1 /* $NetBSD: linux_futex.c,v 1.7 2006/07/24 19:01:49 manu Exp $ */ 2 3 /*- 4 * Copyright (c) 2005 Emmanuel Dreyfus, all rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. All advertising materials mentioning features or use of this software 15 * must display the following acknowledgement: 16 * This product includes software developed by Emmanuel Dreyfus 17 * 4. The name of the author may not be used to endorse or promote 18 * products derived from this software without specific prior written 19 * permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE THE AUTHOR AND CONTRIBUTORS ``AS IS'' 22 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, 23 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 24 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS 25 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 26 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 27 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 28 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 29 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 30 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 31 * POSSIBILITY OF SUCH DAMAGE. 32 */ 33 34 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD$"); 36 #if 0 37 __KERNEL_RCSID(1, "$NetBSD: linux_futex.c,v 1.7 2006/07/24 19:01:49 manu Exp $"); 38 #endif 39 40 #include "opt_compat.h" 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/imgact.h> 45 #include <sys/kernel.h> 46 #include <sys/ktr.h> 47 #include <sys/lock.h> 48 #include <sys/malloc.h> 49 #include <sys/mutex.h> 50 #include <sys/priv.h> 51 #include <sys/proc.h> 52 #include <sys/queue.h> 53 #include <sys/sched.h> 54 #include <sys/sx.h> 55 56 #ifdef COMPAT_LINUX32 57 #include <machine/../linux32/linux.h> 58 #include <machine/../linux32/linux32_proto.h> 59 #else 60 #include <machine/../linux/linux.h> 61 #include <machine/../linux/linux_proto.h> 62 #endif 63 #include <compat/linux/linux_futex.h> 64 #include <compat/linux/linux_emul.h> 65 #include <compat/linux/linux_util.h> 66 67 MALLOC_DEFINE(M_FUTEX, "futex", "Linux futexes"); 68 MALLOC_DEFINE(M_FUTEX_WP, "futex wp", "Linux futexes wp"); 69 70 struct futex; 71 72 struct waiting_proc { 73 uint32_t wp_flags; 74 struct futex *wp_futex; 75 TAILQ_ENTRY(waiting_proc) wp_list; 76 }; 77 78 struct futex { 79 struct sx f_lck; 80 uint32_t *f_uaddr; 81 uint32_t f_refcount; 82 LIST_ENTRY(futex) f_list; 83 TAILQ_HEAD(lf_waiting_proc, waiting_proc) f_waiting_proc; 84 }; 85 86 struct futex_list futex_list; 87 88 #define FUTEX_LOCK(f) sx_xlock(&(f)->f_lck) 89 #define FUTEX_UNLOCK(f) sx_xunlock(&(f)->f_lck) 90 #define FUTEX_INIT(f) sx_init_flags(&(f)->f_lck, "ftlk", 0) 91 #define FUTEX_DESTROY(f) sx_destroy(&(f)->f_lck) 92 #define FUTEX_ASSERT_LOCKED(f) sx_assert(&(f)->f_lck, SA_XLOCKED) 93 94 struct mtx futex_mtx; /* protects the futex list */ 95 #define FUTEXES_LOCK mtx_lock(&futex_mtx) 96 #define FUTEXES_UNLOCK mtx_unlock(&futex_mtx) 97 98 /* flags for futex_get() */ 99 #define FUTEX_CREATE_WP 0x1 /* create waiting_proc */ 100 #define FUTEX_DONTCREATE 0x2 /* don't create futex if not exists */ 101 #define FUTEX_DONTEXISTS 0x4 /* return EINVAL if futex exists */ 102 103 /* wp_flags */ 104 #define FUTEX_WP_REQUEUED 0x1 /* wp requeued - wp moved from wp_list 105 * of futex where thread sleep to wp_list 106 * of another futex. 