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: stable/12/sys/compat/linux/linux_futex.c 370058 2021-06-29 20:01:48Z markj $");
40 #if 0
41 __KERNEL_RCSID(1, "$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_DEFINE2(futex, futex_put, entry, "struct futex *",
95 "struct waiting_proc *");
96 LIN_SDT_PROBE_DEFINE3(futex, futex_put, destroy, "uint32_t *", "uint32_t",
97 "int");
98 LIN_SDT_PROBE_DEFINE3(futex, futex_put, unlock, "uint32_t *", "uint32_t",
99 "int");
100 LIN_SDT_PROBE_DEFINE0(futex, futex_put, return);
101 LIN_SDT_PROBE_DEFINE3(futex, futex_get0, entry, "uint32_t *", "struct futex **",
102 "uint32_t");
103 LIN_SDT_PROBE_DEFINE1(futex, futex_get0, umtx_key_get_error, "int");
104 LIN_SDT_PROBE_DEFINE3(futex, futex_get0, shared, "uint32_t *", "uint32_t",
105 "int");
106 LIN_SDT_PROBE_DEFINE1(futex, futex_get0, null, "uint32_t *");
107 LIN_SDT_PROBE_DEFINE3(futex, futex_get0, new, "uint32_t *", "uint32_t", "int");
108 LIN_SDT_PROBE_DEFINE1(futex, futex_get0, return, "int");
109 LIN_SDT_PROBE_DEFINE3(futex, futex_get, entry, "uint32_t *",
110 "struct waiting_proc **", "struct futex **");
111 LIN_SDT_PROBE_DEFINE0(futex, futex_get, error);
112 LIN_SDT_PROBE_DEFINE1(futex, futex_get, return, "int");
113 LIN_SDT_PROBE_DEFINE3(futex, futex_sleep, entry, "struct futex *",
114 "struct waiting_proc **", "struct timespec *");
115 LIN_SDT_PROBE_DEFINE5(futex, futex_sleep, requeue_error, "int", "uint32_t *",
116 "struct waiting_proc *", "uint32_t *", "uint32_t");
117 LIN_SDT_PROBE_DEFINE3(futex, futex_sleep, sleep_error, "int", "uint32_t *",
118 "struct waiting_proc *");
119 LIN_SDT_PROBE_DEFINE1(futex, futex_sleep, return, "int");
120 LIN_SDT_PROBE_DEFINE3(futex, futex_wake, entry, "struct futex *", "int",
121 "uint32_t");
122 LIN_SDT_PROBE_DEFINE3(futex, futex_wake, iterate, "uint32_t",
123 "struct waiting_proc *", "uint32_t");
124 LIN_SDT_PROBE_DEFINE1(futex, futex_wake, wakeup, "struct waiting_proc *");
125 LIN_SDT_PROBE_DEFINE1(futex, futex_wake, return, "int");
126 LIN_SDT_PROBE_DEFINE4(futex, futex_requeue, entry, "struct futex *", "int",
127 "struct futex *", "int");
128 LIN_SDT_PROBE_DEFINE1(futex, futex_requeue, wakeup, "struct waiting_proc *");
129 LIN_SDT_PROBE_DEFINE3(futex, futex_requeue, requeue, "uint32_t *",
130 "struct waiting_proc *", "uint32_t");
131 LIN_SDT_PROBE_DEFINE1(futex, futex_requeue, return, "int");
132 LIN_SDT_PROBE_DEFINE4(futex, futex_wait, entry, "struct futex *",
133 "struct waiting_proc **", "struct timespec *", "uint32_t");
134 LIN_SDT_PROBE_DEFINE1(futex, futex_wait, sleep_error, "int");
135 LIN_SDT_PROBE_DEFINE1(futex, futex_wait, return, "int");
136 LIN_SDT_PROBE_DEFINE3(futex, futex_atomic_op, entry, "struct thread *",
137 "int", "uint32_t");
138 LIN_SDT_PROBE_DEFINE4(futex, futex_atomic_op, decoded_op, "int", "int", "int",
139 "int");
140 LIN_SDT_PROBE_DEFINE0(futex, futex_atomic_op, missing_access_check);
141 LIN_SDT_PROBE_DEFINE1(futex, futex_atomic_op, unimplemented_op, "int");
142 LIN_SDT_PROBE_DEFINE1(futex, futex_atomic_op, unimplemented_cmp, "int");
143 LIN_SDT_PROBE_DEFINE1(futex, futex_atomic_op, return, "int");
144 LIN_SDT_PROBE_DEFINE2(futex, linux_sys_futex, entry, "struct thread *",
145 "struct linux_sys_futex_args *");
146 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_clockswitch);
147 LIN_SDT_PROBE_DEFINE1(futex, linux_sys_futex, copyin_error, "int");
148 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, invalid_cmp_requeue_use);
149 LIN_SDT_PROBE_DEFINE3(futex, linux_sys_futex, debug_wait, "uint32_t *",
150 "uint32_t", "uint32_t");
151 LIN_SDT_PROBE_DEFINE4(futex, linux_sys_futex, debug_wait_value_neq,
152 "uint32_t *", "uint32_t", "int", "uint32_t");
153 LIN_SDT_PROBE_DEFINE3(futex, linux_sys_futex, debug_wake, "uint32_t *",
154 "uint32_t", "uint32_t");
155 LIN_SDT_PROBE_DEFINE5(futex, linux_sys_futex, debug_cmp_requeue, "uint32_t *",
156 "uint32_t", "uint32_t", "uint32_t *", "struct l_timespec *");
157 LIN_SDT_PROBE_DEFINE2(futex, linux_sys_futex, debug_cmp_requeue_value_neq,
158 "uint32_t", "int");
159 LIN_SDT_PROBE_DEFINE5(futex, linux_sys_futex, debug_wake_op, "uint32_t *",
160 "int", "uint32_t", "uint32_t *", "uint32_t");
161 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unhandled_efault);
162 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_lock_pi);
163 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_unlock_pi);
164 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_trylock_pi);
165 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, deprecated_requeue);
166 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_wait_requeue_pi);
167 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_cmp_requeue_pi);
168 LIN_SDT_PROBE_DEFINE1(futex, linux_sys_futex, unknown_operation, "int");
169 LIN_SDT_PROBE_DEFINE1(futex, linux_sys_futex, return, "int");
170 LIN_SDT_PROBE_DEFINE2(futex, linux_set_robust_list, entry, "struct thread *",
171 "struct linux_set_robust_list_args *");
172 LIN_SDT_PROBE_DEFINE0(futex, linux_set_robust_list, size_error);
173 LIN_SDT_PROBE_DEFINE1(futex, linux_set_robust_list, return, "int");
174 LIN_SDT_PROBE_DEFINE2(futex, linux_get_robust_list, entry, "struct thread *",
175 "struct linux_get_robust_list_args *");
176 LIN_SDT_PROBE_DEFINE1(futex, linux_get_robust_list, copyout_error, "int");
177 LIN_SDT_PROBE_DEFINE1(futex, linux_get_robust_list, return, "int");
178 LIN_SDT_PROBE_DEFINE3(futex, handle_futex_death, entry,
179 "struct linux_emuldata *", "uint32_t *", "unsigned int");
180 LIN_SDT_PROBE_DEFINE1(futex, handle_futex_death, copyin_error, "int");
181 LIN_SDT_PROBE_DEFINE1(futex, handle_futex_death, return, "int");
182 LIN_SDT_PROBE_DEFINE3(futex, fetch_robust_entry, entry,
