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 /* support.s */
 277 int futex_xchgl(int oparg, uint32_t *uaddr, int *oldval);
 278 int futex_addl(int oparg, uint32_t *uaddr, int *oldval);
 279 int futex_orl(int oparg, uint32_t *uaddr, int *oldval);
 280 int futex_andl(int oparg, uint32_t *uaddr, int *oldval);
 281 int futex_xorl(int oparg, uint32_t *uaddr, int *oldval);
 282
 283
 284 static int
 285 futex_copyin_timeout(int op, struct l_timespec *luts, int clockrt,
 286     struct timespec *ts)
 287 {
 288         struct l_timespec lts;
 289         struct timespec kts;
 290         int error;
 291
 292         error = copyin(luts, &lts, sizeof(lts));
 293         if (error)
 294                 return (error);
 295
 296         error = linux_to_native_timespec(ts, &lts);
 297         if (error)
 298                 return (error);
 299         if (clockrt) {
 300                 nanotime(&kts);
 301                 timespecsub(ts, &kts);
 302         } else if (op == LINUX_FUTEX_WAIT_BITSET) {
 303                 nanouptime(&kts);
 304                 timespecsub(ts, &kts);
 305         }
 306         return (error);
 307 }
 308
 309 static void
 310 futex_put(struct futex *f, struct waiting_proc *wp)
 311 {
 312         LIN_SDT_PROBE2(futex, futex_put, entry, f, wp);
 313
 314         if (wp != NULL) {
 315                 if ((wp->wp_flags & FUTEX_WP_REMOVED) == 0)
 316                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
 317                 free(wp, M_FUTEX_WP);
 318         }
 319
 320         FUTEXES_LOCK;
 321         if (--f->f_refcount == 0) {
 322                 LIST_REMOVE(f, f_list);
 323                 FUTEXES_UNLOCK;
 324                 if (FUTEX_LOCKED(f))
 325                         futex_unlock(f);
 326
 327                 LIN_SDT_PROBE3(futex, futex_put, destroy, f->f_uaddr,
 328                     f->f_refcount, f->f_key.shared);
 329                 LINUX_CTR3(sys_futex, "futex_put destroy uaddr %p ref %d "
 330                     "shared %d", f->f_uaddr, f->f_refcount, f->f_key.shared);
 331                 umtx_key_release(&f->f_key);
 332                 FUTEX_DESTROY(f);
 333                 free(f, M_FUTEX);
 334
 335                 LIN_SDT_PROBE0(futex, futex_put, return);
 336                 return;
 337         }
 338
 339         LIN_SDT_PROBE3(futex, futex_put, unlock, f->f_uaddr, f->f_refcount,
 340             f->f_key.shared);
 341         LINUX_CTR3(sys_futex, "futex_put uaddr %p ref %d shared %d",
 342             f->f_uaddr, f->f_refcount, f->f_key.shared);
 343         FUTEXES_UNLOCK;
 344         if (FUTEX_LOCKED(f))
 345                 futex_unlock(f);
 346
 347         LIN_SDT_PROBE0(futex, futex_put, return);
 348 }
 349
 350 static int
 351 futex_get0(uint32_t *uaddr, struct futex **newf, uint32_t flags)
 352 {
 353         struct futex *f, *tmpf;
 354         struct umtx_key key;
 355         int error;
 356
 357         LIN_SDT_PROBE3(futex, futex_get0, entry, uaddr, newf, flags);
 358
 359         *newf = tmpf = NULL;
 360
 361         error = umtx_key_get(uaddr, TYPE_FUTEX, (flags & FUTEX_SHARED) ?
 362             AUTO_SHARE : THREAD_SHARE, &key);
 363         if (error) {
 364                 LIN_SDT_PROBE1(futex, futex_get0, umtx_key_get_error, error);
 365                 LIN_SDT_PROBE1(futex, futex_get0, return, error);
 366                 return (error);
 367         }
 368 retry:
 369         FUTEXES_LOCK;
 370         LIST_FOREACH(f, &futex_list, f_list) {
 371                 if (umtx_key_match(&f->f_key, &key)) {
 372                         if (tmpf != NULL) {
 373                                 if (FUTEX_LOCKED(tmpf))
 374                                         futex_unlock(tmpf);
 375                                 FUTEX_DESTROY(tmpf);
 376                                 free(tmpf, M_FUTEX);
 377                         }
 378                         if (flags & FUTEX_DONTEXISTS) {
 379                                 FUTEXES_UNLOCK;
 380                                 umtx_key_release(&key);
 381
 382                                 LIN_SDT_PROBE1(futex, futex_get0, return,
 383                                     EINVAL);
 384                                 return (EINVAL);
 385                         }
 386
 387                         /*
 388                          * Increment refcount of the found futex to
 389                          * prevent it from deallocation before FUTEX_LOCK()
 390                          */
 391                         ++f->f_refcount;
 392                         FUTEXES_UNLOCK;
 393                         umtx_key_release(&key);
 394
 395                         if ((flags & FUTEX_DONTLOCK) == 0)
 396                                 futex_lock(f);
 397                         *newf = f;
 398                         LIN_SDT_PROBE3(futex, futex_get0, shared, uaddr,
 399                             f->f_refcount, f->f_key.shared);
 400                         LINUX_CTR3(sys_futex, "futex_get uaddr %p ref %d shared %d",
 401                             uaddr, f->f_refcount, f->f_key.shared);
 402
 403                         LIN_SDT_PROBE1(futex, futex_get0, return, 0);
 404                         return (0);
 405                 }
 406         }
 407
 408         if (flags & FUTEX_DONTCREATE) {
 409                 FUTEXES_UNLOCK;
 410                 umtx_key_release(&key);
 411                 LIN_SDT_PROBE1(futex, futex_get0, null, uaddr);
 412                 LINUX_CTR1(sys_futex, "futex_get uaddr %p null", uaddr);
 413
 414                 LIN_SDT_PROBE1(futex, futex_get0, return, 0);
 415                 return (0);
 416         }
 417
 418         if (tmpf == NULL) {
 419                 FUTEXES_UNLOCK;
 420                 tmpf = malloc(sizeof(*tmpf), M_FUTEX, M_WAITOK | M_ZERO);
 421                 tmpf->f_uaddr = uaddr;
 422                 tmpf->f_key = key;
 423                 tmpf->f_refcount = 1;
 424                 tmpf->f_bitset = FUTEX_BITSET_MATCH_ANY;
 425                 FUTEX_INIT(tmpf);
 426                 TAILQ_INIT(&tmpf->f_waiting_proc);
 427
 428                 /*
 429                  * Lock the new futex before an insert into the futex_list
 430                  * to prevent futex usage by other.
