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 /* uevent helper program, used during early boot */
  41 static ssize_t uevent_helper_show(struct kobject *kobj,
  42                                   struct kobj_attribute *attr, char *buf)
  43 {
  44         return sprintf(buf, "%s\n", uevent_helper);
  45 }
  46 static ssize_t uevent_helper_store(struct kobject *kobj,
  47                                    struct kobj_attribute *attr,
  48                                    const char *buf, size_t count)
  49 {
  50         if (count+1 > UEVENT_HELPER_PATH_LEN)
  51                 return -ENOENT;
  52         memcpy(uevent_helper, buf, count);
  53         uevent_helper[count] = '\0';
  54         if (count && uevent_helper[count-1] == '\n')
  55                 uevent_helper[count-1] = '\0';
  56         return count;
  57 }
  58 KERNEL_ATTR_RW(uevent_helper);
  59
  60
  61 #ifdef CONFIG_PROFILING
  62 static ssize_t profiling_show(struct kobject *kobj,
  63                                   struct kobj_attribute *attr, char *buf)
  64 {
  65         return sprintf(buf, "%d\n", prof_on);
  66 }
  67 static ssize_t profiling_store(struct kobject *kobj,
  68                                    struct kobj_attribute *attr,
  69                                    const char *buf, size_t count)
  70 {
  71         int ret;
  72
  73         if (prof_on)
  74                 return -EEXIST;
  75         /*
  76          * This eventually calls into get_option() which
  77          * has a ton of callers and is not const.  It is
  78          * easiest to cast it away here.
  79          */
  80         profile_setup((char *)buf);
  81         ret = profile_init();
  82         if (ret)
  83                 return ret;
  84         ret = create_proc_profile();
  85         if (ret)
  86                 return ret;
  87         return count;
  88 }
  89 KERNEL_ATTR_RW(profiling);
  90 #endif
  91
  92 #ifdef CONFIG_KEXEC
  93 static ssize_t kexec_loaded_show(struct kobject *kobj,
  94                                  struct kobj_attribute *attr, char *buf)
  95 {
  96         return sprintf(buf, "%d\n", !!kexec_image);
  97 }
  98 KERNEL_ATTR_RO(kexec_loaded);
  99
 100 static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
 101                                        struct kobj_attribute *attr, char *buf)
 102 {
 103         return sprintf(buf, "%d\n", !!kexec_crash_image);
 104 }
 105 KERNEL_ATTR_RO(kexec_crash_loaded);
 106
 107 static ssize_t kexec_crash_size_show(struct kobject *kobj,
 108                                        struct kobj_attribute *attr, char *buf)
 109 {
 110         return sprintf(buf, "%zu\n", crash_get_memory_size());
 111 }
 112 static ssize_t kexec_crash_size_store(struct kobject *kobj,
 113                                    struct kobj_attribute *attr,
 114                                    const char *buf, size_t count)
 115 {
 116         unsigned long cnt;
 117         int ret;
 118
 119         if (kstrtoul(buf, 0, &cnt))
 120                 return -EINVAL;
 121
 122         ret = crash_shrink_memory(cnt);
 123         return ret < 0 ? ret : count;
 124 }
 125 KERNEL_ATTR_RW(kexec_crash_size);
 126
 127 static ssize_t vmcoreinfo_show(struct kobject *kobj,
 128                                struct kobj_attribute *attr, char *buf)
 129 {
 130         return sprintf(buf, "%lx %x\n",
 131                        paddr_vmcoreinfo_note(),
 132                        (unsigned int)sizeof(vmcoreinfo_note));
 133 }
 134 KERNEL_ATTR_RO(vmcoreinfo);
 135
 136 #endif /* CONFIG_KEXEC */
 137
 138 /* whether file capabilities are enabled */
 139 static ssize_t fscaps_show(struct kobject *kobj,
 140                                   struct kobj_attribute *attr, char *buf)
 141 {
 142         return sprintf(buf, "%d\n", file_caps_enabled);
 143 }
 144 KERNEL_ATTR_RO(fscaps);
 145
 146 int rcu_expedited;
 147 static ssize_t rcu_expedited_show(struct kobject *kobj,
 148                                   struct kobj_attribute *attr, char *buf)
 149 {
 150         return sprintf(buf, "%d\n", rcu_expedited);
 151 }
 152 static ssize_t rcu_expedited_store(struct kobject *kobj,
 153                                    struct kobj_attribute *attr,
 154                                    const char *buf, size_t count)
 155 {
 156         if (kstrtoint(buf, 0, &rcu_expedited))
 157                 return -EINVAL;
 158
 159         return count;
 160 }
 161 KERNEL_ATTR_RW(rcu_expedited);
 162
 163 /*
 164  * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
 165  */
 166 extern const void __start_notes __weak;
 167 extern const void __stop_notes __weak;
 168 #define notes_size (&__stop_notes - &__start_notes)
 169
 170 static ssize_t notes_read(struct file *filp, struct kobject *kobj,
 171                           struct bin_attribute *bin_attr,
 172                           char *buf, loff_t off, size_t count)
 173 {
 174         memcpy(buf, &__start_notes + off, count);
 175         return count;
 176 }
 177
 178 static struct bin_attribute notes_attr = {
 179         .attr = {
 180                 .name = "notes",
 181                 .mode = S_IRUGO,
 182         },
 183         .read = &notes_read,
 184 };
 185
 186 struct kobject *kernel_kobj;
 187 EXPORT_SYMBOL_GPL(kernel_kobj);
 188
 189 static struct attribute * kernel_attrs[] = {
 190         &fscaps_attr.attr,
 191         &uevent_seqnum_attr.attr,
 192         &uevent_helper_attr.attr,
 193 #ifdef CONFIG_PROFILING
 194         &profiling_attr.attr,
 195 #endif
 196 #ifdef CONFIG_KEXEC
 197         &kexec_loaded_attr.attr,
 198         &kexec_crash_loaded_attr.attr,
 199         &kexec_crash_size_attr.attr,
 200         &vmcoreinfo_attr.attr,
 201 #endif
 202         &rcu_expedited_attr.attr,
 203         NULL
 204 };
 205
 206 static struct attribute_group kernel_attr_group = {
 207         .attrs = kernel_attrs,
 208 };
 209
 210 static int __init ksysfs_init(void)
 211 {
 212         int error;
 213
 214         kernel_kobj = kobject_create_and_add("kernel", NULL);
 215         if (!kernel_kobj) {
 216                 error = -ENOMEM;
 217                 goto exit;
 218         }
 219         error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
 220         if (error)
 221                 goto kset_exit;
 222
 223         if (notes_size > 0) {
 224                 notes_attr.size = notes_size;
 225                 error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
 226                 if (error)
 227                         goto group_exit;
 228         }
 229
 230         return 0;
 231
 232 group_exit:
 233         sysfs_remove_group(kernel_kobj, &kernel_attr_group);
 234 kset_exit:
 235         kobject_put(kernel_kobj);
 236 exit:
 237         return error;
 238 }
 239
 240 core_initcall(ksysfs_init);