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/sdt.h>
55 #include <sys/sx.h>
56 #include <sys/umtx.h>
57
58 #ifdef COMPAT_LINUX32
59 #include <machine/../linux32/linux.h>
60 #include <machine/../linux32/linux32_proto.h>
61 #else
62 #include <machine/../linux/linux.h>
63 #include <machine/../linux/linux_proto.h>
64 #endif
65 #include <compat/linux/linux_dtrace.h>
66 #include <compat/linux/linux_emul.h>
67 #include <compat/linux/linux_futex.h>
68 #include <compat/linux/linux_timer.h>
69 #include <compat/linux/linux_util.h>
70
71 /* DTrace init */
72 LIN_SDT_PROVIDER_DECLARE(LINUX_DTRACE);
73
74 /**
75 * Futex part for the special DTrace module "locks".
76 */
77 LIN_SDT_PROBE_DEFINE1(locks, futex_mtx, locked, "struct mtx *");
78 LIN_SDT_PROBE_DEFINE1(locks, futex_mtx, unlock, "struct mtx *");
79
80 /**
81 * Per futex probes.
82 */
83 LIN_SDT_PROBE_DEFINE1(futex, futex, create, "struct sx *");
84 LIN_SDT_PROBE_DEFINE1(futex, futex, destroy, "struct sx *");
85
86 /**
87 * DTrace probes in this module.
88 */
89 LIN_SDT_PROBE_DEFINE2(futex, futex_put, entry, "struct futex *",
90 "struct waiting_proc *");
91 LIN_SDT_PROBE_DEFINE3(futex, futex_put, destroy, "uint32_t *", "uint32_t",
92 "int");
93 LIN_SDT_PROBE_DEFINE3(futex, futex_put, unlock, "uint32_t *", "uint32_t",
94 "int");
95 LIN_SDT_PROBE_DEFINE0(futex, futex_put, return);
96 LIN_SDT_PROBE_DEFINE3(futex, futex_get0, entry, "uint32_t *", "struct futex **",
97 "uint32_t");
98 LIN_SDT_PROBE_DEFINE1(futex, futex_get0, umtx_key_get_error, "int");
99 LIN_SDT_PROBE_DEFINE3(futex, futex_get0, shared, "uint32_t *", "uint32_t",
100 "int");
101 LIN_SDT_PROBE_DEFINE1(futex, futex_get0, null, "uint32_t *");
102 LIN_SDT_PROBE_DEFINE3(futex, futex_get0, new, "uint32_t *", "uint32_t", "int");
103 LIN_SDT_PROBE_DEFINE1(futex, futex_get0, return, "int");
104 LIN_SDT_PROBE_DEFINE3(futex, futex_get, entry, "uint32_t *",
105 "struct waiting_proc **", "struct futex **");
106 LIN_SDT_PROBE_DEFINE0(futex, futex_get, error);
107 LIN_SDT_PROBE_DEFINE1(futex, futex_get, return, "int");
108 LIN_SDT_PROBE_DEFINE3(futex, futex_sleep, entry, "struct futex *",
109 "struct waiting_proc **", "int");
110 LIN_SDT_PROBE_DEFINE5(futex, futex_sleep, requeue_error, "int", "uint32_t *",
111 "struct waiting_proc *", "uint32_t *", "uint32_t");
112 LIN_SDT_PROBE_DEFINE3(futex, futex_sleep, sleep_error, "int", "uint32_t *",
113 "struct waiting_proc *");
114 LIN_SDT_PROBE_DEFINE1(futex, futex_sleep, return, "int");
115 LIN_SDT_PROBE_DEFINE3(futex, futex_wake, entry, "struct futex *", "int",
116 "uint32_t");
117 LIN_SDT_PROBE_DEFINE3(futex, futex_wake, iterate, "uint32_t",
118 "struct waiting_proc *", "uint32_t");
119 LIN_SDT_PROBE_DEFINE1(futex, futex_wake, wakeup, "struct waiting_proc *");
120 LIN_SDT_PROBE_DEFINE1(futex, futex_wake, return, "int");
121 LIN_SDT_PROBE_DEFINE4(futex, futex_requeue, entry, "struct futex *", "int",
122 "struct futex *", "int");
123 LIN_SDT_PROBE_DEFINE1(futex, futex_requeue, wakeup, "struct waiting_proc *");
124 LIN_SDT_PROBE_DEFINE3(futex, futex_requeue, requeue, "uint32_t *",
125 "struct waiting_proc *", "uint32_t");
126 LIN_SDT_PROBE_DEFINE1(futex, futex_requeue, return, "int");
127 LIN_SDT_PROBE_DEFINE4(futex, futex_wait, entry, "struct futex *",
128 "struct waiting_proc **", "int", "uint32_t");
129 LIN_SDT_PROBE_DEFINE1(futex, futex_wait, sleep_error, "int");
130 LIN_SDT_PROBE_DEFINE1(futex, futex_wait, return, "int");
131 LIN_SDT_PROBE_DEFINE3(futex, futex_atomic_op, entry, "struct thread *",
132 "int", "uint32_t");
133 LIN_SDT_PROBE_DEFINE4(futex, futex_atomic_op, decoded_op, "int", "int", "int",
134 "int");
135 LIN_SDT_PROBE_DEFINE0(futex, futex_atomic_op, missing_access_check);
136 LIN_SDT_PROBE_DEFINE1(futex, futex_atomic_op, unimplemented_op, "int");
137 LIN_SDT_PROBE_DEFINE1(futex, futex_atomic_op, unimplemented_cmp, "int");
138 LIN_SDT_PROBE_DEFINE1(futex, futex_atomic_op, return, "int");
139 LIN_SDT_PROBE_DEFINE2(futex, linux_sys_futex, entry, "struct thread *",
140 "struct linux_sys_futex_args *");
141 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_clockswitch);
142 LIN_SDT_PROBE_DEFINE1(futex, linux_sys_futex, itimerfix_error, "int");
143 LIN_SDT_PROBE_DEFINE1(futex, linux_sys_futex, copyin_error, "int");
144 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, invalid_cmp_requeue_use);
145 LIN_SDT_PROBE_DEFINE3(futex, linux_sys_futex, debug_wait, "uint32_t *",
146 "uint32_t", "uint32_t");
