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.

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

Configuration

There is one instance of this register that is used in both Secure and Non-secure states.

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

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 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.

Accessing the PMXEVCNTR

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

MRC <syntax>

This register can be written using MCR with the following syntax:

MCR <syntax>

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

<syntax> opc1opc2CRncoprocCRm
p15, 0, <Rt>, c9, c13, 2000010100111111101

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.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:

Note

In an implementation that includes EL2, in Non-secure state at EL0 and EL1:

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 G1.11.2 (Exception priority order) in the ARM® Architecture Reference Manual, ARMv8, for ARMv8-A architecture profile for exceptions taken to AArch32 state, and section D1.13.2 (Synchronous exception prioritization) for exceptions taken to AArch64 state. 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 && HCR_EL2.E2H==0 :

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

When EL2 is implemented and is using AArch64 and SCR_EL3.NS==1 && HCR_EL2.E2H==1 && HCR_EL2.TGE==0 :

When EL2 is implemented and is using AArch32 and SCR_EL3.NS==1 :

When EL3 is implemented and is using AArch64 :




28/09/2017 08:24

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