FreeBSD/Linux Kernel Cross Reference
sys/i386/i386/uio_machdep.c

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * Copyright (c) 2004 Alan L. Cox <alc@cs.rice.edu>
      * Copyright (c) 1982, 1986, 1991, 1993
      *      The Regents of the University of California.  All rights reserved.
      * (c) UNIX System Laboratories, Inc.
      * All or some portions of this file are derived from material licensed
      * to the University of California by American Telephone and Telegraph
     * Co. or Unix System Laboratories, Inc. and are reproduced herein with
     * the permission of UNIX System Laboratories, Inc.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)kern_subr.c 8.3 (Berkeley) 1/21/94
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/kernel.h>
    #include <sys/lock.h>
    #include <sys/mutex.h>
    #include <sys/proc.h>
    #include <sys/sched.h>
    #include <sys/sf_buf.h>
    #include <sys/uio.h>
    
    #include <vm/vm.h>
    #include <vm/vm_page.h>
    
    /*
     * Implement uiomove(9) from physical memory using sf_bufs to reduce
     * the creation and destruction of ephemeral mappings.
     */
    int
    uiomove_fromphys(vm_page_t ma[], vm_offset_t offset, int n, struct uio *uio)
    {
            struct sf_buf *sf;
            struct thread *td = curthread;
            struct iovec *iov;
            void *cp;
            vm_offset_t page_offset;
            size_t cnt;
            int error = 0;
            int save = 0;
    
            KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
                ("uiomove_fromphys: mode"));
            KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
                ("uiomove_fromphys proc"));
            save = td->td_pflags & TDP_DEADLKTREAT;
            td->td_pflags |= TDP_DEADLKTREAT;
            while (n > 0 && uio->uio_resid) {
                    iov = uio->uio_iov;
                    cnt = iov->iov_len;
                    if (cnt == 0) {
                            uio->uio_iov++;
                            uio->uio_iovcnt--;
                            continue;
                    }
                    if (cnt > n)
                            cnt = n;
                    page_offset = offset & PAGE_MASK;
                    cnt = min(cnt, PAGE_SIZE - page_offset);
                    sched_pin();
                    sf = sf_buf_alloc(ma[offset >> PAGE_SHIFT], SFB_CPUPRIVATE);
                    cp = (char *)sf_buf_kva(sf) + page_offset;
                    switch (uio->uio_segflg) {
                    case UIO_USERSPACE:
                            maybe_yield();
                            if (uio->uio_rw == UIO_READ)
                                    error = copyout(cp, iov->iov_base, cnt);
                            else
                                    error = copyin(iov->iov_base, cp, cnt);
                           if (error) {
                                   sf_buf_free(sf);
                                   sched_unpin();
                                   goto out;
                           }
                           break;
                   case UIO_SYSSPACE:
                           if (uio->uio_rw == UIO_READ)
                                   bcopy(cp, iov->iov_base, cnt);
                           else
                                   bcopy(iov->iov_base, cp, cnt);
                           break;
                   case UIO_NOCOPY:
                           break;
                   }
                   sf_buf_free(sf);
                   sched_unpin();
                   iov->iov_base = (char *)iov->iov_base + cnt;
                   iov->iov_len -= cnt;
                   uio->uio_resid -= cnt;
                   uio->uio_offset += cnt;
                   offset += cnt;
                   n -= cnt;
           }
   out:
           if (save == 0)
                   td->td_pflags &= ~TDP_DEADLKTREAT;
           return (error);
   }

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