147 LIN_SDT_PROBE_DEFINE4(futex, linux_sys_futex, debug_wait_value_neq,
148 "uint32_t *", "uint32_t", "int", "uint32_t");
149 LIN_SDT_PROBE_DEFINE3(futex, linux_sys_futex, debug_wake, "uint32_t *",
150 "uint32_t", "uint32_t");
151 LIN_SDT_PROBE_DEFINE5(futex, linux_sys_futex, debug_cmp_requeue, "uint32_t *",
152 "uint32_t", "uint32_t", "uint32_t *", "struct l_timespec *");
153 LIN_SDT_PROBE_DEFINE2(futex, linux_sys_futex, debug_cmp_requeue_value_neq,
154 "uint32_t", "int");
155 LIN_SDT_PROBE_DEFINE5(futex, linux_sys_futex, debug_wake_op, "uint32_t *",
156 "int", "uint32_t", "uint32_t *", "uint32_t");
157 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unhandled_efault);
158 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_lock_pi);
159 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_unlock_pi);
160 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_trylock_pi);
161 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, deprecated_requeue);
162 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_wait_requeue_pi);
163 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_cmp_requeue_pi);
164 LIN_SDT_PROBE_DEFINE1(futex, linux_sys_futex, unknown_operation, "int");
165 LIN_SDT_PROBE_DEFINE1(futex, linux_sys_futex, return, "int");
166 LIN_SDT_PROBE_DEFINE2(futex, linux_set_robust_list, entry, "struct thread *",
167 "struct linux_set_robust_list_args *");
168 LIN_SDT_PROBE_DEFINE0(futex, linux_set_robust_list, size_error);
169 LIN_SDT_PROBE_DEFINE1(futex, linux_set_robust_list, return, "int");
170 LIN_SDT_PROBE_DEFINE2(futex, linux_get_robust_list, entry, "struct thread *",
171 "struct linux_get_robust_list_args *");
172 LIN_SDT_PROBE_DEFINE1(futex, linux_get_robust_list, copyout_error, "int");
173 LIN_SDT_PROBE_DEFINE1(futex, linux_get_robust_list, return, "int");
174 LIN_SDT_PROBE_DEFINE3(futex, handle_futex_death, entry,
175 "struct linux_emuldata *", "uint32_t *", "unsigned int");
176 LIN_SDT_PROBE_DEFINE1(futex, handle_futex_death, copyin_error, "int");
177 LIN_SDT_PROBE_DEFINE1(futex, handle_futex_death, return, "int");
178 LIN_SDT_PROBE_DEFINE3(futex, fetch_robust_entry, entry,
179 "struct linux_robust_list **", "struct linux_robust_list **",
180 "unsigned int *");
181 LIN_SDT_PROBE_DEFINE1(futex, fetch_robust_entry, copyin_error, "int");
182 LIN_SDT_PROBE_DEFINE1(futex, fetch_robust_entry, return, "int");
183 LIN_SDT_PROBE_DEFINE2(futex, release_futexes, entry, "struct thread *",
184 "struct linux_emuldata *");
185 LIN_SDT_PROBE_DEFINE1(futex, release_futexes, copyin_error, "int");
186 LIN_SDT_PROBE_DEFINE0(futex, release_futexes, return);
187
188 struct futex;
189
190 struct waiting_proc {
191 uint32_t wp_flags;
192 struct futex *wp_futex;
193 TAILQ_ENTRY(waiting_proc) wp_list;
194 };
195
196 struct futex {
197 struct sx f_lck;
198 uint32_t *f_uaddr; /* user-supplied value, for debug */
199 struct umtx_key f_key;
200 uint32_t f_refcount;
201 uint32_t f_bitset;
202 LIST_ENTRY(futex) f_list;
203 TAILQ_HEAD(lf_waiting_proc, waiting_proc) f_waiting_proc;
204 };
205
206 struct futex_list futex_list;
207
208 #define FUTEX_LOCK(f) sx_xlock(&(f)->f_lck)
209 #define FUTEX_UNLOCK(f) sx_xunlock(&(f)->f_lck)
210 #define FUTEX_INIT(f) do { \
211 sx_init_flags(&(f)->f_lck, "ftlk", \
212 SX_DUPOK); \
213 LIN_SDT_PROBE1(futex, futex, create, \
214 &(f)->f_lck); \
215 } while (0)
216 #define FUTEX_DESTROY(f) do { \
217 LIN_SDT_PROBE1(futex, futex, destroy, \
218 &(f)->f_lck); \
219 sx_destroy(&(f)->f_lck); \
220 } while (0)
221 #define FUTEX_ASSERT_LOCKED(f) sx_assert(&(f)->f_lck, SA_XLOCKED)
222
223 struct mtx futex_mtx; /* protects the futex list */
224 #define FUTEXES_LOCK do { \
225 mtx_lock(&futex_mtx); \
226 LIN_SDT_PROBE1(locks, futex_mtx, \
227 locked, &futex_mtx); \
228 } while (0)
229 #define FUTEXES_UNLOCK do { \
230 LIN_SDT_PROBE1(locks, futex_mtx, \
231 unlock, &futex_mtx); \
232 mtx_unlock(&futex_mtx); \
233 } while (0)
234
235 /* flags for futex_get() */
236 #define FUTEX_CREATE_WP 0x1 /* create waiting_proc */
237 #define FUTEX_DONTCREATE 0x2 /* don't create futex if not exists */
238 #define FUTEX_DONTEXISTS 0x4 /* return EINVAL if futex exists */
239 #define FUTEX_SHARED 0x8 /* shared futex */
240
241 /* wp_flags */
242 #define FUTEX_WP_REQUEUED 0x1 /* wp requeued - wp moved from wp_list
243 * of futex where thread sleep to wp_list
244 * of another futex.
245 */
246 #define FUTEX_WP_REMOVED 0x2 /* wp is woken up and removed from futex
247 * wp_list to prevent double wakeup.
