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/8.2/sys/kern/kern_subr.c 199583 2009-11-20 15:27:52Z jhb $");
   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                 if (vm_page_sleep_if_busy(user_pg, TRUE, "vm_pgmoveco"))
  109                         goto retry;
  110                 vm_page_lock_queues();
  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         WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
  329             "Calling ureadc()");
  330 
  331 again:
  332         if (uio->uio_iovcnt == 0 || uio->uio_resid == 0)
  333                 panic("ureadc");
  334         iov = uio->uio_iov;
  335         if (iov->iov_len == 0) {
  336                 uio->uio_iovcnt--;
  337                 uio->uio_iov++;
  338                 goto again;
  339         }
  340         switch (uio->uio_segflg) {
  341 
  342         case UIO_USERSPACE:
  343                 if (subyte(iov->iov_base, c) < 0)
  344                         return (EFAULT);
  345                 break;
  346 
  347         case UIO_SYSSPACE:
  348                 iov_base = iov->iov_base;
  349                 *iov_base = c;
  350                 iov->iov_base = iov_base;
  351                 break;
  352 
  353         case UIO_NOCOPY:
  354                 break;
  355         }
  356         iov->iov_base = (char *)iov->iov_base + 1;
  357         iov->iov_len--;
  358         uio->uio_resid--;
  359         uio->uio_offset++;
  360         return (0);
  361 }
  362 
  363 /*
  364  * General routine to allocate a hash table with control of memory flags.
  365  */
  366 void *
  367 hashinit_flags(int elements, struct malloc_type *type, u_long *hashmask,
  368     int flags)
  369 {
  370         long hashsize;
  371         LIST_HEAD(generic, generic) *hashtbl;
  372         int i;
  373 
  374         if (elements <= 0)
  375                 panic("hashinit: bad elements");
  376 
  377         /* Exactly one of HASH_WAITOK and HASH_NOWAIT must be set. */
  378         KASSERT((flags & HASH_WAITOK) ^ (flags & HASH_NOWAIT),
  379             ("Bad flags (0x%x) passed to hashinit_flags", flags));
  380 
  381         for (hashsize = 1; hashsize <= elements; hashsize <<= 1)
  382                 continue;
  383         hashsize >>= 1;
  384 
  385         if (flags & HASH_NOWAIT)
  386                 hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl),
  387                     type, M_NOWAIT);
  388         else
  389                 hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl),
  390                     type, M_WAITOK);
  391 
  392         if (hashtbl != NULL) {
  393                 for (i = 0; i < hashsize; i++)
  394                         LIST_INIT(&hashtbl[i]);
  395                 *hashmask = hashsize - 1;
  396         }
  397         return (hashtbl);
  398 }
  399 
  400 /*
  401  * Allocate and initialize a hash table with default flag: may sleep.
  402  */
  403 void *
  404 hashinit(int elements, struct malloc_type *type, u_long *hashmask)
  405 {
  406 
  407         return (hashinit_flags(elements, type, hashmask, HASH_WAITOK));
  408 }
  409 
  410 void
  411 hashdestroy(void *vhashtbl, struct malloc_type *type, u_long hashmask)
  412 {
  413         LIST_HEAD(generic, generic) *hashtbl, *hp;
  414 
  415         hashtbl = vhashtbl;
  416         for (hp = hashtbl; hp <= &hashtbl[hashmask]; hp++)
  417                 if (!LIST_EMPTY(hp))
  418                         panic("hashdestroy: hash not empty");
  419         free(hashtbl, type);
  420 }
  421 
  422 static int primes[] = { 1, 13, 31, 61, 127, 251, 509, 761, 1021, 1531, 2039,
  423                         2557, 3067, 3583, 4093, 4603, 5119, 5623, 6143, 6653,
  424                         7159, 7673, 8191, 12281, 16381, 24571, 32749 };
  425 #define NPRIMES (sizeof(primes) / sizeof(primes[0]))
  426 
  427 /*
  428  * General routine to allocate a prime number sized hash table.
