linux-kernel - Re: [PATCH] lib/crypto: blake2b: Limit frame size workaround to GCC

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Message-ID: <CAHmME9o7rw=Hi9ykfU4GD6Jxzo6Q404FVGVkUDh+RCjr_-DadQ@mail.gmail.com>
Date: Mon, 24 Nov 2025 18:14:31 +0100
From: "Jason A. Donenfeld" <Jason@...c4.com>
To: david laight <david.laight@...box.com>
Cc: Eric Biggers <ebiggers@...nel.org>, Thorsten Blum <thorsten.blum@...ux.dev>, 
	Ard Biesheuvel <ardb@...nel.org>, linux-crypto@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] lib/crypto: blake2b: Limit frame size workaround to GCC <
 12.2 on i386

On Mon, Nov 24, 2025 at 10:08 AM david laight <david.laight@...box.com> wrote:
> > How about we roll up the BLAKE2b rounds loop if !CONFIG_64BIT?
>
> I do wonder about the real benefit of some of the massive loop unrolling
> that happens in a lot of these algorithms (not just blake2b).

I remember looking at this in the context of blake2s, with two paths,
depending on CONFIG_CC_OPTIMIZE_FOR_SIZE, but the savings didn't seem
enough for the performance hit. It might be platform specific though.
I guess try it and post numbers, and that'll either be a compelling
reason to adjust it or still "meh"?

Jason