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 return sprintf(buf, "%zu\n", crash_get_memory_size()); 109 } 110 static ssize_t kexec_crash_size_store(struct kobject *kobj, 111 struct kobj_attribute *attr, 112 const char *buf, size_t count) 113 { 114 unsigned long cnt; 115 int ret; 116 117 if (kstrtoul(buf, 0, &cnt)) 118 return -EINVAL; 119 120 ret = crash_shrink_memory(cnt); 121 return ret < 0 ? ret : count; 122 } 123 KERNEL_ATTR_RW(kexec_crash_size); 124 125 #endif /* CONFIG_KEXEC_CORE */ 126 127 #ifdef CONFIG_CRASH_CORE 128 129 static ssize_t vmcoreinfo_show(struct kobject *kobj, 130 struct kobj_attribute *attr, char *buf) 131 { 132 phys_addr_t vmcore_base = paddr_vmcoreinfo_note(); 133 return sprintf(buf, "%pa %x\n", &vmcore_base, 134 (unsigned int)VMCOREINFO_NOTE_SIZE); 135 } 136 KERNEL_ATTR_RO(vmcoreinfo); 137 138 #endif /* CONFIG_CRASH_CORE */ 139 140 /* whether file capabilities are enabled */ 141 static ssize_t fscaps_show(struct kobject *kobj, 142 struct kobj_attribute *attr, char *buf) 143 { 144 return sprintf(buf, "%d\n", file_caps_enabled); 145 } 146 KERNEL_ATTR_RO(fscaps); 147 148 #ifndef CONFIG_TINY_RCU 149 int rcu_expedited; 150 static ssize_t rcu_expedited_show(struct kobject *kobj, 151 struct kobj_attribute *attr, char *buf) 152 { 153 return sprintf(buf, "%d\n", READ_ONCE(rcu_expedited)); 154 } 155 static ssize_t rcu_expedited_store(struct kobject *kobj, 156 struct kobj_attribute *attr, 157 const char *buf, size_t count) 158 { 159 if (kstrtoint(buf, 0, &rcu_expedited)) 160 return -EINVAL; 161 162 return count; 163 } 164 KERNEL_ATTR_RW(rcu_expedited); 165 166 int rcu_normal; 167 static ssize_t rcu_normal_show(struct kobject *kobj, 168 struct kobj_attribute *attr, char *buf) 169 { 170 return sprintf(buf, "%d\n", READ_ONCE(rcu_normal)); 171 } 172 static ssize_t rcu_normal_store(struct kobject *kobj, 173 struct kobj_attribute *attr, 174 const char *buf, size_t count) 175 { 176 if (kstrtoint(buf, 0, &rcu_normal)) 177 return -EINVAL; 178 179 return count; 180 } 181 KERNEL_ATTR_RW(rcu_normal); 182 #endif /* #ifndef CONFIG_TINY_RCU */ 183 184 /* 185 * Make /sys/kernel/notes give the raw contents of our kernel .notes section. 186 */ 187 extern const void __start_notes __weak; 188 extern const void __stop_notes __weak; 189 #define notes_size (&__stop_notes - &__start_notes) 190 191 static ssize_t notes_read(struct file *filp, struct kobject *kobj, 192 struct bin_attribute *bin_attr, 193 char *buf, loff_t off, size_t count) 194 { 195 memcpy(buf, &__start_notes + off, count); 196 return count; 197 } 198 199 static struct bin_attribute notes_attr __ro_after_init = { 200 .attr = { 201 .name = "notes", 202 .mode = S_IRUGO, 203 }, 204 .read = ¬es_read, 205 }; 206 207 struct kobject *kernel_kobj; 208 EXPORT_SYMBOL_GPL(kernel_kobj); 209 210 static struct attribute * kernel_attrs[] = { 211 &fscaps_attr.attr, 212 &uevent_seqnum_attr.attr, 213 #ifdef CONFIG_UEVENT_HELPER 214 &uevent_helper_attr.attr, 215 #endif 216 #ifdef CONFIG_PROFILING 217 &profiling_attr.attr, 218 #endif 219 #ifdef CONFIG_KEXEC_CORE 220 &kexec_loaded_attr.attr, 221 &kexec_crash_loaded_attr.attr, 222 &kexec_crash_size_attr.attr, 223 #endif 224 #ifdef CONFIG_CRASH_CORE 225 &vmcoreinfo_attr.attr, 226 #endif 227 #ifndef CONFIG_TINY_RCU 228 &rcu_expedited_attr.attr, 229 &rcu_normal_attr.attr, 230 #endif 231 NULL 232 }; 233 234 static const struct attribute_group kernel_attr_group = { 235 .attrs = kernel_attrs, 236 }; 237 238 static int __init ksysfs_init(void) 239 { 240 int error; 241 242 kernel_kobj = kobject_create_and_add("kernel", NULL); 243 if (!kernel_kobj) { 244 error = -ENOMEM; 245 goto exit; 246 } 247 error = sysfs_create_group(kernel_kobj, &kernel_attr_group); 248 if (error) 249 goto kset_exit; 250 251 if (notes_size > 0) { 252 notes_attr.size = notes_size; 253 error = sysfs_create_bin_file(kernel_kobj, ¬es_attr); 254 if (error) 255 goto group_exit; 256 } 257 258 return 0; 259 260 group_exit: 261 sysfs_remove_group(kernel_kobj, &kernel_attr_group); 262 kset_exit: 263 kobject_put(kernel_kobj); 264 exit: 265 return error; 266 } 267 268 core_initcall(ksysfs_init); 269