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

# AMEVCNTR0<n>, Activity Monitors Event Counter Registers 0, n = 0 - 15

The AMEVCNTR0<n> characteristics are:

## Purpose

Provides access to the architected activity monitor event counters.

## Configuration

AArch32 System register AMEVCNTR0<n> bits [63:0] are architecturally mapped to AArch64 System register AMEVCNTR0<n>_EL0[63:0] .

AArch32 System register AMEVCNTR0<n> bits [63:0] are architecturally mapped to External register AMEVCNTR0<n>[63:0] .

This register is present only when AMUv1 is implemented. Otherwise, direct accesses to AMEVCNTR0<n> are UNDEFINED.

Some or all RW fields of this register have defined reset values. These apply only if the PE resets into an Exception level that is using AArch32. Otherwise, RW fields in this register reset to architecturally UNKNOWN values.

## Attributes

AMEVCNTR0<n> is a 64-bit register.

## Field descriptions

The AMEVCNTR0<n> bit assignments are:

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
ACNT
ACNT
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

#### ACNT, bits [63:0]

Architected activity monitor event counter n.

Value of architected activity monitor event counter n, where n is the number of this register and is a number from 0 to 15.

If the counter is enabled, writes to this register have UNPREDICTABLE results.

On a Cold reset, this field resets to 0.

## Accessing the AMEVCNTR0<n>

If <n> is greater than or equal to the number of architected activity monitor event counters, reads and writes of AMEVCNTR0<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.

Note

AMCGCR.CG0NC identifies the number of architected activity monitor event counters.

Accesses to this register use the following encodings:

#### MRRC{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <Rt2>, <CRm>

coproc | CRm | opc1
--- | --- | ---
0b1111 | 0b000[n:3] | 0b0[n:2:0]

if CRm == 0 then if PSTATE.EL == EL0 then if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> != '11' && HSTR_EL2.T0 == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x04); elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T0 == '1' then AArch32.TakeHypTrapException(0x04); elsif !ELUsingAArch32(EL1) && AMUSERENR_EL0.EN == '0' then if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x04); else AArch64.AArch32SystemAccessTrap(EL1, 0x04); elsif EL2Enabled() && !ELUsingAArch32(EL2) && CPTR_EL2.TAM == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x04); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.TAM == '1' then AArch64.AArch32SystemAccessTrap(EL3, 0x04); else return AMEVCNTR0[UInt(CRm<0>:opc1<2:0>)]; elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T0 == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x04); elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T0 == '1' then AArch32.TakeHypTrapException(0x04); elsif EL2Enabled() && !ELUsingAArch32(EL2) && CPTR_EL2.TAM == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x04); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.TAM == '1' then AArch64.AArch32SystemAccessTrap(EL3, 0x04); else return AMEVCNTR0[UInt(CRm<0>:opc1<2:0>)]; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.TAM == '1' then AArch64.AArch32SystemAccessTrap(EL3, 0x04); else return AMEVCNTR0[UInt(CRm<0>:opc1<2:0>)]; elsif PSTATE.EL == EL3 then return AMEVCNTR0[UInt(CRm<0>:opc1<2:0>)]; else UNDEFINED;

#### MCRR{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <Rt2>, <CRm>

coproc | CRm | opc1
--- | --- | ---
0b1111 | 0b000[n:3] | 0b0[n:2:0]

if CRm == 0 then if PSTATE.EL == EL1 && EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T0 == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x04); elsif PSTATE.EL == EL1 && EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T0 == '1' then AArch32.TakeHypTrapException(0x04); elsif IsHighestEL(PSTATE.EL) then AMEVCNTR0[UInt(CRm<0>:opc1<2:0>)] = R[t2]:R[t]; else UNDEFINED; else UNDEFINED;

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

Copyright © 2010-2019 Arm Limited or its affiliates. All rights reserved. This document is Non-Confidential.