sys/compat/linux/linux_futex.c

   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("$FreeBSD$");
  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 struct futex_list futex_list;
 211
 212 #define FUTEX_LOCK(f)           mtx_lock(&(f)->f_lck)
 213 #define FUTEX_LOCKED(f)         mtx_owned(&(f)->f_lck)
 214 #define FUTEX_UNLOCK(f)         mtx_unlock(&(f)->f_lck)
 215 #define FUTEX_INIT(f)           do { \
 216                                     mtx_init(&(f)->f_lck, "ftlk", NULL, \
 217                                         MTX_DUPOK); \
 218                                     LIN_SDT_PROBE1(futex, futex, create, \
 219                                         &(f)->f_lck); \
 220                                 } while (0)
 221 #define FUTEX_DESTROY(f)        do { \
 222                                     LIN_SDT_PROBE1(futex, futex, destroy, \
 223                                         &(f)->f_lck); \
 224                                     mtx_destroy(&(f)->f_lck); \
 225                                 } while (0)
 226 #define FUTEX_ASSERT_LOCKED(f)  mtx_assert(&(f)->f_lck, MA_OWNED)
 227 #define FUTEX_ASSERT_UNLOCKED(f) mtx_assert(&(f)->f_lck, MA_NOTOWNED)
 228
 229 struct mtx futex_mtx;                   /* protects the futex list */
 230 #define FUTEXES_LOCK            do { \
 231                                     mtx_lock(&futex_mtx); \
 232                                     LIN_SDT_PROBE1(locks, futex_mtx, \
 233                                         locked, &futex_mtx); \
 234                                 } while (0)
 235 #define FUTEXES_UNLOCK          do { \
 236                                     LIN_SDT_PROBE1(locks, futex_mtx, \
 237                                         unlock, &futex_mtx); \
 238                                     mtx_unlock(&futex_mtx); \
 239                                 } while (0)
 240
 241 /* flags for futex_get() */
 242 #define FUTEX_CREATE_WP         0x1     /* create waiting_proc */
 243 #define FUTEX_DONTCREATE        0x2     /* don't create futex if not exists */
 244 #define FUTEX_DONTEXISTS        0x4     /* return EINVAL if futex exists */
 245 #define FUTEX_SHARED            0x8     /* shared futex */
 246 #define FUTEX_DONTLOCK          0x10    /* don't lock futex */
 247
 248 /* wp_flags */
 249 #define FUTEX_WP_REQUEUED       0x1     /* wp requeued - wp moved from wp_list
 250                                          * of futex where thread sleep to wp_list
 251                                          * of another futex.
 252                                          */
 253 #define FUTEX_WP_REMOVED        0x2     /* wp is woken up and removed from futex
 254                                          * wp_list to prevent double wakeup.
 255                                          */
 256
 257 static void futex_put(struct futex *, struct waiting_proc *);
 258 static int futex_get0(uint32_t *, struct futex **f, uint32_t);
 259 static int futex_get(uint32_t *, struct waiting_proc **, struct futex **,
 260     uint32_t);
 261 static int futex_sleep(struct futex *, struct waiting_proc *, struct timespec *);
 262 static int futex_wake(struct futex *, int, uint32_t);
 263 static int futex_requeue(struct futex *, int, struct futex *, int);
 264 static int futex_copyin_timeout(int, struct l_timespec *, int,
 265     struct timespec *);
 266 static int futex_wait(struct futex *, struct waiting_proc *, struct timespec *,
 267     uint32_t);
 268 static void futex_lock(struct futex *);
 269 static void futex_unlock(struct futex *);
 270 static int futex_atomic_op(struct thread *, int, uint32_t *);
 271 static int handle_futex_death(struct linux_emuldata *, uint32_t *,
 272     unsigned int);
 273 static int fetch_robust_entry(struct linux_robust_list **,
 274     struct linux_robust_list **, unsigned int *);
 275
 276 static int
 277 futex_copyin_timeout(int op, struct l_timespec *luts, int clockrt,
 278     struct timespec *ts)
 279 {
 280         struct l_timespec lts;
 281         struct timespec kts;
 282         int error;
 283
 284         error = copyin(luts, &lts, sizeof(lts));
 285         if (error)
 286                 return (error);
 287
 288         error = linux_to_native_timespec(ts, &lts);
 289         if (error)
 290                 return (error);
 291         if (clockrt) {
 292                 nanotime(&kts);
 293                 timespecsub(ts, &kts, ts);
 294         } else if (op == LINUX_FUTEX_WAIT_BITSET) {
 295                 nanouptime(&kts);
 296                 timespecsub(ts, &kts, ts);
 297         }
 298         return (error);
 299 }
 300
 301 static void
 302 futex_put(struct futex *f, struct waiting_proc *wp)
 303 {
 304         LIN_SDT_PROBE2(futex, futex_put, entry, f, wp);
 305
 306         if (wp != NULL) {
 307                 if ((wp->wp_flags & FUTEX_WP_REMOVED) == 0)
 308                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
 309                 free(wp, M_FUTEX_WP);
 310         }
 311
 312         FUTEXES_LOCK;
 313         if (--f->f_refcount == 0) {
 314                 LIST_REMOVE(f, f_list);
 315                 FUTEXES_UNLOCK;
 316                 if (FUTEX_LOCKED(f))
 317                         futex_unlock(f);
 318
 319                 LIN_SDT_PROBE3(futex, futex_put, destroy, f->f_uaddr,
 320                     f->f_refcount, f->f_key.shared);
 321                 LINUX_CTR3(sys_futex, "futex_put destroy uaddr %p ref %d "
 322                     "shared %d", f->f_uaddr, f->f_refcount, f->f_key.shared);
 323                 umtx_key_release(&f->f_key);
 324                 FUTEX_DESTROY(f);
 325                 free(f, M_FUTEX);
 326
 327                 LIN_SDT_PROBE0(futex, futex_put, return);
 328                 return;
 329         }
 330
 331         LIN_SDT_PROBE3(futex, futex_put, unlock, f->f_uaddr, f->f_refcount,
 332             f->f_key.shared);
 333         LINUX_CTR3(sys_futex, "futex_put uaddr %p ref %d shared %d",
 334             f->f_uaddr, f->f_refcount, f->f_key.shared);
 335         FUTEXES_UNLOCK;
 336         if (FUTEX_LOCKED(f))
 337                 futex_unlock(f);
 338
 339         LIN_SDT_PROBE0(futex, futex_put, return);
 340 }
 341
 342 static int
 343 futex_get0(uint32_t *uaddr, struct futex **newf, uint32_t flags)
 344 {
 345         struct futex *f, *tmpf;
 346         struct umtx_key key;
 347         int error;
 348
 349         LIN_SDT_PROBE3(futex, futex_get0, entry, uaddr, newf, flags);
 350
 351         *newf = tmpf = NULL;
 352
 353         error = umtx_key_get(uaddr, TYPE_FUTEX, (flags & FUTEX_SHARED) ?
