FreeBSD/Linux Kernel Cross Reference
sys/x86/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.
     * 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: releng/11.2/sys/x86/include/segments.h 331722 2018-03-29 02:50:57Z eadler $
     */
    
    #ifndef _X86_SEGMENTS_H_
    #define _X86_SEGMENTS_H_
    
    /*
     * X86 Segmentation Data Structures and definitions
     */
    
    /*
     * Selectors
     */
    #define SEL_RPL_MASK    3               /* requester priv level */
    #define ISPL(s)         ((s)&3)         /* 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 */
    
    /*
     * User segment descriptors (%cs, %ds etc for i386 apps. 64 bit wide)
     * For long-mode apps, %cs only has the conforming bit in sd_type, the sd_dpl,
     * sd_p, sd_l and sd_def32 which must be zero).  %ds only has sd_p.
     */
    struct segment_descriptor {
            unsigned sd_lolimit:16;         /* segment extent (lsb) */
            unsigned sd_lobase:24;          /* 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) */
    } __packed;
    
    struct user_segment_descriptor {
            unsigned sd_lolimit:16;         /* segment extent (lsb) */
            unsigned sd_lobase:24;          /* 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:1;               /* unused */
            unsigned sd_long:1;             /* long mode (cs only) */
            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) */
    } __packed;
    
    #define USD_GETBASE(sd)         (((sd)->sd_lobase) | (sd)->sd_hibase << 24)
    #define USD_SETBASE(sd, b)      (sd)->sd_lobase = (b);  \
                                    (sd)->sd_hibase = ((b) >> 24);
    #define USD_GETLIMIT(sd)        (((sd)->sd_lolimit) | (sd)->sd_hilimit << 16)
    #define USD_SETLIMIT(sd, l)     (sd)->sd_lolimit = (l); \
                                    (sd)->sd_hilimit = ((l) >> 16);
    
    #ifdef __i386__
    /*
     * 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) */
   } __packed;
   
   /*
    * Generic descriptor
    */
   union descriptor {
           struct segment_descriptor sd;
           struct gate_descriptor gd;
   };
   #else
   /*
    * Gate descriptors (e.g. indirect descriptors, trap, interrupt etc. 128 bit)
    * Only interrupt and trap gates have gd_ist.
    */
   struct gate_descriptor {
           uint64_t gd_looffset:16;        /* gate offset (lsb) */
           uint64_t gd_selector:16;        /* gate segment selector */
           uint64_t gd_ist:3;              /* IST table index */
           uint64_t gd_xx:5;               /* unused */
           uint64_t gd_type:5;             /* segment type */
           uint64_t gd_dpl:2;              /* segment descriptor priority level */
           uint64_t gd_p:1;                /* segment descriptor present */
           uint64_t gd_hioffset:48;        /* gate offset (msb) */
           uint64_t sd_xx1:32;
   } __packed;
   
   /*
    * Generic descriptor
    */
   union descriptor {
           struct user_segment_descriptor sd;
           struct gate_descriptor gd;
   };
   #endif
   
           /* 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_SYSTSS       9      /* system available 64 bit TSS */
   #define SDT_SYSNULL3    10      /* system null again */
   #define SDT_SYS386BSY   11      /* system 386 TSS busy */
   #define SDT_SYSBSY      11      /* system busy 64 bit TSS */
   #define SDT_SYS386CGT   12      /* system 386 call gate */
   #define SDT_SYSCGT      12      /* system 64 bit call gate */
   #define SDT_SYSNULL4    13      /* system null again */
   #define SDT_SYS386IGT   14      /* system 386 interrupt gate */
   #define SDT_SYSIGT      14      /* system 64 bit interrupt gate */
   #define SDT_SYS386TGT   15      /* system 386 trap gate */
   #define SDT_SYSTGT      15      /* system 64 bit 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 */
   
   /*
    * Size of IDT table
    */
   #define NIDT            256     /* 32 reserved, 0x80 syscall, most are h/w */
   #define NRSVIDT         32      /* reserved entries for cpu exceptions */
   