107 */ 108 #define FUTEX_WP_REMOVED 0x2 /* wp is woken up and removed from futex 109 * wp_list to prevent double wakeup. 110 */ 111 112 /* support.s */ 113 int futex_xchgl(int oparg, uint32_t *uaddr, int *oldval); 114 int futex_addl(int oparg, uint32_t *uaddr, int *oldval); 115 int futex_orl(int oparg, uint32_t *uaddr, int *oldval); 116 int futex_andl(int oparg, uint32_t *uaddr, int *oldval); 117 int futex_xorl(int oparg, uint32_t *uaddr, int *oldval); 118 119 static void 120 futex_put(struct futex *f, struct waiting_proc *wp) 121 { 122 123 FUTEX_ASSERT_LOCKED(f); 124 if (wp != NULL) { 125 if ((wp->wp_flags & FUTEX_WP_REMOVED) == 0) 126 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list); 127 free(wp, M_FUTEX_WP); 128 } 129 130 FUTEXES_LOCK; 131 if (--f->f_refcount == 0) { 132 LIST_REMOVE(f, f_list); 133 FUTEXES_UNLOCK; 134 FUTEX_UNLOCK(f); 135 136 LINUX_CTR2(sys_futex, "futex_put destroy uaddr %p ref %d", 137 f->f_uaddr, f->f_refcount); 138 FUTEX_DESTROY(f); 139 free(f, M_FUTEX); 140 return; 141 } 142 143 LINUX_CTR2(sys_futex, "futex_put uaddr %p ref %d", 144 f->f_uaddr, f->f_refcount); 145 FUTEXES_UNLOCK; 146 FUTEX_UNLOCK(f); 147 } 148 149 static int 150 futex_get0(uint32_t *uaddr, struct futex **newf, uint32_t flags) 151 { 152 struct futex *f, *tmpf; 153 154 *newf = tmpf = NULL; 155 156 retry: 157 FUTEXES_LOCK; 158 LIST_FOREACH(f, &futex_list, f_list) { 159 if (f->f_uaddr == uaddr) { 160 if (tmpf != NULL) { 161 FUTEX_UNLOCK(tmpf); 162 FUTEX_DESTROY(tmpf); 163 free(tmpf, M_FUTEX); 164 } 165 if (flags & FUTEX_DONTEXISTS) { 166 FUTEXES_UNLOCK; 167 return (EINVAL); 168 } 169 170 /* 171 * Increment refcount of the found futex to 172 * prevent it from deallocation before FUTEX_LOCK() 173 */ 174 ++f->f_refcount; 175 FUTEXES_UNLOCK; 176 177 FUTEX_LOCK(f); 178 *newf = f; 179 LINUX_CTR2(sys_futex, "futex_get uaddr %p ref %d", 180 uaddr, f->f_refcount); 181 return (0); 182 } 183 } 184 185 if (flags & FUTEX_DONTCREATE) { 186 FUTEXES_UNLOCK; 187 LINUX_CTR1(sys_futex, "futex_get uaddr %p null", uaddr); 188 return (0); 189 } 190 191 if (tmpf == NULL) { 192 FUTEXES_UNLOCK; 193 tmpf = malloc(sizeof(*tmpf), M_FUTEX, M_WAITOK | M_ZERO); 194 tmpf->f_uaddr = uaddr; 195 tmpf->f_refcount = 1; 196 FUTEX_INIT(tmpf); 197 TAILQ_INIT(&tmpf->f_waiting_proc); 198 199 /* 200 * Lock the new futex before an insert into the futex_list 201 * to prevent futex usage by other. 