1 /* 2 * kernel/ksysfs.c - sysfs attributes in /sys/kernel, which 3 * are not related to any other subsystem 4 * 5 * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org> 6 * 7 * This file is release under the GPLv2 8 * 9 */ 10 11 #include <linux/kobject.h> 12 #include <linux/string.h> 13 #include <linux/sysfs.h> 14 #include <linux/module.h> 15 #include <linux/init.h> 16 #include <linux/kexec.h> 17 #include <linux/sched.h> 18 19 #define KERNEL_ATTR_RO(_name) \ 20 static struct subsys_attribute _name##_attr = __ATTR_RO(_name) 21 22 #define KERNEL_ATTR_RW(_name) \ 23 static struct subsys_attribute _name##_attr = \ 24 __ATTR(_name, 0644, _name##_show, _name##_store) 25 26 #if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET) 27 /* current uevent sequence number */ 28 static ssize_t uevent_seqnum_show(struct kset *kset, char *page) 29 { 30 return sprintf(page, "%llu\n", (unsigned long long)uevent_seqnum); 31 } 32 KERNEL_ATTR_RO(uevent_seqnum); 33 34 /* uevent helper program, used during early boo */ 35 static ssize_t uevent_helper_show(struct kset *kset, char *page) 36 { 37 return sprintf(page, "%s\n", uevent_helper); 38 } 39 static ssize_t uevent_helper_store(struct kset *kset, const char *page, size_t count) 40 { 41 if (count+1 > UEVENT_HELPER_PATH_LEN) 42 return -ENOENT; 43 memcpy(uevent_helper, page, count); 44 uevent_helper[count] = '\0'; 45 if (count && uevent_helper[count-1] == '\n') 46 uevent_helper[count-1] = '\0'; 47 return count; 48 } 49 KERNEL_ATTR_RW(uevent_helper); 50 #endif 51 52 #ifdef CONFIG_KEXEC 53 static ssize_t kexec_loaded_show(struct kset *kset, char *page) 54 { 55 return sprintf(page, "%d\n", !!kexec_image); 56 } 57 KERNEL_ATTR_RO(kexec_loaded); 58 59 static ssize_t kexec_crash_loaded_show(struct kset *kset, char *page) 60 { 61 return sprintf(page, "%d\n", !!kexec_crash_image); 62 } 63 KERNEL_ATTR_RO(kexec_crash_loaded); 64 #endif /* CONFIG_KEXEC */ 65 66 /* 67 * Make /sys/kernel/notes give the raw contents of our kernel .notes section. 68 */ 69 extern const void __start_notes __attribute__((weak)); 70 extern const void __stop_notes __attribute__((weak)); 71 #define notes_size (&__stop_notes - &__start_notes) 72 73 static ssize_t notes_read(struct kobject *kobj, struct bin_attribute *bin_attr, 74 char *buf, loff_t off, size_t count) 75 { 76 memcpy(buf, &__start_notes + off, count); 77 return count; 78 } 79 80 static struct bin_attribute notes_attr = { 81 .attr = { 82 .name = "notes", 83 .mode = S_IRUGO, 84 }, 85 .read = ¬es_read, 86 }; 87 88 decl_subsys(kernel, NULL, NULL); 89 EXPORT_SYMBOL_GPL(kernel_subsys); 90 91 static struct attribute * kernel_attrs[] = { 92 #if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET) 93 &uevent_seqnum_attr.attr, 94 &uevent_helper_attr.attr, 95 #endif 96 #ifdef CONFIG_KEXEC 97 &kexec_loaded_attr.attr, 98 &kexec_crash_loaded_attr.attr, 99 #endif 100 NULL 101 }; 102 103 static struct attribute_group kernel_attr_group = { 104 .attrs = kernel_attrs, 105 }; 106 107 static int __init ksysfs_init(void) 108 { 109 int error = subsystem_register(&kernel_subsys); 110 if (!error) 111 error = sysfs_create_group(&kernel_subsys.kobj, 112 &kernel_attr_group); 113 114 if (!error && notes_size > 0) { 115 notes_attr.size = notes_size; 116 error = sysfs_create_bin_file(&kernel_subsys.kobj, 117 ¬es_attr); 118 } 119 120 /* 121 * Create "/sys/kernel/uids" directory and corresponding root user's 122 * directory under it. 123 */ 124 if (!error) 125 error = uids_kobject_init(); 126 127 return error; 128 } 129 130 core_initcall(ksysfs_init); 131