x86/idle: Use MONITORX and MWAITX mnemonics in <asm/mwait.h>

ubizjak · bp3tk0v · commit d20a5d96eddb · 2025-08-22T13:52:21.000+02:00
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@gmail.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/20250616083056.157460-1-ubizjak@gmail.com
diff --git 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)
@@ -80,9 +78,7 @@ static __always_inline void __mwaitx(u32 eax, u32 ebx, u32 ecx)
 {
 	/* No need for TSA buffer clearing on AMD */
 
-	/* "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));
 }
 
 /*

Original file line number	Diff line number	Diff line change
`@@ -36,9 +36,7 @@ static __always_inline void __monitor(const void *eax, u32 ecx, u32 edx)`
`36`	`36`
`37`	`37`	`static __always_inline void __monitorx(const void *eax, u32 ecx, u32 edx)`
`38`	`38`	`{`
`39`		`- /* "monitorx %eax, %ecx, %edx" */`
`40`		`- asm volatile(".byte 0x0f, 0x01, 0xfa"`
`41`		`- :: "a" (eax), "c" (ecx), "d"(edx));`
	`39`	`+ asm volatile("monitorx" :: "a" (eax), "c" (ecx), "d"(edx));`
`42`	`40`	`}`
`43`	`41`
`44`	`42`	`static __always_inline void __mwait(u32 eax, u32 ecx)`
`@@ -80,9 +78,7 @@ static __always_inline void __mwaitx(u32 eax, u32 ebx, u32 ecx)`
`80`	`78`	`{`
`81`	`79`	`/* No need for TSA buffer clearing on AMD */`
`82`	`80`
`83`		`- /* "mwaitx %eax, %ebx, %ecx" */`
`84`		`- asm volatile(".byte 0x0f, 0x01, 0xfb"`
`85`		`- :: "a" (eax), "b" (ebx), "c" (ecx));`
	`81`	`+ asm volatile("mwaitx" :: "a" (eax), "b" (ebx), "c" (ecx));`
`86`	`82`	`}`
`87`	`83`
`88`	`84`	`/*`