 431                  */
 432                 if ((flags & FUTEX_DONTLOCK) == 0)
 433                         futex_lock(tmpf);
 434                 goto retry;
 435         }
 436
 437         LIST_INSERT_HEAD(&futex_list, tmpf, f_list);
 438         FUTEXES_UNLOCK;
 439
 440         LIN_SDT_PROBE3(futex, futex_get0, new, uaddr, tmpf->f_refcount,
 441             tmpf->f_key.shared);
 442         LINUX_CTR3(sys_futex, "futex_get uaddr %p ref %d shared %d new",
 443             uaddr, tmpf->f_refcount, tmpf->f_key.shared);
 444         *newf = tmpf;
 445
 446         LIN_SDT_PROBE1(futex, futex_get0, return, 0);
 447         return (0);
 448 }
 449
 450 static int
 451 futex_get(uint32_t *uaddr, struct waiting_proc **wp, struct futex **f,
 452     uint32_t flags)
 453 {
 454         int error;
 455
 456         LIN_SDT_PROBE3(futex, futex_get, entry, uaddr, wp, f);
 457
 458         if (flags & FUTEX_CREATE_WP) {
 459                 *wp = malloc(sizeof(struct waiting_proc), M_FUTEX_WP, M_WAITOK);
 460                 (*wp)->wp_flags = 0;
 461         }
 462         error = futex_get0(uaddr, f, flags);
 463         if (error) {
 464                 LIN_SDT_PROBE0(futex, futex_get, error);
 465
 466                 if (flags & FUTEX_CREATE_WP)
 467                         free(*wp, M_FUTEX_WP);
 468
 469                 LIN_SDT_PROBE1(futex, futex_get, return, error);
 470                 return (error);
 471         }
 472         if (flags & FUTEX_CREATE_WP) {
 473                 TAILQ_INSERT_HEAD(&(*f)->f_waiting_proc, *wp, wp_list);
 474                 (*wp)->wp_futex = *f;
 475         }
 476
 477         LIN_SDT_PROBE1(futex, futex_get, return, error);
 478         return (error);
 479 }
 480
 481 static inline void
 482 futex_lock(struct futex *f)
 483 {
 484
 485         LINUX_CTR3(sys_futex, "futex_lock uaddr %p ref %d shared %d",
 486             f->f_uaddr, f->f_refcount, f->f_key.shared);
 487         FUTEX_ASSERT_UNLOCKED(f);
 488         FUTEX_LOCK(f);
 489 }
 490
 491 static inline void
 492 futex_unlock(struct futex *f)
 493 {
 494
 495         LINUX_CTR3(sys_futex, "futex_unlock uaddr %p ref %d shared %d",
 496             f->f_uaddr, f->f_refcount, f->f_key.shared);
 497         FUTEX_ASSERT_LOCKED(f);
 498         FUTEX_UNLOCK(f);
 499 }
 500
 501 static int
 502 futex_sleep(struct futex *f, struct waiting_proc *wp, struct timespec *ts)
 503 {
 504         struct timespec uts;
 505         sbintime_t sbt, prec, tmp;
 506         time_t over;
 507         int error;
 508
 509         FUTEX_ASSERT_LOCKED(f);
 510         if (ts != NULL) {
 511                 uts = *ts;
 512                 if (uts.tv_sec > INT32_MAX / 2) {
 513                         over = uts.tv_sec - INT32_MAX / 2;
 514                         uts.tv_sec -= over;
 515                 }
 516                 tmp = tstosbt(uts);
 517                 if (TIMESEL(&sbt, tmp))
 518                         sbt += tc_tick_sbt;
 519                 sbt += tmp;
 520                 prec = tmp;
 521                 prec >>= tc_precexp;
 522         } else {
 523                 sbt = 0;
 524                 prec = 0;
 525         }
 526         LIN_SDT_PROBE3(futex, futex_sleep, entry, f, wp, sbt);
 527         LINUX_CTR4(sys_futex, "futex_sleep enter uaddr %p wp %p timo %ld ref %d",
 528             f->f_uaddr, wp, sbt, f->f_refcount);
 529
 530         error = msleep_sbt(wp, &f->f_lck, PCATCH, "futex", sbt, prec, C_ABSOLUTE);
 531         if (wp->wp_flags & FUTEX_WP_REQUEUED) {
 532                 KASSERT(f != wp->wp_futex, ("futex != wp_futex"));
 533
 534                 if (error) {
 535                         LIN_SDT_PROBE5(futex, futex_sleep, requeue_error, error,
 536                             f->f_uaddr, wp, wp->wp_futex->f_uaddr,
 537                             wp->wp_futex->f_refcount);
 538                 }
 539
 540                 LINUX_CTR5(sys_futex, "futex_sleep out error %d uaddr %p wp"
