1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
4 * Copyright (C) 2005-2006, Thomas Gleixner, Russell King
5 *
6 * This file contains the core interrupt handling code. Detailed
7 * information is available in Documentation/core-api/genericirq.rst
8 *
9 */
10
11#include <linux/irq.h>
12#include <linux/random.h>
13#include <linux/sched.h>
14#include <linux/interrupt.h>
15#include <linux/kernel_stat.h>
16
17#include <asm/irq_regs.h>
18
19#include <trace/events/irq.h>
20
21#include "internals.h"
22
23#ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER
24void (*handle_arch_irq)(struct pt_regs *) __ro_after_init;
25#endif
26
27/**
28 * handle_bad_irq - handle spurious and unhandled irqs
29 * @desc:      description of the interrupt
30 *
31 * Handles spurious and unhandled IRQ's. It also prints a debugmessage.
32 */
33void handle_bad_irq(struct irq_desc *desc)
34{
35	unsigned int irq = irq_desc_get_irq(desc);
36
37	print_irq_desc(irq, desc);
38	kstat_incr_irqs_this_cpu(desc);
39	ack_bad_irq(irq);
40}
41EXPORT_SYMBOL_GPL(handle_bad_irq);
42
43/*
44 * Special, empty irq handler:
45 */
46irqreturn_t no_action(int cpl, void *dev_id)
47{
48	return IRQ_NONE;
49}
50EXPORT_SYMBOL_GPL(no_action);
51
52static void warn_no_thread(unsigned int irq, struct irqaction *action)
53{
54	if (test_and_set_bit(IRQTF_WARNED, &action->thread_flags))
55		return;
56
57	printk(KERN_WARNING "IRQ %d device %s returned IRQ_WAKE_THREAD "
58	       "but no thread function available.", irq, action->name);
59}
60
61void __irq_wake_thread(struct irq_desc *desc, struct irqaction *action)
62{
63	/*
64	 * In case the thread crashed and was killed we just pretend that
65	 * we handled the interrupt. The hardirq handler has disabled the
66	 * device interrupt, so no irq storm is lurking.
67	 */
68	if (action->thread->flags & PF_EXITING)
69		return;
70
71	/*
72	 * Wake up the handler thread for this action. If the
73	 * RUNTHREAD bit is already set, nothing to do.
74	 */
75	if (test_and_set_bit(IRQTF_RUNTHREAD, &action->thread_flags))
76		return;
77
78	/*
79	 * It's safe to OR the mask lockless here. We have only two
80	 * places which write to threads_oneshot: This code and the
81	 * irq thread.
82	 *
83	 * This code is the hard irq context and can never run on two
84	 * cpus in parallel. If it ever does we have more serious
85	 * problems than this bitmask.
86	 *
87	 * The irq threads of this irq which clear their "running" bit
88	 * in threads_oneshot are serialized via desc->lock against
89	 * each other and they are serialized against this code by
90	 * IRQS_INPROGRESS.
91	 *
92	 * Hard irq handler:
93	 *
94	 *	spin_lock(desc->lock);
95	 *	desc->state |= IRQS_INPROGRESS;
96	 *	spin_unlock(desc->lock);
97	 *	set_bit(IRQTF_RUNTHREAD, &action->thread_flags);
98	 *	desc->threads_oneshot |= mask;
99	 *	spin_lock(desc->lock);
100	 *	desc->state &= ~IRQS_INPROGRESS;
101	 *	spin_unlock(desc->lock);
102	 *
103	 * irq thread:
104	 *
105	 * again:
106	 *	spin_lock(desc->lock);
107	 *	if (desc->state & IRQS_INPROGRESS) {
108	 *		spin_unlock(desc->lock);
109	 *		while(desc->state & IRQS_INPROGRESS)
110	 *			cpu_relax();
111	 *		goto again;
112	 *	}
113	 *	if (!test_bit(IRQTF_RUNTHREAD, &action->thread_flags))
114	 *		desc->threads_oneshot &= ~mask;
115	 *	spin_unlock(desc->lock);
116	 *
117	 * So either the thread waits for us to clear IRQS_INPROGRESS
118	 * or we are waiting in the flow handler for desc->lock to be
119	 * released before we reach this point. The thread also checks
120	 * IRQTF_RUNTHREAD under desc->lock. If set it leaves
121	 * threads_oneshot untouched and runs the thread another time.
