crypto: lib/sha256 - Unroll SHA256 loop 8 times intead of 64

This reduces code size substantially (on x86_64 with gcc-10 the size of
sha256_update() goes from 7593 bytes to 1952 bytes including the new
SHA256_K array), and on x86 is slightly faster than the full unroll
(tested on Broadwell Xeon).

Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 38 insertions, 136 deletions

diff --git a/lib/crypto/sha256.c b/lib/crypto/sha256.c
index c6bfeacc5b81..e2e29d9b0ccd 100644
--- a/lib/crypto/sha256.c
+++ b/lib/crypto/sha256.c
@@ -18,6 +18,25 @@
 #include <crypto/sha.h>
 #include <asm/unaligned.h>
 
+static const u32 SHA256_K[] = {
+	0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
+	0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
+	0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
+	0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
+	0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
+	0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
+	0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
+	0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
+	0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
+	0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
+	0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
+	0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
+	0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
+	0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
+	0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
+	0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2,
+};
+
 static inline u32 Ch(u32 x, u32 y, u32 z)
 {
 	return z ^ (x & (y ^ z));
@@ -43,9 +62,17 @@ static inline void BLEND_OP(int I, u32 *W)
 	W[I] = s1(W[I-2]) + W[I-7] + s0(W[I-15]) + W[I-16];
 }
 
+#define SHA256_ROUND(i, a, b, c, d, e, f, g, h) do {		\
+	u32 t1, t2;						\
+	t1 = h + e1(e) + Ch(e, f, g) + SHA256_K[i] + W[i];	\
+	t2 = e0(a) + Maj(a, b, c);				\
+	d += t1;						\
+	h = t1 + t2;						\
+} while (0)
+
 static void sha256_transform(u32 *state, const u8 *input, u32 *W)
 {
-	u32 a, b, c, d, e, f, g, h, t1, t2;
+	u32 a, b, c, d, e, f, g, h;
 	int i;
 
 	/* load the input */
@@ -61,141 +88,16 @@ static void sha256_transform(u32 *state, const u8 *input, u32 *W)
 	e = state[4];  f = state[5];  g = state[6];  h = state[7];
 
