sys/emulation/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 "opt_compat.h"
  35
  36 #include <sys/param.h>
  37 #include <sys/systm.h>
  38 #include <sys/imgact.h>
  39 #include <sys/imgact_aout.h>
  40 #include <sys/imgact_elf.h>
  41 #include <sys/kern_syscall.h>
  42 #include <sys/lock.h>
  43 #include <sys/malloc.h>
  44 #include <sys/proc.h>
  45 #include <sys/signalvar.h>
  46 #include <sys/sysent.h>
  47 #include <sys/sysproto.h>
  48 #include <sys/priv.h>
  49 #include <sys/lock.h>
  50 #include <sys/spinlock2.h>
  51
  52 #include <vm/vm.h>
  53 #include <vm/vm_param.h>
  54 #include <vm/vm_page.h>
  55 #include <vm/vm_extern.h>
  56 #include <sys/exec.h>
  57 #include <sys/kernel.h>
  58 #include <sys/module.h>
  59 #include <machine/cpu.h>
  60 #include <machine/limits.h>
  61
  62 #include "i386/linux.h"
  63 #include "i386/linux_proto.h"
  64 #include "linux_signal.h"
  65 #include "linux_util.h"
  66 #include "linux_emuldata.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 lock     f_lck;
  81         uint32_t        *f_uaddr;
  82         uint32_t        f_refcount;
  83         LIST_ENTRY(futex) f_list;
  84         TAILQ_HEAD(lf_waiting_proc, waiting_proc) f_waiting_proc;
  85 };
  86
  87 struct futex_list futex_list;
  88
  89 #if 0
  90 #define FUTEX_LOCK(f)           spin_lock(&(f)->f_lck)
  91 #define FUTEX_UNLOCK(f)         spin_unlock(&(f)->f_lck)
  92 #define FUTEX_INIT(f)           spin_init(&(f)->f_lck)
  93 #define FUTEX_SLEEP(f, id, flag, wm, timo)      ssleep((id), &(f)->f_lck, (flag), (wm), (timo))
  94 #endif
  95
  96 #define FUTEX_LOCK(f)           lockmgr(&(f)->f_lck, LK_EXCLUSIVE)
  97 #define FUTEX_UNLOCK(f)         lockmgr(&(f)->f_lck, LK_RELEASE)
  98 #define FUTEX_INIT(f)           lockinit(&(f)->f_lck, "ftlk", 0, LK_CANRECURSE)
  99 #define FUTEX_DESTROY(f)        lockuninit(&(f)->f_lck)
 100 #define FUTEX_ASSERT_LOCKED(f)  KKASSERT(lockstatus(&(f)->f_lck, curthread) == LK_EXCLUSIVE)
 101 #define FUTEX_SLEEP(f, id, flag, wm, timo)      lksleep((id), &(f)->f_lck, (flag), (wm), (timo))
 102
 103 struct lock futex_mtx;                  /* protects the futex list */
 104 #define FUTEXES_LOCK            lockmgr(&futex_mtx, LK_EXCLUSIVE)
 105 #define FUTEXES_UNLOCK          lockmgr(&futex_mtx, LK_RELEASE)
 106
 107 /* Debug magic to take advantage of freebsd's mess */
 108 #if LINUX_DEBUG
 109 #define LINUX_CTR_PREFIX
 110 #else
 111 #define LINUX_CTR_PREFIX        while (0)
 112 #endif
 113
 114 #define LINUX_CTR1(a,b,c)       LINUX_CTR_PREFIX kprintf("linux_futex: " b "\n",c)
 115 #define LINUX_CTR2(a,b,c,d)     LINUX_CTR_PREFIX kprintf("linux_futex: " b "\n",c,d)
 116 #define LINUX_CTR3(a,b,c,d,e)   LINUX_CTR_PREFIX kprintf("linux_futex: " b "\n",c,d,e)
 117 #define LINUX_CTR4(a,b,c,d,e,f) LINUX_CTR_PREFIX kprintf("linux_futex: " b "\n",c,d,e,f)
 118 #define LINUX_CTR5(a,b,c,d,e,f,g)       LINUX_CTR_PREFIX kprintf("linux_futex: " b "\n",c,d,e,f,g)
 119
 120
 121
 122 /* flags for futex_get() */
 123 #define FUTEX_CREATE_WP         0x1     /* create waiting_proc */
 124 #define FUTEX_DONTCREATE        0x2     /* don't create futex if not exists */
 125 #define FUTEX_DONTEXISTS        0x4     /* return EINVAL if futex exists */
 126
 127 /* wp_flags */
 128 #define FUTEX_WP_REQUEUED       0x1     /* wp requeued - wp moved from wp_list
 129                                          * of futex where thread sleep to wp_list
 130                                          * of another futex.
