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Linux/kernel/ksysfs.c

  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 and rcu_normal */
 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_loaded());
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         phys_addr_t vmcore_base = paddr_vmcoreinfo_note();
132         return sprintf(buf, "%pa %x\n", &vmcore_base,
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 #ifndef CONFIG_TINY_RCU
148 int rcu_expedited;
149 static ssize_t rcu_expedited_show(struct kobject *kobj,
150                                   struct kobj_attribute *attr, char *buf)
151 {
152         return sprintf(buf, "%d\n", READ_ONCE(rcu_expedited));
153 }
154 static ssize_t rcu_expedited_store(struct kobject *kobj,
155                                    struct kobj_attribute *attr,
156                                    const char *buf, size_t count)
157 {
158         if (kstrtoint(buf, 0, &rcu_expedited))
159                 return -EINVAL;
160 
161         return count;
162 }
163 KERNEL_ATTR_RW(rcu_expedited);
164 
165 int rcu_normal;
166 static ssize_t rcu_normal_show(struct kobject *kobj,
167                                struct kobj_attribute *attr, char *buf)
168 {
169         return sprintf(buf, "%d\n", READ_ONCE(rcu_normal));
170 }
171 static ssize_t rcu_normal_store(struct kobject *kobj,
172                                 struct kobj_attribute *attr,
173                                 const char *buf, size_t count)
174 {
175         if (kstrtoint(buf, 0, &rcu_normal))
176                 return -EINVAL;
177 
178         return count;
179 }
180 KERNEL_ATTR_RW(rcu_normal);
181 #endif /* #ifndef CONFIG_TINY_RCU */
182 
183 /*
184  * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
185  */
186 extern const void __start_notes __weak;
187 extern const void __stop_notes __weak;
188 #define notes_size (&__stop_notes - &__start_notes)
189 
190 static ssize_t notes_read(struct file *filp, struct kobject *kobj,
191                           struct bin_attribute *bin_attr,
192                           char *buf, loff_t off, size_t count)
193 {
194         memcpy(buf, &__start_notes + off, count);
195         return count;
196 }
197 
198 static struct bin_attribute notes_attr = {
199         .attr = {
200                 .name = "notes",
201                 .mode = S_IRUGO,
202         },
203         .read = &notes_read,
204 };
205 
206 struct kobject *kernel_kobj;
207 EXPORT_SYMBOL_GPL(kernel_kobj);
208 
209 static struct attribute * kernel_attrs[] = {
210         &fscaps_attr.attr,
211         &uevent_seqnum_attr.attr,
212 #ifdef CONFIG_UEVENT_HELPER
213         &uevent_helper_attr.attr,
214 #endif
215 #ifdef CONFIG_PROFILING
216         &profiling_attr.attr,
217 #endif
218 #ifdef CONFIG_KEXEC_CORE
219         &kexec_loaded_attr.attr,
220         &kexec_crash_loaded_attr.attr,
221         &kexec_crash_size_attr.attr,
222         &vmcoreinfo_attr.attr,
223 #endif
224 #ifndef CONFIG_TINY_RCU
225         &rcu_expedited_attr.attr,
226         &rcu_normal_attr.attr,
227 #endif
228         NULL
229 };
230 
231 static struct attribute_group kernel_attr_group = {
232         .attrs = kernel_attrs,
233 };
234 
235 static int __init ksysfs_init(void)
236 {
237         int error;
238 
239         kernel_kobj = kobject_create_and_add("kernel", NULL);
240         if (!kernel_kobj) {
241                 error = -ENOMEM;
242                 goto exit;
243         }
244         error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
245         if (error)
246                 goto kset_exit;
247 
248         if (notes_size > 0) {
249                 notes_attr.size = notes_size;
250                 error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
251                 if (error)
252                         goto group_exit;
253         }
254 
255         return 0;
256 
257 group_exit:
258         sysfs_remove_group(kernel_kobj, &kernel_attr_group);
259 kset_exit:
260         kobject_put(kernel_kobj);
261 exit:
262         return error;
263 }
264 
265 core_initcall(ksysfs_init);
266 

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