 541                     " %p requeued uaddr %p ref %d",
 542                     error, f->f_uaddr, wp, wp->wp_futex->f_uaddr,
 543                     wp->wp_futex->f_refcount);
 544                 futex_put(f, NULL);
 545                 f = wp->wp_futex;
 546                 futex_lock(f);
 547         } else {
 548                 if (error) {
 549                         LIN_SDT_PROBE3(futex, futex_sleep, sleep_error, error,
 550                             f->f_uaddr, wp);
 551                 }
 552                 LINUX_CTR3(sys_futex, "futex_sleep out error %d uaddr %p wp %p",
 553                     error, f->f_uaddr, wp);
 554         }
 555
 556         futex_put(f, wp);
 557
 558         LIN_SDT_PROBE1(futex, futex_sleep, return, error);
 559         return (error);
 560 }
 561
 562 static int
 563 futex_wake(struct futex *f, int n, uint32_t bitset)
 564 {
 565         struct waiting_proc *wp, *wpt;
 566         int count = 0;
 567
 568         LIN_SDT_PROBE3(futex, futex_wake, entry, f, n, bitset);
 569
 570         if (bitset == 0) {
 571                 LIN_SDT_PROBE1(futex, futex_wake, return, EINVAL);
 572                 return (EINVAL);
 573         }
 574
 575         FUTEX_ASSERT_LOCKED(f);
 576         TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) {
 577                 LIN_SDT_PROBE3(futex, futex_wake, iterate, f->f_uaddr, wp,
 578                     f->f_refcount);
 579                 LINUX_CTR3(sys_futex, "futex_wake uaddr %p wp %p ref %d",
 580                     f->f_uaddr, wp, f->f_refcount);
 581                 /*
 582                  * Unless we find a matching bit in
 583                  * the bitset, continue searching.
 584                  */
 585                 if (!(wp->wp_futex->f_bitset & bitset))
 586                         continue;
 587
 588                 wp->wp_flags |= FUTEX_WP_REMOVED;
 589                 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
 590                 LIN_SDT_PROBE1(futex, futex_wake, wakeup, wp);
 591                 wakeup_one(wp);
 592                 if (++count == n)
 593                         break;
 594         }
 595
 596         LIN_SDT_PROBE1(futex, futex_wake, return, count);
 597         return (count);
 598 }
 599
 600 static int
 601 futex_requeue(struct futex *f, int n, struct futex *f2, int n2)
 602 {
 603         struct waiting_proc *wp, *wpt;
 604         int count = 0;
 605
 606         LIN_SDT_PROBE4(futex, futex_requeue, entry, f, n, f2, n2);
 607
 608         FUTEX_ASSERT_LOCKED(f);
 609         FUTEX_ASSERT_LOCKED(f2);
 610
 611         TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) {
 612                 if (++count <= n) {
 613                         LINUX_CTR2(sys_futex, "futex_req_wake uaddr %p wp %p",
 614                             f->f_uaddr, wp);
 615                         wp->wp_flags |= FUTEX_WP_REMOVED;
 616                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
 617                         LIN_SDT_PROBE1(futex, futex_requeue, wakeup, wp);
 618                         wakeup_one(wp);
 619                 } else {
 620                         LIN_SDT_PROBE3(futex, futex_requeue, requeue,
 621                             f->f_uaddr, wp, f2->f_uaddr);
 622                         LINUX_CTR3(sys_futex, "futex_requeue uaddr %p wp %p to %p",
 623                             f->f_uaddr, wp, f2->f_uaddr);
 624                         wp->wp_flags |= FUTEX_WP_REQUEUED;
 625                         /* Move wp to wp_list of f2 futex */
 626                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
 627                         TAILQ_INSERT_HEAD(&f2->f_waiting_proc, wp, wp_list);
 628
 629                         /*
 630                          * Thread which sleeps on wp after waking should
 631                          * acquire f2 lock, so increment refcount of f2 to
 632                          * prevent it from premature deallocation.
