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  * 3. All advertising materials mentioning features or use of this software
   19  *    must display the following acknowledgement:
   20  *      This product includes software developed by the University of
   21  *      California, Berkeley and its contributors.
   22  * 4. Neither the name of the University nor the names of its contributors
   23  *    may be used to endorse or promote products derived from this software
   24  *    without specific prior written permission.
   25  *
   26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   36  * SUCH DAMAGE.
   37  *
   38  *      @(#)kern_subr.c 8.3 (Berkeley) 1/21/94
   39  * $FreeBSD: releng/5.1/sys/kern/kern_subr.c 120688 2003-10-03 13:02:50Z nectar $
   40  */
   41 
   42 #include "opt_zero.h"
   43 
   44 #include <sys/param.h>
   45 #include <sys/systm.h>
   46 #include <sys/kernel.h>
   47 #include <sys/ktr.h>
   48 #include <sys/limits.h>
   49 #include <sys/lock.h>
   50 #include <sys/mutex.h>
   51 #include <sys/proc.h>
   52 #include <sys/malloc.h>
   53 #include <sys/resourcevar.h>
   54 #include <sys/sched.h>
   55 #include <sys/sysctl.h>
   56 #include <sys/vnode.h>
   57 
   58 #include <vm/vm.h>
   59 #include <vm/vm_page.h>
   60 #include <vm/vm_map.h>
   61 #ifdef ZERO_COPY_SOCKETS
   62 #include <vm/vm_param.h>
   63 #include <vm/vm_object.h>
   64 #endif
   65 
   66 SYSCTL_INT(_kern, KERN_IOV_MAX, iov_max, CTLFLAG_RD, NULL, UIO_MAXIOV,
   67         "Maximum number of elements in an I/O vector; sysconf(_SC_IOV_MAX)");
   68 
   69 #ifdef ZERO_COPY_SOCKETS
   70 /* Declared in uipc_socket.c */
   71 extern int so_zero_copy_receive;
   72 
   73 static int
   74 vm_pgmoveco(vm_map_t mapa, vm_object_t srcobj, vm_offset_t kaddr,
   75     vm_offset_t uaddr)
   76 {
   77         vm_map_t map = mapa;
   78         vm_page_t kern_pg, user_pg;
   79         vm_object_t uobject;
   80         vm_map_entry_t entry;
   81         vm_pindex_t upindex, kpindex;
   82         vm_prot_t prot;
   83         boolean_t wired;
   84 
   85         /*
   86          * First lookup the kernel page.
   87          */
   88         kern_pg = PHYS_TO_VM_PAGE(vtophys(kaddr));
   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         if ((user_pg = vm_page_lookup(uobject, upindex)) != NULL) {
   96                 do
   97                         vm_page_lock_queues();
   98                 while (vm_page_sleep_if_busy(user_pg, 1, "vm_pgmoveco"));
   99                 vm_page_busy(user_pg);
  100                 pmap_remove_all(user_pg);
  101                 vm_page_free(user_pg);
  102         } else
  103                 vm_page_lock_queues();
  104         if (kern_pg->busy || ((kern_pg->queue - kern_pg->pc) == PQ_FREE) ||
  105             (kern_pg->hold_count != 0)|| (kern_pg->flags & PG_BUSY)) {
  106                 printf("vm_pgmoveco: pindex(%lu), busy(%d), PG_BUSY(%d), "
  107                        "hold(%d) paddr(0x%lx)\n", (u_long)kern_pg->pindex,
  108                         kern_pg->busy, (kern_pg->flags & PG_BUSY) ? 1 : 0,
  109                         kern_pg->hold_count, (u_long)kern_pg->phys_addr);
  110                 if ((kern_pg->queue - kern_pg->pc) == PQ_FREE)
  111                         panic("vm_pgmoveco: renaming free page");
  112                 else
  113                         panic("vm_pgmoveco: renaming busy page");
  114         }
  115         kpindex = kern_pg->pindex;
  116         vm_page_busy(kern_pg);
  117         vm_page_rename(kern_pg, uobject, upindex);
  118         vm_page_flag_clear(kern_pg, PG_BUSY);
  119         kern_pg->valid = VM_PAGE_BITS_ALL;
  120         vm_page_unlock_queues();
  121 
  122         vm_map_lookup_done(map, entry);
