The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: 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/10.2/sys/compat/linux/linux_futex.c 293893 2016-01-14 09:10:46Z glebius $");
   36 #if 0
   37 __KERNEL_RCSID(1, "$NetBSD: linux_futex.c,v 1.7 2006/07/24 19:01:49 manu Exp $");
   38 #endif
   39 
   40 #include "opt_compat.h"
   41 #include "opt_kdtrace.h"
   42 
   43 #include <sys/param.h>
   44 #include <sys/systm.h>
   45 #include <sys/imgact.h>
   46 #include <sys/kernel.h>
   47 #include <sys/ktr.h>
   48 #include <sys/lock.h>
   49 #include <sys/malloc.h>
   50 #include <sys/mutex.h>
   51 #include <sys/priv.h>
   52 #include <sys/proc.h>
   53 #include <sys/queue.h>
   54 #include <sys/sched.h>
   55 #include <sys/sdt.h>
   56 #include <sys/sx.h>
   57 #include <sys/umtx.h>
   58 
   59 #ifdef COMPAT_LINUX32
   60 #include <machine/../linux32/linux.h>
   61 #include <machine/../linux32/linux32_proto.h>
   62 #else
   63 #include <machine/../linux/linux.h>
   64 #include <machine/../linux/linux_proto.h>
   65 #endif
   66 #include <compat/linux/linux_dtrace.h>
   67 #include <compat/linux/linux_emul.h>
   68 #include <compat/linux/linux_futex.h>
   69 #include <compat/linux/linux_util.h>
   70 
   71 /* DTrace init */
   72 LIN_SDT_PROVIDER_DECLARE(LINUX_DTRACE);
   73 
   74 /* Linuxulator-global DTrace probes */
   75 LIN_SDT_PROBE_DECLARE(locks, emul_lock, locked);
   76 LIN_SDT_PROBE_DECLARE(locks, emul_lock, unlock);
   77 
   78 /**
   79  * Futex part for the special DTrace module "locks".
   80  */
   81 LIN_SDT_PROBE_DEFINE1(locks, futex_mtx, locked, "struct mtx *");
   82 LIN_SDT_PROBE_DEFINE1(locks, futex_mtx, unlock, "struct mtx *");
   83 
   84 /**
   85  * Per futex probes.
   86  */
   87 LIN_SDT_PROBE_DEFINE1(futex, futex, create, "struct sx *");
   88 LIN_SDT_PROBE_DEFINE1(futex, futex, destroy, "struct sx *");
   89 
   90 /**
   91  * DTrace probes in this module.
   92  */
   93 LIN_SDT_PROBE_DEFINE2(futex, futex_put, entry, "struct futex *",
   94     "struct waiting_proc *");
   95 LIN_SDT_PROBE_DEFINE3(futex, futex_put, destroy, "uint32_t *", "uint32_t",
   96     "int");
   97 LIN_SDT_PROBE_DEFINE3(futex, futex_put, unlock, "uint32_t *", "uint32_t",
   98     "int");
   99 LIN_SDT_PROBE_DEFINE0(futex, futex_put, return);
  100 LIN_SDT_PROBE_DEFINE3(futex, futex_get0, entry, "uint32_t *", "struct futex **",
  101     "uint32_t");
  102 LIN_SDT_PROBE_DEFINE1(futex, futex_get0, umtx_key_get_error, "int");
  103 LIN_SDT_PROBE_DEFINE3(futex, futex_get0, shared, "uint32_t *", "uint32_t",
  104     "int");
  105 LIN_SDT_PROBE_DEFINE1(futex, futex_get0, null, "uint32_t *");
  106 LIN_SDT_PROBE_DEFINE3(futex, futex_get0, new, "uint32_t *", "uint32_t", "int");
  107 LIN_SDT_PROBE_DEFINE1(futex, futex_get0, return, "int");
  108 LIN_SDT_PROBE_DEFINE3(futex, futex_get, entry, "uint32_t *",
  109     "struct waiting_proc **", "struct futex **");
  110 LIN_SDT_PROBE_DEFINE0(futex, futex_get, error);
  111 LIN_SDT_PROBE_DEFINE1(futex, futex_get, return, "int");
  112 LIN_SDT_PROBE_DEFINE3(futex, futex_sleep, entry, "struct futex *",
  113     "struct waiting_proc **", "int");
  114 LIN_SDT_PROBE_DEFINE5(futex, futex_sleep, requeue_error, "int", "uint32_t *",
  115     "struct waiting_proc *", "uint32_t *", "uint32_t");
  116 LIN_SDT_PROBE_DEFINE3(futex, futex_sleep, sleep_error, "int", "uint32_t *",
  117     "struct waiting_proc *");
  118 LIN_SDT_PROBE_DEFINE1(futex, futex_sleep, return, "int");
  119 LIN_SDT_PROBE_DEFINE3(futex, futex_wake, entry, "struct futex *", "int",
  120     "uint32_t");
  121 LIN_SDT_PROBE_DEFINE3(futex, futex_wake, iterate, "uint32_t",
  122     "struct waiting_proc *", "uint32_t");
  123 LIN_SDT_PROBE_DEFINE1(futex, futex_wake, wakeup, "struct waiting_proc *");
  124 LIN_SDT_PROBE_DEFINE1(futex, futex_wake, return, "int");
  125 LIN_SDT_PROBE_DEFINE4(futex, futex_requeue, entry, "struct futex *", "int",
  126     "struct futex *", "int");
  127 LIN_SDT_PROBE_DEFINE1(futex, futex_requeue, wakeup, "struct waiting_proc *");
  128 LIN_SDT_PROBE_DEFINE3(futex, futex_requeue, requeue, "uint32_t *",
  129     "struct waiting_proc *", "uint32_t");
  130 LIN_SDT_PROBE_DEFINE1(futex, futex_requeue, return, "int");
  131 LIN_SDT_PROBE_DEFINE4(futex, futex_wait, entry, "struct futex *",
  132     "struct waiting_proc **", "int", "uint32_t");
  133 LIN_SDT_PROBE_DEFINE1(futex, futex_wait, sleep_error, "int");
  134 LIN_SDT_PROBE_DEFINE1(futex, futex_wait, return, "int");
  135 LIN_SDT_PROBE_DEFINE3(futex, futex_atomic_op, entry, "struct thread *",
  136     "int", "uint32_t");
  137 LIN_SDT_PROBE_DEFINE4(futex, futex_atomic_op, decoded_op, "int", "int", "int",
  138     "int");
  139 LIN_SDT_PROBE_DEFINE0(futex, futex_atomic_op, missing_access_check);
  140 LIN_SDT_PROBE_DEFINE1(futex, futex_atomic_op, unimplemented_op, "int");
  141 LIN_SDT_PROBE_DEFINE1(futex, futex_atomic_op, unimplemented_cmp, "int");
  142 LIN_SDT_PROBE_DEFINE1(futex, futex_atomic_op, return, "int");
  143 LIN_SDT_PROBE_DEFINE2(futex, linux_sys_futex, entry, "struct thread *",
  144     "struct linux_sys_futex_args *");
  145 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_clockswitch);
  146 LIN_SDT_PROBE_DEFINE1(futex, linux_sys_futex, itimerfix_error, "int");
  147 LIN_SDT_PROBE_DEFINE1(futex, linux_sys_futex, copyin_error, "int");
  148 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, invalid_cmp_requeue_use);
  149 LIN_SDT_PROBE_DEFINE3(futex, linux_sys_futex, debug_wait, "uint32_t *",
  150     "uint32_t", "uint32_t");
  151 LIN_SDT_PROBE_DEFINE4(futex, linux_sys_futex, debug_wait_value_neq,