248 */
249
250 static void futex_put(struct futex *, struct waiting_proc *);
251 static int futex_get0(uint32_t *, struct futex **f, uint32_t);
252 static int futex_get(uint32_t *, struct waiting_proc **, struct futex **,
253 uint32_t);
254 static int futex_sleep(struct futex *, struct waiting_proc *, int);
255 static int futex_wake(struct futex *, int, uint32_t);
256 static int futex_requeue(struct futex *, int, struct futex *, int);
257 static int futex_wait(struct futex *, struct waiting_proc *, int,
258 uint32_t);
259 static int futex_atomic_op(struct thread *, int, uint32_t *);
260 static int handle_futex_death(struct linux_emuldata *, uint32_t *,
261 unsigned int);
262 static int fetch_robust_entry(struct linux_robust_list **,
263 struct linux_robust_list **, unsigned int *);
264
265 /* support.s */
266 int futex_xchgl(int oparg, uint32_t *uaddr, int *oldval);
267 int futex_addl(int oparg, uint32_t *uaddr, int *oldval);
268 int futex_orl(int oparg, uint32_t *uaddr, int *oldval);
269 int futex_andl(int oparg, uint32_t *uaddr, int *oldval);
270 int futex_xorl(int oparg, uint32_t *uaddr, int *oldval);
271
272
273 static void
futex_put(struct futex * f,struct waiting_proc * wp)274 futex_put(struct futex *f, struct waiting_proc *wp)
275 {
276 LIN_SDT_PROBE2(futex, futex_put, entry, f, wp);
277
278 FUTEX_ASSERT_LOCKED(f);
279 if (wp != NULL) {
280 if ((wp->wp_flags & FUTEX_WP_REMOVED) == 0)
281 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
282 free(wp, M_FUTEX_WP);
283 }
284
285 FUTEXES_LOCK;
286 if (--f->f_refcount == 0) {
287 LIST_REMOVE(f, f_list);
288 FUTEXES_UNLOCK;
289 FUTEX_UNLOCK(f);
290
291 LIN_SDT_PROBE3(futex, futex_put, destroy, f->f_uaddr,
292 f->f_refcount, f->f_key.shared);
293 LINUX_CTR3(sys_futex, "futex_put destroy uaddr %p ref %d "
294 "shared %d", f->f_uaddr, f->f_refcount, f->f_key.shared);
295 umtx_key_release(&f->f_key);
296 FUTEX_DESTROY(f);
297 free(f, M_FUTEX);
298
299 LIN_SDT_PROBE0(futex, futex_put, return);
300 return;
301 }
302
303 LIN_SDT_PROBE3(futex, futex_put, unlock, f->f_uaddr, f->f_refcount,
304 f->f_key.shared);
305 LINUX_CTR3(sys_futex, "futex_put uaddr %p ref %d shared %d",
306 f->f_uaddr, f->f_refcount, f->f_key.shared);
307 FUTEXES_UNLOCK;
308 FUTEX_UNLOCK(f);
309
310 LIN_SDT_PROBE0(futex, futex_put, return);
311 }
312
313 static int
futex_get0(uint32_t * uaddr,struct futex ** newf,uint32_t flags)314 futex_get0(uint32_t *uaddr, struct futex **newf, uint32_t flags)
315 {
316 struct futex *f, *tmpf;
317 struct umtx_key key;
318 int error;
319
320 LIN_SDT_PROBE3(futex, futex_get0, entry, uaddr, newf, flags);
321
322 *newf = tmpf = NULL;
323
324 error = umtx_key_get(uaddr, TYPE_FUTEX, (flags & FUTEX_SHARED) ?
325 AUTO_SHARE : THREAD_SHARE, &key);
326 if (error) {
327 LIN_SDT_PROBE1(futex, futex_get0, umtx_key_get_error, error);
328 LIN_SDT_PROBE1(futex, futex_get0, return, error);
329 return (error);
330 }
331 retry:
332 FUTEXES_LOCK;
333 LIST_FOREACH(f, &futex_list, f_list) {
334 if (umtx_key_match(&f->f_key, &key)) {
335 if (tmpf != NULL) {
336 FUTEX_UNLOCK(tmpf);
337 FUTEX_DESTROY(tmpf);
338 free(tmpf, M_FUTEX);
339 }
340 if (flags & FUTEX_DONTEXISTS) {
341 FUTEXES_UNLOCK;
342 umtx_key_release(&key);
343
344 LIN_SDT_PROBE1(futex, futex_get0, return,
345 EINVAL);
346 return (EINVAL);
347 }
348
349 /*
350 * Increment refcount of the found futex to
351 * prevent it from deallocation before FUTEX_LOCK()
352 */
353 ++f->f_refcount;
354 FUTEXES_UNLOCK;
355 umtx_key_release(&key);
356
357 FUTEX_LOCK(f);
358 *newf = f;
359 LIN_SDT_PROBE3(futex, futex_get0, shared, uaddr,
360 f->f_refcount, f->f_key.shared);
361 LINUX_CTR3(sys_futex, "futex_get uaddr %p ref %d shared %d",
362 uaddr, f->f_refcount, f->f_key.shared);
363
364 LIN_SDT_PROBE1(futex, futex_get0, return, 0);
365 return (0);
366 }
367 }
368
369 if (flags & FUTEX_DONTCREATE) {
370 FUTEXES_UNLOCK;
371 umtx_key_release(&key);
372 LIN_SDT_PROBE1(futex, futex_get0, null, uaddr);
373 LINUX_CTR1(sys_futex, "futex_get uaddr %p null", uaddr);
374
375 LIN_SDT_PROBE1(futex, futex_get0, return, 0);
376 return (0);
377 }
378
379 if (tmpf == NULL) {
380 FUTEXES_UNLOCK;
381 tmpf = malloc(sizeof(*tmpf), M_FUTEX, M_WAITOK | M_ZERO);
382 tmpf->f_uaddr = uaddr;
383 tmpf->f_key = key;
384 tmpf->f_refcount = 1;
385 tmpf->f_bitset = FUTEX_BITSET_MATCH_ANY;
386 FUTEX_INIT(tmpf);
387 TAILQ_INIT(&tmpf->f_waiting_proc);
388
389 /*
390 * Lock the new futex before an insert into the futex_list
391 * to prevent futex usage by other.
