From 0a02b0ee8a2070303b2bf824573cb5528cc38cc5 Mon Sep 17 00:00:00 2001 From: Vincent Donnefort Date: Wed, 21 Dec 2022 16:53:34 +0000 Subject: [PATCH] FROMLIST: timekeeping: Export the boot clock in snapshots On arm64 systems, the arch timer can be accessible by both EL1 and EL2. This means when running with nVHE or protected KVM, it is easy to generate clock values from the hypervisor, synchronized with the kernel. 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. Bug: 357781595 Link: https://lore.kernel.org/all/20240805173234.3542917-5-vdonnefort@google.com/ Change-Id: I18ab228d1c4e0a9684ba014b2ede87bac7087850 Signed-off-by: Vincent Donnefort --- include/linux/timekeeping.h | 4 ++++ kernel/time/timekeeping.c | 5 +++++ 2 files changed, 9 insertions(+) diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h index e85c27347e44..0fc6a61d64bd 100644 --- a/include/linux/timekeeping.h +++ b/include/linux/timekeeping.h @@ -280,6 +280,8 @@ struct ktime_timestamps { * @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 + * @mono_shift: The monotonic clock slope shift + * @mono_mult: The monotonic clock slope mult */ struct system_time_snapshot { u64 cycles; @@ -289,6 +291,8 @@ struct system_time_snapshot { enum clocksource_ids cs_id; unsigned int clock_was_set_seq; u8 cs_was_changed_seq; + u32 mono_shift; + u32 mono_mult; }; /** diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 47e44b9d2671..2f126cec4773 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1057,6 +1057,7 @@ noinstr time64_t __ktime_get_real_seconds(void) void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot) { struct timekeeper *tk = &tk_core.timekeeper; + u32 mono_mult, mono_shift; unsigned int seq; ktime_t base_raw; ktime_t base_real; @@ -1080,12 +1081,16 @@ void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot) 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); + mono_mult = tk->tkr_mono.mult; + mono_shift = tk->tkr_mono.shift; } while (read_seqcount_retry(&tk_core.seq, seq)); 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); + systime_snapshot->mono_shift = mono_shift; + systime_snapshot->mono_mult = mono_mult; } EXPORT_SYMBOL_GPL(ktime_get_snapshot);