1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
4  *
5  * This file contains spurious interrupt handling.
6  */
7 
8 #include <linux/jiffies.h>
9 #include <linux/irq.h>
10 #include <linux/module.h>
11 #include <linux/interrupt.h>
12 #include <linux/moduleparam.h>
13 #include <linux/timer.h>
14 
15 #include "internals.h"
16 
17 static int irqfixup __read_mostly;
18 
19 #define POLL_SPURIOUS_IRQ_INTERVAL (HZ/10)
20 static void poll_spurious_irqs(struct timer_list *unused);
21 static DEFINE_TIMER(poll_spurious_irq_timer, poll_spurious_irqs);
22 static int irq_poll_cpu;
23 static atomic_t irq_poll_active;
24 
25 /*
26  * We wait here for a poller to finish.
27  *
28  * If the poll runs on this CPU, then we yell loudly and return
29  * false. That will leave the interrupt line disabled in the worst
30  * case, but it should never happen.
31  *
32  * We wait until the poller is done and then recheck disabled and
33  * action (about to be disabled). Only if it's still active, we return
34  * true and let the handler run.
35  */
irq_wait_for_poll(struct irq_desc * desc)36 bool irq_wait_for_poll(struct irq_desc *desc)
37 	__must_hold(&desc->lock)
38 {
39 	if (WARN_ONCE(irq_poll_cpu == smp_processor_id(),
40 		      "irq poll in progress on cpu %d for irq %d\n",
41 		      smp_processor_id(), desc->irq_data.irq))
42 		return false;
43 
44 #ifdef CONFIG_SMP
45 	do {
46 		raw_spin_unlock(&desc->lock);
47 		while (irqd_irq_inprogress(&desc->irq_data))
48 			cpu_relax();
49 		raw_spin_lock(&desc->lock);
50 	} while (irqd_irq_inprogress(&desc->irq_data));
51 	/* Might have been disabled in meantime */
52 	return !irqd_irq_disabled(&desc->irq_data) && desc->action;
53 #else
54 	return false;
55 #endif
56 }
57 
58 
59 /*
60  * Recovery handler for misrouted interrupts.
61  */
try_one_irq(struct irq_desc * desc,bool force)62 static int try_one_irq(struct irq_desc *desc, bool force)
63 {
64 	irqreturn_t ret = IRQ_NONE;
65 	struct irqaction *action;
66 
67 	raw_spin_lock(&desc->lock);
68 
69 	/*
70 	 * PER_CPU, nested thread interrupts and interrupts explicitly
71 	 * marked polled are excluded from polling.
72 	 */
73 	if (irq_settings_is_per_cpu(desc) ||
74 	    irq_settings_is_nested_thread(desc) ||
75 	    irq_settings_is_polled(desc))
76 		goto out;
77 
78 	/*
79 	 * Do not poll disabled interrupts unless the spurious
80 	 * disabled poller asks explicitly.
81 	 */
82 	if (irqd_irq_disabled(&desc->irq_data) && !force)
83 		goto out;
84 
85 	/*
86 	 * All handlers must agree on IRQF_SHARED, so we test just the
87 	 * first.
