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 boot */
  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 kexec_crash_size_show(struct kobject *kobj,
 104                                        struct kobj_attribute *attr, char *buf)
 105 {
 106         return sprintf(buf, "%zu\n", crash_get_memory_size());
 107 }
 108 static ssize_t kexec_crash_size_store(struct kobject *kobj,
 109                                    struct kobj_attribute *attr,
 110                                    const char *buf, size_t count)
 111 {
 112         unsigned long cnt;
 113         int ret;
 114
 115         if (strict_strtoul(buf, 0, &cnt))
 116                 return -EINVAL;
 117
 118         ret = crash_shrink_memory(cnt);
 119         return ret < 0 ? ret : count;
 120 }
 121 KERNEL_ATTR_RW(kexec_crash_size);
 122
 123 static ssize_t vmcoreinfo_show(struct kobject *kobj,
 124                                struct kobj_attribute *attr, char *buf)
 125 {
 126         return sprintf(buf, "%lx %x\n",
 127                        paddr_vmcoreinfo_note(),
 128                        (unsigned int)vmcoreinfo_max_size);
 129 }
 130 KERNEL_ATTR_RO(vmcoreinfo);
 131
 132 #endif /* CONFIG_KEXEC */
 133
 134 /*
 135  * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
 136  */
 137 extern const void __start_notes __attribute__((weak));
 138 extern const void __stop_notes __attribute__((weak));
 139 #define notes_size (&__stop_notes - &__start_notes)
 140
 141 static ssize_t notes_read(struct kobject *kobj, struct bin_attribute *bin_attr,
 142                           char *buf, loff_t off, size_t count)
 143 {
 144         memcpy(buf, &__start_notes + off, count);
 145         return count;
 146 }
 147
 148 static struct bin_attribute notes_attr = {
 149         .attr = {
 150                 .name = "notes",
 151                 .mode = S_IRUGO,
 152         },
 153         .read = &notes_read,
 154 };
 155
 156 struct kobject *kernel_kobj;
 157 EXPORT_SYMBOL_GPL(kernel_kobj);
 158
 159 static struct attribute * kernel_attrs[] = {
 160 #if defined(CONFIG_HOTPLUG)
 161         &uevent_seqnum_attr.attr,
 162         &uevent_helper_attr.attr,
 163 #endif
 164 #ifdef CONFIG_PROFILING
 165         &profiling_attr.attr,
 166 #endif
 167 #ifdef CONFIG_KEXEC
 168         &kexec_loaded_attr.attr,
 169         &kexec_crash_loaded_attr.attr,
 170         &kexec_crash_size_attr.attr,
 171         &vmcoreinfo_attr.attr,
 172 #endif
 173         NULL
 174 };
 175
 176 static struct attribute_group kernel_attr_group = {
 177         .attrs = kernel_attrs,
 178 };
 179
 180 static int __init ksysfs_init(void)
 181 {
 182         int error;
 183
 184         kernel_kobj = kobject_create_and_add("kernel", NULL);
 185         if (!kernel_kobj) {
 186                 error = -ENOMEM;
 187                 goto exit;
 188         }
 189         error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
 190         if (error)
 191                 goto kset_exit;
 192
 193         if (notes_size > 0) {
 194                 notes_attr.size = notes_size;
 195                 error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
 196                 if (error)
 197                         goto group_exit;
 198         }
 199
 200         return 0;
 201
 202 group_exit:
 203         sysfs_remove_group(kernel_kobj, &kernel_attr_group);
 204 kset_exit:
 205         kobject_put(kernel_kobj);
 206 exit:
 207         return error;
 208 }
 209
 210 core_initcall(ksysfs_init);