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 = \
28 __ATTR(_name, 0644, _name##_show, _name##_store)
29
30 /* current uevent sequence number */
uevent_seqnum_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)31 static ssize_t uevent_seqnum_show(struct kobject *kobj,
32 struct kobj_attribute *attr, char *buf)
33 {
34 return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum);
35 }
36 KERNEL_ATTR_RO(uevent_seqnum);
37
38 #ifdef CONFIG_UEVENT_HELPER
39 /* uevent helper program, used during early boot */
uevent_helper_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)40 static ssize_t uevent_helper_show(struct kobject *kobj,
41 struct kobj_attribute *attr, char *buf)
42 {
43 return sprintf(buf, "%s\n", uevent_helper);
44 }
uevent_helper_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)45 static ssize_t uevent_helper_store(struct kobject *kobj,
46 struct kobj_attribute *attr,
47 const char *buf, size_t count)
48 {
49 if (count+1 > UEVENT_HELPER_PATH_LEN)
50 return -ENOENT;
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';
55 return count;
56 }
57 KERNEL_ATTR_RW(uevent_helper);
58 #endif
59
60 #ifdef CONFIG_PROFILING
profiling_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)61 static ssize_t profiling_show(struct kobject *kobj,
62 struct kobj_attribute *attr, char *buf)
63 {
64 return sprintf(buf, "%d\n", prof_on);
65 }
profiling_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)66 static ssize_t profiling_store(struct kobject *kobj,
67 struct kobj_attribute *attr,
68 const char *buf, size_t count)
69 {
70 int ret;
71
72 if (prof_on)
73 return -EEXIST;
74 /*
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.
78 */
79 profile_setup((char *)buf);
80 ret = profile_init();
81 if (ret)
82 return ret;
83 ret = create_proc_profile();
84 if (ret)
85 return ret;
86 return count;
87 }
88 KERNEL_ATTR_RW(profiling);
89 #endif
90
91 #ifdef CONFIG_KEXEC_CORE
kexec_loaded_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)92 static ssize_t kexec_loaded_show(struct kobject *kobj,
93 struct kobj_attribute *attr, char *buf)
94 {
95 return sprintf(buf, "%d\n", !!kexec_image);
96 }
97 KERNEL_ATTR_RO(kexec_loaded);
98
kexec_crash_loaded_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)99 static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
100 struct kobj_attribute *attr, char *buf)
101 {
102 return sprintf(buf, "%d\n", kexec_crash_loaded());
103 }
104 KERNEL_ATTR_RO(kexec_crash_loaded);
105
kexec_crash_size_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)106 static ssize_t kexec_crash_size_show(struct kobject *kobj,
107 struct kobj_attribute *attr, char *buf)
108 {
109 ssize_t size = crash_get_memory_size();
110
111 if (size < 0)
112 return size;
113
114 return sprintf(buf, "%zd\n", size);
115 }
kexec_crash_size_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)116 static ssize_t kexec_crash_size_store(struct kobject *kobj,
117 struct kobj_attribute *attr,
118 const char *buf, size_t count)
119 {
120 unsigned long cnt;
121 int ret;
122
123 if (kstrtoul(buf, 0, &cnt))
124 return -EINVAL;
125
126 ret = crash_shrink_memory(cnt);
127 return ret < 0 ? ret : count;
128 }
129 KERNEL_ATTR_RW(kexec_crash_size);
130
131 #endif /* CONFIG_KEXEC_CORE */
132
133 #ifdef CONFIG_CRASH_CORE
134
vmcoreinfo_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)135 static ssize_t vmcoreinfo_show(struct kobject *kobj,
136 struct kobj_attribute *attr, char *buf)
137 {
138 phys_addr_t vmcore_base = paddr_vmcoreinfo_note();
139 return sprintf(buf, "%pa %x\n", &vmcore_base,
140 (unsigned int)VMCOREINFO_NOTE_SIZE);
141 }
142 KERNEL_ATTR_RO(vmcoreinfo);
143
144 #endif /* CONFIG_CRASH_CORE */
