/*- * Copyright (c) 2001, John Baldwin . * 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. * 3. 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 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. */ /* * This module holds the global variables and machine independent functions * used for the kernel SMP support. */ #include __FBSDID("$FreeBSD$"); #include #include #include #include #include #include #include #include #include #include #include #include #include #include "opt_sched.h" #ifdef SMP volatile cpuset_t stopped_cpus; volatile cpuset_t started_cpus; cpuset_t hlt_cpus_mask; cpuset_t logical_cpus_mask; void (*cpustop_restartfunc)(void); #endif /* This is used in modules that need to work in both SMP and UP. */ cpuset_t all_cpus; int mp_ncpus; /* export this for libkvm consumers. */ int mp_maxcpus = MAXCPU; volatile int smp_started; u_int mp_maxid; SYSCTL_NODE(_kern, OID_AUTO, smp, CTLFLAG_RD, NULL, "Kernel SMP"); SYSCTL_UINT(_kern_smp, OID_AUTO, maxid, CTLFLAG_RD, &mp_maxid, 0, "Max CPU ID."); SYSCTL_INT(_kern_smp, OID_AUTO, maxcpus, CTLFLAG_RD, &mp_maxcpus, 0, "Max number of CPUs that the system was compiled for."); 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_RDTUN, &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"); int smp_topology = 0; /* Which topology we're using. */ SYSCTL_INT(_kern_smp, OID_AUTO, topology, CTLFLAG_RD, &smp_topology, 0, "Topology override setting; 0 is default provided by hardware."); TUNABLE_INT("kern.smp.topology", &smp_topology); #ifdef SMP /* 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"); /* Variables needed for SMP rendezvous. */ static volatile int smp_rv_ncpus; static void (*volatile smp_rv_setup_func)(void *arg); static void (*volatile smp_rv_action_func)(void *arg); static void (*volatile smp_rv_teardown_func)(void *arg); static void *volatile smp_rv_func_arg; static volatile int smp_rv_waiters[3]; static volatile int smp_rv_generation; /* * Shared mutex to restrict busywaits between smp_rendezvous() and * smp(_targeted)_tlb_shootdown(). A deadlock occurs if both of these * functions trigger at once and cause multiple CPUs to busywait with * interrupts disabled. */ struct mtx smp_ipi_mtx; /* * Let the MD SMP code initialize mp_maxid very early if it can. */ static void mp_setmaxid(void *dummy) { cpu_mp_setmaxid(); } SYSINIT(cpu_mp_setmaxid, SI_SUB_TUNABLES, SI_ORDER_FIRST, mp_setmaxid, NULL); /* * Call the MD SMP initialization code. */ static void mp_start(void *dummy) { mtx_init(&smp_ipi_mtx, "smp rendezvous", NULL, MTX_SPIN); /* Probe for MP hardware. */ if (smp_disabled != 0 || cpu_mp_probe() == 0) { mp_ncpus = 1; all_cpus = PCPU_GET(cpumask); return; } 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_THIRD, 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(). */ THREAD_LOCK_ASSERT(td, 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_cpu(id, 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 * */ static int generic_stop_cpus(cpuset_t map, u_int type) { #ifdef KTR char cpusetbuf[CPUSETBUFSIZ]; #endif static volatile u_int stopping_cpu = NOCPU; int i; KASSERT( #if defined(__amd64__) type == IPI_STOP || type == IPI_STOP_HARD || type == IPI_SUSPEND, #else type == IPI_STOP || type == IPI_STOP_HARD, #endif ("%s: invalid stop type", __func__)); if (!smp_started) return (0); CTR2(KTR_SMP, "stop_cpus(%s) with %u type", cpusetobj_strprint(cpusetbuf, &map), type); if (stopping_cpu != PCPU_GET(cpuid)) while (atomic_cmpset_int(&stopping_cpu, NOCPU, PCPU_GET(cpuid)) == 0) while (stopping_cpu != NOCPU) cpu_spinwait(); /* spin */ /* send the stop