[PATCH 10/14] vdso: Introduce aux_clock_resolution_ns()

["Thomas Weißschuh" <thomas.weissschuh@linutronix.de>]

Move the constant resolution to a shared header,
so the vDSO can use it and return it without going through a syscall.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
---
 include/vdso/auxclock.h   | 13 +++++++++++++
 kernel/time/timekeeping.c |  6 ++++--
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/include/vdso/auxclock.h b/include/vdso/auxclock.h
new file mode 100644
index 0000000000000000000000000000000000000000..6d6e74cbc400e7f5cd7194280759f5e5f3059900
--- /dev/null
+++ b/include/vdso/auxclock.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _VDSO_AUXCLOCK_H
+#define _VDSO_AUXCLOCK_H
+
+#include <uapi/linux/time.h>
+#include <uapi/linux/types.h>
+
+static __always_inline u64 aux_clock_resolution_ns(void)
+{
+	return 1;
+}
+
+#endif /* _VDSO_AUXCLOCK_H */
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 6a61887eb87e364b3ef170939919a8d4046c0508..6a088378df54d561ecfeafb45a8b54333e11a9a7 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -26,6 +26,8 @@
 #include <linux/audit.h>
 #include <linux/random.h>
 
+#include <vdso/auxclock.h>
+
 #include "tick-internal.h"
 #include "ntp_internal.h"
 #include "timekeeping_internal.h"
@@ -2842,8 +2844,8 @@ static int aux_get_res(clockid_t id, struct timespec64 *tp)
 	if (!clockid_aux_valid(id))
 		return -ENODEV;
 
-	tp->tv_sec = 0;
-	tp->tv_nsec = 1;
+	tp->tv_sec = aux_clock_resolution_ns() / NSEC_PER_SEC;
+	tp->tv_nsec = aux_clock_resolution_ns() % NSEC_PER_SEC;
 	return 0;
 }
 

-- 
2.50.0