AMUSERENR

Global user enable register for the activity monitors. Enables or disables EL0 access to the activity monitors. AMUSERENR_EL0 is applicable to both the architected and the auxiliary counter groups.

Configuration

AArch64 System register AMUSERENR_EL0 bits [31:0] are architecturally mapped to AArch32 System register AMUSERENR[31:0].

This register is present only when FEAT_AMUv1 is implemented. Otherwise, direct accesses to AMUSERENR_EL0 are UNDEFINED.

Attributes

Field descriptions

Bits [63:1]

EN, bit [0]

Traps EL0 accesses to the activity monitors registers to EL1, or to EL2 when it is implemented and enabled for the current Security state and HCR_EL2.TGE is 1, as follows:

In AArch64 state, accesses to the following registers are trapped, reported using EC syndrome value 0x18:
- 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, MRC and MCR accesses to the following registers are trapped and reported using EC syndrome value 0x03, MRRC and MCRR accesses are trapped and reported using EC syndrome value 0x04:
- AMCFGR, AMCGCR, AMCNTENCLR0, AMCNTENCLR1, AMCNTENSET0, AMCNTENSET1, AMCR, AMEVCNTR0<n>, AMEVCNTR1<n>, AMEVTYPER0<n>, and AMEVTYPER1<n>.

EN	Meaning
0b0	EL0 accesses to the activity monitors registers are trapped.
0b1	This control does not cause any instructions to be trapped. Software can access all activity monitor registers at EL0.

Note

AMUSERENR_EL0 can always be read at EL0 and is not governed by this bit.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

Accessing AMUSERENR_EL0

Accesses to this register use the following encodings in the System register encoding space:

MRS <Xt>, AMUSERENR_EL0

op0	op1	CRn	CRm	op2
0b11	0b011	0b1101	0b0010	0b011

if PSTATE.EL == EL0 then if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && CPTR_EL3.TAM == '1' then UNDEFINED; elsif EL2Enabled() && CPTR_EL2.TAM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && CPTR_EL3.TAM == '1' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else X[t, 64] = AMUSERENR_EL0; elsif PSTATE.EL == EL1 then if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && CPTR_EL3.TAM == '1' then UNDEFINED; elsif EL2Enabled() && CPTR_EL2.TAM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && CPTR_EL3.TAM == '1' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else X[t, 64] = AMUSERENR_EL0; elsif PSTATE.EL == EL2 then if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && CPTR_EL3.TAM == '1' then UNDEFINED; elsif HaveEL(EL3) && CPTR_EL3.TAM == '1' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else X[t, 64] = AMUSERENR_EL0; elsif PSTATE.EL == EL3 then X[t, 64] = AMUSERENR_EL0;

MSR AMUSERENR_EL0, <Xt>

op0	op1	CRn	CRm	op2
0b11	0b011	0b1101	0b0010	0b011

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.TAM == '1' then UNDEFINED; elsif EL2Enabled() && CPTR_EL2.TAM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && CPTR_EL3.TAM == '1' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else AMUSERENR_EL0 = X[t, 64]; elsif PSTATE.EL == EL2 then if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && CPTR_EL3.TAM == '1' then UNDEFINED; elsif HaveEL(EL3) && CPTR_EL3.TAM == '1' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else AMUSERENR_EL0 = X[t, 64]; elsif PSTATE.EL == EL3 then AMUSERENR_EL0 = X[t, 64];

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RES0
RES0																															EN

AMUSERENR_EL0, Activity Monitors User Enable Register

Purpose