1 /* 2 * kernel/ksysfs.c - sysfs attributes in /sys/kernel, which 3 * are not related to any other subsystem 4 * 5 * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org> 6 * 7 * This file is release under the GPLv2 8 * 9 */ 10 11 #include <linux/kobject.h> 12 #include <linux/string.h> 13 #include <linux/sysfs.h> 14 #include <linux/export.h> 15 #include <linux/init.h> 16 #include <linux/kexec.h> 17 #include <linux/profile.h> 18 #include <linux/stat.h> 19 #include <linux/sched.h> 20 #include <linux/capability.h> 21 #include <linux/compiler.h> 22 23 #include <linux/rcupdate.h> /* rcu_expedited and rcu_normal */ 24 25 #define KERNEL_ATTR_RO(_name) \ 26 static struct kobj_attribute _name##_attr = __ATTR_RO(_name) 27 28 #define KERNEL_ATTR_RW(_name) \ 29 static struct kobj_attribute _name##_attr = \ 30 __ATTR(_name, 0644, _name##_show, _name##_store) 31 32 /* current uevent sequence number */ 33 static ssize_t uevent_seqnum_show(struct kobject *kobj, 34 struct kobj_attribute *attr, char *buf) 35 { 36 return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum); 37 } 38 KERNEL_ATTR_RO(uevent_seqnum); 39 40 #ifdef CONFIG_UEVENT_HELPER 41 /* uevent helper program, used during early boot */ 42 static ssize_t uevent_helper_show(struct kobject *kobj, 43 struct kobj_attribute *attr, char *buf) 44 { 45 return sprintf(buf, "%s\n", uevent_helper); 46 } 47 static ssize_t uevent_helper_store(struct kobject *kobj, 48 struct kobj_attribute *attr, 49 const char *buf, size_t count) 50 { 51 if (count+1 > UEVENT_HELPER_PATH_LEN) 52 return -ENOENT; 53 memcpy(uevent_helper, buf, count); 54 uevent_helper[count] = '\0'; 55 if (count && uevent_helper[count-1] == '\n') 56 uevent_helper[count-1] = '\0'; 57 return count; 58 } 59 KERNEL_ATTR_RW(uevent_helper); 60 #endif 61 62 #ifdef CONFIG_PROFILING 63 static ssize_t profiling_show(struct kobject *kobj, 64 struct kobj_attribute *attr, char *buf) 65 { 66 return sprintf(buf, "%d\n", prof_on); 67 } 68 static ssize_t profiling_store(struct kobject *kobj, 69 struct kobj_attribute *attr, 70 const char *buf, size_t count) 71 { 72 int ret; 73 74 if (prof_on) 75 return -EEXIST; 76 /* 77 * This eventually calls into get_option() which 78 * has a ton of callers and is not const. It is 79 * easiest to cast it away here. 80 */ 81 profile_setup((char *)buf); 82 ret = profile_init(); 83 if (ret) 84 return ret; 85 ret = create_proc_profile(); 86 if (ret) 87 return ret; 88 return count; 89 } 90 KERNEL_ATTR_RW(profiling); 91 #endif 92 93 #ifdef CONFIG_KEXEC_CORE 94 static ssize_t kexec_loaded_show(struct kobject *kobj, 95 struct kobj_attribute *attr, char *buf) 96 { 97 return sprintf(buf, "%d\n", !!kexec_image); 98 } 99 KERNEL_ATTR_RO(kexec_loaded); 100 101 static ssize_t kexec_crash_loaded_show(struct kobject *kobj, 102 struct kobj_attribute *attr, char *buf) 103 { 104 return sprintf(buf, "%d\n", !!kexec_crash_image); 105 } 106 KERNEL_ATTR_RO(kexec_crash_loaded); 107 108 static ssize_t kexec_crash_size_show(struct kobject *kobj, 109 struct kobj_attribute *attr, char *buf) 110 { 111 return sprintf(buf, "%zu\n", crash_get_memory_size()); 112 } 113 static ssize_t kexec_crash_size_store(struct kobject *kobj, 114 struct kobj_attribute *attr, 115 const char *buf, size_t count) 116 { 117 unsigned long cnt; 118 int ret; 119 120 if (kstrtoul(buf, 0, &cnt)) 121 return -EINVAL; 122 123 ret = crash_shrink_memory(cnt); 124 return ret < 0 ? ret : count; 125 } 126 KERNEL_ATTR_RW(kexec_crash_size); 127 128 static