1 | /* $NetBSD: db_memrw.c,v 1.2 2016/05/12 06:45:16 maxv Exp $ */ |
2 | |
3 | /*- |
4 | * Copyright (c) 1996, 2000 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 Jason R. Thorpe. |
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 | * Modified for i386 from hp300 version by |
48 | * Jason R. Thorpe <thorpej@zembu.com>. |
49 | * |
50 | * Basic copy to amd64 by fvdl. |
51 | * |
52 | * i386 and amd64 merge by jym. |
53 | */ |
54 | |
55 | #include <sys/cdefs.h> |
56 | __KERNEL_RCSID(0, "$NetBSD: db_memrw.c,v 1.2 2016/05/12 06:45:16 maxv Exp $" ); |
57 | |
58 | #include <sys/param.h> |
59 | #include <sys/proc.h> |
60 | #include <sys/systm.h> |
61 | |
62 | #include <machine/db_machdep.h> |
63 | |
64 | #include <ddb/db_access.h> |
65 | |
66 | /* |
67 | * Read bytes from kernel address space for debugger. |
68 | */ |
69 | void |
70 | db_read_bytes(vaddr_t addr, size_t size, char *data) |
71 | { |
72 | char *src; |
73 | |
74 | src = (char *)addr; |
75 | |
76 | if (size == 8) { |
77 | *((long *)data) = *((long *)src); |
78 | return; |
79 | } |
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 | *data++ = *src++; |
93 | } |
94 | |
95 | /* |
96 | * Write bytes somewhere in the kernel text. Make the text |
97 | * pages writable temporarily. |
98 | */ |
99 | static void |
100 | db_write_text(vaddr_t addr, size_t size, const char *data) |
101 | { |
102 | pt_entry_t *ppte, pte; |
103 | size_t limit; |
104 | char *dst; |
105 | |
106 | if (size == 0) |
107 | return; |
108 | |
109 | dst = (char *)addr; |
110 | |
111 | do { |
112 | addr = (vaddr_t)dst; |
113 | /* |
114 | * Get the PTE for the page. |
115 | */ |
116 | ppte = kvtopte(addr); |
117 | pte = *ppte; |
118 | |
119 | if ((pte & PG_V) == 0) { |
120 | printf(" address %p not a valid page\n" , dst); |
121 | return; |
122 | } |
123 | |
124 | /* |
125 | * Compute number of bytes that can be written |
126 | * with this mapping and subtract it from the |
127 | * total size. |
128 | */ |
129 | if (pte & PG_PS) |
130 | limit = NBPD_L2 - (addr & (NBPD_L2 - 1)); |
131 | else |
132 | limit = PAGE_SIZE - (addr & PGOFSET); |
133 | if (limit > size) |
134 | limit = size; |
135 | size -= limit; |
136 | |
137 | /* |
138 | * Make the kernel text page writable. |
139 | */ |
140 | pmap_pte_clearbits(ppte, PG_KR); |
141 | pmap_pte_setbits(ppte, PG_KW); |
142 | pmap_update_pg(addr); |
143 | |
144 | /* |
145 | * MULTIPROCESSOR: no shootdown required as the PTE continues to |
146 | * map the same page and other CPUs do not need write access. |
147 | */ |
148 | |
149 | /* |
150 | * Page is now writable. Do as much access as we |
151 | * can in this page. |
152 | */ |
153 | for (; limit > 0; limit--) |
154 | *dst++ = *data++; |
155 | |
156 | /* |
157 | * Turn the page back to read-only. |
158 | */ |
159 | pmap_pte_clearbits(ppte, PG_KW); |
160 | pmap_pte_setbits(ppte, PG_KR); |
161 | pmap_update_pg(addr); |
162 | |
163 | /* |
164 | * MULTIPROCESSOR: no shootdown required as all other CPUs |
165 | * should be in CPUF_PAUSE state and will not cache the PTE |
166 | * with the write access set. |
167 | */ |
168 | } while (size != 0); |
169 | } |
170 | |
171 | /* |
172 | * Write bytes to kernel address space for debugger. |
173 | */ |
174 | void |
175 | db_write_bytes(vaddr_t addr, size_t size, const char *data) |
176 | { |
177 | extern int __rodata_start; |
178 | extern int __data_start; |
179 | char *dst; |
180 | |
181 | dst = (char *)addr; |
182 | |
183 | /* If any part is in kernel text or rodata, use db_write_text() */ |
184 | if ((addr >= KERNBASE && addr < (vaddr_t)&__rodata_start) || |
185 | (addr >= (vaddr_t)&__rodata_start && addr < (vaddr_t)&__data_start)) { |
186 | db_write_text(addr, size, data); |
187 | return; |
188 | } |
189 | |
190 | dst = (char *)addr; |
191 | |
192 | if (size == 8) { |
193 | *((long *)dst) = *((const long *)data); |
194 | return; |
195 | } |
196 | |
197 | if (size == 4) { |
198 | *((int *)dst) = *((const int *)data); |
199 | return; |
200 | } |
201 | |
202 | if (size == 2) { |
203 | *((short *)dst) = *((const short *)data); |
204 | return; |
205 | } |
206 | |
207 | while (size-- > 0) |
208 | *dst++ = *data++; |
209 | } |
210 | |