root/kernel/ksysfs.c

DEFINITIONS

1. uevent_seqnum_show
2. uevent_helper_show
3. uevent_helper_store
4. kexec_loaded_show
5. kexec_crash_loaded_show
6. vmcoreinfo_show
7. notes_read
8. ksysfs_init

/*
 * kernel/ksysfs.c - sysfs attributes in /sys/kernel, which
 *                   are not related to any other subsystem
 *
 * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
 * 
 * This file is release under the GPLv2
 *
 */

#include <linux/kobject.h>
#include <linux/string.h>
#include <linux/sysfs.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kexec.h>
#include <linux/sched.h>

#define KERNEL_ATTR_RO(_name) \
static struct kobj_attribute _name##_attr = __ATTR_RO(_name)

#define KERNEL_ATTR_RW(_name) \
static struct kobj_attribute _name##_attr = \
        __ATTR(_name, 0644, _name##_show, _name##_store)

#if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET)
/* current uevent sequence number */
static ssize_t uevent_seqnum_show(struct kobject *kobj,
                                  struct kobj_attribute *attr, char *buf)
{
        return sprintf(buf, "%llu\n", (unsigned long long)uevent_seqnum);
}
KERNEL_ATTR_RO(uevent_seqnum);

/* uevent helper program, used during early boo */
static ssize_t uevent_helper_show(struct kobject *kobj,
                                  struct kobj_attribute *attr, char *buf)
{
        return sprintf(buf, "%s\n", uevent_helper);
}
static ssize_t uevent_helper_store(struct kobject *kobj,
                                   struct kobj_attribute *attr,
                                   const char *buf, size_t count)
{
        if (count+1 > UEVENT_HELPER_PATH_LEN)
                return -ENOENT;
        memcpy(uevent_helper, buf, count);
        uevent_helper[count] = '\0';
        if (count && uevent_helper[count-1] == '\n')
                uevent_helper[count-1] = '\0';
        return count;
}
KERNEL_ATTR_RW(uevent_helper);
#endif

#ifdef CONFIG_KEXEC
static ssize_t kexec_loaded_show(struct kobject *kobj,
                                 struct kobj_attribute *attr, char *buf)
{
        return sprintf(buf, "%d\n", !!kexec_image);
}
KERNEL_ATTR_RO(kexec_loaded);

static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
                                       struct kobj_attribute *attr, char *buf)
{
        return sprintf(buf, "%d\n", !!kexec_crash_image);
}
KERNEL_ATTR_RO(kexec_crash_loaded);

static ssize_t vmcoreinfo_show(struct kobject *kobj,
                               struct kobj_attribute *attr, char *buf)
{
        return sprintf(buf, "%lx %x\n",
                       paddr_vmcoreinfo_note(),
                       (unsigned int)vmcoreinfo_max_size);
}
KERNEL_ATTR_RO(vmcoreinfo);

#endif /* CONFIG_KEXEC */

/*
 * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
 */
extern const void __start_notes __attribute__((weak));
extern const void __stop_notes __attribute__((weak));
#define notes_size (&__stop_notes - &__start_notes)

static ssize_t notes_read(struct kobject *kobj, struct bin_attribute *bin_attr,
                          char *buf, loff_t off, size_t count)
{
        memcpy(buf, &__start_notes + off, count);
        return count;
}

static struct bin_attribute notes_attr = {
        .attr = {
                .name = "notes",
                .mode = S_IRUGO,
        },
        .read = &notes_read,
};

struct kobject *kernel_kobj;
EXPORT_SYMBOL_GPL(kernel_kobj);

static struct attribute * kernel_attrs[] = {
#if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET)
        &uevent_seqnum_attr.attr,
        &uevent_helper_attr.attr,
#endif
#ifdef CONFIG_KEXEC
        &kexec_loaded_attr.attr,
        &kexec_crash_loaded_attr.attr,
        &vmcoreinfo_attr.attr,
#endif
        NULL
};

static struct attribute_group kernel_attr_group = {
        .attrs = kernel_attrs,
};

static int __init ksysfs_init(void)
{
        int error;

        kernel_kobj = kobject_create_and_add("kernel", NULL);
        if (!kernel_kobj) {
                error = -ENOMEM;
                goto exit;
        }
        error = sysfs_create_group(kernel_kobj, &kernel_attr_group);
        if (error)
                goto kset_exit;

        if (notes_size > 0) {
                notes_attr.size = notes_size;
                error = sysfs_create_bin_file(kernel_kobj, &notes_attr);
                if (error)
                        goto group_exit;
        }

        /* create the /sys/kernel/uids/ directory */
        error = uids_sysfs_init();
        if (error)
                goto notes_exit;

        return 0;

notes_exit:
        if (notes_size > 0)
                sysfs_remove_bin_file(kernel_kobj, &notes_attr);
group_exit:
        sysfs_remove_group(kernel_kobj, &kernel_attr_group);
kset_exit:
        kobject_put(kernel_kobj);
exit:
        return error;
}

core_initcall(ksysfs_init);