 354             AUTO_SHARE : THREAD_SHARE, &key);
 355         if (error) {
 356                 LIN_SDT_PROBE1(futex, futex_get0, umtx_key_get_error, error);
 357                 LIN_SDT_PROBE1(futex, futex_get0, return, error);
 358                 return (error);
 359         }
 360 retry:
 361         FUTEXES_LOCK;
 362         LIST_FOREACH(f, &futex_list, f_list) {
 363                 if (umtx_key_match(&f->f_key, &key)) {
 364                         if (tmpf != NULL) {
 365                                 if (FUTEX_LOCKED(tmpf))
 366                                         futex_unlock(tmpf);
 367                                 FUTEX_DESTROY(tmpf);
 368                                 free(tmpf, M_FUTEX);
 369                         }
 370                         if (flags & FUTEX_DONTEXISTS) {
 371                                 FUTEXES_UNLOCK;
 372                                 umtx_key_release(&key);
 373
 374                                 LIN_SDT_PROBE1(futex, futex_get0, return,
 375                                     EINVAL);
 376                                 return (EINVAL);
 377                         }
 378
 379                         /*
 380                          * Increment refcount of the found futex to
 381                          * prevent it from deallocation before FUTEX_LOCK()
 382                          */
 383                         ++f->f_refcount;
 384                         FUTEXES_UNLOCK;
 385                         umtx_key_release(&key);
 386
 387                         if ((flags & FUTEX_DONTLOCK) == 0)
 388                                 futex_lock(f);
 389                         *newf = f;
 390                         LIN_SDT_PROBE3(futex, futex_get0, shared, uaddr,
 391                             f->f_refcount, f->f_key.shared);
 392                         LINUX_CTR3(sys_futex, "futex_get uaddr %p ref %d shared %d",
 393                             uaddr, f->f_refcount, f->f_key.shared);
 394
 395                         LIN_SDT_PROBE1(futex, futex_get0, return, 0);
 396                         return (0);
 397                 }
 398         }
 399
 400         if (flags & FUTEX_DONTCREATE) {
 401                 FUTEXES_UNLOCK;
 402                 umtx_key_release(&key);
 403                 LIN_SDT_PROBE1(futex, futex_get0, null, uaddr);
 404                 LINUX_CTR1(sys_futex, "futex_get uaddr %p null", uaddr);
 405
 406                 LIN_SDT_PROBE1(futex, futex_get0, return, 0);
 407                 return (0);
 408         }
 409
 410         if (tmpf == NULL) {
 411                 FUTEXES_UNLOCK;
 412                 tmpf = malloc(sizeof(*tmpf), M_FUTEX, M_WAITOK | M_ZERO);
 413                 tmpf->f_uaddr = uaddr;
 414                 tmpf->f_key = key;
 415                 tmpf->f_refcount = 1;
 416                 tmpf->f_bitset = FUTEX_BITSET_MATCH_ANY;
 417                 FUTEX_INIT(tmpf);
 418                 TAILQ_INIT(&tmpf->f_waiting_proc);
 419
 420                 /*
 421                  * Lock the new futex before an insert into the futex_list
 422                  * to prevent futex usage by other.