 633                          */
 634                         wp->wp_futex = f2;
 635                         FUTEXES_LOCK;
 636                         ++f2->f_refcount;
 637                         FUTEXES_UNLOCK;
 638                         if (count - n >= n2)
 639                                 break;
 640                 }
 641         }
 642
 643         LIN_SDT_PROBE1(futex, futex_requeue, return, count);
 644         return (count);
 645 }
 646
 647 static int
 648 futex_wait(struct futex *f, struct waiting_proc *wp, struct timespec *ts,
 649     uint32_t bitset)
 650 {
 651         int error;
 652
 653         LIN_SDT_PROBE4(futex, futex_wait, entry, f, wp, ts, bitset);
 654
 655         if (bitset == 0) {
 656                 LIN_SDT_PROBE1(futex, futex_wait, return, EINVAL);
 657                 return (EINVAL);
 658         }
 659
 660         f->f_bitset = bitset;
 661         error = futex_sleep(f, wp, ts);
 662         if (error)
 663                 LIN_SDT_PROBE1(futex, futex_wait, sleep_error, error);
 664         if (error == EWOULDBLOCK)
 665                 error = ETIMEDOUT;
 666
 667         LIN_SDT_PROBE1(futex, futex_wait, return, error);
 668         return (error);
 669 }
 670
 671 static int
 672 futex_atomic_op(struct thread *td, int encoded_op, uint32_t *uaddr)
 673 {
 674         int op = (encoded_op >> 28) & 7;
 675         int cmp = (encoded_op >> 24) & 15;
 676         int oparg = (encoded_op << 8) >> 20;
 677         int cmparg = (encoded_op << 20) >> 20;
 678         int oldval = 0, ret;
 679
 680         LIN_SDT_PROBE3(futex, futex_atomic_op, entry, td, encoded_op, uaddr);
 681
 682         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
 683                 oparg = 1 << oparg;
 684
 685         LIN_SDT_PROBE4(futex, futex_atomic_op, decoded_op, op, cmp, oparg,
 686             cmparg);
 687
 688         /* XXX: Linux verifies access here and returns EFAULT */
 689         LIN_SDT_PROBE0(futex, futex_atomic_op, missing_access_check);
 690
 691         switch (op) {
 692         case FUTEX_OP_SET:
 693                 ret = futex_xchgl(oparg, uaddr, &oldval);
 694                 break;
 695         case FUTEX_OP_ADD:
 696                 ret = futex_addl(oparg, uaddr, &oldval);
 697                 break;
 698         case FUTEX_OP_OR:
 699                 ret = futex_orl(oparg, uaddr, &oldval);
 700                 break;
 701         case FUTEX_OP_ANDN:
 702                 ret = futex_andl(~oparg, uaddr, &oldval);
 703                 break;
 704         case FUTEX_OP_XOR:
 705                 ret = futex_xorl(oparg, uaddr, &oldval);
 706                 break;
 707         default:
 708                 LIN_SDT_PROBE1(futex, futex_atomic_op, unimplemented_op, op);
 709                 ret = -ENOSYS;
 710                 break;
 711         }
 712
 713         if (ret) {
 714                 LIN_SDT_PROBE1(futex, futex_atomic_op, return, ret);
 715                 return (ret);
 716         }
 717
 718         switch (cmp) {
 719         case FUTEX_OP_CMP_EQ:
 720                 ret = (oldval == cmparg);
 721                 break;
 722         case FUTEX_OP_CMP_NE:
 723                 ret = (oldval != cmparg);
 724                 break;
 725         case FUTEX_OP_CMP_LT:
 726                 ret = (oldval < cmparg);
 727                 break;
 728         case FUTEX_OP_CMP_GE:
 729                 ret = (oldval >= cmparg);
 730                 break;
 731         case FUTEX_OP_CMP_LE:
 732                 ret = (oldval <= cmparg);
 733                 break;
 734         case FUTEX_OP_CMP_GT:
 735                 ret = (oldval > cmparg);
 736                 break;
 737         default:
 738                 LIN_SDT_PROBE1(futex, futex_atomic_op, unimplemented_cmp, cmp);
 739                 ret = -ENOSYS;
 740         }
 741
 742         LIN_SDT_PROBE1(futex, futex_atomic_op, return, ret);
 743         return (ret);
 744 }
 745
 746 int
 747 linux_sys_futex(struct thread *td, struct linux_sys_futex_args *args)
 748 {
 749         int clockrt, nrwake, op_ret, ret;
 750         struct linux_pemuldata *pem;
 751         struct waiting_proc *wp;
 752         struct futex *f, *f2;
 753         struct timespec uts, *ts;
 754         int error, save;
 755         uint32_t flags, val;
 756
 757         LIN_SDT_PROBE2(futex, linux_sys_futex, entry, td, args);
 758
 759         if (args->op & LINUX_FUTEX_PRIVATE_FLAG) {
 760                 flags = 0;
 761                 args->op &= ~LINUX_FUTEX_PRIVATE_FLAG;
 762         } else
 763                 flags = FUTEX_SHARED;
 764
 765         /*
 766          * Currently support for switching between CLOCK_MONOTONIC and
 767          * CLOCK_REALTIME is not present. However Linux forbids the use of
 768          * FUTEX_CLOCK_REALTIME with any op except FUTEX_WAIT_BITSET and
 769          * FUTEX_WAIT_REQUEUE_PI.
