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/7.4/sys/compat/linux/linux_futex.c 194375 2009-06-17 16:56:21Z dchagin $");
   36 #if 0
   37 __KERNEL_RCSID(1, "$NetBSD: linux_futex.c,v 1.7 2006/07/24 19:01:49 manu Exp $");
   38 #endif
   39 
   40 #include "opt_compat.h"
   41 
   42 #include <sys/param.h>
   43 #include <sys/systm.h>
   44 #include <sys/imgact.h>
   45 #include <sys/kernel.h>
   46 #include <sys/ktr.h>
   47 #include <sys/lock.h>
   48 #include <sys/malloc.h>
   49 #include <sys/mutex.h>
   50 #include <sys/priv.h>
   51 #include <sys/proc.h>
   52 #include <sys/queue.h>
   53 #include <sys/sched.h>
   54 #include <sys/sx.h>
   55 
   56 #ifdef COMPAT_LINUX32
   57 #include <machine/../linux32/linux.h>
   58 #include <machine/../linux32/linux32_proto.h>
   59 #else
   60 #include <machine/../linux/linux.h>
   61 #include <machine/../linux/linux_proto.h>
   62 #endif
   63 #include <compat/linux/linux_futex.h>
   64 #include <compat/linux/linux_emul.h>
   65 #include <compat/linux/linux_util.h>
   66 
   67 MALLOC_DEFINE(M_FUTEX, "futex", "Linux futexes");
   68 MALLOC_DEFINE(M_FUTEX_WP, "futex wp", "Linux futexes wp");
   69 
   70 struct futex;
   71 
   72 struct waiting_proc {
   73         uint32_t        wp_flags;
   74         struct futex    *wp_futex;
   75         TAILQ_ENTRY(waiting_proc) wp_list;
   76 };
   77 
   78 struct futex {
   79         struct sx       f_lck;
   80         uint32_t        *f_uaddr;
   81         uint32_t        f_refcount;
   82         LIST_ENTRY(futex) f_list;
   83         TAILQ_HEAD(lf_waiting_proc, waiting_proc) f_waiting_proc;
   84 };
   85 
   86 struct futex_list futex_list;
   87 
   88 #define FUTEX_LOCK(f)           sx_xlock(&(f)->f_lck)
   89 #define FUTEX_UNLOCK(f)         sx_xunlock(&(f)->f_lck)
   90 #define FUTEX_INIT(f)           sx_init_flags(&(f)->f_lck, "ftlk", 0)
   91 #define FUTEX_DESTROY(f)        sx_destroy(&(f)->f_lck)
   92 #define FUTEX_ASSERT_LOCKED(f)  sx_assert(&(f)->f_lck, SA_XLOCKED)
   93 
   94 struct mtx futex_mtx;                   /* protects the futex list */
   95 #define FUTEXES_LOCK            mtx_lock(&futex_mtx)
   96 #define FUTEXES_UNLOCK          mtx_unlock(&futex_mtx)
   97 
   98 /* flags for futex_get() */
   99 #define FUTEX_CREATE_WP         0x1     /* create waiting_proc */
  100 #define FUTEX_DONTCREATE        0x2     /* don't create futex if not exists */
  101 #define FUTEX_DONTEXISTS        0x4     /* return EINVAL if futex exists */
  102 
  103 /* wp_flags */
  104 #define FUTEX_WP_REQUEUED       0x1     /* wp requeued - wp moved from wp_list
  105                                          * of futex where thread sleep to wp_list
  106                                          * of another futex.
  107                                          */
  108 #define FUTEX_WP_REMOVED        0x2     /* wp is woken up and removed from futex
  109                                          * wp_list to prevent double wakeup.
