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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 for_each_action_of_desc(desc, action) {
192 irqreturn_t res;
193
194 /*
195 * If this IRQ would be threaded under force_irqthreads, mark it so.
196 */
197 if (irq_settings_can_thread(desc) &&
198 !(action->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT)))
199 lockdep_hardirq_threaded();
200
201 trace_irq_handler_entry(irq, action);
202
203 if (static_branch_unlikely(&irqhandler_duration_check_enabled)) {
204 u64 ts_start = local_clock();
205
206 res = action->handler(irq, action->dev_id);
207 irqhandler_duration_check(ts_start, irq, action);
208 } else {
209 res = action->handler(irq, action->dev_id);
210 }
211
212 trace_irq_handler_exit(irq, action, res);
213
214 if (WARN_ONCE(!irqs_disabled(),"irq %u handler %pS enabled interrupts\n",
215 irq, action->handler))
216 local_irq_disable();
217
218 switch (res) {
219 case IRQ_WAKE_THREAD:
220 /*
221 * Catch drivers which return WAKE_THREAD but
222 * did not set up a thread function
223 */
224 if (unlikely(!action->thread_fn)) {
225 warn_no_thread(irq, action);
226 break;
227 }
228
229 __irq_wake_thread(desc, action);
230 break;
231
232 default:
233 break;
234 }
235
236 retval |= res;
237 }
238
239 return retval;
240}
241
242irqreturn_t handle_irq_event_percpu(struct irq_desc *desc)
243{
244 irqreturn_t retval;
245
246 retval = __handle_irq_event_percpu(desc);
247
248 add_interrupt_randomness(desc->irq_data.irq);
249
250 if (!irq_settings_no_debug(desc))
251 note_interrupt(desc, retval);
252 return retval;
253}
254
255irqreturn_t handle_irq_event(struct irq_desc *desc)
256{
257 irqreturn_t ret;
258
259 desc->istate &= ~IRQS_PENDING;
260 irqd_set(&desc->irq_data, IRQD_IRQ_INPROGRESS);
261 raw_spin_unlock(&desc->lock);
262
263 ret = handle_irq_event_percpu(desc);
264
265 raw_spin_lock(&desc->lock);
266 irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);
267 return ret;
268}
269
270#ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER
271int __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
272{
273 if (handle_arch_irq)
274 return -EBUSY;
275
276 handle_arch_irq = handle_irq;
277 return 0;
278}
279
280/**
281 * generic_handle_arch_irq - root irq handler for architectures which do no
282 * entry accounting themselves
283 * @regs: Register file coming from the low-level handling code
284 */
285asmlinkage void noinstr generic_handle_arch_irq(struct pt_regs *regs)
286{
287 struct pt_regs *old_regs;
288
289 irq_enter();
290 old_regs = set_irq_regs(regs);
291 handle_arch_irq(regs);
292 set_irq_regs(old_regs);
293 irq_exit();
294}
295#endif