The ZCR_EL1 characteristics are:
This register controls aspects of SVE visible at Exception levels EL1 and EL0.
This register is present only when FEAT_SVE is implemented. Otherwise, direct accesses to ZCR_EL1 are UNDEFINED.
This register has no effect if the PE is in Streaming SVE mode.
When HCR_EL2.{E2H, TGE} == {1, 1} and EL2 is enabled in the current Security state, this register has no effect on execution at EL0.
ZCR_EL1 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 | RAZ/WI | LEN |
Reserved, RES0.
Reserved, RAZ/WI.
Effective SVE Vector Length (VL).
Constrains the effective scalable vector register length for EL1 and EL0 to (LEN+1)*128 bits when the PE is not in Streaming SVE mode.
For all purposes other than returning the result of a direct read of ZCR_EL1, this field selects the effective vector length as follows:
If the requested length is larger than the effective vector length at the next more privileged Exception level in the current Security state, if any, then the effective vector length at the more privileged Exception level is used.
If the requested length is not implemented, then the requested length rounded down to the nearest implemented scalable vector length is used.
Otherwise, the requested length is used.
An indirect read of ZCR_EL1.LEN appears to occur in program order relative to a direct write of the same register, without the need for explicit synchronization.
The reset behavior of this field is:
When HCR_EL2.E2H is 1, without explicit synchronization, access from EL3 using the mnemonic ZCR_EL1 or ZCR_EL12 are not guaranteed to be ordered with respect to accesses using the other mnemonic.
Accesses to this register use the following encodings in the System register encoding space:
op0 | op1 | CRn | CRm | op2 |
---|---|---|---|---|
0b11 | 0b000 | 0b0001 | 0b0010 | 0b000 |
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.EZ == '0' then UNDEFINED; elsif CPACR_EL1.ZEN == 'x0' then AArch64.SystemAccessTrap(EL1, 0x19); elsif EL2Enabled() && HCR_EL2.E2H == '0' && CPTR_EL2.TZ == '1' then AArch64.SystemAccessTrap(EL2, 0x19); elsif EL2Enabled() && HCR_EL2.E2H == '1' && CPTR_EL2.ZEN == 'x0' then AArch64.SystemAccessTrap(EL2, 0x19); elsif HaveEL(EL3) && CPTR_EL3.EZ == '0' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x19); elsif EL2Enabled() && HCR_EL2.<NV2,NV1,NV> == '111' then return NVMem[0x1E0]; else return ZCR_EL1; elsif PSTATE.EL == EL2 then if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && CPTR_EL3.EZ == '0' then UNDEFINED; elsif HCR_EL2.E2H == '0' && CPTR_EL2.TZ == '1' then AArch64.SystemAccessTrap(EL2, 0x19); elsif HCR_EL2.E2H == '1' && CPTR_EL2.ZEN == 'x0' then AArch64.SystemAccessTrap(EL2, 0x19); elsif HaveEL(EL3) && CPTR_EL3.EZ == '0' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x19); elsif HCR_EL2.E2H == '1' then return ZCR_EL2; else return ZCR_EL1; elsif PSTATE.EL == EL3 then if CPTR_EL3.EZ == '0' then AArch64.SystemAccessTrap(EL3, 0x19); else return ZCR_EL1;
op0 | op1 | CRn | CRm | op2 |
---|---|---|---|---|
0b11 | 0b000 | 0b0001 | 0b0010 | 0b000 |
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.EZ == '0' then UNDEFINED; elsif CPACR_EL1.ZEN == 'x0' then AArch64.SystemAccessTrap(EL1, 0x19); elsif EL2Enabled() && HCR_EL2.E2H == '0' && CPTR_EL2.TZ == '1' then AArch64.SystemAccessTrap(EL2, 0x19); elsif EL2Enabled() && HCR_EL2.E2H == '1' && CPTR_EL2.ZEN == 'x0' then AArch64.SystemAccessTrap(EL2, 0x19); elsif HaveEL(EL3) && CPTR_EL3.EZ == '0' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x19); elsif EL2Enabled() && HCR_EL2.<NV2,NV1,NV> == '111' then NVMem[0x1E0] = X[t]; else ZCR_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.EZ == '0' then UNDEFINED; elsif HCR_EL2.E2H == '0' && CPTR_EL2.TZ == '1' then AArch64.SystemAccessTrap(EL2, 0x19); elsif HCR_EL2.E2H == '1' && CPTR_EL2.ZEN == 'x0' then AArch64.SystemAccessTrap(EL2, 0x19); elsif HaveEL(EL3) && CPTR_EL3.EZ == '0' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x19); elsif HCR_EL2.E2H == '1' then ZCR_EL2 = X[t]; else ZCR_EL1 = X[t]; elsif PSTATE.EL == EL3 then if CPTR_EL3.EZ == '0' then AArch64.SystemAccessTrap(EL3, 0x19); else ZCR_EL1 = X[t];
op0 | op1 | CRn | CRm | op2 |
---|---|---|---|---|
0b11 | 0b101 | 0b0001 | 0b0010 | 0b000 |
if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && HCR_EL2.<NV2,NV1,NV> == '101' then return NVMem[0x1E0]; 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.EZ == '0' then UNDEFINED; elsif CPTR_EL2.ZEN == 'x0' then AArch64.SystemAccessTrap(EL2, 0x19); elsif HaveEL(EL3) && CPTR_EL3.EZ == '0' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x19); else return ZCR_EL1; else UNDEFINED; elsif PSTATE.EL == EL3 then if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.E2H == '1' then if CPTR_EL3.EZ == '0' then AArch64.SystemAccessTrap(EL3, 0x19); else return ZCR_EL1; else UNDEFINED;
op0 | op1 | CRn | CRm | op2 |
---|---|---|---|---|
0b11 | 0b101 | 0b0001 | 0b0010 | 0b000 |
if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && HCR_EL2.<NV2,NV1,NV> == '101' then NVMem[0x1E0] = 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.EZ == '0' then UNDEFINED; elsif CPTR_EL2.ZEN == 'x0' then AArch64.SystemAccessTrap(EL2, 0x19); elsif HaveEL(EL3) && CPTR_EL3.EZ == '0' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x19); else ZCR_EL1 = X[t]; else UNDEFINED; elsif PSTATE.EL == EL3 then if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.E2H == '1' then if CPTR_EL3.EZ == '0' then AArch64.SystemAccessTrap(EL3, 0x19); else ZCR_EL1 = X[t]; else UNDEFINED;
20/09/2021 12:37; d4a233ffbdfb36e47856c443a7ce9a85f5e501ca
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