321 lines
8.0 KiB
C
321 lines
8.0 KiB
C
/*
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* Copyright (c) 2001
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* John Baldwin <jhb@FreeBSD.org>. All rights reserved.
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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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* 4. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY JOHN BALDWIN 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 JOHN BALDWIN OR THE VOICES IN HIS HEAD
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
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* THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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/*
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* This module holds the global variables and machine independent functions
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* used for the kernel SMP support.
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/ktr.h>
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#include <sys/proc.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/pcpu.h>
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#include <sys/smp.h>
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#include <sys/sysctl.h>
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#include <machine/smp.h>
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volatile u_int stopped_cpus;
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volatile u_int started_cpus;
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void (*cpustop_restartfunc) __P((void));
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int mp_ncpus;
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volatile int smp_started;
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u_int all_cpus;
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u_int mp_maxid;
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SYSCTL_NODE(_kern, OID_AUTO, smp, CTLFLAG_RD, NULL, "Kernel SMP");
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int smp_active = 0; /* are the APs allowed to run? */
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SYSCTL_INT(_kern_smp, OID_AUTO, active, CTLFLAG_RW, &smp_active, 0, "");
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int smp_cpus = 1; /* how many cpu's running */
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SYSCTL_INT(_kern_smp, OID_AUTO, cpus, CTLFLAG_RD, &smp_cpus, 0, "");
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/* Enable forwarding of a signal to a process running on a different CPU */
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static int forward_signal_enabled = 1;
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SYSCTL_INT(_kern_smp, OID_AUTO, forward_signal_enabled, CTLFLAG_RW,
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&forward_signal_enabled, 0, "");
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/* Enable forwarding of roundrobin to all other cpus */
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static int forward_roundrobin_enabled = 1;
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SYSCTL_INT(_kern_smp, OID_AUTO, forward_roundrobin_enabled, CTLFLAG_RW,
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&forward_roundrobin_enabled, 0, "");
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/* Variables needed for SMP rendezvous. */
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static void (*smp_rv_setup_func)(void *arg);
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static void (*smp_rv_action_func)(void *arg);
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static void (*smp_rv_teardown_func)(void *arg);
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static void *smp_rv_func_arg;
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static volatile int smp_rv_waiters[2];
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static struct mtx smp_rv_mtx;
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static int mp_probe_status;
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/*
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* Initialize MI SMP variables.
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*/
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static void
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mp_probe(void *dummy)
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{
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mp_probe_status = cpu_mp_probe();
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}
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SYSINIT(cpu_mp_probe, SI_SUB_TUNABLES, SI_ORDER_FIRST, mp_probe, NULL);
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/*
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* Call the MD SMP initialization code.
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*/
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static void
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mp_start(void *dummy)
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{
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/* Probe for MP hardware. */
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if (mp_probe_status == 0)
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return;
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mtx_init(&smp_rv_mtx, "smp rendezvous", MTX_SPIN);
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cpu_mp_start();
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printf("FreeBSD/SMP: Multiprocessor System Detected: %d CPUs\n",
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mp_ncpus);
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cpu_mp_announce();
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}
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SYSINIT(cpu_mp, SI_SUB_CPU, SI_ORDER_SECOND, mp_start, NULL)
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void
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forward_signal(struct thread *td)
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{
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int id;
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/*
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* signotify() has already set PS_ASTPENDING on this process so all
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* we need to do is poke it if it is currently executing so that it
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* executes ast().
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*/
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mtx_assert(&sched_lock, MA_OWNED);
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KASSERT(td->td_proc->p_stat == SRUN, ("forward_signal: process is not SRUN"));
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CTR1(KTR_SMP, "forward_signal(%p)", td->td_proc);
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if (!smp_started || cold || panicstr)
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return;
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if (!forward_signal_enabled)
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return;
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/* No need to IPI ourself. */
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if (td == curthread)
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return;
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id = td->td_kse->ke_oncpu;
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if (id == NOCPU)
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return;
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ipi_selected(1 << id, IPI_AST);
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}
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void
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forward_roundrobin(void)
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{
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struct pcpu *pc;
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struct thread *td;
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u_int id, map;
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mtx_assert(&sched_lock, MA_OWNED);
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CTR0(KTR_SMP, "forward_roundrobin()");
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if (!smp_started || cold || panicstr)
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return;
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if (!forward_roundrobin_enabled)
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return;
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map = 0;
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SLIST_FOREACH(pc, &cpuhead, pc_allcpu) {
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td = pc->pc_curthread;
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id = pc->pc_cpumask;
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if (id != PCPU_GET(cpumask) && (id & stopped_cpus) == 0 &&
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td != pc->pc_idlethread) {
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td->td_kse->ke_flags |= KEF_NEEDRESCHED;
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map |= id;
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}
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}
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ipi_selected(map, IPI_AST);
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}
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/*
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* When called the executing CPU will send an IPI to all other CPUs
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* requesting that they halt execution.
