DBGOSLSR, Debug OS Lock Status Register

The DBGOSLSR characteristics are:

Purpose

Provides status information for the OS Lock.

Configuration

AArch32 System register DBGOSLSR bits [31:0] are architecturally mapped to AArch64 System register OSLSR_EL1[31:0].

This register is present only when AArch32 is supported at any Exception level. Otherwise, direct accesses to DBGOSLSR are UNDEFINED.

The OS Lock status is also visible in the external debug interface through EDPRSR.

Attributes

DBGOSLSR is a 32-bit register.

Field descriptions

The DBGOSLSR bit assignments are:

313029282726252423222120191817161514131211109876543210
RES0OSLM[1]nTTOSLKOSLM[0]

Bits [31:4]

Reserved, RES0.

OSLM, bits [3, 0]

OS lock model implemented. Identifies the form of OS save and restore mechanism implemented.

OSLMMeaning
0b00

OS Lock not implemented.

0b10

OS Lock implemented.

All other values are reserved. In an Armv8 implementation the value 0b00 is not permitted.

The OSLM field is split as follows:

nTT, bit [2]

Not 32-bit access. This bit is always RAZ. It indicates that a 32-bit access is needed to write the key to the OS Lock Access Register.

OSLK, bit [1]

OS Lock Status. The possible values are:

OSLKMeaning
0b0

OS Lock unlocked.

0b1

OS Lock locked.

The OS Lock is locked and unlocked by writing to the OS Lock Access Register.

On a Cold reset, this field resets to 1.

Accessing the DBGOSLSR

Accesses to this register use the following encodings:

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

coprocopc1CRnCRmopc2
0b11100b0000b00010b00010b100

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) && MDCR_EL3.TDOSA == '1' then UNDEFINED; elsif EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.<TDE,TDOSA> != '00' then AArch64.AArch32SystemAccessTrap(EL2, 0x05); elsif EL2Enabled() && ELUsingAArch32(EL2) && HDCR.<TDE,TDOSA> != '00' then AArch32.TakeHypTrapException(0x05); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDOSA == '1' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.AArch32SystemAccessTrap(EL3, 0x05); else return DBGOSLSR; elsif PSTATE.EL == EL2 then if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && MDCR_EL3.TDOSA == '1' then UNDEFINED; elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDOSA == '1' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.AArch32SystemAccessTrap(EL3, 0x05); else return DBGOSLSR; elsif PSTATE.EL == EL3 then return DBGOSLSR;


30/03/2021 20:51; e3551d56dc294a4d55296a6c10544191ada08a8e

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