   /*
    * Entries in the Interrupt Descriptor Table (IDT)
    */
   #define IDT_DE          0       /* #DE: Divide Error */
   #define IDT_DB          1       /* #DB: Debug */
   #define IDT_NMI         2       /* Nonmaskable External Interrupt */
   #define IDT_BP          3       /* #BP: Breakpoint */
   #define IDT_OF          4       /* #OF: Overflow */
   #define IDT_BR          5       /* #BR: Bound Range Exceeded */
   #define IDT_UD          6       /* #UD: Undefined/Invalid Opcode */
   #define IDT_NM          7       /* #NM: No Math Coprocessor */
   #define IDT_DF          8       /* #DF: Double Fault */
   #define IDT_FPUGP       9       /* Coprocessor Segment Overrun */
   #define IDT_TS          10      /* #TS: Invalid TSS */
   #define IDT_NP          11      /* #NP: Segment Not Present */
   #define IDT_SS          12      /* #SS: Stack Segment Fault */
   #define IDT_GP          13      /* #GP: General Protection Fault */
   #define IDT_PF          14      /* #PF: Page Fault */
   #define IDT_MF          16      /* #MF: FPU Floating-Point Error */
   #define IDT_AC          17      /* #AC: Alignment Check */
   #define IDT_MC          18      /* #MC: Machine Check */
   #define IDT_XF          19      /* #XF: SIMD Floating-Point Exception */
   #define IDT_IO_INTS     NRSVIDT /* Base of IDT entries for I/O interrupts. */
   #define IDT_SYSCALL     0x80    /* System Call Interrupt Vector */
   #define IDT_DTRACE_RET  0x92    /* DTrace pid provider Interrupt Vector */
   #define IDT_EVTCHN      0x93    /* Xen HVM Event Channel Interrupt Vector */
   
   #if defined(__i386__)
   /*
    * Entries in the Global Descriptor Table (GDT)
    * Note that each 4 entries share a single 32 byte L1 cache line.
    * Some of the fast syscall instructions require a specific order here.
    */
   #define GNULL_SEL       0       /* Null Descriptor */
   #define GPRIV_SEL       1       /* SMP Per-Processor Private Data */
   #define GUFS_SEL        2       /* User %fs Descriptor (order critical: 1) */
   #define GUGS_SEL        3       /* User %gs Descriptor (order critical: 2) */
   #define GCODE_SEL       4       /* Kernel Code Descriptor (order critical: 1) */
   #define GDATA_SEL       5       /* Kernel Data Descriptor (order critical: 2) */
   #define GUCODE_SEL      6       /* User Code Descriptor (order critical: 3) */
   #define GUDATA_SEL      7       /* User Data Descriptor (order critical: 4) */
   #define GBIOSLOWMEM_SEL 8       /* BIOS low memory access (must be entry 8) */
   #define GPROC0_SEL      9       /* Task state process slot zero and up */
   #define GLDT_SEL        10      /* Default User LDT */
   #define GUSERLDT_SEL    11      /* User LDT */
   #define GPANIC_SEL      12      /* Task state to consider panic from */
   #define GBIOSCODE32_SEL 13      /* BIOS interface (32bit Code) */
   #define GBIOSCODE16_SEL 14      /* BIOS interface (16bit Code) */
   #define GBIOSDATA_SEL   15      /* BIOS interface (Data) */
   #define GBIOSUTIL_SEL   16      /* BIOS interface (Utility) */
   #define GBIOSARGS_SEL   17      /* BIOS interface (Arguments) */
   #define GNDIS_SEL       18      /* For the NDIS layer */
   #define NGDT            19
   
   /*
    * 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)
   
   #else /* !__i386__ */
   /*
    * Entries in the Global Descriptor Table (GDT)
    */
   #define GNULL_SEL       0       /* Null Descriptor */
   #define GNULL2_SEL      1       /* Null Descriptor */
   #define GUFS32_SEL      2       /* User 32 bit %fs Descriptor */
   #define GUGS32_SEL      3       /* User 32 bit %gs Descriptor */
   #define GCODE_SEL       4       /* Kernel Code Descriptor */
   #define GDATA_SEL       5       /* Kernel Data Descriptor */
   #define GUCODE32_SEL    6       /* User 32 bit code Descriptor */
   #define GUDATA_SEL      7       /* User 32/64 bit Data Descriptor */
   #define GUCODE_SEL      8       /* User 64 bit Code Descriptor */
   #define GPROC0_SEL      9       /* TSS for entering kernel etc */
   /* slot 10 is second half of GPROC0_SEL */
   #define GUSERLDT_SEL    11      /* LDT */
   /* slot 12 is second half of GUSERLDT_SEL */
   #define NGDT            13
   #endif /* __i386__ */
   
   #endif /* !_X86_SEGMENTS_H_ */

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