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_wr(&(f)->f_lck)
  91 #define FUTEX_UNLOCK(f)         spin_unlock_wr(&(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                         *wp = NULL;
 254                 }
 255                 return (error);
 256         }
 257         if (flags & FUTEX_CREATE_WP) {
 258                 TAILQ_INSERT_HEAD(&(*f)->f_waiting_proc, *wp, wp_list);
 259                 (*wp)->wp_futex = *f;
 260         }
 261
 262         return (error);
 263 }
 264
 265 static int
 266 futex_sleep(struct futex *f, struct waiting_proc *wp, unsigned long timeout)
 267 {
 268         int error;
 269
 270         FUTEX_ASSERT_LOCKED(f);
 271         LINUX_CTR4(sys_futex, "futex_sleep enter uaddr %p wp %p timo %ld ref %d",
 272             f->f_uaddr, wp, timeout, f->f_refcount);
 273         error = FUTEX_SLEEP(f, wp, PCATCH, "futex", timeout);
 274 #if 0
 275         error = ssleep(wp, &f->f_lck, PCATCH, "futex", timeout);
 276         error = sx_sleep(wp, &f->f_lck, PCATCH, "futex", timeout);
 277 #endif
 278         if (wp->wp_flags & FUTEX_WP_REQUEUED) {
 279                 KASSERT(f != wp->wp_futex, ("futex != wp_futex"));
 280                 LINUX_CTR5(sys_futex, "futex_sleep out error %d uaddr %p w"
 281                     " %p requeued uaddr %p ref %d",
 282                     error, f->f_uaddr, wp, wp->wp_futex->f_uaddr,
 283                     wp->wp_futex->f_refcount);
 284                 futex_put(f, NULL);
 285                 f = wp->wp_futex;
 286                 FUTEX_LOCK(f);
 287         }
 288
 289         futex_put(f, wp);
 290         return (error);
 291 }
 292
 293 static int
 294 futex_wake(struct futex *f, int n)
 295 {
 296         struct waiting_proc *wp, *wpt;
 297         int count = 0;
 298
 299         FUTEX_ASSERT_LOCKED(f);
 300         TAILQ_FOREACH_MUTABLE(wp, &f->f_waiting_proc, wp_list, wpt) {
 301                 LINUX_CTR3(sys_futex, "futex_wake uaddr %p wp %p ref %d",
 302                     f->f_uaddr, wp, f->f_refcount);
 303                 wp->wp_flags |= FUTEX_WP_REMOVED;
 304                 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
 305                 wakeup_one(wp);
 306                 if (++count == n)
 307                         break;
 308         }
 309
 310         return (count);
 311 }
 312
 313 static int
 314 futex_requeue(struct futex *f, int n, struct futex *f2, int n2)
 315 {
 316         struct waiting_proc *wp, *wpt;
 317         int count = 0;
 318
 319         FUTEX_ASSERT_LOCKED(f);
 320         FUTEX_ASSERT_LOCKED(f2);
 321
 322         TAILQ_FOREACH_MUTABLE(wp, &f->f_waiting_proc, wp_list, wpt) {
 323                 if (++count <= n) {
 324                         LINUX_CTR2(sys_futex, "futex_req_wake uaddr %p wp %p",
 325                             f->f_uaddr, wp);
 326                         wp->wp_flags |= FUTEX_WP_REMOVED;
 327                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
 328                         wakeup_one(wp);
 329                 } else {
 330                         LINUX_CTR3(sys_futex, "futex_requeue uaddr %p wp %p to %p",
 331                             f->f_uaddr, wp, f2->f_uaddr);
 332                         wp->wp_flags |= FUTEX_WP_REQUEUED;
 333                         /* Move wp to wp_list of f2 futex */
 334                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
 335                         TAILQ_INSERT_HEAD(&f2->f_waiting_proc, wp, wp_list);
 336
 337                         /*
 338                          * Thread which sleeps on wp after waking should
 339                          * acquire f2 lock, so increment refcount of f2 to
 340                          * prevent it from premature deallocation.
