1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2013 HUAWEI
4 * Author: Cai Zhiyong <caizhiyong@huawei.com>
5 *
6 * Read block device partition table from the command line.
7 * Typically used for fixed block (eMMC) embedded devices.
8 * It has no MBR, so saves storage space. Bootloader can be easily accessed
9 * by absolute address of data on the block device.
10 * Users can easily change the partition.
11 *
12 * The format for the command line is just like mtdparts.
13 *
14 * For further information, see "Documentation/block/cmdline-partition.txt"
15 *
16 */
17
18 #include <linux/cmdline-parser.h>
19
20 #include "check.h"
21 #include "cmdline.h"
22
23 static char *cmdline;
24 static struct cmdline_parts *bdev_parts;
25
add_part(int slot,struct cmdline_subpart * subpart,void * param)26 static int add_part(int slot, struct cmdline_subpart *subpart, void *param)
27 {
28 int label_min;
29 struct partition_meta_info *info;
30 char tmp[sizeof(info->volname) + 4];
31 struct parsed_partitions *state = (struct parsed_partitions *)param;
32
33 if (slot >= state->limit)
34 return 1;
35
36 put_partition(state, slot, subpart->from >> 9,
37 subpart->size >> 9);
38
39 info = &state->parts[slot].info;
40
41 label_min = min_t(int, sizeof(info->volname) - 1,
42 sizeof(subpart->name));
43 strncpy(info->volname, subpart->name, label_min);
44 info->volname[label_min] = '\0';
45
46 snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
47 strlcat(state->pp_buf, tmp, PAGE_SIZE);
48
49 state->parts[slot].has_info = true;
50
51 return 0;
52 }
53
cmdline_parts_setup(char * s)54 static int __init cmdline_parts_setup(char *s)
55 {
56 cmdline = s;
57 return 1;
58 }
59 __setup("blkdevparts=", cmdline_parts_setup);
60
has_overlaps(sector_t from,sector_t size,sector_t from2,sector_t size2)61 static bool has_overlaps(sector_t from, sector_t size,
62 sector_t from2, sector_t size2)
63 {
64 sector_t end = from + size;
65 sector_t end2 = from2 + size2;
66
67 if (from >= from2 && from < end2)
68 return true;
69
70 if (end > from2 && end <= end2)
71 return true;
72
73 if (from2 >= from && from2 < end)
74 return true;
75
76 if (end2 > from && end2 <= end)
77 return true;
78
79 return false;
80 }
81
overlaps_warns_header(void)82 static inline void overlaps_warns_header(void)
83 {
84 pr_warn("Overlapping partitions are used in command line partitions.");
85 pr_warn("Don't use filesystems on overlapping partitions:");
86 }
87
cmdline_parts_verifier(int slot,struct parsed_partitions * state)88 static void cmdline_parts_verifier(int slot, struct parsed_partitions *state)
89 {
90 int i;
91 bool header = true;
92
93 for (; slot < state->limit && state->parts[slot].has_info; slot++) {
94 for (i = slot+1; i < state->limit && state->parts[i].has_info;
95 i++) {
96 if (has_overlaps(state->parts[slot].from,
97 state->parts[slot].size,
98 state->parts[i].from,
99 state->parts[i].size)) {
100 if (header) {
101 header = false;
102 overlaps_warns_header();
103 }
104 pr_warn("%s[%llu,%llu] overlaps with "
105 "%s[%llu,%llu].",
106 state->parts[slot].info.volname,
107 (u64)state->parts[slot].from << 9,
108 (u64)state->parts[slot].size << 9,
109 state->parts[i].info.volname,
110 (u64)state->parts[i].from << 9,
111 (u64)state->parts[i].size << 9);
112 }
113 }
114 }
115 }
116
117 /*
118 * Purpose: allocate cmdline partitions.
119 * Returns:
120 * -1 if unable to read the partition table
121 * 0 if this isn't our partition table
122 * 1 if successful
123 */
cmdline_partition(struct parsed_partitions * state)124 int cmdline_partition(struct parsed_partitions *state)
125 {
126 sector_t disk_size;
127 char bdev[BDEVNAME_SIZE];
128 struct cmdline_parts *parts;
129
130 if (cmdline) {
131 if (bdev_parts)
132 cmdline_parts_free(&bdev_parts);
133
134 if (cmdline_parts_parse(&bdev_parts, cmdline)) {
135 cmdline = NULL;
136 return -1;
137 }
138 cmdline = NULL;
139 }
140
141 if (!bdev_parts)
142 return 0;
143
144 bdevname(state->bdev, bdev);
145 parts = cmdline_parts_find(bdev_parts, bdev);
146 if (!parts)
147 return 0;
148
149 disk_size = get_capacity(state->bdev->bd_disk) << 9;
150
151 cmdline_parts_set(parts, disk_size, 1, add_part, (void *)state);
152 cmdline_parts_verifier(1, state);
153
154 strlcat(state->pp_buf, "\n", PAGE_SIZE);
155
156 return 1;
157 }
158