1 files changed, 478 insertions, 0 deletions
diff --git a/kernel/irq/spurious.c b/kernel/irq/spurious.c
new file mode 100644
index 000000000..02b2daf07
--- /dev/null
+++ b/kernel/irq/spurious.c
@@ -0,0 +1,478 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
+ *
+ * This file contains spurious interrupt handling.
+ */
+
+#include <linux/jiffies.h>
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/moduleparam.h>
+#include <linux/timer.h>
+
+#include "internals.h"
+
+static int irqfixup __read_mostly;
+
+#define POLL_SPURIOUS_IRQ_INTERVAL (HZ/10)
+static void poll_spurious_irqs(struct timer_list *unused);
+static DEFINE_TIMER(poll_spurious_irq_timer, poll_spurious_irqs);
+static int irq_poll_cpu;
+static atomic_t irq_poll_active;
+
+/*
+ * We wait here for a poller to finish.
+ *
+ * If the poll runs on this CPU, then we yell loudly and return
+ * false. That will leave the interrupt line disabled in the worst
+ * case, but it should never happen.
+ *
+ * We wait until the poller is done and then recheck disabled and
+ * action (about to be disabled). Only if it's still active, we return
+ * true and let the handler run.
+ */
+bool irq_wait_for_poll(struct irq_desc *desc)
+	__must_hold(&desc->lock)
+{
+	if (WARN_ONCE(irq_poll_cpu == smp_processor_id(),
+		      "irq poll in progress on cpu %d for irq %d\n",
+		      smp_processor_id(), desc->irq_data.irq))
+		return false;
+
+#ifdef CONFIG_SMP
+	do {
+		raw_spin_unlock(&desc->lock);
+		while (irqd_irq_inprogress(&desc->irq_data))
+			cpu_relax();
+		raw_spin_lock(&desc->lock);
+	} while (irqd_irq_inprogress(&desc->irq_data));
+	/* Might have been disabled in meantime */
+	return !irqd_irq_disabled(&desc->irq_data) && desc->action;
+#else
+	return false;
+#endif
+}
+
+
+/*
+ * Recovery handler for misrouted interrupts.
+ */
+static int try_one_irq(struct irq_desc *desc, bool force)
+{
+	irqreturn_t ret = IRQ_NONE;
+	struct irqaction *action;
+
+	raw_spin_lock(&desc->lock);
+
+	/*
+	 * PER_CPU, nested thread interrupts and interrupts explicitly
+	 * marked polled are excluded from polling.
+	 */
+	if (irq_settings_is_per_cpu(desc) ||
+	    irq_settings_is_nested_thread(desc) ||
+	    irq_settings_is_polled(desc))
+		goto out;
+
+	/*
+	 * Do not poll disabled interrupts unless the spurious
+	 * disabled poller asks explicitly.
+	 */
+	if (irqd_irq_disabled(&desc->irq_data) && !force)
+		goto out;
+
+	/*
+	 * All handlers must agree on IRQF_SHARED, so we test just the
+	 * first.