ssize_t vmcoreinfo_show(struct kobject *kobj, 129 struct kobj_attribute *attr, char *buf) 130 { 131 return sprintf(buf, "%lx %x\n", 132 paddr_vmcoreinfo_note(), 133 (unsigned int)sizeof(vmcoreinfo_note)); 134 } 135 KERNEL_ATTR_RO(vmcoreinfo); 136 137 #endif /* CONFIG_KEXEC_CORE */ 138 139 /* whether file capabilities are enabled */ 140 static ssize_t fscaps_show(struct kobject *kobj, 141 struct kobj_attribute *attr, char *buf) 142 { 143 return sprintf(buf, "%d\n", file_caps_enabled); 144 } 145 KERNEL_ATTR_RO(fscaps); 146 147 #ifndef CONFIG_TINY_RCU 148 int rcu_expedited; 149 static ssize_t rcu_expedited_show(struct kobject *kobj, 150 struct kobj_attribute *attr, char *buf) 151 { 152 return sprintf(buf, "%d\n", READ_ONCE(rcu_expedited)); 153 } 154 static ssize_t rcu_expedited_store(struct kobject *kobj, 155 struct kobj_attribute *attr, 156 const char *buf, size_t count) 157 { 158 if (kstrtoint(buf, 0, &rcu_expedited)) 159 return -EINVAL; 160 161 return count; 162 } 163 KERNEL_ATTR_RW(rcu_expedited); 164 165 int rcu_normal; 166 static ssize_t rcu_normal_show(struct kobject *kobj, 167 struct kobj_attribute *attr, char *buf) 168 { 169 return sprintf(buf, "%d\n", READ_ONCE(rcu_normal)); 170 } 171 static ssize_t rcu_normal_store(struct kobject *kobj, 172 struct kobj_attribute *attr, 173 const char *buf, size_t count) 174 { 175 if (kstrtoint(buf, 0, &rcu_normal)) 176 return -EINVAL; 177 178 return count; 179 } 180 KERNEL_ATTR_RW(rcu_normal); 181 #endif /* #ifndef CONFIG_TINY_RCU */ 182 183 /* 184 * Make /sys/kernel/notes give the raw contents of our kernel .notes section. 185 */ 186 extern const void __start_notes __weak; 187 extern const void __stop_notes __weak; 188 #define notes_size (&__stop_notes - &__start_notes) 189 190 static ssize_t notes_read(struct file *filp, struct kobject *kobj, 191 struct bin_attribute *bin_attr, 192 char *buf, loff_t off, size_t count) 193 { 194 memcpy(buf, &__start_notes + off, count); 195 return count; 196 } 197 198 static struct bin_attribute notes_attr = { 199 .attr = { 200 .name = "notes", 201 .mode = S_IRUGO, 202 }, 203 .read = ¬es_read, 204 }; 205 206 struct kobject *kernel_kobj; 207 EXPORT_SYMBOL_GPL(kernel_kobj); 208 209 static struct attribute * kernel_attrs[] = { 210 &fscaps_attr.attr, 211 &uevent_seqnum_attr.attr, 212 #ifdef CONFIG_UEVENT_HELPER 213 &uevent_helper_attr.attr, 214 #endif 215 #ifdef CONFIG_PROFILING 216 &profiling_attr.attr, 217 #endif 218 #ifdef CONFIG_KEXEC_CORE 219 &kexec_loaded_attr.attr, 220 &kexec_crash_loaded_attr.attr, 221 &kexec_crash_size_attr.attr, 222 &vmcoreinfo_attr.attr, 223 #endif 224 #ifndef CONFIG_TINY_RCU 225 &rcu_expedited_attr.attr, 226 &rcu_normal_attr.attr, 227 #endif 228 NULL 229 }; 230 231 static struct attribute_group kernel_attr_group = { 232 .attrs = kernel_attrs, 233 }; 234 235 static int __init ksysfs_init(void) 236 { 237 int error; 238 239 kernel_kobj = kobject_create_and_add("kernel", NULL); 240 if (!kernel_kobj) { 241 error = -ENOMEM; 242 goto exit; 243 } 244 error = sysfs_create_group(kernel_kobj, &kernel_attr_group); 245 if (error) 246 goto kset_exit; 247 248 if (notes_size > 0) { 249 notes_attr.size = notes_size; 250 error = sysfs_create_bin_file(kernel_kobj, ¬es_attr); 251 if (error) 252 goto group_exit; 253 } 254 255 return 0; 256 257 group_exit: 258 sysfs_remove_group(kernel_kobj, &kernel_attr_group); 259 kset_exit: 260 kobject_put(kernel_kobj); 261 exit: 262 return error; 263 } 264 265 core_initcall(ksysfs_init); 266