1/* $OpenBSD: segments.h,v 1.18 2025/06/27 17:23:49 bluhm Exp $ */
2/* $NetBSD: segments.h,v 1.1 2003/04/26 18:39:47 fvdl Exp $ */
3
4/*-
5 * Copyright (c) 1995, 1997
6 * Charles M. Hannum. All rights reserved.
7 * Copyright (c) 1989, 1990 William F. Jolitz
8 * Copyright (c) 1990 The Regents of the University of California.
9 * All rights reserved.
10 *
11 * This code is derived from software contributed to Berkeley by
12 * William Jolitz.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 * notice, this list of conditions and the following disclaimer in the
21 * documentation and/or other materials provided with the distribution.
22 * 3. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 * @(#)segments.h 7.1 (Berkeley) 5/9/91
39 */
40
41/*
42 * Adapted for NetBSD/amd64 by fvdl@wasabisystems.com.
43 */
44
45/*
46 * 386 Segmentation Data Structures and definitions
47 * William F. Jolitz (william@ernie.berkeley.edu) 6/20/1989
48 */
49
50#ifndef _MACHINE_SEGMENTS_H_
51#define _MACHINE_SEGMENTS_H_
52
53/*
54 * Selectors
55 */
56
57#define ISPL(s) ((s) & SEL_RPL) /* what is the priority level of a selector */
58#define SEL_KPL 0 /* kernel privilege level */
59#define SEL_UPL 3 /* user privilege level */
60#define SEL_RPL 3 /* requester's privilege level mask */
61#define ISLDT(s) ((s) & SEL_LDT) /* is it local or global */
62#define SEL_LDT 4 /* local descriptor table */
63
64#define SYSSEL_START (NGDT_MEM << 3)
65#define GDT_SIZE (SYSSEL_START + (NGDT_SYS << 4))
66
67/*
68 * These define the index not from the start of the GDT, but from
69 * the part of the GDT that they're allocated from.
70 * First NGDT_MEM entries are 8-byte descriptors for CS and DS.
71 * Next NGDT_SYS entries are 16-byte descriptors defining TSSs.
72 */
73
74#define IDXSEL(s) (((s) >> 3) & 0x1fff)
75#define IDXDYNSEL(s) ((((s) & ~SEL_RPL) - DYNSEL_START) >> 4)
76
77#define GSEL(s,r) (((s) << 3) | r)
78#define GSYSSEL(s,r) ((((s) << 4) + SYSSEL_START) | r)
79#define GDYNSEL(s,r) ((((s) << 4) + DYNSEL_START) | r | SEL_KPL)
80
81#define LSEL(s,r) ((s) | r | SEL_LDT)
82
83#define USERMODE(c, f) (ISPL(c) == SEL_UPL)
84#define KERNELMODE(c, f) (ISPL(c) == SEL_KPL)
85
86#ifndef _LOCORE
87
88/*
89 * Memory and System segment descriptors
90 */
91
92/*
93 * Below is used for TSS and LDT.
94 */
95struct sys_segment_descriptor {
96 u_int64_t sd_lolimit:16; /* segment extent (lsb) */
97 u_int64_t sd_lobase:24; /* segment base address (lsb) */
98 u_int64_t sd_type:5; /* segment type */
99 u_int64_t sd_dpl:2; /* segment descriptor priority level */
100 u_int64_t sd_p:1; /* segment descriptor present */
101 u_int64_t sd_hilimit:4; /* segment extent (msb) */
102 u_int64_t sd_xx1:3; /* avl, long and def32 (not used) */
103 u_int64_t sd_gran:1; /* limit granularity (byte/page) */
104 u_int64_t sd_hibase:40; /* segment base address (msb) */
105 u_int64_t sd_xx2:8; /* reserved */
106 u_int64_t sd_zero:5; /* must be zero */
107 u_int64_t sd_xx3:19; /* reserved */
108} __packed;
109
110/*
111 * Below is used for cs, ds, etc.
