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PMXEVCNTR, Performance Monitors Selected Event Count Register

The PMXEVCNTR characteristics are:

Purpose

Reads or writes the value of the selected event counter, PMEVCNTR<n>. PMSELR.SEL determines which event counter is selected.

Configuration

AArch32 System register PMXEVCNTR bits [31:0] are architecturally mapped to AArch64 System register PMXEVCNTR_EL0[31:0] .

This register is present only when AArch32 is supported at any Exception level and FEAT_PMUv3 is implemented. Otherwise, direct accesses to PMXEVCNTR are UNDEFINED.

Attributes

PMXEVCNTR is a 32-bit register.

Field descriptions

The PMXEVCNTR bit assignments are:

313029282726252423222120191817161514131211109876543210
PMEVCNTR<n>

PMEVCNTR<n>, bits [31:0]

Value of the selected event counter, PMEVCNTR<n>, where n is the value stored in PMSELR.SEL.

If FEAT_PMUv3p5 is implemented, the event counter is 64 bits and only the least-significant part of the event counter is accessible in AArch32 state:

  • Reads from PMXEVCNTR return bits [31:0] of the counter.

  • Writes to PMXEVCNTR update bits [31:0] and leave bits [63:32] unchanged.

  • There is no means to access bits [63:32] directly from AArch32 state.

  • If the implementation does not support AArch64 at any Exception level, bits [63:32] are not required to be implemented.

If FEAT_PMUv3p5 is not implemented, the event counter is 32 bits.

On a Warm reset, this field resets to an architecturally UNKNOWN value.

Accessing the PMXEVCNTR

If FEAT_FGT is implemented and PMSELR.SEL is greater than or equal to the number of accessible counters, then the behavior of permitted reads and writes of PMXEVCNTR is as follows:

  • If PMSELR.SEL selects an unimplemented event counter, the access is UNDEFINED.
  • Otherwise, the access is trapped to EL2.

If FEAT_FGT is not implemented and PMSELR.SEL is greater than or equal to the number of accessible counters, then reads and writes of PMXEVCNTR are CONSTRAINED UNPREDICTABLE, and the following behaviors are permitted:

  • Accesses to the register are UNDEFINED.
  • Accesses to the register behave as RAZ/WI.
  • Accesses to the register execute as a NOP
  • Accesses to the register behave as if PMSELR.SEL has an UNKNOWN value less than the number of event counters accessible at the current Exception level and Security state.
  • If EL2 is implemented and enabled in the current Security state, and PMSELR.SEL is less than the number of implemented event counters, accesses from EL1 or permitted accesses from EL0 are trapped to EL2.
Note

In EL0, an access is permitted if it is enabled by PMUSERENR.{ER,EN} or PMUSERENR_EL0.{ER,EN}.

If EL2 is implemented and enabled in the current Security state, at EL0 and EL1:

  • If EL2 is using AArch32, HDCR.HPMN identifies the number of accessible event counters.
  • If EL2 is using AArch64, MDCR_EL2.HPMN identifies the number of accessible event counters.

Otherwise, the number of accessible event counters is the number of implemented counters. See HDCR.HPMN and MDCR_EL2.HPMN for more details.

Accesses to this register use the following encodings:

MRC{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

coprocopc1CRnCRmopc2
0b11110b0000b10010b11010b010
if PSTATE.EL == EL0 then
    if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then
        UNDEFINED;
    elsif !ELUsingAArch32(EL1) && PMUSERENR_EL0.<ER,EN> == '00' then
        if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then
            AArch64.AArch32SystemAccessTrap(EL2, 0x03);
        else
            AArch64.AArch32SystemAccessTrap(EL1, 0x03);
    elsif ELUsingAArch32(EL1) && PMUSERENR.<ER,EN> == '00' then
        if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then
            AArch64.AArch32SystemAccessTrap(EL2, 0x03);
        elsif EL2Enabled() && ELUsingAArch32(EL2) && HCR.TGE == '1' then
            AArch32.TakeHypTrapException(0x00);
        else
            UNDEFINED;
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> != '11' && HSTR_EL2.T9 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T9 == '1' then
        AArch32.TakeHypTrapException(0x03);
    elsif EL2Enabled() && !ELUsingAArch32(EL1) && HCR_EL2.<E2H,TGE> != '11' && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HDFGRTR_EL2.PMEVCNTRn_EL0 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.TPM == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HDCR.TPM == '1' then
        AArch32.TakeHypTrapException(0x03);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    else
        return PMXEVCNTR;
elsif PSTATE.EL == EL1 then
    if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then
        UNDEFINED;
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T9 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T9 == '1' then
        AArch32.TakeHypTrapException(0x03);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.TPM == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HDCR.TPM == '1' then
        AArch32.TakeHypTrapException(0x03);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    else
        return PMXEVCNTR;
elsif PSTATE.EL == EL2 then
    if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then
        UNDEFINED;
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    else
        return PMXEVCNTR;
elsif PSTATE.EL == EL3 then
    return PMXEVCNTR;

MCR{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

coprocopc1CRnCRmopc2
0b11110b0000b10010b11010b010
if PSTATE.EL == EL0 then
    if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then
        UNDEFINED;
    elsif !ELUsingAArch32(EL1) && PMUSERENR_EL0.EN == '0' then
        if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then
            AArch64.AArch32SystemAccessTrap(EL2, 0x03);
        else
            AArch64.AArch32SystemAccessTrap(EL1, 0x03);
    elsif ELUsingAArch32(EL1) && PMUSERENR.EN == '0' then
        if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then
            AArch64.AArch32SystemAccessTrap(EL2, 0x03);
        elsif EL2Enabled() && ELUsingAArch32(EL2) && HCR.TGE == '1' then
            AArch32.TakeHypTrapException(0x00);
        else
            UNDEFINED;
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> != '11' && HSTR_EL2.T9 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T9 == '1' then
        AArch32.TakeHypTrapException(0x03);
    elsif EL2Enabled() && !ELUsingAArch32(EL1) && HCR_EL2.<E2H,TGE> != '11' && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HDFGWTR_EL2.PMEVCNTRn_EL0 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.TPM == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HDCR.TPM == '1' then
        AArch32.TakeHypTrapException(0x03);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    else
        PMXEVCNTR = R[t];
elsif PSTATE.EL == EL1 then
    if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then
        UNDEFINED;
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T9 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T9 == '1' then
        AArch32.TakeHypTrapException(0x03);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.TPM == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HDCR.TPM == '1' then
        AArch32.TakeHypTrapException(0x03);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    else
        PMXEVCNTR = R[t];
elsif PSTATE.EL == EL2 then
    if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then
        UNDEFINED;
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    else
        PMXEVCNTR = R[t];
elsif PSTATE.EL == EL3 then
    PMXEVCNTR = R[t];


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