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 /* Bitmap to handle software resend of interrupts: */
  25 static DECLARE_BITMAP(irqs_resend, IRQ_BITMAP_BITS);
  26
  27 /*
  28  * Run software resends of IRQ's
  29  */
  30 static void resend_irqs(unsigned long arg)
  31 {
  32         struct irq_desc *desc;
  33         int irq;
  34
  35         while (!bitmap_empty(irqs_resend, nr_irqs)) {
  36                 irq = find_first_bit(irqs_resend, nr_irqs);
  37                 clear_bit(irq, irqs_resend);
  38                 desc = irq_to_desc(irq);
  39                 if (!desc)
  40                         continue;
  41                 local_irq_disable();
  42                 desc->handle_irq(desc);
  43                 local_irq_enable();
  44         }
  45 }
  46
  47 /* Tasklet to handle resend: */
  48 static DECLARE_TASKLET_OLD(resend_tasklet, resend_irqs);
  49
  50 static int irq_sw_resend(struct irq_desc *desc)
  51 {
  52         unsigned int irq = irq_desc_get_irq(desc);
  53
  54         /*
  55          * Validate whether this interrupt can be safely injected from
  56          * non interrupt context
  57          */
  58         if (handle_enforce_irqctx(&desc->irq_data))
  59                 return -EINVAL;
  60
  61         /*
  62          * If the interrupt is running in the thread context of the parent
  63          * irq we need to be careful, because we cannot trigger it
  64          * directly.
  65          */
  66         if (irq_settings_is_nested_thread(desc)) {
  67                 /*
  68                  * If the parent_irq is valid, we retrigger the parent,
  69                  * otherwise we do nothing.
  70                  */
  71                 if (!desc->parent_irq)
  72                         return -EINVAL;
  73                 irq = desc->parent_irq;
  74         }
  75
  76         /* Set it pending and activate the softirq: */
  77         set_bit(irq, irqs_resend);
  78         tasklet_schedule(&resend_tasklet);
  79         return 0;
  80 }
  81
  82 #else
  83 static int irq_sw_resend(struct irq_desc *desc)
  84 {
  85         return -EINVAL;
  86 }
  87 #endif
  88
  89 static int try_retrigger(struct irq_desc *desc)
  90 {
  91         if (desc->irq_data.chip->irq_retrigger)
  92                 return desc->irq_data.chip->irq_retrigger(&desc->irq_data);
  93
  94 #ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
  95         return irq_chip_retrigger_hierarchy(&desc->irq_data);
  96 #else
  97         return 0;
  98 #endif
  99 }
 100
 101 /*
 102  * IRQ resend
 103  *
 104  * Is called with interrupts disabled and desc->lock held.
 105  */
 106 int check_irq_resend(struct irq_desc *desc, bool inject)
 107 {
 108         int err = 0;
 109
 110         /*
 111          * We do not resend level type interrupts. Level type interrupts
 112          * are resent by hardware when they are still active. Clear the
 113          * pending bit so suspend/resume does not get confused.
 114          */
 115         if (irq_settings_is_level(desc)) {
 116                 desc->istate &= ~IRQS_PENDING;
 117                 return -EINVAL;
 118         }
 119
 120         if (desc->istate & IRQS_REPLAY)
 121                 return -EBUSY;
 122
 123         if (!(desc->istate & IRQS_PENDING) && !inject)
 124                 return 0;
 125
 126         desc->istate &= ~IRQS_PENDING;
 127
 128         if (!try_retrigger(desc))
 129                 err = irq_sw_resend(desc);
 130
 131         /* If the retrigger was successfull, mark it with the REPLAY bit */
 132         if (!err)
 133                 desc->istate |= IRQS_REPLAY;
 134         return err;
 135 }
 136
 137 #ifdef CONFIG_GENERIC_IRQ_INJECTION
 138 /**
 139  * irq_inject_interrupt - Inject an interrupt for testing/error injection
 140  * @irq:        The interrupt number
 141  *
 142  * This function must only be used for debug and testing purposes!
 143  *
 144  * Especially on x86 this can cause a premature completion of an interrupt
 145  * affinity change causing the interrupt line to become stale. Very
 146  * unlikely, but possible.
 147  *
 148  * The injection can fail for various reasons:
 149  * - Interrupt is not activated
 150  * - Interrupt is NMI type or currently replaying
 151  * - Interrupt is level type
 152  * - Interrupt does not support hardware retrigger and software resend is
 153  *   either not enabled or not possible for the interrupt.
 154  */
 155 int irq_inject_interrupt(unsigned int irq)
 156 {
 157         struct irq_desc *desc;
 158         unsigned long flags;
 159         int err;
 160
 161         /* Try the state injection hardware interface first */
 162         if (!irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING, true))
 163                 return 0;
 164
 165         /* That failed, try via the resend mechanism */
 166         desc = irq_get_desc_buslock(irq, &flags, 0);
 167         if (!desc)
 168                 return -EINVAL;
 169
 170         /*
 171          * Only try to inject when the interrupt is:
 172          *  - not NMI type
 173          *  - activated
 174          */
 175         if ((desc->istate & IRQS_NMI) || !irqd_is_activated(&desc->irq_data))
 176                 err = -EINVAL;
 177         else
 178                 err = check_irq_resend(desc, true);
 179
 180         irq_put_desc_busunlock(desc, flags);
 181         return err;
 182 }
 183 EXPORT_SYMBOL_GPL(irq_inject_interrupt);
 184 #endif