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OSLAR_EL1, OS Lock Access Register

The OSLAR_EL1 characteristics are:

Purpose

Used to lock or unlock the OS Lock.

Configuration

AArch64 System register OSLAR_EL1 bits [31:0] are architecturally mapped to AArch32 System register DBGOSLAR[31:0] .

AArch64 System register OSLAR_EL1 bits [31:0] are architecturally mapped to External register OSLAR_EL1[31:0] .

Attributes

OSLAR_EL1 is a 64-bit register.

Field descriptions

The OSLAR_EL1 bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
RES0
RES0OSLK
313029282726252423222120191817161514131211109876543210

Bits [63:1]

Reserved, RES0.

OSLK, bit [0]

On writes to OSLAR_EL1, bit[0] is copied to the OS Lock.

Use OSLSR_EL1.OSLK to check the current status of the lock.

Accessing the OSLAR_EL1

Accesses to this register use the following encodings:

MSR OSLAR_EL1, <Xt>

op0op1CRnCRmop2
0b100b0000b00010b00000b100
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'" && MDCR_EL3.TDOSA == '1' then
        UNDEFINED;
    elsif EL2Enabled() && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HDFGWTR_EL2.OSLAR_EL1 == '1' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif EL2Enabled() && MDCR_EL2.<TDE,TDOSA> != '00' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif HaveEL(EL3) && MDCR_EL3.TDOSA == '1' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch64.SystemAccessTrap(EL3, 0x18);
    else
        OSLAR_EL1 = X[t];
elsif PSTATE.EL == EL2 then
    if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && MDCR_EL3.TDOSA == '1' then
        UNDEFINED;
    elsif HaveEL(EL3) && MDCR_EL3.TDOSA == '1' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch64.SystemAccessTrap(EL3, 0x18);
    else
        OSLAR_EL1 = X[t];
elsif PSTATE.EL == EL3 then
    OSLAR_EL1 = X[t];