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/10.3/sys/compat/linux/linux_futex.c 293897 2016-01-14 09:11:42Z 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_timer.h>
   70 #include <compat/linux/linux_util.h>
   71 
   72 /* DTrace init */
   73 LIN_SDT_PROVIDER_DECLARE(LINUX_DTRACE);
   74 
   75 /**
   76  * Futex part for the special DTrace module "locks".
   77  */
   78 LIN_SDT_PROBE_DEFINE1(locks, futex_mtx, locked, "struct mtx *");
   79 LIN_SDT_PROBE_DEFINE1(locks, futex_mtx, unlock, "struct mtx *");
   80 
   81 /**
   82  * Per futex probes.
   83  */
   84 LIN_SDT_PROBE_DEFINE1(futex, futex, create, "struct sx *");
   85 LIN_SDT_PROBE_DEFINE1(futex, futex, destroy, "struct sx *");
   86 
   87 /**
   88  * DTrace probes in this module.
   89  */
   90 LIN_SDT_PROBE_DEFINE2(futex, futex_put, entry, "struct futex *",
   91     "struct waiting_proc *");
   92 LIN_SDT_PROBE_DEFINE3(futex, futex_put, destroy, "uint32_t *", "uint32_t",
   93     "int");
   94 LIN_SDT_PROBE_DEFINE3(futex, futex_put, unlock, "uint32_t *", "uint32_t",
   95     "int");
   96 LIN_SDT_PROBE_DEFINE0(futex, futex_put, return);
   97 LIN_SDT_PROBE_DEFINE3(futex, futex_get0, entry, "uint32_t *", "struct futex **",
   98     "uint32_t");
   99 LIN_SDT_PROBE_DEFINE1(futex, futex_get0, umtx_key_get_error, "int");
  100 LIN_SDT_PROBE_DEFINE3(futex, futex_get0, shared, "uint32_t *", "uint32_t",
  101     "int");
  102 LIN_SDT_PROBE_DEFINE1(futex, futex_get0, null, "uint32_t *");
  103 LIN_SDT_PROBE_DEFINE3(futex, futex_get0, new, "uint32_t *", "uint32_t", "int");
  104 LIN_SDT_PROBE_DEFINE1(futex, futex_get0, return, "int");
  105 LIN_SDT_PROBE_DEFINE3(futex, futex_get, entry, "uint32_t *",
  106     "struct waiting_proc **", "struct futex **");
  107 LIN_SDT_PROBE_DEFINE0(futex, futex_get, error);
  108 LIN_SDT_PROBE_DEFINE1(futex, futex_get, return, "int");
  109 LIN_SDT_PROBE_DEFINE3(futex, futex_sleep, entry, "struct futex *",
  110     "struct waiting_proc **", "int");
  111 LIN_SDT_PROBE_DEFINE5(futex, futex_sleep, requeue_error, "int", "uint32_t *",
  112     "struct waiting_proc *", "uint32_t *", "uint32_t");
  113 LIN_SDT_PROBE_DEFINE3(futex, futex_sleep, sleep_error, "int", "uint32_t *",
  114     "struct waiting_proc *");
  115 LIN_SDT_PROBE_DEFINE1(futex, futex_sleep, return, "int");
  116 LIN_SDT_PROBE_DEFINE3(futex, futex_wake, entry, "struct futex *", "int",
  117     "uint32_t");
  118 LIN_SDT_PROBE_DEFINE3(futex, futex_wake, iterate, "uint32_t",
  119     "struct waiting_proc *", "uint32_t");
  120 LIN_SDT_PROBE_DEFINE1(futex, futex_wake, wakeup, "struct waiting_proc *");
  121 LIN_SDT_PROBE_DEFINE1(futex, futex_wake, return, "int");
  122 LIN_SDT_PROBE_DEFINE4(futex, futex_requeue, entry, "struct futex *", "int",
  123     "struct futex *", "int");
  124 LIN_SDT_PROBE_DEFINE1(futex, futex_requeue, wakeup, "struct waiting_proc *");
  125 LIN_SDT_PROBE_DEFINE3(futex, futex_requeue, requeue, "uint32_t *",
  126     "struct waiting_proc *", "uint32_t");
  127 LIN_SDT_PROBE_DEFINE1(futex, futex_requeue, return, "int");
  128 LIN_SDT_PROBE_DEFINE4(futex, futex_wait, entry, "struct futex *",
  129     "struct waiting_proc **", "int", "uint32_t");
  130 LIN_SDT_PROBE_DEFINE1(futex, futex_wait, sleep_error, "int");
  131 LIN_SDT_PROBE_DEFINE1(futex, futex_wait, return, "int");
  132 LIN_SDT_PROBE_DEFINE3(futex, futex_atomic_op, entry, "struct thread *",
  133     "int", "uint32_t");
  134 LIN_SDT_PROBE_DEFINE4(futex, futex_atomic_op, decoded_op, "int", "int", "int",
  135     "int");
  136 LIN_SDT_PROBE_DEFINE0(futex, futex_atomic_op, missing_access_check);
  137 LIN_SDT_PROBE_DEFINE1(futex, futex_atomic_op, unimplemented_op, "int");
  138 LIN_SDT_PROBE_DEFINE1(futex, futex_atomic_op, unimplemented_cmp, "int");
  139 LIN_SDT_PROBE_DEFINE1(futex, futex_atomic_op, return, "int");
  140 LIN_SDT_PROBE_DEFINE2(futex, linux_sys_futex, entry, "struct thread *",
  141     "struct linux_sys_futex_args *");
  142 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_clockswitch);
  143 LIN_SDT_PROBE_DEFINE1(futex, linux_sys_futex, itimerfix_error, "int");
  144 LIN_SDT_PROBE_DEFINE1(futex, linux_sys_futex, copyin_error, "int");
  145 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, invalid_cmp_requeue_use);
  146 LIN_SDT_PROBE_DEFINE3(futex, linux_sys_futex, debug_wait, "uint32_t *",
  147     "uint32_t", "uint32_t");
  148 LIN_SDT_PROBE_DEFINE4(futex, linux_sys_futex, debug_wait_value_neq,
  149     "uint32_t *", "uint32_t", "int", "uint32_t");
  150 LIN_SDT_PROBE_DEFINE3(futex, linux_sys_futex, debug_wake, "uint32_t *",
  151     "uint32_t", "uint32_t");
  152 LIN_SDT_PROBE_DEFINE5(futex, linux_sys_futex, debug_cmp_requeue, "uint32_t *",
  153     "uint32_t", "uint32_t", "uint32_t *", "struct l_timespec *");
  154 LIN_SDT_PROBE_DEFINE2(futex, linux_sys_futex, debug_cmp_requeue_value_neq,
  155     "uint32_t", "int");
  156 LIN_SDT_PROBE_DEFINE5(futex, linux_sys_futex, debug_wake_op, "uint32_t *",
  157     "int", "uint32_t", "uint32_t *", "uint32_t");
  158 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unhandled_efault);