183 "struct linux_robust_list **", "struct linux_robust_list **",
184 "unsigned int *");
185 LIN_SDT_PROBE_DEFINE1(futex, fetch_robust_entry, copyin_error, "int");
186 LIN_SDT_PROBE_DEFINE1(futex, fetch_robust_entry, return, "int");
187 LIN_SDT_PROBE_DEFINE2(futex, release_futexes, entry, "struct thread *",
188 "struct linux_emuldata *");
189 LIN_SDT_PROBE_DEFINE1(futex, release_futexes, copyin_error, "int");
190 LIN_SDT_PROBE_DEFINE0(futex, release_futexes, return);
191
192 struct futex;
193
194 struct waiting_proc {
195 uint32_t wp_flags;
196 struct futex *wp_futex;
197 TAILQ_ENTRY(waiting_proc) wp_list;
198 };
199
200 struct futex {
201 struct mtx f_lck;
202 uint32_t *f_uaddr; /* user-supplied value, for debug */
203 struct umtx_key f_key;
204 uint32_t f_refcount;
205 uint32_t f_bitset;
206 LIST_ENTRY(futex) f_list;
207 TAILQ_HEAD(lf_waiting_proc, waiting_proc) f_waiting_proc;
208 };
209
210 #define FUTEX_LOCK(f) mtx_lock(&(f)->f_lck)
211 #define FUTEX_LOCKED(f) mtx_owned(&(f)->f_lck)
212 #define FUTEX_UNLOCK(f) mtx_unlock(&(f)->f_lck)
213 #define FUTEX_INIT(f) do { \
214 mtx_init(&(f)->f_lck, "ftlk", NULL, \
215 MTX_DUPOK); \
216 LIN_SDT_PROBE1(futex, futex, create, \
217 &(f)->f_lck); \
218 } while (0)
219 #define FUTEX_DESTROY(f) do { \
220 LIN_SDT_PROBE1(futex, futex, destroy, \
221 &(f)->f_lck); \
222 mtx_destroy(&(f)->f_lck); \
223 } while (0)
224 #define FUTEX_ASSERT_LOCKED(f) mtx_assert(&(f)->f_lck, MA_OWNED)
225 #define FUTEX_ASSERT_UNLOCKED(f) mtx_assert(&(f)->f_lck, MA_NOTOWNED)
226
227 #define FUTEXES_LOCK do { \
228 mtx_lock(&futex_mtx); \
229 LIN_SDT_PROBE1(locks, futex_mtx, \
230 locked, &futex_mtx); \
231 } while (0)
232 #define FUTEXES_UNLOCK do { \
233 LIN_SDT_PROBE1(locks, futex_mtx, \
234 unlock, &futex_mtx); \
235 mtx_unlock(&futex_mtx); \
236 } while (0)
237
238 /* flags for futex_get() */
239 #define FUTEX_CREATE_WP 0x1 /* create waiting_proc */
240 #define FUTEX_DONTCREATE 0x2 /* don't create futex if not exists */
241 #define FUTEX_DONTEXISTS 0x4 /* return EINVAL if futex exists */
242 #define FUTEX_SHARED 0x8 /* shared futex */
243 #define FUTEX_DONTLOCK 0x10 /* don't lock futex */
244
245 /* wp_flags */
246 #define FUTEX_WP_REQUEUED 0x1 /* wp requeued - wp moved from wp_list
247 * of futex where thread sleep to wp_list
248 * of another futex.
249 */
250 #define FUTEX_WP_REMOVED 0x2 /* wp is woken up and removed from futex
251 * wp_list to prevent double wakeup.
252 */
253
254 static void futex_put(struct futex *, struct waiting_proc *);
255 static int futex_get0(uint32_t *, struct futex **f, uint32_t);
256 static int futex_get(uint32_t *, struct waiting_proc **, struct futex **,
257 uint32_t);
258 static int futex_sleep(struct futex *, struct waiting_proc *, struct timespec *);
259 static int futex_wake(struct futex *, int, uint32_t);
260 static int futex_requeue(struct futex *, int, struct futex *, int);
261 static int futex_copyin_timeout(int, struct l_timespec *, int,
262 struct timespec *);
263 static int futex_wait(struct futex *, struct waiting_proc *, struct timespec *,
264 uint32_t);
265 static void futex_lock(struct futex *);
266 static void futex_unlock(struct futex *);
267 static int futex_atomic_op(struct thread *, int, uint32_t *);
268 static int handle_futex_death(struct linux_emuldata *, uint32_t *,
269 unsigned int);
270 static int fetch_robust_entry(struct linux_robust_list **,
271 struct linux_robust_list **, unsigned int *);
272
273 static int
futex_copyin_timeout(int op,struct l_timespec * luts,int clockrt,struct timespec * ts)274 futex_copyin_timeout(int op, struct l_timespec *luts, int clockrt,
275 struct timespec *ts)
276 {
277 struct l_timespec lts;
278 struct timespec kts;
279 int error;
280
281 error = copyin(luts, <s, sizeof(lts));
282 if (error)
283 return (error);
284
285 error = linux_to_native_timespec(ts, <s);
286 if (error)
287 return (error);
288 if (clockrt) {
289 nanotime(&kts);
290 timespecsub(ts, &kts, ts);
291 } else if (op == LINUX_FUTEX_WAIT_BITSET) {
292 nanouptime(&kts);
293 timespecsub(ts, &kts, ts);
294 }
295 return (error);
296 }
297
298 static void
futex_put(struct futex * f,struct waiting_proc * wp)299 futex_put(struct futex *f, struct waiting_proc *wp)
300 {
301 LIN_SDT_PROBE2(futex, futex_put, entry, f, wp);
302
303 if (wp != NULL) {
304 if ((wp->wp_flags & FUTEX_WP_REMOVED) == 0)
305 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
306 free(wp, M_FUTEX_WP);
307 }
308
309 FUTEXES_LOCK;
310 if (--f->f_refcount == 0) {
311 LIST_REMOVE(f, f_list);
312 FUTEXES_UNLOCK;
313 if (FUTEX_LOCKED(f))
314 futex_unlock(f);
315
316 LIN_SDT_PROBE3(futex, futex_put, destroy, f->f_uaddr,
317 f->f_refcount, f->f_key.shared);
318 LINUX_CTR3(sys_futex, "futex_put destroy uaddr %p ref %d "
319 "shared %d", f->f_uaddr, f->f_refcount, f->f_key.shared);
320 umtx_key_release(&f->f_key);
321 FUTEX_DESTROY(f);
322 free(f, M_FUTEX);
323
324 LIN_SDT_PROBE0(futex, futex_put, return);
325 return;
326 }
327
328 LIN_SDT_PROBE3(futex, futex_put, unlock, f->f_uaddr, f->f_refcount,
329 f->f_key.shared);
330 LINUX_CTR3(sys_futex, "futex_put uaddr %p ref %d shared %d",
331 f->f_uaddr, f->f_refcount, f->f_key.shared);
332 if (FUTEX_LOCKED(f))
333 futex_unlock(f);
334 FUTEXES_UNLOCK;
335
336 LIN_SDT_PROBE0(futex, futex_put, return);
337 }
338
339 static int
futex_get0(uint32_t * uaddr,struct futex ** newf,uint32_t flags)340 futex_get0(uint32_t *uaddr, struct futex **newf, uint32_t flags)
341 {
342 struct futex *f, *tmpf;
343 struct umtx_key key;
344 int error;
345
346 LIN_SDT_PROBE3(futex, futex_get0, entry, uaddr, newf, flags);
347
348 *newf = tmpf = NULL;
349
350 error = umtx_key_get(uaddr, TYPE_FUTEX, (flags & FUTEX_SHARED) ?
