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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: paul.gortmaker@windriver.com, x86@kernel.org,
	regressions@leemhuis.info, richard.purdie@linuxfoundation.org,
	regressions@lists.linux.dev
Subject: [patch 0/2] x86/alternatives: Prevent crash in NOP optimizer
Date: Thu,  7 Dec 2023 20:49:22 +0100 (CET)	[thread overview]
Message-ID: <20231207193859.961361261@linutronix.de> (raw)
In-Reply-To: <87r0k9ym0y.ffs@tglx>

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!

Thanks,

	tglx



  parent reply	other threads:[~2023-12-07 19:49 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-10-29 18:41 32 bit qemu regression from v6.5 tip pull [6c480f222128 x86/alternative: Rewrite optimize_nops() some] Paul Gortmaker
2023-10-30  8:26 ` Peter Zijlstra
2023-10-30 10:55   ` Richard Purdie
2023-10-30 11:44     ` Peter Zijlstra
2023-10-30 15:28       ` Paul Gortmaker
2023-10-30 18:24         ` Thomas Gleixner
2023-10-30 19:30           ` Thomas Gleixner
2023-10-31 15:40             ` Paul Gortmaker
2023-11-11 11:51               ` Linux regression tracking (Thorsten Leemhuis)
2023-11-22 14:11                 ` Richard Purdie
2023-11-29  8:57                 ` Thomas Gleixner
2023-12-06 15:46                   ` Paul Gortmaker
2023-12-07 16:34                     ` Thomas Gleixner
2023-12-07 16:52                       ` Paul Gortmaker
2023-12-07 19:49                   ` Thomas Gleixner [this message]
2023-12-07 19:49                     ` [patch 1/2] x86/alternatives: Sync core before enabling interrupts Thomas Gleixner
2023-12-07 19:49                     ` [patch 2/2] x86/alternatives: Disable interrupts and sync when optimizing NOPs in place Thomas Gleixner
2023-12-08 13:22                       ` Borislav Petkov
2023-12-08 13:37                         ` Thomas Gleixner
2023-12-08  8:35                     ` [patch 0/2] x86/alternatives: Prevent crash in NOP optimizer Paul Gortmaker
2023-12-15  9:10                     ` Peter Zijlstra

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