  159 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_lock_pi);
  160 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_unlock_pi);
  161 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_trylock_pi);
  162 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, deprecated_requeue);
  163 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_wait_requeue_pi);
  164 LIN_SDT_PROBE_DEFINE0(futex, linux_sys_futex, unimplemented_cmp_requeue_pi);
  165 LIN_SDT_PROBE_DEFINE1(futex, linux_sys_futex, unknown_operation, "int");
  166 LIN_SDT_PROBE_DEFINE1(futex, linux_sys_futex, return, "int");
  167 LIN_SDT_PROBE_DEFINE2(futex, linux_set_robust_list, entry, "struct thread *",
  168     "struct linux_set_robust_list_args *");
  169 LIN_SDT_PROBE_DEFINE0(futex, linux_set_robust_list, size_error);
  170 LIN_SDT_PROBE_DEFINE1(futex, linux_set_robust_list, return, "int");
  171 LIN_SDT_PROBE_DEFINE2(futex, linux_get_robust_list, entry, "struct thread *",
  172     "struct linux_get_robust_list_args *");
  173 LIN_SDT_PROBE_DEFINE1(futex, linux_get_robust_list, copyout_error, "int");
  174 LIN_SDT_PROBE_DEFINE1(futex, linux_get_robust_list, return, "int");
  175 LIN_SDT_PROBE_DEFINE3(futex, handle_futex_death, entry,
  176     "struct linux_emuldata *", "uint32_t *", "unsigned int");
  177 LIN_SDT_PROBE_DEFINE1(futex, handle_futex_death, copyin_error, "int");
  178 LIN_SDT_PROBE_DEFINE1(futex, handle_futex_death, return, "int");
  179 LIN_SDT_PROBE_DEFINE3(futex, fetch_robust_entry, entry,
  180     "struct linux_robust_list **", "struct linux_robust_list **",
  181     "unsigned int *");
  182 LIN_SDT_PROBE_DEFINE1(futex, fetch_robust_entry, copyin_error, "int");
  183 LIN_SDT_PROBE_DEFINE1(futex, fetch_robust_entry, return, "int");
  184 LIN_SDT_PROBE_DEFINE2(futex, release_futexes, entry, "struct thread *",
  185     "struct linux_emuldata *");
  186 LIN_SDT_PROBE_DEFINE1(futex, release_futexes, copyin_error, "int");
  187 LIN_SDT_PROBE_DEFINE0(futex, release_futexes, return);
  188 
  189 struct futex;
  190 
  191 struct waiting_proc {
  192         uint32_t        wp_flags;
  193         struct futex    *wp_futex;
  194         TAILQ_ENTRY(waiting_proc) wp_list;
  195 };
  196 
  197 struct futex {
  198         struct sx       f_lck;
  199         uint32_t        *f_uaddr;       /* user-supplied value, for debug */
  200         struct umtx_key f_key;
  201         uint32_t        f_refcount;
  202         uint32_t        f_bitset;
  203         LIST_ENTRY(futex) f_list;
  204         TAILQ_HEAD(lf_waiting_proc, waiting_proc) f_waiting_proc;
  205 };
  206 
  207 struct futex_list futex_list;
  208 
  209 #define FUTEX_LOCK(f)           sx_xlock(&(f)->f_lck)
  210 #define FUTEX_UNLOCK(f)         sx_xunlock(&(f)->f_lck)
  211 #define FUTEX_INIT(f)           do { \
  212                                     sx_init_flags(&(f)->f_lck, "ftlk", \
  213                                         SX_DUPOK); \
  214                                     LIN_SDT_PROBE1(futex, futex, create, \
  215                                         &(f)->f_lck); \
  216                                 } while (0)
  217 #define FUTEX_DESTROY(f)        do { \
  218                                     LIN_SDT_PROBE1(futex, futex, destroy, \
  219                                         &(f)->f_lck); \
  220                                     sx_destroy(&(f)->f_lck); \
  221                                 } while (0)
  222 #define FUTEX_ASSERT_LOCKED(f)  sx_assert(&(f)->f_lck, SA_XLOCKED)
  223 
  224 struct mtx futex_mtx;                   /* protects the futex list */
  225 #define FUTEXES_LOCK            do { \
  226                                     mtx_lock(&futex_mtx); \
  227                                     LIN_SDT_PROBE1(locks, futex_mtx, \
  228                                         locked, &futex_mtx); \
  229                                 } while (0)
  230 #define FUTEXES_UNLOCK          do { \
  231                                     LIN_SDT_PROBE1(locks, futex_mtx, \
  232                                         unlock, &futex_mtx); \
  233                                     mtx_unlock(&futex_mtx); \
  234                                 } while (0)
  235 
  236 /* flags for futex_get() */
  237 #define FUTEX_CREATE_WP         0x1     /* create waiting_proc */
  238 #define FUTEX_DONTCREATE        0x2     /* don't create futex if not exists */
  239 #define FUTEX_DONTEXISTS        0x4     /* return EINVAL if futex exists */
  240 #define FUTEX_SHARED            0x8     /* shared futex */
  241 
  242 /* wp_flags */
  243 #define FUTEX_WP_REQUEUED       0x1     /* wp requeued - wp moved from wp_list
  244                                          * of futex where thread sleep to wp_list
  245                                          * of another futex.
  246                                          */
  247 #define FUTEX_WP_REMOVED        0x2     /* wp is woken up and removed from futex
  248                                          * wp_list to prevent double wakeup.
