1 /* $NetBSD: sys_sched.c,v 1.46 2016/07/30 15:38:17 christos Exp $ */ 2 3 /* 4 * Copyright (c) 2008, 2011 Mindaugas Rasiukevicius <rmind at NetBSD org> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 /* 30 * System calls relating to the scheduler. 31 * 32 * Lock order: 33 * 34 * cpu_lock -> 35 * proc_lock -> 36 * proc_t::p_lock -> 37 * lwp_t::lwp_lock 38 * 39 * TODO: 40 * - Handle pthread_setschedprio() as defined by POSIX; 41 * - Handle sched_yield() case for SCHED_FIFO as defined by POSIX; 42 */ 43 44 #include <sys/cdefs.h> 45 __KERNEL_RCSID(0, "$NetBSD: sys_sched.c,v 1.46 2016/07/30 15:38:17 christos Exp $"); 46 47 #include <sys/param.h> 48 49 #include <sys/cpu.h> 50 #include <sys/kauth.h> 51 #include <sys/kmem.h> 52 #include <sys/lwp.h> 53 #include <sys/mutex.h> 54 #include <sys/proc.h> 55 #include <sys/pset.h> 56 #include <sys/sched.h> 57 #include <sys/syscallargs.h> 58 #include <sys/sysctl.h> 59 #include <sys/systm.h> 60 #include <sys/types.h> 61 #include <sys/unistd.h> 62 63 static struct sysctllog *sched_sysctl_log; 64 static kauth_listener_t sched_listener; 65 66 /* 67 * Convert user priority or the in-kernel priority or convert the current 68 * priority to the appropriate range according to the policy change. 69 */ 70 static pri_t 71 convert_pri(lwp_t *l, int policy, pri_t pri) 72 { 73 74 /* Convert user priority to the in-kernel */ 75 if (pri != PRI_NONE) { 76 /* Only for real-time threads */ 77 KASSERT(pri >= SCHED_PRI_MIN && pri <= SCHED_PRI_MAX); 78 KASSERT(policy != SCHED_OTHER); 79 return PRI_USER_RT + pri; 80 } 81 82 /* Neither policy, nor priority change */ 83 if (l->l_class == policy) 84 return l->l_priority; 85 86 /* Time-sharing -> real-time */ 87 if (l->l_class == SCHED_OTHER) { 88 KASSERT(policy == SCHED_FIFO || policy == SCHED_RR); 89 return PRI_USER_RT; 90 } 91 92 /* Real-time -> time-sharing */ 93 if (policy == SCHED_OTHER) { 94 KASSERT(l->l_class == SCHED_FIFO || l->l_class == SCHED_RR); 95 /* 96 * this is a bit arbitrary because the priority is dynamic 97 * for SCHED_OTHER threads and will likely be changed by 98 * the scheduler soon anyway. 99 */ 100 return l->l_priority - PRI_USER_RT; 101 } 102 103 /* Real-time -> real-time */ 104 return l->l_priority; 105 } 106 107 int 108 do_sched_setparam(pid_t pid, lwpid_t lid, int policy, 109 const struct sched_param *params) 110 { 111 struct proc *p; 112 struct lwp *t; 113 pri_t pri; 114 u_int lcnt; 115 int error; 116 117 error = 0; 118 119 pri = params->sched_priority; 120 121 /* If no parameters specified, just return (this should not happen) */ 122 if (pri == PRI_NONE && policy == SCHED_NONE) 123 return 0; 124 125 /* Validate scheduling class */ 126 if (policy != SCHED_NONE && (policy < SCHED_OTHER || policy > SCHED_RR)) 127 return EINVAL; 128 129 /* Validate priority */ 130 if (pri != PRI_NONE && (pri < SCHED_PRI_MIN || pri > SCHED_PRI_MAX)) 131 return EINVAL; 132 133 if (pid != 0) { 134 /* Find the process */ 135 mutex_enter(proc_lock); 136 p = proc_find(pid); 137 if (p == NULL) { 138 mutex_exit(proc_lock); 139 return ESRCH; 140 } 141 mutex_enter(p->p_lock); 142 mutex_exit(proc_lock); 143 /* Disallow modification of system processes */ 144 if ((p->p_flag & PK_SYSTEM) != 0) { 145 mutex_exit(p->p_lock); 146 return EPERM; 147 } 148 } else { 149 /* Use the calling process */ 150 p = curlwp->l_proc; 151 mutex_enter(p->p_lock); 152 } 153 154 /* Find the LWP(s) */ 155 lcnt = 0; 156 LIST_FOREACH(t, &p->p_lwps, l_sibling) { 157 pri_t kpri; 158 int lpolicy; 159 160 if (lid && lid != t->l_lid) 161 continue; 162 163 lcnt++; 164 lwp_lock(t); 165 lpolicy = (policy == SCHED_NONE) ? t->l_class : policy; 166 167 /* Disallow setting of priority for SCHED_OTHER threads */ 168 if (lpolicy == SCHED_OTHER && pri != PRI_NONE) { 169 lwp_unlock(t); 170 error = EINVAL; 171 break; 172 } 173 174 /* Convert priority, if needed */ 175 kpri = convert_pri(t, lpolicy, pri); 176 177 /* Check the permission */ 178 error = kauth_authorize_process(kauth_cred_get(), 179 KAUTH_PROCESS_SCHEDULER_SETPARAM, p, t, KAUTH_ARG(lpolicy), 180 KAUTH_ARG(kpri)); 181 if (error) { 182 lwp_unlock(t); 183 break; 184 } 185 186 /* Set the scheduling class, change the priority */ 187 t->l_class = lpolicy; 188 lwp_changepri(t, kpri); 189 lwp_unlock(t); 190 } 191 mutex_exit(p->p_lock); 192 return (lcnt == 0) ? ESRCH : error; 193 } 194 195 /* 196 * Set scheduling parameters. 197 */ 198 int 199 sys__sched_setparam(struct lwp *l, const struct sys__sched_setparam_args *uap, 200 register_t *retval) 201 { 202 /* { 203 syscallarg(pid_t) pid; 204 syscallarg(lwpid_t) lid; 205 syscallarg(int) policy; 206 syscallarg(const struct sched_param *) params; 207 } */ 208 struct sched_param params; 209 int error; 210 211 /* Get the parameters from the user-space */ 212 error = copyin(SCARG(uap, params), ¶ms, sizeof(params)); 213 if (error) 214 goto out; 215 216 error = do_sched_setparam(SCARG(uap, pid), SCARG(uap, lid), 217 SCARG(uap, policy), ¶ms); 218 out: 219 return error; 220 } 221 222 /* 223 * do_sched_getparam: 224 * 225 * if lid=0, returns the parameter of the first LWP in the process. 226 */ 227 int 228 do_sched_getparam(pid_t pid, lwpid_t lid, int *policy, 229 struct sched_param *params) 230 { 231 struct sched_param lparams; 232 struct lwp *t; 233 int error, lpolicy; 234 235 t = lwp_find2(pid, lid); /* acquire p_lock */ 236 if (t == NULL) 237 return ESRCH; 238 239 /* Check the permission */ 240 error = kauth_authorize_process(kauth_cred_get(), 241 KAUTH_PROCESS_SCHEDULER_GETPARAM, t->l_proc, NULL, NULL, NULL); 242 if (error != 0) { 243 mutex_exit(t->l_proc->p_lock); 244 return error; 245 } 246 247 lwp_lock(t); 248 lparams.sched_priority = t->l_priority; 249 lpolicy = t->l_class; 250 lwp_unlock(t); 251 mutex_exit(t->l_proc->p_lock); 252 253 /* 254 * convert to the user-visible priority value. 255 * it's an inversion of convert_pri(). 256 * 257 * the SCHED_OTHER case is a bit arbitrary given that 258 * - we don't allow setting the priority. 259 * - the priority is dynamic. 260 */ 261 switch (lpolicy) { 262 case SCHED_OTHER: 263 lparams.sched_priority -= PRI_USER; 264 break; 265 case SCHED_RR: 266 case SCHED_FIFO: 267 lparams.sched_priority -= PRI_USER_RT; 268 break; 269 } 270 271 if (policy != NULL) 272 *policy = lpolicy; 273 274 if (params != NULL) 275 *params = lparams; 276 277 return error; 278 } 279 280 /* 281 * Get scheduling parameters. 