Holds the value of the processor Cycle Counter, CCNT, that counts processor clock cycles. See 'Time as measured by the Performance Monitors cycle counter' for more information.
PMCCFILTR_EL0 determines the modes and states in which the PMCCNTR_EL0 can increment.
AArch64 System register PMCCNTR_EL0 bits [63:0] are architecturally mapped to AArch32 System register PMCCNTR[63:0].
AArch64 System register PMCCNTR_EL0 bits [63:0] are architecturally mapped to External register PMU.PMCCNTR_EL0[63:0].
This register is present only when FEAT_PMUv3 is implemented. Otherwise, direct accesses to PMCCNTR_EL0 are UNDEFINED.
All counters are subject to any changes in clock frequency, including clock stopping caused by the WFI and WFE instructions. This means that it is CONSTRAINED UNPREDICTABLE whether or not PMCCNTR_EL0 continues to increment when clocks are stopped by WFI and WFE instructions.
PMCCNTR_EL0 is a 64-bit register.
| 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 |
| 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 |
| CCNT | |||||||||||||||||||||||||||||||
| CCNT | |||||||||||||||||||||||||||||||
Cycle count. Depending on the values of PMCR_EL0.{LC,D}, this field increments in one of the following ways:
Writing 1 to PMCR_EL0.C sets this field to 0.
The reset behavior of this field is:
Permitted reads and writes of PMCCNTR_EL0 are RAZ/WI if all of the following are true:
Permitted writes of PMCCNTR_EL0 are ignored if all of the following are true:
Accesses to this register use the following encodings in the System register encoding space:
MRS <Xt>, PMCCNTR_EL0
| op0 | op1 | CRn | CRm | op2 |
|---|---|---|---|---|
| 0b11 | 0b011 | 0b1001 | 0b1101 | 0b000 |
if PSTATE.EL == EL0 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.TPM == '1' then UNDEFINED; elsif (IsFeatureImplemented(FEAT_PMUv3p9) && PMUSERENR_EL0.<UEN,CR,EN> == '000') || (!IsFeatureImplemented(FEAT_PMUv3p9) && PMUSERENR_EL0.<CR,EN> == '00') then if EL2Enabled() && HCR_EL2.TGE == '1' then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL1, 0x18); elsif EL2Enabled() && !ELIsInHost(EL0) && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HDFGRTR_EL2.PMCCNTR_EL0 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && MDCR_EL2.TPM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && MDCR_EL3.TPM == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else X[t, 64] = PMCCNTR_EL0; elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.TPM == '1' then UNDEFINED; elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HDFGRTR_EL2.PMCCNTR_EL0 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && MDCR_EL2.TPM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && MDCR_EL3.TPM == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else X[t, 64] = PMCCNTR_EL0; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.TPM == '1' then UNDEFINED; elsif HaveEL(EL3) && MDCR_EL3.TPM == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else X[t, 64] = PMCCNTR_EL0; elsif PSTATE.EL == EL3 then X[t, 64] = PMCCNTR_EL0;
MSR PMCCNTR_EL0, <Xt>
| op0 | op1 | CRn | CRm | op2 |
|---|---|---|---|---|
| 0b11 | 0b011 | 0b1001 | 0b1101 | 0b000 |
if PSTATE.EL == EL0 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.TPM == '1' then UNDEFINED; elsif PMUSERENR_EL0.EN == '0' && (!IsFeatureImplemented(FEAT_PMUv3p9) || PMUSERENR_EL0.UEN == '0') then if EL2Enabled() && HCR_EL2.TGE == '1' then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL1, 0x18); elsif EL2Enabled() && !ELIsInHost(EL0) && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HDFGWTR_EL2.PMCCNTR_EL0 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && MDCR_EL2.TPM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && MDCR_EL3.TPM == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else PMCCNTR_EL0 = X[t, 64]; elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.TPM == '1' then UNDEFINED; elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HDFGWTR_EL2.PMCCNTR_EL0 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && MDCR_EL2.TPM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && MDCR_EL3.TPM == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else PMCCNTR_EL0 = X[t, 64]; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.TPM == '1' then UNDEFINED; elsif HaveEL(EL3) && MDCR_EL3.TPM == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else PMCCNTR_EL0 = X[t, 64]; elsif PSTATE.EL == EL3 then PMCCNTR_EL0 = X[t, 64];