1 /* $NetBSD: disksubr.c,v 1.42 2019/04/03 22:10:49 christos Exp $ */
2
3 /*
4 * Copyright (c) 1994, 1995, 1996 Carnegie-Mellon University.
5 * All rights reserved.
6 *
7 * Authors: Keith Bostic, Chris G. Demetriou
8 *
9 * Permission to use, copy, modify and distribute this software and
10 * its documentation is hereby granted, provided that both the copyright
11 * notice and this permission notice appear in all copies of the
12 * software, derivative works or modified versions, and any portions
13 * thereof, and that both notices appear in supporting documentation.
14 *
15 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
16 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
17 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
18 *
19 * Carnegie Mellon requests users of this software to return to
20 *
21 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
22 * School of Computer Science
23 * Carnegie Mellon University
24 * Pittsburgh PA 15213-3890
25 *
26 * any improvements or extensions that they make and grant Carnegie the
27 * rights to redistribute these changes.
28 */
29
30 #include <sys/cdefs.h> /* RCS ID & Copyright macro defns */
31
32 __KERNEL_RCSID(0, "$NetBSD: disksubr.c,v 1.42 2019/04/03 22:10:49 christos Exp $");
33
34 #include <sys/param.h>
35 #include <sys/systm.h>
36 #include <sys/buf.h>
37 #include <sys/ioccom.h>
38 #include <sys/device.h>
39 #include <sys/disklabel.h>
40 #include <sys/disk.h>
41
42 #include <machine/cpu.h>
43 #include <machine/autoconf.h>
44
45 extern device_t bootdv;
46
47 /*
48 * Attempt to read a disk label from a device
49 * using the indicated strategy routine.
50 * The label must be partly set up before this:
51 * secpercyl and anything required in the strategy routine
52 * (e.g., sector size) must be filled in before calling us.
53 * Returns null on success and an error string on failure.
54 */
55 const char *
readdisklabel(dev_t dev,void (* strat)(struct buf *),struct disklabel * lp,struct cpu_disklabel * clp)56 readdisklabel(dev_t dev, void (*strat)(struct buf *), struct disklabel *lp, struct cpu_disklabel *clp)
57 {
58 struct buf *bp;
59 struct disklabel *dlp;
60 struct dkbad *bdp;
61 const char *msg = NULL;
62 int i;
63
64 /* minimal requirements for archtypal disk label */
65 if (lp->d_secsize == 0)
66 lp->d_secsize = DEV_BSIZE;
67 if (lp->d_secperunit == 0)
68 lp->d_secperunit = 0x1fffffff;
69 lp->d_npartitions = RAW_PART + 1;
70 if (lp->d_partitions[RAW_PART].p_size == 0)
71 lp->d_partitions[RAW_PART].p_size = lp->d_secperunit;
72 lp->d_partitions[RAW_PART].p_offset = 0;
73
74 /* obtain buffer to probe drive with */
75 bp = geteblk((int)lp->d_secsize);
76
77 /* next, dig out disk label */
78 bp->b_dev = dev;
79 bp->b_blkno = LABELSECTOR;
80 bp->b_cylinder = 0;
81 bp->b_bcount = lp->d_secsize;
82 bp->b_flags |= B_READ;
83 (*strat)(bp);
84
85 /* if successful, locate disk label within block and validate */
86 if (biowait(bp)) {
87 msg = "disk label read error";
88 goto done;
89 }
90
91 dlp = (struct disklabel *)((char *)bp->b_data + LABELOFFSET);
92 if (dlp->d_magic == DISKMAGIC) {
93 if (dkcksum(dlp))
94 msg = "NetBSD disk label corrupted";
95 else
96 *lp = *dlp;
97 } else
98 msg = "no disk label";
99 if (msg)
100 goto done;
101
102 /* obtain bad sector table if requested and present */
103 if (clp && (bdp = &clp->bad) != NULL && (lp->d_flags & D_BADSECT)) {
104 struct dkbad *db;
105
106 i = 0;
107 do {
108 /* read a bad sector table */
109 bp->b_oflags &= ~BO_DONE;
110 bp->b_flags |= B_READ;
111 bp->b_blkno = lp->d_secperunit - lp->d_nsectors + i;
112 if (lp->d_secsize > DEV_BSIZE)
113 bp->b_blkno *= lp->d_secsize / DEV_BSIZE;
114 else
115 bp->b_blkno /= DEV_BSIZE / lp->d_secsize;
116 bp->b_bcount = lp->d_secsize;
117 bp->b_cylinder = lp->d_ncylinders - 1;
118 (*strat)(bp);
119
120 /* if successful, validate, otherwise try another */
121 if (biowait(bp)) {
122 msg = "bad sector table I/O error";
123 } else {
124 db = (struct dkbad *)(bp->b_data);
125 #define DKBAD_MAGIC 0x4321
126 if (db->bt_mbz == 0
127 && db->bt_flag == DKBAD_MAGIC) {
128 msg = NULL;
129 *bdp = *db;
130 break;
131 } else
132 msg = "bad sector table corrupted";
133 }
134 } while (bp->b_error != 0 && (i += 2) < 10 &&
135 i < lp->d_nsectors);
136 }
137
138 done:
139 brelse(bp, 0);
140 return (msg);
141 }
142
143 /*
144 * Write disk label back to device after modification.
145 * This means write out the rigid disk blocks to represent the
146 * label. Hope the user was careful.
147 */
148 int
writedisklabel(dev_t dev,void (* strat)(struct buf *),struct disklabel * lp,struct cpu_disklabel * clp)149 writedisklabel(dev_t dev, void (*strat)(struct buf *), struct disklabel *lp, struct cpu_disklabel *clp)
150 {
151 struct buf *bp;
152 struct disklabel *dlp;
153 int error = 0;
154
155 bp = geteblk((int)lp->d_secsize);
156 bp->b_dev = dev;
157 bp->b_blkno = LABELSECTOR;
158 bp->b_cylinder = 0;
159 bp->b_bcount = lp->d_secsize;
160 bp->b_flags |= B_READ; /* get current label */
161 (*strat)(bp);
162 if ((error = biowait(bp)) != 0)
163 goto done;
164
165 dlp = (struct disklabel *)((char *)bp->b_data + LABELOFFSET);
166 *dlp = *lp; /* struct assignment */
167
168 /*
169 * The Alpha requires that the boot block be checksummed.
170 * The first 63 8-bit quantites are summed into the 64th.
171 */
172 {
173 int i;
174 u_long *dp, sum;
175
176 dp = (u_long *)bp->b_data;
177 sum = 0;
178 for (i = 0; i < 63; i++)
179 sum += dp[i];
180 dp[63] = sum;
181 }
182
183 bp->b_flags &= ~B_READ;
184 bp->b_flags |= B_WRITE;
185 bp->b_oflags &= ~BO_DONE;
186 (*strat)(bp);
187 error = biowait(bp);
188
189 done:
190 brelse(bp, 0);
191 return (error);
192 }
193