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The CPACR_EL1 characteristics are:
Controls access to trace, SVE, Advanced SIMD and floating-point functionality.
AArch64 System register CPACR_EL1 bits [31:0] are architecturally mapped to AArch32 System register CPACR[31:0] .
When HCR_EL2.{E2H, TGE} == {1, 1}, the fields in this register have no effect on execution at EL0 and EL1. In this case, the controls provided by CPTR_EL2 are used.
CPACR_EL1 is a 64-bit register.
The CPACR_EL1 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 | TTA | RES0 | FPEN | RES0 | ZEN | RES0 | |||||||||||||||||||||||||
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 |
Reserved, RES0.
Traps EL0 and EL1 System register accesses to all implemented trace registers to EL1, or to EL2 when it is implemented and enabled for the current Security state and HCR_EL2.{E2H, .TGE} is {01,1}, from both Execution states as follows:
In AArch64 state, accesses to trace registers are trapped, reported using EC syndrome value 0x18.
In AArch32 state, MRC and MCR accesses to trace registers are trapped, reported using EC syndrome value 0x05.
In AArch32 state, MRRC and MCRR accesses to trace registers are trapped, reported using EC syndrome value 0x0C.
TTA | Meaning |
---|---|
0b0 | This control does not cause any instructions to be trapped. |
0b1 | This control causes EL0 and EL1 System register accesses to all implemented trace registers to be trapped. |
System register accesses to the trace registers can have side-effects. When a System register access is trapped, any side-effects that are normally associated with the access do not occur before the exception is taken.
If System register access to the trace functionality is not implemented, this bit is RES0.
This field resets to an architecturally UNKNOWN value.
Reserved, RES0.
Traps EL0 and EL1 accesses to the SVE, Advanced SIMD, and floating-point registers to EL1, reported using EC syndrome value 0x07, or to EL2 reported using EC syndrome value 0x00, when EL2 is implemented and enabled for the current Security state and HCR_EL2.{E2H, .TGE} is {01,1}, from both Execution states as follows:
FPEN | Meaning |
---|---|
0b00 | This control causes any instructions at EL0 or EL1 that use the registers associated with SVE, Advanced SIMD and floating-point execution to be trapped, unless they are trapped by CPACR_EL1.ZEN. |
0b01 | This control causes any instructions at EL0 that use the registers associated with SVE, Advanced SIMD and floating-point execution to be trapped, unless they are trapped by CPACR_EL1.ZEN, but does not cause any instruction at EL1 to be trapped. |
0b10 | This control causes any instructions at EL0 or EL1 that use the registers associated with SVE, Advanced SIMD and floating-point execution to be trapped, unless they are trapped by CPACR_EL1.ZEN. |
0b11 | This control does not cause any instructions to be trapped. |
Writes to MVFR0, MVFR1 and MVFR2 from EL1 or higher are CONSTRAINED UNPREDICTABLE and whether these accesses can be trapped by this control depends on implemented CONSTRAINED UNPREDICTABLE behavior.
This field resets to an architecturally UNKNOWN value.
Reserved, RES0.
Traps SVE instructions and instructions that access SVE System registers at EL0 and EL1 to EL1, or to EL2 when it is implemented and enabled for the current Security state and HCR_EL2.{E2H, .TGE} is {0,1}.1.
ZEN | Meaning |
---|---|
0b00 | This control causes these instructions executed at EL0 or EL1 to be trapped. |
0b01 | This control causes these instructions executed at EL0 to be trapped, but does not cause any instruction at EL1 to be trapped. |
0b10 | This control causes these instructions executed at EL0 or EL1 to be trapped. |
0b11 | This control does not cause any instruction to be trapped. |
This field resets to an architecturally UNKNOWN value.
Reserved, RES0.
Reserved, RES0.
When HCR_EL2.E2H is 1, without explicit synchronization, access from EL3 using the mnemonic CPACR_EL1 or CPACR_EL12 are not guaranteed to be ordered with respect to accesses using the other mnemonic.
