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) \ 33static struct kobj_attribute _name##_attr = __ATTR_RO(_name) 34 35#define KERNEL_ATTR_RW(_name) \ 36static struct kobj_attribute _name##_attr = __ATTR_RW(_name) 37 38/* current uevent sequence number */ 39static 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} 44KERNEL_ATTR_RO(uevent_seqnum); 45 46/* cpu byteorder */ 47static 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} 52KERNEL_ATTR_RO(cpu_byteorder); 53 54/* address bits */ 55static 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} 60KERNEL_ATTR_RO(address_bits); 61 62#ifdef CONFIG_UEVENT_HELPER 63/* uevent helper program, used during early boot */ 64static 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} 69static 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} 81KERNEL_ATTR_RW(uevent_helper); 82#endif 83 84#ifdef CONFIG_PROFILING 85static 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} 90static 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} 112KERNEL_ATTR_RW(profiling); 113#endif 114 115#ifdef CONFIG_KEXEC_CORE 116static 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} 121KERNEL_ATTR_RO(kexec_loaded); 122 123#ifdef CONFIG_CRASH_DUMP 124static 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} 129KERNEL_ATTR_RO(kexec_crash_loaded); 130 131static 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} 141static 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} 154KERNEL_ATTR_RW(kexec_crash_size); 155 156#endif /* CONFIG_CRASH_DUMP*/ 157#endif /* CONFIG_KEXEC_CORE */ 158 159#ifdef CONFIG_VMCORE_INFO 160 161static 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} 168KERNEL_ATTR_RO(vmcoreinfo); 169 170#ifdef CONFIG_CRASH_HOTPLUG 171static 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} 178KERNEL_ATTR_RO(crash_elfcorehdr_size); 179 180#endif 181 182#endif /* CONFIG_VMCORE_INFO */ 183 184/* whether file capabilities are enabled */ 185static 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} 190KERNEL_ATTR_RO(fscaps); 191 192#ifndef CONFIG_TINY_RCU 193int rcu_expedited; 194static 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} 199static 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} 208KERNEL_ATTR_RW(rcu_expedited); 209 210int rcu_normal; 211static 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} 216static 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} 225KERNEL_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 */ 231extern const void __start_notes __weak; 232extern const void __stop_notes __weak; 233#define notes_size (&__stop_notes - &__start_notes) 234 235static 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 243static struct bin_attribute notes_attr __ro_after_init = { 244 .attr = { 245 .name = "notes", 246 .mode = S_IRUGO, 247 }, 248 .read = ¬es_read, 249}; 250 251struct kobject *kernel_kobj; 252EXPORT_SYMBOL_GPL(kernel_kobj); 253 254static 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 285static const struct attribute_group kernel_attr_group = { 286 .attrs = kernel_attrs, 287}; 288 289static 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 311group_exit: 312 sysfs_remove_group(kernel_kobj, &kernel_attr_group); 313kset_exit: 314 kobject_put(kernel_kobj); 315exit: 316 return error; 317} 318 319core_initcall(ksysfs_init); 320