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

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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 <suzuki.poulose@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

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Anshuman Khandual 2018-09-20 09:36:21 +05:30 • committed by Catalin Marinas

parent 520ad98871

commit 21f8479617

2 changed files with 29 additions and 0 deletions

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12

arch/arm64/include/asm/esr.h

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17

arch/arm64/kernel/traps.c

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