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

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    1 /*-
    2  * Copyright (c) 1982, 1986, 1991, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  * (c) UNIX System Laboratories, Inc.
    5  * All or some portions of this file are derived from material licensed
    6  * to the University of California by American Telephone and Telegraph
    7  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
    8  * the permission of UNIX System Laboratories, Inc.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 4. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  *      @(#)kern_subr.c 8.3 (Berkeley) 1/21/94
   35  */
   36 
   37 #include <sys/cdefs.h>
   38 __FBSDID("$FreeBSD: src/sys/kern/kern_subr.c,v 1.88.2.2 2005/01/31 23:26:16 imp Exp $");
   39 
   40 #include "opt_zero.h"
   41 
   42 #include <sys/param.h>
   43 #include <sys/systm.h>
   44 #include <sys/kernel.h>
   45 #include <sys/ktr.h>
   46 #include <sys/limits.h>
   47 #include <sys/lock.h>
   48 #include <sys/mutex.h>
   49 #include <sys/proc.h>
   50 #include <sys/malloc.h>
   51 #include <sys/resourcevar.h>
   52 #include <sys/sched.h>
   53 #include <sys/sysctl.h>
   54 #include <sys/vnode.h>
   55 
   56 #include <vm/vm.h>
   57 #include <vm/vm_page.h>
   58 #include <vm/vm_map.h>
   59 #ifdef ZERO_COPY_SOCKETS
   60 #include <vm/vm_param.h>
   61 #include <vm/vm_object.h>
   62 #endif
   63 
   64 SYSCTL_INT(_kern, KERN_IOV_MAX, iov_max, CTLFLAG_RD, NULL, UIO_MAXIOV,
   65         "Maximum number of elements in an I/O vector; sysconf(_SC_IOV_MAX)");
   66 
   67 #ifdef ZERO_COPY_SOCKETS
   68 /* Declared in uipc_socket.c */
   69 extern int so_zero_copy_receive;
   70 
   71 static int
   72 vm_pgmoveco(vm_map_t mapa, vm_object_t srcobj, vm_offset_t kaddr,
   73     vm_offset_t uaddr)
   74 {
   75         vm_map_t map = mapa;
   76         vm_page_t kern_pg, user_pg;
   77         vm_object_t uobject;
   78         vm_map_entry_t entry;
   79         vm_pindex_t upindex, kpindex;
   80         vm_prot_t prot;
   81         boolean_t wired;
   82 
   83         /*
   84          * First lookup the kernel page.
   85          */
   86         kern_pg = PHYS_TO_VM_PAGE(vtophys(kaddr));
   87         /*
   88          * XXX The vm object containing kern_pg needs locking.
   89          */
   90         if ((vm_map_lookup(&map, uaddr,
   91                            VM_PROT_WRITE, &entry, &uobject,
   92                            &upindex, &prot, &wired)) != KERN_SUCCESS) {
   93                 return(EFAULT);
   94         }
   95         VM_OBJECT_LOCK(uobject);
   96         if ((user_pg = vm_page_lookup(uobject, upindex)) != NULL) {
   97                 do
   98                         vm_page_lock_queues();
   99                 while (vm_page_sleep_if_busy(user_pg, 1, "vm_pgmoveco"));
  100                 vm_page_busy(user_pg);
  101                 pmap_remove_all(user_pg);
  102                 vm_page_free(user_pg);
  103         } else
  104                 vm_page_lock_queues();
  105         if (kern_pg->busy || ((kern_pg->queue - kern_pg->pc) == PQ_FREE) ||
  106             (kern_pg->hold_count != 0)|| (kern_pg->flags & PG_BUSY)) {
  107                 printf("vm_pgmoveco: pindex(%lu), busy(%d), PG_BUSY(%d), "
  108                        "hold(%d) paddr(0x%lx)\n", (u_long)kern_pg->pindex,
  109                         kern_pg->busy, (kern_pg->flags & PG_BUSY) ? 1 : 0,
  110                         kern_pg->hold_count, (u_long)kern_pg->phys_addr);
