no old file | htmldiff from- | (new)

AArch32 Registers | AArch64 Registers | AArch32 Instructions | AArch64 Instructions | Index by Encoding | External Registers | External Registers by Offset | Registers by Functional Group | Proprietary Notice

# TRCCCCTLR, Cycle Count Control Register

The TRCCCCTLR characteristics are:

## Purpose

Set the threshold value for cycle counting.

## Configuration

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

This register is present only when TRCIDR0.TRCCCI == 0b1 and ETE is implemented. Otherwise, direct accesses to TRCCCCTLR are UNDEFINED.

## Attributes

TRCCCCTLR is a 64-bit register.

## Field descriptions

The TRCCCCTLR bit assignments are:

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
RES0
RES0 | THRESHOLD
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

#### Bits [63:12]

Reserved, RES0.

#### THRESHOLD, bits [11:0]

Sets the threshold value for instruction trace cycle counting.

The minimum threshold value that can be programmed into THRESHOLD is given in TRCIDR3.CCITMIN. If the THRESHOLD value is smaller than the value in TRCIDR3.CCITMIN then the behavior is CONSTRAINED UNPREDICTABLE. That is, cycle counts might or might not be included in the trace and the cycle count threshold is not known.

Writing a value of zero when TRCCONFIGR.CCI is set to enable instruction trace cycle counting, results in CONSTRAINED UNPREDICTABLE behavior. That is, cycle counts might or might not be included in the trace and the cycle count threshold is not known.

On a Trace unit reset, this field resets to an architecturally UNKNOWN value.

## Accessing the TRCCCCTLR

Must be programmed if TRCCONFIGR.CCI == 0b1.

Writes are CONSTRAINED UNPREDICTABLE if the trace unit is not in the Idle state.

Accesses to this register use the following encodings:

#### MRS <Xt>, TRCCCCTLR

op0 | op1 | CRn | CRm | op2
--- | --- | --- | --- | ---
0b10 | 0b001 | 0b0000 | 0b1110 | 0b000

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if CPACR_EL1.TTA == '1' then AArch64.SystemAccessTrap(EL1, 0x18); elsif EL2Enabled() && !ELUsingAArch32(EL2) && CPTR_EL2.TTA == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.TTA == '1' then AArch64.SystemAccessTrap(EL3, 0x18); else return TRCCCCTLR; elsif PSTATE.EL == EL2 then if CPTR_EL2.TTA == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.TTA == '1' then AArch64.SystemAccessTrap(EL3, 0x18); else return TRCCCCTLR; elsif PSTATE.EL == EL3 then if CPTR_EL3.TTA == '1' then AArch64.SystemAccessTrap(EL3, 0x18); else return TRCCCCTLR;

#### MSR TRCCCCTLR, <Xt>

op0 | op1 | CRn | CRm | op2
--- | --- | --- | --- | ---
0b10 | 0b001 | 0b0000 | 0b1110 | 0b000

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if CPACR_EL1.TTA == '1' then AArch64.SystemAccessTrap(EL1, 0x18); elsif EL2Enabled() && !ELUsingAArch32(EL2) && CPTR_EL2.TTA == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.TTA == '1' then AArch64.SystemAccessTrap(EL3, 0x18); else TRCCCCTLR = X[t]; elsif PSTATE.EL == EL2 then if CPTR_EL2.TTA == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.TTA == '1' then AArch64.SystemAccessTrap(EL3, 0x18); else TRCCCCTLR = X[t]; elsif PSTATE.EL == EL3 then if CPTR_EL3.TTA == '1' then AArch64.SystemAccessTrap(EL3, 0x18); else TRCCCCTLR = X[t];

AArch32 Registers | AArch64 Registers | AArch32 Instructions | AArch64 Instructions | Index by Encoding | External Registers | External Registers by Offset | Registers by Functional Group | Proprietary Notice

15/04/2019 16:47; 8c23526ba8a13a72aada4137daf3e3977b49036e

Copyright © 2010-2019 Arm Limited or its affiliates. All rights reserved. This document is Non-Confidential.

no old file | htmldiff from- | (new)