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# PMXEVCNTR_EL0, Performance Monitors Selected Event Count Register

The PMXEVCNTR_EL0 characteristics are:

## Purpose

Reads or writes the value of the selected event counter, PMEVCNTR<n>_EL0. PMSELR_EL0.SEL determines which event counter is selected.

## Configuration

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

PMXEVCNTR_EL0 is a 64-bit register.

## Field descriptions

The PMXEVCNTR_EL0 bit assignments are:

### When ARMv8.5-PMU is implemented:

63 | 62 | 61 | 60 | 59 | 58 | 57 | 56 | 55 | 54 | 53 | 52 | 51 | 50 | 49 | 48 | 47 | 46 | 45 | 44 | 43 | 42 | 41 | 40 | 39 | 38 | 37 | 36 | 35 | 34 | 33 | 32
PMEVCNTR<n>
PMEVCNTR<n>
31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0

#### PMEVCNTR<n>, bits [63:0]

Value of the selected event counter, PMEVCNTR<n>_EL0, where n is the value stored in PMSELR_EL0.SEL.

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

### Otherwise:

63 | 62 | 61 | 60 | 59 | 58 | 57 | 56 | 55 | 54 | 53 | 52 | 51 | 50 | 49 | 48 | 47 | 46 | 45 | 44 | 43 | 42 | 41 | 40 | 39 | 38 | 37 | 36 | 35 | 34 | 33 | 32
RES0
PMEVCNTR<n>
31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0

#### Bits [63:32]

Reserved, RES0.

#### PMEVCNTR<n>, bits [31:0]

Value of the selected event counter, PMEVCNTR<n>_EL0, where n is the value stored in PMSELR_EL0.SEL.

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

## Accessing the PMXEVCNTR_EL0

If PMSELR_EL0.SEL is greater than or equal to the number of accessible counters then reads and writes of PMXEVCNTR_EL0 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_EL0.SEL has an UNKNOWN value less than the number of counters accessible at the current Exception level and Security state.
- If EL2 is implemented and enabled in the current Security state, and PMSELR_EL0.SEL 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_EL0.{ER,EN}.

If EL2 is implemented and enabled in the current Security state, in EL1 and EL0, MDCR_EL2.HPMN identifies the number of accessible counters. Otherwise, the number of accessible counters is the number of implemented counters. See MDCR_EL2.HPMN for more details.

Accesses to this register use the following encodings:

#### MRS <Xt>, PMXEVCNTR_EL0

op0 | op1 | CRn | CRm | op2
--- | --- | --- | --- | ---
0b11 | 0b011 | 0b1001 | 0b1101 | 0b010

if PSTATE.EL == EL0 then if !ELUsingAArch32(EL1) && PMUSERENR_EL0.<ER,EN> == '00' then if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL1, 0x18); elsif EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.TPM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then AArch64.SystemAccessTrap(EL3, 0x18); else return PMXEVCNTR_EL0; elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.TPM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then AArch64.SystemAccessTrap(EL3, 0x18); else return PMXEVCNTR_EL0; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then AArch64.SystemAccessTrap(EL3, 0x18); else return PMXEVCNTR_EL0; elsif PSTATE.EL == EL3 then return PMXEVCNTR_EL0;

#### MSR PMXEVCNTR_EL0, <Xt>

op0 | op1 | CRn | CRm | op2
--- | --- | --- | --- | ---
0b11 | 0b011 | 0b1001 | 0b1101 | 0b010

if PSTATE.EL == EL0 then if !ELUsingAArch32(EL1) && PMUSERENR_EL0.EN == '0' then if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL1, 0x18); elsif EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.TPM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then AArch64.SystemAccessTrap(EL3, 0x18); else PMXEVCNTR_EL0 = X[t]; elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.TPM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then AArch64.SystemAccessTrap(EL3, 0x18); else PMXEVCNTR_EL0 = X[t]; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TPM == '1' then AArch64.SystemAccessTrap(EL3, 0x18); else PMXEVCNTR_EL0 = X[t]; elsif PSTATE.EL == EL3 then PMXEVCNTR_EL0 = X[t];

AArch32 Registers | AArch64 Registers | AArch32 Instructions | AArch64 Instructions | Index by Encoding | External Registers | External Registers by Offset | Registers by Functional Group | Proprietary Notice

27/03/2019 21:59; e5e4db499bf9867a4b93324c4dbac985d3da9376

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