aboutsummaryrefslogtreecommitdiff
path: root/arch/um/os-Linux/time.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/um/os-Linux/time.c')
-rw-r--r--arch/um/os-Linux/time.c61
1 files changed, 57 insertions, 4 deletions
diff --git a/arch/um/os-Linux/time.c b/arch/um/os-Linux/time.c
index e4928059946..dec5678fc17 100644
--- a/arch/um/os-Linux/time.c
+++ b/arch/um/os-Linux/time.c
@@ -9,7 +9,9 @@
#include <time.h>
#include <sys/time.h>
#include "kern_constants.h"
+#include "kern_util.h"
#include "os.h"
+#include "process.h"
#include "user.h"
int set_interval(void)
@@ -58,12 +60,17 @@ static inline long long timeval_to_ns(const struct timeval *tv)
long long disable_timer(void)
{
struct itimerval time = ((struct itimerval) { { 0, 0 }, { 0, 0 } });
+ int remain, max = UM_NSEC_PER_SEC / UM_HZ;
if (setitimer(ITIMER_VIRTUAL, &time, &time) < 0)
printk(UM_KERN_ERR "disable_timer - setitimer failed, "
"errno = %d\n", errno);
- return timeval_to_ns(&time.it_value);
+ remain = timeval_to_ns(&time.it_value);
+ if (remain > max)
+ remain = max;
+
+ return remain;
}
long long os_nsecs(void)
@@ -79,7 +86,48 @@ static int after_sleep_interval(struct timespec *ts)
{
return 0;
}
+
+static void deliver_alarm(void)
+{
+ alarm_handler(SIGVTALRM, NULL);
+}
+
+static unsigned long long sleep_time(unsigned long long nsecs)
+{
+ return nsecs;
+}
+
#else
+unsigned long long last_tick;
+unsigned long long skew;
+
+static void deliver_alarm(void)
+{
+ unsigned long long this_tick = os_nsecs();
+ int one_tick = UM_NSEC_PER_SEC / UM_HZ;
+
+ /* Protection against the host's time going backwards */
+ if ((last_tick != 0) && (this_tick < last_tick))
+ this_tick = last_tick;
+
+ if (last_tick == 0)
+ last_tick = this_tick - one_tick;
+
+ skew += this_tick - last_tick;
+
+ while (skew >= one_tick) {
+ alarm_handler(SIGVTALRM, NULL);
+ skew -= one_tick;
+ }
+
+ last_tick = this_tick;
+}
+
+static unsigned long long sleep_time(unsigned long long nsecs)
+{
+ return nsecs > skew ? nsecs - skew : 0;
+}
+
static inline long long timespec_to_us(const struct timespec *ts)
{
return ((long long) ts->tv_sec * UM_USEC_PER_SEC) +
@@ -102,6 +150,11 @@ static int after_sleep_interval(struct timespec *ts)
*/
if (start_usecs > usec)
start_usecs = usec;
+
+ start_usecs -= skew / UM_NSEC_PER_USEC;
+ if (start_usecs < 0)
+ start_usecs = 0;
+
tv = ((struct timeval) { .tv_sec = start_usecs / UM_USEC_PER_SEC,
.tv_usec = start_usecs % UM_USEC_PER_SEC });
interval = ((struct itimerval) { { 0, usec }, tv });
@@ -113,8 +166,6 @@ static int after_sleep_interval(struct timespec *ts)
}
#endif
-extern void alarm_handler(int sig, struct sigcontext *sc);
-
void idle_sleep(unsigned long long nsecs)
{
struct timespec ts;
@@ -126,10 +177,12 @@ void idle_sleep(unsigned long long nsecs)
*/
if (nsecs == 0)
nsecs = UM_NSEC_PER_SEC / UM_HZ;
+
+ nsecs = sleep_time(nsecs);
ts = ((struct timespec) { .tv_sec = nsecs / UM_NSEC_PER_SEC,
.tv_nsec = nsecs % UM_NSEC_PER_SEC });
if (nanosleep(&ts, &ts) == 0)
- alarm_handler(SIGVTALRM, NULL);
+ deliver_alarm();
after_sleep_interval(&ts);
}