  123         return(KERN_SUCCESS);
  124 }
  125 #endif /* ZERO_COPY_SOCKETS */
  126 
  127 int
  128 uiomove(void *cp, int n, struct uio *uio)
  129 {
  130         struct thread *td = curthread;
  131         struct iovec *iov;
  132         u_int cnt;
  133         int error = 0;
  134         int save = 0;
  135 
  136         KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
  137             ("uiomove: mode"));
  138         KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
  139             ("uiomove proc"));
  140 
  141         if (td) {
  142                 mtx_lock_spin(&sched_lock);
  143                 save = td->td_flags & TDF_DEADLKTREAT;
  144                 td->td_flags |= TDF_DEADLKTREAT;
  145                 mtx_unlock_spin(&sched_lock);
  146         }
  147 
  148         while (n > 0 && uio->uio_resid) {
  149                 iov = uio->uio_iov;
  150                 cnt = iov->iov_len;
  151                 if (cnt == 0) {
  152                         uio->uio_iov++;
  153                         uio->uio_iovcnt--;
  154                         continue;
  155                 }
  156                 if (cnt > n)
  157                         cnt = n;
  158 
  159                 switch (uio->uio_segflg) {
  160 
  161                 case UIO_USERSPACE:
  162                         if (ticks - PCPU_GET(switchticks) >= hogticks)
  163                                 uio_yield();
  164                         if (uio->uio_rw == UIO_READ)
  165                                 error = copyout(cp, iov->iov_base, cnt);
  166                         else
  167                                 error = copyin(iov->iov_base, cp, cnt);
  168                         if (error)
  169                                 goto out;
  170                         break;
  171 
  172                 case UIO_SYSSPACE:
  173                         if (uio->uio_rw == UIO_READ)
  174                                 bcopy(cp, iov->iov_base, cnt);
  175                         else
  176                                 bcopy(iov->iov_base, cp, cnt);
  177                         break;
  178                 case UIO_NOCOPY:
  179                         break;
  180                 }
  181                 iov->iov_base = (char *)iov->iov_base + cnt;
  182                 iov->iov_len -= cnt;
  183                 uio->uio_resid -= cnt;
  184                 uio->uio_offset += cnt;
  185                 cp = (char *)cp + cnt;
  186                 n -= cnt;
  187         }
  188 out:
  189         if (td && save == 0) {
  190                 mtx_lock_spin(&sched_lock);
  191                 td->td_flags &= ~TDF_DEADLKTREAT;
  192                 mtx_unlock_spin(&sched_lock);
  193         }
  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, struct vm_object *obj,
  225     int disposable)
  226 {
  227         struct iovec *iov;
  228         int error;
  229 
  230         iov = uio->uio_iov;
  231         if (uio->uio_rw == UIO_READ) {
  232                 if ((so_zero_copy_receive != 0)
  233                  && (obj != NULL)
  234                  && ((cnt & PAGE_MASK) == 0)
  235                  && ((((intptr_t) iov->iov_base) & PAGE_MASK) == 0)
  236                  && ((uio->uio_offset & PAGE_MASK) == 0)
  237                  && ((((intptr_t) cp) & PAGE_MASK) == 0)
  238                  && (obj->type == OBJT_DEFAULT)
  239                  && (disposable != 0)) {
  240                         /* SOCKET: use page-trading */
  241                         /*
  242                          * We only want to call vm_pgmoveco() on
  243                          * disposeable pages, since it gives the
  244                          * kernel page to the userland process.
