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 * $DragonFly: src/sys/platform/vkernel/platform/cothread.c,v 1.3 2008/05/07 17:19:47 dillon Exp $ 35 */ 36 /* 37 * Provides the vkernel with an asynchronous I/O mechanism using pthreads 38 * which operates outside the cpu abstraction. Cothreads are intended to 39 * operate like DMA engines and may ONLY make libc and cothread_*() calls. 40 * The cothread may NOT call into the vkernel since abstractions like 41 * 'mycpu' do not exist for it. 42 */ 43 44 #include <sys/interrupt.h> 45 #include <sys/kernel.h> 46 #include <sys/memrange.h> 47 #include <sys/tls.h> 48 #include <sys/types.h> 49 #include <sys/bus.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 72 /* 73 * Create a co-processor thread for a virtual kernel. This thread operates 74 * outside of the virtual kernel cpu abstraction and may only make direct 75 * cothread and libc calls. 76 */ 77 cothread_t 78 cothread_create(void (*thr_func)(cothread_t cotd), 79 void (*thr_intr)(cothread_t cotd), 80 void *arg, const char *name) 81 { 82 cothread_t cotd; 83 84 cotd = kmalloc(sizeof(*cotd), M_DEVBUF, M_WAITOK|M_ZERO); 85 cotd->thr_intr = thr_intr; 86 cotd->thr_func = thr_func; 87 cotd->arg = arg; 88 crit_enter(); 89 pthread_mutex_init(&cotd->mutex, NULL); 90 pthread_cond_init(&cotd->cond, NULL); 91 crit_exit(); 92 93 cotd->pintr = pthread_self(); 94 95 cotd->intr_id = register_int_virtual(1, (void *)thr_intr, cotd, name, 96 NULL, INTR_MPSAFE); 97 98 /* 99 * The vkernel's cpu_disable_intr() masks signals. We don't want 100 * our coprocessor thread taking any unix signals :-) 101 */ 102 crit_enter(); 103 cpu_mask_all_signals(); 104 pthread_create(&cotd->pthr, NULL, (void *)cothread_thread, cotd); 105 cpu_unmask_all_signals(); 106 crit_exit(); 107 return(cotd); 108 } 109 110 /* 111 * Wait for the target thread to terminate and then destroy the cothread 112 * structure. 113 */ 114 void 115 cothread_delete(cothread_t *cotdp) 116 { 117 cothread_t cotd; 118 119 if ((cotd = *cotdp) != NULL) { 120 unregister_int_virtual(cotd->intr_id); 121 crit_enter(); 122 pthread_join(cotd->pthr, NULL); 123 crit_exit(); 124 kfree(cotd, M_DEVBUF); 125 *cotdp = NULL; 126 } 127 } 128 129 static void 130 cothread_thread(void *arg) 131 { 132 cothread_t cotd = arg; 133 134 cpu_mask_all_signals(); /* XXX remove me? should already be masked */ 135 /* 136 * %gs (aka mycpu) is illegal in cothreads. Note that %fs is used 137 * by pthreads. 138 */ 139 /* JG try another approach? */ 140 tls_set_gs(0, sizeof(struct privatespace)); 141 cotd->thr_func(cotd); 142 } 143 144 /* 145 * Called by the cothread to generate an interrupt back to the vkernel. 146 */ 147 void 148 cothread_intr(cothread_t cotd) 149 { 150 pthread_kill(cotd->pintr, SIGIO); 151 } 152 153 /* 154 * Called by the vkernel to wakeup a cothread. 155 * The cothread must be locked. 156 */ 157 void 158 cothread_signal(cothread_t cotd) 159 { 160 pthread_cond_signal(&cotd->cond); 161 } 162 163 /* 164 * Called by the cothread to wait for the vkernel to call cothread_signal(). 165 * The cothread must be locked. 166 */ 167 void 168 cothread_wait(cothread_t cotd) 169 { 170 pthread_cond_wait(&cotd->cond, &cotd->mutex); 171 } 172 173 /* 174 * Typically called by kernel thread or cothread 175 * 176 * These must be a matched pair. We will acquire a critical 177 * section in cothread_lock() and release it in cothread_unlock(). 178 * 179 * We do this to simplify cothread operation to prevent an 180 * interrupt (e.g. vkd_io_intr()) from preempting a vkd_strategy() 181 * call and creating a recursion in the pthread. 182 */ 183 void 184 cothread_lock(cothread_t cotd, int is_cotd) 185 { 186 if (is_cotd) { 187 pthread_mutex_lock(&cotd->mutex); 188 } else { 189 crit_enter_id("cothread"); 190 pthread_mutex_lock(&cotd->mutex); 191 } 192 } 193 194 void 195 cothread_unlock(cothread_t cotd, int is_cotd) 196 { 197 if (is_cotd) { 198 pthread_mutex_unlock(&cotd->mutex); 199 } else { 200 pthread_mutex_unlock(&cotd->mutex); 201 crit_exit_id("cothread"); 202 } 203 } 204