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, int timeout)
 258 {
 259         int error;
 260
 261         FUTEX_ASSERT_LOCKED(f);
 262         LINUX_CTR4(sys_futex, "futex_sleep enter uaddr %p wp %p timo %d 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;
 358         struct timeval tv;
 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                 TIMESPEC_TO_TIMEVAL(&tv, &timeout);
 371                 error = itimerfix(&tv);
 372                 if (error)
 373                         return (error);
 374                 timeout_hz = tvtohz(&tv);
 375         } else
 376                 timeout_hz = 0;
 377
 378         error = futex_sleep(f, wp, timeout_hz);
 379         if (error == EWOULDBLOCK)
 380                 error = ETIMEDOUT;
 381
 382         return (error);
 383 }
 384
 385 static int
 386 futex_atomic_op(struct thread *td, int encoded_op, uint32_t *uaddr)
 387 {
 388         int op = (encoded_op >> 28) & 7;
 389         int cmp = (encoded_op >> 24) & 15;
 390         int oparg = (encoded_op << 8) >> 20;
 391         int cmparg = (encoded_op << 20) >> 20;
 392         int oldval = 0, ret;
 393
 394         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
 395                 oparg = 1 << oparg;
 396
 397 #ifdef DEBUG
 398         if (ldebug(sys_futex))
 399                 printf("futex_atomic_op: op = %d, cmp = %d, oparg = %x, "
 400                        "cmparg = %x, uaddr = %p\n",
 401                        op, cmp, oparg, cmparg, uaddr);
 402 #endif
 403         /* XXX: Linux verifies access here and returns EFAULT */
 404
 405         switch (op) {
 406         case FUTEX_OP_SET:
 407                 ret = futex_xchgl(oparg, uaddr, &oldval);
 408                 break;
 409         case FUTEX_OP_ADD:
 410                 ret = futex_addl(oparg, uaddr, &oldval);
 411                 break;
 412         case FUTEX_OP_OR:
 413                 ret = futex_orl(oparg, uaddr, &oldval);
 414                 break;
 415         case FUTEX_OP_ANDN:
 416                 ret = futex_andl(~oparg, uaddr, &oldval);
 417                 break;
 418         case FUTEX_OP_XOR:
 419                 ret = futex_xorl(oparg, uaddr, &oldval);
 420                 break;
 421         default:
 422                 ret = -ENOSYS;
 423                 break;
 424         }
 425
 426         if (ret)
 427                 return (ret);
 428
 429         switch (cmp) {
 430         case FUTEX_OP_CMP_EQ:
 431                 return (oldval == cmparg);
 432         case FUTEX_OP_CMP_NE:
 433                 return (oldval != cmparg);
 434         case FUTEX_OP_CMP_LT:
 435                 return (oldval < cmparg);
 436         case FUTEX_OP_CMP_GE:
 437                 return (oldval >= cmparg);
 438         case FUTEX_OP_CMP_LE:
 439                 return (oldval <= cmparg);
 440         case FUTEX_OP_CMP_GT:
 441                 return (oldval > cmparg);
 442         default:
 443                 return (-ENOSYS);
 444         }
 445 }
 446
 447 int
 448 linux_sys_futex(struct thread *td, struct linux_sys_futex_args *args)
 449 {
 450         int clockrt, nrwake, op_ret, ret, val;
 451         struct linux_emuldata *em;
 452         struct waiting_proc *wp;
 453         struct futex *f, *f2;
 454         int error;
 455         uint32_t flags;
 456
 457         if (args->op & LINUX_FUTEX_PRIVATE_FLAG) {
 458                 flags = 0;
 459                 args->op &= ~LINUX_FUTEX_PRIVATE_FLAG;
 460         } else
 461                 flags = FUTEX_SHARED;
 462
 463         /*
 464          * Currently support for switching between CLOCK_MONOTONIC and
 465          * CLOCK_REALTIME is not present. However Linux forbids the use of
 466          * FUTEX_CLOCK_REALTIME with any op except FUTEX_WAIT_BITSET and
 467          * FUTEX_WAIT_REQUEUE_PI.
