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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * xenfs.c - a filesystem for passing info between the a domain and4 * the hypervisor.5 *6 * 2008-10-07 Alex Zeffertt Replaced /proc/xen/xenbus with xenfs filesystem7 * and /proc/xen compatibility mount point.8 * Turned xenfs into a loadable module.9 */10 11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt12 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 28MODULE_DESCRIPTION("Xen filesystem");29MODULE_LICENSE("GPL");30 31static 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(buf, size, off, tmp, strlen(tmp));40}41 42static const struct file_operations capabilities_file_ops = {43 .read = capabilities_read,44 .llseek = default_llseek,45};46 47static 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_SYMS63 { "xensyms", &xensyms_ops, S_IRUSR},64#endif65 {""},66 };67 68 return simple_fill_super(sb, XENFS_SUPER_MAGIC,69 xen_initial_domain() ? xenfs_init_files : xenfs_files);70}71 72static int xenfs_get_tree(struct fs_context *fc)73{74 return get_tree_single(fc, xenfs_fill_super);75}76 77static const struct fs_context_operations xenfs_context_ops = {78 .get_tree = xenfs_get_tree,79};80 81static int xenfs_init_fs_context(struct fs_context *fc)82{83 fc->ops = &xenfs_context_ops;84 return 0;85}86 87static 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};93MODULE_ALIAS_FS("xenfs");94 95static int __init xenfs_init(void)96{97 if (xen_domain())98 return register_filesystem(&xenfs_type);99 100 return 0;101}102 103static void __exit xenfs_exit(void)104{105 if (xen_domain())106 unregister_filesystem(&xenfs_type);107}108 109module_init(xenfs_init);110module_exit(xenfs_exit);111 112