x86: provide userspace implementation of sched_getcpu() where possible
Reviewed by: jhb Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D32901
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@ -5,7 +5,7 @@
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SRCS+= \
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__vdso_gettc.c \
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pkru.c \
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sched_getcpu_gen.c
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sched_getcpu_x86.c
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MAN+= \
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pkru.3
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81
lib/libc/x86/sys/sched_getcpu_x86.c
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81
lib/libc/x86/sys/sched_getcpu_x86.c
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@ -0,0 +1,81 @@
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/*-
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* Copyright (c) 2021 The FreeBSD Foundation
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*
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* This software were developed by Konstantin Belousov <kib@FreeBSD.org>
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* under sponsorship from the FreeBSD Foundation.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/param.h>
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#include <machine/cpufunc.h>
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#include <machine/specialreg.h>
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#include <machine/sysarch.h>
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#include <x86/ifunc.h>
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#include <errno.h>
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#include <sched.h>
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#include "libc_private.h"
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static int
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sched_getcpu_sys(void)
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{
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return (__sys_sched_getcpu());
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}
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static int
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sched_getcpu_rdpid(void)
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{
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register_t res;
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__asm("rdpid %0" : "=r" (res));
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return ((int)res);
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}
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static int
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sched_getcpu_rdtscp(void)
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{
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int res;
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__asm("rdtscp" : "=c" (res) : : "eax", "edx");
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return (res);
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}
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DEFINE_UIFUNC(, int, sched_getcpu, (void))
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{
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u_int amd_feature, cpu_exthigh, p[4];
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if ((cpu_stdext_feature2 & CPUID_STDEXT2_RDPID) != 0)
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return (sched_getcpu_rdpid);
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amd_feature = 0;
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if (cpu_feature != 0) {
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do_cpuid(0x80000000, p);
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cpu_exthigh = p[0];
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if (cpu_exthigh >= 0x80000001) {
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do_cpuid(0x80000001, p);
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amd_feature = p[3];
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}
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}
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return ((amd_feature & AMDID_RDTSCP) == 0 ?
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sched_getcpu_sys : sched_getcpu_rdtscp);
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}
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