handle.c

  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	/*
137	 * This might be a premature wakeup before the thread reached the
138	 * thread function and set the IRQTF_READY bit. It's waiting in
139	 * kthread code with state UNINTERRUPTIBLE. Once it reaches the
140	 * thread function it waits with INTERRUPTIBLE. The wakeup is not
141	 * lost in that case because the thread is guaranteed to observe
142	 * the RUN flag before it goes to sleep in wait_for_interrupt().
143	 */
144	wake_up_state(action->thread, TASK_INTERRUPTIBLE);
145}
146
147static DEFINE_STATIC_KEY_FALSE(irqhandler_duration_check_enabled);
148static u64 irqhandler_duration_threshold_ns __ro_after_init;
149
150static int __init irqhandler_duration_check_setup(char *arg)
151{
152	unsigned long val;
153	int ret;
154
155	ret = kstrtoul(arg, 0, &val);
156	if (ret) {
157		pr_err("Unable to parse irqhandler.duration_warn_us setting: ret=%d\n", ret);
158		return 0;
159	}
160
161	if (!val) {
162		pr_err("Invalid irqhandler.duration_warn_us setting, must be > 0\n");
163		return 0;
164	}
165
166	irqhandler_duration_threshold_ns = val * 1000;
167	static_branch_enable(&irqhandler_duration_check_enabled);
168
169	return 1;
170}
171__setup("irqhandler.duration_warn_us=", irqhandler_duration_check_setup);
172
173static inline void irqhandler_duration_check(u64 ts_start, unsigned int irq,
174					     const struct irqaction *action)
175{
176	u64 delta_ns = local_clock() - ts_start;
177
178	if (unlikely(delta_ns > irqhandler_duration_threshold_ns)) {
179		pr_warn_ratelimited("[CPU%u] long duration of IRQ[%u:%ps], took: %llu us\n",
180				    smp_processor_id(), irq, action->handler,
181				    div_u64(delta_ns, NSEC_PER_USEC));
182	}
183}
184
185irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc)
186{
187	irqreturn_t retval = IRQ_NONE;
188	unsigned int irq = desc->irq_data.irq;
189	struct irqaction *action;
190
191	record_irq_time(desc);
192
193	for_each_action_of_desc(desc, action) {
194		irqreturn_t res;
195
196		/*
197		 * If this IRQ would be threaded under force_irqthreads, mark it so.
198		 */
199		if (irq_settings_can_thread(desc) &&
200		    !(action->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT)))
201			lockdep_hardirq_threaded();
202
203		trace_irq_handler_entry(irq, action);
204
205		if (static_branch_unlikely(&irqhandler_duration_check_enabled)) {
206			u64 ts_start = local_clock();
207
208			res = action->handler(irq, action->dev_id);
209			irqhandler_duration_check(ts_start, irq, action);
210		} else {
211			res = action->handler(irq, action->dev_id);
212		}
213
214		trace_irq_handler_exit(irq, action, res);
215
216		if (WARN_ONCE(!irqs_disabled(),"irq %u handler %pS enabled interrupts\n",
217			      irq, action->handler))
218			local_irq_disable();
219
220		switch (res) {
221		case IRQ_WAKE_THREAD:
222			/*
223			 * Catch drivers which return WAKE_THREAD but
224			 * did not set up a thread function
225			 */
226			if (unlikely(!action->thread_fn)) {
227				warn_no_thread(irq, action);
228				break;
229			}
230
231			__irq_wake_thread(desc, action);
232			break;
233
234		default:
235			break;
236		}
237
238		retval |= res;
239	}
240
241	return retval;
242}
243
244irqreturn_t handle_irq_event_percpu(struct irq_desc *desc)
245{
246	irqreturn_t retval;
247
248	retval = __handle_irq_event_percpu(desc);
249
250	add_interrupt_randomness(desc->irq_data.irq);
251
252	if (!irq_settings_no_debug(desc))
253		note_interrupt(desc, retval);
254	return retval;
255}
256
257irqreturn_t handle_irq_event(struct irq_desc *desc)
258{
259	irqreturn_t ret;
260
261	desc->istate &= ~IRQS_PENDING;
262	irqd_set(&desc->irq_data, IRQD_IRQ_INPROGRESS);
263	raw_spin_unlock(&desc->lock);
264
265	ret = handle_irq_event_percpu(desc);
266
267	raw_spin_lock(&desc->lock);
268	irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);
269	return ret;
270}
271
272#ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER
273int __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
274{
275	if (handle_arch_irq)
276		return -EBUSY;
277
278	handle_arch_irq = handle_irq;
279	return 0;
280}
281
282/**
283 * generic_handle_arch_irq - root irq handler for architectures which do no
284 *                           entry accounting themselves
285 * @regs:	Register file coming from the low-level handling code
286 */
287asmlinkage void noinstr generic_handle_arch_irq(struct pt_regs *regs)
288{
289	struct pt_regs *old_regs;
290
291	irq_enter();
292	old_regs = set_irq_regs(regs);
293	handle_arch_irq(regs);
294	set_irq_regs(old_regs);
295	irq_exit();
296}
297#endif