From: Paul Menzel <pmenzel@molgen.mpg.de>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Paul Mackerras <paulus@samba.org>,
Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Derek Parker <parkerderek86@gmail.com>,
Dmitrii Okunev <xaionaro@gmail.com>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: Possible regression by ab037dd87a2f (powerpc/vdso: Switch VDSO to generic C implementation.)
Date: Wed, 28 Jul 2021 10:26:29 +0200 [thread overview]
Message-ID: <4f037af0-5066-ebb9-53a6-733b3bd8eeac@molgen.mpg.de> (raw)
In-Reply-To: <3661999754da1a5e5c810fa669654cc7db95b059.camel@kernel.crashing.org>
Dear Benjamin,
Am 28.07.21 um 01:14 schrieb Benjamin Herrenschmidt:
> On Tue, 2021-07-27 at 10:45 +0200, Paul Menzel wrote:
>> On ppc64le Go 1.16.2 from Ubuntu 21.04 terminates with a segmentation
>> fault [1], and it might be related to *[release-branch.go1.16] runtime:
>> fix crash during VDSO calls on PowerPC* [2], conjecturing that commit
>> ab037dd87a2f (powerpc/vdso: Switch VDSO to generic C implementation.)
>> added in Linux 5.11 causes this.
>>
>> If this is indeed the case, this would be a regression in userspace. Is
>> there a generic fix or should the change be reverted?
>
> From the look at the links you posted, this appears to be completely
> broken assumptions by Go that some registers don't change while calling
> what essentially are external library functions *while inside those
> functions* (ie in this case from a signal handler).
>
> I suppose it would be possible to build the VDSO with gcc arguments to
> make it not use r30, but that's just gross...
Thank you for looking into this. No idea, if it falls under Linux’ no
regression policy or not.
Kind regards,
Paul
next prev parent reply other threads:[~2021-07-28 8:27 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-27 8:45 Possible regression by ab037dd87a2f (powerpc/vdso: Switch VDSO to generic C implementation.) Paul Menzel
2021-07-27 23:14 ` Benjamin Herrenschmidt
2021-07-28 8:26 ` Paul Menzel [this message]
2021-07-28 12:43 ` Michael Ellerman
2021-07-28 12:53 ` Paul Menzel
2021-07-29 7:41 ` Michael Ellerman
2021-07-29 8:33 ` Paul Menzel
2021-07-29 12:58 ` Michael Ellerman
[not found] ` <875ywt1s9r.fsf__45665.8238823124$1627544516$gmane$org@mpe.ellerman.id.au>
2021-07-29 8:48 ` Andreas Schwab
2021-08-02 6:04 ` Michael Ellerman
[not found] ` <OF44F7146F.67A4C1C2-ON00258720.004DBF64-00258720.004FCFCC@ibm.com>
2021-08-02 6:18 ` Michael Ellerman
2021-08-02 12:48 ` Benjamin Herrenschmidt
2021-08-02 18:07 ` Segher Boessenkool
2021-08-02 18:14 ` Lynn Boger
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