uml: virtualized time fix

With the current timekeeping, !CONFIG_UML_REAL_TIME_CLOCK has
inconsistent behavior.  Previously, gettimeofday could be (and was)
isolated from the clock ticking.  Now, it's not, so when
CONFIG_UML_REAL_TIME_CLOCK is disabled, gettimeofday must progress in
lockstep with the clock, making it fully virtual.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 12 insertions, 2 deletions

diff --git a/arch/um/kernel/time.c b/arch/um/kernel/time.c
index 9fd80ee3eef6..cd7349de8ca6 100644
--- a/arch/um/kernel/time.c
+++ b/arch/um/kernel/time.c
@@ -34,8 +34,8 @@ unsigned long long sched_clock(void)
         return (unsigned long long)jiffies_64 * (1000000000 / HZ);
 }
 
-static unsigned long long prev_nsecs[NR_CPUS];
 #ifdef CONFIG_UML_REAL_TIME_CLOCK
+static unsigned long long prev_nsecs[NR_CPUS];
 static long long delta[NR_CPUS];                /* Deviation per interval */
 #endif
 
@@ -94,7 +94,12 @@ irqreturn_t um_timer(int irq, void *dev)
 
         do_timer(1);
 
+#ifdef CONFIG_UML_REAL_TIME_CLOCK
         nsecs = get_time();
+#else
+        nsecs = (unsigned long long) xtime.tv_sec * BILLION + xtime.tv_nsec +
+                BILLION / HZ;
+#endif
         xtime.tv_sec = nsecs / NSEC_PER_SEC;
         xtime.tv_nsec = nsecs - xtime.tv_sec * NSEC_PER_SEC;
 
@@ -127,13 +132,18 @@ void time_init(void)
         nsecs = os_nsecs();
         set_normalized_timespec(&wall_to_monotonic, -nsecs / BILLION,
                                 -nsecs % BILLION);
+        set_normalized_timespec(&xtime, nsecs / BILLION, nsecs % BILLION);
         late_time_init = register_timer;
 }
 
 void do_gettimeofday(struct timeval *tv)
 {
+#ifdef CONFIG_UML_REAL_TIME_CLOCK
         unsigned long long nsecs = get_time();
-
+#else
+        unsigned long long nsecs = (unsigned long long) xtime.tv_sec * BILLION +
+                xtime.tv_nsec;
+#endif
         tv->tv_sec = nsecs / NSEC_PER_SEC;
         /* Careful about calculations here - this was originally done as
          * (nsecs - tv->tv_sec * NSEC_PER_SEC) / NSEC_PER_USEC