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 <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 = __ATTR_RW(_name)
28 :
29 : /* current uevent sequence number */
30 0 : static ssize_t uevent_seqnum_show(struct kobject *kobj,
31 : struct kobj_attribute *attr, char *buf)
32 : {
33 0 : return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum);
34 : }
35 : KERNEL_ATTR_RO(uevent_seqnum);
36 :
37 : #ifdef CONFIG_UEVENT_HELPER
38 : /* uevent helper program, used during early boot */
39 : static ssize_t uevent_helper_show(struct kobject *kobj,
40 : struct kobj_attribute *attr, char *buf)
41 : {
42 : return sprintf(buf, "%s\n", uevent_helper);
43 : }
44 : static ssize_t uevent_helper_store(struct kobject *kobj,
45 : struct kobj_attribute *attr,
46 : const char *buf, size_t count)
47 : {
48 : if (count+1 > UEVENT_HELPER_PATH_LEN)
49 : return -ENOENT;
50 : memcpy(uevent_helper, buf, count);
51 : uevent_helper[count] = '\0';
52 : if (count && uevent_helper[count-1] == '\n')
53 : uevent_helper[count-1] = '\0';
54 : return count;
55 : }
56 : KERNEL_ATTR_RW(uevent_helper);
57 : #endif
58 :
59 : #ifdef CONFIG_PROFILING
60 : static ssize_t profiling_show(struct kobject *kobj,
61 : struct kobj_attribute *attr, char *buf)
62 : {
63 : return sprintf(buf, "%d\n", prof_on);
64 : }
65 : static ssize_t profiling_store(struct kobject *kobj,
66 : struct kobj_attribute *attr,
67 : const char *buf, size_t count)
68 : {
69 : int ret;
70 :
71 : if (prof_on)
72 : return -EEXIST;
73 : /*
74 : * This eventually calls into get_option() which
75 : * has a ton of callers and is not const. It is
76 : * easiest to cast it away here.
77 : */
78 : profile_setup((char *)buf);
79 : ret = profile_init();
80 : if (ret)
81 : return ret;
82 : ret = create_proc_profile();
83 : if (ret)
84 : return ret;
85 : return count;
86 : }
87 : KERNEL_ATTR_RW(profiling);
88 : #endif
89 :
90 : #ifdef CONFIG_KEXEC_CORE
91 : static ssize_t kexec_loaded_show(struct kobject *kobj,
92 : struct kobj_attribute *attr, char *buf)
93 : {
94 : return sprintf(buf, "%d\n", !!kexec_image);
95 : }
96 : KERNEL_ATTR_RO(kexec_loaded);
97 :
98 : static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
99 : struct kobj_attribute *attr, char *buf)
100 : {
101 : return sprintf(buf, "%d\n", kexec_crash_loaded());
102 : }
103 : KERNEL_ATTR_RO(kexec_crash_loaded);
104 :
105 : static ssize_t kexec_crash_size_show(struct kobject *kobj,
106 : struct kobj_attribute *attr, char *buf)
107 : {
108 : return sprintf(buf, "%zu\n", crash_get_memory_size());
109 : }
110 : static ssize_t kexec_crash_size_store(struct kobject *kobj,
111 : struct kobj_attribute *attr,
112 : const char *buf, size_t count)
113 : {
114 : unsigned long cnt;
115 : int ret;
116 :
117 : if (kstrtoul(buf, 0, &cnt))
118 : return -EINVAL;
119 :
120 : ret = crash_shrink_memory(cnt);
121 : return ret < 0 ? ret : count;
122 : }
123 : KERNEL_ATTR_RW(kexec_crash_size);
124 :
125 : #endif /* CONFIG_KEXEC_CORE */
126 :
127 : #ifdef CONFIG_CRASH_CORE
128 :
129 : static ssize_t vmcoreinfo_show(struct kobject *kobj,
130 : struct kobj_attribute *attr, char *buf)
131 : {
132 : phys_addr_t vmcore_base = paddr_vmcoreinfo_note();
133 : return sprintf(buf, "%pa %x\n", &vmcore_base,
134 : (unsigned int)VMCOREINFO_NOTE_SIZE);
135 : }
136 : KERNEL_ATTR_RO(vmcoreinfo);
137 :
138 : #endif /* CONFIG_CRASH_CORE */
139 :
140 : /* whether file capabilities are enabled */
141 0 : static ssize_t fscaps_show(struct kobject *kobj,
