linux-kernel - [PATCH] x86/idle: Use MONITORX and MWAITX mnemonics in <asm/mwait.h>

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Message-ID: <20250616083056.157460-1-ubizjak@gmail.com>
Date: Mon, 16 Jun 2025 10:30:41 +0200
From: Uros Bizjak <ubizjak@...il.com>
To: x86@...nel.ort,
	linux-kernel@...r.kernel.org
Cc: Uros Bizjak <ubizjak@...il.com>,
	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] x86/idle: Use MONITORX and MWAITX mnemonics in <asm/mwait.h>

Current minimum required version of binutils is 2.30,
which supports MONITORX and MWAITX instruction mnemonics.

Replace the byte-wise specification of MONITORX and
MWAITX with these proper mnemonics.

No functional change intended.

Signed-off-by: Uros Bizjak <ubizjak@...il.com>
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/include/asm/mwait.h | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/mwait.h b/arch/x86/include/asm/mwait.h
index dd2b129b0418..d4bcbe59626d 100644
--- a/arch/x86/include/asm/mwait.h
+++ b/arch/x86/include/asm/mwait.h
@@ -36,9 +36,7 @@ static __always_inline void __monitor(const void *eax, u32 ecx, u32 edx)
 
 static __always_inline void __monitorx(const void *eax, u32 ecx, u32 edx)
 {
-	/* "monitorx %eax, %ecx, %edx" */
-	asm volatile(".byte 0x0f, 0x01, 0xfa"
-		     :: "a" (eax), "c" (ecx), "d"(edx));
+	asm volatile("monitorx" :: "a" (eax), "c" (ecx), "d"(edx));
 }
 
 static __always_inline void __mwait(u32 eax, u32 ecx)
@@ -82,9 +80,7 @@ static __always_inline void __mwaitx(u32 eax, u32 ebx, u32 ecx)
 {
 	/* No MDS buffer clear as this is AMD/HYGON only */
 
-	/* "mwaitx %eax, %ebx, %ecx" */
-	asm volatile(".byte 0x0f, 0x01, 0xfb"
-		     :: "a" (eax), "b" (ebx), "c" (ecx));
+	asm volatile("mwaitx" :: "a" (eax), "b" (ebx), "c" (ecx));
 }
 
 /*
-- 
2.49.0