The following commit has been merged into the timers/ptp branch of tip:
Commit-ID: 9b7fc3f14576c268f62fe0b882fac5e61239b659
Gitweb: https://git.kernel.org/tip/9b7fc3f14576c268f62fe0b882fac5e61239b659
Author: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
AuthorDate: Tue, 01 Jul 2025 10:58:04 +02:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Fri, 18 Jul 2025 13:45:32 +02:00
vdso: Introduce aux_clock_resolution_ns()
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>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250701-vdso-auxclock-v1-10-df7d9f87b9b8@linutronix.de
---
include/vdso/auxclock.h | 13 +++++++++++++
kernel/time/timekeeping.c | 6 ++++--
2 files changed, 17 insertions(+), 2 deletions(-)
create mode 100644 include/vdso/auxclock.h
diff --git a/include/vdso/auxclock.h b/include/vdso/auxclock.h
new file mode 100644
index 0000000..6d6e74c
--- /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 c6fe89b..cbcf090 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"
@@ -2876,8 +2878,8 @@ 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;
}