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author | Thomas Gleixner <tglx@linutronix.de> | 2014-07-17 01:05:12 +0400 |
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committer | John Stultz <john.stultz@linaro.org> | 2014-07-24 02:01:51 +0400 |
commit | 09ec54429c6d10f87d1f084de53ae2c1c3a81108 (patch) | |
tree | 842749293edd755e8bb12e1433c2f9df7dd842cf /kernel/time/timekeeping_internal.h | |
parent | 3a97837784acbf9fed699fc04d1799b0eb742fdf (diff) | |
download | linux-09ec54429c6d10f87d1f084de53ae2c1c3a81108.tar.xz |
clocksource: Move cycle_last validation to core code
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>
Diffstat (limited to 'kernel/time/timekeeping_internal.h')
-rw-r--r-- | kernel/time/timekeeping_internal.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/kernel/time/timekeeping_internal.h b/kernel/time/timekeeping_internal.h index 05dfa6b25dc4..4ea005a7f9da 100644 --- a/kernel/time/timekeeping_internal.h +++ b/kernel/time/timekeeping_internal.h @@ -12,9 +12,18 @@ extern void tk_debug_account_sleep_time(struct timespec64 *t); #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 */ |