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/interrupt.h>
43 #include <sys/kernel.h>
44 #include <sys/memrange.h>
45 #include <sys/tls.h>
46 #include <sys/types.h>
47 #include <sys/bus.h>
48 #include <sys/thread2.h>
49 #include <time.h>
50 
51 #include <vm/vm_extern.h>
52 #include <vm/vm_kern.h>
53 #include <vm/vm_object.h>
54 #include <vm/vm_page.h>
55 
56 #include <machine/cpu.h>
57 #include <machine/cpufunc.h>
58 #include <machine/globaldata.h>
59 #include <machine/md_var.h>
60 #include <machine/pmap.h>
61 #include <machine/smp.h>
62 #include <machine/tls.h>
63 #include <machine/cothread.h>
64 
65 #include <unistd.h>
66 #include <pthread.h>
67 #include <signal.h>
68 #include <stdio.h>
69 
70 static void cothread_thread(void *arg);
71 extern int vmm_enabled;
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
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 	void *stack;
85 	pthread_attr_t attr;
86 
87 	cotd = kmalloc(sizeof(*cotd), M_DEVBUF, M_WAITOK|M_ZERO);
88 	cotd->thr_intr = thr_intr;
89 	cotd->thr_func = thr_func;
90 	cotd->arg = arg;
91 	crit_enter();
92 	pthread_mutex_init(&cotd->mutex, NULL);
93 	pthread_cond_init(&cotd->cond, NULL);
94 	crit_exit();
95 
96 	cotd->pintr = pthread_self();
97 
98 	if (thr_intr) {
99 		cotd->intr_id = register_int_virtual(1, (void *)thr_intr,
100 						     cotd, name,
101 						     NULL, INTR_MPSAFE);
102 	}
103 
104 	/*
105 	 * The vkernel's cpu_disable_intr() masks signals.  We don't want
106 	 * our coprocessor thread taking any unix signals :-)
107 	 */
108 	pthread_attr_init(&attr);
109 	if (vmm_enabled) {
110 		stack = mmap(NULL, KERNEL_STACK_SIZE,
111 			     PROT_READ|PROT_WRITE|PROT_EXEC,
112 			     MAP_ANON, -1, 0);
113 		if (stack == MAP_FAILED) {
114 			panic("Unable to allocate stack for cothread\n");
115 		}
116 		pthread_attr_setstack(&attr, stack, KERNEL_STACK_SIZE);
117 	}
118 	crit_enter();
119 	cpu_mask_all_signals();
120 	pthread_create(&cotd->pthr, &attr, (void *)cothread_thread, cotd);
121 	cpu_unmask_all_signals();
122 	crit_exit();
123 	pthread_attr_destroy(&attr);
124 
125 	return(cotd);
126 }
127 
128 /*
129  * Wait for the target thread to terminate and then destroy the cothread
130  * structure.
131  */
132 void
133 cothread_delete(cothread_t *cotdp)
134 {
135 	cothread_t cotd;
136 
137 	if ((cotd = *cotdp) != NULL) {
138 		if (cotd->thr_intr)
139 			unregister_int_virtual(cotd->intr_id);
140 		crit_enter();
141 		pthread_join(cotd->pthr, NULL);
142 		crit_exit();
143 		kfree(cotd, M_DEVBUF);
144 		*cotdp = NULL;
145 	}
146 }
147 
148 static void
149 cothread_thread(void *arg)
150 {
151 	cothread_t cotd = arg;
152 
153 	cpu_mask_all_signals(); /* XXX remove me? should already be masked */
154 	/*
155 	 * %gs (aka mycpu) is illegal in cothreads.   Note that %fs is used
156 	 * by pthreads.
157 	 */
158 	/* JG try another approach? */
159 	tls_set_gs(0, sizeof(struct privatespace));
160 	cotd->thr_func(cotd);
161 }
162 
163 /*
164  * Called by the cothread to generate an interrupt back to the vkernel.
165  */
166 void
167 cothread_intr(cothread_t cotd)
168 {
169 	pthread_kill(cotd->pintr, SIGALRM);
170 }
171 
172 /*
173  * Called by the vkernel to wakeup a cothread.
174  * The cothread must be locked.
175  */
176 void
177 cothread_signal(cothread_t cotd)
178 {
179 	pthread_cond_signal(&cotd->cond);
180 }
181 
182 /*
183  * Called by the cothread to wait for the vkernel to call cothread_signal().
184  * The cothread must be locked.
185  */
186 void
187 cothread_wait(cothread_t cotd)
188 {
189 	pthread_cond_wait(&cotd->cond, &cotd->mutex);
190 }
191 
192 /*
193  * Used for systimer support
194  */
195 void
196 cothread_sleep(cothread_t cotd, struct timespec *ts)
197 {
198 	nanosleep(ts, NULL);
199 }
200 
201 void
202 cothread_wakeup(cothread_t cotd, struct timespec *ts)
203 {
204 	ts->tv_sec = 0;
205 	ts->tv_nsec = 0;
206 	pthread_kill(cotd->pthr, SIGINT);
207 }
208 
209 /*
210  * Typically called by kernel thread or cothread
211  *
212  * These must be a matched pair.  We will acquire a critical
213  * section in cothread_lock() and release it in cothread_unlock().
214  *
215  * We do this to simplify cothread operation to prevent an
216  * interrupt (e.g. vkd_io_intr()) from preempting a vkd_strategy()
217  * call and creating a recursion in the pthread.
218  */
219 void
220 cothread_lock(cothread_t cotd, int is_cotd)
221 {
222 	if (is_cotd) {
223 		pthread_mutex_lock(&cotd->mutex);
224 	} else {
225 		crit_enter_id("cothread");
226 		pthread_mutex_lock(&cotd->mutex);
227 	}
228 }
229 
230 void
231 cothread_unlock(cothread_t cotd, int is_cotd)
232 {
233 	if (is_cotd) {
234 		pthread_mutex_unlock(&cotd->mutex);
235 	} else {
236 		pthread_mutex_unlock(&cotd->mutex);
237 		crit_exit_id("cothread");
238 	}
239 }
240