linux-kernel - Re: [PATCH v3 3/4] x86/alternative: Rewrite optimize

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 8 Feb 2023 21:45:39 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Andrew.Cooper3@...rix.com
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, mhiramat@...nel.org,
        kirill.shutemov@...ux.intel.com, jpoimboe@...hat.com
Subject: Re: [PATCH v3 3/4] x86/alternative: Rewrite optimize_nops() some

On Wed, Feb 08, 2023 at 09:44:04PM +0100, Peter Zijlstra wrote:
> GNU as seems to go to .nops 12. 13 gives me a single byte nop and a 12.
> That's also exactly the 3 prefix limit, after which some uarchs start
> taking heavy decode penalties.

Oh noes, counting hard. It maxes out at 11, not 12. Sadness.

Instead, lemme go figure out what those alternatives actually are.