The configurable printk timestamping wants access to clock realtime. Right
now there is no ktime_get_real_fast_ns() accessor because reading the
monotonic base and the realtime offset cannot be done atomically. Contrary
to boot time this offset can change during runtime and cause half updated
readouts.
struct tk_read_base was fully packed when the fast timekeeper access was
implemented. commit ceea5e3771 ("time: Fix clock->read(clock) race around
clocksource changes") removed the 'read' function pointer from the
structure, but of course left the comment stale.
So now the structure can fit a new 64bit member w/o violating the cache
line constraints.
Add real_base to tk_read_base and update it in the fast timekeeper update
sequence.
Implement an accessor which follows the same scheme as the accessor to
clock monotonic, but uses the new real_base to access clock real time.
The runtime overhead for updating real_base is minimal as it just adds two
cache hot values and stores them into an already dirtied cache line along
with the other fast timekeeper updates.
Change-Id: I67297bb116aba7400645dd593f83dba149ae65d3
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead,org>
Link: https://lkml.kernel.org/r/1505757060-2004-3-git-send-email-prarit@redhat.com
Signed-off-by: Naveen <133593113+elohim-etz@users.noreply.github.com>
259 lines
6.2 KiB
C
259 lines
6.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_TIMEKEEPING_H
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#define _LINUX_TIMEKEEPING_H
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#include <linux/errno.h>
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/* Included from linux/ktime.h */
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void timekeeping_init(void);
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extern int timekeeping_suspended;
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/* Architecture timer tick functions: */
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extern void update_process_times(int user);
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extern void xtime_update(unsigned long ticks);
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/*
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* Get and set timeofday
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*/
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extern int do_settimeofday64(const struct timespec64 *ts);
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extern int do_sys_settimeofday64(const struct timespec64 *tv,
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const struct timezone *tz);
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/*
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* timespec64 based interfaces
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*/
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extern void ktime_get_raw_ts64(struct timespec64 *ts);
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extern void ktime_get_ts64(struct timespec64 *ts);
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extern void ktime_get_real_ts64(struct timespec64 *tv);
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extern void ktime_get_coarse_ts64(struct timespec64 *ts);
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extern void ktime_get_coarse_real_ts64(struct timespec64 *ts);
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void getboottime64(struct timespec64 *ts);
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/*
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* time64_t base interfaces
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*/
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extern time64_t ktime_get_seconds(void);
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extern time64_t ktime_get_real_seconds(void);
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/*
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* ktime_t based interfaces
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*/
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enum tk_offsets {
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TK_OFFS_REAL,
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TK_OFFS_BOOT,
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TK_OFFS_TAI,
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TK_OFFS_MAX,
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};
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extern ktime_t ktime_get(void);
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extern ktime_t ktime_get_with_offset(enum tk_offsets offs);
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extern ktime_t ktime_get_coarse_with_offset(enum tk_offsets offs);
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extern ktime_t ktime_mono_to_any(ktime_t tmono, enum tk_offsets offs);
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extern ktime_t ktime_get_raw(void);
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extern u32 ktime_get_resolution_ns(void);
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/**
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* ktime_get_real - get the real (wall-) time in ktime_t format
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*/
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static inline ktime_t ktime_get_real(void)
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{
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return ktime_get_with_offset(TK_OFFS_REAL);
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}
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static inline ktime_t ktime_get_coarse_real(void)
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{
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return ktime_get_coarse_with_offset(TK_OFFS_REAL);
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}
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/**
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* ktime_get_boottime - Returns monotonic time since boot in ktime_t format
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*
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* This is similar to CLOCK_MONTONIC/ktime_get, but also includes the
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* time spent in suspend.
