linux-kernel - Re: [Y2038] [PATCH 3/8] powerpc: fix vdso32 for ppc64le

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Message-ID: <58067b19b218600f95dbb9726e63b435d040be1c.camel@codethink.co.uk>
Date:   Thu, 21 Nov 2019 15:56:12 +0000
From:   Ben Hutchings <ben.hutchings@...ethink.co.uk>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     y2038 Mailman List <y2038@...ts.linaro.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [Y2038] [PATCH 3/8] powerpc: fix vdso32 for ppc64le

On Thu, 2019-11-21 at 11:02 +0100, Arnd Bergmann wrote:
> On Wed, Nov 20, 2019 at 10:49 PM Ben Hutchings
> <ben.hutchings@...ethink.co.uk> wrote:
> > On Wed, 2019-11-20 at 20:35 +0100, Arnd Bergmann wrote:
> > > On Wed, Nov 20, 2019 at 8:13 PM Ben Hutchings
> > > <ben.hutchings@...ethink.co.uk> wrote:
> > > > On Fri, 2019-11-08 at 21:34 +0100, Arnd Bergmann wrote:
> > > > > On little-endian 32-bit application running on 64-bit kernels,
> > > > > the current vdso would read the wrong half of the xtime seconds
> > > > > field. Change it to return the lower half like it does on
> > > > > big-endian.
> > > > 
> > > > ppc64le doesn't have 32-bit compat so this is only theoretical.
> > > 
> > > That is probably true. I only looked at the kernel, which today still
> > > supports compat mode for ppc64le, but I saw the patches to disable
> > > it, and I don't think anyone has even attempted building user space
> > > for it.
> > 
> > COMPAT is still enabled for some reason, but VDSO32 isn't (since 4.2).
> 
> Ok, I had missed that detail. Should I just drop my patch then?

I think so.

Ben.

-- 
Ben Hutchings, Software Developer                         Codethink Ltd
https://www.codethink.co.uk/                 Dale House, 35 Dale Street
                                     Manchester, M1 2HF, United Kingdom