You copied the Doc URL to your clipboard.

Architectural Feature Trap Register, EL3

The CPTR_EL3 characteristics are:

Purpose

Controls trapping to EL3 for accesses to CPACR, Trace functionality and registers associated with Advanced SIMD and Floating-point execution. Controls EL3 access to this functionality.

CPTR_EL3 is part of the Security registers functional group.

Usage constraints

This register is accessible as follows:

EL0

EL1

(NS)

EL1

(S)

EL2

EL3

(SCR.NS = 1)

EL3

(SCR.NS = 0)

- - - - RW RW
Configurations

There are no configuration notes.

Attributes

CPTR_EL3 is a 32-bit register.

Figure 4.42 shows the CPTR_EL3 bit assignments.

To view this graphic, your browser must support the SVG format. Either install a browser with native support, or install an appropriate plugin such as Adobe SVG Viewer.


Table 4.86 shows the CPTR_EL3 bit assignments.

Table 4.86.  CPTR_EL3 bit assignments
Bits Name Function
[31] TCPAC

This causes a direct access to the CPACR_EL1 from EL1 or the CPTR_EL2 from EL2 to trap to EL3 unless it is trapped at EL2. The possible values are:

0

Does not cause access to the CPACR_EL1 or CPTR_EL2 to be trapped.

1

Causes access to the CPACR_EL1 or CPTR_EL2 to be trapped.

[30:21] -

Reserved, res0.

[20] TTA

Trap Trace Access.

Not implemented. res0.

[19:14] -

Reserved, res0.

[13:12] - Reserved, res1.
[11] -

Reserved, res0.

[10] TFP

This causes instructions that access the registers associated with Advanced SIMD or floating-point execution to trap to EL3 when executed from any exception level, unless trapped to EL1 or EL2. The possible values are:

0

Does not cause any instruction to be trapped.This is the reset value if the Advanced SIMD and Floating-point Extension is not implemented.

1

Causes any instructions that use the registers associated with Advanced SIMD or floating-point execution to be trapped. This is always the value if the Advanced SIMD and Floating-point Extension is not implemented.

[9:0] -

Reserved, res1.


To access the CPTR_EL3:

	
MRS <Xt>, CPTR_EL3 ; Read CPTR_EL3 into Xt
MSR CPTR_EL3, <Xt> ; Write Xt to CPTR_EL3
Was this page helpful? Yes No