1 /* $NetBSD: sys_sched.c,v 1.47 2020/01/27 22:05:10 ad 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 */ 42 43 #include <sys/cdefs.h> 44 __KERNEL_RCSID(0, "$NetBSD: sys_sched.c,v 1.47 2020/01/27 22:05:10 ad Exp $"); 45 46 #include <sys/param.h> 47 48 #include <sys/cpu.h> 49 #include <sys/kauth.h> 50 #include <sys/kmem.h> 51 #include <sys/lwp.h> 52 #include <sys/mutex.h> 53 #include <sys/proc.h> 54 #include <sys/pset.h> 55 #include <sys/sched.h> 56 #include <sys/syscallargs.h> 57 #include <sys/sysctl.h> 58 #include <sys/systm.h> 59 #include <sys/types.h> 60 #include <sys/unistd.h> 61 62 static struct sysctllog *sched_sysctl_log; 63 static kauth_listener_t sched_listener; 64 65 /* 66 * Convert user priority or the in-kernel priority or convert the current 67 * priority to the appropriate range according to the policy change. 68 */ 69 static pri_t 70 convert_pri(lwp_t *l, int policy, pri_t pri) 71 { 72 73 /* Convert user priority to the in-kernel */ 74 if (pri != PRI_NONE) { 75 /* Only for real-time threads */ 76 KASSERT(pri >= SCHED_PRI_MIN && pri <= SCHED_PRI_MAX); 77 KASSERT(policy != SCHED_OTHER); 78 return PRI_USER_RT + pri; 79 } 80 81 /* Neither policy, nor priority change */ 82 if (l->l_class == policy) 83 return l->l_priority; 84 85 /* Time-sharing -> real-time */ 86 if (l->l_class == SCHED_OTHER) { 87 KASSERT(policy == SCHED_FIFO || policy == SCHED_RR); 88 return PRI_USER_RT; 89 } 90 91 /* Real-time -> time-sharing */ 92 if (policy == SCHED_OTHER) { 93 KASSERT(l->l_class == SCHED_FIFO || l->l_class == SCHED_RR); 94 /* 95 * this is a bit arbitrary because the priority is dynamic 96 * for SCHED_OTHER threads and will likely be changed by 97 * the scheduler soon anyway. 98 */ 99 return l->l_priority - PRI_USER_RT; 100 } 101 102 /* Real-time -> real-time */ 103 return l->l_priority; 104 } 105 106 int 107 do_sched_setparam(pid_t pid, lwpid_t lid, int policy, 108 const struct sched_param *params) 109 { 110 struct proc *p; 111 struct lwp *t; 112 pri_t pri; 113 u_int lcnt; 114 int error; 115 116 error = 0; 117 118 pri = params->sched_priority; 119 120 /* If no parameters specified, just return (this should not happen) */ 121 if (pri == PRI_NONE && policy == SCHED_NONE) 122 return 0; 123 124 /* Validate scheduling class */ 125 if (policy != SCHED_NONE && (policy < SCHED_OTHER || policy > SCHED_RR)) 126 return EINVAL; 127 128 /* Validate priority */ 129 if (pri != PRI_NONE && (pri < SCHED_PRI_MIN || pri > SCHED_PRI_MAX)) 130 return EINVAL; 131 132 if (pid != 0) { 133 /* Find the process */ 134 mutex_enter(proc_lock); 135 p = proc_find(pid); 136 if (p == NULL) { 137 mutex_exit(proc_lock); 138 return ESRCH; 139 } 140 mutex_enter(p->p_lock); 141 mutex_exit(proc_lock); 142 /* Disallow modification of system processes */ 143 if ((p->p_flag & PK_SYSTEM) != 0) { 144 mutex_exit(p->p_lock); 145 return EPERM; 146 } 147 } else { 148 /* Use the calling process */ 149 p = curlwp->l_proc; 150 mutex_enter(p->p_lock); 151 } 152 153 /* Find the LWP(s) */ 154 lcnt = 0; 155 LIST_FOREACH(t, &p->p_lwps, l_sibling) { 156 pri_t kpri; 157 int lpolicy; 158 159 if (lid && lid != t->l_lid) 160 continue; 161 162 lcnt++; 163 lwp_lock(t); 164 lpolicy = (policy == SCHED_NONE) ? t->l_class : policy; 165 166 /* Disallow setting of priority for SCHED_OTHER threads */ 167 if (lpolicy == SCHED_OTHER && pri != PRI_NONE) { 168 lwp_unlock(t); 169 error = EINVAL; 170 break; 171 } 172 173 /* Convert priority, if needed */ 174 kpri = convert_pri(t, lpolicy, pri); 175 176 /* Check the permission */ 177 error = kauth_authorize_process(kauth_cred_get(), 178 KAUTH_PROCESS_SCHEDULER_SETPARAM, p, t, KAUTH_ARG(lpolicy), 179 KAUTH_ARG(kpri)); 180 if (error) { 181 lwp_unlock(t); 182 break; 183 } 184 185 /* Set the scheduling class, change the priority */ 186 t->l_class = lpolicy; 187 lwp_changepri(t, kpri); 188 lwp_unlock(t); 189 } 190 mutex_exit(p->p_lock); 191 return (lcnt == 0) ? ESRCH : error; 192 } 193 194 /* 195 * Set scheduling parameters. 196 */ 197 int 198 sys__sched_setparam(struct lwp *l, const struct sys__sched_setparam_args *uap, 199 register_t *retval) 200 { 201 /* { 202 syscallarg(pid_t) pid; 203 syscallarg(lwpid_t) lid; 204 syscallarg(int) policy; 205 syscallarg(const struct sched_param *) params; 206 } */ 207 struct sched_param params; 208 int error; 209 210 /* Get the parameters from the user-space */ 211 error = copyin(SCARG(uap, params), ¶ms, sizeof(params)); 212 if (error) 213 goto out; 214 215 error = do_sched_setparam(SCARG(uap, pid), SCARG(uap, lid), 216 SCARG(uap, policy), ¶ms); 217 out: 218 return error; 219 } 220 221 /* 222 * do_sched_getparam: 223 * 224 * if lid=0, returns the parameter of the first LWP in the process. 225 */ 226 int 227 do_sched_getparam(pid_t pid, lwpid_t lid, int *policy, 228 struct sched_param *params) 229 { 230 struct sched_param lparams; 231 struct lwp *t; 232 int error, lpolicy; 233 234 t = lwp_find2(pid, lid); /* acquire p_lock */ 235 if (t == NULL) 236 return ESRCH; 237 238 /* Check the permission */ 239 error = kauth_authorize_process(kauth_cred_get(), 240 KAUTH_PROCESS_SCHEDULER_GETPARAM, t->l_proc, NULL, NULL, NULL); 241 if (error != 0) { 242 mutex_exit(t->l_proc->p_lock); 243 return error; 244 } 245 246 lwp_lock(t); 247 lparams.sched_priority = t->l_priority; 248 lpolicy = t->l_class; 249 lwp_unlock(t); 250 mutex_exit(t->l_proc->p_lock); 251 252 /* 253 * convert to the user-visible priority value. 254 * it's an inversion of convert_pri(). 255 * 256 * the SCHED_OTHER case is a bit arbitrary given that 257 * - we don't allow setting the priority. 258 * - the priority is dynamic. 259 */ 260 switch (lpolicy) { 261 case SCHED_OTHER: 262 lparams.sched_priority -= PRI_USER; 263 break; 264 case SCHED_RR: 265 case SCHED_FIFO: 266 lparams.sched_priority -= PRI_USER_RT; 267 break; 268 } 269 270 if (policy != NULL) 271 *policy = lpolicy; 272 273 if (params != NULL) 274 *params = lparams; 275 276 return error; 277 } 278 279 /* 280 * Get scheduling parameters. 281 */ 282 int 283 sys__sched_getparam(struct lwp *l, const struct sys__sched_getparam_args *uap, 284 register_t *retval) 285 { 286 /* { 287 syscallarg(pid_t) pid; 288 syscallarg(lwpid_t) lid; 289 syscallarg(int *) policy; 290 syscallarg(struct sched_param *) params; 291 } */ 292 struct sched_param params; 293 int error, policy; 294 295 error = do_sched_getparam(SCARG(uap, pid), SCARG(uap, lid), &policy, 296 ¶ms); 297 if (error) 298 goto out; 299 300 error = copyout(¶ms, SCARG(uap, params), sizeof(params)); 301 if (error == 0 && SCARG(uap, policy) != NULL) 302 error = copyout(&policy, SCARG(uap, policy), sizeof(int)); 303 out: 304 return error; 305 } 306 307 /* 308 * Allocate the CPU set, and get it from userspace. 309 */ 310 static int 311 genkcpuset(kcpuset_t **dset, const cpuset_t *sset, size_t size) 312 { 313 kcpuset_t *kset; 314 int error; 315 316 kcpuset_create(&kset, true); 317 error = kcpuset_copyin(sset, kset, size); 318 if (error) { 319 kcpuset_unuse(kset, NULL); 320 } else { 321 *dset = kset; 322 } 323 return error; 324 } 325 326 /* 327 * Set affinity. 328 */ 329 int 330 sys__sched_setaffinity(struct lwp *l, 331 const struct sys__sched_setaffinity_args *uap, register_t *retval) 332 { 333 /* { 334 syscallarg(pid_t) pid; 335 syscallarg(lwpid_t) lid; 336 syscallarg(size_t) size; 337 syscallarg(const cpuset_t *) cpuset; 338 } */ 339 kcpuset_t *kcset, *kcpulst = NULL; 340 struct cpu_info *ici, *ci; 341 struct proc *p; 342 struct lwp *t; 343 CPU_INFO_ITERATOR cii; 344 bool alloff; 345 lwpid_t lid; 346 u_int lcnt; 347 int error; 348 349 error = genkcpuset(&kcset, SCARG(uap, cpuset), SCARG(uap, size)); 350 if (error) 351 return error; 352 353 /* 354 * Traverse _each_ CPU to: 355 * - Check that CPUs in the mask have no assigned processor set. 356 * - Check that at least one CPU from the mask is online. 357 * - Find the first target CPU to migrate. 358 * 359 * To avoid the race with CPU online/offline calls and processor sets, 360 * cpu_lock will be locked for the entire operation. 361 */ 362 ci = NULL; 363 alloff = false; 364 mutex_enter(&cpu_lock); 365 for (CPU_INFO_FOREACH(cii, ici)) { 366 struct schedstate_percpu *ispc; 367 368 if (!kcpuset_isset(kcset, cpu_index(ici))) { 369 continue; 370 } 371 372 ispc = &ici->ci_schedstate; 373 /* Check that CPU is not in the processor-set */ 374 if (ispc->spc_psid != PS_NONE) { 375 error = EPERM; 376 goto out; 377 } 378 /* Skip offline CPUs */ 379 if (ispc->spc_flags & SPCF_OFFLINE) { 380 alloff = true; 381 continue; 382 } 383 /* Target CPU to migrate */ 384 if (ci == NULL) { 385 ci = ici; 386 } 387 } 388 if (ci == NULL) { 389 if (alloff) { 390 /* All CPUs in the set are offline */ 391 error = EPERM; 392 goto out; 393 } 394 /* Empty set */ 395 kcpuset_unuse(kcset, &kcpulst); 396 kcset = NULL; 397 } 398 399 if (SCARG(uap, pid) != 0) { 400 /* Find the process */ 401 mutex_enter(proc_lock); 402 p = proc_find(SCARG(uap, pid)); 403 if (p == NULL) { 404 mutex_exit(proc_lock); 405 error = ESRCH; 406 goto out; 407 } 408 mutex_enter(p->p_lock); 409 mutex_exit(proc_lock); 410 /* Disallow modification of system processes. */ 411 if ((p->p_flag & PK_SYSTEM) != 0) { 412 mutex_exit(p->p_lock); 413 error = EPERM; 414 goto out; 415 } 416 } else { 417 /* Use the calling process */ 418 p = l->l_proc; 419 mutex_enter(p->p_lock); 420 } 421 422 /* 423 * Check the permission. 424 */ 425 error = kauth_authorize_process(l->l_cred, 426 KAUTH_PROCESS_SCHEDULER_SETAFFINITY, p, NULL, NULL, NULL); 427 if (error != 0) { 428 mutex_exit(p->p_lock); 429 goto out; 430 } 431 432 /* Iterate through LWP(s). */ 433 lcnt = 0; 434 lid = SCARG(uap, lid); 435 LIST_FOREACH(t, &p->p_lwps, l_sibling) { 436 if (lid && lid != t->l_lid) { 437 continue; 438 } 439 lwp_lock(t); 440 /* No affinity for zombie LWPs. */ 441 if (t->l_stat == LSZOMB) { 442 lwp_unlock(t); 443 continue; 444 } 445 /* First, release existing affinity, if any. */ 446 if (t->l_affinity) { 447 kcpuset_unuse(t->l_affinity, &kcpulst); 448 } 449 if (kcset) { 450 /* 451 * Hold a reference on affinity mask, assign mask to 452 * LWP and migrate it to another CPU (unlocks LWP). 453 */ 454 kcpuset_use(kcset); 455 t->l_affinity = kcset; 456 lwp_migrate(t, ci); 457 } else { 458 /* Old affinity mask is released, just clear. */ 459 t->l_affinity = NULL; 460 lwp_unlock(t); 461 } 462 lcnt++; 463 } 464 mutex_exit(p->p_lock); 465 if (lcnt == 0) { 466 error = ESRCH; 467 } 468 out: 469 mutex_exit(&cpu_lock); 470 471 /* 472 * Drop the initial reference (LWPs, if any, have the ownership now), 473 * and destroy whatever is in the G/C list, if filled. 474 */ 475 if (kcset) { 476 kcpuset_unuse(kcset, &kcpulst); 477 } 478 if (kcpulst) { 479 kcpuset_destroy(kcpulst); 480 } 481 return error; 482 } 483 484 /* 485 * Get affinity. 486 */ 487 int 488 sys__sched_getaffinity(struct lwp *l, 489 const struct sys__sched_getaffinity_args *uap, register_t *retval) 490 { 491 /* { 492 syscallarg(pid_t) pid; 493 syscallarg(lwpid_t) lid; 494 syscallarg(size_t) size; 495 syscallarg(cpuset_t *) cpuset; 496 } */ 497 struct lwp *t; 498 kcpuset_t *kcset; 499 int error; 500 501 error = genkcpuset(&kcset, SCARG(uap, cpuset), SCARG(uap, size)); 502 if (error) 503 return error; 504 505 /* Locks the LWP */ 506 t = lwp_find2(SCARG(uap, pid), SCARG(uap, lid)); 507 if (t == NULL) { 508 error = ESRCH; 509 goto out; 510 } 511 /* Check the permission */ 512 if (kauth_authorize_process(l->l_cred, 513 KAUTH_PROCESS_SCHEDULER_GETAFFINITY, t->l_proc, NULL, NULL, NULL)) { 514 mutex_exit(t->l_proc->p_lock); 515 error = EPERM; 516 goto out; 517 } 518 lwp_lock(t); 519 if (t->l_affinity) { 520 kcpuset_copy(kcset, t->l_affinity); 521 } else { 522 kcpuset_zero(kcset); 523 } 524 lwp_unlock(t); 525 mutex_exit(t->l_proc->p_lock); 526 527 error = kcpuset_copyout(kcset, SCARG(uap, cpuset), SCARG(uap, size)); 528 out: 529 kcpuset_unuse(kcset, NULL); 530 return error; 531 } 532 533 /* 534 * Priority protection for PTHREAD_PRIO_PROTECT. This is a weak 535 * analogue of priority inheritance: temp raise the priority 536 * of the caller when accessing a protected resource. 537 */ 538 int 539 sys__sched_protect(struct lwp *l, 540 const struct sys__sched_protect_args *uap, register_t *retval) 541 { 542 /* { 543 syscallarg(int) priority; 544 syscallarg(int *) opriority; 545 } */ 546 int error; 547 pri_t pri; 548 549 KASSERT(l->l_inheritedprio == -1); 550 KASSERT(l->l_auxprio == -1 || l->l_auxprio == l->l_protectprio); 551 552 pri = SCARG(uap, priority); 553 error = 0; 554 lwp_lock(l); 555 if (pri == -1) { 556 /* back out priority changes */ 557 switch(l->l_protectdepth) { 558 case 0: 559 error = EINVAL; 560 break; 561 case 1: 562 l->l_protectdepth = 0; 563 l->l_protectprio = -1; 564 l->l_auxprio = -1; 565 break; 566 default: 567 l->l_protectdepth--; 568 break; 569 } 570 } else if (pri < 0) { 571 /* Just retrieve the current value, for debugging */ 572 if (l->l_protectprio == -1) 573 error = ENOENT; 574 else 575 *retval = l->l_protectprio - PRI_USER_RT; 576 } else if (__predict_false(pri < SCHED_PRI_MIN || 577 pri > SCHED_PRI_MAX || l->l_priority > pri + PRI_USER_RT)) { 578 /* must fail if existing priority is higher */ 579 error = EPERM; 580 } else { 581 /* play along but make no changes if not a realtime LWP. */ 582 l->l_protectdepth++; 583 pri += PRI_USER_RT; 584 if (__predict_true(l->l_class != SCHED_OTHER && 585 pri > l->l_protectprio)) { 586 l->l_protectprio = pri; 587 l->l_auxprio = pri; 588 } 589 } 590 lwp_unlock(l); 591 592 return error; 593 } 594 595 /* 596 * Yield. 597 */ 598 int 599 sys_sched_yield(struct lwp *l, const void *v, register_t *retval) 600 { 601 602 yield(); 603 return 0; 604 } 605 606 /* 607 * Sysctl nodes and initialization. 608 */ 609 static void 610 sysctl_sched_setup(struct sysctllog **clog) 611 { 612 const struct sysctlnode *node = NULL; 613 614 sysctl_createv(clog, 0, NULL, NULL, 615 CTLFLAG_PERMANENT|CTLFLAG_IMMEDIATE, 616 CTLTYPE_INT, "posix_sched", 617 SYSCTL_DESCR("Version of IEEE Std 1003.1 and its " 618 "Process Scheduling option to which the " 619 "system attempts to conform"), 620 NULL, _POSIX_PRIORITY_SCHEDULING, NULL, 0, 621 CTL_KERN, CTL_CREATE, CTL_EOL); 622 sysctl_createv(clog, 0, NULL, &node, 623 CTLFLAG_PERMANENT, 624 CTLTYPE_NODE, "sched", 625 SYSCTL_DESCR("Scheduler options"), 626 NULL, 0, NULL, 0, 627 CTL_KERN, CTL_CREATE, CTL_EOL); 628 629 if (node == NULL) 630 return; 631 632 sysctl_createv(clog, 0, &node, NULL, 633 CTLFLAG_PERMANENT | CTLFLAG_IMMEDIATE, 634 CTLTYPE_INT, "pri_min", 635 SYSCTL_DESCR("Minimal POSIX real-time priority"), 636 NULL, SCHED_PRI_MIN, NULL, 0, 637 CTL_CREATE, CTL_EOL); 638 sysctl_createv(clog, 0, &node, NULL, 639 CTLFLAG_PERMANENT | CTLFLAG_IMMEDIATE, 640 CTLTYPE_INT, "pri_max", 641 SYSCTL_DESCR("Maximal POSIX real-time priority"), 642 NULL, SCHED_PRI_MAX, NULL, 0, 643 CTL_CREATE, CTL_EOL); 644 } 645 646 static int 647 sched_listener_cb(kauth_cred_t cred, kauth_action_t action, void *cookie, 648 void *arg0, void *arg1, void *arg2, void *arg3) 649 { 650 struct proc *p; 651 int result; 652 653 result = KAUTH_RESULT_DEFER; 654 p = arg0; 655 656 switch (action) { 657 case KAUTH_PROCESS_SCHEDULER_GETPARAM: 658 if (kauth_cred_uidmatch(cred, p->p_cred)) 659 result = KAUTH_RESULT_ALLOW; 660 break; 661 662 case KAUTH_PROCESS_SCHEDULER_SETPARAM: 663 if (kauth_cred_uidmatch(cred, p->p_cred)) { 664 struct lwp *l; 665 int policy; 666 pri_t priority; 667 668 l = arg1; 669 policy = (int)(unsigned long)arg2; 670 priority = (pri_t)(unsigned long)arg3; 671 672 if ((policy == l->l_class || 673 (policy != SCHED_FIFO && policy != SCHED_RR)) && 674 priority <= l->l_priority) 675 result = KAUTH_RESULT_ALLOW; 676 } 677 678 break; 679 680 case KAUTH_PROCESS_SCHEDULER_GETAFFINITY: 681 result = KAUTH_RESULT_ALLOW; 682 break; 683 684 case KAUTH_PROCESS_SCHEDULER_SETAFFINITY: 685 /* Privileged; we let the secmodel handle this. */ 686 break; 687 688 default: 689 break; 690 } 691 692 return result; 693 } 694 695 void 696 sched_init(void) 697 { 698 699 sysctl_sched_setup(&sched_sysctl_log); 700 701 sched_listener = kauth_listen_scope(KAUTH_SCOPE_PROCESS, 702 sched_listener_cb, NULL); 703 } 704