351 AUTO_SHARE : THREAD_SHARE, &key);
352 if (error) {
353 LIN_SDT_PROBE1(futex, futex_get0, umtx_key_get_error, error);
354 LIN_SDT_PROBE1(futex, futex_get0, return, error);
355 return (error);
356 }
357 retry:
358 FUTEXES_LOCK;
359 LIST_FOREACH(f, &futex_list, f_list) {
360 if (umtx_key_match(&f->f_key, &key)) {
361 if (tmpf != NULL) {
362 if (FUTEX_LOCKED(tmpf))
363 futex_unlock(tmpf);
364 FUTEX_DESTROY(tmpf);
365 free(tmpf, M_FUTEX);
366 }
367 if (flags & FUTEX_DONTEXISTS) {
368 FUTEXES_UNLOCK;
369 umtx_key_release(&key);
370
371 LIN_SDT_PROBE1(futex, futex_get0, return,
372 EINVAL);
373 return (EINVAL);
374 }
375
376 /*
377 * Increment refcount of the found futex to
378 * prevent it from deallocation before FUTEX_LOCK()
379 */
380 ++f->f_refcount;
381 FUTEXES_UNLOCK;
382 umtx_key_release(&key);
383
384 if ((flags & FUTEX_DONTLOCK) == 0)
385 futex_lock(f);
386 *newf = f;
387 LIN_SDT_PROBE3(futex, futex_get0, shared, uaddr,
388 f->f_refcount, f->f_key.shared);
389 LINUX_CTR3(sys_futex, "futex_get uaddr %p ref %d shared %d",
390 uaddr, f->f_refcount, f->f_key.shared);
391
392 LIN_SDT_PROBE1(futex, futex_get0, return, 0);
393 return (0);
394 }
395 }
396
397 if (flags & FUTEX_DONTCREATE) {
398 FUTEXES_UNLOCK;
399 umtx_key_release(&key);
400 LIN_SDT_PROBE1(futex, futex_get0, null, uaddr);
401 LINUX_CTR1(sys_futex, "futex_get uaddr %p null", uaddr);
402
403 LIN_SDT_PROBE1(futex, futex_get0, return, 0);
404 return (0);
405 }
406
407 if (tmpf == NULL) {
408 FUTEXES_UNLOCK;
409 tmpf = malloc(sizeof(*tmpf), M_FUTEX, M_WAITOK | M_ZERO);
410 tmpf->f_uaddr = uaddr;
411 tmpf->f_key = key;
412 tmpf->f_refcount = 1;
413 tmpf->f_bitset = FUTEX_BITSET_MATCH_ANY;
414 FUTEX_INIT(tmpf);
415 TAILQ_INIT(&tmpf->f_waiting_proc);
416
417 /*
418 * Lock the new futex before an insert into the futex_list
419 * to prevent futex usage by other.