  249                                          */
  250 
  251 static void futex_put(struct futex *, struct waiting_proc *);
  252 static int futex_get0(uint32_t *, struct futex **f, uint32_t);
  253 static int futex_get(uint32_t *, struct waiting_proc **, struct futex **,
  254     uint32_t);
  255 static int futex_sleep(struct futex *, struct waiting_proc *, int);
  256 static int futex_wake(struct futex *, int, uint32_t);
  257 static int futex_requeue(struct futex *, int, struct futex *, int);
  258 static int futex_wait(struct futex *, struct waiting_proc *, int,
  259     uint32_t);
  260 static int futex_atomic_op(struct thread *, int, uint32_t *);
  261 static int handle_futex_death(struct linux_emuldata *, uint32_t *,
  262     unsigned int);
  263 static int fetch_robust_entry(struct linux_robust_list **,
  264     struct linux_robust_list **, unsigned int *);
  265 
  266 /* support.s */
  267 int futex_xchgl(int oparg, uint32_t *uaddr, int *oldval);
  268 int futex_addl(int oparg, uint32_t *uaddr, int *oldval);
  269 int futex_orl(int oparg, uint32_t *uaddr, int *oldval);
  270 int futex_andl(int oparg, uint32_t *uaddr, int *oldval);
  271 int futex_xorl(int oparg, uint32_t *uaddr, int *oldval);
  272 
  273 
  274 static void
  275 futex_put(struct futex *f, struct waiting_proc *wp)
  276 {
  277         LIN_SDT_PROBE2(futex, futex_put, entry, f, wp);
  278 
  279         FUTEX_ASSERT_LOCKED(f);
  280         if (wp != NULL) {
  281                 if ((wp->wp_flags & FUTEX_WP_REMOVED) == 0)
  282                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
  283                 free(wp, M_FUTEX_WP);
  284         }
  285 
  286         FUTEXES_LOCK;
  287         if (--f->f_refcount == 0) {
  288                 LIST_REMOVE(f, f_list);
  289                 FUTEXES_UNLOCK;
  290                 FUTEX_UNLOCK(f);
  291 
  292                 LIN_SDT_PROBE3(futex, futex_put, destroy, f->f_uaddr,
  293                     f->f_refcount, f->f_key.shared);
  294                 LINUX_CTR3(sys_futex, "futex_put destroy uaddr %p ref %d "
  295                     "shared %d", f->f_uaddr, f->f_refcount, f->f_key.shared);
  296                 umtx_key_release(&f->f_key);
  297                 FUTEX_DESTROY(f);
  298                 free(f, M_FUTEX);
  299 
  300                 LIN_SDT_PROBE0(futex, futex_put, return);
  301                 return;
  302         }
  303 
  304         LIN_SDT_PROBE3(futex, futex_put, unlock, f->f_uaddr, f->f_refcount,
  305             f->f_key.shared);
  306         LINUX_CTR3(sys_futex, "futex_put uaddr %p ref %d shared %d",
  307             f->f_uaddr, f->f_refcount, f->f_key.shared);
  308         FUTEXES_UNLOCK;
  309         FUTEX_UNLOCK(f);
  310 
  311         LIN_SDT_PROBE0(futex, futex_put, return);
  312 }
  313 
  314 static int
  315 futex_get0(uint32_t *uaddr, struct futex **newf, uint32_t flags)
  316 {
  317         struct futex *f, *tmpf;
  318         struct umtx_key key;
  319         int error;
  320 
  321         LIN_SDT_PROBE3(futex, futex_get0, entry, uaddr, newf, flags);
  322 
  323         *newf = tmpf = NULL;
  324 
  325         error = umtx_key_get(uaddr, TYPE_FUTEX, (flags & FUTEX_SHARED) ?
  326             AUTO_SHARE : THREAD_SHARE, &key);
  327         if (error) {
  328                 LIN_SDT_PROBE1(futex, futex_get0, umtx_key_get_error, error);
  329                 LIN_SDT_PROBE1(futex, futex_get0, return, error);
  330                 return (error);
  331         }
  332 retry:
  333         FUTEXES_LOCK;
  334         LIST_FOREACH(f, &futex_list, f_list) {
  335                 if (umtx_key_match(&f->f_key, &key)) {
  336                         if (tmpf != NULL) {
  337                                 FUTEX_UNLOCK(tmpf);
  338                                 FUTEX_DESTROY(tmpf);
  339                                 free(tmpf, M_FUTEX);
  340                         }
  341                         if (flags & FUTEX_DONTEXISTS) {
  342                                 FUTEXES_UNLOCK;
  343                                 umtx_key_release(&key);
  344 
  345                                 LIN_SDT_PROBE1(futex, futex_get0, return,
  346                                     EINVAL);
  347                                 return (EINVAL);
  348                         }
  349 
  350                         /*
  351                          * Increment refcount of the found futex to
  352                          * prevent it from deallocation before FUTEX_LOCK()
  353                          */
  354                         ++f->f_refcount;
  355                         FUTEXES_UNLOCK;
  356                         umtx_key_release(&key);
  357 
  358                         FUTEX_LOCK(f);
  359                         *newf = f;
  360                         LIN_SDT_PROBE3(futex, futex_get0, shared, uaddr,
  361                             f->f_refcount, f->f_key.shared);
  362                         LINUX_CTR3(sys_futex, "futex_get uaddr %p ref %d shared %d",
  363                             uaddr, f->f_refcount, f->f_key.shared);
  364 
  365                         LIN_SDT_PROBE1(futex, futex_get0, return, 0);
  366                         return (0);
  367                 }
  368         }
  369 
  370         if (flags & FUTEX_DONTCREATE) {
  371                 FUTEXES_UNLOCK;
  372                 umtx_key_release(&key);
  373                 LIN_SDT_PROBE1(futex, futex_get0, null, uaddr);
  374                 LINUX_CTR1(sys_futex, "futex_get uaddr %p null", uaddr);
  375 
  376                 LIN_SDT_PROBE1(futex, futex_get0, return, 0);
  377                 return (0);
  378         }
  379 
  380         if (tmpf == NULL) {
  381                 FUTEXES_UNLOCK;
  382                 tmpf = malloc(sizeof(*tmpf), M_FUTEX, M_WAITOK | M_ZERO);
  383                 tmpf->f_uaddr = uaddr;
  384                 tmpf->f_key = key;
  385                 tmpf->f_refcount = 1;
  386                 tmpf->f_bitset = FUTEX_BITSET_MATCH_ANY;
  387                 FUTEX_INIT(tmpf);
  388                 TAILQ_INIT(&tmpf->f_waiting_proc);
  389 
  390                 /*
  391                  * Lock the new futex before an insert into the futex_list
  392                  * to prevent futex usage by other.
