From eba302268a019275fd6ff452d4ff0b94fef11c76 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Fri, 29 May 2026 21:59:51 +0200 Subject: timekeeping: Provide ktime_get_snapshot_id() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit ktime_get_snapshot() provides a snapshot of the underlying clocksource counter value and the corresponding CLOCK_MONOTONIC_RAW, CLOCK_REALTIME and CLOCK_BOOTTIME timestamps. There is no usage of CLOCK_REALTIME and CLOCK_BOOTTIME at the same time and CLOCK_BOOTTIME support was just added for the ARM64 KVM tracing mechanism, which needs CLOCK_BOOTTIME and the underlying clocksource counter value. ktime_get_snapshot() is also not suitable for usage with CLOCK_AUX, but that's a prerequisite to support PTP hardware timestamping for CLOCK_AUX steering. As a first step, rename ktime_get_snapshot() to ktime_get_snapshot_id(), which now takes a clockid argument to select the clock which needs to be captured. The result is stored in system_time_snapshot::systime, which will replace the system_time_snapshot::real/boot members once all usage sites have been converted. ktime_get_snapshot() is a simple wrapper which hands in CLOCK_REALTIME as clockid argument for the conversion period. That means CLOCK_REALTIME is now captured twice, but that redunancy is only temporary. As all usage sites of struct system_time_snapshot has to be updated anyway, rename the 'raw' member to 'monoraw' for clarity. No functional change vs. current users of ktime_get_snapshot() Signed-off-by: Thomas Gleixner Tested-by: David Woodhouse Tested-by: Arthur Kiyanovski Reviewed-by: David Woodhouse Reviewed-by: Thomas Weißschuh Reviewed-by: Jacob Keller Link: https://patch.msgid.link/20260529195556.971591633@kernel.org --- include/linux/timekeeping.h | 34 ++++++++++++++++++++++++---------- 1 file changed, 24 insertions(+), 10 deletions(-) (limited to 'include/linux') diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h index aee2c1a46e47..161157c8d27e 100644 --- a/include/linux/timekeeping.h +++ b/include/linux/timekeeping.h @@ -276,24 +276,32 @@ static inline bool ktime_get_aux_ts64(clockid_t id, struct timespec64 *kt) { ret #endif /** - * struct system_time_snapshot - simultaneous raw/real time capture with - * counter value - * @cycles: Clocksource counter value to produce the system times - * @real: Realtime system time - * @boot: Boot time - * @raw: Monotonic raw system time - * @cs_id: Clocksource ID + * struct system_time_snapshot - Simultaneous time capture of CLOCK_MONOTONIC_RAW, + * a selected CLOCK_* and the clocksource counter value + * @cycles: Clocksource counter value to produce the system times + * @systime: The system time of the selected CLOCK ID + * @real: Realtime system time + * @boot: Boot time + * @raw: Monotonic raw system time + * @monoraw: Monotonic raw system time + * @cs_id: Clocksource ID * @clock_was_set_seq: The sequence number of clock-was-set events * @cs_was_changed_seq: The sequence number of clocksource change events + * @valid: True if the snapshot is valid */ struct system_time_snapshot { u64 cycles; + ktime_t systime; ktime_t real; ktime_t boot; - ktime_t raw; + union { + ktime_t raw; + ktime_t monoraw; + }; enum clocksource_ids cs_id; unsigned int clock_was_set_seq; u8 cs_was_changed_seq; + u8 valid; }; /** @@ -341,9 +349,15 @@ extern int get_device_system_crosststamp( struct system_device_crosststamp *xtstamp); /* - * Simultaneously snapshot realtime and monotonic raw clocks + * Simultaneously snapshot a given clock with MONOTONIC_RAW and the underlying + * clocksource counter value. */ -extern void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot); +extern void ktime_get_snapshot_id(clockid_t clock_id, struct system_time_snapshot *systime_snapshot); + +static inline void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot) +{ + ktime_get_snapshot_id(CLOCK_REALTIME, systime_snapshot); +} /* * Persistent clock related interfaces -- cgit v1.2.3