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 /* current uevent sequence number */
  30 static ssize_t uevent_seqnum_show(struct kobject *kobj,
  31                                   struct kobj_attribute *attr, char *buf)
  32 {
  33         return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum);
  34 }
  35 KERNEL_ATTR_RO(uevent_seqnum);
  36
  37 /* uevent helper program, used during early boot */
  38 static ssize_t uevent_helper_show(struct kobject *kobj,
  39                                   struct kobj_attribute *attr, char *buf)
  40 {
  41         return sprintf(buf, "%s\n", uevent_helper);
  42 }
  43 static ssize_t uevent_helper_store(struct kobject *kobj,
  44                                    struct kobj_attribute *attr,
  45                                    const char *buf, size_t count)
  46 {
  47         if (count+1 > UEVENT_HELPER_PATH_LEN)
  48                 return -ENOENT;
  49         memcpy(uevent_helper, buf, count);
  50         uevent_helper[count] = '\0';
  51         if (count && uevent_helper[count-1] == '\n')
  52                 uevent_helper[count-1] = '\0';
  53         return count;
  54 }
  55 KERNEL_ATTR_RW(uevent_helper);
  56
  57
  58 #ifdef CONFIG_PROFILING
  59 static ssize_t profiling_show(struct kobject *kobj,
  60                                   struct kobj_attribute *attr, char *buf)
  61 {
  62         return sprintf(buf, "%d\n", prof_on);
  63 }
  64 static ssize_t profiling_store(struct kobject *kobj,
  65                                    struct kobj_attribute *attr,
  66                                    const char *buf, size_t count)
  67 {
  68         int ret;
  69
  70         if (prof_on)
  71                 return -EEXIST;
  72         /*
  73          * This eventually calls into get_option() which
  74          * has a ton of callers and is not const.  It is
  75          * easiest to cast it away here.
  76          */
  77         profile_setup((char *)buf);
  78         ret = profile_init();
  79         if (ret)
  80                 return ret;
  81         ret = create_proc_profile();
  82         if (ret)
  83                 return ret;
  84         return count;
  85 }
  86 KERNEL_ATTR_RW(profiling);
  87 #endif
  88
  89 #ifdef CONFIG_KEXEC
  90 static ssize_t kexec_loaded_show(struct kobject *kobj,
  91                                  struct kobj_attribute *attr, char *buf)
  92 {
  93         return sprintf(buf, "%d\n", !!kexec_image);
  94 }
  95 KERNEL_ATTR_RO(kexec_loaded);
  96
  97 static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
  98                                        struct kobj_attribute *attr, char *buf)
  99 {
 100         return sprintf(buf, "%d\n", !!kexec_crash_image);
 101 }
 102 KERNEL_ATTR_RO(kexec_crash_loaded);
 103
 104 static ssize_t kexec_crash_size_show(struct kobject *kobj,
 105                                        struct kobj_attribute *attr, char *buf)
 106 {
 107         return sprintf(buf, "%zu\n", crash_get_memory_size());
 108 }
 109 static ssize_t kexec_crash_size_store(struct kobject *kobj,
 110                                    struct kobj_attribute *attr,
 111                                    const char *buf, size_t count)
 112 {
 113         unsigned long cnt;
 114         int ret;
 115
 116         if (strict_strtoul(buf, 0, &cnt))
 117                 return -EINVAL;
 118
 119         ret = crash_shrink_memory(cnt);
 120         return ret < 0 ? ret : count;
 121 }
 122 KERNEL_ATTR_RW(kexec_crash_size);
 123
 124 static ssize_t vmcoreinfo_show(struct kobject *kobj,
 125                                struct kobj_attribute *attr, char *buf)
 126 {
 127         return sprintf(buf, "%lx %x\n",
 128                        paddr_vmcoreinfo_note(),
 129                        (unsigned int)vmcoreinfo_max_size);
 130 }
 131 KERNEL_ATTR_RO(vmcoreinfo);
 132
 133 #endif /* CONFIG_KEXEC */
 134
 135 /* whether file capabilities are enabled */
 136 static ssize_t fscaps_show(struct kobject *kobj,
 137                                   struct kobj_attribute *attr, char *buf)
 138 {
 139         return sprintf(buf, "%d\n", file_caps_enabled);
 140 }
 141 KERNEL_ATTR_RO(fscaps);
 142
 143 int rcu_expedited;
 144 static ssize_t rcu_expedited_show(struct kobject *kobj,
 145                                   struct kobj_attribute *attr, char *buf)
 146 {
 147         return sprintf(buf, "%d\n", rcu_expedited);
 148 }
 149 static ssize_t rcu_expedited_store(struct kobject *kobj,
 150                                    struct kobj_attribute *attr,
 151                                    const char *buf, size_t count)
 152 {
 153         if (kstrtoint(buf, 0, &rcu_expedited))
 154                 return -EINVAL;
 155
 156         return count;
 157 }
 158 KERNEL_ATTR_RW(rcu_expedited);
 159
 160 /*
 161  * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
 162  */
 163 extern const void __start_notes __attribute__((weak));
 164 extern const void __stop_notes __attribute__((weak));
 165 #define notes_size (&__stop_notes - &__start_notes)
 166
 167 static ssize_t notes_read(struct file *filp, struct kobject *kobj,
 168                           struct bin_attribute *bin_attr,
 169                           char *buf, loff_t off, size_t count)
 170 {
 171         memcpy(buf, &__start_notes + off, count);
 172         return count;
 173 }
 174
 175 static struct bin_attribute notes_attr = {
 176         .attr = {
 177                 .name = "notes",
 178                 .mode = S_IRUGO,
 179         },
 180         .read = &notes_read,
 181 };
 182
 183 struct kobject *kernel_kobj;
 184 EXPORT_SYMBOL_GPL(kernel_kobj);
 185
 186 static struct attribute * kernel_attrs[] = {
 187         &fscaps_attr.attr,
 188         &uevent_seqnum_attr.attr,
 189         &uevent_helper_attr.attr,
 190 #ifdef CONFIG_PROFILING
 191         &profiling_attr.attr,
 192 #endif
 193 #ifdef CONFIG_KEXEC
 194         &kexec_loaded_attr.attr,
 195         &kexec_crash_loaded_attr.attr,
 196         &kexec_crash_size_attr.attr,
 197         &vmcoreinfo_attr.attr,
 198 #endif
 199         &rcu_expedited_attr.attr,
 200         NULL
 201 };
 202
 203 static struct attribute_group kernel_attr_group = {
 204         .attrs = kernel_attrs,
 205 };
 206
 207 static int __init ksysfs_init(void)
 208 {
 209         int error;
 210
 211         kernel_kobj = kobject_create_and_add("kernel", NULL);
 212         if (!kernel_kobj) {
 213                 error = -ENOMEM;
 214                 goto exit;
 215         }
 216         error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
 217         if (error)
 218                 goto kset_exit;
 219
 220         if (notes_size > 0) {
 221                 notes_attr.size = notes_size;
 222                 error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
 223                 if (error)
 224                         goto group_exit;
 225         }
 226
 227         return 0;
 228
 229 group_exit:
 230         sysfs_remove_group(kernel_kobj, &kernel_attr_group);
 231 kset_exit:
 232         kobject_put(kernel_kobj);
 233 exit:
 234         return error;
 235 }
 236
 237 core_initcall(ksysfs_init);