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  * Copyright (c) 2005 Emmanuel Dreyfus, all rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. All advertising materials mentioning features or use of this software
  15  *    must display the following acknowledgement:
  16  *      This product includes software developed by Emmanuel Dreyfus
  17  * 4. The name of the author may not be used to endorse or promote
  18  *    products derived from this software without specific prior written
  19  *    permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE THE AUTHOR AND CONTRIBUTORS ``AS IS''
  22  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  23  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  24  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
  25  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  26  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  27  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  28  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  29  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  30  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  31  * POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 #include <sys/cdefs.h>
  35 __FBSDID("$FreeBSD$");
  36 #if 0
  37 __KERNEL_RCSID(1, "$NetBSD: linux_futex.c,v 1.7 2006/07/24 19:01:49 manu Exp $");
  38 #endif
  39
  40 #include "opt_compat.h"
  41
  42 #include <sys/param.h>
  43 #include <sys/systm.h>
  44 #include <sys/imgact.h>
  45 #include <sys/kernel.h>
  46 #include <sys/ktr.h>
  47 #include <sys/lock.h>
  48 #include <sys/malloc.h>
  49 #include <sys/mutex.h>
  50 #include <sys/priv.h>
  51 #include <sys/proc.h>
  52 #include <sys/queue.h>
  53 #include <sys/sched.h>
  54 #include <sys/sx.h>
  55 #include <sys/umtx.h>
  56
  57 #ifdef COMPAT_LINUX32
  58 #include <machine/../linux32/linux.h>
  59 #include <machine/../linux32/linux32_proto.h>
  60 #else
  61 #include <machine/../linux/linux.h>
  62 #include <machine/../linux/linux_proto.h>
  63 #endif
  64 #include <compat/linux/linux_emul.h>
  65 #include <compat/linux/linux_futex.h>
  66 #include <compat/linux/linux_util.h>
  67
  68 MALLOC_DEFINE(M_FUTEX, "futex", "Linux futexes");
  69 MALLOC_DEFINE(M_FUTEX_WP, "futex wp", "Linux futexes wp");
  70
  71 struct futex;
  72
  73 struct waiting_proc {
  74         uint32_t        wp_flags;
  75         struct futex    *wp_futex;
  76         TAILQ_ENTRY(waiting_proc) wp_list;
  77 };
  78
  79 struct futex {
  80         struct sx       f_lck;
  81         uint32_t        *f_uaddr;       /* user-supplied value, for debug */
  82         struct umtx_key f_key;
  83         uint32_t        f_refcount;
  84         uint32_t        f_bitset;
  85         LIST_ENTRY(futex) f_list;
  86         TAILQ_HEAD(lf_waiting_proc, waiting_proc) f_waiting_proc;
  87 };
  88
  89 struct futex_list futex_list;
  90
  91 #define FUTEX_LOCK(f)           sx_xlock(&(f)->f_lck)
  92 #define FUTEX_UNLOCK(f)         sx_xunlock(&(f)->f_lck)
  93 #define FUTEX_INIT(f)           sx_init_flags(&(f)->f_lck, "ftlk", SX_DUPOK)
  94 #define FUTEX_DESTROY(f)        sx_destroy(&(f)->f_lck)
  95 #define FUTEX_ASSERT_LOCKED(f)  sx_assert(&(f)->f_lck, SA_XLOCKED)
  96
  97 struct mtx futex_mtx;                   /* protects the futex list */
  98 #define FUTEXES_LOCK            mtx_lock(&futex_mtx)
  99 #define FUTEXES_UNLOCK          mtx_unlock(&futex_mtx)
 100
 101 /* flags for futex_get() */
 102 #define FUTEX_CREATE_WP         0x1     /* create waiting_proc */
 103 #define FUTEX_DONTCREATE        0x2     /* don't create futex if not exists */
 104 #define FUTEX_DONTEXISTS        0x4     /* return EINVAL if futex exists */
 105 #define FUTEX_SHARED            0x8     /* shared futex */
 106
 107 /* wp_flags */
 108 #define FUTEX_WP_REQUEUED       0x1     /* wp requeued - wp moved from wp_list
 109                                          * of futex where thread sleep to wp_list
 110                                          * of another futex.
 111                                          */
 112 #define FUTEX_WP_REMOVED        0x2     /* wp is woken up and removed from futex
 113                                          * wp_list to prevent double wakeup.
