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/i386/i386/uio_machdep.c

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    1 /*-
    2  * Copyright (c) 2004 Alan L. Cox <alc@cs.rice.edu>
    3  * Copyright (c) 1982, 1986, 1991, 1993
    4  *      The Regents of the University of California.  All rights reserved.
    5  * (c) UNIX System Laboratories, Inc.
    6  * All or some portions of this file are derived from material licensed
    7  * to the University of California by American Telephone and Telegraph
    8  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
    9  * the permission of UNIX System Laboratories, Inc.
   10  *
   11  * Redistribution and use in source and binary forms, with or without
   12  * modification, are permitted provided that the following conditions
   13  * are met:
   14  * 1. Redistributions of source code must retain the above copyright
   15  *    notice, this list of conditions and the following disclaimer.
   16  * 2. Redistributions in binary form must reproduce the above copyright
   17  *    notice, this list of conditions and the following disclaimer in the
   18  *    documentation and/or other materials provided with the distribution.
   19  * 4. Neither the name of the University nor the names of its contributors
   20  *    may be used to endorse or promote products derived from this software
   21  *    without specific prior written permission.
   22  *
   23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   33  * SUCH DAMAGE.
   34  *
   35  *      @(#)kern_subr.c 8.3 (Berkeley) 1/21/94
   36  */
   37 
   38 #include <sys/cdefs.h>
   39 __FBSDID("$FreeBSD: releng/9.0/sys/i386/i386/uio_machdep.c 218195 2011-02-02 16:35:10Z mdf $");
   40 
   41 #include <sys/param.h>
   42 #include <sys/kernel.h>
   43 #include <sys/lock.h>
   44 #include <sys/mutex.h>
   45 #include <sys/proc.h>
   46 #include <sys/sched.h>
   47 #include <sys/sf_buf.h>
   48 #include <sys/systm.h>
   49 #include <sys/uio.h>
   50 
   51 #include <vm/vm.h>
   52 #include <vm/vm_page.h>
   53 
   54 /*
   55  * Implement uiomove(9) from physical memory using sf_bufs to reduce
   56  * the creation and destruction of ephemeral mappings.
   57  */
   58 int
   59 uiomove_fromphys(vm_page_t ma[], vm_offset_t offset, int n, struct uio *uio)
   60 {
   61         struct sf_buf *sf;
   62         struct thread *td = curthread;
   63         struct iovec *iov;
   64         void *cp;
   65         vm_offset_t page_offset;
   66         size_t cnt;
   67         int error = 0;
   68         int save = 0;
   69 
   70         KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
   71             ("uiomove_fromphys: mode"));
   72         KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
   73             ("uiomove_fromphys proc"));
   74         save = td->td_pflags & TDP_DEADLKTREAT;
   75         td->td_pflags |= TDP_DEADLKTREAT;
   76         while (n > 0 && uio->uio_resid) {
   77                 iov = uio->uio_iov;
   78                 cnt = iov->iov_len;
   79                 if (cnt == 0) {
   80                         uio->uio_iov++;
   81                         uio->uio_iovcnt--;
   82                         continue;
   83                 }
   84                 if (cnt > n)
   85                         cnt = n;
   86                 page_offset = offset & PAGE_MASK;
   87                 cnt = min(cnt, PAGE_SIZE - page_offset);
   88                 sched_pin();
   89                 sf = sf_buf_alloc(ma[offset >> PAGE_SHIFT], SFB_CPUPRIVATE);
   90                 cp = (char *)sf_buf_kva(sf) + page_offset;
   91                 switch (uio->uio_segflg) {
   92                 case UIO_USERSPACE:
   93                         maybe_yield();
   94                         if (uio->uio_rw == UIO_READ)
   95                                 error = copyout(cp, iov->iov_base, cnt);
   96                         else
   97                                 error = copyin(iov->iov_base, cp, cnt);
   98                         if (error) {
   99                                 sf_buf_free(sf);
  100                                 sched_unpin();
  101                                 goto out;
  102                         }
  103                         break;
  104                 case UIO_SYSSPACE:
  105                         if (uio->uio_rw == UIO_READ)
  106                                 bcopy(cp, iov->iov_base, cnt);
  107                         else
  108                                 bcopy(iov->iov_base, cp, cnt);
  109                         break;
  110                 case UIO_NOCOPY:
  111                         break;
  112                 }
  113                 sf_buf_free(sf);
  114                 sched_unpin();
  115                 iov->iov_base = (char *)iov->iov_base + cnt;
  116                 iov->iov_len -= cnt;
  117                 uio->uio_resid -= cnt;
  118                 uio->uio_offset += cnt;
  119                 offset += cnt;
  120                 n -= cnt;
  121         }
  122 out:
  123         if (save == 0)
  124                 td->td_pflags &= ~TDP_DEADLKTREAT;
  125         return (error);
  126 }

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