1 /* 2 * Copyright (c) 2003 Matthew Dillon <dillon@backplane.com> All rights reserved. 3 * Copyright (c) 1997, Stefan Esser <se@freebsd.org> All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice unmodified, this list of conditions, and the following 10 * disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 * $FreeBSD: src/sys/kern/kern_intr.c,v 1.24.2.1 2001/10/14 20:05:50 luigi Exp $ 27 * $DragonFly: src/sys/kern/kern_intr.c,v 1.22 2005/06/16 21:12:19 dillon Exp $ 28 * 29 */ 30 31 #include <sys/param.h> 32 #include <sys/systm.h> 33 #include <sys/malloc.h> 34 #include <sys/kernel.h> 35 #include <sys/sysctl.h> 36 #include <sys/thread.h> 37 #include <sys/proc.h> 38 #include <sys/thread2.h> 39 #include <sys/random.h> 40 41 #include <machine/ipl.h> 42 43 #include <sys/interrupt.h> 44 45 typedef struct intrec { 46 struct intrec *next; 47 inthand2_t *handler; 48 void *argument; 49 const char *name; 50 int intr; 51 } intrec_t; 52 53 static intrec_t *intlists[NHWI+NSWI]; 54 static thread_t ithreads[NHWI+NSWI]; 55 static struct thread ithread_ary[NHWI+NSWI]; 56 static struct random_softc irandom_ary[NHWI+NSWI]; 57 static int irunning[NHWI+NSWI]; 58 static u_int ill_count[NHWI+NSWI]; /* interrupt livelock counter */ 59 static u_int ill_ticks[NHWI+NSWI]; /* track elapsed to calculate freq */ 60 static u_int ill_delta[NHWI+NSWI]; /* track elapsed to calculate freq */ 61 static int ill_state[NHWI+NSWI]; /* current state */ 62 static struct systimer ill_timer[NHWI+NSWI]; /* enforced freq. timer */ 63 static struct systimer ill_rtimer[NHWI+NSWI]; /* recovery timer */ 64 65 #define LIVELOCK_NONE 0 66 #define LIVELOCK_LIMITED 1 67 68 static int livelock_limit = 50000; 69 static int livelock_fallback = 20000; 70 SYSCTL_INT(_kern, OID_AUTO, livelock_limit, 71 CTLFLAG_RW, &livelock_limit, 0, "Livelock interrupt rate limit"); 72 SYSCTL_INT(_kern, OID_AUTO, livelock_fallback, 73 CTLFLAG_RW, &livelock_fallback, 0, "Livelock interrupt fallback rate"); 74 75 static void ithread_handler(void *arg); 76 77 /* 78 * Register an SWI or INTerrupt handler. 79 */ 80 thread_t 81 register_swi(int intr, inthand2_t *handler, void *arg, const char *name) 82 { 83 if (intr < NHWI || intr >= NHWI + NSWI) 84 panic("register_swi: bad intr %d", intr); 85 return(register_int(intr, handler, arg, name)); 86 } 87 88 thread_t 89 register_int(int intr, inthand2_t *handler, void *arg, const char *name) 90 { 91 intrec_t **list; 92 intrec_t *rec; 93 thread_t td; 94 95 if (intr < 0 || intr >= NHWI + NSWI) 96 panic("register_int: bad intr %d", intr); 97 98 rec = malloc(sizeof(intrec_t), M_DEVBUF, M_NOWAIT); 99 if (rec == NULL) 100 panic("register_swi: malloc failed"); 101 rec->handler = handler; 102 rec->argument = arg; 103 rec->name = name; 104 rec->intr = intr; 105 rec->next = NULL; 106 107 list = &intlists[intr]; 108 109 /* 110 * Create an interrupt thread if necessary, leave it in an unscheduled 111 * state. 112 */ 113 if ((td = ithreads[intr]) == NULL) { 114 lwkt_create((void *)ithread_handler, (void *)intr, &ithreads[intr], 115 &ithread_ary[intr], TDF_STOPREQ|TDF_INTTHREAD, -1, 116 "ithread %d", intr); 117 td = ithreads[intr]; 118 if (intr >= NHWI && intr < NHWI + NSWI) 119 lwkt_setpri(td, TDPRI_SOFT_NORM); 120 else 121 lwkt_setpri(td, TDPRI_INT_MED); 122 } 123 124 /* 125 * Add the record to the interrupt list 126 */ 127 crit_enter(); /* token */ 128 while (*list != NULL) 129 list = &(*list)->next; 130 *list = rec; 131 crit_exit(); 132 return(td); 133 } 134 135 void 136 unregister_swi(int intr, inthand2_t *handler) 137 { 138 if (intr < NHWI || intr >= NHWI + NSWI) 139 panic("register_swi: bad intr %d", intr); 140 unregister_int(intr, handler); 141 } 142 143 void 144 unregister_int(int intr, inthand2_t handler) 145 { 146 intrec_t **list; 147 intrec_t *rec; 148 149 if (intr < 0 || intr > NHWI + NSWI) 150 panic("register_int: bad intr %d", intr); 151 list = &intlists[intr]; 152 crit_enter(); 153 while ((rec = *list) != NULL) { 154 if (rec->handler == (void *)handler) { 155 *list = rec->next; 156 break; 157 } 158 list = &rec->next; 159 } 160 crit_exit(); 161 if (rec != NULL) { 162 free(rec, M_DEVBUF); 163 } else { 164 printf("warning: unregister_int: int %d handler %p not found\n", 165 intr, handler); 166 } 167 } 168 169 void 170 swi_setpriority(int intr, int pri) 171 { 172 struct thread *td; 173 174 if (intr < NHWI || intr >= NHWI + NSWI) 175 panic("register_swi: bad intr %d", intr); 176 if ((td = ithreads[intr]) != NULL) 177 lwkt_setpri(td, pri); 178 } 179 180 void 181 register_randintr(int intr) 182 { 183 struct random_softc *sc = &irandom_ary[intr]; 184 sc->sc_intr = intr; 185 sc->sc_enabled = 1; 186 } 187 188 void 189 unregister_randintr(int intr) 190 { 191 struct random_softc *sc = &irandom_ary[intr]; 192 sc->sc_enabled = 0; 193 } 194 195 /* 196 * Dispatch an interrupt. If there's nothing to do we have a stray 197 * interrupt and can just return, leaving the interrupt masked. 198 * 199 * We need to schedule the interrupt and set its irunning[] bit. If 200 * we are not on the interrupt thread's cpu we have to send a message 201 * to the correct cpu that will issue the desired action (interlocking 202 * with the interrupt thread's critical section). 203 * 204 * We are NOT in a critical section, which will allow the scheduled 205 * interrupt to preempt us. The MP lock might *NOT* be held here. 206 */ 207 static void 208 sched_ithd_remote(void *arg) 209 { 210 sched_ithd((int)arg); 211 } 212 213 void 214 sched_ithd(int intr) 215 { 216 thread_t td; 217 218 if ((td = ithreads[intr]) != NULL) { 219 if (intlists[intr] == NULL) { 220 printf("sched_ithd: stray interrupt %d\n", intr); 221 } else { 222 if (td->td_gd == mycpu) { 223 irunning[intr] = 1; 224 lwkt_schedule(td); /* preemption handled internally */ 225 } else { 226 lwkt_send_ipiq(td->td_gd, sched_ithd_remote, (void *)intr); 227 } 228 } 229 } else { 230 printf("sched_ithd: stray interrupt %d\n", intr); 231 } 232 } 233 234 /* 235 * This is run from a periodic SYSTIMER (and thus must be MP safe, the BGL 236 * might not be held). 237 */ 238 static void 239 ithread_livelock_wakeup(systimer_t info) 240 { 241 int intr = (int)info->data; 242 thread_t td; 243 244 if ((td = ithreads[intr]) != NULL) 245 lwkt_schedule(td); 246 } 247 248 249 /* 250 * Interrupt threads run this as their main loop. 251 * 252 * The handler begins execution outside a critical section and with the BGL 253 * held. 254 * 255 * The irunning state starts at 0. When an interrupt occurs, the hardware 256 * interrupt is disabled and sched_ithd() The HW interrupt remains disabled 257 * until all routines have run. We then call ithread_done() to reenable 258 * the HW interrupt and deschedule us until the next interrupt. 259 * 260 * We are responsible for atomically checking irunning[] and ithread_done() 261 * is responsible for atomically checking for platform-specific delayed 262 * interrupts. irunning[] for our irq is only set in the context of our cpu, 263 * so a critical section is a sufficient interlock. 264 */ 265 #define LIVELOCK_TIMEFRAME(freq) ((freq) >> 2) /* 1/4 second */ 266 267 static void 268 ithread_handler(void *arg) 269 { 270 int intr = (int)arg; 271 int freq; 272 u_int bticks; 273 u_int cputicks; 274 intrec_t **list = &intlists[intr]; 275 intrec_t *rec; 276 intrec_t *nrec; 277 struct random_softc *sc = &irandom_ary[intr]; 278 globaldata_t gd = mycpu; 279 280 /* 281 * The loop must be entered with one critical section held. 282 */ 283 crit_enter_gd(gd); 284 285 for (;;) { 286 /* 287 * We can get woken up by the livelock periodic code too, run the 288 * handlers only if there is a real interrupt pending. XXX 289 * 290 * Clear irunning[] prior to running the handlers to interlock 291 * again new events occuring during processing of existing events. 292 * 293 * For now run each handler in a critical section. 