The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/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: releng/6.0/sys/kern/kern_subr.c 139804 2005-01-06 23:35:40Z imp $");
   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 /*
   72  * Identify the physical page mapped at the given kernel virtual
   73  * address.  Insert this physical page into the given address space at
   74  * the given virtual address, replacing the physical page, if any,
   75  * that already exists there.
   76  */
   77 static int
   78 vm_pgmoveco(vm_map_t mapa, vm_offset_t kaddr, vm_offset_t uaddr)
   79 {
   80         vm_map_t map = mapa;
   81         vm_page_t kern_pg, user_pg;
   82         vm_object_t uobject;
   83         vm_map_entry_t entry;
   84         vm_pindex_t upindex;
   85         vm_prot_t prot;
   86         boolean_t wired;
   87 
   88         KASSERT((uaddr & PAGE_MASK) == 0,
   89             ("vm_pgmoveco: uaddr is not page aligned"));
   90 
   91         /*
   92          * Herein the physical page is validated and dirtied.  It is
   93          * unwired in sf_buf_mext().
   94          */
   95         kern_pg = PHYS_TO_VM_PAGE(vtophys(kaddr));
   96         kern_pg->valid = VM_PAGE_BITS_ALL;
   97         KASSERT(kern_pg->queue == PQ_NONE && kern_pg->wire_count == 1,
   98             ("vm_pgmoveco: kern_pg is not correctly wired"));
   99 
  100         if ((vm_map_lookup(&map, uaddr,
  101                            VM_PROT_WRITE, &entry, &uobject,
  102                            &upindex, &prot, &wired)) != KERN_SUCCESS) {
  103                 return(EFAULT);
  104         }
  105         VM_OBJECT_LOCK(uobject);
  106 retry:
  107         if ((user_pg = vm_page_lookup(uobject, upindex)) != NULL) {
  108                 vm_page_lock_queues();
  109                 if (vm_page_sleep_if_busy(user_pg, 1, "vm_pgmoveco"))
  110                         goto retry;
  111                 pmap_remove_all(user_pg);
  112                 vm_page_free(user_pg);
  113         } else {
  114                 /*
  115                  * Even if a physical page does not exist in the
  116                  * object chain's first object, a physical page from a
  117                  * backing object may be mapped read only.
  118                  */
  119                 if (uobject->backing_object != NULL)
  120                         pmap_remove(map->pmap, uaddr, uaddr + PAGE_SIZE);
  121                 vm_page_lock_queues();
  122         }
  123         vm_page_insert(kern_pg, uobject, upindex);
  124         vm_page_dirty(kern_pg);
  125         vm_page_unlock_queues();
  126         VM_OBJECT_UNLOCK(uobject);
  127         vm_map_lookup_done(map, entry);
  128         return(KERN_SUCCESS);
  129 }
  130 #endif /* ZERO_COPY_SOCKETS */
  131 
  132 int
  133 uiomove(void *cp, int n, struct uio *uio)
  134 {
  135         struct thread *td = curthread;
  136         struct iovec *iov;
  137         u_int cnt;
  138         int error = 0;
  139         int save = 0;
  140 
  141         KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
  142             ("uiomove: mode"));
  143         KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
  144             ("uiomove proc"));
  145         WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
  146             "Calling uiomove()");
  147 
  148         save = td->td_pflags & TDP_DEADLKTREAT;
  149         td->td_pflags |= TDP_DEADLKTREAT;
  150 
  151         while (n > 0 && uio->uio_resid) {
  152                 iov = uio->uio_iov;
  153                 cnt = iov->iov_len;
  154                 if (cnt == 0) {
  155                         uio->uio_iov++;
  156                         uio->uio_iovcnt--;
  157                         continue;
  158                 }
  159                 if (cnt > n)
  160                         cnt = n;
  161 
  162                 switch (uio->uio_segflg) {
  163 
  164                 case UIO_USERSPACE:
  165                         if (ticks - PCPU_GET(switchticks) >= hogticks)
  166                                 uio_yield();
  167                         if (uio->uio_rw == UIO_READ)
  168                                 error = copyout(cp, iov->iov_base, cnt);
  169                         else
  170                                 error = copyin(iov->iov_base, cp, cnt);
  171                         if (error)
  172                                 goto out;
  173                         break;
  174 
  175                 case UIO_SYSSPACE:
  176                         if (uio->uio_rw == UIO_READ)
  177                                 bcopy(cp, iov->iov_base, cnt);
  178                         else
  179                                 bcopy(iov->iov_base, cp, cnt);
  180                         break;
  181                 case UIO_NOCOPY:
  182                         break;
  183                 }
  184                 iov->iov_base = (char *)iov->iov_base + cnt;
  185                 iov->iov_len -= cnt;
  186                 uio->uio_resid -= cnt;
  187                 uio->uio_offset += cnt;
  188                 cp = (char *)cp + cnt;
  189                 n -= cnt;
  190         }
  191 out:
  192         if (save == 0)
  193                 td->td_pflags &= ~TDP_DEADLKTREAT;
  194         return (error);
  195 }
  196 
  197 /*
  198  * Wrapper for uiomove() that validates the arguments against a known-good
  199  * kernel buffer.  Currently, uiomove accepts a signed (n) argument, which
  200  * is almost definitely a bad thing, so we catch that here as well.  We
  201  * return a runtime failure, but it might be desirable to generate a runtime
  202  * assertion failure instead.