 	/* now iterate */
-	t1 = h + e1(e) + Ch(e, f, g) + 0x428a2f98 + W[0];
-	t2 = e0(a) + Maj(a, b, c);    d += t1;    h = t1 + t2;
-	t1 = g + e1(d) + Ch(d, e, f) + 0x71374491 + W[1];
-	t2 = e0(h) + Maj(h, a, b);    c += t1;    g = t1 + t2;
-	t1 = f + e1(c) + Ch(c, d, e) + 0xb5c0fbcf + W[2];
-	t2 = e0(g) + Maj(g, h, a);    b += t1;    f = t1 + t2;
-	t1 = e + e1(b) + Ch(b, c, d) + 0xe9b5dba5 + W[3];
-	t2 = e0(f) + Maj(f, g, h);    a += t1;    e = t1 + t2;
-	t1 = d + e1(a) + Ch(a, b, c) + 0x3956c25b + W[4];
-	t2 = e0(e) + Maj(e, f, g);    h += t1;    d = t1 + t2;
-	t1 = c + e1(h) + Ch(h, a, b) + 0x59f111f1 + W[5];
-	t2 = e0(d) + Maj(d, e, f);    g += t1;    c = t1 + t2;
-	t1 = b + e1(g) + Ch(g, h, a) + 0x923f82a4 + W[6];
-	t2 = e0(c) + Maj(c, d, e);    f += t1;    b = t1 + t2;
-	t1 = a + e1(f) + Ch(f, g, h) + 0xab1c5ed5 + W[7];
-	t2 = e0(b) + Maj(b, c, d);    e += t1;    a = t1 + t2;
-
-	t1 = h + e1(e) + Ch(e, f, g) + 0xd807aa98 + W[8];
-	t2 = e0(a) + Maj(a, b, c);    d += t1;    h = t1 + t2;
-	t1 = g + e1(d) + Ch(d, e, f) + 0x12835b01 + W[9];
-	t2 = e0(h) + Maj(h, a, b);    c += t1;    g = t1 + t2;
-	t1 = f + e1(c) + Ch(c, d, e) + 0x243185be + W[10];
-	t2 = e0(g) + Maj(g, h, a);    b += t1;    f = t1 + t2;
-	t1 = e + e1(b) + Ch(b, c, d) + 0x550c7dc3 + W[11];
-	t2 = e0(f) + Maj(f, g, h);    a += t1;    e = t1 + t2;
-	t1 = d + e1(a) + Ch(a, b, c) + 0x72be5d74 + W[12];
-	t2 = e0(e) + Maj(e, f, g);    h += t1;    d = t1 + t2;
-	t1 = c + e1(h) + Ch(h, a, b) + 0x80deb1fe + W[13];
-	t2 = e0(d) + Maj(d, e, f);    g += t1;    c = t1 + t2;
-	t1 = b + e1(g) + Ch(g, h, a) + 0x9bdc06a7 + W[14];
-	t2 = e0(c) + Maj(c, d, e);    f += t1;    b = t1 + t2;
-	t1 = a + e1(f) + Ch(f, g, h) + 0xc19bf174 + W[15];
-	t2 = e0(b) + Maj(b, c, d);    e += t1;    a = t1 + t2;
-
-	t1 = h + e1(e) + Ch(e, f, g) + 0xe49b69c1 + W[16];
-	t2 = e0(a) + Maj(a, b, c);    d += t1;    h = t1 + t2;
-	t1 = g + e1(d) + Ch(d, e, f) + 0xefbe4786 + W[17];
-	t2 = e0(h) + Maj(h, a, b);    c += t1;    g = t1 + t2;
-	t1 = f + e1(c) + Ch(c, d, e) + 0x0fc19dc6 + W[18];
-	t2 = e0(g) + Maj(g, h, a);    b += t1;    f = t1 + t2;
-	t1 = e + e1(b) + Ch(b, c, d) + 0x240ca1cc + W[19];
-	t2 = e0(f) + Maj(f, g, h);    a += t1;    e = t1 + t2;
-	t1 = d + e1(a) + Ch(a, b, c) + 0x2de92c6f + W[20];
-	t2 = e0(e) + Maj(e, f, g);    h += t1;    d = t1 + t2;
-	t1 = c + e1(h) + Ch(h, a, b) + 0x4a7484aa + W[21];
-	t2 = e0(d) + Maj(d, e, f);    g += t1;    c = t1 + t2;
-	t1 = b + e1(g) + Ch(g, h, a) + 0x5cb0a9dc + W[22];
-	t2 = e0(c) + Maj(c, d, e);    f += t1;    b = t1 + t2;