  152     "uint32_t *", "uint32_t", "int", "uint32_t");
  153 LIN_SDT_PROBE_DEFINE3(futex, linux_sys_futex, debug_wake, "uint32_t *",
  154     "uint32_t", "uint32_t");
  155 LIN_SDT_PROBE_DEFINE5(futex, linux_sys_futex, debug_cmp_requeue, "uint32_t *",
  156     "uint32_t", "uint32_t", "uint32_t *", "struct l_timespec *");
  157 LIN_SDT_PROBE_DEFINE2(futex, linux_sys_futex, debug_cmp_requeue_value_neq,
  158     "uint32_t", "int");
  159 LIN_SDT_PROBE_DEFINE5(futex, linux_sys_futex, debug_wake_op, "uint32_t *",
  160     "int", "uint32_t", "uint32_t *", "uint32_t");
  161 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unhandled_efault);
  162 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_lock_pi);
  163 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_unlock_pi);
  164 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_trylock_pi);
  165 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, deprecated_requeue);
  166 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_wait_requeue_pi);
  167 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_cmp_requeue_pi);
  168 LIN_SDT_PROBE_DEFINE1(futex, linux_sys_futex, unknown_operation, "int");
  169 LIN_SDT_PROBE_DEFINE1(futex, linux_sys_futex, return, "int");
  170 LIN_SDT_PROBE_DEFINE2(futex, linux_set_robust_list, entry, "struct thread *",
  171     "struct linux_set_robust_list_args *");
  172 LIN_SDT_PROBE_DEFINE0(futex, linux_set_robust_list, size_error);
  173 LIN_SDT_PROBE_DEFINE1(futex, linux_set_robust_list, return, "int");
  174 LIN_SDT_PROBE_DEFINE2(futex, linux_get_robust_list, entry, "struct thread *",
  175     "struct linux_get_robust_list_args *");
  176 LIN_SDT_PROBE_DEFINE1(futex, linux_get_robust_list, copyout_error, "int");
  177 LIN_SDT_PROBE_DEFINE1(futex, linux_get_robust_list, return, "int");
  178 LIN_SDT_PROBE_DEFINE3(futex, handle_futex_death, entry, "struct proc *",
  179     "uint32_t *", "unsigned int");
  180 LIN_SDT_PROBE_DEFINE1(futex, handle_futex_death, copyin_error, "int");
  181 LIN_SDT_PROBE_DEFINE1(futex, handle_futex_death, return, "int");
  182 LIN_SDT_PROBE_DEFINE3(futex, fetch_robust_entry, entry,
  183     "struct linux_robust_list **", "struct linux_robust_list **",
  184     "unsigned int *");
  185 LIN_SDT_PROBE_DEFINE1(futex, fetch_robust_entry, copyin_error, "int");
  186 LIN_SDT_PROBE_DEFINE1(futex, fetch_robust_entry, return, "int");
  187 LIN_SDT_PROBE_DEFINE1(futex, release_futexes, entry, "struct proc *");
  188 LIN_SDT_PROBE_DEFINE1(futex, release_futexes, copyin_error, "int");
  189 LIN_SDT_PROBE_DEFINE0(futex, release_futexes, return);
  190 
  191 static MALLOC_DEFINE(M_FUTEX, "futex", "Linux futexes");
  192 static MALLOC_DEFINE(M_FUTEX_WP, "futex wp", "Linux futexes wp");
  193 
  194 struct futex;
  195 
  196 struct waiting_proc {
  197         uint32_t        wp_flags;
  198         struct futex    *wp_futex;
  199         TAILQ_ENTRY(waiting_proc) wp_list;
  200 };
  201 
  202 struct futex {
  203         struct sx       f_lck;
  204         uint32_t        *f_uaddr;       /* user-supplied value, for debug */
  205         struct umtx_key f_key;
  206         uint32_t        f_refcount;
  207         uint32_t        f_bitset;
  208         LIST_ENTRY(futex) f_list;
  209         TAILQ_HEAD(lf_waiting_proc, waiting_proc) f_waiting_proc;
  210 };
  211 
  212 struct futex_list futex_list;
  213 
  214 #define FUTEX_LOCK(f)           sx_xlock(&(f)->f_lck)
  215 #define FUTEX_UNLOCK(f)         sx_xunlock(&(f)->f_lck)
  216 #define FUTEX_INIT(f)           do { \
  217                                     sx_init_flags(&(f)->f_lck, "ftlk", \
  218                                         SX_DUPOK); \
  219                                     LIN_SDT_PROBE1(futex, futex, create, \
  220                                         &(f)->f_lck); \
  221                                 } while (0)
  222 #define FUTEX_DESTROY(f)        do { \
  223                                     LIN_SDT_PROBE1(futex, futex, destroy, \
  224                                         &(f)->f_lck); \
  225                                     sx_destroy(&(f)->f_lck); \
  226                                 } while (0)
  227 #define FUTEX_ASSERT_LOCKED(f)  sx_assert(&(f)->f_lck, SA_XLOCKED)
  228 
  229 struct mtx futex_mtx;                   /* protects the futex list */
  230 #define FUTEXES_LOCK            do { \
  231                                     mtx_lock(&futex_mtx); \
  232                                     LIN_SDT_PROBE1(locks, futex_mtx, \
  233                                         locked, &futex_mtx); \
  234                                 } while (0)
  235 #define FUTEXES_UNLOCK          do { \
  236                                     LIN_SDT_PROBE1(locks, futex_mtx, \
  237                                         unlock, &futex_mtx); \
  238                                     mtx_unlock(&futex_mtx); \
  239                                 } while (0)
  240 
  241 /* flags for futex_get() */
  242 #define FUTEX_CREATE_WP         0x1     /* create waiting_proc */
  243 #define FUTEX_DONTCREATE        0x2     /* don't create futex if not exists */
  244 #define FUTEX_DONTEXISTS        0x4     /* return EINVAL if futex exists */
  245 #define FUTEX_SHARED            0x8     /* shared futex */
  246 
  247 /* wp_flags */
  248 #define FUTEX_WP_REQUEUED       0x1     /* wp requeued - wp moved from wp_list
  249                                          * of futex where thread sleep to wp_list
  250                                          * of another futex.