 770          */
 771         clockrt = args->op & LINUX_FUTEX_CLOCK_REALTIME;
 772         args->op = args->op & ~LINUX_FUTEX_CLOCK_REALTIME;
 773         if (clockrt && args->op != LINUX_FUTEX_WAIT_BITSET &&
 774                 args->op != LINUX_FUTEX_WAIT_REQUEUE_PI) {
 775                 LIN_SDT_PROBE0(futex, linux_sys_futex,
 776                     unimplemented_clockswitch);
 777                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
 778                 return (ENOSYS);
 779         }
 780
 781         error = 0;
 782         f = f2 = NULL;
 783
 784         switch (args->op) {
 785         case LINUX_FUTEX_WAIT:
 786                 args->val3 = FUTEX_BITSET_MATCH_ANY;
 787                 /* FALLTHROUGH */
 788
 789         case LINUX_FUTEX_WAIT_BITSET:
 790                 LIN_SDT_PROBE3(futex, linux_sys_futex, debug_wait, args->uaddr,
 791                     args->val, args->val3);
 792                 LINUX_CTR3(sys_futex, "WAIT uaddr %p val 0x%x bitset 0x%x",
 793                     args->uaddr, args->val, args->val3);
 794
 795                 if (args->timeout != NULL) {
 796                         error = futex_copyin_timeout(args->op, args->timeout,
 797                             clockrt, &uts);
 798                         if (error) {
 799                                 LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error,
 800                                     error);
 801                                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 802                                 return (error);
 803                         }
 804                         ts = &uts;
 805                 } else
 806                         ts = NULL;
 807
 808 retry0:
 809                 error = futex_get(args->uaddr, &wp, &f,
 810                     flags | FUTEX_CREATE_WP);
 811                 if (error) {
 812                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 813                         return (error);
 814                 }
 815
 816                 error = copyin_nofault(args->uaddr, &val, sizeof(val));
 817                 if (error) {
 818                         futex_put(f, wp);
 819                         error = copyin(args->uaddr, &val, sizeof(val));
 820                         if (error == 0)
 821                                 goto retry0;
 822                         LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error,
 823                             error);
 824                         LINUX_CTR1(sys_futex, "WAIT copyin failed %d",
 825                             error);
 826                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 827                         return (error);
 828                 }
 829                 if (val != args->val) {
 830                         LIN_SDT_PROBE4(futex, linux_sys_futex,
 831                             debug_wait_value_neq, args->uaddr, args->val, val,
 832                             args->val3);
 833                         LINUX_CTR3(sys_futex,
 834                             "WAIT uaddr %p val 0x%x != uval 0x%x",
 835                             args->uaddr, args->val, val);
 836                         futex_put(f, wp);
 837
 838                         LIN_SDT_PROBE1(futex, linux_sys_futex, return,
 839                             EWOULDBLOCK);
 840                         return (EWOULDBLOCK);
 841                 }
 842
 843                 error = futex_wait(f, wp, ts, args->val3);
 844                 break;
 845
 846         case LINUX_FUTEX_WAKE:
 847                 args->val3 = FUTEX_BITSET_MATCH_ANY;
 848                 /* FALLTHROUGH */
 849
 850         case LINUX_FUTEX_WAKE_BITSET:
 851                 LIN_SDT_PROBE3(futex, linux_sys_futex, debug_wake, args->uaddr,
 852                     args->val, args->val3);
 853                 LINUX_CTR3(sys_futex, "WAKE uaddr %p nrwake 0x%x bitset 0x%x",
 854                     args->uaddr, args->val, args->val3);
 855
 856                 error = futex_get(args->uaddr, NULL, &f,
 857                     flags | FUTEX_DONTCREATE);
 858                 if (error) {
 859                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 860                         return (error);
 861                 }
 862
 863                 if (f == NULL) {
 864                         td->td_retval[0] = 0;
 865
 866                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 867                         return (error);
 868                 }
 869                 td->td_retval[0] = futex_wake(f, args->val, args->val3);
 870                 futex_put(f, NULL);
 871                 break;
 872
 873         case LINUX_FUTEX_CMP_REQUEUE:
 874                 LIN_SDT_PROBE5(futex, linux_sys_futex, debug_cmp_requeue,
 875                     args->uaddr, args->val, args->val3, args->uaddr2,
 876                     args->timeout);
 877                 LINUX_CTR5(sys_futex, "CMP_REQUEUE uaddr %p "
 878                     "nrwake 0x%x uval 0x%x uaddr2 %p nrequeue 0x%x",
 879                     args->uaddr, args->val, args->val3, args->uaddr2,
 880                     args->timeout);
 881
 882                 /*
 883                  * Linux allows this, we would not, it is an incorrect
 884                  * usage of declared ABI, so return EINVAL.
 885                  */
 886                 if (args->uaddr == args->uaddr2) {
 887                         LIN_SDT_PROBE0(futex, linux_sys_futex,
 888                             invalid_cmp_requeue_use);
 889                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, EINVAL);
 890                         return (EINVAL);
 891                 }
 892
 893 retry1:
 894                 error = futex_get(args->uaddr, NULL, &f, flags | FUTEX_DONTLOCK);
 895                 if (error) {
 896                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 897                         return (error);
 898                 }
 899
 900                 /*
 901                  * To avoid deadlocks return EINVAL if second futex
 902                  * exists at this time.
 903                  *
 904                  * Glibc fall back to FUTEX_WAKE in case of any error
 905                  * returned by FUTEX_CMP_REQUEUE.
