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TRFCR, Trace Filter Control Register

The TRFCR characteristics are:

Purpose

Provides EL1 controls for Trace.

Configuration

AArch32 System register TRFCR bits [31:0] are architecturally mapped to AArch64 System register TRFCR_EL1[31:0] .

This register is present only when ARMv8.4-Trace is implemented. Otherwise, direct accesses to TRFCR 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

TRFCR is a 32-bit register.

Field descriptions

The TRFCR bit assignments are:

313029282726252423222120191817161514131211109876543210
RES0TSRES0E1TREE0TRE

Bits [31:7]

Reserved, RES0.

TS, bits [6:5]

Timestamp Control. Controls which timebase is used for trace timestamps.

TSMeaningApplies when
0b01

Virtual timestamp. The traced timestamp is the physical counter value, minus the value of CNTVOFF.

0b10

Guest Physical timestamp. The traced timestamp is the physical counter value, minus the value of CNTPOFF_EL2.

When ARMv8.6-ECV is implemented
0b11

Physical timestamp. The traced timestamp is the physical counter value.

All other values are reserved.

This field is ignored if any of the following are true:

  • SelfHostedTraceEnabled() == FALSE.
  • HTRFCR.TS is not 0b00.

When EL2 is implemented and enabled in the current Security state, the physical counter uses a fixed physical offset of zero if either of the following are true:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

Bits [4:2]

Reserved, RES0.

E1TRE, bit [1]

EL1 Trace Enable.

E1TREMeaning
0b0

Tracing is prohibited in PL1 modes.

0b1

Tracing is allowed in PL1 modes.

This field is ignored if SelfHostedTraceEnabled() == FALSE.

On a Warm reset, this field resets to 0.

E0TRE, bit [0]

EL0 Trace Enable.

E0TREMeaning
0b0

Tracing is prohibited at EL0.

0b1

Tracing is allowed at EL0.

This field is ignored if any of the following are true:

  • SelfHostedTraceEnabled() == FALSE.
  • EL2 is implemented and enabled in the current security state and HCR.TGE == 1.

On a Warm reset, this field resets to 0.

Accessing the TRFCR

Accesses to this register use the following encodings:

MRC{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

coprocopc1CRnCRmopc2
0b11110b0000b00010b00100b001
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T1 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T1 == '1' then
        AArch32.TakeHypTrapException(0x03);
    elsif SCR.NS == '0' then
        UNDEFINED;
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.TTRF == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HDCR.TTRF == '1' then
        AArch32.TakeHypTrapException(0x03);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TTRF == '1' then
        AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    elsif HaveEL(EL3) && ELUsingAArch32(EL3) && PSTATE.M != M32_Monitor && SDCR.TTRF == '1' then
        AArch32.TakeMonitorTrapException();
    else
        return TRFCR;
elsif PSTATE.EL == EL2 then
    if HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TTRF == '1' then
        AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    elsif HaveEL(EL3) && ELUsingAArch32(EL3) && SDCR.TTRF == '1' then
        AArch32.TakeMonitorTrapException();
    else
        return TRFCR;
elsif PSTATE.EL == EL3 then
    if SCR.NS == '0' then
        UNDEFINED;
    else
        return TRFCR;
              

MCR{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

coprocopc1CRnCRmopc2
0b11110b0000b00010b00100b001
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T1 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T1 == '1' then
        AArch32.TakeHypTrapException(0x03);
    elsif SCR.NS == '0' then
        UNDEFINED;
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.TTRF == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HDCR.TTRF == '1' then
        AArch32.TakeHypTrapException(0x03);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TTRF == '1' then
        AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    elsif HaveEL(EL3) && ELUsingAArch32(EL3) && PSTATE.M != M32_Monitor && SDCR.TTRF == '1' then
        AArch32.TakeMonitorTrapException();
    else
        TRFCR = R[t];
elsif PSTATE.EL == EL2 then
    if HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TTRF == '1' then
        AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    elsif HaveEL(EL3) && ELUsingAArch32(EL3) && SDCR.TTRF == '1' then
        AArch32.TakeMonitorTrapException();
    else
        TRFCR = R[t];
elsif PSTATE.EL == EL3 then
    if SCR.NS == '0' then
        UNDEFINED;
    else
        TRFCR = R[t];
              


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