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CNTPCT_EL0, Counter-timer Physical Count register

The CNTPCT_EL0 characteristics are:

Purpose

Holds the 64-bit physical count value.

Configuration

AArch64 System register CNTPCT_EL0 bits [63:0] are architecturally mapped to AArch32 System register CNTPCT[63:0] .

All reads to the CNTPCT_EL0 occur in program order relative to reads to CNTPCTSS_EL0 or CNTPCT_EL0.

Attributes

CNTPCT_EL0 is a 64-bit register.

Field descriptions

The CNTPCT_EL0 bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
Physical count value
Physical count value
313029282726252423222120191817161514131211109876543210

Bits [63:0]

Physical count value.

Reads of CNTPCT_EL0 from EL0 or EL1 return (PCount<63:0> - CNTPOFF_EL2<63:0>) if the access is not trapped, and all of the following are true:

Where PCount<63:0> is the physical count returned when CNTPCT_EL0 is read from EL2 or EL3.

Accessing the CNTPCT_EL0

Accesses to this register use the following encodings:

MRS <Xt>, CNTPCT_EL0

op0op1CRnCRmop2
0b110b0110b11100b00000b001
if PSTATE.EL == EL0 then
    if !ELUsingAArch32(EL1) && !(EL2Enabled() && HCR_EL2.<E2H,TGE> == '11') && CNTKCTL_EL1.EL0PCTEN == '0' then
        if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then
            AArch64.SystemAccessTrap(EL2, 0x18);
        else
            AArch64.SystemAccessTrap(EL1, 0x18);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.E2H == '0' && CNTHCTL_EL2.EL1PCEN == '0' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '10' && CNTHCTL_EL2.EL1PCTEN == '0' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && CNTHCTL_EL2.EL0PCTEN == '0' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    else
        return CNTPCT_EL0;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && CNTHCTL_EL2.EL1PCTEN == '0' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    else
        return CNTPCT_EL0;
elsif PSTATE.EL == EL2 then
    return CNTPCT_EL0;
elsif PSTATE.EL == EL3 then
    return CNTPCT_EL0;
              


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