xref: /freebsd/sys/x86/linux/linux_vdso_gettc_x86.inc (revision 31ba4ce8898f9dfa5e7f054fdbc26e50a599a6e3) 
1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org>
5 * Copyright (c) 2016, 2017, 2019 The FreeBSD Foundation
6 * Copyright (c) 2021 Dmitry Chagin <dchagin@FreeBSD.org>
7 *
8 * Portions of this software were developed by Konstantin Belousov
9 * under sponsorship from the FreeBSD Foundation.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#include <sys/cdefs.h>
34__FBSDID("$FreeBSD$");
35
36#include <sys/param.h>
37
38#if defined(__i386__) || defined(COMPAT_LINUX32)
39#include <i386/include/atomic.h>
40#include <i386/include/cpufunc.h>
41#else
42#include <amd64/include/atomic.h>
43#include <amd64/include/cpufunc.h>
44#endif
45
46static inline u_int
47rdtsc_low(const struct vdso_timehands *th)
48{
49	u_int rv;
50
51	__asm __volatile("rdtsc; shrd %%cl, %%edx, %0"
52	    : "=a" (rv) : "c" (th->th_x86_shift) : "edx");
53	return (rv);
54}
55
56static inline u_int
57rdtscp_low(const struct vdso_timehands *th)
58{
59	u_int rv;
60
61	__asm __volatile("rdtscp; movl %%edi,%%ecx; shrd %%cl, %%edx, %0"
62	    : "=a" (rv) : "D" (th->th_x86_shift) : "ecx", "edx");
63	return (rv);
64}
65
66static u_int
67rdtsc_low_mb_lfence(const struct vdso_timehands *th)
68{
69	lfence();
70	return (rdtsc_low(th));
71}
72
73static u_int
74rdtsc_low_mb_mfence(const struct vdso_timehands *th)
75{
76	mfence();
77	return (rdtsc_low(th));
78}
79
80static u_int
81rdtsc_low_mb_none(const struct vdso_timehands *th)
82{
83	return (rdtsc_low(th));
84}
85
86static u_int
87rdtsc32_mb_lfence(void)
88{
89	lfence();
90	return (rdtsc32());
91}
92
93static u_int
94rdtsc32_mb_mfence(void)
95{
96	mfence();
97	return (rdtsc32());
98}
99
100static u_int
101rdtsc32_mb_none(void)
102{
103	return (rdtsc32());
104}
105
106static u_int
107rdtscp32_(void)
108{
109	return (rdtscp32());
110}
111
112struct tsc_selector_tag {
113	u_int (*ts_rdtsc32)(void);
114	u_int (*ts_rdtsc_low)(const struct vdso_timehands *);
115};
116
117static const struct tsc_selector_tag tsc_selector[] = {
118	[0] = {				/* Intel, LFENCE */
119		.ts_rdtsc32 =	rdtsc32_mb_lfence,
120		.ts_rdtsc_low =	rdtsc_low_mb_lfence,
121	},
122	[1] = {				/* AMD, MFENCE */
123		.ts_rdtsc32 =	rdtsc32_mb_mfence,
124		.ts_rdtsc_low =	rdtsc_low_mb_mfence,
125	},
126	[2] = {				/* No SSE2 */
127		.ts_rdtsc32 = rdtsc32_mb_none,
128		.ts_rdtsc_low = rdtsc_low_mb_none,
129	},
130	[3] = {				/* RDTSCP */
131		.ts_rdtsc32 =	rdtscp32_,
132		.ts_rdtsc_low =	rdtscp_low,
133	},
134};
135
136static u_int
137__vdso_gettc_rdtsc_low(const struct vdso_timehands *th)
138{
139
140	return (tsc_selector[kern_tsc_selector].ts_rdtsc_low(th));
141}
142
143static u_int
144__vdso_gettc_rdtsc32(void)
145{
146
147	return (tsc_selector[kern_tsc_selector].ts_rdtsc32());
148}
149
150int
151__vdso_gettc(const struct vdso_timehands *th, u_int *tc)
152{
153
154	switch (th->th_algo) {
155	case VDSO_TH_ALGO_X86_TSC:
156		*tc = th->th_x86_shift > 0 ? __vdso_gettc_rdtsc_low(th) :
157		    __vdso_gettc_rdtsc32();
158		return (0);
159	case VDSO_TH_ALGO_X86_HPET:
160		/* TODO */
161	default:
162		return (ENOSYS);
163	}
164}
165