The HDCR characteristics are:
Controls the trapping to Hyp mode of Non-secure accesses, at EL1 or lower, to functions provided by the debug and trace architectures and the Performance Monitors Extension.
AArch32 System register HDCR bits [31:0] are architecturally mapped to AArch64 System register MDCR_EL2[31:0] .
If EL2 is not implemented, this register is RES0 from EL3, and other than for a direct read of the register, the PE behaves as if HDCR.HPMN == PMCR.N.
This register is in the Warm reset domain. Some or all RW fields of this register have defined reset values. On a Warm or Cold reset these apply only if the PE resets into EL2 with EL2 using AArch32, or into EL3 with EL3 using AArch32. Otherwise, on a Warm or Cold reset RW fields in this register reset to architecturally UNKNOWN values.
HDCR is a 32-bit register.
The HDCR bit assignments are:
31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
0 | 0 | 0 | 0 | 0 | HLP | 0 | 0 | HCCD | 0 | 0 | 0 | TTRF | 0 | HPMD | 0 | 0 | 0 | 0 | 0 | TDRA | TDOSA | TDA | TDE | HPME | TPM | TPMCR | HPMN |
Reserved, RES0.
Hypervisor Long event counter enable. Determines when unsigned overflow is recorded by a counter overflow bit.
HLP | Meaning |
---|---|
0b0 |
Event counter overflow on increment that causes unsigned overflow of PMEVCNTR<n>[31:0]. |
0b1 |
Event counter overflow on increment that causes unsigned overflow of PMEVCNTR<n>[63:0]. |
If the highest implemented Exception level is using AArch32, it is IMPLEMENTATION DEFINED whether this bit is read/write or RAZ/WI.
If HDCR.HPMN is less than PMCR.N, this bit affects the operation of event counters in the range [HDCR.HPMN:(PMCR.N-1)]. Otherwise this bit has no effect on the operation of the event counters.
The effect of HDCR.HPMN on the operation of this bit applies regardless of whether EL2 is enabled in the current Security state.
For more information see the description of the HPMN field.
PMEVCNTR<n>[63:32] cannot be accessed directly in AArch32 state.
On a Warm reset, in a system where the PE resets into EL2 or EL3, this field resets to 0.
Reserved, RES0.
Reserved, RES0.
Hypervisor Cycle Counter Disable. Prohibits PMCCNTR from counting at EL2.
HCCD | Meaning |
---|---|
0b0 |
Cycle counting by PMCCNTR is not affected by this bit. |
0b1 |
Cycle counting by PMCCNTR is prohibited at EL2. |
This bit does not affect the CPU_CYCLES event or any other event that counts cycles.
On a Warm reset, in a system where the PE resets into EL2 or EL3, this field resets to 0.
Reserved, RES0.
Reserved, RES0.
Traps use of the Trace Filter Control registers at EL1 to EL2.
TTRF | Meaning |
---|---|
0b0 |
Accesses to TRFCR at EL1 are not affected by this control bit. |
0b1 |
Accesses to TRFCR at EL1 generate a Hyp Trap exception. |
On a Warm reset, in a system where the PE resets into EL2 or EL3, this field resets to 0.
Reserved, RES0.
Reserved, RES0.
Guest Performance Monitors Disable. This control prohibits event counting at EL2.
HPMD | Meaning |
---|---|
0b0 |
Event counting allowed in Hyp mode. |
0b1 |
Event counting prohibited in Hyp mode. In an Armv8.1 implementation, event counting is prohibited unless enabled by the IMPLEMENTATION DEFINED authentication interface ExternalSecureNoninvasiveDebugEnabled(). |
This control applies only to:
The other event counters are unaffected. When PMCR.DP is set to 0, PMCCNTR is unaffected.
On a Warm reset, in a system where the PE resets into EL2 or EL3, this field resets to 0.
Reserved, RES0.
Reserved, RES0.
Trap Debug ROM Address register access. Traps Non-secure EL0 and EL1 System register accesses to the Debug ROM registers to Hyp mode.
TDRA | Meaning |
---|---|
0b0 |
This control does not cause any instructions to be trapped. |
0b1 |
Non-secure EL0 and EL1 System register accesses to the DBGDRAR or DBGDSAR are trapped to Hyp mode, unless it is trapped by DBGDSCRext.UDCCdis. |
If HCR.TGE or HDCR.TDE is 1, behavior is as if this bit is 1 other than for the purpose of a direct read.
On a Warm reset, in a system where the PE resets into EL2 or EL3, this field resets to 0.
Trap debug OS-related register access. Traps Non-secure EL1 System register accesses to the powerdown debug registers to Hyp mode.
TDOSA | Meaning |
---|---|
0b0 |
This control does not cause any instructions to be trapped. |
0b1 |
Non-secure EL1 System register accesses to the powerdown debug registers are trapped to Hyp mode. |
The registers for which accesses are trapped are as follows:
These registers are not accessible at EL0.
If HCR.TGE or HDCR.TDE is 1, behavior is as if this bit is 1 other than for the purpose of a direct read.
On a Warm reset, in a system where the PE resets into EL2 or EL3, this field resets to 0.
Trap debug OS-related register access. Traps Non-secure EL1 System register accesses to the powerdown debug registers to Hyp mode.
TDOSA | Meaning |
---|---|
0b0 |
This control does not cause any instructions to be trapped. |
0b1 |
Non-secure EL1 System register accesses to the powerdown debug registers are trapped to Hyp mode. |
The registers for which accesses are trapped are as follows:
It is IMPLEMENTATION DEFINED whether accesses to DBGOSDLR are trapped.
