1 /*-
2 * Copyright (c) 2021 The FreeBSD Foundation
3 *
4 * This software were developed by Konstantin Belousov <kib@FreeBSD.org>
5 * under sponsorship from the FreeBSD Foundation.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <sys/param.h>
30 #include <machine/cpufunc.h>
31 #include <machine/specialreg.h>
32 #include <machine/sysarch.h>
33 #include <x86/ifunc.h>
34 #include <errno.h>
35 #include <sched.h>
36 #include "libc_private.h"
37
38 static int
sched_getcpu_sys(void)39 sched_getcpu_sys(void)
40 {
41 return (__sys_sched_getcpu());
42 }
43
44 static int
sched_getcpu_rdpid(void)45 sched_getcpu_rdpid(void)
46 {
47 register_t res;
48
49 __asm("rdpid %0" : "=r" (res));
50 return ((int)res);
51 }
52
53 static int
sched_getcpu_rdtscp(void)54 sched_getcpu_rdtscp(void)
55 {
56 int res;
57
58 __asm("rdtscp" : "=c" (res) : : "eax", "edx");
59 return (res);
60 }
61
62 DEFINE_UIFUNC(, int, sched_getcpu, (void))
63 {
64 u_int amd_feature, cpu_exthigh, p[4];
65
66 if ((cpu_stdext_feature2 & CPUID_STDEXT2_RDPID) != 0)
67 return (sched_getcpu_rdpid);
68
69 amd_feature = 0;
70 if (cpu_feature != 0) {
71 do_cpuid(0x80000000, p);
72 cpu_exthigh = p[0];
73 if (cpu_exthigh >= 0x80000001) {
74 do_cpuid(0x80000001, p);
75 amd_feature = p[3];
76 }
77 }
78
79 return ((amd_feature & AMDID_RDTSCP) == 0 ?
80 sched_getcpu_sys : sched_getcpu_rdtscp);
81 }
82