1 /*
2 * Copyright 2000 Brian S. Dean <bsd@bsdhome.com>
3 * All Rights Reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY BRIAN S. DEAN ``AS IS'' AND ANY
16 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
18 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL BRIAN S. DEAN BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
20 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
21 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
22 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
23 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
25 * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
26 * DAMAGE.
27 */
28
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31
32 #include <machine/reg.h>
33 #include <machine/sysarch.h>
34
35 int
i386_set_watch(int watchnum,unsigned int watchaddr,int size,int access,struct dbreg * d)36 i386_set_watch(int watchnum, unsigned int watchaddr, int size,
37 int access, struct dbreg * d)
38 {
39 int i;
40 unsigned int mask;
41
42 if (watchnum == -1) {
43 for (i = 0, mask = 0x3; i < 4; i++, mask <<= 2)
44 if ((DBREG_DRX(d,7) & mask) == 0)
45 break;
46 if (i < 4)
47 watchnum = i;
48 else
49 return -1;
50 }
51
52 switch (access) {
53 case DBREG_DR7_EXEC:
54 size = 1; /* size must be 1 for an execution breakpoint */
55 /* fall through */
56 case DBREG_DR7_WRONLY:
57 case DBREG_DR7_RDWR:
58 break;
59 default : return -1; break;
60 }
61
62 /*
63 * we can watch a 1, 2, or 4 byte sized location
64 */
65 switch (size) {
66 case 1 : mask = 0x00; break;
67 case 2 : mask = 0x01 << 2; break;
68 case 4 : mask = 0x03 << 2; break;
69 default : return -1; break;
70 }
71
72 mask |= access;
73
74 /* clear the bits we are about to affect */
75 DBREG_DRX(d,7) &= ~((0x3 << (watchnum*2)) | (0x0f << (watchnum*4+16)));
76
77 /* set drN register to the address, N=watchnum */
78 DBREG_DRX(d,watchnum) = watchaddr;
79
80 /* enable the watchpoint */
81 DBREG_DRX(d,7) |= (0x2 << (watchnum*2)) | (mask << (watchnum*4+16));
82
83 return watchnum;
84 }
85