1 /*
2 * Copyright (c) 2008-2010 The DragonFly Project. All rights reserved.
3 *
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
16 * distribution.
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34 /*
35 * Provides the vkernel with an asynchronous I/O mechanism using pthreads
36 * which operates outside the cpu abstraction. Cothreads are intended to
37 * operate like DMA engines and may ONLY make libc and cothread_*() calls.
38 * The cothread may NOT call into the vkernel since abstractions like
39 * 'mycpu' do not exist for it.
40 */
41
42 #include <sys/types.h>
43 #include <sys/interrupt.h>
44 #include <sys/kernel.h>
45 #include <sys/malloc.h>
46 #include <sys/memrange.h>
47 #include <sys/tls.h>
48 #include <sys/bus.h>
49 #include <sys/thread2.h>
50 #include <time.h>
51
52 #include <vm/vm_extern.h>
53 #include <vm/vm_kern.h>
54 #include <vm/vm_object.h>
55 #include <vm/vm_page.h>
56
57 #include <machine/cpu.h>
58 #include <machine/cpufunc.h>
59 #include <machine/globaldata.h>
60 #include <machine/md_var.h>
61 #include <machine/pmap.h>
62 #include <machine/smp.h>
63 #include <machine/tls.h>
64 #include <machine/cothread.h>
65
66 #include <unistd.h>
67 #include <pthread.h>
68 #include <signal.h>
69 #include <stdio.h>
70
71 static void cothread_thread(void *arg);
72
73 /*
74 * Create a co-processor thread for a virtual kernel. This thread operates
75 * outside of the virtual kernel cpu abstraction and may only make direct
76 * cothread and libc calls.
77 */
78 cothread_t
cothread_create(void (* thr_func)(cothread_t cotd),void (* thr_intr)(cothread_t cotd),void * arg,const char * name)79 cothread_create(void (*thr_func)(cothread_t cotd),
80 void (*thr_intr)(cothread_t cotd),
81 void *arg, const char *name)
82 {
83 cothread_t cotd;
84 pthread_attr_t attr;
85
86 cotd = kmalloc(sizeof(*cotd), M_DEVBUF, M_WAITOK|M_ZERO);
87 cotd->thr_intr = thr_intr;
88 cotd->thr_func = thr_func;
89 cotd->arg = arg;
90 crit_enter();
91 pthread_mutex_init(&cotd->mutex, NULL);
92 pthread_cond_init(&cotd->cond, NULL);
93 crit_exit();
94
95 cotd->pintr = pthread_self();
96
97 if (thr_intr) {
98 cotd->intr_id = register_int_virtual(1, (void *)thr_intr,
99 cotd, name,
100 NULL, INTR_MPSAFE);
101 }
102
103 /*
104 * The vkernel's cpu_disable_intr() masks signals. We don't want
105 * our coprocessor thread taking any unix signals :-)
106 */
107 pthread_attr_init(&attr);
108 crit_enter();
109 cpu_mask_all_signals();
110 pthread_create(&cotd->pthr, &attr, (void *)cothread_thread, cotd);
111 cpu_unmask_all_signals();
112 crit_exit();
113 pthread_attr_destroy(&attr);
114
115 return(cotd);
116 }
117
118 /*
119 * Wait for the target thread to terminate and then destroy the cothread
120 * structure.
121 */
122 void
cothread_delete(cothread_t * cotdp)123 cothread_delete(cothread_t *cotdp)
124 {
125 cothread_t cotd;
126
127 if ((cotd = *cotdp) != NULL) {
128 if (cotd->thr_intr)
129 unregister_int_virtual(cotd->intr_id);
130 crit_enter();
131 pthread_join(cotd->pthr, NULL);
132 crit_exit();
133 kfree(cotd, M_DEVBUF);
134 *cotdp = NULL;
135 }
136 }
137
138 static void
cothread_thread(void * arg)139 cothread_thread(void *arg)
140 {
141 cothread_t cotd = arg;
142
143 cpu_mask_all_signals(); /* XXX remove me? should already be masked */
144 /*
145 * %gs (aka mycpu) is illegal in cothreads. Note that %fs is used
146 * by pthreads.
147 */
148 /* JG try another approach? */
149 tls_set_gs(0, sizeof(struct privatespace));
150 cotd->thr_func(cotd);
151 }
152
153 /*
154 * Called by the cothread to generate an interrupt back to the vkernel.
155 */
156 void
cothread_intr(cothread_t cotd)157 cothread_intr(cothread_t cotd)
158 {
159 pthread_kill(cotd->pintr, SIGALRM);
160 }
161
162 /*
163 * Called by the vkernel to wakeup a cothread.
164 * The cothread must be locked.
165 */
166 void
cothread_signal(cothread_t cotd)167 cothread_signal(cothread_t cotd)
168 {
169 pthread_cond_signal(&cotd->cond);
170 }
171
172 /*
173 * Called by the cothread to wait for the vkernel to call cothread_signal().
174 * The cothread must be locked.
175 */
176 void
cothread_wait(cothread_t cotd)177 cothread_wait(cothread_t cotd)
178 {
179 pthread_cond_wait(&cotd->cond, &cotd->mutex);
180 }
181
182 /*
183 * Used for systimer support
184 */
185 void
cothread_sleep(cothread_t cotd,struct timespec * ts)186 cothread_sleep(cothread_t cotd, struct timespec *ts)
187 {
188 nanosleep(ts, NULL);
189 }
190
191 void
cothread_wakeup(cothread_t cotd,struct timespec * ts)192 cothread_wakeup(cothread_t cotd, struct timespec *ts)
193 {
194 ts->tv_sec = 0;
195 ts->tv_nsec = 0;
196 pthread_kill(cotd->pthr, SIGINT);
197 }
198
199 /*
200 * Typically called by kernel thread or cothread
201 *
202 * These must be a matched pair. We will acquire a critical
203 * section in cothread_lock() and release it in cothread_unlock().
204 *
205 * We do this to simplify cothread operation to prevent an
206 * interrupt (e.g. vkd_io_intr()) from preempting a vkd_strategy()
207 * call and creating a recursion in the pthread.
208 */
209 void
cothread_lock(cothread_t cotd,int is_cotd)210 cothread_lock(cothread_t cotd, int is_cotd)
211 {
212 if (is_cotd) {
213 pthread_mutex_lock(&cotd->mutex);
214 } else {
215 crit_enter_id("cothread");
216 pthread_mutex_lock(&cotd->mutex);
217 }
218 }
219
220 void
cothread_unlock(cothread_t cotd,int is_cotd)221 cothread_unlock(cothread_t cotd, int is_cotd)
222 {
223 if (is_cotd) {
224 pthread_mutex_unlock(&cotd->mutex);
225 } else {
226 pthread_mutex_unlock(&cotd->mutex);
227 crit_exit_id("cothread");
228 }
229 }
230