FreeBSD/Linux Kernel Cross Reference
sys/i386/include/segments.h

     /*-
      * Copyright (c) 1989, 1990 William F. Jolitz
      * Copyright (c) 1990 The Regents of the University of California.
      * All rights reserved.
      *
      * This code is derived from software contributed to Berkeley by
      * William Jolitz.
      *
      * 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. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University 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 REGENTS 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 REGENTS 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.
     *
     *      from: @(#)segments.h    7.1 (Berkeley) 5/9/91
     * $FreeBSD$
     */
    
    #ifndef _MACHINE_SEGMENTS_H_
    #define _MACHINE_SEGMENTS_H_
    
    #include <machine/globals.h>
    
    /*
     * 386 Segmentation Data Structures and definitions
     *      William F. Jolitz (william@ernie.berkeley.edu) 6/20/1989
     */
    
    /*
     * Selectors
     */
    
    #define ISPL(s) ((s)&3)         /* what is the priority level of a selector */
    #define SEL_KPL 0               /* kernel priority level */
    #define SEL_UPL 3               /* user priority level */
    #define ISLDT(s)        ((s)&SEL_LDT)   /* is it local or global */
    #define SEL_LDT 4               /* local descriptor table */
    #define IDXSEL(s)       (((s)>>3) & 0x1fff)             /* index of selector */
    #define LSEL(s,r)       (((s)<<3) | SEL_LDT | r)        /* a local selector */
    #define GSEL(s,r)       (((s)<<3) | r)                  /* a global selector */
    
    /*
     * Memory and System segment descriptors
     */
    struct  segment_descriptor      {
            unsigned sd_lolimit:16 ;        /* segment extent (lsb) */
            unsigned sd_lobase:24 __attribute__ ((packed));
                                            /* segment base address (lsb) */
            unsigned sd_type:5 ;            /* segment type */
            unsigned sd_dpl:2 ;             /* segment descriptor priority level */
            unsigned sd_p:1 ;               /* segment descriptor present */
            unsigned sd_hilimit:4 ;         /* segment extent (msb) */
            unsigned sd_xx:2 ;              /* unused */
            unsigned sd_def32:1 ;           /* default 32 vs 16 bit size */
            unsigned sd_gran:1 ;            /* limit granularity (byte/page units)*/
            unsigned sd_hibase:8 ;          /* segment base address  (msb) */
    } ;
    
    /*
     * Gate descriptors (e.g. indirect descriptors)
     */
    struct  gate_descriptor {
            unsigned gd_looffset:16 ;       /* gate offset (lsb) */
            unsigned gd_selector:16 ;       /* gate segment selector */
            unsigned gd_stkcpy:5 ;          /* number of stack wds to cpy */
            unsigned gd_xx:3 ;              /* unused */
            unsigned gd_type:5 ;            /* segment type */
            unsigned gd_dpl:2 ;             /* segment descriptor priority level */
            unsigned gd_p:1 ;               /* segment descriptor present */
            unsigned gd_hioffset:16 ;       /* gate offset (msb) */
    } ;
    
    /*
     * Generic descriptor
     */
    union   descriptor      {
            struct  segment_descriptor sd;
           struct  gate_descriptor gd;
   };
   
           /* system segments and gate types */
   #define SDT_SYSNULL      0      /* system null */
   #define SDT_SYS286TSS    1      /* system 286 TSS available */
   #define SDT_SYSLDT       2      /* system local descriptor table */
   #define SDT_SYS286BSY    3      /* system 286 TSS busy */
   #define SDT_SYS286CGT    4      /* system 286 call gate */
   #define SDT_SYSTASKGT    5      /* system task gate */
   #define SDT_SYS286IGT    6      /* system 286 interrupt gate */
   #define SDT_SYS286TGT    7      /* system 286 trap gate */
   #define SDT_SYSNULL2     8      /* system null again */
   #define SDT_SYS386TSS    9      /* system 386 TSS available */
   #define SDT_SYSNULL3    10      /* system null again */
   #define SDT_SYS386BSY   11      /* system 386 TSS busy */
   #define SDT_SYS386CGT   12      /* system 386 call gate */
   #define SDT_SYSNULL4    13      /* system null again */
   #define SDT_SYS386IGT   14      /* system 386 interrupt gate */
   #define SDT_SYS386TGT   15      /* system 386 trap gate */
   
           /* memory segment types */
   #define SDT_MEMRO       16      /* memory read only */
   #define SDT_MEMROA      17      /* memory read only accessed */
   #define SDT_MEMRW       18      /* memory read write */
   #define SDT_MEMRWA      19      /* memory read write accessed */
   #define SDT_MEMROD      20      /* memory read only expand dwn limit */
   #define SDT_MEMRODA     21      /* memory read only expand dwn limit accessed */
   #define SDT_MEMRWD      22      /* memory read write expand dwn limit */
   #define SDT_MEMRWDA     23      /* memory read write expand dwn limit accessed */
   #define SDT_MEME        24      /* memory execute only */
   #define SDT_MEMEA       25      /* memory execute only accessed */
   #define SDT_MEMER       26      /* memory execute read */
   #define SDT_MEMERA      27      /* memory execute read accessed */
   #define SDT_MEMEC       28      /* memory execute only conforming */
   #define SDT_MEMEAC      29      /* memory execute only accessed conforming */
   #define SDT_MEMERC      30      /* memory execute read conforming */
   #define SDT_MEMERAC     31      /* memory execute read accessed conforming */
   
   /* is memory segment descriptor pointer ? */
   #define ISMEMSDP(s)     ((s->d_type) >= SDT_MEMRO && (s->d_type) <= SDT_MEMERAC)
   