  110                                          */
  111 
  112 /* support.s */
  113 int futex_xchgl(int oparg, uint32_t *uaddr, int *oldval);
  114 int futex_addl(int oparg, uint32_t *uaddr, int *oldval);
  115 int futex_orl(int oparg, uint32_t *uaddr, int *oldval);
  116 int futex_andl(int oparg, uint32_t *uaddr, int *oldval);
  117 int futex_xorl(int oparg, uint32_t *uaddr, int *oldval);
  118 
  119 static void
  120 futex_put(struct futex *f, struct waiting_proc *wp)
  121 {
  122 
  123         FUTEX_ASSERT_LOCKED(f);
  124         if (wp != NULL) {
  125                 if ((wp->wp_flags & FUTEX_WP_REMOVED) == 0)
  126                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
  127                 free(wp, M_FUTEX_WP);
  128         }
  129 
  130         FUTEXES_LOCK;
  131         if (--f->f_refcount == 0) {
  132                 LIST_REMOVE(f, f_list);
  133                 FUTEXES_UNLOCK;
  134                 FUTEX_UNLOCK(f);
  135 
  136                 LINUX_CTR2(sys_futex, "futex_put destroy uaddr %p ref %d",
  137                     f->f_uaddr, f->f_refcount);
  138                 FUTEX_DESTROY(f);
  139                 free(f, M_FUTEX);
  140                 return;
  141         }
  142 
  143         LINUX_CTR2(sys_futex, "futex_put uaddr %p ref %d",
  144             f->f_uaddr, f->f_refcount);
  145         FUTEXES_UNLOCK;
  146         FUTEX_UNLOCK(f);
  147 }
  148 
  149 static int
  150 futex_get0(uint32_t *uaddr, struct futex **newf, uint32_t flags)
  151 {
  152         struct futex *f, *tmpf;
  153 
  154         *newf = tmpf = NULL;
  155 
  156 retry:
  157         FUTEXES_LOCK;
  158         LIST_FOREACH(f, &futex_list, f_list) {
  159                 if (f->f_uaddr == uaddr) {
  160                         if (tmpf != NULL) {
  161                                 FUTEX_UNLOCK(tmpf);
  162                                 FUTEX_DESTROY(tmpf);
  163                                 free(tmpf, M_FUTEX);
  164                         }
  165                         if (flags & FUTEX_DONTEXISTS) {
  166                                 FUTEXES_UNLOCK;
  167                                 return (EINVAL);
  168                         }
  169 
  170                         /*
  171                          * Increment refcount of the found futex to
  172                          * prevent it from deallocation before FUTEX_LOCK()
  173                          */
  174                         ++f->f_refcount;
  175                         FUTEXES_UNLOCK;
  176 
  177                         FUTEX_LOCK(f);
  178                         *newf = f;
  179                         LINUX_CTR2(sys_futex, "futex_get uaddr %p ref %d",
  180                             uaddr, f->f_refcount);
  181                         return (0);
  182                 }
  183         }
  184 
  185         if (flags & FUTEX_DONTCREATE) {
  186                 FUTEXES_UNLOCK;
  187                 LINUX_CTR1(sys_futex, "futex_get uaddr %p null", uaddr);
  188                 return (0);
  189         }
  190 
  191         if (tmpf == NULL) {
  192                 FUTEXES_UNLOCK;
  193                 tmpf = malloc(sizeof(*tmpf), M_FUTEX, M_WAITOK | M_ZERO);
  194                 tmpf->f_uaddr = uaddr;
  195                 tmpf->f_refcount = 1;
  196                 FUTEX_INIT(tmpf);
  197                 TAILQ_INIT(&tmpf->f_waiting_proc);
  198 
  199                 /*
  200                  * Lock the new futex before an insert into the futex_list
  201                  * to prevent futex usage by other.
