[PATCH 3/3] vdso/gettimeofday: Add support for CLOCK_REALTIME_ALARM

[Thomas Weißschuh]

CLOCK_REALTIME_ALARM behaves exactly as CLOCK_REALTIME as far as the
vDSO is concerned. The vDSO library can handle it automatically
correctly. Only the basetime needs to be maintained during the tick.

Reuse the CLOCK_REALTIME basetime for CLOCK_REALTIME_ALARM and update
the userspace hres clock mask to include CLOCK_REALTIME_ALARM.
---
 include/vdso/datapage.h | 1 +
 kernel/time/vsyscall.c  | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/include/vdso/datapage.h b/include/vdso/datapage.h
index 33297b5e2521..0aa28a484dcd 100644
--- a/include/vdso/datapage.h
+++ b/include/vdso/datapage.h
@@ -33,6 +33,7 @@ struct vdso_arch_data {
 #define VDSO_BASES	(CLOCK_TAI + 1)
 #define VDSO_BASE_AUX	0
 #define VDSO_HRES	(BIT(CLOCK_REALTIME)		| \
+			 BIT(CLOCK_REALTIME_ALARM)	| \
 			 BIT(CLOCK_MONOTONIC)		| \
 			 BIT(CLOCK_BOOTTIME)		| \
 			 BIT(CLOCK_BOOTTIME_ALARM)	| \
diff --git a/kernel/time/vsyscall.c b/kernel/time/vsyscall.c
index 24082b9d7869..b32bfded7d53 100644
--- a/kernel/time/vsyscall.c
+++ b/kernel/time/vsyscall.c
@@ -75,6 +75,10 @@ static inline void update_vdso_time_data(struct vdso_time_data *vdata, struct ti
 	vdso_ts		= &vc[CS_HRES_COARSE].basetime[CLOCK_TAI];
 	vdso_ts->sec	= tk->xtime_sec + (s64)tk->tai_offset;
 	vdso_ts->nsec	= tk->tkr_mono.xtime_nsec;
+
+	/* CLOCK_REALTIME_ALARM, copy of CLOCK_REALTIME */
+	vdso_ts		= &vc[CS_HRES_COARSE].basetime[CLOCK_REALTIME_ALARM];
+	*vdso_ts	= vc[CS_HRES_COARSE].basetime[CLOCK_REALTIME];
 }
 
 void update_vsyscall(struct timekeeper *tk)

-- 
2.55.0