From: Heiko Carstens <hca@linux.ibm.com>
Date: Fri, 8 May 2026 15:02:46 +0000 (+0200)
Subject: s390/barrier: Use alternative instead of ifdef for bcr_serialize()
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a77ec04920f58dbd95a6e9e1081605f98e63c52d;p=thirdparty%2Fkernel%2Flinux.git

s390/barrier: Use alternative instead of ifdef for bcr_serialize()

Use an alternative to implement bcr_serialize() and use alternative
patching to select between serialization and fast-serialization
depending on the corresponding facility bit.

Reviewed-by: Jan Polensky <japo@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
---

diff --git a/arch/s390/include/asm/barrier.h b/arch/s390/include/asm/barrier.h
index dad02f5b3c8d3..d1e4201f38506 100644
--- a/arch/s390/include/asm/barrier.h
+++ b/arch/s390/include/asm/barrier.h
@@ -8,6 +8,7 @@
 #ifndef __ASM_BARRIER_H
 #define __ASM_BARRIER_H
 
+#include <asm/alternative.h>
 #include <asm/march.h>
 
 /*
@@ -16,16 +17,11 @@
  * to devices.
  */
 
-#ifdef MARCH_HAS_Z196_FEATURES
-/* Fast-BCR without checkpoint synchronization */
-#define __ASM_BCR_SERIALIZE "bcr 14,0"
-#else
-#define __ASM_BCR_SERIALIZE "bcr 15,0"
-#endif
-
 static __always_inline void bcr_serialize(void)
 {
-	asm volatile(__ASM_BCR_SERIALIZE : : : "memory");
+	asm_inline volatile(
+		ALTERNATIVE("bcr 15,0", "bcr 14,0", ALT_FACILITY(45))
+		: : : "memory");
 }
 
 #define __mb()		bcr_serialize()