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x86: provide userspace implementation of sched_getcpu() where possible

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Reviewed by:	jhb
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D32901
This commit is contained in:
Konstantin Belousov 2021-10-31 03:39:31 +02:00
parent 77b2c2f814
commit f239545591
2 changed files with 82 additions and 1 deletions

2
lib/libc/x86/sys/Makefile.inc

@ -5,7 +5,7 @@
SRCS+= \
__vdso_gettc.c \
pkru.c \
sched_getcpu_gen.c
sched_getcpu_x86.c
MAN+= \
pkru.3

81
lib/libc/x86/sys/sched_getcpu_x86.c Normal file

@ -0,0 +1,81 @@
/*-
* Copyright (c) 2021 The FreeBSD Foundation
*
* This software were developed by Konstantin Belousov <kib@FreeBSD.org>
* 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/param.h>
#include <machine/cpufunc.h>
#include <machine/specialreg.h>
#include <machine/sysarch.h>
#include <x86/ifunc.h>
#include <errno.h>
#include <sched.h>
#include "libc_private.h"
static int
sched_getcpu_sys(void)
{
return (__sys_sched_getcpu());
}
static int
sched_getcpu_rdpid(void)
{
register_t res;
__asm("rdpid %0" : "=r" (res));
return ((int)res);
}
static int
sched_getcpu_rdtscp(void)
{
int res;
__asm("rdtscp" : "=c" (res) : : "eax", "edx");
return (res);
}
DEFINE_UIFUNC(, int, sched_getcpu, (void))
{
u_int amd_feature, cpu_exthigh, p[4];
if ((cpu_stdext_feature2 & CPUID_STDEXT2_RDPID) != 0)
return (sched_getcpu_rdpid);
amd_feature = 0;
if (cpu_feature != 0) {
do_cpuid(0x80000000, p);
cpu_exthigh = p[0];
if (cpu_exthigh >= 0x80000001) {
do_cpuid(0x80000001, p);
amd_feature = p[3];
}
}
return ((amd_feature & AMDID_RDTSCP) == 0 ?
sched_getcpu_sys : sched_getcpu_rdtscp);
}