81f61bb1be
For some security scenarios the GDT may already be setup and locked, in which case the kernel trying to set it again could lead to problems. Change-Id: I727c1d213479f46a4bb6f0c04a9096131e10b3e7 Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
79 lines
2.1 KiB
C
79 lines
2.1 KiB
C
/*
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* Copyright (c) 2011-2012, 2014 Wind River Systems, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/**
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* @file
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* @brief IA-32 Global Descriptor Table (GDT) definitions
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*
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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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#include <arch/x86/arch.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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#ifndef _ASMLANGUAGE
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#include <stdint.h>
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#include <toolchain.h>
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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 __packed 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 __aligned(4);
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/* externs */
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#ifdef CONFIG_SET_GDT
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/* This is either the ROM-based GDT in crt0.S or RAM-based in gdt.c,
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* depending on CONFIG_GDT_DYNAMIC
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*/
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extern tGdtHeader _gdt;
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#endif
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#endif /* _ASMLANGUAGE */
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#ifdef __cplusplus
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}
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#endif
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#endif /* _GDT_H */
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