/*-
 * Copyright (c) 2010 Isilon Systems, Inc.
 * Copyright (c) 2010 iX Systems, Inc.
 * Copyright (c) 2010 Panasas, Inc.
 * Copyright (c) 2013-2021 Mellanox Technologies, Ltd.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice unmodified, this list of conditions, and the following
 *    disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#include "opt_global.h"
#include "opt_stack.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/proc.h>
#include <sys/sglist.h>
#include <sys/sleepqueue.h>
#include <sys/refcount.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/bus.h>
#include <sys/eventhandler.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/filio.h>
#include <sys/rwlock.h>
#include <sys/mman.h>
#include <sys/stack.h>
#include <sys/stdarg.h>
#include <sys/sysent.h>
#include <sys/time.h>
#include <sys/user.h>

#include <vm/vm.h>
#include <vm/pmap.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pager.h>
#include <vm/vm_radix.h>

#if defined(__i386__) || defined(__amd64__)
#include <machine/cputypes.h>
#include <machine/md_var.h>
#endif

#include <linux/kobject.h>
#include <linux/cpu.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/cdev.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/sysfs.h>
#include <linux/mm.h>
#include <linux/io.h>
#include <linux/vmalloc.h>
#include <linux/netdevice.h>
#include <linux/timer.h>
#include <linux/interrupt.h>
#include <linux/uaccess.h>
#include <linux/utsname.h>
#include <linux/list.h>
#include <linux/kthread.h>
#include <linux/kernel.h>
#include <linux/compat.h>
#include <linux/io-mapping.h>
#include <linux/poll.h>
#include <linux/smp.h>
#include <linux/wait_bit.h>
#include <linux/rcupdate.h>
#include <linux/interval_tree.h>
#include <linux/interval_tree_generic.h>
#include <linux/printk.h>
#include <linux/seq_file.h>

#if defined(__i386__) || defined(__amd64__)
#include <asm/smp.h>
#include <asm/processor.h>
#endif

#include <xen/xen.h>
#ifdef XENHVM
#undef xen_pv_domain
#undef xen_initial_domain
/* xen/xen-os.h redefines __must_check */
#undef __must_check
#include <xen/xen-os.h>
#endif

SYSCTL_NODE(_compat, OID_AUTO, linuxkpi, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "LinuxKPI parameters");

int linuxkpi_debug;
SYSCTL_INT(_compat_linuxkpi, OID_AUTO, debug, CTLFLAG_RWTUN,
    &linuxkpi_debug, 0, "Set to enable pr_debug() prints. Clear to disable.");

int linuxkpi_rcu_debug;
SYSCTL_INT(_compat_linuxkpi, OID_AUTO, rcu_debug, CTLFLAG_RWTUN,
    &linuxkpi_rcu_debug, 0, "Set to enable RCU warning. Clear to disable.");

int linuxkpi_warn_dump_stack = 0;
SYSCTL_INT(_compat_linuxkpi, OID_AUTO, warn_dump_stack, CTLFLAG_RWTUN,
    &linuxkpi_warn_dump_stack, 0,
    "Set to enable stack traces from WARN_ON(). Clear to disable.");

static struct timeval lkpi_net_lastlog;
static int lkpi_net_curpps;
static int lkpi_net_maxpps = 99;
SYSCTL_INT(_compat_linuxkpi, OID_AUTO, net_ratelimit, CTLFLAG_RWTUN,
    &lkpi_net_maxpps, 0, "Limit number of LinuxKPI net messages per second.");

MALLOC_DEFINE(M_KMALLOC, "lkpikmalloc", "Linux kmalloc compat");

#include <linux/rbtree.h>
/* Undo Linux compat changes. */
#undef RB_ROOT
#undef file
#undef cdev
#define RB_ROOT(head)   (head)->rbh_root

static void linux_destroy_dev(struct linux_cdev *);
static void linux_cdev_deref(struct linux_cdev *ldev);
static struct vm_area_struct *linux_cdev_handle_find(void *handle);

cpumask_t cpu_online_mask;
static cpumask_t **static_single_cpu_mask;
static cpumask_t *static_single_cpu_mask_lcs;
struct kobject linux_class_root;
struct device linux_root_device;
struct class linux_class_misc;
struct list_head pci_drivers;
struct list_head pci_devices;
spinlock_t pci_lock;
struct uts_namespace init_uts_ns;

unsigned long linux_timer_hz_mask;

wait_queue_head_t linux_bit_waitq;
wait_queue_head_t linux_var_waitq;

int
panic_cmp(struct rb_node *one, struct rb_node *two)
{
        panic("no cmp");
}

RB_GENERATE(linux_root, rb_node, __entry, panic_cmp);

#define START(node)     ((node)->start)
#define LAST(node)      ((node)->last)

INTERVAL_TREE_DEFINE(struct interval_tree_node, rb, unsigned long,, START,
    LAST,, lkpi_interval_tree)

static void
linux_device_release(struct device *dev)
{
        pr_debug("linux_device_release: %s\n", dev_name(dev));
        kfree(dev);
}

static ssize_t
linux_class_show(struct kobject *kobj, struct attribute *attr, char *buf)
{
        struct class_attribute *dattr;
        ssize_t error;

        dattr = container_of(attr, struct class_attribute, attr);
        error = -EIO;
        if (dattr->show)
                error = dattr->show(container_of(kobj, struct class, kobj),
                    dattr, buf);
        return (error);
}

static ssize_t
linux_class_store(struct kobject *kobj, struct attribute *attr, const char *buf,
    size_t count)
{
        struct class_attribute *dattr;
        ssize_t error;

        dattr = container_of(attr, struct class_attribute, attr);
        error = -EIO;
        if (dattr->store)
                error = dattr->store(container_of(kobj, struct class, kobj),
                    dattr, buf, count);
        return (error);
}

static void
linux_class_release(struct kobject *kobj)
{
        struct class *class;

        class = container_of(kobj, struct class, kobj);
        if (class->class_release)
                class->class_release(class);
}

static const struct sysfs_ops linux_class_sysfs = {
        .show  = linux_class_show,
        .store = linux_class_store,
};

const struct kobj_type linux_class_ktype = {
        .release = linux_class_release,
        .sysfs_ops = &linux_class_sysfs
};

static void
linux_dev_release(struct kobject *kobj)
{
        struct device *dev;

        dev = container_of(kobj, struct device, kobj);
        /* This is the precedence defined by linux. */
        if (dev->release)
                dev->release(dev);
        else if (dev->class && dev->class->dev_release)
                dev->class->dev_release(dev);
}

static ssize_t
linux_dev_show(struct kobject *kobj, struct attribute *attr, char *buf)
{
        struct device_attribute *dattr;
        ssize_t error;

        dattr = container_of(attr, struct device_attribute, attr);
        error = -EIO;
        if (dattr->show)
                error = dattr->show(container_of(kobj, struct device, kobj),
                    dattr, buf);
        return (error);
}

static ssize_t
linux_dev_store(struct kobject *kobj, struct attribute *attr, const char *buf,
    size_t count)
{
        struct device_attribute *dattr;
        ssize_t error;

        dattr = container_of(attr, struct device_attribute, attr);
        error = -EIO;
        if (dattr->store)
                error = dattr->store(container_of(kobj, struct device, kobj),
                    dattr, buf, count);
        return (error);
}

static const struct sysfs_ops linux_dev_sysfs = {
        .show  = linux_dev_show,
        .store = linux_dev_store,
};

const struct kobj_type linux_dev_ktype = {
        .release = linux_dev_release,
        .sysfs_ops = &linux_dev_sysfs
};

struct device *
device_create(struct class *class, struct device *parent, dev_t devt,
    void *drvdata, const char *fmt, ...)
{
        struct device *dev;
        va_list args;

        dev = kzalloc(sizeof(*dev), M_WAITOK);
        dev->parent = parent;
        dev->class = class;
        dev->devt = devt;
        dev->driver_data = drvdata;
        dev->release = linux_device_release;
        va_start(args, fmt);
        kobject_set_name_vargs(&dev->kobj, fmt, args);
        va_end(args);
        device_register(dev);

        return (dev);
}

struct device *
device_create_groups_vargs(struct class *class, struct device *parent,
    dev_t devt, void *drvdata, const struct attribute_group **groups,
    const char *fmt, va_list args)
{
        struct device *dev = NULL;
        int retval = -ENODEV;

        if (class == NULL || IS_ERR(class))
                goto error;

        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
        if (!dev) {
                retval = -ENOMEM;
                goto error;
        }

        dev->devt = devt;
        dev->class = class;
        dev->parent = parent;
        dev->groups = groups;
        dev->release = device_create_release;
        /* device_initialize() needs the class and parent to be set */
        device_initialize(dev);
        dev_set_drvdata(dev, drvdata);

        retval = kobject_set_name_vargs(&dev->kobj, fmt, args);
        if (retval)
                goto error;

        retval = device_add(dev);
        if (retval)
                goto error;

        return dev;

error:
        put_device(dev);
        return ERR_PTR(retval);
}

struct class *
lkpi_class_create(const char *name)
{
        struct class *class;
        int error;

        class = kzalloc(sizeof(*class), M_WAITOK);
        class->name = name;
        class->class_release = linux_class_kfree;
        error = class_register(class);
        if (error) {
                kfree(class);
                return (NULL);
        }

        return (class);
}

static void
linux_kq_lock(void *arg)
{
        spinlock_t *s = arg;

        spin_lock(s);
}
static void
linux_kq_unlock(void *arg)
{
        spinlock_t *s = arg;

        spin_unlock(s);
}

static void
linux_kq_assert_lock(void *arg, int what)
{
#ifdef INVARIANTS
        spinlock_t *s = arg;

        if (what == LA_LOCKED)
                mtx_assert(s, MA_OWNED);
        else
                mtx_assert(s, MA_NOTOWNED);
#endif
}

static void
linux_file_kqfilter_poll(struct linux_file *, int);

struct linux_file *
linux_file_alloc(void)
{
        struct linux_file *filp;

        filp = kzalloc(sizeof(*filp), GFP_KERNEL);

        /* set initial refcount */
        filp->f_count = 1;

        /* setup fields needed by kqueue support */
        spin_lock_init(&filp->f_kqlock);
        knlist_init(&filp->f_selinfo.si_note, &filp->f_kqlock,
            linux_kq_lock, linux_kq_unlock, linux_kq_assert_lock);

        return (filp);
}

void
linux_file_free(struct linux_file *filp)
{
        if (filp->_file == NULL) {
                if (filp->f_op != NULL && filp->f_op->release != NULL)
                        filp->f_op->release(filp->f_vnode, filp);
                if (filp->f_shmem != NULL)
                        vm_object_deallocate(filp->f_shmem);
                kfree_rcu(filp, rcu);
        } else {
                /*
                 * The close method of the character device or file
                 * will free the linux_file structure:
                 */
                _fdrop(filp->_file, curthread);
        }
}

struct linux_cdev *
cdev_alloc(void)
{
        struct linux_cdev *cdev;

        cdev = kzalloc(sizeof(struct linux_cdev), M_WAITOK);
        kobject_init(&cdev->kobj, &linux_cdev_ktype);
        cdev->refs = 1;
        return (cdev);
}

static int
linux_cdev_pager_fault(vm_object_t vm_obj, vm_ooffset_t offset, int prot,
    vm_page_t *mres)
{
        struct vm_area_struct *vmap;

        vmap = linux_cdev_handle_find(vm_obj->handle);

