linux/kernel/time
Peter Hilber 14274d0bd3 timekeeping: Fix cross-timestamp interpolation for non-x86
So far, get_device_system_crosststamp() unconditionally passes
system_counterval.cycles to timekeeping_cycles_to_ns(). But when
interpolating system time (do_interp == true), system_counterval.cycles is
before tkr_mono.cycle_last, contrary to the timekeeping_cycles_to_ns()
expectations.

On x86, CONFIG_CLOCKSOURCE_VALIDATE_LAST_CYCLE will mitigate on
interpolating, setting delta to 0. With delta == 0, xtstamp->sys_monoraw
and xtstamp->sys_realtime are then set to the last update time, as
implicitly expected by adjust_historical_crosststamp(). On other
architectures, the resulting nonsense xtstamp->sys_monoraw and
xtstamp->sys_realtime corrupt the xtstamp (ts) adjustment in
adjust_historical_crosststamp().

Fix this by deriving xtstamp->sys_monoraw and xtstamp->sys_realtime from
the last update time when interpolating, by using the local variable
"cycles". The local variable already has the right value when
interpolating, unlike system_counterval.cycles.

Fixes: 2c756feb18 ("time: Add history to cross timestamp interface supporting slower devices")
Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/r/20231218073849.35294-4-peter.hilber@opensynergy.com
2024-02-19 12:18:51 +01:00
..
alarmtimer.c alarmtimer: Use maximum alarm time for suspend 2023-10-09 15:03:28 +02:00
clockevents.c clockevents: Make clockevents_subsys const 2024-02-07 15:11:24 +01:00
clocksource-wdtest.c clocksource: Make clocksource watchdog test safe for slow-HZ systems 2021-08-28 17:01:32 +02:00
clocksource.c clocksource: Make clocksource_subsys const 2024-02-07 15:11:24 +01:00
hrtimer.c hrtimers: Update formatting of documentation 2024-02-19 09:37:59 +01:00
itimer.c
jiffies.c clocksource: Make clocksource watchdog test safe for slow-HZ systems 2021-08-28 17:01:32 +02:00
Kconfig clocksource: Loosen clocksource watchdog constraints 2023-01-03 20:43:45 -08:00
Makefile time: Improve performance of time64_to_tm() 2021-06-24 11:51:59 +02:00
namespace.c vdso/timens: Refactor copy-pasted find_timens_vvar_page() helper into one copy 2022-12-01 11:35:40 +01:00
ntp_internal.h
ntp.c timekeeping, clocksource: Fix various typos in comments 2021-03-22 23:06:48 +01:00
posix-clock.c posix-clock: introduce posix_clock_context concept 2023-10-15 20:07:52 +01:00
posix-cpu-timers.c posix-cpu-timers: Implement the missing timer_wait_running callback 2023-04-21 15:34:33 +02:00
posix-stubs.c posix-timers: Get rid of [COMPAT_]SYS_NI() uses 2023-12-20 21:30:27 -08:00
posix-timers.c posix-timers: Refer properly to CONFIG_HIGH_RES_TIMERS 2023-06-18 22:41:53 +02:00
posix-timers.h
sched_clock.c time/sched_clock: Provide sched_clock_noinstr() 2023-06-05 21:11:04 +02:00
test_udelay.c time/debug: Fix memory leak with using debugfs_lookup() 2023-02-09 20:12:27 +01:00
tick-broadcast-hrtimer.c time/tick-broadcast: Remove RCU_NONIDLE() usage 2023-01-13 11:48:16 +01:00
tick-broadcast.c tick/broadcast: Make broadcast device replacement work correctly 2023-05-08 23:18:16 +02:00
tick-common.c tick/common: Align tick period during sched_timer setup 2023-06-16 20:45:28 +02:00
tick-internal.h time: Make sysfs_get_uname() function visible in header 2023-11-22 14:12:10 +01:00
tick-legacy.c
tick-oneshot.c time: Fix various kernel-doc problems 2023-01-03 11:07:58 +01:00
tick-sched.c tick/sched: Add function description for tick_nohz_next_event() 2024-02-19 09:38:00 +01:00
tick-sched.h timers/nohz: Protect idle/iowait sleep time under seqcount 2023-04-18 16:35:12 +02:00
time_test.c kunit: time: Mark test as slow using test attributes 2023-07-26 13:29:35 -06:00
time.c time: add kernel-doc in time.c 2023-07-14 13:47:07 -06:00
timeconst.bc
timeconv.c time: Improve performance of time64_to_tm() 2021-06-24 11:51:59 +02:00
timecounter.c time/timecounter: Mark 1st argument of timecounter_cyc2time() as const 2021-04-16 21:03:50 +02:00
timekeeping_debug.c
timekeeping_internal.h
timekeeping.c timekeeping: Fix cross-timestamp interpolation for non-x86 2024-02-19 12:18:51 +01:00
timekeeping.h
timer_list.c timer_list: Print name of per-cpu wakeup device 2021-05-31 17:04:49 +02:00
timer.c timers: Add struct member description for timer_base 2024-02-19 09:38:00 +01:00
vsyscall.c timekeeping, clocksource: Fix various typos in comments 2021-03-22 23:06:48 +01:00