420 */
421 if ((flags & FUTEX_DONTLOCK) == 0)
422 futex_lock(tmpf);
423 goto retry;
424 }
425
426 LIST_INSERT_HEAD(&futex_list, tmpf, f_list);
427 FUTEXES_UNLOCK;
428
429 LIN_SDT_PROBE3(futex, futex_get0, new, uaddr, tmpf->f_refcount,
430 tmpf->f_key.shared);
431 LINUX_CTR3(sys_futex, "futex_get uaddr %p ref %d shared %d new",
432 uaddr, tmpf->f_refcount, tmpf->f_key.shared);
433 *newf = tmpf;
434
435 LIN_SDT_PROBE1(futex, futex_get0, return, 0);
436 return (0);
437 }
438
439 static int
futex_get(uint32_t * uaddr,struct waiting_proc ** wp,struct futex ** f,uint32_t flags)440 futex_get(uint32_t *uaddr, struct waiting_proc **wp, struct futex **f,
441 uint32_t flags)
442 {
443 int error;
444
445 LIN_SDT_PROBE3(futex, futex_get, entry, uaddr, wp, f);
446
447 if (flags & FUTEX_CREATE_WP) {
448 *wp = malloc(sizeof(struct waiting_proc), M_FUTEX_WP, M_WAITOK);
449 (*wp)->wp_flags = 0;
450 }
451 error = futex_get0(uaddr, f, flags);
452 if (error) {
453 LIN_SDT_PROBE0(futex, futex_get, error);
454
455 if (flags & FUTEX_CREATE_WP)
456 free(*wp, M_FUTEX_WP);
457
458 LIN_SDT_PROBE1(futex, futex_get, return, error);
459 return (error);
460 }
461 if (flags & FUTEX_CREATE_WP) {
462 TAILQ_INSERT_HEAD(&(*f)->f_waiting_proc, *wp, wp_list);
463 (*wp)->wp_futex = *f;
464 }
465
466 LIN_SDT_PROBE1(futex, futex_get, return, error);
467 return (error);
468 }
469
470 static inline void
futex_lock(struct futex * f)471 futex_lock(struct futex *f)
472 {
473
474 LINUX_CTR3(sys_futex, "futex_lock uaddr %p ref %d shared %d",
475 f->f_uaddr, f->f_refcount, f->f_key.shared);
476 FUTEX_ASSERT_UNLOCKED(f);
477 FUTEX_LOCK(f);
478 }
479
480 static inline void
futex_unlock(struct futex * f)481 futex_unlock(struct futex *f)
482 {
483
484 LINUX_CTR3(sys_futex, "futex_unlock uaddr %p ref %d shared %d",
485 f->f_uaddr, f->f_refcount, f->f_key.shared);
486 FUTEX_ASSERT_LOCKED(f);
487 FUTEX_UNLOCK(f);
488 }
489
490 static int
futex_sleep(struct futex * f,struct waiting_proc * wp,struct timespec * ts)491 futex_sleep(struct futex *f, struct waiting_proc *wp, struct timespec *ts)
492 {
493 struct timespec uts;
494 sbintime_t sbt, prec, tmp;
495 time_t over;
496 int error;
497
498 FUTEX_ASSERT_LOCKED(f);
499 if (ts != NULL) {
500 uts = *ts;
501 if (uts.tv_sec > INT32_MAX / 2) {
502 over = uts.tv_sec - INT32_MAX / 2;
503 uts.tv_sec -= over;
504 }
505 tmp = tstosbt(uts);
506 if (TIMESEL(&sbt, tmp))
507 sbt += tc_tick_sbt;
508 sbt += tmp;
509 prec = tmp;
510 prec >>= tc_precexp;
511 } else {
512 sbt = 0;
513 prec = 0;
514 }
515 LIN_SDT_PROBE3(futex, futex_sleep, entry, f, wp, sbt);
516 LINUX_CTR4(sys_futex, "futex_sleep enter uaddr %p wp %p timo %ld ref %d",
517 f->f_uaddr, wp, sbt, f->f_refcount);
518
519 error = msleep_sbt(wp, &f->f_lck, PCATCH, "futex", sbt, prec, C_ABSOLUTE);
520 if (wp->wp_flags & FUTEX_WP_REQUEUED) {
521 KASSERT(f != wp->wp_futex, ("futex != wp_futex"));
522
523 if (error) {
524 LIN_SDT_PROBE5(futex, futex_sleep, requeue_error, error,
525 f->f_uaddr, wp, wp->wp_futex->f_uaddr,
526 wp->wp_futex->f_refcount);
527 }
528
529 LINUX_CTR5(sys_futex, "futex_sleep out error %d uaddr %p wp"
530 " %p requeued uaddr %p ref %d",
531 error, f->f_uaddr, wp, wp->wp_futex->f_uaddr,
532 wp->wp_futex->f_refcount);
533 futex_put(f, NULL);
534 f = wp->wp_futex;
535 futex_lock(f);
536 } else {
537 if (error) {
538 LIN_SDT_PROBE3(futex, futex_sleep, sleep_error, error,
539 f->f_uaddr, wp);
540 }
541 LINUX_CTR3(sys_futex, "futex_sleep out error %d uaddr %p wp %p",
542 error, f->f_uaddr, wp);
543 }
544
545 futex_put(f, wp);
546
547 LIN_SDT_PROBE1(futex, futex_sleep, return, error);
548 return (error);
549 }
550
551 static int
futex_wake(struct futex * f,int n,uint32_t bitset)552 futex_wake(struct futex *f, int n, uint32_t bitset)
553 {
554 struct waiting_proc *wp, *wpt;
555 int count = 0;
556
557 LIN_SDT_PROBE3(futex, futex_wake, entry, f, n, bitset);
558
559 if (bitset == 0) {
560 LIN_SDT_PROBE1(futex, futex_wake, return, EINVAL);
561 return (EINVAL);
562 }
563
564 FUTEX_ASSERT_LOCKED(f);
565 TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) {
566 LIN_SDT_PROBE3(futex, futex_wake, iterate, f->f_uaddr, wp,
567 f->f_refcount);
568 LINUX_CTR3(sys_futex, "futex_wake uaddr %p wp %p ref %d",
569 f->f_uaddr, wp, f->f_refcount);
570 /*
571 * Unless we find a matching bit in
572 * the bitset, continue searching.
573 */
574 if (!(wp->wp_futex->f_bitset & bitset))
575 continue;
576
577 wp->wp_flags |= FUTEX_WP_REMOVED;
578 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
579 LIN_SDT_PROBE1(futex, futex_wake, wakeup, wp);
580 wakeup_one(wp);
581 if (++count == n)
582 break;
583 }
584
585 LIN_SDT_PROBE1(futex, futex_wake, return, count);
586 return (count);
587 }
588
589 static int
futex_requeue(struct futex * f,int nrwake,struct futex * f2,int nrrequeue)590 futex_requeue(struct futex *f, int nrwake, struct futex *f2,
591 int nrrequeue)
592 {
593 struct waiting_proc *wp, *wpt;
594 int count = 0;
595
596 LIN_SDT_PROBE4(futex, futex_requeue, entry, f, nrwake, f2, nrrequeue);
597
598 FUTEX_ASSERT_LOCKED(f);
599 FUTEX_ASSERT_LOCKED(f2);
600
601 TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) {
602 if (++count <= nrwake) {
603 LINUX_CTR2(sys_futex, "futex_req_wake uaddr %p wp %p",
604 f->f_uaddr, wp);
605 wp->wp_flags |= FUTEX_WP_REMOVED;
606 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
607 LIN_SDT_PROBE1(futex, futex_requeue, wakeup, wp);
608 wakeup_one(wp);
609 } else {
610 LIN_SDT_PROBE3(futex, futex_requeue, requeue,
611 f->f_uaddr, wp, f2->f_uaddr);
612 LINUX_CTR3(sys_futex, "futex_requeue uaddr %p wp %p to %p",
613 f->f_uaddr, wp, f2->f_uaddr);
614 wp->wp_flags |= FUTEX_WP_REQUEUED;
615 /* Move wp to wp_list of f2 futex */
616 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
617 TAILQ_INSERT_HEAD(&f2->f_waiting_proc, wp, wp_list);
618
619 /*
620 * Thread which sleeps on wp after waking should
621 * acquire f2 lock, so increment refcount of f2 to
622 * prevent it from premature deallocation.
