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.

This register is part of the Performance Monitors registers functional group.

Configuration

AArch64 System register PMXEVCNTR_EL0 is architecturally mapped to AArch32 System register PMXEVCNTR.

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 32-bit register.

Field descriptions

The PMXEVCNTR_EL0 bit assignments are:

313029282726252423222120191817161514131211109876543210
PMEVCNTR<n>

PMEVCNTR<n>, bits [31:0]

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

Accessing the PMXEVCNTR_EL0

This register can be read using MRS with the following syntax:

MRS <Xt>, <systemreg>

This register can be written using MSR (register) with the following syntax:

MSR <systemreg>, <Xt>

This syntax uses the following encoding in the System instruction encoding space:

<systemreg> op0op1CRnCRmop2
PMXEVCNTR_EL01101110011101010

Accessibility

The register is accessible as follows:

Control Accessibility
E2HTGENSEL0EL1EL2EL3
xx0RWRW n/a RW
x01RWRWRWRW
x11RW n/a RWRW

This table applies to all instructions that can access this register.

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:

Note

In an implementation that includes EL2, in Non-secure state at EL0 and EL1, MDCR_EL2.HPMN identifies the number of accessible counters. Otherwise, the number of accessible counters is the number of implemented counters.

Traps and enables

For a description of the prioritization of any generated exceptions, see section D1.13.2 (Synchronous exception prioritization) in the ARM® Architecture Reference Manual, ARMv8, for ARMv8-A architecture profile. Subject to the prioritization rules, the following traps and enables are applicable when accessing this register.

In both Security states, and not dependent on other configuration bits:

When EL2 is implemented and is using AArch64 and SCR_EL3.NS==1 :

When EL3 is implemented and is using AArch64 :




28/09/2017 08:24

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