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 <asm/byteorder.h> |
10 | #include <linux/kobject.h> |
11 | #include <linux/string.h> |
12 | #include <linux/sysfs.h> |
13 | #include <linux/export.h> |
14 | #include <linux/init.h> |
15 | #include <linux/kexec.h> |
16 | #include <linux/profile.h> |
17 | #include <linux/stat.h> |
18 | #include <linux/sched.h> |
19 | #include <linux/capability.h> |
20 | #include <linux/compiler.h> |
21 | |
22 | #include <linux/rcupdate.h> /* rcu_expedited and rcu_normal */ |
23 | |
24 | #if defined(__LITTLE_ENDIAN) |
25 | #define CPU_BYTEORDER_STRING "little" |
26 | #elif defined(__BIG_ENDIAN) |
27 | #define CPU_BYTEORDER_STRING "big" |
28 | #else |
29 | #error Unknown byteorder |
30 | #endif |
31 | |
32 | #define KERNEL_ATTR_RO(_name) \ |
33 | static struct kobj_attribute _name##_attr = __ATTR_RO(_name) |
34 | |
35 | #define KERNEL_ATTR_RW(_name) \ |
36 | static struct kobj_attribute _name##_attr = __ATTR_RW(_name) |
37 | |
38 | /* current uevent sequence number */ |
39 | static ssize_t uevent_seqnum_show(struct kobject *kobj, |
40 | struct kobj_attribute *attr, char *buf) |
41 | { |
42 | return sysfs_emit(buf, fmt: "%llu\n" , (unsigned long long)uevent_seqnum); |
43 | } |
44 | KERNEL_ATTR_RO(uevent_seqnum); |
45 | |
46 | /* cpu byteorder */ |
47 | static ssize_t cpu_byteorder_show(struct kobject *kobj, |
48 | struct kobj_attribute *attr, char *buf) |
49 | { |
50 | return sysfs_emit(buf, fmt: "%s\n" , CPU_BYTEORDER_STRING); |
51 | } |
52 | KERNEL_ATTR_RO(cpu_byteorder); |
53 | |
54 | /* address bits */ |
55 | static ssize_t address_bits_show(struct kobject *kobj, |
56 | struct kobj_attribute *attr, char *buf) |
57 | { |
58 | return sysfs_emit(buf, fmt: "%zu\n" , sizeof(void *) * 8 /* CHAR_BIT */); |
59 | } |
60 | KERNEL_ATTR_RO(address_bits); |
61 | |
62 | #ifdef CONFIG_UEVENT_HELPER |
63 | /* uevent helper program, used during early boot */ |
64 | static ssize_t uevent_helper_show(struct kobject *kobj, |
65 | struct kobj_attribute *attr, char *buf) |
66 | { |
67 | return sysfs_emit(buf, fmt: "%s\n" , uevent_helper); |
68 | } |
69 | static ssize_t uevent_helper_store(struct kobject *kobj, |
70 | struct kobj_attribute *attr, |
71 | const char *buf, size_t count) |
72 | { |
73 | if (count+1 > UEVENT_HELPER_PATH_LEN) |
74 | return -ENOENT; |
75 | memcpy(uevent_helper, buf, count); |
76 | uevent_helper[count] = '\0'; |
77 | if (count && uevent_helper[count-1] == '\n') |
78 | uevent_helper[count-1] = '\0'; |
79 | return count; |
80 | } |
81 | KERNEL_ATTR_RW(uevent_helper); |
82 | #endif |
83 | |
84 | #ifdef CONFIG_PROFILING |
85 | static ssize_t profiling_show(struct kobject *kobj, |
86 | struct kobj_attribute *attr, char *buf) |
87 | { |
88 | return sysfs_emit(buf, fmt: "%d\n" , prof_on); |
89 | } |
90 | static ssize_t profiling_store(struct kobject *kobj, |
91 | struct kobj_attribute *attr, |
92 | const char *buf, size_t count) |
93 | { |
94 | int ret; |
95 | |
96 | if (prof_on) |
97 | return -EEXIST; |
98 | /* |
99 | * This eventually calls into get_option() which |
100 | * has a ton of callers and is not const. It is |
101 | * easiest to cast it away here. |
102 | */ |
103 | profile_setup(str: (char *)buf); |