623 */
624 wp->wp_futex = f2;
625 FUTEXES_LOCK;
626 ++f2->f_refcount;
627 FUTEXES_UNLOCK;
628 if (count - nrwake >= nrrequeue)
629 break;
630 }
631 }
632
633 LIN_SDT_PROBE1(futex, futex_requeue, return, count);
634 return (count);
635 }
636
637 static int
futex_wait(struct futex * f,struct waiting_proc * wp,struct timespec * ts,uint32_t bitset)638 futex_wait(struct futex *f, struct waiting_proc *wp, struct timespec *ts,
639 uint32_t bitset)
640 {
641 int error;
642
643 LIN_SDT_PROBE4(futex, futex_wait, entry, f, wp, ts, bitset);
644
645 if (bitset == 0) {
646 LIN_SDT_PROBE1(futex, futex_wait, return, EINVAL);
647 futex_put(f, wp);
648 return (EINVAL);
649 }
650
651 f->f_bitset = bitset;
652 error = futex_sleep(f, wp, ts);
653 if (error)
654 LIN_SDT_PROBE1(futex, futex_wait, sleep_error, error);
655 if (error == EWOULDBLOCK)
656 error = ETIMEDOUT;
657
658 LIN_SDT_PROBE1(futex, futex_wait, return, error);
659 return (error);
660 }
661
662 static int
futex_atomic_op(struct thread * td,int encoded_op,uint32_t * uaddr)663 futex_atomic_op(struct thread *td, int encoded_op, uint32_t *uaddr)
664 {
665 int op = (encoded_op >> 28) & 7;
666 int cmp = (encoded_op >> 24) & 15;
667 int oparg = (encoded_op << 8) >> 20;
668 int cmparg = (encoded_op << 20) >> 20;
669 int oldval = 0, ret;
670
671 LIN_SDT_PROBE3(futex, futex_atomic_op, entry, td, encoded_op, uaddr);
672
673 if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
674 oparg = 1 << oparg;
675
676 LIN_SDT_PROBE4(futex, futex_atomic_op, decoded_op, op, cmp, oparg,
677 cmparg);
678
679 /* XXX: Linux verifies access here and returns EFAULT */
680 LIN_SDT_PROBE0(futex, futex_atomic_op, missing_access_check);
681
682 switch (op) {
683 case FUTEX_OP_SET:
684 ret = futex_xchgl(oparg, uaddr, &oldval);
685 break;
686 case FUTEX_OP_ADD:
687 ret = futex_addl(oparg, uaddr, &oldval);
688 break;
689 case FUTEX_OP_OR:
690 ret = futex_orl(oparg, uaddr, &oldval);
691 break;
692 case FUTEX_OP_ANDN:
693 ret = futex_andl(~oparg, uaddr, &oldval);
694 break;
695 case FUTEX_OP_XOR:
696 ret = futex_xorl(oparg, uaddr, &oldval);
697 break;
698 default:
699 LIN_SDT_PROBE1(futex, futex_atomic_op, unimplemented_op, op);
700 ret = -ENOSYS;
701 break;
702 }
703
704 if (ret) {
705 LIN_SDT_PROBE1(futex, futex_atomic_op, return, ret);
706 return (ret);
707 }
708
709 switch (cmp) {
710 case FUTEX_OP_CMP_EQ:
711 ret = (oldval == cmparg);
712 break;
713 case FUTEX_OP_CMP_NE:
714 ret = (oldval != cmparg);
715 break;
716 case FUTEX_OP_CMP_LT:
717 ret = (oldval < cmparg);
718 break;
719 case FUTEX_OP_CMP_GE:
720 ret = (oldval >= cmparg);
721 break;
722 case FUTEX_OP_CMP_LE:
723 ret = (oldval <= cmparg);
724 break;
725 case FUTEX_OP_CMP_GT:
726 ret = (oldval > cmparg);
727 break;
728 default:
729 LIN_SDT_PROBE1(futex, futex_atomic_op, unimplemented_cmp, cmp);
730 ret = -ENOSYS;
731 }
732
733 LIN_SDT_PROBE1(futex, futex_atomic_op, return, ret);
734 return (ret);
735 }
736
737 int
linux_sys_futex(struct thread * td,struct linux_sys_futex_args * args)738 linux_sys_futex(struct thread *td, struct linux_sys_futex_args *args)
739 {
740 int clockrt, nrwake, nrrequeue, op_ret, ret;
741 struct linux_pemuldata *pem;
742 struct waiting_proc *wp;
743 struct futex *f, *f2;
744 struct timespec uts, *ts;
745 int error, save;
746 uint32_t flags, val;
747
748 LIN_SDT_PROBE2(futex, linux_sys_futex, entry, td, args);
749
750 if (args->op & LINUX_FUTEX_PRIVATE_FLAG) {
751 flags = 0;
752 args->op &= ~LINUX_FUTEX_PRIVATE_FLAG;
753 } else
754 flags = FUTEX_SHARED;
755
756 /*
757 * Currently support for switching between CLOCK_MONOTONIC and
758 * CLOCK_REALTIME is not present. However Linux forbids the use of
759 * FUTEX_CLOCK_REALTIME with any op except FUTEX_WAIT_BITSET and
760 * FUTEX_WAIT_REQUEUE_PI.