202 */ 203 FUTEX_LOCK(tmpf); 204 goto retry; 205 } 206 207 LIST_INSERT_HEAD(&futex_list, tmpf, f_list); 208 FUTEXES_UNLOCK; 209 210 LINUX_CTR2(sys_futex, "futex_get uaddr %p ref %d new", 211 uaddr, tmpf->f_refcount); 212 *newf = tmpf; 213 return (0); 214 } 215 216 static int 217 futex_get(uint32_t *uaddr, struct waiting_proc **wp, struct futex **f, 218 uint32_t flags) 219 { 220 int error; 221 222 if (flags & FUTEX_CREATE_WP) { 223 *wp = malloc(sizeof(struct waiting_proc), M_FUTEX_WP, M_WAITOK); 224 (*wp)->wp_flags = 0; 225 } 226 error = futex_get0(uaddr, f, flags); 227 if (error) { 228 if (flags & FUTEX_CREATE_WP) 229 free(*wp, M_FUTEX_WP); 230 return (error); 231 } 232 if (flags & FUTEX_CREATE_WP) { 233 TAILQ_INSERT_HEAD(&(*f)->f_waiting_proc, *wp, wp_list); 234 (*wp)->wp_futex = *f; 235 } 236 237 return (error); 238 } 239 240 static int 241 futex_sleep(struct futex *f, struct waiting_proc *wp, unsigned long timeout) 242 { 243 int error; 244 245 FUTEX_ASSERT_LOCKED(f); 246 LINUX_CTR4(sys_futex, "futex_sleep enter uaddr %p wp %p timo %ld ref %d", 247 f->f_uaddr, wp, timeout, f->f_refcount); 248 error = sx_sleep(wp, &f->f_lck, PCATCH, "futex", timeout); 249 if (wp->wp_flags & FUTEX_WP_REQUEUED) { 250 KASSERT(f != wp->wp_futex, ("futex != wp_futex")); 251 LINUX_CTR5(sys_futex, "futex_sleep out error %d uaddr %p w" 252 " %p requeued uaddr %p ref %d", 253 error, f->f_uaddr, wp, wp->wp_futex->f_uaddr, 254 wp->wp_futex->f_refcount); 255 futex_put(f, NULL); 256 f = wp->wp_futex; 257 FUTEX_LOCK(f); 258 } else 259 LINUX_CTR3(sys_futex, "futex_sleep out error %d uaddr %p wp %p", 260 error, f->f_uaddr, wp); 261 262 futex_put(f, wp); 263 return (error); 264 } 265 266 static int 267 futex_wake(struct futex *f, int n) 268 { 269 struct waiting_proc *wp, *wpt; 270 int count = 0; 271 272 FUTEX_ASSERT_LOCKED(f); 273 TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) { 274 LINUX_CTR3(sys_futex, "futex_wake uaddr %p wp %p ref %d", 275 f->f_uaddr, wp, f->f_refcount); 276 wp->wp_flags |= FUTEX_WP_REMOVED; 277 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list); 278 wakeup_one(wp); 279 if (++count == n) 280 break; 281 } 282 283 return (count); 284 } 285 286 static int 287 futex_requeue(struct futex *f, int n, struct futex *f2, int n2) 288 { 289 struct waiting_proc *wp, *wpt; 290 int count = 0; 291 292 FUTEX_ASSERT_LOCKED(f); 293 FUTEX_ASSERT_LOCKED(f2); 294 295 TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) { 296 if (++count <= n) { 297 LINUX_CTR2(sys_futex, "futex_req_wake uaddr %p wp %p", 298 f->f_uaddr, wp); 299 wp->wp_flags |= FUTEX_WP_REMOVED; 300 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list); 301 wakeup_one(wp); 302 } else { 303 LINUX_CTR3(sys_futex, "futex_requeue uaddr %p wp %p to %p", 304 f->f_uaddr, wp, f2->f_uaddr); 305 wp->wp_flags |= FUTEX_WP_REQUEUED; 306 /* Move wp to wp_list of f2 futex */ 307 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list); 308 TAILQ_INSERT_HEAD(&f2->f_waiting_proc, wp, wp_list); 309 310 /* 311 * Thread which sleeps on wp after waking should 312 * acquire f2 lock, so increment refcount of f2 to 313 * prevent it from premature deallocation. 