1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 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 <machine/reg.h> 32 #include <machine/sysarch.h> 33 34 int 35 i386_set_watch(int watchnum, unsigned int watchaddr, int size, 36 int access, struct dbreg * d) 37 { 38 int i; 39 unsigned int mask; 40 41 if (watchnum == -1) { 42 for (i = 0, mask = 0x3; i < 4; i++, mask <<= 2) 43 if ((DBREG_DRX(d,7) & mask) == 0) 44 break; 45 if (i < 4) 46 watchnum = i; 47 else 48 return -1; 49 } 50 51 switch (access) { 52 case DBREG_DR7_EXEC: 53 size = 1; /* size must be 1 for an execution breakpoint */ 54 /* fall through */ 55 case DBREG_DR7_WRONLY: 56 case DBREG_DR7_RDWR: 57 break; 58 default : return -1; break; 59 } 60 61 /* 62 * we can watch a 1, 2, or 4 byte sized location 63 */ 64 switch (size) { 65 case 1 : mask = 0x00; break; 66 case 2 : mask = 0x01 << 2; break; 67 case 4 : mask = 0x03 << 2; break; 68 default : return -1; break; 69 } 70 71 mask |= access; 72 73 /* clear the bits we are about to affect */ 74 DBREG_DRX(d,7) &= ~((0x3 << (watchnum*2)) | (0x0f << (watchnum*4+16))); 75 76 /* set drN register to the address, N=watchnum */ 77 DBREG_DRX(d,watchnum) = watchaddr; 78 79 /* enable the watchpoint */ 80 DBREG_DRX(d,7) |= (0x2 << (watchnum*2)) | (mask << (watchnum*4+16)); 81 82 return watchnum; 83 } 84