 131                                          */
 132 #define FUTEX_WP_REMOVED        0x2     /* wp is woken up and removed from futex
 133                                          * wp_list to prevent double wakeup.
 134                                          */
 135
 136 /* support.s */
 137 int futex_xchgl(int oparg, uint32_t *uaddr, int *oldval);
 138 int futex_addl(int oparg, uint32_t *uaddr, int *oldval);
 139 int futex_orl(int oparg, uint32_t *uaddr, int *oldval);
 140 int futex_andl(int oparg, uint32_t *uaddr, int *oldval);
 141 int futex_xorl(int oparg, uint32_t *uaddr, int *oldval);
 142
 143 static void
 144 futex_put(struct futex *f, struct waiting_proc *wp)
 145 {
 146         FUTEX_ASSERT_LOCKED(f);
 147         if (wp != NULL) {
 148                 if ((wp->wp_flags & FUTEX_WP_REMOVED) == 0)
 149                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
 150                 kfree(wp, M_FUTEX_WP);
 151         }
 152
 153         FUTEXES_LOCK;
 154         if (--f->f_refcount == 0) {
 155                 LIST_REMOVE(f, f_list);
 156                 FUTEXES_UNLOCK;
 157                 FUTEX_UNLOCK(f);
 158
 159                 LINUX_CTR2(sys_futex, "futex_put destroy uaddr %p ref %d",
 160                     f->f_uaddr, f->f_refcount);
 161                 FUTEX_DESTROY(f);
 162                 kfree(f, M_FUTEX);
 163                 return;
 164         }
 165
 166         LINUX_CTR2(sys_futex, "futex_put uaddr %p ref %d",
 167             f->f_uaddr, f->f_refcount);
 168         FUTEXES_UNLOCK;
 169         FUTEX_UNLOCK(f);
 170 }
 171
 172 static int
 173 futex_get0(uint32_t *uaddr, struct futex **newf, uint32_t flags)
 174 {
 175         struct futex *f, *tmpf;
 176
 177         *newf = tmpf = NULL;
 178
 179 retry:
 180         FUTEXES_LOCK;
 181         LIST_FOREACH(f, &futex_list, f_list) {
 182                 if (f->f_uaddr == uaddr) {
 183                         if (tmpf != NULL) {
 184                                 FUTEX_UNLOCK(tmpf);
 185                                 FUTEX_DESTROY(tmpf);
 186                                 kfree(tmpf, M_FUTEX);
 187                         }
 188                         if (flags & FUTEX_DONTEXISTS) {
 189                                 FUTEXES_UNLOCK;
 190                                 return (EINVAL);
 191                         }
 192
 193                         /*
 194                          * Increment refcount of the found futex to
 195                          * prevent it from deallocation before FUTEX_LOCK()
 196                          */
 197                         ++f->f_refcount;
 198                         FUTEXES_UNLOCK;
 199
 200                         FUTEX_LOCK(f);
 201                         *newf = f;
 202                         LINUX_CTR2(sys_futex, "futex_get uaddr %p ref %d",
 203                             uaddr, f->f_refcount);
 204                         return (0);
 205                 }
 206         }
 207
 208         if (flags & FUTEX_DONTCREATE) {
 209                 FUTEXES_UNLOCK;
 210                 LINUX_CTR1(sys_futex, "futex_get uaddr %p null", uaddr);
 211                 return (0);
 212         }
 213
 214         if (tmpf == NULL) {
 215                 FUTEXES_UNLOCK;
 216                 tmpf = kmalloc(sizeof(*tmpf), M_FUTEX, M_WAITOK | M_ZERO);
 217                 tmpf->f_uaddr = uaddr;
 218                 tmpf->f_refcount = 1;
 219                 FUTEX_INIT(tmpf);
 220                 TAILQ_INIT(&tmpf->f_waiting_proc);
 221
 222                 /*
 223                  * Lock the new futex before an insert into the futex_list
 224                  * to prevent futex usage by other.
