[PATCH 1/2] powerpc/locking: implement this_cpu_cmpxchg local API

[Luming Yu]

ppc appears to have already supported cmpxchg-local atomic semantics
that is defined by the kernel convention of the feature.
Add this_cpu_cmpxchg ppc local for the performance benefit of arch
sepcific implementation than asm-generic c verison of the locking API.

Signed-off-by: Luming Yu <luming.yu at shingroup.cn>
---
 arch/powerpc/include/asm/percpu.h | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/arch/powerpc/include/asm/percpu.h b/arch/powerpc/include/asm/percpu.h
index 8e5b7d0b851c..ceab5df6e7ab 100644
--- a/arch/powerpc/include/asm/percpu.h
+++ b/arch/powerpc/include/asm/percpu.h
@@ -18,5 +18,22 @@
 #include <asm-generic/percpu.h>
 
 #include <asm/paca.h>
+#include <asm/cmpxchg.h>
+#ifdef this_cpu_cmpxchg_1
+#undef this_cpu_cmpxchg_1
+#define this_cpu_cmpxchg_1(pcp, oval, nval)	__cmpxchg_local(raw_cpu_ptr(&(pcp)), oval, nval, 1)
+#endif 
+#ifdef this_cpu_cmpxchg_2
+#undef this_cpu_cmpxchg_2
+#define this_cpu_cmpxchg_2(pcp, oval, nval)	__cmpxchg_local(raw_cpu_ptr(&(pcp)), oval, nval, 2)
+#endif
+#ifdef this_cpu_cmpxchg_4
+#undef this_cpu_cmpxchg_4
+#define this_cpu_cmpxchg_4(pcp, oval, nval)	__cmpxchg_local(raw_cpu_ptr(&(pcp)), oval, nval, 4)
+#endif
+#ifdef this_cpu_cmpxchg_8
+#undef this_cpu_cmpxchg_8
+#define this_cpu_cmpxchg_8(pcp, oval, nval)	__cmpxchg_local(raw_cpu_ptr(&(pcp)), oval, nval, 8)
+#endif
 
 #endif /* _ASM_POWERPC_PERCPU_H_ */
-- 
2.42.0.windows.2