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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 */ | |
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 */ | |
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 | } | |
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 | |
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 | } | |
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 | |
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 | ||
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 | ||
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 | } | |
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 | ||
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 */ | |
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; | |
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 | } | |
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; | |
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 | } | |
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 | ||
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 | ||
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); |