+	 */
+	action = desc->action;
+	if (!action || !(action->flags & IRQF_SHARED) ||
+	    (action->flags & __IRQF_TIMER))
+		goto out;
+
+	/* Already running on another processor */
+	if (irqd_irq_inprogress(&desc->irq_data)) {
+		/*
+		 * Already running: If it is shared get the other
+		 * CPU to go looking for our mystery interrupt too
+		 */
+		desc->istate |= IRQS_PENDING;
+		goto out;
+	}
+
+	/* Mark it poll in progress */
+	desc->istate |= IRQS_POLL_INPROGRESS;
+	do {
+		if (handle_irq_event(desc) == IRQ_HANDLED)
+			ret = IRQ_HANDLED;
+		/* Make sure that there is still a valid action */
+		action = desc->action;
+	} while ((desc->istate & IRQS_PENDING) && action);
+	desc->istate &= ~IRQS_POLL_INPROGRESS;
+out:
+	raw_spin_unlock(&desc->lock);
+	return ret == IRQ_HANDLED;
+}
+
+static int misrouted_irq(int irq)
+{
+	struct irq_desc *desc;
+	int i, ok = 0;
+
+	if (atomic_inc_return(&irq_poll_active) != 1)
+		goto out;
+
+	irq_poll_cpu = smp_processor_id();
+
+	for_each_irq_desc(i, desc) {
+		if (!i)
+			 continue;
+
+		if (i == irq)	/* Already tried */
+			continue;
+
+		if (try_one_irq(desc, false))
+			ok = 1;
+	}
+out:
+	atomic_dec(&irq_poll_active);
+	/* So the caller can adjust the irq error counts */
+	return ok;
+}
+
+static void poll_spurious_irqs(struct timer_list *unused)
+{
+	struct irq_desc *desc;
+	int i;
+
+	if (atomic_inc_return(&irq_poll_active) != 1)
+		goto out;
+	irq_poll_cpu = smp_processor_id();
+
+	for_each_irq_desc(i, desc) {
+		unsigned int state;
+
+		if (!i)
+			 continue;
+
+		/* Racy but it doesn't matter */
+		state = desc->istate;
+		barrier();
+		if (!(state & IRQS_SPURIOUS_DISABLED))
+			continue;
+
+		local_irq_disable();
+		try_one_irq(desc, true);
+		local_irq_enable();
+	}
+out:
+	atomic_dec(&irq_poll_active);
+	mod_timer(&poll_spurious_irq_timer,
+		  jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
+}
+
+static inline int bad_action_ret(irqreturn_t action_ret)
+{
+	unsigned int r = action_ret;
+
+	if (likely(r <= (IRQ_HANDLED | IRQ_WAKE_THREAD)))
+		return 0;
+	return 1;
+}
+
+/*
+ * If 99,900 of the previous 100,000 interrupts have not been handled
+ * then assume that the IRQ is stuck in some manner. Drop a diagnostic
+ * and try to turn the IRQ off.
+ *
+ * (The other 100-of-100,000 interrupts may have been a correctly
+ *  functioning device sharing an IRQ with the failing one)
+ */
+static void __report_bad_irq(struct irq_desc *desc, irqreturn_t action_ret)
+{
+	unsigned int irq = irq_desc_get_irq(desc);
+	struct irqaction *action;
+	unsigned long flags;
+
+	if (bad_action_ret(action_ret)) {
+		printk(KERN_ERR "irq event %d: bogus return value %x\n",
+				irq, action_ret);
+	} else {
+		printk(KERN_ERR "irq %d: nobody cared (try booting with "
+				"the \"irqpoll\" option)\n", irq);
+	}
+	dump_stack();
+	printk(KERN_ERR "handlers:\n");
+
+	/*
+	 * We need to take desc->lock here. note_interrupt() is called
+	 * w/o desc->lock held, but IRQ_PROGRESS set. We might race
+	 * with something else removing an action. It's ok to take
+	 * desc->lock here. See synchronize_irq().
+	 */
+	raw_spin_lock_irqsave(&desc->lock, flags);
+	for_each_action_of_desc(desc, action) {
+		printk(KERN_ERR "[<%p>] %ps", action->handler, action->handler);
+		if (action->thread_fn)
+			printk(KERN_CONT " threaded [<%p>] %ps",
+					action->thread_fn, action->thread_fn);
+		printk(KERN_CONT "\n");
+	}
+	raw_spin_unlock_irqrestore(&desc->lock, flags);
+}
+
+static void report_bad_irq(struct irq_desc *desc, irqreturn_t action_ret)
+{
+	static int count = 100;
+
+	if (count > 0) {
+		count--;
+		__report_bad_irq(desc, action_ret);
+	}
+}
+
+static inline int
+try_misrouted_irq(unsigned int irq, struct irq_desc *desc,
+		  irqreturn_t action_ret)
+{
+	struct irqaction *action;
+
+	if (!irqfixup)
+		return 0;
+
+	/* We didn't actually handle the IRQ - see if it was misrouted? */
+	if (action_ret == IRQ_NONE)
+		return 1;
+
+	/*
+	 * But for 'irqfixup == 2' we also do it for handled interrupts if
+	 * they are marked as IRQF_IRQPOLL (or for irq zero, which is the
+	 * traditional PC timer interrupt.. Legacy)
+	 */
+	if (irqfixup < 2)
+		return 0;
+
+	if (!irq)
+		return 1;
+
+	/*
+	 * Since we don't get the descriptor lock, "action" can
+	 * change under us.  We don't really care, but we don't
+	 * want to follow a NULL pointer. So tell the compiler to
+	 * just load it once by using a barrier.