  251                                          */
  252 #define FUTEX_WP_REMOVED        0x2     /* wp is woken up and removed from futex
  253                                          * wp_list to prevent double wakeup.
  254                                          */
  255 
  256 /* support.s */
  257 int futex_xchgl(int oparg, uint32_t *uaddr, int *oldval);
  258 int futex_addl(int oparg, uint32_t *uaddr, int *oldval);
  259 int futex_orl(int oparg, uint32_t *uaddr, int *oldval);
  260 int futex_andl(int oparg, uint32_t *uaddr, int *oldval);
  261 int futex_xorl(int oparg, uint32_t *uaddr, int *oldval);
  262 
  263 static void
  264 futex_put(struct futex *f, struct waiting_proc *wp)
  265 {
  266         LIN_SDT_PROBE2(futex, futex_put, entry, f, wp);
  267 
  268         FUTEX_ASSERT_LOCKED(f);
  269         if (wp != NULL) {
  270                 if ((wp->wp_flags & FUTEX_WP_REMOVED) == 0)
  271                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
  272                 free(wp, M_FUTEX_WP);
  273         }
  274 
  275         FUTEXES_LOCK;
  276         if (--f->f_refcount == 0) {
  277                 LIST_REMOVE(f, f_list);
  278                 FUTEXES_UNLOCK;
  279                 FUTEX_UNLOCK(f);
  280 
  281                 LIN_SDT_PROBE3(futex, futex_put, destroy, f->f_uaddr,
  282                     f->f_refcount, f->f_key.shared);
  283                 LINUX_CTR3(sys_futex, "futex_put destroy uaddr %p ref %d "
  284                     "shared %d", f->f_uaddr, f->f_refcount, f->f_key.shared);
  285                 umtx_key_release(&f->f_key);
  286                 FUTEX_DESTROY(f);
  287                 free(f, M_FUTEX);
  288 
  289                 LIN_SDT_PROBE0(futex, futex_put, return);
  290                 return;
  291         }
  292 
  293         LIN_SDT_PROBE3(futex, futex_put, unlock, f->f_uaddr, f->f_refcount,
  294             f->f_key.shared);
  295         LINUX_CTR3(sys_futex, "futex_put uaddr %p ref %d shared %d",
  296             f->f_uaddr, f->f_refcount, f->f_key.shared);
  297         FUTEXES_UNLOCK;
  298         FUTEX_UNLOCK(f);
  299 
  300         LIN_SDT_PROBE0(futex, futex_put, return);
  301 }
  302 
  303 static int
  304 futex_get0(uint32_t *uaddr, struct futex **newf, uint32_t flags)
  305 {
  306         struct futex *f, *tmpf;
  307         struct umtx_key key;
  308         int error;
  309 
  310         LIN_SDT_PROBE3(futex, futex_get0, entry, uaddr, newf, flags);
  311 
  312         *newf = tmpf = NULL;
  313 
  314         error = umtx_key_get(uaddr, TYPE_FUTEX, (flags & FUTEX_SHARED) ?
  315             AUTO_SHARE : THREAD_SHARE, &key);
  316         if (error) {
  317                 LIN_SDT_PROBE1(futex, futex_get0, umtx_key_get_error, error);
  318                 LIN_SDT_PROBE1(futex, futex_get0, return, error);
  319                 return (error);
  320         }
  321 retry:
  322         FUTEXES_LOCK;
  323         LIST_FOREACH(f, &futex_list, f_list) {
  324                 if (umtx_key_match(&f->f_key, &key)) {
  325                         if (tmpf != NULL) {
  326                                 FUTEX_UNLOCK(tmpf);
  327                                 FUTEX_DESTROY(tmpf);
  328                                 free(tmpf, M_FUTEX);
  329                         }
  330                         if (flags & FUTEX_DONTEXISTS) {
  331                                 FUTEXES_UNLOCK;
  332                                 umtx_key_release(&key);
  333 
  334                                 LIN_SDT_PROBE1(futex, futex_get0, return,
  335                                     EINVAL);
  336                                 return (EINVAL);
  337                         }
  338 
  339                         /*
  340                          * Increment refcount of the found futex to
  341                          * prevent it from deallocation before FUTEX_LOCK()
  342                          */
  343                         ++f->f_refcount;
  344                         FUTEXES_UNLOCK;
  345                         umtx_key_release(&key);
  346 
  347                         FUTEX_LOCK(f);
  348                         *newf = f;
  349                         LIN_SDT_PROBE3(futex, futex_get0, shared, uaddr,
  350                             f->f_refcount, f->f_key.shared);
  351                         LINUX_CTR3(sys_futex, "futex_get uaddr %p ref %d shared %d",
  352                             uaddr, f->f_refcount, f->f_key.shared);
  353 
  354                         LIN_SDT_PROBE1(futex, futex_get0, return, 0);
  355                         return (0);
  356                 }
  357         }
  358 
  359         if (flags & FUTEX_DONTCREATE) {
  360                 FUTEXES_UNLOCK;
  361                 umtx_key_release(&key);
  362                 LIN_SDT_PROBE1(futex, futex_get0, null, uaddr);
  363                 LINUX_CTR1(sys_futex, "futex_get uaddr %p null", uaddr);
  364 
  365                 LIN_SDT_PROBE1(futex, futex_get0, return, 0);
  366                 return (0);
  367         }
  368 
  369         if (tmpf == NULL) {
  370                 FUTEXES_UNLOCK;
  371                 tmpf = malloc(sizeof(*tmpf), M_FUTEX, M_WAITOK | M_ZERO);
  372                 tmpf->f_uaddr = uaddr;
  373                 tmpf->f_key = key;
  374                 tmpf->f_refcount = 1;
  375                 tmpf->f_bitset = FUTEX_BITSET_MATCH_ANY;
  376                 FUTEX_INIT(tmpf);
  377                 TAILQ_INIT(&tmpf->f_waiting_proc);
  378 
  379                 /*
  380                  * Lock the new futex before an insert into the futex_list
  381                  * to prevent futex usage by other.
