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
35int
36i386_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