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From:   Arnd Bergmann <arnd@kernel.org>
Date:   Thu, 22 Jul 2021 16:01:39 +0200
Message-ID: <CAK8P3a0xZAHknG8_kc62aaKrKdzD-QwQYHT61_wTbFDYADu-zw@mail.gmail.com>
Subject: Re: [PATCH v3 9/9] asm-generic: reverse GENERIC_{STRNCPY_FROM,
 STRNLEN}_USER symbols
To:     Johannes Berg <johannes@sipsolutions.net>
Cc:     linux-arch <linux-arch@vger.kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
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On Thu, Jul 22, 2021 at 3:57 PM Johannes Berg <johannes@sipsolutions.net> wrote:
>
> >
> > The remaining architectures at the moment are: ia64, mips, parisc,
> > s390, um and xtensa. We should probably convert these as well, but
>
> I'm not sure it makes sense to convert um, the implementation uses
> strncpy(), and that should use the libc implementation, which is tuned
> for the actual hardware that the binary is running on, so performance
> wise that might be better.
>
> OTOH, maybe this is all in the noise given the huge syscall overhead in
> um, so maybe unifying it would make more sense.

Right, makes sense. I suppose if we end up converting mips and s390,
we should just do arch/um and the others as well for consistency, even
if that adds some overhead.

      Arnd