From: David Woodhouse <dwmw2@infradead.org>
To: Paul Turner <pjt@google.com>,
Peter Zijlstra <peterz@infradead.org>,
"Van De Ven, Arjan" <arjan.van.de.ven@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>,
LKML <linux-kernel@vger.kernel.org>,
Greg Kroah-Hartman <gregkh@linux-foundation.org>,
Tim Chen <tim.c.chen@linux.intel.com>,
Dave Hansen <dave.hansen@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Andy Lutomirski <luto@amacapital.net>,
Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH] x86/retpoline: Avoid return buffer underflows on context switch
Date: Tue, 09 Jan 2018 00:48:02 +0000 [thread overview]
Message-ID: <1515458882.4423.82.camel@infradead.org> (raw)
In-Reply-To: <1515458673.4423.79.camel@amazon.co.uk>
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On Tue, 2018-01-09 at 00:44 +0000, Woodhouse, David wrote:
> On IRC, Arjan assures me that 'pause' here really is sufficient as a
> speculation trap. If we do end up returning back here as a
> misprediction, that 'pause' will stop the speculative execution on
> affected CPUs even though it isn't *architecturally* documented to do
> so.
>
> Arjan, can you confirm that in email please?
That actually doesn't make sense to me. If 'pause' alone is sufficient,
then why in $DEITY's name would we need a '1:pause;jmp 1b' loop in the
retpoline itself?
Arjan?
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next prev parent reply other threads:[~2018-01-09 0:48 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-08 20:15 Andi Kleen
2018-01-08 21:38 ` David Woodhouse
2018-01-08 22:54 ` Andi Kleen
2018-01-08 22:11 ` Peter Zijlstra
2018-01-08 22:17 ` Woodhouse, David
2018-01-08 22:26 ` Peter Zijlstra
2018-01-08 23:25 ` Woodhouse, David
2018-01-08 22:25 ` Andi Kleen
2018-01-08 22:58 ` Andi Kleen
2018-01-09 0:15 ` Paul Turner
2018-01-09 0:15 ` Paul Turner
2018-01-09 0:44 ` Woodhouse, David
2018-01-09 0:48 ` David Woodhouse [this message]
2018-01-09 2:48 ` Paul Turner
2018-01-09 3:05 ` David Woodhouse
2018-01-12 11:15 ` David Laight
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