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.Os 31.Sh NAME 32.Nm pmap_extract , 33.Nm pmap_extract_and_hold 34.Nd map a virtual address to a physical page 35.Sh SYNOPSIS 36.In sys/param.h 37.In vm/vm.h 38.In vm/pmap.h 39.Ft vm_paddr_t 40.Fn pmap_extract "pmap_t pmap" "vm_offset_t va" 41.Ft vm_paddr_t 42.Fn pmap_extract_and_hold "pmap_t pmap" "vm_offset_t va" "vm_prot_t prot" 43.Sh DESCRIPTION 44The 45.Fn pmap_extract 46function maps a virtual address to a physical page. 47In certain situations, callers may use 48.Fn pmap_extract_and_hold 49instead, to ensure that the returned page is held. 50.Pp 51The 52.Fn pmap_extract_and_hold 53function maps a virtual address to a physical page, and atomically holds 54the returned page for use by the caller, only if the mapping permits 55the given page protection. 56.Sh IMPLEMENTATION NOTES 57Currently, the page protection requested by the caller is not verified. 58.Pp 59In the 60.Fn pmap_extract_and_hold 61function, the 62.Va Giant 63lock is held for the duration of the call to ensure that only a single 64caller is present. 65.Sh RETURN VALUES 66The 67.Fn pmap_extract 68function will return the physical page address associated with the 69virtual address 70.Fa va 71inside the physical map 72.Fa pmap . 73If the mapping does not exist, or if the 74.Fa pmap 75parameter is 76.Dv NULL , 77then 78.Dv NULL 79will be returned. 80.Pp 81The 82.Fn pmap_extract_and_hold 83function will return the physical page address associated with the 84virtual address 85.Fa va 86inside the physical map 87.Fa pmap . 88If the mapping does not exist, the result is a no-op, and 89.Dv NULL 90will 91be returned. 92.Sh SEE ALSO 93.Xr mutex 9 , 94.Xr pmap 9 95.Sh AUTHORS 96.An -nosplit 97The 98.Fn pmap_extract_and_hold 99function was implemented by 100.An Alan L. Cox Aq alc@imimic.com . 101This manual page was written by 102.An Bruce M Simpson Aq bms@spc.org . 103