linux-kernel - [PATCH -v2 14/15] x86/percpu: Remove !CONFIG_X86

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Message-ID: <aA3g8BVjYUiBuAT6@gmail.com>
Date: Sun, 27 Apr 2025 09:46:56 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Uros Bizjak <ubizjak@...il.com>
Cc: linux-kernel@...r.kernel.org, "Ahmed S . Darwish" <darwi@...utronix.de>,
	Andrew Cooper <andrew.cooper3@...rix.com>,
	Ard Biesheuvel <ardb@...nel.org>, Arnd Bergmann <arnd@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H . Peter Anvin" <hpa@...or.com>,
	John Ogness <john.ogness@...utronix.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH -v2 14/15] x86/percpu: Remove !CONFIG_X86_CX8 methods


* Uros Bizjak <ubizjak@...il.com> wrote:

> Please see the attached patch that implements the change.

Thanks! I've turned this into a commit with your SOB, replacing my 
placeholder patch, see below.

	Ingo

===================================>
From: Uros Bizjak <ubizjak@...il.com>
Date: Fri, 25 Apr 2025 16:05:14 +0200
Subject: [PATCH] x86/percpu: Remove !CONFIG_X86_CX8 methods

Adjust the constraints to the non-alternatives asm() statement.

Signed-off-by: Uros Bizjak <ubizjak@...il.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
https://lore.kernel.org/r/15696bb3-126b-ef71-f838-80e1e1c1b0aa@gmail.com
---
 arch/x86/include/asm/percpu.h | 24 +++++++++---------------
 1 file changed, 9 insertions(+), 15 deletions(-)

diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index 5fe314a2e73e..bef13b358f7b 100644
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -333,13 +333,10 @@ do {									\
 	old__.var = _oval;						\
 	new__.var = _nval;						\
 									\
-	asm_inline qual (						\
-		ALTERNATIVE("call this_cpu_cmpxchg8b_emu",		\
-			    "cmpxchg8b " __percpu_arg([var]), X86_FEATURE_CX8) \
-		: ALT_OUTPUT_SP([var] "+m" (__my_cpu_var(_var)),	\
-				"+a" (old__.low), "+d" (old__.high))	\
-		: "b" (new__.low), "c" (new__.high),			\
-		  "S" (&(_var))						\
+	asm qual ("cmpxchg8b " __percpu_arg([var])			\
+		: "+m" (__my_cpu_var(_var)),				\
+		  "+a" (old__.low), "+d" (old__.high)			\
+		: "b" (new__.low), "c" (new__.high)			\
 		: "memory");						\
 									\
 	old__.var;							\
@@ -362,15 +359,12 @@ do {									\
 	old__.var = *_oval;						\
 	new__.var = _nval;						\
 									\
-	asm_inline qual (						\
-		ALTERNATIVE("call this_cpu_cmpxchg8b_emu",		\
-			    "cmpxchg8b " __percpu_arg([var]), X86_FEATURE_CX8) \
+	asm qual ("cmpxchg8b " __percpu_arg([var])			\
 		CC_SET(z)						\
-		: ALT_OUTPUT_SP(CC_OUT(z) (success),			\
-				[var] "+m" (__my_cpu_var(_var)),	\
-				"+a" (old__.low), "+d" (old__.high))	\
-		: "b" (new__.low), "c" (new__.high),			\
-		  "S" (&(_var))						\
+		: CC_OUT(z) (success),					\
+		  [var] "+m" (__my_cpu_var(_var)),			\
+		  "+a" (old__.low), "+d" (old__.high)			\
+		: "b" (new__.low), "c" (new__.high)			\
 		: "memory");						\
 	if (unlikely(!success))						\
 		*_oval = old__.var;					\