        MPASS(vmap != NULL);
        MPASS(vmap->vm_private_data == vm_obj->handle);

        if (likely(vmap->vm_ops != NULL && offset < vmap->vm_len)) {
                vm_paddr_t paddr = IDX_TO_OFF(vmap->vm_pfn) + offset;
                vm_page_t page;

                if (((*mres)->flags & PG_FICTITIOUS) != 0) {
                        /*
                         * If the passed in result page is a fake
                         * page, update it with the new physical
                         * address.
                         */
                        page = *mres;
                        vm_page_updatefake(page, paddr, vm_obj->memattr);
                } else {
                        /*
                         * Replace the passed in "mres" page with our
                         * own fake page and free up the all of the
                         * original pages.
                         */
                        VM_OBJECT_WUNLOCK(vm_obj);
                        page = vm_page_getfake(paddr, vm_obj->memattr);
                        VM_OBJECT_WLOCK(vm_obj);

                        vm_page_replace(page, vm_obj, (*mres)->pindex, *mres);
                        *mres = page;
                }
                vm_page_valid(page);
                return (VM_PAGER_OK);
        }
        return (VM_PAGER_FAIL);
}

static int
linux_cdev_pager_populate(vm_object_t vm_obj, vm_pindex_t pidx, int fault_type,
    vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last)
{
        struct vm_area_struct *vmap;
        int err;

        /* get VM area structure */
        vmap = linux_cdev_handle_find(vm_obj->handle);
        MPASS(vmap != NULL);
        MPASS(vmap->vm_private_data == vm_obj->handle);

        VM_OBJECT_WUNLOCK(vm_obj);

        linux_set_current(curthread);

        down_write(&vmap->vm_mm->mmap_sem);
        if (unlikely(vmap->vm_ops == NULL)) {
                err = VM_FAULT_SIGBUS;
        } else {
                struct vm_fault vmf;

                /* fill out VM fault structure */
                vmf.virtual_address = (void *)(uintptr_t)IDX_TO_OFF(pidx);
                vmf.flags = (fault_type & VM_PROT_WRITE) ? FAULT_FLAG_WRITE : 0;
                vmf.pgoff = 0;
                vmf.page = NULL;
                vmf.vma = vmap;

                vmap->vm_pfn_count = 0;
                vmap->vm_pfn_pcount = &vmap->vm_pfn_count;
                vmap->vm_obj = vm_obj;

                err = vmap->vm_ops->fault(&vmf);

                while (vmap->vm_pfn_count == 0 && err == VM_FAULT_NOPAGE) {
                        kern_yield(PRI_USER);
                        err = vmap->vm_ops->fault(&vmf);
                }
        }

        /* translate return code */
        switch (err) {
        case VM_FAULT_OOM:
                err = VM_PAGER_AGAIN;
                break;
        case VM_FAULT_SIGBUS:
                err = VM_PAGER_BAD;
                break;
        case VM_FAULT_NOPAGE:
                /*
                 * By contract the fault handler will return having
                 * busied all the pages itself. If pidx is already
                 * found in the object, it will simply xbusy the first
                 * page and return with vm_pfn_count set to 1.
                 */
                *first = vmap->vm_pfn_first;
                *last = *first + vmap->vm_pfn_count - 1;
                err = VM_PAGER_OK;
                break;
        default:
                err = VM_PAGER_ERROR;
                break;
        }
        up_write(&vmap->vm_mm->mmap_sem);
        VM_OBJECT_WLOCK(vm_obj);
        return (err);
}

static struct rwlock linux_vma_lock;
static TAILQ_HEAD(, vm_area_struct) linux_vma_head =
    TAILQ_HEAD_INITIALIZER(linux_vma_head);

static void
linux_cdev_handle_free(struct vm_area_struct *vmap)
{
        /* Drop reference on vm_file */
        if (vmap->vm_file != NULL)
                fput(vmap->vm_file);

        /* Drop reference on mm_struct */
        mmput(vmap->vm_mm);

        kfree(vmap);
}

static void
linux_cdev_handle_remove(struct vm_area_struct *vmap)
{
        rw_wlock(&linux_vma_lock);
        TAILQ_REMOVE(&linux_vma_head, vmap, vm_entry);
        rw_wunlock(&linux_vma_lock);
}

static struct vm_area_struct *
linux_cdev_handle_find(void *handle)
{
        struct vm_area_struct *vmap;

        rw_rlock(&linux_vma_lock);
        TAILQ_FOREACH(vmap, &linux_vma_head, vm_entry) {
                if (vmap->vm_private_data == handle)
                        break;
        }
        rw_runlock(&linux_vma_lock);
        return (vmap);
}

static int
linux_cdev_pager_ctor(void *handle, vm_ooffset_t size, vm_prot_t prot,
                      vm_ooffset_t foff, struct ucred *cred, u_short *color)
{

        MPASS(linux_cdev_handle_find(handle) != NULL);
        *color = 0;
        return (0);
}

static void
linux_cdev_pager_dtor(void *handle)
{
        const struct vm_operations_struct *vm_ops;
        struct vm_area_struct *vmap;

        vmap = linux_cdev_handle_find(handle);
        MPASS(vmap != NULL);

        /*
         * Remove handle before calling close operation to prevent
         * other threads from reusing the handle pointer.
         */
        linux_cdev_handle_remove(vmap);

        down_write(&vmap->vm_mm->mmap_sem);
        vm_ops = vmap->vm_ops;
        if (likely(vm_ops != NULL))
                vm_ops->close(vmap);
        up_write(&vmap->vm_mm->mmap_sem);

        linux_cdev_handle_free(vmap);
}

static struct cdev_pager_ops linux_cdev_pager_ops[2] = {
  {
        /* OBJT_MGTDEVICE */
        .cdev_pg_populate       = linux_cdev_pager_populate,
        .cdev_pg_ctor   = linux_cdev_pager_ctor,
        .cdev_pg_dtor   = linux_cdev_pager_dtor
  },
  {
        /* OBJT_DEVICE */
        .cdev_pg_fault  = linux_cdev_pager_fault,
        .cdev_pg_ctor   = linux_cdev_pager_ctor,
        .cdev_pg_dtor   = linux_cdev_pager_dtor
  },
};

int
zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
    unsigned long size)
{
        struct pctrie_iter pages;
        vm_object_t obj;
        vm_page_t m;

        obj = vma->vm_obj;
        if (obj == NULL || (obj->flags & OBJ_UNMANAGED) != 0)
                return (-ENOTSUP);
        VM_OBJECT_RLOCK(obj);
        vm_page_iter_limit_init(&pages, obj, OFF_TO_IDX(address + size));
        VM_RADIX_FOREACH_FROM(m, &pages, OFF_TO_IDX(address))
                pmap_remove_all(m);
        VM_OBJECT_RUNLOCK(obj);
        return (0);
}

void
vma_set_file(struct vm_area_struct *vma, struct linux_file *file)
{
        struct linux_file *tmp;

        /* Changing an anonymous vma with this is illegal */
        get_file(file);
        tmp = vma->vm_file;
        vma->vm_file = file;
        fput(tmp);
}

static struct file_operations dummy_ldev_ops = {
        /* XXXKIB */
};

static struct linux_cdev dummy_ldev = {
        .ops = &dummy_ldev_ops,
};

#define LDEV_SI_DTR     0x0001
#define LDEV_SI_REF     0x0002

static void
linux_get_fop(struct linux_file *filp, const struct file_operations **fop,
    struct linux_cdev **dev)
{
        struct linux_cdev *ldev;
        u_int siref;

        ldev = filp->f_cdev;
        *fop = filp->f_op;
        if (ldev != NULL) {
                if (ldev->kobj.ktype == &linux_cdev_static_ktype) {
                        refcount_acquire(&ldev->refs);
                } else {
                        for (siref = ldev->siref;;) {
                                if ((siref & LDEV_SI_DTR) != 0) {
                                        ldev = &dummy_ldev;
                                        *fop = ldev->ops;
                                        siref = ldev->siref;
                                        MPASS((ldev->siref & LDEV_SI_DTR) == 0);
                                } else if (atomic_fcmpset_int(&ldev->siref,
                                    &siref, siref + LDEV_SI_REF)) {
                                        break;
                                }
                        }
                }
        }
        *dev = ldev;
}

static void
linux_drop_fop(struct linux_cdev *ldev)
{

        if (ldev == NULL)
                return;
        if (ldev->kobj.ktype == &linux_cdev_static_ktype) {
                linux_cdev_deref(ldev);
        } else {
                MPASS(ldev->kobj.ktype == &linux_cdev_ktype);
                MPASS((ldev->siref & ~LDEV_SI_DTR) != 0);
                atomic_subtract_int(&ldev->siref, LDEV_SI_REF);
        }
}

#define OPW(fp,td,code) ({                      \
        struct file *__fpop;                    \
        __typeof(code) __retval;                \
                                                \
        __fpop = (td)->td_fpop;                 \
        (td)->td_fpop = (fp);                   \
        __retval = (code);                      \
        (td)->td_fpop = __fpop;                 \
        __retval;                               \
})

static int
linux_dev_fdopen(struct cdev *dev, int fflags, struct thread *td,
    struct file *file)
{
        struct linux_cdev *ldev;
        struct linux_file *filp;
        const struct file_operations *fop;
        int error;

        ldev = dev->si_drv1;

        filp = linux_file_alloc();
        filp->f_dentry = &filp->f_dentry_store;
        filp->f_op = ldev->ops;
        filp->f_mode = file->f_flag;
        filp->f_flags = file->f_flag;
        filp->f_vnode = file->f_vnode;
        filp->_file = file;
        refcount_acquire(&ldev->refs);
        filp->f_cdev = ldev;

        linux_set_current(td);
        linux_get_fop(filp, &fop, &ldev);

        if (fop->open != NULL) {
                error = -fop->open(file->f_vnode, filp);
                if (error != 0) {
                        linux_drop_fop(ldev);
                        linux_cdev_deref(filp->f_cdev);
                        kfree(filp);
                        return (error);
                }
        }

        /* hold on to the vnode - used for fstat() */
        vref(filp->f_vnode);

        /* release the file from devfs */
        finit(file, filp->f_mode, DTYPE_DEV, filp, &linuxfileops);
        linux_drop_fop(ldev);
        return (ENXIO);
}

#define LINUX_IOCTL_MIN_PTR 0x10000UL
#define LINUX_IOCTL_MAX_PTR (LINUX_IOCTL_MIN_PTR + IOCPARM_MAX)

static inline int
linux_remap_address(void **uaddr, size_t len)
{
        uintptr_t uaddr_val = (uintptr_t)(*uaddr);

        if (unlikely(uaddr_val >= LINUX_IOCTL_MIN_PTR &&
            uaddr_val < LINUX_IOCTL_MAX_PTR)) {
                struct task_struct *pts = current;
                if (pts == NULL) {
                        *uaddr = NULL;
                        return (1);
                }

                /* compute data offset */
                uaddr_val -= LINUX_IOCTL_MIN_PTR;

                /* check that length is within bounds */
                if ((len > IOCPARM_MAX) ||
                    (uaddr_val + len) > pts->bsd_ioctl_len) {
                        *uaddr = NULL;
                        return (1);
                }

