1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * kernel/ksysfs.c - sysfs attributes in /sys/kernel, which 4 * are not related to any other subsystem 5 * 6 * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org> 7 */ 8 9 #include <asm/byteorder.h> 10 #include <linux/kobject.h> 11 #include <linux/string.h> 12 #include <linux/sysfs.h> 13 #include <linux/export.h> 14 #include <linux/init.h> 15 #include <linux/kexec.h> 16 #include <linux/profile.h> 17 #include <linux/stat.h> 18 #include <linux/sched.h> 19 #include <linux/capability.h> 20 #include <linux/compiler.h> 21 22 #include <linux/rcupdate.h> /* rcu_expedited and rcu_normal */ 23 24 #if defined(__LITTLE_ENDIAN) 25 #define CPU_BYTEORDER_STRING "little" 26 #elif defined(__BIG_ENDIAN) 27 #define CPU_BYTEORDER_STRING "big" 28 #else 29 #error Unknown byteorder 30 #endif 31 32 #define KERNEL_ATTR_RO(_name) \ 33 static struct kobj_attribute _name##_attr = __ATTR_RO(_name) 34 35 #define KERNEL_ATTR_RW(_name) \ 36 static struct kobj_attribute _name##_attr = __ATTR_RW(_name) 37 38 /* current uevent sequence number */ 39 static ssize_t uevent_seqnum_show(struct kobject *kobj, 40 struct kobj_attribute *attr, char *buf) 41 { 42 return sysfs_emit(buf, "%llu\n", (u64)atomic64_read(&uevent_seqnum)); 43 } 44 KERNEL_ATTR_RO(uevent_seqnum); 45 46 /* cpu byteorder */ 47 static ssize_t cpu_byteorder_show(struct kobject *kobj, 48 struct kobj_attribute *attr, char *buf) 49 { 50 return sysfs_emit(buf, "%s\n", CPU_BYTEORDER_STRING); 51 } 52 KERNEL_ATTR_RO(cpu_byteorder); 53 54 /* address bits */ 55 static ssize_t address_bits_show(struct kobject *kobj, 56 struct kobj_attribute *attr, char *buf) 57 { 58 return sysfs_emit(buf, "%zu\n", sizeof(void *) * 8 /* CHAR_BIT */); 59 } 60 KERNEL_ATTR_RO(address_bits); 61 62 #ifdef CONFIG_UEVENT_HELPER 63 /* uevent helper program, used during early boot */ 64 static ssize_t uevent_helper_show(struct kobject *kobj, 65 struct kobj_attribute *attr, char *buf) 66 { 67 return sysfs_emit(buf, "%s\n", uevent_helper); 68 } 69 static ssize_t uevent_helper_store(struct kobject *kobj, 70 struct kobj_attribute *attr, 71 const char *buf, size_t count) 72 { 73 if (count+1 > UEVENT_HELPER_PATH_LEN) 74 return -ENOENT; 75 memcpy(uevent_helper, buf, count); 76 uevent_helper[count] = '\0'; 77 if (count && uevent_helper[count-1] == '\n') 78 uevent_helper[count-1] = '\0'; 79 return count; 80 } 81 KERNEL_ATTR_RW(uevent_helper); 82 #endif 83 84 #ifdef CONFIG_PROFILING 85 static ssize_t profiling_show(struct kobject *kobj, 86 struct kobj_attribute *attr, char *buf) 87 { 88 return sysfs_emit(buf, "%d\n", prof_on); 89 } 90 static ssize_t profiling_store(struct kobject *kobj, 91 struct kobj_attribute *attr, 92 const char *buf, size_t count) 93 { 94 int ret; 95 static DEFINE_MUTEX(lock); 96 97 /* 98 * We need serialization, for profile_setup() initializes prof_on 99 * value and profile_init() must not reallocate prof_buffer after 100 * once allocated. 101 */ 102 guard(mutex)(&lock); 103 if (prof_on) 104 return -EEXIST; 105 /* 106 * This eventually calls into get_option() which 107 * has a ton of callers and is not const. It is 108 * easiest to cast it away here. 109 */ 110 profile_setup((char *)buf); 111 ret = profile_init(); 112 if (ret) 113 return ret; 114 ret = create_proc_profile(); 115 if (ret) 116 return ret; 117 return count; 118 } 119 KERNEL_ATTR_RW(profiling); 120 #endif 121 122 #ifdef CONFIG_KEXEC_CORE 123 static ssize_t kexec_loaded_show(struct kobject *kobj, 124 struct kobj_attribute *attr, char *buf) 125 { 126 return sysfs_emit(buf, "%d\n", !!kexec_image); 127 } 128 KERNEL_ATTR_RO(kexec_loaded); 129 130 #ifdef CONFIG_CRASH_DUMP 131 static ssize_t kexec_crash_loaded_show(struct kobject *kobj, 132 struct kobj_attribute *attr, char *buf) 133 { 134 return sysfs_emit(buf, "%d\n", kexec_crash_loaded()); 135 } 136 KERNEL_ATTR_RO(kexec_crash_loaded); 137 138 static ssize_t kexec_crash_size_show(struct kobject *kobj, 139 struct kobj_attribute *attr, char *buf) 140 { 141 ssize_t size = crash_get_memory_size(); 142 143 if (size < 0) 144 return size; 145 146 return sysfs_emit(buf, "%zd\n", size); 147 } 148 static ssize_t kexec_crash_size_store(struct kobject *kobj, 149 