gdt.cxx

C++ 编写的EROS RTOS

/*
 * Copyright (C) 1998, 1999, Jonathan S. Shapiro.
 *
 * This file is part of the EROS Operating System.
 *
 * 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,
 * 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 of
 * 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, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include <kerninc/kernel.hxx>
#include "GDT.hxx"
#include "TSS.hxx"

/* Make sure this does not end up in BSS by using dummy initializers */
uint32_t GDT::GDTdescriptor[2];

void
GDT::SetupPageSegment(SegEntry::Name entry, uint32_t linearBase, uint32_t nPages)
{
  SegDescriptor& seg = *((SegDescriptor*) &GdtTable[entry*2]);

  seg.loBase = (linearBase & 0xffffu);
  seg.midBase = (linearBase >> 16) & 0xffu;
  seg.hiBase = (linearBase >> 24) & 0xffu;
  seg.loLimit = (nPages & 0xffffu);
  seg.hiLimit = ((nPages >> 16) & 0xfu);
  seg.granularity = 1;
}

void
GDT::SetupTSS(SegEntry::Name entry, uint32_t base)
{
  SegDescriptor& seg = *((SegDescriptor*) &GdtTable[entry*2]);
  
#ifndef NDEBUG
  SegDescriptor tssSeg;
  tssSeg.loLimit = sizeof(i386TSS)-1;
  tssSeg.loBase = 0;
  tssSeg.midBase = 0;
  tssSeg.hiBase = 0;
  tssSeg.type = 0x9;
  tssSeg.system = 0;
  tssSeg.dpl = 0;
  tssSeg.present = 1;
  tssSeg.hiLimit = 0;
  tssSeg.avl = 0;
  tssSeg.zero = 0;
  tssSeg.sz = 0;
  tssSeg.granularity = 0;

  uint32_t * wTssSeg = (uint32_t *) &tssSeg;
  uint32_t * wseg = (uint32_t *) &seg;

  assert(wseg[0] == wTssSeg[0]);
  assert(wseg[1] == wTssSeg[1]);
#endif
  
  uint32_t linearBase = KVTOL(base);
  
  seg.loBase = linearBase & 0xffffu;
  seg.midBase = (linearBase >> 16) & 0xffu;
  seg.hiBase = (linearBase >> 24) & 0xffu;
}

#define GDT_SIZE (GDT_ENTRIES * 8)

void
GDT::Init()
{
  uint32_t wgdt;

  wgdt = KVTOL(GdtTable);
	
  GDTdescriptor[0] = GDT_SIZE | ((wgdt & 0xffff) << 16);
  GDTdescriptor[1] = wgdt >> 16;

  uint32_t klimit = (0u - KVA) >> EROS_PAGE_ADDR_BITS;
  /* Initialize the GDT so that the kernel segment bases point to the
     right places. The table as initialized is correct for the user
     and APM segments. */
  SetupPageSegment(SegEntry::KernelCode, KVA, klimit );
  SetupPageSegment(SegEntry::KernelData, KVA, 0xfffff /*4G */);
  SetupPageSegment(SegEntry::KProcCode,  KVA, klimit );
  SetupPageSegment(SegEntry::KProcData,  KVA, 0xfffff /*4G */);
  SetupPageSegment(SegEntry::DomainCode,  KVA, LARGE_SPACE_PAGES );
  SetupPageSegment(SegEntry::DomainData,  KVA, LARGE_SPACE_PAGES );
  
  lgdt();
  ReloadSegRegs();
}

#ifdef OPTION_DDB
#include <arch-kerninc/db_machdep.hxx>
#include <ddb/db_output.hxx>

void
db_show_gdt(db_expr_t, int, db_expr_t, char*)
{
  GDT::ddb_dump();
}

void
GDT::ddb_dump()
{
  db_printf("GdtTable at 0x%08x\n", &GdtTable);
  
  for (int entry = 0; entry < GDT_ENTRIES; entry++) {
    SegDescriptor& seg = *((SegDescriptor*) &GdtTable[entry*2]);

    uint32_t base = ((((uint32_t)seg.hiBase) << 24) |
		     (((uint32_t)seg.midBase) << 16) |
		     ((uint32_t)seg.loBase));
    uint32_t limit = ((((uint32_t)seg.hiLimit) << 16) |
		     ((uint32_t)seg.loLimit));
    if (seg.granularity == 1)
      limit <<= EROS_PAGE_ADDR_BITS;
    
    db_printf("[%02d] base=0x%08x limit=0x%08x [w0=0x%08x w1=0x%08x]\n", 
	      entry, base, limit,
	      GdtTable[entry * 2], GdtTable[entry * 2 + 1]);

    db_printf("     ty=%d sys=%d dpl=%d pres=%d avl=%d gran=%d (%d bit)\n",
	      seg.type, seg.system, seg.dpl, seg.present, seg.avl,
	      seg.granularity, seg.sz ? 32 : 16);
  }
}
#endif