104 | ret = profile_init(); |
105 | if (ret) |
106 | return ret; |
107 | ret = create_proc_profile(); |
108 | if (ret) |
109 | return ret; |
110 | return count; |
111 | } |
112 | KERNEL_ATTR_RW(profiling); |
113 | #endif |
114 | |
115 | #ifdef CONFIG_KEXEC_CORE |
116 | static ssize_t kexec_loaded_show(struct kobject *kobj, |
117 | struct kobj_attribute *attr, char *buf) |
118 | { |
119 | return sysfs_emit(buf, fmt: "%d\n" , !!kexec_image); |
120 | } |
121 | KERNEL_ATTR_RO(kexec_loaded); |
122 | |
123 | static ssize_t kexec_crash_loaded_show(struct kobject *kobj, |
124 | struct kobj_attribute *attr, char *buf) |
125 | { |
126 | return sysfs_emit(buf, fmt: "%d\n" , kexec_crash_loaded()); |
127 | } |
128 | KERNEL_ATTR_RO(kexec_crash_loaded); |
129 | |
130 | static ssize_t kexec_crash_size_show(struct kobject *kobj, |
131 | struct kobj_attribute *attr, char *buf) |
132 | { |
133 | ssize_t size = crash_get_memory_size(); |
134 | |
135 | if (size < 0) |
136 | return size; |
137 | |
138 | return sysfs_emit(buf, fmt: "%zd\n" , size); |
139 | } |
140 | static ssize_t kexec_crash_size_store(struct kobject *kobj, |
141 | struct kobj_attribute *attr, |
142 | const char *buf, size_t count) |
143 | { |
144 | unsigned long cnt; |
145 | int ret; |
146 | |
147 | if (kstrtoul(s: buf, base: 0, res: &cnt)) |
148 | return -EINVAL; |
149 | |
150 | ret = crash_shrink_memory(new_size: cnt); |
151 | return ret < 0 ? ret : count; |
152 | } |
153 | KERNEL_ATTR_RW(kexec_crash_size); |
154 | |
155 | #endif /* CONFIG_KEXEC_CORE */ |
156 | |
157 | #ifdef CONFIG_CRASH_CORE |
158 | |
159 | static ssize_t vmcoreinfo_show(struct kobject *kobj, |
160 | struct kobj_attribute *attr, char *buf) |
161 | { |
162 | phys_addr_t vmcore_base = paddr_vmcoreinfo_note(); |
163 | return sysfs_emit(buf, fmt: "%pa %x\n" , &vmcore_base, |
164 | (unsigned int)VMCOREINFO_NOTE_SIZE); |
165 | } |
166 | KERNEL_ATTR_RO(vmcoreinfo); |
167 | |
168 | #ifdef CONFIG_CRASH_HOTPLUG |
169 | static ssize_t crash_elfcorehdr_size_show(struct kobject *kobj, |
170 | struct kobj_attribute *attr, char *buf) |
171 | { |
172 | unsigned int sz = crash_get_elfcorehdr_size(); |
173 | |
174 | return sysfs_emit(buf, fmt: "%u\n" , sz); |
175 | } |
176 | KERNEL_ATTR_RO(crash_elfcorehdr_size); |
177 | |
178 | #endif |
179 | |
180 | #endif /* CONFIG_CRASH_CORE */ |
181 | |
182 | /* whether file capabilities are enabled */ |
183 | static ssize_t fscaps_show(struct kobject *kobj, |
184 | struct kobj_attribute *attr, char *buf) |
185 | { |
186 | return sysfs_emit(buf, fmt: "%d\n" , file_caps_enabled); |
187 | } |
188 | KERNEL_ATTR_RO(fscaps); |
189 | |
190 | #ifndef CONFIG_TINY_RCU |
191 | int rcu_expedited; |
192 | static ssize_t rcu_expedited_show(struct kobject *kobj, |
193 | struct kobj_attribute *attr, char *buf) |
194 | { |
195 | return sysfs_emit(buf, fmt: "%d\n" , READ_ONCE(rcu_expedited)); |
196 | } |
197 | static ssize_t rcu_expedited_store(struct kobject *kobj, |
198 | struct kobj_attribute *attr, |
199 | const char *buf, size_t count) |
200 | { |
201 | if (kstrtoint(s: buf, base: 0, res: &rcu_expedited)) |
202 | return -EINVAL; |
203 | |
204 | return count; |
205 | } |
206 | KERNEL_ATTR_RW(rcu_expedited); |