  202                  */
  203                 FUTEX_LOCK(tmpf);
  204                 goto retry;
  205         }
  206 
  207         LIST_INSERT_HEAD(&futex_list, tmpf, f_list);
  208         FUTEXES_UNLOCK;
  209 
  210         LINUX_CTR2(sys_futex, "futex_get uaddr %p ref %d new",
  211             uaddr, tmpf->f_refcount);
  212         *newf = tmpf;
  213         return (0);
  214 }
  215 
  216 static int
  217 futex_get(uint32_t *uaddr, struct waiting_proc **wp, struct futex **f,
  218     uint32_t flags)
  219 {
  220         int error;
  221 
  222         if (flags & FUTEX_CREATE_WP) {
  223                 *wp = malloc(sizeof(struct waiting_proc), M_FUTEX_WP, M_WAITOK);
  224                 (*wp)->wp_flags = 0;
  225         }
  226         error = futex_get0(uaddr, f, flags);
  227         if (error) {
  228                 if (flags & FUTEX_CREATE_WP)
  229                         free(*wp, M_FUTEX_WP);
  230                 return (error);
  231         }
  232         if (flags & FUTEX_CREATE_WP) {
  233                 TAILQ_INSERT_HEAD(&(*f)->f_waiting_proc, *wp, wp_list);
  234                 (*wp)->wp_futex = *f;
  235         }
  236 
  237         return (error);
  238 }
  239 
  240 static int
  241 futex_sleep(struct futex *f, struct waiting_proc *wp, unsigned long timeout)
  242 {
  243         int error;
  244 
  245         FUTEX_ASSERT_LOCKED(f);
  246         LINUX_CTR4(sys_futex, "futex_sleep enter uaddr %p wp %p timo %ld ref %d",
  247             f->f_uaddr, wp, timeout, f->f_refcount);
  248         error = sx_sleep(wp, &f->f_lck, PCATCH, "futex", timeout);
  249         if (wp->wp_flags & FUTEX_WP_REQUEUED) {
  250                 KASSERT(f != wp->wp_futex, ("futex != wp_futex"));
  251                 LINUX_CTR5(sys_futex, "futex_sleep out error %d uaddr %p w"
  252                     " %p requeued uaddr %p ref %d",
  253                     error, f->f_uaddr, wp, wp->wp_futex->f_uaddr,
  254                     wp->wp_futex->f_refcount);
  255                 futex_put(f, NULL);
  256                 f = wp->wp_futex;
  257                 FUTEX_LOCK(f);
  258         } else
  259                 LINUX_CTR3(sys_futex, "futex_sleep out error %d uaddr %p wp %p",
  260                     error, f->f_uaddr, wp);
  261 
  262         futex_put(f, wp);
  263         return (error);
  264 }
  265 
  266 static int
  267 futex_wake(struct futex *f, int n)
  268 {
  269         struct waiting_proc *wp, *wpt;
  270         int count = 0;
  271 
  272         FUTEX_ASSERT_LOCKED(f);
  273         TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) {
  274                 LINUX_CTR3(sys_futex, "futex_wake uaddr %p wp %p ref %d",
  275                     f->f_uaddr, wp, f->f_refcount);
  276                 wp->wp_flags |= FUTEX_WP_REMOVED;
  277                 TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
  278                 wakeup_one(wp);
  279                 if (++count == n)
  280                         break;
  281         }
  282 
  283         return (count);
  284 }
  285 
  286 static int
  287 futex_requeue(struct futex *f, int n, struct futex *f2, int n2)
  288 {
  289         struct waiting_proc *wp, *wpt;
  290         int count = 0;
  291 
  292         FUTEX_ASSERT_LOCKED(f);
  293         FUTEX_ASSERT_LOCKED(f2);
  294 
  295         TAILQ_FOREACH_SAFE(wp, &f->f_waiting_proc, wp_list, wpt) {
  296                 if (++count <= n) {
  297                         LINUX_CTR2(sys_futex, "futex_req_wake uaddr %p wp %p",
  298                             f->f_uaddr, wp);
  299                         wp->wp_flags |= FUTEX_WP_REMOVED;
  300                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
  301                         wakeup_one(wp);
  302                 } else {
  303                         LINUX_CTR3(sys_futex, "futex_requeue uaddr %p wp %p to %p",
  304                             f->f_uaddr, wp, f2->f_uaddr);
  305                         wp->wp_flags |= FUTEX_WP_REQUEUED;
  306                         /* Move wp to wp_list of f2 futex */
  307                         TAILQ_REMOVE(&f->f_waiting_proc, wp, wp_list);
  308                         TAILQ_INSERT_HEAD(&f2->f_waiting_proc, wp, wp_list);
  309 
  310                         /*
  311                          * Thread which sleeps on wp after waking should
  312                          * acquire f2 lock, so increment refcount of f2 to
  313                          * prevent it from premature deallocation.