                /* re-add kernel buffer address */
                uaddr_val += (uintptr_t)pts->bsd_ioctl_data;

                /* update address location */
                *uaddr = (void *)uaddr_val;
                return (1);
        }
        return (0);
}

int
linux_copyin(const void *uaddr, void *kaddr, size_t len)
{
        if (linux_remap_address(__DECONST(void **, &uaddr), len)) {
                if (uaddr == NULL)
                        return (-EFAULT);
                memcpy(kaddr, uaddr, len);
                return (0);
        }
        return (-copyin(uaddr, kaddr, len));
}

int
linux_copyout(const void *kaddr, void *uaddr, size_t len)
{
        if (linux_remap_address(&uaddr, len)) {
                if (uaddr == NULL)
                        return (-EFAULT);
                memcpy(uaddr, kaddr, len);
                return (0);
        }
        return (-copyout(kaddr, uaddr, len));
}

size_t
linux_clear_user(void *_uaddr, size_t _len)
{
        uint8_t *uaddr = _uaddr;
        size_t len = _len;

        /* make sure uaddr is aligned before going into the fast loop */
        while (((uintptr_t)uaddr & 7) != 0 && len > 7) {
                if (subyte(uaddr, 0))
                        return (_len);
                uaddr++;
                len--;
        }

        /* zero 8 bytes at a time */
        while (len > 7) {
#ifdef __LP64__
                if (suword64(uaddr, 0))
                        return (_len);
#else
                if (suword32(uaddr, 0))
                        return (_len);
                if (suword32(uaddr + 4, 0))
                        return (_len);
#endif
                uaddr += 8;
                len -= 8;
        }

        /* zero fill end, if any */
        while (len > 0) {
                if (subyte(uaddr, 0))
                        return (_len);
                uaddr++;
                len--;
        }
        return (0);
}

int
linux_access_ok(const void *uaddr, size_t len)
{
        uintptr_t saddr;
        uintptr_t eaddr;

        /* get start and end address */
        saddr = (uintptr_t)uaddr;
        eaddr = (uintptr_t)uaddr + len;

        /* verify addresses are valid for userspace */
        return ((saddr == eaddr) ||
            (eaddr > saddr && eaddr <= VM_MAXUSER_ADDRESS));
}

/*
 * This function should return either EINTR or ERESTART depending on
 * the signal type sent to this thread:
 */
static int
linux_get_error(struct task_struct *task, int error)
{
        /* check for signal type interrupt code */
        if (error == EINTR || error == ERESTARTSYS || error == ERESTART) {
                error = -linux_schedule_get_interrupt_value(task);
                if (error == 0)
                        error = EINTR;
        }
        return (error);
}

static int
linux_file_ioctl_sub(struct file *fp, struct linux_file *filp,
    const struct file_operations *fop, u_long cmd, caddr_t data,
    struct thread *td)
{
        struct task_struct *task = current;
        unsigned size;
        int error;

        size = IOCPARM_LEN(cmd);
        /* refer to logic in sys_ioctl() */
        if (size > 0) {
                /*
                 * Setup hint for linux_copyin() and linux_copyout().
                 *
                 * Background: Linux code expects a user-space address
                 * while FreeBSD supplies a kernel-space address.
                 */
                task->bsd_ioctl_data = data;
                task->bsd_ioctl_len = size;
                data = (void *)LINUX_IOCTL_MIN_PTR;
        } else {
                /* fetch user-space pointer */
                data = *(void **)data;
        }
#ifdef COMPAT_FREEBSD32
        if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) {
                /* try the compat IOCTL handler first */
                if (fop->compat_ioctl != NULL) {
                        error = -OPW(fp, td, fop->compat_ioctl(filp,
                            cmd, (u_long)data));
                } else {
                        error = ENOTTY;
                }

                /* fallback to the regular IOCTL handler, if any */
                if (error == ENOTTY && fop->unlocked_ioctl != NULL) {
                        error = -OPW(fp, td, fop->unlocked_ioctl(filp,
                            cmd, (u_long)data));
                }
        } else
#endif
        {
                if (fop->unlocked_ioctl != NULL) {
                        error = -OPW(fp, td, fop->unlocked_ioctl(filp,
                            cmd, (u_long)data));
                } else {
                        error = ENOTTY;
                }
        }
        if (size > 0) {
                task->bsd_ioctl_data = NULL;
                task->bsd_ioctl_len = 0;
        }

        if (error == EWOULDBLOCK) {
                /* update kqfilter status, if any */
                linux_file_kqfilter_poll(filp,
                    LINUX_KQ_FLAG_HAS_READ | LINUX_KQ_FLAG_HAS_WRITE);
        } else {
                error = linux_get_error(task, error);
        }
        return (error);
}

#define LINUX_POLL_TABLE_NORMAL ((poll_table *)1)

/*
 * This function atomically updates the poll wakeup state and returns
 * the previous state at the time of update.
 */
static uint8_t
linux_poll_wakeup_state(atomic_t *v, const uint8_t *pstate)
{
        int c, old;

        c = v->counter;

        while ((old = atomic_cmpxchg(v, c, pstate[c])) != c)
                c = old;

        return (c);
}

static int
linux_poll_wakeup_callback(wait_queue_t *wq, unsigned int wq_state, int flags, void *key)
{
        static const uint8_t state[LINUX_FWQ_STATE_MAX] = {
                [LINUX_FWQ_STATE_INIT] = LINUX_FWQ_STATE_INIT, /* NOP */
                [LINUX_FWQ_STATE_NOT_READY] = LINUX_FWQ_STATE_NOT_READY, /* NOP */
                [LINUX_FWQ_STATE_QUEUED] = LINUX_FWQ_STATE_READY,
                [LINUX_FWQ_STATE_READY] = LINUX_FWQ_STATE_READY, /* NOP */
        };
        struct linux_file *filp = container_of(wq, struct linux_file, f_wait_queue.wq);

        switch (linux_poll_wakeup_state(&filp->f_wait_queue.state, state)) {
        case LINUX_FWQ_STATE_QUEUED:
                linux_poll_wakeup(filp);
                return (1);
        default:
                return (0);
        }
}

void
linux_poll_wait(struct linux_file *filp, wait_queue_head_t *wqh, poll_table *p)
{
        static const uint8_t state[LINUX_FWQ_STATE_MAX] = {
                [LINUX_FWQ_STATE_INIT] = LINUX_FWQ_STATE_NOT_READY,
                [LINUX_FWQ_STATE_NOT_READY] = LINUX_FWQ_STATE_NOT_READY, /* NOP */
                [LINUX_FWQ_STATE_QUEUED] = LINUX_FWQ_STATE_QUEUED, /* NOP */
                [LINUX_FWQ_STATE_READY] = LINUX_FWQ_STATE_QUEUED,
        };

        /* check if we are called inside the select system call */
        if (p == LINUX_POLL_TABLE_NORMAL)
                selrecord(curthread, &filp->f_selinfo);

        switch (linux_poll_wakeup_state(&filp->f_wait_queue.state, state)) {
        case LINUX_FWQ_STATE_INIT:
                /* NOTE: file handles can only belong to one wait-queue */
                filp->f_wait_queue.wqh = wqh;
                filp->f_wait_queue.wq.func = &linux_poll_wakeup_callback;
                add_wait_queue(wqh, &filp->f_wait_queue.wq);
                atomic_set(&filp->f_wait_queue.state, LINUX_FWQ_STATE_QUEUED);
                break;
        default:
                break;
        }
}

static void
linux_poll_wait_dequeue(struct linux_file *filp)
{
        static const uint8_t state[LINUX_FWQ_STATE_MAX] = {
                [LINUX_FWQ_STATE_INIT] = LINUX_FWQ_STATE_INIT,  /* NOP */
                [LINUX_FWQ_STATE_NOT_READY] = LINUX_FWQ_STATE_INIT,
                [LINUX_FWQ_STATE_QUEUED] = LINUX_FWQ_STATE_INIT,
                [LINUX_FWQ_STATE_READY] = LINUX_FWQ_STATE_INIT,
        };

        seldrain(&filp->f_selinfo);

        switch (linux_poll_wakeup_state(&filp->f_wait_queue.state, state)) {
        case LINUX_FWQ_STATE_NOT_READY:
        case LINUX_FWQ_STATE_QUEUED:
        case LINUX_FWQ_STATE_READY:
                remove_wait_queue(filp->f_wait_queue.wqh, &filp->f_wait_queue.wq);
                break;
        default:
                break;
        }
}

void
linux_poll_wakeup(struct linux_file *filp)
{
        /* this function should be NULL-safe */
        if (filp == NULL)
                return;

        selwakeup(&filp->f_selinfo);

        spin_lock(&filp->f_kqlock);
        filp->f_kqflags |= LINUX_KQ_FLAG_NEED_READ |
            LINUX_KQ_FLAG_NEED_WRITE;

        /* make sure the "knote" gets woken up */
        KNOTE_LOCKED(&filp->f_selinfo.si_note, 1);
        spin_unlock(&filp->f_kqlock);
}

static struct linux_file *
__get_file_rcu(struct linux_file **f)
{
        struct linux_file *file1, *file2;

        file1 = READ_ONCE(*f);
        if (file1 == NULL)
                return (NULL);

        if (!refcount_acquire_if_not_zero(
            file1->_file == NULL ? &file1->f_count : &file1->_file->f_count))
                return (ERR_PTR(-EAGAIN));

        file2 = READ_ONCE(*f);
        if (file2 == file1)
                return (file2);

        fput(file1);
        return (ERR_PTR(-EAGAIN));
}

struct linux_file *
linux_get_file_rcu(struct linux_file **f)
{
        struct linux_file *file1;

        for (;;) {
                file1 = __get_file_rcu(f);
                if (file1 == NULL)
                        return (NULL);

                if (IS_ERR(file1))
                        continue;

                return (file1);
        }
}

struct linux_file *
get_file_active(struct linux_file **f)
{
        struct linux_file *file1;

        rcu_read_lock();
        file1 = __get_file_rcu(f);
        rcu_read_unlock();
        if (IS_ERR(file1))
                file1 = NULL;

        return (file1);
}

static void
linux_file_kqfilter_detach(struct knote *kn)
{
        struct linux_file *filp = kn->kn_hook;

        spin_lock(&filp->f_kqlock);
        knlist_remove(&filp->f_selinfo.si_note, kn, 1);
        spin_unlock(&filp->f_kqlock);
}

static int
linux_file_kqfilter_read_event(struct knote *kn, long hint)
{
        struct linux_file *filp = kn->kn_hook;

        mtx_assert(&filp->f_kqlock, MA_OWNED);

        return ((filp->f_kqflags & LINUX_KQ_FLAG_NEED_READ) ? 1 : 0);
}

static int
linux_file_kqfilter_write_event(struct knote *kn, long hint)
{
        struct linux_file *filp = kn->kn_hook;

        mtx_assert(&filp->f_kqlock, MA_OWNED);

        return ((filp->f_kqflags & LINUX_KQ_FLAG_NEED_WRITE) ? 1 : 0);
}

static const struct filterops linux_dev_kqfiltops_read = {
        .f_isfd = 1,
        .f_detach = linux_file_kqfilter_detach,
        .f_event = linux_file_kqfilter_read_event,
        .f_copy = knote_triv_copy,
};

static const struct filterops linux_dev_kqfiltops_write = {
        .f_isfd = 1,
        .f_detach = linux_file_kqfilter_detach,
        .f_event = linux_file_kqfilter_write_event,
        .f_copy = knote_triv_copy,
};

static void
linux_file_kqfilter_poll(struct linux_file *filp, int kqflags)
{
        struct thread *td;
        const struct file_operations *fop;
        struct linux_cdev *ldev;
        int temp;

        if ((filp->f_kqflags & kqflags) == 0)
                return;

        td = curthread;

        linux_get_fop(filp, &fop, &ldev);
        /* get the latest polling state */
        temp = OPW(filp->_file, td, fop->poll(filp, NULL));
        linux_drop_fop(ldev);

        spin_lock(&filp->f_kqlock);
        /* clear kqflags */
        filp->f_kqflags &= ~(LINUX_KQ_FLAG_NEED_READ |
            LINUX_KQ_FLAG_NEED_WRITE);
        /* update kqflags */
        if ((temp & (POLLIN | POLLOUT)) != 0) {
                if ((temp & POLLIN) != 0)
                        filp->f_kqflags |= LINUX_KQ_FLAG_NEED_READ;
                if ((temp & POLLOUT) != 0)
                        filp->f_kqflags |= LINUX_KQ_FLAG_NEED_WRITE;

