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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Tue, 10 Oct 2023 11:37:43 -0700
Message-ID: <CAHk-=wiALZxieQQmvv5sW15HYB_YwC3d_ma9sdp7Zb4Fb4uK2w@mail.gmail.com>
Subject: Re: [PATCH v2 -tip] x86/percpu: Use C for arch_raw_cpu_ptr()
To:     Uros Bizjak <ubizjak@gmail.com>
Cc:     x86@kernel.org, linux-kernel@vger.kernel.org,
        Nadav Amit <namit@vmware.com>,
        Andy Lutomirski <luto@kernel.org>,
        Brian Gerst <brgerst@gmail.com>,
        Denys Vlasenko <dvlasenk@redhat.com>,
        "H . Peter Anvin" <hpa@zytor.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Josh Poimboeuf <jpoimboe@redhat.com>
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On Tue, 10 Oct 2023 at 11:22, Uros Bizjak <ubizjak@gmail.com> wrote:
>
> Please note that besides propagation of the addition into address, the
> patch also exposes memory load to the compiler, with the anticipation
> that the compiler CSEs the load from this_cpu_off from eventual
> multiple addresses. For this to work, we have to get rid of the asms.

I actually checked that the inline asm gets combined, the same way the
this_cpu_read_stable cases do (which we use for 'current').

              Linus