1.\" 2.\" Copyright (c) 2003 Bruce M Simpson <bms@spc.org> 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" $FreeBSD$ 27.\" 28.Dd July 21, 2003 29.Dt PMAP_EXTRACT 9 30.Sh NAME 31.Nm pmap_extract , 32.Nm pmap_extract_and_hold 33.Nd map a virtual address to a physical page 34.Sh SYNOPSIS 35.In sys/param.h 36.In vm/vm.h 37.In vm/pmap.h 38.Ft vm_paddr_t 39.Fn pmap_extract "pmap_t pmap" "vm_offset_t va" 40.Ft vm_paddr_t 41.Fn pmap_extract_and_hold "pmap_t pmap" "vm_offset_t va" "vm_prot_t prot" 42.Sh DESCRIPTION 43The 44.Fn pmap_extract 45function maps a virtual address to a physical page. 46In certain situations, callers may use 47.Fn pmap_extract_and_hold 48instead, to ensure that the returned page is held. 49.Pp 50The 51.Fn pmap_extract_and_hold 52function maps a virtual address to a physical page, and atomically holds 53the returned page for use by the caller, only if the mapping permits 54the given page protection. 55.Sh IMPLEMENTATION NOTES 56Currently, the page protection requested by the caller is not verified. 57.Pp 58In the 59.Fn pmap_extract_and_hold 60function, the 61.Va Giant 62lock is held for the duration of the call to ensure that only a single 63caller is present. 64.Sh RETURN VALUES 65The 66.Fn pmap_extract 67function will return the physical page address associated with the 68virtual address 69.Fa va 70inside the physical map 71.Fa pmap . 72If the mapping does not exist, or if the 73.Fa pmap 74parameter is 75.Dv NULL , 76then 77.Dv NULL 78will be returned. 79.Pp 80The 81.Fn pmap_extract_and_hold 82function will return the physical page address associated with the 83virtual address 84.Fa va 85inside the physical map 86.Fa pmap . 87If the mapping does not exist, the result is a no-op, and 88.Dv NULL 89will 90be returned. 91.Sh SEE ALSO 92.Xr mutex 9 , 93.Xr pmap 9 94.Sh AUTHORS 95.An -nosplit 96The 97.Fn pmap_extract_and_hold 98function was implemented by 99.An Alan L. Cox Aq alc@imimic.com . 100This manual page was written by 101.An Bruce M Simpson Aq bms@spc.org . 102