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

     /*      $NetBSD: segments.h,v 1.70 2022/05/18 13:56:32 andvar Exp $     */
     
     /*-
      * 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. 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.
     *
     *      @(#)segments.h  7.1 (Berkeley) 5/9/91
     */
    
    /*-
     * Copyright (c) 1995, 1997
     *      Charles M. Hannum.  All rights reserved.
     * Copyright (c) 1989, 1990 William F. Jolitz
     *
     * 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.
     *
     *      @(#)segments.h  7.1 (Berkeley) 5/9/91
     */
    
    /*
     * 386 Segmentation Data Structures and definitions
     *      William F. Jolitz (william@ernie.berkeley.edu) 6/20/1989
     */
    
    #ifndef _I386_SEGMENTS_H_
    #define _I386_SEGMENTS_H_
    #ifdef _KERNEL_OPT
    #include "opt_xen.h"
    #endif
    
    /*
     * Selectors
     */
    
    #define ISPL(s)         ((s) & SEL_RPL) /* what is the priority level of a selector */
    #ifndef XENPV
    #define SEL_KPL         0               /* kernel privilege level */
    #else
    #define SEL_XEN         0               /* Xen privilege level */
    #define SEL_KPL         1               /* kernel privilege level */
    #endif /* XENPV */
    #define SEL_UPL         3               /* user privilege level */
    #define SEL_RPL         3               /* requester's privilege level mask */
   #ifdef XENPV
   #define CHK_UPL         2               /* user privilege level mask */
   #else
   #define CHK_UPL         SEL_RPL
   #endif /* XENPV */
   #define ISLDT(s)        ((s) & SEL_LDT) /* is it local or global */
   #define SEL_LDT         4               /* local descriptor table */
   
   #define IOPL_KPL        SEL_KPL
   
   /* Dynamically allocated TSSs and LDTs start (byte offset) */
   #define DYNSEL_START    (NGDT << 3)
   
   #define IDXSEL(s)       (((s) >> 3) & 0x1fff)           /* index of selector */
   #define IDXSELN(s)      (((s) >> 3))                    /* index of selector */
   #define IDXDYNSEL(s)    ((((s) & ~SEL_RPL) - DYNSEL_START) >> 3)
   
   #define GSEL(s,r)       (((s) << 3) | r)                /* a global selector */
   #define GSYSSEL(s,r)    GSEL(s,r)                       /* compat with amd64 */
   #define GDYNSEL(s,r)    ((((s) << 3) + DYNSEL_START) | r | SEL_KPL)
   
   #define LSEL(s,r)       (((s) << 3) | r | SEL_LDT)      /* a local selector */
   
   #define USERMODE(c)             (ISPL(c) == SEL_UPL)
   #define KERNELMODE(c)           (ISPL(c) == SEL_KPL)
   
   #ifndef _LOCORE
   
   #if __GNUC__ == 2 && __GNUC_MINOR__ < 7
   #pragma pack(1)
   #endif
   
   /*
    * Memory and System segment descriptors (both 8 bytes).
    */
   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) */
           unsigned sd_hibase:8;           /* segment base address (msb) */
   } __packed;
   
   /*
    * Gate descriptors (8 bytes).
    */
   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;
   
   /*
    * Xen-specific?
    */
   struct ldt_descriptor {
           __vaddr_t ld_base;
           uint32_t ld_entries;
   } __packed;
   
   /*
    * Generic descriptor (8 bytes).
    */
   union descriptor {
           struct segment_descriptor sd;
           struct gate_descriptor gd;
           struct ldt_descriptor ld;
           uint32_t raw[2];
           uint64_t raw64;
   } __packed;
   
   /*
    * 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;            /* base address  */
   } __packed;
   
   #if __GNUC__ == 2 && __GNUC_MINOR__ < 7
   #pragma pack(4)
   #endif
   
   #ifdef _KERNEL
   #ifdef XENPV
   typedef struct trap_info idt_descriptor_t;
   #else
   typedef struct gate_descriptor idt_descriptor_t; 
   #endif /* XENPV */
   extern union descriptor *gdtstore, *ldtstore;
   
   void setgate(struct gate_descriptor *, void *, int, int, int, int);
   void set_idtgate(idt_descriptor_t *, void *, int, int, int, int);
   void unset_idtgate(idt_descriptor_t *);
   void setregion(struct region_descriptor *, void *, size_t);
   void setsegment(struct segment_descriptor *, const void *, size_t, int, int,
       int, int);
   void unsetgate(struct gate_descriptor *);
   void update_descriptor(union descriptor *, union descriptor *);
   
   struct idt_vec;
   void idt_vec_reserve(struct idt_vec *, int);
   int idt_vec_alloc(struct idt_vec *, int, int);
   void idt_vec_set(struct idt_vec *, int, void (*)(void));
   void idt_vec_free(struct idt_vec *, int);
   void idt_vec_init_cpu_md(struct idt_vec *, cpuid_t);
   bool idt_vec_is_pcpu(void);
   struct idt_vec* idt_vec_ref(struct idt_vec *);
   