761 */
762 clockrt = args->op & LINUX_FUTEX_CLOCK_REALTIME;
763 args->op = args->op & ~LINUX_FUTEX_CLOCK_REALTIME;
764 if (clockrt && args->op != LINUX_FUTEX_WAIT_BITSET &&
765 args->op != LINUX_FUTEX_WAIT_REQUEUE_PI) {
766 LIN_SDT_PROBE0(futex, linux_sys_futex,
767 unimplemented_clockswitch);
768 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
769 return (ENOSYS);
770 }
771
772 error = 0;
773 f = f2 = NULL;
774
775 switch (args->op) {
776 case LINUX_FUTEX_WAIT:
777 args->val3 = FUTEX_BITSET_MATCH_ANY;
778 /* FALLTHROUGH */
779
780 case LINUX_FUTEX_WAIT_BITSET:
781 LIN_SDT_PROBE3(futex, linux_sys_futex, debug_wait, args->uaddr,
782 args->val, args->val3);
783 LINUX_CTR3(sys_futex, "WAIT uaddr %p val 0x%x bitset 0x%x",
784 args->uaddr, args->val, args->val3);
785
786 if (args->timeout != NULL) {
787 error = futex_copyin_timeout(args->op, args->timeout,
788 clockrt, &uts);
789 if (error) {
790 LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error,
791 error);
792 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
793 return (error);
794 }
795 ts = &uts;
796 } else
797 ts = NULL;
798
799 retry0:
800 error = futex_get(args->uaddr, &wp, &f,
801 flags | FUTEX_CREATE_WP);
802 if (error) {
803 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
804 return (error);
805 }
806
807 error = copyin_nofault(args->uaddr, &val, sizeof(val));
808 if (error) {
809 futex_put(f, wp);
810 error = copyin(args->uaddr, &val, sizeof(val));
811 if (error == 0)
812 goto retry0;
813 LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error,
814 error);
815 LINUX_CTR1(sys_futex, "WAIT copyin failed %d",
816 error);
817 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
818 return (error);
819 }
820 if (val != args->val) {
821 LIN_SDT_PROBE4(futex, linux_sys_futex,
822 debug_wait_value_neq, args->uaddr, args->val, val,
823 args->val3);
824 LINUX_CTR3(sys_futex,
825 "WAIT uaddr %p val 0x%x != uval 0x%x",
826 args->uaddr, args->val, val);
827 futex_put(f, wp);
828
829 LIN_SDT_PROBE1(futex, linux_sys_futex, return,
830 EWOULDBLOCK);
831 return (EWOULDBLOCK);
832 }
833
834 error = futex_wait(f, wp, ts, args->val3);
835 break;
836
837 case LINUX_FUTEX_WAKE:
838 args->val3 = FUTEX_BITSET_MATCH_ANY;
839 /* FALLTHROUGH */
840
841 case LINUX_FUTEX_WAKE_BITSET:
842 LIN_SDT_PROBE3(futex, linux_sys_futex, debug_wake, args->uaddr,
843 args->val, args->val3);
844 LINUX_CTR3(sys_futex, "WAKE uaddr %p nrwake 0x%x bitset 0x%x",
845 args->uaddr, args->val, args->val3);
846
847 error = futex_get(args->uaddr, NULL, &f,
848 flags | FUTEX_DONTCREATE);
849 if (error) {
850 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
851 return (error);
852 }
853
854 if (f == NULL) {
855 td->td_retval[0] = 0;
856
857 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
858 return (error);
859 }
860 td->td_retval[0] = futex_wake(f, args->val, args->val3);
861 futex_put(f, NULL);
862 break;
863
864 case LINUX_FUTEX_CMP_REQUEUE:
865 LIN_SDT_PROBE5(futex, linux_sys_futex, debug_cmp_requeue,
866 args->uaddr, args->val, args->val3, args->uaddr2,
867 args->timeout);
868 LINUX_CTR5(sys_futex, "CMP_REQUEUE uaddr %p "
869 "nrwake 0x%x uval 0x%x uaddr2 %p nrequeue 0x%x",
870 args->uaddr, args->val, args->val3, args->uaddr2,
871 args->timeout);
872
873 /*
874 * Linux allows this, we would not, it is an incorrect
875 * usage of declared ABI, so return EINVAL.
876 */
877 if (args->uaddr == args->uaddr2) {
878 LIN_SDT_PROBE0(futex, linux_sys_futex,
879 invalid_cmp_requeue_use);
880 LIN_SDT_PROBE1(futex, linux_sys_futex, return, EINVAL);
881 return (EINVAL);
882 }
883
884 nrrequeue = (int)(unsigned long)args->timeout;
885 nrwake = args->val;
886 /*
887 * Sanity check to prevent signed integer overflow,
888 * see Linux CVE-2018-6927
889 */
890 if (nrwake < 0 || nrrequeue < 0)
891 return (EINVAL);
892
893 retry1:
894 error = futex_get(args->uaddr, NULL, &f, flags | FUTEX_DONTLOCK);
895 if (error) {
896 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
897 return (error);
898 }
899
900 /*
901 * To avoid deadlocks return EINVAL if second futex
902 * exists at this time.
903 *
904 * Glibc fall back to FUTEX_WAKE in case of any error
905 * returned by FUTEX_CMP_REQUEUE.
906 */
907 error = futex_get(args->uaddr2, NULL, &f2,
908 flags | FUTEX_DONTEXISTS | FUTEX_DONTLOCK);
909 if (error) {
910 futex_put(f, NULL);
911
912 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
913 return (error);
914 }
915 futex_lock(f);
916 futex_lock(f2);
917 error = copyin_nofault(args->uaddr, &val, sizeof(val));
918 if (error) {
919 futex_put(f2, NULL);
920 futex_put(f, NULL);
921 error = copyin(args->uaddr, &val, sizeof(val));
922 if (error == 0)
923 goto retry1;
924 LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error,
925 error);
926 LINUX_CTR1(sys_futex, "CMP_REQUEUE copyin failed %d",
927 error);
928 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
929 return (error);
930 }
931 if (val != args->val3) {
932 LIN_SDT_PROBE2(futex, linux_sys_futex,
933 debug_cmp_requeue_value_neq, args->val, val);
934 LINUX_CTR2(sys_futex, "CMP_REQUEUE val 0x%x != uval 0x%x",
935 args->val, val);
936 futex_put(f2, NULL);
937 futex_put(f, NULL);
938
939 LIN_SDT_PROBE1(futex, linux_sys_futex, return, EAGAIN);
940 return (EAGAIN);
941 }
942
943 td->td_retval[0] = futex_requeue(f, nrwake, f2, nrrequeue);
944 futex_put(f2, NULL);
945 futex_put(f, NULL);
946 break;
947
948 case LINUX_FUTEX_WAKE_OP:
949 LIN_SDT_PROBE5(futex, linux_sys_futex, debug_wake_op,
950 args->uaddr, args->op, args->val, args->uaddr2, args->val3);
951 LINUX_CTR5(sys_futex, "WAKE_OP "
952 "uaddr %p nrwake 0x%x uaddr2 %p op 0x%x nrwake2 0x%x",
953 args->uaddr, args->val, args->uaddr2, args->val3,