 225                  */
 226                 FUTEX_LOCK(tmpf);
 227                 goto retry;
 228         }
 229
 230         LIST_INSERT_HEAD(&futex_list, tmpf, f_list);
 231         FUTEXES_UNLOCK;
 232
 233         LINUX_CTR2(sys_futex, "futex_get uaddr %p ref %d new",
 234             uaddr, tmpf->f_refcount);
 235         *newf = tmpf;
 236         return (0);
 237 }
 238
 239 static int
 240 futex_get(uint32_t *uaddr, struct waiting_proc **wp, struct futex **f,
 241     uint32_t flags)
 242 {
 243         int error;
 244
 245         if (flags & FUTEX_CREATE_WP) {
 246                 *wp = kmalloc(sizeof(struct waiting_proc), M_FUTEX_WP, M_WAITOK);
 247                 (*wp)->wp_flags = 0;
 248         }
 249         error = futex_get0(uaddr, f, flags);
 250         if (error) {
 251                 if (flags & FUTEX_CREATE_WP)
 252                         kfree(*wp, M_FUTEX_WP);
 253                 return (error);
 254         }
 255         if (flags & FUTEX_CREATE_WP) {
 256                 TAILQ_INSERT_HEAD(&(*f)->f_waiting_proc, *wp, wp_list);
 257                 (*wp)->wp_futex = *f;
 258         }
 259
 260         return (error);
 261 }
 262
 263 static int
 264 futex_sleep(struct futex *f, struct waiting_proc *wp, int timeout)
 265 {
 266         int error;
 267
 268         FUTEX_ASSERT_LOCKED(f);
 269         LINUX_CTR4(sys_futex, "futex_sleep enter uaddr %p wp %p timo %d ref %d",
 270             f->f_uaddr, wp, timeout, f->f_refcount);
 271         error = FUTEX_SLEEP(f, wp, PCATCH, "futex", timeout);
 272         if (wp->wp_flags & FUTEX_WP_REQUEUED) {
 273                 KASSERT(f != wp->wp_futex, ("futex != wp_futex"));
 274                 LINUX_CTR5(sys_futex, "futex_sleep out error %d uaddr %p w"
 275                     " %p requeued uaddr %p ref %d",
 276                     error, f->f_uaddr, wp, wp->wp_futex->f_uaddr,
 277                     wp->wp_futex->f_refcount);
 278                 futex_put(f, NULL);
 279                 f = wp->wp_futex;
 280                 FUTEX_LOCK(f);
 281         }
 282
 283         futex_put(f, wp);
 284         return (error);
 285 }
 286
 287 static int
 288 futex_wake(struct futex *f, int n)
 289 {
 290         struct waiting_proc *wp, *wpt;
 291         int count = 0;
 292
 293         FUTEX_ASSERT_LOCKED(f);
 294         TAILQ_FOREACH_MUTABLE(wp, &f->f_waiting_proc, wp_list, wpt) {
 295                 LINUX_CTR3(sys_futex, "futex_wake uaddr %p wp %p ref %d",
 296                     f->f_uaddr, wp, f->f_refcount);
 297                 wp->wp_flags |= FUTEX_WP_REMOVED;
 298                 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
 299                 wakeup_one(wp);
 300                 if (++count == n)
 301                         break;
 302         }
 303
 304         return (count);
 305 }
 306
 307 static int
 308 futex_requeue(struct futex *f, int n, struct futex *f2, int n2)
 309 {
 310         struct waiting_proc *wp, *wpt;
 311         int count = 0;
 312
 313         FUTEX_ASSERT_LOCKED(f);
 314         FUTEX_ASSERT_LOCKED(f2);
 315
 316         TAILQ_FOREACH_MUTABLE(wp, &f->f_waiting_proc, wp_list, wpt) {
 317                 if (++count <= n) {
 318                         LINUX_CTR2(sys_futex, "futex_req_wake uaddr %p wp %p",
 319                             f->f_uaddr, wp);
 320                         wp->wp_flags |= FUTEX_WP_REMOVED;
