h3, h4;
 	u64 d0, d1, d2, d3, d4;
-	unsigned int datalen;
 
-	if (unlikely(!dctx->sset)) {
-		datalen = crypto_poly1305_setdesckey(dctx, src, srclen);
-		src += srclen - datalen;
-		srclen = datalen;
-	}
+	if (!nblocks)
+		return;
 
-	r0 = dctx->r[0];
-	r1 = dctx->r[1];
-	r2 = dctx->r[2];
-	r3 = dctx->r[3];
-	r4 = dctx->r[4];
+	r0 = key->r[0];
+	r1 = key->r[1];
+	r2 = key->r[2];
+	r3 = key->r[3];
+	r4 = key->r[4];
 
 	s1 = r1 * 5;
 	s2 = r2 * 5;
 	s3 = r3 * 5;
 	s4 = r4 * 5;
 
-	h0 = dctx->h[0];
-	h1 = dctx->h[1];
-	h2 = dctx->h[2];
-	h3 = dctx->h[3];
-	h4 = dctx->h[4];
-
-	while (likely(srclen >= POLY1305_BLOCK_SIZE)) {
+	h0 = state->h[0];
+	h1 = state->h[1];
+	h2 = state->h[2];
+	h3 = state->h[3];
+	h4 = state->h[4];
 
+	do {
 		/* h += m[i] */
 		h0 += (get_unaligned_le32(src +  0) >> 0) & 0x3ffffff;
 		h1 += (get_unaligned_le32(src +  3) >> 2) & 0x3ffffff;
@@ -154,16 +146,36 @@ static unsigned int poly1305_blocks(struct poly1305_desc_ctx *dctx,
 		h1 += h0 >> 26;       h0 = h0 & 0x3ffffff;
 
 		src += POLY1305_BLOCK_SIZE;
-		srclen -= POLY1305_BLOCK_SIZE;
-	}
+	} while (--nblocks);
 
-	dctx->h[0] = h0;
-	dctx->h[1] = h1;
-	dctx->h[2] = h2;
-	dctx->h[3] = h3;
-	dctx->h[4] = h4;
+	state->h[0] = h0;
+	state->h[1] = h1;
+	state->h[2] = h2;
+	state->h[3] = h3;
+	state->h[4] = h4;
+}
 
-	return srclen;
+void poly1305_core_blocks(struct poly1305_state *state,
+			  const struct poly1305_key *key,
+			  const void *src, unsigned int nblocks)
+{
+	poly1305_blocks_internal(state, key, src, nblocks, 1 << 24);
+}
+EXPORT_SYMBOL_GPL(poly1305_core_blocks);
+
+static void poly1305_blocks(struct poly1305_desc_ctx *dctx,
+			    const u8 *src, unsigned int srclen, u32 hibit)
+{
+	unsigned int datalen;
+
+	if (unlikely(!dctx->sset)) {
+		datalen = crypto_poly1305_setdesckey(dctx, src, srclen);
+		src += srclen - datalen;
+		srclen = datalen;
+	}
+
+	poly1305_blocks_internal(&dctx->h, &dctx->r,
+				 src, srclen / POLY1305_BLOCK_SIZE, hibit);
 }
 
 int crypto_poly1305_update(struct shash_desc *desc,
@@ -187,9 +199,9 @@ int crypto_poly1305_update(struct shash_desc *desc,
 	}
 
 	if (likely(srclen >= POLY1305_BLOCK_SIZE)) {
-		bytes = poly1305_blocks(dctx, src, srclen, 1 << 24);
-		src += srclen - bytes;
-		srclen = bytes;
+		poly1305_blocks(dctx, src, srclen, 1 << 24);
+		src += srclen - (srclen % POLY1305_BLOCK_SIZE);
+		srclen %= POLY1305_BLOCK_SIZE;
 	}
 
 	if (unlikely(srclen)) {
@@ -201,30 +213,18 @@ int crypto_poly1305_update(struct shash_desc *desc,
 }
 EXPORT_SYMBOL_GPL(crypto_poly1305_update);
 
-int crypto_poly1305_final(struct shash_desc *desc, u8 *dst)
+void poly1305_core_emit(const struct poly1305_state *state, void *dst)
 {
-	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
 	u32 h0, h1, h2, h3, h4;
 	u32 g0, g1, g2, g3, g4;
 	u32 mask;
-	u64 f = 0;
-
-	if (unlikely(!dctx->sset))
-		return -ENOKEY;
-
-	if (unlikely(dctx->buflen)) {
-		dctx->buf[dctx->buflen++] = 1;
-		memset(dctx->buf + dctx->buflen, 0,
-		       POLY1305_BLOCK_SIZE - dctx->buflen);
-		poly1305_blocks(dctx, dctx->buf, POLY1305_BLOCK_SIZE, 0);
-	}
 
