Annotation of sys/uvm/uvm_io.c, Revision 1.1
1.1 ! nbrk 1: /* $OpenBSD: uvm_io.c,v 1.16 2005/11/04 21:48:07 miod Exp $ */
! 2: /* $NetBSD: uvm_io.c,v 1.12 2000/06/27 17:29:23 mrg Exp $ */
! 3:
! 4: /*
! 5: *
! 6: * Copyright (c) 1997 Charles D. Cranor and Washington University.
! 7: * All rights reserved.
! 8: *
! 9: * Redistribution and use in source and binary forms, with or without
! 10: * modification, are permitted provided that the following conditions
! 11: * are met:
! 12: * 1. Redistributions of source code must retain the above copyright
! 13: * notice, this list of conditions and the following disclaimer.
! 14: * 2. Redistributions in binary form must reproduce the above copyright
! 15: * notice, this list of conditions and the following disclaimer in the
! 16: * documentation and/or other materials provided with the distribution.
! 17: * 3. All advertising materials mentioning features or use of this software
! 18: * must display the following acknowledgement:
! 19: * This product includes software developed by Charles D. Cranor and
! 20: * Washington University.
! 21: * 4. The name of the author may not be used to endorse or promote products
! 22: * derived from this software without specific prior written permission.
! 23: *
! 24: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
! 25: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
! 26: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
! 27: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
! 28: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
! 29: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
! 30: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
! 31: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
! 32: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
! 33: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
! 34: *
! 35: * from: Id: uvm_io.c,v 1.1.2.2 1997/12/30 12:02:00 mrg Exp
! 36: */
! 37:
! 38: /*
! 39: * uvm_io.c: uvm i/o ops
! 40: */
! 41:
! 42: #include <sys/param.h>
! 43: #include <sys/systm.h>
! 44: #include <sys/mman.h>
! 45: #include <sys/proc.h>
! 46: #include <sys/malloc.h>
! 47: #include <sys/uio.h>
! 48:
! 49: #include <uvm/uvm.h>
! 50:
! 51: /*
! 52: * functions
! 53: */
! 54:
! 55: /*
! 56: * uvm_io: perform I/O on a map
! 57: *
! 58: * => caller must have a reference to "map" so that it doesn't go away
! 59: * while we are working.
! 60: */
! 61:
! 62: int
! 63: uvm_io(vm_map_t map, struct uio *uio, int flags)
! 64: {
! 65: vaddr_t baseva, endva, pageoffset, kva;
! 66: vsize_t chunksz, togo, sz;
! 67: vm_map_entry_t dead_entries;
! 68: int error, extractflags;
! 69:
! 70: /*
! 71: * step 0: sanity checks and set up for copy loop. start with a
! 72: * large chunk size. if we have trouble finding vm space we will
! 73: * reduce it.
! 74: */
! 75:
! 76: if (uio->uio_resid == 0)
! 77: return(0);
! 78: togo = uio->uio_resid;
! 79:
! 80: baseva = (vaddr_t) uio->uio_offset;
! 81: endva = baseva + (togo - 1);
! 82:
! 83: if (endva < baseva) /* wrap around? */
! 84: return(EIO);
! 85:
! 86: if (baseva >= VM_MAXUSER_ADDRESS)
! 87: return(0);
! 88: if (endva >= VM_MAXUSER_ADDRESS)
! 89: /* EOF truncate */
! 90: togo = togo - (endva - VM_MAXUSER_ADDRESS + 1);
! 91: pageoffset = baseva & PAGE_MASK;
! 92: baseva = trunc_page(baseva);
! 93: chunksz = min(round_page(togo + pageoffset), MAXBSIZE);
! 94: error = 0;
! 95:
! 96: extractflags = UVM_EXTRACT_QREF | UVM_EXTRACT_CONTIG;
! 97: if (flags & UVM_IO_FIXPROT)
! 98: extractflags |= UVM_EXTRACT_FIXPROT;
! 99:
! 100: /*
! 101: * step 1: main loop... while we've got data to move
! 102: */
! 103:
! 104: for (/*null*/; togo > 0 ; pageoffset = 0) {
! 105:
! 106: /*
! 107: * step 2: extract mappings from the map into kernel_map
! 108: */
! 109:
! 110: error = uvm_map_extract(map, baseva, chunksz, kernel_map, &kva,
! 111: extractflags);
! 112: if (error) {
! 113:
! 114: /* retry with a smaller chunk... */
! 115: if (error == ENOMEM && chunksz > PAGE_SIZE) {
! 116: chunksz = trunc_page(chunksz / 2);
! 117: if (chunksz < PAGE_SIZE)
! 118: chunksz = PAGE_SIZE;
! 119: continue;
! 120: }
! 121:
! 122: break;
! 123: }
! 124:
! 125: /*
! 126: * step 3: move a chunk of data
! 127: */
! 128:
! 129: sz = chunksz - pageoffset;
! 130: if (sz > togo)
! 131: sz = togo;
! 132: error = uiomove((caddr_t) (kva + pageoffset), sz, uio);
! 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,
! 143: &dead_entries, NULL);
! 144: vm_map_unlock(kernel_map);
! 145:
! 146: if (dead_entries != NULL)
! 147: uvm_unmap_detach(dead_entries, AMAP_REFALL);
! 148:
! 149: /*
! 150: * We defer checking the error return from uiomove until
! 151: * here so that we won't leak memory.
! 152: */
! 153: if (error)
! 154: break;
! 155: }
! 156:
! 157: /*
! 158: * done
! 159: */
! 160:
! 161: return (error);
! 162: }
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