 468          */
 469         clockrt = args->op & LINUX_FUTEX_CLOCK_REALTIME;
 470         args->op = args->op & ~LINUX_FUTEX_CLOCK_REALTIME;
 471         if (clockrt && args->op != LINUX_FUTEX_WAIT_BITSET &&
 472                 args->op != LINUX_FUTEX_WAIT_REQUEUE_PI)
 473                 return (ENOSYS);
 474
 475         error = 0;
 476         f = f2 = NULL;
 477
 478         switch (args->op) {
 479         case LINUX_FUTEX_WAIT:
 480                 args->val3 = FUTEX_BITSET_MATCH_ANY;
 481                 /* FALLTHROUGH */
 482
 483         case LINUX_FUTEX_WAIT_BITSET:
 484
 485                 LINUX_CTR3(sys_futex, "WAIT uaddr %p val %d val3 %d",
 486                     args->uaddr, args->val, args->val3);
 487 #ifdef DEBUG
 488                 if (ldebug(sys_futex))
 489                         printf(ARGS(sys_futex,
 490                             "futex_wait uaddr %p val %d val3 %d"),
 491                             args->uaddr, args->val, args->val3);
 492 #endif
 493                 error = futex_get(args->uaddr, &wp, &f,
 494                     flags | FUTEX_CREATE_WP);
 495                 if (error)
 496                         return (error);
 497                 error = copyin(args->uaddr, &val, sizeof(val));
 498                 if (error) {
 499                         LINUX_CTR1(sys_futex, "WAIT copyin failed %d",
 500                             error);
 501                         futex_put(f, wp);
 502                         return (error);
 503                 }
 504                 if (val != args->val) {
 505                         LINUX_CTR4(sys_futex,
 506                             "WAIT uaddr %p val %d != uval %d val3 %d",
 507                             args->uaddr, args->val, val, args->val3);
 508                         futex_put(f, wp);
 509                         return (EWOULDBLOCK);
 510                 }
 511
 512                 error = futex_wait(f, wp, args->timeout, args->val3);
 513                 break;
 514
 515         case LINUX_FUTEX_WAKE:
 516                 args->val3 = FUTEX_BITSET_MATCH_ANY;
 517                 /* FALLTHROUGH */
 518
 519         case LINUX_FUTEX_WAKE_BITSET:
 520
 521                 LINUX_CTR3(sys_futex, "WAKE uaddr %p val % d val3 %d",
 522                     args->uaddr, args->val, args->val3);
 523
 524 #ifdef DEBUG
 525                 if (ldebug(sys_futex))
 526                         printf(ARGS(sys_futex, "futex_wake uaddr %p val %d val3 %d"),
 527                             args->uaddr, args->val, args->val3);
 528 #endif
 529                 error = futex_get(args->uaddr, NULL, &f,
 530                     flags | FUTEX_DONTCREATE);
 531                 if (error)
 532                         return (error);
 533                 if (f == NULL) {
 534                         td->td_retval[0] = 0;
 535                         return (error);
 536                 }
 537                 td->td_retval[0] = futex_wake(f, args->val, args->val3);
 538                 futex_put(f, NULL);
 539                 break;
 540
 541         case LINUX_FUTEX_CMP_REQUEUE:
 542
 543                 LINUX_CTR5(sys_futex, "CMP_REQUEUE uaddr %p "
 544                     "val %d val3 %d uaddr2 %p val2 %d",
 545                     args->uaddr, args->val, args->val3, args->uaddr2,
 546                     (int)(unsigned long)args->timeout);
 547
 548 #ifdef DEBUG
 549                 if (ldebug(sys_futex))
 550                         printf(ARGS(sys_futex, "futex_cmp_requeue uaddr %p "
 551                             "val %d val3 %d uaddr2 %p val2 %d"),
 552                             args->uaddr, args->val, args->val3, args->uaddr2,
 553                             (int)(unsigned long)args->timeout);
 554 #endif
 555
 556                 /*
 557                  * Linux allows this, we would not, it is an incorrect
 558                  * usage of declared ABI, so return EINVAL.
