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sys/compat/linux/linux_futex.c
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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: releng/8.2/sys/compat/linux/linux_futex.c 215857 2010-11-26 11:02:51Z netchild $"); 36 #if 0 37 __KERNEL_RCSID(1, "$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 clockrt, nrwake, op_ret, ret, val; 432 struct linux_emuldata *em; 433 struct waiting_proc *wp; 434 struct futex *f, *f2 = NULL; 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 /* 447 * Currently support for switching between CLOCK_MONOTONIC and 448 * CLOCK_REALTIME is not present. However Linux forbids the use of 449 * FUTEX_CLOCK_REALTIME with any op except FUTEX_WAIT_BITSET and 450 * FUTEX_WAIT_REQUEUE_PI. 451 */ 452 clockrt = args->op & LINUX_FUTEX_CLOCK_REALTIME; 453 args->op = args->op & ~LINUX_FUTEX_CLOCK_REALTIME; 454 if (clockrt && args->op != LINUX_FUTEX_WAIT_BITSET && 455 args->op != LINUX_FUTEX_WAIT_REQUEUE_PI) 456 return (ENOSYS); 457 458 switch (args->op) { 459 case LINUX_FUTEX_WAIT: 460 461 LINUX_CTR2(sys_futex, "WAIT val %d uaddr %p", 462 args->val, args->uaddr); 463 #ifdef DEBUG 464 if (ldebug(sys_futex)) 465 printf(ARGS(sys_futex, "futex_wait val %d uaddr %p"), 466 args->val, args->uaddr); 467 #endif 468 error = futex_get(args->uaddr, &wp, &f, FUTEX_CREATE_WP); 469 if (error) 470 return (error); 471 error = copyin(args->uaddr, &val, sizeof(val)); 472 if (error) { 473 LINUX_CTR1(sys_futex, "WAIT copyin failed %d", 474 error); 475 futex_put(f, wp); 476 return (error); 477 } 478 if (val != args->val) { 479 LINUX_CTR3(sys_futex, "WAIT uaddr %p val %d != uval %d", 480 args->uaddr, args->val, val); 481 futex_put(f, wp); 482 return (EWOULDBLOCK); 483 } 484 485 error = futex_wait(f, wp, args->timeout); 486 break; 487 488 case LINUX_FUTEX_WAKE: 489 490 LINUX_CTR2(sys_futex, "WAKE val %d uaddr %p", 491 args->val, args->uaddr); 492 493 /* 494 * XXX: Linux is able to cope with different addresses 495 * corresponding to the same mapped memory in the sleeping 496 * and waker process(es). 497 */ 498 #ifdef DEBUG 499 if (ldebug(sys_futex)) 500 printf(ARGS(sys_futex, "futex_wake val %d uaddr %p"), 501 args->val, args->uaddr); 502 #endif 503 error = futex_get(args->uaddr, NULL, &f, FUTEX_DONTCREATE); 504 if (error) 505 return (error); 506 if (f == NULL) { 507 td->td_retval[0] = 0; 508 return (error); 509 } 510 td->td_retval[0] = futex_wake(f, args->val); 511 futex_put(f, NULL); 512 break; 513 514 case LINUX_FUTEX_CMP_REQUEUE: 515 516 LINUX_CTR5(sys_futex, "CMP_REQUEUE uaddr %p " 517 "val %d val3 %d uaddr2 %p val2 %d", 518 args->uaddr, args->val, args->val3, args->uaddr2, 519 (int)(unsigned long)args->timeout); 520 521 #ifdef DEBUG 522 if (ldebug(sys_futex)) 523 printf(ARGS(sys_futex, "futex_cmp_requeue uaddr %p " 524 "val %d val3 %d uaddr2 %p val2 %d"), 525 args->uaddr, args->val, args->val3, args->uaddr2, 526 (int)(unsigned long)args->timeout); 527 #endif 528 529 /* 530 * Linux allows this, we would not, it is an incorrect 531 * usage of declared ABI, so return EINVAL. 532 */ 533 if (args->uaddr == args->uaddr2) 534 return (EINVAL); 535 error = futex_get0(args->uaddr, &f, 0); 536 if (error) 537 return (error); 538 539 /* 540 * To avoid deadlocks return EINVAL if second futex 541 * exists at this time. Otherwise create the new futex 542 * and ignore false positive LOR which thus happens. 543 * 544 * Glibc fall back to FUTEX_WAKE in case of any error 545 * returned by FUTEX_CMP_REQUEUE. 