  393                  */
  394                 FUTEX_LOCK(tmpf);
  395                 goto retry;
  396         }
  397 
  398         LIST_INSERT_HEAD(&futex_list, tmpf, f_list);
  399         FUTEXES_UNLOCK;
  400 
  401         LIN_SDT_PROBE3(futex, futex_get0, new, uaddr, tmpf->f_refcount,
  402             tmpf->f_key.shared);
  403         LINUX_CTR3(sys_futex, "futex_get uaddr %p ref %d shared %d new",
  404             uaddr, tmpf->f_refcount, tmpf->f_key.shared);
  405         *newf = tmpf;
  406 
  407         LIN_SDT_PROBE1(futex, futex_get0, return, 0);
  408         return (0);
  409 }
  410 
  411 static int
  412 futex_get(uint32_t *uaddr, struct waiting_proc **wp, struct futex **f,
  413     uint32_t flags)
  414 {
  415         int error;
  416 
  417         LIN_SDT_PROBE3(futex, futex_get, entry, uaddr, wp, f);
  418 
  419         if (flags & FUTEX_CREATE_WP) {
  420                 *wp = malloc(sizeof(struct waiting_proc), M_FUTEX_WP, M_WAITOK);
  421                 (*wp)->wp_flags = 0;
  422         }
  423         error = futex_get0(uaddr, f, flags);
  424         if (error) {
  425                 LIN_SDT_PROBE0(futex, futex_get, error);
  426 
  427                 if (flags & FUTEX_CREATE_WP)
  428                         free(*wp, M_FUTEX_WP);
  429 
  430                 LIN_SDT_PROBE1(futex, futex_get, return, error);
  431                 return (error);
  432         }
  433         if (flags & FUTEX_CREATE_WP) {
  434                 TAILQ_INSERT_HEAD(&(*f)->f_waiting_proc, *wp, wp_list);
  435                 (*wp)->wp_futex = *f;
  436         }
  437 
  438         LIN_SDT_PROBE1(futex, futex_get, return, error);
  439         return (error);
  440 }
  441 
  442 static int
  443 futex_sleep(struct futex *f, struct waiting_proc *wp, int timeout)
  444 {
  445         int error;
  446 
  447         FUTEX_ASSERT_LOCKED(f);
  448         LIN_SDT_PROBE3(futex, futex_sleep, entry, f, wp, timeout);
  449         LINUX_CTR4(sys_futex, "futex_sleep enter uaddr %p wp %p timo %d ref %d",
  450             f->f_uaddr, wp, timeout, f->f_refcount);
  451         error = sx_sleep(wp, &f->f_lck, PCATCH, "futex", timeout);
  452         if (wp->wp_flags & FUTEX_WP_REQUEUED) {
  453                 KASSERT(f != wp->wp_futex, ("futex != wp_futex"));
  454 
  455                 if (error) {
  456                         LIN_SDT_PROBE5(futex, futex_sleep, requeue_error, error,
  457                             f->f_uaddr, wp, wp->wp_futex->f_uaddr,
  458                             wp->wp_futex->f_refcount);
  459                 }
  460 
  461                 LINUX_CTR5(sys_futex, "futex_sleep out error %d uaddr %p wp"
  462                     " %p requeued uaddr %p ref %d",
  463                     error, f->f_uaddr, wp, wp->wp_futex->f_uaddr,
  464                     wp->wp_futex->f_refcount);
  465                 futex_put(f, NULL);
  466                 f = wp->wp_futex;
  467                 FUTEX_LOCK(f);
  468         } else {
  469                 if (error) {
  470                         LIN_SDT_PROBE3(futex, futex_sleep, sleep_error, error,
  471                             f->f_uaddr, wp);
  472                 }
  473                 LINUX_CTR3(sys_futex, "futex_sleep out error %d uaddr %p wp %p",
  474                     error, f->f_uaddr, wp);
  475         }
  476 
  477         futex_put(f, wp);
  478 
  479         LIN_SDT_PROBE1(futex, futex_sleep, return, error);
  480         return (error);
  481 }
  482 
  483 static int
  484 futex_wake(struct futex *f, int n, uint32_t bitset)
  485 {
  486         struct waiting_proc *wp, *wpt;
  487         int count = 0;
  488 
  489         LIN_SDT_PROBE3(futex, futex_wake, entry, f, n, bitset);
  490 
  491         if (bitset == 0) {
  492                 LIN_SDT_PROBE1(futex, futex_wake, return, EINVAL);
  493                 return (EINVAL);
  494         }
  495 
  496         FUTEX_ASSERT_LOCKED(f);
  497         TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) {
  498                 LIN_SDT_PROBE3(futex, futex_wake, iterate, f->f_uaddr, wp,
  499                     f->f_refcount);
  500                 LINUX_CTR3(sys_futex, "futex_wake uaddr %p wp %p ref %d",
  501                     f->f_uaddr, wp, f->f_refcount);
  502                 /*
  503                  * Unless we find a matching bit in
  504                  * the bitset, continue searching.
  505                  */
  506                 if (!(wp->wp_futex->f_bitset & bitset))
  507                         continue;
  508 
  509                 wp->wp_flags |= FUTEX_WP_REMOVED;
  510                 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
  511                 LIN_SDT_PROBE1(futex, futex_wake, wakeup, wp);
  512                 wakeup_one(wp);
  513                 if (++count == n)
  514                         break;
  515         }
  516 
  517         LIN_SDT_PROBE1(futex, futex_wake, return, count);
  518         return (count);
  519 }
  520 
  521 static int
  522 futex_requeue(struct futex *f, int n, struct futex *f2, int n2)
  523 {
  524         struct waiting_proc *wp, *wpt;
  525         int count = 0;
  526 
  527         LIN_SDT_PROBE4(futex, futex_requeue, entry, f, n, f2, n2);
  528 
  529         FUTEX_ASSERT_LOCKED(f);
  530         FUTEX_ASSERT_LOCKED(f2);
  531 
  532         TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) {
  533                 if (++count <= n) {
  534                         LINUX_CTR2(sys_futex, "futex_req_wake uaddr %p wp %p",
  535                             f->f_uaddr, wp);
  536                         wp->wp_flags |= FUTEX_WP_REMOVED;
  537                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
  538                         LIN_SDT_PROBE1(futex, futex_requeue, wakeup, wp);
  539                         wakeup_one(wp);
  540                 } else {
  541                         LIN_SDT_PROBE3(futex, futex_requeue, requeue,
  542                             f->f_uaddr, wp, f2->f_uaddr);
  543                         LINUX_CTR3(sys_futex, "futex_requeue uaddr %p wp %p to %p",
  544                             f->f_uaddr, wp, f2->f_uaddr);
  545                         wp->wp_flags |= FUTEX_WP_REQUEUED;
  546                         /* Move wp to wp_list of f2 futex */
  547                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
  548                         TAILQ_INSERT_HEAD(&f2->f_waiting_proc, wp, wp_list);
  549 
  550                         /*
  551                          * Thread which sleeps on wp after waking should
  552                          * acquire f2 lock, so increment refcount of f2 to
  553                          * prevent it from premature deallocation.