314 */ 315 wp->wp_futex = f2; 316 FUTEXES_LOCK; 317 ++f2->f_refcount; 318 FUTEXES_UNLOCK; 319 if (count - n >= n2) 320 break; 321 } 322 } 323 324 return (count); 325 } 326 327 static int 328 futex_wait(struct futex *f, struct waiting_proc *wp, struct l_timespec *ts) 329 { 330 struct l_timespec timeout = {0, 0}; 331 struct timeval tv = {0, 0}; 332 int timeout_hz; 333 int error; 334 335 if (ts != NULL) { 336 error = copyin(ts, &timeout, sizeof(timeout)); 337 if (error) 338 return (error); 339 } 340 341 tv.tv_usec = timeout.tv_sec * 1000000 + timeout.tv_nsec / 1000; 342 timeout_hz = tvtohz(&tv); 343 344 if (timeout.tv_sec == 0 && timeout.tv_nsec == 0) 345 timeout_hz = 0; 346 347 /* 348 * If the user process requests a non null timeout, 349 * make sure we do not turn it into an infinite 350 * timeout because timeout_hz gets null. 351 * 352 * We use a minimal timeout of 1/hz. Maybe it would 353 * make sense to just return ETIMEDOUT without sleeping. 354 */ 355 if (((timeout.tv_sec != 0) || (timeout.tv_nsec != 0)) && 356 (timeout_hz == 0)) 357 timeout_hz = 1; 358 359 error = futex_sleep(f, wp, timeout_hz); 360 if (error == EWOULDBLOCK) 361 error = ETIMEDOUT; 362 363 return (error); 364 } 365 366 static int 367 futex_atomic_op(struct thread *td, int encoded_op, uint32_t *uaddr) 368 { 369 int op = (encoded_op >> 28) & 7; 370 int cmp = (encoded_op >> 24) & 15; 371 int oparg = (encoded_op << 8) >> 20; 372 int cmparg = (encoded_op << 20) >> 20; 373 int oldval = 0, ret; 374 375 if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) 376 oparg = 1 << oparg; 377 378 #ifdef DEBUG 379 if (ldebug(sys_futex)) 380 printf("futex_atomic_op: op = %d, cmp = %d, oparg = %x, " 381 "cmparg = %x, uaddr = %p\n", 382 op, cmp, oparg, cmparg, uaddr); 383 #endif 384 /* XXX: linux verifies access here and returns EFAULT */ 385 386 switch (op) { 387 case FUTEX_OP_SET: 388 ret = futex_xchgl(oparg, uaddr, &oldval); 389 break; 390 case FUTEX_OP_ADD: 391 ret = futex_addl(oparg, uaddr, &oldval); 392 break; 393 case FUTEX_OP_OR: 394 ret = futex_orl(oparg, uaddr, &oldval); 395 break; 396 case FUTEX_OP_ANDN: 397 ret = futex_andl(~oparg, uaddr, &oldval); 398 break; 399 case FUTEX_OP_XOR: 400 ret = futex_xorl(oparg, uaddr, &oldval); 401 break; 402 default: 403 ret = -ENOSYS; 404 break; 405 } 406 407 if (ret) 408 return (ret); 409 410 switch (cmp) { 411 case FUTEX_OP_CMP_EQ: 412 return (oldval == cmparg); 413 case FUTEX_OP_CMP_NE: 414 return (oldval != cmparg); 415 case FUTEX_OP_CMP_LT: 416 return (oldval < cmparg); 417 case FUTEX_OP_CMP_GE: 418 return (oldval >= cmparg); 419 case FUTEX_OP_CMP_LE: 420 return (oldval <= cmparg); 421 case FUTEX_OP_CMP_GT: 422 return (oldval > cmparg); 423 default: 424 return (-ENOSYS); 425 } 426 } 427 428 int 429 linux_sys_futex(struct thread *td, struct linux_sys_futex_args *args) 430 { 431 int op_ret, val, ret, nrwake; 432 struct linux_emuldata *em; 433 struct waiting_proc *wp; 434 struct futex *f, *f2; 435 int error = 0; 436 437 /* 438 * Our implementation provides only privates futexes. Most of the apps 439 * should use private futexes but don't claim so. Therefore we treat 440 * all futexes as private by clearing the FUTEX_PRIVATE_FLAG. It works 441 * in most cases (ie. when futexes are not shared on file descriptor 442 * or between different processes.). 