1 /* 2 * xenfs.c - a filesystem for passing info between the a domain and 3 * the hypervisor. 4 * 5 * 2008-10-07 Alex Zeffertt Replaced /proc/xen/xenbus with xenfs filesystem 6 * and /proc/xen compatibility mount point. 7 * Turned xenfs into a loadable module. 8 */ 9 10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 11 12 #include <linux/kernel.h> 13 #include <linux/errno.h> 14 #include <linux/module.h> 15 #include <linux/fs.h> 16 #include <linux/magic.h> 17 18 #include <xen/xen.h> 19 #include <xen/xenbus.h> 20 21 #include "xenfs.h" 22 #include "../privcmd.h" 23 24 #include <asm/xen/hypervisor.h> 25 26 MODULE_DESCRIPTION("Xen filesystem"); 27 MODULE_LICENSE("GPL"); 28 29 static ssize_t capabilities_read(struct file *file, char __user *buf, 30 size_t size, loff_t *off) 31 { 32 char *tmp = ""; 33 34 if (xen_initial_domain()) 35 tmp = "control_d\n"; 36 37 return simple_read_from_buffer(buf, size, off, tmp, strlen(tmp)); 38 } 39 40 static const struct file_operations capabilities_file_ops = { 41 .read = capabilities_read, 42 .llseek = default_llseek, 43 }; 44 45 static int xenfs_fill_super(struct super_block *sb, void *data, int silent) 46 { 47 static struct tree_descr xenfs_files[] = { 48 [2] = { "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR }, 49 { "capabilities", &capabilities_file_ops, S_IRUGO }, 50 { "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR }, 51 {""}, 52 }; 53 54 static struct tree_descr xenfs_init_files[] = { 55 [2] = { "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR }, 56 { "capabilities", &capabilities_file_ops, S_IRUGO }, 57 { "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR }, 58 { "xsd_kva", &xsd_kva_file_ops, S_IRUSR|S_IWUSR}, 59 { "xsd_port", &xsd_port_file_ops, S_IRUSR|S_IWUSR}, 60 #ifdef CONFIG_XEN_SYMS 61 { "xensyms", &xensyms_ops, S_IRUSR}, 62 #endif 63 {""}, 64 }; 65 66 return simple_fill_super(sb, XENFS_SUPER_MAGIC, 67 xen_initial_domain() ? xenfs_init_files : xenfs_files); 68 } 69 70 static struct dentry *xenfs_mount(struct file_system_type *fs_type, 71 int flags, const char *dev_name, 72 void *data) 73 { 74 return mount_single(fs_type, flags, data, xenfs_fill_super); 75 } 76 77 static struct file_system_type xenfs_type = { 78 .owner = THIS_MODULE, 79 .name = "xenfs", 80 .mount = xenfs_mount, 81 .kill_sb = kill_litter_super, 82 }; 83 MODULE_ALIAS_FS("xenfs"); 84 85 static int __init xenfs_init(void) 86 { 87 if (xen_domain()) 88 return register_filesystem(&xenfs_type); 89 90 pr_info("not registering filesystem on non-xen platform\n"); 91 return 0; 92 } 93 94 static void __exit xenfs_exit(void) 95 { 96 if (xen_domain()) 97 unregister_filesystem(&xenfs_type); 98 } 99 100 module_init(xenfs_init); 101 module_exit(xenfs_exit); 102 103