linux-kernel - [PATCH] x86/asm: Use alternative_input() in amd_clear

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Message-ID: <20250314081453.565859-1-ubizjak@gmail.com>
Date: Fri, 14 Mar 2025 09:14:38 +0100
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 alternative_input() in amd_clear_divider()

Use higher-level API to declare assembly with alternatives.

bloat-o-meter reports no code size changes.

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/processor.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 5d2f7e5aff26..b4b5aa46f68b 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -707,8 +707,9 @@ static inline u32 per_cpu_l2c_id(unsigned int cpu)
  */
 static __always_inline void amd_clear_divider(void)
 {
-	asm volatile(ALTERNATIVE("", "div %2\n\t", X86_BUG_DIV0)
-		     :: "a" (0), "d" (0), "r" (1));
+	alternative_input("", "div %[den]",
+			  X86_BUG_DIV0,
+			  "a" (0), "d" (0), [den] "r" (1));
 }
 
 extern void amd_check_microcode(void);
-- 
2.48.1