[PATCH 4.9 052/264] lib/crypto: sha1: re-roll loops to reduce code size

Greg Kroah-Hartman
2022-06-23T17:00:49Z

From: "Jason A. Donenfeld" <Jason@zx2c4.com>

commit 9a1536b093bb5bf60689021275fd24d513bb8db0 upstream.

With SHA-1 no longer being used for anything performance oriented, and
also soon to be phased out entirely, we can make up for the space added
by unrolled BLAKE2s by simply re-rolling SHA-1. Since SHA-1 is so much
more complex, re-rolling it more or less takes care of the code size
added by BLAKE2s. And eventually, hopefully we'll see SHA-1 removed
entirely from most small kernel builds.

Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
lib/sha1.c | 95 ++++++++-----------------------------------------------------
1 file changed, 14 insertions(+), 81 deletions(-)

--- a/lib/sha1.c
+++ b/lib/sha1.c
@@ -9,6 +9,7 @@
#include <linux/export.h>
#include <linux/bitops.h>
#include <linux/cryptohash.h>
+#include <linux/string.h>
#include <asm/unaligned.h>

/*
@@ -54,7 +55,8 @@
#define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \
__u32 TEMP = input(t); setW(t, TEMP); \
E += TEMP + rol32(A,5) + (fn) + (constant); \
- B = ror32(B, 2); } while (0)
+ B = ror32(B, 2); \
+ TEMP = E; E = D; D = C; C = B; B = A; A = TEMP; } while (0)

#define T_0_15(t, A, B, C, D, E) SHA_ROUND(t, SHA_SRC, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
#define T_16_19(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
@@ -81,6 +83,7 @@
void sha_transform(__u32 *digest, const char *data, __u32 *array)
{
__u32 A, B, C, D, E;
+ unsigned int i = 0;

A = digest[0];
B = digest[1];
@@ -89,94 +92,24 @@ void sha_transform(__u32 *digest, const
E = digest[4];

/* Round 1 - iterations 0-16 take their input from 'data' */
- T_0_15( 0, A, B, C, D, E);
- T_0_15( 1, E, A, B, C, D);
- T_0_15( 2, D, E, A, B, C);
- T_0_15( 3, C, D, E, A, B);
- T_0_15( 4, B, C, D, E, A);
- T_0_15( 5, A, B, C, D, E);
- T_0_15( 6, E, A, B, C, D);
- T_0_15( 7, D, E, A, B, C);
- T_0_15( 8, C, D, E, A, B);
- T_0_15( 9, B, C, D, E, A);
- T_0_15(10, A, B, C, D, E);
- T_0_15(11, E, A, B, C, D);
- T_0_15(12, D, E, A, B, C);
- T_0_15(13, C, D, E, A, B);
- T_0_15(14, B, C, D, E, A);
- T_0_15(15, A, B, C, D, E);
+ for (; i < 16; ++i)
+ T_0_15(i, A, B, C, D, E);

/* Round 1 - tail. Input from 512-bit mixing array */
- T_16_19(16, E, A, B, C, D);
- T_16_19(17, D, E, A, B, C);
- T_16_19(18, C, D, E, A, B);
- T_16_19(19, B, C, D, E, A);
+ for (; i < 20; ++i)
+ T_16_19(i, A, B, C, D, E);

/* Round 2 */
- T_20_39(20, A, B, C, D, E);
- T_20_39(21, E, A, B, C, D);
- T_20_39(22, D, E, A, B, C);
- T_20_39(23, C, D, E, A, B);
- T_20_39(24, B, C, D, E, A);
- T_20_39(25, A, B, C, D, E);
- T_20_39(26, E, A, B, C, D);
- T_20_39(27, D, E, A, B, C);
- T_20_39(28, C, D, E, A, B);
- T_20_39(29, B, C, D, E, A);
- T_20_39(30, A, B, C, D, E);
- T_20_39(31, E, A, B, C, D);
- T_20_39(32, D, E, A, B, C);
- T_20_39(33, C, D, E, A, B);
- T_20_39(34, B, C, D, E, A);
- T_20_39(35, A, B, C, D, E);
- T_20_39(36, E, A, B, C, D);
- T_20_39(37, D, E, A, B, C);
- T_20_39(38, C, D, E, A, B);
- T_20_39(39, B, C, D, E, A);
+ for (; i < 40; ++i)
+ T_20_39(i, A, B, C, D, E);

/* Round 3 */
- T_40_59(40, A, B, C, D, E);
- T_40_59(41, E, A, B, C, D);
- T_40_59(42, D, E, A, B, C);
- T_40_59(43, C, D, E, A, B);
- T_40_59(44, B, C, D, E, A);
- T_40_59(45, A, B, C, D, E);
- T_40_59(46, E, A, B, C, D);
- T_40_59(47, D, E, A, B, C);
- T_40_59(48, C, D, E, A, B);
- T_40_59(49, B, C, D, E, A);
- T_40_59(50, A, B, C, D, E);
- T_40_59(51, E, A, B, C, D);
- T_40_59(52, D, E, A, B, C);
- T_40_59(53, C, D, E, A, B);
- T_40_59(54, B, C, D, E, A);
- T_40_59(55, A, B, C, D, E);
- T_40_59(56, E, A, B, C, D);
- T_40_59(57, D, E, A, B, C);
- T_40_59(58, C, D, E, A, B);
- T_40_59(59, B, C, D, E, A);
+ for (; i < 60; ++i)
+ T_40_59(i, A, B, C, D, E);

/* Round 4 */
- T_60_79(60, A, B, C, D, E);
- T_60_79(61, E, A, B, C, D);
- T_60_79(62, D, E, A, B, C);
- T_60_79(63, C, D, E, A, B);
- T_60_79(64, B, C, D, E, A);
- T_60_79(65, A, B, C, D, E);
- T_60_79(66, E, A, B, C, D);
- T_60_79(67, D, E, A, B, C);
- T_60_79(68, C, D, E, A, B);
- T_60_79(69, B, C, D, E, A);
- T_60_79(70, A, B, C, D, E);
- T_60_79(71, E, A, B, C, D);
- T_60_79(72, D, E, A, B, C);
- T_60_79(73, C, D, E, A, B);
- T_60_79(74, B, C, D, E, A);
- T_60_79(75, A, B, C, D, E);
- T_60_79(76, E, A, B, C, D);
- T_60_79(77, D, E, A, B, C);
- T_60_79(78, C, D, E, A, B);
- T_60_79(79, B, C, D, E, A);
+ for (; i < 80; ++i)
+ T_60_79(i, A, B, C, D, E);

digest[0] += A;
digest[1] += B;