 423                  */
 424                 if ((flags & FUTEX_DONTLOCK) == 0)
 425                         futex_lock(tmpf);
 426                 goto retry;
 427         }
 428
 429         LIST_INSERT_HEAD(&futex_list, tmpf, f_list);
 430         FUTEXES_UNLOCK;
 431
 432         LIN_SDT_PROBE3(futex, futex_get0, new, uaddr, tmpf->f_refcount,
 433             tmpf->f_key.shared);
 434         LINUX_CTR3(sys_futex, "futex_get uaddr %p ref %d shared %d new",
 435             uaddr, tmpf->f_refcount, tmpf->f_key.shared);
 436         *newf = tmpf;
 437
 438         LIN_SDT_PROBE1(futex, futex_get0, return, 0);
 439         return (0);
 440 }
 441
 442 static int
 443 futex_get(uint32_t *uaddr, struct waiting_proc **wp, struct futex **f,
 444     uint32_t flags)
 445 {
 446         int error;
 447
 448         LIN_SDT_PROBE3(futex, futex_get, entry, uaddr, wp, f);
 449
 450         if (flags & FUTEX_CREATE_WP) {
 451                 *wp = malloc(sizeof(struct waiting_proc), M_FUTEX_WP, M_WAITOK);
 452                 (*wp)->wp_flags = 0;
 453         }
 454         error = futex_get0(uaddr, f, flags);
 455         if (error) {
 456                 LIN_SDT_PROBE0(futex, futex_get, error);
 457
 458                 if (flags & FUTEX_CREATE_WP)
 459                         free(*wp, M_FUTEX_WP);
 460
 461                 LIN_SDT_PROBE1(futex, futex_get, return, error);
 462                 return (error);
 463         }
 464         if (flags & FUTEX_CREATE_WP) {
 465                 TAILQ_INSERT_HEAD(&(*f)->f_waiting_proc, *wp, wp_list);
 466                 (*wp)->wp_futex = *f;
 467         }
 468
 469         LIN_SDT_PROBE1(futex, futex_get, return, error);
 470         return (error);
 471 }
 472
 473 static inline void
 474 futex_lock(struct futex *f)
 475 {
 476
 477         LINUX_CTR3(sys_futex, "futex_lock uaddr %p ref %d shared %d",
 478             f->f_uaddr, f->f_refcount, f->f_key.shared);
 479         FUTEX_ASSERT_UNLOCKED(f);
 480         FUTEX_LOCK(f);
 481 }
 482
 483 static inline void
 484 futex_unlock(struct futex *f)
 485 {
 486
 487         LINUX_CTR3(sys_futex, "futex_unlock uaddr %p ref %d shared %d",
 488             f->f_uaddr, f->f_refcount, f->f_key.shared);
 489         FUTEX_ASSERT_LOCKED(f);
 490         FUTEX_UNLOCK(f);
 491 }
 492
 493 static int
 494 futex_sleep(struct futex *f, struct waiting_proc *wp, struct timespec *ts)
 495 {
 496         struct timespec uts;
 497         sbintime_t sbt, prec, tmp;
 498         time_t over;
 499         int error;
 500
 501         FUTEX_ASSERT_LOCKED(f);
 502         if (ts != NULL) {
 503                 uts = *ts;
 504                 if (uts.tv_sec > INT32_MAX / 2) {
 505                         over = uts.tv_sec - INT32_MAX / 2;
 506                         uts.tv_sec -= over;
 507                 }
 508                 tmp = tstosbt(uts);
 509                 if (TIMESEL(&sbt, tmp))
 510                         sbt += tc_tick_sbt;
 511                 sbt += tmp;
 512                 prec = tmp;
 513                 prec >>= tc_precexp;
 514         } else {
 515                 sbt = 0;
 516                 prec = 0;
 517         }
 518         LIN_SDT_PROBE3(futex, futex_sleep, entry, f, wp, sbt);
 519         LINUX_CTR4(sys_futex, "futex_sleep enter uaddr %p wp %p timo %ld ref %d",
 520             f->f_uaddr, wp, sbt, f->f_refcount);
 521
 522         error = msleep_sbt(wp, &f->f_lck, PCATCH, "futex", sbt, prec, C_ABSOLUTE);
 523         if (wp->wp_flags & FUTEX_WP_REQUEUED) {
 524                 KASSERT(f != wp->wp_futex, ("futex != wp_futex"));
 525
 526                 if (error) {
 527                         LIN_SDT_PROBE5(futex, futex_sleep, requeue_error, error,
 528                             f->f_uaddr, wp, wp->wp_futex->f_uaddr,
 529                             wp->wp_futex->f_refcount);
 530                 }
 531
 532                 LINUX_CTR5(sys_futex, "futex_sleep out error %d uaddr %p wp"
 533                     " %p requeued uaddr %p ref %d",
 534                     error, f->f_uaddr, wp, wp->wp_futex->f_uaddr,
 535                     wp->wp_futex->f_refcount);
 536                 futex_put(f, NULL);
 537                 f = wp->wp_futex;
 538                 futex_lock(f);
 539         } else {
 540                 if (error) {
 541                         LIN_SDT_PROBE3(futex, futex_sleep, sleep_error, error,
 542                             f->f_uaddr, wp);
 543                 }
 544                 LINUX_CTR3(sys_futex, "futex_sleep out error %d uaddr %p wp %p",
 545                     error, f->f_uaddr, wp);
 546         }
 547
 548         futex_put(f, wp);
 549
 550         LIN_SDT_PROBE1(futex, futex_sleep, return, error);
 551         return (error);
 552 }
 553
 554 static int
 555 futex_wake(struct futex *f, int n, uint32_t bitset)
 556 {
 557         struct waiting_proc *wp, *wpt;
 558         int count = 0;
 559
 560         LIN_SDT_PROBE3(futex, futex_wake, entry, f, n, bitset);
 561
 562         if (bitset == 0) {
 563                 LIN_SDT_PROBE1(futex, futex_wake, return, EINVAL);
 564                 return (EINVAL);
 565         }
 566
 567         FUTEX_ASSERT_LOCKED(f);
 568         TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) {
 569                 LIN_SDT_PROBE3(futex, futex_wake, iterate, f->f_uaddr, wp,
 570                     f->f_refcount);
 571                 LINUX_CTR3(sys_futex, "futex_wake uaddr %p wp %p ref %d",
 572                     f->f_uaddr, wp, f->f_refcount);
 573                 /*
 574                  * Unless we find a matching bit in
 575                  * the bitset, continue searching.
