arm64/cpufeatures: Emulate MRS instructions by parsing ESR_ELx.ISS

Armv8.4-A extension enables MRS instruction encodings inside ESR_ELx.ISS
during exception class ESR_ELx_EC_SYS64 (0x18). This encoding can be used
to emulate MRS instructions which can avoid fetch/decode from user space
thus improving performance. This adds a new sys64_hook structure element
with applicable ESR mask/value pair for MRS instructions on various system
registers but constrained by sysreg encodings which is currently allowed
to be emulated.

Reviewed-by: Suzuki K Poulose <[email protected]>
Acked-by: Mark Rutland <[email protected]>
Signed-off-by: Anshuman Khandual <[email protected]>
Signed-off-by: Catalin Marinas <[email protected]>

0 files changed, 0 insertions, 0 deletions