  429  */
  430 void *
  431 phashinit(int elements, struct malloc_type *type, u_long *nentries)
  432 {
  433         long hashsize;
  434         LIST_HEAD(generic, generic) *hashtbl;
  435         int i;
  436 
  437         if (elements <= 0)
  438                 panic("phashinit: bad elements");
  439         for (i = 1, hashsize = primes[1]; hashsize <= elements;) {
  440                 i++;
  441                 if (i == NPRIMES)
  442                         break;
  443                 hashsize = primes[i];
  444         }
  445         hashsize = primes[i - 1];
  446         hashtbl = malloc((u_long)hashsize * sizeof(*hashtbl), type, M_WAITOK);
  447         for (i = 0; i < hashsize; i++)
  448                 LIST_INIT(&hashtbl[i]);
  449         *nentries = hashsize;
  450         return (hashtbl);
  451 }
  452 
  453 void
  454 uio_yield(void)
  455 {
  456         struct thread *td;
  457 
  458         td = curthread;
  459         DROP_GIANT();
  460         thread_lock(td);
  461         sched_prio(td, td->td_user_pri);
  462         mi_switch(SW_INVOL | SWT_RELINQUISH, NULL);
  463         thread_unlock(td);
  464         PICKUP_GIANT();
  465 }
  466 
  467 int
  468 copyinfrom(const void * __restrict src, void * __restrict dst, size_t len,
  469     int seg)
  470 {
  471         int error = 0;
  472 
  473         switch (seg) {
  474         case UIO_USERSPACE:
  475                 error = copyin(src, dst, len);
  476                 break;
  477         case UIO_SYSSPACE:
  478                 bcopy(src, dst, len);
  479                 break;
  480         default:
  481                 panic("copyinfrom: bad seg %d\n", seg);
  482         }
  483         return (error);
  484 }
  485 
  486 int
  487 copyinstrfrom(const void * __restrict src, void * __restrict dst, size_t len,
  488     size_t * __restrict copied, int seg)
  489 {
  490         int error = 0;
  491 
  492         switch (seg) {
  493         case UIO_USERSPACE:
  494                 error = copyinstr(src, dst, len, copied);
  495                 break;
  496         case UIO_SYSSPACE:
  497                 error = copystr(src, dst, len, copied);
  498                 break;
  499         default:
  500                 panic("copyinstrfrom: bad seg %d\n", seg);
  501         }
  502         return (error);
  503 }
  504 
  505 int
  506 copyiniov(struct iovec *iovp, u_int iovcnt, struct iovec **iov, int error)
  507 {
  508         u_int iovlen;
  509 
  510         *iov = NULL;
  511         if (iovcnt > UIO_MAXIOV)
  512                 return (error);
  513         iovlen = iovcnt * sizeof (struct iovec);
  514         *iov = malloc(iovlen, M_IOV, M_WAITOK);
  515         error = copyin(iovp, *iov, iovlen);
  516         if (error) {
  517                 free(*iov, M_IOV);
  518                 *iov = NULL;
  519         }
  520         return (error);
  521 }
  522 
  523 int
  524 copyinuio(struct iovec *iovp, u_int iovcnt, struct uio **uiop)
  525 {
  526         struct iovec *iov;
  527         struct uio *uio;
  528         u_int iovlen;
  529         int error, i;
  530 
  531         *uiop = NULL;
  532         if (iovcnt > UIO_MAXIOV)
  533                 return (EINVAL);
  534         iovlen = iovcnt * sizeof (struct iovec);
  535         uio = malloc(iovlen + sizeof *uio, M_IOV, M_WAITOK);
  536         iov = (struct iovec *)(uio + 1);
  537         error = copyin(iovp, iov, iovlen);
  538         if (error) {
  539                 free(uio, M_IOV);
  540                 return (error);
  541         }
  542         uio->uio_iov = iov;
  543         uio->uio_iovcnt = iovcnt;
  544         uio->uio_segflg = UIO_USERSPACE;
  545         uio->uio_offset = -1;
  546         uio->uio_resid = 0;
  547         for (i = 0; i < iovcnt; i++) {
  548                 if (iov->iov_len > INT_MAX - uio->uio_resid) {
  549                         free(uio, M_IOV);
  550                         return (EINVAL);
  551                 }
  552                 uio->uio_resid += iov->iov_len;
  553                 iov++;
  554         }
  555         *uiop = uio;
  556         return (0);
  557 }
  558 
  559 struct uio *
  560 cloneuio(struct uio *uiop)
  561 {
  562         struct uio *uio;
  563         int iovlen;
  564 
  565         iovlen = uiop->uio_iovcnt * sizeof (struct iovec);
  566         uio = malloc(iovlen + sizeof *uio, M_IOV, M_WAITOK);
  567         *uio = *uiop;
  568         uio->uio_iov = (struct iovec *)(uio + 1);
  569         bcopy(uiop->uio_iov, uio->uio_iov, iovlen);
  570         return (uio);
  571 }
Cache object: 8ba69b561e23f0dd0fa8d7610a10cecb
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FreeBSD/Linux Kernel Cross Reference sys/kern/kern_subr.c

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