  203  */
  204 int
  205 uiomove_frombuf(void *buf, int buflen, struct uio *uio)
  206 {
  207         unsigned int offset, n;
  208 
  209         if (uio->uio_offset < 0 || uio->uio_resid < 0 ||
  210             (offset = uio->uio_offset) != uio->uio_offset)
  211                 return (EINVAL);
  212         if (buflen <= 0 || offset >= buflen)
  213                 return (0);
  214         if ((n = buflen - offset) > INT_MAX)
  215                 return (EINVAL);
  216         return (uiomove((char *)buf + offset, n, uio));
  217 }
  218 
  219 #ifdef ZERO_COPY_SOCKETS
  220 /*
  221  * Experimental support for zero-copy I/O
  222  */
  223 static int
  224 userspaceco(void *cp, u_int cnt, struct uio *uio, int disposable)
  225 {
  226         struct iovec *iov;
  227         int error;
  228 
  229         iov = uio->uio_iov;
  230         if (uio->uio_rw == UIO_READ) {
  231                 if ((so_zero_copy_receive != 0)
  232                  && ((cnt & PAGE_MASK) == 0)
  233                  && ((((intptr_t) iov->iov_base) & PAGE_MASK) == 0)
  234                  && ((uio->uio_offset & PAGE_MASK) == 0)
  235                  && ((((intptr_t) cp) & PAGE_MASK) == 0)
  236                  && (disposable != 0)) {
  237                         /* SOCKET: use page-trading */
  238                         /*
  239                          * We only want to call vm_pgmoveco() on
  240                          * disposeable pages, since it gives the
  241                          * kernel page to the userland process.
  242                          */
  243                         error = vm_pgmoveco(&curproc->p_vmspace->vm_map,
  244                             (vm_offset_t)cp, (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, int disposable)
  266 {
  267         struct iovec *iov;
  268         u_int cnt;
  269         int error;
  270 
  271         KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
  272             ("uiomoveco: mode"));
  273         KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
  274             ("uiomoveco proc"));
  275 
  276         while (n > 0 && uio->uio_resid) {
  277                 iov = uio->uio_iov;
  278                 cnt = iov->iov_len;
  279                 if (cnt == 0) {
  280                         uio->uio_iov++;
  281                         uio->uio_iovcnt--;
  282                         continue;
  283                 }
  284                 if (cnt > n)
  285                         cnt = n;
  286 
  287                 switch (uio->uio_segflg) {
  288 
  289                 case UIO_USERSPACE:
  290                         if (ticks - PCPU_GET(switchticks) >= hogticks)
  291                                 uio_yield();
  292 
  293                         error = userspaceco(cp, cnt, uio, disposable);
  294 
  295                         if (error)
  296                                 return (error);
  297                         break;
  298 
  299                 case UIO_SYSSPACE:
  300                         if (uio->uio_rw == UIO_READ)
  301                                 bcopy(cp, iov->iov_base, cnt);
  302                         else
  303                                 bcopy(iov->iov_base, cp, cnt);
  304                         break;
  305                 case UIO_NOCOPY:
  306                         break;
  307                 }
  308                 iov->iov_base = (char *)iov->iov_base + cnt;
  309                 iov->iov_len -= cnt;
  310                 uio->uio_resid -= cnt;
  311                 uio->uio_offset += cnt;
  312                 cp = (char *)cp + cnt;
  313                 n -= cnt;
  314         }
  315         return (0);
  316 }
  317 #endif /* ZERO_COPY_SOCKETS */
  318 
  319 /*
  320  * Give next character to user as result of read.