  111                 if ((kern_pg->queue - kern_pg->pc) == PQ_FREE)
  112                         panic("vm_pgmoveco: renaming free page");
  113                 else
  114                         panic("vm_pgmoveco: renaming busy page");
  115         }
  116         kpindex = kern_pg->pindex;
  117         vm_page_busy(kern_pg);
  118         vm_page_rename(kern_pg, uobject, upindex);
  119         vm_page_flag_clear(kern_pg, PG_BUSY);
  120         kern_pg->valid = VM_PAGE_BITS_ALL;
  121         vm_page_unlock_queues();
  122         VM_OBJECT_UNLOCK(uobject);
  123         vm_map_lookup_done(map, entry);
  124         return(KERN_SUCCESS);
  125 }
  126 #endif /* ZERO_COPY_SOCKETS */
  127 
  128 int
  129 uiomove(void *cp, int n, struct uio *uio)
  130 {
  131         struct thread *td = curthread;
  132         struct iovec *iov;
  133         u_int cnt;
  134         int error = 0;
  135         int save = 0;
  136 
  137         KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
  138             ("uiomove: mode"));
  139         KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
  140             ("uiomove proc"));
  141         WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
  142             "Calling uiomove()");
  143 
  144         save = td->td_pflags & TDP_DEADLKTREAT;
  145         td->td_pflags |= TDP_DEADLKTREAT;
  146 
  147         while (n > 0 && uio->uio_resid) {
  148                 iov = uio->uio_iov;
  149                 cnt = iov->iov_len;
  150                 if (cnt == 0) {
  151                         uio->uio_iov++;
  152                         uio->uio_iovcnt--;
  153                         continue;
  154                 }
  155                 if (cnt > n)
  156                         cnt = n;
  157 
  158                 switch (uio->uio_segflg) {
  159 
  160                 case UIO_USERSPACE:
  161                         if (ticks - PCPU_GET(switchticks) >= hogticks)
  162                                 uio_yield();
  163                         if (uio->uio_rw == UIO_READ)
  164                                 error = copyout(cp, iov->iov_base, cnt);
  165                         else
  166                                 error = copyin(iov->iov_base, cp, cnt);
  167                         if (error)
  168                                 goto out;
  169                         break;
  170 
  171                 case UIO_SYSSPACE:
  172                         if (uio->uio_rw == UIO_READ)
  173                                 bcopy(cp, iov->iov_base, cnt);
  174                         else
  175                                 bcopy(iov->iov_base, cp, cnt);
  176                         break;
  177                 case UIO_NOCOPY:
  178                         break;
  179                 }
  180                 iov->iov_base = (char *)iov->iov_base + cnt;
  181                 iov->iov_len -= cnt;
  182                 uio->uio_resid -= cnt;
  183                 uio->uio_offset += cnt;
  184                 cp = (char *)cp + cnt;
  185                 n -= cnt;
  186         }
  187 out:
  188         if (save == 0)
  189                 td->td_pflags &= ~TDP_DEADLKTREAT;
  190         return (error);
  191 }
  192 
  193 /*
  194  * Wrapper for uiomove() that validates the arguments against a known-good
  195  * kernel buffer.  Currently, uiomove accepts a signed (n) argument, which
  196  * is almost definitely a bad thing, so we catch that here as well.  We
  197  * return a runtime failure, but it might be desirable to generate a runtime
  198  * assertion failure instead.
