gdt.h

Go to the documentation of this file.

/*-
 * Copyright (c) 2002-2018 The UbixOS Project.
 * All rights reserved.
 *
 * This was developed by Christopher W. Olsen for the UbixOS Project.
 *
 * 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, the following disclaimer and the list of authors.
 * 2) Redistributions in binary form must reproduce the above copyright notice, this list of
 *    conditions, the following disclaimer and the list of authors in the documentation and/or
 *    other materials provided with the distribution.
 * 3) Neither the name of the UbixOS Project 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 AUTHOR 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 OWNER 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.
 */
 
#ifndef _GDT_H_
#define _GDT_H_
 
#define SEL_GET_PL(sel)  ((sel)&3) /* Get Priority Level Of Selector */
#define SEL_GET_LG(sel)  ((sel)&4) /* Return Local/Global Descriptor */
#define SEL_GET_IDX(sel) (((sel)>>3) & 0x1FFF) /* Get Selector Index */
 
#define SEL_PL_KERN 0x0
#define SEL_PL_USER 0x3
 
/* Descriptor Definitions */
#define dCall 0x0C00 /* 386 Call Gate                */
#define dCode 0x1800 /* Code Segment                 */
#define dData 0x1000 /* Data Segment                 */
#define dInt  0x0E00 /* 386 Interrupt Gate           */
#define dLdt  0x200  /* Local Descriptor Table (LDT) */
#define dTask 0x500  /* Task gate                    */
#define dTrap 0x0F00 /* 386 Trap Gate                */
#define dTss  0x900  /* Task State Segment (TSS)     */
 
/* Descriptor Options */
#define dDpl3     0x6000 /* DPL3 or mask for DPL             */
#define dDpl2     0x4000 /* DPL2 or mask for DPL             */
#define dDpl1     0x2000 /* DPL1 or mask for DPL             */
#define dDpl0     0x0000 /* DPL0 or mask for DPL             */
#define dPresent  0x8000 /* Present                          */
#define dNpresent 0x8000 /* Not Present                      */
#define dAcc      0x100  /* Accessed (Data or Code)          */
#define dWrite    0x200  /* Writable (Data segments only)    */
#define dRead     0x200  /* Readable (Code segments only)    */
#define dBusy     0xB00  /* Busy (TSS only)    was 200       */
#define dEexdown  0x400  /* Expand down (Data segments only) */
#define dConform  0x400  /* Conforming (Code segments only)  */
#define dBig      0x40   /* Default to 32 bit mode           */
#define dBiglim   0x80   /* Limit is in 4K units             */
 
/* GDT Descriptor */
struct gdtDescriptor {
    unsigned short limitLow; /* Limit 0..15    */
    unsigned short baseLow; /* Base  0..15    */
    unsigned char baseMed; /* Base  16..23   */
    unsigned char access; /* Access Byte    */
    unsigned int limitHigh :4; /* Limit 16..19   */
    unsigned int granularity :4; /* Granularity    */
    unsigned char baseHigh; /* Base 24..31    */
}__attribute__ ((packed));
 
struct gdtGate {
    unsigned short offsetLow; /* Offset 0..15  */
    unsigned short selector; /* Selector      */
    unsigned short access; /* Access Flags  */
    unsigned short offsetHigh; /* Offset 16..31 */
}__attribute__ ((packed));
 
union descriptorTableUnion {
    struct gdtDescriptor descriptor; /* Normal descriptor */
    struct gdtGate gate; /* Gate descriptor */
    unsigned long dummy; /* Any other info */
};
 
#define ubixDescriptorTable(name, length) union descriptorTableUnion name[length] =
#define ubixStandardDescriptor(base, limit, control) {.descriptor = {(limit & 0xffff), (base & 0xffff), ((base >> 16) & 0xff), ((control + dPresent) >> 8), (limit >> 16), ((control & 0xff) >> 4), (base >> 24)}}
#define ubixGateDescriptor(offset, selector, control) {.gate = {(offset & 0xffff), selector, (control+dPresent), (offset >> 16) }}
 
extern union descriptorTableUnion ubixGDT[11];
 
#endif
 
/***
 $Log: gdt.h,v $
 Revision 1.1.1.1  2006/06/01 12:46:15  reddawg
 ubix2
 
 Revision 1.2  2005/10/12 00:13:37  reddawg
 Removed
 
 Revision 1.1.1.1  2005/09/26 17:23:52  reddawg
 no message
 
 Revision 1.5  2004/08/15 16:47:49  reddawg
 Fixed
 
 Revision 1.4  2004/07/22 20:53:07  reddawg
 atkbd: fixed problem
 
 Revision 1.3  2004/05/21 15:12:17  reddawg
 Cleaned up
 
 END
 ***/