subr_smp.c revision 331910
1/*- 2 * Copyright (c) 2001, John Baldwin <jhb@FreeBSD.org>. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27/* 28 * This module holds the global variables and machine independent functions 29 * used for the kernel SMP support. 30 */ 31 32#include <sys/cdefs.h> 33__FBSDID("$FreeBSD: stable/10/sys/kern/subr_smp.c 331910 2018-04-03 07:52:06Z avg $"); 34 35#include <sys/param.h> 36#include <sys/systm.h> 37#include <sys/kernel.h> 38#include <sys/ktr.h> 39#include <sys/proc.h> 40#include <sys/bus.h> 41#include <sys/lock.h> 42#include <sys/mutex.h> 43#include <sys/pcpu.h> 44#include <sys/sched.h> 45#include <sys/smp.h> 46#include <sys/sysctl.h> 47 48#include <machine/cpu.h> 49#include <machine/smp.h> 50 51#include "opt_sched.h" 52 53#ifdef SMP 54volatile cpuset_t stopped_cpus; 55volatile cpuset_t started_cpus; 56volatile cpuset_t suspended_cpus; 57cpuset_t hlt_cpus_mask; 58cpuset_t logical_cpus_mask; 59 60void (*cpustop_restartfunc)(void); 61#endif 62 63static int sysctl_kern_smp_active(SYSCTL_HANDLER_ARGS); 64 65/* This is used in modules that need to work in both SMP and UP. */ 66cpuset_t all_cpus; 67 68int mp_ncpus; 69/* export this for libkvm consumers. */ 70int mp_maxcpus = MAXCPU; 71 72volatile int smp_started; 73u_int mp_maxid; 74 75static SYSCTL_NODE(_kern, OID_AUTO, smp, CTLFLAG_RD|CTLFLAG_CAPRD, NULL, 76 "Kernel SMP"); 77 78SYSCTL_INT(_kern_smp, OID_AUTO, maxid, CTLFLAG_RD|CTLFLAG_CAPRD, &mp_maxid, 0, 79 "Max CPU ID."); 80 81SYSCTL_INT(_kern_smp, OID_AUTO, maxcpus, CTLFLAG_RD|CTLFLAG_CAPRD, &mp_maxcpus, 82 0, "Max number of CPUs that the system was compiled for."); 83 84SYSCTL_PROC(_kern_smp, OID_AUTO, active, CTLFLAG_RD | CTLTYPE_INT, NULL, 0, 85 sysctl_kern_smp_active, "I", "Indicates system is running in SMP mode"); 86 87int smp_disabled = 0; /* has smp been disabled? */ 88SYSCTL_INT(_kern_smp, OID_AUTO, disabled, CTLFLAG_RDTUN|CTLFLAG_CAPRD, 89 &smp_disabled, 0, "SMP has been disabled from the loader"); 90TUNABLE_INT("kern.smp.disabled", &smp_disabled); 91 92int smp_cpus = 1; /* how many cpu's running */ 93SYSCTL_INT(_kern_smp, OID_AUTO, cpus, CTLFLAG_RD|CTLFLAG_CAPRD, &smp_cpus, 0, 94 "Number of CPUs online"); 95 96int smp_topology = 0; /* Which topology we're using. */ 97SYSCTL_INT(_kern_smp, OID_AUTO, topology, CTLFLAG_RD, &smp_topology, 0, 98 "Topology override setting; 0 is default provided by hardware."); 99TUNABLE_INT("kern.smp.topology", &smp_topology); 100 101#ifdef SMP 102/* Enable forwarding of a signal to a process running on a different CPU */ 103static int forward_signal_enabled = 1; 104SYSCTL_INT(_kern_smp, OID_AUTO, forward_signal_enabled, CTLFLAG_RW, 105 &forward_signal_enabled, 0, 106 "Forwarding of a signal to a process on a different CPU"); 107 108/* Variables needed for SMP rendezvous. */ 109static volatile int smp_rv_ncpus; 110static void (*volatile smp_rv_setup_func)(void *arg); 111static void (*volatile smp_rv_action_func)(void *arg); 112static void (*volatile smp_rv_teardown_func)(void *arg); 113static void *volatile smp_rv_func_arg; 114static volatile int smp_rv_waiters[4]; 115 116/* 117 * Shared mutex to restrict busywaits between smp_rendezvous() and 118 * smp(_targeted)_tlb_shootdown(). A deadlock occurs if both of these 119 * functions trigger at once and cause multiple CPUs to busywait with 120 * interrupts disabled. 