xref: /openbmc/linux/kernel/ksysfs.c (revision 9b9c2cd4)
1 /*
2  * kernel/ksysfs.c - sysfs attributes in /sys/kernel, which
3  * 		     are not related to any other subsystem
4  *
5  * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
6  *
7  * This file is release under the GPLv2
8  *
9  */
10 
11 #include <linux/kobject.h>
12 #include <linux/string.h>
13 #include <linux/sysfs.h>
14 #include <linux/export.h>
15 #include <linux/init.h>
16 #include <linux/kexec.h>
17 #include <linux/profile.h>
18 #include <linux/stat.h>
19 #include <linux/sched.h>
20 #include <linux/capability.h>
21 #include <linux/compiler.h>
22 
23 #include <linux/rcupdate.h>	/* rcu_expedited */
24 
25 #define KERNEL_ATTR_RO(_name) \
26 static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
27 
28 #define KERNEL_ATTR_RW(_name) \
29 static struct kobj_attribute _name##_attr = \
30 	__ATTR(_name, 0644, _name##_show, _name##_store)
31 
32 /* current uevent sequence number */
33 static ssize_t uevent_seqnum_show(struct kobject *kobj,
34 				  struct kobj_attribute *attr, char *buf)
35 {
36 	return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum);
37 }
38 KERNEL_ATTR_RO(uevent_seqnum);
39 
40 #ifdef CONFIG_UEVENT_HELPER
41 /* uevent helper program, used during early boot */
42 static ssize_t uevent_helper_show(struct kobject *kobj,
43 				  struct kobj_attribute *attr, char *buf)
44 {
45 	return sprintf(buf, "%s\n", uevent_helper);
46 }
47 static ssize_t uevent_helper_store(struct kobject *kobj,
48 				   struct kobj_attribute *attr,
49 				   const char *buf, size_t count)
50 {
51 	if (count+1 > UEVENT_HELPER_PATH_LEN)
52 		return -ENOENT;
53 	memcpy(uevent_helper, buf, count);
54 	uevent_helper[count] = '\0';
55 	if (count && uevent_helper[count-1] == '\n')
56 		uevent_helper[count-1] = '\0';
57 	return count;
58 }
59 KERNEL_ATTR_RW(uevent_helper);
60 #endif
61 
62 #ifdef CONFIG_PROFILING
63 static ssize_t profiling_show(struct kobject *kobj,
64 				  struct kobj_attribute *attr, char *buf)
65 {
66 	return sprintf(buf, "%d\n", prof_on);
67 }
68 static ssize_t profiling_store(struct kobject *kobj,
69 				   struct kobj_attribute *attr,
70 				   const char *buf, size_t count)
71 {
72 	int ret;
73 
74 	if (prof_on)
75 		return -EEXIST;
76 	/*
77 	 * This eventually calls into get_option() which
78 	 * has a ton of callers and is not const.  It is
79 	 * easiest to cast it away here.
80 	 */
81 	profile_setup((char *)buf);
82 	ret = profile_init();
83 	if (ret)
84 		return ret;
85 	ret = create_proc_profile();
86 	if (ret)
87 		return ret;
88 	return count;
89 }
90 KERNEL_ATTR_RW(profiling);
91 #endif
92 
93 #ifdef CONFIG_KEXEC_CORE
94 static ssize_t kexec_loaded_show(struct kobject *kobj,
95 				 struct kobj_attribute *attr, char *buf)
96 {
97 	return sprintf(buf, "%d\n", !!kexec_image);
98 }
99 KERNEL_ATTR_RO(kexec_loaded);
100 
101 static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
102 				       struct kobj_attribute *attr, char *buf)
103 {
104 	return sprintf(buf, "%d\n", !!kexec_crash_image);
105 }
106 KERNEL_ATTR_RO(kexec_crash_loaded);
107 
108 static ssize_t kexec_crash_size_show(struct kobject *kobj,
109 				       struct kobj_attribute *attr, char *buf)
110 {
111 	return sprintf(buf, "%zu\n", crash_get_memory_size());
112 }
113 static ssize_t kexec_crash_size_store(struct kobject *kobj,
