linux-kernel - Re: [PATCH v2 2/3] x86/traps: Print non-canonical address on #GP

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Date:   Wed, 20 Nov 2019 12:41:39 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Dmitry Vyukov <dvyukov@...gle.com>, Jann Horn <jannh@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        the arch/x86 maintainers <x86@...nel.org>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: Re: [PATCH v2 2/3] x86/traps: Print non-canonical address on #GP


* Borislav Petkov <bp@...en8.de> wrote:

> On Mon, Nov 18, 2019 at 05:44:07PM +0100, Borislav Petkov wrote:
> > [    2.523708] Write protecting the kernel read-only data: 16384k
> > [    2.524729] Freeing unused kernel image (text/rodata gap) memory: 2040K
> > [    2.525594] Freeing unused kernel image (rodata/data gap) memory: 368K
> > [    2.541414] x86/mm: Checked W+X mappings: passed, no W+X pages found.
> > 
> > <--- important first splat starts here:
> > 
> > [    2.542218] [*] general protection fault while derefing a non-canonical address 0xdfff000000000001: 0000 [#1] PREEMPT SMP
> 		  ^
> 
> Btw, tglx just suggested on IRC to simply slap the die_counter number here so
> that you have
> 
> [    2.543343] [1] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.4.0-rc8+ #8
> [    2.544138] [1] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.1-1 04/01/2014
> ...
> 
> which also tells you to which splat the line belongs to.
>
> Also useful.

Yeah - but I think it would be even better to make it part of the 
timestamp - most tools will already discard the [] bit, so why not merge 
the two:

> [    2.543343-#1] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.4.0-rc8+ #8
> [    2.544138-#1] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.1-1 04/01/2014

Thanks,

	Ingo