1 /* $OpenBSD: db_memrw.c,v 1.9 2024/02/23 18:19:02 cheloha Exp $ */
2 /* $NetBSD: db_memrw.c,v 1.1 2003/04/26 18:39:27 fvdl Exp $ */
3
4 /*-
5 * Copyright (c) 1996, 2000 The NetBSD Foundation, Inc.
6 * All rights reserved.
7 *
8 * This code is derived from software contributed to The NetBSD Foundation
9 * by Gordon W. Ross and Jason R. Thorpe.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30 * POSSIBILITY OF SUCH DAMAGE.
31 */
32
33 /*
34 * Interface to the debugger for virtual memory read/write.
35 *
36 * To write in the text segment, we have to first make
37 * the page writable, do the write, then restore the PTE.
38 * For writes outside the text segment, and all reads,
39 * just do the access -- if it causes a fault, the debugger
40 * will recover with a longjmp to an appropriate place.
41 *
42 * ALERT! If you want to access device registers with a
43 * specific size, then the read/write functions have to
44 * make sure to do the correct sized pointer access.
45 *
46 * Modified for i386 from hp300 version by
47 * Jason R. Thorpe <thorpej@zembu.com>.
48 *
49 * Basic copy to amd64 by fvdl.
50 */
51
52 #include <sys/param.h>
53 #include <sys/systm.h>
54
55 #include <uvm/uvm_extern.h>
56
57 #include <machine/db_machdep.h>
58
59 /*
60 * Read bytes from kernel address space for debugger.
61 */
62 void
db_read_bytes(vaddr_t addr,size_t size,void * datap)63 db_read_bytes(vaddr_t addr, size_t size, void *datap)
64 {
65 char *data = datap, *src;
66
67 src = (char *)addr;
68
69 if (size == 8) {
70 *((long *)data) = *((long *)src);
71 return;
72 }
73
74 if (size == 4) {
75 *((int *)data) = *((int *)src);
76 return;
77 }
78
79 if (size == 2) {
80 *((short *)data) = *((short *)src);
81 return;
82 }
83
84 while (size-- > 0)
85 *data++ = *src++;
86 }
87
88 /*
89 * Write bytes somewhere in the kernel text. Make the text
90 * pages writable temporarily.
91 */
92 static void
db_write_text(vaddr_t addr,size_t size,char * data)93 db_write_text(vaddr_t addr, size_t size, char *data)
94 {
95 pt_entry_t *pte, oldpte, tmppte;
96 vaddr_t pgva;
97 size_t limit;
98 char *dst;
99
100 if (size == 0)
101 return;
102
103 dst = (char *)addr;
104
105 do {
106 /*
107 * Get the PTE for the page.
108 */
109 pte = kvtopte(addr);
110 oldpte = *pte;
111
112 if ((oldpte & PG_V) == 0) {
113 printf(" address %p not a valid page\n", dst);
114 return;
115 }
116
117 /*
118 * Get the VA for the page.
119 */
120 if (oldpte & PG_PS)
121 pgva = (vaddr_t)dst & PG_LGFRAME;
122 else
123 pgva = trunc_page((vaddr_t)dst);
124
125 /*
126 * Compute number of bytes that can be written
127 * with this mapping and subtract it from the
128 * total size.
129 */
130 if (oldpte & PG_PS)
131 limit = NBPD_L2 - ((vaddr_t)dst & (NBPD_L2 - 1));
132 else
133 limit = PAGE_SIZE - ((vaddr_t)dst & PGOFSET);
134 if (limit > size)
135 limit = size;
136 size -= limit;
137
138 tmppte = (oldpte & ~PG_KR) | PG_KW;
139 *pte = tmppte;
140 pmap_update_pg(pgva);
141
142 /*
143 * Page is now writable. Do as much access as we
144 * can in this page.
145 */
146 for (; limit > 0; limit--)
147 *dst++ = *data++;
148
149 /*
150 * Restore the old PTE.
151 */
152 *pte = oldpte;
153
154 pmap_update_pg(pgva);
155
156 } while (size != 0);
157 }
158
159 /*
160 * Write bytes to kernel address space for debugger.
161 */
162 void
db_write_bytes(vaddr_t addr,size_t size,void * datap)163 db_write_bytes(vaddr_t addr, size_t size, void *datap)
164 {
165 extern char etext;
166 char *data = datap, *dst;
167
168 /* If any part is in kernel text, use db_write_text() */
169 if (addr >= KERNBASE && addr < (vaddr_t)&etext) {
170 db_write_text(addr, size, data);
171 return;
172 }
173
174 dst = (char *)addr;
175
176 if (size == 8) {
177 *((long *)dst) = *((long *)data);
178 return;
179 }
180
181 if (size == 4) {
182 *((int *)dst) = *((int *)data);
183 return;
184 }
185
186 if (size == 2) {
187 *((short *)dst) = *((short *)data);
188 return;
189 }
190
191 while (size-- > 0)
192 *dst++ = *data++;
193 }
194