392 */
393 FUTEX_LOCK(tmpf);
394 goto retry;
395 }
396
397 LIST_INSERT_HEAD(&futex_list, tmpf, f_list);
398 FUTEXES_UNLOCK;
399
400 LIN_SDT_PROBE3(futex, futex_get0, new, uaddr, tmpf->f_refcount,
401 tmpf->f_key.shared);
402 LINUX_CTR3(sys_futex, "futex_get uaddr %p ref %d shared %d new",
403 uaddr, tmpf->f_refcount, tmpf->f_key.shared);
404 *newf = tmpf;
405
406 LIN_SDT_PROBE1(futex, futex_get0, return, 0);
407 return (0);
408 }
409
410 static int
futex_get(uint32_t * uaddr,struct waiting_proc ** wp,struct futex ** f,uint32_t flags)411 futex_get(uint32_t *uaddr, struct waiting_proc **wp, struct futex **f,
412 uint32_t flags)
413 {
414 int error;
415
416 LIN_SDT_PROBE3(futex, futex_get, entry, uaddr, wp, f);
417
418 if (flags & FUTEX_CREATE_WP) {
419 *wp = malloc(sizeof(struct waiting_proc), M_FUTEX_WP, M_WAITOK);
420 (*wp)->wp_flags = 0;
421 }
422 error = futex_get0(uaddr, f, flags);
423 if (error) {
424 LIN_SDT_PROBE0(futex, futex_get, error);
425
426 if (flags & FUTEX_CREATE_WP)
427 free(*wp, M_FUTEX_WP);
428
429 LIN_SDT_PROBE1(futex, futex_get, return, error);
430 return (error);
431 }
432 if (flags & FUTEX_CREATE_WP) {
433 TAILQ_INSERT_HEAD(&(*f)->f_waiting_proc, *wp, wp_list);
434 (*wp)->wp_futex = *f;
435 }
436
437 LIN_SDT_PROBE1(futex, futex_get, return, error);
438 return (error);
439 }
440
441 static int
futex_sleep(struct futex * f,struct waiting_proc * wp,int timeout)442 futex_sleep(struct futex *f, struct waiting_proc *wp, int timeout)
443 {
444 int error;
445
446 FUTEX_ASSERT_LOCKED(f);
447 LIN_SDT_PROBE3(futex, futex_sleep, entry, f, wp, timeout);
448 LINUX_CTR4(sys_futex, "futex_sleep enter uaddr %p wp %p timo %d ref %d",
449 f->f_uaddr, wp, timeout, f->f_refcount);
450 error = sx_sleep(wp, &f->f_lck, PCATCH, "futex", timeout);
451 if (wp->wp_flags & FUTEX_WP_REQUEUED) {
452 KASSERT(f != wp->wp_futex, ("futex != wp_futex"));
453
454 if (error) {
455 LIN_SDT_PROBE5(futex, futex_sleep, requeue_error, error,
456 f->f_uaddr, wp, wp->wp_futex->f_uaddr,
457 wp->wp_futex->f_refcount);
458 }
459
460 LINUX_CTR5(sys_futex, "futex_sleep out error %d uaddr %p wp"
461 " %p requeued uaddr %p ref %d",
462 error, f->f_uaddr, wp, wp->wp_futex->f_uaddr,
463 wp->wp_futex->f_refcount);
464 futex_put(f, NULL);
465 f = wp->wp_futex;
466 FUTEX_LOCK(f);
467 } else {
468 if (error) {
469 LIN_SDT_PROBE3(futex, futex_sleep, sleep_error, error,
470 f->f_uaddr, wp);
471 }
472 LINUX_CTR3(sys_futex, "futex_sleep out error %d uaddr %p wp %p",
473 error, f->f_uaddr, wp);
474 }
475
476 futex_put(f, wp);
477
478 LIN_SDT_PROBE1(futex, futex_sleep, return, error);
479 return (error);
480 }
481
482 static int
futex_wake(struct futex * f,int n,uint32_t bitset)483 futex_wake(struct futex *f, int n, uint32_t bitset)
484 {
485 struct waiting_proc *wp, *wpt;
486 int count = 0;
487
488 LIN_SDT_PROBE3(futex, futex_wake, entry, f, n, bitset);
489
490 if (bitset == 0) {
491 LIN_SDT_PROBE1(futex, futex_wake, return, EINVAL);
492 return (EINVAL);
493 }
494
495 FUTEX_ASSERT_LOCKED(f);
496 TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) {
497 LIN_SDT_PROBE3(futex, futex_wake, iterate, f->f_uaddr, wp,
498 f->f_refcount);
499 LINUX_CTR3(sys_futex, "futex_wake uaddr %p wp %p ref %d",
500 f->f_uaddr, wp, f->f_refcount);
501 /*
502 * Unless we find a matching bit in
503 * the bitset, continue searching.
504 */
505 if (!(wp->wp_futex->f_bitset & bitset))
506 continue;
507
508 wp->wp_flags |= FUTEX_WP_REMOVED;
509 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
510 LIN_SDT_PROBE1(futex, futex_wake, wakeup, wp);
511 wakeup_one(wp);
512 if (++count == n)
513 break;
514 }
515
516 LIN_SDT_PROBE1(futex, futex_wake, return, count);
517 return (count);
518 }
519
520 static int
futex_requeue(struct futex * f,int n,struct futex * f2,int n2)521 futex_requeue(struct futex *f, int n, struct futex *f2, int n2)
522 {
523 struct waiting_proc *wp, *wpt;
524 int count = 0;
525
526 LIN_SDT_PROBE4(futex, futex_requeue, entry, f, n, f2, n2);
527
528 FUTEX_ASSERT_LOCKED(f);
529 FUTEX_ASSERT_LOCKED(f2);
530
531 TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) {
532 if (++count <= n) {
533 LINUX_CTR2(sys_futex, "futex_req_wake uaddr %p wp %p",
534 f->f_uaddr, wp);
535 wp->wp_flags |= FUTEX_WP_REMOVED;
536 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
537 LIN_SDT_PROBE1(futex, futex_requeue, wakeup, wp);
538 wakeup_one(wp);
539 } else {
540 LIN_SDT_PROBE3(futex, futex_requeue, requeue,
541 f->f_uaddr, wp, f2->f_uaddr);
542 LINUX_CTR3(sys_futex, "futex_requeue uaddr %p wp %p to %p",
543 f->f_uaddr, wp, f2->f_uaddr);
544 wp->wp_flags |= FUTEX_WP_REQUEUED;
545 /* Move wp to wp_list of f2 futex */
546 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
547 TAILQ_INSERT_HEAD(&f2->f_waiting_proc, wp, wp_list);
548
549 /*
550 * Thread which sleeps on wp after waking should
551 * acquire f2 lock, so increment refcount of f2 to
552 * prevent it from premature deallocation.
