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

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Message-ID: <20250414145650.10776-1-ubizjak@gmail.com>
Date: Mon, 14 Apr 2025 16:55:57 +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>
Subject: [PATCH] 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>
---
 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");
 }
 
 static __always_inline void cpu_relax(void)
-- 
2.42.0