+	 */
+	action = desc->action;
+	barrier();
+	return action && (action->flags & IRQF_IRQPOLL);
+}
+
+#define SPURIOUS_DEFERRED	0x80000000
+
+void note_interrupt(struct irq_desc *desc, irqreturn_t action_ret)
+{
+	unsigned int irq;
+
+	if (desc->istate & IRQS_POLL_INPROGRESS ||
+	    irq_settings_is_polled(desc))
+		return;
+
+	if (bad_action_ret(action_ret)) {
+		report_bad_irq(desc, action_ret);
+		return;
+	}
+
+	/*
+	 * We cannot call note_interrupt from the threaded handler
+	 * because we need to look at the compound of all handlers
+	 * (primary and threaded). Aside of that in the threaded
+	 * shared case we have no serialization against an incoming
+	 * hardware interrupt while we are dealing with a threaded
+	 * result.
+	 *
+	 * So in case a thread is woken, we just note the fact and
+	 * defer the analysis to the next hardware interrupt.
+	 *
+	 * The threaded handlers store whether they successfully
+	 * handled an interrupt and we check whether that number
+	 * changed versus the last invocation.
+	 *
+	 * We could handle all interrupts with the delayed by one
+	 * mechanism, but for the non forced threaded case we'd just
+	 * add pointless overhead to the straight hardirq interrupts
+	 * for the sake of a few lines less code.
+	 */
+	if (action_ret & IRQ_WAKE_THREAD) {
+		/*
+		 * There is a thread woken. Check whether one of the
+		 * shared primary handlers returned IRQ_HANDLED. If
+		 * not we defer the spurious detection to the next
+		 * interrupt.
+		 */
+		if (action_ret == IRQ_WAKE_THREAD) {
+			int handled;
+			/*
+			 * We use bit 31 of thread_handled_last to
+			 * denote the deferred spurious detection
+			 * active. No locking necessary as
+			 * thread_handled_last is only accessed here
+			 * and we have the guarantee that hard
+			 * interrupts are not reentrant.
+			 */
+			if (!(desc->threads_handled_last & SPURIOUS_DEFERRED)) {
+				desc->threads_handled_last |= SPURIOUS_DEFERRED;
+				return;
+			}
+			/*
+			 * Check whether one of the threaded handlers
+			 * returned IRQ_HANDLED since the last
+			 * interrupt happened.
+			 *
+			 * For simplicity we just set bit 31, as it is
+			 * set in threads_handled_last as well. So we
+			 * avoid extra masking. And we really do not
+			 * care about the high bits of the handled
+			 * count. We just care about the count being
+			 * different than the one we saw before.
+			 */
+			handled = atomic_read(&desc->threads_handled);
+			handled |= SPURIOUS_DEFERRED;
+			if (handled != desc->threads_handled_last) {
+				action_ret = IRQ_HANDLED;
+				/*
+				 * Note: We keep the SPURIOUS_DEFERRED
+				 * bit set. We are handling the
+				 * previous invocation right now.
+				 * Keep it for the current one, so the
+				 * next hardware interrupt will
+				 * account for it.
+				 */
+				desc->threads_handled_last = handled;
+			} else {
+				/*
+				 * None of the threaded handlers felt
+				 * responsible for the last interrupt
+				 *
+				 * We keep the SPURIOUS_DEFERRED bit
+				 * set in threads_handled_last as we
+				 * need to account for the current
+				 * interrupt as well.
