1 /* $NetBSD: idt.c,v 1.17 2022/08/20 23:48:51 riastradh Exp $ */
2
3 /*-
4 * Copyright (c) 1996, 1997, 1998, 2000, 2009 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Charles M. Hannum, by Jason R. Thorpe of the Numerical Aerospace
9 * Simulation Facility NASA Ames Research Center, and by Andrew Doran.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30 * POSSIBILITY OF SUCH DAMAGE.
31 */
32
33 /*-
34 * Copyright (c) 1982, 1987, 1990 The Regents of the University of California.
35 * All rights reserved.
36 *
37 * This code is derived from software contributed to Berkeley by
38 * William Jolitz.
39 *
40 * Redistribution and use in source and binary forms, with or without
41 * modification, are permitted provided that the following conditions
42 * are met:
43 * 1. Redistributions of source code must retain the above copyright
44 * notice, this list of conditions and the following disclaimer.
45 * 2. Redistributions in binary form must reproduce the above copyright
46 * notice, this list of conditions and the following disclaimer in the
47 * documentation and/or other materials provided with the distribution.
48 * 3. Neither the name of the University nor the names of its contributors
49 * may be used to endorse or promote products derived from this software
50 * without specific prior written permission.
51 *
52 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
53 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
54 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
55 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
56 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
57 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
58 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
59 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
60 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
61 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
62 * SUCH DAMAGE.
63 *
64 * @(#)machdep.c 7.4 (Berkeley) 6/3/91
65 */
66
67 #include <sys/cdefs.h>
68 __KERNEL_RCSID(0, "$NetBSD: idt.c,v 1.17 2022/08/20 23:48:51 riastradh Exp $");
69
70 #include "opt_pcpu_idt.h"
71
72 #include <sys/param.h>
73 #include <sys/systm.h>
74 #include <sys/mutex.h>
75 #include <sys/cpu.h>
76 #include <sys/atomic.h>
77
78 #include <uvm/uvm.h>
79
80 #include <machine/pmap_private.h>
81 #include <machine/segments.h>
82
83 /*
84 * XEN PV and native have a different idea of what idt entries should
85 * look like.
86 */
87
88 /* Normalise across XEN PV and native */
89 #if defined(XENPV)
90
91 void
set_idtgate(struct trap_info * xen_idd,void * function,int ist,int type,int dpl,int sel)92 set_idtgate(struct trap_info *xen_idd, void *function, int ist,
93 int type, int dpl, int sel)
94 {
95 /*
96 * Find the page boundary in which the descriptor resides.
97 * We make an assumption here, that the descriptor is part of
98 * a table (array), which fits in a page and is page aligned.
99 *
100 * This assumption is from the usecases at early startup in
101 * machine/machdep.c
102 *
103 * Thus this function may not work in the "general" case of a
104 * randomly located idt entry template (for eg:).
105 */
106
107 vaddr_t xen_idt_vaddr = ((vaddr_t) xen_idd) & ~PAGE_MASK;
108
109 //kpreempt_disable();
110 #if defined(__x86_64__)
111 /* Make it writeable, so we can update the values. */
112 pmap_changeprot_local(xen_idt_vaddr, VM_PROT_READ | VM_PROT_WRITE);
113 #endif /* __x86_64 */
114 xen_idd->cs = sel;
115 xen_idd->address = (unsigned long) function;
116 xen_idd->flags = dpl;
117
118 /*
119 * Again we make the assumption that the descriptor is
120 * implicitly part of an idt, which we infer as
121 * xen_idt_vaddr. (See above).
