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OSECCR_EL1, OS Lock Exception Catch Control Register

The OSECCR_EL1 characteristics are:

Purpose

Provides a mechanism for an operating system to access the contents of EDECCR that are otherwise invisible to software, so it can save/restore the contents of EDECCR over powerdown on behalf of the external debugger.

Configuration

AArch64 System register OSECCR_EL1 bits [31:0] are architecturally mapped to AArch32 System register DBGOSECCR[31:0] .

AArch64 System register OSECCR_EL1 bits [31:0] are architecturally mapped to External register EDECCR[31:0] .

If OSLSR_EL1.OSLK == 0, then OSECCR_EL1 returns an UNKNOWN value on reads and ignores writes.

Attributes

OSECCR_EL1 is a 64-bit register.

Field descriptions

The OSECCR_EL1 bit assignments are:

When DBGOSLSR.OSLK == 1:
6362616059585756555453525150494847464544434241403938373635343332
RES0
EDECCR
313029282726252423222120191817161514131211109876543210

Bits [63:32]

Reserved, RES0.

EDECCR, bits [31:0]

Used for save/restore to EDECCR over powerdown.

Reads or writes to this field are indirect accesses to EDECCR.

Accessing the OSECCR_EL1

Accesses to this register use the following encodings:

MRS <Xt>, OSECCR_EL1

op0op1CRnCRmop2
0b100b0000b00000b01100b010
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.<TDE,TDA> != '00' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDA == '1' then
        AArch64.SystemAccessTrap(EL3, 0x18);
    else
        return OSECCR_EL1;
elsif PSTATE.EL == EL2 then
    if HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDA == '1' then
        AArch64.SystemAccessTrap(EL3, 0x18);
    else
        return OSECCR_EL1;
elsif PSTATE.EL == EL3 then
    return OSECCR_EL1;
              

MSR OSECCR_EL1, <Xt>

op0op1CRnCRmop2
0b100b0000b00000b01100b010
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.<TDE,TDA> != '00' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDA == '1' then
        AArch64.SystemAccessTrap(EL3, 0x18);
    else
        OSECCR_EL1 = X[t];
elsif PSTATE.EL == EL2 then
    if HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDA == '1' then
        AArch64.SystemAccessTrap(EL3, 0x18);
    else
        OSECCR_EL1 = X[t];
elsif PSTATE.EL == EL3 then
    OSECCR_EL1 = X[t];
              


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