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 */
uevent_seqnum_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)39 static ssize_t uevent_seqnum_show(struct kobject *kobj,
40 struct kobj_attribute *attr, char *buf)
41 {
42 return sysfs_emit(buf, "%llu\n", (unsigned long long)uevent_seqnum);
43 }
44 KERNEL_ATTR_RO(uevent_seqnum);
45
46 /* cpu byteorder */
cpu_byteorder_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)47 static ssize_t cpu_byteorder_show(struct kobject *kobj,
48 struct kobj_attribute *attr, char *buf)
49 {
50 return sysfs_emit(buf, "%s\n", CPU_BYTEORDER_STRING);
51 }
52 KERNEL_ATTR_RO(cpu_byteorder);
53
54 /* address bits */
address_bits_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)55 static ssize_t address_bits_show(struct kobject *kobj,
56 struct kobj_attribute *attr, char *buf)
57 {
58 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 */
uevent_helper_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)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 }
uevent_helper_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)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
profiling_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)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 }
profiling_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)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
kexec_loaded_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)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
kexec_crash_loaded_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)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
kexec_crash_size_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)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 }
kexec_crash_size_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)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
vmcoreinfo_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)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 #ifdef CONFIG_CRASH_HOTPLUG
crash_elfcorehdr_size_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)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, "%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 */
fscaps_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)183 static ssize_t fscaps_show(struct kobject *kobj,
184 struct kobj_attribute *attr, char *buf)
185 {
186 return sysfs_emit(buf, "%d\n", file_caps_enabled);
187 }
188 KERNEL_ATTR_RO(fscaps);
189
190 #ifndef CONFIG_TINY_RCU
191 int rcu_expedited;
rcu_expedited_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)192 static ssize_t rcu_expedited_show(struct kobject *kobj,
193 struct kobj_attribute *attr, char *buf)
194 {
195 return sysfs_emit(buf, "%d\n", READ_ONCE(rcu_expedited));
196 }
rcu_expedited_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)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(buf, 0, &rcu_expedited))
202 return -EINVAL;
203
204 return count;
205 }
206 KERNEL_ATTR_RW(rcu_expedited);
207
208 int rcu_normal;
rcu_normal_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)209 static ssize_t rcu_normal_show(struct kobject *kobj,
210 struct kobj_attribute *attr, char *buf)
211 {
212 return sysfs_emit(buf, "%d\n", READ_ONCE(rcu_normal));
213 }
rcu_normal_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)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(buf, 0, &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
notes_read(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t count)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
ksysfs_init(void)285 static int __init ksysfs_init(void)
286 {
287 int error;
288
289 kernel_kobj = kobject_create_and_add("kernel", NULL);
290 if (!kernel_kobj) {
291 error = -ENOMEM;
292 goto exit;
293 }
294 error = sysfs_create_group(kernel_kobj, &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(kernel_kobj, ¬es_attr);
301 if (error)
302 goto group_exit;
303 }
304
305 return 0;
306
307 group_exit:
308 sysfs_remove_group(kernel_kobj, &kernel_attr_group);
309 kset_exit:
310 kobject_put(kernel_kobj);
311 exit:
312 return error;
313 }
314
315 core_initcall(ksysfs_init);
316