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uvm_io.c revision 1.15 
      1 /*	$NetBSD: uvm_io.c,v 1.15 2001/06/02 18:09:26 chs 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/param.h>
     42 #include <sys/systm.h>
     43 #include <sys/mman.h>
     44 #include <sys/proc.h>
     45 #include <sys/malloc.h>
     46 #include <sys/uio.h>
     47 
     48 #include <uvm/uvm.h>
     49 
     50 /*
     51  * functions
     52  */
     53 
     54 /*
     55  * uvm_io: perform I/O on a map
     56  *
     57  * => caller must have a reference to "map" so that it doesn't go away
     58  *    while we are working.
     59  */
     60 
     61 int
     62 uvm_io(map, uio)
     63 	struct vm_map *map;
     64 	struct uio *uio;
     65 {
     66 	vaddr_t baseva, endva, pageoffset, kva;
     67 	vsize_t chunksz, togo, sz;
     68 	struct vm_map_entry *dead_entries;
     69 	int error;
     70 
     71 	/*
     72 	 * step 0: sanity checks and set up for copy loop.  start with a
     73 	 * large chunk size.  if we have trouble finding vm space we will
     74 	 * reduce it.
     75 	 */
     76 
     77 	if (uio->uio_resid == 0)
     78 		return(0);
     79 	togo = uio->uio_resid;
     80 
     81 	baseva = (vaddr_t) uio->uio_offset;
     82 	endva = baseva + (togo - 1);
     83 
     84 	if (endva < baseva)   /* wrap around? */
     85 		return(EIO);
     86 
     87 	if (baseva >= VM_MAXUSER_ADDRESS)
     88 		return(0);
     89 	if (endva >= VM_MAXUSER_ADDRESS)
     90 		/* EOF truncate */
     91 		togo = togo - (endva - VM_MAXUSER_ADDRESS + 1);
     92 	pageoffset = baseva & PAGE_MASK;
     93 	baseva = trunc_page(baseva);
     94 	chunksz = min(round_page(togo + pageoffset), MAXBSIZE);
     95 	error = 0;
     96 
     97 	/*
     98 	 * step 1: main loop...  while we've got data to move
     99 	 */
    100 
    101 	for (/*null*/; togo > 0 ; pageoffset = 0) {
    102 
    103 		/*
    104 		 * step 2: extract mappings from the map into kernel_map
    105 		 */
    106 
    107 		error = uvm_map_extract(map, baseva, chunksz, kernel_map, &kva,
    108 			    UVM_EXTRACT_QREF | UVM_EXTRACT_CONTIG |
    109 			    UVM_EXTRACT_FIXPROT);
    110 		if (error) {
    111 
    112 			/* retry with a smaller chunk... */
    113 			if (error == ENOMEM && chunksz > PAGE_SIZE) {
    114 				chunksz = trunc_page(chunksz / 2);
    115 				if (chunksz < PAGE_SIZE)
    116 					chunksz = PAGE_SIZE;
    117 				continue;
    118 			}
    119 
    120 			break;
    121 		}
    122 
    123 		/*
    124 		 * step 3: move a chunk of data
    125 		 */
    126 
    127 		sz = chunksz - pageoffset;
    128 		if (sz > togo)
    129 			sz = togo;
    130 		error = uiomove((caddr_t) (kva + pageoffset), sz, uio);
    131 		if (error)
    132 			break;
    133 		togo -= sz;
    134 		baseva += chunksz;
    135 
    136 
    137 		/*
    138 		 * step 4: unmap the area of kernel memory
    139 		 */
    140 
    141 		vm_map_lock(kernel_map);
    142 		uvm_unmap_remove(kernel_map, kva, kva + chunksz, &dead_entries);
    143 		vm_map_unlock(kernel_map);
    144 		if (dead_entries != NULL)
    145 			uvm_unmap_detach(dead_entries, AMAP_REFALL);
    146 	}
    147 	return (error);
    148 }
    149