+				 */
+				action_ret = IRQ_NONE;
+			}
+		} else {
+			/*
+			 * One of the primary handlers returned
+			 * IRQ_HANDLED. So we don't care about the
+			 * threaded handlers on the same line. Clear
+			 * the deferred detection bit.
+			 *
+			 * In theory we could/should check whether the
+			 * deferred bit is set and take the result of
+			 * the previous run into account here as
+			 * well. But it's really not worth the
+			 * trouble. If every other interrupt is
+			 * handled we never trigger the spurious
+			 * detector. And if this is just the one out
+			 * of 100k unhandled ones which is handled
+			 * then we merily delay the spurious detection
+			 * by one hard interrupt. Not a real problem.
+			 */
+			desc->threads_handled_last &= ~SPURIOUS_DEFERRED;
+		}
+	}
+
+	if (unlikely(action_ret == IRQ_NONE)) {
+		/*
+		 * If we are seeing only the odd spurious IRQ caused by
+		 * bus asynchronicity then don't eventually trigger an error,
+		 * otherwise the counter becomes a doomsday timer for otherwise
+		 * working systems
+		 */
+		if (time_after(jiffies, desc->last_unhandled + HZ/10))
+			desc->irqs_unhandled = 1;
+		else
+			desc->irqs_unhandled++;
+		desc->last_unhandled = jiffies;
+	}
+
+	irq = irq_desc_get_irq(desc);
+	if (unlikely(try_misrouted_irq(irq, desc, action_ret))) {
+		int ok = misrouted_irq(irq);
+		if (action_ret == IRQ_NONE)
+			desc->irqs_unhandled -= ok;
+	}
+
+	if (likely(!desc->irqs_unhandled))
+		return;
+
+	/* Now getting into unhandled irq detection */
+	desc->irq_count++;
+	if (likely(desc->irq_count < 100000))
+		return;
+
+	desc->irq_count = 0;
+	if (unlikely(desc->irqs_unhandled > 99900)) {
+		/*
+		 * The interrupt is stuck
+		 */
+		__report_bad_irq(desc, action_ret);
+		/*
+		 * Now kill the IRQ
+		 */
+		printk(KERN_EMERG "Disabling IRQ #%d\n", irq);
+		desc->istate |= IRQS_SPURIOUS_DISABLED;
+		desc->depth++;
+		irq_disable(desc);
+
+		mod_timer(&poll_spurious_irq_timer,
+			  jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
+	}
+	desc->irqs_unhandled = 0;
+}
+
+bool noirqdebug __read_mostly;
+
+int noirqdebug_setup(char *str)
+{
+	noirqdebug = 1;
+	printk(KERN_INFO "IRQ lockup detection disabled\n");
+
+	return 1;
+}
+
+__setup("noirqdebug", noirqdebug_setup);
+module_param(noirqdebug, bool, 0644);
+MODULE_PARM_DESC(noirqdebug, "Disable irq lockup detection when true");
+
+static int __init irqfixup_setup(char *str)
+{
+	if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
+		pr_warn("irqfixup boot option not supported with PREEMPT_RT\n");
+		return 1;
+	}
+	irqfixup = 1;
+	printk(KERN_WARNING "Misrouted IRQ fixup support enabled.\n");
+	printk(KERN_WARNING "This may impact system performance.\n");
+
+	return 1;
+}
+
+__setup("irqfixup", irqfixup_setup);
+module_param(irqfixup, int, 0644);
+
+static int __init irqpoll_setup(char *str)
+{
+	if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
+		pr_warn("irqpoll boot option not supported with PREEMPT_RT\n");
+		return 1;
+	}
+	irqfixup = 2;
+	printk(KERN_WARNING "Misrouted IRQ fixup and polling support "
+				"enabled\n");
+	printk(KERN_WARNING "This may significantly impact system "
+				"performance\n");
+	return 1;
+}
+
+__setup("irqpoll", irqpoll_setup);