 559                  */
 560                 if (args->uaddr == args->uaddr2)
 561                         return (EINVAL);
 562                 error = futex_get(args->uaddr, NULL, &f, flags);
 563                 if (error)
 564                         return (error);
 565
 566                 /*
 567                  * To avoid deadlocks return EINVAL if second futex
 568                  * exists at this time.
 569                  *
 570                  * Glibc fall back to FUTEX_WAKE in case of any error
 571                  * returned by FUTEX_CMP_REQUEUE.
 572                  */
 573                 error = futex_get(args->uaddr2, NULL, &f2,
 574                     flags | FUTEX_DONTEXISTS);
 575                 if (error) {
 576                         futex_put(f, NULL);
 577                         return (error);
 578                 }
 579                 error = copyin(args->uaddr, &val, sizeof(val));
 580                 if (error) {
 581                         LINUX_CTR1(sys_futex, "CMP_REQUEUE copyin failed %d",
 582                             error);
 583                         futex_put(f2, NULL);
 584                         futex_put(f, NULL);
 585                         return (error);
 586                 }
 587                 if (val != args->val3) {
 588                         LINUX_CTR2(sys_futex, "CMP_REQUEUE val %d != uval %d",
 589                             args->val, val);
 590                         futex_put(f2, NULL);
 591                         futex_put(f, NULL);
 592                         return (EAGAIN);
 593                 }
 594
 595                 nrwake = (int)(unsigned long)args->timeout;
 596                 td->td_retval[0] = futex_requeue(f, args->val, f2, nrwake);
 597                 futex_put(f2, NULL);
 598                 futex_put(f, NULL);
 599                 break;
 600
 601         case LINUX_FUTEX_WAKE_OP:
 602
 603                 LINUX_CTR5(sys_futex, "WAKE_OP "
 604                     "uaddr %p op %d val %x uaddr2 %p val3 %x",
 605                     args->uaddr, args->op, args->val,
 606                     args->uaddr2, args->val3);
 607
 608 #ifdef DEBUG
 609                 if (ldebug(sys_futex))
 610                         printf(ARGS(sys_futex, "futex_wake_op "
 611                             "uaddr %p op %d val %x uaddr2 %p val3 %x"),
 612                             args->uaddr, args->op, args->val,
 613                             args->uaddr2, args->val3);
 614 #endif
 615                 error = futex_get(args->uaddr, NULL, &f, flags);
 616                 if (error)
 617                         return (error);
 618                 if (args->uaddr != args->uaddr2)
 619                         error = futex_get(args->uaddr2, NULL, &f2, flags);
 620                 if (error) {
 621                         futex_put(f, NULL);
 622                         return (error);
 623                 }
 624
 625                 /*
 626                  * This function returns positive number as results and
 627                  * negative as errors
 628                  */
 629                 op_ret = futex_atomic_op(td, args->val3, args->uaddr2);
 630
 631                 if (op_ret < 0) {
 632                         /* XXX: We don't handle the EFAULT yet. */
 633                         if (op_ret != -EFAULT) {
 634                                 if (f2 != NULL)
 635                                         futex_put(f2, NULL);
 636                                 futex_put(f, NULL);
 637                                 return (-op_ret);
 638                         }
 639                         if (f2 != NULL)
 640                                 futex_put(f2, NULL);
 641                         futex_put(f, NULL);
 642                         return (EFAULT);
 643                 }
 644
 645                 ret = futex_wake(f, args->val, args->val3);
 646
 647                 if (op_ret > 0) {
 648                         op_ret = 0;
 649                         nrwake = (int)(unsigned long)args->timeout;
 650
 651                         if (f2 != NULL)
 652                                 op_ret += futex_wake(f2, nrwake, args->val3);
