[S390] introduce vdso on s390

Add a vdso to speed up gettimeofday and clock_getres/clock_gettime for
CLOCK_REALTIME/CLOCK_MONOTONIC.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index eccefbbff887..b73bbf31f432 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -36,6 +36,7 @@
 #include <asm/delay.h>
 #include <asm/s390_ext.h>
 #include <asm/div64.h>
+#include <asm/vdso.h>
 #include <asm/irq.h>
 #include <asm/irq_regs.h>
 #include <asm/timer.h>
@@ -223,6 +224,36 @@ static struct clocksource clocksource_tod = {
 };
 
 
+void update_vsyscall(struct timespec *wall_time, struct clocksource *clock)
+{
+        if (clock != &clocksource_tod)
+                return;
+
+        /* Make userspace gettimeofday spin until we're done. */
+        ++vdso_data->tb_update_count;
+        smp_wmb();
+        vdso_data->xtime_tod_stamp = clock->cycle_last;
+        vdso_data->xtime_clock_sec = xtime.tv_sec;
+        vdso_data->xtime_clock_nsec = xtime.tv_nsec;
+        vdso_data->wtom_clock_sec = wall_to_monotonic.tv_sec;
+        vdso_data->wtom_clock_nsec = wall_to_monotonic.tv_nsec;
+        smp_wmb();
+        ++vdso_data->tb_update_count;
+}
+
+extern struct timezone sys_tz;
+
+void update_vsyscall_tz(void)
+{
+        /* Make userspace gettimeofday spin until we're done. */
+        ++vdso_data->tb_update_count;
+        smp_wmb();
+        vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
+        vdso_data->tz_dsttime = sys_tz.tz_dsttime;
+        smp_wmb();
+        ++vdso_data->tb_update_count;
+}
+
 /*
  * Initialize the TOD clock and the CPU timer of
  * the boot cpu.