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From: Ingo Molnar <mingo@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Andrey Ryabinin <ryabinin.a.a@gmail.com>,
	Alexander Potapenko <glider@google.com>,
	Andrey Konovalov <andreyknvl@gmail.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org,
	Fei Yang <fei.yang@intel.com>,
	stable@vger.kernel.org
Subject: Re: [PATCHv2] x86/alternatives: Disable KASAN in apply_alternatives()
Date: Wed, 11 Oct 2023 10:11:46 +0200	[thread overview]
Message-ID: <ZSZYwvHTSapAaJQv@gmail.com> (raw)
In-Reply-To: <20231011074616.GL14330@noisy.programming.kicks-ass.net>


* Peter Zijlstra <peterz@infradead.org> wrote:

> >  	DPRINTK(ALT, "alt table %px, -> %px", start, end);
> > +
> > +	/*
> > +	 * In the case CONFIG_X86_5LEVEL=y, KASAN_SHADOW_START is defined using
> > +	 * cpu_feature_enabled(X86_FEATURE_LA57) and is therefore patched here.
> > +	 * During the process, KASAN becomes confused and triggers
> 
> 	because of partial LA57 convertion ..

Not all LA57 related sites are patched yet at this point, and KASAN sees
a weird & broken mixture of LA48 and LA57 runtime semantics, right?

Ie. as far as KASAN is concerned, the LA48 -> LA57 behavioral switchover
must be atomic, but during the kernel code patching process it isn't.

Thanks,

	Ingo

  reply	other threads:[~2023-10-11  8:11 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-10-11  6:58 [PATCHv2] x86/alternatives: Disable KASAN in apply_alternatives() Kirill A. Shutemov
2023-10-11  7:46 ` Peter Zijlstra
2023-10-11  8:11   ` Ingo Molnar [this message]
2023-10-11  9:37     ` Peter Zijlstra
2023-10-11 13:27   ` Kirill A. Shutemov
2023-10-11 20:45     ` Ingo Molnar

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