282 */ 283 int 284 sys__sched_getparam(struct lwp *l, const struct sys__sched_getparam_args *uap, 285 register_t *retval) 286 { 287 /* { 288 syscallarg(pid_t) pid; 289 syscallarg(lwpid_t) lid; 290 syscallarg(int *) policy; 291 syscallarg(struct sched_param *) params; 292 } */ 293 struct sched_param params; 294 int error, policy; 295 296 error = do_sched_getparam(SCARG(uap, pid), SCARG(uap, lid), &policy, 297 ¶ms); 298 if (error) 299 goto out; 300 301 error = copyout(¶ms, SCARG(uap, params), sizeof(params)); 302 if (error == 0 && SCARG(uap, policy) != NULL) 303 error = copyout(&policy, SCARG(uap, policy), sizeof(int)); 304 out: 305 return error; 306 } 307 308 /* 309 * Allocate the CPU set, and get it from userspace. 310 */ 311 static int 312 genkcpuset(kcpuset_t **dset, const cpuset_t *sset, size_t size) 313 { 314 kcpuset_t *kset; 315 int error; 316 317 kcpuset_create(&kset, true); 318 error = kcpuset_copyin(sset, kset, size); 319 if (error) { 320 kcpuset_unuse(kset, NULL); 321 } else { 322 *dset = kset; 323 } 324 return error; 325 } 326 327 /* 328 * Set affinity. 329 */ 330 int 331 sys__sched_setaffinity(struct lwp *l, 332 const struct sys__sched_setaffinity_args *uap, register_t *retval) 333 { 334 /* { 335 syscallarg(pid_t) pid; 336 syscallarg(lwpid_t) lid; 337 syscallarg(size_t) size; 338 syscallarg(const cpuset_t *) cpuset; 339 } */ 340 kcpuset_t *kcset, *kcpulst = NULL; 341 struct cpu_info *ici, *ci; 342 struct proc *p; 343 struct lwp *t; 344 CPU_INFO_ITERATOR cii; 345 bool alloff; 346 lwpid_t lid; 347 u_int lcnt; 348 int error; 349 350 error = genkcpuset(&kcset, SCARG(uap, cpuset), SCARG(uap, size)); 351 if (error) 352 return error; 353 354 /* 355 * Traverse _each_ CPU to: 356 * - Check that CPUs in the mask have no assigned processor set. 357 * - Check that at least one CPU from the mask is online. 358 * - Find the first target CPU to migrate. 359 * 360 * To avoid the race with CPU online/offline calls and processor sets, 361 * cpu_lock will be locked for the entire operation. 362 */ 363 ci = NULL; 364 alloff = false; 365 mutex_enter(&cpu_lock); 366 for (CPU_INFO_FOREACH(cii, ici)) { 367 struct schedstate_percpu *ispc; 368 369 if (!kcpuset_isset(kcset, cpu_index(ici))) { 370 continue; 371 } 372 373 ispc = &ici->ci_schedstate; 374 /* Check that CPU is not in the processor-set */ 375 if (ispc->spc_psid != PS_NONE) { 376 error = EPERM; 377 goto out; 378 } 379 /* Skip offline CPUs */ 380 if (ispc->spc_flags & SPCF_OFFLINE) { 381 alloff = true; 382 continue; 383 } 384 /* Target CPU to migrate */ 385 if (ci == NULL) { 386 ci = ici; 387 } 388 } 389 if (ci == NULL) { 390 if (alloff) { 391 /* All CPUs in the set are offline */ 392 error = EPERM; 393 goto out; 394 } 395 /* Empty set */ 396 kcpuset_unuse(kcset, &kcpulst); 397 kcset = NULL; 398 } 399 400 if (SCARG(uap, pid) != 0) { 401 /* Find the process */ 402 mutex_enter(proc_lock); 403 p = proc_find(SCARG(uap, pid)); 404 if (p == NULL) { 405 mutex_exit(proc_lock); 406 error = ESRCH; 407 goto out; 408 } 409 mutex_enter(p->p_lock); 410 mutex_exit(proc_lock); 411 /* Disallow modification of system processes. */ 412 if ((p->p_flag & PK_SYSTEM) != 0) { 413 mutex_exit(p->p_lock); 414 error = EPERM; 415 goto out; 416 } 417 } else { 418 /* Use the calling process */ 419 p = l->l_proc; 420 mutex_enter(p->p_lock); 421 } 422 423 /* 424 * Check the permission. 