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3.2.39. c6, Instruction Fault Address Register

The purpose of the Instruction Fault Address Register (IFAR) is to hold the address of instructions that cause a prefetch abort.

The IFAR is:

  • a read/write register banked for Secure and Nonsecure states

  • accessible in privileged modes only.

The Instruction Fault Address Register bits [31:1] contain the instruction fault MVA and bit [0] is RAZ.

Table 3.72 shows the results of attempted access for each mode.

Results of access to the Instruction Fault Address RegisterAn entry of Undefined in the table means that the access gives an Undefined Instruction exception when the coprocessor instruction is executed.
Secure privilegedNonsecure privilegedSecure User Nonsecure User
Secure dataSecure dataNonsecure dataNonsecure dataUndefinedUndefinedUndefinedUndefined

To access the IFAR, read or write CP15 with:

MRC p15, 0, <Rd>, c6, c0, 2 ; Read Instruction Fault Address Register
MCR p15, 0, <Rd>, c6, c0, 2 ; Write Instruction Fault Address Register

A write to this register sets the IFAR to the value of the data written. This is useful for a debugger to restore the value of the IFAR.