linux-kernel - Re: [PATCH v3 1/3] kasan: mark !__SANITIZE_ADDRESS__ stubs __always

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Message-ID: <DF261MXQUYYU.130N0WZE4DP4U@google.com>
Date: Fri, 19 Dec 2025 11:45:01 +0000
From: Brendan Jackman <jackmanb@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Brendan Jackman <jackmanb@...gle.com>
Cc: 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>, Marco Elver <elver@...gle.com>, 
	Ard Biesheuvel <ardb@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>, 
	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>, Nathan Chancellor <nathan@...nel.org>, 
	Nick Desaulniers <nick.desaulniers+lkml@...il.com>, Bill Wendling <morbo@...gle.com>, 
	Justin Stitt <justinstitt@...gle.com>, <kasan-dev@...glegroups.com>, 
	<linux-kernel@...r.kernel.org>, <llvm@...ts.linux.dev>
Subject: Re: [PATCH v3 1/3] kasan: mark !__SANITIZE_ADDRESS__ stubs __always_inline

>> 
>> So in the meantime what's the cleanest fix? Going straight to the arch_*
>> calls from SEV seems pretty yucky in its own right.
>
> This is what I would do (and have done in the past):
>
>  14d3b376b6c3 ("x86/entry, cpumask: Provide non-instrumented variant of cpu_is_offline()")
>  f5c54f77b07b ("cpumask: Add a x86-specific cpumask_clear_cpu() helper")

OK, let's do it this way then.


>> > For the short term, we could avoid this by using arch___set_bit()
>
> arch_set_bit(), right?

I don't think so. Currently the GHCB accessors ar using __set_bit() i.e.
the non-atomic version. Am I missing something?