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
5 *
6 * This file contains the IRQ-resend code
7 *
8 * If the interrupt is waiting to be processed, we try to re-run it.
9 * We can't directly run it from here since the caller might be in an
10 * interrupt-protected region. Not all irq controller chips can
11 * retrigger interrupts at the hardware level, so in those cases
12 * we allow the resending of IRQs via a tasklet.
13 */
14
15 #include <linux/irq.h>
16 #include <linux/module.h>
17 #include <linux/random.h>
18 #include <linux/interrupt.h>
19
20 #include "internals.h"
21
22 #ifdef CONFIG_HARDIRQS_SW_RESEND
23
24 /* hlist_head to handle software resend of interrupts: */
25 static HLIST_HEAD(irq_resend_list);
26 static DEFINE_RAW_SPINLOCK(irq_resend_lock);
27
28 /*
29 * Run software resends of IRQ's
30 */
resend_irqs(struct tasklet_struct * unused)31 static void resend_irqs(struct tasklet_struct *unused)
32 {
33 guard(raw_spinlock_irq)(&irq_resend_lock);
34 while (!hlist_empty(&irq_resend_list)) {
35 struct irq_desc *desc;
36
37 desc = hlist_entry(irq_resend_list.first, struct irq_desc, resend_node);
38 hlist_del_init(&desc->resend_node);
39
40 raw_spin_unlock(&irq_resend_lock);
41 desc->handle_irq(desc);
42 raw_spin_lock(&irq_resend_lock);
43 }
44 }
45
46 /* Tasklet to handle resend: */
47 static DECLARE_TASKLET(resend_tasklet, resend_irqs);
48
irq_sw_resend(struct irq_desc * desc)49 static int irq_sw_resend(struct irq_desc *desc)
50 {
51 /*
52 * Validate whether this interrupt can be safely injected from
53 * non interrupt context
54 */
55 if (irqd_is_handle_enforce_irqctx(&desc->irq_data))
56 return -EINVAL;
57
58 /*
59 * If the interrupt is running in the thread context of the parent
60 * irq we need to be careful, because we cannot trigger it
61 * directly.
62 */
63 if (irq_settings_is_nested_thread(desc)) {
64 /*
65 * If the parent_irq is valid, we retrigger the parent,
66 * otherwise we do nothing.
67 */
68 if (!desc->parent_irq)
69 return -EINVAL;
70
71 desc = irq_to_desc(desc->parent_irq);
72 if (!desc)
73 return -EINVAL;
74 }
75
76 /* Add to resend_list and activate the softirq: */
77 scoped_guard(raw_spinlock, &irq_resend_lock) {
78 if (hlist_unhashed(&desc->resend_node))
79 hlist_add_head(&desc->resend_node, &irq_resend_list);
80 }
81 tasklet_schedule(&resend_tasklet);
82 return 0;
83 }
84
clear_irq_resend(struct irq_desc * desc)85 void clear_irq_resend(struct irq_desc *desc)
86 {
87 guard(raw_spinlock)(&irq_resend_lock);
88 hlist_del_init(&desc->resend_node);
89 }
90
irq_resend_init(struct irq_desc * desc)91 void irq_resend_init(struct irq_desc *desc)
92 {
93 INIT_HLIST_NODE(&desc->resend_node);
94 }
95 #else
clear_irq_resend(struct irq_desc * desc)96 void clear_irq_resend(struct irq_desc *desc) {}
irq_resend_init(struct irq_desc * desc)97 void irq_resend_init(struct irq_desc *desc) {}
98
irq_sw_resend(struct irq_desc * desc)99 static int irq_sw_resend(struct irq_desc *desc)
100 {
101 return -EINVAL;
102 }
103 #endif
104
try_retrigger(struct irq_desc * desc)105 static int try_retrigger(struct irq_desc *desc)
106 {
107 if (desc->irq_data.chip->irq_retrigger)
108 return desc->irq_data.chip->irq_retrigger(&desc->irq_data);
109
110 #ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
111 return irq_chip_retrigger_hierarchy(&desc->irq_data);
112 #else
113 return 0;
114 #endif
115 }
116
117 /*
118 * IRQ resend
119 *
120 * Is called with interrupts disabled and desc->lock held.
121 */
check_irq_resend(struct irq_desc * desc,bool inject)122 int check_irq_resend(struct irq_desc *desc, bool inject)
123 {
124 int err = 0;
125
126 /*
127 * We do not resend level type interrupts. Level type interrupts
128 * are resent by hardware when they are still active. Clear the
129 * pending bit so suspend/resume does not get confused.
130 */
131 if (irq_settings_is_level(desc)) {
132 desc->istate &= ~IRQS_PENDING;
133 return -EINVAL;
134 }
135
136 if (desc->istate & IRQS_REPLAY)
137 return -EBUSY;
138
139 if (!(desc->istate & IRQS_PENDING) && !inject)
140 return 0;
141
142 desc->istate &= ~IRQS_PENDING;
143
144 if (!try_retrigger(desc))
145 err = irq_sw_resend(desc);
146
147 /* If the retrigger was successful, mark it with the REPLAY bit */
148 if (!err)
149 desc->istate |= IRQS_REPLAY;
150 return err;
151 }
152
153 #ifdef CONFIG_GENERIC_IRQ_INJECTION
154 /**
155 * irq_inject_interrupt - Inject an interrupt for testing/error injection
156 * @irq: The interrupt number
157 *
158 * This function must only be used for debug and testing purposes!
159 *
160 * Especially on x86 this can cause a premature completion of an interrupt
161 * affinity change causing the interrupt line to become stale. Very
162 * unlikely, but possible.
163 *
164 * The injection can fail for various reasons:
165 * - Interrupt is not activated
166 * - Interrupt is NMI type or currently replaying
167 * - Interrupt is level type
168 * - Interrupt does not support hardware retrigger and software resend is
169 * either not enabled or not possible for the interrupt.
170 */
irq_inject_interrupt(unsigned int irq)171 int irq_inject_interrupt(unsigned int irq)
172 {
173 int err = -EINVAL;
174
175 /* Try the state injection hardware interface first */
176 if (!irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING, true))
177 return 0;
178
179 /* That failed, try via the resend mechanism */
180 scoped_irqdesc_get_and_buslock(irq, 0) {
181 struct irq_desc *desc = scoped_irqdesc;
182
183 /*
184 * Only try to inject when the interrupt is:
185 * - not NMI type
186 * - activated
187 */
188 if (!irq_is_nmi(desc) && irqd_is_activated(&desc->irq_data))
189 err = check_irq_resend(desc, true);
190 }
191 return err;
192 }
193 EXPORT_SYMBOL_GPL(irq_inject_interrupt);
194 #endif
195