553 */
554 wp->wp_futex = f2;
555 FUTEXES_LOCK;
556 ++f2->f_refcount;
557 FUTEXES_UNLOCK;
558 if (count - n >= n2)
559 break;
560 }
561 }
562
563 LIN_SDT_PROBE1(futex, futex_requeue, return, count);
564 return (count);
565 }
566
567 static int
futex_wait(struct futex * f,struct waiting_proc * wp,int timeout_hz,uint32_t bitset)568 futex_wait(struct futex *f, struct waiting_proc *wp, int timeout_hz,
569 uint32_t bitset)
570 {
571 int error;
572
573 LIN_SDT_PROBE4(futex, futex_wait, entry, f, wp, timeout_hz, bitset);
574
575 if (bitset == 0) {
576 LIN_SDT_PROBE1(futex, futex_wait, return, EINVAL);
577 return (EINVAL);
578 }
579
580 f->f_bitset = bitset;
581 error = futex_sleep(f, wp, timeout_hz);
582 if (error)
583 LIN_SDT_PROBE1(futex, futex_wait, sleep_error, error);
584 if (error == EWOULDBLOCK)
585 error = ETIMEDOUT;
586
587 LIN_SDT_PROBE1(futex, futex_wait, return, error);
588 return (error);
589 }
590
591 static int
futex_atomic_op(struct thread * td,int encoded_op,uint32_t * uaddr)592 futex_atomic_op(struct thread *td, int encoded_op, uint32_t *uaddr)
593 {
594 int op = (encoded_op >> 28) & 7;
595 int cmp = (encoded_op >> 24) & 15;
596 int oparg = (encoded_op << 8) >> 20;
597 int cmparg = (encoded_op << 20) >> 20;
598 int oldval = 0, ret;
599
600 LIN_SDT_PROBE3(futex, futex_atomic_op, entry, td, encoded_op, uaddr);
601
602 if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
603 oparg = 1 << oparg;
604
605 LIN_SDT_PROBE4(futex, futex_atomic_op, decoded_op, op, cmp, oparg,
606 cmparg);
607
608 /* XXX: Linux verifies access here and returns EFAULT */
609 LIN_SDT_PROBE0(futex, futex_atomic_op, missing_access_check);
610
611 switch (op) {
612 case FUTEX_OP_SET:
613 ret = futex_xchgl(oparg, uaddr, &oldval);
614 break;
615 case FUTEX_OP_ADD:
616 ret = futex_addl(oparg, uaddr, &oldval);
617 break;
618 case FUTEX_OP_OR:
619 ret = futex_orl(oparg, uaddr, &oldval);
620 break;
621 case FUTEX_OP_ANDN:
622 ret = futex_andl(~oparg, uaddr, &oldval);
623 break;
624 case FUTEX_OP_XOR:
625 ret = futex_xorl(oparg, uaddr, &oldval);
626 break;
627 default:
628 LIN_SDT_PROBE1(futex, futex_atomic_op, unimplemented_op, op);
629 ret = -ENOSYS;
630 break;
631 }
632
633 if (ret) {
634 LIN_SDT_PROBE1(futex, futex_atomic_op, return, ret);
635 return (ret);
636 }
637
638 switch (cmp) {
639 case FUTEX_OP_CMP_EQ:
640 ret = (oldval == cmparg);
641 break;
642 case FUTEX_OP_CMP_NE:
643 ret = (oldval != cmparg);
644 break;
645 case FUTEX_OP_CMP_LT:
646 ret = (oldval < cmparg);
647 break;
648 case FUTEX_OP_CMP_GE:
649 ret = (oldval >= cmparg);
650 break;
651 case FUTEX_OP_CMP_LE:
652 ret = (oldval <= cmparg);
653 break;
654 case FUTEX_OP_CMP_GT:
655 ret = (oldval > cmparg);
656 break;
657 default:
658 LIN_SDT_PROBE1(futex, futex_atomic_op, unimplemented_cmp, cmp);
659 ret = -ENOSYS;
660 }
661
662 LIN_SDT_PROBE1(futex, futex_atomic_op, return, ret);
663 return (ret);
664 }
665
666 int
linux_sys_futex(struct thread * td,struct linux_sys_futex_args * args)667 linux_sys_futex(struct thread *td, struct linux_sys_futex_args *args)
668 {
669 int clockrt, nrwake, op_ret, ret;
670 struct linux_pemuldata *pem;
671 struct waiting_proc *wp;
672 struct futex *f, *f2;
673 struct l_timespec ltimeout;
674 struct timespec timeout;
675 struct timeval utv, ctv;
676 int timeout_hz;
677 int error;
678 uint32_t flags, val;
679
680 LIN_SDT_PROBE2(futex, linux_sys_futex, entry, td, args);
681
682 if (args->op & LINUX_FUTEX_PRIVATE_FLAG) {
683 flags = 0;
684 args->op &= ~LINUX_FUTEX_PRIVATE_FLAG;
685 } else
686 flags = FUTEX_SHARED;
687
688 /*
689 * Currently support for switching between CLOCK_MONOTONIC and
690 * CLOCK_REALTIME is not present. However Linux forbids the use of
691 * FUTEX_CLOCK_REALTIME with any op except FUTEX_WAIT_BITSET and
692 * FUTEX_WAIT_REQUEUE_PI.
693 */
694 clockrt = args->op & LINUX_FUTEX_CLOCK_REALTIME;
695 args->op = args->op & ~LINUX_FUTEX_CLOCK_REALTIME;
696 if (clockrt && args->op != LINUX_FUTEX_WAIT_BITSET &&
697 args->op != LINUX_FUTEX_WAIT_REQUEUE_PI) {
698 LIN_SDT_PROBE0(futex, linux_sys_futex,
699 unimplemented_clockswitch);
700 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
701 return (ENOSYS);
702 }
703
704 error = 0;
705 f = f2 = NULL;
706
707 switch (args->op) {
708 case LINUX_FUTEX_WAIT:
709 args->val3 = FUTEX_BITSET_MATCH_ANY;
710 /* FALLTHROUGH */
711
712 case LINUX_FUTEX_WAIT_BITSET:
713 LIN_SDT_PROBE3(futex, linux_sys_futex, debug_wait, args->uaddr,
714 args->val, args->val3);
715 LINUX_CTR3(sys_futex, "WAIT uaddr %p val 0x%x bitset 0x%x",
716 args->uaddr, args->val, args->val3);
717
718 if (args->timeout != NULL) {
719 error = copyin(args->timeout, <imeout, sizeof(ltimeout));
720 if (error) {
721 LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error,
722 error);
723 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
724 return (error);
725 }
726 error = linux_to_native_timespec(&timeout, <imeout);
727 if (error)
728 return (error);
729 TIMESPEC_TO_TIMEVAL(&utv, &timeout);
730 error = itimerfix(&utv);
731 if (error) {
732 LIN_SDT_PROBE1(futex, linux_sys_futex, itimerfix_error,
733 error);
734 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
735 return (error);
736 }
737 if (clockrt) {
738 microtime(&ctv);
739 timevalsub(&utv, &ctv);
