timekeeping: Add the boot clock to system time snapshot

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

diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index fc12a9ba2c884271a75608211a72173b7ebaa24c..e85c27347e44fd625dbab9d0fa7f0bce11c49d84 100644 (file)
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -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;

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 7e6f409bf3114af3ef237ef2b48760a73aba7b43..47e44b9d26711624a020f77a69534a5204d53da9 100644 (file)
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -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);