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AArch64 Debug.Pmu Pseudocode

Library pseudocode for aarch64/debug/pmu/AArch64.CheckForPMUOverflow

// AArch64.CheckForPMUOverflow()
// =============================
// Signal Performance Monitors overflow IRQ and CTI overflow events

boolean AArch64.CheckForPMUOverflow()

    pmuirq = PMCR_EL0.E == '1' && PMINTENSET_EL1<31> == '1' && PMOVSSET_EL0<31> == '1';
    for n = 0 to UInt(PMCR_EL0.N) - 1
        if HaveEL(EL2) then
            E = (if n < UInt(MDCR_EL2.HPMN) then PMCR_EL0.E else MDCR_EL2.HPME);
        else
            E = PMCR_EL0.E;
        if E == '1' && PMINTENSET_EL1<n> == '1' && PMOVSSET_EL0<n> == '1' then pmuirq = TRUE;

    SetInterruptRequestLevel(InterruptID_PMUIRQ, if pmuirq then HIGH else LOW);

    CTI_SetEventLevel(CrossTriggerIn_PMUOverflow, if pmuirq then HIGH else LOW);

    // The request remains set until the condition is cleared. (For example, an interrupt handler
    // or cross-triggered event handler clears the overflow status flag by writing to PMOVSCLR_EL0.)

    return pmuirq;

Library pseudocode for aarch64/debug/pmu/AArch64.CountEvents

// AArch64.CountEvents()
// =====================
// Return TRUE if counter "n" should count its event. For the cycle counter, n == 31.

boolean AArch64.CountEvents(integer n)
    assert n == 31 || n < UInt(PMCR_EL0.N);

    // Event counting is disabled in Debug state
    debug = Halted();

    // In Non-secure state, some counters are reserved for EL2
    if HaveEL(EL2) then
        E = if n < UInt(MDCR_EL2.HPMN) || n == 31 then PMCR_EL0.E else MDCR_EL2.HPME;
    else
        E = PMCR_EL0.E;
    enabled = E == '1' && PMCNTENSET_EL0<n> == '1';

    if !IsSecure() then
        // Event counting in Non-secure state is allowed unless all of:
        // * EL2 and the HPMD Extension are implemented
        // * Executing at EL2
        // * PMNx is not reserved for EL2
        // * MDCR_EL2.HPMD == 1
        if HaveHPMDExt() && PSTATE.EL == EL2 && (n < UInt(MDCR_EL2.HPMN) || n == 31) then
            prohibited = (MDCR_EL2.HPMD == '1');
        else
            prohibited = FALSE;
    else
        // Event counting in Secure state is prohibited unless any one of:
        // * EL3 is not implemented
        // * EL3 is using AArch64 and MDCR_EL3.SPME == 1
        prohibited = HaveEL(EL3) && MDCR_EL3.SPME == '0';

    // The IMPLEMENTATION DEFINED authentication interface might override software controls
    if prohibited && !HaveNoSecurePMUDisableOverride() then
        prohibited = !ExternalSecureNoninvasiveDebugEnabled();

    // For the cycle counter, PMCR_EL0.DP enables counting when otherwise prohibited
    if prohibited && n == 31 then prohibited = (PMCR_EL0.DP == '1');

    // Event counting can be filtered by the {P, U, NSK, NSU, NSH, M} bits
    filter = if n == 31 then PMCCFILTR else PMEVTYPER[n];

    P = filter<31>;
    U = filter<30>;
    NSK = if HaveEL(EL3) then filter<29> else '0';
    NSU = if HaveEL(EL3) then filter<28> else '0';
    NSH = if HaveEL(EL2) then filter<27> else '0';
    M = if HaveEL(EL3) then filter<26> else '0';

    case PSTATE.EL of
        when EL0  filtered = if IsSecure() then U == '1' else U != NSU;
        when EL1  filtered = if IsSecure() then P == '1' else P != NSK;
        when EL2  filtered = (NSH == '0');
        when EL3  filtered = (M != P);

    return !debug && enabled && !prohibited && !filtered;
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