122	 */
123	desc->threads_oneshot |= action->thread_mask;
124
125	/*
126	 * We increment the threads_active counter in case we wake up
127	 * the irq thread. The irq thread decrements the counter when
128	 * it returns from the handler or in the exit path and wakes
129	 * up waiters which are stuck in synchronize_irq() when the
130	 * active count becomes zero. synchronize_irq() is serialized
131	 * against this code (hard irq handler) via IRQS_INPROGRESS
132	 * like the finalize_oneshot() code. See comment above.
133	 */
134	atomic_inc(&desc->threads_active);
135
136	wake_up_process(action->thread);
137}
138
139irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc)
140{
141	irqreturn_t retval = IRQ_NONE;
142	unsigned int irq = desc->irq_data.irq;
143	struct irqaction *action;
144
145	record_irq_time(desc);
146
147	for_each_action_of_desc(desc, action) {
148		irqreturn_t res;
149
150		/*
151		 * If this IRQ would be threaded under force_irqthreads, mark it so.
152		 */
153		if (irq_settings_can_thread(desc) &&
154		    !(action->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT)))
155			lockdep_hardirq_threaded();
156
157		trace_irq_handler_entry(irq, action);
158		res = action->handler(irq, action->dev_id);
159		trace_irq_handler_exit(irq, action, res);
160
161		if (WARN_ONCE(!irqs_disabled(),"irq %u handler %pS enabled interrupts\n",
162			      irq, action->handler))
163			local_irq_disable();
164
165		switch (res) {
166		case IRQ_WAKE_THREAD:
167			/*
168			 * Catch drivers which return WAKE_THREAD but
169			 * did not set up a thread function
170			 */
171			if (unlikely(!action->thread_fn)) {
172				warn_no_thread(irq, action);
173				break;
174			}
175
176			__irq_wake_thread(desc, action);
177			break;
178
179		default:
180			break;
181		}
182
183		retval |= res;
184	}
185
186	return retval;
187}
188
189irqreturn_t handle_irq_event_percpu(struct irq_desc *desc)
190{
191	irqreturn_t retval;
192
193	retval = __handle_irq_event_percpu(desc);
194
195	add_interrupt_randomness(desc->irq_data.irq);
196
197	if (!irq_settings_no_debug(desc))
198		note_interrupt(desc, retval);
199	return retval;
200}
201
202irqreturn_t handle_irq_event(struct irq_desc *desc)
203{
204	irqreturn_t ret;
205
206	desc->istate &= ~IRQS_PENDING;
207	irqd_set(&desc->irq_data, IRQD_IRQ_INPROGRESS);
208	raw_spin_unlock(&desc->lock);
209
210	ret = handle_irq_event_percpu(desc);
211
212	raw_spin_lock(&desc->lock);
213	irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);
214	return ret;
215}
216
217#ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER
218int __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
219{
220	if (handle_arch_irq)
221		return -EBUSY;
222
223	handle_arch_irq = handle_irq;
224	return 0;
225}
226
227/**
228 * generic_handle_arch_irq - root irq handler for architectures which do no
229 *                           entry accounting themselves
230 * @regs:	Register file coming from the low-level handling code
231 */
232asmlinkage void noinstr generic_handle_arch_irq(struct pt_regs *regs)
233{
234	struct pt_regs *old_regs;
235
236	irq_enter();
237	old_regs = set_irq_regs(regs);
238	handle_arch_irq(regs);
239	set_irq_regs(old_regs);
240	irq_exit();
241}
242#endif
243