 114                                          */
 115
 116 /* support.s */
 117 int futex_xchgl(int oparg, uint32_t *uaddr, int *oldval);
 118 int futex_addl(int oparg, uint32_t *uaddr, int *oldval);
 119 int futex_orl(int oparg, uint32_t *uaddr, int *oldval);
 120 int futex_andl(int oparg, uint32_t *uaddr, int *oldval);
 121 int futex_xorl(int oparg, uint32_t *uaddr, int *oldval);
 122
 123 static void
 124 futex_put(struct futex *f, struct waiting_proc *wp)
 125 {
 126
 127         FUTEX_ASSERT_LOCKED(f);
 128         if (wp != NULL) {
 129                 if ((wp->wp_flags & FUTEX_WP_REMOVED) == 0)
 130                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
 131                 free(wp, M_FUTEX_WP);
 132         }
 133
 134         FUTEXES_LOCK;
 135         if (--f->f_refcount == 0) {
 136                 LIST_REMOVE(f, f_list);
 137                 FUTEXES_UNLOCK;
 138                 FUTEX_UNLOCK(f);
 139
 140                 LINUX_CTR3(sys_futex, "futex_put destroy uaddr %p ref %d "
 141                     "shared %d", f->f_uaddr, f->f_refcount, f->f_key.shared);
 142                 umtx_key_release(&f->f_key);
 143                 FUTEX_DESTROY(f);
 144                 free(f, M_FUTEX);
 145                 return;
 146         }
 147
 148         LINUX_CTR3(sys_futex, "futex_put uaddr %p ref %d shared %d",
 149             f->f_uaddr, f->f_refcount, f->f_key.shared);
 150         FUTEXES_UNLOCK;
 151         FUTEX_UNLOCK(f);
 152 }
 153
 154 static int
 155 futex_get0(uint32_t *uaddr, struct futex **newf, uint32_t flags)
 156 {
 157         struct futex *f, *tmpf;
 158         struct umtx_key key;
 159         int error;
 160
 161         *newf = tmpf = NULL;
 162
 163         error = umtx_key_get(uaddr, TYPE_FUTEX, (flags & FUTEX_SHARED) ?
 164             AUTO_SHARE : THREAD_SHARE, &key);
 165         if (error)
 166                 return (error);
 167 retry:
 168         FUTEXES_LOCK;
 169         LIST_FOREACH(f, &futex_list, f_list) {
 170                 if (umtx_key_match(&f->f_key, &key)) {
 171                         if (tmpf != NULL) {
 172                                 FUTEX_UNLOCK(tmpf);
 173                                 FUTEX_DESTROY(tmpf);
 174                                 free(tmpf, M_FUTEX);
 175                         }
 176                         if (flags & FUTEX_DONTEXISTS) {
 177                                 FUTEXES_UNLOCK;
 178                                 umtx_key_release(&key);
 179                                 return (EINVAL);
 180                         }
 181
 182                         /*
 183                          * Increment refcount of the found futex to
 184                          * prevent it from deallocation before FUTEX_LOCK()
 185                          */
 186                         ++f->f_refcount;
 187                         FUTEXES_UNLOCK;
 188                         umtx_key_release(&key);
 189
 190                         FUTEX_LOCK(f);
 191                         *newf = f;
 192                         LINUX_CTR3(sys_futex, "futex_get uaddr %p ref %d shared %d",
 193                             uaddr, f->f_refcount, f->f_key.shared);
 194                         return (0);
 195                 }
 196         }
 197
 198         if (flags & FUTEX_DONTCREATE) {
 199                 FUTEXES_UNLOCK;
 200                 umtx_key_release(&key);
 201                 LINUX_CTR1(sys_futex, "futex_get uaddr %p null", uaddr);
 202                 return (0);
 203         }
 204
 205         if (tmpf == NULL) {
 206                 FUTEXES_UNLOCK;
 207                 tmpf = malloc(sizeof(*tmpf), M_FUTEX, M_WAITOK | M_ZERO);
 208                 tmpf->f_uaddr = uaddr;
 209                 tmpf->f_key = key;
 210                 tmpf->f_refcount = 1;
 211                 tmpf->f_bitset = FUTEX_BITSET_MATCH_ANY;
 212                 FUTEX_INIT(tmpf);
 213                 TAILQ_INIT(&tmpf->f_waiting_proc);
 214
 215                 /*
 216                  * Lock the new futex before an insert into the futex_list
 217                  * to prevent futex usage by other.
