tss.c

一个操作系统的源代码

/** tss.c
 **
 ** Original Author: Kasper Verdich Lund
 ** Date: 10/11/99
 **
 ** Description:
 ** TSS routines
 **
 ** This program is free software, you can redistribute it and/or
 ** modify it under the terms of the GNU General Public License
 ** as published by the Free Software Foundation; either version
 ** 2 of the License, or (at your option) any later version.
 **
 ** This program is distributed in the hope that it will be
 ** useful, but WITHOUT ANY WARRANTY; without even the implied
 ** warranty or MERCHANTABILITY or FITNESS FOR A PARTICULAR
 ** PURPOSE.  See the GNU General Public License for more
 ** details.
 **
 ** You should have received a copy of the GNU General Public
 ** License along with this program; if not, write to the
 ** Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 ** Boston, MA 02111-1307 USA
 **
 *********************************************************Apostle OS**/

#include <tss.h>
#include <gdt.h>
#include <paging.h>
#include <exception.h>
#include <address_space.h>
#include <mem.h>
#include <string.h>

TSS *systemTSS;
TSS *doublefaultTSS;
TSS *nmiTSS;

static TSS *newTSS(dword i_eip, dword i_esp, dword i_cr3, dword i_eflags,
		   dword i_cs, dword i_ds, dword i_ss)
{
  TSS *tss = (TSS *)pmalloc();
  memset(tss, 0, PAGE_SIZE);
  tss->eip = i_eip;
  tss->esp = i_esp;
  tss->cr3 = i_cr3;
  tss->eflags = i_eflags;
  tss->cs = i_cs;
  tss->ds = i_ds;
  tss->ss = i_ss;
  return tss;
}

void setKernelStack(TSS *tss, dword sp)
{
  tss->esp0 = sp;
  tss->ss0 = 0x10;
}

/* must be called AFTER setupGDT */
void setupTSS(void)
{
  systemTSS = newTSS(0, 0, 0, 0, 0, 0, 0);
  setKernelStack(systemTSS, 0);
  doublefaultTSS = newTSS((dword)&__DoubleFault, 
			  (dword)malloc(PAGE_SIZE)+PAGE_SIZE,
			  (dword)systemSpace, 0x02, 0x08, 0x23, 0x10);
  nmiTSS = newTSS((dword)&__NonMaskableInterrupt, 
		  (dword)malloc(PAGE_SIZE)+PAGE_SIZE,
		  (dword)systemSpace, 0x02, 0x08, 0x23, 0x10);
  setupDescriptor(&GDT[5], (dword)systemTSS, sizeof(TSS)-1, 9, 0, 0, 0); /* 0x28 */
  setupDescriptor(&GDT[6], (dword)doublefaultTSS, sizeof(TSS)-1, 9, 0, 0, 0);
  setupDescriptor(&GDT[7], (dword)nmiTSS, sizeof(TSS)-1, 9, 0, 0, 0);
  __asm__("movl $0x28, %eax\n"
	  "ltr %ax");
}