/*-
 * Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: releng/11.0/lib/libc/amd64/sys/__vdso_gettc.c 286284 2015-08-04 12:33:51Z kib $");

#include <sys/types.h>
#include <sys/elf.h>
#include <sys/time.h>
#include <sys/vdso.h>
#include <machine/cpufunc.h>
#include "libc_private.h"

static u_int
__vdso_gettc_low(const struct vdso_timehands *th)
{
	u_int rv;

	__asm __volatile("lfence; rdtsc; shrd %%cl, %%edx, %0"
	    : "=a" (rv) : "c" (th->th_x86_shift) : "edx");
	return (rv);
}

static u_int
__vdso_rdtsc32(void)
{
	u_int rv;

	__asm __volatile("lfence;rdtsc" : "=a" (rv) : : "edx");
	return (rv);
}

#pragma weak __vdso_gettc
u_int
__vdso_gettc(const struct vdso_timehands *th)
{

	return (th->th_x86_shift > 0 ? __vdso_gettc_low(th) :
	    __vdso_rdtsc32());
}

#pragma weak __vdso_gettimekeep
int
__vdso_gettimekeep(struct vdso_timekeep **tk)
{

	return (_elf_aux_info(AT_TIMEKEEP, tk, sizeof(*tk)));
}