source: mainline/kernel/arch/ia32/src/pm.c@ b1349e0

/*
 * 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 <arch/types.h>
#include <arch/interrupt.h>
#include <arch/asm.h>
#include <arch/context.h>
#include <panic.h>
#include <arch/mm/page.h>
#include <mm/slab.h>
#include <memstr.h>
#include <arch/boot/boot.h>
#include <interrupt.h>

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

/*
 * We have no 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 is for GS register which holds pointer to the TLS thread
 * structure in it's 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 },
        /* TLS descriptor */
        { 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 | DPL_KERNEL, 0xf, 0, 0, 0, 0, 0 }
#endif  
};

static idescriptor_t idt[IDT_ITEMS];

static tss_t tss;

tss_t *tss_p = NULL;

/* gdtr is changed by kmp before next CPU is initialized */
ptr_16_32_t bootstrap_gdtr = { .limit = sizeof(gdt), .base = KA2PA((uintptr_t) gdt) };
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((uintptr_t) t, sizeof(struct tss), 0);
}

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

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

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

                d->access = AR_PRESENT | AR_INTERRUPT;  /* masking interrupt */

                if (i == VECTOR_SYSCALL) {
                        /*
                         * The syscall interrupt gate must be calleable from userland.
                         */
                        d->access |= DPL_USER;
                }
                
                idt_setoffset(d, ((uintptr_t) interrupt_handlers) + i * interrupt_handler_size);
        }
}


/* 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 = &tss;
        }
        else {
                tss_p = (tss_t *) malloc(sizeof(tss_t), FRAME_ATOMIC);
                if (!tss_p)
                        panic("could not allocate TSS\n");
        }

        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(selector(TSS_DES));
        
        clean_IOPL_NT_flags();    /* Disable I/O on nonprivileged levels and clear NT flag. */
        clean_AM_flag();          /* Disable alignment check */
}

void set_tls_desc(uintptr_t tls)
{
        ptr_16_32_t cpugdtr;
        descriptor_t *gdt_p;

        gdtr_store(&cpugdtr);
        gdt_p = (descriptor_t *) cpugdtr.base;
        gdt_setbase(&gdt_p[TLS_DES], tls);
        /* Reload gdt register to update GS in CPU */
        gdtr_load(&cpugdtr);
}

/** @}
 */