 576                  */
 577                 if (!(wp->wp_futex->f_bitset & bitset))
 578                         continue;
 579
 580                 wp->wp_flags |= FUTEX_WP_REMOVED;
 581                 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
 582                 LIN_SDT_PROBE1(futex, futex_wake, wakeup, wp);
 583                 wakeup_one(wp);
 584                 if (++count == n)
 585                         break;
 586         }
 587
 588         LIN_SDT_PROBE1(futex, futex_wake, return, count);
 589         return (count);
 590 }
 591
 592 static int
 593 futex_requeue(struct futex *f, int n, struct futex *f2, int n2)
 594 {
 595         struct waiting_proc *wp, *wpt;
 596         int count = 0;
 597
 598         LIN_SDT_PROBE4(futex, futex_requeue, entry, f, n, f2, n2);
 599
 600         FUTEX_ASSERT_LOCKED(f);
 601         FUTEX_ASSERT_LOCKED(f2);
 602
 603         TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) {
 604                 if (++count <= n) {
 605                         LINUX_CTR2(sys_futex, "futex_req_wake uaddr %p wp %p",
 606                             f->f_uaddr, wp);
 607                         wp->wp_flags |= FUTEX_WP_REMOVED;
 608                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
 609                         LIN_SDT_PROBE1(futex, futex_requeue, wakeup, wp);
 610                         wakeup_one(wp);
 611                 } else {
 612                         LIN_SDT_PROBE3(futex, futex_requeue, requeue,
 613                             f->f_uaddr, wp, f2->f_uaddr);
 614                         LINUX_CTR3(sys_futex, "futex_requeue uaddr %p wp %p to %p",
 615                             f->f_uaddr, wp, f2->f_uaddr);
 616                         wp->wp_flags |= FUTEX_WP_REQUEUED;
 617                         /* Move wp to wp_list of f2 futex */
 618                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
 619                         TAILQ_INSERT_HEAD(&f2->f_waiting_proc, wp, wp_list);
 620
 621                         /*
 622                          * Thread which sleeps on wp after waking should
 623                          * acquire f2 lock, so increment refcount of f2 to
 624                          * prevent it from premature deallocation.
 625                          */
 626                         wp->wp_futex = f2;
 627                         FUTEXES_LOCK;
 628                         ++f2->f_refcount;
 629                         FUTEXES_UNLOCK;
 630                         if (count - n >= n2)
 631                                 break;
 632                 }
 633         }
 634
 635         LIN_SDT_PROBE1(futex, futex_requeue, return, count);
 636         return (count);
 637 }
 638
 639 static int
 640 futex_wait(struct futex *f, struct waiting_proc *wp, struct timespec *ts,
 641     uint32_t bitset)
 642 {
 643         int error;
 644
 645         LIN_SDT_PROBE4(futex, futex_wait, entry, f, wp, ts, bitset);
 646
 647         if (bitset == 0) {
 648                 LIN_SDT_PROBE1(futex, futex_wait, return, EINVAL);
 649                 return (EINVAL);
 650         }
 651
 652         f->f_bitset = bitset;
 653         error = futex_sleep(f, wp, ts);
 654         if (error)
 655                 LIN_SDT_PROBE1(futex, futex_wait, sleep_error, error);
 656         if (error == EWOULDBLOCK)
 657                 error = ETIMEDOUT;
 658
 659         LIN_SDT_PROBE1(futex, futex_wait, return, error);
 660         return (error);
 661 }
 662
 663 static int
 664 futex_atomic_op(struct thread *td, int encoded_op, uint32_t *uaddr)
 665 {
 666         int op = (encoded_op >> 28) & 7;
 667         int cmp = (encoded_op >> 24) & 15;
 668         int oparg = (encoded_op << 8) >> 20;
 669         int cmparg = (encoded_op << 20) >> 20;
 670         int oldval = 0, ret;
 671
 672         LIN_SDT_PROBE3(futex, futex_atomic_op, entry, td, encoded_op, uaddr);
 673
 674         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
 675                 oparg = 1 << oparg;
 676
 677         LIN_SDT_PROBE4(futex, futex_atomic_op, decoded_op, op, cmp, oparg,
 678             cmparg);
 679
 680         /* XXX: Linux verifies access here and returns EFAULT */
 681         LIN_SDT_PROBE0(futex, futex_atomic_op, missing_access_check);
 682
 683         switch (op) {
 684         case FUTEX_OP_SET:
 685                 ret = futex_xchgl(oparg, uaddr, &oldval);
 686                 break;
 687         case FUTEX_OP_ADD:
 688                 ret = futex_addl(oparg, uaddr, &oldval);
 689                 break;
 690         case FUTEX_OP_OR:
 691                 ret = futex_orl(oparg, uaddr, &oldval);
 692                 break;
 693         case FUTEX_OP_ANDN:
 694                 ret = futex_andl(~oparg, uaddr, &oldval);
 695                 break;
 696         case FUTEX_OP_XOR:
 697                 ret = futex_xorl(oparg, uaddr, &oldval);
 698                 break;
 699         default:
 700                 LIN_SDT_PROBE1(futex, futex_atomic_op, unimplemented_op, op);
 701                 ret = -ENOSYS;
 702                 break;
 703         }
 704
 705         if (ret) {
 706                 LIN_SDT_PROBE1(futex, futex_atomic_op, return, ret);
 707                 return (ret);
 708         }
 709
 710         switch (cmp) {
 711         case FUTEX_OP_CMP_EQ:
 712                 ret = (oldval == cmparg);
 713                 break;
 714         case FUTEX_OP_CMP_NE:
 715                 ret = (oldval != cmparg);
 716                 break;
 717         case FUTEX_OP_CMP_LT:
 718                 ret = (oldval < cmparg);
 719                 break;
 720         case FUTEX_OP_CMP_GE:
 721                 ret = (oldval >= cmparg);
 722                 break;
 723         case FUTEX_OP_CMP_LE:
 724                 ret = (oldval <= cmparg);
 725                 break;
 726         case FUTEX_OP_CMP_GT:
 727                 ret = (oldval > cmparg);
 728                 break;
 729         default:
 730                 LIN_SDT_PROBE1(futex, futex_atomic_op, unimplemented_cmp, cmp);
 731                 ret = -ENOSYS;
 732         }
 733
 734         LIN_SDT_PROBE1(futex, futex_atomic_op, return, ret);
 735         return (ret);
 736 }
 737
 738 int
 739 linux_sys_futex(struct thread *td, struct linux_sys_futex_args *args)
 740 {
 741         int clockrt, nrwake, op_ret, ret;
 742         struct linux_pemuldata *pem;
 743         struct waiting_proc *wp;
 744         struct futex *f, *f2;
 745         struct timespec uts, *ts;
 746         int error, save;
 747         uint32_t flags, val;
 748
 749         LIN_SDT_PROBE2(futex, linux_sys_futex, entry, td, args);
 750
 751         if (args->op & LINUX_FUTEX_PRIVATE_FLAG) {
 752                 flags = 0;
 753                 args->op &= ~LINUX_FUTEX_PRIVATE_FLAG;
 754         } else
 755                 flags = FUTEX_SHARED;
 756
 757         /*
 758          * Currently support for switching between CLOCK_MONOTONIC and
 759          * CLOCK_REALTIME is not present. However Linux forbids the use of
 760          * FUTEX_CLOCK_REALTIME with any op except FUTEX_WAIT_BITSET and
 761          * FUTEX_WAIT_REQUEUE_PI.
