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 1.21 2005/06/06 15:02:27 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 intrmask_t *maskptr; /* LEGACY */ 49 void *argument; 50 const char *name; 51 int intr; 52 } intrec_t; 53 54 static intrec_t *intlists[NHWI+NSWI]; 55 static thread_t ithreads[NHWI+NSWI]; 56 static struct thread ithread_ary[NHWI+NSWI]; 57 static struct random_softc irandom_ary[NHWI+NSWI]; 58 static int irunning[NHWI+NSWI]; 59 static u_int ill_count[NHWI+NSWI]; /* interrupt livelock counter */ 60 static u_int ill_ticks[NHWI+NSWI]; /* track elapsed to calculate freq */ 61 static u_int ill_delta[NHWI+NSWI]; /* track elapsed to calculate freq */ 62 static int ill_state[NHWI+NSWI]; /* current state */ 63 static struct systimer ill_timer[NHWI+NSWI]; /* enforced freq. timer */ 64 static struct systimer ill_rtimer[NHWI+NSWI]; /* recovery timer */ 65 static intrmask_t dummy_intr_mask; 66 67 #define LIVELOCK_NONE 0 68 #define LIVELOCK_LIMITED 1 69 70 static int livelock_limit = 50000; 71 static int livelock_fallback = 20000; 72 SYSCTL_INT(_kern, OID_AUTO, livelock_limit, 73 CTLFLAG_RW, &livelock_limit, 0, "Livelock interrupt rate limit"); 74 SYSCTL_INT(_kern, OID_AUTO, livelock_fallback, 75 CTLFLAG_RW, &livelock_fallback, 0, "Livelock interrupt fallback rate"); 76 77 static void ithread_handler(void *arg); 78 79 /* 80 * Register an SWI or INTerrupt handler. 81 * 82 * Note that maskptr exists to support legacy spl handling and is not intended 83 * to be permanent (because spls are not compatible with BGL removal). 84 */ 85 thread_t 86 register_swi(int intr, inthand2_t *handler, void *arg, const char *name, 87 intrmask_t *maskptr) 88 { 89 if (intr < NHWI || intr >= NHWI + NSWI) 90 panic("register_swi: bad intr %d", intr); 91 return(register_int(intr, handler, arg, name, maskptr)); 92 } 93 94 thread_t 95 register_int(int intr, inthand2_t *handler, void *arg, const char *name, 96 intrmask_t *maskptr) 97 { 98 intrec_t **list; 99 intrec_t *rec; 100 thread_t td; 101 102 if (intr < 0 || intr >= NHWI + NSWI) 103 panic("register_int: bad intr %d", intr); 104 if (maskptr == NULL) 105 maskptr = &dummy_intr_mask; 106 107 rec = malloc(sizeof(intrec_t), M_DEVBUF, M_NOWAIT); 108 if (rec == NULL) 109 panic("register_swi: malloc failed"); 110 rec->handler = handler; 111 rec->maskptr = maskptr; 112 rec->argument = arg; 113 rec->name = name; 114 rec->intr = intr; 115 rec->next = NULL; 116 117 list = &intlists[intr]; 118 119 /* 120 * Create an interrupt thread if necessary, leave it in an unscheduled 121 * state. 122 */ 123 if ((td = ithreads[intr]) == NULL) { 124 lwkt_create((void *)ithread_handler, (void *)intr, &ithreads[intr], 125 &ithread_ary[intr], TDF_STOPREQ|TDF_INTTHREAD, -1, 126 "ithread %d", intr); 127 td = ithreads[intr]; 128 if (intr >= NHWI && intr < NHWI + NSWI) 129 lwkt_setpri(td, TDPRI_SOFT_NORM); 130 else 131 lwkt_setpri(td, TDPRI_INT_MED); 132 } 133 134 /* 135 * Add the record to the interrupt list 136 */ 137 crit_enter(); /* token */ 138 while (*list != NULL) 139 list = &(*list)->next; 140 *list = rec; 141 crit_exit(); 142 return(td); 143 } 144 145 void 146 unregister_swi(int intr, inthand2_t *handler) 147 { 148 if (intr < NHWI || intr >= NHWI + NSWI) 149 panic("register_swi: bad intr %d", intr); 150 unregister_int(intr, handler); 151 } 152 153 void 154 unregister_int(int intr, inthand2_t handler) 155 { 156 intrec_t **list; 157 intrec_t *rec; 158 159 if (intr < 0 || intr > NHWI + NSWI) 160 panic("register_int: bad intr %d", intr); 161 list = &intlists[intr]; 162 crit_enter(); 163 while ((rec = *list) != NULL) { 164 if (rec->handler == (void *)handler) { 165 *list = rec->next; 166 break; 167 } 168 list = &rec->next; 169 } 170 crit_exit(); 171 if (rec != NULL) { 172 free(rec, M_DEVBUF); 173 } else { 174 printf("warning: unregister_int: int %d handler %p not found\n", 