  554                          */
  555                         wp->wp_futex = f2;
  556                         FUTEXES_LOCK;
  557                         ++f2->f_refcount;
  558                         FUTEXES_UNLOCK;
  559                         if (count - n >= n2)
  560                                 break;
  561                 }
  562         }
  563 
  564         LIN_SDT_PROBE1(futex, futex_requeue, return, count);
  565         return (count);
  566 }
  567 
  568 static int
  569 futex_wait(struct futex *f, struct waiting_proc *wp, int timeout_hz,
  570     uint32_t bitset)
  571 {
  572         int error;
  573 
  574         LIN_SDT_PROBE4(futex, futex_wait, entry, f, wp, timeout_hz, bitset);
  575 
  576         if (bitset == 0) {
  577                 LIN_SDT_PROBE1(futex, futex_wait, return, EINVAL);
  578                 return (EINVAL);
  579         }
  580 
  581         f->f_bitset = bitset;
  582         error = futex_sleep(f, wp, timeout_hz);
  583         if (error)
  584                 LIN_SDT_PROBE1(futex, futex_wait, sleep_error, error);
  585         if (error == EWOULDBLOCK)
  586                 error = ETIMEDOUT;
  587 
  588         LIN_SDT_PROBE1(futex, futex_wait, return, error);
  589         return (error);
  590 }
  591 
  592 static int
  593 futex_atomic_op(struct thread *td, int encoded_op, uint32_t *uaddr)
  594 {
  595         int op = (encoded_op >> 28) & 7;
  596         int cmp = (encoded_op >> 24) & 15;
  597         int oparg = (encoded_op << 8) >> 20;
  598         int cmparg = (encoded_op << 20) >> 20;
  599         int oldval = 0, ret;
  600 
  601         LIN_SDT_PROBE3(futex, futex_atomic_op, entry, td, encoded_op, uaddr);
  602 
  603         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
  604                 oparg = 1 << oparg;
  605 
  606         LIN_SDT_PROBE4(futex, futex_atomic_op, decoded_op, op, cmp, oparg,
  607             cmparg);
  608         
  609         /* XXX: Linux verifies access here and returns EFAULT */
  610         LIN_SDT_PROBE0(futex, futex_atomic_op, missing_access_check);
  611 
  612         switch (op) {
  613         case FUTEX_OP_SET:
  614                 ret = futex_xchgl(oparg, uaddr, &oldval);
  615                 break;
  616         case FUTEX_OP_ADD:
  617                 ret = futex_addl(oparg, uaddr, &oldval);
  618                 break;
  619         case FUTEX_OP_OR:
  620                 ret = futex_orl(oparg, uaddr, &oldval);
  621                 break;
  622         case FUTEX_OP_ANDN:
  623                 ret = futex_andl(~oparg, uaddr, &oldval);
  624                 break;
  625         case FUTEX_OP_XOR:
  626                 ret = futex_xorl(oparg, uaddr, &oldval);
  627                 break;
  628         default:
  629                 LIN_SDT_PROBE1(futex, futex_atomic_op, unimplemented_op, op);
  630                 ret = -ENOSYS;
  631                 break;
  632         }
  633 
  634         if (ret) {
  635                 LIN_SDT_PROBE1(futex, futex_atomic_op, return, ret);
  636                 return (ret);
  637         }
  638 
  639         switch (cmp) {
  640         case FUTEX_OP_CMP_EQ:
  641                 ret = (oldval == cmparg);
  642                 break;
  643         case FUTEX_OP_CMP_NE:
  644                 ret = (oldval != cmparg);
  645                 break;
  646         case FUTEX_OP_CMP_LT:
  647                 ret = (oldval < cmparg);
  648                 break;
  649         case FUTEX_OP_CMP_GE:
  650                 ret = (oldval >= cmparg);
  651                 break;
  652         case FUTEX_OP_CMP_LE:
  653                 ret = (oldval <= cmparg);
  654                 break;
  655         case FUTEX_OP_CMP_GT:
  656                 ret = (oldval > cmparg);
  657                 break;
  658         default:
  659                 LIN_SDT_PROBE1(futex, futex_atomic_op, unimplemented_cmp, cmp);
  660                 ret = -ENOSYS;
  661         }
  662 
  663         LIN_SDT_PROBE1(futex, futex_atomic_op, return, ret);
  664         return (ret);
  665 }
  666 
  667 int
  668 linux_sys_futex(struct thread *td, struct linux_sys_futex_args *args)
  669 {
  670         int clockrt, nrwake, op_ret, ret;
  671         struct linux_pemuldata *pem;
  672         struct waiting_proc *wp;
  673         struct futex *f, *f2;
  674         struct l_timespec ltimeout;
  675         struct timespec timeout;
  676         struct timeval utv, ctv;
  677         int timeout_hz;
  678         int error;
  679         uint32_t flags, val;
  680 
  681         LIN_SDT_PROBE2(futex, linux_sys_futex, entry, td, args);
  682 
  683         if (args->op & LINUX_FUTEX_PRIVATE_FLAG) {
  684                 flags = 0;
  685                 args->op &= ~LINUX_FUTEX_PRIVATE_FLAG;
  686         } else
  687                 flags = FUTEX_SHARED;
  688 
  689         /*
  690          * Currently support for switching between CLOCK_MONOTONIC and
  691          * CLOCK_REALTIME is not present. However Linux forbids the use of
  692          * FUTEX_CLOCK_REALTIME with any op except FUTEX_WAIT_BITSET and
  693          * FUTEX_WAIT_REQUEUE_PI.
  694          */
  695         clockrt = args->op & LINUX_FUTEX_CLOCK_REALTIME;
  696         args->op = args->op & ~LINUX_FUTEX_CLOCK_REALTIME;
  697         if (clockrt && args->op != LINUX_FUTEX_WAIT_BITSET &&
  698                 args->op != LINUX_FUTEX_WAIT_REQUEUE_PI) {
  699                 LIN_SDT_PROBE0(futex, linux_sys_futex,
  700                     unimplemented_clockswitch);
  701                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
  702                 return (ENOSYS);
  703         }
  704 
  705         error = 0;
  706         f = f2 = NULL;
  707 
  708         switch (args->op) {
  709         case LINUX_FUTEX_WAIT:
  710                 args->val3 = FUTEX_BITSET_MATCH_ANY;
  711                 /* FALLTHROUGH */
  712 
  713         case LINUX_FUTEX_WAIT_BITSET:
  714                 LIN_SDT_PROBE3(futex, linux_sys_futex, debug_wait, args->uaddr,
  715                     args->val, args->val3);
  716                 LINUX_CTR3(sys_futex, "WAIT uaddr %p val 0x%x bitset 0x%x",
  717                     args->uaddr, args->val, args->val3);
  718 
  719                 if (args->timeout != NULL) {
  720                         error = copyin(args->timeout, &ltimeout, sizeof(ltimeout));
  721                         if (error) {
  722                                 LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error,
  723                                     error);
  724                                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  725                                 return (error);
  726                         }
  727                         error = linux_to_native_timespec(&timeout, &ltimeout);
  728                         if (error)
  729                                 return (error);
  730                         TIMESPEC_TO_TIMEVAL(&utv, &timeout);
  731                         error = itimerfix(&utv);
  732                         if (error) {
  733                                 LIN_SDT_PROBE1(futex, linux_sys_futex, itimerfix_error,
  734                                     error);
  735                                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  736                                 return (error);
  737                         }
  738                         if (clockrt) {
  739                                 microtime(&ctv);
  740                                 timevalsub(&utv, &ctv);
  741                         } else if (args->op == LINUX_FUTEX_WAIT_BITSET) {
  742                                 microuptime(&ctv);
  743                                 timevalsub(&utv, &ctv);
  744                         }
  745                         if (utv.tv_sec < 0)
  746                                 timevalclear(&utv);
  747                         timeout_hz = tvtohz(&utv);
