6 files changed, 98 insertions, 3 deletions

diff --git a/arch/x86/include/asm/vgtod.h b/arch/x86/include/asm/vgtod.h
index dc27a69e5d2a..3d61e204826f 100644
--- a/arch/x86/include/asm/vgtod.h
+++ b/arch/x86/include/asm/vgtod.h
@@ -21,6 +21,7 @@ struct vsyscall_gtod_data {
                 u32     shift;
         } clock;
         struct timespec wall_to_monotonic;
+        struct timespec wall_time_coarse;
 };
 extern struct vsyscall_gtod_data __vsyscall_gtod_data
 __section_vsyscall_gtod_data;
diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c
index 25ee06a80aad..cf53a78e2dcf 100644
--- a/arch/x86/kernel/vsyscall_64.c
+++ b/arch/x86/kernel/vsyscall_64.c
@@ -87,6 +87,7 @@ void update_vsyscall(struct timespec *wall_time, struct clocksource *clock)
         vsyscall_gtod_data.wall_time_sec = wall_time->tv_sec;
         vsyscall_gtod_data.wall_time_nsec = wall_time->tv_nsec;
         vsyscall_gtod_data.wall_to_monotonic = wall_to_monotonic;
+        vsyscall_gtod_data.wall_time_coarse = __current_kernel_time();
         write_sequnlock_irqrestore(&vsyscall_gtod_data.lock, flags);
 }
 
diff --git a/arch/x86/vdso/vclock_gettime.c b/arch/x86/vdso/vclock_gettime.c
index 6a40b78b46aa..ee55754cc3c5 100644
--- a/arch/x86/vdso/vclock_gettime.c
+++ b/arch/x86/vdso/vclock_gettime.c
@@ -86,14 +86,47 @@ notrace static noinline int do_monotonic(struct timespec *ts)
         return 0;
 }
 
+notrace static noinline int do_realtime_coarse(struct timespec *ts)
+{
+        unsigned long seq;
+        do {
+                seq = read_seqbegin(&gtod->lock);
+                ts->tv_sec = gtod->wall_time_coarse.tv_sec;
+                ts->tv_nsec = gtod->wall_time_coarse.tv_nsec;
+        } while (unlikely(read_seqretry(&gtod->lock, seq)));
+        return 0;
+}
+
+notrace static noinline int do_monotonic_coarse(struct timespec *ts)
+{
+        unsigned long seq, ns, secs;
+        do {
+                seq = read_seqbegin(&gtod->lock);
+                secs = gtod->wall_time_coarse.tv_sec;
+                ns = gtod->wall_time_coarse.tv_nsec;
+                secs += gtod->wall_to_monotonic.tv_sec;
+                ns += gtod->wall_to_monotonic.tv_nsec;
+        } while (unlikely(read_seqretry(&gtod->lock, seq)));
+        vset_normalized_timespec(ts, secs, ns);
+        return 0;
+}
+
 notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
 {
-        if (likely(gtod->sysctl_enabled && gtod->clock.vread))
+        if (likely(gtod->sysctl_enabled))
                 switch (clock) {
                 case CLOCK_REALTIME:
-                        return do_realtime(ts);
+                        if (likely(gtod->clock.vread))
+                                return do_realtime(ts);
+                        break;
                 case CLOCK_MONOTONIC:
-                        return do_monotonic(ts);
+                        if (likely(gtod->clock.vread))
+                                return do_monotonic(ts);
+                        break;
+                case CLOCK_REALTIME_COARSE:
+                        return do_realtime_coarse(ts);
+                case CLOCK_MONOTONIC_COARSE:
+                        return do_monotonic_coarse(ts);
                 }
         return vdso_fallback_gettime(clock, ts);
 }
diff --git a/include/linux/time.h b/include/linux/time.h
index f505988398e6..256232f7e5e6 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -110,6 +110,8 @@ extern int timekeeping_suspended;
 
 unsigned long get_seconds(void);
 struct timespec current_kernel_time(void);
+struct timespec __current_kernel_time(void); /* does not hold xtime_lock */
+struct timespec get_monotonic_coarse(void);
 