  314                          */
  315                         wp->wp_futex = f2;
  316                         FUTEXES_LOCK;
  317                         ++f2->f_refcount;
  318                         FUTEXES_UNLOCK;
  319                         if (count - n >= n2)
  320                                 break;
  321                 }
  322         }
  323 
  324         return (count);
  325 }
  326 
  327 static int
  328 futex_wait(struct futex *f, struct waiting_proc *wp, struct l_timespec *ts)
  329 {
  330         struct l_timespec timeout = {0, 0};
  331         struct timeval tv = {0, 0};
  332         int timeout_hz;
  333         int error;
  334 
  335         if (ts != NULL) {
  336                 error = copyin(ts, &timeout, sizeof(timeout));
  337                 if (error)
  338                         return (error);
  339         }
  340 
  341         tv.tv_usec = timeout.tv_sec * 1000000 + timeout.tv_nsec / 1000;
  342         timeout_hz = tvtohz(&tv);
  343 
  344         if (timeout.tv_sec == 0 && timeout.tv_nsec == 0)
  345                 timeout_hz = 0;
  346 
  347         /*
  348          * If the user process requests a non null timeout,
  349          * make sure we do not turn it into an infinite
  350          * timeout because timeout_hz gets null.
  351          *
  352          * We use a minimal timeout of 1/hz. Maybe it would
  353          * make sense to just return ETIMEDOUT without sleeping.
  354          */
  355         if (((timeout.tv_sec != 0) || (timeout.tv_nsec != 0)) &&
  356             (timeout_hz == 0))
  357                 timeout_hz = 1;
  358 
  359         error = futex_sleep(f, wp, timeout_hz);
  360         if (error == EWOULDBLOCK)
  361                 error = ETIMEDOUT;
  362 
  363         return (error);
  364 }
  365 
  366 static int
  367 futex_atomic_op(struct thread *td, int encoded_op, uint32_t *uaddr)
  368 {
  369         int op = (encoded_op >> 28) & 7;
  370         int cmp = (encoded_op >> 24) & 15;
  371         int oparg = (encoded_op << 8) >> 20;
  372         int cmparg = (encoded_op << 20) >> 20;
  373         int oldval = 0, ret;
  374 
  375         if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
  376                 oparg = 1 << oparg;
  377 
  378 #ifdef DEBUG
  379         if (ldebug(sys_futex))
  380                 printf("futex_atomic_op: op = %d, cmp = %d, oparg = %x, "
  381                        "cmparg = %x, uaddr = %p\n",
  382                        op, cmp, oparg, cmparg, uaddr);
  383 #endif
  384         /* XXX: linux verifies access here and returns EFAULT */
  385 
  386         switch (op) {
  387         case FUTEX_OP_SET:
  388                 ret = futex_xchgl(oparg, uaddr, &oldval);
  389                 break;
  390         case FUTEX_OP_ADD:
  391                 ret = futex_addl(oparg, uaddr, &oldval);
  392                 break;
  393         case FUTEX_OP_OR:
  394                 ret = futex_orl(oparg, uaddr, &oldval);
  395                 break;
  396         case FUTEX_OP_ANDN:
  397                 ret = futex_andl(~oparg, uaddr, &oldval);
  398                 break;
  399         case FUTEX_OP_XOR:
  400                 ret = futex_xorl(oparg, uaddr, &oldval);
  401                 break;
  402         default:
  403                 ret = -ENOSYS;
  404                 break;
  405         }
  406 
  407         if (ret)
  408                 return (ret);
  409 
  410         switch (cmp) {
  411         case FUTEX_OP_CMP_EQ:
  412                 return (oldval == cmparg);
  413         case FUTEX_OP_CMP_NE:
  414                 return (oldval != cmparg);
  415         case FUTEX_OP_CMP_LT:
  416                 return (oldval < cmparg);
  417         case FUTEX_OP_CMP_GE:
  418                 return (oldval >= cmparg);
  419         case FUTEX_OP_CMP_LE:
  420                 return (oldval <= cmparg);
  421         case FUTEX_OP_CMP_GT:
  422                 return (oldval > cmparg);
  423         default:
  424                 return (-ENOSYS);
  425         }
  426 }
  427 
  428 int