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*
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* Usually (but not necessarily) called with 'other_cpus' as its arg.
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*
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* - Signals all CPUs in map to stop.
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* - Waits for each to stop.
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*
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* Returns:
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* -1: error
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* 0: NA
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* 1: ok
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*
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* XXX FIXME: this is not MP-safe, needs a lock to prevent multiple CPUs
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* from executing at same time.
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*/
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int
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stop_cpus(u_int map)
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{
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int i;
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if (!smp_started)
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return 0;
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CTR1(KTR_SMP, "stop_cpus(%x)", map);
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/* send the stop IPI to all CPUs in map */
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ipi_selected(map, IPI_STOP);
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i = 0;
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while ((atomic_load_acq_int(&stopped_cpus) & map) != map) {
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/* spin */
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i++;
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#ifdef DIAGNOSTIC
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if (i == 100000) {
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printf("timeout stopping cpus\n");
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break;
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}
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#endif
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}
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return 1;
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}
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/*
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* Called by a CPU to restart stopped CPUs.
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*
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* Usually (but not necessarily) called with 'stopped_cpus' as its arg.
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*
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* - Signals all CPUs in map to restart.
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* - Waits for each to restart.
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*
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* Returns:
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* -1: error
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* 0: NA
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* 1: ok
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*/
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int
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restart_cpus(u_int map)
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{
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if (!smp_started)
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return 0;
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CTR1(KTR_SMP, "restart_cpus(%x)", map);
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/* signal other cpus to restart */
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atomic_store_rel_int(&started_cpus, map);
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/* wait for each to clear its bit */
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while ((atomic_load_acq_int(&stopped_cpus) & map) != 0)
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; /* nothing */
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return 1;
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}
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/*
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* All-CPU rendezvous. CPUs are signalled, all execute the setup function
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* (if specified), rendezvous, execute the action function (if specified),
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* rendezvous again, execute the teardown function (if specified), and then
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* resume.
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*
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* Note that the supplied external functions _must_ be reentrant and aware
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* that they are running in parallel and in an unknown lock context.
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*/
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void
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smp_rendezvous_action(void)
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{
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/* setup function */
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if (smp_rv_setup_func != NULL)
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smp_rv_setup_func(smp_rv_func_arg);
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/* spin on entry rendezvous */
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atomic_add_int(&smp_rv_waiters[0], 1);
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while (atomic_load_acq_int(&smp_rv_waiters[0]) < mp_ncpus)
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; /* nothing */
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/* action function */
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if (smp_rv_action_func != NULL)
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smp_rv_action_func(smp_rv_func_arg);
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/* spin on exit rendezvous */
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atomic_add_int(&smp_rv_waiters[1], 1);
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while (atomic_load_acq_int(&smp_rv_waiters[1]) < mp_ncpus)
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; /* nothing */
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/* teardown function */
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if (smp_rv_teardown_func != NULL)
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smp_rv_teardown_func(smp_rv_func_arg);
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}
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void
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smp_rendezvous(void (* setup_func)(void *),
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void (* action_func)(void *),
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void (* teardown_func)(void *),
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void *arg)
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{
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if (!smp_started) {
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if (setup_func != NULL)
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setup_func(arg);
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if (action_func != NULL)
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action_func(arg);
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if (teardown_func != NULL)
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teardown_func(arg);
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return;
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}
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/* obtain rendezvous lock */
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mtx_lock_spin(&smp_rv_mtx);
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/* set static function pointers */
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smp_rv_setup_func = setup_func;
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smp_rv_action_func = action_func;
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smp_rv_teardown_func = teardown_func;
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smp_rv_func_arg = arg;
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smp_rv_waiters[0] = 0;
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smp_rv_waiters[1] = 0;
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/* signal other processors, which will enter the IPI with interrupts off */
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ipi_all_but_self(IPI_RENDEZVOUS);
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/* call executor function */
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smp_rendezvous_action();
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/* release lock */
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mtx_unlock_spin(&smp_rv_mtx);
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}
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