ksysfs.c

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

#include <linux/kobject.h>
#include <linux/string.h>
#include <linux/sysfs.h>
#include <linux/export.h>
#include <linux/init.h>
#include <linux/kexec.h>
#include <linux/profile.h>
#include <linux/stat.h>
#include <linux/sched.h>
#include <linux/capability.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)
/* 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 boot */
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_PROFILING
static ssize_t profiling_show(struct kobject *kobj,
                  struct kobj_attribute *attr, char *buf)
{
    return sprintf(buf, "%d\n", prof_on);
}
static ssize_t profiling_store(struct kobject *kobj,
                   struct kobj_attribute *attr,
                   const char *buf, size_t count)
{
    int ret;

    if (prof_on)
        return -EEXIST;
    /*
     * This eventually calls into get_option() which
     * has a ton of callers and is not const.  It is
     * easiest to cast it away here.
     */
    profile_setup((char *)buf);
    ret = profile_init();
    if (ret)
        return ret;
    ret = create_proc_profile();
    if (ret)
        return ret;
    return count;
}
KERNEL_ATTR_RW(profiling);
#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 kexec_crash_size_show(struct kobject *kobj,
                       struct kobj_attribute *attr, char *buf)
{
    return sprintf(buf, "%zu\n", crash_get_memory_size());
}
static ssize_t kexec_crash_size_store(struct kobject *kobj,
                   struct kobj_attribute *attr,
                   const char *buf, size_t count)
{
    unsigned long cnt;
    int ret;

    if (strict_strtoul(buf, 0, &cnt))
        return -EINVAL;

    ret = crash_shrink_memory(cnt);
    return ret < 0 ? ret : count;
}
KERNEL_ATTR_RW(kexec_crash_size);

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 */

/* whether file capabilities are enabled */
static ssize_t fscaps_show(struct kobject *kobj,
                  struct kobj_attribute *attr, char *buf)
{
    return sprintf(buf, "%d\n", file_caps_enabled);
}
KERNEL_ATTR_RO(fscaps);

/*
 * 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 file *filp, 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[] = {
    &fscaps_attr.attr,
#if defined(CONFIG_HOTPLUG)
    &uevent_seqnum_attr.attr,
    &uevent_helper_attr.attr,
#endif
#ifdef CONFIG_PROFILING
    &profiling_attr.attr,
#endif
#ifdef CONFIG_KEXEC
    &kexec_loaded_attr.attr,
    &kexec_crash_loaded_attr.attr,
    &kexec_crash_size_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;
    }

    return 0;

group_exit:
    sysfs_remove_group(kernel_kobj, &kernel_attr_group);
kset_exit:
    kobject_put(kernel_kobj);
exit:
    return error;
}

core_initcall(ksysfs_init);