  429 linux_sys_futex(struct thread *td, struct linux_sys_futex_args *args)
  430 {
  431         int op_ret, val, ret, nrwake;
  432         struct linux_emuldata *em;
  433         struct waiting_proc *wp;
  434         struct futex *f, *f2;
  435         int error = 0;
  436 
  437         /*
  438          * Our implementation provides only privates futexes. Most of the apps
  439          * should use private futexes but don't claim so. Therefore we treat
  440          * all futexes as private by clearing the FUTEX_PRIVATE_FLAG. It works
  441          * in most cases (ie. when futexes are not shared on file descriptor
  442          * or between different processes.).
  443          */
  444         args->op = (args->op & ~LINUX_FUTEX_PRIVATE_FLAG);
  445 
  446         switch (args->op) {
  447         case LINUX_FUTEX_WAIT:
  448 
  449                 LINUX_CTR2(sys_futex, "WAIT val %d uaddr %p",
  450                     args->val, args->uaddr);
  451 #ifdef DEBUG
  452                 if (ldebug(sys_futex))
  453                         printf(ARGS(sys_futex, "futex_wait val %d uaddr %p"),
  454                             args->val, args->uaddr);
  455 #endif
  456                 error = futex_get(args->uaddr, &wp, &f, FUTEX_CREATE_WP);
  457                 if (error)
  458                         return (error);
  459                 error = copyin(args->uaddr, &val, sizeof(val));
  460                 if (error) {
  461                         LINUX_CTR1(sys_futex, "WAIT copyin failed %d",
  462                             error);
  463                         futex_put(f, wp);
  464                         return (error);
  465                 }
  466                 if (val != args->val) {
  467                         LINUX_CTR3(sys_futex, "WAIT uaddr %p val %d != uval %d",
  468                             args->uaddr, args->val, val);
  469                         futex_put(f, wp);
  470                         return (EWOULDBLOCK);
  471                 }
  472 
  473                 error = futex_wait(f, wp, args->timeout);
  474                 break;
  475 
  476         case LINUX_FUTEX_WAKE:
  477 
  478                 LINUX_CTR2(sys_futex, "WAKE val %d uaddr %p",
  479                     args->val, args->uaddr);
  480 
  481                 /*
  482                  * XXX: Linux is able to cope with different addresses
  483                  * corresponding to the same mapped memory in the sleeping
  484                  * and waker process(es).
  485                  */
  486 #ifdef DEBUG
  487                 if (ldebug(sys_futex))
  488                         printf(ARGS(sys_futex, "futex_wake val %d uaddr %p"),
  489                             args->val, args->uaddr);
  490 #endif
  491                 error = futex_get(args->uaddr, NULL, &f, FUTEX_DONTCREATE);
  492                 if (error)
  493                         return (error);
  494                 if (f == NULL) {
  495                         td->td_retval[0] = 0;
  496                         return (error);;
  497                 }
  498                 td->td_retval[0] = futex_wake(f, args->val);
  499                 futex_put(f, NULL);
  500                 break;
  501 
  502         case LINUX_FUTEX_CMP_REQUEUE:
  503 
  504                 LINUX_CTR5(sys_futex, "CMP_REQUEUE uaddr %p "
  505                     "val %d val3 %d uaddr2 %p val2 %d",
  506                     args->uaddr, args->val, args->val3, args->uaddr2,
  507                     (int)(unsigned long)args->timeout);
  508 
  509 #ifdef DEBUG
  510                 if (ldebug(sys_futex))
  511                         printf(ARGS(sys_futex, "futex_cmp_requeue uaddr %p "
  512                             "val %d val3 %d uaddr2 %p val2 %d"),
  513                             args->uaddr, args->val, args->val3, args->uaddr2,
  514                             (int)(unsigned long)args->timeout);
  515 #endif
  516 
  517                 /*
  518                  * Linux allows this, we would not, it is an incorrect
  519                  * usage of declared ABI, so return EINVAL.
