1 | // SPDX-License-Identifier: GPL-2.0 |
2 | #include <linux/slab.h> |
3 | #include <linux/proc_fs.h> |
4 | #include <asm/setup.h> |
5 | #include <asm/types.h> |
6 | #include <asm/page.h> |
7 | |
8 | struct buffer { |
9 | size_t size; |
10 | char data[]; |
11 | }; |
12 | |
13 | static ssize_t atags_read(struct file *file, char __user *buf, |
14 | size_t count, loff_t *ppos) |
15 | { |
16 | struct buffer *b = pde_data(inode: file_inode(f: file)); |
17 | return simple_read_from_buffer(to: buf, count, ppos, from: b->data, available: b->size); |
18 | } |
19 | |
20 | static const struct proc_ops atags_proc_ops = { |
21 | .proc_read = atags_read, |
22 | .proc_lseek = default_llseek, |
23 | }; |
24 | |
25 | #define BOOT_PARAMS_SIZE 1536 |
26 | static char __initdata atags_copy[BOOT_PARAMS_SIZE]; |
27 | |
28 | void __init save_atags(const struct tag *tags) |
29 | { |
30 | memcpy(atags_copy, tags, sizeof(atags_copy)); |
31 | } |
32 | |
33 | static int __init init_atags_procfs(void) |
34 | { |
35 | /* |
36 | * This cannot go into save_atags() because kmalloc and proc don't work |
37 | * yet when it is called. |
38 | */ |
39 | struct proc_dir_entry *tags_entry; |
40 | struct tag *tag = (struct tag *)atags_copy; |
41 | struct buffer *b; |
42 | size_t size; |
43 | |
44 | if (tag->hdr.tag != ATAG_CORE) { |
45 | pr_info("No ATAGs?\n" ); |
46 | return -EINVAL; |
47 | } |
48 | |
49 | for (; tag->hdr.size; tag = tag_next(tag)) |
50 | ; |
51 | |
52 | /* include the terminating ATAG_NONE */ |
53 | size = (char *)tag - atags_copy + sizeof(struct tag_header); |
54 | |
55 | WARN_ON(tag->hdr.tag != ATAG_NONE); |
56 | |
57 | b = kmalloc(size: sizeof(*b) + size, GFP_KERNEL); |
58 | if (!b) |
59 | goto nomem; |
60 | |
61 | b->size = size; |
62 | memcpy(b->data, atags_copy, size); |
63 | |
64 | tags_entry = proc_create_data("atags" , 0400, NULL, &atags_proc_ops, b); |
65 | if (!tags_entry) |
66 | goto nomem; |
67 | |
68 | return 0; |
69 | |
70 | nomem: |
71 | kfree(objp: b); |
72 | pr_err("Exporting ATAGs: not enough memory\n" ); |
73 | |
74 | return -ENOMEM; |
75 | } |
76 | arch_initcall(init_atags_procfs); |
77 | |