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/export.h>
  15 #include <linux/init.h>
  16 #include <linux/kexec.h>
  17 #include <linux/profile.h>
  18 #include <linux/stat.h>
  19 #include <linux/sched.h>
  20 #include <linux/capability.h>
  21
  22 #include <linux/rcupdate.h>     /* rcu_expedited */
  23
  24 #define KERNEL_ATTR_RO(_name) \
  25 static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
  26
  27 #define KERNEL_ATTR_RW(_name) \
  28 static struct kobj_attribute _name##_attr = \
  29         __ATTR(_name, 0644, _name##_show, _name##_store)
  30
  31 /* current uevent sequence number */
  32 static ssize_t uevent_seqnum_show(struct kobject *kobj,
  33                                   struct kobj_attribute *attr, char *buf)
  34 {
  35         return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum);
  36 }
  37 KERNEL_ATTR_RO(uevent_seqnum);
  38
  39 /* uevent helper program, used during early boot */
  40 static ssize_t uevent_helper_show(struct kobject *kobj,
  41                                   struct kobj_attribute *attr, char *buf)
  42 {
  43         return sprintf(buf, "%s\n", uevent_helper);
  44 }
  45 static ssize_t uevent_helper_store(struct kobject *kobj,
  46                                    struct kobj_attribute *attr,
  47                                    const char *buf, size_t count)
  48 {
  49         if (count+1 > UEVENT_HELPER_PATH_LEN)
  50                 return -ENOENT;
  51         memcpy(uevent_helper, buf, count);
  52         uevent_helper[count] = '\0';
  53         if (count && uevent_helper[count-1] == '\n')
  54                 uevent_helper[count-1] = '\0';
  55         return count;
  56 }
  57 KERNEL_ATTR_RW(uevent_helper);
  58
  59
  60 #ifdef CONFIG_PROFILING
  61 static ssize_t profiling_show(struct kobject *kobj,
  62                                   struct kobj_attribute *attr, char *buf)
  63 {
  64         return sprintf(buf, "%d\n", prof_on);
  65 }
  66 static ssize_t profiling_store(struct kobject *kobj,
  67                                    struct kobj_attribute *attr,
  68                                    const char *buf, size_t count)
  69 {
  70         int ret;
  71
  72         if (prof_on)
  73                 return -EEXIST;
  74         /*
  75          * This eventually calls into get_option() which
  76          * has a ton of callers and is not const.  It is
  77          * easiest to cast it away here.
  78          */
  79         profile_setup((char *)buf);
  80         ret = profile_init();
  81         if (ret)
  82                 return ret;
  83         ret = create_proc_profile();
  84         if (ret)
  85                 return ret;
  86         return count;
  87 }
  88 KERNEL_ATTR_RW(profiling);
  89 #endif
  90
  91 #ifdef CONFIG_KEXEC
  92 static ssize_t kexec_loaded_show(struct kobject *kobj,
  93                                  struct kobj_attribute *attr, char *buf)
  94 {
  95         return sprintf(buf, "%d\n", !!kexec_image);
  96 }
  97 KERNEL_ATTR_RO(kexec_loaded);
  98
  99 static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
 100                                        struct kobj_attribute *attr, char *buf)
 101 {
 102         return sprintf(buf, "%d\n", !!kexec_crash_image);
 103 }
 104 KERNEL_ATTR_RO(kexec_crash_loaded);
 105
 106 static ssize_t kexec_crash_size_show(struct kobject *kobj,
 107                                        struct kobj_attribute *attr, char *buf)
 108 {
 109         return sprintf(buf, "%zu\n", crash_get_memory_size());
 110 }
 111 static ssize_t kexec_crash_size_store(struct kobject *kobj,
 112                                    struct kobj_attribute *attr,
 113                                    const char *buf, size_t count)
 114 {
 115         unsigned long cnt;
 116         int ret;
 117
 118         if (kstrtoul(buf, 0, &cnt))