-	t1 = a + e1(f) + Ch(f, g, h) + 0x76f988da + W[23];
-	t2 = e0(b) + Maj(b, c, d);    e += t1;    a = t1 + t2;
-
-	t1 = h + e1(e) + Ch(e, f, g) + 0x983e5152 + W[24];
-	t2 = e0(a) + Maj(a, b, c);    d += t1;    h = t1 + t2;
-	t1 = g + e1(d) + Ch(d, e, f) + 0xa831c66d + W[25];
-	t2 = e0(h) + Maj(h, a, b);    c += t1;    g = t1 + t2;
-	t1 = f + e1(c) + Ch(c, d, e) + 0xb00327c8 + W[26];
-	t2 = e0(g) + Maj(g, h, a);    b += t1;    f = t1 + t2;
-	t1 = e + e1(b) + Ch(b, c, d) + 0xbf597fc7 + W[27];
-	t2 = e0(f) + Maj(f, g, h);    a += t1;    e = t1 + t2;
-	t1 = d + e1(a) + Ch(a, b, c) + 0xc6e00bf3 + W[28];
-	t2 = e0(e) + Maj(e, f, g);    h += t1;    d = t1 + t2;
-	t1 = c + e1(h) + Ch(h, a, b) + 0xd5a79147 + W[29];
-	t2 = e0(d) + Maj(d, e, f);    g += t1;    c = t1 + t2;
-	t1 = b + e1(g) + Ch(g, h, a) + 0x06ca6351 + W[30];
-	t2 = e0(c) + Maj(c, d, e);    f += t1;    b = t1 + t2;
-	t1 = a + e1(f) + Ch(f, g, h) + 0x14292967 + W[31];
-	t2 = e0(b) + Maj(b, c, d);    e += t1;    a = t1 + t2;
-
-	t1 = h + e1(e) + Ch(e, f, g) + 0x27b70a85 + W[32];
-	t2 = e0(a) + Maj(a, b, c);    d += t1;    h = t1 + t2;
-	t1 = g + e1(d) + Ch(d, e, f) + 0x2e1b2138 + W[33];
-	t2 = e0(h) + Maj(h, a, b);    c += t1;    g = t1 + t2;
-	t1 = f + e1(c) + Ch(c, d, e) + 0x4d2c6dfc + W[34];
-	t2 = e0(g) + Maj(g, h, a);    b += t1;    f = t1 + t2;
-	t1 = e + e1(b) + Ch(b, c, d) + 0x53380d13 + W[35];
-	t2 = e0(f) + Maj(f, g, h);    a += t1;    e = t1 + t2;
-	t1 = d + e1(a) + Ch(a, b, c) + 0x650a7354 + W[36];
-	t2 = e0(e) + Maj(e, f, g);    h += t1;    d = t1 + t2;
-	t1 = c + e1(h) + Ch(h, a, b) + 0x766a0abb + W[37];
-	t2 = e0(d) + Maj(d, e, f);    g += t1;    c = t1 + t2;
-	t1 = b + e1(g) + Ch(g, h, a) + 0x81c2c92e + W[38];
-	t2 = e0(c) + Maj(c, d, e);    f += t1;    b = t1 + t2;
-	t1 = a + e1(f) + Ch(f, g, h) + 0x92722c85 + W[39];
-	t2 = e0(b) + Maj(b, c, d);    e += t1;    a = t1 + t2;
-
-	t1 = h + e1(e) + Ch(e, f, g) + 0xa2bfe8a1 + W[40];
-	t2 = e0(a) + Maj(a, b, c);    d += t1;    h = t1 + t2;
-	t1 = g + e1(d) + Ch(d, e, f) + 0xa81a664b + W[41];
-	t2 = e0(h) + Maj(h, a, b);    c += t1;    g = t1 + t2;
-	t1 = f + e1(c) + Ch(c, d, e) + 0xc24b8b70 + W[42];
-	t2 = e0(g) + Maj(g, h, a);    b += t1;    f = t1 + t2;
-	t1 = e + e1(b) + Ch(b, c, d) + 0xc76c51a3 + W[43];
-	t2 = e0(f) + Maj(f, g, h);    a += t1;    e = t1 + t2;
-	t1 = d + e1(a) + Ch(a, b, c) + 0xd192e819 + W[44];
-	t2 = e0(e) + Maj(e, f, g);    h += t1;    d = t1 + t2;
-	t1 = c + e1(h) + Ch(h, a, b) + 0xd6990624 + W[45];
-	t2 = e0(d) + Maj(d, e, f);    g += t1;    c = t1 + t2;