88 	 */
89 	action = desc->action;
90 	if (!action || !(action->flags & IRQF_SHARED) ||
91 	    (action->flags & __IRQF_TIMER))
92 		goto out;
93 
94 	/* Already running on another processor */
95 	if (irqd_irq_inprogress(&desc->irq_data)) {
96 		/*
97 		 * Already running: If it is shared get the other
98 		 * CPU to go looking for our mystery interrupt too
99 		 */
100 		desc->istate |= IRQS_PENDING;
101 		goto out;
102 	}
103 
104 	/* Mark it poll in progress */
105 	desc->istate |= IRQS_POLL_INPROGRESS;
106 	do {
107 		if (handle_irq_event(desc) == IRQ_HANDLED)
108 			ret = IRQ_HANDLED;
109 		/* Make sure that there is still a valid action */
110 		action = desc->action;
111 	} while ((desc->istate & IRQS_PENDING) && action);
112 	desc->istate &= ~IRQS_POLL_INPROGRESS;
113 out:
114 	raw_spin_unlock(&desc->lock);
115 	return ret == IRQ_HANDLED;
116 }
117 
misrouted_irq(int irq)118 static int misrouted_irq(int irq)
119 {
120 	struct irq_desc *desc;
121 	int i, ok = 0;
122 
123 	if (atomic_inc_return(&irq_poll_active) != 1)
124 		goto out;
125 
126 	irq_poll_cpu = smp_processor_id();
127 
128 	for_each_irq_desc(i, desc) {
129 		if (!i)
130 			 continue;
131 
132 		if (i == irq)	/* Already tried */
133 			continue;
134 
135 		if (try_one_irq(desc, false))
136 			ok = 1;
137 	}
138 out:
139 	atomic_dec(&irq_poll_active);
140 	/* So the caller can adjust the irq error counts */
141 	return ok;
142 }
143 
poll_spurious_irqs(struct timer_list * unused)144 static void poll_spurious_irqs(struct timer_list *unused)
145 {
146 	struct irq_desc *desc;
147 	int i;
148 
149 	if (atomic_inc_return(&irq_poll_active) != 1)
150 		goto out;
151 	irq_poll_cpu = smp_processor_id();
152 
153 	for_each_irq_desc(i, desc) {
154 		unsigned int state;
155 
156 		if (!i)
157 			 continue;
158 
159 		/* Racy but it doesn't matter */
160 		state = desc->istate;
161 		barrier();
162 		if (!(state & IRQS_SPURIOUS_DISABLED))
163 			continue;
164 
165 		local_irq_disable();
166 		try_one_irq(desc, true);
167 		local_irq_enable();
168 	}
169 out:
170 	atomic_dec(&irq_poll_active);
171 	mod_timer(&poll_spurious_irq_timer,
172 		  jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
173 }
174 
bad_action_ret(irqreturn_t action_ret)175 static inline int bad_action_ret(irqreturn_t action_ret)
176 {
177 	unsigned int r = action_ret;
178 
179 	if (likely(r <= (IRQ_HANDLED | IRQ_WAKE_THREAD)))
180 		return 0;
181 	return 1;
182 }
183 
184 /*
185  * If 99,900 of the previous 100,000 interrupts have not been handled
186  * then assume that the IRQ is stuck in some manner. Drop a diagnostic
187  * and try to turn the IRQ off.
188  *
189  * (The other 100-of-100,000 interrupts may have been a correctly
190  *  functioning device sharing an IRQ with the failing one)
191  */
__report_bad_irq(struct irq_desc * desc,irqreturn_t action_ret)192 static void __report_bad_irq(struct irq_desc *desc, irqreturn_t action_ret)
193 {
194 	unsigned int irq = irq_desc_get_irq(desc);
195 	struct irqaction *action;
196 	unsigned long flags;
197 
198 	if (bad_action_ret(action_ret)) {
199 		printk(KERN_ERR "irq event %d: bogus return value %x\n",
200 				irq, action_ret);
201 	} else {
202 		printk(KERN_ERR "irq %d: nobody cared (try booting with "
203 				"the \"irqpoll\" option)\n", irq);
204 	}
205 	dump_stack();
206 	printk(KERN_ERR "handlers:\n");
207 
208 	/*
209 	 * We need to take desc->lock here. note_interrupt() is called
210 	 * w/o desc->lock held, but IRQ_PROGRESS set. We might race
211 	 * with something else removing an action. It's ok to take
212 	 * desc->lock here. See synchronize_irq().
213 	 */
214 	raw_spin_lock_irqsave(&desc->lock, flags);
215 	for_each_action_of_desc(desc, action) {
216 		printk(KERN_ERR "[<%p>] %ps", action->handler, action->handler);
217 		if (action->thread_fn)
218 			printk(KERN_CONT " threaded [<%p>] %ps",
219 					action->thread_fn, action->thread_fn);
220 		printk(KERN_CONT "\n");
221 	}
222 	raw_spin_unlock_irqrestore(&desc->lock, flags);
223 }
224 
report_bad_irq(struct irq_desc * desc,irqreturn_t action_ret)225 static void report_bad_irq(struct irq_desc *desc, irqreturn_t action_ret)
226 {
227 	static int count = 100;
228 
229 	if (count > 0) {
230 		count--;
231 		__report_bad_irq(desc, action_ret);
232 	}
233 }
234 
235 static inline int
try_misrouted_irq(unsigned int irq,struct irq_desc * desc,irqreturn_t action_ret)236 try_misrouted_irq(unsigned int irq, struct irq_desc *desc,
237 		  irqreturn_t action_ret)
238 {
239 	struct irqaction *action;
240 
241 	if (!irqfixup)
242 		return 0;
243 
244 	/* We didn't actually handle the IRQ - see if it was misrouted? */
245 	if (action_ret == IRQ_NONE)
246 		return 1;
247 
248 	/*
249 	 * But for 'irqfixup == 2' we also do it for handled interrupts if
250 	 * they are marked as IRQF_IRQPOLL (or for irq zero, which is the
251 	 * traditional PC timer interrupt.. Legacy)
252 	 */
253 	if (irqfixup < 2)
254 		return 0;
255 
256 	if (!irq)
257 		return 1;
258 
259 	/*
260 	 * Since we don't get the descriptor lock, "action" can
261 	 * change under us.  We don't really care, but we don't
262 	 * want to follow a NULL pointer. So tell the compiler to
263 	 * just load it once by using a barrier.