 762          */
 763         clockrt = args->op & LINUX_FUTEX_CLOCK_REALTIME;
 764         args->op = args->op & ~LINUX_FUTEX_CLOCK_REALTIME;
 765         if (clockrt && args->op != LINUX_FUTEX_WAIT_BITSET &&
 766                 args->op != LINUX_FUTEX_WAIT_REQUEUE_PI) {
 767                 LIN_SDT_PROBE0(futex, linux_sys_futex,
 768                     unimplemented_clockswitch);
 769                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
 770                 return (ENOSYS);
 771         }
 772
 773         error = 0;
 774         f = f2 = NULL;
 775
 776         switch (args->op) {
 777         case LINUX_FUTEX_WAIT:
 778                 args->val3 = FUTEX_BITSET_MATCH_ANY;
 779                 /* FALLTHROUGH */
 780
 781         case LINUX_FUTEX_WAIT_BITSET:
 782                 LIN_SDT_PROBE3(futex, linux_sys_futex, debug_wait, args->uaddr,
 783                     args->val, args->val3);
 784                 LINUX_CTR3(sys_futex, "WAIT uaddr %p val 0x%x bitset 0x%x",
 785                     args->uaddr, args->val, args->val3);
 786
 787                 if (args->timeout != NULL) {
 788                         error = futex_copyin_timeout(args->op, args->timeout,
 789                             clockrt, &uts);
 790                         if (error) {
 791                                 LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error,
 792                                     error);
 793                                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 794                                 return (error);
 795                         }
 796                         ts = &uts;
 797                 } else
 798                         ts = NULL;
 799
 800 retry0:
 801                 error = futex_get(args->uaddr, &wp, &f,
 802                     flags | FUTEX_CREATE_WP);
 803                 if (error) {
 804                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 805                         return (error);
 806                 }
 807
 808                 error = copyin_nofault(args->uaddr, &val, sizeof(val));
 809                 if (error) {
 810                         futex_put(f, wp);
 811                         error = copyin(args->uaddr, &val, sizeof(val));
 812                         if (error == 0)
 813                                 goto retry0;
 814                         LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error,
 815                             error);
 816                         LINUX_CTR1(sys_futex, "WAIT copyin failed %d",
 817                             error);
 818                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 819                         return (error);
 820                 }
 821                 if (val != args->val) {
 822                         LIN_SDT_PROBE4(futex, linux_sys_futex,
 823                             debug_wait_value_neq, args->uaddr, args->val, val,
 824                             args->val3);
 825                         LINUX_CTR3(sys_futex,
 826                             "WAIT uaddr %p val 0x%x != uval 0x%x",
 827                             args->uaddr, args->val, val);
 828                         futex_put(f, wp);
 829
 830                         LIN_SDT_PROBE1(futex, linux_sys_futex, return,
 831                             EWOULDBLOCK);
 832                         return (EWOULDBLOCK);
 833                 }
 834
 835                 error = futex_wait(f, wp, ts, args->val3);
 836                 break;
 837
 838         case LINUX_FUTEX_WAKE:
 839                 args->val3 = FUTEX_BITSET_MATCH_ANY;
 840                 /* FALLTHROUGH */
 841
 842         case LINUX_FUTEX_WAKE_BITSET:
 843                 LIN_SDT_PROBE3(futex, linux_sys_futex, debug_wake, args->uaddr,
 844                     args->val, args->val3);
 845                 LINUX_CTR3(sys_futex, "WAKE uaddr %p nrwake 0x%x bitset 0x%x",
 846                     args->uaddr, args->val, args->val3);
 847
 848                 error = futex_get(args->uaddr, NULL, &f,
 849                     flags | FUTEX_DONTCREATE);
 850                 if (error) {
 851                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 852                         return (error);
 853                 }
 854
 855                 if (f == NULL) {
 856                         td->td_retval[0] = 0;
 857
 858                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 859                         return (error);
 860                 }
 861                 td->td_retval[0] = futex_wake(f, args->val, args->val3);
 862                 futex_put(f, NULL);
 863                 break;
 864
 865         case LINUX_FUTEX_CMP_REQUEUE:
 866                 LIN_SDT_PROBE5(futex, linux_sys_futex, debug_cmp_requeue,
 867                     args->uaddr, args->val, args->val3, args->uaddr2,
 868                     args->timeout);
 869                 LINUX_CTR5(sys_futex, "CMP_REQUEUE uaddr %p "
 870                     "nrwake 0x%x uval 0x%x uaddr2 %p nrequeue 0x%x",
 871                     args->uaddr, args->val, args->val3, args->uaddr2,
 872                     args->timeout);
 873
 874                 /*
 875                  * Linux allows this, we would not, it is an incorrect
 876                  * usage of declared ABI, so return EINVAL.
