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", (u64)atomic64_read(&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
123 #ifdef CONFIG_CRASH_DUMP
kexec_crash_loaded_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)124 static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
125 struct kobj_attribute *attr, char *buf)
126 {
127 return sysfs_emit(buf, "%d\n", kexec_crash_loaded());
128 }
129 KERNEL_ATTR_RO(kexec_crash_loaded);
130
kexec_crash_size_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)131 static ssize_t kexec_crash_size_show(struct kobject *kobj,
132 struct kobj_attribute *attr, char *buf)
133 {
134 ssize_t size = crash_get_memory_size();
135
136 if (size < 0)
137 return size;
138
139 return sysfs_emit(buf, "%zd\n", size);
140 }
kexec_crash_size_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)141 static ssize_t kexec_crash_size_store(struct kobject *kobj,
142 struct kobj_attribute *attr,
143 const char *buf, size_t count)
144 {
145 unsigned long cnt;
146 int ret;
147
148 if (kstrtoul(buf, 0, &cnt))
149 return -EINVAL;
150
151 ret = crash_shrink_memory(cnt);
152 return ret < 0 ? ret : count;
153 }
154 KERNEL_ATTR_RW(kexec_crash_size);
155
156 #endif /* CONFIG_CRASH_DUMP*/
157 #endif /* CONFIG_KEXEC_CORE */
158
159 #ifdef CONFIG_VMCORE_INFO
160
vmcoreinfo_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)161 static ssize_t vmcoreinfo_show(struct kobject *kobj,
162 struct kobj_attribute *attr, char *buf)
163 {
164 phys_addr_t vmcore_base = paddr_vmcoreinfo_note();
165 return sysfs_emit(buf, "%pa %x\n", &vmcore_base,
166 (unsigned int)VMCOREINFO_NOTE_SIZE);
167 }
168 KERNEL_ATTR_RO(vmcoreinfo);
169
170 #ifdef CONFIG_CRASH_HOTPLUG
crash_elfcorehdr_size_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)171 static ssize_t crash_elfcorehdr_size_show(struct kobject *kobj,
172 struct kobj_attribute *attr, char *buf)
173 {
174 unsigned int sz = crash_get_elfcorehdr_size();
175
176 return sysfs_emit(buf, "%u\n", sz);
177 }
178 KERNEL_ATTR_RO(crash_elfcorehdr_size);
179
180 #endif
181
182 #endif /* CONFIG_VMCORE_INFO */
183
184 /* whether file capabilities are enabled */
fscaps_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)185 static ssize_t fscaps_show(struct kobject *kobj,
186 struct kobj_attribute *attr, char *buf)
187 {
188 return sysfs_emit(buf, "%d\n", file_caps_enabled);
189 }
190 KERNEL_ATTR_RO(fscaps);
191
192 #ifndef CONFIG_TINY_RCU
193 int rcu_expedited;
rcu_expedited_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)194 static ssize_t rcu_expedited_show(struct kobject *kobj,
195 struct kobj_attribute *attr, char *buf)
196 {
197 return sysfs_emit(buf, "%d\n", READ_ONCE(rcu_expedited));
198 }
rcu_expedited_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)199 static ssize_t rcu_expedited_store(struct kobject *kobj,
200 struct kobj_attribute *attr,
201 const char *buf, size_t count)
202 {
203 if (kstrtoint(buf, 0, &rcu_expedited))
204 return -EINVAL;
205
206 return count;
207 }
208 KERNEL_ATTR_RW(rcu_expedited);
209
210 int rcu_normal;
rcu_normal_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)211 static ssize_t rcu_normal_show(struct kobject *kobj,
212 struct kobj_attribute *attr, char *buf)
213 {
214 return sysfs_emit(buf, "%d\n", READ_ONCE(rcu_normal));
215 }
rcu_normal_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)216 static ssize_t rcu_normal_store(struct kobject *kobj,
217 struct kobj_attribute *attr,
218 const char *buf, size_t count)
219 {
220 if (kstrtoint(buf, 0, &rcu_normal))
221 return -EINVAL;
222
223 return count;
224 }
225 KERNEL_ATTR_RW(rcu_normal);
226 #endif /* #ifndef CONFIG_TINY_RCU */
227
228 /*
229 * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
230 */
231 extern const void __start_notes __weak;
232 extern const void __stop_notes __weak;
233 #define notes_size (&__stop_notes - &__start_notes)
234
notes_read(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t count)235 static ssize_t notes_read(struct file *filp, struct kobject *kobj,
236 struct bin_attribute *bin_attr,
237 char *buf, loff_t off, size_t count)
238 {
239 memcpy(buf, &__start_notes + off, count);
240 return count;
241 }
242
243 static struct bin_attribute notes_attr __ro_after_init = {
244 .attr = {
245 .name = "notes",
246 .mode = S_IRUGO,
247 },
248 .read = ¬es_read,
249 };
250
251 struct kobject *kernel_kobj;
252 EXPORT_SYMBOL_GPL(kernel_kobj);
253
254 static struct attribute * kernel_attrs[] = {
255 &fscaps_attr.attr,
256 &uevent_seqnum_attr.attr,
257 &cpu_byteorder_attr.attr,
258 &address_bits_attr.attr,
259 #ifdef CONFIG_UEVENT_HELPER
260 &uevent_helper_attr.attr,
261 #endif
262 #ifdef CONFIG_PROFILING
263 &profiling_attr.attr,
264 #endif
265 #ifdef CONFIG_KEXEC_CORE
266 &kexec_loaded_attr.attr,
267 #ifdef CONFIG_CRASH_DUMP
268 &kexec_crash_loaded_attr.attr,
269 &kexec_crash_size_attr.attr,
270 #endif
271 #endif
272 #ifdef CONFIG_VMCORE_INFO
273 &vmcoreinfo_attr.attr,
274 #ifdef CONFIG_CRASH_HOTPLUG
275 &crash_elfcorehdr_size_attr.attr,
276 #endif
277 #endif
278 #ifndef CONFIG_TINY_RCU
279 &rcu_expedited_attr.attr,
280 &rcu_normal_attr.attr,
281 #endif
282 NULL
283 };
284
285 static const struct attribute_group kernel_attr_group = {
286 .attrs = kernel_attrs,
287 };
288
ksysfs_init(void)289 static int __init ksysfs_init(void)
290 {
291 int error;
292
293 kernel_kobj = kobject_create_and_add("kernel", NULL);
294 if (!kernel_kobj) {
295 error = -ENOMEM;
296 goto exit;
297 }
298 error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
299 if (error)
300 goto kset_exit;
301
302 if (notes_size > 0) {
303 notes_attr.size = notes_size;
304 error = sysfs_create_bin_file(kernel_kobj, ¬es_attr);
305 if (error)
306 goto group_exit;
307 }
308
309 return 0;
310
311 group_exit:
312 sysfs_remove_group(kernel_kobj, &kernel_attr_group);
313 kset_exit:
314 kobject_put(kernel_kobj);
315 exit:
316 return error;
317 }
318
319 core_initcall(ksysfs_init);
320