interrupts.cc

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/*
 * Copyright (c) 2009, 2012-2013, 2016, 2019 ARM Limited
 * All rights reserved.
 *
 * The license below extends only to copyright in the software and shall
 * not be construed as granting a license to any other intellectual
 * property including but not limited to intellectual property relating
 * to a hardware implementation of the functionality of the software
 * licensed hereunder.  You may use the software subject to the license
 * terms below provided that you ensure that this notice is replicated
 * unmodified and in its entirety in all distributions of the software,
 * modified or unmodified, in source code or in binary form.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
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 * neither the name of the copyright holders nor the names of its
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 * this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
#include "arch/arm/interrupts.hh"
 
#include "arch/arm/system.hh"
 
bool
ArmISA::Interrupts::takeInt(InterruptTypes int_type) const
{
    // Table G1-17~19 of ARM V8 ARM
    InterruptMask mask;
    bool highest_el_is_64 = ArmSystem::highestELIs64(tc);
 
    CPSR cpsr = tc->readMiscReg(MISCREG_CPSR);
    SCR scr;
    HCR hcr;
    hcr = tc->readMiscReg(MISCREG_HCR);
    ExceptionLevel el = currEL(tc);
    bool cpsr_mask_bit, scr_routing_bit, scr_fwaw_bit, hcr_mask_override_bit;
 
    if (!highest_el_is_64)
        scr = tc->readMiscReg(MISCREG_SCR);
    else
        scr = tc->readMiscReg(MISCREG_SCR_EL3);
 
    bool is_secure = isSecure(tc);
 
    switch(int_type) {
      case INT_FIQ:
        cpsr_mask_bit = cpsr.f;
        scr_routing_bit = scr.fiq;
        scr_fwaw_bit = scr.fw;
        hcr_mask_override_bit = hcr.fmo;
        break;
      case INT_IRQ:
        cpsr_mask_bit = cpsr.i;
        scr_routing_bit = scr.irq;
        scr_fwaw_bit = 1;
        hcr_mask_override_bit = hcr.imo;
        break;
      case INT_ABT:
        cpsr_mask_bit = cpsr.a;
        scr_routing_bit = scr.ea;
        scr_fwaw_bit = scr.aw;
        hcr_mask_override_bit = hcr.amo;
        break;
      default:
        panic("Unhandled interrupt type!");
    }
 
    if (hcr.tge)
        hcr_mask_override_bit = 1;
 
    if (!highest_el_is_64) {
        // AArch32
        if (!scr_routing_bit) {
            // SCR IRQ == 0
            if (!hcr_mask_override_bit)
                mask = INT_MASK_M;
            else {
                if (!is_secure && (el == EL0 || el == EL1))
                    mask = INT_MASK_T;
                else
                    mask = INT_MASK_M;
            }
        } else {
            // SCR IRQ == 1
            if ((!is_secure) &&
                (hcr_mask_override_bit ||
                    (!scr_fwaw_bit && !hcr_mask_override_bit)))
                mask = INT_MASK_T;
            else
                mask = INT_MASK_M;
        }
    } else {
        // AArch64
        if (!scr_routing_bit) {
            // SCR IRQ == 0
            if (!scr.rw) {
                // SCR RW == 0
                if (!hcr_mask_override_bit) {
                    if (el == EL3)
                        mask = INT_MASK_P;
                    else
                        mask = INT_MASK_M;
                } else {
                    if (el == EL3)
                        mask = INT_MASK_T;
                    else if (is_secure || el == EL2)
                        mask = INT_MASK_M;
                    else
                        mask = INT_MASK_T;
                }
            } else {
                // SCR RW == 1
                if (!hcr_mask_override_bit) {
                    if (el == EL3 || el == EL2)
                        mask = INT_MASK_P;
                    else
                        mask = INT_MASK_M;
                } else {
                    if (el == EL3)
                        mask = INT_MASK_P;
                    else if (is_secure || el == EL2)
                        mask = INT_MASK_M;
                    else
                        mask = INT_MASK_T;
                }
            }
        } else {
            // SCR IRQ == 1
            if (el == EL3)
                mask = INT_MASK_M;
            else
                mask = INT_MASK_T;
        }
    }
 
    return ((mask == INT_MASK_T) ||
            ((mask == INT_MASK_M) && !cpsr_mask_bit)) &&
            (mask != INT_MASK_P);
}