 321                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
 322                         wakeup_one(wp);
 323                 } else {
 324                         LINUX_CTR3(sys_futex, "futex_requeue uaddr %p wp %p to %p",
 325                             f->f_uaddr, wp, f2->f_uaddr);
 326                         wp->wp_flags |= FUTEX_WP_REQUEUED;
 327                         /* Move wp to wp_list of f2 futex */
 328                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
 329                         TAILQ_INSERT_HEAD(&f2->f_waiting_proc, wp, wp_list);
 330
 331                         /*
 332                          * Thread which sleeps on wp after waking should
 333                          * acquire f2 lock, so increment refcount of f2 to
 334                          * prevent it from premature deallocation.
 335                          */
 336                         wp->wp_futex = f2;
 337                         FUTEXES_LOCK;
 338                         ++f2->f_refcount;
 339                         FUTEXES_UNLOCK;
 340                         if (count - n >= n2)
 341                                 break;
 342                 }
 343         }
 344
 345         return (count);
 346 }
 347
 348 static int
 349 futex_wait(struct futex *f, struct waiting_proc *wp, struct l_timespec *ts)
 350 {
 351         struct l_timespec timeout;
 352         struct timeval tv;
 353         int timeout_hz;
 354         int error;
 355
 356         if (ts != NULL) {
 357                 error = copyin(ts, &timeout, sizeof(timeout));
 358                 if (error)
 359                         return (error);
 360                 TIMESPEC_TO_TIMEVAL(&tv, &timeout);
 361                 error = itimerfix(&tv);
 362                 if (error)
 363                         return (error);
 364                 timeout_hz = tvtohz_high(&tv);
 365         } else {
 366                 timeout_hz = 0;
 367         }
 368
 369         error = futex_sleep(f, wp, timeout_hz);
 370         if (error == EWOULDBLOCK)
 371                 error = ETIMEDOUT;
 372
 373         return (error);
 374 }
 375
 376 static int
 377 futex_atomic_op(struct proc *p, int encoded_op, uint32_t *uaddr)
 378 {
 379         int op = (encoded_op >> 28) & 7;
 380         int cmp = (encoded_op >> 24) & 15;
 381         int oparg = (encoded_op << 8) >> 20;
 382         int cmparg = (encoded_op << 20) >> 20;
 383         int oldval = 0, ret;
 384
 385         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
 386                 oparg = 1 << oparg;
 387
 388 #ifdef DEBUG
 389         if (ldebug(sys_futex))
 390                 kprintf("futex_atomic_op: op = %d, cmp = %d, oparg = %x, "
 391                        "cmparg = %x, uaddr = %p\n",
 392                        op, cmp, oparg, cmparg, uaddr);
 393 #endif
 394         /* XXX: linux verifies access here and returns EFAULT */
 395
 396         switch (op) {
 397         case FUTEX_OP_SET:
 398                 ret = futex_xchgl(oparg, uaddr, &oldval);
 399                 break;
 400         case FUTEX_OP_ADD:
 401                 ret = futex_addl(oparg, uaddr, &oldval);
 402                 break;
 403         case FUTEX_OP_OR:
 404                 ret = futex_orl(oparg, uaddr, &oldval);
 405                 break;
 406         case FUTEX_OP_ANDN:
