[PATCH v4 08/11] s390/percpu: Use percpu code section for this_cpu_cmpxchg128()

[Heiko Carstens <hca@linux.ibm.com>]

Convert this_cpu_cmpxchg128() to make use of percpu code section
functionality. This is just for the sake of completeness, since
currently there is no in-kernel user of this_cpu_cmpxchg128().

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
---
 arch/s390/include/asm/percpu.h | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/arch/s390/include/asm/percpu.h b/arch/s390/include/asm/percpu.h
index 78c3aaa138f7..0eae65937c0d 100644
--- a/arch/s390/include/asm/percpu.h
+++ b/arch/s390/include/asm/percpu.h
@@ -312,15 +312,23 @@ do {									\
 #define this_cpu_cmpxchg128(pcp, oval, nval)				\
 ({									\
 	typedef typeof(pcp) pcp_op_T__;					\
-	u128 old__, new__, ret__;					\
+	u128 old__ = (oval), new__ = (nval);				\
 	pcp_op_T__ *ptr__;						\
-	old__ = oval;							\
-	new__ = nval;							\
-	preempt_disable_notrace();					\
-	ptr__ = raw_cpu_ptr(&(pcp));					\
-	ret__ = cmpxchg128((void *)ptr__, old__, new__);		\
-	preempt_enable_notrace();					\
-	ret__;								\
+									\
+	ptr__ = PERCPU_PTR(&(pcp));					\
+	asm_inline volatile(						\
+		__PCPU_BEGIN("%[lcreg]","%[lcoff]","%[ptr__]")		\
+		"	cdsg	%[old__],%[new__],0(%[ptr__])\n"	\
+		__PCPU_END("%[lcreg]")					\
+		: [old__] "+&d" (old__), [ptr__] "+&a" (ptr__),		\
+		  "+m" (*ptr__),					\
+		  "=m" (((struct lowcore *)0)->percpu_register)		\
+		: [new__] "d" (new__),					\
+		  [lcreg] "i" (LC_PERCPU_REGISTER),			\
+		  [lcoff] "i" (LC_PERCPU_OFFSET),			\
+		  "m" (((struct lowcore *)0)->percpu_offset)		\
+		: "memory", "cc");					\
+	old__;								\
 })
 
 #define arch_this_cpu_xchg(pcp, nval)					\
-- 
2.53.0