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// SPDX-License-Identifier: GPL-2.0
#include <stdbool.h>
#include <errno.h>
#include <linux/stddef.h>
#include <linux/perf_event.h>
#include <linux/types.h>
#include <asm/barrier.h>
#include "../../../util/debug.h"
#include "../../../util/tsc.h"
int perf_read_tsc_conversion(const struct perf_event_mmap_page *pc,
struct perf_tsc_conversion *tc)
{
bool cap_user_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_user_time_zero = pc->cap_user_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_user_time_zero)
return -EOPNOTSUPP;
return 0;
}
u64 rdtsc(void)
{
unsigned int low, high;
asm volatile("rdtsc" : "=a" (low), "=d" (high));
return low | ((u64)high) << 32;
}
int perf_event__synth_time_conv(const struct perf_event_mmap_page *pc,
struct perf_tool *tool,
perf_event__handler_t process,
struct machine *machine)
{
union perf_event event = {
.time_conv = {
.header = {
.type = PERF_RECORD_TIME_CONV,
.size = sizeof(struct perf_record_time_conv),
},
},
};
struct perf_tsc_conversion tc;
int err;
if (!pc)
return 0;
err = perf_read_tsc_conversion(pc, &tc);
if (err == -EOPNOTSUPP)
return 0;
if (err)
return err;
pr_debug2("Synthesizing TSC conversion information\n");
event.time_conv.time_mult = tc.time_mult;
event.time_conv.time_shift = tc.time_shift;
event.time_conv.time_zero = tc.time_zero;
return process(tool, &event, NULL, machine);
}
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