740 } else if (args->op == LINUX_FUTEX_WAIT_BITSET) {
741 microuptime(&ctv);
742 timevalsub(&utv, &ctv);
743 }
744 if (utv.tv_sec < 0)
745 timevalclear(&utv);
746 timeout_hz = tvtohz(&utv);
747 } else
748 timeout_hz = 0;
749
750 error = futex_get(args->uaddr, &wp, &f,
751 flags | FUTEX_CREATE_WP);
752 if (error) {
753 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
754 return (error);
755 }
756
757 error = copyin(args->uaddr, &val, sizeof(val));
758 if (error) {
759 LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error,
760 error);
761 LINUX_CTR1(sys_futex, "WAIT copyin failed %d",
762 error);
763 futex_put(f, wp);
764
765 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
766 return (error);
767 }
768 if (val != args->val) {
769 LIN_SDT_PROBE4(futex, linux_sys_futex,
770 debug_wait_value_neq, args->uaddr, args->val, val,
771 args->val3);
772 LINUX_CTR3(sys_futex,
773 "WAIT uaddr %p val 0x%x != uval 0x%x",
774 args->uaddr, args->val, val);
775 futex_put(f, wp);
776
777 LIN_SDT_PROBE1(futex, linux_sys_futex, return,
778 EWOULDBLOCK);
779 return (EWOULDBLOCK);
780 }
781
782 error = futex_wait(f, wp, timeout_hz, args->val3);
783 break;
784
785 case LINUX_FUTEX_WAKE:
786 args->val3 = FUTEX_BITSET_MATCH_ANY;
787 /* FALLTHROUGH */
788
789 case LINUX_FUTEX_WAKE_BITSET:
790 LIN_SDT_PROBE3(futex, linux_sys_futex, debug_wake, args->uaddr,
791 args->val, args->val3);
792 LINUX_CTR3(sys_futex, "WAKE uaddr %p nrwake 0x%x bitset 0x%x",
793 args->uaddr, args->val, args->val3);
794
795 error = futex_get(args->uaddr, NULL, &f,
796 flags | FUTEX_DONTCREATE);
797 if (error) {
798 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
799 return (error);
800 }
801
802 if (f == NULL) {
803 td->td_retval[0] = 0;
804
805 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
806 return (error);
807 }
808 td->td_retval[0] = futex_wake(f, args->val, args->val3);
809 futex_put(f, NULL);
810 break;
811
812 case LINUX_FUTEX_CMP_REQUEUE:
813 LIN_SDT_PROBE5(futex, linux_sys_futex, debug_cmp_requeue,
814 args->uaddr, args->val, args->val3, args->uaddr2,
815 args->timeout);
816 LINUX_CTR5(sys_futex, "CMP_REQUEUE uaddr %p "
817 "nrwake 0x%x uval 0x%x uaddr2 %p nrequeue 0x%x",
818 args->uaddr, args->val, args->val3, args->uaddr2,
819 args->timeout);
820
821 /*
822 * Linux allows this, we would not, it is an incorrect
823 * usage of declared ABI, so return EINVAL.
824 */
825 if (args->uaddr == args->uaddr2) {
826 LIN_SDT_PROBE0(futex, linux_sys_futex,
827 invalid_cmp_requeue_use);
828 LIN_SDT_PROBE1(futex, linux_sys_futex, return, EINVAL);
829 return (EINVAL);
830 }
831
832 error = futex_get(args->uaddr, NULL, &f, flags);
833 if (error) {
834 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
835 return (error);
836 }
837
838 /*
839 * To avoid deadlocks return EINVAL if second futex
840 * exists at this time.
841 *
842 * Glibc fall back to FUTEX_WAKE in case of any error
843 * returned by FUTEX_CMP_REQUEUE.
844 */
845 error = futex_get(args->uaddr2, NULL, &f2,
846 flags | FUTEX_DONTEXISTS);
847 if (error) {
848 futex_put(f, NULL);
849
850 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
851 return (error);
852 }
853 error = copyin(args->uaddr, &val, sizeof(val));
854 if (error) {
855 LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error,
856 error);
857 LINUX_CTR1(sys_futex, "CMP_REQUEUE copyin failed %d",
858 error);
859 futex_put(f2, NULL);
860 futex_put(f, NULL);
861
862 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
863 return (error);
864 }
865 if (val != args->val3) {
866 LIN_SDT_PROBE2(futex, linux_sys_futex,
867 debug_cmp_requeue_value_neq, args->val, val);
868 LINUX_CTR2(sys_futex, "CMP_REQUEUE val 0x%x != uval 0x%x",
869 args->val, val);
870 futex_put(f2, NULL);
871 futex_put(f, NULL);
872
873 LIN_SDT_PROBE1(futex, linux_sys_futex, return, EAGAIN);
874 return (EAGAIN);
875 }
876
877 nrwake = (int)(unsigned long)args->timeout;
878 td->td_retval[0] = futex_requeue(f, args->val, f2, nrwake);
879 futex_put(f2, NULL);
880 futex_put(f, NULL);
881 break;
882
883 case LINUX_FUTEX_WAKE_OP:
884 LIN_SDT_PROBE5(futex, linux_sys_futex, debug_wake_op,
885 args->uaddr, args->op, args->val, args->uaddr2, args->val3);
886 LINUX_CTR5(sys_futex, "WAKE_OP "
887 "uaddr %p nrwake 0x%x uaddr2 %p op 0x%x nrwake2 0x%x",
888 args->uaddr, args->val, args->uaddr2, args->val3,
889 args->timeout);
890
891 error = futex_get(args->uaddr, NULL, &f, flags);
892 if (error) {
893 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
894 return (error);
895 }
896
897 if (args->uaddr != args->uaddr2)
898 error = futex_get(args->uaddr2, NULL, &f2, flags);
899 if (error) {
900 futex_put(f, NULL);
901
902 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
903 return (error);
904 }
905
906 /*
907 * This function returns positive number as results and
908 * negative as errors
909 */
910 op_ret = futex_atomic_op(td, args->val3, args->uaddr2);
911
912 LINUX_CTR2(sys_futex, "WAKE_OP atomic_op uaddr %p ret 0x%x",
913 args->uaddr, op_ret);
914
915 if (op_ret < 0) {
916 /* XXX: We don't handle the EFAULT yet. */
917 if (op_ret != -EFAULT) {
918 if (f2 != NULL)
919 futex_put(f2, NULL);
920 futex_put(f, NULL);
921
922 LIN_SDT_PROBE1(futex, linux_sys_futex, return,
923 -op_ret);
924 return (-op_ret);
925 } else {
926 LIN_SDT_PROBE0(futex, linux_sys_futex,