Accesses to this register use the following encodings:
op0 | op1 | CRn | CRm | op2 |
---|---|---|---|---|
0b11 | 0b000 | 0b0001 | 0b0000 | 0b010 |
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) && CPTR_EL3.TCPAC == '1' then
UNDEFINED;
elsif EL2Enabled() && !ELUsingAArch32(EL2) && CPTR_EL2.TCPAC == '1' then
AArch64.SystemAccessTrap(EL2, 0x18);
elsif EL2Enabled() && !ELUsingAArch32(EL2) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGRTR_EL2.CPACR_EL1 == '1' then
AArch64.SystemAccessTrap(EL2, 0x18);
elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.TCPAC == '1' then
if Halted() && EDSCR.SDD == '1' then
UNDEFINED;
else
AArch64.SystemAccessTrap(EL3, 0x18);
elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<NV2,NV1,NV> == '111' then
return NVMem[0x100];
else
return CPACR_EL1;
elsif PSTATE.EL == EL2 then
if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && CPTR_EL3.TCPAC == '1' then
UNDEFINED;
elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.TCPAC == '1' then
if Halted() && EDSCR.SDD == '1' then
UNDEFINED;
else
AArch64.SystemAccessTrap(EL3, 0x18);
elsif HCR_EL2.E2H == '1' then
return CPTR_EL2;
else
return CPACR_EL1;
elsif PSTATE.EL == EL3 then
return CPACR_EL1;
op0 | op1 | CRn | CRm | op2 |
---|---|---|---|---|
0b11 | 0b000 | 0b0001 | 0b0000 | 0b010 |
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) && CPTR_EL3.TCPAC == '1' then
UNDEFINED;
elsif EL2Enabled() && !ELUsingAArch32(EL2) && CPTR_EL2.TCPAC == '1' then
AArch64.SystemAccessTrap(EL2, 0x18);
elsif EL2Enabled() && !ELUsingAArch32(EL2) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGWTR_EL2.CPACR_EL1 == '1' then
AArch64.SystemAccessTrap(EL2, 0x18);
elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.TCPAC == '1' then
if Halted() && EDSCR.SDD == '1' then
UNDEFINED;
else
AArch64.SystemAccessTrap(EL3, 0x18);
elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<NV2,NV1,NV> == '111' then
NVMem[0x100] = X[t];
else
CPACR_EL1 = X[t];
elsif PSTATE.EL == EL2 then
if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && CPTR_EL3.TCPAC == '1' then
UNDEFINED;
elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.TCPAC == '1' then
if Halted() && EDSCR.SDD == '1' then
UNDEFINED;
else
AArch64.SystemAccessTrap(EL3, 0x18);
elsif HCR_EL2.E2H == '1' then
CPTR_EL2 = X[t];
else
CPACR_EL1 = X[t];
elsif PSTATE.EL == EL3 then
CPACR_EL1 = X[t];
op0 | op1 | CRn | CRm | op2 |
---|---|---|---|---|
0b11 | 0b101 | 0b0001 | 0b0000 | 0b010 |
if PSTATE.EL == EL0 then
UNDEFINED;
elsif PSTATE.EL == EL1 then
if EL2Enabled() && HCR_EL2.<NV2,NV1,NV> == '101' then
return NVMem[0x100];
elsif EL2Enabled() && HCR_EL2.NV == '1' then
AArch64.SystemAccessTrap(EL2, 0x18);
else
UNDEFINED;
elsif PSTATE.EL == EL2 then
if HCR_EL2.E2H == '1' then
if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && CPTR_EL3.TCPAC == '1' then
UNDEFINED;
elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.TCPAC == '1' then
if Halted() && EDSCR.SDD == '1' then
UNDEFINED;
else
AArch64.SystemAccessTrap(EL3, 0x18);
else
return CPACR_EL1;
else
UNDEFINED;
elsif PSTATE.EL == EL3 then
if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.E2H == '1' then
return CPACR_EL1;
else
UNDEFINED;
op0 | op1 | CRn | CRm | op2 |
---|---|---|---|---|
0b11 | 0b101 | 0b0001 | 0b0000 | 0b010 |
if PSTATE.EL == EL0 then
UNDEFINED;
elsif PSTATE.EL == EL1 then
if EL2Enabled() && HCR_EL2.<NV2,NV1,NV> == '101' then
NVMem[0x100] = X[t];
elsif EL2Enabled() && HCR_EL2.NV == '1' then
AArch64.SystemAccessTrap(EL2, 0x18);
else
UNDEFINED;
elsif PSTATE.EL == EL2 then
if HCR_EL2.E2H == '1' then
if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && CPTR_EL3.TCPAC == '1' then
UNDEFINED;
elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.TCPAC == '1' then
if Halted() && EDSCR.SDD == '1' then
UNDEFINED;
else
AArch64.SystemAccessTrap(EL3, 0x18);
else
CPACR_EL1 = X[t];
else
UNDEFINED;
elsif PSTATE.EL == EL3 then
if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.E2H == '1' then
CPACR_EL1 = X[t];
else
UNDEFINED;
0114/0704/2020 1520:5709; 80324f0b9997bede489cc15ad1565345720bcd2adff0d3e465311dd9ce541b6a1e1d6c05a0668645
Copyright © 2010-2020 Arm Limited or its affiliates. All rights reserved. This document is Non-Confidential.
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