                /* make sure the "knote" gets woken up */
                KNOTE_LOCKED(&filp->f_selinfo.si_note, 0);
        }
        spin_unlock(&filp->f_kqlock);
}

static int
linux_file_kqfilter(struct file *file, struct knote *kn)
{
        struct linux_file *filp;
        struct thread *td;
        int error;

        td = curthread;
        filp = (struct linux_file *)file->f_data;
        filp->f_flags = file->f_flag;
        if (filp->f_op->poll == NULL)
                return (EINVAL);

        spin_lock(&filp->f_kqlock);
        switch (kn->kn_filter) {
        case EVFILT_READ:
                filp->f_kqflags |= LINUX_KQ_FLAG_HAS_READ;
                kn->kn_fop = &linux_dev_kqfiltops_read;
                kn->kn_hook = filp;
                knlist_add(&filp->f_selinfo.si_note, kn, 1);
                error = 0;
                break;
        case EVFILT_WRITE:
                filp->f_kqflags |= LINUX_KQ_FLAG_HAS_WRITE;
                kn->kn_fop = &linux_dev_kqfiltops_write;
                kn->kn_hook = filp;
                knlist_add(&filp->f_selinfo.si_note, kn, 1);
                error = 0;
                break;
        default:
                error = EINVAL;
                break;
        }
        spin_unlock(&filp->f_kqlock);

        if (error == 0) {
                linux_set_current(td);

                /* update kqfilter status, if any */
                linux_file_kqfilter_poll(filp,
                    LINUX_KQ_FLAG_HAS_READ | LINUX_KQ_FLAG_HAS_WRITE);
        }
        return (error);
}

static int
linux_file_mmap_single(struct file *fp, const struct file_operations *fop,
    vm_ooffset_t *offset, vm_size_t size, struct vm_object **object,
    int nprot, bool is_shared, struct thread *td)
{
        struct task_struct *task;
        struct vm_area_struct *vmap;
        struct mm_struct *mm;
        struct linux_file *filp;
        vm_memattr_t attr;
        int error;

        filp = (struct linux_file *)fp->f_data;
        filp->f_flags = fp->f_flag;

        if (fop->mmap == NULL)
                return (EOPNOTSUPP);

        linux_set_current(td);

        /*
         * The same VM object might be shared by multiple processes
         * and the mm_struct is usually freed when a process exits.
         *
         * The atomic reference below makes sure the mm_struct is
         * available as long as the vmap is in the linux_vma_head.
         */
        task = current;
        mm = task->mm;
        if (atomic_inc_not_zero(&mm->mm_users) == 0)
                return (EINVAL);

        vmap = kzalloc(sizeof(*vmap), GFP_KERNEL);
        vmap->vm_start = 0;
        vmap->vm_end = size;
        vmap->vm_pgoff = *offset / PAGE_SIZE;
        vmap->vm_pfn = 0;
        vmap->vm_flags = vmap->vm_page_prot = (nprot & VM_PROT_ALL);
        if (is_shared)
                vmap->vm_flags |= VM_SHARED;
        vmap->vm_ops = NULL;
        vmap->vm_file = get_file(filp);
        vmap->vm_mm = mm;

        if (unlikely(down_write_killable(&vmap->vm_mm->mmap_sem))) {
                error = linux_get_error(task, EINTR);
        } else {
                error = -OPW(fp, td, fop->mmap(filp, vmap));
                error = linux_get_error(task, error);
                up_write(&vmap->vm_mm->mmap_sem);
        }

        if (error != 0) {
                linux_cdev_handle_free(vmap);
                return (error);
        }

        attr = pgprot2cachemode(vmap->vm_page_prot);

        if (vmap->vm_ops != NULL) {
                struct vm_area_struct *ptr;
                void *vm_private_data;
                bool vm_no_fault;

                if (vmap->vm_ops->open == NULL ||
                    vmap->vm_ops->close == NULL ||
                    vmap->vm_private_data == NULL) {
                        /* free allocated VM area struct */
                        linux_cdev_handle_free(vmap);
                        return (EINVAL);
                }

                vm_private_data = vmap->vm_private_data;

                rw_wlock(&linux_vma_lock);
                TAILQ_FOREACH(ptr, &linux_vma_head, vm_entry) {
                        if (ptr->vm_private_data == vm_private_data)
                                break;
                }
                /* check if there is an existing VM area struct */
                if (ptr != NULL) {
                        /* check if the VM area structure is invalid */
                        if (ptr->vm_ops == NULL ||
                            ptr->vm_ops->open == NULL ||
                            ptr->vm_ops->close == NULL) {
                                error = ESTALE;
                                vm_no_fault = 1;
                        } else {
                                error = EEXIST;
                                vm_no_fault = (ptr->vm_ops->fault == NULL);
                        }
                } else {
                        /* insert VM area structure into list */
                        TAILQ_INSERT_TAIL(&linux_vma_head, vmap, vm_entry);
                        error = 0;
                        vm_no_fault = (vmap->vm_ops->fault == NULL);
                }
                rw_wunlock(&linux_vma_lock);

                if (error != 0) {
                        /* free allocated VM area struct */
                        linux_cdev_handle_free(vmap);
                        /* check for stale VM area struct */
                        if (error != EEXIST)
                                return (error);
                }

                /* check if there is no fault handler */
                if (vm_no_fault) {
                        *object = cdev_pager_allocate(vm_private_data, OBJT_DEVICE,
                            &linux_cdev_pager_ops[1], size, nprot, *offset,
                            td->td_ucred);
                } else {
                        *object = cdev_pager_allocate(vm_private_data, OBJT_MGTDEVICE,
                            &linux_cdev_pager_ops[0], size, nprot, *offset,
                            td->td_ucred);
                }

                /* check if allocating the VM object failed */
                if (*object == NULL) {
                        if (error == 0) {
                                /* remove VM area struct from list */
                                linux_cdev_handle_remove(vmap);
                                /* free allocated VM area struct */
                                linux_cdev_handle_free(vmap);
                        }
                        return (EINVAL);
                }
        } else {
                struct sglist *sg;

                sg = sglist_alloc(1, M_WAITOK);
                sglist_append_phys(sg,
                    (vm_paddr_t)vmap->vm_pfn << PAGE_SHIFT, vmap->vm_len);

                *object = vm_pager_allocate(OBJT_SG, sg, vmap->vm_len,
                    nprot, 0, td->td_ucred);

                linux_cdev_handle_free(vmap);

                if (*object == NULL) {
                        sglist_free(sg);
                        return (EINVAL);
                }
        }

        if (attr != VM_MEMATTR_DEFAULT) {
                VM_OBJECT_WLOCK(*object);
                vm_object_set_memattr(*object, attr);
                VM_OBJECT_WUNLOCK(*object);
        }
        *offset = 0;
        return (0);
}

struct cdevsw linuxcdevsw = {
        .d_version = D_VERSION,
        .d_fdopen = linux_dev_fdopen,
        .d_name = "lkpidev",
};

static int
linux_file_read(struct file *file, struct uio *uio, struct ucred *active_cred,
    int flags, struct thread *td)
{
        struct linux_file *filp;
        const struct file_operations *fop;
        struct linux_cdev *ldev;
        ssize_t bytes;
        int error;

        error = 0;
        filp = (struct linux_file *)file->f_data;
        filp->f_flags = file->f_flag;
        /* XXX no support for I/O vectors currently */
        if (uio->uio_iovcnt != 1)
                return (EOPNOTSUPP);
        if (uio->uio_resid > DEVFS_IOSIZE_MAX)
                return (EINVAL);
        linux_set_current(td);
        linux_get_fop(filp, &fop, &ldev);
        if (fop->read != NULL) {
                bytes = OPW(file, td, fop->read(filp,
                    uio->uio_iov->iov_base,
                    uio->uio_iov->iov_len, &uio->uio_offset));
                if (bytes >= 0) {
                        uio->uio_iov->iov_base =
                            ((uint8_t *)uio->uio_iov->iov_base) + bytes;
                        uio->uio_iov->iov_len -= bytes;
                        uio->uio_resid -= bytes;
                } else {
                        error = linux_get_error(current, -bytes);
                }
        } else
                error = ENXIO;

        /* update kqfilter status, if any */
        linux_file_kqfilter_poll(filp, LINUX_KQ_FLAG_HAS_READ);
        linux_drop_fop(ldev);

        return (error);
}

static int
linux_file_write(struct file *file, struct uio *uio, struct ucred *active_cred,
    int flags, struct thread *td)
{
        struct linux_file *filp;
        const struct file_operations *fop;
        struct linux_cdev *ldev;
        ssize_t bytes;
        int error;

        filp = (struct linux_file *)file->f_data;
        filp->f_flags = file->f_flag;
        /* XXX no support for I/O vectors currently */
        if (uio->uio_iovcnt != 1)
                return (EOPNOTSUPP);
        if (uio->uio_resid > DEVFS_IOSIZE_MAX)
                return (EINVAL);
        linux_set_current(td);
        linux_get_fop(filp, &fop, &ldev);
        if (fop->write != NULL) {
                bytes = OPW(file, td, fop->write(filp,
                    uio->uio_iov->iov_base,
                    uio->uio_iov->iov_len, &uio->uio_offset));
                if (bytes >= 0) {
                        uio->uio_iov->iov_base =
                            ((uint8_t *)uio->uio_iov->iov_base) + bytes;
                        uio->uio_iov->iov_len -= bytes;
                        uio->uio_resid -= bytes;
                        error = 0;
                } else {
                        error = linux_get_error(current, -bytes);
                }
        } else
                error = ENXIO;

