linux-kernel - Re: WARNING: can't access registers at asm_common

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Message-ID: <69717baf-2f2c-bc53-b8c5-36552855fa99@suse.com>
Date:   Thu, 19 Nov 2020 13:28:55 +0100
From:   Jürgen Groß <jgross@...e.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Shinichiro Kawasaki <shinichiro.kawasaki@....com>
Cc:     Andy Lutomirski <luto@...nel.org>,
        Andrew Cooper <andrew.cooper3@...rix.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Damien Le Moal <Damien.LeMoal@....com>,
        X86 ML <x86@...nel.org>
Subject: Re: WARNING: can't access registers at asm_common_interrupt

On 19.11.20 13:01, Peter Zijlstra wrote:
> On Thu, Nov 19, 2020 at 11:51:00AM +0000, Shinichiro Kawasaki wrote:
>> I tried Peter's patch in my test system and result looks good. The warning is
>> still observed with 5.10-rc4. With the patch on top of 5.10-rc4, the warning
>> disappeared.
> 
> The patch on its own is not sufficient to fix things; there needs to be
> an accompanying objtool patch to generate the correct unwind
> information.
> 
> This patch only ensures objtool has enough information to be able to
> dtrt, but as it stands it shouldn't even compile, it should complain
> about an alternative trying to modify the stack and bail.
> 

It complains, but doesn't bail.

I'm nearly ready with my series replacing all the custom code paravirt
patches by ALTERNATIVEs. Quite some paravirt macro cruft turned out to
be unused, so there is a rather large cleanup patch included. :-)


Juergen

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