linux-kernel - [PATCH 1/4] x86/asm: inline constant inputs in rdpkru(), wrpkru()

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Message-ID: <20250307061203.3281-1-adobriyan@gmail.com>
Date: Fri,  7 Mar 2025 09:12:00 +0300
From: Alexey Dobriyan <adobriyan@...il.com>
To: tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de,
	dave.hansen@...ux.intel.com
Cc: x86@...nel.org,
	hpa@...or.com,
	linux-kernel@...r.kernel.org,
	Alexey Dobriyan <adobriyan@...il.com>
Subject: [PATCH 1/4] x86/asm: inline constant inputs in rdpkru(), wrpkru()

Put immediate values directly into registers deleting dummy variables.

Signed-off-by: Alexey Dobriyan <adobriyan@...il.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 21ce480658b1..494a1aa19f05 100644
--- a/arch/x86/include/asm/special_insns.h
+++ b/arch/x86/include/asm/special_insns.h
@@ -79,7 +79,6 @@ void native_write_cr4(unsigned long val);
 #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
 static inline u32 rdpkru(void)
 {
-	u32 ecx = 0;
 	u32 edx, pkru;
 
 	/*
@@ -88,20 +87,18 @@ static inline u32 rdpkru(void)
 	 */
 	asm volatile(".byte 0x0f,0x01,0xee\n\t"
 		     : "=a" (pkru), "=d" (edx)
-		     : "c" (ecx));
+		     : "c" (0));
 	return pkru;
 }
 
 static inline void wrpkru(u32 pkru)
 {
-	u32 ecx = 0, edx = 0;
-
 	/*
 	 * "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));
+		     : : "a" (pkru), "c" (0), "d" (0));
 }
 
 #else
-- 
2.45.3