The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/compat/linux/linux_futex.c

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    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: releng/9.1/sys/compat/linux/linux_futex.c 219460 2011-03-10 19:50:12Z jhb $");
   36 #if 0
   37 __KERNEL_RCSID(1, "$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 }

Cache object: bf1ac9a6e88d8c94cd602e91d614f5d8


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