443 */ 444 args->op = (args->op & ~LINUX_FUTEX_PRIVATE_FLAG); 445 446 switch (args->op) { 447 case LINUX_FUTEX_WAIT: 448 449 LINUX_CTR2(sys_futex, "WAIT val %d uaddr %p", 450 args->val, args->uaddr); 451 #ifdef DEBUG 452 if (ldebug(sys_futex)) 453 printf(ARGS(sys_futex, "futex_wait val %d uaddr %p"), 454 args->val, args->uaddr); 455 #endif 456 error = futex_get(args->uaddr, &wp, &f, FUTEX_CREATE_WP); 457 if (error) 458 return (error); 459 error = copyin(args->uaddr, &val, sizeof(val)); 460 if (error) { 461 LINUX_CTR1(sys_futex, "WAIT copyin failed %d", 462 error); 463 futex_put(f, wp); 464 return (error); 465 } 466 if (val != args->val) { 467 LINUX_CTR3(sys_futex, "WAIT uaddr %p val %d != uval %d", 468 args->uaddr, args->val, val); 469 futex_put(f, wp); 470 return (EWOULDBLOCK); 471 } 472 473 error = futex_wait(f, wp, args->timeout); 474 break; 475 476 case LINUX_FUTEX_WAKE: 477 478 LINUX_CTR2(sys_futex, "WAKE val %d uaddr %p", 479 args->val, args->uaddr); 480 481 /* 482 * XXX: Linux is able to cope with different addresses 483 * corresponding to the same mapped memory in the sleeping 484 * and waker process(es). 485 */ 486 #ifdef DEBUG 487 if (ldebug(sys_futex)) 488 printf(ARGS(sys_futex, "futex_wake val %d uaddr %p"), 489 args->val, args->uaddr); 490 #endif 491 error = futex_get(args->uaddr, NULL, &f, FUTEX_DONTCREATE); 492 if (error) 493 return (error); 494 if (f == NULL) { 495 td->td_retval[0] = 0; 496 return (error); 497 } 498 td->td_retval[0] = futex_wake(f, args->val); 499 futex_put(f, NULL); 500 break; 501 502 case LINUX_FUTEX_CMP_REQUEUE: 503 504 LINUX_CTR5(sys_futex, "CMP_REQUEUE uaddr %p " 505 "val %d val3 %d uaddr2 %p val2 %d", 506 args->uaddr, args->val, args->val3, args->uaddr2, 507 (int)(unsigned long)args->timeout); 508 509 #ifdef DEBUG 510 if (ldebug(sys_futex)) 511 printf(ARGS(sys_futex, "futex_cmp_requeue uaddr %p " 512 "val %d val3 %d uaddr2 %p val2 %d"), 513 args->uaddr, args->val, args->val3, args->uaddr2, 514 (int)(unsigned long)args->timeout); 515 #endif 516 517 /* 518 * Linux allows this, we would not, it is an incorrect 519 * usage of declared ABI, so return EINVAL. 520 */ 521 if (args->uaddr == args->uaddr2) 522 return (EINVAL); 523 error = futex_get0(args->uaddr, &f, 0); 524 if (error) 525 return (error); 526 527 /* 528 * To avoid deadlocks return EINVAL if second futex 529 * exists at this time. Otherwise create the new futex 530 * and ignore false positive LOR which thus happens. 531 * 532 * Glibc fall back to FUTEX_WAKE in case of any error 533 * returned by FUTEX_CMP_REQUEUE. 534 */ 535 error = futex_get0(args->uaddr2, &f2, FUTEX_DONTEXISTS); 536 if (error) { 537 futex_put(f, NULL); 538 return (error); 539 } 540 error = copyin(args->uaddr, &val, sizeof(val)); 541 if (error) { 542 LINUX_CTR1(sys_futex, "CMP_REQUEUE copyin failed %d", 543 error); 544 futex_put(f2, NULL); 545 futex_put(f, NULL); 546 return (error); 547 } 548 if (val != args->val3) { 549 LINUX_CTR2(sys_futex, "CMP_REQUEUE val %d != uval %d", 550 args->val, val); 551 futex_put(f2, NULL); 552 futex_put(f, NULL); 553 return (EAGAIN); 554 } 555 556 nrwake = (int)(unsigned long)args->timeout; 557 td->td_retval[0] = futex_requeue(f, args->val, f2, nrwake); 558 futex_put(f2, NULL); 559 futex_put(f, NULL); 560 break; 