sys/uvm/uvm_io.c

   1 /*      $NetBSD: uvm_io.c,v 1.23 2005/12/20 08:25:58 skrll Exp $        */
   2
   3 /*
   4  *
   5  * Copyright (c) 1997 Charles D. Cranor and Washington University.
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by Charles D. Cranor and
  19  *      Washington University.
  20  * 4. The name of the author may not be used to endorse or promote products
  21  *    derived from this software without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  24  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  25  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  26  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  27  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  28  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  29  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  30  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  31  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  32  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  33  *
  34  * from: Id: uvm_io.c,v 1.1.2.2 1997/12/30 12:02:00 mrg Exp
  35  */
  36
  37 /*
  38  * uvm_io.c: uvm i/o ops
  39  */
  40
  41 #include <sys/cdefs.h>
  42 __KERNEL_RCSID(0, "$NetBSD: uvm_io.c,v 1.23 2005/12/20 08:25:58 skrll Exp $");
  43
  44 #include <sys/param.h>
  45 #include <sys/systm.h>
  46 #include <sys/mman.h>
  47 #include <sys/proc.h>
  48 #include <sys/malloc.h>
  49 #include <sys/uio.h>
  50
  51 #include <uvm/uvm.h>
  52
  53 /*
  54  * functions
  55  */
  56
  57 /*
  58  * uvm_io: perform I/O on a map
  59  *
  60  * => caller must have a reference to "map" so that it doesn't go away
  61  *    while we are working.
  62  */
  63
  64 int
  65 uvm_io(struct vm_map *map, struct uio *uio)
  66 {
  67         vaddr_t baseva, endva, pageoffset, kva;
  68         vsize_t chunksz, togo, sz;
  69         struct vm_map_entry *dead_entries;
  70         int error;
  71
  72         /*
  73          * step 0: sanity checks and set up for copy loop.  start with a
  74          * large chunk size.  if we have trouble finding vm space we will
  75          * reduce it.
  76          */
  77
  78         if (uio->uio_resid == 0)
  79                 return(0);
  80         togo = uio->uio_resid;
  81
  82         baseva = (vaddr_t) uio->uio_offset;
  83         endva = baseva + (togo - 1);
  84
  85         if (endva < baseva)   /* wrap around? */
  86                 return(EIO);
  87
  88         if (baseva >= VM_MAXUSER_ADDRESS)
  89                 return(0);
  90         if (endva >= VM_MAXUSER_ADDRESS)
  91                 /* EOF truncate */
  92                 togo = togo - (endva - VM_MAXUSER_ADDRESS + 1);
  93         pageoffset = baseva & PAGE_MASK;
  94         baseva = trunc_page(baseva);
  95         chunksz = MIN(round_page(togo + pageoffset), trunc_page(MAXPHYS));
  96         error = 0;
  97
  98         /*
  99          * step 1: main loop...  while we've got data to move
 100          */
 101
 102         for (/*null*/; togo > 0 ; pageoffset = 0) {
 103
 104                 /*
 105                  * step 2: extract mappings from the map into kernel_map
 106                  */
 107
 108                 error = uvm_map_extract(map, baseva, chunksz, kernel_map, &kva,
 109                             UVM_EXTRACT_QREF | UVM_EXTRACT_CONTIG |
 110                             UVM_EXTRACT_FIXPROT);
 111                 if (error) {
 112
 113                         /* retry with a smaller chunk... */
 114                         if (error == ENOMEM && chunksz > PAGE_SIZE) {
 115                                 chunksz = trunc_page(chunksz / 2);
 116                                 if (chunksz < PAGE_SIZE)
 117                                         chunksz = PAGE_SIZE;
 118                                 continue;
 119                         }
 120
 121                         break;
 122                 }
 123
 124                 /*
 125                  * step 3: move a chunk of data
 126                  */
 127
 128                 sz = chunksz - pageoffset;
 129                 if (sz > togo)
 130                         sz = togo;
 131                 error = uiomove((void *) (kva + pageoffset), sz, uio);
 132                 togo -= sz;
 133                 baseva += chunksz;
 134
 135                 /*
 136                  * step 4: unmap the area of kernel memory
 137                  */
 138
 139                 vm_map_lock(kernel_map);
 140                 uvm_unmap_remove(kernel_map, kva, kva + chunksz, &dead_entries,
 141                     NULL, 0);
 142                 vm_map_unlock(kernel_map);
 143                 if (dead_entries != NULL)
 144                         uvm_unmap_detach(dead_entries, AMAP_REFALL);
 145
 146                 if (error)
 147                         break;
 148         }
 149         return (error);
 150 }