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 subsys_attribute _name##_attr = __ATTR_RO(_name)
  21
  22 #define KERNEL_ATTR_RW(_name) \
  23 static struct subsys_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 kset *kset, char *page)
  29 {
  30         return sprintf(page, "%llu\n", (unsigned long long)uevent_seqnum);
  31 }
  32 KERNEL_ATTR_RO(uevent_seqnum);
  33
  34 /* uevent helper program, used during early boo */
  35 static ssize_t uevent_helper_show(struct kset *kset, char *page)
  36 {
  37         return sprintf(page, "%s\n", uevent_helper);
  38 }
  39 static ssize_t uevent_helper_store(struct kset *kset, const char *page, size_t count)
  40 {
  41         if (count+1 > UEVENT_HELPER_PATH_LEN)
  42                 return -ENOENT;
  43         memcpy(uevent_helper, page, count);
  44         uevent_helper[count] = '\0';
  45         if (count && uevent_helper[count-1] == '\n')
  46                 uevent_helper[count-1] = '\0';
  47         return count;
  48 }
  49 KERNEL_ATTR_RW(uevent_helper);
  50 #endif
  51
  52 #ifdef CONFIG_KEXEC
  53 static ssize_t kexec_loaded_show(struct kset *kset, char *page)
  54 {
  55         return sprintf(page, "%d\n", !!kexec_image);
  56 }
  57 KERNEL_ATTR_RO(kexec_loaded);
  58
  59 static ssize_t kexec_crash_loaded_show(struct kset *kset, char *page)
  60 {
  61         return sprintf(page, "%d\n", !!kexec_crash_image);
  62 }
  63 KERNEL_ATTR_RO(kexec_crash_loaded);
  64 #endif /* CONFIG_KEXEC */
  65
  66 /*
  67  * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
  68  */
  69 extern const void __start_notes __attribute__((weak));
  70 extern const void __stop_notes __attribute__((weak));
  71 #define notes_size (&__stop_notes - &__start_notes)
  72
  73 static ssize_t notes_read(struct kobject *kobj, struct bin_attribute *bin_attr,
  74                           char *buf, loff_t off, size_t count)
  75 {
  76         memcpy(buf, &__start_notes + off, count);
  77         return count;
  78 }
  79
  80 static struct bin_attribute notes_attr = {
  81         .attr = {
  82                 .name = "notes",
  83                 .mode = S_IRUGO,
  84         },
  85         .read = &notes_read,
  86 };
  87
  88 decl_subsys(kernel, NULL, NULL);
  89 EXPORT_SYMBOL_GPL(kernel_subsys);
  90
  91 static struct attribute * kernel_attrs[] = {
  92 #if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET)
  93         &uevent_seqnum_attr.attr,
  94         &uevent_helper_attr.attr,
  95 #endif
  96 #ifdef CONFIG_KEXEC
  97         &kexec_loaded_attr.attr,
  98         &kexec_crash_loaded_attr.attr,
  99 #endif
 100         NULL
 101 };
 102
 103 static struct attribute_group kernel_attr_group = {
 104         .attrs = kernel_attrs,
 105 };
 106
 107 static int __init ksysfs_init(void)
 108 {
 109         int error = subsystem_register(&kernel_subsys);
 110         if (!error)
 111                 error = sysfs_create_group(&kernel_subsys.kobj,
 112                                            &kernel_attr_group);
 113
 114         if (!error && notes_size > 0) {
 115                 notes_attr.size = notes_size;
 116                 error = sysfs_create_bin_file(&kernel_subsys.kobj,
 117                                               &notes_attr);
 118         }
 119
 120         /*
 121          * Create "/sys/kernel/uids" directory and corresponding root user's
 122          * directory under it.
 123          */
 124         if (!error)
 125                 error = uids_kobject_init();
 126
 127         return error;
 128 }
 129
 130 core_initcall(ksysfs_init);