207 | |
208 | int rcu_normal; |
209 | static ssize_t rcu_normal_show(struct kobject *kobj, |
210 | struct kobj_attribute *attr, char *buf) |
211 | { |
212 | return sysfs_emit(buf, fmt: "%d\n" , READ_ONCE(rcu_normal)); |
213 | } |
214 | static ssize_t rcu_normal_store(struct kobject *kobj, |
215 | struct kobj_attribute *attr, |
216 | const char *buf, size_t count) |
217 | { |
218 | if (kstrtoint(s: buf, base: 0, res: &rcu_normal)) |
219 | return -EINVAL; |
220 | |
221 | return count; |
222 | } |
223 | KERNEL_ATTR_RW(rcu_normal); |
224 | #endif /* #ifndef CONFIG_TINY_RCU */ |
225 | |
226 | /* |
227 | * Make /sys/kernel/notes give the raw contents of our kernel .notes section. |
228 | */ |
229 | extern const void __start_notes __weak; |
230 | extern const void __stop_notes __weak; |
231 | #define notes_size (&__stop_notes - &__start_notes) |
232 | |
233 | static ssize_t notes_read(struct file *filp, struct kobject *kobj, |
234 | struct bin_attribute *bin_attr, |
235 | char *buf, loff_t off, size_t count) |
236 | { |
237 | memcpy(buf, &__start_notes + off, count); |
238 | return count; |
239 | } |
240 | |
241 | static struct bin_attribute notes_attr __ro_after_init = { |
242 | .attr = { |
243 | .name = "notes" , |
244 | .mode = S_IRUGO, |
245 | }, |
246 | .read = ¬es_read, |
247 | }; |
248 | |
249 | struct kobject *kernel_kobj; |
250 | EXPORT_SYMBOL_GPL(kernel_kobj); |
251 | |
252 | static struct attribute * kernel_attrs[] = { |
253 | &fscaps_attr.attr, |
254 | &uevent_seqnum_attr.attr, |
255 | &cpu_byteorder_attr.attr, |
256 | &address_bits_attr.attr, |
257 | #ifdef CONFIG_UEVENT_HELPER |
258 | &uevent_helper_attr.attr, |
259 | #endif |
260 | #ifdef CONFIG_PROFILING |
261 | &profiling_attr.attr, |
262 | #endif |
263 | #ifdef CONFIG_KEXEC_CORE |
264 | &kexec_loaded_attr.attr, |
265 | &kexec_crash_loaded_attr.attr, |
266 | &kexec_crash_size_attr.attr, |
267 | #endif |
268 | #ifdef CONFIG_CRASH_CORE |
269 | &vmcoreinfo_attr.attr, |
270 | #ifdef CONFIG_CRASH_HOTPLUG |
271 | &crash_elfcorehdr_size_attr.attr, |
272 | #endif |
273 | #endif |
274 | #ifndef CONFIG_TINY_RCU |
275 | &rcu_expedited_attr.attr, |
276 | &rcu_normal_attr.attr, |
277 | #endif |
278 | NULL |
279 | }; |
280 | |
281 | static const struct attribute_group kernel_attr_group = { |
282 | .attrs = kernel_attrs, |
283 | }; |
284 | |
285 | static int __init ksysfs_init(void) |
286 | { |
287 | int error; |
288 | |
289 | kernel_kobj = kobject_create_and_add(name: "kernel" , NULL); |
290 | if (!kernel_kobj) { |
291 | error = -ENOMEM; |
292 | goto exit; |
293 | } |
294 | error = sysfs_create_group(kobj: kernel_kobj, grp: &kernel_attr_group); |
295 | if (error) |
296 | goto kset_exit; |
297 | |
298 | if (notes_size > 0) { |
299 | notes_attr.size = notes_size; |
300 | error = sysfs_create_bin_file(kobj: kernel_kobj, attr: ¬es_attr); |
301 | if (error) |
302 | goto group_exit; |
303 | } |
304 | |
305 | return 0; |
306 | |
307 | group_exit: |
308 | sysfs_remove_group(kobj: kernel_kobj, grp: &kernel_attr_group); |
309 | kset_exit: |
310 | kobject_put(kobj: kernel_kobj); |
311 | exit: |
312 | return error; |
313 | } |
314 | |
315 | core_initcall(ksysfs_init); |
316 | |