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 */
uevent_seqnum_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)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 */
uevent_helper_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)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 }
uevent_helper_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)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
profiling_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)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 }
profiling_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)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
kexec_loaded_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)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
kexec_crash_loaded_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)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
kexec_crash_size_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)105 static ssize_t kexec_crash_size_show(struct kobject *kobj,
106 struct kobj_attribute *attr, char *buf)
107 {
108 ssize_t size = crash_get_memory_size();
109
110 if (size < 0)
111 return size;
112
113 return sprintf(buf, "%zd\n", size);
114 }
kexec_crash_size_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)115 static ssize_t kexec_crash_size_store(struct kobject *kobj,
116 struct kobj_attribute *attr,
117 const char *buf, size_t count)
118 {
119 unsigned long cnt;
120 int ret;
121
122 if (kstrtoul(buf, 0, &cnt))
123 return -EINVAL;
124
125 ret = crash_shrink_memory(cnt);
126 return ret < 0 ? ret : count;
127 }
128 KERNEL_ATTR_RW(kexec_crash_size);
129
130 #endif /* CONFIG_KEXEC_CORE */
131
132 #ifdef CONFIG_CRASH_CORE
133
vmcoreinfo_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)134 static ssize_t vmcoreinfo_show(struct kobject *kobj,
135 struct kobj_attribute *attr, char *buf)
136 {
137 phys_addr_t vmcore_base = paddr_vmcoreinfo_note();
138 return sprintf(buf, "%pa %x\n", &vmcore_base,
139 (unsigned int)VMCOREINFO_NOTE_SIZE);
140 }
141 KERNEL_ATTR_RO(vmcoreinfo);
142
143 #endif /* CONFIG_CRASH_CORE */
144
145 /* whether file capabilities are enabled */
fscaps_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)146 static ssize_t fscaps_show(struct kobject *kobj,
147 struct kobj_attribute *attr, char *buf)
148 {
149 return sprintf(buf, "%d\n", file_caps_enabled);
150 }
151 KERNEL_ATTR_RO(fscaps);
152
153 #ifndef CONFIG_TINY_RCU
154 int rcu_expedited;
rcu_expedited_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)155 static ssize_t rcu_expedited_show(struct kobject *kobj,
156 struct kobj_attribute *attr, char *buf)
157 {
158 return sprintf(buf, "%d\n", READ_ONCE(rcu_expedited));
159 }
rcu_expedited_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)160 static ssize_t rcu_expedited_store(struct kobject *kobj,
161 struct kobj_attribute *attr,
162 const char *buf, size_t count)
163 {
164 if (kstrtoint(buf, 0, &rcu_expedited))
165 return -EINVAL;
166
167 return count;
168 }
169 KERNEL_ATTR_RW(rcu_expedited);
170
171 int rcu_normal;
rcu_normal_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)172 static ssize_t rcu_normal_show(struct kobject *kobj,
173 struct kobj_attribute *attr, char *buf)
174 {
175 return sprintf(buf, "%d\n", READ_ONCE(rcu_normal));
176 }
rcu_normal_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)177 static ssize_t rcu_normal_store(struct kobject *kobj,
178 struct kobj_attribute *attr,
179 const char *buf, size_t count)
180 {
181 if (kstrtoint(buf, 0, &rcu_normal))
182 return -EINVAL;
183
184 return count;
185 }
186 KERNEL_ATTR_RW(rcu_normal);
187 #endif /* #ifndef CONFIG_TINY_RCU */
188
189 /*
190 * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
191 */
192 extern const void __start_notes __weak;
193 extern const void __stop_notes __weak;
194 #define notes_size (&__stop_notes - &__start_notes)
195
notes_read(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t count)196 static ssize_t notes_read(struct file *filp, struct kobject *kobj,
197 struct bin_attribute *bin_attr,
198 char *buf, loff_t off, size_t count)
199 {
200 memcpy(buf, &__start_notes + off, count);
201 return count;
202 }
203
204 static struct bin_attribute notes_attr __ro_after_init = {
205 .attr = {
206 .name = "notes",
207 .mode = S_IRUGO,
208 },
209 .read = ¬es_read,
210 };
211
212 struct kobject *kernel_kobj;
213 EXPORT_SYMBOL_GPL(kernel_kobj);
214
215 static struct attribute * kernel_attrs[] = {
216 &fscaps_attr.attr,
217 &uevent_seqnum_attr.attr,
218 #ifdef CONFIG_UEVENT_HELPER
219 &uevent_helper_attr.attr,
220 #endif
221 #ifdef CONFIG_PROFILING
222 &profiling_attr.attr,
223 #endif
224 #ifdef CONFIG_KEXEC_CORE
225 &kexec_loaded_attr.attr,
226 &kexec_crash_loaded_attr.attr,
227 &kexec_crash_size_attr.attr,
228 #endif
229 #ifdef CONFIG_CRASH_CORE
230 &vmcoreinfo_attr.attr,
231 #endif
232 #ifndef CONFIG_TINY_RCU
233 &rcu_expedited_attr.attr,
234 &rcu_normal_attr.attr,
235 #endif
236 NULL
237 };
238
239 static const struct attribute_group kernel_attr_group = {
240 .attrs = kernel_attrs,
241 };
242
ksysfs_init(void)243 static int __init ksysfs_init(void)
244 {
245 int error;
246
247 kernel_kobj = kobject_create_and_add("kernel", NULL);
248 if (!kernel_kobj) {
249 error = -ENOMEM;
250 goto exit;
251 }
252 error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
253 if (error)
254 goto kset_exit;
255
256 if (notes_size > 0) {
257 notes_attr.size = notes_size;
258 error = sysfs_create_bin_file(kernel_kobj, ¬es_attr);
259 if (error)
260 goto group_exit;
261 }
262
263 return 0;
264
265 group_exit:
266 sysfs_remove_group(kernel_kobj, &kernel_attr_group);
267 kset_exit:
268 kobject_put(kernel_kobj);
269 exit:
270 return error;
271 }
272
273 core_initcall(ksysfs_init);
274