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