// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
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* Copyright (C) 2005-2006, Thomas Gleixner, Russell King
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*
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* This file contains the core interrupt handling code. Detailed
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* information is available in Documentation/core-api/genericirq.rst
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*
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*/
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#include <linux/irq.h>
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#include <linux/random.h>
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#include <linux/sched.h>
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#include <linux/interrupt.h>
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#include <linux/kernel_stat.h>
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#include <trace/events/irq.h>
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#include "internals.h"
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#ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER
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void (*handle_arch_irq)(struct pt_regs *) __ro_after_init;
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#endif
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/**
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* handle_bad_irq - handle spurious and unhandled irqs
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* @desc: description of the interrupt
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*
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* Handles spurious and unhandled IRQ's. It also prints a debugmessage.
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*/
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void handle_bad_irq(struct irq_desc *desc)
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{
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unsigned int irq = irq_desc_get_irq(desc);
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print_irq_desc(irq, desc);
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kstat_incr_irqs_this_cpu(desc);
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ack_bad_irq(irq);
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}
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EXPORT_SYMBOL_GPL(handle_bad_irq);
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/*
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* Special, empty irq handler:
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*/
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irqreturn_t no_action(int cpl, void *dev_id)
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{
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return IRQ_NONE;
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}
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EXPORT_SYMBOL_GPL(no_action);
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static void warn_no_thread(unsigned int irq, struct irqaction *action)
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{
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if (test_and_set_bit(IRQTF_WARNED, &action->thread_flags))
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return;
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printk(KERN_WARNING "IRQ %d device %s returned IRQ_WAKE_THREAD "
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"but no thread function available.", irq, action->name);
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}
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void __irq_wake_thread(struct irq_desc *desc, struct irqaction *action)
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{
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/*
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* In case the thread crashed and was killed we just pretend that
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* we handled the interrupt. The hardirq handler has disabled the
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* device interrupt, so no irq storm is lurking.
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*/
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if (action->thread->flags & PF_EXITING)
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return;
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/*
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* Wake up the handler thread for this action. If the
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* RUNTHREAD bit is already set, nothing to do.
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*/
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if (test_and_set_bit(IRQTF_RUNTHREAD, &action->thread_flags))
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return;
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/*
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* It's safe to OR the mask lockless here. We have only two
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* places which write to threads_oneshot: This code and the
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* irq thread.
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*
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* This code is the hard irq context and can never run on two
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* cpus in parallel. If it ever does we have more serious
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* problems than this bitmask.
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*
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* The irq threads of this irq which clear their "running" bit
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* in threads_oneshot are serialized via desc->lock against
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* each other and they are serialized against this code by
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* IRQS_INPROGRESS.
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*
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* Hard irq handler:
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*
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* spin_lock(desc->lock);
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* desc->state |= IRQS_INPROGRESS;
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* spin_unlock(desc->lock);
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* set_bit(IRQTF_RUNTHREAD, &action->thread_flags);
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* desc->threads_oneshot |= mask;
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* spin_lock(desc->lock);
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* desc->state &= ~IRQS_INPROGRESS;
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* spin_unlock(desc->lock);
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*
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* irq thread:
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*
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* again:
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* spin_lock(desc->lock);
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* if (desc->state & IRQS_INPROGRESS) {
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* spin_unlock(desc->lock);
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* while(desc->state & IRQS_INPROGRESS)
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* cpu_relax();
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* goto again;
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* }
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* if (!test_bit(IRQTF_RUNTHREAD, &action->thread_flags))
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* desc->threads_oneshot &= ~mask;
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* spin_unlock(desc->lock);
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*
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* So either the thread waits for us to clear IRQS_INPROGRESS
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* or we are waiting in the flow handler for desc->lock to be
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* released before we reach this point. The thread also checks
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* IRQTF_RUNTHREAD under desc->lock. If set it leaves
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* threads_oneshot untouched and runs the thread another time.
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*/
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desc->threads_oneshot |= action->thread_mask;
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/*
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* We increment the threads_active counter in case we wake up
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* the irq thread. The irq thread decrements the counter when
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* it returns from the handler or in the exit path and wakes
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* up waiters which are stuck in synchronize_irq() when the
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* active count becomes zero. synchronize_irq() is serialized
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* against this code (hard irq handler) via IRQS_INPROGRESS
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* like the finalize_oneshot() code. See comment above.
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*/
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atomic_inc(&desc->threads_active);
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wake_up_process(action->thread);
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}
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irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc, unsigned int *flags)
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{
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irqreturn_t retval = IRQ_NONE;
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unsigned int irq = desc->irq_data.irq;
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struct irqaction *action;
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record_irq_time(desc);
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for_each_action_of_desc(desc, action) {
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irqreturn_t res;
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/*
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* If this IRQ would be threaded under force_irqthreads, mark it so.
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*/
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if (irq_settings_can_thread(desc) &&
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!(action->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT)))
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lockdep_hardirq_threaded();
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trace_irq_handler_entry(irq, action);
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res = action->handler(irq, action->dev_id);
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trace_irq_handler_exit(irq, action, res);
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if (WARN_ONCE(!irqs_disabled(),"irq %u handler %pS enabled interrupts\n",
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irq, action->handler))
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local_irq_disable();
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switch (res) {
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case IRQ_WAKE_THREAD:
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/*
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* Catch drivers which return WAKE_THREAD but
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* did not set up a thread function
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*/
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if (unlikely(!action->thread_fn)) {
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warn_no_thread(irq, action);
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break;
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}
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__irq_wake_thread(desc, action);
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fallthrough; /* to add to randomness */
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case IRQ_HANDLED:
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*flags |= action->flags;
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break;
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default:
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break;
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}
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retval |= res;
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}
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return retval;
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}
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irqreturn_t handle_irq_event_percpu(struct irq_desc *desc)
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{
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irqreturn_t retval;
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unsigned int flags = 0;
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retval = __handle_irq_event_percpu(desc, &flags);
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add_interrupt_randomness(desc->irq_data.irq);
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if (!noirqdebug)
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note_interrupt(desc, retval);
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return retval;
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}
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irqreturn_t handle_irq_event(struct irq_desc *desc)
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{
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irqreturn_t ret;
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desc->istate &= ~IRQS_PENDING;
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irqd_set(&desc->irq_data, IRQD_IRQ_INPROGRESS);
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raw_spin_unlock(&desc->lock);
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ret = handle_irq_event_percpu(desc);
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raw_spin_lock(&desc->lock);
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irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);
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return ret;
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}
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#ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER
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int __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
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{
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if (handle_arch_irq)
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return -EBUSY;
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handle_arch_irq = handle_irq;
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return 0;
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}
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#endif
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