xref: /freebsd/share/man/man9/pmap_extract.9 (revision 8019c643f10ad325e1fe6a69d8d7480eb2088725)
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.Dv 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 NULL, then NULL will be returned.
75.Pp
76The
77.Fn pmap_extract_and_hold
78function will return the physical page address associated with the
79virtual address
80.Fa va
81inside the physical map
82.Fa pmap .
83If the mapping does not exist, the result is a no-op, and NULL will
84be returned.
85.Sh SEE ALSO
86.Xr mutex 9 ,
87.Xr pmap 9
88.Sh AUTHORS
89.An -nosplit
90The
91.Fn pmap_extract_and_hold
92function was implemented by
93.An Alan L. Cox Aq alc@imimic.com .
94This manual page was written by
95.An Bruce M Simpson Aq bms@spc.org .
96