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/8.1/sys/compat/linux/linux_futex.c 203786 2010-02-11 18:34:06Z mjacob $");
36 #if 0
37 __KERNEL_RCSID(1, "$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 }
Cache object: 635424f4521e809999695807b30f57ff
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