s390/cpum_sf: Convert to cmpxchg128()

Now that there is a cross arch u128 and cmpxchg128(), use those
instead of the custom CDSG helper.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20230531132324.058821078@infradead.org

arch/s390/include/asm/cpu_mf.h

@@ -140,7 +140,7 @@ union hws_trailer_header {
 		unsigned int dsdes:16;	/* 48-63: size of diagnostic SDE */
 		unsigned long long overflow; /* 64 - Overflow Count   */
 	};
-	__uint128_t val;
+	u128 val;
 };
 
 struct hws_trailer_entry {

arch/s390/kernel/perf_cpum_sf.c

@@ -1271,16 +1271,6 @@ static void hw_collect_samples(struct perf_event *event, unsigned long *sdbt,
 	}
 }
 
-static inline __uint128_t __cdsg(__uint128_t *ptr, __uint128_t old, __uint128_t new)
-{
-	asm volatile(
-		"	cdsg	%[old],%[new],%[ptr]\n"
-		: [old] "+d" (old), [ptr] "+QS" (*ptr)
-		: [new] "d" (new)
-		: "memory", "cc");
-	return old;
-}
-
 /* hw_perf_event_update() - Process sampling buffer
  * @event:	The perf event
  * @flush_all:	Flag to also flush partially filled sample-data-blocks
@@ -1352,7 +1342,7 @@ static void hw_perf_event_update(struct perf_event *event, int flush_all)
 			new.f = 0;
 			new.a = 1;
 			new.overflow = 0;
-			prev.val = __cdsg(&te->header.val, old.val, new.val);
+			prev.val = cmpxchg128(&te->header.val, old.val, new.val);
 		} while (prev.val != old.val);
 
 		/* Advance to next sample-data-block */
@@ -1562,7 +1552,7 @@ static bool aux_set_alert(struct aux_buffer *aux, unsigned long alert_index,
 		}
 		new.a = 1;
 		new.overflow = 0;
-		prev.val = __cdsg(&te->header.val, old.val, new.val);
+		prev.val = cmpxchg128(&te->header.val, old.val, new.val);
 	} while (prev.val != old.val);
 	return true;
 }
@@ -1636,7 +1626,7 @@ static bool aux_reset_buffer(struct aux_buffer *aux, unsigned long range,
 				new.a = 1;
 			else
 				new.a = 0;
-			prev.val = __cdsg(&te->header.val, old.val, new.val);
+			prev.val = cmpxchg128(&te->header.val, old.val, new.val);
 		} while (prev.val != old.val);
 		*overflow += orig_overflow;
 	}