The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    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  * 4. Neither the name of the University nor the names of its contributors
   18  *    may be used to endorse or promote products derived from this software
   19  *    without specific prior written permission.
   20  *
   21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   31  * SUCH DAMAGE.
   32  *
   33  *      from: @(#)segments.h    7.1 (Berkeley) 5/9/91
   34  * $FreeBSD: releng/8.3/sys/i386/include/segments.h 227950 2011-11-24 19:02:04Z rstone $
   35  */
   36 
   37 #ifndef _MACHINE_SEGMENTS_H_
   38 #define _MACHINE_SEGMENTS_H_
   39 
   40 /*
   41  * 386 Segmentation Data Structures and definitions
   42  *      William F. Jolitz (william@ernie.berkeley.edu) 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 #ifdef XEN
   51 #define SEL_KPL 1               /* kernel priority level */
   52 #else
   53 #define SEL_KPL 0               /* kernel priority level */
   54 #endif
   55 #define SEL_UPL 3               /* user priority level */
   56 #define ISLDT(s)        ((s)&SEL_LDT)   /* is it local or global */
   57 #define SEL_LDT 4               /* local descriptor table */
   58 #define IDXSEL(s)       (((s)>>3) & 0x1fff)             /* index of selector */
   59 #define LSEL(s,r)       (((s)<<3) | SEL_LDT | r)        /* a local selector */
   60 #define GSEL(s,r)       (((s)<<3) | r)                  /* a global selector */
   61 
   62 /*
   63  * Memory and System segment descriptors
   64  */
   65 struct  segment_descriptor      {
   66         unsigned sd_lolimit:16 ;        /* segment extent (lsb) */
   67         unsigned sd_lobase:24 __packed; /* segment base address (lsb) */
   68         unsigned sd_type:5 ;            /* segment type */
   69         unsigned sd_dpl:2 ;             /* segment descriptor priority level */
   70         unsigned sd_p:1 ;               /* segment descriptor present */
   71         unsigned sd_hilimit:4 ;         /* segment extent (msb) */
   72         unsigned sd_xx:2 ;              /* unused */
   73         unsigned sd_def32:1 ;           /* default 32 vs 16 bit size */
   74         unsigned sd_gran:1 ;            /* limit granularity (byte/page units)*/
   75         unsigned sd_hibase:8 ;          /* segment base address  (msb) */
   76 } ;
   77 
   78 #define USD_GETBASE(sd)         (((sd)->sd_lobase) | (sd)->sd_hibase << 24) 
   79 #define USD_SETBASE(sd, b)      (sd)->sd_lobase = (b);  \
   80                                 (sd)->sd_hibase = ((b) >> 24);
   81 #define USD_GETLIMIT(sd)        (((sd)->sd_lolimit) | (sd)->sd_hilimit << 16)
   82 #define USD_SETLIMIT(sd, l)     (sd)->sd_lolimit = (l); \
   83                                 (sd)->sd_hilimit = ((l) >> 16);
   84 
   85 /*
   86  * Gate descriptors (e.g. indirect descriptors)
   87  */
   88 struct  gate_descriptor {
   89         unsigned gd_looffset:16 ;       /* gate offset (lsb) */
   90         unsigned gd_selector:16 ;       /* gate segment selector */
   91         unsigned gd_stkcpy:5 ;          /* number of stack wds to cpy */
   92         unsigned gd_xx:3 ;              /* unused */
   93         unsigned gd_type:5 ;            /* segment type */
   94         unsigned gd_dpl:2 ;             /* segment descriptor priority level */
   95         unsigned gd_p:1 ;               /* segment descriptor present */
   96         unsigned gd_hioffset:16 ;       /* gate offset (msb) */
   97 } ;
   98 
   99 /*
  100  * Generic descriptor
  101  */
  102 union   descriptor      {
  103         struct  segment_descriptor sd;
  104         struct  gate_descriptor gd;
  105 };
  106 
  107         /* system segments and gate types */
  108 #define SDT_SYSNULL      0      /* system null */
  109 #define SDT_SYS286TSS    1      /* system 286 TSS available */
  110 #define SDT_SYSLDT       2      /* system local descriptor table */
  111 #define SDT_SYS286BSY    3      /* system 286 TSS busy */
  112 #define SDT_SYS286CGT    4      /* system 286 call gate */
  113 #define SDT_SYSTASKGT    5      /* system task gate */
  114 #define SDT_SYS286IGT    6      /* system 286 interrupt gate */
  115 #define SDT_SYS286TGT    7      /* system 286 trap gate */
  116 #define SDT_SYSNULL2     8      /* system null again */
  117 #define SDT_SYS386TSS    9      /* system 386 TSS available */
  118 #define SDT_SYSNULL3    10      /* system null again */
  119 #define SDT_SYS386BSY   11      /* system 386 TSS busy */
  120 #define SDT_SYS386CGT   12      /* system 386 call gate */
  121 #define SDT_SYSNULL4    13      /* system null again */
  122 #define SDT_SYS386IGT   14      /* system 386 interrupt gate */
  123 #define SDT_SYS386TGT   15      /* system 386 trap gate */
  124 