145
146 /* whether file capabilities are enabled */
fscaps_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)147 static ssize_t fscaps_show(struct kobject *kobj,
148 struct kobj_attribute *attr, char *buf)
149 {
150 return sprintf(buf, "%d\n", file_caps_enabled);
151 }
152 KERNEL_ATTR_RO(fscaps);
153
154 #ifndef CONFIG_TINY_RCU
155 int rcu_expedited;
rcu_expedited_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)156 static ssize_t rcu_expedited_show(struct kobject *kobj,
157 struct kobj_attribute *attr, char *buf)
158 {
159 return sprintf(buf, "%d\n", READ_ONCE(rcu_expedited));
160 }
rcu_expedited_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)161 static ssize_t rcu_expedited_store(struct kobject *kobj,
162 struct kobj_attribute *attr,
163 const char *buf, size_t count)
164 {
165 if (kstrtoint(buf, 0, &rcu_expedited))
166 return -EINVAL;
167
168 return count;
169 }
170 KERNEL_ATTR_RW(rcu_expedited);
171
172 int rcu_normal;
rcu_normal_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)173 static ssize_t rcu_normal_show(struct kobject *kobj,
174 struct kobj_attribute *attr, char *buf)
175 {
176 return sprintf(buf, "%d\n", READ_ONCE(rcu_normal));
177 }
rcu_normal_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)178 static ssize_t rcu_normal_store(struct kobject *kobj,
179 struct kobj_attribute *attr,
180 const char *buf, size_t count)
181 {
182 if (kstrtoint(buf, 0, &rcu_normal))
183 return -EINVAL;
184
185 return count;
186 }
187 KERNEL_ATTR_RW(rcu_normal);
188 #endif /* #ifndef CONFIG_TINY_RCU */
189
190 /*
191 * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
192 */
193 extern const void __start_notes __weak;
194 extern const void __stop_notes __weak;
195 #define notes_size (&__stop_notes - &__start_notes)
196
notes_read(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t count)197 static ssize_t notes_read(struct file *filp, struct kobject *kobj,
198 struct bin_attribute *bin_attr,
199 char *buf, loff_t off, size_t count)
200 {
201 memcpy(buf, &__start_notes + off, count);
202 return count;
203 }
204
205 static struct bin_attribute notes_attr __ro_after_init = {
206 .attr = {
207 .name = "notes",
208 .mode = S_IRUGO,
209 },
210 .read = ¬es_read,
211 };
212
213 struct kobject *kernel_kobj;
214 EXPORT_SYMBOL_GPL(kernel_kobj);
215
216 static struct attribute * kernel_attrs[] = {
217 &fscaps_attr.attr,
218 &uevent_seqnum_attr.attr,
219 #ifdef CONFIG_UEVENT_HELPER
220 &uevent_helper_attr.attr,
221 #endif
222 #ifdef CONFIG_PROFILING
223 &profiling_attr.attr,
224 #endif
225 #ifdef CONFIG_KEXEC_CORE
226 &kexec_loaded_attr.attr,
227 &kexec_crash_loaded_attr.attr,
228 &kexec_crash_size_attr.attr,
229 #endif
230 #ifdef CONFIG_CRASH_CORE
231 &vmcoreinfo_attr.attr,
232 #endif
233 #ifndef CONFIG_TINY_RCU
234 &rcu_expedited_attr.attr,
235 &rcu_normal_attr.attr,
236 #endif
237 NULL
238 };
239
240 static const struct attribute_group kernel_attr_group = {
241 .attrs = kernel_attrs,
242 };
243
ksysfs_init(void)244 static int __init ksysfs_init(void)
245 {
246 int error;
247
248 kernel_kobj = kobject_create_and_add("kernel", NULL);
249 if (!kernel_kobj) {
250 error = -ENOMEM;
251 goto exit;
252 }
253 error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
254 if (error)
255 goto kset_exit;
256
257 if (notes_size > 0) {
258 notes_attr.size = notes_size;
259 error = sysfs_create_bin_file(kernel_kobj, ¬es_attr);
260 if (error)
261 goto group_exit;
262 }
263
264 return 0;
265
266 group_exit:
267 sysfs_remove_group(kernel_kobj, &kernel_attr_group);
268 kset_exit:
269 kobject_put(kernel_kobj);
270 exit:
271 return error;
272 }
273
274 core_initcall(ksysfs_init);
275