[PATCH v4 1/3] timens: additional helper functions for boottime offset handling

["Michael Weiß" <michael.weiss@aisec.fraunhofer.de>]

Provide functions for time_namespace to subtract the boottime offset
from a timespec64 as well as to apply the boottime offset to u64 types in
nanoseconds.

Signed-off-by: Michael Weiß <michael.weiss@aisec.fraunhofer.de>
---
 include/linux/time_namespace.h | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index 5b6031385db0..68770ac9ba89 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -77,6 +77,20 @@ static inline void timens_add_boottime(struct timespec64 *ts)
 	*ts = timespec64_add(*ts, ns_offsets->boottime);
 }
 
+static inline u64 timens_add_boottime_ns(u64 nsec)
+{
+	struct timens_offsets *ns_offsets = &current->nsproxy->time_ns->offsets;
+
+	return nsec + timespec64_to_ns(&ns_offsets->boottime);
+}
+
+static inline void timens_sub_boottime(struct timespec64 *ts)
+{
+	struct timens_offsets *ns_offsets = &current->nsproxy->time_ns->offsets;
+
+	*ts = timespec64_sub(*ts, ns_offsets->boottime);
+}
+
 ktime_t do_timens_ktime_to_host(clockid_t clockid, ktime_t tim,
 				struct timens_offsets *offsets);
 
@@ -130,6 +144,14 @@ static inline int timens_on_fork(struct nsproxy *nsproxy,
 
 static inline void timens_add_monotonic(struct timespec64 *ts) { }
 static inline void timens_add_boottime(struct timespec64 *ts) { }
+
+static inline u64 timens_add_boottime_ns(u64 nsec)
+{
+	return nsec;
+}
+
+static inline void timens_sub_boottime(struct timespec64 *ts) { }
+
 static inline ktime_t timens_ktime_to_host(clockid_t clockid, ktime_t tim)
 {
 	return tim;
-- 
2.20.1