xref: /openbmc/linux/block/partitions/cmdline.c (revision b830f94f)
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.rst"
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 
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 
54 static int __init cmdline_parts_setup(char *s)
55 {
56 	cmdline = s;
57 	return 1;
58 }
59 __setup("blkdevparts=", cmdline_parts_setup);
60 
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 
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 
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  */
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