ARM ARM1176JZF-S Technical Reference Manual page 214

ARM DDI 0301H
ID012310
For all other cases when the VA to PA operation fails, the processor only updates the PA register,
Secure or Non-secure version, depending on the Secure or Non-secure state of the core when
the operation was issued, with the Fault Status Register encoding and bit[0] set. The Data Fault
Status Register and Fault Address Register remain unchanged and the processor does not send
an abort to the core.
To use the PA Register read or write CP15 c7 with:
• Opcode_1 set to 0
• CRn set to c7
• CRm set to c4
• Opcode_2 set to 0.
For example:
MRC p15, 0, <Rd>, c7, c4, 0
MCR p15, 0, <Rd>, c7, c4, 0
VA to PA translation in the current world
The purpose of the VA to PA translation in the current world is to translate the address with the
current virtual mapping for either Secure or Non-secure worlds.
The VA to PA translation in the current world operations use:
• CP15 c7
• four, 32-bit write-only operations common to the Secure and Non-secure worlds
• operations accessible in privileged modes only
The operations work for privileged or User access permissions and returns information in the
PA Register for aborts, when the translation is unsuccessful, or page table information, when the
translation succeeds.
Attempts to access the VA to PA translation operations in the current world in User mode result
in an Undefined exception.
To use the VA to PA translation in the current world write CP15 c7 with:
• Opcode_1 set to 0
• CRn set to c7
• CRm set to c8
• Opcode_2 set to:
— 0 for privileged read permission
— 1 for privileged write permission
— 2 for User read permission
— 3 for User write permission.
General register <Rn> contains the VA for translation. The result returns in the PA Register, for
example:
MCR p15,0,<Rn>,c7,c8,3
MRC p15,0,<Rd>,c7,c4,0
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; Read PA Register
; Write PA Register
;get VA = <Rn> and run VA-to-PA translation
;with User write permission.
;if the selected page table has the
;User write permission, the PA is loaded
;in PA register, otherwise abort information is
;loaded in PA Register
;read in <Rd> the PA value
System Control Coprocessor
3-82