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_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 #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);