121 */ 122struct mtx smp_ipi_mtx; 123 124/* 125 * Let the MD SMP code initialize mp_maxid very early if it can. 126 */ 127static void 128mp_setmaxid(void *dummy) 129{ 130 cpu_mp_setmaxid(); 131} 132SYSINIT(cpu_mp_setmaxid, SI_SUB_TUNABLES, SI_ORDER_FIRST, mp_setmaxid, NULL); 133 134/* 135 * Call the MD SMP initialization code. 136 */ 137static void 138mp_start(void *dummy) 139{ 140 141 mtx_init(&smp_ipi_mtx, "smp rendezvous", NULL, MTX_SPIN); 142 143 /* Probe for MP hardware. */ 144 if (smp_disabled != 0 || cpu_mp_probe() == 0) { 145 mp_ncpus = 1; 146 CPU_SETOF(PCPU_GET(cpuid), &all_cpus); 147 return; 148 } 149 150 cpu_mp_start(); 151 printf("FreeBSD/SMP: Multiprocessor System Detected: %d CPUs\n", 152 mp_ncpus); 153 cpu_mp_announce(); 154} 155SYSINIT(cpu_mp, SI_SUB_CPU, SI_ORDER_THIRD, mp_start, NULL); 156 157void 158forward_signal(struct thread *td) 159{ 160 int id; 161 162 /* 163 * signotify() has already set TDF_ASTPENDING and TDF_NEEDSIGCHECK on 164 * this thread, so all we need to do is poke it if it is currently 165 * executing so that it executes ast(). 166 */ 167 THREAD_LOCK_ASSERT(td, MA_OWNED); 168 KASSERT(TD_IS_RUNNING(td), 169 ("forward_signal: thread is not TDS_RUNNING")); 170 171 CTR1(KTR_SMP, "forward_signal(%p)", td->td_proc); 172 173 if (!smp_started || cold || panicstr) 174 return; 175 if (!forward_signal_enabled) 176 return; 177 178 /* No need to IPI ourself. */ 179 if (td == curthread) 180 return; 181 182 id = td->td_oncpu; 183 if (id == NOCPU) 184 return; 185 ipi_cpu(id, IPI_AST); 186} 187 188/* 189 * When called the executing CPU will send an IPI to all other CPUs 190 * requesting that they halt execution. 191 * 192 * Usually (but not necessarily) called with 'other_cpus' as its arg. 193 * 194 * - Signals all CPUs in map to stop. 195 * - Waits for each to stop. 196 * 197 * Returns: 198 * -1: error 199 * 0: NA 200 * 1: ok 201 * 202 */ 203static int 204generic_stop_cpus(cpuset_t map, u_int type) 205{ 206#ifdef KTR 207 char cpusetbuf[CPUSETBUFSIZ]; 208#endif 209 static volatile u_int stopping_cpu = NOCPU; 210 int i; 211 volatile cpuset_t *cpus; 212 213 KASSERT( 214#if defined(__amd64__) || defined(__i386__) 215 type == IPI_STOP || type == IPI_STOP_HARD || type == IPI_SUSPEND, 216#else 217 type == IPI_STOP || type == IPI_STOP_HARD, 218#endif 219 ("%s: invalid stop type", __func__)); 220 221 if (!smp_started) 222 return (0); 223 224 CTR2(KTR_SMP, "stop_cpus(%s) with %u type", 225 cpusetobj_strprint(cpusetbuf, &map), type); 226 227#if defined(__amd64__) || defined(__i386__) 228 /* 229 * When suspending, ensure there are are no IPIs in progress. 230 * IPIs that have been issued, but not yet delivered (e.g. 231 * not pending on a vCPU when running under virtualization) 232 * will be lost, violating FreeBSD's assumption of reliable 233 * IPI delivery. 