linux-kernel - [PATCH] x86/asm: Use RDPKRU and WRPKRU mnemonics in <asm/special

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Message-ID: <20250616083611.157740-1-ubizjak@gmail.com>
Date: Mon, 16 Jun 2025 10:35:57 +0200
From: Uros Bizjak <ubizjak@...il.com>
To: x86@...nel.org,
	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/asm: Use RDPKRU and WRPKRU mnemonics in <asm/special_insns.h>

Current minimum required version of binutils is 2.30,
which supports RDPKRU and WRPKRU instruction mnemonics.

Replace the byte-wise specification of RDPKRU and
WRPKRU 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/special_insns.h | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h
index ecda17efa042..13e272e1a53f 100644
--- a/arch/x86/include/asm/special_insns.h
+++ b/arch/x86/include/asm/special_insns.h
@@ -75,9 +75,7 @@ static inline u32 rdpkru(void)
 	 * "rdpkru" instruction.  Places PKRU contents in to EAX,
 	 * clears EDX and requires that ecx=0.
 	 */
-	asm volatile(".byte 0x0f,0x01,0xee\n\t"
-		     : "=a" (pkru), "=d" (edx)
-		     : "c" (ecx));
+	asm volatile("rdpkru" : "=a" (pkru), "=d" (edx) : "c" (ecx));
 	return pkru;
 }
 
@@ -89,8 +87,7 @@ static inline void wrpkru(u32 pkru)
 	 * "wrpkru" instruction.  Loads contents in EAX to PKRU,
 	 * requires that ecx = edx = 0.
 	 */
-	asm volatile(".byte 0x0f,0x01,0xef\n\t"
-		     : : "a" (pkru), "c"(ecx), "d"(edx));
+	asm volatile("wrpkru" : : "a" (pkru), "c"(ecx), "d"(edx));
 }
 
 #else
-- 
2.49.0