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LORC_EL1, LORegion Control (EL1)

The LORC_EL1 characteristics are:

Purpose

Enables and disables LORegions, and selects the current LORegion descriptor.

Configuration

This register is present only when ARMv8.1-LOR is implemented. Otherwise, direct accesses to LORC_EL1 are UNDEFINED.

If no LORegion descriptors are supported by the PE, then this register is RES0.

Attributes

LORC_EL1 is a 64-bit register.

Field descriptions

The LORC_EL1 bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
RES0
RES0DSRES0EN
313029282726252423222120191817161514131211109876543210

Bits [63:10]

Reserved, RES0.

DS, bits [9:2]

Descriptor Select. Selects the current LORegion descriptor accessed by LORSA_EL1, LOREA_EL1, and LORN_EL1.

The number of LORegion descriptors in IMPLEMENTATION DEFINED. The maximum number of LORegion descriptors supported is 256. If the number is less than 256, then bits[63:M+2] are RES0, where M is Log2(Number of LORegion descriptors supported by the implementation).

If this field points to an LORegion descriptor that is not supported by an implementation, then the registers LORN_EL1, LOREA_EL1, and LORSA_EL1 are RES0.

This field resets to an architecturally UNKNOWN value.

Bit [1]

Reserved, RES0.

EN, bit [0]

Enable. Indicates whether LORegions are enabled.

ENMeaning
0b0

Disabled. Memory accesses do not match any LORegions.

0b1

Enabled. Memory accesses may match a LORegion.

This bit is permitted to be cached in a TLB.

This field resets to 0.

Accessing the LORC_EL1

Accesses to this register use the following encodings:

MRS <Xt>, LORC_EL1

op0op1CRnCRmop2
0b110b0000b10100b01000b011
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && SCR_EL3.TLOR == '1' then
        UNDEFINED;
    elsif SCR_EL3.NS == '0' then
        UNDEFINED;
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TLOR == '1' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGRTR_EL2.LORC_EL1 == '1' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.TLOR == '1' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch64.SystemAccessTrap(EL3, 0x18);
    else
        return LORC_EL1;
elsif PSTATE.EL == EL2 then
    if SCR_EL3.NS == '0' then
        UNDEFINED;
    elsif Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && SCR_EL3.TLOR == '1' then
        UNDEFINED;
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.TLOR == '1' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch64.SystemAccessTrap(EL3, 0x18);
    else
        return LORC_EL1;
elsif PSTATE.EL == EL3 then
    if SCR_EL3.NS == '0' then
        UNDEFINED;
    else
        return LORC_EL1;
              

MSR LORC_EL1, <Xt>

op0op1CRnCRmop2
0b110b0000b10100b01000b011
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && SCR_EL3.TLOR == '1' then
        UNDEFINED;
    elsif SCR_EL3.NS == '0' then
        UNDEFINED;
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TLOR == '1' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGWTR_EL2.LORC_EL1 == '1' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.TLOR == '1' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch64.SystemAccessTrap(EL3, 0x18);
    else
        LORC_EL1 = X[t];
elsif PSTATE.EL == EL2 then
    if SCR_EL3.NS == '0' then
        UNDEFINED;
    elsif Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && SCR_EL3.TLOR == '1' then
        UNDEFINED;
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.TLOR == '1' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch64.SystemAccessTrap(EL3, 0x18);
    else
        LORC_EL1 = X[t];
elsif PSTATE.EL == EL3 then
    if SCR_EL3.NS == '0' then
        UNDEFINED;
    else
        LORC_EL1 = X[t];