234 */ 235 if (type == IPI_SUSPEND) 236 mtx_lock_spin(&smp_ipi_mtx); 237#endif 238 239 if (stopping_cpu != PCPU_GET(cpuid)) 240 while (atomic_cmpset_int(&stopping_cpu, NOCPU, 241 PCPU_GET(cpuid)) == 0) 242 while (stopping_cpu != NOCPU) 243 cpu_spinwait(); /* spin */ 244 245 /* send the stop IPI to all CPUs in map */ 246 ipi_selected(map, type); 247 248#if defined(__amd64__) || defined(__i386__) 249 if (type == IPI_SUSPEND) 250 cpus = &suspended_cpus; 251 else 252#endif 253 cpus = &stopped_cpus; 254 255 i = 0; 256 while (!CPU_SUBSET(cpus, &map)) { 257 /* spin */ 258 cpu_spinwait(); 259 i++; 260 if (i == 100000000) { 261 printf("timeout stopping cpus\n"); 262 break; 263 } 264 } 265 266#if defined(__amd64__) || defined(__i386__) 267 if (type == IPI_SUSPEND) 268 mtx_unlock_spin(&smp_ipi_mtx); 269#endif 270 271 stopping_cpu = NOCPU; 272 return (1); 273} 274 275int 276stop_cpus(cpuset_t map) 277{ 278 279 return (generic_stop_cpus(map, IPI_STOP)); 280} 281 282int 283stop_cpus_hard(cpuset_t map) 284{ 285 286 return (generic_stop_cpus(map, IPI_STOP_HARD)); 287} 288 289#if defined(__amd64__) || defined(__i386__) 290int 291suspend_cpus(cpuset_t map) 292{ 293 294 return (generic_stop_cpus(map, IPI_SUSPEND)); 295} 296#endif 297 298/* 299 * Called by a CPU to restart stopped CPUs. 300 * 301 * Usually (but not necessarily) called with 'stopped_cpus' as its arg. 302 * 303 * - Signals all CPUs in map to restart. 304 * - Waits for each to restart. 305 * 306 * Returns: 307 * -1: error 308 * 0: NA 309 * 1: ok 310 */ 311static int 312generic_restart_cpus(cpuset_t map, u_int type) 313{ 314#ifdef KTR 315 char cpusetbuf[CPUSETBUFSIZ]; 316#endif 317 volatile cpuset_t *cpus; 318 319 KASSERT( 320#if defined(__amd64__) || defined(__i386__) 321 type == IPI_STOP || type == IPI_STOP_HARD || type == IPI_SUSPEND, 322#else 323 type == IPI_STOP || type == IPI_STOP_HARD, 324#endif 325 ("%s: invalid stop type", __func__)); 326 327 if (!smp_started) 328 return 0; 329 330 CTR1(KTR_SMP, "restart_cpus(%s)", cpusetobj_strprint(cpusetbuf, &map)); 331 332#if defined(__amd64__) || defined(__i386__) 333 if (type == IPI_SUSPEND) 334 cpus = &resuming_cpus; 335 else 336#endif 337 cpus = &stopped_cpus; 338 339 /* signal other cpus to restart */ 340#if defined(__amd64__) || defined(__i386__) 341 if (type == IPI_SUSPEND) 342 CPU_COPY_STORE_REL(&map, &toresume_cpus); 343 else 344#endif 345 CPU_COPY_STORE_REL(&map, &started_cpus); 346 347 /* wait for each to clear its bit */ 348 while (CPU_OVERLAP(cpus, &map)) 349 cpu_spinwait(); 350 351 return 1; 352} 353 354int 355restart_cpus(cpuset_t map) 356{ 357 358 return (generic_restart_cpus(map, IPI_STOP)); 359} 360 361#if defined(__amd64__) || defined(__i386__) 362int 363resume_cpus(cpuset_t map) 364{ 365 366 return (generic_restart_cpus(map, IPI_SUSPEND)); 367} 368#endif 369 370/* 371 * All-CPU rendezvous. CPUs are signalled, all execute the setup function 372 * (if specified), rendezvous, execute the action function (if specified), 373 * rendezvous again, execute the teardown function (if specified), and then 374 * resume. 375 * 376 * Note that the supplied external functions _must_ be reentrant and aware 377 * that they are running in parallel and in an unknown lock context. 