System Control
ARM DDI 0500D
Copyright © 2013-2014 ARM. All rights reserved.
4-54
ID021414
Non-Confidential
[9]
UMA
User Mask Access. Controls access to interrupt masks from EL0, when EL0 is using AArch64. The possible
values of this bit are:
0
Disable access to the interrupt masks from EL0.
1
Enable access to the interrupt masks from EL0.
[8]
SED
SETEND instruction disable. The possible values are:
0
The SETEND instruction is enabled. This is the reset value.
1
The SETEND instruction is
UNDEFINED
.
[7]
ITD
IT instruction disable. The possible values are:
0
The IT instruction functionality is enabled. This is the reset value.
1
All encodings of the IT instruction with hw1[3:0]!=1000 are
UNDEFINED
and treated as
unallocated.All encodings of the subsequent instruction with the following values for hw1 are
UNDEFINED
(and treated as unallocated):
11xxxxxxxxxxxxxx
All 32-bit instructions, B(2), B(1), Undefined, SVC, Load/Store multiple
1x11xxxxxxxxxxxx
Miscellaneous 16-bit instructions
1x100xxxxxxxxxxx
ADD Rd, PC, #imm
01001xxxxxxxxxxx
LDR Rd, [PC, #imm]
0100x1xxx1111xxx
ADD(4),CMP(3), MOV, BX pc, BLX pc
010001xx1xxxx111
ADD(4),CMP(3), MOV
Contrary to the standard treatment of conditional
UNDEFINED
instructions in the ARM
architecture, in this case these instructions are always treated as
UNDEFINED
, regardless of
whether the instruction would pass or fail its condition codes as a result of being in an IT block.
[6]
THEE
RES
0
T32EE is not implemented.
[5]
CP15BEN
CP15 barrier enable. The possible values are:
0
CP15 barrier operations disabled. Their encodings are
UNDEFINED
.
1
CP15 barrier operations enabled. This is the reset value.
[4]
SA0
Enable EL0 stack alignment check. The possible values are:
0
Disable EL0 stack alignment check.
1
Enable EL0 stack alignment check. This is the reset value.
[3]
SA
Enable SP alignment check. The possible values are:
0
Disable SP alignment check.
1
Enable SP alignment check. This is the reset value.
[2]
C
Cache enable. The possible values are:
0
Data and unified caches disabled. This is the reset value.
1
Data and unified caches enabled.
[1]
A
Alignment check enable. The possible values are:
0
Alignment fault checking disabled. This is the reset value.
1
Alignment fault checking enabled.
Table 4-67 SCTLR_EL1 bit assignments (continued)
Bits
Name
Function