s390: add KCSAN instrumentation to barriers and spinlocks

test_barrier fails on s390 because of the missing KCSAN instrumentation
for several synchronization primitives.

Add it to barriers by defining __mb(), __rmb(), __wmb(), __dma_rmb()
and __dma_wmb(), and letting the common code in asm-generic/barrier.h
do the rest.

Spinlocks require instrumentation only on the unlock path; notify KCSAN
that the CPU cannot move memory accesses outside of the spin lock. In
reality it also cannot move stores inside of it, but this is not
important and can be omitted.

Reported-by: Tobias Huschle <huschle@linux.ibm.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

arch/s390/include/asm/barrier.h

@@ -26,14 +26,14 @@ static __always_inline void bcr_serialize(void)
 	asm volatile(__ASM_BCR_SERIALIZE : : : "memory");
 }
 
-#define mb()		bcr_serialize()
-#define rmb()		barrier()
-#define wmb()		barrier()
-#define dma_rmb()	mb()
-#define dma_wmb()	mb()
-#define __smp_mb()	mb()
-#define __smp_rmb()	rmb()
-#define __smp_wmb()	wmb()
+#define __mb()		bcr_serialize()
+#define __rmb()		barrier()
+#define __wmb()		barrier()
+#define __dma_rmb()	__mb()
+#define __dma_wmb()	__mb()
+#define __smp_mb()	__mb()
+#define __smp_rmb()	__rmb()
+#define __smp_wmb()	__wmb()
 
 #define __smp_store_release(p, v)					\
 do {									\

arch/s390/include/asm/spinlock.h

@@ -77,6 +77,7 @@ static inline int arch_spin_trylock(arch_spinlock_t *lp)
 static inline void arch_spin_unlock(arch_spinlock_t *lp)
 {
 	typecheck(int, lp->lock);
+	kcsan_release();
 	asm_inline volatile(
 		ALTERNATIVE("", ".insn rre,0xb2fa0000,7,0", 49)	/* NIAI 7 */
 		"	sth	%1,%0\n"