linux-kernel - Re: [PATCH v2] x86: bring back rep movsq for user access on CPUs without ERMS

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Date:   Sun, 3 Sep 2023 14:08:58 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Mateusz Guzik <mjguzik@...il.com>
Cc:     linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        bp@...en8.de
Subject: Re: [PATCH v2] x86: bring back rep movsq for user access on CPUs
 without ERMS

On Sun, 3 Sept 2023 at 14:06, Mateusz Guzik <mjguzik@...il.com> wrote:
>
> I don't think it is *that* bad. I did a quick sanity check on that
> front by rolling with bpftrace on cases which pass AT_EMPTY_PATH *and*
> provide a path.

I guess you are right - nobody sane would use AT_EMPTY_PATH except if
they don't have a path.

Of course, the only reason we're discussing this in the first place is
because people are doing insane things, which makes _that_ particular
argument very weak indeed...

                     Linus