114 				   struct kobj_attribute *attr,
115 				   const char *buf, size_t count)
116 {
117 	unsigned long cnt;
118 	int ret;
119 
120 	if (kstrtoul(buf, 0, &cnt))
121 		return -EINVAL;
122 
123 	ret = crash_shrink_memory(cnt);
124 	return ret < 0 ? ret : count;
125 }
126 KERNEL_ATTR_RW(kexec_crash_size);
127 
128 static ssize_t vmcoreinfo_show(struct kobject *kobj,
129 			       struct kobj_attribute *attr, char *buf)
130 {
131 	return sprintf(buf, "%lx %x\n",
132 		       paddr_vmcoreinfo_note(),
133 		       (unsigned int)sizeof(vmcoreinfo_note));
134 }
135 KERNEL_ATTR_RO(vmcoreinfo);
136 
137 #endif /* CONFIG_KEXEC_CORE */
138 
139 /* whether file capabilities are enabled */
140 static ssize_t fscaps_show(struct kobject *kobj,
141 				  struct kobj_attribute *attr, char *buf)
142 {
143 	return sprintf(buf, "%d\n", file_caps_enabled);
144 }
145 KERNEL_ATTR_RO(fscaps);
146 
147 int rcu_expedited;
148 static ssize_t rcu_expedited_show(struct kobject *kobj,
149 				  struct kobj_attribute *attr, char *buf)
150 {
151 	return sprintf(buf, "%d\n", rcu_expedited);
152 }
153 static ssize_t rcu_expedited_store(struct kobject *kobj,
154 				   struct kobj_attribute *attr,
155 				   const char *buf, size_t count)
156 {
157 	if (kstrtoint(buf, 0, &rcu_expedited))
158 		return -EINVAL;
159 
160 	return count;
161 }
162 KERNEL_ATTR_RW(rcu_expedited);
163 
164 /*
165  * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
166  */
167 extern const void __start_notes __weak;
168 extern const void __stop_notes __weak;
169 #define	notes_size (&__stop_notes - &__start_notes)
170 
171 static ssize_t notes_read(struct file *filp, struct kobject *kobj,
172 			  struct bin_attribute *bin_attr,
173 			  char *buf, loff_t off, size_t count)
174 {
175 	memcpy(buf, &__start_notes + off, count);
176 	return count;
177 }
178 
179 static struct bin_attribute notes_attr = {
180 	.attr = {
181 		.name = "notes",
182 		.mode = S_IRUGO,
183 	},
184 	.read = &notes_read,
185 };
186 
187 struct kobject *kernel_kobj;
188 EXPORT_SYMBOL_GPL(kernel_kobj);
189 
190 static struct attribute * kernel_attrs[] = {
191 	&fscaps_attr.attr,
192 	&uevent_seqnum_attr.attr,
193 #ifdef CONFIG_UEVENT_HELPER
194 	&uevent_helper_attr.attr,
195 #endif
196 #ifdef CONFIG_PROFILING
197 	&profiling_attr.attr,
198 #endif
199 #ifdef CONFIG_KEXEC_CORE
200 	&kexec_loaded_attr.attr,
201 	&kexec_crash_loaded_attr.attr,
202 	&kexec_crash_size_attr.attr,
203 	&vmcoreinfo_attr.attr,
204 #endif
205 	&rcu_expedited_attr.attr,
206 	NULL
207 };
208 
209 static struct attribute_group kernel_attr_group = {
210 	.attrs = kernel_attrs,
211 };
212 
213 static int __init ksysfs_init(void)
214 {
215 	int error;
216 
217 	kernel_kobj = kobject_create_and_add("kernel", NULL);
218 	if (!kernel_kobj) {
219 		error = -ENOMEM;
220 		goto exit;
221 	}
222 	error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
223 	if (error)
224 		goto kset_exit;
225 
226 	if (notes_size > 0) {
227 		notes_attr.size = notes_size;
228 		error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
229 		if (error)
230 			goto group_exit;
231 	}
232 
233 	return 0;
234 
235 group_exit:
236 	sysfs_remove_group(kernel_kobj, &kernel_attr_group);
237 kset_exit:
238 	kobject_put(kernel_kobj);
239 exit:
240 	return error;
241 }
242 
243 core_initcall(ksysfs_init);
244