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3b01e04379
The 8259a PIC has a well known problem of generating flaky IRQ7 interrupts. The correct solution is to always check if an IRQ7 interrupt is real or not by probing the PIC's ISR register. This check is only mandatory if the IRQ7 is actually being used by the system. More importantly, the handler should NEVER send and EOI if the interrupt was spurious. This patch addresses this issue by implementing a fake empty handler for this IRQ and, as stated, NOT sending the EOI.
77 lines
2.8 KiB
C
77 lines
2.8 KiB
C
/*
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* Copyright (C) 2015, Intel Corporation. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. Neither the name of the copyright holder nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "gdt.h"
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#include "helpers.h"
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#include "idt.h"
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#include "interrupt.h"
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#include "pic.h"
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#define IRQ7_INT PIC_INT(7)
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static void
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double_fault_handler(struct interrupt_context context)
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{
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halt();
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}
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/*---------------------------------------------------------------------------*/
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static void
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spurious_irq7_handler(void)
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{
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/*
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* NOTE: Originally IRQ7 was used for the parallel port interrupts. Nowadays,
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* though, it is only used if some other IRQ (i.e.: a PCIx interrupt) is
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* mapped to it. In this case we will have to check the PIC ISR register in
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* order to confirm this was a real interrupt.
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*
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* In case of a spurious interrupt, we should NEVER send an EOI here so the PIC
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* doesn't trigger the next queued interrupt.
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*/
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}
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/*---------------------------------------------------------------------------*/
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void
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cpu_init(void)
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{
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gdt_init();
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idt_init();
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/* Set an interrupt handler for Double Fault exception. This way, we avoid
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* the system to triple fault, leaving no trace about what happened.
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*/
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SET_INTERRUPT_HANDLER(8, 1, double_fault_handler);
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pic_init();
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/* Set a 'fake' handler for the Spurious IRQ7 interrupts.
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* Refer to http://wiki.osdev.org/PIC .
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*/
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SET_INTERRUPT_HANDLER(IRQ7_INT, 0, spurious_irq7_handler);
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}
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