1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License").  You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22/*
23 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27#pragma ident	"%Z%%M%	%I%	%E% SMI"
28
29#include <sys/param.h>
30
31static uint_t		*mddb_crctab = NULL;
32
33#ifndef _KERNEL
34#include <meta.h>
35#include <assert.h>
36#define	MD_ZALLOC(x)	Zalloc(x)
37#define	MD_FREE(x, y)	Free(x)
38#else	/* _KERNEL */
39#define	MD_ZALLOC(x)	kmem_zalloc(x, KM_SLEEP)
40#define	MD_FREE(x, y)	kmem_free(x, y)
41#include <sys/thread.h>
42#include <sys/types.h>
43#include <sys/kmem.h>
44#include <sys/debug.h>
45#endif	/* ! _KERNEL */
46#include <sys/lvm/md_crc.h>
47
48#define	MDDB_CRCMAGIC 987654
49
50static uint_t *
51crcgentab(void)
52{
53	int	b, i;
54	uint_t		v;
55	uint_t		*crctab;
56	uint_t		poly = 0x04c11db7;
57
58	crctab = (uint_t *)MD_ZALLOC(256 * sizeof (int));
59	for (b = 0; b < 256; b++) {
60		for (v = b << (24), i = 0; i < 8; i++) {
61			if (v & ((unsigned int)1 << 31)) {
62				v = (v << 1) ^ poly;
63			} else {
64				v = v << 1;
65			}
66		}
67		crctab[b] = v;
68	}
69	return (crctab);
70}
71
72/*
73 * crc function that allows  a number of areas to be skipped (ignored)
74 * during the crc computation.  The result area of the record is also ignored
75 * during the crc computation.  Ignored areas are used for data that may
76 * be changed after record has been crcgen'd, but before the data has been
77 * written to disk or for when a multi-owner diskset may have multiple
78 * nodes writing the same record data with the exception of the timestamp field.
79 * The list of skip areas must be in ascending order of offset and if any
80 * areas overlap, the list will be modified.
81 */
82uint_t
83crcfunc(
84	uint_t	check,
85	uchar_t *record,	/* record to be check-summed */
86	uint_t	*result,	/* put check-sum here(really u_long) */
87	size_t	size,		/* size of record in bytes */
88	crc_skip_t *skip	/* list of areas to skip */
89)
90{
91	uint_t		newcrc;
92	uint_t		*crctab;
93	uchar_t		*recaddr;
94	crc_skip_t	*s, *p;
95
96	/*
97	 * Check skip areas to see if they overlap (this should never happen,
98	 * but is handled just in case something changes in the future).
99	 * Also the skip list must be in ascending order of offset, assert
100	 * error if this is not the case.
101	 * If any 2 adjacent skip areas overlap, then the skip areas will
102	 * be merged into 1 skip area and the other skip area is freed.
103	 * If any 2 adjacent skip areas abut (border) each other, then skip
104	 * areas are not merged, but are left as 2 independent skip areas.
105	 * If the skip areas are identical, no change is made to either skip
106	 * area since this is handled later.
107	 */
108	if (skip) {
109		p = NULL;
110		for (s = skip; s != NULL; s = s->skip_next) {
111			if (p == NULL) {
112				p = s;
113				continue;
114			}
115#ifdef _KERNEL
116			ASSERT(s->skip_offset > p->skip_offset);
117#else
118			assert(s->skip_offset > p->skip_offset);
119#endif
120			if ((p->skip_offset + p->skip_size) > s->skip_offset) {
121				/*
122				 * Current area overlaps previous, modify
123				 * previous area and release current
124				 */
125				p->skip_size += s->skip_size - (p->skip_offset
126				    + p->skip_size - s->skip_offset);
127				p->skip_next = s->skip_next;
128				MD_FREE(s, sizeof (crc_skip_t));
129				s = p;
130			}
131			p = s;
132		}
133	}
134
135	if (! mddb_crctab)
136		mddb_crctab = crcgentab();
137
138	crctab = mddb_crctab;
139	newcrc = MDDB_CRCMAGIC;
140
141	recaddr = record;
142	s = skip;
143	while (size--) {
144		/* Skip the result pointer */
145		if (record == (uchar_t *)result) {
146			record += sizeof (uint_t);
147			size -= (sizeof (uint_t) - 1);
148			continue;
149		}
150
151		/*
152		 * Skip over next skip area if non-null
153		 */
154		if ((s) && (record == (recaddr + (s->skip_offset)))) {
155			record += s->skip_size;
156			size -= (s->skip_size - 1);
157			s = s->skip_next;
158			continue;
159		}
160
161		newcrc = (newcrc << 8) ^ crctab[(newcrc >> 24) ^ *record++];
162	}
163
164	/* If we are checking, we either get a 0 - OK, or 1 - Not OK result */
165	if (check) {
166		if (*((uint_t *)result) == newcrc)
167			return (0);
168		return (1);
169	}
170
171	/*
172	 * If we are generating, we stuff the result, if we have a result
173	 * pointer, and return the value.
174	 */
175	if (result != NULL)
176		*((uint_t *)result) = newcrc;
177	return (newcrc);
178}
179
180void
181crcfreetab(void)
182{
183	if (mddb_crctab) {
184		MD_FREE((caddr_t)mddb_crctab, 256 * sizeof (int));
185		mddb_crctab = NULL;
186	}
187}
188