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git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
timekeeping: Prepare timekeeping_cycles_to_ns() for overflow safety
Open code clocksource_delta() in timekeeping_cycles_to_ns() so that
overflow safety can be added efficiently.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240325064023.2997-17-adrian.hunter@intel.com
authored by
Adrian Hunter
and committed by
Thomas Gleixner
e809a80a
3094c6db
+11
-1
+11
-1
kernel/time/timekeeping.c
+11
-1
kernel/time/timekeeping.c
···
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static inline u64 timekeeping_cycles_to_ns(const struct tk_read_base *tkr, u64 cycles)
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{
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/* Calculate the delta since the last update_wall_time() */
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u64 delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
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u64 mask = tkr->mask, delta = (cycles - tkr->cycle_last) & mask;
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+
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if (IS_ENABLED(CONFIG_CLOCKSOURCE_VALIDATE_LAST_CYCLE)) {
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/*
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* Handle clocksource inconsistency between CPUs to prevent
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* time from going backwards by checking for the MSB of the
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* mask being set in the delta.
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*/
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if (unlikely(delta & ~(mask >> 1)))
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return tkr->xtime_nsec >> tkr->shift;
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}
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return ((delta * tkr->mult) + tkr->xtime_nsec) >> tkr->shift;
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}