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