linux-kernel - [tip: x86/core] x86/asm: Use CLFLUSHOPT and CLWB mnemonics in <asm/special

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Message-ID: <174238220692.14745.17959838732333963549.tip-bot2@tip-bot2>
Date: Wed, 19 Mar 2025 11:03:26 -0000
From: "tip-bot2 for Uros Bizjak" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Uros Bizjak <ubizjak@...il.com>, Ingo Molnar <mingo@...nel.org>,
 Andy Lutomirski <luto@...nel.org>, Brian Gerst <brgerst@...il.com>,
 "H. Peter Anvin" <hpa@...or.com>,
 Linus Torvalds <torvalds@...ux-foundation.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: x86/core] x86/asm: Use CLFLUSHOPT and CLWB mnemonics in
 <asm/special_insns.h>

The following commit has been merged into the x86/core branch of tip:

Commit-ID:     53286632450835c49b5c177f97e4899645f15730
Gitweb:        https://git.kernel.org/tip/53286632450835c49b5c177f97e4899645f15730
Author:        Uros Bizjak <ubizjak@...il.com>
AuthorDate:    Thu, 13 Mar 2025 11:26:55 +01:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Wed, 19 Mar 2025 11:26:58 +01:00

x86/asm: Use CLFLUSHOPT and CLWB mnemonics in <asm/special_insns.h>

Current minimum required version of binutils is 2.25,
which supports CLFLUSHOPT and CLWB instruction mnemonics.

Replace the byte-wise specification of CLFLUSHOPT and
CLWB with these proper mnemonics.

No functional change intended.

Signed-off-by: Uros Bizjak <ubizjak@...il.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Brian Gerst <brgerst@...il.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Link: https://lore.kernel.org/r/20250313102715.333142-1-ubizjak@gmail.com
---
 arch/x86/include/asm/special_insns.h | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h
index 21ce480..9b10bd1 100644
--- a/arch/x86/include/asm/special_insns.h
+++ b/arch/x86/include/asm/special_insns.h
@@ -176,9 +176,8 @@ static __always_inline void clflush(volatile void *__p)

 static inline void clflushopt(volatile void *__p)
 {
-	alternative_io(".byte 0x3e; clflush %0",
-		       ".byte 0x66; clflush %0",
-		       X86_FEATURE_CLFLUSHOPT,
+	alternative_io("ds clflush %0",
+		       "clflushopt %0", X86_FEATURE_CLFLUSHOPT,
 		       "+m" (*(volatile char __force *)__p));
 }

@@ -187,13 +186,10 @@ static inline void clwb(volatile void *__p)
 	volatile struct { char x[64]; } *p = __p;

 	asm volatile(ALTERNATIVE_2(
-		".byte 0x3e; clflush (%[pax])",
-		".byte 0x66; clflush (%[pax])", /* clflushopt (%%rax) */
-		X86_FEATURE_CLFLUSHOPT,
-		".byte 0x66, 0x0f, 0xae, 0x30",  /* clwb (%%rax) */
-		X86_FEATURE_CLWB)
-		: [p] "+m" (*p)
-		: [pax] "a" (p));
+		"ds clflush %0",
+		"clflushopt %0", X86_FEATURE_CLFLUSHOPT,
+		"clwb %0", X86_FEATURE_CLWB)
+		: "+m" (*p));
 }

 #ifdef CONFIG_X86_USER_SHADOW_STACK