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 96 if (prof_on) 97 return -EEXIST; 98 /* 99 * This eventually calls into get_option() which 100 * has a ton of callers and is not const. It is 101 * easiest to cast it away here. 102 */ 103 profile_setup((char *)buf); 104 ret = profile_init(); 105 if (ret) 106 return ret; 107 ret = create_proc_profile(); 108 if (ret) 109 return ret; 110 return count; 111 } 112 KERNEL_ATTR_RW(profiling); 113 #endif 114 115 #ifdef CONFIG_KEXEC_CORE 116 static ssize_t kexec_loaded_show(struct kobject *kobj, 117 struct kobj_attribute *attr, char *buf) 118 { 119 return sysfs_emit(buf, "%d\n", !!kexec_image); 120 } 121 KERNEL_ATTR_RO(kexec_loaded); 122 123 #ifdef CONFIG_CRASH_DUMP 124 static ssize_t kexec_crash_loaded_show(struct kobject *kobj, 125 struct kobj_attribute *attr, char *buf) 126 { 127 return sysfs_emit(buf, "%d\n", kexec_crash_loaded()); 128 } 129 KERNEL_ATTR_RO(kexec_crash_loaded); 130 131 static ssize_t kexec_crash_size_show(struct kobject *kobj, 132 struct kobj_attribute *attr, char *buf) 133 { 134 ssize_t size = crash_get_memory_size(); 135 136 if (size < 0) 137 return size; 138 139 return sysfs_emit(buf, "%zd\n", size); 140 } 141 static ssize_t kexec_crash_size_store(struct kobject *kobj, 142 struct kobj_attribute *attr, 143 const char *buf, size_t count) 144 { 145 unsigned long cnt; 146 int ret; 147 148 if (kstrtoul(buf, 0, &cnt)) 149 return -EINVAL; 150 151 ret = crash_shrink_memory(cnt); 152 return ret < 0 ? ret : count; 153 } 154 KERNEL_ATTR_RW(kexec_crash_size); 155 156 #endif /* CONFIG_CRASH_DUMP*/ 157 #endif /* CONFIG_KEXEC_CORE */ 158 159 #ifdef CONFIG_VMCORE_INFO 160 161 static ssize_t vmcoreinfo_show(struct kobject *kobj, 162 struct kobj_attribute *attr, char *buf) 163 { 164 phys_addr_t vmcore_base = paddr_vmcoreinfo_note(); 165 return sysfs_emit(buf, "%pa %x\n", &vmcore_base, 166 (unsigned int)VMCOREINFO_NOTE_SIZE); 167 } 168 KERNEL_ATTR_RO(vmcoreinfo); 169 170 #ifdef CONFIG_CRASH_HOTPLUG 171 static ssize_t crash_elfcorehdr_size_show(struct kobject *kobj, 172 struct kobj_attribute *attr, char *buf) 173 { 174 unsigned int sz = crash_get_elfcorehdr_size(); 175 176 return sysfs_emit(buf, "%u\n", sz); 177 } 178 KERNEL_ATTR_RO(crash_elfcorehdr_size); 179 180 #endif 181 182 #endif /* CONFIG_VMCORE_INFO */ 183 184 /* whether file capabilities are enabled */ 185 static ssize_t fscaps_show(struct kobject *kobj, 186 struct kobj_attribute *attr, char *buf) 187 { 188 return sysfs_emit(buf, "%d\n", file_caps_enabled); 189 } 190 KERNEL_ATTR_RO(fscaps); 191 192 #ifndef CONFIG_TINY_RCU 193 int rcu_expedited; 194 static ssize_t rcu_expedited_show(struct kobject *kobj, 195 struct kobj_attribute *attr, char *buf) 196 { 197 return sysfs_emit(buf, "%d\n", READ_ONCE(rcu_expedited)); 198 } 199 static ssize_t rcu_expedited_store(struct kobject *kobj, 200 struct kobj_attribute *attr, 