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
  22 #define KERNEL_ATTR_RO(_name) \
  23 static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
  24
  25 #define KERNEL_ATTR_RW(_name) \
  26 static struct kobj_attribute _name##_attr = \
  27         __ATTR(_name, 0644, _name##_show, _name##_store)
  28
  29 #if defined(CONFIG_HOTPLUG)
  30 /* current uevent sequence number */
  31 static ssize_t uevent_seqnum_show(struct kobject *kobj,
  32                                   struct kobj_attribute *attr, char *buf)
  33 {
  34         return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum);
  35 }
  36 KERNEL_ATTR_RO(uevent_seqnum);
  37
  38 /* uevent helper program, used during early boot */
  39 static ssize_t uevent_helper_show(struct kobject *kobj,
  40                                   struct kobj_attribute *attr, char *buf)
  41 {
  42         return sprintf(buf, "%s\n", uevent_helper);
  43 }
  44 static ssize_t uevent_helper_store(struct kobject *kobj,
  45                                    struct kobj_attribute *attr,
  46                                    const char *buf, size_t count)
  47 {
  48         if (count+1 > UEVENT_HELPER_PATH_LEN)
  49                 return -ENOENT;
  50         memcpy(uevent_helper, buf, count);
  51         uevent_helper[count] = '\0';
  52         if (count && uevent_helper[count-1] == '\n')
  53                 uevent_helper[count-1] = '\0';
  54         return count;
  55 }
  56 KERNEL_ATTR_RW(uevent_helper);
  57 #endif
  58
  59 #ifdef CONFIG_PROFILING
  60 static ssize_t profiling_show(struct kobject *kobj,
  61                                   struct kobj_attribute *attr, char *buf)
  62 {
  63         return sprintf(buf, "%d\n", prof_on);
  64 }
  65 static ssize_t profiling_store(struct kobject *kobj,
  66                                    struct kobj_attribute *attr,
  67                                    const char *buf, size_t count)
  68 {
  69         int ret;
  70
  71         if (prof_on)
  72                 return -EEXIST;
  73         /*
  74          * This eventually calls into get_option() which
  75          * has a ton of callers and is not const.  It is
  76          * easiest to cast it away here.
  77          */
  78         profile_setup((char *)buf);
  79         ret = profile_init();
  80         if (ret)
  81                 return ret;
  82         ret = create_proc_profile();
  83         if (ret)
  84                 return ret;
  85         return count;
  86 }
  87 KERNEL_ATTR_RW(profiling);
  88 #endif
  89
  90 #ifdef CONFIG_KEXEC
  91 static ssize_t kexec_loaded_show(struct kobject *kobj,
  92                                  struct kobj_attribute *attr, char *buf)
  93 {
  94         return sprintf(buf, "%d\n", !!kexec_image);
  95 }
  96 KERNEL_ATTR_RO(kexec_loaded);
  97
  98 static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
  99                                        struct kobj_attribute *attr, char *buf)
 100 {
 101         return sprintf(buf, "%d\n", !!kexec_crash_image);
 102 }
 103 KERNEL_ATTR_RO(kexec_crash_loaded);
 104
 105 static ssize_t kexec_crash_size_show(struct kobject *kobj,
 106                                        struct kobj_attribute *attr, char *buf)
 107 {
 108         return sprintf(buf, "%zu\n", crash_get_memory_size());
 109 }
 110 static ssize_t kexec_crash_size_store(struct kobject *kobj,
 111                                    struct kobj_attribute *attr,
 112                                    const char *buf, size_t count)
 113 {
 114         unsigned long cnt;
 115         int ret;
 116
 117         if (strict_strtoul(buf, 0, &cnt))
 118                 return -EINVAL;
 119
 120         ret = crash_shrink_memory(cnt);
 121         return ret < 0 ? ret : count;
 122 }
 123 KERNEL_ATTR_RW(kexec_crash_size);
 124
 125 static ssize_t vmcoreinfo_show(struct kobject *kobj,
 126                                struct kobj_attribute *attr, char *buf)
 127 {
 128         return sprintf(buf, "%lx %x\n",
 129                        paddr_vmcoreinfo_note(),
 130                        (unsigned int)vmcoreinfo_max_size);
 131 }
 132 KERNEL_ATTR_RO(vmcoreinfo);
 133
 134 #endif /* CONFIG_KEXEC */
 135
 136 /* whether file capabilities are enabled */
 137 static ssize_t fscaps_show(struct kobject *kobj,
 138                                   struct kobj_attribute *attr, char *buf)
 139 {
 140         return sprintf(buf, "%d\n", file_caps_enabled);
 141 }
 142 KERNEL_ATTR_RO(fscaps);
 143
 144 int rcu_expedited;
 145 static ssize_t rcu_expedited_show(struct kobject *kobj,
 146                                   struct kobj_attribute *attr, char *buf)
 147 {
 148         return sprintf(buf, "%d\n", rcu_expedited);
 149 }
 150 static ssize_t rcu_expedited_store(struct kobject *kobj,
 151                                    struct kobj_attribute *attr,
 152                                    const char *buf, size_t count)
 153 {
 154         if (kstrtoint(buf, 0, &rcu_expedited))
 155                 return -EINVAL;
 156
 157         return count;
 158 }
 159 KERNEL_ATTR_RW(rcu_expedited);
 160
 161 /*
 162  * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
 163  */
 164 extern const void __start_notes __attribute__((weak));
 165 extern const void __stop_notes __attribute__((weak));
 166 #define notes_size (&__stop_notes - &__start_notes)
 167
 168 static ssize_t notes_read(struct file *filp, struct kobject *kobj,
 169                           struct bin_attribute *bin_attr,
 170                           char *buf, loff_t off, size_t count)
 171 {
 172         memcpy(buf, &__start_notes + off, count);
 173         return count;
 174 }
 175
 176 static struct bin_attribute notes_attr = {
 177         .attr = {
 178                 .name = "notes",
 179                 .mode = S_IRUGO,
 180         },
 181         .read = &notes_read,
 182 };
 183
 184 struct kobject *kernel_kobj;
 185 EXPORT_SYMBOL_GPL(kernel_kobj);
 186
 187 static struct attribute * kernel_attrs[] = {
 188         &fscaps_attr.attr,
 189 #if defined(CONFIG_HOTPLUG)
 190         &uevent_seqnum_attr.attr,
 191         &uevent_helper_attr.attr,
 192 #endif
 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);