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timekeeping: Add the boot clock to system time snapshot

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For tracing purpose, the boot clock is interesting as it doesn't stop on
suspend. Export it as part of the time snapshot. This will later allow
the hypervisor to add boot clock timestamps to its events.

Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20240911093029.3279154-5-vdonnefort@google.com
This commit is contained in:
Vincent Donnefort 2024-09-11 10:30:20 +01:00 • committed by Thomas Gleixner
parent 9852d85ec9
commit 8102c4daf4
2 changed files with 6 additions and 0 deletions
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2
include/linux/timekeeping.h
View file

@ -275,6 +275,7 @@ struct ktime_timestamps {
* 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
* @clock_was_set_seq: The sequence number of clock-was-set events
@ -283,6 +284,7 @@ struct ktime_timestamps {
struct system_time_snapshot {
u64 cycles;
ktime_t real;
ktime_t boot;
ktime_t raw;
enum clocksource_ids cs_id;
unsigned int clock_was_set_seq;

4
kernel/time/timekeeping.c
View file

@ -1060,6 +1060,7 @@ void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
unsigned int seq;
ktime_t base_raw;
ktime_t base_real;
ktime_t base_boot;
u64 nsec_raw;
u64 nsec_real;
u64 now;
@ -1074,6 +1075,8 @@ void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
base_real = ktime_add(tk->tkr_mono.base,
tk_core.timekeeper.offs_real);
base_boot = ktime_add(tk->tkr_mono.base,
tk_core.timekeeper.offs_boot);
base_raw = tk->tkr_raw.base;
nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
@ -1081,6 +1084,7 @@ void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
systime_snapshot->cycles = now;
systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
systime_snapshot->boot = ktime_add_ns(base_boot, nsec_real);
systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
}
EXPORT_SYMBOL_GPL(ktime_get_snapshot);