linux/kernel/ksysfs.c
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   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) \
  23static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
  24
  25#define KERNEL_ATTR_RW(_name) \
  26static struct kobj_attribute _name##_attr = \
  27        __ATTR(_name, 0644, _name##_show, _name##_store)
  28
  29/* current uevent sequence number */
  30static 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}
  35KERNEL_ATTR_RO(uevent_seqnum);
  36
  37/* uevent helper program, used during early boot */
  38static 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}
  43static 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}
  55KERNEL_ATTR_RW(uevent_helper);
  56
  57
  58#ifdef CONFIG_PROFILING
  59static ssize_t profiling_show(struct kobject *kobj,
  60                                  struct kobj_attribute *attr, char *buf)
  61{
  62        return sprintf(buf, "%d\n", prof_on);
  63}
  64static 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}
  86KERNEL_ATTR_RW(profiling);
  87#endif
  88
  89#ifdef CONFIG_KEXEC
  90static 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}
  95KERNEL_ATTR_RO(kexec_loaded);
  96
  97static 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}
 102KERNEL_ATTR_RO(kexec_crash_loaded);
 103
 104static 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}
 109static 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}
 122KERNEL_ATTR_RW(kexec_crash_size);
 123
 124static 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}
 131KERNEL_ATTR_RO(vmcoreinfo);
 132
 133#endif /* CONFIG_KEXEC */
 134
 135/* whether file capabilities are enabled */
 136static 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}
 141KERNEL_ATTR_RO(fscaps);
 142
 143int rcu_expedited;
 144static ssize_t rcu_expedited_show(struct kobject *kobj,
 145                                  struct kobj_attribute *attr, char *buf)
 146{
 147        return sprintf(buf, "%d\n", rcu_expedited);
 148}
 149static ssize_t rcu_expedited_store(struct kobject *kobj,
 150                                   struct kobj_attribute *attr,
 151                                   const char *buf, size_t count)
 152{
 153        if (kstrtoint(buf, 0, &rcu_expedited))
 154                return -EINVAL;
 155
 156        return count;
 157}
 158KERNEL_ATTR_RW(rcu_expedited);
 159
 160/*
 161 * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
 162 */
 163extern const void __start_notes __attribute__((weak));
 164extern const void __stop_notes __attribute__((weak));
 165#define notes_size (&__stop_notes - &__start_notes)
 166
 167static ssize_t notes_read(struct file *filp, struct kobject *kobj,
 168                          struct bin_attribute *bin_attr,
 169                          char *buf, loff_t off, size_t count)
 170{
 171        memcpy(buf, &__start_notes + off, count);
 172        return count;
 173}
 174
 175static struct bin_attribute notes_attr = {
 176        .attr = {
 177                .name = "notes",
 178                .mode = S_IRUGO,
 179        },
 180        .read = &notes_read,
 181};
 182
 183struct kobject *kernel_kobj;
 184EXPORT_SYMBOL_GPL(kernel_kobj);
 185
 186static struct attribute * kernel_attrs[] = {
 187        &fscaps_attr.attr,
 188        &uevent_seqnum_attr.attr,
 189        &uevent_helper_attr.attr,
 190#ifdef CONFIG_PROFILING
 191        &profiling_attr.attr,
 192#endif
 193#ifdef CONFIG_KEXEC
 194        &kexec_loaded_attr.attr,
 195        &kexec_crash_loaded_attr.attr,
 196        &kexec_crash_size_attr.attr,
 197        &vmcoreinfo_attr.attr,
 198#endif
 199        &rcu_expedited_attr.attr,
 200        NULL
 201};
 202
 203static struct attribute_group kernel_attr_group = {
 204        .attrs = kernel_attrs,
 205};
 206
 207static int __init ksysfs_init(void)
 208{
 209        int error;
 210
 211        kernel_kobj = kobject_create_and_add("kernel", NULL);
 212        if (!kernel_kobj) {
 213                error = -ENOMEM;
 214                goto exit;
 215        }
 216        error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
 217        if (error)
 218                goto kset_exit;
 219
 220        if (notes_size > 0) {
 221                notes_attr.size = notes_size;
 222                error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
 223                if (error)
 224                        goto group_exit;
 225        }
 226
 227        return 0;
 228
 229group_exit:
 230        sysfs_remove_group(kernel_kobj, &kernel_attr_group);
 231kset_exit:
 232        kobject_put(kernel_kobj);
 233exit:
 234        return error;
 235}
 236
 237core_initcall(ksysfs_init);
 238
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