264 	 */
265 	action = desc->action;
266 	barrier();
267 	return action && (action->flags & IRQF_IRQPOLL);
268 }
269 
270 #define SPURIOUS_DEFERRED	0x80000000
271 
note_interrupt(struct irq_desc * desc,irqreturn_t action_ret)272 void note_interrupt(struct irq_desc *desc, irqreturn_t action_ret)
273 {
274 	unsigned int irq;
275 
276 	if (desc->istate & IRQS_POLL_INPROGRESS ||
277 	    irq_settings_is_polled(desc))
278 		return;
279 
280 	if (bad_action_ret(action_ret)) {
281 		report_bad_irq(desc, action_ret);
282 		return;
283 	}
284 
285 	/*
286 	 * We cannot call note_interrupt from the threaded handler
287 	 * because we need to look at the compound of all handlers
288 	 * (primary and threaded). Aside of that in the threaded
289 	 * shared case we have no serialization against an incoming
290 	 * hardware interrupt while we are dealing with a threaded
291 	 * result.
292 	 *
293 	 * So in case a thread is woken, we just note the fact and
294 	 * defer the analysis to the next hardware interrupt.
295 	 *
296 	 * The threaded handlers store whether they successfully
297 	 * handled an interrupt and we check whether that number
298 	 * changed versus the last invocation.
299 	 *
300 	 * We could handle all interrupts with the delayed by one
301 	 * mechanism, but for the non forced threaded case we'd just
302 	 * add pointless overhead to the straight hardirq interrupts
303 	 * for the sake of a few lines less code.
304 	 */
305 	if (action_ret & IRQ_WAKE_THREAD) {
306 		/*
307 		 * There is a thread woken. Check whether one of the
308 		 * shared primary handlers returned IRQ_HANDLED. If
309 		 * not we defer the spurious detection to the next
310 		 * interrupt.
311 		 */
312 		if (action_ret == IRQ_WAKE_THREAD) {
313 			int handled;
314 			/*
315 			 * We use bit 31 of thread_handled_last to
316 			 * denote the deferred spurious detection
317 			 * active. No locking necessary as
318 			 * thread_handled_last is only accessed here
319 			 * and we have the guarantee that hard
320 			 * interrupts are not reentrant.
321 			 */
322 			if (!(desc->threads_handled_last & SPURIOUS_DEFERRED)) {
323 				desc->threads_handled_last |= SPURIOUS_DEFERRED;
324 				return;
325 			}
326 			/*
327 			 * Check whether one of the threaded handlers
328 			 * returned IRQ_HANDLED since the last
329 			 * interrupt happened.
330 			 *
331 			 * For simplicity we just set bit 31, as it is
332 			 * set in threads_handled_last as well. So we
333 			 * avoid extra masking. And we really do not
334 			 * care about the high bits of the handled
335 			 * count. We just care about the count being
336 			 * different than the one we saw before.
337 			 */
338 			handled = atomic_read(&desc->threads_handled);
339 			handled |= SPURIOUS_DEFERRED;
340 			if (handled != desc->threads_handled_last) {
341 				action_ret = IRQ_HANDLED;
342 				/*
343 				 * Note: We keep the SPURIOUS_DEFERRED
344 				 * bit set. We are handling the
345 				 * previous invocation right now.
346 				 * Keep it for the current one, so the
347 				 * next hardware interrupt will
348 				 * account for it.
349 				 */
350 				desc->threads_handled_last = handled;
351 			} else {
352 				/*
353 				 * None of the threaded handlers felt
354 				 * responsible for the last interrupt
355 				 *
356 				 * We keep the SPURIOUS_DEFERRED bit
357 				 * set in threads_handled_last as we
358 				 * need to account for the current
359 				 * interrupt as well.
