1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * xenfs.c - a filesystem for passing info between the a domain and |
4 | * the hypervisor. |
5 | * |
6 | * 2008-10-07 Alex Zeffertt Replaced /proc/xen/xenbus with xenfs filesystem |
7 | * and /proc/xen compatibility mount point. |
8 | * Turned xenfs into a loadable module. |
9 | */ |
10 | |
11 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
12 | |
13 | #include <linux/kernel.h> |
14 | #include <linux/errno.h> |
15 | #include <linux/module.h> |
16 | #include <linux/fs.h> |
17 | #include <linux/fs_context.h> |
18 | #include <linux/magic.h> |
19 | |
20 | #include <xen/xen.h> |
21 | #include <xen/xenbus.h> |
22 | |
23 | #include "xenfs.h" |
24 | #include "../privcmd.h" |
25 | |
26 | #include <asm/xen/hypervisor.h> |
27 | |
28 | MODULE_DESCRIPTION("Xen filesystem" ); |
29 | MODULE_LICENSE("GPL" ); |
30 | |
31 | static ssize_t capabilities_read(struct file *file, char __user *buf, |
32 | size_t size, loff_t *off) |
33 | { |
34 | char *tmp = "" ; |
35 | |
36 | if (xen_initial_domain()) |
37 | tmp = "control_d\n" ; |
38 | |
39 | return simple_read_from_buffer(to: buf, count: size, ppos: off, from: tmp, strlen(tmp)); |
40 | } |
41 | |
42 | static const struct file_operations capabilities_file_ops = { |
43 | .read = capabilities_read, |
44 | .llseek = default_llseek, |
45 | }; |
46 | |
47 | static int xenfs_fill_super(struct super_block *sb, struct fs_context *fc) |
48 | { |
49 | static const struct tree_descr xenfs_files[] = { |
50 | [2] = { "xenbus" , &xen_xenbus_fops, S_IRUSR|S_IWUSR }, |
51 | { "capabilities" , &capabilities_file_ops, S_IRUGO }, |
52 | { "privcmd" , &xen_privcmd_fops, S_IRUSR|S_IWUSR }, |
53 | {"" }, |
54 | }; |
55 | |
56 | static const struct tree_descr xenfs_init_files[] = { |
57 | [2] = { "xenbus" , &xen_xenbus_fops, S_IRUSR|S_IWUSR }, |
58 | { "capabilities" , &capabilities_file_ops, S_IRUGO }, |
59 | { "privcmd" , &xen_privcmd_fops, S_IRUSR|S_IWUSR }, |
60 | { "xsd_kva" , &xsd_kva_file_ops, S_IRUSR|S_IWUSR}, |
61 | { "xsd_port" , &xsd_port_file_ops, S_IRUSR|S_IWUSR}, |
62 | #ifdef CONFIG_XEN_SYMS |
63 | { "xensyms" , &xensyms_ops, S_IRUSR}, |
64 | #endif |
65 | {"" }, |
66 | }; |
67 | |
68 | return simple_fill_super(sb, XENFS_SUPER_MAGIC, |
69 | xen_initial_domain() ? xenfs_init_files : xenfs_files); |
70 | } |
71 | |
72 | static int xenfs_get_tree(struct fs_context *fc) |
73 | { |
74 | return get_tree_single(fc, fill_super: xenfs_fill_super); |
75 | } |
76 | |
77 | static const struct fs_context_operations xenfs_context_ops = { |
78 | .get_tree = xenfs_get_tree, |
79 | }; |
80 | |
81 | static int xenfs_init_fs_context(struct fs_context *fc) |
82 | { |
83 | fc->ops = &xenfs_context_ops; |
84 | return 0; |
85 | } |
86 | |
87 | static struct file_system_type xenfs_type = { |
88 | .owner = THIS_MODULE, |
89 | .name = "xenfs" , |
90 | .init_fs_context = xenfs_init_fs_context, |
91 | .kill_sb = kill_litter_super, |
92 | }; |
93 | MODULE_ALIAS_FS("xenfs" ); |
94 | |
95 | static int __init xenfs_init(void) |
96 | { |
97 | if (xen_domain()) |
98 | return register_filesystem(&xenfs_type); |
99 | |
100 | return 0; |
101 | } |
102 | |
103 | static void __exit xenfs_exit(void) |
104 | { |
105 | if (xen_domain()) |
106 | unregister_filesystem(&xenfs_type); |
107 | } |
108 | |
109 | module_init(xenfs_init); |
110 | module_exit(xenfs_exit); |
111 | |
112 | |