  520                  */
  521                 if (args->uaddr == args->uaddr2)
  522                         return (EINVAL);
  523                 error = futex_get0(args->uaddr, &f, 0);
  524                 if (error)
  525                         return (error);
  526 
  527                 /*
  528                  * To avoid deadlocks return EINVAL if second futex
  529                  * exists at this time. Otherwise create the new futex
  530                  * and ignore false positive LOR which thus happens.
  531                  *
  532                  * Glibc fall back to FUTEX_WAKE in case of any error
  533                  * returned by FUTEX_CMP_REQUEUE.
  534                  */
  535                 error = futex_get0(args->uaddr2, &f2, FUTEX_DONTEXISTS);
  536                 if (error) {
  537                         futex_put(f, NULL);
  538                         return (error);
  539                 }
  540                 error = copyin(args->uaddr, &val, sizeof(val));
  541                 if (error) {
  542                         LINUX_CTR1(sys_futex, "CMP_REQUEUE copyin failed %d",
  543                             error);
  544                         futex_put(f2, NULL);
  545                         futex_put(f, NULL);
  546                         return (error);
  547                 }
  548                 if (val != args->val3) {
  549                         LINUX_CTR2(sys_futex, "CMP_REQUEUE val %d != uval %d",
  550                             args->val, val);
  551                         futex_put(f2, NULL);
  552                         futex_put(f, NULL);
  553                         return (EAGAIN);
  554                 }
  555 
  556                 nrwake = (int)(unsigned long)args->timeout;
  557                 td->td_retval[0] = futex_requeue(f, args->val, f2, nrwake);
  558                 futex_put(f2, NULL);
  559                 futex_put(f, NULL);
  560                 break;
  561 
  562         case LINUX_FUTEX_WAKE_OP:
  563 
  564                 LINUX_CTR5(sys_futex, "WAKE_OP "
  565                     "uaddr %p op %d val %x uaddr2 %p val3 %x",
  566                     args->uaddr, args->op, args->val,
  567                     args->uaddr2, args->val3);
  568 
  569 #ifdef DEBUG
  570                 if (ldebug(sys_futex))
  571                         printf(ARGS(sys_futex, "futex_wake_op "
  572                             "uaddr %p op %d val %x uaddr2 %p val3 %x"),
  573                             args->uaddr, args->op, args->val,
  574                             args->uaddr2, args->val3);
  575 #endif
  576                 error = futex_get0(args->uaddr, &f, 0);
  577                 if (error)
  578                         return (error);
  579                 if (args->uaddr != args->uaddr2)
  580                         error = futex_get0(args->uaddr2, &f2, 0);
  581                 if (error) {
  582                         futex_put(f, NULL);
  583                         return (error);
  584                 }
  585 
  586                 /*
  587                  * This function returns positive number as results and
  588                  * negative as errors
  589                  */
  590                 op_ret = futex_atomic_op(td, args->val3, args->uaddr2);
  591 
  592                 if (op_ret < 0) {
  593                         /* XXX: We don't handle the EFAULT yet. */
  594                         if (op_ret != -EFAULT) {
  595                                 if (f2 != NULL)
  596                                         futex_put(f2, NULL);
  597                                 futex_put(f, NULL);
  598                                 return (-op_ret);
  599                         }
  600                         if (f2 != NULL)
  601                                 futex_put(f2, NULL);
  602                         futex_put(f, NULL);
  603                         return (EFAULT);
