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From: Peter Zijlstra <peterz@infradead.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	Damien Le Moal <Damien.LeMoal@wdc.com>,
	andrew.cooper3@citrix.com, jgross@suse.com
Subject: Re: WARNING: can't access registers at asm_common_interrupt
Date: Wed, 11 Nov 2020 21:42:28 +0100	[thread overview]
Message-ID: <20201111204228.GQ2628@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20201111181328.mbxcz2uap2vnqpxq@treble>

On Wed, Nov 11, 2020 at 12:13:28PM -0600, Josh Poimboeuf wrote:
> On Wed, Nov 11, 2020 at 06:47:36PM +0100, Peter Zijlstra wrote:

> > Yeah, so it's all a giant can of worms that; also see:
> > 
> >   https://lkml.kernel.org/r/20200821084738.508092956@infradead.org
> > 
> > The basic idea is to only trace edges, ie. when the hardware state
> > actually changes. Sadly this means doing a pushf/pop before the cli.
> > Ideally CLI would store the old IF in CF or something like that, but
> > alas.
> 
> Right, that makes sense for save/restore, but is the disabled check
> really needed for local_irq_disable()?  Wouldn't that always be an edge?

IIRC there is code that does local_irq_disable() even though IRQs are
already disabled. This is 'harmless'.

> And anyway I don't see a similar check for local_irq_enable().

I know there is code that does local_irq_enable() with IRQs already
enabled, I'm not exactly sure why this is different. I'll have to put it
on the todo list :/

  parent reply	other threads:[~2020-11-11 20:42 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-06  6:04 Shinichiro Kawasaki
2020-11-06 18:06 ` Josh Poimboeuf
2020-11-09  9:10   ` Shinichiro Kawasaki
2020-11-10  3:19     ` Josh Poimboeuf
2020-11-10  9:19       ` Shinichiro Kawasaki
2020-11-11 17:05 ` Josh Poimboeuf
2020-11-11 17:47   ` Peter Zijlstra
2020-11-11 18:13     ` Josh Poimboeuf
2020-11-11 18:46       ` Andrew Cooper
2020-11-11 19:42         ` Peter Zijlstra
2020-11-11 19:59           ` Josh Poimboeuf
2020-11-11 20:07             ` Peter Zijlstra
2020-11-11 20:15               ` Josh Poimboeuf
2020-11-11 20:25                 ` Andrew Cooper
2020-11-11 20:39                   ` Peter Zijlstra
2020-11-13 17:34                   ` Andy Lutomirski
2020-11-14  9:16                     ` Jürgen Groß
2020-11-14 18:10                       ` Andy Lutomirski
2020-11-15  6:33                         ` Jürgen Groß
2020-11-15 16:05                           ` Andy Lutomirski
2020-11-15 16:13                             ` Jürgen Groß
2020-11-16 11:56                     ` Jürgen Groß
2020-11-16 13:04                       ` Peter Zijlstra
2020-11-18  6:47                         ` Jürgen Groß
2020-11-18  8:22                           ` Peter Zijlstra
2020-11-19 11:51                             ` Shinichiro Kawasaki
2020-11-19 12:01                               ` Peter Zijlstra
2020-11-19 12:28                                 ` Jürgen Groß
2020-11-19 12:48                                 ` Shinichiro Kawasaki
2020-11-11 20:35                 ` Peter Zijlstra
2020-11-11 20:42       ` Peter Zijlstra [this message]
  -- strict thread matches above, loose matches on Subject: below --
2020-09-06 20:46 syzbot

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