1 /* $NetBSD: db_memrw.c,v 1.8 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 Gordon W. Ross and Jeremy Cooper.
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 /*
33 * Interface to the debugger for virtual memory read/write.
34 * This file is shared by DDB and KGDB, and must work even
35 * when only KGDB is included (thus no db_printf calls).
36 *
37 * To write in the text segment, we have to first make
38 * the page writable, do the write, then restore the PTE.
39 * For writes outside the text segment, and all reads,
40 * just do the access -- if it causes a fault, the debugger
41 * will recover with a longjmp to an appropriate place.
42 *
43 * ALERT! If you want to access device registers with a
44 * specific size, then the read/write functions have to
45 * make sure to do the correct sized pointer access.
46 */
47
48 #include <sys/cdefs.h>
49 __KERNEL_RCSID(0, "$NetBSD: db_memrw.c,v 1.8 2008/04/28 20:23:37 martin Exp $");
50
51 #include <sys/param.h>
52 #include <sys/systm.h>
53 #include <sys/proc.h>
54
55 #include <uvm/uvm_extern.h>
56
57 #include <machine/db_machdep.h>
58 #include <machine/pte.h>
59
60 #include <sun2/sun2/machdep.h>
61 #include <sun2/sun2/control.h>
62
63 #include <ddb/db_access.h>
64
65 extern char etext[]; /* defined by the linker */
66 extern char kernel_text[]; /* locore.s */
67
68 static void db_write_text(char *, size_t size, const char *);
69
70
71 /*
72 * Read bytes from kernel address space for debugger.
73 * This used to check for valid PTEs, but now that
74 * traps in DDB work correctly, "Just Do It!"
75 */
76 void
db_read_bytes(db_addr_t addr,size_t size,char * data)77 db_read_bytes(db_addr_t addr, size_t size, char *data)
78 {
79 char *src = (char *)addr;
80
81 if (size == 4) {
82 *((int *)data) = *((int *)src);
83 return;
84 }
85
86 if (size == 2) {
87 *((short *)data) = *((short *)src);
88 return;
89 }
90
91 while (size > 0) {
92 --size;
93 *data++ = *src++;
94 }
95 }
96
97 /*
98 * Write bytes somewhere in kernel text.
99 * Makes text page writable temporarily.
100 */
101 static void
db_write_text(char * dst,size_t size,const char * data)102 db_write_text(char *dst, size_t size, const char *data)
103 {
104 int oldpte, tmppte;
105 vaddr_t pgva, prevpg;
106 int old_ctx;
107
108 /* Prevent restoring a garbage PTE. */
109 if (size <= 0)
110 return;
111
112 pgva = m68k_trunc_page((long)dst);
113
114 old_ctx = get_context();
115 set_context(0);
116
117 goto firstpage;
118 do {
119
120 /*
121 * If we are on a new page, restore the PTE
122 * for the previous page, and make the new
123 * page writable.
124 */
125 pgva = m68k_trunc_page((long)dst);
126 if (pgva != prevpg) {
127 /*
128 * Restore old PTE. No cache flush,
129 * because the tmp PTE has no-cache.
130 */
131 set_pte(prevpg, oldpte);
132
133 firstpage:
134 oldpte = get_pte(pgva);
135 if ((oldpte & PG_VALID) == 0) {
136 printf(" address %p not a valid page\n", dst);
137 set_context(old_ctx);
138 return;
139 }
140
141 /*
142 * Make the pte writable and non-cached.
143 */
144 tmppte = oldpte;
145 tmppte |= (PG_WRITE | PG_NC);
146
147 set_pte(pgva, tmppte);
148 prevpg = pgva;
149 }
150
151 /* Now we can write in this page of kernel text... */
152 *dst++ = *data++;
153
154 } while (--size > 0);
155
156 /* Restore old PTE for the last page touched. */
157 set_pte(prevpg, oldpte);
158 set_context(old_ctx);
159 }
160
161 /*
162 * Write bytes to kernel address space for debugger.
163 */
164 void
db_write_bytes(db_addr_t addr,size_t size,const char * data)165 db_write_bytes(db_addr_t addr, size_t size, const char *data)
166 {
167 char *dst = (char *)addr;
168
169 /* If any part is in kernel text, use db_write_text() */
170 if ((dst < etext) && ((dst + size) > kernel_text)) {
171 db_write_text(dst, size, data);
172 return;
173 }
174
175 if (size == 4) {
176 *((int *)dst) = *((const int *)data);
177 return;
178 }
179
180 if (size == 2) {
181 *((short *)dst) = *((const short *)data);
182 return;
183 }
184
185 while (size > 0) {
186 --size;
187 *dst++ = *data++;
188 }
189 }
190
191