 653                         else
 654                                 op_ret += futex_wake(f, nrwake, args->val3);
 655                         ret += op_ret;
 656
 657                 }
 658                 if (f2 != NULL)
 659                         futex_put(f2, NULL);
 660                 futex_put(f, NULL);
 661                 td->td_retval[0] = ret;
 662                 break;
 663
 664         case LINUX_FUTEX_LOCK_PI:
 665                 /* not yet implemented */
 666                 linux_msg(td,
 667                           "linux_sys_futex: "
 668                           "op LINUX_FUTEX_LOCK_PI not implemented\n");
 669                 return (ENOSYS);
 670
 671         case LINUX_FUTEX_UNLOCK_PI:
 672                 /* not yet implemented */
 673                 linux_msg(td,
 674                           "linux_sys_futex: "
 675                           "op LINUX_FUTEX_UNLOCK_PI not implemented\n");
 676                 return (ENOSYS);
 677
 678         case LINUX_FUTEX_TRYLOCK_PI:
 679                 /* not yet implemented */
 680                 linux_msg(td,
 681                           "linux_sys_futex: "
 682                           "op LINUX_FUTEX_TRYLOCK_PI not implemented\n");
 683                 return (ENOSYS);
 684
 685         case LINUX_FUTEX_REQUEUE:
 686
 687                 /*
 688                  * Glibc does not use this operation since version 2.3.3,
 689                  * as it is racy and replaced by FUTEX_CMP_REQUEUE operation.
 690                  * Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when
 691                  * FUTEX_REQUEUE returned EINVAL.
 692                  */
 693                 em = em_find(td->td_proc, EMUL_DONTLOCK);
 694                 if ((em->flags & LINUX_XDEPR_REQUEUEOP) == 0) {
 695                         linux_msg(td,
 696                                   "linux_sys_futex: "
 697                                   "unsupported futex_requeue op\n");
 698                         em->flags |= LINUX_XDEPR_REQUEUEOP;
 699                 }
 700                 return (EINVAL);
 701
 702         case LINUX_FUTEX_WAIT_REQUEUE_PI:
 703                 /* not yet implemented */
 704                 linux_msg(td,
 705                           "linux_sys_futex: "
 706                           "op FUTEX_WAIT_REQUEUE_PI not implemented\n");
 707                 return (ENOSYS);
 708
 709         case LINUX_FUTEX_CMP_REQUEUE_PI:
 710                 /* not yet implemented */
 711                 linux_msg(td,
 712                             "linux_sys_futex: "
 713                             "op LINUX_FUTEX_CMP_REQUEUE_PI not implemented\n");
 714                 return (ENOSYS);
 715
 716         default:
 717                 linux_msg(td,
 718                           "linux_sys_futex: unknown op %d\n", args->op);
 719                 return (ENOSYS);
 720         }
 721
 722         return (error);
 723 }
 724
 725 int
 726 linux_set_robust_list(struct thread *td, struct linux_set_robust_list_args *args)
 727 {
 728         struct linux_emuldata *em;
 729
 730 #ifdef DEBUG
 731         if (ldebug(set_robust_list))
 732                 printf(ARGS(set_robust_list, "head %p len %d"),
 733                     args->head, args->len);
 734 #endif
 735
 736         if (args->len != sizeof(struct linux_robust_list_head))
 737                 return (EINVAL);
 738
 739         em = em_find(td->td_proc, EMUL_DOLOCK);
 740         em->robust_futexes = args->head;
 741         EMUL_UNLOCK(&emul_lock);
 742
 743         return (0);
 744 }
 745
 746 int
 747 linux_get_robust_list(struct thread *td, struct linux_get_robust_list_args *args)
 748 {
 749         struct linux_emuldata *em;
 750         struct linux_robust_list_head *head;
 751         l_size_t len = sizeof(struct linux_robust_list_head);
 752         int error = 0;
 753
 754 #ifdef  DEBUG
 755         if (ldebug(get_robust_list))
 756                 printf(ARGS(get_robust_list, ""));
 757 #endif
 758
 759         if (!args->pid) {
 760                 em = em_find(td->td_proc, EMUL_DONTLOCK);
 761                 head = em->robust_futexes;
 762         } else {
