linux-kernel - Re: [PATCH 03/21] rcu: Add a note about noinstr VS unsafe eqs functions

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: <20220519150135.GA618878@lothringen>
Date:   Thu, 19 May 2022 17:01:35 +0200
From:   Frederic Weisbecker <frederic@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     LKML <linux-kernel@...r.kernel.org>, Phil Auld <pauld@...hat.com>,
        Alex Belits <abelits@...vell.com>,
        Nicolas Saenz Julienne <nsaenz@...nel.org>,
        Xiongfeng Wang <wangxiongfeng2@...wei.com>,
        Neeraj Upadhyay <quic_neeraju@...cinc.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Yu Liao <liaoyu15@...wei.com>,
        Boqun Feng <boqun.feng@...il.com>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Marcelo Tosatti <mtosatti@...hat.com>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        Uladzislau Rezki <uladzislau.rezki@...y.com>,
        Joel Fernandes <joel@...lfernandes.org>
Subject: Re: [PATCH 03/21] rcu: Add a note about noinstr VS unsafe eqs
 functions

On Thu, May 19, 2022 at 04:48:21PM +0200, Peter Zijlstra wrote:
> On Tue, May 03, 2022 at 12:00:33PM +0200, Frederic Weisbecker wrote:
> > Some RCU functions enter or exit into/from RCU idle mode while using
> > trace-able and lockdep-aware IRQs (un-)masking. This could be easily
> > solved with using raw versions of local_irq_*() but we would then
> > lose some precious debugging informations.
> > 
> > Another possible way to solve this may consist in using rude RCU-tasks
> > in lockdep and irqsoff tracing.
> > 
> > In any case and until this get solved, those RCU functions can't get
> > tagged as noinstr even though they should.
> 
> No need to speculate on how to solve it; the generic entry code has
> alternatives that are good. It's just that reworking your architecture
> isn't trivial.

Speaking of, please have a look at this:

https://lore.kernel.org/all/20220518162118.GA2661055@paulmck-ThinkPad-P17-Gen-1/