 906                  */
 907                 error = futex_get(args->uaddr2, NULL, &f2,
 908                     flags | FUTEX_DONTEXISTS | FUTEX_DONTLOCK);
 909                 if (error) {
 910                         futex_put(f, NULL);
 911
 912                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 913                         return (error);
 914                 }
 915                 futex_lock(f);
 916                 futex_lock(f2);
 917                 error = copyin_nofault(args->uaddr, &val, sizeof(val));
 918                 if (error) {
 919                         futex_put(f2, NULL);
 920                         futex_put(f, NULL);
 921                         error = copyin(args->uaddr, &val, sizeof(val));
 922                         if (error == 0)
 923                                 goto retry1;
 924                         LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error,
 925                             error);
 926                         LINUX_CTR1(sys_futex, "CMP_REQUEUE copyin failed %d",
 927                             error);
 928                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 929                         return (error);
 930                 }
 931                 if (val != args->val3) {
 932                         LIN_SDT_PROBE2(futex, linux_sys_futex,
 933                             debug_cmp_requeue_value_neq, args->val, val);
 934                         LINUX_CTR2(sys_futex, "CMP_REQUEUE val 0x%x != uval 0x%x",
 935                             args->val, val);
 936                         futex_put(f2, NULL);
 937                         futex_put(f, NULL);
 938
 939                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, EAGAIN);
 940                         return (EAGAIN);
 941                 }
 942
 943                 nrwake = (int)(unsigned long)args->timeout;
 944                 td->td_retval[0] = futex_requeue(f, args->val, f2, nrwake);
 945                 futex_put(f2, NULL);
 946                 futex_put(f, NULL);
 947                 break;
 948
 949         case LINUX_FUTEX_WAKE_OP:
 950                 LIN_SDT_PROBE5(futex, linux_sys_futex, debug_wake_op,
 951                     args->uaddr, args->op, args->val, args->uaddr2, args->val3);
 952                 LINUX_CTR5(sys_futex, "WAKE_OP "
 953                     "uaddr %p nrwake 0x%x uaddr2 %p op 0x%x nrwake2 0x%x",
 954                     args->uaddr, args->val, args->uaddr2, args->val3,
 955                     args->timeout);
 956
 957                 if (args->uaddr == args->uaddr2) {
 958                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, EINVAL);
 959                         return (EINVAL);
 960                 }
 961
 962 retry2:
 963                 error = futex_get(args->uaddr, NULL, &f, flags | FUTEX_DONTLOCK);
 964                 if (error) {
 965                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 966                         return (error);
 967                 }
 968
 969                 error = futex_get(args->uaddr2, NULL, &f2, flags | FUTEX_DONTLOCK);
 970                 if (error) {
 971                         futex_put(f, NULL);
 972
 973                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 974                         return (error);
 975                 }
 976                 futex_lock(f);
 977                 futex_lock(f2);
 978
 979                 /*
 980                  * This function returns positive number as results and
 981                  * negative as errors
 982                  */
 983                 save = vm_fault_disable_pagefaults();
 984                 op_ret = futex_atomic_op(td, args->val3, args->uaddr2);
 985                 vm_fault_enable_pagefaults(save);
 986
 987                 LINUX_CTR2(sys_futex, "WAKE_OP atomic_op uaddr %p ret 0x%x",
 988                     args->uaddr, op_ret);
 989
 990                 if (op_ret < 0) {
 991                         if (f2 != NULL)
 992                                 futex_put(f2, NULL);
 993                         futex_put(f, NULL);
 994                         error = copyin(args->uaddr2, &val, sizeof(val));
 995                         if (error == 0)
 996                                 goto retry2;
 997                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 998                         return (error);
 999                 }
1000
1001                 ret = futex_wake(f, args->val, args->val3);
1002
1003                 if (op_ret > 0) {
1004                         op_ret = 0;
1005                         nrwake = (int)(unsigned long)args->timeout;
1006
1007                         if (f2 != NULL)
1008                                 op_ret += futex_wake(f2, nrwake, args->val3);
1009                         else
1010                                 op_ret += futex_wake(f, nrwake, args->val3);
1011                         ret += op_ret;
1012
1013                 }
1014                 if (f2 != NULL)
1015                         futex_put(f2, NULL);
1016                 futex_put(f, NULL);
1017                 td->td_retval[0] = ret;
1018                 break;
1019
1020         case LINUX_FUTEX_LOCK_PI:
1021                 /* not yet implemented */
1022                 pem = pem_find(td->td_proc);
1023                 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
1024                         linux_msg(td,
1025                                   "linux_sys_futex: "
1026                                   "unsupported futex_pi op\n");
1027                         pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
1028                         LIN_SDT_PROBE0(futex, linux_sys_futex,
1029                             unimplemented_lock_pi);
1030                 }
1031                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1032                 return (ENOSYS);
1033
1034         case LINUX_FUTEX_UNLOCK_PI:
1035                 /* not yet implemented */
1036                 pem = pem_find(td->td_proc);
1037                 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
1038                         linux_msg(td,
1039                                   "linux_sys_futex: "
1040                                   "unsupported futex_pi op\n");
1041                         pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
1042                         LIN_SDT_PROBE0(futex, linux_sys_futex,
1043                             unimplemented_unlock_pi);
1044                 }
1045                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1046                 return (ENOSYS);
1047
1048         case LINUX_FUTEX_TRYLOCK_PI:
1049                 /* not yet implemented */
1050                 pem = pem_find(td->td_proc);
1051                 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
1052                         linux_msg(td,
1053                                   "linux_sys_futex: "
1054                                   "unsupported futex_pi op\n");
1055                         pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
1056                         LIN_SDT_PROBE0(futex, linux_sys_futex,
1057                             unimplemented_trylock_pi);
1058                 }
1059                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1060                 return (ENOSYS);
1061
1062         case LINUX_FUTEX_REQUEUE:
1063                 /*
1064                  * Glibc does not use this operation since version 2.3.3,
1065                  * as it is racy and replaced by FUTEX_CMP_REQUEUE operation.