  382                  */
  383                 FUTEX_LOCK(tmpf);
  384                 goto retry;
  385         }
  386 
  387         LIST_INSERT_HEAD(&futex_list, tmpf, f_list);
  388         FUTEXES_UNLOCK;
  389 
  390         LIN_SDT_PROBE3(futex, futex_get0, new, uaddr, tmpf->f_refcount,
  391             tmpf->f_key.shared);
  392         LINUX_CTR3(sys_futex, "futex_get uaddr %p ref %d shared %d new",
  393             uaddr, tmpf->f_refcount, tmpf->f_key.shared);
  394         *newf = tmpf;
  395 
  396         LIN_SDT_PROBE1(futex, futex_get0, return, 0);
  397         return (0);
  398 }
  399 
  400 static int
  401 futex_get(uint32_t *uaddr, struct waiting_proc **wp, struct futex **f,
  402     uint32_t flags)
  403 {
  404         int error;
  405 
  406         LIN_SDT_PROBE3(futex, futex_get, entry, uaddr, wp, f);
  407 
  408         if (flags & FUTEX_CREATE_WP) {
  409                 *wp = malloc(sizeof(struct waiting_proc), M_FUTEX_WP, M_WAITOK);
  410                 (*wp)->wp_flags = 0;
  411         }
  412         error = futex_get0(uaddr, f, flags);
  413         if (error) {
  414                 LIN_SDT_PROBE0(futex, futex_get, error);
  415 
  416                 if (flags & FUTEX_CREATE_WP)
  417                         free(*wp, M_FUTEX_WP);
  418 
  419                 LIN_SDT_PROBE1(futex, futex_get, return, error);
  420                 return (error);
  421         }
  422         if (flags & FUTEX_CREATE_WP) {
  423                 TAILQ_INSERT_HEAD(&(*f)->f_waiting_proc, *wp, wp_list);
  424                 (*wp)->wp_futex = *f;
  425         }
  426 
  427         LIN_SDT_PROBE1(futex, futex_get, return, error);
  428         return (error);
  429 }
  430 
  431 static int
  432 futex_sleep(struct futex *f, struct waiting_proc *wp, int timeout)
  433 {
  434         int error;
  435 
  436         FUTEX_ASSERT_LOCKED(f);
  437         LIN_SDT_PROBE3(futex, futex_sleep, entry, f, wp, timeout);
  438         LINUX_CTR4(sys_futex, "futex_sleep enter uaddr %p wp %p timo %d ref %d",
  439             f->f_uaddr, wp, timeout, f->f_refcount);
  440         error = sx_sleep(wp, &f->f_lck, PCATCH, "futex", timeout);
  441         if (wp->wp_flags & FUTEX_WP_REQUEUED) {
  442                 KASSERT(f != wp->wp_futex, ("futex != wp_futex"));
  443 
  444                 if (error) {
  445                         LIN_SDT_PROBE5(futex, futex_sleep, requeue_error, error,
  446                             f->f_uaddr, wp, wp->wp_futex->f_uaddr,
  447                             wp->wp_futex->f_refcount);
  448                 }
  449 
  450                 LINUX_CTR5(sys_futex, "futex_sleep out error %d uaddr %p wp"
  451                     " %p requeued uaddr %p ref %d",
  452                     error, f->f_uaddr, wp, wp->wp_futex->f_uaddr,
  453                     wp->wp_futex->f_refcount);
  454                 futex_put(f, NULL);
  455                 f = wp->wp_futex;
  456                 FUTEX_LOCK(f);
  457         } else {
  458                 if (error) {
  459                         LIN_SDT_PROBE3(futex, futex_sleep, sleep_error, error,
  460                             f->f_uaddr, wp);
  461                 }
  462                 LINUX_CTR3(sys_futex, "futex_sleep out error %d uaddr %p wp %p",
  463                     error, f->f_uaddr, wp);
  464         }
  465 
  466         futex_put(f, wp);
  467 
  468         LIN_SDT_PROBE1(futex, futex_sleep, return, error);
  469         return (error);
  470 }
  471 
  472 static int
  473 futex_wake(struct futex *f, int n, uint32_t bitset)
  474 {
  475         struct waiting_proc *wp, *wpt;
  476         int count = 0;
  477 
  478         LIN_SDT_PROBE3(futex, futex_wake, entry, f, n, bitset);
  479 
  480         if (bitset == 0) {
  481                 LIN_SDT_PROBE1(futex, futex_wake, return, EINVAL);
  482                 return (EINVAL);
  483         }
  484 
  485         FUTEX_ASSERT_LOCKED(f);
  486         TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) {
  487                 LIN_SDT_PROBE3(futex, futex_wake, iterate, f->f_uaddr, wp,
  488                     f->f_refcount);
  489                 LINUX_CTR3(sys_futex, "futex_wake uaddr %p wp %p ref %d",
  490                     f->f_uaddr, wp, f->f_refcount);
  491                 /*
  492                  * Unless we find a matching bit in
  493                  * the bitset, continue searching.
  494                  */
  495                 if (!(wp->wp_futex->f_bitset & bitset))
  496                         continue;
  497 
  498                 wp->wp_flags |= FUTEX_WP_REMOVED;
  499                 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
  500                 LIN_SDT_PROBE1(futex, futex_wake, wakeup, wp);
  501                 wakeup_one(wp);
  502                 if (++count == n)
  503                         break;
  504         }
  505 
  506         LIN_SDT_PROBE1(futex, futex_wake, return, count);
  507         return (count);
  508 }
  509 
  510 static int
  511 futex_requeue(struct futex *f, int n, struct futex *f2, int n2)
  512 {
  513         struct waiting_proc *wp, *wpt;
  514         int count = 0;
  515 
  516         LIN_SDT_PROBE4(futex, futex_requeue, entry, f, n, f2, n2);
  517 
  518         FUTEX_ASSERT_LOCKED(f);
  519         FUTEX_ASSERT_LOCKED(f2);
  520 
  521         TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) {
  522                 if (++count <= n) {
  523                         LINUX_CTR2(sys_futex, "futex_req_wake uaddr %p wp %p",
  524                             f->f_uaddr, wp);
  525                         wp->wp_flags |= FUTEX_WP_REMOVED;
  526                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
  527                         LIN_SDT_PROBE1(futex, futex_requeue, wakeup, wp);
  528                         wakeup_one(wp);
  529                 } else {
  530                         LIN_SDT_PROBE3(futex, futex_requeue, requeue,
  531                             f->f_uaddr, wp, f2->f_uaddr);
  532                         LINUX_CTR3(sys_futex, "futex_requeue uaddr %p wp %p to %p",
  533                             f->f_uaddr, wp, f2->f_uaddr);
  534                         wp->wp_flags |= FUTEX_WP_REQUEUED;
  535                         /* Move wp to wp_list of f2 futex */
  536                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
  537                         TAILQ_INSERT_HEAD(&f2->f_waiting_proc, wp, wp_list);
  538 
  539                         /*
  540                          * Thread which sleeps on wp after waking should
  541                          * acquire f2 lock, so increment refcount of f2 to
  542                          * prevent it from premature deallocation.
