85 lines
2.9 KiB
C
85 lines
2.9 KiB
C
/* gdt.h - IA-32 Global Descriptor Table (GDT) definitions */
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/*
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* Copyright (c) 2011-2012, 2014 Wind River Systems, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1) Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* 2) Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* 3) Neither the name of Wind River Systems nor the names of its contributors
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* may be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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DESCRIPTION
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This file provides definitions for the Global Descriptor Table (GDT) for the
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IA-32 architecture.
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*/
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#ifndef _GDT_H
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#define _GDT_H
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/* includes */
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#include <nanokernel/x86/arch.h>
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#ifndef _ASMLANGUAGE
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#include <stdint.h>
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#include <toolchain.h>
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/* typedefs */
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/* a generic GDT entry structure definition */
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typedef struct s_gdtDesc {
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uint16_t limitLowerWord; /* bits 0:15 of segment limit */
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uint16_t baseAdrsLowerWord; /* bits 0:15 of segment base address */
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uint8_t baseAdrsMidByte; /* bits 16:23 of segment base address */
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uint8_t descType; /* descriptor type fields */
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uint8_t limitUpperByte; /* bits 16:19 of limit + more type fields */
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uint8_t baseAdrsUpperByte; /* bits 24:31 of segment base address */
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} tGdtDesc;
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/*
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* structure definition for the GDT "header"
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* (does not include the GDT entries).
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* The structure is packed to force the structure to appear "as is".
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* Unfortunately, this appears to remove any alignment restrictions
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* so the aligned attribute is used.
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*/
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typedef struct PACK_STRUCT s_gdtHeader
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{
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uint16_t limit; /* GDT limit */
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tGdtDesc *pEntries; /* pointer to the GDT entries */
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} tGdtHeader __attribute__((aligned(4)));
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/* externs */
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extern tGdtHeader _gdt; /* GDT is implemented in arch/x86/core/gdt.c */
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#endif /* _ASMLANGUAGE */
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#endif /* _GDT_H */
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