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uvm_io.c revision 1.22 
      1 /*	$NetBSD: uvm_io.c,v 1.22 2005/12/06 16:01:13 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/cdefs.h>
     42 __KERNEL_RCSID(0, "$NetBSD: uvm_io.c,v 1.22 2005/12/06 16:01:13 chs 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((caddr_t) (kva + pageoffset), sz, uio);
    132 		togo -= sz;
    133 		baseva += chunksz;
    134 
    135 
    136 		/*
    137 		 * step 4: unmap the area of kernel memory
    138 		 */
    139 
    140 		vm_map_lock(kernel_map);
    141 		uvm_unmap_remove(kernel_map, kva, kva + chunksz, &dead_entries,
    142 		    NULL, 0);
    143 		vm_map_unlock(kernel_map);
    144 		if (dead_entries != NULL)
    145 			uvm_unmap_detach(dead_entries, AMAP_REFALL);
    146 
    147 		if (error)
    148 			break;
    149 	}
    150 	return (error);
    151 }
    152