 407                 ret = futex_andl(~oparg, uaddr, &oldval);
 408                 break;
 409         case FUTEX_OP_XOR:
 410                 ret = futex_xorl(oparg, uaddr, &oldval);
 411                 break;
 412         default:
 413                 ret = -ENOSYS;
 414                 break;
 415         }
 416
 417         if (ret)
 418                 return (ret);
 419
 420         switch (cmp) {
 421         case FUTEX_OP_CMP_EQ:
 422                 return (oldval == cmparg);
 423         case FUTEX_OP_CMP_NE:
 424                 return (oldval != cmparg);
 425         case FUTEX_OP_CMP_LT:
 426                 return (oldval < cmparg);
 427         case FUTEX_OP_CMP_GE:
 428                 return (oldval >= cmparg);
 429         case FUTEX_OP_CMP_LE:
 430                 return (oldval <= cmparg);
 431         case FUTEX_OP_CMP_GT:
 432                 return (oldval > cmparg);
 433         default:
 434                 return (-ENOSYS);
 435         }
 436 }
 437
 438 int
 439 sys_linux_sys_futex(struct linux_sys_futex_args *args)
 440 {
 441         int op_ret, val, ret, nrwake;
 442         struct waiting_proc *wp;
 443         struct futex *f, *f2 = NULL;
 444         int error = 0;
 445
 446         /*
 447          * Our implementation provides only privates futexes. Most of the apps
 448          * should use private futexes but don't claim so. Therefore we treat
 449          * all futexes as private by clearing the FUTEX_PRIVATE_FLAG. It works
 450          * in most cases (ie. when futexes are not shared on file descriptor
 451          * or between different processes.).
 452          */
 453         args->op = (args->op & ~LINUX_FUTEX_PRIVATE_FLAG);
 454
 455         switch (args->op) {
 456         case LINUX_FUTEX_WAIT:
 457                 LINUX_CTR2(sys_futex, "WAIT val %d uaddr %p",
 458                     args->val, args->uaddr);
 459 #ifdef DEBUG
 460                 if (ldebug(sys_futex))
 461                         kprintf(ARGS(sys_futex, "futex_wait val %d uaddr %p"),
 462                             args->val, args->uaddr);
 463 #endif
 464                 error = futex_get(args->uaddr, &wp, &f, FUTEX_CREATE_WP);
 465                 if (error)
 466                         return (error);
 467                 error = copyin(args->uaddr, &val, sizeof(val));
 468                 if (error) {
 469                         LINUX_CTR1(sys_futex, "WAIT copyin failed %d",
 470                             error);
 471                         futex_put(f, wp);
 472                         return (error);
 473                 }
 474                 if (val != args->val) {
 475                         LINUX_CTR3(sys_futex, "WAIT uaddr %p val %d != uval %d",
 476                             args->uaddr, args->val, val);
 477                         futex_put(f, wp);
 478                         return (EWOULDBLOCK);
 479                 }
 480
 481                 error = futex_wait(f, wp, args->timeout);
 482                 break;
 483
 484         case LINUX_FUTEX_WAKE:
 485
 486                 LINUX_CTR2(sys_futex, "WAKE val %d uaddr %p",
 487                     args->val, args->uaddr);
 488
 489                 /*
 490                  * XXX: Linux is able to cope with different addresses
 491                  * corresponding to the same mapped memory in the sleeping
 492                  * and waker process(es).
