1 // SPDX-License-Identifier: GPL-2.0-only
3 * kernel/ksysfs.c - sysfs attributes in /sys/kernel, which
4 * are not related to any other subsystem
6 * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
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/kexec.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>
22 #include <linux/rcupdate.h> /* rcu_expedited and rcu_normal */
24 #if defined(__LITTLE_ENDIAN)
25 #define CPU_BYTEORDER_STRING "little"
26 #elif defined(__BIG_ENDIAN)
27 #define CPU_BYTEORDER_STRING "big"
29 #error Unknown byteorder
32 #define KERNEL_ATTR_RO(_name) \
33 static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
35 #define KERNEL_ATTR_RW(_name) \
36 static struct kobj_attribute _name##_attr = __ATTR_RW(_name)
38 /* current uevent sequence number */
39 static ssize_t uevent_seqnum_show(struct kobject *kobj,
40 struct kobj_attribute *attr, char *buf)
42 return sysfs_emit(buf, "%llu\n", (unsigned long long)uevent_seqnum);
44 KERNEL_ATTR_RO(uevent_seqnum);
47 static ssize_t cpu_byteorder_show(struct kobject *kobj,
48 struct kobj_attribute *attr, char *buf)
50 return sysfs_emit(buf, "%s\n", CPU_BYTEORDER_STRING);
52 KERNEL_ATTR_RO(cpu_byteorder);
55 static ssize_t address_bits_show(struct kobject *kobj,
56 struct kobj_attribute *attr, char *buf)
58 return sysfs_emit(buf, "%zu\n", sizeof(void *) * 8 /* CHAR_BIT */);
60 KERNEL_ATTR_RO(address_bits);
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)
67 return sysfs_emit(buf, "%s\n", uevent_helper);
69 static ssize_t uevent_helper_store(struct kobject *kobj,
70 struct kobj_attribute *attr,
71 const char *buf, size_t count)
73 if (count+1 > UEVENT_HELPER_PATH_LEN)
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';
81 KERNEL_ATTR_RW(uevent_helper);
84 #ifdef CONFIG_PROFILING
85 static ssize_t profiling_show(struct kobject *kobj,
86 struct kobj_attribute *attr, char *buf)
88 return sysfs_emit(buf, "%d\n", prof_on);
90 static ssize_t profiling_store(struct kobject *kobj,
91 struct kobj_attribute *attr,
92 const char *buf, size_t count)
99 * This eventually calls into get_option() which
100 * has a ton of callers and is not const. It is
101 * easiest to cast it away here.
103 profile_setup((char *)buf);
104 ret = profile_init();
107 ret = create_proc_profile();
112 KERNEL_ATTR_RW(profiling);
115 #ifdef CONFIG_KEXEC_CORE
116 static ssize_t kexec_loaded_show(struct kobject *kobj,
117 struct kobj_attribute *attr, char *buf)
119 return sysfs_emit(buf, "%d\n", !!kexec_image);
121 KERNEL_ATTR_RO(kexec_loaded);
123 static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
124 struct kobj_attribute *attr, char *buf)
126 return sysfs_emit(buf, "%d\n", kexec_crash_loaded());
128 KERNEL_ATTR_RO(kexec_crash_loaded);
130 static ssize_t kexec_crash_size_show(struct kobject *kobj,
131 struct kobj_attribute *attr, char *buf)
133 ssize_t size = crash_get_memory_size();
138 return sysfs_emit(buf, "%zd\n", size);
140 static ssize_t kexec_crash_size_store(struct kobject *kobj,
141 struct kobj_attribute *attr,
142 const char *buf, size_t count)
147 if (kstrtoul(buf, 0, &cnt))
150 ret = crash_shrink_memory(cnt);
151 return ret < 0 ? ret : count;
153 KERNEL_ATTR_RW(kexec_crash_size);
155 #endif /* CONFIG_KEXEC_CORE */
157 #ifdef CONFIG_CRASH_CORE
159 static ssize_t vmcoreinfo_show(struct kobject *kobj,
160 struct kobj_attribute *attr, char *buf)