 341                          */
 342                         wp->wp_futex = f2;
 343                         FUTEXES_LOCK;
 344                         ++f2->f_refcount;
 345                         FUTEXES_UNLOCK;
 346                         if (count - n >= n2)
 347                                 break;
 348                 }
 349         }
 350
 351         return (count);
 352 }
 353
 354 static int
 355 futex_wait(struct futex *f, struct waiting_proc *wp, struct l_timespec *ts)
 356 {
 357         struct l_timespec timeout = {0, 0};
 358         struct timeval tv = {0, 0};
 359         int timeout_hz;
 360         int error;
 361
 362         if (ts != NULL) {
 363                 error = copyin(ts, &timeout, sizeof(timeout));
 364                 if (error)
 365                         return (error);
 366         }
 367
 368         tv.tv_usec = timeout.tv_sec * 1000000 + timeout.tv_nsec / 1000;
 369         timeout_hz = tvtohz_high(&tv);
 370
 371         if (timeout.tv_sec == 0 && timeout.tv_nsec == 0)
 372                 timeout_hz = 0;
 373
 374         /*
 375          * If the user process requests a non null timeout,
 376          * make sure we do not turn it into an infinite
 377          * timeout because timeout_hz gets null.
 378          *
 379          * We use a minimal timeout of 1/hz. Maybe it would
 380          * make sense to just return ETIMEDOUT without sleeping.
 381          */
 382         if (((timeout.tv_sec != 0) || (timeout.tv_nsec != 0)) &&
 383             (timeout_hz == 0))
 384                 timeout_hz = 1;
 385
 386         error = futex_sleep(f, wp, timeout_hz);
 387         if (error == EWOULDBLOCK)
 388                 error = ETIMEDOUT;
 389
 390         return (error);
 391 }
 392
 393 static int
 394 futex_atomic_op(struct proc *p, int encoded_op, uint32_t *uaddr)
 395 {
 396         int op = (encoded_op >> 28) & 7;
 397         int cmp = (encoded_op >> 24) & 15;
 398         int oparg = (encoded_op << 8) >> 20;
 399         int cmparg = (encoded_op << 20) >> 20;
 400         int oldval = 0, ret;
 401
 402         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
 403                 oparg = 1 << oparg;
 404
 405 #ifdef DEBUG
 406         if (ldebug(sys_futex))
 407                 kprintf("futex_atomic_op: op = %d, cmp = %d, oparg = %x, "
 408                        "cmparg = %x, uaddr = %p\n",
 409                        op, cmp, oparg, cmparg, uaddr);
 410 #endif
 411         /* XXX: linux verifies access here and returns EFAULT */
 412
 413         switch (op) {
 414         case FUTEX_OP_SET:
 415                 ret = futex_xchgl(oparg, uaddr, &oldval);
 416                 break;
 417         case FUTEX_OP_ADD:
 418                 ret = futex_addl(oparg, uaddr, &oldval);
 419                 break;
 420         case FUTEX_OP_OR:
 421                 ret = futex_orl(oparg, uaddr, &oldval);
 422                 break;
 423         case FUTEX_OP_ANDN:
 424                 ret = futex_andl(~oparg, uaddr, &oldval);
 425                 break;
 426         case FUTEX_OP_XOR:
 427                 ret = futex_xorl(oparg, uaddr, &oldval);
 428                 break;
 429         default:
 430                 ret = -ENOSYS;
 431                 break;
 432         }
 433
 434         if (ret)
 435                 return (ret);
 436
 437         switch (cmp) {
 438         case FUTEX_OP_CMP_EQ:
 439                 return (oldval == cmparg);
 440         case FUTEX_OP_CMP_NE:
 441                 return (oldval != cmparg);
 442         case FUTEX_OP_CMP_LT:
 443                 return (oldval < cmparg);
 444         case FUTEX_OP_CMP_GE:
 445                 return (oldval >= cmparg);
 446         case FUTEX_OP_CMP_LE:
 447                 return (oldval <= cmparg);
 448         case FUTEX_OP_CMP_GT:
 449                 return (oldval > cmparg);
 450         default:
 451                 return (-ENOSYS);
 452         }
 453 }
 454
 455 int
 456 sys_linux_sys_futex(struct linux_sys_futex_args *args)
 457 {
 458         int op_ret, val, ret, nrwake;
 459         struct waiting_proc *wp;
 460         struct futex *f, *f2;
 461         int error = 0;
 462
 463         /*
 464          * Our implementation provides only privates futexes. Most of the apps
 465          * should use private futexes but don't claim so. Therefore we treat
 466          * all futexes as private by clearing the FUTEX_PRIVATE_FLAG. It works
 467          * in most cases (ie. when futexes are not shared on file descriptor
 468          * or between different processes.).
