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uvm_io.c revision 1.2 
      1 /*	$NetBSD: uvm_io.c,v 1.2 1998/02/06 22:31:53 thorpej Exp $	*/
      2 
      3 /*
      4  * XXXCDC: "ROUGH DRAFT" QUALITY UVM PRE-RELEASE FILE!
      5  *	   >>>USE AT YOUR OWN RISK, WORK IS NOT FINISHED<<<
      6  */
      7 /*
      8  *
      9  * Copyright (c) 1997 Charles D. Cranor and Washington University.
     10  * All rights reserved.
     11  *
     12  * Redistribution and use in source and binary forms, with or without
     13  * modification, are permitted provided that the following conditions
     14  * are met:
     15  * 1. Redistributions of source code must retain the above copyright
     16  *    notice, this list of conditions and the following disclaimer.
     17  * 2. Redistributions in binary form must reproduce the above copyright
     18  *    notice, this list of conditions and the following disclaimer in the
     19  *    documentation and/or other materials provided with the distribution.
     20  * 3. All advertising materials mentioning features or use of this software
     21  *    must display the following acknowledgement:
     22  *      This product includes software developed by Charles D. Cranor and
     23  *      Washington University.
     24  * 4. The name of the author may not be used to endorse or promote products
     25  *    derived from this software without specific prior written permission.
     26  *
     27  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     28  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     29  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     30  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     31  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     32  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     33  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     34  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     35  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     36  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     37  */
     38 
     39 /*
     40  * uvm_io.c: uvm i/o ops
     41  */
     42 
     43 #include <sys/param.h>
     44 #include <sys/systm.h>
     45 #include <sys/mount.h>
     46 #include <sys/mman.h>
     47 #include <sys/proc.h>
     48 #include <sys/malloc.h>
     49 #include <sys/uio.h>
     50 
     51 #include <vm/vm.h>
     52 #include <vm/vm_page.h>
     53 #include <vm/vm_kern.h>
     54 
     55 #include <sys/syscallargs.h>
     56 
     57 #include <uvm/uvm.h>
     58 
     59 /*
     60  * functions
     61  */
     62 
     63 /*
     64  * uvm_io: perform I/O on a map
     65  *
     66  * => caller must have a reference to "map" so that it doesn't go away
     67  *    while we are working.
     68  */
     69 
     70 int uvm_io(map, uio)
     71 
     72 vm_map_t map;
     73 struct uio *uio;
     74 
     75 {
     76   vm_offset_t baseva, endva, pageoffset, kva;
     77   vm_size_t chunksz, togo, sz;
     78   vm_map_entry_t dead_entries;
     79   int error;
     80 
     81   /*
     82    * step 0: sanity checks and set up for copy loop.  start with a
     83    * large chunk size.  if we have trouble finding vm space we will
     84    * reduce it.
     85    */
     86 
     87   if (uio->uio_resid == 0)
     88     return(0);
     89   togo = uio->uio_resid;
     90 
     91   baseva = (vm_offset_t) uio->uio_offset;
     92   endva = baseva + (togo - 1);
     93 
     94   if (endva < baseva)   /* wrap around? */
     95     return(EIO);
     96 
     97   if (baseva >= VM_MAXUSER_ADDRESS)
     98     return(0);
     99   if (endva >= VM_MAXUSER_ADDRESS)
    100     togo = togo - (endva - VM_MAXUSER_ADDRESS + 1); /* EOF truncate */
    101   pageoffset = baseva & PAGE_MASK;
    102   baseva = trunc_page(baseva);
    103   chunksz = min(round_page(togo + pageoffset), MAXBSIZE);
    104   error = 0;
    105 
    106   /*
    107    * step 1: main loop...  while we've got data to move
    108    */
    109 
    110   for (/*null*/; togo > 0 ; pageoffset = 0) {
    111 
    112     /*
    113      * step 2: extract mappings from the map into kernel_map
    114      */
    115 
    116     error = uvm_map_extract(map, baseva, chunksz, kernel_map, &kva,
    117 			    UVM_EXTRACT_QREF | UVM_EXTRACT_CONTIG |
    118 			    UVM_EXTRACT_FIXPROT);
    119     if (error) {
    120 
    121       /* retry with a smaller chunk... */
    122       if (error == ENOMEM && chunksz > PAGE_SIZE) {
    123 	chunksz = trunc_page(chunksz / 2);
    124 	if (chunksz < PAGE_SIZE)
    125 	  chunksz = PAGE_SIZE;
    126 	continue;
    127       }
    128 
    129       break;
    130     }
    131 
    132     /*
    133      * step 3: move a chunk of data
    134      */
    135 
    136     sz = chunksz - pageoffset;
    137     if (sz > togo)
    138       sz = togo;
    139     error = uiomove((caddr_t) (kva + pageoffset), sz, uio);
    140     if (error)
    141       break;
    142     togo -= sz;
    143     baseva += chunksz;
    144 
    145 
    146     /*
    147      * step 4: unmap the area of kernel memory
    148      */
    149 
    150     vm_map_lock(kernel_map);
    151     (void) uvm_unmap_remove(kernel_map, kva, kva+chunksz, 1, &dead_entries);
    152     vm_map_unlock(kernel_map);
    153 
    154     if (dead_entries != NULL)
    155       uvm_unmap_detach(dead_entries, AMAP_REFALL);
    156 
    157   }
    158 
    159   /*
    160    * done
    161    */
    162 
    163   return(error);
    164 }
    165