linux-kernel - Re: [RFC PATCH] rseq: x86: implement abort-at-ip extension

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: <396330808.24806.1642005485899.JavaMail.zimbra@efficios.com>
Date:   Wed, 12 Jan 2022 11:38:05 -0500 (EST)
From:   Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:     Florian Weimer <fw@...eb.enyo.de>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        paulmck <paulmck@...nel.org>, Boqun Feng <boqun.feng@...il.com>,
        "H. Peter Anvin" <hpa@...or.com>, Paul Turner <pjt@...gle.com>,
        linux-api <linux-api@...r.kernel.org>,
        Christian Brauner <christian.brauner@...ntu.com>,
        carlos <carlos@...hat.com>
Subject: Re: [RFC PATCH] rseq: x86: implement abort-at-ip extension

----- On Jan 12, 2022, at 11:00 AM, Florian Weimer fw@...eb.enyo.de wrote:

> * Peter Zijlstra:
> 
>> On Wed, Jan 12, 2022 at 04:16:36PM +0100, Florian Weimer wrote:
>>
>>> You could perhaps push a signal frame onto the stack.  It's going to
>>> be expensive, but it's already in the context switch path, so maybe it
>>> does not matter.
>>
>> Please no! Signals are a trainwreck that need change (see the whole
>> AVX-512 / AMX saga), we shouldn't use more of that just cause.
> 
> If it's a signal, it should be modeled as such.  I think it's pretty
> close to a synchronous signal.

Florian, just to validate here: is your argument about AVX-512/AMX or about
rseq abort-at-ip ?

Am I understanding correctly that you would prefer that the kernel push an entire
signal frame onto the stack rather than just push the abort-at-ip value
on abort ? If it is the case, are there advantages in doing so ? Tooling support ?

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com