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uvm_io.c revision 1.6 
      1 /*	$NetBSD: uvm_io.c,v 1.6 1998/08/13 02:11:00 eeh 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/mman.h>
     48 #include <sys/proc.h>
     49 #include <sys/malloc.h>
     50 #include <sys/uio.h>
     51 
     52 #include <vm/vm.h>
     53 #include <vm/vm_page.h>
     54 #include <vm/vm_kern.h>
     55 
     56 #include <uvm/uvm.h>
     57 
     58 /*
     59  * functions
     60  */
     61 
     62 /*
     63  * uvm_io: perform I/O on a map
     64  *
     65  * => caller must have a reference to "map" so that it doesn't go away
     66  *    while we are working.
     67  */
     68 
     69 int
     70 uvm_io(map, uio)
     71 	vm_map_t map;
     72 	struct uio *uio;
     73 {
     74 	vaddr_t baseva, endva, pageoffset, kva;
     75 	vsize_t chunksz, togo, sz;
     76 	vm_map_entry_t dead_entries;
     77 	int error;
     78 
     79 	/*
     80 	 * step 0: sanity checks and set up for copy loop.  start with a
     81 	 * large chunk size.  if we have trouble finding vm space we will
     82 	 * reduce it.
     83 	 */
     84 
     85 	if (uio->uio_resid == 0)
     86 		return(0);
     87 	togo = uio->uio_resid;
     88 
     89 	baseva = (vaddr_t) uio->uio_offset;
     90 	endva = baseva + (togo - 1);
     91 
     92 	if (endva < baseva)   /* wrap around? */
     93 		return(EIO);
     94 
     95 	if (baseva >= VM_MAXUSER_ADDRESS)
     96 		return(0);
     97 	if (endva >= VM_MAXUSER_ADDRESS)
     98 		/* EOF truncate */
     99 		togo = togo - (endva - VM_MAXUSER_ADDRESS + 1);
    100 	pageoffset = baseva & PAGE_MASK;
    101 	baseva = trunc_page(baseva);
    102 	chunksz = min(round_page(togo + pageoffset), MAXBSIZE);
    103 	error = 0;
    104 
    105 	/*
    106 	 * step 1: main loop...  while we've got data to move
    107 	 */
    108 
    109 	for (/*null*/; togo > 0 ; pageoffset = 0) {
    110 
    111 		/*
    112 		 * step 2: extract mappings from the map into kernel_map
    113 		 */
    114 
    115 		error = uvm_map_extract(map, baseva, chunksz, kernel_map, &kva,
    116 			    UVM_EXTRACT_QREF | UVM_EXTRACT_CONTIG |
    117 			    UVM_EXTRACT_FIXPROT);
    118 		if (error) {
    119 
    120 			/* retry with a smaller chunk... */
    121 			if (error == ENOMEM && chunksz > PAGE_SIZE) {
    122 				chunksz = trunc_page(chunksz / 2);
    123 				if (chunksz < PAGE_SIZE)
    124 					chunksz = PAGE_SIZE;
    125 				continue;
    126 			}
    127 
    128 			break;
    129 		}
    130 
    131 		/*
    132 		 * step 3: move a chunk of data
    133 		 */
    134 
    135 		sz = chunksz - pageoffset;
    136 		if (sz > togo)
    137 			sz = togo;
    138 		error = uiomove((caddr_t) (kva + pageoffset), sz, uio);
    139 		if (error)
    140 			break;
    141 		togo -= sz;
    142 		baseva += chunksz;
    143 
    144 
    145 		/*
    146 		 * step 4: unmap the area of kernel memory
    147 		 */
    148 
    149 		vm_map_lock(kernel_map);
    150 		(void)uvm_unmap_remove(kernel_map, kva, kva+chunksz, 1,
    151 		    &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 	 * done
    160 	 */
    161 
    162 	return (error);
    163 }
    164