 877                  */
 878                 if (args->uaddr == args->uaddr2) {
 879                         LIN_SDT_PROBE0(futex, linux_sys_futex,
 880                             invalid_cmp_requeue_use);
 881                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, EINVAL);
 882                         return (EINVAL);
 883                 }
 884
 885 retry1:
 886                 error = futex_get(args->uaddr, NULL, &f, flags | FUTEX_DONTLOCK);
 887                 if (error) {
 888                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 889                         return (error);
 890                 }
 891
 892                 /*
 893                  * To avoid deadlocks return EINVAL if second futex
 894                  * exists at this time.
 895                  *
 896                  * Glibc fall back to FUTEX_WAKE in case of any error
 897                  * returned by FUTEX_CMP_REQUEUE.
 898                  */
 899                 error = futex_get(args->uaddr2, NULL, &f2,
 900                     flags | FUTEX_DONTEXISTS | FUTEX_DONTLOCK);
 901                 if (error) {
 902                         futex_put(f, NULL);
 903
 904                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 905                         return (error);
 906                 }
 907                 futex_lock(f);
 908                 futex_lock(f2);
 909                 error = copyin_nofault(args->uaddr, &val, sizeof(val));
 910                 if (error) {
 911                         futex_put(f2, NULL);
 912                         futex_put(f, NULL);
 913                         error = copyin(args->uaddr, &val, sizeof(val));
 914                         if (error == 0)
 915                                 goto retry1;
 916                         LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error,
 917                             error);
 918                         LINUX_CTR1(sys_futex, "CMP_REQUEUE copyin failed %d",
 919                             error);
 920                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 921                         return (error);
 922                 }
 923                 if (val != args->val3) {
 924                         LIN_SDT_PROBE2(futex, linux_sys_futex,
 925                             debug_cmp_requeue_value_neq, args->val, val);
 926                         LINUX_CTR2(sys_futex, "CMP_REQUEUE val 0x%x != uval 0x%x",
 927                             args->val, val);
 928                         futex_put(f2, NULL);
 929                         futex_put(f, NULL);
 930
 931                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, EAGAIN);
 932                         return (EAGAIN);
 933                 }
 934
 935                 nrwake = (int)(unsigned long)args->timeout;
 936                 td->td_retval[0] = futex_requeue(f, args->val, f2, nrwake);
 937                 futex_put(f2, NULL);
 938                 futex_put(f, NULL);
 939                 break;
 940
 941         case LINUX_FUTEX_WAKE_OP:
 942                 LIN_SDT_PROBE5(futex, linux_sys_futex, debug_wake_op,
 943                     args->uaddr, args->op, args->val, args->uaddr2, args->val3);
 944                 LINUX_CTR5(sys_futex, "WAKE_OP "
 945                     "uaddr %p nrwake 0x%x uaddr2 %p op 0x%x nrwake2 0x%x",
 946                     args->uaddr, args->val, args->uaddr2, args->val3,
 947                     args->timeout);
 948
 949                 if (args->uaddr == args->uaddr2) {
 950                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, EINVAL);
 951                         return (EINVAL);
 952                 }
 953
 954 retry2:
 955                 error = futex_get(args->uaddr, NULL, &f, flags | FUTEX_DONTLOCK);
 956                 if (error) {
 957                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 958                         return (error);
 959                 }
 960
 961                 error = futex_get(args->uaddr2, NULL, &f2, flags | FUTEX_DONTLOCK);
 962                 if (error) {
 963                         futex_put(f, NULL);
 964
 965                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 966                         return (error);
 967                 }
 968                 futex_lock(f);
 969                 futex_lock(f2);
 970
 971                 /*
 972                  * This function returns positive number as results and
 973                  * negative as errors
 974                  */
 975                 save = vm_fault_disable_pagefaults();
 976                 op_ret = futex_atomic_op(td, args->val3, args->uaddr2);
 977                 vm_fault_enable_pagefaults(save);
 978
 979                 LINUX_CTR2(sys_futex, "WAKE_OP atomic_op uaddr %p ret 0x%x",
 980                     args->uaddr, op_ret);
 981
 982                 if (op_ret < 0) {
 983                         if (f2 != NULL)
 984                                 futex_put(f2, NULL);
 985                         futex_put(f, NULL);
 986                         error = copyin(args->uaddr2, &val, sizeof(val));
 987                         if (error == 0)
 988                                 goto retry2;
 989                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 990                         return (error);
 991                 }
 992
 993                 ret = futex_wake(f, args->val, args->val3);
 994
 995                 if (op_ret > 0) {
 996                         op_ret = 0;
 997                         nrwake = (int)(unsigned long)args->timeout;
 998
 999                         if (f2 != NULL)
1000                                 op_ret += futex_wake(f2, nrwake, args->val3);
1001                         else
1002                                 op_ret += futex_wake(f, nrwake, args->val3);
1003                         ret += op_ret;
1004
1005                 }
1006                 if (f2 != NULL)
1007                         futex_put(f2, NULL);
1008                 futex_put(f, NULL);
1009                 td->td_retval[0] = ret;
1010                 break;
1011
1012         case LINUX_FUTEX_LOCK_PI:
1013                 /* not yet implemented */
1014                 pem = pem_find(td->td_proc);
1015                 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
1016                         linux_msg(td,
1017                                   "linux_sys_futex: "
1018                                   "unsupported futex_pi op\n");
1019                         pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
1020                         LIN_SDT_PROBE0(futex, linux_sys_futex,
1021                             unimplemented_lock_pi);
1022                 }
1023                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1024                 return (ENOSYS);
1025
1026         case LINUX_FUTEX_UNLOCK_PI:
1027                 /* not yet implemented */
1028                 pem = pem_find(td->td_proc);
1029                 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
1030                         linux_msg(td,
1031                                   "linux_sys_futex: "
1032                                   "unsupported futex_pi op\n");
1033                         pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
1034                         LIN_SDT_PROBE0(futex, linux_sys_futex,
1035                             unimplemented_unlock_pi);
1036                 }
1037                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1038                 return (ENOSYS);
1039
1040         case LINUX_FUTEX_TRYLOCK_PI:
1041                 /* not yet implemented */
1042                 pem = pem_find(td->td_proc);
1043                 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
1044                         linux_msg(td,
1045                                   "linux_sys_futex: "
1046                                   "unsupported futex_pi op\n");
1047                         pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
1048                         LIN_SDT_PROBE0(futex, linux_sys_futex,
1049                             unimplemented_trylock_pi);
1050                 }
1051                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1052                 return (ENOSYS);
1053
1054         case LINUX_FUTEX_REQUEUE:
1055                 /*
1056                  * Glibc does not use this operation since version 2.3.3,
1057                  * as it is racy and replaced by FUTEX_CMP_REQUEUE operation.