 493                  */
 494 #ifdef DEBUG
 495                 if (ldebug(sys_futex))
 496                         kprintf(ARGS(sys_futex, "futex_wake val %d uaddr %p"),
 497                             args->val, args->uaddr);
 498 #endif
 499                 error = futex_get(args->uaddr, NULL, &f, FUTEX_DONTCREATE);
 500                 if (error)
 501                         return (error);
 502                 if (f == NULL) {
 503                         args->sysmsg_iresult = 0;
 504                         return (error);
 505                 }
 506                 args->sysmsg_iresult = futex_wake(f, args->val);
 507                 futex_put(f, NULL);
 508                 break;
 509
 510         case LINUX_FUTEX_CMP_REQUEUE:
 511
 512                 LINUX_CTR5(sys_futex, "CMP_REQUEUE uaddr %p "
 513                     "val %d val3 %d uaddr2 %p val2 %d",
 514                     args->uaddr, args->val, args->val3, args->uaddr2,
 515                     (int)(unsigned long)args->timeout);
 516
 517 #ifdef DEBUG
 518                 if (ldebug(sys_futex))
 519                         kprintf(ARGS(sys_futex, "futex_cmp_requeue uaddr %p "
 520                             "val %d val3 %d uaddr2 %p val2 %d"),
 521                             args->uaddr, args->val, args->val3, args->uaddr2,
 522                             (int)(unsigned long)args->timeout);
 523 #endif
 524                 /*
 525                  * Linux allows this, we would not, it is an incorrect
 526                  * usage of declared ABI, so return EINVAL.
 527                  */
 528                 if (args->uaddr == args->uaddr2)
 529                         return (EINVAL);
 530                 error = futex_get0(args->uaddr, &f, 0);
 531                 if (error)
 532                         return (error);
 533
 534                 /*
 535                  * To avoid deadlocks return EINVAL if second futex
 536                  * exists at this time. Otherwise create the new futex
 537                  * and ignore false positive LOR which thus happens.
 538                  *
 539                  * Glibc fall back to FUTEX_WAKE in case of any error
 540                  * returned by FUTEX_CMP_REQUEUE.
 541                  */
 542                 error = futex_get0(args->uaddr2, &f2, FUTEX_DONTEXISTS);
 543                 if (error) {
 544                         futex_put(f, NULL);
 545                         return (error);
 546                 }
 547                 error = copyin(args->uaddr, &val, sizeof(val));
 548                 if (error) {
 549                         LINUX_CTR1(sys_futex, "CMP_REQUEUE copyin failed %d",
 550                             error);
 551                         futex_put(f2, NULL);
 552                         futex_put(f, NULL);
 553                         return (error);
 554                 }
 555                 if (val != args->val3) {
 556                         LINUX_CTR2(sys_futex, "CMP_REQUEUE val %d != uval %d",
 557                             args->val, val);
 558                         futex_put(f2, NULL);
 559                         futex_put(f, NULL);
 560                         return (EAGAIN);
 561                 }
 562
 563                 nrwake = (int)(unsigned long)args->timeout;
 564                 args->sysmsg_iresult = futex_requeue(f, args->val, f2, nrwake);
 565                 futex_put(f2, NULL);
 566                 futex_put(f, NULL);
 567                 break;
 568
 569         case LINUX_FUTEX_WAKE_OP:
 570
 571                 LINUX_CTR5(sys_futex, "WAKE_OP "
 572                     "uaddr %p op %d val %x uaddr2 %p val3 %x",
 573                     args->uaddr, args->op, args->val,
 574                     args->uaddr2, args->val3);
 575
 576 #ifdef DEBUG
 577                 if (ldebug(sys_futex))
 578                         kprintf(ARGS(sys_futex, "futex_wake_op "
 579                             "uaddr %p op %d val %x uaddr2 %p val3 %x"),
 580                             args->uaddr, args->op, args->val,
 581                             args->uaddr2, args->val3);
 582 #endif
 583                 error = futex_get0(args->uaddr, &f, 0);
 584                 if (error)
 585                         return (error);
 586                 if (args->uaddr != args->uaddr2)
 587                         error = futex_get0(args->uaddr2, &f2, 0);