        /* update kqfilter status, if any */
        linux_file_kqfilter_poll(filp, LINUX_KQ_FLAG_HAS_WRITE);

        linux_drop_fop(ldev);

        return (error);
}

static int
linux_file_poll(struct file *file, int events, struct ucred *active_cred,
    struct thread *td)
{
        struct linux_file *filp;
        const struct file_operations *fop;
        struct linux_cdev *ldev;
        int revents;

        filp = (struct linux_file *)file->f_data;
        filp->f_flags = file->f_flag;
        linux_set_current(td);
        linux_get_fop(filp, &fop, &ldev);
        if (fop->poll != NULL) {
                revents = OPW(file, td, fop->poll(filp,
                    LINUX_POLL_TABLE_NORMAL)) & events;
        } else {
                revents = 0;
        }
        linux_drop_fop(ldev);
        return (revents);
}

static int
linux_file_close(struct file *file, struct thread *td)
{
        struct linux_file *filp;
        int (*release)(struct inode *, struct linux_file *);
        const struct file_operations *fop;
        struct linux_cdev *ldev;
        int error;

        filp = (struct linux_file *)file->f_data;

        KASSERT(file_count(filp) == 0,
            ("File refcount(%d) is not zero", file_count(filp)));

        if (td == NULL)
                td = curthread;

        error = 0;
        filp->f_flags = file->f_flag;
        linux_set_current(td);
        linux_poll_wait_dequeue(filp);
        linux_get_fop(filp, &fop, &ldev);
        /*
         * Always use the real release function, if any, to avoid
         * leaking device resources:
         */
        release = filp->f_op->release;
        if (release != NULL)
                error = -OPW(file, td, release(filp->f_vnode, filp));
        funsetown(&filp->f_sigio);
        if (filp->f_vnode != NULL)
                vrele(filp->f_vnode);
        linux_drop_fop(ldev);
        ldev = filp->f_cdev;
        if (ldev != NULL)
                linux_cdev_deref(ldev);
        linux_synchronize_rcu(RCU_TYPE_REGULAR);
        kfree(filp);

        return (error);
}

static int
linux_file_ioctl(struct file *fp, u_long cmd, void *data, struct ucred *cred,
    struct thread *td)
{
        struct linux_file *filp;
        const struct file_operations *fop;
        struct linux_cdev *ldev;
        struct fiodgname_arg *fgn;
        const char *p;
        int error, i;

        error = 0;
        filp = (struct linux_file *)fp->f_data;
        filp->f_flags = fp->f_flag;
        linux_get_fop(filp, &fop, &ldev);

        linux_set_current(td);
        switch (cmd) {
        case FIONBIO:
                break;
        case FIOASYNC:
                if (fop->fasync == NULL)
                        break;
                error = -OPW(fp, td, fop->fasync(0, filp, fp->f_flag & FASYNC));
                break;
        case FIOSETOWN:
                error = fsetown(*(int *)data, &filp->f_sigio);
                if (error == 0) {
                        if (fop->fasync == NULL)
                                break;
                        error = -OPW(fp, td, fop->fasync(0, filp,
                            fp->f_flag & FASYNC));
                }
                break;
        case FIOGETOWN:
                *(int *)data = fgetown(&filp->f_sigio);
                break;
        case FIODGNAME:
#ifdef  COMPAT_FREEBSD32
        case FIODGNAME_32:
#endif
                if (filp->f_cdev == NULL || filp->f_cdev->cdev == NULL) {
                        error = ENXIO;
                        break;
                }
                fgn = data;
                p = devtoname(filp->f_cdev->cdev);
                i = strlen(p) + 1;
                if (i > fgn->len) {
                        error = EINVAL;
                        break;
                }
                error = copyout(p, fiodgname_buf_get_ptr(fgn, cmd), i);
                break;
        default:
                error = linux_file_ioctl_sub(fp, filp, fop, cmd, data, td);
                break;
        }
        linux_drop_fop(ldev);
        return (error);
}

static int
linux_file_mmap_sub(struct thread *td, vm_size_t objsize, vm_prot_t prot,
    vm_prot_t maxprot, int flags, struct file *fp,
    vm_ooffset_t *foff, const struct file_operations *fop, vm_object_t *objp)
{
        /*
         * Character devices do not provide private mappings
         * of any kind:
         */
        if ((maxprot & VM_PROT_WRITE) == 0 &&
            (prot & VM_PROT_WRITE) != 0)
                return (EACCES);
        if ((flags & (MAP_PRIVATE | MAP_COPY)) != 0)
                return (EINVAL);

        return (linux_file_mmap_single(fp, fop, foff, objsize, objp,
            (int)prot, (flags & MAP_SHARED) ? true : false, td));
}

static int
linux_file_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t size,
    vm_prot_t prot, vm_prot_t cap_maxprot, int flags, vm_ooffset_t foff,
    struct thread *td)
{
        struct linux_file *filp;
        const struct file_operations *fop;
        struct linux_cdev *ldev;
        struct mount *mp;
        struct vnode *vp;
        vm_object_t object;
        vm_prot_t maxprot;
        int error;

        filp = (struct linux_file *)fp->f_data;

        vp = filp->f_vnode;
        if (vp == NULL)
                return (EOPNOTSUPP);

        /*
         * Ensure that file and memory protections are
         * compatible.
         */
        mp = vp->v_mount;
        if (mp != NULL && (mp->mnt_flag & MNT_NOEXEC) != 0) {
                maxprot = VM_PROT_NONE;
                if ((prot & VM_PROT_EXECUTE) != 0)
                        return (EACCES);
        } else
                maxprot = VM_PROT_EXECUTE;
        if ((fp->f_flag & FREAD) != 0)
                maxprot |= VM_PROT_READ;
        else if ((prot & VM_PROT_READ) != 0)
                return (EACCES);

        /*
         * If we are sharing potential changes via MAP_SHARED and we
         * are trying to get write permission although we opened it
         * without asking for it, bail out.
         *
         * Note that most character devices always share mappings.
         *
         * Rely on linux_file_mmap_sub() to fail invalid MAP_PRIVATE
         * requests rather than doing it here.
         */
        if ((flags & MAP_SHARED) != 0) {
                if ((fp->f_flag & FWRITE) != 0)
                        maxprot |= VM_PROT_WRITE;
                else if ((prot & VM_PROT_WRITE) != 0)
                        return (EACCES);
        }
        maxprot &= cap_maxprot;

        linux_get_fop(filp, &fop, &ldev);
        error = linux_file_mmap_sub(td, size, prot, maxprot, flags, fp,
            &foff, fop, &object);
        if (error != 0)
                goto out;

        error = vm_mmap_object(map, addr, size, prot, maxprot, flags, object,
            foff, FALSE, td);
        if (error != 0)
                vm_object_deallocate(object);
out:
        linux_drop_fop(ldev);
        return (error);
}

static int
linux_file_stat(struct file *fp, struct stat *sb, struct ucred *active_cred)
{
        struct linux_file *filp;
        struct vnode *vp;
        int error;

        filp = (struct linux_file *)fp->f_data;
        if (filp->f_vnode == NULL)
                return (EOPNOTSUPP);

        vp = filp->f_vnode;

        vn_lock(vp, LK_SHARED | LK_RETRY);
        error = VOP_STAT(vp, sb, curthread->td_ucred, NOCRED);
        VOP_UNLOCK(vp);

        return (error);
}

static int
linux_file_fill_kinfo(struct file *fp, struct kinfo_file *kif,
    struct filedesc *fdp)
{
        struct linux_file *filp;
        struct vnode *vp;
        int error;

        filp = fp->f_data;
        vp = filp->f_vnode;
        if (vp == NULL) {
                error = 0;
                kif->kf_type = KF_TYPE_DEV;
        } else {
                vref(vp);
                FILEDESC_SUNLOCK(fdp);
                error = vn_fill_kinfo_vnode(vp, kif);
                vrele(vp);
                kif->kf_type = KF_TYPE_VNODE;
                FILEDESC_SLOCK(fdp);
        }
        return (error);
}

unsigned int
linux_iminor(struct inode *inode)
{
        struct linux_cdev *ldev;

        if (inode == NULL || inode->v_rdev == NULL ||
            inode->v_rdev->si_devsw != &linuxcdevsw)
                return (-1U);
        ldev = inode->v_rdev->si_drv1;
        if (ldev == NULL)
                return (-1U);

        return (minor(ldev->dev));
}

static int
linux_file_kcmp(struct file *fp1, struct file *fp2, struct thread *td)
{
        struct linux_file *filp1, *filp2;

        if (fp2->f_type != DTYPE_DEV)
                return (3);

        filp1 = fp1->f_data;
        filp2 = fp2->f_data;
        return (kcmp_cmp((uintptr_t)filp1->f_cdev, (uintptr_t)filp2->f_cdev));
}

const struct fileops linuxfileops = {
        .fo_read = linux_file_read,
        .fo_write = linux_file_write,
        .fo_truncate = invfo_truncate,
        .fo_kqfilter = linux_file_kqfilter,
        .fo_stat = linux_file_stat,
        .fo_fill_kinfo = linux_file_fill_kinfo,
        .fo_poll = linux_file_poll,
        .fo_close = linux_file_close,
        .fo_ioctl = linux_file_ioctl,
        .fo_mmap = linux_file_mmap,
        .fo_chmod = invfo_chmod,
        .fo_chown = invfo_chown,
        .fo_sendfile = invfo_sendfile,
        .fo_cmp = linux_file_kcmp,
        .fo_flags = DFLAG_PASSABLE,
};

static char *
devm_kvasprintf(struct device *dev, gfp_t gfp, const char *fmt, va_list ap)
{
        unsigned int len;
        char *p;
        va_list aq;

        va_copy(aq, ap);
        len = vsnprintf(NULL, 0, fmt, aq);
        va_end(aq);

        if (dev != NULL)
                p = devm_kmalloc(dev, len + 1, gfp);
        else
                p = kmalloc(len + 1, gfp);
        if (p != NULL)
                vsnprintf(p, len + 1, fmt, ap);

        return (p);
}

char *
kvasprintf(gfp_t gfp, const char *fmt, va_list ap)
{

        return (devm_kvasprintf(NULL, gfp, fmt, ap));
}

char *
lkpi_devm_kasprintf(struct device *dev, gfp_t gfp, const char *fmt, ...)
{
        va_list ap;
        char *p;

        va_start(ap, fmt);
        p = devm_kvasprintf(dev, gfp, fmt, ap);
        va_end(ap);

        return (p);
}

char *
kasprintf(gfp_t gfp, const char *fmt, ...)
{
        va_list ap;
        char *p;

        va_start(ap, fmt);
        p = kvasprintf(gfp, fmt, ap);
        va_end(ap);

        return (p);
}

int
__lkpi_hexdump_printf(void *arg1 __unused, const char *fmt, ...)
{
        va_list ap;
        int result;

        va_start(ap, fmt);
        result = vprintf(fmt, ap);
        va_end(ap);
        return (result);
}

int
__lkpi_hexdump_sbuf_printf(void *arg1, const char *fmt, ...)
{
        va_list ap;
        int result;

        va_start(ap, fmt);
        result = sbuf_vprintf(arg1, fmt, ap);
        va_end(ap);
        return (result);
}

void
lkpi_hex_dump(int(*_fpf)(void *, const char *, ...), void *arg1,
    const char *level, const char *prefix_str,
    const int prefix_type, const int rowsize, const int groupsize,
    const void *buf, size_t len, const bool ascii, const bool trailing_newline)
{
        typedef const struct { long long value; } __packed *print_64p_t;
        typedef const struct { uint32_t value; } __packed *print_32p_t;
        typedef const struct { uint16_t value; } __packed *print_16p_t;
        const void *buf_old = buf;
        int row, linelen, ret;

