kernel/irq/handle.c

   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