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PMEVCNTR<n>, Performance Monitors Event Count Registers, n = 0 - 30

The PMEVCNTR<n> characteristics are:

Purpose

Holds event counter n, which counts events, where n is 0 to 30.

Configuration

AArch32 System register PMEVCNTR<n> bits [31:0] are architecturally mapped to AArch64 System register PMEVCNTR<n>_EL0[31:0] .

AArch32 System register PMEVCNTR<n> bits [31:0] are architecturally mapped to External register PMEVCNTR<n>_EL0[31:0] .

This register is in the Warm reset domain. On a Warm or Cold reset RW fields in this register reset to architecturally UNKNOWN values.

Attributes

PMEVCNTR<n> is a 32-bit register.

Field descriptions

The PMEVCNTR<n> bit assignments are:

313029282726252423222120191817161514131211109876543210
Event counter n

Bits [31:0]

Event counter n. Value of event counter n, where n is the number of this register and is a number from 0 to 30.

If ARMv8.5-PMU 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 PMEVCNTR<n> return bits [31:0] of the counter.

  • Writes to PMEVCNTR<n> update bits [31:0] and leave bits [63:32] unchanged.

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

If ARMv8.5-PMU is not implemented, the event counter is 32 bits.

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

Accessing the PMEVCNTR<n>

PMEVCNTR<n> can also be accessed by using PMXEVCNTR with PMSELR.SEL set to the value of <n>.

If <n> is greater than or equal to the number of accessible counters, reads and writes of PMEVCNTR<n> 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
  • If EL2 is implemented and enabled in the current Security state, and <n> is less than the number of implemented 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 PMUSERER_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 counters.
  • If EL2 is using AArch64, MDCR_EL2.HPMN identifies the number of accessible counters.

Otherwise, the number of accessible 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>}

opc1opc2CRncoprocCRm
0b0000b[n:2:0]0b11100b11110b10[n:4:3]
if PSTATE.EL == EL0 then
    if !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) && 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
        AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    else
        return PMEVCNTR[UInt(CRm<1:0>:opc2<2:0>)];
elsif PSTATE.EL == EL1 then
    if 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
        AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    else
        return PMEVCNTR[UInt(CRm<1:0>:opc2<2:0>)];
elsif PSTATE.EL == EL2 then
    if HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then
        AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    else
        return PMEVCNTR[UInt(CRm<1:0>:opc2<2:0>)];
elsif PSTATE.EL == EL3 then
    return PMEVCNTR[UInt(CRm<1:0>:opc2<2:0>)];
              

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

opc1opc2CRncoprocCRm
0b0000b[n:2:0]0b11100b11110b10[n:4:3]
if PSTATE.EL == EL0 then
    if !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) && 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
        AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    else
        PMEVCNTR[UInt(CRm<1:0>:opc2<2:0>)] = R[t];
elsif PSTATE.EL == EL1 then
    if 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
        AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    else
        PMEVCNTR[UInt(CRm<1:0>:opc2<2:0>)] = R[t];
elsif PSTATE.EL == EL2 then
    if HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then
        AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    else
        PMEVCNTR[UInt(CRm<1:0>:opc2<2:0>)] = R[t];
elsif PSTATE.EL == EL3 then
    PMEVCNTR[UInt(CRm<1:0>:opc2<2:0>)] = R[t];
              


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