source: mainline/kernel/arch/ia32/src/pm.c@ d6f9fff

/*
 * 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.
 */

/** @addtogroup ia32
 * @{
 */
/** @file
 */

#include <arch/pm.h>
#include <config.h>
#include <typedefs.h>
#include <arch/interrupt.h>
#include <arch/asm.h>
#include <arch/context.h>
#include <panic.h>
#include <arch/mm/page.h>
#include <mm/km.h>
#include <mm/frame.h>
#include <mm/slab.h>
#include <memstr.h>
#include <arch/boot/boot.h>
#include <interrupt.h>

/*
 * Early ia32 configuration functions and data structures.
 */

/*
 * We don't have much use for segmentation 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.
 *
 * One special segment apart of that is for the GS register which holds
 * a pointer to the VREG page in its base.
 */
descriptor_t gdt[GDT_ITEMS] = {
        /* NULL descriptor */
        { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
        /* KTEXT descriptor */
        { 0xffff, 0, 0, AR_PRESENT | AR_CODE | DPL_KERNEL, 0xf, 0, 0, 1, 1, 0 },
        /* KDATA descriptor */
        { 0xffff, 0, 0, AR_PRESENT | AR_DATA | AR_WRITABLE | DPL_KERNEL, 0xf, 0, 0, 1, 1, 0 },
        /* UTEXT descriptor */
        { 0xffff, 0, 0, AR_PRESENT | AR_CODE | DPL_USER, 0xf, 0, 0, 1, 1, 0 },
        /* UDATA descriptor */
        { 0xffff, 0, 0, AR_PRESENT | AR_DATA | AR_WRITABLE | DPL_USER, 0xf, 0, 0, 1, 1, 0 },
        /* TSS descriptor - set up will be completed later */
        { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
        /* VREG descriptor - segment used for virtual registers, will be reinitialized later */
        { 0xffff, 0 , 0, AR_PRESENT | AR_DATA | AR_WRITABLE | DPL_USER, 0xf, 0, 0, 1, 1, 0 },
        /* VESA Init descriptor */
#ifdef CONFIG_FB
        { 0xffff, 0, VESA_INIT_SEGMENT >> 12, AR_PRESENT | AR_CODE | AR_READABLE | DPL_KERNEL, 0xf, 0, 0, 0, 0, 0 },
        { 0xffff, 0, VESA_INIT_SEGMENT >> 12, AR_PRESENT | AR_DATA | AR_WRITABLE | DPL_KERNEL, 0xf, 0, 0, 0, 0, 0 }
#endif
};

static idescriptor_t idt[IDT_ITEMS];

static tss_t tss0;

tss_t *tss_p = NULL;

/* gdtr is changed by kmp before next CPU is initialized */
ptr_16_32_t gdtr = {
        .limit = sizeof(gdt),
        .base = (uintptr_t) gdt
};

void gdt_setbase(descriptor_t *d, uintptr_t base)
{
        d->base_0_15 = base & 0xffff;
        d->base_16_23 = (base >> 16) & 0xff;
        d->base_24_31 = (base >> 24) & 0xff;
}

void gdt_setlimit(descriptor_t *d, uint32_t limit)
{
        d->limit_0_15 = limit & 0xffff;
        d->limit_16_19 = (limit >> 16) & 0xf;
}

void idt_setoffset(idescriptor_t *d, uintptr_t offset)
{
        /*
         * Offset is a linear address.
         */
        d->offset_0_15 = offset & 0xffff;
        d->offset_16_31 = offset >> 16;
}

void tss_initialize(tss_t *t)
{
        memsetb(t, sizeof(tss_t), 0);
}

/*
 * This function takes care of proper setup of IDT and IDTR.
 */
void idt_init(void)
{
        idescriptor_t *d;
        unsigned int i;

        for (i = 0; i < IDT_ITEMS; i++) {
                d = &idt[i];

                d->unused = 0;
                d->selector = GDT_SELECTOR(KTEXT_DES);

                if (i == VECTOR_SYSCALL) {
                        /*
                         * The syscall trap gate must be callable from
                         * userland. Interrupts will remain enabled.
                         */
                        d->access = AR_PRESENT | AR_TRAP | DPL_USER;
                } else {
                        /*
                         * Other interrupts use interrupt gates which
                         * disable interrupts.
                         */
                        d->access = AR_PRESENT | AR_INTERRUPT;
                }
        }

