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/*

 * Copyright (C) 2001-2004 Jakub Jermar

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - 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.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * 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 <arch/pm.h>

#include <arch/mm/page.h>

#include <arch/types.h>

#include <arch/interrupt.h>

#include <arch/asm.h>

#include <config.h>

#include <memstr.h>

#include <mm/heap.h>

#include <debug.h>

/*

 * There is no segmentation in long mode so we set up flat mode. In this

 * mode, we use, for each privilege level, two segments spanning the

 * whole memory. One is for code and one is for data.

 */

struct descriptor gdt[GDT_ITEMS] = {

    /* NULL descriptor */

    { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },

    /* KTEXT descriptor */

    { .limit_0_15  = 0xffff,

      .base_0_15   = 0,

      .base_16_23  = 0,

      .access      = AR_PRESENT | AR_CODE | DPL_KERNEL | AR_READABLE ,

      .limit_16_19 = 0xf,

      .available   = 0,

      .longmode    = 1,

      .special     = 0,

      .granularity = 1,

      .base_24_31  = 0 },

    /* KDATA descriptor */

    { .limit_0_15  = 0xffff,

      .base_0_15   = 0,

      .base_16_23  = 0,

      .access      = AR_PRESENT | AR_DATA | AR_WRITABLE | DPL_KERNEL,

      .limit_16_19 = 0xf,

      .available   = 0,

      .longmode    = 0,

      .special     = 0,

      .granularity = 1,

      .base_24_31  = 0 },

    /* UTEXT descriptor */

    { .limit_0_15  = 0xffff,

      .base_0_15   = 0,

      .base_16_23  = 0,

      .access      = AR_PRESENT | AR_CODE | DPL_USER,

      .limit_16_19 = 0xf,

      .available   = 0,

      .longmode    = 1,

      .special     = 0,

      .granularity = 1,

      .base_24_31  = 0 },

    /* UDATA descriptor */

    { .limit_0_15  = 0xffff,

      .base_0_15   = 0,

      .base_16_23  = 0,

      .access      = AR_PRESENT | AR_DATA | AR_WRITABLE | DPL_USER,

      .limit_16_19 = 0xf,

      .available   = 0,

      .longmode    = 0,

      .special     = 1,

      .granularity = 1,

      .base_24_31  = 0 },

    /* KTEXT 16-bit protected */

    { .limit_0_15  = 0xffff,

      .base_0_15   = 0,

      .base_16_23  = 0,

      .access      = AR_PRESENT | AR_CODE | DPL_KERNEL | AR_READABLE,

      .limit_16_19 = 0xf,

      .available   = 0,

      .longmode    = 0,

      .special     = 0,

      .granularity = 1,

      .base_24_31  = 0 },

    /* TSS descriptor - set up will be completed later,

     * on AMD64 it is 64-bit - 2 items in table */

    { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },

    { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }

};

struct idescriptor idt[IDT_ITEMS];

struct ptr_16_64 gdtr = {.limit = sizeof(gdt), .base= (__u64) &gdt };

struct ptr_16_64 idtr = {.limit = sizeof(idt), .base= (__u64) &idt };

static struct tss tss;

struct tss *tss_p = NULL;

/* TODO: Does not compile correctly if it does not exist ???? */

int __attribute__ ((section ("K_DATA_START"))) __fake;

void gdt_tss_setbase(struct descriptor *d, __address base)

{

    struct tss_descriptor *td = (struct tss_descriptor *) d;

    td->base_0_15 = base & 0xffff;

    td->base_16_23 = ((base) >> 16) & 0xff;

    td->base_24_31 = ((base) >> 24) & 0xff;

    td->base_32_63 = ((base) >> 32);

}

void gdt_tss_setlimit(struct descriptor *d, __u32 limit)

{

    struct tss_descriptor *td = (struct tss_descriptor *) d;

    td->limit_0_15 = limit & 0xffff;

    td->limit_16_19 = (limit >> 16) & 0xf;

}

void idt_setoffset(struct idescriptor *d, __address offset)

{

    /*

     * Offset is a linear address.

     */

    d->offset_0_15 = offset & 0xffff;

    d->offset_16_31 = offset >> 16 & 0xffff;

    d->offset_32_63 = offset >> 32;

}

void tss_initialize(struct tss *t)

{

    memsetb((__address) t, sizeof(struct tss), 0);

}

/*

 * This function takes care of proper setup of IDT and IDTR.

 */

void idt_init(void)

{

    struct idescriptor *d;

    int i;

    for (i = 0; i < IDT_ITEMS; i++) {

        d = &idt[i];

        d->unused = 0;

        d->selector = gdtselector(KTEXT_DES);

        d->present = 1;

        d->type = AR_INTERRUPT; /* masking interrupt */

        if (i == VECTOR_SYSCALL) {

            /*

             * The syscall interrupt gate must be calleable from userland.

             */

            d->dpl |= PL_USER;

        }

        idt_setoffset(d, ((__address) interrupt_handlers) + i*interrupt_handler_size);

        trap_register(i, null_interrupt);

    }

    trap_register(13, gp_fault);

    trap_register( 7, nm_fault);

    trap_register(12, ss_fault);   

}

/* Clean IOPL(12,13) and NT(14) flags in EFLAGS register */

static void clean_IOPL_NT_flags(void)

{

    asm

    (

        "pushfq;"

        "pop %%rax;"

        "and $~(0x7000),%%rax;"

        "pushq %%rax;"

        "popfq;"

        :

        :

        :"%rax"

    );

}

/* Clean AM(18) flag in CR0 register */

static void clean_AM_flag(void)

{

    asm

    (

        "mov %%cr0,%%rax;"

        "and $~(0x40000),%%rax;"

        "mov %%rax,%%cr0;"

        :

        :

        :"%rax"

    );

}

void pm_init(void)

{

    struct descriptor *gdt_p = (struct descriptor *) gdtr.base;

    struct tss_descriptor *tss_desc;

    /*

     * Each CPU has its private GDT and TSS.

     * All CPUs share one IDT.

     */

    if (config.cpu_active == 1) {

        idt_init();

        /*

         * NOTE: bootstrap CPU has statically allocated TSS, because

         * the heap hasn't been initialized so far.

         */

        tss_p = &tss;

    }

    else {

        tss_p = (struct tss *) malloc(sizeof(struct tss));

        if (!tss_p)

            panic("could not allocate TSS\n");

    }

    tss_initialize(tss_p);

    tss_desc = (struct tss_descriptor *) (&gdt_p[TSS_DES]);

    tss_desc->present = 1;

    tss_desc->type = AR_TSS;

    tss_desc->dpl = PL_KERNEL;

    gdt_tss_setbase(&gdt_p[TSS_DES], (__address) tss_p);

    gdt_tss_setlimit(&gdt_p[TSS_DES], sizeof(struct tss) - 1);

    __asm__("lgdt %0" : : "m"(gdtr));

    __asm__("lidt %0" : : "m"(idtr));

    /*

     * As of this moment, the current CPU has its own GDT pointing

     * to its own TSS. We just need to load the TR register.

     */

    __asm__("ltr %0" : : "r" ((__u16) gdtselector(TSS_DES)));

    clean_IOPL_NT_flags();    /* Disable I/O on nonprivileged levels */

    clean_AM_flag();          /* Disable alignment check */

}