CPTR_EL3 Architectural Feature Trap Register (EL3) when EL3 is implemented and FEAT_AA64 is implemented Controls trapping to EL3 of accesses to CPACR, CPACR_EL1, HCPTR, CPTR_EL2, trace, Activity Monitor, SME, Streaming SVE, SVE, and Advanced SIMD and floating-point functionality. Secure CPTR_EL3 is a 64-bit register. 63 32 63:32 Reserved, RES0. TCPAC 31 31 31 Traps all of the following to EL3, from both Execution states and any Security state. EL2 accesses to CPTR_EL2, reported using EC syndrome value 0x18, or HCPTR, reported using EC syndrome value 0x03. EL2 and EL1 accesses to CPACR_EL1 reported using EC syndrome value 0x18, or CPACR reported using EC syndrome value 0x03. When CPTR_EL3.TCPAC is: 0b0 This control does not cause any instructions to be trapped. 0b1 EL2 accesses to the CPTR_EL2 or HCPTR, and EL2 and EL1 accesses to the CPACR_EL1 or CPACR, are trapped to EL3, unless they are trapped by CPTR_EL2.TCPAC. AU TAM 30 30 0 Trap Activity Monitor access. Traps EL2, EL1, and EL0 accesses to all Activity Monitors System registers to EL3. Accesses to the Activity Monitors System registers are trapped as follows: In AArch64 state, the following registers are trapped to EL3 and reported using EC syndrome value 0x18: AMUSERENR_EL0, AMCFGR_EL0, AMCGCR_EL0, AMCNTENCLR0_EL0, AMCNTENCLR1_EL0, AMCNTENSET0_EL0, AMCNTENSET1_EL0, AMCR_EL0, AMEVCNTR0<n>_EL0, AMEVCNTR1<n>_EL0, AMEVTYPER0<n>_EL0, and AMEVTYPER1<n>_EL0. In AArch32 state, accesses with MRC or MCR to the following registers reported using EC syndrome value 0x03: AMUSERENR, AMCFGR, AMCGCR, AMCNTENCLR0, AMCNTENCLR1, AMCNTENSET0, AMCNTENSET1, AMCR, AMEVTYPER0<n>, and AMEVTYPER1<n>. In AArch32 state, accesses with MRRC or MCRR to the following registers, reported using EC syndrome value 0x04: AMEVCNTR0<n>, AMEVCNTR1<n>. 0b0 Accesses from EL2, EL1, and EL0 to Activity Monitors System registers are not trapped. 0b1 Accesses from EL2, EL1, and EL0 to Activity Monitors System registers are trapped to EL3. AU When FEAT_AMUv1 is implemented 30 30 30 Reserved, RES0. Otherwise 29 21 29:21 Reserved, RES0. TTA 20 20 0 Traps System register accesses. Accesses to the trace System registers, from all Exception levels, any Security state, and both Execution states are trapped to EL3 as follows: In AArch64 state, trace System registers with op0=2, op1=1, and CRn<0b1000 are trapped to EL3 and reported using EC syndrome value 0x18. In AArch32 state, accesses using MCR or MRC to the trace System registers with cpnum=14, opc1=1, and CRn<0b1000 are reported using EC syndrome value 0x05. The ETMv4 architecture and ETE do not permit EL0 to access the trace System registers. If the trace unit implements FEAT_ETMv4 or FEAT_ETE, EL0 accesses to the trace System registers are UNDEFINED, and any resulting exception is higher priority than this trap exception. EL3 does not provide traps on trace System register accesses through the Memory-mapped interface. System register accesses to the trace System registers can have side-effects. When a System register access is trapped, no side-effects occur before the exception is taken, see 'Configurable instruction controls'. 0b0 This control does not cause any instructions to be trapped. 