crypto: poly1305 - add new 32 and 64-bit generic versions

These two C implementations from Zinc -- a 32x32 one and a 64x64 one,
depending on the platform -- come from Andrew Moon's public domain
poly1305-donna portable code, modified for usage in the kernel. The
precomputation in the 32-bit version and the use of 64x64 multiplies in
the 64-bit version make these perform better than the code it replaces.
Moon's code is also very widespread and has received many eyeballs of
scrutiny.

There's a bit of interference between the x86 implementation, which
relies on internal details of the old scalar implementation. In the next
commit, the x86 implementation will be replaced with a faster one that
doesn't rely on this, so none of this matters much. But for now, to keep
this passing the tests, we inline the bits of the old implementation
that the x86 implementation relied on. Also, since we now support a
slightly larger key space, via the union, some offsets had to be fixed
up.

Nonce calculation was folded in with the emit function, to take
advantage of 64x64 arithmetic. However, Adiantum appeared to rely on no
nonce handling in emit, so this path was conditionalized. We also
introduced a new struct, poly1305_core_key, to represent the precise
amount of space that particular implementation uses.

Testing with kbench9000, depending on the CPU, the update function for
the 32x32 version has been improved by 4%-7%, and for the 64x64 by
19%-30%. The 32x32 gains are small, but I think there's great value in
having a parallel implementation to the 64x64 one so that the two can be
compared side-by-side as nice stand-alone units.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 7 insertions, 162 deletions

diff --git a/lib/crypto/poly1305.c b/lib/crypto/poly1305.c
index 32ec293c65ae..9d2d14df0fee 100644
--- a/lib/crypto/poly1305.c
+++ b/lib/crypto/poly1305.c
@@ -12,151 +12,9 @@
 #include <linux/module.h>
 #include <asm/unaligned.h>
 
-static inline u64 mlt(u64 a, u64 b)
-{
-	return a * b;
-}
-
-static inline u32 sr(u64 v, u_char n)
-{
-	return v >> n;
-}
-
-static inline u32 and(u32 v, u32 mask)
-{
-	return v & mask;
-}
-
-void poly1305_core_setkey(struct poly1305_key *key, const u8 *raw_key)
-{
-	/* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
-	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);
-
-void poly1305_core_blocks(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;
-
-	if (!nblocks)
-		return;
-
-	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 = 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;
-		h2 += (get_unaligned_le32(src +  6) >> 4) & 0x3ffffff;
-		h3 += (get_unaligned_le32(src +  9) >> 6) & 0x3ffffff;
-		h4 += (get_unaligned_le32(src + 12) >> 8) | (hibit << 24);
-
-		/* h *= r */
-		d0 = mlt(h0, r0) + mlt(h1, s4) + mlt(h2, s3) +
-		     mlt(h3, s2) + mlt(h4, s1);
-		d1 = mlt(h0, r1) + mlt(h1, r0) + mlt(h2, s4) +
-		     mlt(h3, s3) + mlt(h4, s2);
-		d2 = mlt(h0, r2) + mlt(h1, r1) + mlt(h2, r0) +
-		     mlt(h3, s4) + mlt(h4, s3);
-		d3 = mlt(h0, r3) + mlt(h1, r2) + mlt(h2, r1) +
-		     mlt(h3, r0) + mlt(h4, s4);
-		d4 = mlt(h0, r4) + mlt(h1, r3) + mlt(h2, r2) +
-		     mlt(h3, r1) + mlt(h4, r0);
-
-		/* (partial) h %= p */
-		d1 += sr(d0, 26);     h0 = and(d0, 0x3ffffff);
-		d2 += sr(d1, 26);     h1 = and(d1, 0x3ffffff);
-		d3 += sr(d2, 26);     h2 = and(d2, 0x3ffffff);
-		d4 += sr(d3, 26);     h3 = and(d3, 0x3ffffff);
-		h0 += sr(d4, 26) * 5; h4 = and(d4, 0x3ffffff);
-		h1 += h0 >> 26;       h0 = h0 & 0x3ffffff;
-
-		src += POLY1305_BLOCK_SIZE;
-	} while (--nblocks);
-
-	state->h[0] = h0;
-	state->h[1] = h1;
-	state->h[2] = h2;
-	state->h[3] = h3;
-	state->h[4] = h4;
-}
-EXPORT_SYMBOL_GPL(poly1305_core_blocks);
-
-void poly1305_core_emit(const struct poly1305_state *state, void *dst)
-{
-	u32 h0, h1, h2, h3, h4;
-	u32 g0, g1, g2, g3, g4;
-	u32 mask;
-
-	/* fully carry h */
-	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;
-	h4 += (h3 >> 26);     h3 = h3 & 0x3ffffff;
-	h0 += (h4 >> 26) * 5; h4 = h4 & 0x3ffffff;
-	h1 += (h0 >> 26);     h0 = h0 & 0x3ffffff;
-
-	/* compute h + -p */
-	g0 = h0 + 5;
-	g1 = h1 + (g0 >> 26);             g0 &= 0x3ffffff;
-	g2 = h2 + (g1 >> 26);             g1 &= 0x3ffffff;
-	g3 = h3 + (g2 >> 26);             g2 &= 0x3ffffff;
-	g4 = h4 + (g3 >> 26) - (1 << 26); g3 &= 0x3ffffff;
-
-	/* select h if h < p, or h + -p if h >= p */
-	mask = (g4 >> ((sizeof(u32) * 8) - 1)) - 1;
-	g0 &= mask;
-	g1 &= mask;
-	g2 &= mask;
-	g3 &= mask;
-	g4 &= mask;
-	mask = ~mask;
-	h0 = (h0 & mask) | g0;
-	h1 = (h1 & mask) | g1;
-	h2 = (h2 & mask) | g2;
-	h3 = (h3 & mask) | g3;
-	h4 = (h4 & mask) | g4;
-
-	/* h = h % (2^128) */
-	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);
-
 void poly1305_init_generic(struct poly1305_desc_ctx *desc, const u8 *key)
 {
-	poly1305_core_setkey(desc->r, key);
+	poly1305_core_setkey(&desc->core_r, key);
 	desc->s[0] = get_unaligned_le32(key + 16);
 	desc->s[1] = get_unaligned_le32(key + 20);
 	desc->s[2] = get_unaligned_le32(key + 24);
@@ -164,7 +22,7 @@ void poly1305_init_generic(struct poly1305_desc_ctx *desc, const u8 *key)
 	poly1305_core_init(&desc->h);
 	desc->buflen = 0;
 	desc->sset = true;
-	desc->rset = 1;
+	desc->rset = 2;
 }
 EXPORT_SYMBOL_GPL(poly1305_init_generic);
 
