linux-kernel - Re: [RFC PATCH v2 01/10] lib: vdso: ensure all arches have 32bit fallback

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Date:   Fri, 10 Jan 2020 21:56:09 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Andy Lutomirski <luto@...nel.org>,
        Christophe Leroy <christophe.leroy@....fr>
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Arnd Bergmann <arnd@...db.de>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Andrew Lutomirski <luto@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        "open list\:MIPS" <linux-mips@...r.kernel.org>,
        X86 ML <x86@...nel.org>
Subject: Re: [RFC PATCH v2 01/10] lib: vdso: ensure all arches have 32bit fallback

Andy Lutomirski <luto@...nel.org> writes:

> On Mon, Dec 23, 2019 at 6:31 AM Christophe Leroy
> <christophe.leroy@....fr> wrote:
>>
>> In order to simplify next step which moves fallback call at arch
>> level, ensure all arches have a 32bit fallback instead of handling
>> the lack of 32bit fallback in the common code based
>> on VDSO_HAS_32BIT_FALLBACK
>
> I don't like this.  You've implemented what appear to be nonsensical
> fallbacks (the 32-bit fallback for a 64-bit vDSO build?  There's no
> such thing).
>
> How exactly does this simplify patch 2?

There is a patchset from Vincenzo which fell through the cracks which
addresses the VDS_HAS_32BIT_FALLBACK issue properly. I'm about to pick
it up. See:

 https://lore.kernel.org/lkml/20190830135902.20861-1-vincenzo.frascino@arm.com/

Thanks,

        tglx