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Annotation of Net2/arch/i386/include/segments.h, revision 1.1

1.1     ! root        1: /*-
        !             2:  * Copyright (c) 1989, 1990 William F. Jolitz
        !             3:  * Copyright (c) 1990 The Regents of the University of California.
        !             4:  * All rights reserved.
        !             5:  *
        !             6:  * This code is derived from software contributed to Berkeley by
        !             7:  * William Jolitz.
        !             8:  *
        !             9:  * Redistribution and use in source and binary forms, with or without
        !            10:  * modification, are permitted provided that the following conditions
        !            11:  * are met:
        !            12:  * 1. Redistributions of source code must retain the above copyright
        !            13:  *    notice, this list of conditions and the following disclaimer.
        !            14:  * 2. Redistributions in binary form must reproduce the above copyright
        !            15:  *    notice, this list of conditions and the following disclaimer in the
        !            16:  *    documentation and/or other materials provided with the distribution.
        !            17:  * 3. All advertising materials mentioning features or use of this software
        !            18:  *    must display the following acknowledgement:
        !            19:  *     This product includes software developed by the University of
        !            20:  *     California, Berkeley and its contributors.
        !            21:  * 4. Neither the name of the University nor the names of its contributors
        !            22:  *    may be used to endorse or promote products derived from this software
        !            23:  *    without specific prior written permission.
        !            24:  *
        !            25:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            26:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            27:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            28:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            29:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            30:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            31:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            32:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            33:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            34:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            35:  * SUCH DAMAGE.
        !            36:  *
        !            37:  *     @(#)segments.h  7.1 (Berkeley) 5/9/91
        !            38:  */
        !            39: 
        !            40: /*
        !            41:  * 386 Segmentation Data Structures and definitions
        !            42:  *     William F. Jolitz ([email protected]) 6/20/1989
        !            43:  */
        !            44: 
        !            45: /*
        !            46:  * Selectors
        !            47:  */
        !            48: 
        !            49: #define        ISPL(s) ((s)&3)         /* what is the priority level of a selector */
        !            50: #define        SEL_KPL 0               /* kernel priority level */     
        !            51: #define        SEL_UPL 3               /* user priority level */       
        !            52: #define        ISLDT(s)        ((s)&SEL_LDT)   /* is it local or global */
        !            53: #define        SEL_LDT 4               /* local descriptor table */    
        !            54: #define        IDXSEL(s)       (((s)>>3) & 0x1fff)             /* index of selector */
        !            55: #define        LSEL(s,r)       (((s)<<3) | SEL_LDT | r)        /* a local selector */
        !            56: #define        GSEL(s,r)       (((s)<<3) | r)                  /* a global selector */
        !            57: 
        !            58: /*
        !            59:  * Memory and System segment descriptors
        !            60:  */
        !            61: struct segment_descriptor      {
        !            62:        unsigned sd_lolimit:16 ;        /* segment extent (lsb) */
        !            63:        unsigned sd_lobase:24 ;         /* segment base address (lsb) */
        !            64:        unsigned sd_type:5 ;            /* segment type */
        !            65:        unsigned sd_dpl:2 ;             /* segment descriptor priority level */
        !            66:        unsigned sd_p:1 ;               /* segment descriptor present */
        !            67:        unsigned sd_hilimit:4 ;         /* segment extent (msb) */
        !            68:        unsigned sd_xx:2 ;              /* unused */
        !            69:        unsigned sd_def32:1 ;           /* default 32 vs 16 bit size */
        !            70:        unsigned sd_gran:1 ;            /* limit granularity (byte/page units)*/
        !            71:        unsigned sd_hibase:8 ;          /* segment base address  (msb) */
        !            72: } ;
        !            73: 
        !            74: /*
        !            75:  * Gate descriptors (e.g. indirect descriptors)
        !            76:  */
        !            77: struct gate_descriptor {
        !            78:        unsigned gd_looffset:16 ;       /* gate offset (lsb) */
        !            79:        unsigned gd_selector:16 ;       /* gate segment selector */
        !            80:        unsigned gd_stkcpy:5 ;          /* number of stack wds to cpy */
        !            81:        unsigned gd_xx:3 ;              /* unused */
        !            82:        unsigned gd_type:5 ;            /* segment type */
        !            83:        unsigned gd_dpl:2 ;             /* segment descriptor priority level */
        !            84:        unsigned gd_p:1 ;               /* segment descriptor present */
        !            85:        unsigned gd_hioffset:16 ;       /* gate offset (msb) */
        !            86: } ;
        !            87: 
        !            88: /*
        !            89:  * Generic descriptor
        !            90:  */
        !            91: union  descriptor      {
        !            92:        struct  segment_descriptor sd;
        !            93:        struct  gate_descriptor gd;
        !            94: };
        !            95: #define        d_type  gd.gd_type
        !            96: 
        !            97:        /* system segments and gate types */
        !            98: #define        SDT_SYSNULL      0      /* system null */
        !            99: #define        SDT_SYS286TSS    1      /* system 286 TSS available */
