mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-13 14:04:05 +08:00
09ec54429c
The only user of the cycle_last validation is the x86 TSC. In order to
provide NMI safe accessor functions for clock monotonic and
monotonic_raw we need to do that in the core.
We can't do the TSC specific
if (now < cycle_last)
now = cycle_last;
for the other wrapping around clocksources, but TSC has
CLOCKSOURCE_MASK(64) which actually does not mask out anything so if
now is less than cycle_last the subtraction will give a negative
result. So we can check for that in clocksource_delta() and return 0
for that case.
Implement and enable it for x86
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
30 lines
663 B
C
30 lines
663 B
C
#ifndef _TIMEKEEPING_INTERNAL_H
|
|
#define _TIMEKEEPING_INTERNAL_H
|
|
/*
|
|
* timekeeping debug functions
|
|
*/
|
|
#include <linux/clocksource.h>
|
|
#include <linux/time.h>
|
|
|
|
#ifdef CONFIG_DEBUG_FS
|
|
extern void tk_debug_account_sleep_time(struct timespec64 *t);
|
|
#else
|
|
#define tk_debug_account_sleep_time(x)
|
|
#endif
|
|
|
|
#ifdef CONFIG_CLOCKSOURCE_VALIDATE_LAST_CYCLE
|
|
static inline cycle_t clocksource_delta(cycle_t now, cycle_t last, cycle_t mask)
|
|
{
|
|
cycle_t ret = (now - last) & mask;
|
|
|
|
return (s64) ret > 0 ? ret : 0;
|
|
}
|
|
#else
|
|
static inline cycle_t clocksource_delta(cycle_t now, cycle_t last, cycle_t mask)
|
|
{
|
|
return (now - last) & mask;
|
|
}
|
|
#endif
|
|
|
|
#endif /* _TIMEKEEPING_INTERNAL_H */
|