/*      $NetBSD: mem.c,v 1.31 1996/05/03 19:42:19 christos Exp $        */
/*      $OpenBSD: mem.c,v 1.60 2024/12/30 02:46:00 guenther 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/memrange.h>
#include <sys/rwlock.h>
#include <sys/atomic.h>

#include <machine/conf.h>

#include <uvm/uvm_extern.h>

extern char *vmmap;            /* poor name! */
caddr_t zeropage;

/* open counter for aperture */
#ifdef APERTURE
static int ap_open_count = 0;
extern int allowaperture;

#define VGA_START 0xA0000
#define BIOS_END  0xFFFFF
#endif

#ifdef MTRR
struct mem_range_softc mem_range_softc;
static int mem_ioctl(dev_t, u_long, caddr_t, int, struct proc *);
#endif

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;
#ifdef APERTURE
        case 4:
                if (suser(p) != 0 || !allowaperture)
                        return (EPERM);

                /* authorize only one simultaneous open() unless
                 * allowaperture=3 */
                if (ap_open_count > 0 && allowaperture < 3)
                        return(EPERM);
                ap_open_count++;
                break;
#endif
        default:
                return (ENXIO);
        }
        return (0);
}

int
mmclose(dev_t dev, int flag, int mode, struct proc *p)
{
#ifdef APERTURE
        if (minor(dev) == 4)
                ap_open_count = 0;
#endif
        return (0);
}

static struct rwlock physlock = RWLOCK_INITIALIZER("mmrw");
int
mmrw(dev_t dev, struct uio *uio, int flags)
{
        vaddr_t o, v;
        size_t c;
        struct iovec *iov;
        int error = 0;

        if (minor(dev) == 0) {
                /* lock against other uses of shared vmmap */
                error = rw_enter(&physlock, RW_WRITE | RW_INTR);
                if (error)
                        return (error);
        }
        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;
                        pmap_enter(pmap_kernel(), (vaddr_t)vmmap,
                            trunc_page(v), uio->uio_rw == UIO_READ ?
                            PROT_READ : PROT_WRITE, PMAP_WIRED);
                        pmap_update(pmap_kernel());
                        o = uio->uio_offset & PGOFSET;
                        c = ulmin(uio->uio_resid, NBPG - o);
                        error = uiomove((caddr_t)vmmap + o, c, uio);
                        pmap_remove(pmap_kernel(), (vaddr_t)vmmap,
                            (vaddr_t)vmmap + NBPG);
                        pmap_update(pmap_kernel());
                        continue;

                /* minor device 1 is kernel memory */
                case 1:
                        v = uio->uio_offset;
                        c = ulmin(iov->iov_len, MAXPHYS);
                        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 (zeropage == NULL) {
                                zeropage = malloc(PAGE_SIZE, M_TEMP,
                                    M_WAITOK|M_ZERO);
                        }
                        c = ulmin(iov->iov_len, PAGE_SIZE);
                        error = uiomove(zeropage, c, uio);
                        continue;

                default:
                        return (ENXIO);
                }
                iov->iov_base = (char *)iov->iov_base + c;
                iov->iov_len -= c;
                uio->uio_offset += c;
                uio->uio_resid -= c;
        }
        if (minor(dev) == 0) {
                rw_exit(&physlock);
        }
        return (error);
}

paddr_t
mmmmap(dev_t dev, off_t off, int prot)
{
        struct proc *p = curproc;       /* XXX */

        switch (minor(dev)) {
        /* minor device 0 is physical memory */
        case 0:
                if ((u_int)off > ptoa(physmem) && suser(p) != 0)
                        return -1;
                return off;

#ifdef APERTURE
        /* minor device 4 is aperture driver */
        case 4:
                /* Check if a write combining mapping is requested. */
                if (off >= MEMRANGE_WC_RANGE)
                        off = (off - MEMRANGE_WC_RANGE) | PMAP_WC;

                switch (allowaperture) {
                case 1:
                        /* Allow mapping of the VGA framebuffer & BIOS only */
                        if ((off >= VGA_START && off <= BIOS_END) ||
                            (unsigned)off > (unsigned)ptoa(physmem))
                                return off;
                        else
                                return -1;
                case 2:
                case 3:
                        /* Allow mapping of the whole 1st megabyte
                           for x86emu */
                        if (off <= BIOS_END ||
                            (unsigned)off > (unsigned)ptoa(physmem))
                                return off;
                        else
                                return -1;
                default:
                        return -1;
                }
                        
#endif
        default:
                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;
        }

#ifdef MTRR
        switch (minor(dev)) {
        case 0:
        case 4:
                return mem_ioctl(dev, cmd, data, flags, p);
        }
#endif
        return (ENOTTY);
}

#ifdef MTRR
/*
 * Operations for changing memory attributes.
 *
 * This is basically just an ioctl shim for mem_range_attr_get
 * and mem_range_attr_set.
 */
static int
mem_ioctl(dev_t dev, u_long cmd, caddr_t data, int flags, struct proc *p)
{
        int nd, error = 0;
        struct mem_range_op *mo = (struct mem_range_op *)data;
        struct mem_range_desc *md;
        
        /* is this for us? */
        if ((cmd != MEMRANGE_GET) &&
            (cmd != MEMRANGE_SET))
                return (ENOTTY);

        /* any chance we can handle this? */
        if (mem_range_softc.mr_op == NULL)
                return (EOPNOTSUPP);

        /* do we have any descriptors? */
        if (mem_range_softc.mr_ndesc == 0)
                return (ENXIO);

        switch (cmd) {
        case MEMRANGE_GET:
                nd = imin(mo->mo_arg[0], mem_range_softc.mr_ndesc);
                if (nd > 0) {
                        md = mallocarray(nd, sizeof(struct mem_range_desc),
                            M_MEMDESC, M_WAITOK);
                        error = mem_range_attr_get(md, &nd);
                        if (!error)
                                error = copyout(md, mo->mo_desc,
                                        nd * sizeof(struct mem_range_desc));
                        free(md, M_MEMDESC, nd * sizeof(struct mem_range_desc));
                } else {
                        nd = mem_range_softc.mr_ndesc;
                }
                mo->mo_arg[0] = nd;
                break;
                
        case MEMRANGE_SET:
                md = malloc(sizeof(struct mem_range_desc), M_MEMDESC, M_WAITOK);
                error = copyin(mo->mo_desc, md, sizeof(struct mem_range_desc));
                /* clamp description string */
                md->mr_owner[sizeof(md->mr_owner) - 1] = 0;
                if (error == 0)
                        error = mem_range_attr_set(md, &mo->mo_arg[0]);
                free(md, M_MEMDESC, sizeof(struct mem_range_desc));
                break;
        }
        return (error);
}

/*
 * Implementation-neutral, kernel-callable functions for manipulating
 * memory range attributes.
 */
int
mem_range_attr_get(struct mem_range_desc *mrd, int *arg)
{
        /* can we handle this? */
        if (mem_range_softc.mr_op == NULL)
                return (EOPNOTSUPP);

        if (*arg == 0) {
                *arg = mem_range_softc.mr_ndesc;
        } else {
                bcopy(mem_range_softc.mr_desc, mrd, (*arg) * sizeof(struct mem_range_desc));
        }
        return (0);
}

int
mem_range_attr_set(struct mem_range_desc *mrd, int *arg)
{
        /* can we handle this? */
        if (mem_range_softc.mr_op == NULL)
                return (EOPNOTSUPP);

        return (mem_range_softc.mr_op->set(&mem_range_softc, mrd, arg));
}

#endif /* MTRR */