954 args->timeout);
955
956 if (args->uaddr == args->uaddr2) {
957 LIN_SDT_PROBE1(futex, linux_sys_futex, return, EINVAL);
958 return (EINVAL);
959 }
960
961 retry2:
962 error = futex_get(args->uaddr, NULL, &f, flags | FUTEX_DONTLOCK);
963 if (error) {
964 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
965 return (error);
966 }
967
968 error = futex_get(args->uaddr2, NULL, &f2, flags | FUTEX_DONTLOCK);
969 if (error) {
970 futex_put(f, NULL);
971
972 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
973 return (error);
974 }
975 futex_lock(f);
976 futex_lock(f2);
977
978 /*
979 * This function returns positive number as results and
980 * negative as errors
981 */
982 save = vm_fault_disable_pagefaults();
983 op_ret = futex_atomic_op(td, args->val3, args->uaddr2);
984 vm_fault_enable_pagefaults(save);
985
986 LINUX_CTR2(sys_futex, "WAKE_OP atomic_op uaddr %p ret 0x%x",
987 args->uaddr, op_ret);
988
989 if (op_ret < 0) {
990 if (f2 != NULL)
991 futex_put(f2, NULL);
992 futex_put(f, NULL);
993 error = copyin(args->uaddr2, &val, sizeof(val));
994 if (error == 0)
995 goto retry2;
996 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
997 return (error);
998 }
999
1000 ret = futex_wake(f, args->val, args->val3);
1001
1002 if (op_ret > 0) {
1003 op_ret = 0;
1004 nrwake = (int)(unsigned long)args->timeout;
1005
1006 if (f2 != NULL)
1007 op_ret += futex_wake(f2, nrwake, args->val3);
1008 else
1009 op_ret += futex_wake(f, nrwake, args->val3);
1010 ret += op_ret;
1011
1012 }
1013 if (f2 != NULL)
1014 futex_put(f2, NULL);
1015 futex_put(f, NULL);
1016 td->td_retval[0] = ret;
1017 break;
1018
1019 case LINUX_FUTEX_LOCK_PI:
1020 /* not yet implemented */
1021 pem = pem_find(td->td_proc);
1022 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
1023 linux_msg(td, "unsupported FUTEX_LOCK_PI");
1024 pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
1025 LIN_SDT_PROBE0(futex, linux_sys_futex,
1026 unimplemented_lock_pi);
1027 }
1028 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1029 return (ENOSYS);
1030
1031 case LINUX_FUTEX_UNLOCK_PI:
1032 /* not yet implemented */
1033 pem = pem_find(td->td_proc);
1034 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
1035 linux_msg(td, "unsupported FUTEX_UNLOCK_PI");
1036 pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
1037 LIN_SDT_PROBE0(futex, linux_sys_futex,
1038 unimplemented_unlock_pi);
1039 }
1040 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1041 return (ENOSYS);
1042
1043 case LINUX_FUTEX_TRYLOCK_PI:
1044 /* not yet implemented */
1045 pem = pem_find(td->td_proc);
1046 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
1047 linux_msg(td, "unsupported FUTEX_TRYLOCK_PI");
1048 pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
1049 LIN_SDT_PROBE0(futex, linux_sys_futex,
1050 unimplemented_trylock_pi);
1051 }
1052 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1053 return (ENOSYS);
1054
1055 case LINUX_FUTEX_REQUEUE:
1056 /*
1057 * Glibc does not use this operation since version 2.3.3,
1058 * as it is racy and replaced by FUTEX_CMP_REQUEUE operation.
1059 * Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when
1060 * FUTEX_REQUEUE returned EINVAL.
1061 */
1062 pem = pem_find(td->td_proc);
1063 if ((pem->flags & LINUX_XDEPR_REQUEUEOP) == 0) {
1064 linux_msg(td, "unsupported FUTEX_REQUEUE");
1065 pem->flags |= LINUX_XDEPR_REQUEUEOP;
1066 LIN_SDT_PROBE0(futex, linux_sys_futex,
1067 deprecated_requeue);
1068 }
1069
1070 LIN_SDT_PROBE1(futex, linux_sys_futex, return, EINVAL);
1071 return (EINVAL);
1072
1073 case LINUX_FUTEX_WAIT_REQUEUE_PI:
1074 /* not yet implemented */
1075 pem = pem_find(td->td_proc);
1076 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
1077 linux_msg(td, "unsupported FUTEX_WAIT_REQUEUE_PI");
1078 pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
1079 LIN_SDT_PROBE0(futex, linux_sys_futex,
1080 unimplemented_wait_requeue_pi);
1081 }
1082 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1083 return (ENOSYS);
1084
1085 case LINUX_FUTEX_CMP_REQUEUE_PI:
1086 /* not yet implemented */
1087 pem = pem_find(td->td_proc);
1088 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
1089 linux_msg(td, "unsupported FUTEX_CMP_REQUEUE_PI");
1090 pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
1091 LIN_SDT_PROBE0(futex, linux_sys_futex,
1092 unimplemented_cmp_requeue_pi);
1093 }
1094 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1095 return (ENOSYS);
1096
1097 default:
1098 linux_msg(td, "unsupported futex op %d", args->op);
1099 LIN_SDT_PROBE1(futex, linux_sys_futex, unknown_operation,
1100 args->op);
1101 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1102 return (ENOSYS);
1103 }
1104
1105 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
1106 return (error);
1107 }
1108
1109 int
linux_set_robust_list(struct thread * td,struct linux_set_robust_list_args * args)1110 linux_set_robust_list(struct thread *td, struct linux_set_robust_list_args *args)
1111 {
1112 struct linux_emuldata *em;
1113
1114 LIN_SDT_PROBE2(futex, linux_set_robust_list, entry, td, args);
1115
1116 if (args->len != sizeof(struct linux_robust_list_head)) {
1117 LIN_SDT_PROBE0(futex, linux_set_robust_list, size_error);
1118 LIN_SDT_PROBE1(futex, linux_set_robust_list, return, EINVAL);
1119 return (EINVAL);
1120 }
1121
1122 em = em_find(td);
1123 em->robust_futexes = args->head;
1124
1125 LIN_SDT_PROBE1(futex, linux_set_robust_list, return, 0);
1126 return (0);
1127 }
1128
1129 int
linux_get_robust_list(struct thread * td,struct linux_get_robust_list_args * args)1130 linux_get_robust_list(struct thread *td, struct linux_get_robust_list_args *args)
1131 {
1132 struct linux_emuldata *em;