 218                  */
 219                 FUTEX_LOCK(tmpf);
 220                 goto retry;
 221         }
 222
 223         LIST_INSERT_HEAD(&futex_list, tmpf, f_list);
 224         FUTEXES_UNLOCK;
 225
 226         LINUX_CTR3(sys_futex, "futex_get uaddr %p ref %d shared %d new",
 227             uaddr, tmpf->f_refcount, tmpf->f_key.shared);
 228         *newf = tmpf;
 229         return (0);
 230 }
 231
 232 static int
 233 futex_get(uint32_t *uaddr, struct waiting_proc **wp, struct futex **f,
 234     uint32_t flags)
 235 {
 236         int error;
 237
 238         if (flags & FUTEX_CREATE_WP) {
 239                 *wp = malloc(sizeof(struct waiting_proc), M_FUTEX_WP, M_WAITOK);
 240                 (*wp)->wp_flags = 0;
 241         }
 242         error = futex_get0(uaddr, f, flags);
 243         if (error) {
 244                 if (flags & FUTEX_CREATE_WP)
 245                         free(*wp, M_FUTEX_WP);
 246                 return (error);
 247         }
 248         if (flags & FUTEX_CREATE_WP) {
 249                 TAILQ_INSERT_HEAD(&(*f)->f_waiting_proc, *wp, wp_list);
 250                 (*wp)->wp_futex = *f;
 251         }
 252
 253         return (error);
 254 }
 255
 256 static int
 257 futex_sleep(struct futex *f, struct waiting_proc *wp, unsigned long timeout)
 258 {
 259         int error;
 260
 261         FUTEX_ASSERT_LOCKED(f);
 262         LINUX_CTR4(sys_futex, "futex_sleep enter uaddr %p wp %p timo %ld ref %d",
 263             f->f_uaddr, wp, timeout, f->f_refcount);
 264         error = sx_sleep(wp, &f->f_lck, PCATCH, "futex", timeout);
 265         if (wp->wp_flags & FUTEX_WP_REQUEUED) {
 266                 KASSERT(f != wp->wp_futex, ("futex != wp_futex"));
 267                 LINUX_CTR5(sys_futex, "futex_sleep out error %d uaddr %p w"
 268                     " %p requeued uaddr %p ref %d",
 269                     error, f->f_uaddr, wp, wp->wp_futex->f_uaddr,
 270                     wp->wp_futex->f_refcount);
 271                 futex_put(f, NULL);
 272                 f = wp->wp_futex;
 273                 FUTEX_LOCK(f);
 274         } else
 275                 LINUX_CTR3(sys_futex, "futex_sleep out error %d uaddr %p wp %p",
 276                     error, f->f_uaddr, wp);
 277
 278         futex_put(f, wp);
 279         return (error);
 280 }
 281
 282 static int
 283 futex_wake(struct futex *f, int n, uint32_t bitset)
 284 {
 285         struct waiting_proc *wp, *wpt;
 286         int count = 0;
 287
 288         if (bitset == 0)
 289                 return (EINVAL);
 290
 291         FUTEX_ASSERT_LOCKED(f);
 292         TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) {
 293                 LINUX_CTR3(sys_futex, "futex_wake uaddr %p wp %p ref %d",
 294                     f->f_uaddr, wp, f->f_refcount);
 295                 /*
 296                  * Unless we find a matching bit in
 297                  * the bitset, continue searching.
 298                  */
 299                 if (!(wp->wp_futex->f_bitset & bitset))
 300                         continue;
 301
 302                 wp->wp_flags |= FUTEX_WP_REMOVED;
 303                 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
 304                 wakeup_one(wp);
 305                 if (++count == n)
 306                         break;
 307         }
 308
 309         return (count);
 310 }
 311
 312 static int
 313 futex_requeue(struct futex *f, int n, struct futex *f2, int n2)
 314 {
 315         struct waiting_proc *wp, *wpt;
 316         int count = 0;
 317
 318         FUTEX_ASSERT_LOCKED(f);
 319         FUTEX_ASSERT_LOCKED(f2);
 320
 321         TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) {
 322                 if (++count <= n) {
 323                         LINUX_CTR2(sys_futex, "futex_req_wake uaddr %p wp %p",
 324                             f->f_uaddr, wp);
 325                         wp->wp_flags |= FUTEX_WP_REMOVED;
 326                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
 327                         wakeup_one(wp);
 328                 } else {
 329                         LINUX_CTR3(sys_futex, "futex_requeue uaddr %p wp %p to %p",
 330                             f->f_uaddr, wp, f2->f_uaddr);
 331                         wp->wp_flags |= FUTEX_WP_REQUEUED;
 332                         /* Move wp to wp_list of f2 futex */
 333                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
 334                         TAILQ_INSERT_HEAD(&f2->f_waiting_proc, wp, wp_list);
 335
 336                         /*
 337                          * Thread which sleeps on wp after waking should
 338                          * acquire f2 lock, so increment refcount of f2 to
 339                          * prevent it from premature deallocation.
