linux-kernel - Re: [PATCH] x86: add hintable NOPs emulation

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] [day] [month] [year] [list]

Message-ID: <20250820103027.GHaKWjw_eVAbFEe8se@fat_crate.local>
Date: Wed, 20 Aug 2025 12:30:27 +0200
From: Borislav Petkov <bp@...en8.de>
To: Marcos Del Sol Vives <marcos@...a.pet>
Cc: "Ahmed S. Darwish" <darwi@...utronix.de>, linux-kernel@...r.kernel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>, Brian Gerst <brgerst@...il.com>,
	Uros Bizjak <ubizjak@...il.com>, Ard Biesheuvel <ardb@...nel.org>,
	David Kaplan <david.kaplan@....com>, Kees Cook <kees@...nel.org>,
	"Peter Zijlstra (Intel)" <peterz@...radead.org>,
	Andrew Cooper <andrew.cooper3@...rix.com>,
	Oleg Nesterov <oleg@...hat.com>, "Xin Li (Intel)" <xin@...or.com>,
	Sabyrzhan Tasbolatov <snovitoll@...il.com>
Subject: Re: [PATCH] x86: add hintable NOPs emulation

On Wed, Aug 20, 2025 at 12:21:40PM +0200, Marcos Del Sol Vives wrote:
> Would a simple:
> 
> > pr_warn_once("Your processor does not correctly handle hintable NOPs.\n");
> > pr_warn_once("The kernel will emulate them, but the performance will be impacted!\n");
> 
> work for you, then? With no thread information, as that might make the user
> think there is only once binary impacted.

I don't mind if you make the warning message as helpful as possible and even
dump current->comm and whatever else is needed to help the user address the
issue.

What I mind is flooding dmesg unnecessarily with the same stanzas over and
over again.

If the user can do something about it, then she should be able to find out
also which executables need to be recompiled.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette