1 /* $NetBSD: linux_futex.c,v 1.7 2006/07/24 19:01:49 manu Exp $ */ 2 3 /*- 4 * SPDX-License-Identifier: BSD-4-Clause 5 * 6 * Copyright (c) 2009-2016 Dmitry Chagin 7 * Copyright (c) 2005 Emmanuel Dreyfus 8 * All rights reserved. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by Emmanuel Dreyfus 21 * 4. The name of the author may not be used to endorse or promote 22 * products derived from this software without specific prior written 23 * permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE THE AUTHOR AND CONTRIBUTORS ``AS IS'' 26 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, 27 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 28 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS 29 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 30 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 31 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 32 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 33 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 34 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35 * POSSIBILITY OF SUCH DAMAGE. 36 */ 37 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 #if 0 41 __KERNEL_RCSID(1, "$NetBSD: linux_futex.c,v 1.7 2006/07/24 19:01:49 manu Exp $"); 42 #endif 43 44 #include "opt_compat.h" 45 46 #include <sys/param.h> 47 #include <sys/systm.h> 48 #include <sys/imgact.h> 49 #include <sys/kernel.h> 50 #include <sys/ktr.h> 51 #include <sys/lock.h> 52 #include <sys/malloc.h> 53 #include <sys/mutex.h> 54 #include <sys/priv.h> 55 #include <sys/proc.h> 56 #include <sys/queue.h> 57 #include <sys/sched.h> 58 #include <sys/sdt.h> 59 #include <sys/umtx.h> 60 61 #include <vm/vm_extern.h> 62 63 #ifdef COMPAT_LINUX32 64 #include <machine/../linux32/linux.h> 65 #include <machine/../linux32/linux32_proto.h> 66 #else 67 #include <machine/../linux/linux.h> 68 #include <machine/../linux/linux_proto.h> 69 #endif 70 #include <compat/linux/linux_dtrace.h> 71 #include <compat/linux/linux_emul.h> 72 #include <compat/linux/linux_futex.h> 73 #include <compat/linux/linux_timer.h> 74 #include <compat/linux/linux_util.h> 75 76 /* DTrace init */ 77 LIN_SDT_PROVIDER_DECLARE(LINUX_DTRACE); 78 79 /** 80 * Futex part for the special DTrace module "locks". 81 */ 82 LIN_SDT_PROBE_DEFINE1(locks, futex_mtx, locked, "struct mtx *"); 83 LIN_SDT_PROBE_DEFINE1(locks, futex_mtx, unlock, "struct mtx *"); 84 85 /** 86 * Per futex probes. 87 */ 88 LIN_SDT_PROBE_DEFINE1(futex, futex, create, "struct sx *"); 89 LIN_SDT_PROBE_DEFINE1(futex, futex, destroy, "struct sx *"); 90 91 /** 92 * DTrace probes in this module. 93 */ 94 LIN_SDT_PROBE_DEFINE3(futex, futex_put, destroy, "uint32_t *", "uint32_t", 95 "int"); 96 LIN_SDT_PROBE_DEFINE3(futex, futex_put, unlock, "uint32_t *", "uint32_t", 97 "int"); 98 LIN_SDT_PROBE_DEFINE1(futex, futex_get0, umtx_key_get_error, "int"); 99 LIN_SDT_PROBE_DEFINE3(futex, futex_get0, shared, "uint32_t *", "uint32_t", 100 "int"); 101 LIN_SDT_PROBE_DEFINE1(futex, futex_get0, null, "uint32_t *"); 102 LIN_SDT_PROBE_DEFINE3(futex, futex_get0, new, "uint32_t *", "uint32_t", "int"); 103 LIN_SDT_PROBE_DEFINE0(futex, futex_get, error); 104 LIN_SDT_PROBE_DEFINE5(futex, futex_sleep, requeue_error, "int", "uint32_t *", 105 "struct waiting_proc *", "uint32_t *", "uint32_t"); 106 LIN_SDT_PROBE_DEFINE3(futex, futex_sleep, sleep_error, "int", "uint32_t *", 107 "struct waiting_proc *"); 108 LIN_SDT_PROBE_DEFINE3(futex, futex_wake, iterate, "uint32_t", 109 "struct waiting_proc *", "uint32_t"); 110 LIN_SDT_PROBE_DEFINE1(futex, futex_wake, wakeup, "struct waiting_proc *"); 111 LIN_SDT_PROBE_DEFINE1(futex, futex_requeue, wakeup, "struct waiting_proc *"); 112 LIN_SDT_PROBE_DEFINE3(futex, futex_requeue, requeue, "uint32_t *", 113 "struct waiting_proc *", "uint32_t"); 114 LIN_SDT_PROBE_DEFINE1(futex, futex_wait, sleep_error, "int"); 115 LIN_SDT_PROBE_DEFINE4(futex, futex_atomic_op, decoded_op, "int", "int", "int", 116 "int"); 117 LIN_SDT_PROBE_DEFINE0(futex, futex_atomic_op, missing_access_check); 118 LIN_SDT_PROBE_DEFINE1(futex, futex_atomic_op, unimplemented_op, "int"); 119 LIN_SDT_PROBE_DEFINE1(futex, futex_atomic_op, unimplemented_cmp, "int"); 120 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_clockswitch); 121 LIN_SDT_PROBE_DEFINE1(futex, linux_sys_futex, copyin_error, "int"); 122 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, invalid_cmp_requeue_use); 123 LIN_SDT_PROBE_DEFINE3(futex, linux_sys_futex, debug_wait, "uint32_t *", 124 "uint32_t", "uint32_t"); 125 LIN_SDT_PROBE_DEFINE4(futex, linux_sys_futex, debug_wait_value_neq, 126 "uint32_t *", "uint32_t", "int", "uint32_t"); 127 LIN_SDT_PROBE_DEFINE3(futex, linux_sys_futex, debug_wake, "uint32_t *", 128 "uint32_t", "uint32_t"); 129 LIN_SDT_PROBE_DEFINE5(futex, linux_sys_futex, debug_cmp_requeue, "uint32_t *", 130 "uint32_t", "uint32_t", "uint32_t *", "struct l_timespec *"); 131 LIN_SDT_PROBE_DEFINE2(futex, linux_sys_futex, debug_cmp_requeue_value_neq, 132 "uint32_t", "int"); 133 LIN_SDT_PROBE_DEFINE5(futex, linux_sys_futex, debug_wake_op, "uint32_t *", 134 "int", "uint32_t", "uint32_t *", "uint32_t"); 135 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unhandled_efault); 136 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_lock_pi); 137 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_unlock_pi); 138 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_trylock_pi); 139 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, deprecated_requeue); 140 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_wait_requeue_pi); 141 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_cmp_requeue_pi); 142 LIN_SDT_PROBE_DEFINE1(futex, linux_sys_futex, unknown_operation, "int"); 143 LIN_SDT_PROBE_DEFINE0(futex, linux_set_robust_list, size_error); 144 LIN_SDT_PROBE_DEFINE1(futex, linux_get_robust_list, copyout_error, "int"); 145 LIN_SDT_PROBE_DEFINE1(futex, handle_futex_death, copyin_error, "int"); 146 LIN_SDT_PROBE_DEFINE1(futex, fetch_robust_entry, copyin_error, "int"); 147 LIN_SDT_PROBE_DEFINE1(futex, release_futexes, copyin_error, "int"); 148 149 struct futex; 150 151 struct waiting_proc { 152 uint32_t wp_flags; 153 struct futex *wp_futex; 154 TAILQ_ENTRY(waiting_proc) wp_list; 155 }; 156 157 struct futex { 158 struct mtx f_lck; 159 uint32_t *f_uaddr; /* user-supplied value, for debug */ 160 struct umtx_key f_key; 161 uint32_t f_refcount; 162 uint32_t f_bitset; 163 LIST_ENTRY(futex) f_list; 164 TAILQ_HEAD(lf_waiting_proc, waiting_proc) f_waiting_proc; 165 }; 166 167 #define FUTEX_LOCK(f) mtx_lock(&(f)->f_lck) 168 #define FUTEX_LOCKED(f) mtx_owned(&(f)->f_lck) 169 #define FUTEX_UNLOCK(f) mtx_unlock(&(f)->f_lck) 170 #define FUTEX_INIT(f) do { \ 171 mtx_init(&(f)->f_lck, "ftlk", NULL, \ 172 MTX_DUPOK); \ 173 LIN_SDT_PROBE1(futex, futex, create, \ 174 &(f)->f_lck); \ 175 } while (0) 176 #define FUTEX_DESTROY(f) do { \ 177 LIN_SDT_PROBE1(futex, futex, destroy, \ 178 &(f)->f_lck); \ 179 mtx_destroy(&(f)->f_lck); \ 180 } while (0) 181 #define FUTEX_ASSERT_LOCKED(f) mtx_assert(&(f)->f_lck, MA_OWNED) 182 #define FUTEX_ASSERT_UNLOCKED(f) mtx_assert(&(f)->f_lck, MA_NOTOWNED) 183 184 #define FUTEXES_LOCK do { \ 185 mtx_lock(&futex_mtx); \ 186 LIN_SDT_PROBE1(locks, futex_mtx, \ 187 locked, &futex_mtx); \ 188 } while (0) 189 #define FUTEXES_UNLOCK do { \ 190 LIN_SDT_PROBE1(locks, futex_mtx, \ 191 unlock, &futex_mtx); \ 192 mtx_unlock(&futex_mtx); \ 193 } while (0) 194 195 /* flags for futex_get() */ 196 #define FUTEX_CREATE_WP 0x1 /* create waiting_proc */ 197 #define FUTEX_DONTCREATE 0x2 /* don't create futex if not exists */ 198 #define FUTEX_DONTEXISTS 0x4 /* return EINVAL if futex exists */ 199 #define FUTEX_SHARED 0x8 /* shared futex */ 200 #define FUTEX_DONTLOCK 0x10 /* don't lock futex */ 201 202 /* wp_flags */ 203 #define FUTEX_WP_REQUEUED 0x1 /* wp requeued - wp moved from wp_list 204 * of futex where thread sleep to wp_list 205 * of another futex. 206 */ 207 #define FUTEX_WP_REMOVED 0x2 /* wp is woken up and removed from futex 208 * wp_list to prevent double wakeup. 209 */ 210 211 static void futex_put(struct futex *, struct waiting_proc *); 212 static int futex_get0(uint32_t *, struct futex **f, uint32_t); 213 static int futex_get(uint32_t *, struct waiting_proc **, struct futex **, 214 uint32_t); 215 static int futex_sleep(struct futex *, struct waiting_proc *, struct timespec *); 216 static int futex_wake(struct futex *, int, uint32_t); 217 static int futex_requeue(struct futex *, int, struct futex *, int); 218 static int futex_copyin_timeout(int, struct l_timespec *, int, 219 struct timespec *); 220 static int futex_wait(struct futex *, struct waiting_proc *, struct timespec *, 221 uint32_t); 222 static void futex_lock(struct futex *); 223 static void futex_unlock(struct futex *); 224 static int futex_atomic_op(struct thread *, int, uint32_t *); 225 static int handle_futex_death(struct linux_emuldata *, uint32_t *, 226 unsigned int); 227 static int fetch_robust_entry(struct linux_robust_list **, 228 struct linux_robust_list **, unsigned int *); 229 230 static int 231 futex_copyin_timeout(int op, struct l_timespec *luts, int clockrt, 232 struct timespec *ts) 233 { 234 struct l_timespec lts; 235 struct timespec kts; 236 int error; 237 238 error = copyin(luts, <s, sizeof(lts)); 239 if (error) 240 return (error); 241 242 error = linux_to_native_timespec(ts, <s); 243 if (error) 244 return (error); 245 if (clockrt) { 246 nanotime(&kts); 247 timespecsub(ts, &kts, ts); 248 } else if (op == LINUX_FUTEX_WAIT_BITSET) { 249 nanouptime(&kts); 250 timespecsub(ts, &kts, ts); 251 } 252 return (error); 253 } 254 255 static void 256 futex_put(struct futex *f, struct waiting_proc *wp) 257 { 258 259 if (wp != NULL) { 260 if ((wp->wp_flags & FUTEX_WP_REMOVED) == 0) 261 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list); 262 free(wp, M_FUTEX_WP); 263 } 264 265 FUTEXES_LOCK; 266 if (--f->f_refcount == 0) { 267 LIST_REMOVE(f, f_list); 268 FUTEXES_UNLOCK; 269 if (FUTEX_LOCKED(f)) 270 futex_unlock(f); 271 272 LIN_SDT_PROBE3(futex, futex_put, destroy, f->f_uaddr, 273 f->f_refcount, f->f_key.shared); 274 LINUX_CTR3(sys_futex, "futex_put destroy uaddr %p ref %d " 275 "shared %d", f->f_uaddr, f->f_refcount, f->f_key.shared); 276 umtx_key_release(&f->f_key); 277 FUTEX_DESTROY(f); 278 free(f, M_FUTEX); 279 return; 280 } 281 282 LIN_SDT_PROBE3(futex, futex_put, unlock, f->f_uaddr, f->f_refcount, 283 f->f_key.shared); 284 LINUX_CTR3(sys_futex, "futex_put uaddr %p ref %d shared %d", 285 f->f_uaddr, f->f_refcount, f->f_key.shared); 286 if (FUTEX_LOCKED(f)) 287 futex_unlock(f); 288 FUTEXES_UNLOCK; 289 } 290 291 static int 292 futex_get0(uint32_t *uaddr, struct futex **newf, uint32_t flags) 293 { 294 struct futex *f, *tmpf; 295 struct umtx_key key; 296 int error; 297 298 *newf = tmpf = NULL; 299 300 error = umtx_key_get(uaddr, TYPE_FUTEX, (flags & FUTEX_SHARED) ? 301 AUTO_SHARE : THREAD_SHARE, &key); 302 if (error) { 303 LIN_SDT_PROBE1(futex, futex_get0, umtx_key_get_error, error); 304 return (error); 305 } 306 retry: 307 FUTEXES_LOCK; 308 LIST_FOREACH(f, &futex_list, f_list) { 309 if (umtx_key_match(&f->f_key, &key)) { 310 if (tmpf != NULL) { 311 if (FUTEX_LOCKED(tmpf)) 312 futex_unlock(tmpf); 313 FUTEX_DESTROY(tmpf); 314 free(tmpf, M_FUTEX); 315 } 316 if (flags & FUTEX_DONTEXISTS) { 317 FUTEXES_UNLOCK; 318 umtx_key_release(&key); 319 320 return (EINVAL); 321 } 322 323 /* 324 * Increment refcount of the found futex to 325 * prevent it from deallocation before FUTEX_LOCK() 326 */ 327 ++f->f_refcount; 328 FUTEXES_UNLOCK; 329 umtx_key_release(&key); 330 331 if ((flags & FUTEX_DONTLOCK) == 0) 332 futex_lock(f); 333 *newf = f; 334 LIN_SDT_PROBE3(futex, futex_get0, shared, uaddr, 335 f->f_refcount, f->f_key.shared); 336 LINUX_CTR3(sys_futex, "futex_get uaddr %p ref %d shared %d", 337 uaddr, f->f_refcount, f->f_key.shared); 338 339 return (0); 340 } 341 } 342 343 if (flags & FUTEX_DONTCREATE) { 344 FUTEXES_UNLOCK; 345 umtx_key_release(&key); 346 LIN_SDT_PROBE1(futex, futex_get0, null, uaddr); 347 LINUX_CTR1(sys_futex, "futex_get uaddr %p null", uaddr); 348 349 return (0); 350 } 351 352 if (tmpf == NULL) { 353 FUTEXES_UNLOCK; 354 tmpf = malloc(sizeof(*tmpf), M_FUTEX, M_WAITOK | M_ZERO); 355 tmpf->f_uaddr = uaddr; 356 tmpf->f_key = key; 357 tmpf->f_refcount = 1; 358 tmpf->f_bitset = FUTEX_BITSET_MATCH_ANY; 359 FUTEX_INIT(tmpf); 360 TAILQ_INIT(&tmpf->f_waiting_proc); 361 362 /* 363 * Lock the new futex before an insert into the futex_list 364 * to prevent futex usage by other. 365 */ 366 if ((flags & FUTEX_DONTLOCK) == 0) 367 futex_lock(tmpf); 368 goto retry; 369 } 370 371 LIST_INSERT_HEAD(&futex_list, tmpf, f_list); 372 FUTEXES_UNLOCK; 373 374 LIN_SDT_PROBE3(futex, futex_get0, new, uaddr, tmpf->f_refcount, 375 tmpf->f_key.shared); 376 LINUX_CTR3(sys_futex, "futex_get uaddr %p ref %d shared %d new", 377 uaddr, tmpf->f_refcount, tmpf->f_key.shared); 378 *newf = tmpf; 379 380 return (0); 381 } 382 383 static int 384 futex_get(uint32_t *uaddr, struct waiting_proc **wp, struct futex **f, 385 uint32_t flags) 386 { 387 int error; 388 389 if (flags & FUTEX_CREATE_WP) { 390 *wp = malloc(sizeof(struct waiting_proc), M_FUTEX_WP, M_WAITOK); 391 (*wp)->wp_flags = 0; 392 } 393 error = futex_get0(uaddr, f, flags); 394 if (error) { 395 LIN_SDT_PROBE0(futex, futex_get, error); 396 397 if (flags & FUTEX_CREATE_WP) 398 free(*wp, M_FUTEX_WP); 399 400 return (error); 401 } 402 if (flags & FUTEX_CREATE_WP) { 403 TAILQ_INSERT_HEAD(&(*f)->f_waiting_proc, *wp, wp_list); 404 (*wp)->wp_futex = *f; 405 } 406 407 return (error); 408 } 409 410 static inline void 411 futex_lock(struct futex *f) 412 { 413 414 LINUX_CTR3(sys_futex, "futex_lock uaddr %p ref %d shared %d", 415 f->f_uaddr, f->f_refcount, f->f_key.shared); 416 FUTEX_ASSERT_UNLOCKED(f); 417 FUTEX_LOCK(f); 418 } 419 420 static inline void 421 futex_unlock(struct futex *f) 422 { 423 424 LINUX_CTR3(sys_futex, "futex_unlock uaddr %p ref %d shared %d", 425 f->f_uaddr, f->f_refcount, f->f_key.shared); 426 FUTEX_ASSERT_LOCKED(f); 427 FUTEX_UNLOCK(f); 428 } 429 430 static int 431 futex_sleep(struct futex *f, struct waiting_proc *wp, struct timespec *ts) 432 { 433 struct timespec uts; 434 sbintime_t sbt, prec, tmp; 435 time_t over; 436 int error; 437 438 FUTEX_ASSERT_LOCKED(f); 439 if (ts != NULL) { 440 uts = *ts; 441 if (uts.tv_sec > INT32_MAX / 2) { 442 over = uts.tv_sec - INT32_MAX / 2; 443 uts.tv_sec -= over; 444 } 445 tmp = tstosbt(uts); 446 if (TIMESEL(&sbt, tmp)) 447 sbt += tc_tick_sbt; 448 sbt += tmp; 449 prec = tmp; 450 prec >>= tc_precexp; 451 } else { 452 sbt = 0; 453 prec = 0; 454 } 455 LINUX_CTR4(sys_futex, "futex_sleep enter uaddr %p wp %p timo %ld ref %d", 456 f->f_uaddr, wp, sbt, f->f_refcount); 457 458 error = msleep_sbt(wp, &f->f_lck, PCATCH, "futex", sbt, prec, C_ABSOLUTE); 459 if (wp->wp_flags & FUTEX_WP_REQUEUED) { 460 KASSERT(f != wp->wp_futex, ("futex != wp_futex")); 461 462 if (error) { 463 LIN_SDT_PROBE5(futex, futex_sleep, requeue_error, error, 464 f->f_uaddr, wp, wp->wp_futex->f_uaddr, 465 wp->wp_futex->f_refcount); 466 } 467 468 LINUX_CTR5(sys_futex, "futex_sleep out error %d uaddr %p wp" 469 " %p requeued uaddr %p ref %d", 470 error, f->f_uaddr, wp, wp->wp_futex->f_uaddr, 471 wp->wp_futex->f_refcount); 472 futex_put(f, NULL); 473 f = wp->wp_futex; 474 futex_lock(f); 475 } else { 476 if (error) { 477 LIN_SDT_PROBE3(futex, futex_sleep, sleep_error, error, 478 f->f_uaddr, wp); 479 } 480 LINUX_CTR3(sys_futex, "futex_sleep out error %d uaddr %p wp %p", 481 error, f->f_uaddr, wp); 482 } 483 484 futex_put(f, wp); 485 486 return (error); 487 } 488 489 static int 490 futex_wake(struct futex *f, int n, uint32_t bitset) 491 { 492 struct waiting_proc *wp, *wpt; 493 int count = 0; 494 495 if (bitset == 0) 496 return (EINVAL); 497 498 FUTEX_ASSERT_LOCKED(f); 499 TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) { 500 LIN_SDT_PROBE3(futex, futex_wake, iterate, f->f_uaddr, wp, 501 f->f_refcount); 502 LINUX_CTR3(sys_futex, "futex_wake uaddr %p wp %p ref %d", 503 f->f_uaddr, wp, f->f_refcount); 504 /* 505 * Unless we find a matching bit in 506 * the bitset, continue searching. 507 */ 508 if (!(wp->wp_futex->f_bitset & bitset)) 509 continue; 510 511 wp->wp_flags |= FUTEX_WP_REMOVED; 512 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list); 513 LIN_SDT_PROBE1(futex, futex_wake, wakeup, wp); 514 wakeup_one(wp); 515 if (++count == n) 516 break; 517 } 518 519 return (count); 520 } 521 522 static int 523 futex_requeue(struct futex *f, int n, struct futex *f2, int n2) 524 { 525 struct waiting_proc *wp, *wpt; 526 int count = 0; 527 528 FUTEX_ASSERT_LOCKED(f); 529 FUTEX_ASSERT_LOCKED(f2); 530 531 TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) { 532 if (++count <= n) { 533 LINUX_CTR2(sys_futex, "futex_req_wake uaddr %p wp %p", 534 f->f_uaddr, wp); 535 wp->wp_flags |= FUTEX_WP_REMOVED; 536 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list); 537 LIN_SDT_PROBE1(futex, futex_requeue, wakeup, wp); 538 wakeup_one(wp); 539 } else { 540 LIN_SDT_PROBE3(futex, futex_requeue, requeue, 541 f->f_uaddr, wp, f2->f_uaddr); 542 LINUX_CTR3(sys_futex, "futex_requeue uaddr %p wp %p to %p", 543 f->f_uaddr, wp, f2->f_uaddr); 544 wp->wp_flags |= FUTEX_WP_REQUEUED; 545 /* Move wp to wp_list of f2 futex */ 546 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list); 547 TAILQ_INSERT_HEAD(&f2->f_waiting_proc, wp, wp_list); 548 549 /* 550 * Thread which sleeps on wp after waking should 551 * acquire f2 lock, so increment refcount of f2 to 552 * prevent it from premature deallocation. 553 */ 554 wp->wp_futex = f2; 555 FUTEXES_LOCK; 556 ++f2->f_refcount; 557 FUTEXES_UNLOCK; 558 if (count - n >= n2) 559 break; 560 } 561 } 562 563 return (count); 564 } 565 566 static int 567 futex_wait(struct futex *f, struct waiting_proc *wp, struct timespec *ts, 568 uint32_t bitset) 569 { 570 int error; 571 572 if (bitset == 0) { 573 futex_put(f, wp); 574 return (EINVAL); 575 } 576 577 f->f_bitset = bitset; 578 error = futex_sleep(f, wp, ts); 579 if (error) 580 LIN_SDT_PROBE1(futex, futex_wait, sleep_error, error); 581 if (error == EWOULDBLOCK) 582 error = ETIMEDOUT; 583 584 return (error); 585 } 586 587 static int 588 futex_atomic_op(struct thread *td, int encoded_op, uint32_t *uaddr) 589 { 590 int op = (encoded_op >> 28) & 7; 591 int cmp = (encoded_op >> 24) & 15; 592 int oparg = (encoded_op << 8) >> 20; 593 int cmparg = (encoded_op << 20) >> 20; 594 int oldval = 0, ret; 595 596 if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) 597 oparg = 1 << oparg; 598 599 LIN_SDT_PROBE4(futex, futex_atomic_op, decoded_op, op, cmp, oparg, 600 cmparg); 601 602 /* XXX: Linux verifies access here and returns EFAULT */ 603 LIN_SDT_PROBE0(futex, futex_atomic_op, missing_access_check); 604 605 switch (op) { 606 case FUTEX_OP_SET: 607 ret = futex_xchgl(oparg, uaddr, &oldval); 608 break; 609 case FUTEX_OP_ADD: 610 ret = futex_addl(oparg, uaddr, &oldval); 611 break; 612 case FUTEX_OP_OR: 613 ret = futex_orl(oparg, uaddr, &oldval); 614 break; 615 case FUTEX_OP_ANDN: 616 ret = futex_andl(~oparg, uaddr, &oldval); 617 break; 618 case FUTEX_OP_XOR: 619 ret = futex_xorl(oparg, uaddr, &oldval); 620 break; 621 default: 622 LIN_SDT_PROBE1(futex, futex_atomic_op, unimplemented_op, op); 623 ret = -ENOSYS; 624 break; 625 } 626 627 if (ret) 628 return (ret); 629 630 switch (cmp) { 631 case FUTEX_OP_CMP_EQ: 632 ret = (oldval == cmparg); 633 break; 634 case FUTEX_OP_CMP_NE: 635 ret = (oldval != cmparg); 636 break; 637 case FUTEX_OP_CMP_LT: 638 ret = (oldval < cmparg); 639 break; 640 case FUTEX_OP_CMP_GE: 641 ret = (oldval >= cmparg); 642 break; 643 case FUTEX_OP_CMP_LE: 644 ret = (oldval <= cmparg); 645 break; 646 case FUTEX_OP_CMP_GT: 647 ret = (oldval > cmparg); 648 break; 649 default: 650 LIN_SDT_PROBE1(futex, futex_atomic_op, unimplemented_cmp, cmp); 651 ret = -ENOSYS; 652 } 653 654 return (ret); 655 } 656 657 int 658 linux_sys_futex(struct thread *td, struct linux_sys_futex_args *args) 659 { 660 int clockrt, nrwake, op_ret, ret; 661 struct linux_pemuldata *pem; 662 struct waiting_proc *wp; 663 struct futex *f, *f2; 664 struct timespec uts, *ts; 665 int error, save; 666 uint32_t flags, val; 667 668 if (args->op & LINUX_FUTEX_PRIVATE_FLAG) { 669 flags = 0; 670 args->op &= ~LINUX_FUTEX_PRIVATE_FLAG; 671 } else 672 flags = FUTEX_SHARED; 673 674 /* 675 * Currently support for switching between CLOCK_MONOTONIC and 676 * CLOCK_REALTIME is not present. However Linux forbids the use of 677 * FUTEX_CLOCK_REALTIME with any op except FUTEX_WAIT_BITSET and 678 * FUTEX_WAIT_REQUEUE_PI. 679 */ 680 clockrt = args->op & LINUX_FUTEX_CLOCK_REALTIME; 681 args->op = args->op & ~LINUX_FUTEX_CLOCK_REALTIME; 682 if (clockrt && args->op != LINUX_FUTEX_WAIT_BITSET && 683 args->op != LINUX_FUTEX_WAIT_REQUEUE_PI) { 684 LIN_SDT_PROBE0(futex, linux_sys_futex, 685 unimplemented_clockswitch); 686 return (ENOSYS); 687 } 688 689 error = 0; 690 f = f2 = NULL; 691 692 switch (args->op) { 693 case LINUX_FUTEX_WAIT: 694 args->val3 = FUTEX_BITSET_MATCH_ANY; 695 /* FALLTHROUGH */ 696 697 case LINUX_FUTEX_WAIT_BITSET: 698 LIN_SDT_PROBE3(futex, linux_sys_futex, debug_wait, args->uaddr, 699 args->val, args->val3); 700 LINUX_CTR3(sys_futex, "WAIT uaddr %p val 0x%x bitset 0x%x", 701 args->uaddr, args->val, args->val3); 702 703 if (args->timeout != NULL) { 704 error = futex_copyin_timeout(args->op, args->timeout, 705 clockrt, &uts); 706 if (error) { 707 LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error, 708 error); 709 return (error); 710 } 711 ts = &uts; 712 } else 713 ts = NULL; 714 715 retry0: 716 error = futex_get(args->uaddr, &wp, &f, 717 flags | FUTEX_CREATE_WP); 718 if (error) 719 return (error); 720 721 error = copyin_nofault(args->uaddr, &val, sizeof(val)); 722 if (error) { 723 futex_put(f, wp); 724 error = copyin(args->uaddr, &val, sizeof(val)); 725 if (error == 0) 726 goto retry0; 727 LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error, 728 error); 729 LINUX_CTR1(sys_futex, "WAIT copyin failed %d", 730 error); 731 return (error); 732 } 733 if (val != args->val) { 734 LIN_SDT_PROBE4(futex, linux_sys_futex, 735 debug_wait_value_neq, args->uaddr, args->val, val, 736 args->val3); 737 LINUX_CTR3(sys_futex, 738 "WAIT uaddr %p val 0x%x != uval 0x%x", 739 args->uaddr, args->val, val); 740 futex_put(f, wp); 741 return (EWOULDBLOCK); 742 } 743 744 error = futex_wait(f, wp, ts, args->val3); 745 break; 746 747 case LINUX_FUTEX_WAKE: 748 args->val3 = FUTEX_BITSET_MATCH_ANY; 749 /* FALLTHROUGH */ 750 751 case LINUX_FUTEX_WAKE_BITSET: 752 LIN_SDT_PROBE3(futex, linux_sys_futex, debug_wake, args->uaddr, 753 args->val, args->val3); 754 LINUX_CTR3(sys_futex, "WAKE uaddr %p nrwake 0x%x bitset 0x%x", 755 args->uaddr, args->val, args->val3); 756 757 error = futex_get(args->uaddr, NULL, &f, 758 flags | FUTEX_DONTCREATE); 759 if (error) 760 return (error); 761 762 if (f == NULL) { 763 td->td_retval[0] = 0; 764 return (error); 765 } 766 td->td_retval[0] = futex_wake(f, args->val, args->val3); 767 futex_put(f, NULL); 768 break; 769 770 case LINUX_FUTEX_CMP_REQUEUE: 771 LIN_SDT_PROBE5(futex, linux_sys_futex, debug_cmp_requeue, 772 args->uaddr, args->val, args->val3, args->uaddr2, 773 args->timeout); 774 LINUX_CTR5(sys_futex, "CMP_REQUEUE uaddr %p " 775 "nrwake 0x%x uval 0x%x uaddr2 %p nrequeue 0x%x", 776 args->uaddr, args->val, args->val3, args->uaddr2, 777 args->timeout); 778 779 /* 780 * Linux allows this, we would not, it is an incorrect 781 * usage of declared ABI, so return EINVAL. 782 */ 783 if (args->uaddr == args->uaddr2) { 784 LIN_SDT_PROBE0(futex, linux_sys_futex, 785 invalid_cmp_requeue_use); 786 return (EINVAL); 787 } 788 789 retry1: 790 error = futex_get(args->uaddr, NULL, &f, flags | FUTEX_DONTLOCK); 791 if (error) 792 return (error); 793 794 /* 795 * To avoid deadlocks return EINVAL if second futex 796 * exists at this time. 797 * 798 * Glibc fall back to FUTEX_WAKE in case of any error 799 * returned by FUTEX_CMP_REQUEUE. 800 */ 801 error = futex_get(args->uaddr2, NULL, &f2, 802 flags | FUTEX_DONTEXISTS | FUTEX_DONTLOCK); 803 if (error) { 804 futex_put(f, NULL); 805 return (error); 806 } 807 futex_lock(f); 808 futex_lock(f2); 809 error = copyin_nofault(args->uaddr, &val, sizeof(val)); 810 if (error) { 811 futex_put(f2, NULL); 812 futex_put(f, NULL); 813 error = copyin(args->uaddr, &val, sizeof(val)); 814 if (error == 0) 815 goto retry1; 816 LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error, 817 error); 818 LINUX_CTR1(sys_futex, "CMP_REQUEUE copyin failed %d", 819 error); 820 return (error); 821 } 822 if (val != args->val3) { 823 LIN_SDT_PROBE2(futex, linux_sys_futex, 824 debug_cmp_requeue_value_neq, args->val, val); 825 LINUX_CTR2(sys_futex, "CMP_REQUEUE val 0x%x != uval 0x%x", 826 args->val, val); 827 futex_put(f2, NULL); 828 futex_put(f, NULL); 829 return (EAGAIN); 830 } 831 832 nrwake = (int)(unsigned long)args->timeout; 833 td->td_retval[0] = futex_requeue(f, args->val, f2, nrwake); 834 futex_put(f2, NULL); 835 futex_put(f, NULL); 836 break; 837 838 case LINUX_FUTEX_WAKE_OP: 839 LIN_SDT_PROBE5(futex, linux_sys_futex, debug_wake_op, 840 args->uaddr, args->op, args->val, args->uaddr2, args->val3); 841 LINUX_CTR5(sys_futex, "WAKE_OP " 842 "uaddr %p nrwake 0x%x uaddr2 %p op 0x%x nrwake2 0x%x", 843 args->uaddr, args->val, args->uaddr2, args->val3, 844 args->timeout); 845 846 if (args->uaddr == args->uaddr2) 847 return (EINVAL); 848 849 retry2: 850 error = futex_get(args->uaddr, NULL, &f, flags | FUTEX_DONTLOCK); 851 if (error) 852 return (error); 853 854 error = futex_get(args->uaddr2, NULL, &f2, flags | FUTEX_DONTLOCK); 855 if (error) { 856 futex_put(f, NULL); 857 return (error); 858 } 859 futex_lock(f); 860 futex_lock(f2); 861 862 /* 863 * This function returns positive number as results and 864 * negative as errors 865 */ 866 save = vm_fault_disable_pagefaults(); 867 op_ret = futex_atomic_op(td, args->val3, args->uaddr2); 868 vm_fault_enable_pagefaults(save); 869 870 LINUX_CTR2(sys_futex, "WAKE_OP atomic_op uaddr %p ret 0x%x", 871 args->uaddr, op_ret); 872 873 if (op_ret < 0) { 874 if (f2 != NULL) 875 futex_put(f2, NULL); 876 futex_put(f, NULL); 877 error = copyin(args->uaddr2, &val, sizeof(val)); 878 if (error == 0) 879 goto retry2; 880 return (error); 881 } 882 883 ret = futex_wake(f, args->val, args->val3); 884 885 if (op_ret > 0) { 886 op_ret = 0; 887 nrwake = (int)(unsigned long)args->timeout; 888 889 if (f2 != NULL) 890 op_ret += futex_wake(f2, nrwake, args->val3); 891 else 892 op_ret += futex_wake(f, nrwake, args->val3); 893 ret += op_ret; 894 } 895 if (f2 != NULL) 896 futex_put(f2, NULL); 897 futex_put(f, NULL); 898 td->td_retval[0] = ret; 899 break; 900 901 case LINUX_FUTEX_LOCK_PI: 902 /* not yet implemented */ 903 pem = pem_find(td->td_proc); 904 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) { 905 linux_msg(td, "unsupported FUTEX_LOCK_PI"); 906 pem->flags |= LINUX_XUNSUP_FUTEXPIOP; 907 LIN_SDT_PROBE0(futex, linux_sys_futex, 908 unimplemented_lock_pi); 909 } 910 return (ENOSYS); 911 912 case LINUX_FUTEX_UNLOCK_PI: 913 /* not yet implemented */ 914 pem = pem_find(td->td_proc); 915 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) { 916 linux_msg(td, "unsupported FUTEX_UNLOCK_PI"); 917 pem->flags |= LINUX_XUNSUP_FUTEXPIOP; 918 LIN_SDT_PROBE0(futex, linux_sys_futex, 919 unimplemented_unlock_pi); 920 } 921 return (ENOSYS); 922 923 case LINUX_FUTEX_TRYLOCK_PI: 924 /* not yet implemented */ 925 pem = pem_find(td->td_proc); 926 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) { 927 linux_msg(td, "unsupported FUTEX_TRYLOCK_PI"); 928 pem->flags |= LINUX_XUNSUP_FUTEXPIOP; 929 LIN_SDT_PROBE0(futex, linux_sys_futex, 930 unimplemented_trylock_pi); 931 } 932 return (ENOSYS); 933 934 case LINUX_FUTEX_REQUEUE: 935 /* 936 * Glibc does not use this operation since version 2.3.3, 937 * as it is racy and replaced by FUTEX_CMP_REQUEUE operation. 938 * Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when 939 * FUTEX_REQUEUE returned EINVAL. 940 */ 941 pem = pem_find(td->td_proc); 942 if ((pem->flags & LINUX_XDEPR_REQUEUEOP) == 0) { 943 linux_msg(td, "unsupported FUTEX_REQUEUE"); 944 pem->flags |= LINUX_XDEPR_REQUEUEOP; 945 LIN_SDT_PROBE0(futex, linux_sys_futex, 946 deprecated_requeue); 947 } 948 return (EINVAL); 949 950 case LINUX_FUTEX_WAIT_REQUEUE_PI: 951 /* not yet implemented */ 952 pem = pem_find(td->td_proc); 953 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) { 954 linux_msg(td, "unsupported FUTEX_WAIT_REQUEUE_PI"); 955 pem->flags |= LINUX_XUNSUP_FUTEXPIOP; 956 LIN_SDT_PROBE0(futex, linux_sys_futex, 957 unimplemented_wait_requeue_pi); 958 } 959 return (ENOSYS); 960 961 case LINUX_FUTEX_CMP_REQUEUE_PI: 962 /* not yet implemented */ 963 pem = pem_find(td->td_proc); 964 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) { 965 linux_msg(td, "unsupported FUTEX_CMP_REQUEUE_PI"); 966 pem->flags |= LINUX_XUNSUP_FUTEXPIOP; 967 LIN_SDT_PROBE0(futex, linux_sys_futex, 968 unimplemented_cmp_requeue_pi); 969 } 970 return (ENOSYS); 971 972 default: 973 linux_msg(td, "unsupported futex op %d", args->op); 974 LIN_SDT_PROBE1(futex, linux_sys_futex, unknown_operation, 975 args->op); 976 return (ENOSYS); 977 } 978 979 return (error); 980 } 981 982 int 983 linux_set_robust_list(struct thread *td, struct linux_set_robust_list_args *args) 984 { 985 struct linux_emuldata *em; 986 987 if (args->len != sizeof(struct linux_robust_list_head)) { 988 LIN_SDT_PROBE0(futex, linux_set_robust_list, size_error); 989 return (EINVAL); 990 } 991 992 em = em_find(td); 993 em->robust_futexes = args->head; 994 995 return (0); 996 } 997 998 int 999 linux_get_robust_list(struct thread *td, struct linux_get_robust_list_args *args) 1000 { 1001 struct linux_emuldata *em; 1002 struct linux_robust_list_head *head; 1003 l_size_t len = sizeof(struct linux_robust_list_head); 1004 struct thread *td2; 1005 int error = 0; 1006 1007 if (!args->pid) { 1008 em = em_find(td); 1009 KASSERT(em != NULL, ("get_robust_list: emuldata notfound.