linux-kernel - Re: [PATCH 1/2] x86: Remove dynamic NOP selection

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]

Message-ID: <4F17FAD6-9183-4F29-850D-8DE88FAB3658@zytor.com>
Date: Sun, 21 Jan 2024 18:04:42 -0800
From: "H. Peter Anvin" <hpa@...or.com>
To: Thorsten Glaser <tg@...ian.org>, Steven Rostedt <rostedt@...dmis.org>
CC: Peter Zijlstra <peterz@...radead.org>, x86@...nel.org,
        torvalds@...uxfoundation.org, linux-kernel@...r.kernel.org,
        linux-toolchains@...r.kernel.org, jpoimboe@...hat.com,
        alexei.starovoitov@...il.com, mhiramat@...nel.org
Subject: Re: [PATCH 1/2] x86: Remove dynamic NOP selection

On January 21, 2024 5:17:36 PM PST, Thorsten Glaser <tg@...ian.org> wrote:
>Steven Rostedt dixit:
>
>>> >This was, incidentally, triggered by looking into a problem report that
>>> >something did *not* work on a Geode LX system.
>>
>>What problem happened?
>
>It turned out to be a compiler issue (GCC thinks i686 means PPro,
>not 686-class CPUs, and -fcf-protection causes long NOPs, which
>not all 686-class CPUs support, to be inserted). This turned out
>to break a large part of Debian stable on OLPCs and other systems,
>and the kernel’s changes in nopl handling were tabled as arguments.
>
>https://www.jookia.org/wiki/Nopl has a longer writeup on the nopl
>history.
>
>bye,
>//mirabilos

i686 *is* Pentium Pro...