// SPDX-License-Identifier: GPL-2.0-only
/*
 * 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>
 */

#include <asm/byteorder.h>
#include <linux/kobject.h>
#include <linux/string.h>
#include <linux/sysfs.h>
#include <linux/export.h>
#include <linux/init.h>
#include <linux/vmcore_info.h>
#include <linux/profile.h>
#include <linux/stat.h>
#include <linux/sched.h>
#include <linux/capability.h>
#include <linux/compiler.h>

#include <linux/rcupdate.h>     /* rcu_expedited and rcu_normal */

#if defined(__LITTLE_ENDIAN)
#define CPU_BYTEORDER_STRING    "little"
#elif defined(__BIG_ENDIAN)
#define CPU_BYTEORDER_STRING    "big"
#else
#error Unknown byteorder
#endif

#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_RW(_name)

/* current uevent sequence number */
static ssize_t uevent_seqnum_show(struct kobject *kobj,
                                  struct kobj_attribute *attr, char *buf)
{
        return sysfs_emit(buf, "%llu\n", (u64)atomic64_read(&uevent_seqnum));
}
KERNEL_ATTR_RO(uevent_seqnum);

/* cpu byteorder */
static ssize_t cpu_byteorder_show(struct kobject *kobj,
                                  struct kobj_attribute *attr, char *buf)
{
        return sysfs_emit(buf, "%s\n", CPU_BYTEORDER_STRING);
}
KERNEL_ATTR_RO(cpu_byteorder);

/* address bits */
static ssize_t address_bits_show(struct kobject *kobj,
                                 struct kobj_attribute *attr, char *buf)
{
        return sysfs_emit(buf, "%zu\n", sizeof(void *) * 8 /* CHAR_BIT */);
}
KERNEL_ATTR_RO(address_bits);

#ifdef CONFIG_UEVENT_HELPER
/* uevent helper program, used during early boot */
static ssize_t uevent_helper_show(struct kobject *kobj,
                                  struct kobj_attribute *attr, char *buf)
{
        return sysfs_emit(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 sysfs_emit(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;
        static DEFINE_MUTEX(lock);

        /*
         * We need serialization, for profile_setup() initializes prof_on
         * value and profile_init() must not reallocate prof_buffer after
         * once allocated.
         */
        guard(mutex)(&lock);
        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_VMCORE_INFO

static ssize_t vmcoreinfo_show(struct kobject *kobj,
                               struct kobj_attribute *attr, char *buf)
{
        phys_addr_t vmcore_base = paddr_vmcoreinfo_note();
        return sysfs_emit(buf, "%pa %x\n", &vmcore_base,
                          (unsigned int)VMCOREINFO_NOTE_SIZE);
}
KERNEL_ATTR_RO(vmcoreinfo);

#endif /* CONFIG_VMCORE_INFO */

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

#ifndef CONFIG_TINY_RCU
int rcu_expedited;
static ssize_t rcu_expedited_show(struct kobject *kobj,
                                  struct kobj_attribute *attr, char *buf)
{
        return sysfs_emit(buf, "%d\n", READ_ONCE(rcu_expedited));
}
static ssize_t rcu_expedited_store(struct kobject *kobj,
                                   struct kobj_attribute *attr,
                                   const char *buf, size_t count)
{
        if (kstrtoint(buf, 0, &rcu_expedited))
                return -EINVAL;

        return count;
}
KERNEL_ATTR_RW(rcu_expedited);

int rcu_normal;
static ssize_t rcu_normal_show(struct kobject *kobj,
                               struct kobj_attribute *attr, char *buf)
{
        return sysfs_emit(buf, "%d\n", READ_ONCE(rcu_normal));
}
static ssize_t rcu_normal_store(struct kobject *kobj,
                                struct kobj_attribute *attr,
                                const char *buf, size_t count)
{
        if (kstrtoint(buf, 0, &rcu_normal))
                return -EINVAL;

        return count;
}
KERNEL_ATTR_RW(rcu_normal);
#endif /* #ifndef CONFIG_TINY_RCU */

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

static __ro_after_init BIN_ATTR_SIMPLE_RO(notes);

struct kobject *kernel_kobj;
EXPORT_SYMBOL_GPL(kernel_kobj);

static struct attribute * kernel_attrs[] = {
        &fscaps_attr.attr,
        &uevent_seqnum_attr.attr,
        &cpu_byteorder_attr.attr,
        &address_bits_attr.attr,
#ifdef CONFIG_UEVENT_HELPER
        &uevent_helper_attr.attr,
#endif
#ifdef CONFIG_PROFILING
        &profiling_attr.attr,
#endif
#ifdef CONFIG_VMCORE_INFO
        &vmcoreinfo_attr.attr,
#endif
#ifndef CONFIG_TINY_RCU
        &rcu_expedited_attr.attr,
        &rcu_normal_attr.attr,
#endif
        NULL
};

static const 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) {
                bin_attr_notes.private = (void *)&__start_notes;
                bin_attr_notes.size = notes_size;
                error = sysfs_create_bin_file(kernel_kobj, &bin_attr_notes);
                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);