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