1 /* $OpenBSD: uvm_io.c,v 1.26 2016/01/09 11:34:27 kettenis 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/uio.h> 39 40 #include <uvm/uvm.h> 41 42 /* 43 * functions 44 */ 45 46 /* 47 * uvm_io: perform I/O on a map 48 * 49 * => caller must have a reference to "map" so that it doesn't go away 50 * while we are working. 51 */ 52 53 int 54 uvm_io(vm_map_t map, struct uio *uio, int flags) 55 { 56 vaddr_t baseva, endva, pageoffset, kva; 57 vsize_t chunksz, togo, sz; 58 struct uvm_map_deadq dead_entries; 59 int error, extractflags; 60 61 /* 62 * step 0: sanity checks and set up for copy loop. start with a 63 * large chunk size. if we have trouble finding vm space we will 64 * reduce it. 65 */ 66 if (uio->uio_resid == 0) 67 return(0); 68 togo = uio->uio_resid; 69 70 baseva = (vaddr_t) uio->uio_offset; 71 endva = baseva + (togo - 1); 72 73 if (endva < baseva) /* wrap around? */ 74 return(EIO); 75 76 if (baseva >= VM_MAXUSER_ADDRESS) 77 return(0); 78 if (endva >= VM_MAXUSER_ADDRESS) 79 /* EOF truncate */ 80 togo = togo - (endva - VM_MAXUSER_ADDRESS + 1); 81 pageoffset = baseva & PAGE_MASK; 82 baseva = trunc_page(baseva); 83 chunksz = min(round_page(togo + pageoffset), MAXBSIZE); 84 error = 0; 85 86 extractflags = 0; 87 if (flags & UVM_IO_FIXPROT) 88 extractflags |= UVM_EXTRACT_FIXPROT; 89 90 /* step 1: main loop... while we've got data to move */ 91 for (/*null*/; togo > 0 ; pageoffset = 0) { 92 /* step 2: extract mappings from the map into kernel_map */ 93 error = uvm_map_extract(map, baseva, chunksz, &kva, 94 extractflags); 95 if (error) { 96 97 /* retry with a smaller chunk... */ 98 if (error == ENOMEM && chunksz > PAGE_SIZE) { 99 chunksz = trunc_page(chunksz / 2); 100 if (chunksz < PAGE_SIZE) 101 chunksz = PAGE_SIZE; 102 continue; 103 } 104 105 break; 106 } 107 108 /* step 3: move a chunk of data */ 109 sz = chunksz - pageoffset; 110 if (sz > togo) 111 sz = togo; 112 error = uiomove((caddr_t) (kva + pageoffset), sz, uio); 113 togo -= sz; 114 baseva += chunksz; 115 116 /* step 4: unmap the area of kernel memory */ 117 vm_map_lock(kernel_map); 118 TAILQ_INIT(&dead_entries); 119 uvm_unmap_remove(kernel_map, kva, kva+chunksz, 120 &dead_entries, FALSE, TRUE); 121 vm_map_unlock(kernel_map); 122 uvm_unmap_detach(&dead_entries, AMAP_REFALL); 123 124 /* 125 * We defer checking the error return from uiomove until 126 * here so that we won't leak memory. 127 */ 128 if (error) 129 break; 130 } 131 132 return (error); 133 } 134