        while (len > 0) {
                linelen = 0;
                if (level != NULL) {
                        ret = _fpf(arg1, "%s", level);
                        if (ret < 0)
                                break;
                        linelen += ret;
                }
                if (prefix_str != NULL) {
                        ret = _fpf(
                            arg1, "%s%s", linelen ? " " : "", prefix_str);
                        if (ret < 0)
                                break;
                        linelen += ret;
                }

                switch (prefix_type) {
                case DUMP_PREFIX_ADDRESS:
                        ret = _fpf(
                            arg1, "%s[%p]", linelen ? " " : "", buf);
                        if (ret < 0)
                                return;
                        linelen += ret;
                        break;
                case DUMP_PREFIX_OFFSET:
                        ret = _fpf(
                            arg1, "%s[%#tx]", linelen ? " " : "",
                            ((const char *)buf - (const char *)buf_old));
                        if (ret < 0)
                                return;
                        linelen += ret;
                        break;
                default:
                        break;
                }
                for (row = 0; row != rowsize; row++) {
                        if (groupsize == 8 && len > 7) {
                                ret = _fpf(
                                    arg1, "%s%016llx", linelen ? " " : "",
                                    ((print_64p_t)buf)->value);
                                if (ret < 0)
                                        return;
                                linelen += ret;
                                buf = (const uint8_t *)buf + 8;
                                len -= 8;
                        } else if (groupsize == 4 && len > 3) {
                                ret = _fpf(
                                    arg1, "%s%08x", linelen ? " " : "",
                                    ((print_32p_t)buf)->value);
                                if (ret < 0)
                                        return;
                                linelen += ret;
                                buf = (const uint8_t *)buf + 4;
                                len -= 4;
                        } else if (groupsize == 2 && len > 1) {
                                ret = _fpf(
                                    arg1, "%s%04x", linelen ? " " : "",
                                    ((print_16p_t)buf)->value);
                                if (ret < 0)
                                        return;
                                linelen += ret;
                                buf = (const uint8_t *)buf + 2;
                                len -= 2;
                        } else if (len > 0) {
                                ret = _fpf(
                                    arg1, "%s%02x", linelen ? " " : "",
                                    *(const uint8_t *)buf);
                                if (ret < 0)
                                        return;
                                linelen += ret;
                                buf = (const uint8_t *)buf + 1;
                                len--;
                        } else {
                                break;
                        }
                }
                if (len > 0 && trailing_newline) {
                        ret = _fpf(arg1, "\n");
                        if (ret < 0)
                                break;
                }
        }
}

struct hdtb_context {
        char    *linebuf;
        size_t   linebuflen;
        int      written;
};

static int
hdtb_cb(void *arg, const char *format, ...)
{
        struct hdtb_context *context;
        int written;
        va_list args;

        context = arg;

        va_start(args, format);
        written = vsnprintf(
            context->linebuf, context->linebuflen, format, args);
        va_end(args);

        if (written < 0)
                return (written);

        /*
         * Linux' hex_dump_to_buffer() function has the same behaviour as
         * snprintf() basically. Therefore, it returns the number of bytes it
         * would have written if the destination buffer was large enough.
         *
         * If the destination buffer was exhausted, lkpi_hex_dump() will
         * continue to call this callback but it will only compute the bytes it
         * would have written but write nothing to that buffer.
         */
        context->written += written;

        if (written < context->linebuflen) {
                context->linebuf += written;
                context->linebuflen -= written;
        } else {
                context->linebuf += context->linebuflen;
                context->linebuflen = 0;
        }

        return (written);
}

int
lkpi_hex_dump_to_buffer(const void *buf, size_t len, int rowsize,
    int groupsize, char *linebuf, size_t linebuflen, bool ascii)
{
        int written;
        struct hdtb_context context;

        context.linebuf = linebuf;
        context.linebuflen = linebuflen;
        context.written = 0;

        if (rowsize != 16 && rowsize != 32)
                rowsize = 16;

        len = min(len, rowsize);

        lkpi_hex_dump(
            hdtb_cb, &context, NULL, NULL, DUMP_PREFIX_NONE,
            rowsize, groupsize, buf, len, ascii, false);

        written = context.written;

        return (written);
}

static void
linux_timer_callback_wrapper(void *context)
{
        struct timer_list *timer;

        timer = context;

        /* the timer is about to be shutdown permanently */
        if (timer->function == NULL)
                return;

        if (linux_set_current_flags(curthread, M_NOWAIT)) {
                /* try again later */
                callout_reset(&timer->callout, 1,
                    &linux_timer_callback_wrapper, timer);
                return;
        }

        timer->function(timer->data);
}

static int
linux_timer_jiffies_until(unsigned long expires)
{
        unsigned long delta = expires - jiffies;

        /*
         * Guard against already expired values and make sure that the value can
         * be used as a tick count, rather than a jiffies count.
         */
        if ((long)delta < 1)
                delta = 1;
        else if (delta > INT_MAX)
                delta = INT_MAX;
        return ((int)delta);
}

int
mod_timer(struct timer_list *timer, unsigned long expires)
{
        int ret;

        timer->expires = expires;
        ret = callout_reset(&timer->callout,
            linux_timer_jiffies_until(expires),
            &linux_timer_callback_wrapper, timer);

        MPASS(ret == 0 || ret == 1);

        return (ret == 1);
}

void
add_timer(struct timer_list *timer)
{

        callout_reset(&timer->callout,
            linux_timer_jiffies_until(timer->expires),
            &linux_timer_callback_wrapper, timer);
}

void
add_timer_on(struct timer_list *timer, int cpu)
{

        callout_reset_on(&timer->callout,
            linux_timer_jiffies_until(timer->expires),
            &linux_timer_callback_wrapper, timer, cpu);
}

int
timer_delete(struct timer_list *timer)
{

        if (callout_stop(&(timer)->callout) == -1)
                return (0);
        return (1);
}

int
timer_delete_sync(struct timer_list *timer)
{

        if (callout_drain(&(timer)->callout) == -1)
                return (0);
        return (1);
}

int
timer_shutdown_sync(struct timer_list *timer)
{

        timer->function = NULL;
        return (del_timer_sync(timer));
}

/* greatest common divisor, Euclid equation */
static uint64_t
lkpi_gcd_64(uint64_t a, uint64_t b)
{
        uint64_t an;
        uint64_t bn;

        while (b != 0) {
                an = b;
                bn = a % b;
                a = an;
                b = bn;
        }
        return (a);
}

uint64_t lkpi_nsec2hz_rem;
uint64_t lkpi_nsec2hz_div = 1000000000ULL;
uint64_t lkpi_nsec2hz_max;

uint64_t lkpi_usec2hz_rem;
uint64_t lkpi_usec2hz_div = 1000000ULL;
uint64_t lkpi_usec2hz_max;

uint64_t lkpi_msec2hz_rem;
uint64_t lkpi_msec2hz_div = 1000ULL;
uint64_t lkpi_msec2hz_max;

static void
linux_timer_init(void *arg)
{
        uint64_t gcd;

        /*
         * Compute an internal HZ value which can divide 2**32 to
         * avoid timer rounding problems when the tick value wraps
         * around 2**32:
         */
        linux_timer_hz_mask = 1;
        while (linux_timer_hz_mask < (unsigned long)hz)
                linux_timer_hz_mask *= 2;
        linux_timer_hz_mask--;

        /* compute some internal constants */

        lkpi_nsec2hz_rem = hz;
        lkpi_usec2hz_rem = hz;
        lkpi_msec2hz_rem = hz;

        gcd = lkpi_gcd_64(lkpi_nsec2hz_rem, lkpi_nsec2hz_div);
        lkpi_nsec2hz_rem /= gcd;
        lkpi_nsec2hz_div /= gcd;
        lkpi_nsec2hz_max = -1ULL / lkpi_nsec2hz_rem;

        gcd = lkpi_gcd_64(lkpi_usec2hz_rem, lkpi_usec2hz_div);
        lkpi_usec2hz_rem /= gcd;
        lkpi_usec2hz_div /= gcd;
        lkpi_usec2hz_max = -1ULL / lkpi_usec2hz_rem;

        gcd = lkpi_gcd_64(lkpi_msec2hz_rem, lkpi_msec2hz_div);
        lkpi_msec2hz_rem /= gcd;
        lkpi_msec2hz_div /= gcd;
        lkpi_msec2hz_max = -1ULL / lkpi_msec2hz_rem;
}
SYSINIT(linux_timer, SI_SUB_DRIVERS, SI_ORDER_FIRST, linux_timer_init, NULL);

void
linux_complete_common(struct completion *c, int all)
{
        sleepq_lock(c);
        if (all) {
                c->done = UINT_MAX;
                sleepq_broadcast(c, SLEEPQ_SLEEP, 0, 0);
        } else {
                if (c->done != UINT_MAX)
                        c->done++;
                sleepq_signal(c, SLEEPQ_SLEEP, 0, 0);
        }
        sleepq_release(c);
}

/*
 * Indefinite wait for done != 0 with or without signals.
 */
int
linux_wait_for_common(struct completion *c, int flags)
{
        struct task_struct *task;
        int error;

        if (SCHEDULER_STOPPED())
                return (0);

        task = current;

        if (flags != 0)
                flags = SLEEPQ_INTERRUPTIBLE | SLEEPQ_SLEEP;
        else
                flags = SLEEPQ_SLEEP;
        error = 0;
        for (;;) {
                sleepq_lock(c);
                if (c->done)
                        break;
                sleepq_add(c, NULL, "completion", flags, 0);
                if (flags & SLEEPQ_INTERRUPTIBLE) {
                        DROP_GIANT();
                        error = -sleepq_wait_sig(c, 0);
                        PICKUP_GIANT();
                        if (error != 0) {
                                linux_schedule_save_interrupt_value(task, error);
                                error = -ERESTARTSYS;
                                goto intr;
                        }
                } else {
                        DROP_GIANT();
                        sleepq_wait(c, 0);
                        PICKUP_GIANT();
                }
        }
        if (c->done != UINT_MAX)
                c->done--;
        sleepq_release(c);

intr:
        return (error);
}

/*
 * Time limited wait for done != 0 with or without signals.
 */
unsigned long
linux_wait_for_timeout_common(struct completion *c, unsigned long timeout,
    int flags)
{
        struct task_struct *task;
        unsigned long end = jiffies + timeout, error;

        if (SCHEDULER_STOPPED())
                return (0);

        task = current;

        if (flags != 0)
                flags = SLEEPQ_INTERRUPTIBLE | SLEEPQ_SLEEP;
        else
                flags = SLEEPQ_SLEEP;

        for (;;) {
                sleepq_lock(c);
                if (c->done)
                        break;
                sleepq_add(c, NULL, "completion", flags, 0);
                sleepq_set_timeout(c, linux_timer_jiffies_until(end));

                DROP_GIANT();
                if (flags & SLEEPQ_INTERRUPTIBLE)
                        error = -sleepq_timedwait_sig(c, 0);
                else
                        error = -sleepq_timedwait(c, 0);
                PICKUP_GIANT();

                if (error != 0) {
                        /* check for timeout */
                        if (error == -EWOULDBLOCK) {
                                error = 0;      /* timeout */
                        } else {
                                /* signal happened */
                                linux_schedule_save_interrupt_value(task, error);
                                error = -ERESTARTSYS;
                        }
                        goto done;
                }
        }
        if (c->done != UINT_MAX)
                c->done--;
        sleepq_release(c);