 763                 struct proc *p;
 764
 765                 p = pfind(args->pid);
 766                 if (p == NULL)
 767                         return (ESRCH);
 768
 769                 em = em_find(p, EMUL_DONTLOCK);
 770                 /* XXX: ptrace? */
 771                 if (priv_check(td, PRIV_CRED_SETUID) ||
 772                     priv_check(td, PRIV_CRED_SETEUID) ||
 773                     p_candebug(td, p)) {
 774                         PROC_UNLOCK(p);
 775                         return (EPERM);
 776                 }
 777                 head = em->robust_futexes;
 778
 779                 PROC_UNLOCK(p);
 780         }
 781
 782         error = copyout(&len, args->len, sizeof(l_size_t));
 783         if (error)
 784                 return (EFAULT);
 785
 786         error = copyout(head, args->head, sizeof(struct linux_robust_list_head));
 787
 788         return (error);
 789 }
 790
 791 static int
 792 handle_futex_death(struct proc *p, uint32_t *uaddr, int pi)
 793 {
 794         uint32_t uval, nval, mval;
 795         struct futex *f;
 796         int error;
 797
 798 retry:
 799         if (copyin(uaddr, &uval, 4))
 800                 return (EFAULT);
 801         if ((uval & FUTEX_TID_MASK) == p->p_pid) {
 802                 mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED;
 803                 nval = casuword32(uaddr, uval, mval);
 804
 805                 if (nval == -1)
 806                         return (EFAULT);
 807
 808                 if (nval != uval)
 809                         goto retry;
 810
 811                 if (!pi && (uval & FUTEX_WAITERS)) {
 812                         error = futex_get(uaddr, NULL, &f,
 813                             FUTEX_DONTCREATE | FUTEX_SHARED);
 814                         if (error)
 815                                 return (error);
 816                         if (f != NULL) {
 817                                 futex_wake(f, 1, FUTEX_BITSET_MATCH_ANY);
 818                                 futex_put(f, NULL);
 819                         }
 820                 }
 821         }
 822
 823         return (0);
 824 }
 825
 826 static int
 827 fetch_robust_entry(struct linux_robust_list **entry,
 828     struct linux_robust_list **head, int *pi)
 829 {
 830         l_ulong uentry;
 831
 832         if (copyin((const void *)head, &uentry, sizeof(l_ulong)))
 833                 return (EFAULT);
 834
 835         *entry = (void *)(uentry & ~1UL);
 836         *pi = uentry & 1;
 837
 838         return (0);
 839 }
 840
 841 /* This walks the list of robust futexes releasing them. */
 842 void
 843 release_futexes(struct proc *p)
 844 {
 845         struct linux_robust_list_head *head = NULL;
 846         struct linux_robust_list *entry, *next_entry, *pending;
 847         unsigned int limit = 2048, pi, next_pi, pip;
 848         struct linux_emuldata *em;
 849         l_long futex_offset;
 850         int rc;
 851
 852         em = em_find(p, EMUL_DONTLOCK);
 853         head = em->robust_futexes;
 854
 855         if (head == NULL)
 856                 return;
 857
 858         if (fetch_robust_entry(&entry, PTRIN(&head->list.next), &pi))
 859                 return;
 860
 861         if (copyin(&head->futex_offset, &futex_offset, sizeof(futex_offset)))
 862                 return;
 863
 864         if (fetch_robust_entry(&pending, PTRIN(&head->pending_list), &pip))
 865                 return;
 866
 867         while (entry != &head->list) {
 868                 rc = fetch_robust_entry(&next_entry, PTRIN(&entry->next), &next_pi);
 869
 870                 if (entry != pending)
 871                         if (handle_futex_death(p, (uint32_t *)entry + futex_offset, pi))
 872                                 return;
 873                 if (rc)
 874                         return;
 875
 876                 entry = next_entry;
 877                 pi = next_pi;
 878
 879                 if (!--limit)
 880                         break;
 881
 882                 sched_relinquish(curthread);
 883         }
 884
 885         if (pending)
 886                 handle_futex_death(p, (uint32_t *)pending + futex_offset, pip);
 887 }