  199  */
  200 int
  201 uiomove_frombuf(void *buf, int buflen, struct uio *uio)
  202 {
  203         unsigned int offset, n;
  204 
  205         if (uio->uio_offset < 0 || uio->uio_resid < 0 ||
  206             (offset = uio->uio_offset) != uio->uio_offset)
  207                 return (EINVAL);
  208         if (buflen <= 0 || offset >= buflen)
  209                 return (0);
  210         if ((n = buflen - offset) > INT_MAX)
  211                 return (EINVAL);
  212         return (uiomove((char *)buf + offset, n, uio));
  213 }
  214 
  215 #ifdef ZERO_COPY_SOCKETS
  216 /*
  217  * Experimental support for zero-copy I/O
  218  */
  219 static int
  220 userspaceco(void *cp, u_int cnt, struct uio *uio, struct vm_object *obj,
  221     int disposable)
  222 {
  223         struct iovec *iov;
  224         int error;
  225 
  226         iov = uio->uio_iov;
  227         if (uio->uio_rw == UIO_READ) {
  228                 if ((so_zero_copy_receive != 0)
  229                  && (obj != NULL)
  230                  && ((cnt & PAGE_MASK) == 0)
  231                  && ((((intptr_t) iov->iov_base) & PAGE_MASK) == 0)
  232                  && ((uio->uio_offset & PAGE_MASK) == 0)
  233                  && ((((intptr_t) cp) & PAGE_MASK) == 0)
  234                  && (obj->type == OBJT_DEFAULT)
  235                  && (disposable != 0)) {
  236                         /* SOCKET: use page-trading */
  237                         /*
  238                          * We only want to call vm_pgmoveco() on
  239                          * disposeable pages, since it gives the
  240                          * kernel page to the userland process.
  241                          */
  242                         error = vm_pgmoveco(&curproc->p_vmspace->vm_map,
  243                                             obj, (vm_offset_t)cp,
  244                                             (vm_offset_t)iov->iov_base);
  245 
  246                         /*
  247                          * If we get an error back, attempt
  248                          * to use copyout() instead.  The
  249                          * disposable page should be freed
  250                          * automatically if we weren't able to move
  251                          * it into userland.
  252                          */
  253                         if (error != 0)
  254                                 error = copyout(cp, iov->iov_base, cnt);
  255                 } else {
  256                         error = copyout(cp, iov->iov_base, cnt);
  257                 }
  258         } else {
  259                 error = copyin(iov->iov_base, cp, cnt);
  260         }
  261         return (error);
  262 }
  263 
  264 int
  265 uiomoveco(void *cp, int n, struct uio *uio, struct vm_object *obj,
  266     int disposable)
  267 {
  268         struct iovec *iov;
  269         u_int cnt;
  270         int error;
  271 
  272         KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
  273             ("uiomoveco: mode"));
  274         KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
  275             ("uiomoveco proc"));
  276 
  277         while (n > 0 && uio->uio_resid) {
  278                 iov = uio->uio_iov;
  279                 cnt = iov->iov_len;
  280                 if (cnt == 0) {
  281                         uio->uio_iov++;
  282                         uio->uio_iovcnt--;
  283                         continue;
  284                 }
  285                 if (cnt > n)
  286                         cnt = n;
  287 
  288                 switch (uio->uio_segflg) {
  289 
  290                 case UIO_USERSPACE:
  291                         if (ticks - PCPU_GET(switchticks) >= hogticks)
  292                                 uio_yield();
  293 
  294                         error = userspaceco(cp, cnt, uio, obj, disposable);
  295 
  296                         if (error)
  297                                 return (error);
  298                         break;
  299 
  300                 case UIO_SYSSPACE:
  301                         if (uio->uio_rw == UIO_READ)
  302                                 bcopy(cp, iov->iov_base, cnt);
  303                         else
  304                                 bcopy(iov->iov_base, cp, cnt);
  305                         break;
  306                 case UIO_NOCOPY:
  307                         break;
  308                 }
  309                 iov->iov_base = (char *)iov->iov_base + cnt;
  310                 iov->iov_len -= cnt;
  311                 uio->uio_resid -= cnt;
  312                 uio->uio_offset += cnt;
  313                 cp = (char *)cp + cnt;
  314                 n -= cnt;
  315         }
  316         return (0);
  317 }
  318 #endif /* ZERO_COPY_SOCKETS */
  319 
  320 /*
  321  * Give next character to user as result of read.
