sys/platform/vkernel64/platform/cothread.c

   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 #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 extern int vmm_enabled;
  73
  74 /*
  75  * Create a co-processor thread for a virtual kernel.  This thread operates
  76  * outside of the virtual kernel cpu abstraction and may only make direct
  77  * cothread and libc calls.
  78  */
  79 cothread_t
  80 cothread_create(void (*thr_func)(cothread_t cotd),
  81                 void (*thr_intr)(cothread_t cotd),
  82                 void *arg, const char *name)
  83 {
  84         cothread_t cotd;
  85         void *stack;
  86         pthread_attr_t attr;
  87
  88         cotd = kmalloc(sizeof(*cotd), M_DEVBUF, M_WAITOK|M_ZERO);
  89         cotd->thr_intr = thr_intr;
  90         cotd->thr_func = thr_func;
  91         cotd->arg = arg;
  92         crit_enter();
  93         pthread_mutex_init(&cotd->mutex, NULL);
  94         pthread_cond_init(&cotd->cond, NULL);
  95         crit_exit();
  96
  97         cotd->pintr = pthread_self();
  98
  99         if (thr_intr) {
 100                 cotd->intr_id = register_int_virtual(1, (void *)thr_intr,
 101                                                      cotd, name,
 102                                                      NULL, INTR_MPSAFE);
 103         }
 104
 105         /*
 106          * The vkernel's cpu_disable_intr() masks signals.  We don't want
 107          * our coprocessor thread taking any unix signals :-)
 108          */
 109         pthread_attr_init(&attr);
 110         if (vmm_enabled) {
 111                 stack = mmap(NULL, KERNEL_STACK_SIZE,
 112                              PROT_READ|PROT_WRITE|PROT_EXEC,
 113                              MAP_ANON, -1, 0);
 114                 if (stack == MAP_FAILED) {
 115                         panic("Unable to allocate stack for cothread\n");
 116                 }
 117                 pthread_attr_setstack(&attr, stack, KERNEL_STACK_SIZE);
 118         }
 119         crit_enter();
 120         cpu_mask_all_signals();
 121         pthread_create(&cotd->pthr, &attr, (void *)cothread_thread, cotd);
 122         cpu_unmask_all_signals();
 123         crit_exit();
 124         pthread_attr_destroy(&attr);
 125
 126         return(cotd);
 127 }
 128
 129 /*
 130  * Wait for the target thread to terminate and then destroy the cothread
 131  * structure.
 132  */
 133 void
 134 cothread_delete(cothread_t *cotdp)
 135 {
 136         cothread_t cotd;
 137
 138         if ((cotd = *cotdp) != NULL) {
 139                 if (cotd->thr_intr)
 140                         unregister_int_virtual(cotd->intr_id);
 141                 crit_enter();
 142                 pthread_join(cotd->pthr, NULL);
 143                 crit_exit();
 144                 kfree(cotd, M_DEVBUF);
 145                 *cotdp = NULL;
 146         }
 147 }
 148
 149 static void
 150 cothread_thread(void *arg)
 151 {
 152         cothread_t cotd = arg;
 153
 154         cpu_mask_all_signals(); /* XXX remove me? should already be masked */
 155         /*
 156          * %gs (aka mycpu) is illegal in cothreads.   Note that %fs is used
 157          * by pthreads.
 158          */
 159         /* JG try another approach? */
 160         tls_set_gs(0, sizeof(struct privatespace));
 161         cotd->thr_func(cotd);
 162 }
 163
 164 /*
 165  * Called by the cothread to generate an interrupt back to the vkernel.
 166  */
 167 void
 168 cothread_intr(cothread_t cotd)
 169 {
 170         pthread_kill(cotd->pintr, SIGALRM);
 171 }
 172
 173 /*
 174  * Called by the vkernel to wakeup a cothread.
 175  * The cothread must be locked.
 176  */
 177 void
 178 cothread_signal(cothread_t cotd)
 179 {
 180         pthread_cond_signal(&cotd->cond);
 181 }
 182
 183 /*
 184  * Called by the cothread to wait for the vkernel to call cothread_signal().
 185  * The cothread must be locked.
 186  */
 187 void
 188 cothread_wait(cothread_t cotd)
 189 {
 190         pthread_cond_wait(&cotd->cond, &cotd->mutex);
 191 }
 192
 193 /*
 194  * Used for systimer support
 195  */
 196 void
 197 cothread_sleep(cothread_t cotd, struct timespec *ts)
 198 {
 199         nanosleep(ts, NULL);
 200 }
 201
 202 void
 203 cothread_wakeup(cothread_t cotd, struct timespec *ts)
 204 {
 205         ts->tv_sec = 0;
 206         ts->tv_nsec = 0;
 207         pthread_kill(cotd->pthr, SIGINT);
 208 }
 209
 210 /*
 211  * Typically called by kernel thread or cothread
 212  *
 213  * These must be a matched pair.  We will acquire a critical
 214  * section in cothread_lock() and release it in cothread_unlock().
 215  *
 216  * We do this to simplify cothread operation to prevent an
 217  * interrupt (e.g. vkd_io_intr()) from preempting a vkd_strategy()
 218  * call and creating a recursion in the pthread.
 219  */
 220 void
 221 cothread_lock(cothread_t cotd, int is_cotd)
 222 {
 223         if (is_cotd) {
 224                 pthread_mutex_lock(&cotd->mutex);
 225         } else {
 226                 crit_enter_id("cothread");
 227                 pthread_mutex_lock(&cotd->mutex);
 228         }
 229 }
 230
 231 void
 232 cothread_unlock(cothread_t cotd, int is_cotd)
 233 {
 234         if (is_cotd) {
 235                 pthread_mutex_unlock(&cotd->mutex);
 236         } else {
 237                 pthread_mutex_unlock(&cotd->mutex);
 238                 crit_exit_id("cothread");
 239         }
 240 }