linux-kernel - [PATCH v2 2/2] um/asm: Replace "REP; NOP" with PAUSE mnemonic

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Message-ID: <20250418083436.133148-2-ubizjak@gmail.com>
Date: Fri, 18 Apr 2025 10:33:59 +0200
From: Uros Bizjak <ubizjak@...il.com>
To: linux-um@...ts.infradead.org,
	x86@...nel.org,
	linux-kernel@...r.kernel.org
Cc: Uros Bizjak <ubizjak@...il.com>,
	Richard Weinberger <richard@....at>,
	Anton Ivanov <anton.ivanov@...bridgegreys.com>,
	Johannes Berg <johannes@...solutions.net>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	David Laight <david.laight.linux@...il.com>
Subject: [PATCH v2 2/2] um/asm: Replace "REP; NOP" with PAUSE mnemonic

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@...il.com>
Cc: Richard Weinberger <richard@....at>
Cc: Anton Ivanov <anton.ivanov@...bridgegreys.com>
Cc: Johannes Berg <johannes@...solutions.net>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: David Laight <david.laight.linux@...il.com>
---
v2: Rename rep_nop() to native_pause() first.
---
 arch/x86/um/asm/processor.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/um/asm/processor.h b/arch/x86/um/asm/processor.h
index d50549e0089c..e222d2ae28fd 100644
--- a/arch/x86/um/asm/processor.h
+++ b/arch/x86/um/asm/processor.h
@@ -21,10 +21,10 @@
 
 #include <asm/user.h>
 
-/* REP NOP (PAUSE) is a good thing to insert into busy-wait loops. */
+/* PAUSE is a good thing to insert into busy-wait loops. */
 static __always_inline void native_pause(void)
 {
-	__asm__ __volatile__("rep;nop": : :"memory");
+	__asm__ __volatile__("pause": : :"memory");
 }
 
 static __always_inline void cpu_relax(void)
-- 
2.49.0