 340                          */
 341                         wp->wp_futex = f2;
 342                         FUTEXES_LOCK;
 343                         ++f2->f_refcount;
 344                         FUTEXES_UNLOCK;
 345                         if (count - n >= n2)
 346                                 break;
 347                 }
 348         }
 349
 350         return (count);
 351 }
 352
 353 static int
 354 futex_wait(struct futex *f, struct waiting_proc *wp, struct l_timespec *ts,
 355     uint32_t bitset)
 356 {
 357         struct l_timespec timeout = {0, 0};
 358         struct timeval tv = {0, 0};
 359         int timeout_hz;
 360         int error;
 361
 362         if (bitset == 0)
 363                 return (EINVAL);
 364         f->f_bitset = bitset;
 365
 366         if (ts != NULL) {
 367                 error = copyin(ts, &timeout, sizeof(timeout));
 368                 if (error)
 369                         return (error);
 370         }
 371
 372         tv.tv_usec = timeout.tv_sec * 1000000 + timeout.tv_nsec / 1000;
 373         timeout_hz = tvtohz(&tv);
 374
 375         if (timeout.tv_sec == 0 && timeout.tv_nsec == 0)
 376                 timeout_hz = 0;
 377
 378         /*
 379          * If the user process requests a non null timeout,
 380          * make sure we do not turn it into an infinite
 381          * timeout because timeout_hz gets null.
 382          *
 383          * We use a minimal timeout of 1/hz. Maybe it would
 384          * make sense to just return ETIMEDOUT without sleeping.
 385          */
 386         if (((timeout.tv_sec != 0) || (timeout.tv_nsec != 0)) &&
 387             (timeout_hz == 0))
 388                 timeout_hz = 1;
 389
 390         error = futex_sleep(f, wp, timeout_hz);
 391         if (error == EWOULDBLOCK)
 392                 error = ETIMEDOUT;
 393
 394         return (error);
 395 }
 396
 397 static int
 398 futex_atomic_op(struct thread *td, int encoded_op, uint32_t *uaddr)
 399 {
 400         int op = (encoded_op >> 28) & 7;
 401         int cmp = (encoded_op >> 24) & 15;
 402         int oparg = (encoded_op << 8) >> 20;
 403         int cmparg = (encoded_op << 20) >> 20;
 404         int oldval = 0, ret;
 405
 406         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
 407                 oparg = 1 << oparg;
 408
 409 #ifdef DEBUG
 410         if (ldebug(sys_futex))
 411                 printf("futex_atomic_op: op = %d, cmp = %d, oparg = %x, "
 412                        "cmparg = %x, uaddr = %p\n",
 413                        op, cmp, oparg, cmparg, uaddr);
 414 #endif
 415         /* XXX: Linux verifies access here and returns EFAULT */
 416
 417         switch (op) {
 418         case FUTEX_OP_SET:
 419                 ret = futex_xchgl(oparg, uaddr, &oldval);
 420                 break;
 421         case FUTEX_OP_ADD:
 422                 ret = futex_addl(oparg, uaddr, &oldval);
 423                 break;
 424         case FUTEX_OP_OR:
 425                 ret = futex_orl(oparg, uaddr, &oldval);
 426                 break;
 427         case FUTEX_OP_ANDN:
 428                 ret = futex_andl(~oparg, uaddr, &oldval);
 429                 break;
 430         case FUTEX_OP_XOR:
 431                 ret = futex_xorl(oparg, uaddr, &oldval);
 432                 break;
 433         default:
 434                 ret = -ENOSYS;
 435                 break;
 436         }
 437
 438         if (ret)
 439                 return (ret);
 440
 441         switch (cmp) {
 442         case FUTEX_OP_CMP_EQ:
 443                 return (oldval == cmparg);
 444         case FUTEX_OP_CMP_NE:
 445                 return (oldval != cmparg);
 446         case FUTEX_OP_CMP_LT:
 447                 return (oldval < cmparg);
 448         case FUTEX_OP_CMP_GE:
 449                 return (oldval >= cmparg);
 450         case FUTEX_OP_CMP_LE:
 451                 return (oldval <= cmparg);
 452         case FUTEX_OP_CMP_GT:
 453                 return (oldval > cmparg);
 454         default:
 455                 return (-ENOSYS);
 456         }
 457 }
 458
 459 int
 460 linux_sys_futex(struct thread *td, struct linux_sys_futex_args *args)
 461 {
 462         int clockrt, nrwake, op_ret, ret, val;
 463         struct linux_emuldata *em;
 464         struct waiting_proc *wp;
 465         struct futex *f, *f2;
 466         int error;
 467         uint32_t flags;
 468
