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