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
24 void (*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 */
33 void 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 }
41 EXPORT_SYMBOL_GPL(handle_bad_irq);
42
43 /*
44 * Special, empty irq handler:
45 */
46 irqreturn_t no_action(int cpl, void *dev_id)
47 {
48 return IRQ_NONE;
49 }
50 EXPORT_SYMBOL_GPL(no_action);
51
52 static 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
61 void __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
139 irqreturn_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
189 irqreturn_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
202 irqreturn_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
218 int __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 */
232 asmlinkage 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
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