   /* is 286 gate descriptor pointer ? */
   #define IS286GDP(s)     (((s->d_type) >= SDT_SYS286CGT \
                                    && (s->d_type) < SDT_SYS286TGT))
   
   /* is 386 gate descriptor pointer ? */
   #define IS386GDP(s)     (((s->d_type) >= SDT_SYS386CGT \
                                   && (s->d_type) < SDT_SYS386TGT))
   
   /* is gate descriptor pointer ? */
   #define ISGDP(s)        (IS286GDP(s) || IS386GDP(s))
   
   /* is segment descriptor pointer ? */
   #define ISSDP(s)        (ISMEMSDP(s) || !ISGDP(s))
   
   /* is system segment descriptor pointer ? */
   #define ISSYSSDP(s)     (!ISMEMSDP(s) && !ISGDP(s))
   
   /*
    * Software definitions are in this convenient format,
    * which are translated into inconvenient segment descriptors
    * when needed to be used by the 386 hardware
    */
   
   struct  soft_segment_descriptor {
           unsigned ssd_base ;             /* segment base address  */
           unsigned ssd_limit ;            /* segment extent */
           unsigned ssd_type:5 ;           /* segment type */
           unsigned ssd_dpl:2 ;            /* segment descriptor priority level */
           unsigned ssd_p:1 ;              /* segment descriptor present */
           unsigned ssd_xx:4 ;             /* unused */
           unsigned ssd_xx1:2 ;            /* unused */
           unsigned ssd_def32:1 ;          /* default 32 vs 16 bit size */
           unsigned ssd_gran:1 ;           /* limit granularity (byte/page units)*/
   };
   
   /*
    * region descriptors, used to load gdt/idt tables before segments yet exist.
    */
   struct region_descriptor {
           unsigned rd_limit:16;                           /* segment extent */
           unsigned rd_base:32 __attribute__ ((packed));   /* base address  */
   };
   
   /*
    * Segment Protection Exception code bits
    */
   
   #define SEGEX_EXT       0x01    /* recursive or externally induced */
   #define SEGEX_IDT       0x02    /* interrupt descriptor table */
   #define SEGEX_TI        0x04    /* local descriptor table */
                                   /* other bits are affected descriptor index */
   #define SEGEX_IDX(s)    ((s)>>3)&0x1fff)
   
   /*
    * Size of IDT table
    */
   
   #if defined(SMP) || defined(APIC_IO)
   #define NIDT    256             /* we use them all */
   #else
   #define NIDT    129             /* 32 reserved, 16 h/w, 0 s/w, linux's 0x80 */
   #endif /* SMP || APIC_IO */
   #define NRSVIDT 32              /* reserved entries for cpu exceptions */
   
   /*
    * Entries in the Global Descriptor Table (GDT)
    */
   #define GNULL_SEL       0       /* Null Descriptor */
   #define GCODE_SEL       1       /* Kernel Code Descriptor */
   #define GDATA_SEL       2       /* Kernel Data Descriptor */
   #define GPRIV_SEL       3       /* SMP Per-Processor Private Data */
   #define GPROC0_SEL      4       /* Task state process slot zero and up */
   #define GLDT_SEL        5       /* LDT - eventually one per process */
   #define GUSERLDT_SEL    6       /* User LDT */
   #define GTGATE_SEL      7       /* Process task switch gate */
   #define GBIOSLOWMEM_SEL 8       /* BIOS low memory access (must be entry 8) */
   #define GPANIC_SEL      9       /* Task state to consider panic from */
   #define GBIOSCODE32_SEL 10      /* BIOS interface (32bit Code) */
   #define GBIOSCODE16_SEL 11      /* BIOS interface (16bit Code) */
   #define GBIOSDATA_SEL   12      /* BIOS interface (Data) */
   #define GBIOSUTIL_SEL   13      /* BIOS interface (Utility) */
   #define GBIOSARGS_SEL   14      /* BIOS interface (Arguments) */
   
   #ifdef BDE_DEBUGGER
   #define NGDT            18      /* some of 11-17 are reserved for debugger */
   #else
   #define NGDT            15
   #endif
   
   /*
    * Entries in the Local Descriptor Table (LDT)
    */
   #define LSYS5CALLS_SEL  0       /* forced by intel BCS */
   #define LSYS5SIGR_SEL   1
   #define L43BSDCALLS_SEL 2       /* notyet */
   #define LUCODE_SEL      3
   #define LSOL26CALLS_SEL 4       /* Solaris >= 2.6 system call gate */
   #define LUDATA_SEL      5
   /* separate stack, es,fs,gs sels ? */
   /* #define      LPOSIXCALLS_SEL 5*/     /* notyet */
   #define LBSDICALLS_SEL  16      /* BSDI system call gate */
   #define NLDT            (LBSDICALLS_SEL + 1)
   
   #ifdef _KERNEL
   #ifndef currentldt
   extern int      currentldt;
   #endif
   extern int      _default_ldt;
   extern union descriptor gdt[];
   extern struct soft_segment_descriptor gdt_segs[];
   extern struct gate_descriptor *idt;
   extern union descriptor ldt[NLDT];
   
   void    lgdt            __P((struct region_descriptor *rdp));
   void    lidt            __P((struct region_descriptor *rdp));
   void    lldt            __P((u_short sel));
   void    sdtossd         __P((struct segment_descriptor *sdp,
                                struct soft_segment_descriptor *ssdp));
   void    ssdtosd         __P((struct soft_segment_descriptor *ssdp,
                                struct segment_descriptor *sdp));
   #endif /* _KERNEL */
   
   #endif /* !_MACHINE_SEGMENTS_H_ */

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