__vdso_gettc.c revision 292709 
1/*-
2 * Copyright (c) 2015 The FreeBSD Foundation
3 *
4 * This software was developed by Konstantin Belousov
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/cdefs.h>
30__FBSDID("$FreeBSD: head/lib/libc/arm/sys/__vdso_gettc.c 292709 2015-12-24 22:13:52Z kib $");
31
32#include <sys/types.h>
33#include <sys/elf.h>
34#include <sys/time.h>
35#include <sys/vdso.h>
36#include <machine/cpufunc.h>
37#include <machine/acle-compat.h>
38#include "libc_private.h"
39
40#if __ARM_ARCH >= 6
41static inline uint64_t
42cp15_cntvct_get(void)
43{
44	uint64_t reg;
45
46	__asm __volatile("mrrc\tp15, 1, %Q0, %R0, c14" : "=r" (reg));
47	return (reg);
48}
49
50static inline uint64_t
51cp15_cntpct_get(void)
52{
53	uint64_t reg;
54
55	__asm __volatile("mrrc\tp15, 0, %Q0, %R0, c14" : "=r" (reg));
56	return (reg);
57}
58#endif
59
60#pragma weak __vdso_gettc
61u_int
62__vdso_gettc(const struct vdso_timehands *th)
63{
64	uint64_t val;
65
66#if __ARM_ARCH >= 6
67	/*
68	 * Userspace gettimeofday() is only enabled on ARMv7 CPUs, but
69	 * libc is compiled for ARMv6.  Due to clang issues, .arch
70	 * armv7-a directive does not work.
71	 */
72	__asm __volatile(".word\t0xf57ff06f" : : : "memory"); /* isb */
73	val = th->th_physical == 0 ? cp15_cntvct_get() : cp15_cntpct_get();
74#else
75	val = 0;
76#endif
77	return (val);
78}
79
80#pragma weak __vdso_gettimekeep
81int
82__vdso_gettimekeep(struct vdso_timekeep **tk)
83{
84
85	return (_elf_aux_info(AT_TIMEKEEP, tk, sizeof(*tk)));
86}
87