  604                 }
  605 
  606                 ret = futex_wake(f, args->val);
  607 
  608                 if (op_ret > 0) {
  609                         op_ret = 0;
  610                         nrwake = (int)(unsigned long)args->timeout;
  611 
  612                         if (f2 != NULL)
  613                                 op_ret += futex_wake(f2, nrwake);
  614                         else
  615                                 op_ret += futex_wake(f, nrwake);
  616                         ret += op_ret;
  617 
  618                 }
  619                 if (f2 != NULL)
  620                         futex_put(f2, NULL);
  621                 futex_put(f, NULL);
  622                 td->td_retval[0] = ret;
  623                 break;
  624 
  625         case LINUX_FUTEX_LOCK_PI:
  626                 /* not yet implemented */
  627                 return (ENOSYS);
  628 
  629         case LINUX_FUTEX_UNLOCK_PI:
  630                 /* not yet implemented */
  631                 return (ENOSYS);
  632 
  633         case LINUX_FUTEX_TRYLOCK_PI:
  634                 /* not yet implemented */
  635                 return (ENOSYS);
  636 
  637         case LINUX_FUTEX_REQUEUE:
  638 
  639                 /*
  640                  * Glibc does not use this operation since version 2.3.3,
  641                  * as it is racy and replaced by FUTEX_CMP_REQUEUE operation.
  642                  * Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when
  643                  * FUTEX_REQUEUE returned EINVAL.
  644                  */
  645                 em = em_find(td->td_proc, EMUL_DONTLOCK);
  646                 if (em->used_requeue == 0) {
  647                         printf("linux(%s (%d)) sys_futex: "
  648                         "unsupported futex_requeue op\n",
  649                         td->td_proc->p_comm, td->td_proc->p_pid);
  650                                 em->used_requeue = 1;
  651                 }
  652                 return (EINVAL);
  653 
  654         default:
  655                 printf("linux_sys_futex: unknown op %d\n", args->op);
  656                 return (ENOSYS);
  657         }
  658 
  659         return (error);
  660 }
  661 
  662 int
  663 linux_set_robust_list(struct thread *td, struct linux_set_robust_list_args *args)
  664 {
  665         struct linux_emuldata *em;
  666 
  667 #ifdef DEBUG
  668         if (ldebug(set_robust_list))
  669                 printf(ARGS(set_robust_list, "head %p len %d"),
  670                     args->head, args->len);
  671 #endif
  672 
  673         if (args->len != sizeof(struct linux_robust_list_head))
  674                 return (EINVAL);
  675 
  676         em = em_find(td->td_proc, EMUL_DOLOCK);
  677         em->robust_futexes = args->head;
  678         EMUL_UNLOCK(&emul_lock);
  679 
  680         return (0);     
  681 }
  682 
  683 int
  684 linux_get_robust_list(struct thread *td, struct linux_get_robust_list_args *args)
  685 {
  686         struct linux_emuldata *em;
  687         struct linux_robust_list_head *head;
  688         l_size_t len = sizeof(struct linux_robust_list_head);
  689         int error = 0;
  690 
  691 #ifdef  DEBUG
  692         if (ldebug(get_robust_list))
  693                 printf(ARGS(get_robust_list, ""));
  694 #endif
  695 
  696         if (!args->pid) {
  697                 em = em_find(td->td_proc, EMUL_DONTLOCK);
  698                 head = em->robust_futexes;              
  699         } else {
  700                 struct proc *p;
  701 
  702                 p = pfind(args->pid);
  703                 if (p == NULL)
  704                         return (ESRCH);
  705 
  706                 em = em_find(p, EMUL_DONTLOCK);
  707                 /* XXX: ptrace? */
  708                 if (priv_check(td, PRIV_CRED_SETUID) || 
  709                     priv_check(td, PRIV_CRED_SETEUID) ||
  710                     p_candebug(td, p)) {