  543                          */
  544                         wp->wp_futex = f2;
  545                         FUTEXES_LOCK;
  546                         ++f2->f_refcount;
  547                         FUTEXES_UNLOCK;
  548                         if (count - n >= n2)
  549                                 break;
  550                 }
  551         }
  552 
  553         LIN_SDT_PROBE1(futex, futex_requeue, return, count);
  554         return (count);
  555 }
  556 
  557 static int
  558 futex_wait(struct futex *f, struct waiting_proc *wp, int timeout_hz,
  559     uint32_t bitset)
  560 {
  561         int error;
  562 
  563         LIN_SDT_PROBE4(futex, futex_wait, entry, f, wp, timeout_hz, bitset);
  564 
  565         if (bitset == 0) {
  566                 LIN_SDT_PROBE1(futex, futex_wait, return, EINVAL);
  567                 return (EINVAL);
  568         }
  569 
  570         f->f_bitset = bitset;
  571         error = futex_sleep(f, wp, timeout_hz);
  572         if (error)
  573                 LIN_SDT_PROBE1(futex, futex_wait, sleep_error, error);
  574         if (error == EWOULDBLOCK)
  575                 error = ETIMEDOUT;
  576 
  577         LIN_SDT_PROBE1(futex, futex_wait, return, error);
  578         return (error);
  579 }
  580 
  581 static int
  582 futex_atomic_op(struct thread *td, int encoded_op, uint32_t *uaddr)
  583 {
  584         int op = (encoded_op >> 28) & 7;
  585         int cmp = (encoded_op >> 24) & 15;
  586         int oparg = (encoded_op << 8) >> 20;
  587         int cmparg = (encoded_op << 20) >> 20;
  588         int oldval = 0, ret;
  589 
  590         LIN_SDT_PROBE3(futex, futex_atomic_op, entry, td, encoded_op, uaddr);
  591 
  592         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
  593                 oparg = 1 << oparg;
  594 
  595         LIN_SDT_PROBE4(futex, futex_atomic_op, decoded_op, op, cmp, oparg,
  596             cmparg);
  597         
  598         /* XXX: Linux verifies access here and returns EFAULT */
  599         LIN_SDT_PROBE0(futex, futex_atomic_op, missing_access_check);
  600 
  601         switch (op) {
  602         case FUTEX_OP_SET:
  603                 ret = futex_xchgl(oparg, uaddr, &oldval);
  604                 break;
  605         case FUTEX_OP_ADD:
  606                 ret = futex_addl(oparg, uaddr, &oldval);
  607                 break;
  608         case FUTEX_OP_OR:
  609                 ret = futex_orl(oparg, uaddr, &oldval);
  610                 break;
  611         case FUTEX_OP_ANDN:
  612                 ret = futex_andl(~oparg, uaddr, &oldval);
  613                 break;
  614         case FUTEX_OP_XOR:
  615                 ret = futex_xorl(oparg, uaddr, &oldval);
  616                 break;
  617         default:
  618                 LIN_SDT_PROBE1(futex, futex_atomic_op, unimplemented_op, op);
  619                 ret = -ENOSYS;
  620                 break;
  621         }
  622 
  623         if (ret) {
  624                 LIN_SDT_PROBE1(futex, futex_atomic_op, return, ret);
  625                 return (ret);
  626         }
  627 
  628         switch (cmp) {
  629         case FUTEX_OP_CMP_EQ:
  630                 ret = (oldval == cmparg);
  631                 break;
  632         case FUTEX_OP_CMP_NE:
  633                 ret = (oldval != cmparg);
  634                 break;
  635         case FUTEX_OP_CMP_LT:
  636                 ret = (oldval < cmparg);
  637                 break;
  638         case FUTEX_OP_CMP_GE:
  639                 ret = (oldval >= cmparg);
  640                 break;
  641         case FUTEX_OP_CMP_LE:
  642                 ret = (oldval <= cmparg);
  643                 break;
  644         case FUTEX_OP_CMP_GT:
  645                 ret = (oldval > cmparg);
  646                 break;
  647         default:
  648                 LIN_SDT_PROBE1(futex, futex_atomic_op, unimplemented_cmp, cmp);
  649                 ret = -ENOSYS;
  650         }
  651 
  652         LIN_SDT_PROBE1(futex, futex_atomic_op, return, ret);
  653         return (ret);
  654 }
  655 
  656 int
  657 linux_sys_futex(struct thread *td, struct linux_sys_futex_args *args)
  658 {
  659         int clockrt, nrwake, op_ret, ret;
  660         struct linux_emuldata *em;
  661         struct waiting_proc *wp;
  662         struct futex *f, *f2;
  663         struct l_timespec timeout;
  664         struct timeval utv, ctv;
  665         int timeout_hz;
  666         int error;
  667         uint32_t flags, val;
  668 
  669         LIN_SDT_PROBE2(futex, linux_sys_futex, entry, td, args);
  670 
  671         if (args->op & LINUX_FUTEX_PRIVATE_FLAG) {
  672                 flags = 0;
  673                 args->op &= ~LINUX_FUTEX_PRIVATE_FLAG;
  674         } else
  675                 flags = FUTEX_SHARED;
  676 
  677         /*
  678          * Currently support for switching between CLOCK_MONOTONIC and
  679          * CLOCK_REALTIME is not present. However Linux forbids the use of
  680          * FUTEX_CLOCK_REALTIME with any op except FUTEX_WAIT_BITSET and
  681          * FUTEX_WAIT_REQUEUE_PI.
