Line data Source code
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 0 : static ssize_t uevent_seqnum_show(struct kobject *kobj,
40 : struct kobj_attribute *attr, char *buf)
41 : {
42 0 : return sysfs_emit(buf, "%llu\n", (unsigned long long)uevent_seqnum);
43 : }
44 : KERNEL_ATTR_RO(uevent_seqnum);
45 :
46 : /* cpu byteorder */
47 0 : static ssize_t cpu_byteorder_show(struct kobject *kobj,
48 : struct kobj_attribute *attr, char *buf)
49 : {
50 0 : return sysfs_emit(buf, "%s\n", CPU_BYTEORDER_STRING);
51 : }
52 : KERNEL_ATTR_RO(cpu_byteorder);
53 :
54 : /* address bits */
55 0 : static ssize_t address_bits_show(struct kobject *kobj,
56 : struct kobj_attribute *attr, char *buf)
57 : {
58 0 : return sysfs_emit(buf, "%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, "%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, "%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((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, "%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, "%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, "%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(buf, 0, &cnt))
148 : return -EINVAL;
149 :
150 : ret = crash_shrink_memory(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, "%pa %x\n", &vmcore_base,
164 : (unsigned int)VMCOREINFO_NOTE_SIZE);
165 : }
166 : KERNEL_ATTR_RO(vmcoreinfo);
167 :
168 : #endif /* CONFIG_CRASH_CORE */
169 :
170 : /* whether file capabilities are enabled */
171 0 : static ssize_t fscaps_show(struct kobject *kobj,
172 : struct kobj_attribute *attr, char *buf)
173 : {
174 0 : return sysfs_emit(buf, "%d\n", file_caps_enabled);
175 : }
176 : KERNEL_ATTR_RO(fscaps);
177 :
178 : #ifndef CONFIG_TINY_RCU
179 : int rcu_expedited;
180 : static ssize_t rcu_expedited_show(struct kobject *kobj,
181 : struct kobj_attribute *attr, char *buf)
182 : {
183 : return sysfs_emit(buf, "%d\n", READ_ONCE(rcu_expedited));
184 : }
185 : static ssize_t rcu_expedited_store(struct kobject *kobj,
186 : struct kobj_attribute *attr,
187 : const char *buf, size_t count)
188 : {
189 : if (kstrtoint(buf, 0, &rcu_expedited))
190 : return -EINVAL;
191 :
192 : return count;
193 : }
194 : KERNEL_ATTR_RW(rcu_expedited);
195 :
196 : int rcu_normal;
197 : static ssize_t rcu_normal_show(struct kobject *kobj,
198 : struct kobj_attribute *attr, char *buf)
199 : {
200 : return sysfs_emit(buf, "%d\n", READ_ONCE(rcu_normal));
201 : }
202 : static ssize_t rcu_normal_store(struct kobject *kobj,
203 : struct kobj_attribute *attr,
204 : const char *buf, size_t count)
205 : {
206 : if (kstrtoint(buf, 0, &rcu_normal))
207 : return -EINVAL;
208 :
209 : return count;
210 : }
211 : KERNEL_ATTR_RW(rcu_normal);
212 : #endif /* #ifndef CONFIG_TINY_RCU */
213 :
214 : /*
215 : * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
216 : */
217 : extern const void __start_notes __weak;
218 : extern const void __stop_notes __weak;
219 : #define notes_size (&__stop_notes - &__start_notes)
220 :
221 0 : static ssize_t notes_read(struct file *filp, struct kobject *kobj,
222 : struct bin_attribute *bin_attr,
223 : char *buf, loff_t off, size_t count)
224 : {
225 0 : memcpy(buf, &__start_notes + off, count);
226 0 : return count;
227 : }
228 :
229 : static struct bin_attribute notes_attr __ro_after_init = {
230 : .attr = {
231 : .name = "notes",
232 : .mode = S_IRUGO,
233 : },
234 : .read = ¬es_read,
235 : };
236 :
237 : struct kobject *kernel_kobj;
238 : EXPORT_SYMBOL_GPL(kernel_kobj);
239 :
240 : static struct attribute * kernel_attrs[] = {
241 : &fscaps_attr.attr,
242 : &uevent_seqnum_attr.attr,
243 : &cpu_byteorder_attr.attr,
244 : &address_bits_attr.attr,
245 : #ifdef CONFIG_UEVENT_HELPER
246 : &uevent_helper_attr.attr,
247 : #endif
248 : #ifdef CONFIG_PROFILING
249 : &profiling_attr.attr,
250 : #endif
251 : #ifdef CONFIG_KEXEC_CORE
252 : &kexec_loaded_attr.attr,
253 : &kexec_crash_loaded_attr.attr,
254 : &kexec_crash_size_attr.attr,
255 : #endif
256 : #ifdef CONFIG_CRASH_CORE
257 : &vmcoreinfo_attr.attr,
258 : #endif
259 : #ifndef CONFIG_TINY_RCU
260 : &rcu_expedited_attr.attr,
261 : &rcu_normal_attr.attr,
262 : #endif
263 : NULL
264 : };
265 :
266 : static const struct attribute_group kernel_attr_group = {
267 : .attrs = kernel_attrs,
268 : };
269 :
270 1 : static int __init ksysfs_init(void)
271 : {
272 : int error;
273 :
274 1 : kernel_kobj = kobject_create_and_add("kernel", NULL);
275 1 : if (!kernel_kobj) {
276 : error = -ENOMEM;
277 : goto exit;
278 : }
279 1 : error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
280 1 : if (error)
281 : goto kset_exit;
282 :
283 1 : if (notes_size > 0) {
284 1 : notes_attr.size = notes_size;
285 1 : error = sysfs_create_bin_file(kernel_kobj, ¬es_attr);
286 1 : if (error)
287 : goto group_exit;
288 : }
289 :
290 : return 0;
291 :
292 : group_exit:
293 0 : sysfs_remove_group(kernel_kobj, &kernel_attr_group);
294 : kset_exit:
295 0 : kobject_put(kernel_kobj);
296 : exit:
297 : return error;
298 : }
299 :
300 : core_initcall(ksysfs_init);
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