1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright 2000  Brian S. Dean <bsd@bsdhome.com>
5 * All Rights Reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY BRIAN S. DEAN ``AS IS'' AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
20 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL BRIAN S. DEAN BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
22 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
23 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
24 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
25 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
27 * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
28 * DAMAGE.
29 */
30
31#include <sys/cdefs.h>
32__FBSDID("$FreeBSD$");
33
34#include <machine/reg.h>
35#include <machine/sysarch.h>
36
37int
38i386_set_watch(int watchnum, unsigned int watchaddr, int size,
39               int access, struct dbreg * d)
40{
41	int i;
42	unsigned int mask;
43
44	if (watchnum == -1) {
45		for (i = 0, mask = 0x3; i < 4; i++, mask <<= 2)
46			if ((DBREG_DRX(d,7) & mask) == 0)
47				break;
48		if (i < 4)
49			watchnum = i;
50		else
51			return -1;
52	}
53
54	switch (access) {
55	case DBREG_DR7_EXEC:
56		size = 1; /* size must be 1 for an execution breakpoint */
57		/* fall through */
58	case DBREG_DR7_WRONLY:
59	case DBREG_DR7_RDWR:
60		break;
61	default : return -1; break;
62	}
63
64	/*
65	 * we can watch a 1, 2, or 4 byte sized location
66	 */
67	switch (size) {
68	case 1  : mask = 0x00; break;
69	case 2  : mask = 0x01 << 2; break;
70	case 4  : mask = 0x03 << 2; break;
71	default : return -1; break;
72	}
73
74	mask |= access;
75
76	/* clear the bits we are about to affect */
77	DBREG_DRX(d,7) &= ~((0x3 << (watchnum*2)) | (0x0f << (watchnum*4+16)));
78
79	/* set drN register to the address, N=watchnum */
80	DBREG_DRX(d,watchnum) = watchaddr;
81
82	/* enable the watchpoint */
83	DBREG_DRX(d,7) |= (0x2 << (watchnum*2)) | (mask << (watchnum*4+16));
84
85	return watchnum;
86}
87