3 files changed, 38 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);
 }