927 unhandled_efault);
928 }
929 if (f2 != NULL)
930 futex_put(f2, NULL);
931 futex_put(f, NULL);
932
933 LIN_SDT_PROBE1(futex, linux_sys_futex, return, EFAULT);
934 return (EFAULT);
935 }
936
937 ret = futex_wake(f, args->val, args->val3);
938
939 if (op_ret > 0) {
940 op_ret = 0;
941 nrwake = (int)(unsigned long)args->timeout;
942
943 if (f2 != NULL)
944 op_ret += futex_wake(f2, nrwake, args->val3);
945 else
946 op_ret += futex_wake(f, nrwake, args->val3);
947 ret += op_ret;
948
949 }
950 if (f2 != NULL)
951 futex_put(f2, NULL);
952 futex_put(f, NULL);
953 td->td_retval[0] = ret;
954 break;
955
956 case LINUX_FUTEX_LOCK_PI:
957 /* not yet implemented */
958 pem = pem_find(td->td_proc);
959 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
960 linux_msg(td,
961 "linux_sys_futex: "
962 "unsupported futex_pi op\n");
963 pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
964 LIN_SDT_PROBE0(futex, linux_sys_futex,
965 unimplemented_lock_pi);
966 }
967 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
968 return (ENOSYS);
969
970 case LINUX_FUTEX_UNLOCK_PI:
971 /* not yet implemented */
972 pem = pem_find(td->td_proc);
973 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
974 linux_msg(td,
975 "linux_sys_futex: "
976 "unsupported futex_pi op\n");
977 pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
978 LIN_SDT_PROBE0(futex, linux_sys_futex,
979 unimplemented_unlock_pi);
980 }
981 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
982 return (ENOSYS);
983
984 case LINUX_FUTEX_TRYLOCK_PI:
985 /* not yet implemented */
986 pem = pem_find(td->td_proc);
987 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
988 linux_msg(td,
989 "linux_sys_futex: "
990 "unsupported futex_pi op\n");
991 pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
992 LIN_SDT_PROBE0(futex, linux_sys_futex,
993 unimplemented_trylock_pi);
994 }
995 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
996 return (ENOSYS);
997
998 case LINUX_FUTEX_REQUEUE:
999
1000 /*
1001 * Glibc does not use this operation since version 2.3.3,
1002 * as it is racy and replaced by FUTEX_CMP_REQUEUE operation.
1003 * Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when
1004 * FUTEX_REQUEUE returned EINVAL.
1005 */
1006 pem = pem_find(td->td_proc);
1007 if ((pem->flags & LINUX_XDEPR_REQUEUEOP) == 0) {
1008 linux_msg(td,
1009 "linux_sys_futex: "
1010 "unsupported futex_requeue op\n");
1011 pem->flags |= LINUX_XDEPR_REQUEUEOP;
1012 LIN_SDT_PROBE0(futex, linux_sys_futex,
1013 deprecated_requeue);
1014 }
1015
1016 LIN_SDT_PROBE1(futex, linux_sys_futex, return, EINVAL);
1017 return (EINVAL);
1018
1019 case LINUX_FUTEX_WAIT_REQUEUE_PI:
1020 /* not yet implemented */
1021 pem = pem_find(td->td_proc);
1022 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
1023 linux_msg(td,
1024 "linux_sys_futex: "
1025 "unsupported futex_pi op\n");
1026 pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
1027 LIN_SDT_PROBE0(futex, linux_sys_futex,
1028 unimplemented_wait_requeue_pi);
1029 }
1030 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1031 return (ENOSYS);
1032
1033 case LINUX_FUTEX_CMP_REQUEUE_PI:
1034 /* not yet implemented */
1035 pem = pem_find(td->td_proc);
1036 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
1037 linux_msg(td,
1038 "linux_sys_futex: "
1039 "unsupported futex_pi op\n");
1040 pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
1041 LIN_SDT_PROBE0(futex, linux_sys_futex,
1042 unimplemented_cmp_requeue_pi);
1043 }
1044 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1045 return (ENOSYS);
1046
1047 default:
1048 linux_msg(td,
1049 "linux_sys_futex: unknown op %d\n", args->op);
1050 LIN_SDT_PROBE1(futex, linux_sys_futex, unknown_operation,
1051 args->op);
1052 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1053 return (ENOSYS);
1054 }
1055
1056 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
1057 return (error);
1058 }
1059
1060 int
linux_set_robust_list(struct thread * td,struct linux_set_robust_list_args * args)1061 linux_set_robust_list(struct thread *td, struct linux_set_robust_list_args *args)
1062 {
1063 struct linux_emuldata *em;
1064
1065 LIN_SDT_PROBE2(futex, linux_set_robust_list, entry, td, args);
1066
1067 if (args->len != sizeof(struct linux_robust_list_head)) {
1068 LIN_SDT_PROBE0(futex, linux_set_robust_list, size_error);
1069 LIN_SDT_PROBE1(futex, linux_set_robust_list, return, EINVAL);
1070 return (EINVAL);
1071 }
1072
1073 em = em_find(td);
1074 em->robust_futexes = args->head;
1075
1076 LIN_SDT_PROBE1(futex, linux_set_robust_list, return, 0);
1077 return (0);
1078 }
1079
1080 int
linux_get_robust_list(struct thread * td,struct linux_get_robust_list_args * args)1081 linux_get_robust_list(struct thread *td, struct linux_get_robust_list_args *args)
1082 {
1083 struct linux_emuldata *em;
1084 struct linux_robust_list_head *head;
1085 l_size_t len = sizeof(struct linux_robust_list_head);
1086 struct thread *td2;
1087 int error = 0;
1088
1089 LIN_SDT_PROBE2(futex, linux_get_robust_list, entry, td, args);
1090
1091 if (!args->pid) {
1092 em = em_find(td);
1093 KASSERT(em != NULL, ("get_robust_list: emuldata notfound.\n"));
1094 head = em->robust_futexes;
1095 } else {
1096 td2 = tdfind(args->pid, -1);
1097 if (td2 == NULL) {