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*/
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static inline ktime_t ktime_get_boottime(void)
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{
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return ktime_get_with_offset(TK_OFFS_BOOT);
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}
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static inline ktime_t ktime_get_coarse_boottime(void)
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{
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return ktime_get_coarse_with_offset(TK_OFFS_BOOT);
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}
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/**
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* ktime_get_clocktai - Returns the TAI time of day in ktime_t format
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*/
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static inline ktime_t ktime_get_clocktai(void)
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{
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return ktime_get_with_offset(TK_OFFS_TAI);
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}
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static inline ktime_t ktime_get_coarse_clocktai(void)
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{
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return ktime_get_coarse_with_offset(TK_OFFS_TAI);
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}
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/**
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* ktime_mono_to_real - Convert monotonic time to clock realtime
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*/
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static inline ktime_t ktime_mono_to_real(ktime_t mono)
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{
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return ktime_mono_to_any(mono, TK_OFFS_REAL);
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}
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static inline u64 ktime_get_ns(void)
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{
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return ktime_to_ns(ktime_get());
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}
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static inline u64 ktime_get_real_ns(void)
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{
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return ktime_to_ns(ktime_get_real());
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}
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static inline u64 ktime_get_boottime_ns(void)
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{
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return ktime_to_ns(ktime_get_boottime());
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}
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static inline u64 ktime_get_clocktai_ns(void)
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{
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return ktime_to_ns(ktime_get_clocktai());
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}
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static inline u64 ktime_get_raw_ns(void)
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{
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return ktime_to_ns(ktime_get_raw());
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}
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extern u64 ktime_get_mono_fast_ns(void);
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extern u64 ktime_get_raw_fast_ns(void);
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extern u64 ktime_get_boot_fast_ns(void);
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extern u64 ktime_get_real_fast_ns(void);
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/*
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* timespec64 interfaces utilizing the ktime based ones
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*/
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static inline void ktime_get_boottime_ts64(struct timespec64 *ts)
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{
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*ts = ktime_to_timespec64(ktime_get_boottime());
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}
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static inline void ktime_get_clocktai_ts64(struct timespec64 *ts)
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{
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*ts = ktime_to_timespec64(ktime_get_clocktai());
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}
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/*
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* RTC specific
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*/
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extern bool timekeeping_rtc_skipsuspend(void);
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extern bool timekeeping_rtc_skipresume(void);
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extern void timekeeping_inject_sleeptime64(struct timespec64 *delta);
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/*
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* PPS accessor
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*/
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extern void ktime_get_raw_and_real_ts64(struct timespec64 *ts_raw,
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struct timespec64 *ts_real);
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/*
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* struct system_time_snapshot - simultaneous raw/real time capture with
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* counter value
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* @cycles: Clocksource counter value to produce the system times
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* @real: Realtime system time
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* @raw: Monotonic raw system time
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* @clock_was_set_seq: The sequence number of clock was set events
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* @cs_was_changed_seq: The sequence number of clocksource change events
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*/
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struct system_time_snapshot {
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u64 cycles;
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ktime_t real;
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ktime_t raw;
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unsigned int clock_was_set_seq;
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u8 cs_was_changed_seq;
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};
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/*
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* struct system_device_crosststamp - system/device cross-timestamp
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* (syncronized capture)
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* @device: Device time
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* @sys_realtime: Realtime simultaneous with device time
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* @sys_monoraw: Monotonic raw simultaneous with device time
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*/
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struct system_device_crosststamp {
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ktime_t device;
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ktime_t sys_realtime;
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ktime_t sys_monoraw;
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};
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/*
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* struct system_counterval_t - system counter value with the pointer to the
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* corresponding clocksource
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* @cycles: System counter value
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* @cs: Clocksource corresponding to system counter value. Used by
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* timekeeping code to verify comparibility of two cycle values
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*/
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struct system_counterval_t {
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u64 cycles;
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struct clocksource *cs;
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};
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/*
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* Get cross timestamp between system clock and device clock
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*/
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extern int get_device_system_crosststamp(
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int (*get_time_fn)(ktime_t *device_time,
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struct system_counterval_t *system_counterval,
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void *ctx),
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void *ctx,
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struct system_time_snapshot *history,
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struct system_device_crosststamp *xtstamp);
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/*
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* Simultaneously snapshot realtime and monotonic raw clocks
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*/
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extern void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot);
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/*
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* Persistent clock related interfaces
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*/
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extern int persistent_clock_is_local;
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extern void read_persistent_clock64(struct timespec64 *ts);
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extern void read_boot_clock64(struct timespec64 *ts);
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extern int update_persistent_clock64(struct timespec64 now);
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/*
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* deprecated aliases, don't use in new code
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*/
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#define getnstimeofday64(ts) ktime_get_real_ts64(ts)
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#define get_monotonic_boottime64(ts) ktime_get_boottime_ts64(ts)
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#define getrawmonotonic64(ts) ktime_get_raw_ts64(ts)
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#define timekeeping_clocktai64(ts) ktime_get_clocktai_ts64(ts)
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static inline struct timespec64 current_kernel_time64(void)
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{
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struct timespec64 ts;
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ktime_get_coarse_real_ts64(&ts);
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return ts;
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}
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static inline struct timespec64 get_monotonic_coarse64(void)
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{
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struct timespec64 ts;
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ktime_get_coarse_ts64(&ts);
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return ts;
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}
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#endif
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