-	t1 = b + e1(g) + Ch(g, h, a) + 0xf40e3585 + W[46];
-	t2 = e0(c) + Maj(c, d, e);    f += t1;    b = t1 + t2;
-	t1 = a + e1(f) + Ch(f, g, h) + 0x106aa070 + W[47];
-	t2 = e0(b) + Maj(b, c, d);    e += t1;    a = t1 + t2;
-
-	t1 = h + e1(e) + Ch(e, f, g) + 0x19a4c116 + W[48];
-	t2 = e0(a) + Maj(a, b, c);    d += t1;    h = t1 + t2;
-	t1 = g + e1(d) + Ch(d, e, f) + 0x1e376c08 + W[49];
-	t2 = e0(h) + Maj(h, a, b);    c += t1;    g = t1 + t2;
-	t1 = f + e1(c) + Ch(c, d, e) + 0x2748774c + W[50];
-	t2 = e0(g) + Maj(g, h, a);    b += t1;    f = t1 + t2;
-	t1 = e + e1(b) + Ch(b, c, d) + 0x34b0bcb5 + W[51];
-	t2 = e0(f) + Maj(f, g, h);    a += t1;    e = t1 + t2;
-	t1 = d + e1(a) + Ch(a, b, c) + 0x391c0cb3 + W[52];
-	t2 = e0(e) + Maj(e, f, g);    h += t1;    d = t1 + t2;
-	t1 = c + e1(h) + Ch(h, a, b) + 0x4ed8aa4a + W[53];
-	t2 = e0(d) + Maj(d, e, f);    g += t1;    c = t1 + t2;
-	t1 = b + e1(g) + Ch(g, h, a) + 0x5b9cca4f + W[54];
-	t2 = e0(c) + Maj(c, d, e);    f += t1;    b = t1 + t2;
-	t1 = a + e1(f) + Ch(f, g, h) + 0x682e6ff3 + W[55];
-	t2 = e0(b) + Maj(b, c, d);    e += t1;    a = t1 + t2;
-
-	t1 = h + e1(e) + Ch(e, f, g) + 0x748f82ee + W[56];
-	t2 = e0(a) + Maj(a, b, c);    d += t1;    h = t1 + t2;
-	t1 = g + e1(d) + Ch(d, e, f) + 0x78a5636f + W[57];
-	t2 = e0(h) + Maj(h, a, b);    c += t1;    g = t1 + t2;
-	t1 = f + e1(c) + Ch(c, d, e) + 0x84c87814 + W[58];
-	t2 = e0(g) + Maj(g, h, a);    b += t1;    f = t1 + t2;
-	t1 = e + e1(b) + Ch(b, c, d) + 0x8cc70208 + W[59];
-	t2 = e0(f) + Maj(f, g, h);    a += t1;    e = t1 + t2;
-	t1 = d + e1(a) + Ch(a, b, c) + 0x90befffa + W[60];
-	t2 = e0(e) + Maj(e, f, g);    h += t1;    d = t1 + t2;
-	t1 = c + e1(h) + Ch(h, a, b) + 0xa4506ceb + W[61];
-	t2 = e0(d) + Maj(d, e, f);    g += t1;    c = t1 + t2;
-	t1 = b + e1(g) + Ch(g, h, a) + 0xbef9a3f7 + W[62];
-	t2 = e0(c) + Maj(c, d, e);    f += t1;    b = t1 + t2;
-	t1 = a + e1(f) + Ch(f, g, h) + 0xc67178f2 + W[63];
-	t2 = e0(b) + Maj(b, c, d);    e += t1;    a = t1 + t2;
+	for (i = 0; i < 64; i += 8) {
+		SHA256_ROUND(i + 0, a, b, c, d, e, f, g, h);
+		SHA256_ROUND(i + 1, h, a, b, c, d, e, f, g);
+		SHA256_ROUND(i + 2, g, h, a, b, c, d, e, f);
+		SHA256_ROUND(i + 3, f, g, h, a, b, c, d, e);
+		SHA256_ROUND(i + 4, e, f, g, h, a, b, c, d);
+		SHA256_ROUND(i + 5, d, e, f, g, h, a, b, c);
+		SHA256_ROUND(i + 6, c, d, e, f, g, h, a, b);
+		SHA256_ROUND(i + 7, b, c, d, e, f, g, h, a);
+	}
 
 	state[0] += a; state[1] += b; state[2] += c; state[3] += d;
 	state[4] += e; state[5] += f; state[6] += g; state[7] += h;