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 18 #define KERNEL_ATTR_RO(_name) \ 19 static struct subsys_attribute _name##_attr = __ATTR_RO(_name) 20 21 #define KERNEL_ATTR_RW(_name) \ 22 static struct subsys_attribute _name##_attr = \ 23 __ATTR(_name, 0644, _name##_show, _name##_store) 24 25 #if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET) 26 /* current uevent sequence number */ 27 static ssize_t uevent_seqnum_show(struct kset *kset, char *page) 28 { 29 return sprintf(page, "%llu\n", (unsigned long long)uevent_seqnum); 30 } 31 KERNEL_ATTR_RO(uevent_seqnum); 32 33 /* uevent helper program, used during early boo */ 34 static ssize_t uevent_helper_show(struct kset *kset, char *page) 35 { 36 return sprintf(page, "%s\n", uevent_helper); 37 } 38 static ssize_t uevent_helper_store(struct kset *kset, const char *page, size_t count) 39 { 40 if (count+1 > UEVENT_HELPER_PATH_LEN) 41 return -ENOENT; 42 memcpy(uevent_helper, page, count); 43 uevent_helper[count] = '\0'; 44 if (count && uevent_helper[count-1] == '\n') 45 uevent_helper[count-1] = '\0'; 46 return count; 47 } 48 KERNEL_ATTR_RW(uevent_helper); 49 #endif 50 51 #ifdef CONFIG_KEXEC 52 static ssize_t kexec_loaded_show(struct kset *kset, char *page) 53 { 54 return sprintf(page, "%d\n", !!kexec_image); 55 } 56 KERNEL_ATTR_RO(kexec_loaded); 57 58 static ssize_t kexec_crash_loaded_show(struct kset *kset, char *page) 59 { 60 return sprintf(page, "%d\n", !!kexec_crash_image); 61 } 62 KERNEL_ATTR_RO(kexec_crash_loaded); 63 #endif /* CONFIG_KEXEC */ 64 65 /* 66 * Make /sys/kernel/notes give the raw contents of our kernel .notes section. 67 */ 68 extern const void __start_notes __attribute__((weak)); 69 extern const void __stop_notes __attribute__((weak)); 70 #define notes_size (&__stop_notes - &__start_notes) 71 72 static ssize_t notes_read(struct kobject *kobj, struct bin_attribute *bin_attr, 73 char *buf, loff_t off, size_t count) 74 { 75 memcpy(buf, &__start_notes + off, count); 76 return count; 77 } 78 79 static struct bin_attribute notes_attr = { 80 .attr = { 81 .name = "notes", 82 .mode = S_IRUGO, 83 }, 84 .read = ¬es_read, 85 }; 86 87 decl_subsys(kernel, NULL, NULL); 88 EXPORT_SYMBOL_GPL(kernel_subsys); 89 90 static struct attribute * kernel_attrs[] = { 91 #if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET) 92 &uevent_seqnum_attr.attr, 93 &uevent_helper_attr.attr, 94 #endif 95 #ifdef CONFIG_KEXEC 96 &kexec_loaded_attr.attr, 97 &kexec_crash_loaded_attr.attr, 98 #endif 99 NULL 100 }; 101 102 static struct attribute_group kernel_attr_group = { 103 .attrs = kernel_attrs, 104 }; 105 106 static int __init ksysfs_init(void) 107 { 108 int error = subsystem_register(&kernel_subsys); 109 if (!error) 110 error = sysfs_create_group(&kernel_subsys.kobj, 111 &kernel_attr_group); 112 113 if (!error && notes_size > 0) { 114 notes_attr.size = notes_size; 115 error = sysfs_create_bin_file(&kernel_subsys.kobj, 116 ¬es_attr); 117 } 118 119 return error; 120 } 121 122 core_initcall(ksysfs_init); 123