112 */
113struct mem_segment_descriptor {
114 unsigned int sd_lolimit:16; /* segment extent (lsb) */
115 unsigned int sd_lobase:24; /* segment base address (lsb) */
116 unsigned int sd_type:5; /* segment type */
117 unsigned int sd_dpl:2; /* segment descriptor priority level */
118 unsigned int sd_p:1; /* segment descriptor present */
119 unsigned int sd_hilimit:4; /* segment extent (msb) */
120 unsigned int sd_avl:1; /* available */
121 unsigned int sd_long:1; /* long mode */
122 unsigned int sd_def32:1; /* default 32 vs 16 bit size */
123 unsigned int sd_gran:1; /* limit granularity (byte/page) */
124 unsigned int sd_hibase:8; /* segment base address (msb) */
125} __packed;
126
127/*
128 * Gate descriptors (e.g. indirect descriptors)
129 */
130struct gate_descriptor {
131 u_int64_t gd_looffset:16; /* gate offset (lsb) */
132 u_int64_t gd_selector:16; /* gate segment selector */
133 u_int64_t gd_ist:3; /* IST select */
134 u_int64_t gd_xx1:5; /* reserved */
135 u_int64_t gd_type:5; /* segment type */
136 u_int64_t gd_dpl:2; /* segment descriptor priority level */
137 u_int64_t gd_p:1; /* segment descriptor present */
138 u_int64_t gd_hioffset:48; /* gate offset (msb) */
139 u_int64_t gd_xx2:8; /* reserved */
140 u_int64_t gd_zero:5; /* must be zero */
141 u_int64_t gd_xx3:19; /* reserved */
142} __packed;
143
144/*
145 * region descriptors, used to load gdt/idt tables before segments yet exist.
146 */
147struct region_descriptor {
148 u_int16_t rd_limit; /* segment extent */
149 u_int64_t rd_base; /* base address */
150} __packed;
151
152#ifdef _KERNEL
153extern struct gate_descriptor *idt;
154extern struct gate_descriptor early_idt[];
155
156void setgate(struct gate_descriptor *, void *, int, int, int, int);
157void unsetgate(struct gate_descriptor *);
158void setregion(struct region_descriptor *, void *, u_int16_t);
159void set_sys_segment(struct sys_segment_descriptor *, void *, size_t,
160 int, int, int);
161void set_mem_segment(struct mem_segment_descriptor *, void *, size_t,
162 int, int, int, int, int);
163int idt_vec_alloc(int, int);
164int idt_vec_alloc_range(int, int, int);
165void idt_vec_set(int, void (*)(void));
166void idt_vec_free(int);
167void cpu_init_idt(void);
168
169#endif /* _KERNEL */
170
171#endif /* !_LOCORE */
172
173/* system segments and gate types */
174#define SDT_SYSNULL 0 /* system null */
175#define SDT_SYS286TSS 1 /* system 286 TSS available */
176#define SDT_SYSLDT 2 /* system local descriptor table */
177#define SDT_SYS286BSY 3 /* system 286 TSS busy */
178#define SDT_SYS286CGT 4 /* system 286 call gate */
179#define SDT_SYSTASKGT 5 /* system task gate */
180#define SDT_SYS286IGT 6 /* system 286 interrupt gate */
181#define SDT_SYS286TGT 7 /* system 286 trap gate */
182#define SDT_SYSNULL2 8 /* system null again */
183#define SDT_SYS386TSS 9 /* system 386 TSS available */
184#define SDT_SYSNULL3 10 /* system null again */
185#define SDT_SYS386BSY 11 /* system 386 TSS busy */
186#define SDT_SYS386CGT 12 /* system 386 call gate */
187#define SDT_SYSNULL4 13 /* system null again */
188#define SDT_SYS386IGT 14 /* system 386 interrupt gate */
189#define SDT_SYS386TGT 15 /* system 386 trap gate */
190
191/* memory segment types */
