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 = \ 28 __ATTR(_name, 0644, _name##_show, _name##_store) 29 30 /* current uevent sequence number */ 31 static ssize_t uevent_seqnum_show(struct kobject *kobj, 32 struct kobj_attribute *attr, char *buf) 33 { 34 return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum); 35 } 36 KERNEL_ATTR_RO(uevent_seqnum); 37 38 #ifdef CONFIG_UEVENT_HELPER 39 /* uevent helper program, used during early boot */ 40 static ssize_t uevent_helper_show(struct kobject *kobj, 41 struct kobj_attribute *attr, char *buf) 42 { 43 return sprintf(buf, "%s\n", uevent_helper); 44 } 45 static ssize_t uevent_helper_store(struct kobject *kobj, 46 struct kobj_attribute *attr, 47 const char *buf, size_t count) 48 { 49 if (count+1 > UEVENT_HELPER_PATH_LEN) 50 return -ENOENT; 51 memcpy(uevent_helper, buf, count); 52 uevent_helper[count] = '\0'; 53 if (count && uevent_helper[count-1] == '\n') 54 uevent_helper[count-1] = '\0'; 55 return count; 56 } 57 KERNEL_ATTR_RW(uevent_helper); 58 #endif 59 60 #ifdef CONFIG_PROFILING 61 static ssize_t profiling_show(struct kobject *kobj, 62 struct kobj_attribute *attr, char *buf) 63 { 64 return sprintf(buf, "%d\n", prof_on); 65 } 66 static ssize_t profiling_store(struct kobject *kobj, 67 struct kobj_attribute *attr, 68 const char *buf, size_t count) 69 { 70 int ret; 71 72 if (prof_on) 73 return -EEXIST; 74 /* 75 * This eventually calls into get_option() which 76 * has a ton of callers and is not const. It is 77 * easiest to cast it away here. 78 */ 79 profile_setup((char *)buf); 80 ret = profile_init(); 81 if (ret) 82 return ret; 83 ret = create_proc_profile(); 84 if (ret) 85 return ret; 86 return count; 87 } 88 KERNEL_ATTR_RW(profiling); 89 #endif 90 91 #ifdef CONFIG_KEXEC_CORE 92 static ssize_t kexec_loaded_show(struct kobject *kobj, 93 struct kobj_attribute *attr, char *buf) 94 { 95 return sprintf(buf, "%d\n", !!kexec_image); 96 } 97 KERNEL_ATTR_RO(kexec_loaded); 98 99 static ssize_t kexec_crash_loaded_show(struct kobject *kobj, 100 struct kobj_attribute *attr, char *buf) 101 { 102 return sprintf(buf, "%d\n", kexec_crash_loaded()); 103 } 104 KERNEL_ATTR_RO(kexec_crash_loaded); 105 106 static ssize_t kexec_crash_size_show(struct kobject *kobj, 107 struct kobj_attribute *attr, char *buf) 108 { 109 return sprintf(buf, "%zu\n", crash_get_memory_size()); 110 } 111 static ssize_t kexec_crash_size_store(struct kobject *kobj, 112 struct kobj_attribute *attr, 113 const char *buf, size_t count) 114 { 115 unsigned long cnt; 116 int ret; 117 118 if (kstrtoul(buf, 0, &cnt)) 119 return -EINVAL; 120 121 ret = crash_shrink_memory(cnt); 122 return ret < 0 ? ret : count; 123 } 124 KERNEL_ATTR_RW(kexec_crash_size); 125 126 #endif /* CONFIG_KEXEC_CORE */ 127 128 #ifdef CONFIG_CRASH_CORE 129 130 static ssize_t vmcoreinfo_show(struct kobject *kobj, 131 struct kobj_attribute *attr, char *buf) 132 { 133 phys_addr_t vmcore_base = paddr_vmcoreinfo_note(); 134 return sprintf(buf, "%pa %x\n", &vmcore_base, 135 (unsigned int)VMCOREINFO_NOTE_SIZE); 136 } 137 KERNEL_ATTR_RO(vmcoreinfo); 138 139 #endif /* CONFIG_CRASH_CORE */ 140 141 /* whether file capabilities are enabled */ 142 static ssize_t