1058                  * Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when
1059                  * FUTEX_REQUEUE returned EINVAL.
1060                  */
1061                 pem = pem_find(td->td_proc);
1062                 if ((pem->flags & LINUX_XDEPR_REQUEUEOP) == 0) {
1063                         linux_msg(td,
1064                                   "linux_sys_futex: "
1065                                   "unsupported futex_requeue op\n");
1066                         pem->flags |= LINUX_XDEPR_REQUEUEOP;
1067                         LIN_SDT_PROBE0(futex, linux_sys_futex,
1068                             deprecated_requeue);
1069                 }
1070
1071                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, EINVAL);
1072                 return (EINVAL);
1073
1074         case LINUX_FUTEX_WAIT_REQUEUE_PI:
1075                 /* not yet implemented */
1076                 pem = pem_find(td->td_proc);
1077                 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
1078                         linux_msg(td,
1079                                   "linux_sys_futex: "
1080                                   "unsupported futex_pi op\n");
1081                         pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
1082                         LIN_SDT_PROBE0(futex, linux_sys_futex,
1083                             unimplemented_wait_requeue_pi);
1084                 }
1085                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1086                 return (ENOSYS);
1087
1088         case LINUX_FUTEX_CMP_REQUEUE_PI:
1089                 /* not yet implemented */
1090                 pem = pem_find(td->td_proc);
1091                 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
1092                         linux_msg(td,
1093                                   "linux_sys_futex: "
1094                                   "unsupported futex_pi op\n");
1095                         pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
1096                         LIN_SDT_PROBE0(futex, linux_sys_futex,
1097                             unimplemented_cmp_requeue_pi);
1098                 }
1099                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1100                 return (ENOSYS);
1101
1102         default:
1103                 linux_msg(td,
1104                           "linux_sys_futex: unknown op %d\n", args->op);
1105                 LIN_SDT_PROBE1(futex, linux_sys_futex, unknown_operation,
1106                     args->op);
1107                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1108                 return (ENOSYS);
1109         }
1110
1111         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
1112         return (error);
1113 }
1114
1115 int
1116 linux_set_robust_list(struct thread *td, struct linux_set_robust_list_args *args)
1117 {
1118         struct linux_emuldata *em;
1119
1120         LIN_SDT_PROBE2(futex, linux_set_robust_list, entry, td, args);
1121
1122         if (args->len != sizeof(struct linux_robust_list_head)) {
1123                 LIN_SDT_PROBE0(futex, linux_set_robust_list, size_error);
1124                 LIN_SDT_PROBE1(futex, linux_set_robust_list, return, EINVAL);
1125                 return (EINVAL);
1126         }
1127
1128         em = em_find(td);
1129         em->robust_futexes = args->head;
1130
1131         LIN_SDT_PROBE1(futex, linux_set_robust_list, return, 0);
1132         return (0);
1133 }
1134
1135 int
1136 linux_get_robust_list(struct thread *td, struct linux_get_robust_list_args *args)
1137 {
1138         struct linux_emuldata *em;
1139         struct linux_robust_list_head *head;
1140         l_size_t len = sizeof(struct linux_robust_list_head);
1141         struct thread *td2;
1142         int error = 0;
1143
1144         LIN_SDT_PROBE2(futex, linux_get_robust_list, entry, td, args);
1145
1146         if (!args->pid) {
1147                 em = em_find(td);
1148                 KASSERT(em != NULL, ("get_robust_list: emuldata notfound.\n"));
1149                 head = em->robust_futexes;
1150         } else {
1151                 td2 = tdfind(args->pid, -1);
1152                 if (td2 == NULL) {
1153                         LIN_SDT_PROBE1(futex, linux_get_robust_list, return,
1154                             ESRCH);
1155                         return (ESRCH);
1156                 }
1157                 if (SV_PROC_ABI(td2->td_proc) != SV_ABI_LINUX) {
1158                         LIN_SDT_PROBE1(futex, linux_get_robust_list, return,
1159                             EPERM);
1160                         PROC_UNLOCK(td2->td_proc);
1161                         return (EPERM);
1162                 }
1163
1164                 em = em_find(td2);
1165                 KASSERT(em != NULL, ("get_robust_list: emuldata notfound.\n"));
1166                 /* XXX: ptrace? */
1167                 if (priv_check(td, PRIV_CRED_SETUID) ||
1168                     priv_check(td, PRIV_CRED_SETEUID) ||
1169                     p_candebug(td, td2->td_proc)) {
1170                         PROC_UNLOCK(td2->td_proc);
1171
1172                         LIN_SDT_PROBE1(futex, linux_get_robust_list, return,
1173                             EPERM);
1174                         return (EPERM);
1175                 }
1176                 head = em->robust_futexes;
1177
1178                 PROC_UNLOCK(td2->td_proc);
1179         }
1180
1181         error = copyout(&len, args->len, sizeof(l_size_t));
1182         if (error) {
1183                 LIN_SDT_PROBE1(futex, linux_get_robust_list, copyout_error,
1184                     error);
