linux-kernel - [PATCH 2/2] x86/vdso: Use RDPID mnemonic in vdso_red

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Message-ID: <20250616095315.230620-2-ubizjak@gmail.com>
Date: Mon, 16 Jun 2025 11:52:58 +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 2/2] x86/vdso: Use RDPID mnemonic in vdso_red_cpunode()

Current minimum required version of binutils is 2.30,
which supports RDPID instruction mnemonic.

Replace the byte-wise specification of RDPID with
this proper mnemonic.

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/segment.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h
index 93fcf0daba01..f59ae7186940 100644
--- a/arch/x86/include/asm/segment.h
+++ b/arch/x86/include/asm/segment.h
@@ -255,9 +255,9 @@ static inline void vdso_read_cpunode(unsigned *cpu, unsigned *node)
 	 * If RDPID is available, use it.
 	 */
 	alternative_io ("lsl %[seg],%k[p]",
-			".byte 0xf3,0x0f,0xc7,0xf8", /* RDPID %eax/rax */
+			"rdpid %[p]",
 			X86_FEATURE_RDPID,
-			[p] "=a" (p), [seg] "r" (__CPUNODE_SEG));
+			[p] "=r" (p), [seg] "r" (__CPUNODE_SEG));
 
 	if (cpu)
 		*cpu = (p & VDSO_CPUNODE_MASK);
-- 
2.49.0