1 /* $OpenBSD: uvm_io.c,v 1.22 2014/07/11 16:35:40 jsg Exp $ */ 2 /* $NetBSD: uvm_io.c,v 1.12 2000/06/27 17:29:23 mrg Exp $ */ 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 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 * 28 * from: Id: uvm_io.c,v 1.1.2.2 1997/12/30 12:02:00 mrg Exp 29 */ 30 31 /* 32 * uvm_io.c: uvm i/o ops 33 */ 34 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/mman.h> 38 #include <sys/proc.h> 39 #include <sys/malloc.h> 40 #include <sys/uio.h> 41 42 #include <uvm/uvm.h> 43 44 /* 45 * functions 46 */ 47 48 /* 49 * uvm_io: perform I/O on a map 50 * 51 * => caller must have a reference to "map" so that it doesn't go away 52 * while we are working. 53 */ 54 55 int 56 uvm_io(vm_map_t map, struct uio *uio, int flags) 57 { 58 vaddr_t baseva, endva, pageoffset, kva; 59 vsize_t chunksz, togo, sz; 60 struct uvm_map_deadq dead_entries; 61 int error, extractflags; 62 63 /* 64 * step 0: sanity checks and set up for copy loop. start with a 65 * large chunk size. if we have trouble finding vm space we will 66 * reduce it. 67 */ 68 if (uio->uio_resid == 0) 69 return(0); 70 togo = uio->uio_resid; 71 72 baseva = (vaddr_t) uio->uio_offset; 73 endva = baseva + (togo - 1); 74 75 if (endva < baseva) /* wrap around? */ 76 return(EIO); 77 78 if (baseva >= VM_MAXUSER_ADDRESS) 79 return(0); 80 if (endva >= VM_MAXUSER_ADDRESS) 81 /* EOF truncate */ 82 togo = togo - (endva - VM_MAXUSER_ADDRESS + 1); 83 pageoffset = baseva & PAGE_MASK; 84 baseva = trunc_page(baseva); 85 chunksz = min(round_page(togo + pageoffset), MAXBSIZE); 86 error = 0; 87 88 extractflags = 0; 89 if (flags & UVM_IO_FIXPROT) 90 extractflags |= UVM_EXTRACT_FIXPROT; 91 92 /* step 1: main loop... while we've got data to move */ 93 for (/*null*/; togo > 0 ; pageoffset = 0) { 94 /* step 2: extract mappings from the map into kernel_map */ 95 error = uvm_map_extract(map, baseva, chunksz, &kva, 96 extractflags); 97 if (error) { 98 99 /* retry with a smaller chunk... */ 100 if (error == ENOMEM && chunksz > PAGE_SIZE) { 101 chunksz = trunc_page(chunksz / 2); 102 if (chunksz < PAGE_SIZE) 103 chunksz = PAGE_SIZE; 104 continue; 105 } 106 107 break; 108 } 109 110 /* step 3: move a chunk of data */ 111 sz = chunksz - pageoffset; 112 if (sz > togo) 113 sz = togo; 114 error = uiomove((caddr_t) (kva + pageoffset), sz, uio); 115 togo -= sz; 116 baseva += chunksz; 117 118 /* step 4: unmap the area of kernel memory */ 119 vm_map_lock(kernel_map); 120 TAILQ_INIT(&dead_entries); 121 uvm_unmap_remove(kernel_map, kva, kva+chunksz, 122 &dead_entries, FALSE, TRUE); 123 vm_map_unlock(kernel_map); 124 uvm_unmap_detach(&dead_entries, AMAP_REFALL); 125 126 /* 127 * We defer checking the error return from uiomove until 128 * here so that we won't leak memory. 129 */ 130 if (error) 131 break; 132 } 133 134 return (error); 135 } 136