 469          */
 470         args->op = (args->op & ~LINUX_FUTEX_PRIVATE_FLAG);
 471
 472         switch (args->op) {
 473         case LINUX_FUTEX_WAIT:
 474                 LINUX_CTR2(sys_futex, "WAIT val %d uaddr %p",
 475                     args->val, args->uaddr);
 476 #ifdef DEBUG
 477                 if (ldebug(sys_futex))
 478                         kprintf(ARGS(sys_futex, "futex_wait val %d uaddr %p"),
 479                             args->val, args->uaddr);
 480 #endif
 481                 error = futex_get(args->uaddr, &wp, &f, FUTEX_CREATE_WP);
 482                 if (error)
 483                         return (error);
 484                 error = copyin(args->uaddr, &val, sizeof(val));
 485                 if (error) {
 486                         LINUX_CTR1(sys_futex, "WAIT copyin failed %d",
 487                             error);
 488                         futex_put(f, wp);
 489                         return (error);
 490                 }
 491                 if (val != args->val) {
 492                         LINUX_CTR3(sys_futex, "WAIT uaddr %p val %d != uval %d",
 493                             args->uaddr, args->val, val);
 494                         futex_put(f, wp);
 495                         return (EWOULDBLOCK);
 496                 }
 497
 498                 error = futex_wait(f, wp, args->timeout);
 499                 break;
 500
 501         case LINUX_FUTEX_WAKE:
 502
 503                 LINUX_CTR2(sys_futex, "WAKE val %d uaddr %p",
 504                     args->val, args->uaddr);
 505
 506                 /*
 507                  * XXX: Linux is able to cope with different addresses
 508                  * corresponding to the same mapped memory in the sleeping
 509                  * and waker process(es).
 510                  */
 511 #ifdef DEBUG
 512                 if (ldebug(sys_futex))
 513                         kprintf(ARGS(sys_futex, "futex_wake val %d uaddr %p"),
 514                             args->val, args->uaddr);
 515 #endif
 516                 error = futex_get(args->uaddr, NULL, &f, FUTEX_DONTCREATE);
 517                 if (error)
 518                         return (error);
 519                 if (f == NULL) {
 520                         args->sysmsg_iresult = 0;
 521                         return (error);
 522                 }
 523                 args->sysmsg_iresult = futex_wake(f, args->val);
 524                 futex_put(f, NULL);
 525                 break;
 526
 527         case LINUX_FUTEX_CMP_REQUEUE:
 528
 529                 LINUX_CTR5(sys_futex, "CMP_REQUEUE uaddr %p "
 530                     "val %d val3 %d uaddr2 %p val2 %d",
 531                     args->uaddr, args->val, args->val3, args->uaddr2,
 532                     (int)(unsigned long)args->timeout);
 533
 534 #ifdef DEBUG
 535                 if (ldebug(sys_futex))
 536                         kprintf(ARGS(sys_futex, "futex_cmp_requeue uaddr %p "
 537                             "val %d val3 %d uaddr2 %p val2 %d"),
 538                             args->uaddr, args->val, args->val3, args->uaddr2,
 539                             (int)(unsigned long)args->timeout);
 540 #endif
 541                 /*
 542                  * Linux allows this, we would not, it is an incorrect
 543                  * usage of declared ABI, so return EINVAL.
 544                  */
 545                 if (args->uaddr == args->uaddr2)
 546                         return (EINVAL);
 547                 error = futex_get0(args->uaddr, &f, 0);
 548                 if (error)
 549                         return (error);
 550
 551                 /*
 552                  * To avoid deadlocks return EINVAL if second futex
 553                  * exists at this time. Otherwise create the new futex
 554                  * and ignore false positive LOR which thus happens.
 555                  *
 556                  * Glibc fall back to FUTEX_WAKE in case of any error
 557                  * returned by FUTEX_CMP_REQUEUE.
