2 * Copyright (c) 1989, 1990 William F. Jolitz
3 * Copyright (c) 1990 The Regents of the University of California.
6 * This code is derived from software contributed to Berkeley by
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19 * This product includes software developed by the University of
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25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37 * from: @(#)segments.h 7.1 (Berkeley) 5/9/91
42 * 386 Segmentation Data Structures and definitions
43 * William F. Jolitz (william@ernie.berkeley.edu) 6/20/1989
50 #define ISPL(s) ((s)&3) /* what is the priority level of a selector */
51 #define SEL_KPL 0 /* kernel priority level */
52 #define SEL_UPL 3 /* user priority level */
53 #define ISLDT(s) ((s)&SEL_LDT) /* is it local or global */
54 #define SEL_LDT 4 /* local descriptor table */
55 #define IDXSEL(s) (((s)>>3) & 0x1fff) /* index of selector */
56 #define LSEL(s,r) (((s)<<3) | SEL_LDT | r) /* a local selector */
57 #define GSEL(s,r) (((s)<<3) | r) /* a global selector */
60 * Memory and System segment descriptors
62 struct segment_descriptor {
63 unsigned sd_lolimit:16 ; /* segment extent (lsb) */
64 unsigned sd_lobase:24 ; /* segment base address (lsb) */
65 unsigned sd_type:5 ; /* segment type */
66 unsigned sd_dpl:2 ; /* segment descriptor priority level */
67 unsigned sd_p:1 ; /* segment descriptor present */
68 unsigned sd_hilimit:4 ; /* segment extent (msb) */
69 unsigned sd_xx:2 ; /* unused */
70 unsigned sd_def32:1 ; /* default 32 vs 16 bit size */
71 unsigned sd_gran:1 ; /* limit granularity (byte/page units)*/
72 unsigned sd_hibase:8 ; /* segment base address (msb) */
76 * Gate descriptors (e.g. indirect descriptors)
78 struct gate_descriptor {
79 unsigned gd_looffset:16 ; /* gate offset (lsb) */
80 unsigned gd_selector:16 ; /* gate segment selector */
81 unsigned gd_stkcpy:5 ; /* number of stack wds to cpy */
82 unsigned gd_xx:3 ; /* unused */
83 unsigned gd_type:5 ; /* segment type */
84 unsigned gd_dpl:2 ; /* segment descriptor priority level */
85 unsigned gd_p:1 ; /* segment descriptor present */
86 unsigned gd_hioffset:16 ; /* gate offset (msb) */
93 struct segment_descriptor sd;
94 struct gate_descriptor gd;
97 /* system segments and gate types */
98 #define SDT_SYSNULL 0 /* system null */
99 #define SDT_SYS286TSS 1 /* system 286 TSS available */
100 #define SDT_SYSLDT 2 /* system local descriptor table */
101 #define SDT_SYS286BSY 3 /* system 286 TSS busy */
102 #define SDT_SYS286CGT 4 /* system 286 call gate */
103 #define SDT_SYSTASKGT 5 /* system task gate */
104 #define SDT_SYS286IGT 6 /* system 286 interrupt gate */
105 #define SDT_SYS286TGT 7 /* system 286 trap gate */
106 #define SDT_SYSNULL2 8 /* system null again */
107 #define SDT_SYS386TSS 9 /* system 386 TSS available */
108 #define SDT_SYSNULL3 10 /* system null again */
109 #define SDT_SYS386BSY 11 /* system 386 TSS busy */
110 #define SDT_SYS386CGT 12 /* system 386 call gate */
111 #define SDT_SYSNULL4 13 /* system null again */
112 #define SDT_SYS386IGT 14 /* system 386 interrupt gate */
113 #define SDT_SYS386TGT 15 /* system 386 trap gate */
115 /* memory segment types */
116 #define SDT_MEMRO 16 /* memory read only */
117 #define SDT_MEMROA 17 /* memory read only accessed */
118 #define SDT_MEMRW 18 /* memory read write */
119 #define SDT_MEMRWA 19 /* memory read write accessed */
120 #define SDT_MEMROD 20 /* memory read only expand dwn limit */
121 #define SDT_MEMRODA 21 /* memory read only expand dwn limit accessed */
122 #define SDT_MEMRWD 22 /* memory read write expand dwn limit */
123 #define SDT_MEMRWDA 23 /* memory read write expand dwn limit acessed */
124 #define SDT_MEME 24 /* memory execute only */
125 #define SDT_MEMEA 25 /* memory execute only accessed */
126 #define SDT_MEMER 26 /* memory execute read */
127 #define SDT_MEMERA 27 /* memory execute read accessed */
128 #define SDT_MEMEC 28 /* memory execute only conforming */
129 #define SDT_MEMEAC 29 /* memory execute only accessed conforming */
130 #define SDT_MEMERC 30 /* memory execute read conforming */
131 #define SDT_MEMERAC 31 /* memory execute read accessed conforming */
133 /* is memory segment descriptor pointer ? */
134 #define ISMEMSDP(s) ((s->d_type) >= SDT_MEMRO && (s->d_type) <= SDT_MEMERAC)
136 /* is 286 gate descriptor pointer ? */
137 #define IS286GDP(s) (((s->d_type) >= SDT_SYS286CGT \
138 && (s->d_type) < SDT_SYS286TGT))
140 /* is 386 gate descriptor pointer ? */
141 #define IS386GDP(s) (((s->d_type) >= SDT_SYS386CGT \
142 && (s->d_type) < SDT_SYS386TGT))
144 /* is gate descriptor pointer ? */
145 #define ISGDP(s) (IS286GDP(s) || IS386GDP(s))
147 /* is segment descriptor pointer ? */
148 #define ISSDP(s) (ISMEMSDP(s) || !ISGDP(s))
150 /* is system segment descriptor pointer ? */
151 #define ISSYSSDP(s) (!ISMEMSDP(s) && !ISGDP(s))
154 * Software definitions are in this convenient format,
155 * which are translated into inconvenient segment descriptors
156 * when needed to be used by the 386 hardware
159 struct soft_segment_descriptor {
160 unsigned ssd_base ; /* segment base address */
161 unsigned ssd_limit ; /* segment extent */
162 unsigned ssd_type:5 ; /* segment type */
163 unsigned ssd_dpl:2 ; /* segment descriptor priority level */
164 unsigned ssd_p:1 ; /* segment descriptor present */
165 unsigned ssd_xx:4 ; /* unused */
166 unsigned ssd_xx1:2 ; /* unused */
167 unsigned ssd_def32:1 ; /* default 32 vs 16 bit size */
168 unsigned ssd_gran:1 ; /* limit granularity (byte/page units)*/
171 extern ssdtosd() ; /* to decode a ssd */
172 extern sdtossd() ; /* to encode a sd */
175 * region descriptors, used to load gdt/idt tables before segments yet exist.
177 struct region_descriptor {
178 unsigned rd_limit:16; /* segment extent */
179 unsigned rd_base:32; /* base address */
183 * Segment Protection Exception code bits
186 #define SEGEX_EXT 0x01 /* recursive or externally induced */
187 #define SEGEX_IDT 0x02 /* interrupt descriptor table */
188 #define SEGEX_TI 0x04 /* local descriptor table */
189 /* other bits are affected descriptor index */
190 #define SEGEX_IDX(s) ((s)>>3)&0x1fff)
197 #define NRSVIDT 32 /* reserved entries for cpu exceptions */