  748                 } else
  749                         timeout_hz = 0;
  750 
  751                 error = futex_get(args->uaddr, &wp, &f,
  752                     flags | FUTEX_CREATE_WP);
  753                 if (error) {
  754                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  755                         return (error);
  756                 }
  757 
  758                 error = copyin(args->uaddr, &val, sizeof(val));
  759                 if (error) {
  760                         LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error,
  761                             error);
  762                         LINUX_CTR1(sys_futex, "WAIT copyin failed %d",
  763                             error);
  764                         futex_put(f, wp);
  765 
  766                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  767                         return (error);
  768                 }
  769                 if (val != args->val) {
  770                         LIN_SDT_PROBE4(futex, linux_sys_futex,
  771                             debug_wait_value_neq, args->uaddr, args->val, val,
  772                             args->val3);
  773                         LINUX_CTR3(sys_futex,
  774                             "WAIT uaddr %p val 0x%x != uval 0x%x",
  775                             args->uaddr, args->val, val);
  776                         futex_put(f, wp);
  777 
  778                         LIN_SDT_PROBE1(futex, linux_sys_futex, return,
  779                             EWOULDBLOCK);
  780                         return (EWOULDBLOCK);
  781                 }
  782 
  783                 error = futex_wait(f, wp, timeout_hz, args->val3);
  784                 break;
  785 
  786         case LINUX_FUTEX_WAKE:
  787                 args->val3 = FUTEX_BITSET_MATCH_ANY;
  788                 /* FALLTHROUGH */
  789 
  790         case LINUX_FUTEX_WAKE_BITSET:
  791                 LIN_SDT_PROBE3(futex, linux_sys_futex, debug_wake, args->uaddr,
  792                     args->val, args->val3);
  793                 LINUX_CTR3(sys_futex, "WAKE uaddr %p nrwake 0x%x bitset 0x%x",
  794                     args->uaddr, args->val, args->val3);
  795 
  796                 error = futex_get(args->uaddr, NULL, &f,
  797                     flags | FUTEX_DONTCREATE);
  798                 if (error) {
  799                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  800                         return (error);
  801                 }
  802 
  803                 if (f == NULL) {
  804                         td->td_retval[0] = 0;
  805 
  806                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  807                         return (error);
  808                 }
  809                 td->td_retval[0] = futex_wake(f, args->val, args->val3);
  810                 futex_put(f, NULL);
  811                 break;
  812 
  813         case LINUX_FUTEX_CMP_REQUEUE:
  814                 LIN_SDT_PROBE5(futex, linux_sys_futex, debug_cmp_requeue,
  815                     args->uaddr, args->val, args->val3, args->uaddr2,
  816                     args->timeout);
  817                 LINUX_CTR5(sys_futex, "CMP_REQUEUE uaddr %p "
  818                     "nrwake 0x%x uval 0x%x uaddr2 %p nrequeue 0x%x",
  819                     args->uaddr, args->val, args->val3, args->uaddr2,
  820                     args->timeout);
  821 
  822                 /*
  823                  * Linux allows this, we would not, it is an incorrect
  824                  * usage of declared ABI, so return EINVAL.
  825                  */
  826                 if (args->uaddr == args->uaddr2) {
  827                         LIN_SDT_PROBE0(futex, linux_sys_futex,
  828                             invalid_cmp_requeue_use);
  829                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, EINVAL);
  830                         return (EINVAL);
  831                 }
  832 
  833                 error = futex_get(args->uaddr, NULL, &f, flags);
  834                 if (error) {
  835                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  836                         return (error);
  837                 }
  838 
  839                 /*
  840                  * To avoid deadlocks return EINVAL if second futex
  841                  * exists at this time.
  842                  *
  843                  * Glibc fall back to FUTEX_WAKE in case of any error
  844                  * returned by FUTEX_CMP_REQUEUE.
  845                  */
  846                 error = futex_get(args->uaddr2, NULL, &f2,
  847                     flags | FUTEX_DONTEXISTS);
  848                 if (error) {
  849                         futex_put(f, NULL);
  850 
  851                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  852                         return (error);
  853                 }
  854                 error = copyin(args->uaddr, &val, sizeof(val));
  855                 if (error) {
  856                         LIN_SDT_PROBE1(futex, linux_sys_futex, copyin_error,
  857                             error);
  858                         LINUX_CTR1(sys_futex, "CMP_REQUEUE copyin failed %d",
  859                             error);
  860                         futex_put(f2, NULL);
  861                         futex_put(f, NULL);
  862 
  863                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  864                         return (error);
  865                 }
  866                 if (val != args->val3) {
  867                         LIN_SDT_PROBE2(futex, linux_sys_futex,
  868                             debug_cmp_requeue_value_neq, args->val, val);
  869                         LINUX_CTR2(sys_futex, "CMP_REQUEUE val 0x%x != uval 0x%x",
  870                             args->val, val);
  871                         futex_put(f2, NULL);
  872                         futex_put(f, NULL);
  873 
  874                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, EAGAIN);
  875                         return (EAGAIN);
  876                 }
  877 
  878                 nrwake = (int)(unsigned long)args->timeout;
  879                 td->td_retval[0] = futex_requeue(f, args->val, f2, nrwake);
  880                 futex_put(f2, NULL);
  881                 futex_put(f, NULL);
  882                 break;
  883 
  884         case LINUX_FUTEX_WAKE_OP:
  885                 LIN_SDT_PROBE5(futex, linux_sys_futex, debug_wake_op,
  886                     args->uaddr, args->op, args->val, args->uaddr2, args->val3);
  887                 LINUX_CTR5(sys_futex, "WAKE_OP "
  888                     "uaddr %p nrwake 0x%x uaddr2 %p op 0x%x nrwake2 0x%x",
  889                     args->uaddr, args->val, args->uaddr2, args->val3,
  890                     args->timeout);
  891 
  892                 error = futex_get(args->uaddr, NULL, &f, flags);
  893                 if (error) {
  894                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  895                         return (error);
  896                 }
  897 
  898                 if (args->uaddr != args->uaddr2)
  899                         error = futex_get(args->uaddr2, NULL, &f2, flags);
  900                 if (error) {
  901                         futex_put(f, NULL);
  902 
  903                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
  904                         return (error);
  905                 }
  906 
  907                 /*
  908                  * This function returns positive number as results and
  909                  * negative as errors
  910                  */
  911                 op_ret = futex_atomic_op(td, args->val3, args->uaddr2);
  912 
  913                 LINUX_CTR2(sys_futex, "WAKE_OP atomic_op uaddr %p ret 0x%x",
  914                     args->uaddr, op_ret);
  915 
  916                 if (op_ret < 0) {
