linux-kernel - Re: [RFC PATCH v1] powerpc: Enable KFENCE for PPC32

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Message-ID: <87tupprfan.fsf@mpe.ellerman.id.au>
Date:   Fri, 05 Mar 2021 22:49:36 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Marco Elver <elver@...gle.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>
Cc:     Alexander Potapenko <glider@...gle.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        LKML <linux-kernel@...r.kernel.org>,
        linuxppc-dev@...ts.ozlabs.org,
        kasan-dev <kasan-dev@...glegroups.com>
Subject: Re: [RFC PATCH v1] powerpc: Enable KFENCE for PPC32

Marco Elver <elver@...gle.com> writes:
...
>
> The choice is between:
>
> 1. ARCH_FUNC_PREFIX (as a matter of fact, the ARCH_FUNC_PREFIX patch
> is already in -mm). Perhaps we could optimize it further, by checking
> ARCH_FUNC_PREFIX in buf, and advancing buf like you propose, but I'm
> not sure it's worth worrying about.
>
> 2. The dynamic solution that I proposed that does not use a hard-coded
> '.' (or some variation thereof).
>
> Please tell me which solution you prefer, 1 or 2 -- I'd like to stop
> bikeshedding here. If there's a compelling argument for hard-coding
> the '.' in non-arch code, please clarify, but otherwise I'd like to
> keep arch-specific things out of generic code.

It's your choice, I was just trying to minimise the size of the wart you
have to carry in kfence code to deal with it.

The ARCH_FUNC_PREFIX solution is fine by me.

cheers