   
   #endif /* _KERNEL */
   
   #endif /* !_LOCORE */
   
   /* 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 */
   
   #define SDTYPE(p)       (((const struct segment_descriptor *)(p))->sd_type)
   /* is memory segment descriptor pointer ? */
   #define ISMEMSDP(s)     (SDTYPE(s) >= SDT_MEMRO && \
                            SDTYPE(s) <= SDT_MEMERAC)
   
   /* is 286 gate descriptor pointer ? */
   #define IS286GDP(s)     (SDTYPE(s) >= SDT_SYS286CGT && \
                            SDTYPE(s) < SDT_SYS286TGT)
   
   /* is 386 gate descriptor pointer ? */
   #define IS386GDP(s)     (SDTYPE(s) >= SDT_SYS386CGT && \
                            SDTYPE(s) < 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))
   
   /*
    * 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 */
   
   /*
    * Entries in the Interrupt Descriptor Table (IDT)
    */
   #define NIDT    256
   #define NRSVIDT 32              /* reserved entries for CPU exceptions */
   
   /*
    * Entries in the Global Descriptor Table (GDT).
    *
    * NB: If you change GBIOSCODE/GBIOSDATA, you *must* rebuild arch/i386/
    * bioscall/biostramp.inc, as that relies on GBIOSCODE/GBIOSDATA and a
    * normal kernel build does not rebuild it (it's merely included whole-
    * sale from i386/bioscall.s)
    *
    * Also, note that the GEXTBIOSDATA_SEL selector is special, as it maps
    * to the value 0x0040 (when created as a KPL global selector).  Some
    * BIOSes reference the extended BIOS data area at segment 0040 in a non
    * relocatable fashion (even when in protected mode); mapping the zero page
    * via the GEXTBIOSDATA_SEL allows these buggy BIOSes to continue to work
    * under NetBSD.
    *
    * The order if the first 5 descriptors is special; the sysenter/sysexit
    * instructions depend on them.
    */
   #define GNULL_SEL       0       /* Null descriptor */
   #define GCODE_SEL       1       /* Kernel code descriptor */
   #define GDATA_SEL       2       /* Kernel data descriptor */
   #define GUCODE_SEL      3       /* User code descriptor */
   #define GUDATA_SEL      4       /* User data descriptor */
   #define GLDT_SEL        5       /* Default LDT descriptor */
   #define GCPU_SEL        6       /* per-CPU segment */
   #define GEXTBIOSDATA_SEL 8      /* magic to catch BIOS refs to EBDA */
   #define GAPM32CODE_SEL  9       /* 3 APM segments must be consecutive */
   #define GAPM16CODE_SEL  10      /* and in the specified order: code32 */
   #define GAPMDATA_SEL    11      /* code16 and then data per APM spec */
   #define GBIOSCODE_SEL   12
   #define GBIOSDATA_SEL   13
   #define GPNPBIOSCODE_SEL 14
   #define GPNPBIOSDATA_SEL 15
   #define GPNPBIOSSCRATCH_SEL 16
   #define GPNPBIOSTRAMP_SEL 17
   #define GTRAPTSS_SEL    18
   #define GIPITSS_SEL     19
   #define GUCODEBIG_SEL   20      /* User code with executable stack */
   #define GUFS_SEL        21      /* Per-thread %fs */
   #define GUGS_SEL        22      /* Per-thread %gs */
   #define NGDT            23
   
   /*
    * Entries in the Local Descriptor Table (LDT).
    * DO NOT ADD KERNEL DATA/CODE SEGMENTS TO THIS TABLE.
    */
   #define LSYS5CALLS_SEL  0       /* iBCS system call gate */
   #define LSYS5SIGR_SEL   1       /* iBCS sigreturn gate */
   #define LUCODE_SEL      2       /* User code descriptor */
   #define LUDATA_SEL      3       /* User data descriptor */
   #define LSOL26CALLS_SEL 4       /* Solaris 2.6 system call gate */
   #define LUCODEBIG_SEL   5       /* User code with executable stack */
   #define LBSDICALLS_SEL  16      /* BSDI system call gate */
   #define NLDT            17
   
   #endif /* _I386_SEGMENTS_H_ */

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