378 */ 379void 380smp_rendezvous_action(void) 381{ 382 struct thread *td; 383 void *local_func_arg; 384 void (*local_setup_func)(void*); 385 void (*local_action_func)(void*); 386 void (*local_teardown_func)(void*); 387#ifdef INVARIANTS 388 int owepreempt; 389#endif 390 391 /* Ensure we have up-to-date values. */ 392 atomic_add_acq_int(&smp_rv_waiters[0], 1); 393 while (smp_rv_waiters[0] < smp_rv_ncpus) 394 cpu_spinwait(); 395 396 /* Fetch rendezvous parameters after acquire barrier. */ 397 local_func_arg = smp_rv_func_arg; 398 local_setup_func = smp_rv_setup_func; 399 local_action_func = smp_rv_action_func; 400 local_teardown_func = smp_rv_teardown_func; 401 402 /* 403 * Use a nested critical section to prevent any preemptions 404 * from occurring during a rendezvous action routine. 405 * Specifically, if a rendezvous handler is invoked via an IPI 406 * and the interrupted thread was in the critical_exit() 407 * function after setting td_critnest to 0 but before 408 * performing a deferred preemption, this routine can be 409 * invoked with td_critnest set to 0 and td_owepreempt true. 410 * In that case, a critical_exit() during the rendezvous 411 * action would trigger a preemption which is not permitted in 412 * a rendezvous action. To fix this, wrap all of the 413 * rendezvous action handlers in a critical section. We 414 * cannot use a regular critical section however as having 415 * critical_exit() preempt from this routine would also be 416 * problematic (the preemption must not occur before the IPI 417 * has been acknowledged via an EOI). Instead, we 418 * intentionally ignore td_owepreempt when leaving the 419 * critical section. This should be harmless because we do 420 * not permit rendezvous action routines to schedule threads, 421 * and thus td_owepreempt should never transition from 0 to 1 422 * during this routine. 423 */ 424 td = curthread; 425 td->td_critnest++; 426#ifdef INVARIANTS 427 owepreempt = td->td_owepreempt; 428#endif 429 430 /* 431 * If requested, run a setup function before the main action 432 * function. Ensure all CPUs have completed the setup 433 * function before moving on to the action function. 434 */ 435 if (local_setup_func != smp_no_rendevous_barrier) { 436 if (smp_rv_setup_func != NULL) 437 smp_rv_setup_func(smp_rv_func_arg); 438 atomic_add_int(&smp_rv_waiters[1], 1); 439 while (smp_rv_waiters[1] < smp_rv_ncpus) 440 cpu_spinwait(); 441 } 442 443 if (local_action_func != NULL) 444 local_action_func(local_func_arg); 445 446 if (local_teardown_func != smp_no_rendevous_barrier) { 447 /* 448 * Signal that the main action has been completed. If a 449 * full exit rendezvous is requested, then all CPUs will 450 * wait here until all CPUs have finished the main action. 451 */ 452 atomic_add_int(&smp_rv_waiters[2], 1); 453 while (smp_rv_waiters[2] < smp_rv_ncpus) 454 cpu_spinwait(); 455 456 if (local_teardown_func != NULL) 457 local_teardown_func(local_func_arg); 458 } 459 460 /* 461 * Signal that the rendezvous is fully completed by this CPU. 462 * This means that no member of smp_rv_* pseudo-structure will be 463 * accessed by this target CPU after this point; in particular, 464 * memory pointed by smp_rv_func_arg. 465 */ 466 atomic_add_int(&smp_rv_waiters[3], 1); 467 468 td->td_critnest--; 469 KASSERT(owepreempt == td->td_owepreempt, 470 ("rendezvous action changed td_owepreempt")); 471} 472 473void 474smp_rendezvous_cpus(cpuset_t map, 