These registers are not accessible at EL0.
If HCR.TGE or HDCR.TDE is 1, behavior is as if this bit is 1 other than for the purpose of a direct read.
On a Warm reset, in a system where the PE resets into EL2 or EL3, this field resets to 0.
Trap debug access. Traps Non-secure EL0 and EL1 System register accesses to those debug System registers in the (coproc==0b1110) encoding space that are not trapped by either of the following:
TDA | Meaning |
---|---|
0b0 |
This control does not cause any instructions to be trapped. |
0b1 |
Non-secure EL0 or EL1 System register accesses to the debug registers, other than the registers trapped by HDCR.TDRA and HDCR.TDOSA, are trapped to Hyp mode, unless it is trapped by DBGDSCRext.UDCCdis. |
Traps of AArch32 accesses to DBGDTRRXint and DBGDTRTXint are ignored in Debug state.
If HCR.TGE or HDCR.TDE is 1, behavior is as if this bit is 1 other than for the purpose of a direct read.
On a Warm reset, in a system where the PE resets into EL2 or EL3, this field resets to 0.
Trap Debug exceptions. The possible values of this bit are:
TDE | Meaning |
---|---|
0b0 |
This control has no effect on the routing of debug exceptions, and has no effect on Non-secure accesses to debug registers. |
0b1 |
Debug exceptions generated at EL1 or EL0 are routed to EL2 when enabled in the current Security state. The HDCR.{TDRA, TDOSA, TDA} fields are treated as being 1 for all purposes other than returning the result of a direct read of the register. |
When HCR.TGE == 1, the PE behaves as if the value of this field is 1 for all purposes other than returning the value of a direct read of the register.
On a Warm reset, in a system where the PE resets into EL2 or EL3, this field resets to 0.
[HDCR.HPMN:(N-1)] event counters enable.
HPME | Meaning |
---|---|
0b0 |
Event counters in the range [HDCR.HPMN:(PMCR.N-1)] are disabled. |
0b1 |
Event counters in the range [HDCR.HPMN:(PMCR.N-1)] are enabled by PMCNTENSET. |
If HDCR.HPMN is less than PMCR.N, the event counters in the range [HDCR.HPMN:(PMCR.N-1)], are enabled and disabled by this bit. Otherwise this bit has no effect on the operation of the event counters.
The effect of HDCR.HPMN on the operation of this bit applies regardless of whether EL2 is enabled in the current Security state.
For more information see the description of the HPMN field.
On a Warm reset, in a system where the PE resets into EL2 or EL3, this field resets to an architecturally UNKNOWN value.
Reserved, RES0.
Trap Performance Monitors accesses. Traps Non-secure EL0 and EL1 accesses to all Performance Monitors registers to Hyp mode.
TPM | Meaning |
---|---|
0b0 |
This control does not cause any instructions to be trapped. |
0b1 |
Non-secure EL0 and EL1 accesses to all Performance Monitors registers are trapped to Hyp mode. |
EL2 does not provide traps on Performance Monitor register accesses through the optional memory-mapped external debug interface.
On a Warm reset, in a system where the PE resets into EL2 or EL3, this field resets to 0.
Reserved, RES0.
Trap PMCR accesses. Traps Non-secure EL0 and EL1 accesses to the PMCR to Hyp mode.
TPMCR | Meaning |
---|---|
0b0 |
This control does not cause any instructions to be trapped. |
0b1 |
Non-secure EL0 and EL1 accesses to the PMCR are trapped to Hyp mode, unless it is trapped by PMUSERENR.EN. |
EL2 does not provide traps on Performance Monitor register accesses through the optional memory-mapped external debug interface.
On a Warm reset, in a system where the PE resets into EL2 or EL3, this field resets to 0.
Reserved, RES0.
Defines the number of event counters that are accessible from Non-secure EL1 modes, and from Non-secure EL0 modes if unprivileged access is enabled.
If HPMN is less than PMCR.N, HPMN divides the event counters into two ranges, [0:(HPMN-1)] and [HPMN:(PMCR.N-1)].
For an event counter in the range [0:(HPMN-1)]:
If HPMN is equal to PMCR.N, this applies to all event counters.
If HPMN is less than PMCR.N, for an event counter in the range [HPMN:(PMCR.N-1)]:
If this field is set to 0, or to a value larger than PMCR.N, then the following CONSTRAINED UNPREDICTABLE behavior applies:
On a Warm reset, in a system where the PE resets into EL2 or EL3, this field resets to the value in PMCR.N.
Reserved, RES0.
Accesses to this register use the following encodings:
opc1 | opc2 | CRn | coproc | CRm |
---|---|---|---|---|
0b100 | 0b001 | 0b0001 | 0b1111 | 0b0001 |
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); else UNDEFINED; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDA == '1' then AArch64.AArch32SystemAccessTrap(EL3, 0x03); else return HDCR; elsif PSTATE.EL == EL3 then if SCR.NS == '0' then UNDEFINED; else return HDCR;
opc1 | opc2 | CRn | coproc | CRm |
---|---|---|---|---|
0b100 | 0b001 | 0b0001 | 0b1111 | 0b0001 |
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); else UNDEFINED; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDA == '1' then AArch64.AArch32SystemAccessTrap(EL3, 0x03); else HDCR = R[t]; elsif PSTATE.EL == EL3 then if SCR.NS == '0' then UNDEFINED; else HDCR = R[t];
13/12/2018 16:42; 6379d01c197f1d40720d32d0f84c419c9187c009
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