 588                 if (error) {
 589                         futex_put(f, NULL);
 590                         return (error);
 591                 }
 592
 593                 /*
 594                  * This function returns positive number as results and
 595                  * negative as errors
 596                  */
 597                 op_ret = futex_atomic_op(curproc, args->val3, args->uaddr2);
 598
 599                 if (op_ret < 0) {
 600                         /* XXX: We don't handle the EFAULT yet. */
 601                         if (op_ret != -EFAULT) {
 602                                 if (f2 != NULL)
 603                                         futex_put(f2, NULL);
 604                                 futex_put(f, NULL);
 605                                 return (-op_ret);
 606                         }
 607                         if (f2 != NULL)
 608                                 futex_put(f2, NULL);
 609                         futex_put(f, NULL);
 610                         return (EFAULT);
 611                 }
 612
 613                 ret = futex_wake(f, args->val);
 614
 615                 if (op_ret > 0) {
 616                         op_ret = 0;
 617                         nrwake = (int)(unsigned long)args->timeout;
 618
 619                         if (f2 != NULL)
 620                                 op_ret += futex_wake(f2, nrwake);
 621                         else
 622                                 op_ret += futex_wake(f, nrwake);
 623                         ret += op_ret;
 624
 625                 }
 626                 if (f2 != NULL)
 627                         futex_put(f2, NULL);
 628                 futex_put(f, NULL);
 629                 args->sysmsg_iresult = ret;
 630                 break;
 631
 632         case LINUX_FUTEX_LOCK_PI:
 633                 /* not yet implemented */
 634                 return (ENOSYS);
 635
 636         case LINUX_FUTEX_UNLOCK_PI:
 637                 /* not yet implemented */
 638                 return (ENOSYS);
 639
 640         case LINUX_FUTEX_TRYLOCK_PI:
 641                 /* not yet implemented */
 642                 return (ENOSYS);
 643
 644         case LINUX_FUTEX_REQUEUE:
 645
 646                 /*
 647                  * Glibc does not use this operation since version 2.3.3,
 648                  * as it is racy and replaced by FUTEX_CMP_REQUEUE operation.
 649                  * Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when
 650                  * FUTEX_REQUEUE returned EINVAL.
 651                  */
 652                 return (EINVAL);
 653
 654         default:
 655                 kprintf("linux_sys_futex: unknown op %d\n", args->op);
 656                 return (ENOSYS);
 657         }
 658
 659         return (error);
 660 }
 661
 662 int
 663 sys_linux_set_robust_list(struct linux_set_robust_list_args *args)
 664 {
 665 #ifdef DEBUG
 666         if (ldebug(set_robust_list))
 667                 kprintf(ARGS(set_robust_list, "head %p len %d"),
 668                     args->head, args->len);
 669 #endif
 670
 671         if (args->len != sizeof(struct linux_robust_list_head))
 672                 return (EINVAL);
 673
 674         emuldata_set_robust(curproc, args->head);
 675
 676         return (0);
 677 }
 678
 679
 680
 681 int
 682 sys_linux_get_robust_list(struct linux_get_robust_list_args *args)
 683 {
 684         struct linux_emuldata *em;
 685         struct linux_robust_list_head empty_head;
 686         struct linux_robust_list_head *head;
 687         l_size_t len = sizeof(struct linux_robust_list_head);
 688         int error = 0;
 689
 690 #ifdef  DEBUG
 691         if (ldebug(get_robust_list))
 692                 kprintf(ARGS(get_robust_list, ""));
 693 #endif
 694
 695         if (args->pid == 0) {
 696                 EMUL_LOCK();
 697                 em = emuldata_get(curproc);
 698                 KKASSERT(em != NULL);
 699                 if (em->robust_futexes == NULL) {
 700                         bzero(&empty_head, sizeof(empty_head));
 701                         head = &empty_head;
 702                 } else {
 703                         head = em->robust_futexes;
 704                 }
 705                 EMUL_UNLOCK();
 706         } else {
 707                 struct proc *p;
 708
 709                 p = pfind(args->pid);