561 562 case LINUX_FUTEX_WAKE_OP: 563 564 LINUX_CTR5(sys_futex, "WAKE_OP " 565 "uaddr %p op %d val %x uaddr2 %p val3 %x", 566 args->uaddr, args->op, args->val, 567 args->uaddr2, args->val3); 568 569 #ifdef DEBUG 570 if (ldebug(sys_futex)) 571 printf(ARGS(sys_futex, "futex_wake_op " 572 "uaddr %p op %d val %x uaddr2 %p val3 %x"), 573 args->uaddr, args->op, args->val, 574 args->uaddr2, args->val3); 575 #endif 576 error = futex_get0(args->uaddr, &f, 0); 577 if (error) 578 return (error); 579 if (args->uaddr != args->uaddr2) 580 error = futex_get0(args->uaddr2, &f2, 0); 581 if (error) { 582 futex_put(f, NULL); 583 return (error); 584 } 585 586 /* 587 * This function returns positive number as results and 588 * negative as errors 589 */ 590 op_ret = futex_atomic_op(td, args->val3, args->uaddr2); 591 592 if (op_ret < 0) { 593 /* XXX: We don't handle the EFAULT yet. */ 594 if (op_ret != -EFAULT) { 595 if (f2 != NULL) 596 futex_put(f2, NULL); 597 futex_put(f, NULL); 598 return (-op_ret); 599 } 600 if (f2 != NULL) 601 futex_put(f2, NULL); 602 futex_put(f, NULL); 603 return (EFAULT); 604 } 605 606 ret = futex_wake(f, args->val); 607 608 if (op_ret > 0) { 609 op_ret = 0; 610 nrwake = (int)(unsigned long)args->timeout; 611 612 if (f2 != NULL) 613 op_ret += futex_wake(f2, nrwake); 614 else 615 op_ret += futex_wake(f, nrwake); 616 ret += op_ret; 617 618 } 619 if (f2 != NULL) 620 futex_put(f2, NULL); 621 futex_put(f, NULL); 622 td->td_retval[0] = ret; 623 break; 624 625 case LINUX_FUTEX_LOCK_PI: 626 /* not yet implemented */ 627 return (ENOSYS); 628 629 case LINUX_FUTEX_UNLOCK_PI: 630 /* not yet implemented */ 631 return (ENOSYS); 632 633 case LINUX_FUTEX_TRYLOCK_PI: 634 /* not yet implemented */ 635 return (ENOSYS); 636 637 case LINUX_FUTEX_REQUEUE: 638 639 /* 640 * Glibc does not use this operation since version 2.3.3, 641 * as it is racy and replaced by FUTEX_CMP_REQUEUE operation. 642 * Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when 643 * FUTEX_REQUEUE returned EINVAL. 644 */ 645 em = em_find(td->td_proc, EMUL_DONTLOCK); 646 if (em->used_requeue == 0) { 647 printf("linux(%s (%d)) sys_futex: " 648 "unsupported futex_requeue op\n", 649 td->td_proc->p_comm, td->td_proc->p_pid); 650 em->used_requeue = 1; 651 } 652 return (EINVAL); 653 654 default: 655 printf("linux_sys_futex: unknown op %d\n", args->op); 656 return (ENOSYS); 657 } 658 659 return (error); 660 } 661 662 int 663 linux_set_robust_list(struct thread *td, struct linux_set_robust_list_args *args) 664 { 665 struct linux_emuldata *em; 666 667 #ifdef DEBUG 668 if (ldebug(set_robust_list)) 669 printf(ARGS(set_robust_list, "head %p len %d"), 670 args->head, args->len); 671 #endif 672 673 if (args->len != sizeof(struct linux_robust_list_head)) 674 return (EINVAL); 675 676 em = em_find(td->td_proc, EMUL_DOLOCK); 677 em->robust_futexes = args->head; 678 EMUL_UNLOCK(&emul_lock); 679 680 return (0); 681 } 682 683 int 684 linux_get_robust_list(struct thread *td, struct linux_get_robust_list_args *args) 685 { 686 struct linux_emuldata *em; 687 struct linux_robust_list_head *head; 688 