201 const char *buf, size_t count) 202 { 203 if (kstrtoint(buf, 0, &rcu_expedited)) 204 return -EINVAL; 205 206 return count; 207 } 208 KERNEL_ATTR_RW(rcu_expedited); 209 210 int rcu_normal; 211 static ssize_t rcu_normal_show(struct kobject *kobj, 212 struct kobj_attribute *attr, char *buf) 213 { 214 return sysfs_emit(buf, "%d\n", READ_ONCE(rcu_normal)); 215 } 216 static ssize_t rcu_normal_store(struct kobject *kobj, 217 struct kobj_attribute *attr, 218 const char *buf, size_t count) 219 { 220 if (kstrtoint(buf, 0, &rcu_normal)) 221 return -EINVAL; 222 223 return count; 224 } 225 KERNEL_ATTR_RW(rcu_normal); 226 #endif /* #ifndef CONFIG_TINY_RCU */ 227 228 /* 229 * Make /sys/kernel/notes give the raw contents of our kernel .notes section. 230 */ 231 extern const void __start_notes __weak; 232 extern const void __stop_notes __weak; 233 #define notes_size (&__stop_notes - &__start_notes) 234 235 static ssize_t notes_read(struct file *filp, struct kobject *kobj, 236 struct bin_attribute *bin_attr, 237 char *buf, loff_t off, size_t count) 238 { 239 memcpy(buf, &__start_notes + off, count); 240 return count; 241 } 242 243 static struct bin_attribute notes_attr __ro_after_init = { 244 .attr = { 245 .name = "notes", 246 .mode = S_IRUGO, 247 }, 248 .read = ¬es_read, 249 }; 250 251 struct kobject *kernel_kobj; 252 EXPORT_SYMBOL_GPL(kernel_kobj); 253 254 static struct attribute * kernel_attrs[] = { 255 &fscaps_attr.attr, 256 &uevent_seqnum_attr.attr, 257 &cpu_byteorder_attr.attr, 258 &address_bits_attr.attr, 259 #ifdef CONFIG_UEVENT_HELPER 260 &uevent_helper_attr.attr, 261 #endif 262 #ifdef CONFIG_PROFILING 263 &profiling_attr.attr, 264 #endif 265 #ifdef CONFIG_KEXEC_CORE 266 &kexec_loaded_attr.attr, 267 #ifdef CONFIG_CRASH_DUMP 268 &kexec_crash_loaded_attr.attr, 269 &kexec_crash_size_attr.attr, 270 #endif 271 #endif 272 #ifdef CONFIG_VMCORE_INFO 273 &vmcoreinfo_attr.attr, 274 #ifdef CONFIG_CRASH_HOTPLUG 275 &crash_elfcorehdr_size_attr.attr, 276 #endif 277 #endif 278 #ifndef CONFIG_TINY_RCU 279 &rcu_expedited_attr.attr, 280 &rcu_normal_attr.attr, 281 #endif 282 NULL 283 }; 284 285 static const struct attribute_group kernel_attr_group = { 286 .attrs = kernel_attrs, 287 }; 288 289 static int __init ksysfs_init(void) 290 { 291 int error; 292 293 kernel_kobj = kobject_create_and_add("kernel", NULL); 294 if (!kernel_kobj) { 295 error = -ENOMEM; 296 goto exit; 297 } 298 error = sysfs_create_group(kernel_kobj, &kernel_attr_group); 299 if (error) 300 goto kset_exit; 301 302 if (notes_size > 0) { 303 notes_attr.size = notes_size; 304 error = sysfs_create_bin_file(kernel_kobj, ¬es_attr); 305 if (error) 306 goto group_exit; 307 } 308 309 return 0; 310 311 group_exit: 312 sysfs_remove_group(kernel_kobj, &kernel_attr_group); 313 kset_exit: 314 kobject_put(kernel_kobj); 315 exit: 316 return error; 317 } 318 319 core_initcall(ksysfs_init); 320