1 /* $OpenBSD: usertc.c,v 1.5 2022/09/22 04:57:07 robert Exp $ */
2 /*
3 * Copyright (c) 2020 Paul Irofti <paul@irofti.net>
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 #include <sys/types.h>
19 #include <sys/timetc.h>
20
21 static inline u_int
rdtsc_lfence(void)22 rdtsc_lfence(void)
23 {
24 uint32_t hi, lo;
25 __asm volatile("lfence; rdtsc" : "=a"(lo), "=d"(hi));
26 return ((uint64_t)lo)|(((uint64_t)hi)<<32);
27 }
28
29 static inline u_int
rdtscp(void)30 rdtscp(void)
31 {
32 uint32_t hi, lo;
33 __asm volatile("rdtscp" : "=a"(lo), "=d"(hi) : : "ecx");
34 return ((uint64_t)lo)|(((uint64_t)hi)<<32);
35 }
36
37 static int
tc_get_timecount(struct timekeep * tk,u_int * tc)38 tc_get_timecount(struct timekeep *tk, u_int *tc)
39 {
40 switch (tk->tk_user) {
41 case TC_TSC_LFENCE:
42 *tc = rdtsc_lfence();
43 return 0;
44 case TC_TSC_RDTSCP:
45 *tc = rdtscp();
46 return 0;
47 }
48
49 return -1;
50 }
51
52 int (*const _tc_get_timecount)(struct timekeep *, u_int *) = tc_get_timecount;
53