        /* return how many jiffies are left */
        error = linux_timer_jiffies_until(end);
done:
        return (error);
}

int
linux_try_wait_for_completion(struct completion *c)
{
        int isdone;

        sleepq_lock(c);
        isdone = (c->done != 0);
        if (c->done != 0 && c->done != UINT_MAX)
                c->done--;
        sleepq_release(c);
        return (isdone);
}

int
linux_completion_done(struct completion *c)
{
        int isdone;

        sleepq_lock(c);
        isdone = (c->done != 0);
        sleepq_release(c);
        return (isdone);
}

static void
linux_cdev_deref(struct linux_cdev *ldev)
{
        if (refcount_release(&ldev->refs) &&
            ldev->kobj.ktype == &linux_cdev_ktype)
                kfree(ldev);
}

static void
linux_cdev_release(struct kobject *kobj)
{
        struct linux_cdev *cdev;
        struct kobject *parent;

        cdev = container_of(kobj, struct linux_cdev, kobj);
        parent = kobj->parent;
        linux_destroy_dev(cdev);
        linux_cdev_deref(cdev);
        kobject_put(parent);
}

static void
linux_cdev_static_release(struct kobject *kobj)
{
        struct cdev *cdev;
        struct linux_cdev *ldev;

        ldev = container_of(kobj, struct linux_cdev, kobj);
        cdev = ldev->cdev;
        if (cdev != NULL) {
                destroy_dev(cdev);
                ldev->cdev = NULL;
        }
        kobject_put(kobj->parent);
}

int
linux_cdev_device_add(struct linux_cdev *ldev, struct device *dev)
{
        int ret;

        if (dev->devt != 0) {
                /* Set parent kernel object. */
                ldev->kobj.parent = &dev->kobj;

                /*
                 * Unlike Linux we require the kobject of the
                 * character device structure to have a valid name
                 * before calling this function:
                 */
                if (ldev->kobj.name == NULL)
                        return (-EINVAL);

                ret = cdev_add(ldev, dev->devt, 1);
                if (ret)
                        return (ret);
        }
        ret = device_add(dev);
        if (ret != 0 && dev->devt != 0)
                cdev_del(ldev);
        return (ret);
}

void
linux_cdev_device_del(struct linux_cdev *ldev, struct device *dev)
{
        device_del(dev);

        if (dev->devt != 0)
                cdev_del(ldev);
}

static void
linux_destroy_dev(struct linux_cdev *ldev)
{

        if (ldev->cdev == NULL)
                return;

        MPASS((ldev->siref & LDEV_SI_DTR) == 0);
        MPASS(ldev->kobj.ktype == &linux_cdev_ktype);

        atomic_set_int(&ldev->siref, LDEV_SI_DTR);
        while ((atomic_load_int(&ldev->siref) & ~LDEV_SI_DTR) != 0)
                pause("ldevdtr", hz / 4);

        destroy_dev(ldev->cdev);
        ldev->cdev = NULL;
}

const struct kobj_type linux_cdev_ktype = {
        .release = linux_cdev_release,
};

const struct kobj_type linux_cdev_static_ktype = {
        .release = linux_cdev_static_release,
};

static void
linux_handle_ifnet_link_event(void *arg, struct ifnet *ifp, int linkstate)
{
        struct notifier_block *nb;
        struct netdev_notifier_info ni;

        nb = arg;
        ni.ifp = ifp;
        ni.dev = (struct net_device *)ifp;
        if (linkstate == LINK_STATE_UP)
                nb->notifier_call(nb, NETDEV_UP, &ni);
        else
                nb->notifier_call(nb, NETDEV_DOWN, &ni);
}

static void
linux_handle_ifnet_arrival_event(void *arg, struct ifnet *ifp)
{
        struct notifier_block *nb;
        struct netdev_notifier_info ni;

        nb = arg;
        ni.ifp = ifp;
        ni.dev = (struct net_device *)ifp;
        nb->notifier_call(nb, NETDEV_REGISTER, &ni);
}

static void
linux_handle_ifnet_departure_event(void *arg, struct ifnet *ifp)
{
        struct notifier_block *nb;
        struct netdev_notifier_info ni;

        nb = arg;
        ni.ifp = ifp;
        ni.dev = (struct net_device *)ifp;
        nb->notifier_call(nb, NETDEV_UNREGISTER, &ni);
}

static void
linux_handle_iflladdr_event(void *arg, struct ifnet *ifp)
{
        struct notifier_block *nb;
        struct netdev_notifier_info ni;

        nb = arg;
        ni.ifp = ifp;
        ni.dev = (struct net_device *)ifp;
        nb->notifier_call(nb, NETDEV_CHANGEADDR, &ni);
}

static void
linux_handle_ifaddr_event(void *arg, struct ifnet *ifp)
{
        struct notifier_block *nb;
        struct netdev_notifier_info ni;

        nb = arg;
        ni.ifp = ifp;
        ni.dev = (struct net_device *)ifp;
        nb->notifier_call(nb, NETDEV_CHANGEIFADDR, &ni);
}

int
register_netdevice_notifier(struct notifier_block *nb)
{

        nb->tags[NETDEV_UP] = EVENTHANDLER_REGISTER(
            ifnet_link_event, linux_handle_ifnet_link_event, nb, 0);
        nb->tags[NETDEV_REGISTER] = EVENTHANDLER_REGISTER(
            ifnet_arrival_event, linux_handle_ifnet_arrival_event, nb, 0);
        nb->tags[NETDEV_UNREGISTER] = EVENTHANDLER_REGISTER(
            ifnet_departure_event, linux_handle_ifnet_departure_event, nb, 0);
        nb->tags[NETDEV_CHANGEADDR] = EVENTHANDLER_REGISTER(
            iflladdr_event, linux_handle_iflladdr_event, nb, 0);

        return (0);
}

int
register_inetaddr_notifier(struct notifier_block *nb)
{

        nb->tags[NETDEV_CHANGEIFADDR] = EVENTHANDLER_REGISTER(
            ifaddr_event, linux_handle_ifaddr_event, nb, 0);
        return (0);
}

int
unregister_netdevice_notifier(struct notifier_block *nb)
{

        EVENTHANDLER_DEREGISTER(ifnet_link_event,
            nb->tags[NETDEV_UP]);
        EVENTHANDLER_DEREGISTER(ifnet_arrival_event,
            nb->tags[NETDEV_REGISTER]);
        EVENTHANDLER_DEREGISTER(ifnet_departure_event,
            nb->tags[NETDEV_UNREGISTER]);
        EVENTHANDLER_DEREGISTER(iflladdr_event,
            nb->tags[NETDEV_CHANGEADDR]);

        return (0);
}

int
unregister_inetaddr_notifier(struct notifier_block *nb)
{

        EVENTHANDLER_DEREGISTER(ifaddr_event,
            nb->tags[NETDEV_CHANGEIFADDR]);

        return (0);
}

struct list_sort_thunk {
        int (*cmp)(void *, struct list_head *, struct list_head *);
        void *priv;
};

static inline int
linux_le_cmp(const void *d1, const void *d2, void *priv)
{
        struct list_head *le1, *le2;
        struct list_sort_thunk *thunk;

        thunk = priv;
        le1 = *(__DECONST(struct list_head **, d1));
        le2 = *(__DECONST(struct list_head **, d2));
        return ((thunk->cmp)(thunk->priv, le1, le2));
}

void
list_sort(void *priv, struct list_head *head, int (*cmp)(void *priv,
    struct list_head *a, struct list_head *b))
{
        struct list_sort_thunk thunk;
        struct list_head **ar, *le;
        size_t count, i;

        count = 0;
        list_for_each(le, head)
                count++;
        ar = malloc(sizeof(struct list_head *) * count, M_KMALLOC, M_WAITOK);
        i = 0;
        list_for_each(le, head)
                ar[i++] = le;
        thunk.cmp = cmp;
        thunk.priv = priv;
        qsort_r(ar, count, sizeof(struct list_head *), linux_le_cmp, &thunk);
        INIT_LIST_HEAD(head);
        for (i = 0; i < count; i++)
                list_add_tail(ar[i], head);
        free(ar, M_KMALLOC);
}

#if defined(__i386__) || defined(__amd64__)
int
linux_wbinvd_on_all_cpus(void)
{

        pmap_invalidate_cache();
        return (0);
}
#endif

int
linux_on_each_cpu(void callback(void *), void *data)
{

        smp_rendezvous(smp_no_rendezvous_barrier, callback,
            smp_no_rendezvous_barrier, data);
        return (0);
}

int
linux_in_atomic(void)
{

        return ((curthread->td_pflags & TDP_NOFAULTING) != 0);
}

struct linux_cdev *
linux_find_cdev(const char *name, unsigned major, unsigned minor)
{
        dev_t dev = MKDEV(major, minor);
        struct cdev *cdev;

        dev_lock();
        LIST_FOREACH(cdev, &linuxcdevsw.d_devs, si_list) {
                struct linux_cdev *ldev = cdev->si_drv1;
                if (ldev->dev == dev &&
                    strcmp(kobject_name(&ldev->kobj), name) == 0) {
                        break;
                }
        }
        dev_unlock();

        return (cdev != NULL ? cdev->si_drv1 : NULL);
}

int
__register_chrdev(unsigned int major, unsigned int baseminor,
    unsigned int count, const char *name,
    const struct file_operations *fops)
{
        struct linux_cdev *cdev;
        int ret = 0;
        int i;

        for (i = baseminor; i < baseminor + count; i++) {
                cdev = cdev_alloc();
                cdev->ops = fops;
                kobject_set_name(&cdev->kobj, name);

                ret = cdev_add(cdev, makedev(major, i), 1);
                if (ret != 0)
                        break;
        }
        return (ret);
}

int
__register_chrdev_p(unsigned int major, unsigned int baseminor,
    unsigned int count, const char *name,
    const struct file_operations *fops, uid_t uid,
    gid_t gid, int mode)
{
        struct linux_cdev *cdev;
        int ret = 0;
        int i;

        for (i = baseminor; i < baseminor + count; i++) {
                cdev = cdev_alloc();
                cdev->ops = fops;
                kobject_set_name(&cdev->kobj, name);

                ret = cdev_add_ext(cdev, makedev(major, i), uid, gid, mode);
                if (ret != 0)
                        break;
        }
        return (ret);
}

void
__unregister_chrdev(unsigned int major, unsigned int baseminor,
    unsigned int count, const char *name)
{
        struct linux_cdev *cdevp;
        int i;

        for (i = baseminor; i < baseminor + count; i++) {
                cdevp = linux_find_cdev(name, major, i);
                if (cdevp != NULL)
                        cdev_del(cdevp);
        }
}

void
linux_dump_stack(void)
{
#ifdef STACK
        struct stack st;

        stack_save(&st);
        stack_print(&st);
#endif
}

int
linuxkpi_net_ratelimit(void)
{

        return (ppsratecheck(&lkpi_net_lastlog, &lkpi_net_curpps,
           lkpi_net_maxpps));
}

struct io_mapping *
io_mapping_create_wc(resource_size_t base, unsigned long size)
{
        struct io_mapping *mapping;

        mapping = kmalloc(sizeof(*mapping), GFP_KERNEL);
        if (mapping == NULL)
                return (NULL);
        return (io_mapping_init_wc(mapping, base, size));
}