425 */ 426 error = kauth_authorize_process(l->l_cred, 427 KAUTH_PROCESS_SCHEDULER_SETAFFINITY, p, NULL, NULL, NULL); 428 if (error != 0) { 429 mutex_exit(p->p_lock); 430 goto out; 431 } 432 433 /* Iterate through LWP(s). */ 434 lcnt = 0; 435 lid = SCARG(uap, lid); 436 LIST_FOREACH(t, &p->p_lwps, l_sibling) { 437 if (lid && lid != t->l_lid) { 438 continue; 439 } 440 lwp_lock(t); 441 /* No affinity for zombie LWPs. */ 442 if (t->l_stat == LSZOMB) { 443 lwp_unlock(t); 444 continue; 445 } 446 /* First, release existing affinity, if any. */ 447 if (t->l_affinity) { 448 kcpuset_unuse(t->l_affinity, &kcpulst); 449 } 450 if (kcset) { 451 /* 452 * Hold a reference on affinity mask, assign mask to 453 * LWP and migrate it to another CPU (unlocks LWP). 454 */ 455 kcpuset_use(kcset); 456 t->l_affinity = kcset; 457 lwp_migrate(t, ci); 458 } else { 459 /* Old affinity mask is released, just clear. */ 460 t->l_affinity = NULL; 461 lwp_unlock(t); 462 } 463 lcnt++; 464 } 465 mutex_exit(p->p_lock); 466 if (lcnt == 0) { 467 error = ESRCH; 468 } 469 out: 470 mutex_exit(&cpu_lock); 471 472 /* 473 * Drop the initial reference (LWPs, if any, have the ownership now), 474 * and destroy whatever is in the G/C list, if filled. 475 */ 476 if (kcset) { 477 kcpuset_unuse(kcset, &kcpulst); 478 } 479 if (kcpulst) { 480 kcpuset_destroy(kcpulst); 481 } 482 return error; 483 } 484 485 /* 486 * Get affinity. 487 */ 488 int 489 sys__sched_getaffinity(struct lwp *l, 490 const struct sys__sched_getaffinity_args *uap, register_t *retval) 491 { 492 /* { 493 syscallarg(pid_t) pid; 494 syscallarg(lwpid_t) lid; 495 syscallarg(size_t) size; 496 syscallarg(cpuset_t *) cpuset; 497 } */ 498 struct lwp *t; 499 kcpuset_t *kcset; 500 int error; 501 502 error = genkcpuset(&kcset, SCARG(uap, cpuset), SCARG(uap, size)); 503 if (error) 504 return error; 505 506 /* Locks the LWP */ 507 t = lwp_find2(SCARG(uap, pid), SCARG(uap, lid)); 508 if (t == NULL) { 509 error = ESRCH; 510 goto out; 511 } 512 /* Check the permission */ 513 if (kauth_authorize_process(l->l_cred, 514 KAUTH_PROCESS_SCHEDULER_GETAFFINITY, t->l_proc, NULL, NULL, NULL)) { 515 mutex_exit(t->l_proc->p_lock); 516 error = EPERM; 517 goto out; 518 } 519 lwp_lock(t); 520 if (t->l_affinity) { 521 kcpuset_copy(kcset, t->l_affinity); 522 } else { 523 kcpuset_zero(kcset); 524 } 525 lwp_unlock(t); 526 mutex_exit(t->l_proc->p_lock); 527 528 error = kcpuset_copyout(kcset, SCARG(uap, cpuset), SCARG(uap, size)); 529 out: 530 kcpuset_unuse(kcset, NULL); 531 return error; 532 } 533 534 /* 535 * Priority protection for PTHREAD_PRIO_PROTECT. This is a weak 536 * analogue of priority inheritance: temp raise the priority 537 * of the caller when accessing a protected resource. 538 */ 539 int 540 sys__sched_protect(struct lwp *l, 541 const struct sys__sched_protect_args *uap, register_t *retval) 542 { 543 /* { 544 syscallarg(int) priority; 545 syscallarg(int *) opriority; 546 } */ 547 int error; 548 pri_t pri; 549 550 KASSERT(l->l_inheritedprio == -1); 551 KASSERT(l->l_auxprio == -1 || l->l_auxprio == l->l_protectprio); 552 553 pri = SCARG(uap, priority); 554 error = 0; 555 lwp_lock(l); 556 if (pri == -1) { 557 /* back out priority changes */ 558 switch(l->l_protectdepth) { 559 case 0: 560 error = EINVAL; 561 break; 562 case 1: 563 l->l_protectdepth = 0; 564 l->l_protectprio = -1; 565 l->l_auxprio = -1; 566 break; 567 default: 568 l->l_protectdepth--; 569 break; 570 } 571 } else if (pri < 0) { 572 /* Just