  682          */
  683         clockrt = args->op & LINUX_FUTEX_CLOCK_REALTIME;
  684         args->op = args->op & ~LINUX_FUTEX_CLOCK_REALTIME;
  685         if (clockrt && args->op != LINUX_FUTEX_WAIT_BITSET &&
  686                 args->op != LINUX_FUTEX_WAIT_REQUEUE_PI) {
  687                 LIN_SDT_PROBE0(futex, linux_sys_futex,
  688                     unimplemented_clockswitch);
  689                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
  690                 return (ENOSYS);
  691         }
  692 
  693         error = 0;
  694         f = f2 = NULL;
  695 
  696         switch (args->op) {
  697         case LINUX_FUTEX_WAIT:
  698                 args->val3 = FUTEX_BITSET_MATCH_ANY;
  699                 /* FALLTHROUGH */
  700 
  701         case LINUX_FUTEX_WAIT_BITSET:
  702                 LIN_SDT_PROBE3(futex, linux_sys_futex, debug_wait, args->uaddr,
  703                     args->val, args->val3);
  704                 LINUX_CTR3(sys_futex, "WAIT uaddr %p val 0x%x bitset 0x%x",
  705                     args->uaddr, args->val, args->val3);
  706 
  707                 error = futex_get(args->uaddr, &wp, &f,
  708                     flags | FUTEX_CREATE_WP);
  709                 if (error) {
  710                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  711                         return (error);
  712                 }
  713 
  714                 error = copyin(args->uaddr, &val, sizeof(val));
  715                 if (error) {
  716                         LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error,
  717                             error);
  718                         LINUX_CTR1(sys_futex, "WAIT copyin failed %d",
  719                             error);
  720                         futex_put(f, wp);
  721 
  722                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  723                         return (error);
  724                 }
  725                 if (val != args->val) {
  726                         LIN_SDT_PROBE4(futex, linux_sys_futex,
  727                             debug_wait_value_neq, args->uaddr, args->val, val,
  728                             args->val3);
  729                         LINUX_CTR3(sys_futex,
  730                             "WAIT uaddr %p val 0x%x != uval 0x%x",
  731                             args->uaddr, args->val, val);
  732                         futex_put(f, wp);
  733 
  734                         LIN_SDT_PROBE1(futex, linux_sys_futex, return,
  735                             EWOULDBLOCK);
  736                         return (EWOULDBLOCK);
  737                 }
  738 
  739                 if (args->timeout != NULL) {
  740                         error = copyin(args->timeout, &timeout, sizeof(timeout));
  741                         if (error) {
  742                                 LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error,
  743                                     error);
  744                                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  745                                 futex_put(f, wp);
  746                                 return (error);
  747                         }
  748                         TIMESPEC_TO_TIMEVAL(&utv, &timeout);
  749                         error = itimerfix(&utv);
  750                         if (error) {
  751                                 LIN_SDT_PROBE1(futex, linux_sys_futex, itimerfix_error,
  752                                     error);
  753                                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  754                                 futex_put(f, wp);
  755                                 return (error);
  756                         }
  757                         if (clockrt) {
  758                                 microtime(&ctv);
  759                                 timevalsub(&utv, &ctv);
  760                         } else if (args->op == LINUX_FUTEX_WAIT_BITSET) {
  761                                 microuptime(&ctv);
  762                                 timevalsub(&utv, &ctv);
  763                         }
  764                         if (utv.tv_sec < 0)
  765                                 timevalclear(&utv);
  766                         timeout_hz = tvtohz(&utv);
  767                 } else
  768                         timeout_hz = 0;
  769 
  770                 error = futex_wait(f, wp, timeout_hz, args->val3);
  771                 break;
  772 
  773         case LINUX_FUTEX_WAKE:
  774                 args->val3 = FUTEX_BITSET_MATCH_ANY;
  775                 /* FALLTHROUGH */
  776 
  777         case LINUX_FUTEX_WAKE_BITSET:
  778                 LIN_SDT_PROBE3(futex, linux_sys_futex, debug_wake, args->uaddr,
  779                     args->val, args->val3);
  780                 LINUX_CTR3(sys_futex, "WAKE uaddr %p nrwake 0x%x bitset 0x%x",
  781                     args->uaddr, args->val, args->val3);
  782 
  783                 error = futex_get(args->uaddr, NULL, &f,
  784                     flags | FUTEX_DONTCREATE);
  785                 if (error) {
  786                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  787                         return (error);
  788                 }
  789 
  790                 if (f == NULL) {
  791                         td->td_retval[0] = 0;
  792 
  793                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  794                         return (error);
  795                 }
  796                 td->td_retval[0] = futex_wake(f, args->val, args->val3);
  797                 futex_put(f, NULL);
  798                 break;
  799 
  800         case LINUX_FUTEX_CMP_REQUEUE:
  801                 LIN_SDT_PROBE5(futex, linux_sys_futex, debug_cmp_requeue,
  802                     args->uaddr, args->val, args->val3, args->uaddr2,
  803                     args->timeout);
  804                 LINUX_CTR5(sys_futex, "CMP_REQUEUE uaddr %p "
  805                     "nrwake 0x%x uval 0x%x uaddr2 %p nrequeue 0x%x",
  806                     args->uaddr, args->val, args->val3, args->uaddr2,
  807                     args->timeout);
  808 
  809                 /*
  810                  * Linux allows this, we would not, it is an incorrect
  811                  * usage of declared ABI, so return EINVAL.
  812                  */
  813                 if (args->uaddr == args->uaddr2) {
  814                         LIN_SDT_PROBE0(futex, linux_sys_futex,
  815                             invalid_cmp_requeue_use);
  816                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, EINVAL);
  817                         return (EINVAL);
  818                 }
  819 
  820                 error = futex_get(args->uaddr, NULL, &f, flags);
  821                 if (error) {
  822                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  823                         return (error);
  824                 }
  825 
  826                 /*
  827                  * To avoid deadlocks return EINVAL if second futex
  828                  * exists at this time.
  829                  *
  830                  * Glibc fall back to FUTEX_WAKE in case of any error
  831                  * returned by FUTEX_CMP_REQUEUE.
  832                  */
  833                 error = futex_get(args->uaddr2, NULL, &f2,
  834                     flags | FUTEX_DONTEXISTS);
  835                 if (error) {
  836                         futex_put(f, NULL);
  837 
  838                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  839                         return (error);
  840                 }
  841                 error = copyin(args->uaddr, &val, sizeof(val));
  842                 if (error) {
  843                         LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error,
  844                             error);
  845                         LINUX_CTR1(sys_futex, "CMP_REQUEUE copyin failed %d",
  846                             error);
  847                         futex_put(f2, NULL);
  848                         futex_put(f, NULL);
  849 
  850                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  851                         return (error);
  852                 }
  853                 if (val != args->val3) {
