/*      $NetBSD: prekern.c,v 1.6 2022/08/21 14:05:52 mlelstv Exp $      */

/*
 * Copyright (c) 2017 The NetBSD Foundation, Inc. All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Maxime Villard.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

#include <sys/cdefs.h>

#include "opt_realmem.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/cpu.h>
#include <sys/conf.h>

#include <uvm/uvm.h>
#include <machine/pmap.h>
#include <machine/pmap_private.h>
#include <machine/bootinfo.h>
#include <machine/cpufunc.h>

#include <x86/bootspace.h>

#include <dev/isa/isareg.h>
#include <machine/isa_machdep.h>

#define PREKERN_API_VERSION     2

struct prekern_args {
        int version;
        int boothowto;
        void *bootinfo;
        void *bootspace;
        int esym;
        int biosextmem;
        int biosbasemem;
        int cpuid_level;
        uint32_t nox_flag;
        uint64_t PDPpaddr;
        vaddr_t atdevbase;
        vaddr_t lwp0uarea;
        paddr_t first_avail;
};

void main(void);
void init_slotspace(void);
void init_x86_64(paddr_t);

static void prekern_copy_args(struct prekern_args *);
static void prekern_unmap(void);
int start_prekern(struct prekern_args *);

static void
prekern_copy_args(struct prekern_args *pkargs)
{
        extern int boothowto;
        extern struct bootinfo bootinfo;
        extern struct bootspace bootspace;
        extern int esym;
        extern int biosextmem;
        extern int biosbasemem;
        extern int cpuid_level;
        extern uint32_t nox_flag;
        extern uint64_t PDPpaddr;
        extern vaddr_t lwp0uarea;

        boothowto = pkargs->boothowto;
        memcpy(&bootinfo, pkargs->bootinfo, sizeof(bootinfo));
        memcpy(&bootspace, pkargs->bootspace, sizeof(bootspace));
        esym = pkargs->esym;

#ifndef REALEXTMEM
        biosextmem = pkargs->biosextmem;
#else
        biosextmem = REALEXTMEM;
#endif

#ifndef REALBASEMEM
        biosbasemem = pkargs->biosbasemem;
#else
        biosbasemem = REALBASEMEM;
#endif

        cpuid_level = pkargs->cpuid_level;
        nox_flag = pkargs->nox_flag;
        PDPpaddr = pkargs->PDPpaddr;
        atdevbase = pkargs->atdevbase;
        lwp0uarea = pkargs->lwp0uarea;
}

static void
prekern_unmap_pte(void)
{
        extern struct bootspace bootspace;
        pd_entry_t *pdir = (pd_entry_t *)bootspace.pdir;

        /* Unmap the prekern recursive PTE slot. */
        pdir[509] = 0;
        tlbflushg();
}

static void
prekern_unmap(void)
{
        /* Unmap the prekern itself. */
        L4_BASE[0] = 0;
        tlbflushg();
}

/*
 * The prekern jumps here.
 */
int
start_prekern(struct prekern_args *pkargs)
{
        paddr_t first_avail;

        if (pkargs->version != PREKERN_API_VERSION) {
                return -1;
        }

        prekern_copy_args(pkargs);
        first_avail = pkargs->first_avail;

        prekern_unmap_pte();
        init_slotspace();
        init_x86_64(first_avail);
        prekern_unmap();

        main();

        panic("main returned");

        return 0;
}