 469         if (args->op & LINUX_FUTEX_PRIVATE_FLAG) {
 470                 flags = 0;
 471                 args->op &= ~LINUX_FUTEX_PRIVATE_FLAG;
 472         } else
 473                 flags = FUTEX_SHARED;
 474
 475         /*
 476          * Currently support for switching between CLOCK_MONOTONIC and
 477          * CLOCK_REALTIME is not present. However Linux forbids the use of
 478          * FUTEX_CLOCK_REALTIME with any op except FUTEX_WAIT_BITSET and
 479          * FUTEX_WAIT_REQUEUE_PI.
 480          */
 481         clockrt = args->op & LINUX_FUTEX_CLOCK_REALTIME;
 482         args->op = args->op & ~LINUX_FUTEX_CLOCK_REALTIME;
 483         if (clockrt && args->op != LINUX_FUTEX_WAIT_BITSET &&
 484                 args->op != LINUX_FUTEX_WAIT_REQUEUE_PI)
 485                 return (ENOSYS);
 486
 487         error = 0;
 488         f = f2 = NULL;
 489
 490         switch (args->op) {
 491         case LINUX_FUTEX_WAIT:
 492                 args->val3 = FUTEX_BITSET_MATCH_ANY;
 493                 /* FALLTHROUGH */
 494
 495         case LINUX_FUTEX_WAIT_BITSET:
 496
 497                 LINUX_CTR3(sys_futex, "WAIT uaddr %p val %d val3 %d",
 498                     args->uaddr, args->val, args->val3);
 499 #ifdef DEBUG
 500                 if (ldebug(sys_futex))
 501                         printf(ARGS(sys_futex,
 502                             "futex_wait uaddr %p val %d val3 %d"),
 503                             args->uaddr, args->val, args->val3);
 504 #endif
 505                 error = futex_get(args->uaddr, &wp, &f,
 506                     flags | FUTEX_CREATE_WP);
 507                 if (error)
 508                         return (error);
 509                 error = copyin(args->uaddr, &val, sizeof(val));
 510                 if (error) {
 511                         LINUX_CTR1(sys_futex, "WAIT copyin failed %d",
 512                             error);
 513                         futex_put(f, wp);
 514                         return (error);
 515                 }
 516                 if (val != args->val) {
 517                         LINUX_CTR4(sys_futex,
 518                             "WAIT uaddr %p val %d != uval %d val3 %d",
 519                             args->uaddr, args->val, val, args->val3);
 520                         futex_put(f, wp);
 521                         return (EWOULDBLOCK);
 522                 }
 523
 524                 error = futex_wait(f, wp, args->timeout, args->val3);
 525                 break;
 526
 527         case LINUX_FUTEX_WAKE:
 528                 args->val3 = FUTEX_BITSET_MATCH_ANY;
 529                 /* FALLTHROUGH */
 530
 531         case LINUX_FUTEX_WAKE_BITSET:
 532
 533                 LINUX_CTR3(sys_futex, "WAKE uaddr %p val % d val3 %d",
 534                     args->uaddr, args->val, args->val3);
 535
 536 #ifdef DEBUG
 537                 if (ldebug(sys_futex))
 538                         printf(ARGS(sys_futex, "futex_wake uaddr %p val %d val3 %d"),
 539                             args->uaddr, args->val, args->val3);
 540 #endif
 541                 error = futex_get(args->uaddr, NULL, &f,
 542                     flags | FUTEX_DONTCREATE);
 543                 if (error)
 544                         return (error);
 545                 if (f == NULL) {
 546                         td->td_retval[0] = 0;
 547                         return (error);
 548                 }
 549                 td->td_retval[0] = futex_wake(f, args->val, args->val3);
 550                 futex_put(f, NULL);
 551                 break;
 552
 553         case LINUX_FUTEX_CMP_REQUEUE:
 554
 555                 LINUX_CTR5(sys_futex, "CMP_REQUEUE uaddr %p "
 556                     "val %d val3 %d uaddr2 %p val2 %d",
 557                     args->uaddr, args->val, args->val3, args->uaddr2,
 558                     (int)(unsigned long)args->timeout);
 559
 560 #ifdef DEBUG
 561                 if (ldebug(sys_futex))
 562                         printf(ARGS(sys_futex, "futex_cmp_requeue uaddr %p "
 563                             "val %d val3 %d uaddr2 %p val2 %d"),
 564                             args->uaddr, args->val, args->val3, args->uaddr2,
 565                             (int)(unsigned long)args->timeout);
 566 #endif
 567
 568                 /*
 569                  * Linux allows this, we would not, it is an incorrect
 570                  * usage of declared ABI, so return EINVAL.