175 intr, handler); 176 } 177 } 178 179 void 180 swi_setpriority(int intr, int pri) 181 { 182 struct thread *td; 183 184 if (intr < NHWI || intr >= NHWI + NSWI) 185 panic("register_swi: bad intr %d", intr); 186 if ((td = ithreads[intr]) != NULL) 187 lwkt_setpri(td, pri); 188 } 189 190 void 191 register_randintr(int intr) 192 { 193 struct random_softc *sc = &irandom_ary[intr]; 194 sc->sc_intr = intr; 195 sc->sc_enabled = 1; 196 } 197 198 void 199 unregister_randintr(int intr) 200 { 201 struct random_softc *sc = &irandom_ary[intr]; 202 sc->sc_enabled = 0; 203 } 204 205 /* 206 * Dispatch an interrupt. If there's nothing to do we have a stray 207 * interrupt and can just return, leaving the interrupt masked. 208 * 209 * We need to schedule the interrupt and set its irunning[] bit. If 210 * we are not on the interrupt thread's cpu we have to send a message 211 * to the correct cpu that will issue the desired action (interlocking 212 * with the interrupt thread's critical section). 213 * 214 * We are NOT in a critical section, which will allow the scheduled 215 * interrupt to preempt us. The MP lock might *NOT* be held here. 216 */ 217 static void 218 sched_ithd_remote(void *arg) 219 { 220 sched_ithd((int)arg); 221 } 222 223 void 224 sched_ithd(int intr) 225 { 226 thread_t td; 227 228 if ((td = ithreads[intr]) != NULL) { 229 if (intlists[intr] == NULL) { 230 printf("sched_ithd: stray interrupt %d\n", intr); 231 } else { 232 if (td->td_gd == mycpu) { 233 irunning[intr] = 1; 234 lwkt_schedule(td); /* preemption handled internally */ 235 } else { 236 lwkt_send_ipiq(td->td_gd, sched_ithd_remote, (void *)intr); 237 } 238 } 239 } else { 240 printf("sched_ithd: stray interrupt %d\n", intr); 241 } 242 } 243 244 /* 245 * This is run from a periodic SYSTIMER (and thus must be MP safe, the BGL 246 * might not be held). 247 */ 248 static void 249 ithread_livelock_wakeup(systimer_t info) 250 { 251 int intr = (int)info->data; 252 thread_t td; 253 254 if ((td = ithreads[intr]) != NULL) 255 lwkt_schedule(td); 256 } 257 258 259 /* 260 * Interrupt threads run this as their main loop. 261 * 262 * The handler begins execution outside a critical section and with the BGL 263 * held. 264 * 265 * The irunning state starts at 0. When an interrupt occurs, the hardware 266 * interrupt is disabled and sched_ithd() The HW interrupt remains disabled 267 * until all routines have run. We then call ithread_done() to reenable 268 * the HW interrupt and deschedule us until the next interrupt. 269 * 270 * We are responsible for atomically checking irunning[] and ithread_done() 271 * is responsible for atomically checking for platform-specific delayed 272 * interrupts. irunning[] for our irq is only set in the context of our cpu, 273 * so a critical section is a sufficient interlock. 274 */ 275 #define LIVELOCK_TIMEFRAME(freq) ((freq) >> 2) /* 1/4 second */ 276 277 static void 278 ithread_handler(void *arg) 279 { 280 int intr = (int)arg; 281 int freq; 282 u_int bticks; 283 u_int cputicks; 284 intrec_t **list = &intlists[intr]; 285 intrec_t *rec; 286 intrec_t *nrec; 287 struct random_softc *sc = &irandom_ary[intr]; 288 globaldata_t gd = mycpu; 289 290 /* 291 * The loop must be entered with one critical section held. 292 */ 293 crit_enter_gd(gd); 294 295 for (;;) { 296 /* 297 * We can get woken up by the livelock periodic code too, run the 298 * handlers only if there is a real interrupt pending. XXX 299 * 300 * Clear irunning[] prior to running the handlers to interlock 301 * again new events occuring during processing of existing events. 302 * 303 * For now run each handler in a critical section. 304 */ 305 irunning[intr] = 0; 306 for (rec = *list; rec; rec = nrec) { 307 nrec = rec->next; 308 rec->handler(rec->argument); 309 } 310 311 /* 312 * Do a quick exit/enter to catch any higher-priority 313 * interrupt sources and so user/system/interrupt statistics 314 * work for interrupt threads. 