From: Uros Bizjak <ubizjak@gmail.com>
To: David Laight <david.laight.linux@gmail.com>
Cc: linux-um@lists.infradead.org, x86@kernel.org,
linux-kernel@vger.kernel.org,
Richard Weinberger <richard@nod.at>,
Anton Ivanov <anton.ivanov@cambridgegreys.com>,
Johannes Berg <johannes@sipsolutions.net>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH] um/asm: Replace "REP; NOP" with PAUSE mnemonic
Date: Wed, 16 Apr 2025 07:53:56 +0200 [thread overview]
Message-ID: <CAFULd4YV0yKTULPM-+Y0b72EJ48tqfW_ni8RjHsQTULT8TGaTQ@mail.gmail.com> (raw)
In-Reply-To: <20250415185558.112621df@pumpkin>
On Tue, Apr 15, 2025 at 7:56 PM David Laight
<david.laight.linux@gmail.com> wrote:
>
> On Mon, 14 Apr 2025 16:55:57 +0200
> Uros Bizjak <ubizjak@gmail.com> wrote:
>
> > Current minimum required version of binutils is 2.25,
> > which supports PAUSE instruction mnemonic.
> >
> > Replace "REP; NOP" with this proper mnemonic.
> >
> > No functional change intended.
> >
> > Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
> > Cc: Richard Weinberger <richard@nod.at>
> > Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
> > Cc: Johannes Berg <johannes@sipsolutions.net>
> > Cc: Thomas Gleixner <tglx@linutronix.de>
> > Cc: Ingo Molnar <mingo@kernel.org>
> > Cc: Borislav Petkov <bp@alien8.de>
> > Cc: Dave Hansen <dave.hansen@linux.intel.com>
> > Cc: "H. Peter Anvin" <hpa@zytor.com>
> > ---
> > arch/x86/um/asm/processor.h | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/um/asm/processor.h b/arch/x86/um/asm/processor.h
> > index 478710384b34..233a7a0d29c9 100644
> > --- a/arch/x86/um/asm/processor.h
> > +++ b/arch/x86/um/asm/processor.h
> > @@ -24,7 +24,7 @@
> > /* REP NOP (PAUSE) is a good thing to insert into busy-wait loops. */
> > static __always_inline void rep_nop(void)
> > {
> > - __asm__ __volatile__("rep;nop": : :"memory");
> > + __asm__ __volatile__("pause": : :"memory");
> > }
> >
>
> That only makes sense if you also change the function name.
This function is used in several places, and is also defined for x86
in arch/x86/include/asm/vdso/processor.h. The renaming should be
coordinated with x86 and should definitely be a separate patch.
Uros.
next prev parent reply other threads:[~2025-04-16 5:54 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-14 14:55 [PATCH] um/asm: Replace "REP; NOP" with PAUSE mnemonic Uros Bizjak
2025-04-15 17:55 ` David Laight
2025-04-16 5:53 ` Uros Bizjak [this message]
2025-04-16 6:57 ` Uros Bizjak
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