Activity Monitors Event Counter Registers 0
Provides access to the architected activity monitor event counters.
AArch64 System register AMEVCNTR0<n>_EL0 bits [31:0] are architecturally mapped to AArch32 System register AMEVCNTR0<n>[31:0].
AArch64 System register AMEVCNTR0<n>_EL0 bits [63:0] are architecturally mapped to External register AMEVCNTR0<n>[63:0].
This register is present only when FEAT_AMUv1 is implemented. Otherwise, direct accesses to AMEVCNTR0<n>_EL0 are UNDEFINED.
AMEVCNTR0<n>_EL0 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 |
| ACNT | |||||||||||||||||||||||||||||||
| ACNT | |||||||||||||||||||||||||||||||
Architected activity monitor event counter n.
Value of architected activity monitor event counter n, where n is the number of this register and is a number from 0 to 3.
If all of the following are true, reads of the AMEVCNTR0<n>_EL0 registers from EL0 or EL1 return (PCount<63:0> - AMEVCNTVOFF0<n>_EL2<63:0>), where PCount is the physical count returned when AMEVCNTR0<n>_EL0 is read from EL2 or EL3:
If the counter is enabled, writes to this register have UNPREDICTABLE results.
The reset behavior of this field is:
If <n> is greater than or equal to the number of architected activity monitor event counters, reads and writes of AMEVCNTR0<n>_EL0 are UNDEFINED.
AMCGCR_EL0.CG0NC identifies the number of architected activity monitor event counters.
Accesses to this register use the following encodings in the System register encoding space:
MRS <Xt>, AMEVCNTR0<m>_EL0 ; Where m = 0-3
(op0 = 0b11, op1 = 0b011, CRn = 0b1101, CRm = 0b010:m[3], op2 = m[2:0])
let m:integer = UInt(CRm[0] :: op2[2:0]); if !IsFeatureImplemented(FEAT_AMUv1) then Undefined(); elsif m >= 4 then Undefined(); elsif HaveEL(EL3) && PSTATE.EL != EL3 && EL3SDDUndefPriority() && CPTR_EL3().TAM == '1' then Undefined(); elsif PSTATE.EL == EL0 then if AMUSERENR_EL0().EN == '0' then AArch64_SystemAccessTraptoEL1orEL2(0x18); elsif EL2Enabled() && CPTR_EL2().TAM == '1' then AArch64_SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && EffectivelyAtEL0NotInHost() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3().FGTEn == '1') && HAFGRTR_EL2()[m + 1] == '1' then AArch64_SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && CPTR_EL3().TAM == '1' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; else X{64}(t) = AMEVCNTR0_EL0(m); end; elsif PSTATE.EL == EL1 then if EL2Enabled() && CPTR_EL2().TAM == '1' then AArch64_SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3().FGTEn == '1') && HAFGRTR_EL2()[m + 1] == '1' then AArch64_SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && CPTR_EL3().TAM == '1' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; else X{64}(t) = AMEVCNTR0_EL0(m); end; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && CPTR_EL3().TAM == '1' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; else X{64}(t) = AMEVCNTR0_EL0(m); end; elsif PSTATE.EL == EL3 then X{64}(t) = AMEVCNTR0_EL0(m); end;
MSR AMEVCNTR0<m>_EL0, <Xt> ; Where m = 0-3
(op0 = 0b11, op1 = 0b011, CRn = 0b1101, CRm = 0b010:m[3], op2 = m[2:0])
let m:integer = UInt(CRm[0] :: op2[2:0]); if !IsFeatureImplemented(FEAT_AMUv1) then Undefined(); elsif m >= 4 then Undefined(); elsif IsHighestEL(PSTATE.EL) then AMEVCNTR0_EL0(m) = X{64}(t); else Undefined(); end;
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