PMSSCR

Holds status information about the captured counters and provides a mechanism for software to initiate a sample.

Configuration

AArch64 System register PMSSCR_EL1 bits [63:0] are architecturally mapped to External register PMU.PMSSCR_EL1[63:0].

This register is present only when FEAT_PMUv3_SS is implemented. Otherwise, direct accesses to PMSSCR_EL1 are UNDEFINED.

Attributes

Field descriptions

Bits [63:33]

NC, bit [32]

No Capture. Indicates whether the PMU counters have been captured.

NC	Meaning
0b0	PMU counters captured.
0b1	PMU counters not captured.

The reset behavior of this field is:

On a Warm reset, this field resets to 1.

Bits [31:1]

SS, bit [0]

Snapshot Capture and Status.

SS	Meaning
0b0	On a read, the Capture event has completed.
0b1	On a read, the Capture event has not completed. On a write, request a Capture event.

Meaning

0b0

On a read, the Capture event has completed.

0b1

On a read, the Capture event has not completed.

On a write, request a Capture event.

A write of 0 to this field is ignored.

It is CONSTRAINED UNPREDICTABLE whether a Capture event has completed if this field is modified when the Capture event is ongoing.

The reset behavior of this field is:

On a Warm reset, this field resets to 0.

Accessing this field has the following behavior:

When PMU capture events are disabled, access to this field is RO.
Otherwise, access to this field is RW.

Accessing PMSSCR_EL1

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

MRS <Xt>, PMSSCR_EL1

op0	op1	CRn	CRm	op2
0b11	0b000	0b1001	0b1101	0b011

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.EnPMSS == '0' then UNDEFINED; elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT2) && ((HaveEL(EL3) && SCR_EL3.FGTEn2 == '0') || HDFGRTR2_EL2.nPMSSCR_EL1 == '0') then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && MDCR_EL3.EnPMSS == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else X[t, 64] = PMSSCR_EL1; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.EnPMSS == '0' then UNDEFINED; elsif HaveEL(EL3) && MDCR_EL3.EnPMSS == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else X[t, 64] = PMSSCR_EL1; elsif PSTATE.EL == EL3 then X[t, 64] = PMSSCR_EL1;

MSR PMSSCR_EL1, <Xt>

op0	op1	CRn	CRm	op2
0b11	0b000	0b1001	0b1101	0b011

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.EnPMSS == '0' then UNDEFINED; elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT2) && ((HaveEL(EL3) && SCR_EL3.FGTEn2 == '0') || HDFGWTR2_EL2.nPMSSCR_EL1 == '0') then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && MDCR_EL3.EnPMSS == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else PMSSCR_EL1 = X[t, 64]; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.EnPMSS == '0' then UNDEFINED; elsif HaveEL(EL3) && MDCR_EL3.EnPMSS == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else PMSSCR_EL1 = X[t, 64]; elsif PSTATE.EL == EL3 then PMSSCR_EL1 = X[t, 64];

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																															NC
RES0																															SS

PMSSCR_EL1, Performance Monitors Snapshot Status and Capture Register

Purpose