104 lines
3.2 KiB
C
104 lines
3.2 KiB
C
/* gdt.c - Global Descriptor Table support */
|
|
|
|
/*
|
|
* Copyright (c) 2011-2014 Wind River Systems, Inc.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions are met:
|
|
*
|
|
* 1) Redistributions of source code must retain the above copyright notice,
|
|
* this list of conditions and the following disclaimer.
|
|
*
|
|
* 2) Redistributions in binary form must reproduce the above copyright notice,
|
|
* this list of conditions and the following disclaimer in the documentation
|
|
* and/or other materials provided with the distribution.
|
|
*
|
|
* 3) Neither the name of Wind River Systems nor the names of its contributors
|
|
* may be used to endorse or promote products derived from this software without
|
|
* specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
|
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
|
|
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
* POSSIBILITY OF SUCH DAMAGE.
|
|
*/
|
|
|
|
/*
|
|
DESCRIPTION
|
|
This module contains routines for updating the global descriptor table (GDT)
|
|
for the IA-32 architecture.
|
|
*/
|
|
|
|
/* includes */
|
|
|
|
#include <linker-defs.h>
|
|
#include <toolchain.h>
|
|
#include <sections.h>
|
|
|
|
#include <nanok.h>
|
|
#include <nanokernel/cpu.h>
|
|
#include <gdt.h>
|
|
|
|
/* defines */
|
|
|
|
#if (CONFIG_NUM_GDT_SPARE_ENTRIES < 0)
|
|
#error "**** CONFIG_NUM_GDT_SPARE_ENTRIES must be at least 0\n\n"
|
|
#endif
|
|
|
|
#define NUM_BASE_GDT_ENTRIES 3
|
|
|
|
#define MAX_GDT_ENTRIES \
|
|
(NUM_BASE_GDT_ENTRIES + CONFIG_NUM_GDT_SPARE_ENTRIES)
|
|
|
|
/* locals */
|
|
|
|
/*
|
|
* The RAM based global descriptor table. It is aligned on an 8 byte boundary
|
|
* as the Intel manuals recommend this for best performance.
|
|
*/
|
|
|
|
/*
|
|
* For MM_POMS, _GdtEntries must be global so the linker script can
|
|
* generate a _GdtEntriesP for crt0.s
|
|
*/
|
|
static
|
|
tGdtDesc
|
|
_GdtEntries[MAX_GDT_ENTRIES]
|
|
__attribute__((aligned(8))) = {
|
|
{/* Entry 0 (selector=0x0000): The "NULL descriptor" */
|
|
0x0000, 0x0000, 0x00, 0x00, 0x00, 0x00},
|
|
{ /* Entry 1 (selector=0x0008): Code descriptor: DPL0 */
|
|
0xffff, /* limit: xffff */
|
|
0x0000, /* base : xxxx0000 */
|
|
0x00, /* base : xx00xxxx */
|
|
0x9b, /* Code e/r, Present, DPL0, Accessed=1 */
|
|
0xcf, /* limit: fxxxx, Page Gra, 32 bit */
|
|
0x00 /* base : 00xxxxxx */
|
|
},
|
|
{ /* Entry 2 (selector=0x0010): Data descriptor: DPL0 */
|
|
0xffff, /* limit: xffff */
|
|
0x0000, /* base : xxxx0000 */
|
|
0x00, /* base : xx00xxxx */
|
|
0x93, /* Data r/w, Present, DPL0, Accessed=1 */
|
|
0xcf, /* limit: fxxxx, Page Gra, 32 bit */
|
|
0x00 /* base : 00xxxxxx */
|
|
},
|
|
};
|
|
|
|
/* globals */
|
|
|
|
tGdtHeader _Gdt = {
|
|
sizeof(tGdtDesc[MAX_GDT_ENTRIES - CONFIG_NUM_GDT_SPARE_ENTRIES]) -
|
|
1,
|
|
&_GdtEntries[0]};
|
|
|
|
|
|
|