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/profile.h>
  18 #include <linux/sched.h>
  19
  20 #define KERNEL_ATTR_RO(_name) \
  21 static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
  22
  23 #define KERNEL_ATTR_RW(_name) \
  24 static struct kobj_attribute _name##_attr = \
  25         __ATTR(_name, 0644, _name##_show, _name##_store)
  26
  27 #if defined(CONFIG_HOTPLUG)
  28 /* current uevent sequence number */
  29 static ssize_t uevent_seqnum_show(struct kobject *kobj,
  30                                   struct kobj_attribute *attr, char *buf)
  31 {
  32         return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum);
  33 }
  34 KERNEL_ATTR_RO(uevent_seqnum);
  35
  36 /* uevent helper program, used during early boo */
  37 static ssize_t uevent_helper_show(struct kobject *kobj,
  38                                   struct kobj_attribute *attr, char *buf)
  39 {
  40         return sprintf(buf, "%s\n", uevent_helper);
  41 }
  42 static ssize_t uevent_helper_store(struct kobject *kobj,
  43                                    struct kobj_attribute *attr,
  44                                    const char *buf, size_t count)
  45 {
  46         if (count+1 > UEVENT_HELPER_PATH_LEN)
  47                 return -ENOENT;
  48         memcpy(uevent_helper, buf, count);
  49         uevent_helper[count] = '\0';
  50         if (count && uevent_helper[count-1] == '\n')
  51                 uevent_helper[count-1] = '\0';
  52         return count;
  53 }
  54 KERNEL_ATTR_RW(uevent_helper);
  55 #endif
  56
  57 #ifdef CONFIG_PROFILING
  58 static ssize_t profiling_show(struct kobject *kobj,
  59                                   struct kobj_attribute *attr, char *buf)
  60 {
  61         return sprintf(buf, "%d\n", prof_on);
  62 }
  63 static ssize_t profiling_store(struct kobject *kobj,
  64                                    struct kobj_attribute *attr,
  65                                    const char *buf, size_t count)
  66 {
  67         int ret;
  68
  69         if (prof_on)
  70                 return -EEXIST;
  71         /*
  72          * This eventually calls into get_option() which
  73          * has a ton of callers and is not const.  It is
  74          * easiest to cast it away here.
  75          */
  76         profile_setup((char *)buf);
  77         ret = profile_init();
  78         if (ret)
  79                 return ret;
  80         ret = create_proc_profile();
  81         if (ret)
  82                 return ret;
  83         return count;
  84 }
  85 KERNEL_ATTR_RW(profiling);
  86 #endif
  87
  88 #ifdef CONFIG_KEXEC
  89 static ssize_t kexec_loaded_show(struct kobject *kobj,
  90                                  struct kobj_attribute *attr, char *buf)
  91 {
  92         return sprintf(buf, "%d\n", !!kexec_image);
  93 }
  94 KERNEL_ATTR_RO(kexec_loaded);
  95
  96 static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
  97                                        struct kobj_attribute *attr, char *buf)
  98 {
  99         return sprintf(buf, "%d\n", !!kexec_crash_image);
 100 }
 101 KERNEL_ATTR_RO(kexec_crash_loaded);
 102
 103 static ssize_t vmcoreinfo_show(struct kobject *kobj,
 104                                struct kobj_attribute *attr, char *buf)
 105 {
 106         return sprintf(buf, "%lx %x\n",
 107                        paddr_vmcoreinfo_note(),
 108                        (unsigned int)vmcoreinfo_max_size);
 109 }
 110 KERNEL_ATTR_RO(vmcoreinfo);
 111
 112 #endif /* CONFIG_KEXEC */
 113
 114 /*
 115  * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
 116  */
 117 extern const void __start_notes __attribute__((weak));
 118 extern const void __stop_notes __attribute__((weak));
 119 #define notes_size (&__stop_notes - &__start_notes)
 120
 121 static ssize_t notes_read(struct kobject *kobj, struct bin_attribute *bin_attr,
 122                           char *buf, loff_t off, size_t count)
 123 {
 124         memcpy(buf, &__start_notes + off, count);
 125         return count;
 126 }
 127
 128 static struct bin_attribute notes_attr = {
 129         .attr = {
 130                 .name = "notes",
 131                 .mode = S_IRUGO,
 132         },
 133         .read = &notes_read,
 134 };
 135
 136 struct kobject *kernel_kobj;
 137 EXPORT_SYMBOL_GPL(kernel_kobj);
 138
 139 static struct attribute * kernel_attrs[] = {
 140 #if defined(CONFIG_HOTPLUG)
 141         &uevent_seqnum_attr.attr,
 142         &uevent_helper_attr.attr,
 143 #endif
 144 #ifdef CONFIG_PROFILING
 145         &profiling_attr.attr,
 146 #endif
 147 #ifdef CONFIG_KEXEC
 148         &kexec_loaded_attr.attr,
 149         &kexec_crash_loaded_attr.attr,
 150         &vmcoreinfo_attr.attr,
 151 #endif
 152         NULL
 153 };
 154
 155 static struct attribute_group kernel_attr_group = {
 156         .attrs = kernel_attrs,
 157 };
 158
 159 static int __init ksysfs_init(void)
 160 {
 161         int error;
 162
 163         kernel_kobj = kobject_create_and_add("kernel", NULL);
 164         if (!kernel_kobj) {
 165                 error = -ENOMEM;
 166                 goto exit;
 167         }
 168         error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
 169         if (error)
 170                 goto kset_exit;
 171
 172         if (notes_size > 0) {
 173                 notes_attr.size = notes_size;
 174                 error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
 175                 if (error)
 176                         goto group_exit;
 177         }
 178
 179         /* create the /sys/kernel/uids/ directory */
 180         error = uids_sysfs_init();
 181         if (error)
 182                 goto notes_exit;
 183
 184         return 0;
 185
 186 notes_exit:
 187         if (notes_size > 0)
 188                 sysfs_remove_bin_file(kernel_kobj, &notes_attr);
 189 group_exit:
 190         sysfs_remove_group(kernel_kobj, &kernel_attr_group);
 191 kset_exit:
 192         kobject_put(kernel_kobj);
 193 exit:
 194         return error;
 195 }
 196
 197 core_initcall(ksysfs_init);