1 #include <stdbool.h> 2 #include <errno.h> 3 4 #include <linux/perf_event.h> 5 6 #include "../../perf.h" 7 #include "../../util/types.h" 8 #include "../../util/debug.h" 9 #include "tsc.h" 10 11 u64 perf_time_to_tsc(u64 ns, struct perf_tsc_conversion *tc) 12 { 13 u64 t, quot, rem; 14 15 t = ns - tc->time_zero; 16 quot = t / tc->time_mult; 17 rem = t % tc->time_mult; 18 return (quot << tc->time_shift) + 19 (rem << tc->time_shift) / tc->time_mult; 20 } 21 22 u64 tsc_to_perf_time(u64 cyc, struct perf_tsc_conversion *tc) 23 { 24 u64 quot, rem; 25 26 quot = cyc >> tc->time_shift; 27 rem = cyc & ((1 << tc->time_shift) - 1); 28 return tc->time_zero + quot * tc->time_mult + 29 ((rem * tc->time_mult) >> tc->time_shift); 30 } 31 32 int perf_read_tsc_conversion(const struct perf_event_mmap_page *pc, 33 struct perf_tsc_conversion *tc) 34 { 35 bool cap_user_time_zero; 36 u32 seq; 37 int i = 0; 38 39 while (1) { 40 seq = pc->lock; 41 rmb(); 42 tc->time_mult = pc->time_mult; 43 tc->time_shift = pc->time_shift; 44 tc->time_zero = pc->time_zero; 45 cap_user_time_zero = pc->cap_user_time_zero; 46 rmb(); 47 if (pc->lock == seq && !(seq & 1)) 48 break; 49 if (++i > 10000) { 50 pr_debug("failed to get perf_event_mmap_page lock\n"); 51 return -EINVAL; 52 } 53 } 54 55 if (!cap_user_time_zero) 56 return -EOPNOTSUPP; 57 58 return 0; 59 } 60