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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
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#define _TIMEKEEPING_INTERNAL_H
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/*
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* timekeeping debug functions
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*/
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#include <linux/clocksource.h>
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#include <linux/time.h>
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#ifdef CONFIG_DEBUG_FS
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extern void tk_debug_account_sleep_time(struct timespec64 *t);
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#else
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#define tk_debug_account_sleep_time(x)
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#endif
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#ifdef CONFIG_CLOCKSOURCE_VALIDATE_LAST_CYCLE
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static inline cycle_t clocksource_delta(cycle_t now, cycle_t last, cycle_t mask)
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{
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cycle_t ret = (now - last) & mask;
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return (s64) ret > 0 ? ret : 0;
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}
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#else
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static inline cycle_t clocksource_delta(cycle_t now, cycle_t last, cycle_t mask)
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{
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return (now - last) & mask;
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}
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#endif
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#endif /* _TIMEKEEPING_INTERNAL_H */
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