  245                          */
  246                         error = vm_pgmoveco(&curproc->p_vmspace->vm_map,
  247                                             obj, (vm_offset_t)cp,
  248                                             (vm_offset_t)iov->iov_base);
  249 
  250                         /*
  251                          * If we get an error back, attempt
  252                          * to use copyout() instead.  The
  253                          * disposable page should be freed
  254                          * automatically if we weren't able to move
  255                          * it into userland.
  256                          */
  257                         if (error != 0)
  258                                 error = copyout(cp, iov->iov_base, cnt);
  259                 } else {
  260                         error = copyout(cp, iov->iov_base, cnt);
  261                 }
  262         } else {
  263                 error = copyin(iov->iov_base, cp, cnt);
  264         }
  265         return (error);
  266 }
  267 
  268 int
  269 uiomoveco(void *cp, int n, struct uio *uio, struct vm_object *obj,
  270     int disposable)
  271 {
  272         struct iovec *iov;
  273         u_int cnt;
  274         int error;
  275 
  276         KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
  277             ("uiomoveco: mode"));
  278         KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
  279             ("uiomoveco proc"));
  280 
  281         while (n > 0 && uio->uio_resid) {
  282                 iov = uio->uio_iov;
  283                 cnt = iov->iov_len;
  284                 if (cnt == 0) {
  285                         uio->uio_iov++;
  286                         uio->uio_iovcnt--;
  287                         continue;
  288                 }
  289                 if (cnt > n)
  290                         cnt = n;
  291 
  292                 switch (uio->uio_segflg) {
  293 
  294                 case UIO_USERSPACE:
  295                         if (ticks - PCPU_GET(switchticks) >= hogticks)
  296                                 uio_yield();
  297 
  298                         error = userspaceco(cp, cnt, uio, obj, disposable);
  299 
  300                         if (error)
  301                                 return (error);
  302                         break;
  303 
  304                 case UIO_SYSSPACE:
  305                         if (uio->uio_rw == UIO_READ)
  306                                 bcopy(cp, iov->iov_base, cnt);
  307                         else
  308                                 bcopy(iov->iov_base, cp, cnt);
  309                         break;
  310                 case UIO_NOCOPY:
  311                         break;
  312                 }
  313                 iov->iov_base = (char *)iov->iov_base + cnt;
  314                 iov->iov_len -= cnt;
  315                 uio->uio_resid -= cnt;
  316                 uio->uio_offset += cnt;
  317                 cp = (char *)cp + cnt;
  318                 n -= cnt;
  319         }
  320         return (0);
  321 }
  322 #endif /* ZERO_COPY_SOCKETS */
  323 
  324 /*
  325  * Give next character to user as result of read.
  326  */
  327 int
  328 ureadc(int c, struct uio *uio)
  329 {
  330         struct iovec *iov;
  331         char *iov_base;
  332 
  333 again:
  334         if (uio->uio_iovcnt == 0 || uio->uio_resid == 0)
  335                 panic("ureadc");
  336         iov = uio->uio_iov;
  337         if (iov->iov_len == 0) {
  338                 uio->uio_iovcnt--;
  339                 uio->uio_iov++;
  340                 goto again;
  341         }
  342         switch (uio->uio_segflg) {
  343 
  344         case UIO_USERSPACE:
  345                 if (subyte(iov->iov_base, c) < 0)
  346                         return (EFAULT);
  347                 break;
  348 
  349         case UIO_SYSSPACE:
  350                 iov_base = iov->iov_base;
  351                 *iov_base = c;
  352                 iov->iov_base = iov_base;
  353                 break;
  354 
  355         case UIO_NOCOPY:
  356                 break;
  357         }
  358         iov->iov_base = (char *)iov->iov_base + 1;
  359         iov->iov_len--;
  360         uio->uio_resid--;
  361         uio->uio_offset++;
  362         return (0);
  363 }
  364 
  365 /*
  366  * General routine to allocate a hash table.
