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 */ handle_bad_irq(struct irq_desc * desc)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 */ no_action(int cpl,void * dev_id)46 irqreturn_t no_action(int cpl, void *dev_id) 47 { 48 return IRQ_NONE; 49 } 50 EXPORT_SYMBOL_GPL(no_action); 51 warn_no_thread(unsigned int irq,struct irqaction * action)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 __irq_wake_thread(struct irq_desc * desc,struct irqaction * action)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 __handle_irq_event_percpu(struct irq_desc * desc)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 handle_irq_event_percpu(struct irq_desc * desc)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 handle_irq_event(struct irq_desc * desc)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 set_handle_irq(void (* handle_irq)(struct pt_regs *))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 */ generic_handle_arch_irq(struct pt_regs * regs)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