retrieve the current value, for debugging */ 573 if (l->l_protectprio == -1) 574 error = ENOENT; 575 else 576 *retval = l->l_protectprio - PRI_USER_RT; 577 } else if (__predict_false(pri < SCHED_PRI_MIN || 578 pri > SCHED_PRI_MAX || l->l_priority > pri + PRI_USER_RT)) { 579 /* must fail if existing priority is higher */ 580 error = EPERM; 581 } else { 582 /* play along but make no changes if not a realtime LWP. */ 583 l->l_protectdepth++; 584 pri += PRI_USER_RT; 585 if (__predict_true(l->l_class != SCHED_OTHER && 586 pri > l->l_protectprio)) { 587 l->l_protectprio = pri; 588 l->l_auxprio = pri; 589 } 590 } 591 lwp_unlock(l); 592 593 return error; 594 } 595 596 /* 597 * Yield. 598 */ 599 int 600 sys_sched_yield(struct lwp *l, const void *v, register_t *retval) 601 { 602 603 yield(); 604 return 0; 605 } 606 607 /* 608 * Sysctl nodes and initialization. 609 */ 610 static void 611 sysctl_sched_setup(struct sysctllog **clog) 612 { 613 const struct sysctlnode *node = NULL; 614 615 sysctl_createv(clog, 0, NULL, NULL, 616 CTLFLAG_PERMANENT|CTLFLAG_IMMEDIATE, 617 CTLTYPE_INT, "posix_sched", 618 SYSCTL_DESCR("Version of IEEE Std 1003.1 and its " 619 "Process Scheduling option to which the " 620 "system attempts to conform"), 621 NULL, _POSIX_PRIORITY_SCHEDULING, NULL, 0, 622 CTL_KERN, CTL_CREATE, CTL_EOL); 623 sysctl_createv(clog, 0, NULL, &node, 624 CTLFLAG_PERMANENT, 625 CTLTYPE_NODE, "sched", 626 SYSCTL_DESCR("Scheduler options"), 627 NULL, 0, NULL, 0, 628 CTL_KERN, CTL_CREATE, CTL_EOL); 629 630 if (node == NULL) 631 return; 632 633 sysctl_createv(clog, 0, &node, NULL, 634 CTLFLAG_PERMANENT | CTLFLAG_IMMEDIATE, 635 CTLTYPE_INT, "pri_min", 636 SYSCTL_DESCR("Minimal POSIX real-time priority"), 637 NULL, SCHED_PRI_MIN, NULL, 0, 638 CTL_CREATE, CTL_EOL); 639 sysctl_createv(clog, 0, &node, NULL, 640 CTLFLAG_PERMANENT | CTLFLAG_IMMEDIATE, 641 CTLTYPE_INT, "pri_max", 642 SYSCTL_DESCR("Maximal POSIX real-time priority"), 643 NULL, SCHED_PRI_MAX, NULL, 0, 644 CTL_CREATE, CTL_EOL); 645 } 646 647 static int 648 sched_listener_cb(kauth_cred_t cred, kauth_action_t action, void *cookie, 649 void *arg0, void *arg1, void *arg2, void *arg3) 650 { 651 struct proc *p; 652 int result; 653 654 result = KAUTH_RESULT_DEFER; 655 p = arg0; 656 657 switch (action) { 658 case KAUTH_PROCESS_SCHEDULER_GETPARAM: 659 if (kauth_cred_uidmatch(cred, p->p_cred)) 660 result = KAUTH_RESULT_ALLOW; 661 break; 662 663 case KAUTH_PROCESS_SCHEDULER_SETPARAM: 664 if (kauth_cred_uidmatch(cred, p->p_cred)) { 665 struct lwp *l; 666 int policy; 667 pri_t priority; 668 669 l = arg1; 670 policy = (int)(unsigned long)arg2; 671 priority = (pri_t)(unsigned long)arg3; 672 673 if ((policy == l->l_class || 674 (policy != SCHED_FIFO && policy != SCHED_RR)) && 675 priority <= l->l_priority) 676 result = KAUTH_RESULT_ALLOW; 677 } 678 679 break; 680 681 case KAUTH_PROCESS_SCHEDULER_GETAFFINITY: 682 result = KAUTH_RESULT_ALLOW; 683 break; 684 685 case KAUTH_PROCESS_SCHEDULER_SETAFFINITY: 686 /* Privileged; we let the secmodel handle this. */ 687 break; 688 689 default: 690 break; 691 } 692 693 return result; 694 } 695 696 void 697 sched_init(void) 698 { 699 700 sysctl_sched_setup(&sched_sysctl_log); 701 702 sched_listener = kauth_listen_scope(KAUTH_SCOPE_PROCESS, 703 sched_listener_cb, NULL); 704 } 705