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) \
26static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
27
28#define KERNEL_ATTR_RW(_name) \
29static struct kobj_attribute _name##_attr = \
30 __ATTR(_name, 0644, _name##_show, _name##_store)
31
32/* current uevent sequence number */
33static 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}
38KERNEL_ATTR_RO(uevent_seqnum);
39
40#ifdef CONFIG_UEVENT_HELPER
41/* uevent helper program, used during early boot */
42static 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}
47static 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}
59KERNEL_ATTR_RW(uevent_helper);
60#endif
61
62#ifdef CONFIG_PROFILING
63static ssize_t profiling_show(struct kobject *kobj,
64 struct kobj_attribute *attr, char *buf)
65{
66 return sprintf(buf, "%d\n", prof_on);
67}
68static 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}
90KERNEL_ATTR_RW(profiling);
91#endif
92
93#ifdef CONFIG_KEXEC_CORE
94static 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}
99KERNEL_ATTR_RO(kexec_loaded);
100
101static 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_loaded());
105}
106KERNEL_ATTR_RO(kexec_crash_loaded);
107
108static 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}
113static 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}
126KERNEL_ATTR_RW(kexec_crash_size);
127
128#endif /* CONFIG_KEXEC_CORE */
129
130#ifdef CONFIG_CRASH_CORE
131
132static ssize_t vmcoreinfo_show(struct kobject *kobj,
133 struct kobj_attribute *attr, char *buf)
134{
135 phys_addr_t vmcore_base = paddr_vmcoreinfo_note();
136 return sprintf(buf, "%pa %x\n", &vmcore_base,
137 (unsigned int)VMCOREINFO_NOTE_SIZE);
138}
139KERNEL_ATTR_RO(vmcoreinfo);
140
141#endif /* CONFIG_CRASH_CORE */
142
143/* whether file capabilities are enabled */
144static ssize_t fscaps_show(struct kobject *kobj,
145 struct kobj_attribute *attr, char *buf)
146{
147 return sprintf(buf, "%d\n", file_caps_enabled);
148}
149KERNEL_ATTR_RO(fscaps);
150
151#ifndef CONFIG_TINY_RCU
152int rcu_expedited;
153static ssize_t rcu_expedited_show(struct kobject *kobj,
154 struct kobj_attribute *attr, char *buf)
155{
156 return sprintf(buf, "%d\n", READ_ONCE(rcu_expedited));
157}
158static ssize_t rcu_expedited_store(struct kobject *kobj,
159 struct kobj_attribute *attr,
160 const char *buf, size_t count)
161{
162 if (kstrtoint(buf, 0, &rcu_expedited))
163 return -EINVAL;
164
165 return count;
166}
167KERNEL_ATTR_RW(rcu_expedited);
168
169int rcu_normal;
170static ssize_t rcu_normal_show(struct kobject *kobj,
171 struct kobj_attribute *attr, char *buf)
172{
173 return sprintf(buf, "%d\n", READ_ONCE(rcu_normal));
174}
175static ssize_t rcu_normal_store(struct kobject *kobj,
176 struct kobj_attribute *attr,
177 const char *buf, size_t count)
178{
179 if (kstrtoint(buf, 0, &rcu_normal))
180 return -EINVAL;
181
182 return count;
183}
184KERNEL_ATTR_RW(rcu_normal);
185#endif /* #ifndef CONFIG_TINY_RCU */
186
187/*
188 * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
189 */
190extern const void __start_notes __weak;
191extern const void __stop_notes __weak;
192#define notes_size (&__stop_notes - &__start_notes)
193
194static ssize_t notes_read(struct file *filp, struct kobject *kobj,
195 struct bin_attribute *bin_attr,
196 char *buf, loff_t off, size_t count)
197{
198 memcpy(buf, &__start_notes + off, count);
199 return count;
200}
201
202static struct bin_attribute notes_attr __ro_after_init = {
203 .attr = {
204 .name = "notes",
205 .mode = S_IRUGO,
206 },
207 .read = &notes_read,
208};
209
210struct kobject *kernel_kobj;
211EXPORT_SYMBOL_GPL(kernel_kobj);
212
213static struct attribute * kernel_attrs[] = {
214 &fscaps_attr.attr,
215 &uevent_seqnum_attr.attr,
216#ifdef CONFIG_UEVENT_HELPER
217 &uevent_helper_attr.attr,
218#endif
219#ifdef CONFIG_PROFILING
220 &profiling_attr.attr,
221#endif
222#ifdef CONFIG_KEXEC_CORE
223 &kexec_loaded_attr.attr,
224 &kexec_crash_loaded_attr.attr,
225 &kexec_crash_size_attr.attr,
226#endif
227#ifdef CONFIG_CRASH_CORE
228 &vmcoreinfo_attr.attr,
229#endif
230#ifndef CONFIG_TINY_RCU
231 &rcu_expedited_attr.attr,
232 &rcu_normal_attr.attr,
233#endif
234 NULL
235};
236
237static const struct attribute_group kernel_attr_group = {
238 .attrs = kernel_attrs,
239};
240
241static int __init ksysfs_init(void)
242{
243 int error;
244
245 kernel_kobj = kobject_create_and_add("kernel", NULL);
246 if (!kernel_kobj) {
247 error = -ENOMEM;
248 goto exit;
249 }
250 error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
251 if (error)
252 goto kset_exit;
253
254 if (notes_size > 0) {
255 notes_attr.size = notes_size;
256 error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
257 if (error)
258 goto group_exit;
259 }
260
261 return 0;
262
263group_exit:
264 sysfs_remove_group(kernel_kobj, &kernel_attr_group);
265kset_exit:
266 kobject_put(kernel_kobj);
267exit:
268 return error;
269}
270
271core_initcall(ksysfs_init);
272