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 */
uevent_seqnum_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)30 static ssize_t uevent_seqnum_show(struct kobject *kobj,
31 				  struct kobj_attribute *attr, char *buf)
32 {
33 	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 */
uevent_helper_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)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 }
uevent_helper_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)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
profiling_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)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 }
profiling_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)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
kexec_loaded_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)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 
kexec_crash_loaded_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)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 
kexec_crash_size_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)105 static ssize_t kexec_crash_size_show(struct kobject *kobj,
106 				       struct kobj_attribute *attr, char *buf)
107 {
108 	ssize_t size = crash_get_memory_size();
109 
110 	if (size < 0)
111 		return size;
112 
113 	return sprintf(buf, "%zd\n", size);
114 }
kexec_crash_size_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)115 static ssize_t kexec_crash_size_store(struct kobject *kobj,
116 				   struct kobj_attribute *attr,
117 				   const char *buf, size_t count)
118 {
119 	unsigned long cnt;
120 	int ret;
121 
122 	if (kstrtoul(buf, 0, &cnt))
123 		return -EINVAL;
124 
125 	ret = crash_shrink_memory(cnt);
126 	return ret < 0 ? ret : count;
127 }
128 KERNEL_ATTR_RW(kexec_crash_size);
129 
130 #endif /* CONFIG_KEXEC_CORE */
131 
132 #ifdef CONFIG_CRASH_CORE
133 
vmcoreinfo_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)134 static ssize_t vmcoreinfo_show(struct kobject *kobj,
135 			       struct kobj_attribute *attr, char *buf)
136 {
137 	phys_addr_t vmcore_base = paddr_vmcoreinfo_note();
138 	return sprintf(buf, "%pa %x\n", &vmcore_base,
139 			(unsigned int)VMCOREINFO_NOTE_SIZE);
140 }
141 KERNEL_ATTR_RO(vmcoreinfo);
142 
143 #endif /* CONFIG_CRASH_CORE */
144 
145 /* whether file capabilities are enabled */
fscaps_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)146 static ssize_t fscaps_show(struct kobject *kobj,
147 				  struct kobj_attribute *attr, char *buf)
148 {
149 	return sprintf(buf, "%d\n", file_caps_enabled);
150 }
151 KERNEL_ATTR_RO(fscaps);
152 
153 #ifndef CONFIG_TINY_RCU
154 int rcu_expedited;
rcu_expedited_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)155 static ssize_t rcu_expedited_show(struct kobject *kobj,
156 				  struct kobj_attribute *attr, char *buf)
157 {
158 	return sprintf(buf, "%d\n", READ_ONCE(rcu_expedited));
159 }
rcu_expedited_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)160 static ssize_t rcu_expedited_store(struct kobject *kobj,
161 				   struct kobj_attribute *attr,
162 				   const char *buf, size_t count)
163 {
164 	if (kstrtoint(buf, 0, &rcu_expedited))
165 		return -EINVAL;
166 
167 	return count;
168 }
169 KERNEL_ATTR_RW(rcu_expedited);
170 
171 int rcu_normal;
rcu_normal_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)172 static ssize_t rcu_normal_show(struct kobject *kobj,
173 			       struct kobj_attribute *attr, char *buf)
174 {
175 	return sprintf(buf, "%d\n", READ_ONCE(rcu_normal));
176 }
rcu_normal_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)177 static ssize_t rcu_normal_store(struct kobject *kobj,
178 				struct kobj_attribute *attr,
179 				const char *buf, size_t count)
180 {
181 	if (kstrtoint(buf, 0, &rcu_normal))
182 		return -EINVAL;
183 
184 	return count;
185 }
186 KERNEL_ATTR_RW(rcu_normal);
187 #endif /* #ifndef CONFIG_TINY_RCU */
188 
189 /*
190  * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
191  */
192 extern const void __start_notes __weak;
193 extern const void __stop_notes __weak;
194 #define	notes_size (&__stop_notes - &__start_notes)
195 
notes_read(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t count)196 static ssize_t notes_read(struct file *filp, struct kobject *kobj,
197 			  struct bin_attribute *bin_attr,
198 			  char *buf, loff_t off, size_t count)
199 {
200 	memcpy(buf, &__start_notes + off, count);
201 	return count;
202 }
203 
204 static struct bin_attribute notes_attr __ro_after_init  = {
205 	.attr = {
206 		.name = "notes",
207 		.mode = S_IRUGO,
208 	},
209 	.read = &notes_read,
210 };
211 
212 struct kobject *kernel_kobj;
213 EXPORT_SYMBOL_GPL(kernel_kobj);
214 
215 static struct attribute * kernel_attrs[] = {
216 	&fscaps_attr.attr,
217 	&uevent_seqnum_attr.attr,
218 #ifdef CONFIG_UEVENT_HELPER
219 	&uevent_helper_attr.attr,
220 #endif
221 #ifdef CONFIG_PROFILING
222 	&profiling_attr.attr,
223 #endif
224 #ifdef CONFIG_KEXEC_CORE
225 	&kexec_loaded_attr.attr,
226 	&kexec_crash_loaded_attr.attr,
227 	&kexec_crash_size_attr.attr,
228 #endif
229 #ifdef CONFIG_CRASH_CORE
230 	&vmcoreinfo_attr.attr,
231 #endif
232 #ifndef CONFIG_TINY_RCU
233 	&rcu_expedited_attr.attr,
234 	&rcu_normal_attr.attr,
235 #endif
236 	NULL
237 };
238 
239 static const struct attribute_group kernel_attr_group = {
240 	.attrs = kernel_attrs,
241 };
242 
ksysfs_init(void)243 static int __init ksysfs_init(void)
244 {
245 	int error;
246 
247 	kernel_kobj = kobject_create_and_add("kernel", NULL);
248 	if (!kernel_kobj) {
249 		error = -ENOMEM;
250 		goto exit;
251 	}
252 	error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
253 	if (error)
254 		goto kset_exit;
255 
256 	if (notes_size > 0) {
257 		notes_attr.size = notes_size;
258 		error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
259 		if (error)
260 			goto group_exit;
261 	}
262 
263 	return 0;
264 
265 group_exit:
266 	sysfs_remove_group(kernel_kobj, &kernel_attr_group);
267 kset_exit:
268 	kobject_put(kernel_kobj);
269 exit:
270 	return error;
271 }
272 
273 core_initcall(ksysfs_init);
274