 119                 return -EINVAL;
 120
 121         ret = crash_shrink_memory(cnt);
 122         return ret < 0 ? ret : count;
 123 }
 124 KERNEL_ATTR_RW(kexec_crash_size);
 125
 126 static ssize_t vmcoreinfo_show(struct kobject *kobj,
 127                                struct kobj_attribute *attr, char *buf)
 128 {
 129         return sprintf(buf, "%lx %x\n",
 130                        paddr_vmcoreinfo_note(),
 131                        (unsigned int)sizeof(vmcoreinfo_note));
 132 }
 133 KERNEL_ATTR_RO(vmcoreinfo);
 134
 135 #endif /* CONFIG_KEXEC */
 136
 137 /* whether file capabilities are enabled */
 138 static ssize_t fscaps_show(struct kobject *kobj,
 139                                   struct kobj_attribute *attr, char *buf)
 140 {
 141         return sprintf(buf, "%d\n", file_caps_enabled);
 142 }
 143 KERNEL_ATTR_RO(fscaps);
 144
 145 int rcu_expedited;
 146 static ssize_t rcu_expedited_show(struct kobject *kobj,
 147                                   struct kobj_attribute *attr, char *buf)
 148 {
 149         return sprintf(buf, "%d\n", rcu_expedited);
 150 }
 151 static ssize_t rcu_expedited_store(struct kobject *kobj,
 152                                    struct kobj_attribute *attr,
 153                                    const char *buf, size_t count)
 154 {
 155         if (kstrtoint(buf, 0, &rcu_expedited))
 156                 return -EINVAL;
 157
 158         return count;
 159 }
 160 KERNEL_ATTR_RW(rcu_expedited);
 161
 162 /*
 163  * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
 164  */
 165 extern const void __start_notes __attribute__((weak));
 166 extern const void __stop_notes __attribute__((weak));
 167 #define notes_size (&__stop_notes - &__start_notes)
 168
 169 static ssize_t notes_read(struct file *filp, struct kobject *kobj,
 170                           struct bin_attribute *bin_attr,
 171                           char *buf, loff_t off, size_t count)
 172 {
 173         memcpy(buf, &__start_notes + off, count);
 174         return count;
 175 }
 176
 177 static struct bin_attribute notes_attr = {
 178         .attr = {
 179                 .name = "notes",
 180                 .mode = S_IRUGO,
 181         },
 182         .read = &notes_read,
 183 };
 184
 185 struct kobject *kernel_kobj;
 186 EXPORT_SYMBOL_GPL(kernel_kobj);
 187
 188 static struct attribute * kernel_attrs[] = {
 189         &fscaps_attr.attr,
 190         &uevent_seqnum_attr.attr,
 191         &uevent_helper_attr.attr,
 192 #ifdef CONFIG_PROFILING
 193         &profiling_attr.attr,
 194 #endif
 195 #ifdef CONFIG_KEXEC
 196         &kexec_loaded_attr.attr,
 197         &kexec_crash_loaded_attr.attr,
 198         &kexec_crash_size_attr.attr,
 199         &vmcoreinfo_attr.attr,
 200 #endif
 201         &rcu_expedited_attr.attr,
 202         NULL
 203 };
 204
 205 static struct attribute_group kernel_attr_group = {
 206         .attrs = kernel_attrs,
 207 };
 208
 209 static int __init ksysfs_init(void)
 210 {
 211         int error;
 212
 213         kernel_kobj = kobject_create_and_add("kernel", NULL);
 214         if (!kernel_kobj) {
 215                 error = -ENOMEM;
 216                 goto exit;
 217         }
 218         error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
 219         if (error)
 220                 goto kset_exit;
 221
 222         if (notes_size > 0) {
 223                 notes_attr.size = notes_size;
 224                 error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
 225                 if (error)
 226                         goto group_exit;
 227         }
 228
 229         return 0;
 230
 231 group_exit:
 232         sysfs_remove_group(kernel_kobj, &kernel_attr_group);
 233 kset_exit:
 234         kobject_put(kernel_kobj);
 235 exit:
 236         return error;
 237 }
 238
 239 core_initcall(ksysfs_init);