xref: /netbsd/sys/arch/sun3/sun3/db_memrw.c (revision bf9ec67e)
1 /*	$NetBSD: db_memrw.c,v 1.21 2001/09/05 13:21:09 tsutsui 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  * 3. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *        This product includes software developed by the NetBSD
21  *        Foundation, Inc. and its contributors.
22  * 4. Neither the name of The NetBSD Foundation nor the names of its
23  *    contributors may be used to endorse or promote products derived
24  *    from this software without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36  * POSSIBILITY OF SUCH DAMAGE.
37  */
38 
39 /*
40  * Interface to the debugger for virtual memory read/write.
41  * This file is shared by DDB and KGDB, and must work even
42  * when only KGDB is included (thus no db_printf calls).
43  *
44  * To write in the text segment, we have to first make
45  * the page writable, do the write, then restore the PTE.
46  * For writes outside the text segment, and all reads,
47  * just do the access -- if it causes a fault, the debugger
48  * will recover with a longjmp to an appropriate place.
49  *
50  * ALERT!  If you want to access device registers with a
51  * specific size, then the read/write functions have to
52  * make sure to do the correct sized pointer access.
53  */
54 
55 #include <sys/param.h>
56 #include <sys/systm.h>
57 #include <sys/proc.h>
58 
59 #include <uvm/uvm_extern.h>
60 
61 #include <machine/db_machdep.h>
62 #include <machine/pte.h>
63 
64 #include <sun3/sun3/machdep.h>
65 
66 #include <ddb/db_access.h>
67 
68 extern char etext[];	/* defined by the linker */
69 extern char	kernel_text[];	/* locore.s */
70 
71 static void db_write_text __P((char *, size_t size, char *));
72 
73 
74 /*
75  * Read bytes from kernel address space for debugger.
76  * This used to check for valid PTEs, but now that
77  * traps in DDB work correctly, "Just Do It!"
78  */
79 void
80 db_read_bytes(addr, size, data)
81 	db_addr_t addr;
82 	size_t size;
83 	char *data;
84 {
85 	 char *src = (char*)addr;
86 
87 	if (size == 4) {
88 		*((int*)data) = *((int*)src);
89 		return;
90 	}
91 
92 	if (size == 2) {
93 		*((short*)data) = *((short*)src);
94 		return;
95 	}
96 
97 	while (size > 0) {
98 		--size;
99 		*data++ = *src++;
100 	}
101 }
102 
103 /*
104  * Write bytes somewhere in kernel text.
105  * Makes text page writable temporarily.
106  */
107 static void
108 db_write_text(dst, size, data)
109 	char *dst;
110 	size_t size;
111 	char *data;
112 {
113 	int		oldpte, tmppte;
114 	vaddr_t pgva, prevpg;
115 
116 	/* Prevent restoring a garbage PTE. */
117 	if (size <= 0)
118 		return;
119 
120 	pgva = m68k_trunc_page((long)dst);
121 
122 	goto firstpage;
123 	do {
124 
125 		/*
126 		 * If we are on a new page, restore the PTE
127 		 * for the previous page, and make the new
128 		 * page writable.
129 		 */
130 		pgva = m68k_trunc_page((long)dst);
131 		if (pgva != prevpg) {
132 			/*
133 			 * Restore old PTE.  No cache flush,
134 			 * because the tmp PTE has no-cache.
135 			 */
136 			set_pte(prevpg, oldpte);
137 
138 		firstpage:
139 			/*
140 			 * Flush the VAC to prevent a cache hit
141 			 * on the old, read-only PTE.
142 			 */
143 #ifdef	HAVECACHE
144 			if (cache_size)
145 				cache_flush_page(pgva);
146 #endif
147 			oldpte = get_pte(pgva);
148 			if ((oldpte & PG_VALID) == 0) {
149 				printf(" address %p not a valid page\n", dst);
150 				return;
151 			}
152 
153 			/*
154 			 * Make the pte writable and non-cached.
155 			 */
156 			tmppte = oldpte;
157 #ifdef	_SUN3_
158 			tmppte |= (PG_WRITE | PG_NC);
159 #endif
160 #ifdef	_SUN3X_
161 			tmppte &= ~MMU_SHORT_PTE_WP;
162 			tmppte |= MMU_SHORT_PTE_CI;
163 #endif
164 
165 			set_pte(pgva, tmppte);
166 			prevpg = pgva;
167 		}
168 
169 		/* Now we can write in this page of kernel text... */
170 		*dst++ = *data++;
171 
172 	} while (--size > 0);
173 
174 	/* Restore old PTE for the last page touched. */
175 	set_pte(prevpg, oldpte);
176 
177 	/* Finally, clear the instruction cache. */
178 	ICIA();
179 }
180 
181 /*
182  * Write bytes to kernel address space for debugger.
183  */
184 void
185 db_write_bytes(addr, size, data)
186 	db_addr_t addr;
187 	size_t size;
188 	char *data;
189 {
190 	char *dst = (char *)addr;
191 
192 	/* If any part is in kernel text, use db_write_text() */
193 	if ((dst < etext) && ((dst + size) > kernel_text)) {
194 		db_write_text(dst, size, data);
195 		return;
196 	}
197 
198 	if (size == 4) {
199 		*((int*)dst) = *((int*)data);
200 		return;
201 	}
202 
203 	if (size == 2) {
204 		*((short*)dst) = *((short*)data);
205 		return;
206 	}
207 
208 	while (size > 0) {
209 		--size;
210 		*dst++ = *data++;
211 	}
212 }
213 
214