 571                  */
 572                 if (args->uaddr == args->uaddr2)
 573                         return (EINVAL);
 574                 error = futex_get(args->uaddr, NULL, &f, flags);
 575                 if (error)
 576                         return (error);
 577
 578                 /*
 579                  * To avoid deadlocks return EINVAL if second futex
 580                  * exists at this time.
 581                  *
 582                  * Glibc fall back to FUTEX_WAKE in case of any error
 583                  * returned by FUTEX_CMP_REQUEUE.
 584                  */
 585                 error = futex_get(args->uaddr2, NULL, &f2,
 586                     flags | FUTEX_DONTEXISTS);
 587                 if (error) {
 588                         futex_put(f, NULL);
 589                         return (error);
 590                 }
 591                 error = copyin(args->uaddr, &val, sizeof(val));
 592                 if (error) {
 593                         LINUX_CTR1(sys_futex, "CMP_REQUEUE copyin failed %d",
 594                             error);
 595                         futex_put(f2, NULL);
 596                         futex_put(f, NULL);
 597                         return (error);
 598                 }
 599                 if (val != args->val3) {
 600                         LINUX_CTR2(sys_futex, "CMP_REQUEUE val %d != uval %d",
 601                             args->val, val);
 602                         futex_put(f2, NULL);
 603                         futex_put(f, NULL);
 604                         return (EAGAIN);
 605                 }
 606
 607                 nrwake = (int)(unsigned long)args->timeout;
 608                 td->td_retval[0] = futex_requeue(f, args->val, f2, nrwake);
 609                 futex_put(f2, NULL);
 610                 futex_put(f, NULL);
 611                 break;
 612
 613         case LINUX_FUTEX_WAKE_OP:
 614
 615                 LINUX_CTR5(sys_futex, "WAKE_OP "
 616                     "uaddr %p op %d val %x uaddr2 %p val3 %x",
 617                     args->uaddr, args->op, args->val,
 618                     args->uaddr2, args->val3);
 619
 620 #ifdef DEBUG
 621                 if (ldebug(sys_futex))
 622                         printf(ARGS(sys_futex, "futex_wake_op "
 623                             "uaddr %p op %d val %x uaddr2 %p val3 %x"),
 624                             args->uaddr, args->op, args->val,
 625                             args->uaddr2, args->val3);
 626 #endif
 627                 error = futex_get(args->uaddr, NULL, &f, flags);
 628                 if (error)
 629                         return (error);
 630                 if (args->uaddr != args->uaddr2)
 631                         error = futex_get(args->uaddr2, NULL, &f2, flags);
 632                 if (error) {
 633                         futex_put(f, NULL);
 634                         return (error);
 635                 }
 636
 637                 /*
 638                  * This function returns positive number as results and
 639                  * negative as errors
 640                  */
 641                 op_ret = futex_atomic_op(td, args->val3, args->uaddr2);
 642
 643                 if (op_ret < 0) {
 644                         /* XXX: We don't handle the EFAULT yet. */
 645                         if (op_ret != -EFAULT) {
 646                                 if (f2 != NULL)
 647                                         futex_put(f2, NULL);
 648                                 futex_put(f, NULL);
 649                                 return (-op_ret);
 650                         }
 651                         if (f2 != NULL)
 652                                 futex_put(f2, NULL);
 653                         futex_put(f, NULL);
 654                         return (EFAULT);
 655                 }
 656
 657                 ret = futex_wake(f, args->val, args->val3);
 658
 659                 if (op_ret > 0) {
 660                         op_ret = 0;
 661                         nrwake = (int)(unsigned long)args->timeout;
 662
 663                         if (f2 != NULL)
 664                                 op_ret += futex_wake(f2, nrwake, args->val3);
