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/module.h>
  15#include <linux/init.h>
  16#include <linux/kexec.h>
  17#include <linux/profile.h>
  18#include <linux/sched.h>
  19#include <linux/capability.h>
  20
  21#define KERNEL_ATTR_RO(_name) \
  22static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
  23
  24#define KERNEL_ATTR_RW(_name) \
  25static struct kobj_attribute _name##_attr = \
  26        __ATTR(_name, 0644, _name##_show, _name##_store)
  27
  28#if defined(CONFIG_HOTPLUG)
  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#endif
  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
 143/*
 144 * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
 145 */
 146extern const void __start_notes __attribute__((weak));
 147extern const void __stop_notes __attribute__((weak));
 148#define notes_size (&__stop_notes - &__start_notes)
 149
 150static 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
 158static struct bin_attribute notes_attr = {
 159        .attr = {
 160                .name = "notes",
 161                .mode = S_IRUGO,
 162        },
 163        .read = &notes_read,
 164};
 165
 166struct kobject *kernel_kobj;
 167EXPORT_SYMBOL_GPL(kernel_kobj);
 168
 169static struct attribute * kernel_attrs[] = {
 170        &fscaps_attr.attr,
 171#if defined(CONFIG_HOTPLUG)
 172        &uevent_seqnum_attr.attr,
 173        &uevent_helper_attr.attr,
 174#endif
 175#ifdef CONFIG_PROFILING
 176        &profiling_attr.attr,
 177#endif
 178#ifdef CONFIG_KEXEC
 179        &kexec_loaded_attr.attr,
 180        &kexec_crash_loaded_attr.attr,
 181        &kexec_crash_size_attr.attr,
 182        &vmcoreinfo_attr.attr,
 183#endif
 184        NULL
 185};
 186
 187static struct attribute_group kernel_attr_group = {
 188        .attrs = kernel_attrs,
 189};
 190
 191static int __init ksysfs_init(void)
 192{
 193        int error;
 194
 195        kernel_kobj = kobject_create_and_add("kernel", NULL);
 196        if (!kernel_kobj) {
 197                error = -ENOMEM;
 198                goto exit;
 199        }
 200        error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
 201        if (error)
 202                goto kset_exit;
 203
 204        if (notes_size > 0) {
 205                notes_attr.size = notes_size;
 206                error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
 207                if (error)
 208                        goto group_exit;
 209        }
 210
 211        return 0;
 212
 213group_exit:
 214        sysfs_remove_group(kernel_kobj, &kernel_attr_group);
 215kset_exit:
 216        kobject_put(kernel_kobj);
 217exit:
 218        return error;
 219}
 220
 221core_initcall(ksysfs_init);
 222
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