1 /* $NetBSD: control.c,v 1.6 2008/04/28 20:23:37 martin Exp $ */
2
3 /*-
4 * Copyright (c) 1996 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Adam Glass, Gordon W. Ross, and Matthew Fredette.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 __KERNEL_RCSID(0, "$NetBSD: control.c,v 1.6 2008/04/28 20:23:37 martin Exp $");
34
35 #include <sys/param.h>
36
37 #include <machine/pte.h>
38 #include <sun2/sun2/control.h>
39
40 int
get_context(void)41 get_context(void)
42 {
43 return (get_control_byte(CONTEXT_REG) & CONTEXT_MASK);
44 }
45
46 void
set_context(int c)47 set_context(int c)
48 {
49 set_control_byte(CONTEXT_REG, (c & CONTEXT_MASK));
50 }
51
52 u_int
get_pte(vaddr_t va)53 get_pte(vaddr_t va)
54 {
55 u_int pte;
56
57 pte = get_control_word(CONTROL_ADDR_BUILD(PGMAP_BASE, va));
58 if (pte & PG_VALID) {
59 /*
60 * This clears bit 30 (the kernel readable bit, which
61 * should always be set), bit 28 (which should always
62 * be set), bit 26 (the user writable bit, which we
63 * always have tracking the kernel writable bit), and
64 * bit 25 (the fill-on-demand bit, which should always
65 * be set). In the protection, this leaves bit 29
66 * (the kernel writable bit) and bit 27 (the user
67 * readable bit). See pte.h for more about this
68 * hack.
69 */
70 pte &= ~(0x56000000);
71 /*
72 * Flip bit 27 (the user readable bit) to become bit
73 * 27 (the PG_SYSTEM bit).
74 */
75 pte ^= (PG_SYSTEM);
76 }
77 return (pte);
78 }
79
80 void
set_pte(vaddr_t va,u_int pte)81 set_pte(vaddr_t va, u_int pte)
82 {
83 if (pte & PG_VALID) {
84 /* Clear bit 26 (the user writable bit). */
85 pte &= (~0x04000000);
86 /*
87 * Flip bit 27 (the PG_SYSTEM bit) to become bit 27
88 * (the user readable bit).
89 */
90 pte ^= (PG_SYSTEM);
91 /*
92 * Always set bits 30 (the kernel readable bit), bit
93 * 28, and bit 25 (the fill-on-demand bit), and set
94 * bit 26 (the user writable bit) iff bit 29 (the
95 * kernel writable bit) is set *and* bit 27 (the user
96 * readable bit) is set. This latter bit of logic is
97 * expressed in the bizarre second term below, chosen
98 * because it needs no branches.
99 */
100 #if (PG_WRITE >> 2) != PG_SYSTEM
101 #error "PG_WRITE and PG_SYSTEM definitions don't match!"
102 #endif
103 pte |= 0x52000000
104 | ((((pte & PG_WRITE) >> 2) & pte) >> 1);
105 }
106 set_control_word(CONTROL_ADDR_BUILD(PGMAP_BASE, va), pte);
107 }
108
109 int
get_segmap(vaddr_t va)110 get_segmap(vaddr_t va)
111 {
112 return (get_control_byte(CONTROL_ADDR_BUILD(SEGMAP_BASE, va)));
113 }
114
115 void
set_segmap(vaddr_t va,int sme)116 set_segmap(vaddr_t va, int sme)
117 {
118 set_control_byte(CONTROL_ADDR_BUILD(SEGMAP_BASE, va), sme);
119 }
120