+/*-
+ * 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.
+ *
+ * @(#)segments.h 7.1 (Berkeley) 5/9/91
+ */
+
+/*
+ * 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 ; /* 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 acessed */
+#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)*/
+};
+
+extern ssdtosd() ; /* to decode a ssd */
+extern sdtossd() ; /* to encode a sd */
+
+/*
+ * 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 */
+};
+
+/*
+ * 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
+ */
+
+#define NIDT 256
+#define NRSVIDT 32 /* reserved entries for cpu exceptions */
projects / unix-history / commitdiff