  125         /* memory segment types */
  126 #define SDT_MEMRO       16      /* memory read only */
  127 #define SDT_MEMROA      17      /* memory read only accessed */
  128 #define SDT_MEMRW       18      /* memory read write */
  129 #define SDT_MEMRWA      19      /* memory read write accessed */
  130 #define SDT_MEMROD      20      /* memory read only expand dwn limit */
  131 #define SDT_MEMRODA     21      /* memory read only expand dwn limit accessed */
  132 #define SDT_MEMRWD      22      /* memory read write expand dwn limit */
  133 #define SDT_MEMRWDA     23      /* memory read write expand dwn limit accessed */
  134 #define SDT_MEME        24      /* memory execute only */
  135 #define SDT_MEMEA       25      /* memory execute only accessed */
  136 #define SDT_MEMER       26      /* memory execute read */
  137 #define SDT_MEMERA      27      /* memory execute read accessed */
  138 #define SDT_MEMEC       28      /* memory execute only conforming */
  139 #define SDT_MEMEAC      29      /* memory execute only accessed conforming */
  140 #define SDT_MEMERC      30      /* memory execute read conforming */
  141 #define SDT_MEMERAC     31      /* memory execute read accessed conforming */
  142 
  143 /*
  144  * Software definitions are in this convenient format,
  145  * which are translated into inconvenient segment descriptors
  146  * when needed to be used by the 386 hardware
  147  */
  148 
  149 struct  soft_segment_descriptor {
  150         unsigned ssd_base ;             /* segment base address  */
  151         unsigned ssd_limit ;            /* segment extent */
  152         unsigned ssd_type:5 ;           /* segment type */
  153         unsigned ssd_dpl:2 ;            /* segment descriptor priority level */
  154         unsigned ssd_p:1 ;              /* segment descriptor present */
  155         unsigned ssd_xx:4 ;             /* unused */
  156         unsigned ssd_xx1:2 ;            /* unused */
  157         unsigned ssd_def32:1 ;          /* default 32 vs 16 bit size */
  158         unsigned ssd_gran:1 ;           /* limit granularity (byte/page units)*/
  159 };
  160 
  161 /*
  162  * region descriptors, used to load gdt/idt tables before segments yet exist.
  163  */
  164 struct region_descriptor {
  165         unsigned rd_limit:16;           /* segment extent */
  166         unsigned rd_base:32 __packed;   /* base address  */
  167 };
  168 
  169 /*
  170  * Segment Protection Exception code bits
  171  */
  172 
  173 #define SEGEX_EXT       0x01    /* recursive or externally induced */
  174 #define SEGEX_IDT       0x02    /* interrupt descriptor table */
  175 #define SEGEX_TI        0x04    /* local descriptor table */
  176                                 /* other bits are affected descriptor index */
  177 #define SEGEX_IDX(s)    (((s)>>3)&0x1fff)
  178 
  179 /*
  180  * Size of IDT table
  181  */
  182 
  183 #define NIDT    256             /* 32 reserved, 0x80 syscall, most are h/w */
  184 #define NRSVIDT 32              /* reserved entries for cpu exceptions */
  185 
  186 /*
  187  * Entries in the Interrupt Descriptor Table (IDT)
  188  */
  189 #define IDT_DE          0       /* #DE: Divide Error */
  190 #define IDT_DB          1       /* #DB: Debug */
  191 #define IDT_NMI         2       /* Nonmaskable External Interrupt */
  192 #define IDT_BP          3       /* #BP: Breakpoint */
  193 #define IDT_OF          4       /* #OF: Overflow */
  194 #define IDT_BR          5       /* #BR: Bound Range Exceeded */
  195 #define IDT_UD          6       /* #UD: Undefined/Invalid Opcode */
  196 #define IDT_NM          7       /* #NM: No Math Coprocessor */
  197 #define IDT_DF          8       /* #DF: Double Fault */
  198 #define IDT_FPUGP       9       /* Coprocessor Segment Overrun */
  199 #define IDT_TS          10      /* #TS: Invalid TSS */
  200 #define IDT_NP          11      /* #NP: Segment Not Present */
  201 #define IDT_SS          12      /* #SS: Stack Segment Fault */
  202 #define IDT_GP          13      /* #GP: General Protection Fault */
  203 #define IDT_PF          14      /* #PF: Page Fault */
  204 #define IDT_MF          16      /* #MF: FPU Floating-Point Error */
  205 #define IDT_AC          17      /* #AC: Alignment Check */
  206 #define IDT_MC          18      /* #MC: Machine Check */
  207 #define IDT_XF          19      /* #XF: SIMD Floating-Point Exception */
  208 #define IDT_IO_INTS     NRSVIDT /* Base of IDT entries for I/O interrupts. */
  209 #define IDT_SYSCALL     0x80    /* System Call Interrupt Vector */
  210 #define IDT_DTRACE_RET  0x20    /* DTrace pid provider Interrupt Vector */
  211 
  212 /*
  213  * Entries in the Global Descriptor Table (GDT)
  214  * Note that each 4 entries share a single 32 byte L1 cache line.
