/*      $OpenBSD: mem.c,v 1.11 2025/12/23 19:16:51 miod Exp $ */

/*
 * Copyright (c) 1988 University of Utah.
 * Copyright (c) 1982, 1986, 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department.
 *
 * 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, 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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
 *
 *      @(#)mem.c       8.3 (Berkeley) 1/12/94
 */

/*
 * Memory special file
 */

#include <sys/param.h>
#include <sys/buf.h>
#include <sys/filio.h>
#include <sys/systm.h>
#include <sys/uio.h>
#include <sys/malloc.h>
#include <sys/atomic.h>

#include <machine/conf.h>

#include <uvm/uvm_extern.h>

caddr_t zpage;
extern vaddr_t first_addr;
extern caddr_t kernelstart;
extern void *etext;

int
mmopen(dev_t dev, int flag, int mode, struct proc *p)
{
        extern int allowkmem;

        switch (minor(dev)) {
        case 0:
        case 1:
                if ((int)atomic_load_int(&securelevel) <= 0 ||
                    atomic_load_int(&allowkmem))
                        break;
                return (EPERM);
        case 2:
        case 12:
                break;
        default:
                return (ENXIO);
        }
        return (0);
}

int
mmclose(dev_t dev, int flag, int mode, struct proc *p)
{

        return (0);
}

int
mmrw(dev_t dev, struct uio *uio, int flags)
{
        vaddr_t v;
        size_t c;
        struct iovec *iov;
        int error = 0;

        while (uio->uio_resid > 0 && error == 0) {
                iov = uio->uio_iov;
                if (iov->iov_len == 0) {
                        uio->uio_iov++;
                        uio->uio_iovcnt--;
                        if (uio->uio_iovcnt < 0)
                                panic("mmrw");
                        continue;
                }
                switch (minor(dev)) {

                /* minor device 0 is physical memory */
                case 0:
                        v = uio->uio_offset;
                        error = uiomove((caddr_t)v, uio->uio_resid, uio);
                        continue;

                /* minor device 1 is kernel memory */
                case 1:
                        v = uio->uio_offset;
                        c = ulmin(iov->iov_len, MAXPHYS);
                        if (v >= (vaddr_t)&kernelstart &&
                            v < (vaddr_t)first_addr) {
                                if (v < (vaddr_t)etext &&
                                    uio->uio_rw == UIO_WRITE)
                                        return (EFAULT);
                        } else if (!uvm_kernacc((caddr_t)v, c,
                            uio->uio_rw == UIO_READ ? B_READ : B_WRITE))
                                return (EFAULT);
                        error = uiomove((caddr_t)v, c, uio);
                        continue;

                /* minor device 2 is /dev/null */
                case 2:
                        if (uio->uio_rw == UIO_WRITE)
                                uio->uio_resid = 0;
                        return (0);

                /* minor device 12 is /dev/zero */
                case 12:
                        if (uio->uio_rw == UIO_WRITE) {
                                c = iov->iov_len;
                                break;
                        }
                        if (zpage == NULL)
                                zpage = malloc(PAGE_SIZE, M_TEMP,
                                    M_WAITOK | M_ZERO);
                        c = ulmin(iov->iov_len, PAGE_SIZE);
                        error = uiomove(zpage, c, uio);
                        continue;

                default:
                        return (ENXIO);
                }
                if (error)
                        break;
                iov->iov_base += c;
                iov->iov_len -= c;
                uio->uio_offset += c;
                uio->uio_resid -= c;
        }

        return (error);
}

paddr_t
mmmmap(dev_t dev, off_t off, int prot)
{
        return (-1);
}

int
mmioctl(dev_t dev, u_long cmd, caddr_t data, int flags, struct proc *p)
{
        switch (cmd) {
        case FIOASYNC:
                /* handled by fd layer */
                return 0;
        }

        return (ENOTTY);
}