360 				 */
361 				action_ret = IRQ_NONE;
362 			}
363 		} else {
364 			/*
365 			 * One of the primary handlers returned
366 			 * IRQ_HANDLED. So we don't care about the
367 			 * threaded handlers on the same line. Clear
368 			 * the deferred detection bit.
369 			 *
370 			 * In theory we could/should check whether the
371 			 * deferred bit is set and take the result of
372 			 * the previous run into account here as
373 			 * well. But it's really not worth the
374 			 * trouble. If every other interrupt is
375 			 * handled we never trigger the spurious
376 			 * detector. And if this is just the one out
377 			 * of 100k unhandled ones which is handled
378 			 * then we merily delay the spurious detection
379 			 * by one hard interrupt. Not a real problem.
380 			 */
381 			desc->threads_handled_last &= ~SPURIOUS_DEFERRED;
382 		}
383 	}
384 
385 	if (unlikely(action_ret == IRQ_NONE)) {
386 		/*
387 		 * If we are seeing only the odd spurious IRQ caused by
388 		 * bus asynchronicity then don't eventually trigger an error,
389 		 * otherwise the counter becomes a doomsday timer for otherwise
390 		 * working systems
391 		 */
392 		if (time_after(jiffies, desc->last_unhandled + HZ/10))
393 			desc->irqs_unhandled = 1;
394 		else
395 			desc->irqs_unhandled++;
396 		desc->last_unhandled = jiffies;
397 	}
398 
399 	irq = irq_desc_get_irq(desc);
400 	if (unlikely(try_misrouted_irq(irq, desc, action_ret))) {
401 		int ok = misrouted_irq(irq);
402 		if (action_ret == IRQ_NONE)
403 			desc->irqs_unhandled -= ok;
404 	}
405 
406 	if (likely(!desc->irqs_unhandled))
407 		return;
408 
409 	/* Now getting into unhandled irq detection */
410 	desc->irq_count++;
411 	if (likely(desc->irq_count < 100000))
412 		return;
413 
414 	desc->irq_count = 0;
415 	if (unlikely(desc->irqs_unhandled > 99900)) {
416 		/*
417 		 * The interrupt is stuck
418 		 */
419 		__report_bad_irq(desc, action_ret);
420 		/*
421 		 * Now kill the IRQ
422 		 */
423 		printk(KERN_EMERG "Disabling IRQ #%d\n", irq);
424 		desc->istate |= IRQS_SPURIOUS_DISABLED;
425 		desc->depth++;
426 		irq_disable(desc);
427 
428 		mod_timer(&poll_spurious_irq_timer,
429 			  jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
430 	}
431 	desc->irqs_unhandled = 0;
432 }
433 
434 bool noirqdebug __read_mostly;
435 
noirqdebug_setup(char * str)436 int noirqdebug_setup(char *str)
437 {
438 	noirqdebug = 1;
439 	printk(KERN_INFO "IRQ lockup detection disabled\n");
440 
441 	return 1;
442 }
443 
444 __setup("noirqdebug", noirqdebug_setup);
445 module_param(noirqdebug, bool, 0644);
446 MODULE_PARM_DESC(noirqdebug, "Disable irq lockup detection when true");
447 
irqfixup_setup(char * str)448 static int __init irqfixup_setup(char *str)
449 {
450 	if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
451 		pr_warn("irqfixup boot option not supported with PREEMPT_RT\n");
452 		return 1;
453 	}
454 	irqfixup = 1;
455 	printk(KERN_WARNING "Misrouted IRQ fixup support enabled.\n");
456 	printk(KERN_WARNING "This may impact system performance.\n");
457 
458 	return 1;
459 }
460 
461 __setup("irqfixup", irqfixup_setup);
462 module_param(irqfixup, int, 0644);
463 
irqpoll_setup(char * str)464 static int __init irqpoll_setup(char *str)
465 {
466 	if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
467 		pr_warn("irqpoll boot option not supported with PREEMPT_RT\n");
468 		return 1;
469 	}
470 	irqfixup = 2;
471 	printk(KERN_WARNING "Misrouted IRQ fixup and polling support "
472 				"enabled\n");
473 	printk(KERN_WARNING "This may significantly impact system "
474 				"performance\n");
475 	return 1;
476 }
477 
478 __setup("irqpoll", irqpoll_setup);
479