fscaps_show(struct kobject *kobj, 143 struct kobj_attribute *attr, char *buf) 144 { 145 return sprintf(buf, "%d\n", file_caps_enabled); 146 } 147 KERNEL_ATTR_RO(fscaps); 148 149 #ifndef CONFIG_TINY_RCU 150 int rcu_expedited; 151 static ssize_t rcu_expedited_show(struct kobject *kobj, 152 struct kobj_attribute *attr, char *buf) 153 { 154 return sprintf(buf, "%d\n", READ_ONCE(rcu_expedited)); 155 } 156 static ssize_t rcu_expedited_store(struct kobject *kobj, 157 struct kobj_attribute *attr, 158 const char *buf, size_t count) 159 { 160 if (kstrtoint(buf, 0, &rcu_expedited)) 161 return -EINVAL; 162 163 return count; 164 } 165 KERNEL_ATTR_RW(rcu_expedited); 166 167 int rcu_normal; 168 static ssize_t rcu_normal_show(struct kobject *kobj, 169 struct kobj_attribute *attr, char *buf) 170 { 171 return sprintf(buf, "%d\n", READ_ONCE(rcu_normal)); 172 } 173 static ssize_t rcu_normal_store(struct kobject *kobj, 174 struct kobj_attribute *attr, 175 const char *buf, size_t count) 176 { 177 if (kstrtoint(buf, 0, &rcu_normal)) 178 return -EINVAL; 179 180 return count; 181 } 182 KERNEL_ATTR_RW(rcu_normal); 183 #endif /* #ifndef CONFIG_TINY_RCU */ 184 185 /* 186 * Make /sys/kernel/notes give the raw contents of our kernel .notes section. 187 */ 188 extern const void __start_notes __weak; 189 extern const void __stop_notes __weak; 190 #define notes_size (&__stop_notes - &__start_notes) 191 192 static ssize_t notes_read(struct file *filp, struct kobject *kobj, 193 struct bin_attribute *bin_attr, 194 char *buf, loff_t off, size_t count) 195 { 196 memcpy(buf, &__start_notes + off, count); 197 return count; 198 } 199 200 static struct bin_attribute notes_attr __ro_after_init = { 201 .attr = { 202 .name = "notes", 203 .mode = S_IRUGO, 204 }, 205 .read = ¬es_read, 206 }; 207 208 struct kobject *kernel_kobj; 209 EXPORT_SYMBOL_GPL(kernel_kobj); 210 211 static struct attribute * kernel_attrs[] = { 212 &fscaps_attr.attr, 213 &uevent_seqnum_attr.attr, 214 #ifdef CONFIG_UEVENT_HELPER 215 &uevent_helper_attr.attr, 216 #endif 217 #ifdef CONFIG_PROFILING 218 &profiling_attr.attr, 219 #endif 220 #ifdef CONFIG_KEXEC_CORE 221 &kexec_loaded_attr.attr, 222 &kexec_crash_loaded_attr.attr, 223 &kexec_crash_size_attr.attr, 224 #endif 225 #ifdef CONFIG_CRASH_CORE 226 &vmcoreinfo_attr.attr, 227 #endif 228 #ifndef CONFIG_TINY_RCU 229 &rcu_expedited_attr.attr, 230 &rcu_normal_attr.attr, 231 #endif 232 NULL 233 }; 234 235 static const struct attribute_group kernel_attr_group = { 236 .attrs = kernel_attrs, 237 }; 238 239 static int __init ksysfs_init(void) 240 { 241 int error; 242 243 kernel_kobj = kobject_create_and_add("kernel", NULL); 244 if (!kernel_kobj) { 245 error = -ENOMEM; 246 goto exit; 247 } 248 error = sysfs_create_group(kernel_kobj, &kernel_attr_group); 249 if (error) 250 goto kset_exit; 251 252 if (notes_size > 0) { 253 notes_attr.size = notes_size; 254 error = sysfs_create_bin_file(kernel_kobj, ¬es_attr); 255 if (error) 256 goto group_exit; 257 } 258 259 return 0; 260 261 group_exit: 262 sysfs_remove_group(kernel_kobj, &kernel_attr_group); 263 kset_exit: 264 kobject_put(kernel_kobj); 265 exit: 266 return error; 267 } 268 269 core_initcall(ksysfs_init); 270