From: Jason A. Donenfeld
> Sent: 27 May 2022 09:11
>
> BLAKE2s has no use as an shash, with no users of it. Just remove all of
> this unnecessary plumbing. Removing this shash was something we talked
> about back when we were making BLAKE2s a built-in, but I simply never
> got around to doing it. So this completes that project.
...
> diff --git a/lib/crypto/blake2s.c b/lib/crypto/blake2s.c
> index c71c09621c09..716da32cf4dc 100644
> --- a/lib/crypto/blake2s.c
> +++ b/lib/crypto/blake2s.c
> @@ -16,16 +16,43 @@
> #include <linux/init.h>
> #include <linux/bug.h>
>
> +static inline void blake2s_set_lastblock(struct blake2s_state *state)
> +{
> + state->f[0] = -1;
> +}
> +
> void blake2s_update(struct blake2s_state *state, const u8 *in, size_t inlen)
> {
> - __blake2s_update(state, in, inlen, false);
> + const size_t fill = BLAKE2S_BLOCK_SIZE - state->buflen;
> +
> + if (unlikely(!inlen))
> + return;
Does this happen often enough to optimise for?
The zero length memcpy() should be fine.
(though pedants might worry about in == NULL)
> + if (inlen > fill) {
Testing inlen >= fill will be better.
You also don't need the code below in the (probably) likely
case that state->buflen == 0.
> + memcpy(state->buf + state->buflen, in, fill);
> + blake2s_compress(state, state->buf, 1, BLAKE2S_BLOCK_SIZE);
> + state->buflen = 0;
> + in += fill;
> + inlen -= fill;
an 'if (!inlen) return' check here may be a cheap optimisation.
> + }
> + if (inlen > BLAKE2S_BLOCK_SIZE) {
This test only needs to be inside the earlier inlen > fill condition.
The compiler may not be able to assume so.
> + const size_t nblocks = DIV_ROUND_UP(inlen, BLAKE2S_BLOCK_SIZE);
Why not inlen/BLAKE2S_BLOCK_SIZE and remove all the '- 1'.
Looping inside blakes2s_compress() has to be better than
doing an extra call when processing the next data block.
> + blake2s_compress(state, in, nblocks - 1, BLAKE2S_BLOCK_SIZE);
> + in += BLAKE2S_BLOCK_SIZE * (nblocks - 1);
> + inlen -= BLAKE2S_BLOCK_SIZE * (nblocks - 1);
> + }
> + memcpy(state->buf + state->buflen, in, inlen);
> + state->buflen += inlen;
> }
> EXPORT_SYMBOL(blake2s_update);
>
> void blake2s_final(struct blake2s_state *state, u8 *out)
> {
> WARN_ON(IS_ENABLED(DEBUG) && !out);
> - __blake2s_final(state, out, false);
> + blake2s_set_lastblock(state);
> + memset(state->buf + state->buflen, 0, BLAKE2S_BLOCK_SIZE - state->buflen); /* Padding */
> + blake2s_compress(state, state->buf, 1, state->buflen);
> + cpu_to_le32_array(state->h, ARRAY_SIZE(state->h));
> + memcpy(out, state->h, state->outlen);
> memzero_explicit(state, sizeof(*state));
> }
> EXPORT_SYMBOL(blake2s_final);
> @@ -38,12 +65,7 @@ static int __init blake2s_mod_init(void)
> return 0;
> }
David
-
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