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Date:   Tue, 10 Oct 2023 13:30:26 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Borislav Petkov <bp@alien8.de>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        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: [PATCH] x86/alternatives: Disable KASAN on text_poke_early() in
 apply_alternatives()
Message-ID: <20231010103026.hcjn47kvjqesxoqj@box.shutemov.name>
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On Tue, Oct 10, 2023 at 12:16:21PM +0200, Peter Zijlstra wrote:
> On Tue, Oct 10, 2023 at 12:10:56PM +0200, Peter Zijlstra wrote:
> 
> > That said, I don't particularly like the patch, I think it should, at
> > the veyr least, cover all of apply_alternatives, not just
> > text_poke_early().
> 
> kasan_arch_is_ready() is another option, x86 doesn't currently define
> that, but that would allow us to shut kasan down harder around patching.
> Not sure if it's worth the trouble though.

IIUC, it was intended to delay KASAN usage until it is ready. KASAN is
functional well before apply_alternatives() and making
kasan_arch_is_ready() temporary false for patching feels like abuse of the
hook.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov