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Message-ID: <ZSZYwvHTSapAaJQv@gmail.com>
Date: Wed, 11 Oct 2023 10:11:46 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>,
Andrey Ryabinin <ryabinin.a.a@...il.com>,
Alexander Potapenko <glider@...gle.com>,
Andrey Konovalov <andreyknvl@...il.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
Vincenzo Frascino <vincenzo.frascino@....com>,
kasan-dev@...glegroups.com, linux-kernel@...r.kernel.org,
Fei Yang <fei.yang@...el.com>, stable@...r.kernel.org
Subject: Re: [PATCHv2] x86/alternatives: Disable KASAN in apply_alternatives()
* Peter Zijlstra <peterz@...radead.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
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