475 void (* setup_func)(void *), 476 void (* action_func)(void *), 477 void (* teardown_func)(void *), 478 void *arg) 479{ 480 int curcpumap, i, ncpus = 0; 481 482 /* Look comments in the !SMP case. */ 483 if (!smp_started) { 484 spinlock_enter(); 485 if (setup_func != NULL) 486 setup_func(arg); 487 if (action_func != NULL) 488 action_func(arg); 489 if (teardown_func != NULL) 490 teardown_func(arg); 491 spinlock_exit(); 492 return; 493 } 494 495 CPU_FOREACH(i) { 496 if (CPU_ISSET(i, &map)) 497 ncpus++; 498 } 499 if (ncpus == 0) 500 panic("ncpus is 0 with non-zero map"); 501 502 mtx_lock_spin(&smp_ipi_mtx); 503 504 /* Pass rendezvous parameters via global variables. */ 505 smp_rv_ncpus = ncpus; 506 smp_rv_setup_func = setup_func; 507 smp_rv_action_func = action_func; 508 smp_rv_teardown_func = teardown_func; 509 smp_rv_func_arg = arg; 510 smp_rv_waiters[1] = 0; 511 smp_rv_waiters[2] = 0; 512 smp_rv_waiters[3] = 0; 513 atomic_store_rel_int(&smp_rv_waiters[0], 0); 514 515 /* 516 * Signal other processors, which will enter the IPI with 517 * interrupts off. 518 */ 519 curcpumap = CPU_ISSET(curcpu, &map); 520 CPU_CLR(curcpu, &map); 521 ipi_selected(map, IPI_RENDEZVOUS); 522 523 /* Check if the current CPU is in the map */ 524 if (curcpumap != 0) 525 smp_rendezvous_action(); 526 527 /* 528 * Ensure that the master CPU waits for all the other 529 * CPUs to finish the rendezvous, so that smp_rv_* 530 * pseudo-structure and the arg are guaranteed to not 531 * be in use. 532 */ 533 while (atomic_load_acq_int(&smp_rv_waiters[3]) < ncpus) 534 cpu_spinwait(); 535 536 mtx_unlock_spin(&smp_ipi_mtx); 537} 538 539void 540smp_rendezvous(void (* setup_func)(void *), 541 void (* action_func)(void *), 542 void (* teardown_func)(void *), 543 void *arg) 544{ 545 smp_rendezvous_cpus(all_cpus, setup_func, action_func, teardown_func, arg); 546} 547 548static struct cpu_group group[MAXCPU]; 549 550struct cpu_group * 551smp_topo(void) 552{ 553 char cpusetbuf[CPUSETBUFSIZ], cpusetbuf2[CPUSETBUFSIZ]; 554 struct cpu_group *top; 555 556 /* 557 * Check for a fake topology request for debugging purposes. 558 */ 559 switch (smp_topology) { 560 case 1: 561 /* Dual core with no sharing. */ 562 top = smp_topo_1level(CG_SHARE_NONE, 2, 0); 563 break; 564 case 2: 565 /* No topology, all cpus are equal. */ 566 top = smp_topo_none(); 567 break; 568 case 3: 569 /* Dual core with shared L2. */ 570 top = smp_topo_1level(CG_SHARE_L2, 2, 0); 571 break; 572 case 4: 573 /* quad core, shared l3 among each package, private l2. */ 574 top = smp_topo_1level(CG_SHARE_L3, 4, 0); 575 break; 576 case 5: 577 /* quad core, 2 dualcore parts on each package share l2. */ 578 top = smp_topo_2level(CG_SHARE_NONE, 2, CG_SHARE_L2, 2, 0); 579 break; 580 case 6: 581 /* Single-core 2xHTT */ 582 top = smp_topo_1level(CG_SHARE_L1, 2, CG_FLAG_HTT); 583 break; 584 case 7: 585 /* quad core with a shared l3, 8 threads sharing L2. */ 586 top = smp_topo_2level(CG_SHARE_L3, 4, CG_SHARE_L2, 8, 587 CG_FLAG_SMT); 588 break; 589 default: 590 /* Default, ask the system what it wants. */ 591 top = cpu_topo(); 592 break; 593 } 594 /* 595 * Verify the returned topology. 