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/amd64/amd64/uio_machdep.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-3-Clause
    3  *
    4  * Copyright (c) 2004 Alan L. Cox <alc@cs.rice.edu>
    5  * Copyright (c) 1982, 1986, 1991, 1993
    6  *      The Regents of the University of California.  All rights reserved.
    7  * (c) UNIX System Laboratories, Inc.
    8  * All or some portions of this file are derived from material licensed
    9  * to the University of California by American Telephone and Telegraph
   10  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
   11  * the permission of UNIX System Laboratories, Inc.
   12  *
   13  * Redistribution and use in source and binary forms, with or without
   14  * modification, are permitted provided that the following conditions
   15  * are met:
   16  * 1. Redistributions of source code must retain the above copyright
   17  *    notice, this list of conditions and the following disclaimer.
   18  * 2. Redistributions in binary form must reproduce the above copyright
   19  *    notice, this list of conditions and the following disclaimer in the
   20  *    documentation and/or other materials provided with the distribution.
   21  * 3. Neither the name of the University nor the names of its contributors
   22  *    may be used to endorse or promote products derived from this software
   23  *    without specific prior written permission.
   24  *
   25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   35  * SUCH DAMAGE.
   36  *
   37  *      @(#)kern_subr.c 8.3 (Berkeley) 1/21/94
   38  */
   39 
   40 #include <sys/cdefs.h>
   41 __FBSDID("$FreeBSD: releng/12.0/sys/amd64/amd64/uio_machdep.c 326023 2017-11-20 19:43:44Z pfg $");
   42 
   43 #include <sys/param.h>
   44 #include <sys/kernel.h>
   45 #include <sys/lock.h>
   46 #include <sys/mutex.h>
   47 #include <sys/proc.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 #include <machine/vmparam.h>
   55 
   56 /*
   57  * Implement uiomove(9) from physical memory using the direct map to
   58  * avoid the creation and destruction of ephemeral mappings.
   59  */
   60 int
   61 uiomove_fromphys(vm_page_t ma[], vm_offset_t offset, int n, struct uio *uio)
   62 {
   63         struct thread *td = curthread;
   64         struct iovec *iov;
   65         void *cp;
   66         vm_offset_t page_offset, vaddr;
   67         size_t cnt;
   68         int error = 0;
   69         int save = 0;
   70         boolean_t mapped;
   71 
   72         KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
   73             ("uiomove_fromphys: mode"));
   74         KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
   75             ("uiomove_fromphys proc"));
   76         save = td->td_pflags & TDP_DEADLKTREAT;
   77         td->td_pflags |= TDP_DEADLKTREAT;
   78         mapped = FALSE;
   79         while (n > 0 && uio->uio_resid) {
   80                 iov = uio->uio_iov;
   81                 cnt = iov->iov_len;
   82                 if (cnt == 0) {
   83                         uio->uio_iov++;
   84                         uio->uio_iovcnt--;
   85                         continue;
   86                 }
   87                 if (cnt > n)
   88                         cnt = n;
   89                 page_offset = offset & PAGE_MASK;
   90                 cnt = min(cnt, PAGE_SIZE - page_offset);
   91                 if (uio->uio_segflg != UIO_NOCOPY) {
   92                         mapped = pmap_map_io_transient(
   93                             &ma[offset >> PAGE_SHIFT], &vaddr, 1, TRUE);
   94                         cp = (char *)vaddr + page_offset;
   95                 }
   96                 switch (uio->uio_segflg) {
   97                 case UIO_USERSPACE:
   98                         maybe_yield();
   99                         if (uio->uio_rw == UIO_READ)
  100                                 error = copyout(cp, iov->iov_base, cnt);
  101                         else
  102                                 error = copyin(iov->iov_base, cp, cnt);
  103                         if (error)
  104                                 goto out;
  105                         break;
  106                 case UIO_SYSSPACE:
  107                         if (uio->uio_rw == UIO_READ)
  108                                 bcopy(cp, iov->iov_base, cnt);
  109                         else
  110                                 bcopy(iov->iov_base, cp, cnt);
  111                         break;
  112                 case UIO_NOCOPY:
  113                         break;
  114                 }
  115                 if (__predict_false(mapped)) {
  116                         pmap_unmap_io_transient(&ma[offset >> PAGE_SHIFT],
  117                             &vaddr, 1, TRUE);
  118                         mapped = FALSE;
  119                 }
  120                 iov->iov_base = (char *)iov->iov_base + cnt;
  121                 iov->iov_len -= cnt;
  122                 uio->uio_resid -= cnt;
  123                 uio->uio_offset += cnt;
  124                 offset += cnt;
  125                 n -= cnt;
  126         }
  127 out:
  128         if (__predict_false(mapped))
  129                 pmap_unmap_io_transient(&ma[offset >> PAGE_SHIFT], &vaddr, 1,
  130                     TRUE);
  131         if (save == 0)
  132                 td->td_pflags &= ~TDP_DEADLKTREAT;
  133         return (error);
  134 }

Cache object: 242fa494b93df205f374ebe6d808ddd6


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