@@ -181,13 +39,14 @@ void poly1305_update_generic(struct poly1305_desc_ctx *desc, const u8 *src,
 		desc->buflen += bytes;
 
 		if (desc->buflen == POLY1305_BLOCK_SIZE) {
-			poly1305_core_blocks(&desc->h, desc->r, desc->buf, 1, 1);
+			poly1305_core_blocks(&desc->h, &desc->core_r, desc->buf,
+					     1, 1);
 			desc->buflen = 0;
 		}
 	}
 
 	if (likely(nbytes >= POLY1305_BLOCK_SIZE)) {
-		poly1305_core_blocks(&desc->h, desc->r, src,
+		poly1305_core_blocks(&desc->h, &desc->core_r, src,
 				     nbytes / POLY1305_BLOCK_SIZE, 1);
 		src += nbytes - (nbytes % POLY1305_BLOCK_SIZE);
 		nbytes %= POLY1305_BLOCK_SIZE;
@@ -202,28 +61,14 @@ EXPORT_SYMBOL_GPL(poly1305_update_generic);
 
 void poly1305_final_generic(struct poly1305_desc_ctx *desc, u8 *dst)
 {
-	__le32 digest[4];
-	u64 f = 0;
-
 	if (unlikely(desc->buflen)) {
 		desc->buf[desc->buflen++] = 1;
 		memset(desc->buf + desc->buflen, 0,
 		       POLY1305_BLOCK_SIZE - desc->buflen);
-		poly1305_core_blocks(&desc->h, desc->r, desc->buf, 1, 0);
+		poly1305_core_blocks(&desc->h, &desc->core_r, desc->buf, 1, 0);
 	}
 
-	poly1305_core_emit(&desc->h, digest);
-
-	/* mac = (h + s) % (2^128) */
-	f = (f >> 32) + le32_to_cpu(digest[0]) + desc->s[0];
-	put_unaligned_le32(f, dst + 0);
-	f = (f >> 32) + le32_to_cpu(digest[1]) + desc->s[1];
-	put_unaligned_le32(f, dst + 4);
-	f = (f >> 32) + le32_to_cpu(digest[2]) + desc->s[2];
-	put_unaligned_le32(f, dst + 8);
-	f = (f >> 32) + le32_to_cpu(digest[3]) + desc->s[3];
-	put_unaligned_le32(f, dst + 12);
-
+	poly1305_core_emit(&desc->h, desc->s, dst);
 	*desc = (struct poly1305_desc_ctx){};
 }
 EXPORT_SYMBOL_GPL(poly1305_final_generic);