AMEVCNTR0<n>_EL0, Activity Monitors Event Counter Registers 0, n = 0 - 15

The AMEVCNTR0<n>_EL0 characteristics are:

Purpose

Provides access to the architected activity monitor event counters.

Configuration

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

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

This register is present only when FEAT_AMUv1 is implemented. Otherwise, direct accesses to AMEVCNTR0<n>_EL0 are UNDEFINED.

Attributes

AMEVCNTR0<n>_EL0 is a 64-bit register.

Field descriptions

The AMEVCNTR0<n>_EL0 bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
313029282726252423222120191817161514131211109876543210
ACNT
ACNT

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 FEAT_AMUv1p1 is implemented, HCR_EL2.AMVOFFEN is 1, SCR_EL3.AMVOFFEN is 1, HCR_EL2.{E2H, TGE} is not {1,1}, and EL2 is implemented in the current Security state, access to these registers at EL0 or EL1 return (PCount<63:0> - AMEVCNTVOFF0<n>_EL2<63:0>).

PCount is the physical count returned when AMEVCNTR0<n>_EL0 is read from EL2 or EL3.

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

On an AMU reset, this field resets to 0.

Accessing the AMEVCNTR0<n>_EL0

If <n> is greater than or equal to the number of architected activity monitor event counters, reads and writes of AMEVCNTR0<n>_EL0 are UNDEFINED.

Note

AMCGCR_EL0.CG0NC identifies the number of architected activity monitor event counters.

Accesses to this register use the following encodings:

MRS <Xt>, AMEVCNTR0<n>_EL0

op0op1CRnCRmop2
0b110b0110b11010b010:n[3]n[2:0]

if PSTATE.EL == EL0 then if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && CPTR_EL3.TAM == '1' then UNDEFINED; elsif AMUSERENR_EL0.EN == '0' then if EL2Enabled() && HCR_EL2.TGE == '1' then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL1, 0x18); elsif EL2Enabled() && CPTR_EL2.TAM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && HCR_EL2.<E2H,TGE> != '11' && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HAFGRTR_EL2.AMEVCNTR0<n>_EL0 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && CPTR_EL3.TAM == '1' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else return AMEVCNTR0_EL0[UInt(CRm<0>:op2<2:0>)]; elsif PSTATE.EL == EL1 then if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && CPTR_EL3.TAM == '1' then UNDEFINED; elsif EL2Enabled() && CPTR_EL2.TAM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HAFGRTR_EL2.AMEVCNTR0<n>_EL0 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && CPTR_EL3.TAM == '1' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else return AMEVCNTR0_EL0[UInt(CRm<0>:op2<2:0>)]; elsif PSTATE.EL == EL2 then if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && CPTR_EL3.TAM == '1' then UNDEFINED; elsif HaveEL(EL3) && CPTR_EL3.TAM == '1' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else return AMEVCNTR0_EL0[UInt(CRm<0>:op2<2:0>)]; elsif PSTATE.EL == EL3 then return AMEVCNTR0_EL0[UInt(CRm<0>:op2<2:0>)];

MSR AMEVCNTR0<n>_EL0, <Xt>

op0op1CRnCRmop2
0b110b0110b11010b010:n[3]n[2:0]

if IsHighestEL(PSTATE.EL) then AMEVCNTR0_EL0[UInt(CRm<0>:op2<2:0>)] = X[t]; else UNDEFINED;


30/03/2021 20:51; e3551d56dc294a4d55296a6c10544191ada08a8e

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