1/* $OpenBSD: segments.h,v 1.28 2020/09/24 11:36:50 deraadt Exp $ */
2/* $NetBSD: segments.h,v 1.23 1996/02/01 22:31:03 mycroft Exp $ */
3
4/*-
5 * Copyright (c) 1995 Charles M. Hannum. All rights reserved.
6 * Copyright (c) 1989, 1990 William F. Jolitz
7 * Copyright (c) 1990 The Regents of the University of California.
8 * All rights reserved.
9 *
10 * This code is derived from software contributed to Berkeley by
11 * William Jolitz.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. Neither the name of the University nor the names of its contributors
22 * may be used to endorse or promote products derived from this software
23 * without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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
35 * SUCH DAMAGE.
36 *
37 * @(#)segments.h 7.1 (Berkeley) 5/9/91
38 */
39
40/*
41 * 386 Segmentation Data Structures and definitions
42 * William F. Jolitz (william@ernie.berkeley.edu) 6/20/1989
43 */
44
45#ifndef _MACHINE_SEGMENTS_H_
46#define _MACHINE_SEGMENTS_H_
47
48/*
49 * Selectors
50 */
51
52#define ISPL(s) ((s) & SEL_RPL) /* what is the priority level of a selector */
53#define SEL_KPL 0 /* kernel privilege level */
54#define SEL_UPL 3 /* user privilege level */
55#define SEL_RPL 3 /* requester's privilege level mask */
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 GSEL(s,r) (((s) << 3) | r) /* a global selector */
60#define LSEL(s,r) (((s) << 3) | r | SEL_LDT) /* a local selector */
61
62#define USERMODE(c, f) (ISPL(c) == SEL_UPL)
63#define KERNELMODE(c, f) (ISPL(c) == SEL_KPL)
64
65#ifndef _LOCORE
66
67/*
68 * Memory and System segment descriptors
69 */
70struct segment_descriptor {
71 unsigned sd_lolimit:16; /* segment extent (lsb) */
72 unsigned sd_lobase:24; /* segment base address (lsb) */
73 unsigned sd_type:5; /* segment type */
74 unsigned sd_dpl:2; /* segment descriptor priority level */
75 unsigned sd_p:1; /* segment descriptor present */
76 unsigned sd_hilimit:4; /* segment extent (msb) */
77 unsigned sd_xx:2; /* unused */
78 unsigned sd_def32:1; /* default 32 vs 16 bit size */
79 unsigned sd_gran:1; /* limit granularity (byte/page) */
80 unsigned sd_hibase:8; /* segment base address (msb) */
81} __packed;
82
83/*
84 * Gate descriptors (e.g. indirect descriptors)
85 */
86struct gate_descriptor {
87 unsigned gd_looffset:16; /* gate offset (lsb) */
88 unsigned gd_selector:16; /* gate segment selector */
89 unsigned gd_stkcpy:5; /* number of stack wds to cpy */
90 unsigned gd_xx:3; /* unused */
91 unsigned gd_type:5; /* segment type */
92 unsigned gd_dpl:2; /* segment descriptor priority level */
93 unsigned gd_p:1; /* segment descriptor present */
94 unsigned gd_hioffset:16; /* gate offset (msb) */
95} __packed;
96
97/*
98 * Generic descriptor
99 */
100union descriptor {
101 struct segment_descriptor sd;
102 struct gate_descriptor gd;
103} __packed;
104
105/*
106 * region descriptors, used to load gdt/idt tables before segments yet exist.
