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lib/crypto: blake2s: Replace manual unrolling with unrolled_full 

As we're doing in the BLAKE2b code, use unrolled_full to make the
compiler handle the loop unrolling.  This simplifies the code slightly.
The generated object code is nearly the same with both gcc and clang.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20251205051155.25274-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
master
Eric Biggers 2025-12-04 21:11:55 -08:00
parent 2e8f7b170a
commit 68b233b1d5
1 changed files with 16 additions and 22 deletions
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38
lib/crypto/blake2s.c
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@ -14,6 +14,7 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/unroll.h>
#include <linux/types.h>
static const u8 blake2s_sigma[10][16] = {
@ -71,29 +72,22 @@ blake2s_compress_generic(struct blake2s_ctx *ctx,
b = ror32(b ^ c, 7); \
} while (0)
#define ROUND(r) do { \
G(r, 0, v[0], v[ 4], v[ 8], v[12]); \
G(r, 1, v[1], v[ 5], v[ 9], v[13]); \
G(r, 2, v[2], v[ 6], v[10], v[14]); \
G(r, 3, v[3], v[ 7], v[11], v[15]); \
G(r, 4, v[0], v[ 5], v[10], v[15]); \
G(r, 5, v[1], v[ 6], v[11], v[12]); \
G(r, 6, v[2], v[ 7], v[ 8], v[13]); \
G(r, 7, v[3], v[ 4], v[ 9], v[14]); \
} while (0)
ROUND(0);
ROUND(1);
ROUND(2);
ROUND(3);
ROUND(4);
ROUND(5);
ROUND(6);
ROUND(7);
ROUND(8);
ROUND(9);
/*
* Unroll the rounds loop to enable constant-folding of the
* blake2s_sigma values.
*/
unrolled_full
for (int r = 0; r < 10; r++) {
G(r, 0, v[0], v[4], v[8], v[12]);
G(r, 1, v[1], v[5], v[9], v[13]);
G(r, 2, v[2], v[6], v[10], v[14]);
G(r, 3, v[3], v[7], v[11], v[15]);
G(r, 4, v[0], v[5], v[10], v[15]);
G(r, 5, v[1], v[6], v[11], v[12]);
G(r, 6, v[2], v[7], v[8], v[13]);
G(r, 7, v[3], v[4], v[9], v[14]);
}
#undef G
#undef ROUND
for (i = 0; i < 8; ++i)
ctx->h[i] ^= v[i] ^ v[i + 8];