l_size_t len = sizeof(struct linux_robust_list_head); 689 int error = 0; 690 691 #ifdef DEBUG 692 if (ldebug(get_robust_list)) 693 printf(ARGS(get_robust_list, "")); 694 #endif 695 696 if (!args->pid) { 697 em = em_find(td->td_proc, EMUL_DONTLOCK); 698 head = em->robust_futexes; 699 } else { 700 struct proc *p; 701 702 p = pfind(args->pid); 703 if (p == NULL) 704 return (ESRCH); 705 706 em = em_find(p, EMUL_DONTLOCK); 707 /* XXX: ptrace? */ 708 if (priv_check(td, PRIV_CRED_SETUID) || 709 priv_check(td, PRIV_CRED_SETEUID) || 710 p_candebug(td, p)) { 711 PROC_UNLOCK(p); 712 return (EPERM); 713 } 714 head = em->robust_futexes; 715 716 PROC_UNLOCK(p); 717 } 718 719 error = copyout(&len, args->len, sizeof(l_size_t)); 720 if (error) 721 return (EFAULT); 722 723 error = copyout(head, args->head, sizeof(struct linux_robust_list_head)); 724 725 return (error); 726 } 727 728 static int 729 handle_futex_death(struct proc *p, uint32_t *uaddr, int pi) 730 { 731 uint32_t uval, nval, mval; 732 struct futex *f; 733 int error; 734 735 retry: 736 if (copyin(uaddr, &uval, 4)) 737 return (EFAULT); 738 if ((uval & FUTEX_TID_MASK) == p->p_pid) { 739 mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED; 740 nval = casuword32(uaddr, uval, mval); 741 742 if (nval == -1) 743 return (EFAULT); 744 745 if (nval != uval) 746 goto retry; 747 748 if (!pi && (uval & FUTEX_WAITERS)) { 749 error = futex_get(uaddr, NULL, &f, 750 FUTEX_DONTCREATE); 751 if (error) 752 return (error); 753 if (f != NULL) { 754 futex_wake(f, 1); 755 futex_put(f, NULL); 756 } 757 } 758 } 759 760 return (0); 761 } 762 763 static int 764 fetch_robust_entry(struct linux_robust_list **entry, 765 struct linux_robust_list **head, int *pi) 766 { 767 l_ulong uentry; 768 769 if (copyin((const void *)head, &uentry, sizeof(l_ulong))) 770 return (EFAULT); 771 772 *entry = (void *)(uentry & ~1UL); 773 *pi = uentry & 1; 774 775 return (0); 776 } 777 778 /* This walks the list of robust futexes releasing them. */ 779 void 780 release_futexes(struct proc *p) 781 { 782 struct linux_robust_list_head *head = NULL; 783 struct linux_robust_list *entry, *next_entry, *pending; 784 unsigned int limit = 2048, pi, next_pi, pip; 785 struct linux_emuldata *em; 786 l_long futex_offset; 787 int rc; 788 789 em = em_find(p, EMUL_DONTLOCK); 790 head = em->robust_futexes; 791 792 if (head == NULL) 793 return; 794 795 if (fetch_robust_entry(&entry, PTRIN(&head->list.next), &pi)) 796 return; 797 798 if (copyin(&head->futex_offset, &futex_offset, sizeof(futex_offset))) 799 return; 800 801 if (fetch_robust_entry(&pending, PTRIN(&head->pending_list), &pip)) 802 return; 803 804 while (entry != &head->list) { 805 rc = fetch_robust_entry(&next_entry, PTRIN(&entry->next), &next_pi); 806 807 if (entry != pending) 808 if (handle_futex_death(p, (uint32_t *)entry + futex_offset, pi)) 809 return; 810 if (rc) 811 return; 812 813 entry = next_entry; 814 pi = next_pi; 815 816 if (!--limit) 817 break; 818 819 sched_relinquish(curthread); 820 } 821 822 if (pending) 823 handle_futex_death(p, (uint32_t *)pending + futex_offset, pip); 824 } 825