From fb82fe2fe8588745edd73aa3a6229facac5c1e15 Mon Sep 17 00:00:00 2001 From: John Stultz Date: Wed, 11 Mar 2015 21:16:31 -0700 Subject: clocksource: Add 'max_cycles' to 'struct clocksource' In order to facilitate clocksource validation, add a 'max_cycles' field to the clocksource structure which will hold the maximum cycle value that can safely be multiplied without potentially causing an overflow. Signed-off-by: John Stultz Cc: Dave Jones Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Prarit Bhargava Cc: Richard Cochran Cc: Stephen Boyd Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1426133800-29329-4-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar --- include/linux/clocksource.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'include') diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h index 9c78d15d33e4..16d048cadebb 100644 --- a/include/linux/clocksource.h +++ b/include/linux/clocksource.h @@ -56,6 +56,7 @@ struct module; * @shift: cycle to nanosecond divisor (power of two) * @max_idle_ns: max idle time permitted by the clocksource (nsecs) * @maxadj: maximum adjustment value to mult (~11%) + * @max_cycles: maximum safe cycle value which won't overflow on multiplication * @flags: flags describing special properties * @archdata: arch-specific data * @suspend: suspend function for the clocksource, if necessary @@ -76,7 +77,7 @@ struct clocksource { #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA struct arch_clocksource_data archdata; #endif - + u64 max_cycles; const char *name; struct list_head list; int rating; @@ -189,7 +190,7 @@ extern struct clocksource * __init clocksource_default_clock(void); extern void clocksource_mark_unstable(struct clocksource *cs); extern u64 -clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask); +clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles); extern void clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec); -- cgit v1.2.2