546 */ 547 error = futex_get0(args->uaddr2, &f2, FUTEX_DONTEXISTS); 548 if (error) { 549 futex_put(f, NULL); 550 return (error); 551 } 552 error = copyin(args->uaddr, &val, sizeof(val)); 553 if (error) { 554 LINUX_CTR1(sys_futex, "CMP_REQUEUE copyin failed %d", 555 error); 556 futex_put(f2, NULL); 557 futex_put(f, NULL); 558 return (error); 559 } 560 if (val != args->val3) { 561 LINUX_CTR2(sys_futex, "CMP_REQUEUE val %d != uval %d", 562 args->val, val); 563 futex_put(f2, NULL); 564 futex_put(f, NULL); 565 return (EAGAIN); 566 } 567 568 nrwake = (int)(unsigned long)args->timeout; 569 td->td_retval[0] = futex_requeue(f, args->val, f2, nrwake); 570 futex_put(f2, NULL); 571 futex_put(f, NULL); 572 break; 573 574 case LINUX_FUTEX_WAKE_OP: 575 576 LINUX_CTR5(sys_futex, "WAKE_OP " 577 "uaddr %p op %d val %x uaddr2 %p val3 %x", 578 args->uaddr, args->op, args->val, 579 args->uaddr2, args->val3); 580 581 #ifdef DEBUG 582 if (ldebug(sys_futex)) 583 printf(ARGS(sys_futex, "futex_wake_op " 584 "uaddr %p op %d val %x uaddr2 %p val3 %x"), 585 args->uaddr, args->op, args->val, 586 args->uaddr2, args->val3); 587 #endif 588 error = futex_get0(args->uaddr, &f, 0); 589 if (error) 590 return (error); 591 if (args->uaddr != args->uaddr2) 592 error = futex_get0(args->uaddr2, &f2, 0); 593 if (error) { 594 futex_put(f, NULL); 595 return (error); 596 } 597 598 /* 599 * This function returns positive number as results and 600 * negative as errors 601 */ 602 op_ret = futex_atomic_op(td, args->val3, args->uaddr2); 603 604 if (op_ret < 0) { 605 /* XXX: We don't handle the EFAULT yet. */ 606 if (op_ret != -EFAULT) { 607 if (f2 != NULL) 608 futex_put(f2, NULL); 609 futex_put(f, NULL); 610 return (-op_ret); 611 } 612 if (f2 != NULL) 613 futex_put(f2, NULL); 614 futex_put(f, NULL); 615 return (EFAULT); 616 } 617 618 ret = futex_wake(f, args->val); 619 620 if (op_ret > 0) { 621 op_ret = 0; 622 nrwake = (int)(unsigned long)args->timeout; 623 624 if (f2 != NULL) 625 op_ret += futex_wake(f2, nrwake); 626 else 627 op_ret += futex_wake(f, nrwake); 628 ret += op_ret; 629 630 } 631 if (f2 != NULL) 632 futex_put(f2, NULL); 633 futex_put(f, NULL); 634 td->td_retval[0] = ret; 635 break; 636 637 case LINUX_FUTEX_LOCK_PI: 638 /* not yet implemented */ 639 linux_msg(td, 640 "linux_sys_futex: " 641 "op LINUX_FUTEX_LOCK_PI not implemented\n"); 642 return (ENOSYS); 643 644 case LINUX_FUTEX_UNLOCK_PI: 645 /* not yet implemented */ 646 linux_msg(td, 647 "linux_sys_futex: " 648 "op LINUX_FUTEX_UNLOCK_PI not implemented\n"); 649 return (ENOSYS); 650 651 case LINUX_FUTEX_TRYLOCK_PI: 652 /* not yet implemented */ 653 linux_msg(td, 654 "linux_sys_futex: " 655 "op LINUX_FUTEX_TRYLOCK_PI not implemented\n"); 656 return (ENOSYS); 657 658 case LINUX_FUTEX_REQUEUE: 659 660 /* 661 * Glibc does not use this operation since version 2.3.3, 662 * as it is racy and replaced by FUTEX_CMP_REQUEUE operation. 663 * Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when 664 * FUTEX_REQUEUE returned EINVAL. 665 */ 666 em = em_find(td->td_proc, EMUL_DONTLOCK); 667 if (em->used_requeue == 0) { 668 linux_msg(td, 669 "linux_sys_futex: " 670 "unsupported futex_requeue op\n"); 671 em->used_requeue = 1; 672 } 673 return (EINVAL); 674 675 case LINUX_FUTEX_WAIT_BITSET: 676 /* not yet implemented */ 677 linux_msg(td, 678 "linux_sys_futex: " 679 "op FUTEX_WAIT_BITSET not implemented\n"); 680 return (ENOSYS); 681 682 case LINUX_FUTEX_WAIT_REQUEUE_PI: 683 /* not yet implemented */ 684 linux_msg(td, 685 "linux_sys_futex: " 686 "op FUTEX_WAIT_REQUEUE_PI not implemented\n"); 687 return (ENOSYS); 688 689 default: 690 linux_msg(td, 691 "linux_sys_futex: unknown op %d\n", args->op); 692 return (ENOSYS); 693 } 694 695 return (error); 696 } 697 698 int 699 linux_set_robust_list(struct thread *td, struct linux_set_robust_list_args *args) 700 { 701 struct linux_emuldata *em; 702 703 #ifdef DEBUG 704 if (ldebug(set_robust_list)) 705 printf(ARGS(set_robust_list, "head %p len %d"), 706 args->head, args->len); 707 #endif 708 709 if (args->len != sizeof(struct linux_robust_list_head)) 710 return (EINVAL); 711 712 em = em_find(td->td_proc, EMUL_DOLOCK); 713 em->robust_futexes = args->head; 714 EMUL_UNLOCK(&emul_lock); 715 716 return (0); 717 } 718 719 int 720 linux_get_robust_list(struct thread *td, struct linux_get_robust_list_args *args) 721 { 722 struct linux_emuldata *em; 723 struct linux_robust_list_head *head; 724 l_size_t len = sizeof(struct linux_robust_list_head); 725 int error = 0; 726 727 #ifdef DEBUG 728 if (ldebug(get_robust_list)) 729 printf(ARGS(get_robust_list, "")); 730 #endif 731 732 if (!args->pid) { 733 em = em_find(td->td_proc, EMUL_DONTLOCK); 734 head = em->robust_futexes; 735 } else { 736 struct proc *p; 737 738 p = pfind(args->pid); 739 if (p == NULL) 740 return (ESRCH); 741 742 em = em_find(p, EMUL_DONTLOCK); 743 /* XXX: ptrace? */ 744 if (priv_check(td, PRIV_CRED_SETUID) || 745 priv_check(td, PRIV_CRED_SETEUID) || 746 p_candebug(td, p)) { 747 PROC_UNLOCK(p); 748 return (EPERM); 749 } 750 head = em->robust_futexes; 751 752 PROC_UNLOCK(p); 753 } 754 755 error = copyout(&len, args->len, sizeof(l_size_t)); 756 if (error) 757 return (EFAULT); 758 759 error = copyout(head, args->head, sizeof(struct linux_robust_list_head)); 760 761 return (error); 762 } 763 764 static int 765 handle_futex_death(struct proc *p, uint32_t *uaddr, int pi) 766 { 767 uint32_t uval, nval, mval; 768 struct futex *f; 769 int error; 770 771 retry: 772 if (copyin(uaddr, &uval, 4)) 773 return (EFAULT); 774 if ((uval & FUTEX_TID_MASK) == p->p_pid) { 775 mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED; 776 nval = casuword32(uaddr, uval, mval); 777 778 if (nval == -1) 779 return (EFAULT); 780 781 if (nval != uval) 782 goto retry; 783 784 if (!pi && (uval & FUTEX_WAITERS)) { 785 error = futex_get(uaddr, NULL, &f, 786 FUTEX_DONTCREATE); 787 if (error) 788 return (error); 789 if (f != NULL) { 790 futex_wake(f, 1); 791 futex_put(f, NULL); 792 } 793 } 794 } 795 796 return (0); 797 } 798 799 static int 800 fetch_robust_entry(struct linux_robust_list **entry, 801 struct linux_robust_list **head, int *pi) 802 { 803 l_ulong uentry; 804 805 if (copyin((const void *)head, &uentry, sizeof(l_ulong))) 806 return (EFAULT); 807 808 *entry = (void *)(uentry & ~1UL); 809 *pi = uentry & 1; 810 811 return (0); 812 } 813 814 /* This walks the list of robust futexes releasing them. */ 815 void 816 release_futexes(struct proc *p) 817 { 818 struct linux_robust_list_head *head = NULL; 819 struct linux_robust_list *entry, *next_entry, *pending; 820 unsigned int limit = 2048, pi, next_pi, pip; 821 struct linux_emuldata *em; 822 l_long futex_offset; 823 int rc; 824 825 em = em_find(p, EMUL_DONTLOCK); 826 head = em->robust_futexes; 827 828 if (head == NULL) 829 return; 830 831 if (fetch_robust_entry(&entry, PTRIN(&head->list.next), &pi)) 832 return; 833 834 if (copyin(&head->futex_offset, &futex_offset, sizeof(futex_offset))) 835 return; 836 837 if (fetch_robust_entry(&pending, PTRIN(&head->pending_list), &pip)) 838 return; 839 840 while (entry != &head->list) { 841 rc = fetch_robust_entry(&next_entry, PTRIN(&entry->next), &next_pi); 842 843 if (entry != pending) 844 if (handle_futex_death(p, (uint32_t *)entry + futex_offset, pi)) 845 return; 846 if (rc) 847 return; 848 849 entry = next_entry; 850 pi = next_pi; 851 852 if (!--limit) 853 break; 854 855 sched_relinquish(curthread); 856 } 857 858 if (pending) 859 handle_futex_death(p, (uint32_t *)pending + futex_offset, pip); 860 }
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