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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 {0,1}, from both Execution states as follows:
In AArch64 state, accesses to trace registers are trapped, reported using ESR_ELx.ECEC syndrome value 0x18.
In AArch32 state, MRC and MCR accesses to trace registers are trapped, reported using ESR_ELx.ECEC syndrome value 0x05.
In AArch32 state, MRRC and MCRR accesses to trace registers are trapped, reported using ESR_ELx.ECEC 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.
On a Warm reset, thisThis 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 ESR_ELx.ECEC syndrome value 0x07, or to EL2 reported using ESR_ELx.ECEC syndrome value 0x00, when EL2 is implemented and enabled for the current Security state and HCR_EL2.{E2H, TGE} is {0,1}, from both Execution states as follows:
Trapping behavior is affected by precedence as follows: A trap taken as a result of CPACR_EL1.ZEN has precedence over the value of CPACR_EL1.FPEN.
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. |
0b01 | This control causes any instructions at EL0 that use the registers associated with SVE, Advanced SIMD and floating-point execution to be trapped, but |
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. |
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.
On a Warm reset, thisThis field resets to an architecturally UNKNOWN value.
Reserved, RES0.
Traps SVE instructions and instructions that access SVE System registers at EL0 and EL1 executionto ofEL1, SVEor instructionsto EL2 when it is implemented and instructionsenabled thatfor directlythe accesscurrent Security state and ZCR_EL1 System register to EL1, or to EL2 when EL2 is implemented and enabled for the current Security state and HCR_EL2.{E2H, TGE} is {0,1}.
The exception is reported using ESR_ELx.EC value 0x19.
Trapping behavior is affected by precedence as follows: A trap taken as a result of CPACR_EL1.ZEN has precedence over the value of CPACR_EL1.FPEN.
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. |
On a Warm reset, thisThis 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'" && CPTR_EL3.TCPAC == '1' then UNDEFINED; elsif EL2Enabled() && CPTR_EL2.TCPAC == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGRTR_EL2.CPACR_EL1 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && CPTR_EL3.TCPAC == '1' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); elsif EL2Enabled() && 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'" && CPTR_EL3.TCPAC == '1' then UNDEFINED; elsif HaveEL(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'" && CPTR_EL3.TCPAC == '1' then UNDEFINED; elsif EL2Enabled() && CPTR_EL2.TCPAC == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGWTR_EL2.CPACR_EL1 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && CPTR_EL3.TCPAC == '1' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); elsif EL2Enabled() && 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'" && CPTR_EL3.TCPAC == '1' then UNDEFINED; elsif HaveEL(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'" && CPTR_EL3.TCPAC == '1' then UNDEFINED; elsif HaveEL(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'" && CPTR_EL3.TCPAC == '1' then UNDEFINED; elsif HaveEL(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;
3001/0907/2020 15:0757; ccead0cb9f089f9ceec50268e82aec9e7104721180324f0b9997bede489cc15ad1565345720bcd2a
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