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(nr: IRQTF_WARNED, addr: &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(nr: IRQTF_RUNTHREAD, addr: &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(v: &desc->threads_active);
135
136 wake_up_process(tsk: action->thread);
137}
138
139static DEFINE_STATIC_KEY_FALSE(irqhandler_duration_check_enabled);
140static u64 irqhandler_duration_threshold_ns __ro_after_init;
141
142static int __init irqhandler_duration_check_setup(char *arg)
143{
144 unsigned long val;
145 int ret;
146
147 ret = kstrtoul(s: arg, base: 0, res: &val);
148 if (ret) {
149 pr_err("Unable to parse irqhandler.duration_warn_us setting: ret=%d\n", ret);
150 return 0;
151 }
152
153 if (!val) {
154 pr_err("Invalid irqhandler.duration_warn_us setting, must be > 0\n");
155 return 0;
156 }
157
158 irqhandler_duration_threshold_ns = val * 1000;
159 static_branch_enable(&irqhandler_duration_check_enabled);
160
161 return 1;
162}
163__setup("irqhandler.duration_warn_us=", irqhandler_duration_check_setup);
164
165static inline void irqhandler_duration_check(u64 ts_start, unsigned int irq,
166 const struct irqaction *action)
167{
168 u64 delta_ns = local_clock() - ts_start;
169
170 if (unlikely(delta_ns > irqhandler_duration_threshold_ns)) {
171 pr_warn_ratelimited("[CPU%u] long duration of IRQ[%u:%ps], took: %llu us\n",
172 smp_processor_id(), irq, action->handler,
173 div_u64(delta_ns, NSEC_PER_USEC));
174 }
175}
176
177irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc)
178{
179 irqreturn_t retval = IRQ_NONE;
180 unsigned int irq = desc->irq_data.irq;
181 struct irqaction *action;
182
183 record_irq_time(desc);
184
185 for_each_action_of_desc(desc, action) {
186 irqreturn_t res;
187
188 /*
189 * If this IRQ would be threaded under force_irqthreads, mark it so.
190 */
191 if (irq_settings_can_thread(desc) &&
192 !(action->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT)))
193 lockdep_hardirq_threaded();
194
195 trace_irq_handler_entry(irq, action);
196
197 if (static_branch_unlikely(&irqhandler_duration_check_enabled)) {
198 u64 ts_start = local_clock();
199
200 res = action->handler(irq, action->dev_id);
201 irqhandler_duration_check(ts_start, irq, action);
202 } else {
203 res = action->handler(irq, action->dev_id);
204 }
205
206 trace_irq_handler_exit(irq, action, ret: res);
207
208 if (WARN_ONCE(!irqs_disabled(),"irq %u handler %pS enabled interrupts\n",
209 irq, action->handler))
210 local_irq_disable();
211
212 switch (res) {
213 case IRQ_WAKE_THREAD:
214 /*
215 * Catch drivers which return WAKE_THREAD but
216 * did not set up a thread function
217 */
218 if (unlikely(!action->thread_fn)) {
219 warn_no_thread(irq, action);
220 break;
221 }
222
223 __irq_wake_thread(desc, action);
224 break;
225
226 default:
227 break;
228 }
229
230 retval |= res;
231 }
232
233 return retval;
234}
235
236irqreturn_t handle_irq_event_percpu(struct irq_desc *desc)
237{
238 irqreturn_t retval;
239
240 retval = __handle_irq_event_percpu(desc);
241
242 add_interrupt_randomness(irq: desc->irq_data.irq);
243
244 if (!irq_settings_no_debug(desc))
245 note_interrupt(desc, action_ret: retval);
246 return retval;
247}
248
249irqreturn_t handle_irq_event(struct irq_desc *desc)
250{
251 irqreturn_t ret;
252
253 desc->istate &= ~IRQS_PENDING;
254 irqd_set(d: &desc->irq_data, mask: IRQD_IRQ_INPROGRESS);
255 raw_spin_unlock(&desc->lock);
256
257 ret = handle_irq_event_percpu(desc);
258
259 raw_spin_lock(&desc->lock);
260 irqd_clear(d: &desc->irq_data, mask: IRQD_IRQ_INPROGRESS);
261 return ret;
262}
263
264#ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER
265int __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
266{
267 if (handle_arch_irq)
268 return -EBUSY;
269
270 handle_arch_irq = handle_irq;
271 return 0;
272}
273
274/**
275 * generic_handle_arch_irq - root irq handler for architectures which do no
276 * entry accounting themselves
277 * @regs: Register file coming from the low-level handling code
278 */
279asmlinkage void noinstr generic_handle_arch_irq(struct pt_regs *regs)
280{
281 struct pt_regs *old_regs;
282
283 irq_enter();
284 old_regs = set_irq_regs(regs);
285 handle_arch_irq(regs);
286 set_irq_regs(old_regs);
287 irq_exit();
288}
289#endif
290