  322  */
  323 int
  324 ureadc(int c, struct uio *uio)
  325 {
  326         struct iovec *iov;
  327         char *iov_base;
  328 
  329 again:
  330         if (uio->uio_iovcnt == 0 || uio->uio_resid == 0)
  331                 panic("ureadc");
  332         iov = uio->uio_iov;
  333         if (iov->iov_len == 0) {
  334                 uio->uio_iovcnt--;
  335                 uio->uio_iov++;
  336                 goto again;
  337         }
  338         switch (uio->uio_segflg) {
  339 
  340         case UIO_USERSPACE:
  341                 if (subyte(iov->iov_base, c) < 0)
  342                         return (EFAULT);
  343                 break;
  344 
  345         case UIO_SYSSPACE:
  346                 iov_base = iov->iov_base;
  347                 *iov_base = c;
  348                 iov->iov_base = iov_base;
  349                 break;
  350 
  351         case UIO_NOCOPY:
  352                 break;
  353         }
  354         iov->iov_base = (char *)iov->iov_base + 1;
  355         iov->iov_len--;
  356         uio->uio_resid--;
  357         uio->uio_offset++;
  358         return (0);
  359 }
  360 
  361 /*
  362  * General routine to allocate a hash table.
  363  */
  364 void *
  365 hashinit(int elements, struct malloc_type *type, u_long *hashmask)
  366 {
  367         long hashsize;
  368         LIST_HEAD(generic, generic) *hashtbl;
  369         int i;
  370 
  371         if (elements <= 0)
  372                 panic("hashinit: bad elements");
  373         for (hashsize = 1; hashsize <= elements; hashsize <<= 1)
  374                 continue;
  375         hashsize >>= 1;
  376         hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type, M_WAITOK);
  377         for (i = 0; i < hashsize; i++)
  378                 LIST_INIT(&hashtbl[i]);
  379         *hashmask = hashsize - 1;
  380         return (hashtbl);
  381 }
  382 
  383 void
  384 hashdestroy(void *vhashtbl, struct malloc_type *type, u_long hashmask)
  385 {
  386         LIST_HEAD(generic, generic) *hashtbl, *hp;
  387 
  388         hashtbl = vhashtbl;
  389         for (hp = hashtbl; hp <= &hashtbl[hashmask]; hp++)
  390                 if (!LIST_EMPTY(hp))
  391                         panic("hashdestroy: hash not empty");
  392         free(hashtbl, type);
  393 }
  394 
  395 static int primes[] = { 1, 13, 31, 61, 127, 251, 509, 761, 1021, 1531, 2039,
  396                         2557, 3067, 3583, 4093, 4603, 5119, 5623, 6143, 6653,
  397                         7159, 7673, 8191, 12281, 16381, 24571, 32749 };
  398 #define NPRIMES (sizeof(primes) / sizeof(primes[0]))
  399 
  400 /*
  401  * General routine to allocate a prime number sized hash table.