  917                         /* XXX: We don't handle the EFAULT yet. */
  918                         if (op_ret != -EFAULT) {
  919                                 if (f2 != NULL)
  920                                         futex_put(f2, NULL);
  921                                 futex_put(f, NULL);
  922 
  923                                 LIN_SDT_PROBE1(futex, linux_sys_futex, return,
  924                                     -op_ret);
  925                                 return (-op_ret);
  926                         } else {
  927                                 LIN_SDT_PROBE0(futex, linux_sys_futex,
  928                                     unhandled_efault);
  929                         }
  930                         if (f2 != NULL)
  931                                 futex_put(f2, NULL);
  932                         futex_put(f, NULL);
  933 
  934                         LIN_SDT_PROBE1(futex, linux_sys_futex, return, EFAULT);
  935                         return (EFAULT);
  936                 }
  937 
  938                 ret = futex_wake(f, args->val, args->val3);
  939 
  940                 if (op_ret > 0) {
  941                         op_ret = 0;
  942                         nrwake = (int)(unsigned long)args->timeout;
  943 
  944                         if (f2 != NULL)
  945                                 op_ret += futex_wake(f2, nrwake, args->val3);
  946                         else
  947                                 op_ret += futex_wake(f, nrwake, args->val3);
  948                         ret += op_ret;
  949 
  950                 }
  951                 if (f2 != NULL)
  952                         futex_put(f2, NULL);
  953                 futex_put(f, NULL);
  954                 td->td_retval[0] = ret;
  955                 break;
  956 
  957         case LINUX_FUTEX_LOCK_PI:
  958                 /* not yet implemented */
  959                 pem = pem_find(td->td_proc);
  960                 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
  961                         linux_msg(td,
  962                                   "linux_sys_futex: "
  963                                   "unsupported futex_pi op\n");
  964                         pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
  965                         LIN_SDT_PROBE0(futex, linux_sys_futex,
  966                             unimplemented_lock_pi);
  967                 }
  968                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
  969                 return (ENOSYS);
  970 
  971         case LINUX_FUTEX_UNLOCK_PI:
  972                 /* not yet implemented */
  973                 pem = pem_find(td->td_proc);
  974                 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
  975                         linux_msg(td,
  976                                   "linux_sys_futex: "
  977                                   "unsupported futex_pi op\n");
  978                         pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
  979                         LIN_SDT_PROBE0(futex, linux_sys_futex,
  980                             unimplemented_unlock_pi);
  981                 }
  982                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
  983                 return (ENOSYS);
  984 
  985         case LINUX_FUTEX_TRYLOCK_PI:
  986                 /* not yet implemented */
  987                 pem = pem_find(td->td_proc);
  988                 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
  989                         linux_msg(td,
  990                                   "linux_sys_futex: "
  991                                   "unsupported futex_pi op\n");
  992                         pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
  993                         LIN_SDT_PROBE0(futex, linux_sys_futex,
  994                             unimplemented_trylock_pi);
  995                 }
  996                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
  997                 return (ENOSYS);
  998 
  999         case LINUX_FUTEX_REQUEUE:
 1000 
 1001                 /*
 1002                  * Glibc does not use this operation since version 2.3.3,
 1003                  * as it is racy and replaced by FUTEX_CMP_REQUEUE operation.
 1004                  * Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when
 1005                  * FUTEX_REQUEUE returned EINVAL.
 1006                  */
 1007                 pem = pem_find(td->td_proc);
 1008                 if ((pem->flags & LINUX_XDEPR_REQUEUEOP) == 0) {
 1009                         linux_msg(td,
 1010                                   "linux_sys_futex: "
 1011                                   "unsupported futex_requeue op\n");
 1012                         pem->flags |= LINUX_XDEPR_REQUEUEOP;
 1013                         LIN_SDT_PROBE0(futex, linux_sys_futex,
 1014                             deprecated_requeue);
 1015                 }
 1016 
 1017                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, EINVAL);
 1018                 return (EINVAL);
 1019 
 1020         case LINUX_FUTEX_WAIT_REQUEUE_PI:
 1021                 /* not yet implemented */
 1022                 pem = pem_find(td->td_proc);
 1023                 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
 1024                         linux_msg(td,
 1025                                   "linux_sys_futex: "
 1026                                   "unsupported futex_pi op\n");
 1027                         pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
 1028                         LIN_SDT_PROBE0(futex, linux_sys_futex,
 1029                             unimplemented_wait_requeue_pi);
 1030                 }
 1031                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
 1032                 return (ENOSYS);
 1033 
 1034         case LINUX_FUTEX_CMP_REQUEUE_PI:
 1035                 /* not yet implemented */
 1036                 pem = pem_find(td->td_proc);
 1037                 if ((pem->flags & LINUX_XUNSUP_FUTEXPIOP) == 0) {
 1038                         linux_msg(td,
 1039                                   "linux_sys_futex: "
 1040                                   "unsupported futex_pi op\n");
 1041                         pem->flags |= LINUX_XUNSUP_FUTEXPIOP;
 1042                         LIN_SDT_PROBE0(futex, linux_sys_futex,
 1043                             unimplemented_cmp_requeue_pi);
 1044                 }
 1045                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
 1046                 return (ENOSYS);
 1047 
 1048         default:
 1049                 linux_msg(td,
 1050                           "linux_sys_futex: unknown op %d\n", args->op);
 1051                 LIN_SDT_PROBE1(futex, linux_sys_futex, unknown_operation,
 1052                     args->op);
 1053                 LIN_SDT_PROBE1(futex, linux_sys_futex, return, ENOSYS);
 1054                 return (ENOSYS);
 1055         }
 1056 
 1057         LIN_SDT_PROBE1(futex, linux_sys_futex, return, error);
 1058         return (error);
 1059 }
 1060 
 1061 int
 1062 linux_set_robust_list(struct thread *td, struct linux_set_robust_list_args *args)
 1063 {
 1064         struct linux_emuldata *em;
 1065 
 1066         LIN_SDT_PROBE2(futex, linux_set_robust_list, entry, td, args);
 1067 
 1068         if (args->len != sizeof(struct linux_robust_list_head)) {
 1069                 LIN_SDT_PROBE0(futex, linux_set_robust_list, size_error);
 1070                 LIN_SDT_PROBE1(futex, linux_set_robust_list, return, EINVAL);
 1071                 return (EINVAL);
 1072         }
 1073 
 1074         em = em_find(td);
 1075         em->robust_futexes = args->head;
 1076 
 1077         LIN_SDT_PROBE1(futex, linux_set_robust_list, return, 0);
 1078         return (0);
 1079 }
 1080 
 1081 int
 1082 linux_get_robust_list(struct thread *td, struct linux_get_robust_list_args *args)
 1083 {
 1084         struct linux_emuldata *em;