1098 LIN_SDT_PROBE1(futex, linux_get_robust_list, return,
1099 ESRCH);
1100 return (ESRCH);
1101 }
1102 if (SV_PROC_ABI(td2->td_proc) != SV_ABI_LINUX) {
1103 LIN_SDT_PROBE1(futex, linux_get_robust_list, return,
1104 EPERM);
1105 PROC_UNLOCK(td2->td_proc);
1106 return (EPERM);
1107 }
1108
1109 em = em_find(td2);
1110 KASSERT(em != NULL, ("get_robust_list: emuldata notfound.\n"));
1111 /* XXX: ptrace? */
1112 if (priv_check(td, PRIV_CRED_SETUID) ||
1113 priv_check(td, PRIV_CRED_SETEUID) ||
1114 p_candebug(td, td2->td_proc)) {
1115 PROC_UNLOCK(td2->td_proc);
1116
1117 LIN_SDT_PROBE1(futex, linux_get_robust_list, return,
1118 EPERM);
1119 return (EPERM);
1120 }
1121 head = em->robust_futexes;
1122
1123 PROC_UNLOCK(td2->td_proc);
1124 }
1125
1126 error = copyout(&len, args->len, sizeof(l_size_t));
1127 if (error) {
1128 LIN_SDT_PROBE1(futex, linux_get_robust_list, copyout_error,
1129 error);
1130 LIN_SDT_PROBE1(futex, linux_get_robust_list, return, EFAULT);
1131 return (EFAULT);
1132 }
1133
1134 error = copyout(head, args->head, sizeof(struct linux_robust_list_head));
1135 if (error) {
1136 LIN_SDT_PROBE1(futex, linux_get_robust_list, copyout_error,
1137 error);
1138 }
1139
1140 LIN_SDT_PROBE1(futex, linux_get_robust_list, return, error);
1141 return (error);
1142 }
1143
1144 static int
handle_futex_death(struct linux_emuldata * em,uint32_t * uaddr,unsigned int pi)1145 handle_futex_death(struct linux_emuldata *em, uint32_t *uaddr,
1146 unsigned int pi)
1147 {
1148 uint32_t uval, nval, mval;
1149 struct futex *f;
1150 int error;
1151
1152 LIN_SDT_PROBE3(futex, handle_futex_death, entry, em, uaddr, pi);
1153
1154 retry:
1155 error = copyin(uaddr, &uval, 4);
1156 if (error) {
1157 LIN_SDT_PROBE1(futex, handle_futex_death, copyin_error, error);
1158 LIN_SDT_PROBE1(futex, handle_futex_death, return, EFAULT);
1159 return (EFAULT);
1160 }
1161 if ((uval & FUTEX_TID_MASK) == em->em_tid) {
1162 mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED;
1163 nval = casuword32(uaddr, uval, mval);
1164
1165 if (nval == -1) {
1166 LIN_SDT_PROBE1(futex, handle_futex_death, return,
1167 EFAULT);
1168 return (EFAULT);
1169 }
1170
1171 if (nval != uval)
1172 goto retry;
1173
1174 if (!pi && (uval & FUTEX_WAITERS)) {
1175 error = futex_get(uaddr, NULL, &f,
1176 FUTEX_DONTCREATE | FUTEX_SHARED);
1177 if (error) {
1178 LIN_SDT_PROBE1(futex, handle_futex_death,
1179 return, error);
1180 return (error);
1181 }
1182 if (f != NULL) {
1183 futex_wake(f, 1, FUTEX_BITSET_MATCH_ANY);
1184 futex_put(f, NULL);
1185 }
1186 }
1187 }
1188
1189 LIN_SDT_PROBE1(futex, handle_futex_death, return, 0);
1190 return (0);
1191 }
1192
1193 static int
fetch_robust_entry(struct linux_robust_list ** entry,struct linux_robust_list ** head,unsigned int * pi)1194 fetch_robust_entry(struct linux_robust_list **entry,
1195 struct linux_robust_list **head, unsigned int *pi)
1196 {
1197 l_ulong uentry;
1198 int error;
1199
1200 LIN_SDT_PROBE3(futex, fetch_robust_entry, entry, entry, head, pi);
1201
1202 error = copyin((const void *)head, &uentry, sizeof(l_ulong));
1203 if (error) {
1204 LIN_SDT_PROBE1(futex, fetch_robust_entry, copyin_error, error);
1205 LIN_SDT_PROBE1(futex, fetch_robust_entry, return, EFAULT);
1206 return (EFAULT);
1207 }
1208
1209 *entry = (void *)(uentry & ~1UL);
1210 *pi = uentry & 1;
1211
1212 LIN_SDT_PROBE1(futex, fetch_robust_entry, return, 0);
1213 return (0);
1214 }
1215
1216 /* This walks the list of robust futexes releasing them. */
1217 void
release_futexes(struct thread * td,struct linux_emuldata * em)1218 release_futexes(struct thread *td, struct linux_emuldata *em)
1219 {
1220 struct linux_robust_list_head *head = NULL;
1221 struct linux_robust_list *entry, *next_entry, *pending;
1222 unsigned int limit = 2048, pi, next_pi, pip;
1223 l_long futex_offset;
1224 int rc, error;
1225
1226 LIN_SDT_PROBE2(futex, release_futexes, entry, td, em);
1227
1228 head = em->robust_futexes;
1229
1230 if (head == NULL) {
1231 LIN_SDT_PROBE0(futex, release_futexes, return);
1232 return;
1233 }
1234
1235 if (fetch_robust_entry(&entry, PTRIN(&head->list.next), &pi)) {
1236 LIN_SDT_PROBE0(futex, release_futexes, return);
1237 return;
1238 }
1239
1240 error = copyin(&head->futex_offset, &futex_offset,
1241 sizeof(futex_offset));
1242 if (error) {
1243 LIN_SDT_PROBE1(futex, release_futexes, copyin_error, error);
1244 LIN_SDT_PROBE0(futex, release_futexes, return);
1245 return;
1246 }
1247
1248 if (fetch_robust_entry(&pending, PTRIN(&head->pending_list), &pip)) {
1249 LIN_SDT_PROBE0(futex, release_futexes, return);
1250 return;
1251 }
1252
1253 while (entry != &head->list) {
1254 rc = fetch_robust_entry(&next_entry, PTRIN(&entry->next), &next_pi);
1255
1256 if (entry != pending)
1257 if (handle_futex_death(em,
1258 (uint32_t *)((caddr_t)entry + futex_offset), pi)) {
1259 LIN_SDT_PROBE0(futex, release_futexes, return);
1260 return;
1261 }
1262 if (rc) {
1263 LIN_SDT_PROBE0(futex, release_futexes, return);
1264 return;
1265 }
1266
1267 entry = next_entry;
1268 pi = next_pi;
1269
1270 if (!--limit)
1271 break;
1272
1273 sched_relinquish(curthread);
1274 }
1275
1276 if (pending)
1277 handle_futex_death(em, (uint32_t *)((caddr_t)pending + futex_offset), pip);
1278
1279 LIN_SDT_PROBE0(futex, release_futexes, return);
1280 }
1281