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
17static int irqfixup __read_mostly;
18
19#define POLL_SPURIOUS_IRQ_INTERVAL (HZ/10)
20static void poll_spurious_irqs(struct timer_list *unused);
21static DEFINE_TIMER(poll_spurious_irq_timer, poll_spurious_irqs);
22static int irq_poll_cpu;
23static 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 */
36bool 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 */
62static 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;
113out:
114	raw_spin_unlock(&desc->lock);
115	return ret == IRQ_HANDLED;
116}
117
118static 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	}
138out:
139	atomic_dec(&irq_poll_active);
140	/* So the caller can adjust the irq error counts */
141	return ok;
142}
143
144static 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	}
169out:
170	atomic_dec(&irq_poll_active);
171	mod_timer(&poll_spurious_irq_timer,
172		  jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
173}
174
175static 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 */
192static 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
225static 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
235static inline int
236try_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
272void 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
434bool noirqdebug __read_mostly;
435
436int 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);
445module_param(noirqdebug, bool, 0644);
446MODULE_PARM_DESC(noirqdebug, "Disable irq lockup detection when true");
447
448static 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);
462module_param(irqfixup, int, 0644);
463
464static 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