 	/* fully carry h */
-	h0 = dctx->h[0];
-	h1 = dctx->h[1];
-	h2 = dctx->h[2];
-	h3 = dctx->h[3];
-	h4 = dctx->h[4];
+	h0 = state->h[0];
+	h1 = state->h[1];
+	h2 = state->h[2];
+	h3 = state->h[3];
+	h4 = state->h[4];
 
 	h2 += (h1 >> 26);     h1 = h1 & 0x3ffffff;
 	h3 += (h2 >> 26);     h2 = h2 & 0x3ffffff;
@@ -254,16 +254,40 @@ int crypto_poly1305_final(struct shash_desc *desc, u8 *dst)
 	h4 = (h4 & mask) | g4;
 
 	/* h = h % (2^128) */
-	h0 = (h0 >>  0) | (h1 << 26);
-	h1 = (h1 >>  6) | (h2 << 20);
-	h2 = (h2 >> 12) | (h3 << 14);
-	h3 = (h3 >> 18) | (h4 <<  8);
+	put_unaligned_le32((h0 >>  0) | (h1 << 26), dst +  0);
+	put_unaligned_le32((h1 >>  6) | (h2 << 20), dst +  4);
+	put_unaligned_le32((h2 >> 12) | (h3 << 14), dst +  8);
+	put_unaligned_le32((h3 >> 18) | (h4 <<  8), dst + 12);
+}
+EXPORT_SYMBOL_GPL(poly1305_core_emit);
+
+int crypto_poly1305_final(struct shash_desc *desc, u8 *dst)
+{
+	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
+	__le32 digest[4];
+	u64 f = 0;
+
+	if (unlikely(!dctx->sset))
+		return -ENOKEY;
+
+	if (unlikely(dctx->buflen)) {
+		dctx->buf[dctx->buflen++] = 1;
+		memset(dctx->buf + dctx->buflen, 0,
+		       POLY1305_BLOCK_SIZE - dctx->buflen);
+		poly1305_blocks(dctx, dctx->buf, POLY1305_BLOCK_SIZE, 0);
+	}
+
+	poly1305_core_emit(&dctx->h, digest);
 
 	/* mac = (h + s) % (2^128) */
-	f = (f >> 32) + h0 + dctx->s[0]; put_unaligned_le32(f, dst +  0);
-	f = (f >> 32) + h1 + dctx->s[1]; put_unaligned_le32(f, dst +  4);
-	f = (f >> 32) + h2 + dctx->s[2]; put_unaligned_le32(f, dst +  8);
-	f = (f >> 32) + h3 + dctx->s[3]; put_unaligned_le32(f, dst + 12);
+	f = (f >> 32) + le32_to_cpu(digest[0]) + dctx->s[0];
+	put_unaligned_le32(f, dst + 0);
+	f = (f >> 32) + le32_to_cpu(digest[1]) + dctx->s[1];
+	put_unaligned_le32(f, dst + 4);
+	f = (f >> 32) + le32_to_cpu(digest[2]) + dctx->s[2];
+	put_unaligned_le32(f, dst + 8);
+	f = (f >> 32) + le32_to_cpu(digest[3]) + dctx->s[3];
+	put_unaligned_le32(f, dst + 12);
 
 	return 0;
 }
diff --git a/include/crypto/poly1305.h b/include/crypto/poly1305.h
index f718a19da82f7..34317ed2071e6 100644
--- a/include/crypto/poly1305.h
+++ b/include/crypto/poly1305.h
@@ -13,13 +13,21 @@
 #define POLY1305_KEY_SIZE	32
 #define POLY1305_DIGEST_SIZE	16
 
+struct poly1305_key {
+	u32 r[5];	/* key, base 2^26 */
+};
+
+struct poly1305_state {
+	u32 h[5];	/* accumulator, base 2^26 */
+};
+
 struct poly1305_desc_ctx {
 	/* key */
-	u32 r[5];
+	struct poly1305_key r;
 	/* finalize key */
 	u32 s[4];
 	/* accumulator */
-	u32 h[5];
+	struct poly1305_state h;
 	/* partial buffer */
 	u8 buf[POLY1305_BLOCK_SIZE];
 	/* bytes used in partial buffer */
@@ -30,6 +38,22 @@ struct poly1305_desc_ctx {
 	bool sset;
 };
 
+/*
+ * Poly1305 core functions.  These implement the ε-almost-∆-universal hash
+ * function underlying the Poly1305 MAC, i.e. they don't add an encrypted nonce
+ * ("s key") at the end.  They also only support block-aligned inputs.
+ */
+void poly1305_core_setkey(struct poly1305_key *key, const u8 *raw_key);
+static inline void poly1305_core_init(struct poly1305_state *state)
+{
+	memset(state->h, 0, sizeof(state->h));
+}
+void poly1305_core_blocks(struct poly1305_state *state,
+			  const struct poly1305_key *key,
+			  const void *src, unsigned int nblocks);
+void poly1305_core_emit(const struct poly1305_state *state, void *dst);
+
+/* Crypto API helper functions for the Poly1305 MAC */
 int crypto_poly1305_init(struct shash_desc *desc);
 unsigned int crypto_poly1305_setdesckey(struct poly1305_desc_ctx *dctx,
 					const u8 *src, unsigned int srclen);
