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
  65 static ssize_t vmcoreinfo_show(struct kset *kset, char *page)
  66 {
  67         return sprintf(page, "%lx %x\n",
  68                        paddr_vmcoreinfo_note(),
  69                        (unsigned int)vmcoreinfo_max_size);
  70 }
  71 KERNEL_ATTR_RO(vmcoreinfo);
  72
  73 #endif /* CONFIG_KEXEC */
  74
  75 /*
  76  * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
  77  */
  78 extern const void __start_notes __attribute__((weak));
  79 extern const void __stop_notes __attribute__((weak));
  80 #define notes_size (&__stop_notes - &__start_notes)
  81
  82 static ssize_t notes_read(struct kobject *kobj, struct bin_attribute *bin_attr,
  83                           char *buf, loff_t off, size_t count)
  84 {
  85         memcpy(buf, &__start_notes + off, count);
  86         return count;
  87 }
  88
  89 static struct bin_attribute notes_attr = {
  90         .attr = {
  91                 .name = "notes",
  92                 .mode = S_IRUGO,
  93         },
  94         .read = &notes_read,
  95 };
  96
  97 decl_subsys(kernel, NULL, NULL);
  98 EXPORT_SYMBOL_GPL(kernel_subsys);
  99
 100 static struct attribute * kernel_attrs[] = {
 101 #if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET)
 102         &uevent_seqnum_attr.attr,
 103         &uevent_helper_attr.attr,
 104 #endif
 105 #ifdef CONFIG_KEXEC
 106         &kexec_loaded_attr.attr,
 107         &kexec_crash_loaded_attr.attr,
 108         &vmcoreinfo_attr.attr,
 109 #endif
 110         NULL
 111 };
 112
 113 static struct attribute_group kernel_attr_group = {
 114         .attrs = kernel_attrs,
 115 };
 116
 117 static int __init ksysfs_init(void)
 118 {
 119         int error = subsystem_register(&kernel_subsys);
 120         if (!error)
 121                 error = sysfs_create_group(&kernel_subsys.kobj,
 122                                            &kernel_attr_group);
 123
 124         if (!error && notes_size > 0) {
 125                 notes_attr.size = notes_size;
 126                 error = sysfs_create_bin_file(&kernel_subsys.kobj,
 127                                               &notes_attr);
 128         }
 129
 130         /*
 131          * Create "/sys/kernel/uids" directory and corresponding root user's
 132          * directory under it.
 133          */
 134         if (!error)
 135                 error = uids_kobject_init();
 136
 137         return error;
 138 }
 139
 140 core_initcall(ksysfs_init);