[PATCH crypto 1/2] lib/crypto: blake2s-generic: reduce code size on small systems

[Jason A. Donenfeld]

Re-wind the loops entirely on kernels optimized for code size. This is
really not good at all performance-wise. But on m68k, it shaves off 4k
of code size, which is apparently important.

Cc: Geert Uytterhoeven <ge...@linux-m68k.org>
Cc: Herbert Xu <herb...@gondor.apana.org.au>
Cc: Ard Biesheuvel <a...@kernel.org>
Signed-off-by: Jason A. Donenfeld <ja...@zx2c4.com>
---
 lib/crypto/blake2s-generic.c | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/lib/crypto/blake2s-generic.c b/lib/crypto/blake2s-generic.c
index 75ccb3e633e6..990f000e22ee 100644
--- a/lib/crypto/blake2s-generic.c
+++ b/lib/crypto/blake2s-generic.c
@@ -46,7 +46,7 @@ void blake2s_compress_generic(struct blake2s_state *state, 
const u8 *block,
 {
        u32 m[16];
        u32 v[16];
-       int i;
+       int i, j;
 
        WARN_ON(IS_ENABLED(DEBUG) &&
                (nblocks > 1 && inc != BLAKE2S_BLOCK_SIZE));
@@ -86,17 +86,23 @@ void blake2s_compress_generic(struct blake2s_state *state, 
const u8 *block,
        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);
-
+               if (IS_ENABLED(CONFIG_CC_OPTIMIZE_FOR_SIZE)) {
+                       for (i = 0; i < 10; ++i) {
+                               for (j = 0; j < 8; ++j)
+                                       G(i, j, v[j % 4], v[((j + (j / 4)) % 4) 
+ 4], v[((j + 2 * (j / 4)) % 4) + 8], v[((j + 3 * (j / 4)) % 4) + 12]);
+                       }
+               } else {
+                       ROUND(0);
+                       ROUND(1);
+                       ROUND(2);
+                       ROUND(3);
+                       ROUND(4);
+                       ROUND(5);
+                       ROUND(6);
+                       ROUND(7);
+                       ROUND(8);
+                       ROUND(9);
+               }
 #undef G
 #undef ROUND
 
-- 
2.34.1