  321  */
  322 int
  323 ureadc(int c, struct uio *uio)
  324 {
  325         struct iovec *iov;
  326         char *iov_base;
  327 
  328 again:
  329         if (uio->uio_iovcnt == 0 || uio->uio_resid == 0)
  330                 panic("ureadc");
  331         iov = uio->uio_iov;
  332         if (iov->iov_len == 0) {
  333                 uio->uio_iovcnt--;
  334                 uio->uio_iov++;
  335                 goto again;
  336         }
  337         switch (uio->uio_segflg) {
  338 
  339         case UIO_USERSPACE:
  340                 if (subyte(iov->iov_base, c) < 0)
  341                         return (EFAULT);
  342                 break;
  343 
  344         case UIO_SYSSPACE:
  345                 iov_base = iov->iov_base;
  346                 *iov_base = c;
  347                 iov->iov_base = iov_base;
  348                 break;
  349 
  350         case UIO_NOCOPY:
  351                 break;
  352         }
  353         iov->iov_base = (char *)iov->iov_base + 1;
  354         iov->iov_len--;
  355         uio->uio_resid--;
  356         uio->uio_offset++;
  357         return (0);
  358 }
  359 
  360 /*
  361  * General routine to allocate a hash table.
  362  */
  363 void *
  364 hashinit(int elements, struct malloc_type *type, u_long *hashmask)
  365 {
  366         long hashsize;
  367         LIST_HEAD(generic, generic) *hashtbl;
  368         int i;
  369 
  370         if (elements <= 0)
  371                 panic("hashinit: bad elements");
  372         for (hashsize = 1; hashsize <= elements; hashsize <<= 1)
  373                 continue;
  374         hashsize >>= 1;
  375         hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type, M_WAITOK);
  376         for (i = 0; i < hashsize; i++)
  377                 LIST_INIT(&hashtbl[i]);
  378         *hashmask = hashsize - 1;
  379         return (hashtbl);
  380 }
  381 
  382 void
  383 hashdestroy(void *vhashtbl, struct malloc_type *type, u_long hashmask)
  384 {
  385         LIST_HEAD(generic, generic) *hashtbl, *hp;
  386 
  387         hashtbl = vhashtbl;
  388         for (hp = hashtbl; hp <= &hashtbl[hashmask]; hp++)
  389                 if (!LIST_EMPTY(hp))
  390                         panic("hashdestroy: hash not empty");
  391         free(hashtbl, type);
  392 }
  393 
  394 static int primes[] = { 1, 13, 31, 61, 127, 251, 509, 761, 1021, 1531, 2039,
  395                         2557, 3067, 3583, 4093, 4603, 5119, 5623, 6143, 6653,
  396                         7159, 7673, 8191, 12281, 16381, 24571, 32749 };
  397 #define NPRIMES (sizeof(primes) / sizeof(primes[0]))
  398 
  399 /*
  400  * General routine to allocate a prime number sized hash table.
