arm64: assembler: Switch ESB-instruction with a vanilla nop if !ARM64_HAS_RAS
The ESB-instruction is a nop on CPUs that don't implement the RAS extensions. This lets us use it in places like the vectors without having to use alternatives. If someone disables CONFIG_ARM64_RAS_EXTN, this instruction still has its RAS extensions behaviour, but we no longer read DISR_EL1 as this register does depend on alternatives. This could go wrong if we want to synchronize an SError from a KVM guest. On a CPU that has the RAS extensions, but the KConfig option was disabled, we consume the pending SError with no chance of ever reading it. Hide the ESB-instruction behind the CONFIG_ARM64_RAS_EXTN option, outputting a regular nop if the feature has been disabled. Reported-by:Julien Thierry <julien.thierry@arm.com> Signed-off-by:
James Morse <james.morse@arm.com> Signed-off-by:
Marc Zyngier <marc.zyngier@arm.com>
parent
4b972a01
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