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uvm_io.c
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uvm_io.c
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/* $NetBSD: uvm_io.c,v 1.23 2005/12/20 08:25:58 skrll Exp $ */
/*
*
* Copyright (c) 1997 Charles D. Cranor and Washington University.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Charles D. Cranor and
* Washington University.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* from: Id: uvm_io.c,v 1.1.2.2 1997/12/30 12:02:00 mrg Exp
*/
/*
* uvm_io.c: uvm i/o ops
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: uvm_io.c,v 1.23 2005/12/20 08:25:58 skrll Exp $");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mman.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/uio.h>
#include <uvm/uvm.h>
/*
* functions
*/
/*
* uvm_io: perform I/O on a map
*
* => caller must have a reference to "map" so that it doesn't go away
* while we are working.
*/
int
uvm_io(struct vm_map *map, struct uio *uio)
{
vaddr_t baseva, endva, pageoffset, kva;
vsize_t chunksz, togo, sz;
struct vm_map_entry *dead_entries;
int error;
/*
* step 0: sanity checks and set up for copy loop. start with a
* large chunk size. if we have trouble finding vm space we will
* reduce it.
*/
if (uio->uio_resid == 0)
return(0);
togo = uio->uio_resid;
baseva = (vaddr_t) uio->uio_offset;
endva = baseva + (togo - 1);
if (endva < baseva) /* wrap around? */
return(EIO);
if (baseva >= VM_MAXUSER_ADDRESS)
return(0);
if (endva >= VM_MAXUSER_ADDRESS)
/* EOF truncate */
togo = togo - (endva - VM_MAXUSER_ADDRESS + 1);
pageoffset = baseva & PAGE_MASK;
baseva = trunc_page(baseva);
chunksz = MIN(round_page(togo + pageoffset), trunc_page(MAXPHYS));
error = 0;
/*
* step 1: main loop... while we've got data to move
*/
for (/*null*/; togo > 0 ; pageoffset = 0) {
/*
* step 2: extract mappings from the map into kernel_map
*/
error = uvm_map_extract(map, baseva, chunksz, kernel_map, &kva,
UVM_EXTRACT_QREF | UVM_EXTRACT_CONTIG |
UVM_EXTRACT_FIXPROT);
if (error) {
/* retry with a smaller chunk... */
if (error == ENOMEM && chunksz > PAGE_SIZE) {
chunksz = trunc_page(chunksz / 2);
if (chunksz < PAGE_SIZE)
chunksz = PAGE_SIZE;
continue;
}
break;
}
/*
* step 3: move a chunk of data
*/
sz = chunksz - pageoffset;
if (sz > togo)
sz = togo;
error = uiomove((caddr_t) (kva + pageoffset), sz, uio);
togo -= sz;
baseva += chunksz;
/*
* step 4: unmap the area of kernel memory
*/
vm_map_lock(kernel_map);
uvm_unmap_remove(kernel_map, kva, kva + chunksz, &dead_entries,
NULL, 0);
vm_map_unlock(kernel_map);
if (dead_entries != NULL)
uvm_unmap_detach(dead_entries, AMAP_REFALL);
if (error)
break;
}
return (error);
}