  711                         PROC_UNLOCK(p);
  712                         return (EPERM);
  713                 }
  714                 head = em->robust_futexes;
  715                 
  716                 PROC_UNLOCK(p);
  717         }
  718 
  719         error = copyout(&len, args->len, sizeof(l_size_t));
  720         if (error)
  721                 return (EFAULT);
  722 
  723         error = copyout(head, args->head, sizeof(struct linux_robust_list_head));
  724 
  725         return (error);
  726 }
  727 
  728 static int
  729 handle_futex_death(struct proc *p, uint32_t *uaddr, int pi)
  730 {
  731         uint32_t uval, nval, mval;
  732         struct futex *f;
  733         int error;
  734 
  735 retry:
  736         if (copyin(uaddr, &uval, 4))
  737                 return (EFAULT);
  738         if ((uval & FUTEX_TID_MASK) == p->p_pid) {
  739                 mval = (uval & FUTEX_WAITERS) | FUTEX_OWNER_DIED;
  740                 nval = casuword32(uaddr, uval, mval);
  741 
  742                 if (nval == -1)
  743                         return (EFAULT);
  744 
  745                 if (nval != uval)
  746                         goto retry;
  747 
  748                 if (!pi && (uval & FUTEX_WAITERS)) {
  749                         error = futex_get(uaddr, NULL, &f,
  750                             FUTEX_DONTCREATE);
  751                         if (error)
  752                                 return (error);
  753                         if (f != NULL) {
  754                                 futex_wake(f, 1);
  755                                 futex_put(f, NULL);
  756                         }
  757                 }
  758         }
  759 
  760         return (0);
  761 }
  762 
  763 static int
  764 fetch_robust_entry(struct linux_robust_list **entry,
  765     struct linux_robust_list **head, int *pi)
  766 {
  767         l_ulong uentry;
  768 
  769         if (copyin((const void *)head, &uentry, sizeof(l_ulong)))
  770                 return (EFAULT);
  771 
  772         *entry = (void *)(uentry & ~1UL);
  773         *pi = uentry & 1;
  774 
  775         return (0);
  776 }
  777 
  778 /* This walks the list of robust futexes releasing them. */
  779 void
  780 release_futexes(struct proc *p)
  781 {
  782         struct linux_robust_list_head *head = NULL;
  783         struct linux_robust_list *entry, *next_entry, *pending;
  784         unsigned int limit = 2048, pi, next_pi, pip;
  785         struct linux_emuldata *em;
  786         l_long futex_offset;
  787         int rc;
  788 
  789         em = em_find(p, EMUL_DONTLOCK);
  790         head = em->robust_futexes;
  791 
  792         if (head == NULL)
  793                 return;
  794 
  795         if (fetch_robust_entry(&entry, PTRIN(&head->list.next), &pi))
  796                 return;
  797 
  798         if (copyin(&head->futex_offset, &futex_offset, sizeof(futex_offset)))
  799                 return;
  800 
  801         if (fetch_robust_entry(&pending, PTRIN(&head->pending_list), &pip))
  802                 return;
  803 
  804         while (entry != &head->list) {
  805                 rc = fetch_robust_entry(&next_entry, PTRIN(&entry->next), &next_pi);
  806 
  807                 if (entry != pending)
  808                         if (handle_futex_death(p, (uint32_t *)entry + futex_offset, pi))
  809                                 return;
  810                 if (rc)
  811                         return;
  812 
  813                 entry = next_entry;
  814                 pi = next_pi;
  815 
  816                 if (!--limit)
  817                         break;
  818 
  819                 sched_relinquish(curthread);
  820         }
  821 
  822         if (pending)
  823                 handle_futex_death(p, (uint32_t *)pending + futex_offset, pip);
  824 }

Cache object: 87fb6208722a0924aced5e6a1e0b5da8


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