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Date: Fri, 15 Dec 2023 10:10:53 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>, paul.gortmaker@windriver.com,
	x86@kernel.org, regressions@leemhuis.info,
	richard.purdie@linuxfoundation.org, regressions@lists.linux.dev
Subject: Re: [patch 0/2] x86/alternatives: Prevent crash in NOP optimizer
Message-ID: <20231215091053.GI36716@noisy.programming.kicks-ass.net>
References: <ZXCXc+BtnLzqMbFv@windriver.com>
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 <0adb772c-e8d2-4444-92b0-00cbfdaf1fac@leemhuis.info>
 <87r0k9ym0y.ffs@tglx>
 <20231207193859.961361261@linutronix.de>
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On Thu, Dec 07, 2023 at 08:49:22PM +0100, Thomas Gleixner wrote:
> The following series addresses the regression report from Paul on behalf of
> the yocto project. It turns out that the recent changes to alternatives
> opened a race window where interrupts are enabled and NOPs are optimized in
> place. An interrupt hitting into the modification will observe inconsistent
> text and crash and burn.
> 
> A 32bit QEMU crashes w/o these fixes reliably within about 50 boot
> attempts. With the fix applied it survived close to 600 attempts by
> now.
> 
> Thanks to Paul for providing all the information!

Urgh and D'0h.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>