1066                  * Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when
1067                  * FUTEX_REQUEUE returned EINVAL.
1068                  */
1069                 pem = pem_find(td->td_proc);
1070                 if ((pem->flags & LINUX_XDEPR_REQUEUEOP) == 0) {
1071                         linux_msg(td,
1072                                   "linux_sys_futex: "
1073                                   "unsupported futex_requeue op\n");
1074                         pem->flags |= LINUX_XDEPR_REQUEUEOP;
1075                         LIN_SDT_PROBE0(futex, linux_sys_futex,
1076                             deprecated_requeue);
1077                 }
1078
1079                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, EINVAL);
1080                 return (EINVAL);
1081
1082         case LINUX_FUTEX_WAIT_REQUEUE_PI:
1083                 /* not yet implemented */
1084                 pem = pem_find(td->td_proc);
1085                 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
1086                         linux_msg(td,
1087                                   "linux_sys_futex: "
1088                                   "unsupported futex_pi op\n");
1089                         pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
1090                         LIN_SDT_PROBE0(futex, linux_sys_futex,
1091                             unimplemented_wait_requeue_pi);
1092                 }
1093                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1094                 return (ENOSYS);
1095
1096         case LINUX_FUTEX_CMP_REQUEUE_PI:
1097                 /* not yet implemented */
1098                 pem = pem_find(td->td_proc);
1099                 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
1100                         linux_msg(td,
1101                                   "linux_sys_futex: "
1102                                   "unsupported futex_pi op\n");
1103                         pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
1104                         LIN_SDT_PROBE0(futex, linux_sys_futex,
1105                             unimplemented_cmp_requeue_pi);
1106                 }
1107                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1108                 return (ENOSYS);
1109
1110         default:
1111                 linux_msg(td,
1112                           "linux_sys_futex: unknown op %d\n", args->op);
1113                 LIN_SDT_PROBE1(futex, linux_sys_futex, unknown_operation,
1114                     args->op);
1115                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
1116                 return (ENOSYS);
1117         }
1118
1119         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
1120         return (error);
1121 }
1122
1123 int
1124 linux_set_robust_list(struct thread *td, struct linux_set_robust_list_args *args)
1125 {
1126         struct linux_emuldata *em;
1127
1128         LIN_SDT_PROBE2(futex, linux_set_robust_list, entry, td, args);
1129
1130         if (args->len != sizeof(struct linux_robust_list_head)) {
1131                 LIN_SDT_PROBE0(futex, linux_set_robust_list, size_error);
1132                 LIN_SDT_PROBE1(futex, linux_set_robust_list, return, EINVAL);
1133                 return (EINVAL);
1134         }
1135
1136         em = em_find(td);
1137         em->robust_futexes = args->head;
1138
1139         LIN_SDT_PROBE1(futex, linux_set_robust_list, return, 0);
1140         return (0);
1141 }
1142
1143 int
1144 linux_get_robust_list(struct thread *td, struct linux_get_robust_list_args *args)
1145 {
1146         struct linux_emuldata *em;
1147         struct linux_robust_list_head *head;
1148         l_size_t len = sizeof(struct linux_robust_list_head);
1149         struct thread *td2;
1150         int error = 0;
1151
1152         LIN_SDT_PROBE2(futex, linux_get_robust_list, entry, td, args);
1153
1154         if (!args->pid) {
1155                 em = em_find(td);
1156                 KASSERT(em != NULL, ("get_robust_list: emuldata notfound.\n"));
1157                 head = em->robust_futexes;
1158         } else {
1159                 td2 = tdfind(args->pid, -1);
1160                 if (td2 == NULL) {
1161                         LIN_SDT_PROBE1(futex, linux_get_robust_list, return,
1162                             ESRCH);
1163                         return (ESRCH);
1164                 }
1165                 if (SV_PROC_ABI(td2->td_proc) != SV_ABI_LINUX) {
1166                         LIN_SDT_PROBE1(futex, linux_get_robust_list, return,
1167                             EPERM);
1168                         PROC_UNLOCK(td2->td_proc);
1169                         return (EPERM);
1170                 }
1171
1172                 em = em_find(td2);
1173                 KASSERT(em != NULL, ("get_robust_list: emuldata notfound.\n"));
1174                 /* XXX: ptrace? */
1175                 if (priv_check(td, PRIV_CRED_SETUID) ||
1176                     priv_check(td, PRIV_CRED_SETEUID) ||
1177                     p_candebug(td, td2->td_proc)) {
1178                         PROC_UNLOCK(td2->td_proc);
1179
1180                         LIN_SDT_PROBE1(futex, linux_get_robust_list, return,
1181                             EPERM);
1182                         return (EPERM);
1183                 }
1184                 head = em->robust_futexes;
1185
1186                 PROC_UNLOCK(td2->td_proc);
1187         }
1188
1189         error = copyout(&len, args->len, sizeof(l_size_t));
1190         if (error) {
1191                 LIN_SDT_PROBE1(futex, linux_get_robust_list, copyout_error,
1192                     error);
