Controls the Branch Record Buffer.
This register is present only when FEAT_BRBE is implemented. Otherwise, direct accesses to BRBCR_EL2 are UNDEFINED.
If EL2 is not implemented, this register is RES0 from EL3.
BRBCR_EL2 is a 64-bit register.
| 63 | 62 | 61 | 60 | 59 | 58 | 57 | 56 | 55 | 54 | 53 | 52 | 51 | 50 | 49 | 48 | 47 | 46 | 45 | 44 | 43 | 42 | 41 | 40 | 39 | 38 | 37 | 36 | 35 | 34 | 33 | 32 |
| 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 |
| RES0 | |||||||||||||||||||||||||||||||
| RES0 | EXCEPTION | ERTN | RES0 | FZPSS | FZP | RES0 | TS | MPRED | CC | RES0 | E2BRE | E0HBRE | |||||||||||||||||||
Reserved, RES0.
Enable the recording of entry to EL2 via an exception.
| EXCEPTION | Meaning |
|---|---|
| 0b0 |
Disable the recording of Branch records for exceptions when taken to EL2. |
| 0b1 |
Enable the recording of Branch records for exceptions when taken to EL2. |
The reset behavior of this field is:
Allow the recording Branch records for exception return instructions from EL2.
| ERTN | Meaning |
|---|---|
| 0b0 |
Disable the recording Branch records for exception return instructions from EL2. |
| 0b1 |
Enable the recording Branch records for exception return instructions from EL2. |
The reset behavior of this field is:
Reserved, RES0.
Freeze BRBE on PMU Snapshot.
| FZPSS | Meaning |
|---|---|
| 0b0 |
Branch recording is not affected by this control. |
| 0b1 |
If BRBCR_EL1.FZPSS is 1, then a BRBE freeze event occurs when a PMU snapshot occurs. |
The reset behavior of this field is:
Reserved, RES0.
Freeze BRBE on PMU overflow.
| FZP | Meaning |
|---|---|
| 0b0 |
Branch recording is not affected by this control. |
| 0b1 | A BRBE freeze event occurs when the PE is in a Non-prohibited region, BRBFCR_EL1.PAUSED is 0, and all the following are true for any value of m greater than or equal to MDCR_EL2.HPMN:
|
The reset behavior of this field is:
Reserved, RES0.
Reserved, RES0.
Timestamp Control.
| TS | Meaning | Applies when |
|---|---|---|
| 0b00 |
Timestamp controlled by BRBCR_EL1.TS. | |
| 0b01 |
Virtual timestamp. The BRBE recorded timestamp is the physical counter value, minus the value of CNTVOFF_EL2. | |
| 0b10 | Guest physical timestamp. The BRBE recorded timestamp is the physical counter value minus a physical offset. If any of the following are true, the physical offset is zero, otherwise the physical offset is the value of CNTPOFF_EL2:
| When FEAT_ECV is implemented |
| 0b11 |
Physical timestamp. The BRBE recorded timestamp is the physical counter value. |
The reset behavior of this field is:
Mask the recording of mispredicts.
| MPRED | Meaning |
|---|---|
| 0b0 |
Disable the recording of mispredict information. |
| 0b1 |
Allow the recording of mispredict information. |
If EL2 is not implemented, then the Effective value of this field is 1, other than for a direct read of the register.
The reset behavior of this field is:
Enable the recording of cycle count information.
| CC | Meaning |
|---|---|
| 0b0 |
Disable the recording of cycle count information. |
| 0b1 |
Allow the recording of cycle count information. |
If EL2 is not implemented, then the Effective value of this field is 1, other than for a direct read of the register.
The reset behavior of this field is:
Reserved, RES0.
EL2 Branch recording enable.
| E2BRE | Meaning |
|---|---|
| 0b0 |
Branch recording prohibited at EL2. |
| 0b1 |
Branch recording enabled at EL2. |
The reset behavior of this field is:
EL0 Branch recording enable.
| E0HBRE | Meaning |
|---|---|
| 0b0 |
Branch recording prohibited at EL0 when HCR_EL2.TGE == 1. |
| 0b1 |
Branch recording enabled at EL0 when HCR_EL2.TGE == 1. |
This field is ignored by the PE when any of the following are true:
The reset behavior of this field is:
When the Effective value of HCR_EL2.E2H is 1, without explicit synchronization, accesses from EL2 using the register name BRBCR_EL2 or BRBCR_EL1 are not guaranteed to be ordered with respect to accesses using the other register name.