 558                  */
 559                 error = futex_get0(args->uaddr2, &f2, FUTEX_DONTEXISTS);
 560                 if (error) {
 561                         futex_put(f, NULL);
 562                         return (error);
 563                 }
 564                 error = copyin(args->uaddr, &val, sizeof(val));
 565                 if (error) {
 566                         LINUX_CTR1(sys_futex, "CMP_REQUEUE copyin failed %d",
 567                             error);
 568                         futex_put(f2, NULL);
 569                         futex_put(f, NULL);
 570                         return (error);
 571                 }
 572                 if (val != args->val3) {
 573                         LINUX_CTR2(sys_futex, "CMP_REQUEUE val %d != uval %d",
 574                             args->val, val);
 575                         futex_put(f2, NULL);
 576                         futex_put(f, NULL);
 577                         return (EAGAIN);
 578                 }
 579
 580                 nrwake = (int)(unsigned long)args->timeout;
 581                 args->sysmsg_iresult = futex_requeue(f, args->val, f2, nrwake);
 582                 futex_put(f2, NULL);
 583                 futex_put(f, NULL);
 584                 break;
 585
 586         case LINUX_FUTEX_WAKE_OP:
 587
 588                 LINUX_CTR5(sys_futex, "WAKE_OP "
 589                     "uaddr %p op %d val %x uaddr2 %p val3 %x",
 590                     args->uaddr, args->op, args->val,
 591                     args->uaddr2, args->val3);
 592
 593 #ifdef DEBUG
 594                 if (ldebug(sys_futex))
 595                         kprintf(ARGS(sys_futex, "futex_wake_op "
 596                             "uaddr %p op %d val %x uaddr2 %p val3 %x"),
 597                             args->uaddr, args->op, args->val,
 598                             args->uaddr2, args->val3);
 599 #endif
 600                 error = futex_get0(args->uaddr, &f, 0);
 601                 if (error)
 602                         return (error);
 603                 if (args->uaddr != args->uaddr2)
 604                         error = futex_get0(args->uaddr2, &f2, 0);
 605                 if (error) {
 606                         futex_put(f, NULL);
 607                         return (error);
 608                 }
 609
 610                 /*
 611                  * This function returns positive number as results and
 612                  * negative as errors
 613                  */
 614                 op_ret = futex_atomic_op(curproc, args->val3, args->uaddr2);
 615
 616                 if (op_ret < 0) {
 617                         /* XXX: We don't handle the EFAULT yet. */
 618                         if (op_ret != -EFAULT) {
 619                                 if (f2 != NULL)
 620                                         futex_put(f2, NULL);
 621                                 futex_put(f, NULL);
 622                                 return (-op_ret);
 623                         }
 624                         if (f2 != NULL)
 625                                 futex_put(f2, NULL);
 626                         futex_put(f, NULL);
 627                         return (EFAULT);
 628                 }
 629
 630                 ret = futex_wake(f, args->val);
 631
 632                 if (op_ret > 0) {
 633                         op_ret = 0;
 634                         nrwake = (int)(unsigned long)args->timeout;
 635
 636                         if (f2 != NULL)
 637                                 op_ret += futex_wake(f2, nrwake);
 638                         else
 639                                 op_ret += futex_wake(f, nrwake);
 640                         ret += op_ret;
 641
 642                 }
 643                 if (f2 != NULL)
 644                         futex_put(f2, NULL);
 645                 futex_put(f, NULL);
 646                 args->sysmsg_iresult = ret;
 647                 break;
 648
 649         case LINUX_FUTEX_LOCK_PI:
 650                 /* not yet implemented */
 651                 return (ENOSYS);
 652
 653         case LINUX_FUTEX_UNLOCK_PI:
 654                 /* not yet implemented */
 655                 return (ENOSYS);
 656
 657         case LINUX_FUTEX_TRYLOCK_PI:
 658                 /* not yet implemented */
 659                 return (ENOSYS);
 660
 661         case LINUX_FUTEX_REQUEUE:
 662
 663                 /*
 664                  * Glibc does not use this operation since version 2.3.3,
 665                  * as it is racy and replaced by FUTEX_CMP_REQUEUE operation.
 666                  * Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when
 667                  * FUTEX_REQUEUE returned EINVAL.
 668                  */
 669                 return (EINVAL);
 670
 671         default:
 672                 kprintf("linux_sys_futex: unknown op %d\n", args->op);
 673                 return (ENOSYS);
 674         }
 675
 676         return (error);
 677 }
 678
 679 int
 680 sys_linux_set_robust_list(struct linux_set_robust_list_args *args)
 681 {
 682 #ifdef DEBUG
 683         if (ldebug(set_robust_list))
 684                 kprintf(ARGS(set_robust_list, "head %p len %d"),
 685                     args->head, args->len);
 686 #endif
 687
 688         if (args->len != sizeof(struct linux_robust_list_head))
 689                 return (EINVAL);
 690
 691         emuldata_set_robust(curproc, args->head);
 692
 693         return (0);
