kernel/gdt.c

#include

static gdt_t     ALIGN(PAGE_SIZE) gdt;

static gdt_ptr_t ALIGN(PAGE_SIZE) gdt_ptr;

void gdt_set_entry(uint32_t index, addr_t base, uint32_t limit, uint32_t type)

{

gdt_entry_t *g = &(gdt.entries[index]);

g->limit_low  =  (limit / 4096) & 0xffff;

g->limit_high = ((limit / 4096) >> 16) & 0xf;

g->base_low   =   base & 0xffff;

g->base_high1 =  (base >> 16) & 0xff;

g->base_high2 =  (base >> 24) & 0xff;

g->type       =   type;

if (type != 0)

g->flags  =   GDT_GRAN_4K | GDT_MODE_32;

}

void dump_gdt(gdt_ptr_t *ptr)

{

gdt_t *val = (gdt_t*)ptr->base;

int i;

for(i=0; ilimit / sizeof(gdt_entry_t); i++)

{

uint8_t *v =(uint8_t *)&val->entries[i];

int j;

for(j=0; j

KPRINTF("%02X", *v);

KPRINTF("      ");

KPRINTF("%01X%04X|", val->entries[i].limit_high, val->entries[i].limit_low);

KPRINTF("%02X%02X%04X|", val->entries[i].base_high2, val->entries[i].base_high1, val->entries[i].base_low);

KPRINTF("%02X|", val->entries[i].type);

KPRINTF("%01X\n", val->entries[i].flags);

}

}

static void gdt_init()

{

KPRINTF("gdt_init\n");

gdt_ptr_t *ptr = &gdt_ptr;

/* Setup GDT entries. */

gdt_set_entry(GDT_NULL      , 0, 0, 0);

gdt_set_entry(GDT_KERNEL_CS , 0, 0xffffffff, GDT_TYPE_CODE0);

gdt_set_entry(GDT_KERNEL_DS , 0, 0xffffffff, GDT_TYPE_DATA0);

gdt_set_entry(GDT_USER_CS   , 0, 0xffffffff, GDT_TYPE_CODE3);

gdt_set_entry(GDT_USER_DS   , 0, 0xffffffff, GDT_TYPE_DATA3);

gdt_set_entry(GDT_TSS       , (addr_t)tss_get(), sizeof(tss_t), GDT_TYPE_TSS0);

/* Set GDT pointer. */

ptr->base  = (addr_t) &gdt;

ptr->limit = sizeof(gdt_t);

/* Load the GDT. */

load_gdt(&gdt_ptr);

}

INITFUNC(gdt_init, INIT_GDT);