gdt.c File Reference

#include "userprog/gdt.h"
#include <debug.h>
#include "userprog/tss.h"
#include "threads/mmu.h"
#include "threads/palloc.h"
#include "threads/vaddr.h"
#include "intrinsic.h"

Include dependency graph for gdt.c:

Classes
struct	segment_desc
struct	segment_descriptor64

Macros
#define	SEG64(type, base, lim, dpl)

Functions
void	gdt_init (void)

Variables
static struct segment_desc	gdt [SEL_CNT]
struct desc_ptr	gdt_ds

Macro Definition Documentation

SEG64

#define SEG64	(		type,
			base,
			lim,
			dpl
	)

Value:

(struct segment_desc) \
{ ((lim) >> 12) & 0xffff, (base) & 0xffff, ((base) >> 16) & 0xff, \
    type, 1, dpl, 1, (unsigned) (lim) >> 28, 0, 1, 0, 1, \
    (unsigned) (base) >> 24 }

Function Documentation

gdt_init()

void gdt_init

(

void

)

                {
    /* Initialize GDT. */
    struct segment_descriptor64 *tss_desc =
        (struct segment_descriptor64 *) &gdt[SEL_TSS >> 3];
    struct task_state *tss = tss_get ();
 
    *tss_desc = (struct segment_descriptor64) {
        .lim_15_0 = (uint64_t) (sizeof (struct task_state)) & 0xffff,
        .base_15_0 = (uint64_t) (tss) & 0xffff,
        .base_23_16 = ((uint64_t) (tss) >> 16) & 0xff,
        .type = 0x9,
        .s = 0,
        .dpl = 0,
        .p = 1,
        .lim_19_16 = ((uint64_t)(sizeof (struct task_state)) >> 16) & 0xf,
        .avl = 0,
        .rsv1 = 0,
        .g = 0,
        .base_31_24 = ((uint64_t)(tss) >> 24) & 0xff,
        .base_63_32 = ((uint64_t)(tss) >> 32) & 0xffffffff,
        .res1 = 0,
        .clear = 0,
        .res2 = 0
    };
 
    lgdt (&gdt_ds);
    /* reload segment registers */
    asm volatile("movw %%ax, %%gs" :: "a" (SEL_UDSEG));
    asm volatile("movw %%ax, %%fs" :: "a" (0));
    asm volatile("movw %%ax, %%es" :: "a" (SEL_KDSEG));
    asm volatile("movw %%ax, %%ds" :: "a" (SEL_KDSEG));
    asm volatile("movw %%ax, %%ss" :: "a" (SEL_KDSEG));
    asm volatile("pushq %%rbx\n"
            "movabs $1f, %%rax\n"
            "pushq %%rax\n"
            "lretq\n"
            "1:\n" :: "b" (SEL_KCSEG):"cc","memory");
    /* Kill the local descriptor table */
    lldt (0);
}

Here is the call graph for this function:

Here is the caller graph for this function:

Variable Documentation

gdt

struct segment_desc gdt[SEL_CNT]

static

Initial value:

= {
    [SEL_NULL >> 3] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
    [SEL_KCSEG >> 3] = SEG64 (0xa, 0x0, 0xffffffff, 0),
    [SEL_KDSEG >> 3] = SEG64 (0x2, 0x0, 0xffffffff, 0),
    [SEL_UDSEG >> 3] = SEG64 (0x2, 0x0, 0xffffffff, 3),
    [SEL_UCSEG >> 3] = SEG64 (0xa, 0x0, 0xffffffff, 3),
    [SEL_TSS >> 3] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
    [6] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
    [7] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
}

gdt_ds

struct desc_ptr gdt_ds

Initial value:

= {
    .size = sizeof(gdt) - 1,
    .address = (uint64_t) gdt
}