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 <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>
21 #include <linux/rcupdate.h> /* rcu_expedited and rcu_normal */
23 #define KERNEL_ATTR_RO(_name) \
24 static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
26 #define KERNEL_ATTR_RW(_name) \
27 static struct kobj_attribute _name##_attr = \
28 __ATTR(_name, 0644, _name##_show, _name##_store)
30 /* current uevent sequence number */
31 static ssize_t uevent_seqnum_show(struct kobject *kobj,
32 struct kobj_attribute *attr, char *buf)
34 return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum);
36 KERNEL_ATTR_RO(uevent_seqnum);
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)
43 return sprintf(buf, "%s\n", uevent_helper);
45 static ssize_t uevent_helper_store(struct kobject *kobj,
46 struct kobj_attribute *attr,
47 const char *buf, size_t count)
49 if (count+1 > UEVENT_HELPER_PATH_LEN)
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';
57 KERNEL_ATTR_RW(uevent_helper);
60 #ifdef CONFIG_PROFILING
61 static ssize_t profiling_show(struct kobject *kobj,
62 struct kobj_attribute *attr, char *buf)
64 return sprintf(buf, "%d\n", prof_on);
66 static ssize_t profiling_store(struct kobject *kobj,
67 struct kobj_attribute *attr,
68 const char *buf, size_t count)
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.
79 profile_setup((char *)buf);
83 ret = create_proc_profile();
88 KERNEL_ATTR_RW(profiling);
91 #ifdef CONFIG_KEXEC_CORE
92 static ssize_t kexec_loaded_show(struct kobject *kobj,
93 struct kobj_attribute *attr, char *buf)
95 return sprintf(buf, "%d\n", !!kexec_image);
97 KERNEL_ATTR_RO(kexec_loaded);
99 static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
100 struct kobj_attribute *attr, char *buf)
102 return sprintf(buf, "%d\n", kexec_crash_loaded());
104 KERNEL_ATTR_RO(kexec_crash_loaded);
106 static ssize_t kexec_crash_size_show(struct kobject *kobj,
107 struct kobj_attribute *attr, char *buf)
109 return sprintf(buf, "%zu\n", crash_get_memory_size());
111 static ssize_t kexec_crash_size_store(struct kobject *kobj,
112 struct kobj_attribute *attr,
113 const char *buf, size_t count)
118 if (kstrtoul(buf, 0, &cnt))
121 ret = crash_shrink_memory(cnt);
122 return ret < 0 ? ret : count;
124 KERNEL_ATTR_RW(kexec_crash_size);
126 #endif /* CONFIG_KEXEC_CORE */
128 #ifdef CONFIG_CRASH_CORE
130 static ssize_t vmcoreinfo_show(struct kobject *kobj,
131 struct kobj_attribute *attr, char *buf)
133 phys_addr_t vmcore_base = paddr_vmcoreinfo_note();
134 return sprintf(buf, "%pa %x\n", &vmcore_base,
135 (unsigned int)VMCOREINFO_NOTE_SIZE);
137 KERNEL_ATTR_RO(vmcoreinfo);
139 #endif /* CONFIG_CRASH_CORE */
141 #if defined(CONFIG_PREEMPT_RT)
142 static ssize_t realtime_show(struct kobject *kobj,
143 struct kobj_attribute *attr, char *buf)
145 return sprintf(buf, "%d\n", 1);
147 KERNEL_ATTR_RO(realtime);
150 /* whether file capabilities are enabled */
151 static ssize_t fscaps_show(struct kobject *kobj,
152 struct kobj_attribute *attr, char *buf)
154 return sprintf(buf, "%d\n", file_caps_enabled);
156 KERNEL_ATTR_RO(fscaps);
158 #ifndef CONFIG_TINY_RCU
160 static ssize_t rcu_expedited_show(struct kobject *kobj,
161 struct kobj_attribute *attr, char *buf)
163 return sprintf(buf, "%d\n", READ_ONCE(rcu_expedited));
165 static ssize_t rcu_expedited_store(struct kobject *kobj,
166 struct kobj_attribute *attr,
167 const char *buf, size_t count)
169 if (kstrtoint(buf, 0, &rcu_expedited))
174 KERNEL_ATTR_RW(rcu_expedited);
177 static ssize_t rcu_normal_show(struct kobject *kobj,
178 struct kobj_attribute *attr, char *buf)
180 return sprintf(buf, "%d\n", READ_ONCE(rcu_normal));
182 static ssize_t rcu_normal_store(struct kobject *kobj,
183 struct kobj_attribute *attr,
184 const char *buf, size_t count)
186 if (kstrtoint(buf, 0, &rcu_normal))
191 KERNEL_ATTR_RW(rcu_normal);
192 #endif /* #ifndef CONFIG_TINY_RCU */
195 * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
197 extern const void __start_notes __weak;
198 extern const void __stop_notes __weak;
199 #define notes_size (&__stop_notes - &__start_notes)
201 static ssize_t notes_read(struct file *filp, struct kobject *kobj,
202 struct bin_attribute *bin_attr,
203 char *buf, loff_t off, size_t count)
205 memcpy(buf, &__start_notes + off, count);
209 static struct bin_attribute notes_attr __ro_after_init = {
217 struct kobject *kernel_kobj;
218 EXPORT_SYMBOL_GPL(kernel_kobj);
220 static struct attribute * kernel_attrs[] = {
222 &uevent_seqnum_attr.attr,
223 #ifdef CONFIG_UEVENT_HELPER
224 &uevent_helper_attr.attr,
226 #ifdef CONFIG_PROFILING
227 &profiling_attr.attr,
229 #ifdef CONFIG_KEXEC_CORE
230 &kexec_loaded_attr.attr,
231 &kexec_crash_loaded_attr.attr,
232 &kexec_crash_size_attr.attr,
234 #ifdef CONFIG_CRASH_CORE
235 &vmcoreinfo_attr.attr,
237 #ifndef CONFIG_TINY_RCU
238 &rcu_expedited_attr.attr,
239 &rcu_normal_attr.attr,
241 #ifdef CONFIG_PREEMPT_RT
247 static const struct attribute_group kernel_attr_group = {
248 .attrs = kernel_attrs,
251 static int __init ksysfs_init(void)
255 kernel_kobj = kobject_create_and_add("kernel", NULL);
260 error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
264 if (notes_size > 0) {
265 notes_attr.size = notes_size;
266 error = sysfs_create_bin_file(kernel_kobj, ¬es_attr);
274 sysfs_remove_group(kernel_kobj, &kernel_attr_group);
276 kobject_put(kernel_kobj);
281 core_initcall(ksysfs_init);