  854                         LIN_SDT_PROBE2(futex, linux_sys_futex,
  855                             debug_cmp_requeue_value_neq, args->val, val);
  856                         LINUX_CTR2(sys_futex, "CMP_REQUEUE val 0x%x != uval 0x%x",
  857                             args->val, val);
  858                         futex_put(f2, NULL);
  859                         futex_put(f, NULL);
  860 
  861                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, EAGAIN);
  862                         return (EAGAIN);
  863                 }
  864 
  865                 nrwake = (int)(unsigned long)args->timeout;
  866                 td->td_retval[0] = futex_requeue(f, args->val, f2, nrwake);
  867                 futex_put(f2, NULL);
  868                 futex_put(f, NULL);
  869                 break;
  870 
  871         case LINUX_FUTEX_WAKE_OP:
  872                 LIN_SDT_PROBE5(futex, linux_sys_futex, debug_wake_op,
  873                     args->uaddr, args->op, args->val, args->uaddr2, args->val3);
  874                 LINUX_CTR5(sys_futex, "WAKE_OP "
  875                     "uaddr %p nrwake 0x%x uaddr2 %p op 0x%x nrwake2 0x%x",
  876                     args->uaddr, args->val, args->uaddr2, args->val3,
  877                     args->timeout);
  878 
  879                 error = futex_get(args->uaddr, NULL, &f, flags);
  880                 if (error) {
  881                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  882                         return (error);
  883                 }
  884 
  885                 if (args->uaddr != args->uaddr2)
  886                         error = futex_get(args->uaddr2, NULL, &f2, flags);
  887                 if (error) {
  888                         futex_put(f, NULL);
  889 
  890                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  891                         return (error);
  892                 }
  893 
  894                 /*
  895                  * This function returns positive number as results and
  896                  * negative as errors
  897                  */
  898                 op_ret = futex_atomic_op(td, args->val3, args->uaddr2);
  899 
  900                 LINUX_CTR2(sys_futex, "WAKE_OP atomic_op uaddr %p ret 0x%x",
  901                     args->uaddr, op_ret);
  902 
  903                 if (op_ret < 0) {
  904                         /* XXX: We don't handle the EFAULT yet. */
  905                         if (op_ret != -EFAULT) {
  906                                 if (f2 != NULL)
  907                                         futex_put(f2, NULL);
  908                                 futex_put(f, NULL);
  909 
  910                                 LIN_SDT_PROBE1(futex, linux_sys_futex, return,
  911                                     -op_ret);
  912                                 return (-op_ret);
  913                         } else {
  914                                 LIN_SDT_PROBE0(futex, linux_sys_futex,
  915                                     unhandled_efault);
  916                         }
  917                         if (f2 != NULL)
  918                                 futex_put(f2, NULL);
  919                         futex_put(f, NULL);
  920 
  921                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, EFAULT);
  922                         return (EFAULT);
  923                 }
  924 
  925                 ret = futex_wake(f, args->val, args->val3);
  926 
  927                 if (op_ret > 0) {
  928                         op_ret = 0;
  929                         nrwake = (int)(unsigned long)args->timeout;
  930 
  931                         if (f2 != NULL)
  932                                 op_ret += futex_wake(f2, nrwake, args->val3);
  933                         else
  934                                 op_ret += futex_wake(f, nrwake, args->val3);
  935                         ret += op_ret;
  936 
  937                 }
  938                 if (f2 != NULL)
  939                         futex_put(f2, NULL);
  940                 futex_put(f, NULL);
  941                 td->td_retval[0] = ret;
  942                 break;
  943 
  944         case LINUX_FUTEX_LOCK_PI:
  945                 /* not yet implemented */
  946                 linux_msg(td,
  947                           "linux_sys_futex: "
  948                           "op LINUX_FUTEX_LOCK_PI not implemented\n");
  949                 LIN_SDT_PROBE0(futex, linux_sys_futex, unimplemented_lock_pi);
  950                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
  951                 return (ENOSYS);
  952 
  953         case LINUX_FUTEX_UNLOCK_PI:
  954                 /* not yet implemented */
  955                 linux_msg(td,
  956                           "linux_sys_futex: "
  957                           "op LINUX_FUTEX_UNLOCK_PI not implemented\n");
  958                 LIN_SDT_PROBE0(futex, linux_sys_futex, unimplemented_unlock_pi);
  959                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
  960                 return (ENOSYS);
  961 
  962         case LINUX_FUTEX_TRYLOCK_PI:
  963                 /* not yet implemented */
  964                 linux_msg(td,
  965                           "linux_sys_futex: "
  966                           "op LINUX_FUTEX_TRYLOCK_PI not implemented\n");
  967                 LIN_SDT_PROBE0(futex, linux_sys_futex,
  968                     unimplemented_trylock_pi);
  969                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
  970                 return (ENOSYS);
  971 
  972         case LINUX_FUTEX_REQUEUE:
  973 
  974                 /*
  975                  * Glibc does not use this operation since version 2.3.3,
  976                  * as it is racy and replaced by FUTEX_CMP_REQUEUE operation.
  977                  * Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when
  978                  * FUTEX_REQUEUE returned EINVAL.
  979                  */
  980                 em = em_find(td->td_proc, EMUL_DONTLOCK);
  981                 if ((em->flags & LINUX_XDEPR_REQUEUEOP) == 0) {
  982                         linux_msg(td,
  983                                   "linux_sys_futex: "
  984                                   "unsupported futex_requeue op\n");
  985                         em->flags |= LINUX_XDEPR_REQUEUEOP;
  986                         LIN_SDT_PROBE0(futex, linux_sys_futex,
  987                             deprecated_requeue);
  988                 }
  989 
  990                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, EINVAL);
  991                 return (EINVAL);
  992 
  993         case LINUX_FUTEX_WAIT_REQUEUE_PI:
  994                 /* not yet implemented */
  995                 linux_msg(td,
  996                           "linux_sys_futex: "
  997                           "op FUTEX_WAIT_REQUEUE_PI not implemented\n");
  998                 LIN_SDT_PROBE0(futex, linux_sys_futex,
  999                     unimplemented_wait_requeue_pi);
 1000                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
 1001                 return (ENOSYS);
 1002 
 1003         case LINUX_FUTEX_CMP_REQUEUE_PI:
 1004                 /* not yet implemented */
 1005                 linux_msg(td,
 1006                             "linux_sys_futex: "
 1007                             "op LINUX_FUTEX_CMP_REQUEUE_PI not implemented\n");
 1008                 LIN_SDT_PROBE0(futex, linux_sys_futex,
 1009                     unimplemented_cmp_requeue_pi);
 1010                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
 1011                 return (ENOSYS);
 1012 
 1013         default:
 1014                 linux_msg(td,
 1015                           "linux_sys_futex: unknown op %d\n", args->op);
 1016                 LIN_SDT_PROBE1(futex, linux_sys_futex, unknown_operation,
 1017                     args->op);
 1018                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
 1019                 return (ENOSYS);
 1020         }
 1021 
 1022         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 1023         return (error);
 1024 }
 1025 
 1026 int
 1027 linux_set_robust_list(struct thread *td, struct linux_set_robust_list_args *args)
 1028 {
 1029         struct linux_emuldata *em;