        !           100: #define        SDT_SYSLDT       2      /* system local descriptor table */
        !           101: #define        SDT_SYS286BSY    3      /* system 286 TSS busy */
        !           102: #define        SDT_SYS286CGT    4      /* system 286 call gate */
        !           103: #define        SDT_SYSTASKGT    5      /* system task gate */
        !           104: #define        SDT_SYS286IGT    6      /* system 286 interrupt gate */
        !           105: #define        SDT_SYS286TGT    7      /* system 286 trap gate */
        !           106: #define        SDT_SYSNULL2     8      /* system null again */
        !           107: #define        SDT_SYS386TSS    9      /* system 386 TSS available */
        !           108: #define        SDT_SYSNULL3    10      /* system null again */
        !           109: #define        SDT_SYS386BSY   11      /* system 386 TSS busy */
        !           110: #define        SDT_SYS386CGT   12      /* system 386 call gate */
        !           111: #define        SDT_SYSNULL4    13      /* system null again */
        !           112: #define        SDT_SYS386IGT   14      /* system 386 interrupt gate */
        !           113: #define        SDT_SYS386TGT   15      /* system 386 trap gate */
        !           114: 
        !           115:        /* memory segment types */
        !           116: #define        SDT_MEMRO       16      /* memory read only */
        !           117: #define        SDT_MEMROA      17      /* memory read only accessed */
        !           118: #define        SDT_MEMRW       18      /* memory read write */
        !           119: #define        SDT_MEMRWA      19      /* memory read write accessed */
        !           120: #define        SDT_MEMROD      20      /* memory read only expand dwn limit */
        !           121: #define        SDT_MEMRODA     21      /* memory read only expand dwn limit accessed */
        !           122: #define        SDT_MEMRWD      22      /* memory read write expand dwn limit */
        !           123: #define        SDT_MEMRWDA     23      /* memory read write expand dwn limit acessed */
        !           124: #define        SDT_MEME        24      /* memory execute only */
        !           125: #define        SDT_MEMEA       25      /* memory execute only accessed */
        !           126: #define        SDT_MEMER       26      /* memory execute read */
        !           127: #define        SDT_MEMERA      27      /* memory execute read accessed */
        !           128: #define        SDT_MEMEC       28      /* memory execute only conforming */
        !           129: #define        SDT_MEMEAC      29      /* memory execute only accessed conforming */
        !           130: #define        SDT_MEMERC      30      /* memory execute read conforming */
        !           131: #define        SDT_MEMERAC     31      /* memory execute read accessed conforming */
        !           132: 
        !           133: /* is memory segment descriptor pointer ? */
        !           134: #define ISMEMSDP(s)    ((s->d_type) >= SDT_MEMRO && (s->d_type) <= SDT_MEMERAC)
        !           135: 
        !           136: /* is 286 gate descriptor pointer ? */
        !           137: #define IS286GDP(s)    (((s->d_type) >= SDT_SYS286CGT \
        !           138:                                 && (s->d_type) < SDT_SYS286TGT))
        !           139: 
        !           140: /* is 386 gate descriptor pointer ? */
        !           141: #define IS386GDP(s)    (((s->d_type) >= SDT_SYS386CGT \
        !           142:                                && (s->d_type) < SDT_SYS386TGT))
        !           143: 
        !           144: /* is gate descriptor pointer ? */
        !           145: #define ISGDP(s)       (IS286GDP(s) || IS386GDP(s))
        !           146: 
        !           147: /* is segment descriptor pointer ? */
        !           148: #define ISSDP(s)       (ISMEMSDP(s) || !ISGDP(s))
        !           149: 
        !           150: /* is system segment descriptor pointer ? */
        !           151: #define ISSYSSDP(s)    (!ISMEMSDP(s) && !ISGDP(s))
        !           152: 
        !           153: /*
        !           154:  * Software definitions are in this convenient format,
        !           155:  * which are translated into inconvenient segment descriptors
        !           156:  * when needed to be used by the 386 hardware
        !           157:  */
        !           158: 
        !           159: struct soft_segment_descriptor {
        !           160:        unsigned ssd_base ;             /* segment base address  */
        !           161:        unsigned ssd_limit ;            /* segment extent */
        !           162:        unsigned ssd_type:5 ;           /* segment type */
        !           163:        unsigned ssd_dpl:2 ;            /* segment descriptor priority level */
        !           164:        unsigned ssd_p:1 ;              /* segment descriptor present */
        !           165:        unsigned ssd_xx:4 ;             /* unused */
        !           166:        unsigned ssd_xx1:2 ;            /* unused */
        !           167:        unsigned ssd_def32:1 ;          /* default 32 vs 16 bit size */
        !           168:        unsigned ssd_gran:1 ;           /* limit granularity (byte/page units)*/
        !           169: };
        !           170: 
        !           171: extern ssdtosd() ;     /* to decode a ssd */
        !           172: extern sdtossd() ;     /* to encode a sd */
        !           173: 
        !           174: /*
        !           175:  * region descriptors, used to load gdt/idt tables before segments yet exist
        !           176:  */
        !           177: struct region_descriptor {
        !           178:        unsigned rd_limit:16 ;          /* segment extent */
        !           179:        char *rd_base;                  /* base address  */
        !           180: };
        !           181: 
        !           182: /*
        !           183:  * Segment Protection Exception code bits
        !           184:  */
        !           185: 
        !           186: #define        SEGEX_EXT       0x01    /* recursive or externally induced */
        !           187: #define        SEGEX_IDT       0x02    /* interrupt descriptor table */
        !           188: #define        SEGEX_TI        0x04    /* local descriptor table */
        !           189:                                /* other bits are affected descriptor index */
        !           190: #define SEGEX_IDX(s)   ((s)>>3)&0x1fff)

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