  215  * Some of the fast syscall instructions require a specific order here.
  216  */
  217 #define GNULL_SEL       0       /* Null Descriptor */
  218 #define GPRIV_SEL       1       /* SMP Per-Processor Private Data */
  219 #define GUFS_SEL        2       /* User %fs Descriptor (order critical: 1) */
  220 #define GUGS_SEL        3       /* User %gs Descriptor (order critical: 2) */
  221 #define GCODE_SEL       4       /* Kernel Code Descriptor (order critical: 1) */
  222 #define GDATA_SEL       5       /* Kernel Data Descriptor (order critical: 2) */
  223 #define GUCODE_SEL      6       /* User Code Descriptor (order critical: 3) */
  224 #define GUDATA_SEL      7       /* User Data Descriptor (order critical: 4) */
  225 #define GBIOSLOWMEM_SEL 8       /* BIOS low memory access (must be entry 8) */
  226 #define GPROC0_SEL      9       /* Task state process slot zero and up */
  227 #define GLDT_SEL        10      /* Default User LDT */
  228 #define GUSERLDT_SEL    11      /* User LDT */
  229 #define GPANIC_SEL      12      /* Task state to consider panic from */
  230 #define GBIOSCODE32_SEL 13      /* BIOS interface (32bit Code) */
  231 #define GBIOSCODE16_SEL 14      /* BIOS interface (16bit Code) */
  232 #define GBIOSDATA_SEL   15      /* BIOS interface (Data) */
  233 #define GBIOSUTIL_SEL   16      /* BIOS interface (Utility) */
  234 #define GBIOSARGS_SEL   17      /* BIOS interface (Arguments) */
  235 #define GNDIS_SEL       18      /* For the NDIS layer */
  236 
  237 #ifdef XEN
  238 #define NGDT            9
  239 #else
  240 #define NGDT            19
  241 #endif
  242 
  243 /*
  244  * Entries in the Local Descriptor Table (LDT)
  245  */
  246 #define LSYS5CALLS_SEL  0       /* forced by intel BCS */
  247 #define LSYS5SIGR_SEL   1
  248 #define L43BSDCALLS_SEL 2       /* notyet */
  249 #define LUCODE_SEL      3
  250 #define LSOL26CALLS_SEL 4       /* Solaris >= 2.6 system call gate */
  251 #define LUDATA_SEL      5
  252 /* separate stack, es,fs,gs sels ? */
  253 /* #define      LPOSIXCALLS_SEL 5*/     /* notyet */
  254 #define LBSDICALLS_SEL  16      /* BSDI system call gate */
  255 #define NLDT            (LBSDICALLS_SEL + 1)
  256 
  257 #ifdef _KERNEL
  258 extern int      _default_ldt;
  259 #ifdef XEN
  260 extern struct proc_ldt default_proc_ldt;
  261 extern union descriptor *gdt;
  262 extern union descriptor *ldt;
  263 #else
  264 extern union descriptor gdt[];
  265 extern union descriptor ldt[NLDT];
  266 #endif
  267 extern struct soft_segment_descriptor gdt_segs[];
  268 extern struct gate_descriptor *idt;
  269 extern struct region_descriptor r_gdt, r_idt;
  270 
  271 void    lgdt(struct region_descriptor *rdp);
  272 void    sdtossd(struct segment_descriptor *sdp,
  273             struct soft_segment_descriptor *ssdp);
  274 void    ssdtosd(struct soft_segment_descriptor *ssdp,
  275             struct segment_descriptor *sdp);
  276 #endif /* _KERNEL */
  277 
  278 #endif /* !_MACHINE_SEGMENTS_H_ */

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