 1085         struct linux_robust_list_head *head;
 1086         l_size_t len = sizeof(struct linux_robust_list_head);
 1087         struct thread *td2;
 1088         int error = 0;
 1089 
 1090         LIN_SDT_PROBE2(futex, linux_get_robust_list, entry, td, args);
 1091 
 1092         if (!args->pid) {
 1093                 em = em_find(td);
 1094                 KASSERT(em != NULL, ("get_robust_list: emuldata notfound.\n"));
 1095                 head = em->robust_futexes;
 1096         } else {
 1097                 td2 = tdfind(args->pid, -1);
 1098                 if (td2 == NULL) {
 1099                         LIN_SDT_PROBE1(futex, linux_get_robust_list, return,
 1100                             ESRCH);
 1101                         return (ESRCH);
 1102                 }
 1103                 if (SV_PROC_ABI(td2->td_proc) != SV_ABI_LINUX) {
 1104                         LIN_SDT_PROBE1(futex, linux_get_robust_list, return,
 1105                             EPERM);
 1106                         PROC_UNLOCK(td2->td_proc);
 1107                         return (EPERM);
 1108                 }
 1109 
 1110                 em = em_find(td2);
 1111                 KASSERT(em != NULL, ("get_robust_list: emuldata notfound.\n"));
 1112                 /* XXX: ptrace? */
 1113                 if (priv_check(td, PRIV_CRED_SETUID) ||
 1114                     priv_check(td, PRIV_CRED_SETEUID) ||
 1115                     p_candebug(td, td2->td_proc)) {
 1116                         PROC_UNLOCK(td2->td_proc);
 1117 
 1118                         LIN_SDT_PROBE1(futex, linux_get_robust_list, return,
 1119                             EPERM);
 1120                         return (EPERM);
 1121                 }
 1122                 head = em->robust_futexes;
 1123 
 1124                 PROC_UNLOCK(td2->td_proc);
 1125         }
 1126 
 1127         error = copyout(&len, args->len, sizeof(l_size_t));
 1128         if (error) {
 1129                 LIN_SDT_PROBE1(futex, linux_get_robust_list, copyout_error,
 1130                     error);
 1131                 LIN_SDT_PROBE1(futex, linux_get_robust_list, return, EFAULT);
 1132                 return (EFAULT);
 1133         }
 1134 
 1135         error = copyout(&head, args->head, sizeof(head));
 1136         if (error) {
 1137                 LIN_SDT_PROBE1(futex, linux_get_robust_list, copyout_error,
 1138                     error);
 1139         }
 1140 
 1141         LIN_SDT_PROBE1(futex, linux_get_robust_list, return, error);
 1142         return (error);
 1143 }
 1144 
 1145 static int
 1146 handle_futex_death(struct linux_emuldata *em, uint32_t *uaddr,
 1147     unsigned int pi)
 1148 {
 1149         uint32_t uval, nval, mval;
 1150         struct futex *f;
 1151         int error;
 1152 
 1153         LIN_SDT_PROBE3(futex, handle_futex_death, entry, em, uaddr, pi);
 1154 
 1155 retry:
 1156         error = copyin(uaddr, &uval, 4);
 1157         if (error) {
 1158                 LIN_SDT_PROBE1(futex, handle_futex_death, copyin_error, error);
 1159                 LIN_SDT_PROBE1(futex, handle_futex_death, return, EFAULT);
 1160                 return (EFAULT);
 1161         }
 1162         if ((uval & FUTEX_TID_MASK) == em->em_tid) {
 1163                 mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED;
 1164                 nval = casuword32(uaddr, uval, mval);
 1165 
 1166                 if (nval == -1) {
 1167                         LIN_SDT_PROBE1(futex, handle_futex_death, return,
 1168                             EFAULT);
 1169                         return (EFAULT);
 1170                 }
 1171 
 1172                 if (nval != uval)
 1173                         goto retry;
 1174 
 1175                 if (!pi && (uval & FUTEX_WAITERS)) {
 1176                         error = futex_get(uaddr, NULL, &f,
 1177                             FUTEX_DONTCREATE | FUTEX_SHARED);
 1178                         if (error) {
 1179                                 LIN_SDT_PROBE1(futex, handle_futex_death,
 1180                                     return, error);
 1181                                 return (error);
 1182                         }
 1183                         if (f != NULL) {
 1184                                 futex_wake(f, 1, FUTEX_BITSET_MATCH_ANY);
 1185                                 futex_put(f, NULL);
 1186                         }
 1187                 }
 1188         }
 1189 
 1190         LIN_SDT_PROBE1(futex, handle_futex_death, return, 0);
 1191         return (0);
 1192 }
 1193 
 1194 static int
 1195 fetch_robust_entry(struct linux_robust_list **entry,
 1196     struct linux_robust_list **head, unsigned int *pi)
 1197 {
 1198         l_ulong uentry;
 1199         int error;
 1200 
 1201         LIN_SDT_PROBE3(futex, fetch_robust_entry, entry, entry, head, pi);
 1202 
 1203         error = copyin((const void *)head, &uentry, sizeof(l_ulong));
 1204         if (error) {
 1205                 LIN_SDT_PROBE1(futex, fetch_robust_entry, copyin_error, error);
 1206                 LIN_SDT_PROBE1(futex, fetch_robust_entry, return, EFAULT);
 1207                 return (EFAULT);
 1208         }
 1209 
 1210         *entry = (void *)(uentry & ~1UL);
 1211         *pi = uentry & 1;
 1212 
 1213         LIN_SDT_PROBE1(futex, fetch_robust_entry, return, 0);
 1214         return (0);
 1215 }
 1216 
 1217 /* This walks the list of robust futexes releasing them. */
 1218 void
 1219 release_futexes(struct thread *td, struct linux_emuldata *em)
 1220 {
 1221         struct linux_robust_list_head *head = NULL;
 1222         struct linux_robust_list *entry, *next_entry, *pending;
 1223         unsigned int limit = 2048, pi, next_pi, pip;
 1224         l_long futex_offset;
 1225         int rc, error;
 1226 
 1227         LIN_SDT_PROBE2(futex, release_futexes, entry, td, em);
 1228 
 1229         head = em->robust_futexes;
 1230 
 1231         if (head == NULL) {
 1232                 LIN_SDT_PROBE0(futex, release_futexes, return);
 1233                 return;
 1234         }
 1235 
 1236         if (fetch_robust_entry(&entry, PTRIN(&head->list.next), &pi)) {
 1237                 LIN_SDT_PROBE0(futex, release_futexes, return);
 1238                 return;
 1239         }
 1240 
 1241         error = copyin(&head->futex_offset, &futex_offset,
 1242             sizeof(futex_offset));
 1243         if (error) {
 1244                 LIN_SDT_PROBE1(futex, release_futexes, copyin_error, error);
 1245                 LIN_SDT_PROBE0(futex, release_futexes, return);
 1246                 return;
 1247         }
 1248 
 1249         if (fetch_robust_entry(&pending, PTRIN(&head->pending_list), &pip)) {
 1250                 LIN_SDT_PROBE0(futex, release_futexes, return);
 1251                 return;
 1252         }
 1253 
 1254         while (entry != &head->list) {
 1255                 rc = fetch_robust_entry(&next_entry, PTRIN(&entry->next), &next_pi);
 1256 
 1257                 if (entry != pending)
 1258                         if (handle_futex_death(em,
 1259                             (uint32_t *)((caddr_t)entry + futex_offset), pi)) {
 1260                                 LIN_SDT_PROBE0(futex, release_futexes, return);
 1261                                 return;
 1262                         }
 1263                 if (rc) {
 1264                         LIN_SDT_PROBE0(futex, release_futexes, return);
 1265                         return;
 1266                 }
 1267 
 1268                 entry = next_entry;
 1269                 pi = next_pi;
 1270 
 1271                 if (!--limit)
 1272                         break;
 1273 
 1274                 sched_relinquish(curthread);
 1275         }
 1276 
 1277         if (pending)
 1278                 handle_futex_death(em, (uint32_t *)((caddr_t)pending + futex_offset), pip);
 1279 
 1280         LIN_SDT_PROBE0(futex, release_futexes, return);
 1281 }

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