315 */ 316 crit_exit_gd(gd); 317 crit_enter_gd(gd); 318 319 /* 320 * This is our interrupt hook to add rate randomness to the random 321 * number generator. 322 */ 323 if (sc->sc_enabled) 324 add_interrupt_randomness(intr); 325 326 /* 327 * This is our livelock test. If we hit the rate limit we 328 * limit ourselves to X interrupts/sec until the rate 329 * falls below 50% of that value, then we unlimit again. 330 * 331 * XXX calling cputimer_count() is expensive but a livelock may 332 * prevent other interrupts from occuring so we cannot use ticks. 333 */ 334 cputicks = sys_cputimer->count(); 335 ++ill_count[intr]; 336 bticks = cputicks - ill_ticks[intr]; 337 ill_ticks[intr] = cputicks; 338 if (bticks > sys_cputimer->freq) 339 bticks = sys_cputimer->freq; 340 341 switch(ill_state[intr]) { 342 case LIVELOCK_NONE: 343 ill_delta[intr] += bticks; 344 if (ill_delta[intr] < LIVELOCK_TIMEFRAME(sys_cputimer->freq)) 345 break; 346 freq = (int64_t)ill_count[intr] * sys_cputimer->freq / 347 ill_delta[intr]; 348 ill_delta[intr] = 0; 349 ill_count[intr] = 0; 350 if (freq < livelock_limit) 351 break; 352 printf("intr %d at %d hz, livelocked! limiting at %d hz\n", 353 intr, freq, livelock_fallback); 354 ill_state[intr] = LIVELOCK_LIMITED; 355 bticks = 0; 356 /* force periodic check to avoid stale removal (if ints stop) */ 357 systimer_init_periodic(&ill_rtimer[intr], ithread_livelock_wakeup, 358 (void *)intr, 1); 359 /* fall through */ 360 case LIVELOCK_LIMITED: 361 /* 362 * Delay (us) before rearming the interrupt 363 */ 364 systimer_init_oneshot(&ill_timer[intr], ithread_livelock_wakeup, 365 (void *)intr, 1 + 1000000 / livelock_fallback); 366 lwkt_deschedule_self(curthread); 367 lwkt_switch(); 368 369 /* in case we were woken up by something else */ 370 systimer_del(&ill_timer[intr]); 371 372 /* 373 * Calculate interrupt rate (note that due to our delay it 374 * will not exceed livelock_fallback). 375 */ 376 ill_delta[intr] += bticks; 377 if (ill_delta[intr] < LIVELOCK_TIMEFRAME(sys_cputimer->freq)) 378 break; 379 freq = (int64_t)ill_count[intr] * sys_cputimer->freq / 380 ill_delta[intr]; 381 ill_delta[intr] = 0; 382 ill_count[intr] = 0; 383 if (freq < (livelock_fallback >> 1)) { 384 printf("intr %d at %d hz, removing livelock limit\n", 385 intr, freq); 386 ill_state[intr] = LIVELOCK_NONE; 387 systimer_del(&ill_rtimer[intr]); 388 } 389 break; 390 } 391 392 /* 393 * There are two races here. irunning[] is set by sched_ithd() 394 * in the context of our cpu and is critical-section safe. We 395 * are responsible for checking it. ipending is not critical 396 * section safe and must be handled by the platform specific 397 * ithread_done() routine. 398 */ 399 if (irunning[intr] == 0) 400 ithread_done(intr); 401 /* must be in critical section on loop */ 402 } 403 /* not reached */ 404 } 405 406 /* 407 * Sysctls used by systat and others: hw.intrnames and hw.intrcnt. 408 * The data for this machine dependent, and the declarations are in machine 409 * dependent code. The layout of intrnames and intrcnt however is machine 410 * independent. 411 * 412 * We do not know the length of intrcnt and intrnames at compile time, so 413 * calculate things at run time. 414 */ 415 static int 416 sysctl_intrnames(SYSCTL_HANDLER_ARGS) 417 { 418 return (sysctl_handle_opaque(oidp, intrnames, eintrnames - intrnames, 419 req)); 420 } 421 422 SYSCTL_PROC(_hw, OID_AUTO, intrnames, CTLTYPE_OPAQUE | CTLFLAG_RD, 423 NULL, 0, sysctl_intrnames, "", "Interrupt Names"); 424 425 static int 426 sysctl_intrcnt(SYSCTL_HANDLER_ARGS) 427 { 428 return (sysctl_handle_opaque(oidp, intrcnt, 429 (char *)eintrcnt - (char *)intrcnt, req)); 430 } 431 432 SYSCTL_PROC(_hw, OID_AUTO, intrcnt, CTLTYPE_OPAQUE | CTLFLAG_RD, 433 NULL, 0, sysctl_intrcnt, "", "Interrupt Counts"); 434