  402  */
  403 void *
  404 phashinit(int elements, struct malloc_type *type, u_long *nentries)
  405 {
  406         long hashsize;
  407         LIST_HEAD(generic, generic) *hashtbl;
  408         int i;
  409 
  410         if (elements <= 0)
  411                 panic("phashinit: bad elements");
  412         for (i = 1, hashsize = primes[1]; hashsize <= elements;) {
  413                 i++;
  414                 if (i == NPRIMES)
  415                         break;
  416                 hashsize = primes[i];
  417         }
  418         hashsize = primes[i - 1];
  419         hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type, M_WAITOK);
  420         for (i = 0; i < hashsize; i++)
  421                 LIST_INIT(&hashtbl[i]);
  422         *nentries = hashsize;
  423         return (hashtbl);
  424 }
  425 
  426 void
  427 uio_yield(void)
  428 {
  429         struct thread *td;
  430 
  431         td = curthread;
  432         mtx_lock_spin(&sched_lock);
  433         DROP_GIANT();
  434         sched_prio(td, td->td_ksegrp->kg_user_pri); /* XXXKSE */
  435         mi_switch(SW_INVOL, NULL);
  436         mtx_unlock_spin(&sched_lock);
  437         PICKUP_GIANT();
  438 }
  439 
  440 int
  441 copyinfrom(const void * __restrict src, void * __restrict dst, size_t len,
  442     int seg)
  443 {
  444         int error = 0;
  445 
  446         switch (seg) {
  447         case UIO_USERSPACE:
  448                 error = copyin(src, dst, len);
  449                 break;
  450         case UIO_SYSSPACE:
  451                 bcopy(src, dst, len);
  452                 break;
  453         default:
  454                 panic("copyinfrom: bad seg %d\n", seg);
  455         }
  456         return (error);
  457 }
  458 
  459 int
  460 copyinstrfrom(const void * __restrict src, void * __restrict dst, size_t len,
  461     size_t * __restrict copied, int seg)
  462 {
  463         int error = 0;
  464 
  465         switch (seg) {
  466         case UIO_USERSPACE:
  467                 error = copyinstr(src, dst, len, copied);
  468                 break;
  469         case UIO_SYSSPACE:
  470                 error = copystr(src, dst, len, copied);
  471                 break;
  472         default:
  473                 panic("copyinstrfrom: bad seg %d\n", seg);
  474         }
  475         return (error);
  476 }
  477 
  478 int
  479 copyiniov(struct iovec *iovp, u_int iovcnt, struct iovec **iov, int error)
  480 {
  481         u_int iovlen;
  482 
  483         *iov = NULL;
  484         if (iovcnt > UIO_MAXIOV)
  485                 return (error);
  486         iovlen = iovcnt * sizeof (struct iovec);
  487         *iov = malloc(iovlen, M_IOV, M_WAITOK);
  488         error = copyin(iovp, *iov, iovlen);
  489         if (error) {
  490                 free(*iov, M_IOV);
  491                 *iov = NULL;
  492         }
  493         return (error);
  494 }
  495 
  496 int
  497 copyinuio(struct iovec *iovp, u_int iovcnt, struct uio **uiop)
  498 {
  499         struct iovec *iov;
  500         struct uio *uio;
  501         u_int iovlen;
  502         int error, i;
  503 
  504         *uiop = NULL;
  505         if (iovcnt > UIO_MAXIOV)
  506                 return (EINVAL);
  507         iovlen = iovcnt * sizeof (struct iovec);
  508         uio = malloc(iovlen + sizeof *uio, M_IOV, M_WAITOK);
  509         iov = (struct iovec *)(uio + 1);
  510         error = copyin(iovp, iov, iovlen);
  511         if (error) {
  512                 free(uio, M_IOV);
  513                 return (error);
  514         }
  515         uio->uio_iov = iov;
  516         uio->uio_iovcnt = iovcnt;
  517         uio->uio_segflg = UIO_USERSPACE;
  518         uio->uio_offset = -1;
  519         uio->uio_resid = 0;
  520         for (i = 0; i < iovcnt; i++) {
  521                 if (iov->iov_len > INT_MAX - uio->uio_resid) {
  522                         free(uio, M_IOV);
  523                         return (EINVAL);
  524                 }
  525                 uio->uio_resid += iov->iov_len;
  526                 iov++;
  527         }
  528         *uiop = uio;
  529         return (0);
  530 }
  531 
  532 struct uio *
  533 cloneuio(struct uio *uiop)
  534 {
  535         struct uio *uio;
  536         int iovlen;
  537 
  538         iovlen = uiop->uio_iovcnt * sizeof (struct iovec);
  539         uio = malloc(iovlen + sizeof *uio, M_IOV, M_WAITOK);
  540         *uio = *uiop;
  541         uio->uio_iov = (struct iovec *)(uio + 1);
  542         bcopy(uiop->uio_iov, uio->uio_iov, iovlen);
  543         return (uio);
  544 }

Cache object: 1e09fc86bc003b93e2a0de8b191396ca


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