\n")); 1010 head = em->robust_futexes; 1011 } else { 1012 td2 = tdfind(args->pid, -1); 1013 if (td2 == NULL) 1014 return (ESRCH); 1015 if (SV_PROC_ABI(td2->td_proc) != SV_ABI_LINUX) { 1016 PROC_UNLOCK(td2->td_proc); 1017 return (EPERM); 1018 } 1019 1020 em = em_find(td2); 1021 KASSERT(em != NULL, ("get_robust_list: emuldata notfound.\n")); 1022 /* XXX: ptrace? */ 1023 if (priv_check(td, PRIV_CRED_SETUID) || 1024 priv_check(td, PRIV_CRED_SETEUID) || 1025 p_candebug(td, td2->td_proc)) { 1026 PROC_UNLOCK(td2->td_proc); 1027 return (EPERM); 1028 } 1029 head = em->robust_futexes; 1030 1031 PROC_UNLOCK(td2->td_proc); 1032 } 1033 1034 error = copyout(&len, args->len, sizeof(l_size_t)); 1035 if (error) { 1036 LIN_SDT_PROBE1(futex, linux_get_robust_list, copyout_error, 1037 error); 1038 return (EFAULT); 1039 } 1040 1041 error = copyout(&head, args->head, sizeof(head)); 1042 if (error) { 1043 LIN_SDT_PROBE1(futex, linux_get_robust_list, copyout_error, 1044 error); 1045 } 1046 1047 return (error); 1048 } 1049 1050 static int 1051 handle_futex_death(struct linux_emuldata *em, uint32_t *uaddr, 1052 unsigned int pi) 1053 { 1054 uint32_t uval, nval, mval; 1055 struct futex *f; 1056 int error; 1057 1058 retry: 1059 error = copyin(uaddr, &uval, 4); 1060 if (error) { 1061 LIN_SDT_PROBE1(futex, handle_futex_death, copyin_error, error); 1062 return (EFAULT); 1063 } 1064 if ((uval & FUTEX_TID_MASK) == em->em_tid) { 1065 mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED; 1066 nval = casuword32(uaddr, uval, mval); 1067 1068 if (nval == -1) 1069 return (EFAULT); 1070 1071 if (nval != uval) 1072 goto retry; 1073 1074 if (!pi && (uval & FUTEX_WAITERS)) { 1075 error = futex_get(uaddr, NULL, &f, 1076 FUTEX_DONTCREATE | FUTEX_SHARED); 1077 if (error) 1078 return (error); 1079 if (f != NULL) { 1080 futex_wake(f, 1, FUTEX_BITSET_MATCH_ANY); 1081 futex_put(f, NULL); 1082 } 1083 } 1084 } 1085 1086 return (0); 1087 } 1088 1089 static int 1090 fetch_robust_entry(struct linux_robust_list **entry, 1091 struct linux_robust_list **head, unsigned int *pi) 1092 { 1093 l_ulong uentry; 1094 int error; 1095 1096 error = copyin((const void *)head, &uentry, sizeof(l_ulong)); 1097 if (error) { 1098 LIN_SDT_PROBE1(futex, fetch_robust_entry, copyin_error, error); 1099 return (EFAULT); 1100 } 1101 1102 *entry = (void *)(uentry & ~1UL); 1103 *pi = uentry & 1; 1104 1105 return (0); 1106 } 1107 1108 /* This walks the list of robust futexes releasing them. */ 1109 void 1110 release_futexes(struct thread *td, struct linux_emuldata *em) 1111 { 1112 struct linux_robust_list_head *head = NULL; 1113 struct linux_robust_list *entry, *next_entry, *pending; 1114 unsigned int limit = 2048, pi, next_pi, pip; 1115 l_long futex_offset; 1116 int rc, error; 1117 1118 head = em->robust_futexes; 1119 1120 if (head == NULL) 1121 return; 1122 1123 if (fetch_robust_entry(&entry, PTRIN(&head->list.next), &pi)) 1124 return; 1125 1126 error = copyin(&head->futex_offset, &futex_offset, 1127 sizeof(futex_offset)); 1128 if (error) { 1129 LIN_SDT_PROBE1(futex, release_futexes, copyin_error, error); 1130 return; 1131 } 1132 1133 if (fetch_robust_entry(&pending, PTRIN(&head->pending_list), &pip)) 1134 return; 1135 1136 while (entry != &head->list) { 1137 rc = fetch_robust_entry(&next_entry, PTRIN(&entry->next), &next_pi); 1138 1139 if (entry != pending) 1140 if (handle_futex_death(em, 1141 (uint32_t *)((caddr_t)entry + futex_offset), pi)) { 1142 return; 1143 } 1144 if (rc) 1145 return; 1146 1147 entry = next_entry; 1148 pi = next_pi; 1149 1150 if (!--limit) 1151 break; 1152 1153 sched_relinquish(curthread); 1154 } 1155 1156 if (pending) 1157 handle_futex_death(em, (uint32_t *)((caddr_t)pending + futex_offset), pip); 1158 } 1159