  367  */
  368 void *
  369 hashinit(int elements, struct malloc_type *type, u_long *hashmask)
  370 {
  371         long hashsize;
  372         LIST_HEAD(generic, generic) *hashtbl;
  373         int i;
  374 
  375         if (elements <= 0)
  376                 panic("hashinit: bad elements");
  377         for (hashsize = 1; hashsize <= elements; hashsize <<= 1)
  378                 continue;
  379         hashsize >>= 1;
  380         hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type, M_WAITOK);
  381         for (i = 0; i < hashsize; i++)
  382                 LIST_INIT(&hashtbl[i]);
  383         *hashmask = hashsize - 1;
  384         return (hashtbl);
  385 }
  386 
  387 void
  388 hashdestroy(void *vhashtbl, struct malloc_type *type, u_long hashmask)
  389 {
  390         LIST_HEAD(generic, generic) *hashtbl, *hp;
  391 
  392         hashtbl = vhashtbl;
  393         for (hp = hashtbl; hp <= &hashtbl[hashmask]; hp++)
  394                 if (!LIST_EMPTY(hp))
  395                         panic("hashdestroy: hash not empty");
  396         free(hashtbl, type);
  397 }
  398 
  399 static int primes[] = { 1, 13, 31, 61, 127, 251, 509, 761, 1021, 1531, 2039,
  400                         2557, 3067, 3583, 4093, 4603, 5119, 5623, 6143, 6653,
  401                         7159, 7673, 8191, 12281, 16381, 24571, 32749 };
  402 #define NPRIMES (sizeof(primes) / sizeof(primes[0]))
  403 
  404 /*
  405  * General routine to allocate a prime number sized hash table.
  406  */
  407 void *
  408 phashinit(int elements, struct malloc_type *type, u_long *nentries)
  409 {
  410         long hashsize;
  411         LIST_HEAD(generic, generic) *hashtbl;
  412         int i;
  413 
  414         if (elements <= 0)
  415                 panic("phashinit: bad elements");
  416         for (i = 1, hashsize = primes[1]; hashsize <= elements;) {
  417                 i++;
  418                 if (i == NPRIMES)
  419                         break;
  420                 hashsize = primes[i];
  421         }
  422         hashsize = primes[i - 1];
  423         hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type, M_WAITOK);
  424         for (i = 0; i < hashsize; i++)
  425                 LIST_INIT(&hashtbl[i]);
  426         *nentries = hashsize;
  427         return (hashtbl);
  428 }
  429 
  430 void
  431 uio_yield(void)
  432 {
  433         struct thread *td;
  434 
  435         td = curthread;
  436         mtx_lock_spin(&sched_lock);
  437         DROP_GIANT();
  438         sched_prio(td, td->td_ksegrp->kg_user_pri); /* XXXKSE */
  439         td->td_proc->p_stats->p_ru.ru_nivcsw++;
  440         mi_switch();
  441         mtx_unlock_spin(&sched_lock);
  442         PICKUP_GIANT();
  443 }
  444 
  445 int
  446 copyinfrom(const void *src, void *dst, size_t len, int seg)
  447 {
  448         int error = 0;
  449 
  450         switch (seg) {
  451         case UIO_USERSPACE:
  452                 error = copyin(src, dst, len);
  453                 break;
  454         case UIO_SYSSPACE:
  455                 bcopy(src, dst, len);
  456                 break;
  457         default:
  458                 panic("copyinfrom: bad seg %d\n", seg);
  459         }
  460         return (error);
  461 }
  462 
  463 int
  464 copyinstrfrom(const void *src, void *dst, size_t len, size_t *copied, int seg)
  465 {
  466         int error = 0;
  467 
  468         switch (seg) {
  469         case UIO_USERSPACE:
  470                 error = copyinstr(src, dst, len, copied);
  471                 break;
  472         case UIO_SYSSPACE:
  473                 error = copystr(src, dst, len, copied);
  474                 break;
  475         default:
  476                 panic("copyinstrfrom: bad seg %d\n", seg);
  477         }
  478         return (error);
  479 }
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FreeBSD/Linux Kernel Cross Reference sys/kern/kern_subr.c

FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_subr.c
