From: Peter Zijlstra <peterz@infradead.org>
To: Ingo Molnar <mingo@kernel.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 11:37:25 +0200 [thread overview]
Message-ID: <20231011093725.GD6307@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <ZSZYwvHTSapAaJQv@gmail.com>
On Wed, Oct 11, 2023 at 10:11:46AM +0200, Ingo Molnar wrote:
>
> * 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.
Yep, half-way through the patching it observes inconsistencies and goes
WTF :-)
next prev parent reply other threads:[~2023-10-11 9:37 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
2023-10-11 9:37 ` Peter Zijlstra [this message]
2023-10-11 13:27 ` Kirill A. Shutemov
2023-10-11 20:45 ` Ingo Molnar
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