linux-kernel - Re: KASAN vs. boot-time switching between 4- and 5-level paging

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Date:   Mon, 10 Jul 2017 19:57:00 +0300
From:   Andrey Ryabinin <aryabinin@...tuozzo.com>
To:     "Kirill A. Shutemov" <kirill@...temov.name>
Cc:     Dmitry Vyukov <dvyukov@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "x86@...nel.org" <x86@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, Andi Kleen <ak@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Andy Lutomirski <luto@...capital.net>,
        linux-arch@...r.kernel.org,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        kasan-dev <kasan-dev@...glegroups.com>
Subject: Re: KASAN vs. boot-time switching between 4- and 5-level paging



On 07/10/2017 03:33 PM, Kirill A. Shutemov wrote:

> 
> [Sorry for loong delay.]
> 
> The patch works for me for legacy boot. But it breaks EFI boot with
> 5-level paging. And I struggle to understand why.
> 
> What I see is many page faults at mm/kasan/kasan.c:758 --
> "DEFINE_ASAN_LOAD_STORE(4)". Handling one of them I get double-fault at
> arch/x86/kernel/head_64.S:298 -- "pushq %r14", which ends up with triple
> fault.
> 
> Any ideas?
> 
> If you want to play with this by yourself, qemu supports la57 -- use
> -cpu "qemu64,+la57".
> 

I'll have a look.