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/module.h>
  15 #include <linux/init.h>
  16 #include <linux/kexec.h>
  17 #include <linux/sched.h>
  18
  19 #define KERNEL_ATTR_RO(_name) \
  20 static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
  21
  22 #define KERNEL_ATTR_RW(_name) \
  23 static struct kobj_attribute _name##_attr = \
  24         __ATTR(_name, 0644, _name##_show, _name##_store)
  25
  26 #if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET)
  27 /* current uevent sequence number */
  28 static ssize_t uevent_seqnum_show(struct kobject *kobj,
  29                                   struct kobj_attribute *attr, char *buf)
  30 {
  31         return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum);
  32 }
  33 KERNEL_ATTR_RO(uevent_seqnum);
  34
  35 /* uevent helper program, used during early boo */
  36 static ssize_t uevent_helper_show(struct kobject *kobj,
  37                                   struct kobj_attribute *attr, char *buf)
  38 {
  39         return sprintf(buf, "%s\n", uevent_helper);
  40 }
  41 static ssize_t uevent_helper_store(struct kobject *kobj,
  42                                    struct kobj_attribute *attr,
  43                                    const char *buf, size_t count)
  44 {
  45         if (count+1 > UEVENT_HELPER_PATH_LEN)
  46                 return -ENOENT;
  47         memcpy(uevent_helper, buf, count);
  48         uevent_helper[count] = '\0';
  49         if (count && uevent_helper[count-1] == '\n')
  50                 uevent_helper[count-1] = '\0';
  51         return count;
  52 }
  53 KERNEL_ATTR_RW(uevent_helper);
  54 #endif
  55
  56 #ifdef CONFIG_KEXEC
  57 static ssize_t kexec_loaded_show(struct kobject *kobj,
  58                                  struct kobj_attribute *attr, char *buf)
  59 {
  60         return sprintf(buf, "%d\n", !!kexec_image);
  61 }
  62 KERNEL_ATTR_RO(kexec_loaded);
  63
  64 static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
  65                                        struct kobj_attribute *attr, char *buf)
  66 {
  67         return sprintf(buf, "%d\n", !!kexec_crash_image);
  68 }
  69 KERNEL_ATTR_RO(kexec_crash_loaded);
  70
  71 static ssize_t vmcoreinfo_show(struct kobject *kobj,
  72                                struct kobj_attribute *attr, char *buf)
  73 {
  74         return sprintf(buf, "%lx %x\n",
  75                        paddr_vmcoreinfo_note(),
  76                        (unsigned int)vmcoreinfo_max_size);
  77 }
  78 KERNEL_ATTR_RO(vmcoreinfo);
  79
  80 #endif /* CONFIG_KEXEC */
  81
  82 /*
  83  * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
  84  */
  85 extern const void __start_notes __attribute__((weak));
  86 extern const void __stop_notes __attribute__((weak));
  87 #define notes_size (&__stop_notes - &__start_notes)
  88
  89 static ssize_t notes_read(struct kobject *kobj, struct bin_attribute *bin_attr,
  90                           char *buf, loff_t off, size_t count)
  91 {
  92         memcpy(buf, &__start_notes + off, count);
  93         return count;
  94 }
  95
  96 static struct bin_attribute notes_attr = {
  97         .attr = {
  98                 .name = "notes",
  99                 .mode = S_IRUGO,
 100         },
 101         .read = &notes_read,
 102 };
 103
 104 struct kobject *kernel_kobj;
 105 EXPORT_SYMBOL_GPL(kernel_kobj);
 106
 107 static struct attribute * kernel_attrs[] = {
 108 #if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET)
 109         &uevent_seqnum_attr.attr,
 110         &uevent_helper_attr.attr,
 111 #endif
 112 #ifdef CONFIG_KEXEC
 113         &kexec_loaded_attr.attr,
 114         &kexec_crash_loaded_attr.attr,
 115         &vmcoreinfo_attr.attr,
 116 #endif
 117         NULL
 118 };
 119
 120 static struct attribute_group kernel_attr_group = {
 121         .attrs = kernel_attrs,
 122 };
 123
 124 static int __init ksysfs_init(void)
 125 {
 126         int error;
 127
 128         kernel_kobj = kobject_create_and_add("kernel", NULL);
 129         if (!kernel_kobj) {
 130                 error = -ENOMEM;
 131                 goto exit;
 132         }
 133         error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
 134         if (error)
 135                 goto kset_exit;
 136
 137         if (notes_size > 0) {
 138                 notes_attr.size = notes_size;
 139                 error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
 140                 if (error)
 141                         goto group_exit;
 142         }
 143
 144         /* create the /sys/kernel/uids/ directory */
 145         error = uids_sysfs_init();
 146         if (error)
 147                 goto notes_exit;
 148
 149         return 0;
 150
 151 notes_exit:
 152         if (notes_size > 0)
 153                 sysfs_remove_bin_file(kernel_kobj, &notes_attr);
 154 group_exit:
 155         sysfs_remove_group(kernel_kobj, &kernel_attr_group);
 156 kset_exit:
 157         kobject_put(kernel_kobj);
 158 exit:
 159         return error;
 160 }
 161
 162 core_initcall(ksysfs_init);