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/vmcore_info.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_VMCORE_INFO 123 124 static ssize_t vmcoreinfo_show(struct kobject *kobj, 125 struct kobj_attribute *attr, char *buf) 126 { 127 phys_addr_t vmcore_base = paddr_vmcoreinfo_note(); 128 return sysfs_emit(buf, "%pa %x\n", &vmcore_base, 129 (unsigned int)VMCOREINFO_NOTE_SIZE); 130 } 131 KERNEL_ATTR_RO(vmcoreinfo); 132 133 #endif /* CONFIG_VMCORE_INFO */ 134 135 /* whether file capabilities are enabled */ 136 static ssize_t fscaps_show(struct kobject *kobj, 137 struct kobj_attribute *attr, char *buf) 138 { 139 return sysfs_emit(buf, "%d\n", file_caps_enabled); 140 } 141 KERNEL_ATTR_RO(fscaps); 142 143 #ifndef CONFIG_TINY_RCU 144 int rcu_expedited; 145 static ssize_t rcu_expedited_show(struct kobject *kobj, 146 struct kobj_attribute *attr, char *buf) 147 { 148 return sysfs_emit(buf, "%d\n", READ_ONCE(rcu_expedited)); 149 } 150 static ssize_t rcu_expedited_store(struct kobject *kobj, 151 struct kobj_attribute *attr, 152 const char *buf, size_t count) 153 { 154 if (kstrtoint(buf, 0, &rcu_expedited)) 155 return -EINVAL; 156 157 return count; 158 } 159 KERNEL_ATTR_RW(rcu_expedited); 160 161 int rcu_normal; 162 static ssize_t rcu_normal_show(struct kobject *kobj, 163 struct kobj_attribute *attr, char *buf) 164 { 165 return sysfs_emit(buf, "%d\n", READ_ONCE(rcu_normal)); 166 } 167 static ssize_t rcu_normal_store(struct kobject *kobj, 168 struct kobj_attribute *attr, 169 const char *buf, size_t count) 170 { 171 if (kstrtoint(buf, 0, &rcu_normal)) 172 return -EINVAL; 173 174 return count; 175 } 176 KERNEL_ATTR_RW(rcu_normal); 177 #endif /* #ifndef CONFIG_TINY_RCU */ 178 179 /* 180 * Make /sys/kernel/notes give the raw contents of our kernel .notes section. 181 */ 182 extern const void __start_notes; 183 extern const void __stop_notes; 184 #define notes_size (&__stop_notes - &__start_notes) 185 186 static __ro_after_init BIN_ATTR_SIMPLE_RO(notes); 187 188 struct kobject *kernel_kobj; 189 EXPORT_SYMBOL_GPL(kernel_kobj); 190 191 static struct attribute * kernel_attrs[] = { 192 &fscaps_attr.attr, 193 &uevent_seqnum_attr.attr, 194 &cpu_byteorder_attr.attr, 195 &address_bits_attr.attr, 196 #ifdef CONFIG_UEVENT_HELPER 197 &uevent_helper_attr.attr, 198 #endif 199 #ifdef CONFIG_PROFILING 200 &profiling_attr.attr, 201 #endif 202 #ifdef CONFIG_VMCORE_INFO 203 &vmcoreinfo_attr.attr, 204 #endif 205 #ifndef CONFIG_TINY_RCU 206 &rcu_expedited_attr.attr, 207 &rcu_normal_attr.attr, 208 #endif 209 NULL 210 }; 211 212 static const struct attribute_group kernel_attr_group = { 213 .attrs = kernel_attrs, 214 }; 215 216 static int __init ksysfs_init(void) 217 { 218 int error; 219 220 kernel_kobj = kobject_create_and_add("kernel", NULL); 221 if (!kernel_kobj) { 222 error = -ENOMEM; 223 goto exit; 224 } 225 error = sysfs_create_group(kernel_kobj, &kernel_attr_group); 226 if (error) 227 goto kset_exit; 228 229 if (notes_size > 0) { 230 bin_attr_notes.private = (void *)&__start_notes; 231 bin_attr_notes.size = notes_size; 232 error = sysfs_create_bin_file(kernel_kobj, &bin_attr_notes); 233 if (error) 234 goto group_exit; 235 } 236 237 return 0; 238 239 group_exit: 240 sysfs_remove_group(kernel_kobj, &kernel_attr_group); 241 kset_exit: 242 kobject_put(kernel_kobj); 243 exit: 244 return error; 245 } 246 247 core_initcall(ksysfs_init); 248