freebsd-dev/sys/x86/linux/linux_vdso_tsc_selector_x86.c

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/*-
* Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org>
* Copyright (c) 2016, 2017, 2019 The FreeBSD Foundation
* Copyright (c) 2021 Dmitry Chagin <dchagin@FreeBSD.org>
*
* Portions of this software were developed by Konstantin Belousov
* under sponsorship from the FreeBSD Foundation.
*
* 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("$FreeBSD$");
#include <sys/param.h>
#include <x86/cputypes.h>
#include <x86/x86_var.h>
#include <x86/specialreg.h>
#include <x86/linux/linux_x86.h>
int
linux_vdso_tsc_selector_idx()
{
bool amd_cpu;
if (cpu_feature == 0)
return (2); /* should not happen due to RDTSC */
amd_cpu = (cpu_vendor_id == CPU_VENDOR_AMD ||
cpu_vendor_id == CPU_VENDOR_HYGON);
if ((amd_feature & AMDID_RDTSCP) != 0)
return (3);
if ((cpu_feature & CPUID_SSE2) == 0)
return (2);
return (amd_cpu ? 1 : 0);
}