 665                         else
 666                                 op_ret += futex_wake(f, nrwake, args->val3);
 667                         ret += op_ret;
 668
 669                 }
 670                 if (f2 != NULL)
 671                         futex_put(f2, NULL);
 672                 futex_put(f, NULL);
 673                 td->td_retval[0] = ret;
 674                 break;
 675
 676         case LINUX_FUTEX_LOCK_PI:
 677                 /* not yet implemented */
 678                 linux_msg(td,
 679                           "linux_sys_futex: "
 680                           "op LINUX_FUTEX_LOCK_PI not implemented\n");
 681                 return (ENOSYS);
 682
 683         case LINUX_FUTEX_UNLOCK_PI:
 684                 /* not yet implemented */
 685                 linux_msg(td,
 686                           "linux_sys_futex: "
 687                           "op LINUX_FUTEX_UNLOCK_PI not implemented\n");
 688                 return (ENOSYS);
 689
 690         case LINUX_FUTEX_TRYLOCK_PI:
 691                 /* not yet implemented */
 692                 linux_msg(td,
 693                           "linux_sys_futex: "
 694                           "op LINUX_FUTEX_TRYLOCK_PI not implemented\n");
 695                 return (ENOSYS);
 696
 697         case LINUX_FUTEX_REQUEUE:
 698
 699                 /*
 700                  * Glibc does not use this operation since version 2.3.3,
 701                  * as it is racy and replaced by FUTEX_CMP_REQUEUE operation.
 702                  * Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when
 703                  * FUTEX_REQUEUE returned EINVAL.
 704                  */
 705                 em = em_find(td->td_proc, EMUL_DONTLOCK);
 706                 if ((em->flags & LINUX_XDEPR_REQUEUEOP) == 0) {
 707                         linux_msg(td,
 708                                   "linux_sys_futex: "
 709                                   "unsupported futex_requeue op\n");
 710                         em->flags |= LINUX_XDEPR_REQUEUEOP;
 711                 }
 712                 return (EINVAL);
 713
 714         case LINUX_FUTEX_WAIT_REQUEUE_PI:
 715                 /* not yet implemented */
 716                 linux_msg(td,
 717                           "linux_sys_futex: "
 718                           "op FUTEX_WAIT_REQUEUE_PI not implemented\n");
 719                 return (ENOSYS);
 720
 721         case LINUX_FUTEX_CMP_REQUEUE_PI:
 722                 /* not yet implemented */
 723                 linux_msg(td,
 724                             "linux_sys_futex: "
 725                             "op LINUX_FUTEX_CMP_REQUEUE_PI not implemented\n");
 726                 return (ENOSYS);
 727
 728         default:
 729                 linux_msg(td,
 730                           "linux_sys_futex: unknown op %d\n", args->op);
 731                 return (ENOSYS);
 732         }
 733
 734         return (error);
 735 }
 736
 737 int
 738 linux_set_robust_list(struct thread *td, struct linux_set_robust_list_args *args)
 739 {
 740         struct linux_emuldata *em;
 741
 742 #ifdef DEBUG
 743         if (ldebug(set_robust_list))
 744                 printf(ARGS(set_robust_list, "head %p len %d"),
 745                     args->head, args->len);
 746 #endif
 747
 748         if (args->len != sizeof(struct linux_robust_list_head))
 749                 return (EINVAL);
 750
 751         em = em_find(td->td_proc, EMUL_DOLOCK);
 752         em->robust_futexes = args->head;
 753         EMUL_UNLOCK(&emul_lock);
 754
 755         return (0);
 756 }
 757
 758 int
 759 linux_get_robust_list(struct thread *td, struct linux_get_robust_list_args *args)
 760 {
 761         struct linux_emuldata *em;
 762         struct linux_robust_list_head *head;
 763         l_size_t len = sizeof(struct linux_robust_list_head);
 764         int error = 0;
 765
 766 #ifdef  DEBUG
 767         if (ldebug(get_robust_list))
 768                 printf(ARGS(get_robust_list, ""));
 769 #endif
 770
 771         if (!args->pid) {
 772                 em = em_find(td->td_proc, EMUL_DONTLOCK);
 773                 head = em->robust_futexes;
 774         } else {