107 */
108struct region_descriptor {
109 unsigned rd_limit:16; /* segment extent */
110 unsigned rd_base:32; /* base address */
111} __packed;
112
113#ifdef _KERNEL
114extern union descriptor *gdt;
115extern struct gate_descriptor idt_region[];
116extern struct gate_descriptor *idt;
117
118#define SEGDESC_LIMIT(sd) (ptoa(((sd).sd_hilimit << 16) | (sd).sd_lolimit))
119
120void setgate(struct gate_descriptor *, void *, int, int, int, int);
121void setregion(struct region_descriptor *, void *, size_t);
122void setsegment(struct segment_descriptor *, void *, size_t, int, int,
123 int, int);
124void initcodesegment(struct segment_descriptor *);
125void unsetgate(struct gate_descriptor *);
126void cpu_init_idt(void);
127
128int idt_vec_alloc(int, int);
129void idt_vec_set(int, void (*)(void));
130void idt_vec_free(int);
131
132#endif /* _KERNEL */
133
134#endif /* !_LOCORE */
135
136/* system segments and gate types */
137#define SDT_SYSNULL 0 /* system null */
138#define SDT_SYS286TSS 1 /* system 286 TSS available */
139#define SDT_SYSLDT 2 /* system local descriptor table */
140#define SDT_SYS286BSY 3 /* system 286 TSS busy */
141#define SDT_SYS286CGT 4 /* system 286 call gate */
142#define SDT_SYSTASKGT 5 /* system task gate */
143#define SDT_SYS286IGT 6 /* system 286 interrupt gate */
144#define SDT_SYS286TGT 7 /* system 286 trap gate */
145#define SDT_SYSNULL2 8 /* system null again */
146#define SDT_SYS386TSS 9 /* system 386 TSS available */
147#define SDT_SYSNULL3 10 /* system null again */
148#define SDT_SYS386BSY 11 /* system 386 TSS busy */
149#define SDT_SYS386CGT 12 /* system 386 call gate */
150#define SDT_SYSNULL4 13 /* system null again */
151#define SDT_SYS386IGT 14 /* system 386 interrupt gate */
152#define SDT_SYS386TGT 15 /* system 386 trap gate */
153
154/* memory segment types */
155#define SDT_MEMRO 16 /* memory read only */
156#define SDT_MEMROA 17 /* memory read only accessed */
157#define SDT_MEMRW 18 /* memory read write */
158#define SDT_MEMRWA 19 /* memory read write accessed */
159#define SDT_MEMROD 20 /* memory read only expand dwn limit */
160#define SDT_MEMRODA 21 /* memory read only expand dwn limit accessed */
161#define SDT_MEMRWD 22 /* memory read write expand dwn limit */
162#define SDT_MEMRWDA 23 /* memory read write expand dwn limit acessed */
163#define SDT_MEME 24 /* memory execute only */
164#define SDT_MEMEA 25 /* memory execute only accessed */
165#define SDT_MEMER 26 /* memory execute read */
166#define SDT_MEMERA 27 /* memory execute read accessed */
167#define SDT_MEMEC 28 /* memory execute only conforming */
168#define SDT_MEMEAC 29 /* memory execute only accessed conforming */
169#define SDT_MEMERC 30 /* memory execute read conforming */
170#define SDT_MEMERAC 31 /* memory execute read accessed conforming */
171
172/* is memory segment descriptor pointer ? */
173#define ISMEMSDP(s) ((s->d_type) >= SDT_MEMRO && \
174 (s->d_type) <= SDT_MEMERAC)
175
176/* is 286 gate descriptor pointer ? */
177#define IS286GDP(s) ((s->d_type) >= SDT_SYS286CGT && \
178 (s->d_type) < SDT_SYS286TGT)
179
180/* is 386 gate descriptor pointer ? */
181#define IS386GDP(s) ((s->d_type) >= SDT_SYS386CGT && \
182 (s->d_type) < SDT_SYS386TGT)
183
184/* is gate descriptor pointer ? */
185#define ISGDP(s) (IS286GDP(s) || IS386GDP(s))
186
187/* is segment descriptor pointer ? */
188#define ISSDP(s) (ISMEMSDP(s) || !ISGDP(s))
189
190/* is system segment descriptor pointer ? */
191#define ISSYSSDP(s) (!ISMEMSDP(s) && !ISGDP(s))
192
193/*
194 * Segment Protection Exception code bits
195 */
196#define SEGEX_EXT 0x01 /* recursive or externally induced */
197#define SEGEX_IDT 0x02 /* interrupt descriptor table */
198#define SEGEX_TI 0x04 /* local descriptor table */
199
200/*
201 * Entries in the Interrupt Descriptor Table (IDT)
202 */
203#define NIDT 256
204#define NRSVIDT 32 /* reserved entries for cpu exceptions */
205
206/*
207 * Entries in the Global Descriptor Table (GDT)
208 */
209#define GNULL_SEL 0 /* Null descriptor */
210#define GCODE_SEL 1 /* Kernel code descriptor */
211#define GDATA_SEL 2 /* Kernel data descriptor */
212#define GLDT_SEL 3 /* Default LDT descriptor (UNUSED) */
213#define GCPU_SEL 4 /* per-CPU segment */
214#define GUCODE_SEL 5 /* User code descriptor (a stack short) */
215#define GUDATA_SEL 6 /* User data descriptor */
216#define GAPM32CODE_SEL 7 /* 32 bit APM code descriptor */
217#define GAPM16CODE_SEL 8 /* 16 bit APM code descriptor */
218#define GAPMDATA_SEL 9 /* APM data descriptor */
219#define GICODE_SEL 10 /* Interrupt code descriptor (same as Kernel code) */
220#define GUFS_SEL 11 /* User per-thread (%fs) descriptor */
221#define GUGS_SEL 12 /* User per-thread (%gs) descriptor */
222#define GTSS_SEL 13 /* common TSS */
223#define GNMITSS_SEL 14 /* NMI TSS */
224#define GBIOS32_SEL 15 /* spare slot for 32 bit BIOS calls */
225#define NGDT 16
226
227#define GDT_SIZE (NGDT << 3)
228
229#endif /* _MACHINE_SEGMENTS_H_ */