System Control
ARM DDI 0500D
Copyright © 2013-2014 ARM. All rights reserved.
4-70
ID021414
Non-Confidential
Figure 4-35 CPTR_EL2 bit assignments
Table 4-74
shows the CPTR_EL2 bit assignments.
To access the CPTR_EL2:
MRS <Xt>, CPTR_EL2 ; Read CPTR_EL2 into Xt
MSR CPTR_EL2, <Xt> ; Write Xt to CPTR_EL2
4.3.39
Hyp System Trap Register
The HSTR_EL2 characteristics are:
Purpose
Controls access to ThumbEE and coprocessor registers at lower exception
levels in AArch32.
Usage constraints
This register is accessible as follows:
Configurations
HSTR_EL2 is architecturally mapped to AArch32 register HSTR. See
Hyp System Trap Register
on page 4-236
.
31
0
RES
0
RES
1
TFP
TCPAC
20 19
21
10 9
11
RES
0
TTA
13 12
14
RES
1
RES
0
30
Table 4-74 CPTR_EL2 bit assignments
Bits
Name
Function
[31]
TCPAC
Traps direct access to CPACR from Non-secure EL1 to EL2. The possible values are:
0
Access to CPACR is not trapped. This is the reset value.
1
Access to CPACR is trapped.
[30:21]
-
Reserved,
RES
0.
[20]
TTA
Trap Trace Access.
Not implemented.
RES
0.
[19:14]
-
Reserved,
RES
0.
[13:12]
-
Reserved,
RES
1.
[11]
-
Reserved,
RES
0.
[10]
TFP
Traps instructions that access registers associated with Advanced SIMD and Floating-point execution from a
lower exception level to EL2, unless trapped to EL1. The possible values are:
0
Instructions are not trapped. This is the reset value if Advanced SIMD and Floating-point are
implemented.
1
Instructions are trapped. This is always the value if Advanced SIMD and Floating-point are not
implemented.
[9:0]
-
Reserved,
RES
1.
EL0
EL1
(NS)
EL1
(S)
EL2
EL3
(SCR.NS = 1)
EL3
(SCR.NS = 0)
-
-
-
RW
RW
RW