xref: /freebsd/sys/amd64/include/sf_buf.h (revision dd41de95a84d979615a2ef11df6850622bf6184e)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 2003, 2005 Alan L. Cox <alc@cs.rice.edu>
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  *
28  * $FreeBSD$
29  */
30 
31 #ifndef _MACHINE_SF_BUF_H_
32 #define _MACHINE_SF_BUF_H_
33 
34 /*
35  * On this machine, the only purpose for which sf_buf is used is to implement
36  * an opaque pointer required by the machine-independent parts of the kernel.
37  * That pointer references the vm_page that is "mapped" by the sf_buf.  The
38  * actual mapping is provided by the direct virtual-to-physical mapping.
39  */
40 static inline vm_offset_t
41 sf_buf_kva(struct sf_buf *sf)
42 {
43 
44 	return (PHYS_TO_DMAP(VM_PAGE_TO_PHYS((vm_page_t)sf)));
45 }
46 
47 static inline vm_page_t
48 sf_buf_page(struct sf_buf *sf)
49 {
50 
51 	return ((vm_page_t)sf);
52 }
53 #endif /* !_MACHINE_SF_BUF_H_ */
54