gdt.c File Reference

#include <libc.h>
#include <types.h>
#include <errno.h>
#include "gdt.h"
#include "sysdesc.h"
#include "tss.h"

Go to the source code of this file.

Macros
#define	POK_CONFIG_NB_THREADS   0
#define	POK_CONFIG_NB_PARTITIONS   0
#define	GDT_SIZE   256

Functions
pok_ret_t	pok_gdt_init ()
int	pok_tss_init ()
void	tss_set_esp0 (uint32_t esp0)
void	gdt_set_segment (uint16_t index, uint32_t base_address, uint32_t limit, e_gdte_type t, int dpl)
void	gdt_set_system (uint16_t index, uint32_t base_address, uint32_t limit, e_gdte_type t, int dpl)
void	gdt_enable (uint16_t index)
void	gdt_disable (uint16_t index)

Variables
gdt_entry_t	pok_gdt [GDT_SIZE]
tss_t	pok_tss

---

Macro Definition Documentation

#define GDT_SIZE   256

Definition at line 35 of file gdt.c.

#define POK_CONFIG_NB_PARTITIONS   0

Definition at line 32 of file gdt.c.

#define POK_CONFIG_NB_THREADS   0

Definition at line 28 of file gdt.c.

---

Function Documentation

void gdt_disable

(

uint16_t

index

)

Definition at line 155 of file gdt.c.

{
   pok_gdt[index].present = 0;
}

void gdt_enable

(

uint16_t

index

)

Definition at line 150 of file gdt.c.

{
   pok_gdt[index].present = 1;
}

void gdt_set_segment	(	uint16_t	index,
		uint32_t	base_address,
		uint32_t	limit,
		e_gdte_type	t,
		int	dpl
	)

Definition at line 99 of file gdt.c.

{
   if (limit > (1 << 20)) /* 4K granularity */
   {
      pok_gdt[index].limit_low = (limit >> 12) & 0xFFFF;
      pok_gdt[index].limit_high = (limit >> 28) & 0xF;
      pok_gdt[index].granularity = 1;
   }
   else /* 1B granularity */
   {
      pok_gdt[index].limit_low = limit & 0xFFFF;
      pok_gdt[index].limit_high = (limit >> 16) & 0xFF;
      pok_gdt[index].granularity = 0;
   }

   pok_gdt[index].base_low = base_address & 0xFFFFFF;
   pok_gdt[index].base_high = (base_address >> 24) & 0xFF;

   pok_gdt[index].type = t & 0xF;
   pok_gdt[index].dpl = dpl & 0x3;

   pok_gdt[index].s = 1;                      /* Segment is data/code type */
   pok_gdt[index].present = 1;
   pok_gdt[index].available = 0;
   pok_gdt[index].op_size = 1;        /* We work on 32 bits segments */
}

void gdt_set_system	(	uint16_t	index,
		uint32_t	base_address,
		uint32_t	limit,
		e_gdte_type	t,
		int	dpl
	)

Definition at line 130 of file gdt.c.

{
   pok_gdt[index].limit_low = limit & 0xFFFF;
   pok_gdt[index].limit_high = (limit >> 16) & 0xFF;
   pok_gdt[index].base_low = base_address & 0xFFFFFF;
   pok_gdt[index].base_high = (base_address >> 24) & 0xFF;

   pok_gdt[index].type = t & 0xF;
   pok_gdt[index].dpl = dpl & 0x3;

   pok_gdt[index].s = 0;                      /* Segment is system type */
   pok_gdt[index].present = 1;
   pok_gdt[index].available = 0;
   pok_gdt[index].op_size = 0;
}

pok_ret_t pok_gdt_init

(

)

Definition at line 41 of file gdt.c.

{
   sysdesc_t sysdesc;

   /* Set null descriptor and clear table */
   memset(pok_gdt, 0, sizeof (gdt_entry_t) * GDT_SIZE);

   /* Set kernel descriptors */
   gdt_set_segment(GDT_CORE_CODE_SEGMENT, 0, ~0UL, GDTE_CODE, 0);
   gdt_set_segment(GDT_CORE_DATA_SEGMENT, 0, ~0UL, GDTE_DATA, 0);

   /* Load GDT */
   sysdesc.limit = sizeof (pok_gdt);
   sysdesc.base = (uint32_t)pok_gdt;

   asm ("lgdt %0"
         :
         : "m" (sysdesc));

   /* Reload Segments */
   asm ("ljmp %0, $1f   \n"
         "1:            \n"
         "mov %1, %%ax  \n"
         "mov %%ax, %%ds        \n"
         "mov %%ax, %%es        \n"
         "mov %%ax, %%fs        \n"
         "mov %%ax, %%gs        \n"
         "mov %%ax, %%ss        \n"
         :
         : "i" (GDT_CORE_CODE_SEGMENT << 3),
         "i" (GDT_CORE_DATA_SEGMENT << 3)
         : "eax");

   pok_tss_init();

   return (POK_ERRNO_OK);
}

int pok_tss_init

(

)

Definition at line 79 of file gdt.c.

{
   uint16_t sel = GDT_BUILD_SELECTOR(GDT_TSS_SEGMENT, 0, 0);

   memset(&pok_tss, 0, sizeof (tss_t));

   pok_tss.ss0 = GDT_BUILD_SELECTOR(GDT_CORE_DATA_SEGMENT, 0, 0);

   gdt_set_system(GDT_TSS_SEGMENT, (uint32_t)&pok_tss,
         sizeof (tss_t), GDTE_TSS, 0);

   asm ("ltr %0" : :"m"(sel));
   return (POK_ERRNO_OK);
}

void tss_set_esp0

(

uint32_t

esp0

)

Definition at line 94 of file gdt.c.

{
   pok_tss.esp0 = esp0;
}

---

Variable Documentation

gdt_entry_t pok_gdt[GDT_SIZE]

Definition at line 37 of file gdt.c.

tss_t pok_tss

Definition at line 39 of file gdt.c.