IPI to all CPUs in map */ ipi_selected(map, type); i = 0; while (!CPU_SUBSET(&stopped_cpus, &map)) { /* spin */ cpu_spinwait(); i++; #ifdef DIAGNOSTIC if (i == 100000) { printf("timeout stopping cpus\n"); break; } #endif } stopping_cpu = NOCPU; return (1); } int stop_cpus(cpuset_t map) { return (generic_stop_cpus(map, IPI_STOP)); } int stop_cpus_hard(cpuset_t map) { return (generic_stop_cpus(map, IPI_STOP_HARD)); } #if defined(__amd64__) int suspend_cpus(cpuset_t map) { return (generic_stop_cpus(map, IPI_SUSPEND)); } #endif /* * 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(cpuset_t map) { #ifdef KTR char cpusetbuf[CPUSETBUFSIZ]; #endif if (!smp_started) return 0; CTR1(KTR_SMP, "restart_cpus(%s)", cpusetobj_strprint(cpusetbuf, &map)); /* signal other cpus to restart */ CPU_COPY_STORE_REL(&map, &started_cpus); /* wait for each to clear its bit */ while (CPU_OVERLAP(&stopped_cpus, &map)) cpu_spinwait(); 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) { struct thread *td; void *local_func_arg; void (*local_setup_func)(void*); void (*local_action_func)(void*); void (*local_teardown_func)(void*); int generation; #ifdef INVARIANTS int owepreempt; #endif /* Ensure we have up-to-date values. */ atomic_add_acq_int(&smp_rv_waiters[0], 1); while (smp_rv_waiters[0] < smp_rv_ncpus) cpu_spinwait(); /* Fetch rendezvous parameters after acquire barrier. */ local_func_arg = smp_rv_func_arg; local_setup_func = smp_rv_setup_func; local_action_func = smp_rv_action_func; local_teardown_func = smp_rv_teardown_func; generation = smp_rv_generation; /* * Use a nested critical section to prevent any preemptions * from occurring during a rendezvous action routine. * Specifically, if a rendezvous handler is invoked via an IPI * and the interrupted thread was in the critical_exit() * function after setting td_critnest to 0 but before * performing a deferred preemption, this routine can be * invoked with td_critnest set to 0 and td_owepreempt true. * In that case, a critical_exit() during the rendezvous * action would trigger a preemption which is not permitted in * a rendezvous action. To fix this, wrap all of the * rendezvous action handlers in a critical section. We * cannot use a regular critical section however as having * critical_exit() preempt from this routine would also be * problematic (the preemption must not occur before the IPI * has been acknowledged via an EOI). Instead, we * intentionally ignore td_owepreempt when leaving the * critical section. This should be harmless because we do * not permit rendezvous action routines to schedule threads, * and thus td_owepreempt should never transition from 0 to 1 * during this routine. */ td = curthread; td->td_critnest++; #ifdef INVARIANTS owepreempt = td->td_owepreempt; #endif /* * If requested, run a setup function before the main action * function. Ensure all CPUs have completed the setup * function before moving on to the action function. */ if (local_setup_func != smp_no_rendevous_barrier) { if (smp_rv_setup_func != NULL) smp_rv_setup_func(smp_rv_func_arg); atomic_add_int(&smp_rv_waiters[1], 1); while (smp_rv_waiters[1] < smp_rv_ncpus) cpu_spinwait(); } if (local_action_func != NULL) local_action_func(local_func_arg); /* * Signal that the main action has been completed. If a * full exit rendezvous is requested, then all CPUs will * wait here until all CPUs have finished the main action. * * Note that the write by the last CPU to finish the action * may become visible to different CPUs at different times. * As a result, the CPU that initiated the rendezvous may * exit the rendezvous