Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Tue, 11 Jan 2022 13:57:51 +0100 | Subject | Re: [PATCH v2 2/2] random: use BLAKE2s instead of SHA1 in extraction |
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Hi Jason,
On Tue, Jan 11, 2022 at 1:50 PM Jason A. Donenfeld <Jason@zx2c4.com> wrote: > On Tue, Jan 11, 2022 at 1:28 PM Jason A. Donenfeld <Jason@zx2c4.com> wrote: > > If you're really quite concerned about m68k code size, I can probably
It's not just m68k. There exist ARM SoCs with 8 MiB builtin SRAM that are used in products running Linux.
> > do some things to reduce that. For example, blake2s256_hmac is only > > used by wireguard and it could probably be made local there. And with > > some trivial loop re-rolling, I can shave off another 2300 bytes. And > > I bet I can find a few other things too. The question is: how > > important is this to you? > > And with another trick (see below), another extra 1000 bytes or so > shaved off. Aside from moving blake2s256_hmac, I'm not really super > enthusiastic about making these changes, but depending on how important > this is to you, maybe we can make something work. There are probably > additional possibilities too with the code.
Cool, much more than 1000 bytes:
add/remove: 1/0 grow/shrink: 0/1 up/down: 160/-4032 (-3872) Function old new delta blake2s_sigma - 160 +160 blake2s_compress_generic 4448 416 -4032 Total: Before=4227876, After=4224004, chg -0.09%
I don't know what the impact is on performance, and if the compiler might do a good job unrolling this again when performance matters (i.e. if CONFIG_CC_OPTIMIZE_FOR_SIZE is not set).
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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