1133 struct linux_robust_list_head *head;
1134 l_size_t len = sizeof(struct linux_robust_list_head);
1135 struct thread *td2;
1136 int error = 0;
1137
1138 LIN_SDT_PROBE2(futex, linux_get_robust_list, entry, td, args);
1139
1140 if (!args->pid) {
1141 em = em_find(td);
1142 KASSERT(em != NULL, ("get_robust_list: emuldata notfound.\n"));
1143 head = em->robust_futexes;
1144 } else {
1145 td2 = tdfind(args->pid, -1);
1146 if (td2 == NULL) {
1147 LIN_SDT_PROBE1(futex, linux_get_robust_list, return,
1148 ESRCH);
1149 return (ESRCH);
1150 }
1151 if (SV_PROC_ABI(td2->td_proc) != SV_ABI_LINUX) {
1152 LIN_SDT_PROBE1(futex, linux_get_robust_list, return,
1153 EPERM);
1154 PROC_UNLOCK(td2->td_proc);
1155 return (EPERM);
1156 }
1157
1158 em = em_find(td2);
1159 KASSERT(em != NULL, ("get_robust_list: emuldata notfound.\n"));
1160 /* XXX: ptrace? */
1161 if (priv_check(td, PRIV_CRED_SETUID) ||
1162 priv_check(td, PRIV_CRED_SETEUID) ||
1163 p_candebug(td, td2->td_proc)) {
1164 PROC_UNLOCK(td2->td_proc);
1165
1166 LIN_SDT_PROBE1(futex, linux_get_robust_list, return,
1167 EPERM);
1168 return (EPERM);
1169 }
1170 head = em->robust_futexes;
1171
1172 PROC_UNLOCK(td2->td_proc);
1173 }
1174
1175 error = copyout(&len, args->len, sizeof(l_size_t));
1176 if (error) {
1177 LIN_SDT_PROBE1(futex, linux_get_robust_list, copyout_error,
1178 error);
1179 LIN_SDT_PROBE1(futex, linux_get_robust_list, return, EFAULT);
1180 return (EFAULT);
1181 }
1182
1183 error = copyout(&head, args->head, sizeof(head));
1184 if (error) {
1185 LIN_SDT_PROBE1(futex, linux_get_robust_list, copyout_error,
1186 error);
1187 }
1188
1189 LIN_SDT_PROBE1(futex, linux_get_robust_list, return, error);
1190 return (error);
1191 }
1192
1193 static int
handle_futex_death(struct linux_emuldata * em,uint32_t * uaddr,unsigned int pi)1194 handle_futex_death(struct linux_emuldata *em, uint32_t *uaddr,
1195 unsigned int pi)
1196 {
1197 uint32_t uval, nval, mval;
1198 struct futex *f;
1199 int error;
1200
1201 LIN_SDT_PROBE3(futex, handle_futex_death, entry, em, uaddr, pi);
1202
1203 retry:
1204 error = copyin(uaddr, &uval, 4);
1205 if (error) {
1206 LIN_SDT_PROBE1(futex, handle_futex_death, copyin_error, error);
1207 LIN_SDT_PROBE1(futex, handle_futex_death, return, EFAULT);
1208 return (EFAULT);
1209 }
1210 if ((uval & FUTEX_TID_MASK) == em->em_tid) {
1211 mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED;
1212 nval = casuword32(uaddr, uval, mval);
1213
1214 if (nval == -1) {
1215 LIN_SDT_PROBE1(futex, handle_futex_death, return,
1216 EFAULT);
1217 return (EFAULT);
1218 }
1219
1220 if (nval != uval)
1221 goto retry;
1222
1223 if (!pi && (uval & FUTEX_WAITERS)) {
1224 error = futex_get(uaddr, NULL, &f,
1225 FUTEX_DONTCREATE | FUTEX_SHARED);
1226 if (error) {
1227 LIN_SDT_PROBE1(futex, handle_futex_death,
1228 return, error);
1229 return (error);
1230 }
1231 if (f != NULL) {
1232 futex_wake(f, 1, FUTEX_BITSET_MATCH_ANY);
1233 futex_put(f, NULL);
1234 }
1235 }
1236 }
1237
1238 LIN_SDT_PROBE1(futex, handle_futex_death, return, 0);
1239 return (0);
1240 }
1241
1242 static int
fetch_robust_entry(struct linux_robust_list ** entry,struct linux_robust_list ** head,unsigned int * pi)1243 fetch_robust_entry(struct linux_robust_list **entry,
1244 struct linux_robust_list **head, unsigned int *pi)
1245 {
1246 l_ulong uentry;
1247 int error;
1248
1249 LIN_SDT_PROBE3(futex, fetch_robust_entry, entry, entry, head, pi);
1250
1251 error = copyin((const void *)head, &uentry, sizeof(l_ulong));
1252 if (error) {
1253 LIN_SDT_PROBE1(futex, fetch_robust_entry, copyin_error, error);
1254 LIN_SDT_PROBE1(futex, fetch_robust_entry, return, EFAULT);
1255 return (EFAULT);
1256 }
1257
1258 *entry = (void *)(uentry & ~1UL);
1259 *pi = uentry & 1;
1260
1261 LIN_SDT_PROBE1(futex, fetch_robust_entry, return, 0);
1262 return (0);
1263 }
1264
1265 /* This walks the list of robust futexes releasing them. */
1266 void
release_futexes(struct thread * td,struct linux_emuldata * em)1267 release_futexes(struct thread *td, struct linux_emuldata *em)
1268 {
1269 struct linux_robust_list_head *head = NULL;
1270 struct linux_robust_list *entry, *next_entry, *pending;
1271 unsigned int limit = 2048, pi, next_pi, pip;
1272 l_long futex_offset;
1273 int rc, error;
1274
1275 LIN_SDT_PROBE2(futex, release_futexes, entry, td, em);
1276
1277 head = em->robust_futexes;
1278
1279 if (head == NULL) {
1280 LIN_SDT_PROBE0(futex, release_futexes, return);
1281 return;
1282 }
1283
1284 if (fetch_robust_entry(&entry, PTRIN(&head->list.next), &pi)) {
1285 LIN_SDT_PROBE0(futex, release_futexes, return);
1286 return;
1287 }
1288
1289 error = copyin(&head->futex_offset, &futex_offset,
1290 sizeof(futex_offset));
1291 if (error) {
1292 LIN_SDT_PROBE1(futex, release_futexes, copyin_error, error);
1293 LIN_SDT_PROBE0(futex, release_futexes, return);
1294 return;
1295 }
1296
1297 if (fetch_robust_entry(&pending, PTRIN(&head->pending_list), &pip)) {
1298 LIN_SDT_PROBE0(futex, release_futexes, return);
1299 return;
1300 }
1301
1302 while (entry != &head->list) {
1303 rc = fetch_robust_entry(&next_entry, PTRIN(&entry->next), &next_pi);
1304
1305 if (entry != pending)
1306 if (handle_futex_death(em,
1307 (uint32_t *)((caddr_t)entry + futex_offset), pi)) {
1308 LIN_SDT_PROBE0(futex, release_futexes, return);
1309 return;
1310 }
1311 if (rc) {
1312 LIN_SDT_PROBE0(futex, release_futexes, return);
1313 return;
1314 }
1315
1316 entry = next_entry;
1317 pi = next_pi;
1318
1319 if (!--limit)
1320 break;
1321
1322 sched_relinquish(curthread);
1323 }
1324
1325 if (pending)
1326 handle_futex_death(em, (uint32_t *)((caddr_t)pending + futex_offset), pip);
1327
1328 LIN_SDT_PROBE0(futex, release_futexes, return);
1329 }
1330