kernel/irq/resend.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
   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  */
  31 static void resend_irqs(struct tasklet_struct *unused)
  32 {
  33         struct irq_desc *desc;
  34
  35         raw_spin_lock_irq(&irq_resend_lock);
  36         while (!hlist_empty(&irq_resend_list)) {
  37                 desc = hlist_entry(irq_resend_list.first, struct irq_desc,
  38                                    resend_node);
  39                 hlist_del_init(&desc->resend_node);
  40                 raw_spin_unlock(&irq_resend_lock);
  41                 desc->handle_irq(desc);
  42                 raw_spin_lock(&irq_resend_lock);
  43         }
  44         raw_spin_unlock_irq(&irq_resend_lock);
  45 }
  46
  47 /* Tasklet to handle resend: */
  48 static DECLARE_TASKLET(resend_tasklet, resend_irqs);
  49
  50 static int irq_sw_resend(struct irq_desc *desc)
  51 {
  52         /*
  53          * Validate whether this interrupt can be safely injected from
  54          * non interrupt context
  55          */
  56         if (handle_enforce_irqctx(&desc->irq_data))
  57                 return -EINVAL;
  58
  59         /*
  60          * If the interrupt is running in the thread context of the parent
  61          * irq we need to be careful, because we cannot trigger it
  62          * directly.
  63          */
  64         if (irq_settings_is_nested_thread(desc)) {
  65                 /*
  66                  * If the parent_irq is valid, we retrigger the parent,
  67                  * otherwise we do nothing.
  68                  */
  69                 if (!desc->parent_irq)
  70                         return -EINVAL;
  71
  72                 desc = irq_to_desc(desc->parent_irq);
  73                 if (!desc)
  74                         return -EINVAL;
  75         }
  76
  77         /* Add to resend_list and activate the softirq: */
  78         raw_spin_lock(&irq_resend_lock);
  79         if (hlist_unhashed(&desc->resend_node))
  80                 hlist_add_head(&desc->resend_node, &irq_resend_list);
  81         raw_spin_unlock(&irq_resend_lock);
  82         tasklet_schedule(&resend_tasklet);
  83         return 0;
  84 }
  85
  86 void clear_irq_resend(struct irq_desc *desc)
  87 {
  88         raw_spin_lock(&irq_resend_lock);
  89         hlist_del_init(&desc->resend_node);
  90         raw_spin_unlock(&irq_resend_lock);
  91 }
  92
  93 void irq_resend_init(struct irq_desc *desc)
  94 {
  95         INIT_HLIST_NODE(&desc->resend_node);
  96 }
  97 #else
  98 void clear_irq_resend(struct irq_desc *desc) {}
  99 void irq_resend_init(struct irq_desc *desc) {}
 100
 101 static int irq_sw_resend(struct irq_desc *desc)
 102 {
 103         return -EINVAL;
 104 }
 105 #endif
 106
 107 static int try_retrigger(struct irq_desc *desc)
 108 {
 109         if (desc->irq_data.chip->irq_retrigger)
 110                 return desc->irq_data.chip->irq_retrigger(&desc->irq_data);
 111
 112 #ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
 113         return irq_chip_retrigger_hierarchy(&desc->irq_data);
 114 #else
 115         return 0;
 116 #endif
 117 }
 118
 119 /*
 120  * IRQ resend
 121  *
 122  * Is called with interrupts disabled and desc->lock held.
 123  */
 124 int check_irq_resend(struct irq_desc *desc, bool inject)
 125 {
 126         int err = 0;
 127
 128         /*
 129          * We do not resend level type interrupts. Level type interrupts
 130          * are resent by hardware when they are still active. Clear the
 131          * pending bit so suspend/resume does not get confused.
 132          */
 133         if (irq_settings_is_level(desc)) {
 134                 desc->istate &= ~IRQS_PENDING;
 135                 return -EINVAL;
 136         }
 137
 138         if (desc->istate & IRQS_REPLAY)
 139                 return -EBUSY;
 140
 141         if (!(desc->istate & IRQS_PENDING) && !inject)
 142                 return 0;
 143
 144         desc->istate &= ~IRQS_PENDING;
 145
 146         if (!try_retrigger(desc))
 147                 err = irq_sw_resend(desc);
 148
 149         /* If the retrigger was successful, mark it with the REPLAY bit */
 150         if (!err)
 151                 desc->istate |= IRQS_REPLAY;
 152         return err;
 153 }
 154
 155 #ifdef CONFIG_GENERIC_IRQ_INJECTION
 156 /**
 157  * irq_inject_interrupt - Inject an interrupt for testing/error injection
 158  * @irq:        The interrupt number
 159  *
 160  * This function must only be used for debug and testing purposes!
 161  *
 162  * Especially on x86 this can cause a premature completion of an interrupt
 163  * affinity change causing the interrupt line to become stale. Very
 164  * unlikely, but possible.
 165  *
 166  * The injection can fail for various reasons:
 167  * - Interrupt is not activated
 168  * - Interrupt is NMI type or currently replaying
 169  * - Interrupt is level type
 170  * - Interrupt does not support hardware retrigger and software resend is
 171  *   either not enabled or not possible for the interrupt.
 172  */
 173 int irq_inject_interrupt(unsigned int irq)
 174 {
 175         struct irq_desc *desc;
 176         unsigned long flags;
 177         int err;
 178
 179         /* Try the state injection hardware interface first */
 180         if (!irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING, true))
 181                 return 0;
 182
 183         /* That failed, try via the resend mechanism */
 184         desc = irq_get_desc_buslock(irq, &flags, 0);
 185         if (!desc)
 186                 return -EINVAL;
 187
 188         /*
 189          * Only try to inject when the interrupt is:
 190          *  - not NMI type
 191          *  - activated
 192          */
 193         if (irq_is_nmi(desc) || !irqd_is_activated(&desc->irq_data))
 194                 err = -EINVAL;
 195         else
 196                 err = check_irq_resend(desc, true);
 197
 198         irq_put_desc_busunlock(desc, flags);
 199         return err;
 200 }
 201 EXPORT_SYMBOL_GPL(irq_inject_interrupt);
 202 #endif