596 */ 597 if (top->cg_count != mp_ncpus) 598 panic("Built bad topology at %p. CPU count %d != %d", 599 top, top->cg_count, mp_ncpus); 600 if (CPU_CMP(&top->cg_mask, &all_cpus)) 601 panic("Built bad topology at %p. CPU mask (%s) != (%s)", 602 top, cpusetobj_strprint(cpusetbuf, &top->cg_mask), 603 cpusetobj_strprint(cpusetbuf2, &all_cpus)); 604 return (top); 605} 606 607struct cpu_group * 608smp_topo_none(void) 609{ 610 struct cpu_group *top; 611 612 top = &group[0]; 613 top->cg_parent = NULL; 614 top->cg_child = NULL; 615 top->cg_mask = all_cpus; 616 top->cg_count = mp_ncpus; 617 top->cg_children = 0; 618 top->cg_level = CG_SHARE_NONE; 619 top->cg_flags = 0; 620 621 return (top); 622} 623 624static int 625smp_topo_addleaf(struct cpu_group *parent, struct cpu_group *child, int share, 626 int count, int flags, int start) 627{ 628 char cpusetbuf[CPUSETBUFSIZ], cpusetbuf2[CPUSETBUFSIZ]; 629 cpuset_t mask; 630 int i; 631 632 CPU_ZERO(&mask); 633 for (i = 0; i < count; i++, start++) 634 CPU_SET(start, &mask); 635 child->cg_parent = parent; 636 child->cg_child = NULL; 637 child->cg_children = 0; 638 child->cg_level = share; 639 child->cg_count = count; 640 child->cg_flags = flags; 641 child->cg_mask = mask; 642 parent->cg_children++; 643 for (; parent != NULL; parent = parent->cg_parent) { 644 if (CPU_OVERLAP(&parent->cg_mask, &child->cg_mask)) 645 panic("Duplicate children in %p. mask (%s) child (%s)", 646 parent, 647 cpusetobj_strprint(cpusetbuf, &parent->cg_mask), 648 cpusetobj_strprint(cpusetbuf2, &child->cg_mask)); 649 CPU_OR(&parent->cg_mask, &child->cg_mask); 650 parent->cg_count += child->cg_count; 651 } 652 653 return (start); 654} 655 656struct cpu_group * 657smp_topo_1level(int share, int count, int flags) 658{ 659 struct cpu_group *child; 660 struct cpu_group *top; 661 int packages; 662 int cpu; 663 int i; 664 665 cpu = 0; 666 top = &group[0]; 667 packages = mp_ncpus / count; 668 top->cg_child = child = &group[1]; 669 top->cg_level = CG_SHARE_NONE; 670 for (i = 0; i < packages; i++, child++) 671 cpu = smp_topo_addleaf(top, child, share, count, flags, cpu); 672 return (top); 673} 674 675struct cpu_group * 676smp_topo_2level(int l2share, int l2count, int l1share, int l1count, 677 int l1flags) 678{ 679 struct cpu_group *top; 680 struct cpu_group *l1g; 681 struct cpu_group *l2g; 682 int cpu; 683 int i; 684 int j; 685 686 cpu = 0; 687 top = &group[0]; 688 l2g = &group[1]; 689 top->cg_child = l2g; 690 top->cg_level = CG_SHARE_NONE; 691 top->cg_children = mp_ncpus / (l2count * l1count); 692 l1g = l2g + top->cg_children; 693 for (i = 0; i < top->cg_children; i++, l2g++) { 694 l2g->cg_parent = top; 695 l2g->cg_child = l1g; 696 l2g->cg_level = l2share; 697 for (j = 0; j < l2count; j++, l1g++) 698 cpu = smp_topo_addleaf(l2g, l1g, l1share, l1count, 699 l1flags, cpu); 700 } 701 return (top); 702} 703 704 705struct cpu_group * 706smp_topo_find(struct cpu_group *top, int cpu) 707{ 708 struct cpu_group *cg; 709 cpuset_t mask; 710 int children; 711 int i; 712 713 CPU_SETOF(cpu, &mask); 714 cg = top; 715 for (;;) { 716 if (!CPU_OVERLAP(&cg->cg_mask, &mask)) 717 return (NULL); 718 if (cg->cg_children == 0) 719 return (cg); 720 children = cg->cg_children; 721 for (i = 0, cg = cg->cg_child; i < children; cg++, i++) 722 if (CPU_OVERLAP(&cg->cg_mask, &mask)) 723 break; 724 } 725 return (NULL); 726} 727#else /* !SMP */ 728 729void 730smp_rendezvous_cpus(cpuset_t map, 731 void (*setup_func)(void *), 732 void (*action_func)(void *), 733 void (*teardown_func)(void *), 734 void *arg) 735{ 736 /* 737 * In the !SMP case we just need to ensure the same initial conditions 738 * as the SMP case. 739 */ 740 spinlock_enter(); 741 if (setup_func != NULL) 742 setup_func(arg); 743 if (action_func != NULL) 744 action_func(arg); 745 if (teardown_func != NULL) 746 teardown_func(arg); 747 spinlock_exit(); 748} 749 750void 751smp_rendezvous(void (*setup_func)(void *), 752 void (*action_func)(void *), 753 void (*teardown_func)(void *), 754 void *arg) 755{ 756 757 /* Look comments in the smp_rendezvous_cpus() case. */ 758 spinlock_enter(); 759 if (setup_func != NULL) 760 setup_func(arg); 761 if (action_func != NULL) 762 action_func(arg); 763 if (teardown_func != NULL) 764 teardown_func(arg); 765 spinlock_exit(); 766} 767 768/* 769 * Provide dummy SMP support for UP kernels. Modules that need to use SMP 770 * APIs will still work using this dummy support. 771 */ 772static void 773mp_setvariables_for_up(void *dummy) 774{ 775 mp_ncpus = 1; 776 mp_maxid = PCPU_GET(cpuid); 777 CPU_SETOF(mp_maxid, &all_cpus); 778 KASSERT(PCPU_GET(cpuid) == 0, ("UP must have a CPU ID of zero")); 779} 780SYSINIT(cpu_mp_setvariables, SI_SUB_TUNABLES, SI_ORDER_FIRST, 781 mp_setvariables_for_up, NULL); 782#endif /* SMP */ 783 784void 785smp_no_rendevous_barrier(void *dummy) 786{ 787#ifdef SMP 788 KASSERT((!smp_started),("smp_no_rendevous called and smp is started")); 789#endif 790} 791 792/* 793 * Wait specified idle threads to switch once. This ensures that even 794 * preempted threads have cycled through the switch function once, 795 * exiting their codepaths. This allows us to change global pointers 796 * with no other synchronization. 797 */ 798int 799quiesce_cpus(cpuset_t map, const char *wmesg, int prio) 800{ 801 struct pcpu *pcpu; 802 u_int gen[MAXCPU]; 803 int error; 804 int cpu; 805 806 error = 0; 807 for (cpu = 0; cpu <= mp_maxid; cpu++) { 808 if (!CPU_ISSET(cpu, &map) || CPU_ABSENT(cpu)) 809 continue; 810 pcpu = pcpu_find(cpu); 811 gen[cpu] = pcpu->pc_idlethread->td_generation; 812 } 813 for (cpu = 0; cpu <= mp_maxid; cpu++) { 814 if (!CPU_ISSET(cpu, &map) || CPU_ABSENT(cpu)) 815 continue; 816 pcpu = pcpu_find(cpu); 817 thread_lock(curthread); 818 sched_bind(curthread, cpu); 819 thread_unlock(curthread); 820 while (gen[cpu] == pcpu->pc_idlethread->td_generation) { 821 error = tsleep(quiesce_cpus, prio, wmesg, 1); 822 if (error != EWOULDBLOCK) 823 goto out; 824 error = 0; 825 } 826 } 827out: 828 thread_lock(curthread); 829 sched_unbind(curthread); 830 thread_unlock(curthread); 831 832 return (error); 833} 834 835int 836quiesce_all_cpus(const char *wmesg, int prio) 837{ 838 839 return quiesce_cpus(all_cpus, wmesg, prio); 840} 841 842/* Extra care is taken with this sysctl because the data type is volatile */ 843static int 844sysctl_kern_smp_active(SYSCTL_HANDLER_ARGS) 845{ 846 int error, active; 847 848 active = smp_started; 849 error = SYSCTL_OUT(req, &active, sizeof(active)); 850 return (error); 851} 852 853