 #define CURRENT_TIME            (current_kernel_time())
 #define CURRENT_TIME_SEC        ((struct timespec) { get_seconds(), 0 })
@@ -243,6 +245,8 @@ struct itimerval {
 #define CLOCK_PROCESS_CPUTIME_ID        2
 #define CLOCK_THREAD_CPUTIME_ID         3
 #define CLOCK_MONOTONIC_RAW             4
+#define CLOCK_REALTIME_COARSE           5
+#define CLOCK_MONOTONIC_COARSE          6
 
 /*
  * The IDs of various hardware clocks:
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index d089d052c4a9..495440779ce3 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -242,6 +242,25 @@ static int posix_get_monotonic_raw(clockid_t which_clock, struct timespec *tp)
         return 0;
 }
 
+
+static int posix_get_realtime_coarse(clockid_t which_clock, struct timespec *tp)
+{
+        *tp = current_kernel_time();
+        return 0;
+}
+
+static int posix_get_monotonic_coarse(clockid_t which_clock,
+                                                struct timespec *tp)
+{
+        *tp = get_monotonic_coarse();
+        return 0;
+}
+
+int posix_get_coarse_res(const clockid_t which_clock, struct timespec *tp)
+{
+        *tp = ktime_to_timespec(KTIME_LOW_RES);
+        return 0;
+}
 /*
  * Initialize everything, well, just everything in Posix clocks/timers ;)
  */
@@ -262,10 +281,26 @@ static __init int init_posix_timers(void)
                 .timer_create = no_timer_create,
                 .nsleep = no_nsleep,
         };
+        struct k_clock clock_realtime_coarse = {
+                .clock_getres = posix_get_coarse_res,
+                .clock_get = posix_get_realtime_coarse,
+                .clock_set = do_posix_clock_nosettime,
+                .timer_create = no_timer_create,
+                .nsleep = no_nsleep,
+        };
+        struct k_clock clock_monotonic_coarse = {
+                .clock_getres = posix_get_coarse_res,
+                .clock_get = posix_get_monotonic_coarse,
+                .clock_set = do_posix_clock_nosettime,
+                .timer_create = no_timer_create,
+                .nsleep = no_nsleep,
+        };
 
         register_posix_clock(CLOCK_REALTIME, &clock_realtime);
         register_posix_clock(CLOCK_MONOTONIC, &clock_monotonic);
         register_posix_clock(CLOCK_MONOTONIC_RAW, &clock_monotonic_raw);
+        register_posix_clock(CLOCK_REALTIME_COARSE, &clock_realtime_coarse);
+        register_posix_clock(CLOCK_MONOTONIC_COARSE, &clock_monotonic_coarse);
 
         posix_timers_cache = kmem_cache_create("posix_timers_cache",
                                         sizeof (struct k_itimer), 0, SLAB_PANIC,
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 15e06defca55..03cbeb34d141 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -847,6 +847,10 @@ unsigned long get_seconds(void)
 }
 EXPORT_SYMBOL(get_seconds);
 
+struct timespec __current_kernel_time(void)
+{
+        return xtime_cache;
+}
 
 struct timespec current_kernel_time(void)
 {
@@ -862,3 +866,20 @@ struct timespec current_kernel_time(void)
         return now;
 }
 EXPORT_SYMBOL(current_kernel_time);
+
+struct timespec get_monotonic_coarse(void)
+{
+        struct timespec now, mono;
+        unsigned long seq;
+
+        do {
+                seq = read_seqbegin(&xtime_lock);
+
+                now = xtime_cache;
+                mono = wall_to_monotonic;
+        } while (read_seqretry(&xtime_lock, seq));
+
+        set_normalized_timespec(&now, now.tv_sec + mono.tv_sec,
+                                now.tv_nsec + mono.tv_nsec);
+        return now;
+}