and drop the lock allowing another * rendezvous to be initiated on the same CPU or a different * CPU. In that case the exit sentinel may be cleared before * all CPUs have noticed causing those CPUs to hang forever. * Workaround this by using a generation count to notice when * this race occurs and to exit the rendezvous in that case. */ MPASS(generation == smp_rv_generation); atomic_add_int(&smp_rv_waiters[2], 1); if (local_teardown_func != smp_no_rendevous_barrier) { while (smp_rv_waiters[2] < smp_rv_ncpus && generation == smp_rv_generation) cpu_spinwait(); if (local_teardown_func != NULL) local_teardown_func(local_func_arg); } td->td_critnest--; KASSERT(owepreempt == td->td_owepreempt, ("rendezvous action changed td_owepreempt")); } void smp_rendezvous_cpus(cpuset_t map, void (* setup_func)(void *), void (* action_func)(void *), void (* teardown_func)(void *), void *arg) { int curcpumap, i, ncpus = 0; 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; } CPU_FOREACH(i) { if (CPU_ISSET(i, &map)) ncpus++; } if (ncpus == 0) panic("ncpus is 0 with non-zero map"); mtx_lock_spin(&smp_ipi_mtx); atomic_add_acq_int(&smp_rv_generation, 1); /* Pass rendezvous parameters via global variables. */ smp_rv_ncpus = ncpus; 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[1] = 0; smp_rv_waiters[2] = 0; atomic_store_rel_int(&smp_rv_waiters[0], 0); /* * Signal other processors, which will enter the IPI with * interrupts off. */ curcpumap = CPU_ISSET(curcpu, &map); CPU_CLR(curcpu, &map); ipi_selected(map, IPI_RENDEZVOUS); /* Check if the current CPU is in the map */ if (curcpumap != 0) smp_rendezvous_action(); /* * If the caller did not request an exit barrier to be enforced * on each CPU, ensure that this CPU waits for all the other * CPUs to finish the rendezvous. */ if (teardown_func == smp_no_rendevous_barrier) while (atomic_load_acq_int(&smp_rv_waiters[2]) < ncpus) cpu_spinwait(); mtx_unlock_spin(&smp_ipi_mtx); } void smp_rendezvous(void (* setup_func)(void *), void (* action_func)(void *), void (* teardown_func)(void *), void *arg) { smp_rendezvous_cpus(all_cpus, setup_func, action_func, teardown_func, arg); } static struct cpu_group group[MAXCPU]; struct cpu_group * smp_topo(void) { char cpusetbuf[CPUSETBUFSIZ], cpusetbuf2[CPUSETBUFSIZ]; struct cpu_group *top; /* * Check for a fake topology request for debugging purposes. */ switch (smp_topology) { case 1: /* Dual core with no sharing. */ top = smp_topo_1level(CG_SHARE_NONE, 2, 0); break; case 2: /* No topology, all cpus are equal. */ top = smp_topo_none(); break; case 3: /* Dual core with shared L2. */ top = smp_topo_1level(CG_SHARE_L2, 2, 0); break; case 4: /* quad core, shared l3 among each package, private l2. */ top = smp_topo_1level(CG_SHARE_L3, 4, 0); break; case 5: /* quad core, 2 dualcore parts on each package share l2. */ top = smp_topo_2level(CG_SHARE_NONE, 2, CG_SHARE_L2, 2, 0); break; case 6: /* Single-core 2xHTT */ top = smp_topo_1level(CG_SHARE_L1, 2, CG_FLAG_HTT); break; case 7: /* quad core with a shared l3, 8 threads sharing L2. */ top = smp_topo_2level(CG_SHARE_L3, 4, CG_SHARE_L2, 8, CG_FLAG_SMT); break; default: /* Default, ask the system what it wants. */ top = cpu_topo(); break; } /* * Verify the returned topology. */ if (top->cg_count != mp_ncpus) panic("Built bad topology at %p. CPU count %d != %d", top, top->cg_count, mp_ncpus); if (CPU_CMP(&top->cg_mask, &all_cpus)) panic("Built bad topology at %p. CPU mask (%s) != (%s)", top, cpusetobj_strprint(cpusetbuf, &top->cg_mask), cpusetobj_strprint(cpusetbuf2, &all_cpus)); return (top); } struct cpu_group * smp_topo_none(void) { struct cpu_group *top; top = &group[0]; top->cg_parent = NULL; top->cg_child = NULL; top->cg_mask = all_cpus; top->cg_count = mp_ncpus; top->cg_children = 0; top->cg_level = CG_SHARE_NONE; top->cg_flags = 0; return (top); } static int smp_topo_addleaf(struct cpu_group *parent, struct cpu_group *child, int share, int count, int flags, int start) { char cpusetbuf[CPUSETBUFSIZ], cpusetbuf2[CPUSETBUFSIZ]; cpuset_t mask; int i; CPU_ZERO(&mask); for (i = 0; i < count; i++, start++) CPU_SET(start, &mask); child->cg_parent = parent; child->cg_child = NULL; child->cg_children = 0; child->cg_level = share; child->cg_count = count; child->cg_flags = flags; child->cg_mask = mask; parent->cg_children++; for (; parent != NULL; parent = parent->cg_parent) { if (CPU_OVERLAP(&parent->cg_mask, &child->cg_mask)) panic("Duplicate children in %p. mask (%s) child (%s)", parent, cpusetobj_strprint(cpusetbuf, &parent->cg_mask), cpusetobj_strprint(cpusetbuf2, &child->cg_mask)); CPU_OR(&parent->cg_mask, &child->cg_mask); parent->cg_count += child->cg_count; } return (start); } struct cpu_group * smp_topo_1level(int share, int count, int flags) { struct cpu_group *child; struct cpu_group *top; int packages; int cpu; int i; cpu = 0; top = &group[0]; packages = mp_ncpus / count; top->cg_child = child = &group[1]; top->cg_level = CG_SHARE_NONE; for (i = 0; i < packages; i++, child++) cpu = smp_topo_addleaf(top, child, share, count, flags, cpu); return (top); } struct cpu_group * smp_topo_2level(int l2share, int l2count, int l1share, int l1count, int l1flags) { struct cpu_group *top; struct cpu_group *l1g; struct cpu_group *l2g; int cpu; int i; int j; cpu = 0; top = &group[0]; l2g = &group[1]; top->cg_child = l2g; top->cg_level = CG_SHARE_NONE; top->cg_children = mp_ncpus / (l2count * l1count); l1g = l2g + top->cg_children; for (i = 0; i < top->cg_children; i++, l2g++) { l2g->cg_parent = top; l2g->cg_child = l1g; l2g->cg_level = l2share; for (j = 0; j < l2count; j++, l1g++) cpu = smp_topo_addleaf(l2g, l1g, l1share, l1count, l1flags, cpu); } return (top); } struct cpu_group * smp_topo_find(struct cpu_group *top, int cpu) { struct cpu_group *cg; cpuset_t mask; int children; int i; CPU_SETOF(cpu, &mask); cg = top; for (;;) { if (!CPU_OVERLAP(&cg->cg_mask, &mask)) return (NULL); if (cg->cg_children == 0) return (cg); children = cg->cg_children; for (i = 0, cg = cg->cg_child; i < children; cg++, i++) if (CPU_OVERLAP(&cg->cg_mask, &mask)) break; } return (NULL); } #else /* !SMP */ void smp_rendezvous_cpus(cpuset_t map, void (*setup_func)(void *), void (*action_func)(void *), void (*teardown_func)(void *), void *arg) { if (setup_func != NULL) setup_func(arg); if (action_func != NULL) action_func(arg); if (teardown_func != NULL) teardown_func(arg); } void smp_rendezvous(void (*setup_func)(void *), void (*action_func)(void *), void (*teardown_func)(void *), void *arg) { if (setup_func != NULL) setup_func(arg); if (action_func != NULL) action_func(arg); if (teardown_func != NULL) teardown_func(arg); } /* * Provide dummy SMP support for UP kernels. Modules that need to use SMP * APIs will still work using this dummy support. */ static void mp_setvariables_for_up(void *dummy) { mp_ncpus = 1; mp_maxid = PCPU_GET(cpuid); all_cpus = PCPU_GET(cpumask); KASSERT(PCPU_GET(cpuid) == 0, ("UP must have a CPU ID of zero")); } SYSINIT(cpu_mp_setvariables, SI_SUB_TUNABLES, SI_ORDER_FIRST, mp_setvariables_for_up, NULL); #endif /* SMP */ void smp_no_rendevous_barrier(void *dummy) { #ifdef SMP KASSERT((!smp_started),("smp_no_rendevous called and smp is started")); #endif }