1185                 LIN_SDT_PROBE1(futex, linux_get_robust_list, return, EFAULT);
1186                 return (EFAULT);
1187         }
1188
1189         error = copyout(&head, args->head, sizeof(head));
1190         if (error) {
1191                 LIN_SDT_PROBE1(futex, linux_get_robust_list, copyout_error,
1192                     error);
1193         }
1194
1195         LIN_SDT_PROBE1(futex, linux_get_robust_list, return, error);
1196         return (error);
1197 }
1198
1199 static int
1200 handle_futex_death(struct linux_emuldata *em, uint32_t *uaddr,
1201     unsigned int pi)
1202 {
1203         uint32_t uval, nval, mval;
1204         struct futex *f;
1205         int error;
1206
1207         LIN_SDT_PROBE3(futex, handle_futex_death, entry, em, uaddr, pi);
1208
1209 retry:
1210         error = copyin(uaddr, &uval, 4);
1211         if (error) {
1212                 LIN_SDT_PROBE1(futex, handle_futex_death, copyin_error, error);
1213                 LIN_SDT_PROBE1(futex, handle_futex_death, return, EFAULT);
1214                 return (EFAULT);
1215         }
1216         if ((uval & FUTEX_TID_MASK) == em->em_tid) {
1217                 mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED;
1218                 nval = casuword32(uaddr, uval, mval);
1219
1220                 if (nval == -1) {
1221                         LIN_SDT_PROBE1(futex, handle_futex_death, return,
1222                             EFAULT);
1223                         return (EFAULT);
1224                 }
1225
1226                 if (nval != uval)
1227                         goto retry;
1228
1229                 if (!pi && (uval & FUTEX_WAITERS)) {
1230                         error = futex_get(uaddr, NULL, &f,
1231                             FUTEX_DONTCREATE | FUTEX_SHARED);
1232                         if (error) {
1233                                 LIN_SDT_PROBE1(futex, handle_futex_death,
1234                                     return, error);
1235                                 return (error);
1236                         }
1237                         if (f != NULL) {
1238                                 futex_wake(f, 1, FUTEX_BITSET_MATCH_ANY);
1239                                 futex_put(f, NULL);
1240                         }
1241                 }
1242         }
1243
1244         LIN_SDT_PROBE1(futex, handle_futex_death, return, 0);
1245         return (0);
1246 }
1247
1248 static int
1249 fetch_robust_entry(struct linux_robust_list **entry,
1250     struct linux_robust_list **head, unsigned int *pi)
1251 {
1252         l_ulong uentry;
1253         int error;
1254
1255         LIN_SDT_PROBE3(futex, fetch_robust_entry, entry, entry, head, pi);
1256
1257         error = copyin((const void *)head, &uentry, sizeof(l_ulong));
1258         if (error) {
1259                 LIN_SDT_PROBE1(futex, fetch_robust_entry, copyin_error, error);
1260                 LIN_SDT_PROBE1(futex, fetch_robust_entry, return, EFAULT);
1261                 return (EFAULT);
1262         }
1263
1264         *entry = (void *)(uentry & ~1UL);
1265         *pi = uentry & 1;
1266
1267         LIN_SDT_PROBE1(futex, fetch_robust_entry, return, 0);
1268         return (0);
1269 }
1270
1271 /* This walks the list of robust futexes releasing them. */
1272 void
1273 release_futexes(struct thread *td, struct linux_emuldata *em)
1274 {
1275         struct linux_robust_list_head *head = NULL;
1276         struct linux_robust_list *entry, *next_entry, *pending;
1277         unsigned int limit = 2048, pi, next_pi, pip;
1278         l_long futex_offset;
1279         int rc, error;
1280
1281         LIN_SDT_PROBE2(futex, release_futexes, entry, td, em);
1282
1283         head = em->robust_futexes;
1284
1285         if (head == NULL) {
1286                 LIN_SDT_PROBE0(futex, release_futexes, return);
1287                 return;
1288         }
1289
1290         if (fetch_robust_entry(&entry, PTRIN(&head->list.next), &pi)) {
1291                 LIN_SDT_PROBE0(futex, release_futexes, return);
1292                 return;
1293         }
1294
1295         error = copyin(&head->futex_offset, &futex_offset,
1296             sizeof(futex_offset));
1297         if (error) {
1298                 LIN_SDT_PROBE1(futex, release_futexes, copyin_error, error);
1299                 LIN_SDT_PROBE0(futex, release_futexes, return);
1300                 return;
1301         }
1302
1303         if (fetch_robust_entry(&pending, PTRIN(&head->pending_list), &pip)) {
1304                 LIN_SDT_PROBE0(futex, release_futexes, return);
1305                 return;
1306         }
1307
1308         while (entry != &head->list) {
1309                 rc = fetch_robust_entry(&next_entry, PTRIN(&entry->next), &next_pi);
1310
1311                 if (entry != pending)
1312                         if (handle_futex_death(em,
1313                             (uint32_t *)((caddr_t)entry + futex_offset), pi)) {
1314                                 LIN_SDT_PROBE0(futex, release_futexes, return);
1315                                 return;
1316                         }
1317                 if (rc) {
1318                         LIN_SDT_PROBE0(futex, release_futexes, return);
1319                         return;
1320                 }
1321
1322                 entry = next_entry;
1323                 pi = next_pi;
1324
1325                 if (!--limit)
1326                         break;
1327
1328                 sched_relinquish(curthread);
1329         }
1330
1331         if (pending)
1332                 handle_futex_death(em, (uint32_t *)((caddr_t)pending + futex_offset), pip);
1333
1334         LIN_SDT_PROBE0(futex, release_futexes, return);
1335 }