162 phys_addr_t vmcore_base = paddr_vmcoreinfo_note();
163 return sysfs_emit(buf, "%pa %x\n", &vmcore_base,
164 (unsigned int)VMCOREINFO_NOTE_SIZE);
166 KERNEL_ATTR_RO(vmcoreinfo);
168 #ifdef CONFIG_CRASH_HOTPLUG
169 static ssize_t crash_elfcorehdr_size_show(struct kobject *kobj,
170 struct kobj_attribute *attr, char *buf)
172 unsigned int sz = crash_get_elfcorehdr_size();
174 return sysfs_emit(buf, "%u\n", sz);
176 KERNEL_ATTR_RO(crash_elfcorehdr_size);
180 #endif /* CONFIG_CRASH_CORE */
182 #if defined(CONFIG_PREEMPT_RT)
183 static ssize_t realtime_show(struct kobject *kobj,
184 struct kobj_attribute *attr, char *buf)
186 return sprintf(buf, "%d\n", 1);
188 KERNEL_ATTR_RO(realtime);
191 /* whether file capabilities are enabled */
192 static ssize_t fscaps_show(struct kobject *kobj,
193 struct kobj_attribute *attr, char *buf)
195 return sysfs_emit(buf, "%d\n", file_caps_enabled);
197 KERNEL_ATTR_RO(fscaps);
199 #ifndef CONFIG_TINY_RCU
201 static ssize_t rcu_expedited_show(struct kobject *kobj,
202 struct kobj_attribute *attr, char *buf)
204 return sysfs_emit(buf, "%d\n", READ_ONCE(rcu_expedited));
206 static ssize_t rcu_expedited_store(struct kobject *kobj,
207 struct kobj_attribute *attr,
208 const char *buf, size_t count)
210 if (kstrtoint(buf, 0, &rcu_expedited))
215 KERNEL_ATTR_RW(rcu_expedited);
218 static ssize_t rcu_normal_show(struct kobject *kobj,
219 struct kobj_attribute *attr, char *buf)
221 return sysfs_emit(buf, "%d\n", READ_ONCE(rcu_normal));
223 static ssize_t rcu_normal_store(struct kobject *kobj,
224 struct kobj_attribute *attr,
225 const char *buf, size_t count)
227 if (kstrtoint(buf, 0, &rcu_normal))
232 KERNEL_ATTR_RW(rcu_normal);
233 #endif /* #ifndef CONFIG_TINY_RCU */
236 * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
238 extern const void __start_notes __weak;
239 extern const void __stop_notes __weak;
240 #define notes_size (&__stop_notes - &__start_notes)
242 static ssize_t notes_read(struct file *filp, struct kobject *kobj,
243 struct bin_attribute *bin_attr,
244 char *buf, loff_t off, size_t count)
246 memcpy(buf, &__start_notes + off, count);
250 static struct bin_attribute notes_attr __ro_after_init = {
258 struct kobject *kernel_kobj;
259 EXPORT_SYMBOL_GPL(kernel_kobj);
261 static struct attribute * kernel_attrs[] = {
263 &uevent_seqnum_attr.attr,
264 &cpu_byteorder_attr.attr,
265 &address_bits_attr.attr,
266 #ifdef CONFIG_UEVENT_HELPER
267 &uevent_helper_attr.attr,
269 #ifdef CONFIG_PROFILING
270 &profiling_attr.attr,
272 #ifdef CONFIG_KEXEC_CORE
273 &kexec_loaded_attr.attr,
274 &kexec_crash_loaded_attr.attr,
275 &kexec_crash_size_attr.attr,
277 #ifdef CONFIG_CRASH_CORE
278 &vmcoreinfo_attr.attr,
279 #ifdef CONFIG_CRASH_HOTPLUG
280 &crash_elfcorehdr_size_attr.attr,
283 #ifndef CONFIG_TINY_RCU
284 &rcu_expedited_attr.attr,
285 &rcu_normal_attr.attr,
287 #ifdef CONFIG_PREEMPT_RT
293 static const struct attribute_group kernel_attr_group = {
294 .attrs = kernel_attrs,
297 static int __init ksysfs_init(void)
301 kernel_kobj = kobject_create_and_add("kernel", NULL);
306 error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
310 if (notes_size > 0) {
311 notes_attr.size = notes_size;
312 error = sysfs_create_bin_file(kernel_kobj, ¬es_attr);
320 sysfs_remove_group(kernel_kobj, &kernel_attr_group);
322 kobject_put(kernel_kobj);
327 core_initcall(ksysfs_init);