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SubjectRe: [PATCHv2] x86/alternatives: Disable KASAN in apply_alternatives()
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 :-)

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