0b1 Any System register access to the trace System registers is trapped to EL3, unless it is trapped by CPACR.TRCDIS, CPACR_EL1.TTA, or CPTR_EL2.TTA. AU When System register access to the trace unit registers is implemented 20 20 20 Reserved, RES0. Otherwise 19 13 19:13 Reserved, RES0. ESM 12 12 0 Traps execution of SME instructions, SVE instructions when FEAT_SVE is not implemented or the PE is in Streaming SVE mode, and instructions that directly access the SMCR_EL1, SMCR_EL2, SMCR_EL3, SMPRI_EL1, SMPRIMAP_EL2, or SVCR System registers, from all Exception levels and any Security state, to EL3. When instructions that directly access the SVCR System register are trapped with reference to this control, the MSR SVCRSM, MSR SVCRZA, and MSR SVCRSMZA instructions are also trapped. When direct accesses to SMPRI_EL1 and SMPRIMAP_EL2 are trapped, the exception is reported using EC syndrome value 0x18. Otherwise, the exception is reported using EC syndrome value 0x1D, with an ISS code of 0x0000000. This field does not affect whether Streaming SVE or SME register values are valid. A trap taken as a result of CPTR_EL3.ESM has precedence over a trap taken as a result of CPTR_EL3.TFP. 0b0 This control causes execution of these instructions at all Exception levels to be trapped. 0b1 This control does not cause execution of any instructions to be trapped. AU When FEAT_SME is implemented 12 12 12 Reserved, RES0. Otherwise 11 11 11 Reserved, RES0. TFP 10 10 10 Traps execution of instructions which access the Advanced SIMD and floating-point functionality, from all Exception levels, any Security state, and both Execution states, to EL3. This includes the following registers, all reported using EC syndrome value 0x07: FPCR, FPSR, FPEXC32_EL2, and any of the SIMD and floating-point registers V0-V31, including their views as D0-D31 registers or S0-S31 registers. If FEAT_FPMR is implemented, FPMR. MVFR0, MVFR1, MVFR2, FPSCR, FPEXC, and any of the SIMD and floating-point registers Q0-Q15, including their views as D0-D31 registers or S0-S31 registers. VMSR accesses to FPSID. Permitted VMSR accesses to FPSID are ignored, but for the purposes of this trap the architecture defines a VMSR access to the FPSID from EL1 or higher as an access to a SIMD and floating-point register. Traps execution at all Exception levels of SME and SVE instructions to EL3 from any Security state. The exception is reported using EC syndrome value 0x07. A trap taken as a result of CPTR_EL3.ESM has precedence over a trap taken as a result of CPTR_EL3.TFP. A trap taken as a result of CPTR_EL3.EZ has precedence over a trap taken as a result of CPTR_EL3.TFP. FPEXC32_EL2 is not accessible from EL0 using AArch64. FPSID, MVFR0, MVFR1, and FPEXC are not accessible from EL0 using AArch32. 0b0 This control does not cause execution of any instructions to be trapped. 0b1 This control causes execution of these instructions at all Exception levels to be trapped. AU 9 9 9 Reserved, RES0. EZ 8 8 0 Traps execution of SVE instructions when the PE is not in Streaming SVE mode, and instructions that directly access the ZCR_EL3, ZCR_EL2, or ZCR_EL1 System registers, from all Exception levels and any Security state, to EL3. The exception is reported using EC syndrome value 0x19. A trap taken as a result of CPTR_EL3.EZ has precedence over a trap taken as a result of CPTR_EL3.TFP. 0b0 This control causes execution of these instructions at all Exception levels to be trapped. 0b1 This control does not cause execution of any instructions to be trapped. AU When FEAT_SVE is implemented 8 8 8 Reserved, RES0. Otherwise 7 0 7:0 Reserved, RES0. MRS <Xt>, CPTR_EL3 if !(HaveEL(EL3) && IsFeatureImplemented(FEAT_AA64)) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then Undefined(); elsif PSTATE.EL == EL2 then Undefined(); elsif PSTATE.EL == EL3 then X{64}(t) = CPTR_EL3(); end; MSR CPTR_EL3, <Xt> if !(HaveEL(EL3) && IsFeatureImplemented(FEAT_AA64)) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then Undefined(); elsif PSTATE.EL == EL2 then Undefined(); elsif PSTATE.EL == EL3 then CPTR_EL3() = X{64}(t); end; 2026-03-26 20:27:25 2026-03_rel