142 : struct kobj_attribute *attr, char *buf)
143 : {
144 0 : return sprintf(buf, "%d\n", file_caps_enabled);
145 : }
146 : KERNEL_ATTR_RO(fscaps);
147 :
148 : #ifndef CONFIG_TINY_RCU
149 : int rcu_expedited;
150 : static ssize_t rcu_expedited_show(struct kobject *kobj,
151 : struct kobj_attribute *attr, char *buf)
152 : {
153 : return sprintf(buf, "%d\n", READ_ONCE(rcu_expedited));
154 : }
155 : static ssize_t rcu_expedited_store(struct kobject *kobj,
156 : struct kobj_attribute *attr,
157 : const char *buf, size_t count)
158 : {
159 : if (kstrtoint(buf, 0, &rcu_expedited))
160 : return -EINVAL;
161 :
162 : return count;
163 : }
164 : KERNEL_ATTR_RW(rcu_expedited);
165 :
166 : int rcu_normal;
167 : static ssize_t rcu_normal_show(struct kobject *kobj,
168 : struct kobj_attribute *attr, char *buf)
169 : {
170 : return sprintf(buf, "%d\n", READ_ONCE(rcu_normal));
171 : }
172 : static ssize_t rcu_normal_store(struct kobject *kobj,
173 : struct kobj_attribute *attr,
174 : const char *buf, size_t count)
175 : {
176 : if (kstrtoint(buf, 0, &rcu_normal))
177 : return -EINVAL;
178 :
179 : return count;
180 : }
181 : KERNEL_ATTR_RW(rcu_normal);
182 : #endif /* #ifndef CONFIG_TINY_RCU */
183 :
184 : /*
185 : * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
186 : */
187 : extern const void __start_notes __weak;
188 : extern const void __stop_notes __weak;
189 : #define notes_size (&__stop_notes - &__start_notes)
190 :
191 0 : static ssize_t notes_read(struct file *filp, struct kobject *kobj,
192 : struct bin_attribute *bin_attr,
193 : char *buf, loff_t off, size_t count)
194 : {
195 0 : memcpy(buf, &__start_notes + off, count);
196 0 : return count;
197 : }
198 :
199 : static struct bin_attribute notes_attr __ro_after_init = {
200 : .attr = {
201 : .name = "notes",
202 : .mode = S_IRUGO,
203 : },
204 : .read = ¬es_read,
205 : };
206 :
207 : struct kobject *kernel_kobj;
208 : EXPORT_SYMBOL_GPL(kernel_kobj);
209 :
210 : static struct attribute * kernel_attrs[] = {
211 : &fscaps_attr.attr,
212 : &uevent_seqnum_attr.attr,
213 : #ifdef CONFIG_UEVENT_HELPER
214 : &uevent_helper_attr.attr,
215 : #endif
216 : #ifdef CONFIG_PROFILING
217 : &profiling_attr.attr,
218 : #endif
219 : #ifdef CONFIG_KEXEC_CORE
220 : &kexec_loaded_attr.attr,
221 : &kexec_crash_loaded_attr.attr,
222 : &kexec_crash_size_attr.attr,
223 : #endif
224 : #ifdef CONFIG_CRASH_CORE
225 : &vmcoreinfo_attr.attr,
226 : #endif
227 : #ifndef CONFIG_TINY_RCU
228 : &rcu_expedited_attr.attr,
229 : &rcu_normal_attr.attr,
230 : #endif
231 : NULL
232 : };
233 :
234 : static const struct attribute_group kernel_attr_group = {
235 : .attrs = kernel_attrs,
236 : };
237 :
238 1 : static int __init ksysfs_init(void)
239 : {
240 : int error;
241 :
242 1 : kernel_kobj = kobject_create_and_add("kernel", NULL);
243 1 : if (!kernel_kobj) {
244 : error = -ENOMEM;
245 : goto exit;
246 : }
247 1 : error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
248 1 : if (error)
249 : goto kset_exit;
250 :
251 1 : if (notes_size > 0) {
252 1 : notes_attr.size = notes_size;
253 1 : error = sysfs_create_bin_file(kernel_kobj, ¬es_attr);
254 1 : if (error)
255 : goto group_exit;
256 : }
257 :
258 : return 0;
259 :
260 : group_exit:
261 0 : sysfs_remove_group(kernel_kobj, &kernel_attr_group);
262 : kset_exit:
263 0 : kobject_put(kernel_kobj);
264 : exit:
265 : return error;
266 : }
267 :
268 : core_initcall(ksysfs_init);
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