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
22static char *cmdline;
23static struct cmdline_parts *bdev_parts;
24
25static int add_part(int slot, struct cmdline_subpart *subpart, void *param)
26{
27	int label_min;
28	struct partition_meta_info *info;
29	char tmp[sizeof(info->volname) + 4];
30	struct parsed_partitions *state = (struct parsed_partitions *)param;
31
32	if (slot >= state->limit)
33		return 1;
34
35	put_partition(state, slot, subpart->from >> 9,
36		      subpart->size >> 9);
37
38	info = &state->parts[slot].info;
39
40	label_min = min_t(int, sizeof(info->volname) - 1,
41			  sizeof(subpart->name));
42	strncpy(info->volname, subpart->name, label_min);
43	info->volname[label_min] = '\0';
44
45	snprintf(tmp, sizeof(tmp), "(%s)", info->volname);
46	strlcat(state->pp_buf, tmp, PAGE_SIZE);
47
48	state->parts[slot].has_info = true;
49
50	return 0;
51}
52
53static int __init cmdline_parts_setup(char *s)
54{
55	cmdline = s;
56	return 1;
57}
58__setup("blkdevparts=", cmdline_parts_setup);
59
60static bool has_overlaps(sector_t from, sector_t size,
61			 sector_t from2, sector_t size2)
62{
63	sector_t end = from + size;
64	sector_t end2 = from2 + size2;
65
66	if (from >= from2 && from < end2)
67		return true;
68
69	if (end > from2 && end <= end2)
70		return true;
71
72	if (from2 >= from && from2 < end)
73		return true;
74
75	if (end2 > from && end2 <= end)
76		return true;
77
78	return false;
79}
80
81static inline void overlaps_warns_header(void)
82{
83	pr_warn("Overlapping partitions are used in command line partitions.");
84	pr_warn("Don't use filesystems on overlapping partitions:");
85}
86
87static void cmdline_parts_verifier(int slot, struct parsed_partitions *state)
88{
89	int i;
90	bool header = true;
91
92	for (; slot < state->limit && state->parts[slot].has_info; slot++) {
93		for (i = slot+1; i < state->limit && state->parts[i].has_info;
94		     i++) {
95			if (has_overlaps(state->parts[slot].from,
96					 state->parts[slot].size,
97					 state->parts[i].from,
98					 state->parts[i].size)) {
99				if (header) {
100					header = false;
101					overlaps_warns_header();
102				}
103				pr_warn("%s[%llu,%llu] overlaps with "
104					"%s[%llu,%llu].",
105					state->parts[slot].info.volname,
106					(u64)state->parts[slot].from << 9,
107					(u64)state->parts[slot].size << 9,
108					state->parts[i].info.volname,
109					(u64)state->parts[i].from << 9,
110					(u64)state->parts[i].size << 9);
111			}
112		}
113	}
114}
115
116/*
117 * Purpose: allocate cmdline partitions.
118 * Returns:
119 * -1 if unable to read the partition table
120 *  0 if this isn't our partition table
121 *  1 if successful
122 */
123int cmdline_partition(struct parsed_partitions *state)
124{
125	sector_t disk_size;
126	char bdev[BDEVNAME_SIZE];
127	struct cmdline_parts *parts;
128
129	if (cmdline) {
130		if (bdev_parts)
131			cmdline_parts_free(&bdev_parts);
132
133		if (cmdline_parts_parse(&bdev_parts, cmdline)) {
134			cmdline = NULL;
135			return -1;
136		}
137		cmdline = NULL;
138	}
139
140	if (!bdev_parts)
141		return 0;
142
143	bdevname(state->bdev, bdev);
144	parts = cmdline_parts_find(bdev_parts, bdev);
145	if (!parts)
146		return 0;
147
148	disk_size = get_capacity(state->bdev->bd_disk) << 9;
149
150	cmdline_parts_set(parts, disk_size, 1, add_part, (void *)state);
151	cmdline_parts_verifier(1, state);
152
153	strlcat(state->pp_buf, "\n", PAGE_SIZE);
154
155	return 1;
156}
157