        d = &idt[0];
        idt_setoffset(d++, (uintptr_t) &int_0);
        idt_setoffset(d++, (uintptr_t) &int_1);
        idt_setoffset(d++, (uintptr_t) &int_2);
        idt_setoffset(d++, (uintptr_t) &int_3);
        idt_setoffset(d++, (uintptr_t) &int_4);
        idt_setoffset(d++, (uintptr_t) &int_5);
        idt_setoffset(d++, (uintptr_t) &int_6);
        idt_setoffset(d++, (uintptr_t) &int_7);
        idt_setoffset(d++, (uintptr_t) &int_8);
        idt_setoffset(d++, (uintptr_t) &int_9);
        idt_setoffset(d++, (uintptr_t) &int_10);
        idt_setoffset(d++, (uintptr_t) &int_11);
        idt_setoffset(d++, (uintptr_t) &int_12);
        idt_setoffset(d++, (uintptr_t) &int_13);
        idt_setoffset(d++, (uintptr_t) &int_14);
        idt_setoffset(d++, (uintptr_t) &int_15);
        idt_setoffset(d++, (uintptr_t) &int_16);
        idt_setoffset(d++, (uintptr_t) &int_17);
        idt_setoffset(d++, (uintptr_t) &int_18);
        idt_setoffset(d++, (uintptr_t) &int_19);
        idt_setoffset(d++, (uintptr_t) &int_20);
        idt_setoffset(d++, (uintptr_t) &int_21);
        idt_setoffset(d++, (uintptr_t) &int_22);
        idt_setoffset(d++, (uintptr_t) &int_23);
        idt_setoffset(d++, (uintptr_t) &int_24);
        idt_setoffset(d++, (uintptr_t) &int_25);
        idt_setoffset(d++, (uintptr_t) &int_26);
        idt_setoffset(d++, (uintptr_t) &int_27);
        idt_setoffset(d++, (uintptr_t) &int_28);
        idt_setoffset(d++, (uintptr_t) &int_29);
        idt_setoffset(d++, (uintptr_t) &int_30);
        idt_setoffset(d++, (uintptr_t) &int_31);
        idt_setoffset(d++, (uintptr_t) &int_32);
        idt_setoffset(d++, (uintptr_t) &int_33);
        idt_setoffset(d++, (uintptr_t) &int_34);
        idt_setoffset(d++, (uintptr_t) &int_35);
        idt_setoffset(d++, (uintptr_t) &int_36);
        idt_setoffset(d++, (uintptr_t) &int_37);
        idt_setoffset(d++, (uintptr_t) &int_38);
        idt_setoffset(d++, (uintptr_t) &int_39);
        idt_setoffset(d++, (uintptr_t) &int_40);
        idt_setoffset(d++, (uintptr_t) &int_41);
        idt_setoffset(d++, (uintptr_t) &int_42);
        idt_setoffset(d++, (uintptr_t) &int_43);
        idt_setoffset(d++, (uintptr_t) &int_44);
        idt_setoffset(d++, (uintptr_t) &int_45);
        idt_setoffset(d++, (uintptr_t) &int_46);
        idt_setoffset(d++, (uintptr_t) &int_47);
        idt_setoffset(d++, (uintptr_t) &int_48);
        idt_setoffset(d++, (uintptr_t) &int_49);
        idt_setoffset(d++, (uintptr_t) &int_50);
        idt_setoffset(d++, (uintptr_t) &int_51);
        idt_setoffset(d++, (uintptr_t) &int_52);
        idt_setoffset(d++, (uintptr_t) &int_53);
        idt_setoffset(d++, (uintptr_t) &int_54);
        idt_setoffset(d++, (uintptr_t) &int_55);
        idt_setoffset(d++, (uintptr_t) &int_56);
        idt_setoffset(d++, (uintptr_t) &int_57);
        idt_setoffset(d++, (uintptr_t) &int_58);
        idt_setoffset(d++, (uintptr_t) &int_59);
        idt_setoffset(d++, (uintptr_t) &int_60);
        idt_setoffset(d++, (uintptr_t) &int_61);
        idt_setoffset(d++, (uintptr_t) &int_62);
        idt_setoffset(d++, (uintptr_t) &int_63);

        idt_setoffset(&idt[VECTOR_SYSCALL], (uintptr_t) &int_syscall);
}

/* Clean IOPL(12,13) and NT(14) flags in EFLAGS register */
static void clean_IOPL_NT_flags(void)
{
        asm volatile (
                "pushfl\n"
                "pop %%eax\n"
                "and $0xffff8fff, %%eax\n"
                "push %%eax\n"
                "popfl\n"
                ::: "eax"
        );
}

/* Clean AM(18) flag in CR0 register */
static void clean_AM_flag(void)
{
        asm volatile (
                "mov %%cr0, %%eax\n"
                "and $0xfffbffff, %%eax\n"
                "mov %%eax, %%cr0\n"
                ::: "eax"
        );
}

void pm_init(void)
{
        descriptor_t *gdt_p = (descriptor_t *) gdtr.base;
        ptr_16_32_t idtr;

        /*
         * Update addresses in GDT and IDT to their virtual counterparts.
         */
        idtr.limit = sizeof(idt);
        idtr.base = (uintptr_t) idt;
        gdtr_load(&gdtr);
        idtr_load(&idtr);
        
        /*
         * 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 = &tss0;
        } else {
                tss_p = (tss_t *) malloc(sizeof(tss_t), FRAME_ATOMIC);
                if (!tss_p)
                        panic("Cannot allocate TSS.");
        }

        tss_initialize(tss_p);
        
        gdt_p[TSS_DES].access = AR_PRESENT | AR_TSS | DPL_KERNEL;
        gdt_p[TSS_DES].special = 1;
        gdt_p[TSS_DES].granularity = 0;
        
        gdt_setbase(&gdt_p[TSS_DES], (uintptr_t) tss_p);
        gdt_setlimit(&gdt_p[TSS_DES], TSS_BASIC_SIZE - 1);

        /*
         * As of this moment, the current CPU has its own GDT pointing
         * to its own TSS. We just need to load the TR register.
         */
        tr_load(GDT_SELECTOR(TSS_DES));
        
        clean_IOPL_NT_flags();    /* Disable I/O on nonprivileged levels and clear NT flag. */
        clean_AM_flag();          /* Disable alignment check */
}

/** @}
 */