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uvm_io.c revision 1.3 
      1 /*	$NetBSD: uvm_io.c,v 1.3 1998/02/07 11:08:43 mrg 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  * from: Id: uvm_io.c,v 1.1.2.2 1997/12/30 12:02:00 mrg Exp
     39  */
     40 
     41 /*
     42  * uvm_io.c: uvm i/o ops
     43  */
     44 
     45 #include <sys/param.h>
     46 #include <sys/systm.h>
     47 #include <sys/mount.h>
     48 #include <sys/mman.h>
     49 #include <sys/proc.h>
     50 #include <sys/malloc.h>
     51 #include <sys/uio.h>
     52 
     53 #include <vm/vm.h>
     54 #include <vm/vm_page.h>
     55 #include <vm/vm_kern.h>
     56 
     57 #include <sys/syscallargs.h>
     58 
     59 #include <uvm/uvm.h>
     60 
     61 /*
     62  * functions
     63  */
     64 
     65 /*
     66  * uvm_io: perform I/O on a map
     67  *
     68  * => caller must have a reference to "map" so that it doesn't go away
     69  *    while we are working.
     70  */
     71 
     72 int uvm_io(map, uio)
     73 
     74 vm_map_t map;
     75 struct uio *uio;
     76 
     77 {
     78   vm_offset_t baseva, endva, pageoffset, kva;
     79   vm_size_t chunksz, togo, sz;
     80   vm_map_entry_t dead_entries;
     81   int error;
     82 
     83   /*
     84    * step 0: sanity checks and set up for copy loop.  start with a
     85    * large chunk size.  if we have trouble finding vm space we will
     86    * reduce it.
     87    */
     88 
     89   if (uio->uio_resid == 0)
     90     return(0);
     91   togo = uio->uio_resid;
     92 
     93   baseva = (vm_offset_t) uio->uio_offset;
     94   endva = baseva + (togo - 1);
     95 
     96   if (endva < baseva)   /* wrap around? */
     97     return(EIO);
     98 
     99   if (baseva >= VM_MAXUSER_ADDRESS)
    100     return(0);
    101   if (endva >= VM_MAXUSER_ADDRESS)
    102     togo = togo - (endva - VM_MAXUSER_ADDRESS + 1); /* EOF truncate */
    103   pageoffset = baseva & PAGE_MASK;
    104   baseva = trunc_page(baseva);
    105   chunksz = min(round_page(togo + pageoffset), MAXBSIZE);
    106   error = 0;
    107 
    108   /*
    109    * step 1: main loop...  while we've got data to move
    110    */
    111 
    112   for (/*null*/; togo > 0 ; pageoffset = 0) {
    113 
    114     /*
    115      * step 2: extract mappings from the map into kernel_map
    116      */
    117 
    118     error = uvm_map_extract(map, baseva, chunksz, kernel_map, &kva,
    119 			    UVM_EXTRACT_QREF | UVM_EXTRACT_CONTIG |
    120 			    UVM_EXTRACT_FIXPROT);
    121     if (error) {
    122 
    123       /* retry with a smaller chunk... */
    124       if (error == ENOMEM && chunksz > PAGE_SIZE) {
    125 	chunksz = trunc_page(chunksz / 2);
    126 	if (chunksz < PAGE_SIZE)
    127 	  chunksz = PAGE_SIZE;
    128 	continue;
    129       }
    130 
    131       break;
    132     }
    133 
    134     /*
    135      * step 3: move a chunk of data
    136      */
    137 
    138     sz = chunksz - pageoffset;
    139     if (sz > togo)
    140       sz = togo;
    141     error = uiomove((caddr_t) (kva + pageoffset), sz, uio);
    142     if (error)
    143       break;
    144     togo -= sz;
    145     baseva += chunksz;
    146 
    147 
    148     /*
    149      * step 4: unmap the area of kernel memory
    150      */
    151 
    152     vm_map_lock(kernel_map);
    153     (void) uvm_unmap_remove(kernel_map, kva, kva+chunksz, 1, &dead_entries);
    154     vm_map_unlock(kernel_map);
    155 
    156     if (dead_entries != NULL)
    157       uvm_unmap_detach(dead_entries, AMAP_REFALL);
    158 
    159   }
    160 
    161   /*
    162    * done
    163    */
    164 
    165   return(error);
    166 }
    167