 710                 if (p == NULL) {
 711                         return (ESRCH);
 712                 }
 713
 714                 EMUL_LOCK();
 715                 em = emuldata_get(p);
 716                 head = em->robust_futexes;
 717                 EMUL_UNLOCK();
 718                 /* XXX: ptrace? p_candebug?*/
 719                 if (priv_check(curthread, PRIV_CRED_SETUID) ||
 720                     priv_check(curthread, PRIV_CRED_SETEUID)/* ||
 721                     p_candebug(curproc, p) */) {
 722                         PRELE(p);
 723                         return (EPERM);
 724                 }
 725                 PRELE(p);
 726         }
 727
 728         error = copyout(&len, args->len, sizeof(l_size_t));
 729         if (error)
 730                 return (EFAULT);
 731
 732         error = copyout(head, args->head, sizeof(struct linux_robust_list_head));
 733
 734         return (error);
 735 }
 736
 737 static int
 738 handle_futex_death(struct proc *p, uint32_t *uaddr, int pi)
 739 {
 740         uint32_t uval, nval, mval;
 741         struct futex *f;
 742         int error;
 743
 744 retry:
 745         if (copyin(uaddr, &uval, 4))
 746                 return (EFAULT);
 747         if ((uval & FUTEX_TID_MASK) == p->p_pid) {
 748                 mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED;
 749                 nval = casuword((ulong *)uaddr, uval, mval);
 750
 751                 if (nval == -1)
 752                         return (EFAULT);
 753
 754                 if (nval != uval)
 755                         goto retry;
 756
 757                 if (!pi && (uval & FUTEX_WAITERS)) {
 758                         error = futex_get(uaddr, NULL, &f,
 759                             FUTEX_DONTCREATE);
 760                         if (error)
 761                                 return (error);
 762                         if (f != NULL) {
 763                                 futex_wake(f, 1);
 764                                 futex_put(f, NULL);
 765                         }
 766                 }
 767         }
 768
 769         return (0);
 770 }
 771
 772 static int
 773 fetch_robust_entry(struct linux_robust_list **entry,
 774     struct linux_robust_list **head, int *pi)
 775 {
 776         l_ulong uentry;
 777
 778         if (copyin((const void *)head, &uentry, sizeof(l_ulong)))
 779                 return (EFAULT);
 780
 781         *entry = (void *)(uentry & ~1UL);
 782         *pi = uentry & 1;
 783
 784         return (0);
 785 }
 786
 787 /* This walks the list of robust futexes releasing them. */
 788 void
 789 release_futexes(struct proc *p)
 790 {
 791         struct linux_robust_list_head *head = NULL;
 792         struct linux_robust_list *entry, *next_entry, *pending;
 793         unsigned int limit = 2048, pi, next_pi, pip;
 794         struct linux_emuldata *em;
 795         l_long futex_offset;
 796         int rc;
 797
 798         EMUL_LOCK();
 799         KKASSERT(p != NULL);
 800         em = emuldata_get(p);
 801         KKASSERT(em != NULL);
 802         head = em->robust_futexes;
 803         EMUL_UNLOCK();
 804
 805         if (head == NULL)
 806                 return;
 807
 808         if (fetch_robust_entry(&entry, PTRIN(&head->list.next), &pi))
 809                 return;
 810
 811         if (copyin(&head->futex_offset, &futex_offset, sizeof(futex_offset)))
 812                 return;
 813
 814         if (fetch_robust_entry(&pending, PTRIN(&head->pending_list), &pip))
 815                 return;
 816
 817         while (entry != &head->list) {
 818                 rc = fetch_robust_entry(&next_entry, PTRIN(&entry->next), &next_pi);
 819
 820                 if (entry != pending)
 821                         if (handle_futex_death(p, (uint32_t *)entry + futex_offset, pi))
 822                                 return;
 823                 if (rc)
 824                         return;
 825
 826                 entry = next_entry;
 827                 pi = next_pi;
 828
 829                 if (!--limit)
 830                         break;
 831
 832                 /* XXX: not sure about this yield, was sched_relinquish(curthread); */
 833                 lwkt_yield();
 834         }
 835
 836         if (pending)
 837                 handle_futex_death(p, (uint32_t *)pending + futex_offset, pip);
 838 }