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 <linux/kobject.h> 10 #include <linux/string.h> 11 #include <linux/sysfs.h> 12 #include <linux/export.h> 13 #include <linux/init.h> 14 #include <linux/kexec.h> 15 #include <linux/profile.h> 16 #include <linux/stat.h> 17 #include <linux/sched.h> 18 #include <linux/capability.h> 19 #include <linux/compiler.h> 20 21 #include <linux/rcupdate.h> /* rcu_expedited and rcu_normal */ 22 23 #define KERNEL_ATTR_RO(_name) \ 24 static struct kobj_attribute _name##_attr = __ATTR_RO(_name) 25 26 #define KERNEL_ATTR_RW(_name) \ 27 static struct kobj_attribute _name##_attr = __ATTR_RW(_name) 28 29 /* current uevent sequence number */ 30 static ssize_t uevent_seqnum_show(struct kobject *kobj, 31 struct kobj_attribute *attr, char *buf) 32 { 33 return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum); 34 } 35 KERNEL_ATTR_RO(uevent_seqnum); 36 37 #ifdef CONFIG_UEVENT_HELPER 38 /* uevent helper program, used during early boot */ 39 static ssize_t uevent_helper_show(struct kobject *kobj, 40 struct kobj_attribute *attr, char *buf) 41 { 42 return sprintf(buf, "%s\n", uevent_helper); 43 } 44 static ssize_t uevent_helper_store(struct kobject *kobj, 45 struct kobj_attribute *attr, 46 const char *buf, size_t count) 47 { 48 if (count+1 > UEVENT_HELPER_PATH_LEN) 49 return -ENOENT; 50 memcpy(uevent_helper, buf, count); 51 uevent_helper[count] = '\0'; 52 if (count && uevent_helper[count-1] == '\n') 53 uevent_helper[count-1] = '\0'; 54 return count; 55 } 56 KERNEL_ATTR_RW(uevent_helper); 57 #endif 58 59 #ifdef CONFIG_PROFILING 60 static ssize_t profiling_show(struct kobject *kobj, 61 struct kobj_attribute *attr, char *buf) 62 { 63 return sprintf(buf, "%d\n", prof_on); 64 } 65 static ssize_t profiling_store(struct kobject *kobj, 66 struct kobj_attribute *attr, 67 const char *buf, size_t count) 68 { 69 int ret; 70 71 if (prof_on) 72 return -EEXIST; 73 /* 74 * This eventually calls into get_option() which 75 * has a ton of callers and is not const. It is 76 * easiest to cast it away here. 77 */ 78 profile_setup((char *)buf); 79 ret = profile_init(); 80 if (ret) 81 return ret; 82 ret = create_proc_profile(); 83 if (ret) 84 return ret; 85 return count; 86 } 87 KERNEL_ATTR_RW(profiling); 88 #endif 89 90 #ifdef CONFIG_KEXEC_CORE 91 static ssize_t kexec_loaded_show(struct kobject *kobj, 92 struct kobj_attribute *attr, char *buf) 93 { 94 return sprintf(buf, "%d\n", !!kexec_image); 95 } 96 KERNEL_ATTR_RO(kexec_loaded); 97 98 static ssize_t kexec_crash_loaded_show(struct kobject *kobj, 99 struct kobj_attribute *attr, char *buf) 100 { 101 return sprintf(buf, "%d\n", kexec_crash_loaded()); 102 } 103 KERNEL_ATTR_RO(kexec_crash_loaded); 104 105 static ssize_t kexec_crash_size_show(struct kobject *kobj, 106 struct kobj_attribute *attr, char *buf) 107 { 108 ssize_t size = crash_get_memory_size(); 109 110 if (size < 0) 111 return size; 112 113 return sprintf(buf, "%zd\n", size); 114 } 115 static ssize_t kexec_crash_size_store(struct kobject *kobj, 116 struct kobj_attribute *attr, 117 const char *buf, size_t count) 118 { 119 unsigned long cnt; 120 int ret; 121 122 if (kstrtoul(buf, 0, &cnt)) 123 return -EINVAL; 124 125 ret = crash_shrink_memory(cnt); 126 return ret < 0 ? ret : count; 127 } 128 KERNEL_ATTR_RW(kexec_crash_size); 129 130 #endif /* CONFIG_KEXEC_CORE */ 131 132 #ifdef CONFIG_CRASH_CORE 133 134 static ssize_t vmcoreinfo_show(struct kobject *kobj, 135 struct kobj_attribute *attr, char *buf) 136 { 137 phys_addr_t vmcore_base = paddr_vmcoreinfo_note(); 138 return sprintf(buf, "%pa %x\n", &vmcore_base, 139 (unsigned int)VMCOREINFO_NOTE_SIZE); 140 } 141 KERNEL_ATTR_RO(vmcoreinfo); 142 143 #endif /* CONFIG_CRASH_CORE */ 144 145 /* whether file capabilities are enabled */ 146 static ssize_t fscaps_show(struct kobject *kobj, 147 struct kobj_attribute *attr, char *buf) 148 { 149 return sprintf(buf, "%d\n", file_caps_enabled); 150 } 151 KERNEL_ATTR_RO(fscaps); 152 153 #ifndef CONFIG_TINY_RCU 154 int rcu_expedited; 155 static ssize_t rcu_expedited_show(struct kobject *kobj, 156 struct kobj_attribute *attr, char *buf) 157 { 158 return sprintf(buf, "%d\n", READ_ONCE(rcu_expedited)); 159 } 160 static ssize_t rcu_expedited_store(struct kobject *kobj, 161 struct kobj_attribute *attr, 162 const char *buf, size_t count) 163 { 164 if (kstrtoint(buf, 0, &rcu_expedited)) 165 return -EINVAL; 166 167 return count; 168 } 169 KERNEL_ATTR_RW(rcu_expedited); 170 171 int rcu_normal; 172 static ssize_t rcu_normal_show(struct kobject *kobj, 173 struct kobj_attribute *attr, char *buf) 174 { 175 return sprintf(buf, "%d\n", READ_ONCE(rcu_normal)); 176 } 177 static ssize_t rcu_normal_store(struct kobject *kobj, 178 struct kobj_attribute *attr, 179 const char *buf, size_t count) 180 { 181 if (kstrtoint(buf, 0, &rcu_normal)) 182 return -EINVAL; 183 184 return count; 185 } 186 KERNEL_ATTR_RW(rcu_normal); 187 #endif /* #ifndef CONFIG_TINY_RCU */ 188 189 /* 190 * Make /sys/kernel/notes give the raw contents of our kernel .notes section. 191 */ 192 extern const void __start_notes __weak; 193 extern const void __stop_notes __weak; 194 #define notes_size (&__stop_notes - &__start_notes) 195 196 static ssize_t notes_read(struct file *filp, struct kobject *kobj, 197 struct bin_attribute *bin_attr, 198 char *buf, loff_t off, size_t count) 199 { 200 memcpy(buf, &__start_notes + off, count); 201 return count; 202 } 203 204 static struct bin_attribute notes_attr __ro_after_init = { 205 .attr = { 206 .name = "notes", 207 .mode = S_IRUGO, 208 }, 209 .read = ¬es_read, 210 }; 211 212 struct kobject *kernel_kobj; 213 EXPORT_SYMBOL_GPL(kernel_kobj); 214 215 static struct attribute * kernel_attrs[] = { 216 &fscaps_attr.attr, 217 &uevent_seqnum_attr.attr, 218 #ifdef CONFIG_UEVENT_HELPER 219 &uevent_helper_attr.attr, 220 #endif 221 #ifdef CONFIG_PROFILING 222 &profiling_attr.attr, 223 #endif 224 #ifdef CONFIG_KEXEC_CORE 225 &kexec_loaded_attr.attr, 226 &kexec_crash_loaded_attr.attr, 227 &kexec_crash_size_attr.attr, 228 #endif 229 #ifdef CONFIG_CRASH_CORE 230 &vmcoreinfo_attr.attr, 231 #endif 232 #ifndef CONFIG_TINY_RCU 233 &rcu_expedited_attr.attr, 234 &rcu_normal_attr.attr, 235 #endif 236 NULL 237 }; 238 239 static const struct attribute_group kernel_attr_group = { 240 .attrs = kernel_attrs, 241 }; 242 243 static int __init ksysfs_init(void) 244 { 245 int error; 246 247 kernel_kobj = kobject_create_and_add("kernel", NULL); 248 if (!kernel_kobj) { 249 error = -ENOMEM; 250 goto exit; 251 } 252 error = sysfs_create_group(kernel_kobj, &kernel_attr_group); 253 if (error) 254 goto kset_exit; 255 256 if (notes_size > 0) { 257 notes_attr.size = notes_size; 258 error = sysfs_create_bin_file(kernel_kobj, ¬es_attr); 259 if (error) 260 goto group_exit; 261 } 262 263 return 0; 264 265 group_exit: 266 sysfs_remove_group(kernel_kobj, &kernel_attr_group); 267 kset_exit: 268 kobject_put(kernel_kobj); 269 exit: 270 return error; 271 } 272 273 core_initcall(ksysfs_init); 274