kernel/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 */
  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
  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 */
 138
 139 #if defined(CONFIG_PREEMPT_RT_FULL)
 140 static ssize_t  realtime_show(struct kobject *kobj,
 141                               struct kobj_attribute *attr, char *buf)
 142 {
 143         return sprintf(buf, "%d\n", 1);
 144 }
 145 KERNEL_ATTR_RO(realtime);
 146 #endif
 147
 148 /* whether file capabilities are enabled */
 149 static ssize_t fscaps_show(struct kobject *kobj,
 150                                   struct kobj_attribute *attr, char *buf)
 151 {
 152         return sprintf(buf, "%d\n", file_caps_enabled);
 153 }
 154 KERNEL_ATTR_RO(fscaps);
 155
 156 int rcu_expedited;
 157 static ssize_t rcu_expedited_show(struct kobject *kobj,
 158                                   struct kobj_attribute *attr, char *buf)
 159 {
 160         return sprintf(buf, "%d\n", rcu_expedited);
 161 }
 162 static ssize_t rcu_expedited_store(struct kobject *kobj,
 163                                    struct kobj_attribute *attr,
 164                                    const char *buf, size_t count)
 165 {
 166         if (kstrtoint(buf, 0, &rcu_expedited))
 167                 return -EINVAL;
 168
 169         return count;
 170 }
 171 KERNEL_ATTR_RW(rcu_expedited);
 172
 173 /*
 174  * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
 175  */
 176 extern const void __start_notes __weak;
 177 extern const void __stop_notes __weak;
 178 #define notes_size (&__stop_notes - &__start_notes)
 179
 180 static ssize_t notes_read(struct file *filp, struct kobject *kobj,
 181                           struct bin_attribute *bin_attr,
 182                           char *buf, loff_t off, size_t count)
 183 {
 184         memcpy(buf, &__start_notes + off, count);
 185         return count;
 186 }
 187
 188 static struct bin_attribute notes_attr = {
 189         .attr = {
 190                 .name = "notes",
 191                 .mode = S_IRUGO,
 192         },
 193         .read = &notes_read,
 194 };
 195
 196 struct kobject *kernel_kobj;
 197 EXPORT_SYMBOL_GPL(kernel_kobj);
 198
 199 static struct attribute * kernel_attrs[] = {
 200         &fscaps_attr.attr,
 201         &uevent_seqnum_attr.attr,
 202 #ifdef CONFIG_UEVENT_HELPER
 203         &uevent_helper_attr.attr,
 204 #endif
 205 #ifdef CONFIG_PROFILING
 206         &profiling_attr.attr,
 207 #endif
 208 #ifdef CONFIG_KEXEC
 209         &kexec_loaded_attr.attr,
 210         &kexec_crash_loaded_attr.attr,
 211         &kexec_crash_size_attr.attr,
 212         &vmcoreinfo_attr.attr,
 213 #endif
 214         &rcu_expedited_attr.attr,
 215 #ifdef CONFIG_PREEMPT_RT_FULL
 216         &realtime_attr.attr,
 217 #endif
 218         NULL
 219 };
 220
 221 static struct attribute_group kernel_attr_group = {
 222         .attrs = kernel_attrs,
 223 };
 224
 225 static int __init ksysfs_init(void)
 226 {
 227         int error;
 228
 229         kernel_kobj = kobject_create_and_add("kernel", NULL);
 230         if (!kernel_kobj) {
 231                 error = -ENOMEM;
 232                 goto exit;
 233         }
 234         error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
 235         if (error)
 236                 goto kset_exit;
 237
 238         if (notes_size > 0) {
 239                 notes_attr.size = notes_size;
 240                 error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
 241                 if (error)
 242                         goto group_exit;
 243         }
 244
 245         return 0;
 246
 247 group_exit:
 248         sysfs_remove_group(kernel_kobj, &kernel_attr_group);
 249 kset_exit:
 250         kobject_put(kernel_kobj);
 251 exit:
 252         return error;
 253 }
 254
 255 core_initcall(ksysfs_init);