1193                 LIN_SDT_PROBE1(futex, linux_get_robust_list, return, EFAULT);
1194                 return (EFAULT);
1195         }
1196
1197         error = copyout(&head, args->head, sizeof(head));
1198         if (error) {
1199                 LIN_SDT_PROBE1(futex, linux_get_robust_list, copyout_error,
1200                     error);
1201         }
1202
1203         LIN_SDT_PROBE1(futex, linux_get_robust_list, return, error);
1204         return (error);
1205 }
1206
1207 static int
1208 handle_futex_death(struct linux_emuldata *em, uint32_t *uaddr,
1209     unsigned int pi)
1210 {
1211         uint32_t uval, nval, mval;
1212         struct futex *f;
1213         int error;
1214
1215         LIN_SDT_PROBE3(futex, handle_futex_death, entry, em, uaddr, pi);
1216
1217 retry:
1218         error = copyin(uaddr, &uval, 4);
1219         if (error) {
1220                 LIN_SDT_PROBE1(futex, handle_futex_death, copyin_error, error);
1221                 LIN_SDT_PROBE1(futex, handle_futex_death, return, EFAULT);
1222                 return (EFAULT);
1223         }
1224         if ((uval & FUTEX_TID_MASK) == em->em_tid) {
1225                 mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED;
1226                 nval = casuword32(uaddr, uval, mval);
1227
1228                 if (nval == -1) {
1229                         LIN_SDT_PROBE1(futex, handle_futex_death, return,
1230                             EFAULT);
1231                         return (EFAULT);
1232                 }
1233
1234                 if (nval != uval)
1235                         goto retry;
1236
1237                 if (!pi && (uval & FUTEX_WAITERS)) {
1238                         error = futex_get(uaddr, NULL, &f,
1239                             FUTEX_DONTCREATE | FUTEX_SHARED);
1240                         if (error) {
1241                                 LIN_SDT_PROBE1(futex, handle_futex_death,
1242                                     return, error);
1243                                 return (error);
1244                         }
1245                         if (f != NULL) {
1246                                 futex_wake(f, 1, FUTEX_BITSET_MATCH_ANY);
1247                                 futex_put(f, NULL);
1248                         }
1249                 }
1250         }
1251
1252         LIN_SDT_PROBE1(futex, handle_futex_death, return, 0);
1253         return (0);
1254 }
1255
1256 static int
1257 fetch_robust_entry(struct linux_robust_list **entry,
1258     struct linux_robust_list **head, unsigned int *pi)
1259 {
1260         l_ulong uentry;
1261         int error;
1262
1263         LIN_SDT_PROBE3(futex, fetch_robust_entry, entry, entry, head, pi);
1264
1265         error = copyin((const void *)head, &uentry, sizeof(l_ulong));
1266         if (error) {
1267                 LIN_SDT_PROBE1(futex, fetch_robust_entry, copyin_error, error);
1268                 LIN_SDT_PROBE1(futex, fetch_robust_entry, return, EFAULT);
1269                 return (EFAULT);
1270         }
1271
1272         *entry = (void *)(uentry & ~1UL);
1273         *pi = uentry & 1;
1274
1275         LIN_SDT_PROBE1(futex, fetch_robust_entry, return, 0);
1276         return (0);
1277 }
1278
1279 /* This walks the list of robust futexes releasing them. */
1280 void
1281 release_futexes(struct thread *td, struct linux_emuldata *em)
1282 {
1283         struct linux_robust_list_head *head = NULL;
1284         struct linux_robust_list *entry, *next_entry, *pending;
1285         unsigned int limit = 2048, pi, next_pi, pip;
1286         l_long futex_offset;
1287         int rc, error;
1288
1289         LIN_SDT_PROBE2(futex, release_futexes, entry, td, em);
1290
1291         head = em->robust_futexes;
1292
1293         if (head == NULL) {
1294                 LIN_SDT_PROBE0(futex, release_futexes, return);
1295                 return;
1296         }
1297
1298         if (fetch_robust_entry(&entry, PTRIN(&head->list.next), &pi)) {
1299                 LIN_SDT_PROBE0(futex, release_futexes, return);
1300                 return;
1301         }
1302
1303         error = copyin(&head->futex_offset, &futex_offset,
1304             sizeof(futex_offset));
1305         if (error) {
1306                 LIN_SDT_PROBE1(futex, release_futexes, copyin_error, error);
1307                 LIN_SDT_PROBE0(futex, release_futexes, return);
1308                 return;
1309         }
1310
1311         if (fetch_robust_entry(&pending, PTRIN(&head->pending_list), &pip)) {
1312                 LIN_SDT_PROBE0(futex, release_futexes, return);
1313                 return;
1314         }
1315
1316         while (entry != &head->list) {
1317                 rc = fetch_robust_entry(&next_entry, PTRIN(&entry->next), &next_pi);
1318
1319                 if (entry != pending)
1320                         if (handle_futex_death(em,
1321                             (uint32_t *)((caddr_t)entry + futex_offset), pi)) {
1322                                 LIN_SDT_PROBE0(futex, release_futexes, return);
1323                                 return;
1324                         }
1325                 if (rc) {
1326                         LIN_SDT_PROBE0(futex, release_futexes, return);
1327                         return;
1328                 }
1329
1330                 entry = next_entry;
1331                 pi = next_pi;
1332
1333                 if (!--limit)
1334                         break;
1335
1336                 sched_relinquish(curthread);
1337         }
1338
1339         if (pending)
1340                 handle_futex_death(em, (uint32_t *)((caddr_t)pending + futex_offset), pip);
1341
1342         LIN_SDT_PROBE0(futex, release_futexes, return);
1343 }