  401  */
  402 void *
  403 phashinit(int elements, struct malloc_type *type, u_long *nentries)
  404 {
  405         long hashsize;
  406         LIST_HEAD(generic, generic) *hashtbl;
  407         int i;
  408 
  409         if (elements <= 0)
  410                 panic("phashinit: bad elements");
  411         for (i = 1, hashsize = primes[1]; hashsize <= elements;) {
  412                 i++;
  413                 if (i == NPRIMES)
  414                         break;
  415                 hashsize = primes[i];
  416         }
  417         hashsize = primes[i - 1];
  418         hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type, M_WAITOK);
  419         for (i = 0; i < hashsize; i++)
  420                 LIST_INIT(&hashtbl[i]);
  421         *nentries = hashsize;
  422         return (hashtbl);
  423 }
  424 
  425 void
  426 uio_yield(void)
  427 {
  428         struct thread *td;
  429 
  430         td = curthread;
  431         mtx_lock_spin(&sched_lock);
  432         DROP_GIANT();
  433         sched_prio(td, td->td_ksegrp->kg_user_pri); /* XXXKSE */
  434         mi_switch(SW_INVOL, NULL);
  435         mtx_unlock_spin(&sched_lock);
  436         PICKUP_GIANT();
  437 }
  438 
  439 int
  440 copyinfrom(const void * __restrict src, void * __restrict dst, size_t len,
  441     int seg)
  442 {
  443         int error = 0;
  444 
  445         switch (seg) {
  446         case UIO_USERSPACE:
  447                 error = copyin(src, dst, len);
  448                 break;
  449         case UIO_SYSSPACE:
  450                 bcopy(src, dst, len);
  451                 break;
  452         default:
  453                 panic("copyinfrom: bad seg %d\n", seg);
  454         }
  455         return (error);
  456 }
  457 
  458 int
  459 copyinstrfrom(const void * __restrict src, void * __restrict dst, size_t len,
  460     size_t * __restrict copied, int seg)
  461 {
  462         int error = 0;
  463 
  464         switch (seg) {
  465         case UIO_USERSPACE:
  466                 error = copyinstr(src, dst, len, copied);
  467                 break;
  468         case UIO_SYSSPACE:
  469                 error = copystr(src, dst, len, copied);
  470                 break;
  471         default:
  472                 panic("copyinstrfrom: bad seg %d\n", seg);
  473         }
  474         return (error);
  475 }
  476 
  477 int
  478 copyiniov(struct iovec *iovp, u_int iovcnt, struct iovec **iov, int error)
  479 {
  480         u_int iovlen;
  481 
  482         *iov = NULL;
  483         if (iovcnt > UIO_MAXIOV)
  484                 return (error);
  485         iovlen = iovcnt * sizeof (struct iovec);
  486         *iov = malloc(iovlen, M_IOV, M_WAITOK);
  487         error = copyin(iovp, *iov, iovlen);
  488         if (error) {
  489                 free(*iov, M_IOV);
  490                 *iov = NULL;
  491         }
  492         return (error);
  493 }
  494 
  495 int
  496 copyinuio(struct iovec *iovp, u_int iovcnt, struct uio **uiop)
  497 {
  498         struct iovec *iov;
  499         struct uio *uio;
  500         u_int iovlen;
  501         int error, i;
  502 
  503         *uiop = NULL;
  504         if (iovcnt > UIO_MAXIOV)
  505                 return (EINVAL);
  506         iovlen = iovcnt * sizeof (struct iovec);
  507         uio = malloc(iovlen + sizeof *uio, M_IOV, M_WAITOK);
  508         iov = (struct iovec *)(uio + 1);
  509         error = copyin(iovp, iov, iovlen);
  510         if (error) {
  511                 free(uio, M_IOV);
  512                 return (error);
  513         }
  514         uio->uio_iov = iov;
  515         uio->uio_iovcnt = iovcnt;
  516         uio->uio_segflg = UIO_USERSPACE;
  517         uio->uio_offset = -1;
  518         uio->uio_resid = 0;
  519         for (i = 0; i < iovcnt; i++) {
  520                 if (iov->iov_len > INT_MAX - uio->uio_resid) {
  521                         free(uio, M_IOV);
  522                         return (EINVAL);
  523                 }
  524                 uio->uio_resid += iov->iov_len;
  525                 iov++;
  526         }
  527         *uiop = uio;
  528         return (0);
  529 }
  530 
  531 struct uio *
  532 cloneuio(struct uio *uiop)
  533 {
  534         struct uio *uio;
  535         int iovlen;
  536 
  537         iovlen = uiop->uio_iovcnt * sizeof (struct iovec);
  538         uio = malloc(iovlen + sizeof *uio, M_IOV, M_WAITOK);
  539         *uio = *uiop;
  540         uio->uio_iov = (struct iovec *)(uio + 1);
  541         bcopy(uiop->uio_iov, uio->uio_iov, iovlen);
  542         return (uio);
  543 }

Cache object: 9d70f62e0cc2c47aa4cbcf773073929a


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