122 */
123 xen_idd->vector = xen_idd - (struct trap_info *)xen_idt_vaddr;
124
125 /* Back to read-only, as it should be. */
126 #if defined(__x86_64__)
127 pmap_changeprot_local(xen_idt_vaddr, VM_PROT_READ);
128 #endif /* __x86_64 */
129 //kpreempt_enable();
130 }
131 void
unset_idtgate(struct trap_info * xen_idd)132 unset_idtgate(struct trap_info *xen_idd)
133 {
134 #if defined(__x86_64__)
135 vaddr_t xen_idt_vaddr = ((vaddr_t) xen_idd) & ~PAGE_MASK;
136
137 /* Make it writeable, so we can update the values. */
138 pmap_changeprot_local(xen_idt_vaddr, VM_PROT_READ | VM_PROT_WRITE);
139 #endif /* __x86_64 */
140
141 /* Zero it */
142 memset(xen_idd, 0, sizeof (*xen_idd));
143
144 #if defined(__x86_64__)
145 /* Back to read-only, as it should be. */
146 pmap_changeprot_local(xen_idt_vaddr, VM_PROT_READ);
147 #endif /* __x86_64 */
148 }
149 #else /* XENPV */
150 void
set_idtgate(struct gate_descriptor * idd,void * function,int ist,int type,int dpl,int sel)151 set_idtgate(struct gate_descriptor *idd, void *function, int ist, int type, int dpl, int sel)
152 {
153 setgate(idd, function, ist, type, dpl, sel);
154 }
155 void
unset_idtgate(struct gate_descriptor * idd)156 unset_idtgate(struct gate_descriptor *idd)
157 {
158 unsetgate(idd);
159 }
160 #endif /* XENPV */
161
162 /*
163 * Allocate an IDT vector slot within the given range.
164 * cpu_lock will be held unless single threaded during early boot.
165 */
166 int
idt_vec_alloc(struct idt_vec * iv,int low,int high)167 idt_vec_alloc(struct idt_vec *iv, int low, int high)
168 {
169 int vec;
170 char *idt_allocmap = iv->iv_allocmap;
171
172 KASSERT(mutex_owned(&cpu_lock) || !mp_online);
173
174 if (low < 0 || high >= __arraycount(iv->iv_allocmap))
175 return -1;
176
177 for (vec = low; vec <= high; vec++) {
178 /* pairs with atomic_store_release in idt_vec_free */
179 if (atomic_load_acquire(&idt_allocmap[vec]) == 0) {
180 /*
181 * No ordering needed here (`relaxed') because
182 * access to free entries is serialized by
183 * cpu_lock or single-threaded operation.
184 */
185 atomic_store_relaxed(&idt_allocmap[vec], 1);
186 return vec;
187 }
188 }
189
190 return -1;
191 }
192
193 void
idt_vec_reserve(struct idt_vec * iv,int vec)194 idt_vec_reserve(struct idt_vec *iv, int vec)
195 {
196 int result;
197
198 KASSERT(mutex_owned(&cpu_lock) || !mp_online);
199
200 result = idt_vec_alloc(iv, vec, vec);
201 if (result < 0) {
202 panic("%s: failed to reserve vec %d", __func__, vec);
203 }
204 }
205
206 void
idt_vec_set(struct idt_vec * iv,int vec,void (* function)(void))207 idt_vec_set(struct idt_vec *iv, int vec, void (*function)(void))
208 {
209 idt_descriptor_t *idt;
210 char *idt_allocmap __diagused = iv->iv_allocmap;
211
212 KASSERT(atomic_load_relaxed(&idt_allocmap[vec]) == 1);
213
214 idt = iv->iv_idt;
215 set_idtgate(&idt[vec], function, 0, SDT_SYS386IGT, SEL_KPL,
216 GSEL(GCODE_SEL, SEL_KPL));
217 }
218
219 /*
220 * Free IDT vector. No locking required as release is atomic.
221 */
222 void
idt_vec_free(struct idt_vec * iv,int vec)223 idt_vec_free(struct idt_vec *iv, int vec)
224 {
225 idt_descriptor_t *idt;
226 char *idt_allocmap = iv->iv_allocmap;
227
228 KASSERT(atomic_load_relaxed(&idt_allocmap[vec]) == 1);
229
230 idt = iv->iv_idt;
231 unset_idtgate(&idt[vec]);
232 /* pairs with atomic_load_acquire in idt_vec_alloc */
233 atomic_store_release(&idt_allocmap[vec], 0);
234 }
235
236 bool
idt_vec_is_pcpu(void)237 idt_vec_is_pcpu(void)
238 {
239
240 #ifdef PCPU_IDT
241 return true;
242 #else
243 return false;
244 #endif
245 }
246
247 struct idt_vec *
idt_vec_ref(struct idt_vec * iv)248 idt_vec_ref(struct idt_vec *iv)
249 {
250 if (idt_vec_is_pcpu())
251 return iv;
252
253 return &(cpu_info_primary.ci_idtvec);
254 }
255