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#include <stdbool.h>
#include <errno.h>
#include <linux/perf_event.h>
#include "../../perf.h"
#include "../../util/types.h"
#include "../../util/debug.h"
#include "tsc.h"
u64 perf_time_to_tsc(u64 ns, struct perf_tsc_conversion *tc)
{
u64 t, quot, rem;
t = ns - tc->time_zero;
quot = t / tc->time_mult;
rem = t % tc->time_mult;
return (quot << tc->time_shift) +
(rem << tc->time_shift) / tc->time_mult;
}
u64 tsc_to_perf_time(u64 cyc, struct perf_tsc_conversion *tc)
{
u64 quot, rem;
quot = cyc >> tc->time_shift;
rem = cyc & ((1 << tc->time_shift) - 1);
return tc->time_zero + quot * tc->time_mult +
((rem * tc->time_mult) >> tc->time_shift);
}
int perf_read_tsc_conversion(const struct perf_event_mmap_page *pc,
struct perf_tsc_conversion *tc)
{
bool cap_usr_time_zero;
u32 seq;
int i = 0;
while (1) {
seq = pc->lock;
rmb();
tc->time_mult = pc->time_mult;
tc->time_shift = pc->time_shift;
tc->time_zero = pc->time_zero;
cap_usr_time_zero = pc->cap_usr_time_zero;
rmb();
if (pc->lock == seq && !(seq & 1))
break;
if (++i > 10000) {
pr_debug("failed to get perf_event_mmap_page lock\n");
return -EINVAL;
}
}
if (!cap_usr_time_zero)
return -EOPNOTSUPP;
return 0;
}
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