xref: /src/sys/uvm/uvm_io.c

/*	$Id: uvm_io.c,v 1.1 1998/02/05 06:25:10 mrg Exp $	*/

/*
 * XXXCDC: "ROUGH DRAFT" QUALITY UVM PRE-RELEASE FILE!
 *	   >>>USE AT YOUR OWN RISK, WORK IS NOT FINISHED<<<
 */
/*
 *
 * Copyright (c) 1997 Charles D. Cranor and Washington University.
 * All rights reserved.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Charles D. Cranor and
 *      Washington University.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

/*
 * uvm_io.c: uvm i/o ops
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mount.h>
#include <sys/mman.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/uio.h>

#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/vm_kern.h>

#include <sys/syscallargs.h>

#include <uvm/uvm.h>

/*
 * functions
 */

/*
 * uvm_io: perform I/O on a map
 *
 * => caller must have a reference to "map" so that it doesn't go away
 *    while we are working.
 */

int uvm_io(map, uio)

vm_map_t map;
struct uio *uio;

{
  vm_offset_t baseva, endva, pageoffset, kva;
  vm_size_t chunksz, togo, sz;
  vm_map_entry_t dead_entries;
  int error;

  /*
   * step 0: sanity checks and set up for copy loop.  start with a
   * large chunk size.  if we have trouble finding vm space we will
   * reduce it.
   */

  if (uio->uio_resid == 0)
    return(0);
  togo = uio->uio_resid;

  baseva = (vm_offset_t) uio->uio_offset;
  endva = baseva + (togo - 1);

  if (endva < baseva)   /* wrap around? */
    return(EIO);

  if (baseva >= VM_MAXUSER_ADDRESS)
    return(0);
  if (endva >= VM_MAXUSER_ADDRESS)
    togo = togo - (endva - VM_MAXUSER_ADDRESS + 1); /* EOF truncate */
  pageoffset = baseva & PAGE_MASK;
  baseva = trunc_page(baseva);
  chunksz = min(round_page(togo + pageoffset), MAXBSIZE);
  error = 0;

  /*
   * step 1: main loop...  while we've got data to move
   */

  for (/*null*/; togo > 0 ; pageoffset = 0) {

    /*
     * step 2: extract mappings from the map into kernel_map
     */

    error = uvm_map_extract(map, baseva, chunksz, kernel_map, &kva,
			    UVM_EXTRACT_QREF | UVM_EXTRACT_CONTIG |
			    UVM_EXTRACT_FIXPROT);
    if (error) {

      /* retry with a smaller chunk... */
      if (error == ENOMEM && chunksz > PAGE_SIZE) {
	chunksz = trunc_page(chunksz / 2);
	if (chunksz < PAGE_SIZE)
	  chunksz = PAGE_SIZE;
	continue;
      }

      break;
    }

    /*
     * step 3: move a chunk of data
     */

    sz = chunksz - pageoffset;
    if (sz > togo)
      sz = togo;
    error = uiomove((caddr_t) (kva + pageoffset), sz, uio);
    if (error)
      break;
    togo -= sz;
    baseva += chunksz;


    /*
     * step 4: unmap the area of kernel memory
     */

    vm_map_lock(kernel_map);
    (void) uvm_unmap_remove(kernel_map, kva, kva+chunksz, 1, &dead_entries);
    vm_map_unlock(kernel_map);

    if (dead_entries != NULL)
      uvm_unmap_detach(dead_entries, AMAP_REFALL);

  }

  /*
   * done
   */

  return(error);
}