/* We likely want a linuxkpi_device.c at some point. */
bool
device_can_wakeup(struct device *dev)
{

        if (dev == NULL)
                return (false);
        /*
         * XXX-BZ iwlwifi queries it as part of enabling WoWLAN.
         * Normally this would be based on a bool in dev->power.XXX.
         * Check such as PCI PCIM_PCAP_*PME.  We have no way to enable this yet.
         * We may get away by directly calling into bsddev for as long as
         * we can assume PCI only avoiding changing struct device breaking KBI.
         */
        pr_debug("%s:%d: not enabled; see comment.\n", __func__, __LINE__);
        return (false);
}

static void
devm_device_group_remove(struct device *dev, void *p)
{
        const struct attribute_group **dr = p;
        const struct attribute_group *group = *dr;

        sysfs_remove_group(&dev->kobj, group);
}

int
lkpi_devm_device_add_group(struct device *dev,
    const struct attribute_group *group)
{
        const struct attribute_group **dr;
        int ret;

        dr = devres_alloc(devm_device_group_remove, sizeof(*dr), GFP_KERNEL);
        if (dr == NULL)
                return (-ENOMEM);

        ret = sysfs_create_group(&dev->kobj, group);
        if (ret == 0) {
                *dr = group;
                devres_add(dev, dr);
        } else
                devres_free(dr);

        return (ret);
}

#if defined(__i386__) || defined(__amd64__)
bool linux_cpu_has_clflush;
struct cpuinfo_x86 boot_cpu_data;
struct cpuinfo_x86 *__cpu_data;
#endif

cpumask_t *
lkpi_get_static_single_cpu_mask(int cpuid)
{

        KASSERT((cpuid >= 0 && cpuid <= mp_maxid), ("%s: invalid cpuid %d\n",
            __func__, cpuid));
        KASSERT(!CPU_ABSENT(cpuid), ("%s: cpu with cpuid %d is absent\n",
            __func__, cpuid));

        return (static_single_cpu_mask[cpuid]);
}

bool
lkpi_xen_initial_domain(void)
{
#ifdef XENHVM
        return (xen_initial_domain());
#else
        return (false);
#endif
}

bool
lkpi_xen_pv_domain(void)
{
#ifdef XENHVM
        return (xen_pv_domain());
#else
        return (false);
#endif
}

static void
linux_compat_init(void *arg)
{
        struct sysctl_oid *rootoid;
        int i;

#if defined(__i386__) || defined(__amd64__)
        static const uint32_t x86_vendors[X86_VENDOR_NUM] = {
                [X86_VENDOR_INTEL] = CPU_VENDOR_INTEL,
                [X86_VENDOR_CYRIX] = CPU_VENDOR_CYRIX,
                [X86_VENDOR_AMD] = CPU_VENDOR_AMD,
                [X86_VENDOR_UMC] = CPU_VENDOR_UMC,
                [X86_VENDOR_CENTAUR] = CPU_VENDOR_CENTAUR,
                [X86_VENDOR_TRANSMETA] = CPU_VENDOR_TRANSMETA,
                [X86_VENDOR_NSC] = CPU_VENDOR_NSC,
                [X86_VENDOR_HYGON] = CPU_VENDOR_HYGON,
        };
        uint8_t x86_vendor = X86_VENDOR_UNKNOWN;

        for (i = 0; i < X86_VENDOR_NUM; i++) {
                if (cpu_vendor_id != 0 && cpu_vendor_id == x86_vendors[i]) {
                        x86_vendor = i;
                        break;
                }
        }
        linux_cpu_has_clflush = (cpu_feature & CPUID_CLFSH);
        boot_cpu_data.x86_clflush_size = cpu_clflush_line_size;
        boot_cpu_data.x86_max_cores = mp_ncpus;
        boot_cpu_data.x86 = CPUID_TO_FAMILY(cpu_id);
        boot_cpu_data.x86_model = CPUID_TO_MODEL(cpu_id);
        boot_cpu_data.x86_vendor = x86_vendor;

        __cpu_data = kmalloc_array(mp_maxid + 1,
            sizeof(*__cpu_data), M_WAITOK | M_ZERO);
        CPU_FOREACH(i) {
                __cpu_data[i].x86_clflush_size = cpu_clflush_line_size;
                __cpu_data[i].x86_max_cores = mp_ncpus;
                __cpu_data[i].x86 = CPUID_TO_FAMILY(cpu_id);
                __cpu_data[i].x86_model = CPUID_TO_MODEL(cpu_id);
                __cpu_data[i].x86_vendor = x86_vendor;
        }
#endif
        rw_init(&linux_vma_lock, "lkpi-vma-lock");

        rootoid = SYSCTL_ADD_ROOT_NODE(NULL,
            OID_AUTO, "sys", CTLFLAG_RD|CTLFLAG_MPSAFE, NULL, "sys");
        kobject_init(&linux_class_root, &linux_class_ktype);
        kobject_set_name(&linux_class_root, "class");
        linux_class_root.oidp = SYSCTL_ADD_NODE(NULL, SYSCTL_CHILDREN(rootoid),
            OID_AUTO, "class", CTLFLAG_RD|CTLFLAG_MPSAFE, NULL, "class");
        kobject_init(&linux_root_device.kobj, &linux_dev_ktype);
        kobject_set_name(&linux_root_device.kobj, "device");
        linux_root_device.kobj.oidp = SYSCTL_ADD_NODE(NULL,
            SYSCTL_CHILDREN(rootoid), OID_AUTO, "device",
            CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, "device");
        linux_root_device.bsddev = root_bus;
        linux_class_misc.name = "misc";
        class_register(&linux_class_misc);
        INIT_LIST_HEAD(&pci_drivers);
        INIT_LIST_HEAD(&pci_devices);
        spin_lock_init(&pci_lock);
        init_waitqueue_head(&linux_bit_waitq);
        init_waitqueue_head(&linux_var_waitq);

        CPU_COPY(&all_cpus, &cpu_online_mask);
        /*
         * Generate a single-CPU cpumask_t for each CPU (possibly) in the system.
         * CPUs are indexed from 0..(mp_maxid).  The entry for cpuid 0 will only
         * have itself in the cpumask, cupid 1 only itself on entry 1, and so on.
         * This is used by cpumask_of() (and possibly others in the future) for,
         * e.g., drivers to pass hints to irq_set_affinity_hint().
         */
        static_single_cpu_mask = kmalloc_array(mp_maxid + 1,
            sizeof(static_single_cpu_mask), M_WAITOK | M_ZERO);

        /*
         * When the number of CPUs reach a threshold, we start to save memory
         * given the sets are static by overlapping those having their single
         * bit set at same position in a bitset word.  Asymptotically, this
         * regular scheme is in O(n²) whereas the overlapping one is in O(n)
         * only with n being the maximum number of CPUs, so the gain will become
         * huge quite quickly.  The threshold for 64-bit architectures is 128
         * CPUs.
         */
        if (mp_ncpus < (2 * _BITSET_BITS)) {
                cpumask_t *sscm_ptr;

                /*
                 * This represents 'mp_ncpus * __bitset_words(CPU_SETSIZE) *
                 * (_BITSET_BITS / 8)' bytes (for comparison with the
                 * overlapping scheme).
                 */
                static_single_cpu_mask_lcs = kmalloc_array(mp_ncpus,
                    sizeof(*static_single_cpu_mask_lcs),
                    M_WAITOK | M_ZERO);

                sscm_ptr = static_single_cpu_mask_lcs;
                CPU_FOREACH(i) {
                        static_single_cpu_mask[i] = sscm_ptr++;
                        CPU_SET(i, static_single_cpu_mask[i]);
                }
        } else {
                /* Pointer to a bitset word. */
                __typeof(((cpuset_t *)NULL)->__bits[0]) *bwp;

                /*
                 * Allocate memory for (static) spans of 'cpumask_t' ('cpuset_t'
                 * really) with a single bit set that can be reused for all
                 * single CPU masks by making them start at different offsets.
                 * We need '__bitset_words(CPU_SETSIZE) - 1' bitset words before
                 * the word having its single bit set, and the same amount
                 * after.
                 */
                static_single_cpu_mask_lcs = mallocarray(_BITSET_BITS,
                    (2 * __bitset_words(CPU_SETSIZE) - 1) * (_BITSET_BITS / 8),
                    M_KMALLOC, M_WAITOK | M_ZERO);

                /*
                 * We rely below on cpuset_t and the bitset generic
                 * implementation assigning words in the '__bits' array in the
                 * same order of bits (i.e., little-endian ordering, not to be
                 * confused with machine endianness, which concerns bits in
                 * words and other integers).  This is an imperfect test, but it
                 * will detect a change to big-endian ordering.
                 */
                _Static_assert(
                    __bitset_word(_BITSET_BITS + 1, _BITSET_BITS) == 1,
                    "Assumes a bitset implementation that is little-endian "
                    "on its words");

                /* Initialize the single bit of each static span. */
                bwp = (__typeof(bwp))static_single_cpu_mask_lcs +
                    (__bitset_words(CPU_SETSIZE) - 1);
                for (i = 0; i < _BITSET_BITS; i++) {
                        CPU_SET(i, (cpuset_t *)bwp);
                        bwp += (2 * __bitset_words(CPU_SETSIZE) - 1);
                }

                /*
                 * Finally set all CPU masks to the proper word in their
                 * relevant span.
                 */
                CPU_FOREACH(i) {
                        bwp = (__typeof(bwp))static_single_cpu_mask_lcs;
                        /* Find the non-zero word of the relevant span. */
                        bwp += (2 * __bitset_words(CPU_SETSIZE) - 1) *
                            (i % _BITSET_BITS) +
                            __bitset_words(CPU_SETSIZE) - 1;
                        /* Shift to find the CPU mask start. */
                        bwp -= (i / _BITSET_BITS);
                        static_single_cpu_mask[i] = (cpuset_t *)bwp;
                }
        }

        strlcpy(init_uts_ns.name.release, osrelease, sizeof(init_uts_ns.name.release));
}
SYSINIT(linux_compat, SI_SUB_DRIVERS, SI_ORDER_SECOND, linux_compat_init, NULL);

static void
linux_compat_uninit(void *arg)
{
        linux_kobject_kfree_name(&linux_class_root);
        linux_kobject_kfree_name(&linux_root_device.kobj);
        linux_kobject_kfree_name(&linux_class_misc.kobj);

        free(static_single_cpu_mask_lcs, M_KMALLOC);
        free(static_single_cpu_mask, M_KMALLOC);
#if defined(__i386__) || defined(__amd64__)
        free(__cpu_data, M_KMALLOC);
#endif

        spin_lock_destroy(&pci_lock);
        rw_destroy(&linux_vma_lock);
}
SYSUNINIT(linux_compat, SI_SUB_DRIVERS, SI_ORDER_SECOND, linux_compat_uninit, NULL);

/*
 * NOTE: Linux frequently uses "unsigned long" for pointer to integer
 * conversion and vice versa, where in FreeBSD "uintptr_t" would be
 * used. Assert these types have the same size, else some parts of the
 * LinuxKPI may not work like expected:
 */
CTASSERT(sizeof(unsigned long) == sizeof(uintptr_t));