struct kobj_attribute *attr, 150 const char *buf, size_t count) 151 { 152 unsigned long cnt; 153 int ret; 154 155 if (kstrtoul(buf, 0, &cnt)) 156 return -EINVAL; 157 158 ret = crash_shrink_memory(cnt); 159 return ret < 0 ? ret : count; 160 } 161 KERNEL_ATTR_RW(kexec_crash_size); 162 163 #endif /* CONFIG_CRASH_DUMP*/ 164 #endif /* CONFIG_KEXEC_CORE */ 165 166 #ifdef CONFIG_VMCORE_INFO 167 168 static ssize_t vmcoreinfo_show(struct kobject *kobj, 169 struct kobj_attribute *attr, char *buf) 170 { 171 phys_addr_t vmcore_base = paddr_vmcoreinfo_note(); 172 return sysfs_emit(buf, "%pa %x\n", &vmcore_base, 173 (unsigned int)VMCOREINFO_NOTE_SIZE); 174 } 175 KERNEL_ATTR_RO(vmcoreinfo); 176 177 #ifdef CONFIG_CRASH_HOTPLUG 178 static ssize_t crash_elfcorehdr_size_show(struct kobject *kobj, 179 struct kobj_attribute *attr, char *buf) 180 { 181 unsigned int sz = crash_get_elfcorehdr_size(); 182 183 return sysfs_emit(buf, "%u\n", sz); 184 } 185 KERNEL_ATTR_RO(crash_elfcorehdr_size); 186 187 #endif 188 189 #endif /* CONFIG_VMCORE_INFO */ 190 191 /* whether file capabilities are enabled */ 192 static ssize_t fscaps_show(struct kobject *kobj, 193 struct kobj_attribute *attr, char *buf) 194 { 195 return sysfs_emit(buf, "%d\n", file_caps_enabled); 196 } 197 KERNEL_ATTR_RO(fscaps); 198 199 #ifndef CONFIG_TINY_RCU 200 int rcu_expedited; 201 static ssize_t rcu_expedited_show(struct kobject *kobj, 202 struct kobj_attribute *attr, char *buf) 203 { 204 return sysfs_emit(buf, "%d\n", READ_ONCE(rcu_expedited)); 205 } 206 static ssize_t rcu_expedited_store(struct kobject *kobj, 207 struct kobj_attribute *attr, 208 const char *buf, size_t count) 209 { 210 if (kstrtoint(buf, 0, &rcu_expedited)) 211 return -EINVAL; 212 213 return count; 214 } 215 KERNEL_ATTR_RW(rcu_expedited); 216 217 int rcu_normal; 218 static ssize_t rcu_normal_show(struct kobject *kobj, 219 struct kobj_attribute *attr, char *buf) 220 { 221 return sysfs_emit(buf, "%d\n", READ_ONCE(rcu_normal)); 222 } 223 static ssize_t rcu_normal_store(struct kobject *kobj, 224 struct kobj_attribute *attr, 225 const char *buf, size_t count) 226 { 227 if (kstrtoint(buf, 0, &rcu_normal)) 228 return -EINVAL; 229 230 return count; 231 } 232 KERNEL_ATTR_RW(rcu_normal); 233 #endif /* #ifndef CONFIG_TINY_RCU */ 234 235 /* 236 * Make /sys/kernel/notes give the raw contents of our kernel .notes section. 237 */ 238 extern const void __start_notes; 239 extern const void __stop_notes; 240 #define notes_size (&__stop_notes - &__start_notes) 241 242 static __ro_after_init BIN_ATTR_SIMPLE_RO(notes); 243 244 struct kobject *kernel_kobj; 245 EXPORT_SYMBOL_GPL(kernel_kobj); 246 247 static struct attribute * kernel_attrs[] = { 248 &fscaps_attr.attr, 249 &uevent_seqnum_attr.attr, 250 &cpu_byteorder_attr.attr, 251 &address_bits_attr.attr, 252 #ifdef CONFIG_UEVENT_HELPER 253 &uevent_helper_attr.attr, 254 #endif 255 #ifdef CONFIG_PROFILING 256 &profiling_attr.attr, 257 #endif 258 #ifdef CONFIG_KEXEC_CORE 259 &kexec_loaded_attr.attr, 260 #ifdef CONFIG_CRASH_DUMP 261 &kexec_crash_loaded_attr.attr, 262 &kexec_crash_size_attr.attr, 263 #endif 264 #endif 265 #ifdef CONFIG_VMCORE_INFO 266 &vmcoreinfo_attr.attr, 267 #ifdef CONFIG_CRASH_HOTPLUG 268 &crash_elfcorehdr_size_attr.attr, 269 #endif 270 #endif 271 #ifndef CONFIG_TINY_RCU 272 &rcu_expedited_attr.attr, 273 &rcu_normal_attr.attr, 274 #endif 275 NULL 276 }; 277 278 static const struct attribute_group kernel_attr_group = { 279 .attrs = kernel_attrs, 280 }; 281 282 static int __init ksysfs_init(void) 283 { 284 int error; 285 286 kernel_kobj = kobject_create_and_add("kernel", NULL); 287 if (!kernel_kobj) { 288 error = -ENOMEM; 289 goto exit; 290 } 291 error = sysfs_create_group(kernel_kobj, &kernel_attr_group); 292 if (error) 293 goto kset_exit; 294 295 if (notes_size > 0) { 296 bin_attr_notes.private = (void *)&__start_notes; 297 bin_attr_notes.size = notes_size; 298 error = sysfs_create_bin_file(kernel_kobj, &bin_attr_notes); 299 if (error) 300 goto group_exit; 301 } 302 303 return 0; 304 305 group_exit: 306 sysfs_remove_group(kernel_kobj, &kernel_attr_group); 307 kset_exit: 308 kobject_put(kernel_kobj); 309 exit: 310 return error; 311 } 312 313 core_initcall(ksysfs_init); 314