 1030 
 1031         LIN_SDT_PROBE2(futex, linux_set_robust_list, entry, td, args);
 1032 
 1033         if (args->len != sizeof(struct linux_robust_list_head)) {
 1034                 LIN_SDT_PROBE0(futex, linux_set_robust_list, size_error);
 1035                 LIN_SDT_PROBE1(futex, linux_set_robust_list, return, EINVAL);
 1036                 return (EINVAL);
 1037         }
 1038 
 1039         em = em_find(td->td_proc, EMUL_DOLOCK);
 1040         em->robust_futexes = args->head;
 1041         EMUL_UNLOCK(&emul_lock);
 1042 
 1043         LIN_SDT_PROBE1(futex, linux_set_robust_list, return, 0);
 1044         return (0);
 1045 }
 1046 
 1047 int
 1048 linux_get_robust_list(struct thread *td, struct linux_get_robust_list_args *args)
 1049 {
 1050         struct linux_emuldata *em;
 1051         struct linux_robust_list_head *head;
 1052         l_size_t len = sizeof(struct linux_robust_list_head);
 1053         int error = 0;
 1054 
 1055         LIN_SDT_PROBE2(futex, linux_get_robust_list, entry, td, args);
 1056 
 1057         if (!args->pid) {
 1058                 em = em_find(td->td_proc, EMUL_DONTLOCK);
 1059                 head = em->robust_futexes;
 1060         } else {
 1061                 struct proc *p;
 1062 
 1063                 p = pfind(args->pid);
 1064                 if (p == NULL) {
 1065                         LIN_SDT_PROBE1(futex, linux_get_robust_list, return,
 1066                             ESRCH);
 1067                         return (ESRCH);
 1068                 }
 1069 
 1070                 em = em_find(p, EMUL_DONTLOCK);
 1071                 /* XXX: ptrace? */
 1072                 if (priv_check(td, PRIV_CRED_SETUID) ||
 1073                     priv_check(td, PRIV_CRED_SETEUID) ||
 1074                     p_candebug(td, p)) {
 1075                         PROC_UNLOCK(p);
 1076 
 1077                         LIN_SDT_PROBE1(futex, linux_get_robust_list, return,
 1078                             EPERM);
 1079                         return (EPERM);
 1080                 }
 1081                 head = em->robust_futexes;
 1082 
 1083                 PROC_UNLOCK(p);
 1084         }
 1085 
 1086         error = copyout(&len, args->len, sizeof(l_size_t));
 1087         if (error) {
 1088                 LIN_SDT_PROBE1(futex, linux_get_robust_list, copyout_error,
 1089                     error);
 1090                 LIN_SDT_PROBE1(futex, linux_get_robust_list, return, EFAULT);
 1091                 return (EFAULT);
 1092         }
 1093 
 1094         error = copyout(&head, args->head, sizeof(head));
 1095         if (error) {
 1096                 LIN_SDT_PROBE1(futex, linux_get_robust_list, copyout_error,
 1097                     error);
 1098         }
 1099 
 1100         LIN_SDT_PROBE1(futex, linux_get_robust_list, return, error);
 1101         return (error);
 1102 }
 1103 
 1104 static int
 1105 handle_futex_death(struct proc *p, uint32_t *uaddr, unsigned int pi)
 1106 {
 1107         uint32_t uval, nval, mval;
 1108         struct futex *f;
 1109         int error;
 1110 
 1111         LIN_SDT_PROBE3(futex, handle_futex_death, entry, p, uaddr, pi);
 1112 
 1113 retry:
 1114         error = copyin(uaddr, &uval, 4);
 1115         if (error) {
 1116                 LIN_SDT_PROBE1(futex, handle_futex_death, copyin_error, error);
 1117                 LIN_SDT_PROBE1(futex, handle_futex_death, return, EFAULT);
 1118                 return (EFAULT);
 1119         }
 1120         if ((uval & FUTEX_TID_MASK) == p->p_pid) {
 1121                 mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED;
 1122                 nval = casuword32(uaddr, uval, mval);
 1123 
 1124                 if (nval == -1) {
 1125                         LIN_SDT_PROBE1(futex, handle_futex_death, return,
 1126                             EFAULT);
 1127                         return (EFAULT);
 1128                 }
 1129 
 1130                 if (nval != uval)
 1131                         goto retry;
 1132 
 1133                 if (!pi && (uval & FUTEX_WAITERS)) {
 1134                         error = futex_get(uaddr, NULL, &f,
 1135                             FUTEX_DONTCREATE | FUTEX_SHARED);
 1136                         if (error) {
 1137                                 LIN_SDT_PROBE1(futex, handle_futex_death,
 1138                                     return, error);
 1139                                 return (error);
 1140                         }
 1141                         if (f != NULL) {
 1142                                 futex_wake(f, 1, FUTEX_BITSET_MATCH_ANY);
 1143                                 futex_put(f, NULL);
 1144                         }
 1145                 }
 1146         }
 1147 
 1148         LIN_SDT_PROBE1(futex, handle_futex_death, return, 0);
 1149         return (0);
 1150 }
 1151 
 1152 static int
 1153 fetch_robust_entry(struct linux_robust_list **entry,
 1154     struct linux_robust_list **head, unsigned int *pi)
 1155 {
 1156         l_ulong uentry;
 1157         int error;
 1158 
 1159         LIN_SDT_PROBE3(futex, fetch_robust_entry, entry, entry, head, pi);
 1160 
 1161         error = copyin((const void *)head, &uentry, sizeof(l_ulong));
 1162         if (error) {
 1163                 LIN_SDT_PROBE1(futex, fetch_robust_entry, copyin_error, error);
 1164                 LIN_SDT_PROBE1(futex, fetch_robust_entry, return, EFAULT);
 1165                 return (EFAULT);
 1166         }
 1167 
 1168         *entry = (void *)(uentry & ~1UL);
 1169         *pi = uentry & 1;
 1170 
 1171         LIN_SDT_PROBE1(futex, fetch_robust_entry, return, 0);
 1172         return (0);
 1173 }
 1174 
 1175 /* This walks the list of robust futexes releasing them. */
 1176 void
 1177 release_futexes(struct proc *p)
 1178 {
 1179         struct linux_robust_list_head *head = NULL;
 1180         struct linux_robust_list *entry, *next_entry, *pending;
 1181         unsigned int limit = 2048, pi, next_pi, pip;
 1182         struct linux_emuldata *em;
 1183         l_long futex_offset;
 1184         int rc, error;
 1185 
 1186         LIN_SDT_PROBE1(futex, release_futexes, entry, p);
 1187 
 1188         em = em_find(p, EMUL_DONTLOCK);
 1189         head = em->robust_futexes;
 1190 
 1191         if (head == NULL) {
 1192                 LIN_SDT_PROBE0(futex, release_futexes, return);
 1193                 return;
 1194         }
 1195 
 1196         if (fetch_robust_entry(&entry, PTRIN(&head->list.next), &pi)) {
 1197                 LIN_SDT_PROBE0(futex, release_futexes, return);
 1198                 return;
 1199         }
 1200 
 1201         error = copyin(&head->futex_offset, &futex_offset,
 1202             sizeof(futex_offset));
 1203         if (error) {
 1204                 LIN_SDT_PROBE1(futex, release_futexes, copyin_error, error);
 1205                 LIN_SDT_PROBE0(futex, release_futexes, return);
 1206                 return;
 1207         }
 1208 
 1209         if (fetch_robust_entry(&pending, PTRIN(&head->pending_list), &pip)) {
 1210                 LIN_SDT_PROBE0(futex, release_futexes, return);
 1211                 return;
 1212         }
 1213 
 1214         while (entry != &head->list) {
 1215                 rc = fetch_robust_entry(&next_entry, PTRIN(&entry->next), &next_pi);
 1216 
 1217                 if (entry != pending)
 1218                         if (handle_futex_death(p,
 1219                             (uint32_t *)((caddr_t)entry + futex_offset), pi)) {
 1220                                 LIN_SDT_PROBE0(futex, release_futexes, return);
 1221                                 return;
 1222                         }
 1223                 if (rc) {
 1224                         LIN_SDT_PROBE0(futex, release_futexes, return);
 1225                         return;
 1226                 }
 1227 
 1228                 entry = next_entry;
 1229                 pi = next_pi;
 1230 
 1231                 if (!--limit)
 1232                         break;
 1233 
 1234                 sched_relinquish(curthread);
 1235         }
 1236 
 1237         if (pending)
 1238                 handle_futex_death(p, (uint32_t *)((caddr_t)pending + futex_offset), pip);
 1239 
 1240         LIN_SDT_PROBE0(futex, release_futexes, return);
 1241 }

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