[S390] switch sched_clock to store-clock-extended.

Add get_clock_xt to read an 8 byte clock value using store clock
extended (STCKE) and use get_clock_xt for sched_clock. STCKE should
be faster than STCK on newer machines.

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

2 files changed, 8 insertions, 6 deletions

diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index cb232c155360..925f9dc0b0a0 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -66,7 +66,7 @@ static u64 xtime_cc;
  */
 unsigned long long sched_clock(void)
 {
-        return ((get_clock() - jiffies_timer_cc) * 125) >> 9;
+        return ((get_clock_xt() - jiffies_timer_cc) * 125) >> 9;
 }
 
 /*
diff --git a/include/asm-s390/timex.h b/include/asm-s390/timex.h
index 98229db24314..6dd7eecbb8e4 100644
--- a/include/asm-s390/timex.h
+++ b/include/asm-s390/timex.h
@@ -62,16 +62,18 @@ static inline unsigned long long get_clock (void)
         return clk;
 }
 
-static inline void get_clock_extended(void *dest)
+static inline unsigned long long get_clock_xt(void)
 {
-        typedef struct { unsigned long long clk[2]; } __clock_t;
+        unsigned char clk[16];
 
 #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ > 2)
-        asm volatile("stcke %0" : "=Q" (*((__clock_t *)dest)) : : "cc");
+        asm volatile("stcke %0" : "=Q" (clk) : : "cc");
 #else /* __GNUC__ */
-        asm volatile("stcke 0(%1)" : "=m" (*((__clock_t *)dest))
-                                   : "a" ((__clock_t *)dest) : "cc");
+        asm volatile("stcke 0(%1)" : "=m" (clk)
+                                   : "a" (clk) : "cc");
 #endif /* __GNUC__ */
+
+        return *((unsigned long long *)&clk[1]);
 }
 
 static inline cycles_t get_cycles(void)