[S390] cmpxchg: implement cmpxchg64()

We have a cmpxchg64_local() implementation but strange enough the
SMP capable variant cmpxchg64() is missing. So implement it.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 29 insertions, 9 deletions

diff --git a/arch/s390/include/asm/cmpxchg.h b/arch/s390/include/asm/cmpxchg.h
index 4052df9030cb..7488e52efa97 100644
--- a/arch/s390/include/asm/cmpxchg.h
+++ b/arch/s390/include/asm/cmpxchg.h
@@ -164,6 +164,33 @@ static inline unsigned long __cmpxchg(void *ptr, unsigned long old,
         ((__typeof__(*(ptr)))__cmpxchg((ptr), (unsigned long)(o),       \
                                        (unsigned long)(n), sizeof(*(ptr))))
 
+#ifdef CONFIG_64BIT
+#define cmpxchg64(ptr, o, n)                                            \
+({                                                                      \
+        BUILD_BUG_ON(sizeof(*(ptr)) != 8);                              \
+        cmpxchg((ptr), (o), (n));                                       \
+})
+#else /* CONFIG_64BIT */
+static inline unsigned long long __cmpxchg64(void *ptr,
+                                             unsigned long long old,
+                                             unsigned long long new)
+{
+        register_pair rp_old = {.pair = old};
+        register_pair rp_new = {.pair = new};
+
+        asm volatile(
+                "       cds     %0,%2,%1"
+                : "+&d" (rp_old), "=Q" (ptr)
+                : "d" (rp_new), "Q" (ptr)
+                : "cc");
+        return rp_old.pair;
+}
+#define cmpxchg64(ptr, o, n)                                            \
+        ((__typeof__(*(ptr)))__cmpxchg64((ptr),                         \
+                                         (unsigned long long)(o),       \
+                                         (unsigned long long)(n)))
+#endif /* CONFIG_64BIT */
+
 #include <asm-generic/cmpxchg-local.h>
 
 static inline unsigned long __cmpxchg_local(void *ptr,
@@ -192,14 +219,7 @@ static inline unsigned long __cmpxchg_local(void *ptr,
 #define cmpxchg_local(ptr, o, n)                                        \
         ((__typeof__(*(ptr)))__cmpxchg_local((ptr), (unsigned long)(o), \
                         (unsigned long)(n), sizeof(*(ptr))))
-#ifdef CONFIG_64BIT
-#define cmpxchg64_local(ptr, o, n)                                      \
-({                                                                      \
-        BUILD_BUG_ON(sizeof(*(ptr)) != 8);                              \
-        cmpxchg_local((ptr), (o), (n));                                 \
-})
-#else
-#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
-#endif
+
+#define cmpxchg64_local(ptr, o, n)      cmpxchg64((ptr), (o), (n))
 
 #endif /* __ASM_CMPXCHG_H */