 775                 struct proc *p;
 776
 777                 p = pfind(args->pid);
 778                 if (p == NULL)
 779                         return (ESRCH);
 780
 781                 em = em_find(p, EMUL_DONTLOCK);
 782                 /* XXX: ptrace? */
 783                 if (priv_check(td, PRIV_CRED_SETUID) ||
 784                     priv_check(td, PRIV_CRED_SETEUID) ||
 785                     p_candebug(td, p)) {
 786                         PROC_UNLOCK(p);
 787                         return (EPERM);
 788                 }
 789                 head = em->robust_futexes;
 790
 791                 PROC_UNLOCK(p);
 792         }
 793
 794         error = copyout(&len, args->len, sizeof(l_size_t));
 795         if (error)
 796                 return (EFAULT);
 797
 798         error = copyout(head, args->head, sizeof(struct linux_robust_list_head));
 799
 800         return (error);
 801 }
 802
 803 static int
 804 handle_futex_death(struct proc *p, uint32_t *uaddr, int pi)
 805 {
 806         uint32_t uval, nval, mval;
 807         struct futex *f;
 808         int error;
 809
 810 retry:
 811         if (copyin(uaddr, &uval, 4))
 812                 return (EFAULT);
 813         if ((uval & FUTEX_TID_MASK) == p->p_pid) {
 814                 mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED;
 815                 nval = casuword32(uaddr, uval, mval);
 816
 817                 if (nval == -1)
 818                         return (EFAULT);
 819
 820                 if (nval != uval)
 821                         goto retry;
 822
 823                 if (!pi && (uval & FUTEX_WAITERS)) {
 824                         error = futex_get(uaddr, NULL, &f,
 825                             FUTEX_DONTCREATE | FUTEX_SHARED);
 826                         if (error)
 827                                 return (error);
 828                         if (f != NULL) {
 829                                 futex_wake(f, 1, FUTEX_BITSET_MATCH_ANY);
 830                                 futex_put(f, NULL);
 831                         }
 832                 }
 833         }
 834
 835         return (0);
 836 }
 837
 838 static int
 839 fetch_robust_entry(struct linux_robust_list **entry,
 840     struct linux_robust_list **head, int *pi)
 841 {
 842         l_ulong uentry;
 843
 844         if (copyin((const void *)head, &uentry, sizeof(l_ulong)))
 845                 return (EFAULT);
 846
 847         *entry = (void *)(uentry & ~1UL);
 848         *pi = uentry & 1;
 849
 850         return (0);
 851 }
 852
 853 /* This walks the list of robust futexes releasing them. */
 854 void
 855 release_futexes(struct proc *p)
 856 {
 857         struct linux_robust_list_head *head = NULL;
 858         struct linux_robust_list *entry, *next_entry, *pending;
 859         unsigned int limit = 2048, pi, next_pi, pip;
 860         struct linux_emuldata *em;
 861         l_long futex_offset;
 862         int rc;
 863
 864         em = em_find(p, EMUL_DONTLOCK);
 865         head = em->robust_futexes;
 866
 867         if (head == NULL)
 868                 return;
 869
 870         if (fetch_robust_entry(&entry, PTRIN(&head->list.next), &pi))
 871                 return;
 872
 873         if (copyin(&head->futex_offset, &futex_offset, sizeof(futex_offset)))
 874                 return;
 875
 876         if (fetch_robust_entry(&pending, PTRIN(&head->pending_list), &pip))
 877                 return;
 878
 879         while (entry != &head->list) {
 880                 rc = fetch_robust_entry(&next_entry, PTRIN(&entry->next), &next_pi);
 881
 882                 if (entry != pending)
 883                         if (handle_futex_death(p, (uint32_t *)entry + futex_offset, pi))
 884                                 return;
 885                 if (rc)
 886                         return;
 887
 888                 entry = next_entry;
 889                 pi = next_pi;
 890
 891                 if (!--limit)
 892                         break;
 893
 894                 sched_relinquish(curthread);
 895         }
 896
 897         if (pending)
 898                 handle_futex_death(p, (uint32_t *)pending + futex_offset, pip);
 899 }