 694 }
 695
 696
 697
 698 int
 699 sys_linux_get_robust_list(struct linux_get_robust_list_args *args)
 700 {
 701         struct linux_emuldata *em;
 702         struct linux_robust_list_head empty_head;
 703         struct linux_robust_list_head *head;
 704         l_size_t len = sizeof(struct linux_robust_list_head);
 705         int error = 0;
 706
 707 #ifdef  DEBUG
 708         if (ldebug(get_robust_list))
 709                 kprintf(ARGS(get_robust_list, ""));
 710 #endif
 711         EMUL_LOCK();
 712         if (args->pid == 0) {
 713                 em = emuldata_get(curproc);
 714                 KKASSERT(em != NULL);
 715                 if (em->robust_futexes == NULL) {
 716                         bzero(&empty_head, sizeof(empty_head));
 717                         head = &empty_head;
 718                 } else {
 719                         head = em->robust_futexes;
 720                 }
 721         } else {
 722                 struct proc *p;
 723
 724                 p = pfind(args->pid);
 725                 if (p == NULL) {
 726                         EMUL_UNLOCK();
 727                         return (ESRCH);
 728                 }
 729
 730                 em = emuldata_get(p);
 731                 /* XXX: ptrace? p_candebug?*/
 732                 if (priv_check(curthread, PRIV_CRED_SETUID) ||
 733                     priv_check(curthread, PRIV_CRED_SETEUID)/* ||
 734                     p_candebug(curproc, p) */) {
 735                         EMUL_UNLOCK();
 736                         return (EPERM);
 737                 }
 738                 head = em->robust_futexes;
 739
 740         }
 741         EMUL_UNLOCK();
 742
 743         error = copyout(&len, args->len, sizeof(l_size_t));
 744         if (error)
 745                 return (EFAULT);
 746
 747         error = copyout(head, args->head, sizeof(struct linux_robust_list_head));
 748
 749         return (error);
 750 }
 751
 752 static int
 753 handle_futex_death(struct proc *p, uint32_t *uaddr, int pi)
 754 {
 755         uint32_t uval, nval, mval;
 756         struct futex *f;
 757         int error;
 758
 759 retry:
 760         if (copyin(uaddr, &uval, 4))
 761                 return (EFAULT);
 762         if ((uval & FUTEX_TID_MASK) == p->p_pid) {
 763                 mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED;
 764                 nval = casuword((ulong *)uaddr, uval, mval);
 765
 766                 if (nval == -1)
 767                         return (EFAULT);
 768
 769                 if (nval != uval)
 770                         goto retry;
 771
 772                 if (!pi && (uval & FUTEX_WAITERS)) {
 773                         error = futex_get(uaddr, NULL, &f,
 774                             FUTEX_DONTCREATE);
 775                         if (error)
 776                                 return (error);
 777                         if (f != NULL) {
 778                                 futex_wake(f, 1);
 779                                 futex_put(f, NULL);
 780                         }
 781                 }
 782         }
 783
 784         return (0);
 785 }
 786
 787 static int
 788 fetch_robust_entry(struct linux_robust_list **entry,
 789     struct linux_robust_list **head, int *pi)
 790 {
 791         l_ulong uentry;
 792
 793         if (copyin((const void *)head, &uentry, sizeof(l_ulong)))
 794                 return (EFAULT);
 795
 796         *entry = (void *)(uentry & ~1UL);
 797         *pi = uentry & 1;
 798
 799         return (0);
 800 }
 801
 802 /* This walks the list of robust futexes releasing them. */
 803 void
 804 release_futexes(struct proc *p)
 805 {
 806         struct linux_robust_list_head *head = NULL;
 807         struct linux_robust_list *entry, *next_entry, *pending;
 808         unsigned int limit = 2048, pi, next_pi, pip;
 809         struct linux_emuldata *em;
 810         l_long futex_offset;
 811         int rc;
 812
 813         EMUL_LOCK();
 814         KKASSERT(p != NULL);
 815         em = emuldata_get(p);
 816         KKASSERT(em != NULL);
 817         head = em->robust_futexes;
 818         EMUL_UNLOCK();
 819
 820         if (head == NULL)
 821                 return;
 822
 823         if (fetch_robust_entry(&entry, PTRIN(&head->list.next), &pi))
 824                 return;
 825
 826         if (copyin(&head->futex_offset, &futex_offset, sizeof(futex_offset)))
 827                 return;
 828
 829         if (fetch_robust_entry(&pending, PTRIN(&head->pending_list), &pip))
 830                 return;
 831
 832         while (entry != &head->list) {
 833                 rc = fetch_robust_entry(&next_entry, PTRIN(&entry->next), &next_pi);
 834
 835                 if (entry != pending)
 836                         if (handle_futex_death(p, (uint32_t *)entry + futex_offset, pi))
 837                                 return;
 838                 if (rc)
 839                         return;
 840
 841                 entry = next_entry;
 842                 pi = next_pi;
 843
 844                 if (!--limit)
 845                         break;
 846
 847 #if 0
 848                 /* XXX: not sure about this yield, was sched_relinquish(curthread); */
 849                 lwkt_deschedule(curthread);
 850                 lwkt_yield();
 851 #endif
 852         }
 853
 854         if (pending)
 855                 handle_futex_death(p, (uint32_t *)pending + futex_offset, pip);
 856 }