192#define SDT_MEMRO 16 /* memory read only */
193#define SDT_MEMROA 17 /* memory read only accessed */
194#define SDT_MEMRW 18 /* memory read write */
195#define SDT_MEMRWA 19 /* memory read write accessed */
196#define SDT_MEMROD 20 /* memory read only expand dwn limit */
197#define SDT_MEMRODA 21 /* memory read only expand dwn limit accessed */
198#define SDT_MEMRWD 22 /* memory read write expand dwn limit */
199#define SDT_MEMRWDA 23 /* memory read write expand dwn limit acessed */
200#define SDT_MEME 24 /* memory execute only */
201#define SDT_MEMEA 25 /* memory execute only accessed */
202#define SDT_MEMER 26 /* memory execute read */
203#define SDT_MEMERA 27 /* memory execute read accessed */
204#define SDT_MEMEC 28 /* memory execute only conforming */
205#define SDT_MEMEAC 29 /* memory execute only accessed conforming */
206#define SDT_MEMERC 30 /* memory execute read conforming */
207#define SDT_MEMERAC 31 /* memory execute read accessed conforming */
208
209/* is memory segment descriptor pointer ? */
210#define ISMEMSDP(s) ((s->d_type) >= SDT_MEMRO && \
211 (s->d_type) <= SDT_MEMERAC)
212
213/* is 286 gate descriptor pointer ? */
214#define IS286GDP(s) ((s->d_type) >= SDT_SYS286CGT && \
215 (s->d_type) < SDT_SYS286TGT)
216
217/* is 386 gate descriptor pointer ? */
218#define IS386GDP(s) ((s->d_type) >= SDT_SYS386CGT && \
219 (s->d_type) < SDT_SYS386TGT)
220
221/* is gate descriptor pointer ? */
222#define ISGDP(s) (IS286GDP(s) || IS386GDP(s))
223
224/* is segment descriptor pointer ? */
225#define ISSDP(s) (ISMEMSDP(s) || !ISGDP(s))
226
227/* is system segment descriptor pointer ? */
228#define ISSYSSDP(s) (!ISMEMSDP(s) && !ISGDP(s))
229
230/*
231 * Segment Protection Exception code bits
232 */
233#define SEGEX_EXT 0x01 /* recursive or externally induced */
234#define SEGEX_IDT 0x02 /* interrupt descriptor table */
235#define SEGEX_TI 0x04 /* local descriptor table */
236
237/*
238 * Entries in the Interrupt Descriptor Table (IDT)
239 */
240#define NIDT 256
241#define NRSVIDT 32 /* reserved entries for cpu exceptions */
242
243/*
244 * Entries in the Global Descriptor Table (GDT)
245 * The code and data descriptors must come first. There
246 * are NGDT_MEM of them.
247 *
248 * Then comes the predefined TSS descriptor.
249 * There are NGDT_SYS of them.
250 *
251 * The particular order of the UDATA and UCODE descriptors is
252 * required by the sysretq instruction.
253 */
254#define GNULL_SEL 0 /* Null descriptor */
255#define GCODE_SEL 1 /* Kernel code descriptor */
256#define GDATA_SEL 2 /* Kernel data descriptor */
257#define GUDATA_SEL 3 /* User data descriptor */
258#define GUCODE_SEL 4 /* User code descriptor */
259#define NGDT_MEM 5
260
261#define GPROC0_SEL 0 /* common TSS */
262#define NGDT_SYS 1
263
264#define GDT_SYS_OFFSET (NGDT_MEM << 3)
265
266#define GDT_ADDR_MEM(s,i) \
267 ((struct mem_segment_descriptor *)((char *)(s) + ((i) << 3)))
268#define GDT_ADDR_SYS(s,i) \
269 ((struct sys_segment_descriptor *)((char *)(s) + ((i) << 4) + SYSSEL_START))
270
271/*
272 * Checks for valid user selectors.
273 */
274#define VALID_USER_CSEL(s) \
275 ((s) == GSEL(GUCODE_SEL, SEL_UPL))
276#define VALID_USER_DSEL(s) \
277 ((s) == GSEL(GUDATA_SEL, SEL_UPL))
278
279#endif /* _MACHINE_SEGMENTS_H_ */