1/*	$NetBSD: db_memrw.c,v 1.7 2005/12/11 12:19:16 christos 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 1.7 2005/12/11 12:19:16 christos 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
65extern char etext[];	/* defined by the linker */
66extern char	kernel_text[];	/* locore.s */
67
68static 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 */
76void
77db_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 */
101static void
102db_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 */
164void
165db_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