294 */ 295 irunning[intr] = 0; 296 for (rec = *list; rec; rec = nrec) { 297 nrec = rec->next; 298 rec->handler(rec->argument); 299 } 300 301 /* 302 * Do a quick exit/enter to catch any higher-priority 303 * interrupt sources and so user/system/interrupt statistics 304 * work for interrupt threads. 305 */ 306 crit_exit_gd(gd); 307 crit_enter_gd(gd); 308 309 /* 310 * This is our interrupt hook to add rate randomness to the random 311 * number generator. 312 */ 313 if (sc->sc_enabled) 314 add_interrupt_randomness(intr); 315 316 /* 317 * This is our livelock test. If we hit the rate limit we 318 * limit ourselves to X interrupts/sec until the rate 319 * falls below 50% of that value, then we unlimit again. 320 * 321 * XXX calling cputimer_count() is expensive but a livelock may 322 * prevent other interrupts from occuring so we cannot use ticks. 323 */ 324 cputicks = sys_cputimer->count(); 325 ++ill_count[intr]; 326 bticks = cputicks - ill_ticks[intr]; 327 ill_ticks[intr] = cputicks; 328 if (bticks > sys_cputimer->freq) 329 bticks = sys_cputimer->freq; 330 331 switch(ill_state[intr]) { 332 case LIVELOCK_NONE: 333 ill_delta[intr] += bticks; 334 if (ill_delta[intr] < LIVELOCK_TIMEFRAME(sys_cputimer->freq)) 335 break; 336 freq = (int64_t)ill_count[intr] * sys_cputimer->freq / 337 ill_delta[intr]; 338 ill_delta[intr] = 0; 339 ill_count[intr] = 0; 340 if (freq < livelock_limit) 341 break; 342 printf("intr %d at %d hz, livelocked! limiting at %d hz\n", 343 intr, freq, livelock_fallback); 344 ill_state[intr] = LIVELOCK_LIMITED; 345 bticks = 0; 346 /* force periodic check to avoid stale removal (if ints stop) */ 347 systimer_init_periodic(&ill_rtimer[intr], ithread_livelock_wakeup, 348 (void *)intr, 1); 349 /* fall through */ 350 case LIVELOCK_LIMITED: 351 /* 352 * Delay (us) before rearming the interrupt 353 */ 354 systimer_init_oneshot(&ill_timer[intr], ithread_livelock_wakeup, 355 (void *)intr, 1 + 1000000 / livelock_fallback); 356 lwkt_deschedule_self(curthread); 357 lwkt_switch(); 358 359 /* in case we were woken up by something else */ 360 systimer_del(&ill_timer[intr]); 361 362 /* 363 * Calculate interrupt rate (note that due to our delay it 364 * will not exceed livelock_fallback). 365 */ 366 ill_delta[intr] += bticks; 367 if (ill_delta[intr] < LIVELOCK_TIMEFRAME(sys_cputimer->freq)) 368 break; 369 freq = (int64_t)ill_count[intr] * sys_cputimer->freq / 370 ill_delta[intr]; 371 ill_delta[intr] = 0; 372 ill_count[intr] = 0; 373 if (freq < (livelock_fallback >> 1)) { 374 printf("intr %d at %d hz, removing livelock limit\n", 375 intr, freq); 376 ill_state[intr] = LIVELOCK_NONE; 377 systimer_del(&ill_rtimer[intr]); 378 } 379 break; 380 } 381 382 /* 383 * There are two races here. irunning[] is set by sched_ithd() 384 * in the context of our cpu and is critical-section safe. We 385 * are responsible for checking it. ipending is not critical 386 * section safe and must be handled by the platform specific 387 * ithread_done() routine. 388 */ 389 if (irunning[intr] == 0) 390 ithread_done(intr); 391 /* must be in critical section on loop */ 392 } 393 /* not reached */ 394 } 395 396 /* 397 * Sysctls used by systat and others: hw.intrnames and hw.intrcnt. 398 * The data for this machine dependent, and the declarations are in machine 399 * dependent code. The layout of intrnames and intrcnt however is machine 400 * independent. 401 * 402 * We do not know the length of intrcnt and intrnames at compile time, so 403 * calculate things at run time. 404 */ 405 static int 406 sysctl_intrnames(SYSCTL_HANDLER_ARGS) 407 { 408 return (sysctl_handle_opaque(oidp, intrnames, eintrnames - intrnames, 409 req)); 410 } 411 412 SYSCTL_PROC(_hw, OID_AUTO, intrnames, CTLTYPE_OPAQUE | CTLFLAG_RD, 413 NULL, 0, sysctl_intrnames, "", "Interrupt Names"); 414 415 static int 416 sysctl_intrcnt(SYSCTL_HANDLER_ARGS) 417 { 418 return (sysctl_handle_opaque(oidp, intrcnt, 419 (char *)eintrcnt - (char *)intrcnt, req)); 420 } 421 422 SYSCTL_PROC(_hw, OID_AUTO, intrcnt, CTLTYPE_OPAQUE | CTLFLAG_RD, 423 NULL, 0, sysctl_intrcnt, "", "Interrupt Counts"); 424