Accesses to this register use the following encodings in the System register encoding space:
MRS <Xt>, BRBCR_EL1
| op0 | op1 | CRn | CRm | op2 |
|---|---|---|---|---|
| 0b10 | 0b001 | 0b1001 | 0b0000 | 0b000 |
if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.SBRBE != '11' && SCR_EL3.NS == '0' then UNDEFINED; elsif HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.SBRBE == 'x0' && SCR_EL3.NS == '1' then UNDEFINED; elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HDFGRTR_EL2.nBRBCTL == '0' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && MDCR_EL3.SBRBE != '11' && SCR_EL3.NS == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); elsif HaveEL(EL3) && MDCR_EL3.SBRBE == 'x0' && SCR_EL3.NS == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); elsif EffectiveHCR_EL2_NVx() == '111' then X[t, 64] = NVMem[0x8E0]; else X[t, 64] = BRBCR_EL1; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.SBRBE != '11' && SCR_EL3.NS == '0' then UNDEFINED; elsif HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.SBRBE == 'x0' && SCR_EL3.NS == '1' then UNDEFINED; elsif HaveEL(EL3) && MDCR_EL3.SBRBE != '11' && SCR_EL3.NS == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); elsif HaveEL(EL3) && MDCR_EL3.SBRBE == 'x0' && SCR_EL3.NS == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); elsif ELIsInHost(EL2) then X[t, 64] = BRBCR_EL2; else X[t, 64] = BRBCR_EL1; elsif PSTATE.EL == EL3 then X[t, 64] = BRBCR_EL1;
MRS <Xt>, BRBCR_EL2
| op0 | op1 | CRn | CRm | op2 |
|---|---|---|---|---|
| 0b10 | 0b100 | 0b1001 | 0b0000 | 0b000 |
if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64.SystemAccessTrap(EL2, 0x18); else UNDEFINED; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.SBRBE != '11' && SCR_EL3.NS == '0' then UNDEFINED; elsif HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.SBRBE == 'x0' && SCR_EL3.NS == '1' then UNDEFINED; elsif HaveEL(EL3) && MDCR_EL3.SBRBE != '11' && SCR_EL3.NS == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); elsif HaveEL(EL3) && MDCR_EL3.SBRBE == 'x0' && SCR_EL3.NS == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else X[t, 64] = BRBCR_EL2; elsif PSTATE.EL == EL3 then X[t, 64] = BRBCR_EL2;
MSR BRBCR_EL1, <Xt>
| op0 | op1 | CRn | CRm | op2 |
|---|---|---|---|---|
| 0b10 | 0b001 | 0b1001 | 0b0000 | 0b000 |
if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.SBRBE != '11' && SCR_EL3.NS == '0' then UNDEFINED; elsif HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.SBRBE == 'x0' && SCR_EL3.NS == '1' then UNDEFINED; elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HDFGWTR_EL2.nBRBCTL == '0' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && MDCR_EL3.SBRBE != '11' && SCR_EL3.NS == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); elsif HaveEL(EL3) && MDCR_EL3.SBRBE == 'x0' && SCR_EL3.NS == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); elsif EffectiveHCR_EL2_NVx() == '111' then NVMem[0x8E0] = X[t, 64]; else BRBCR_EL1 = X[t, 64]; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.SBRBE != '11' && SCR_EL3.NS == '0' then UNDEFINED; elsif HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.SBRBE == 'x0' && SCR_EL3.NS == '1' then UNDEFINED; elsif HaveEL(EL3) && MDCR_EL3.SBRBE != '11' && SCR_EL3.NS == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); elsif HaveEL(EL3) && MDCR_EL3.SBRBE == 'x0' && SCR_EL3.NS == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); elsif ELIsInHost(EL2) then BRBCR_EL2 = X[t, 64]; else BRBCR_EL1 = X[t, 64]; elsif PSTATE.EL == EL3 then BRBCR_EL1 = X[t, 64];
MSR BRBCR_EL2, <Xt>
| op0 | op1 | CRn | CRm | op2 |
|---|---|---|---|---|
| 0b10 | 0b100 | 0b1001 | 0b0000 | 0b000 |
if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64.SystemAccessTrap(EL2, 0x18); else UNDEFINED; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.SBRBE != '11' && SCR_EL3.NS == '0' then UNDEFINED; elsif HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.SBRBE == 'x0' && SCR_EL3.NS == '1' then UNDEFINED; elsif HaveEL(EL3) && MDCR_EL3.SBRBE != '11' && SCR_EL3.NS == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); elsif HaveEL(EL3) && MDCR_EL3.SBRBE == 'x0' && SCR_EL3.NS == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else BRBCR_EL2 = X[t, 64]; elsif PSTATE.EL == EL3 then BRBCR_EL2 = X[t, 64];