arm64: entry: sdei: Restore all clobberable GPRs

Currently __sdei_asm_handler() avoids restoring x20 to x27, as these are
not be clobbered by existing code. This is correct today, but it makes
it awkward to rework __sdei_asm_handler(). Given the rarity of SDEI
events, restoring x20 to x27 should not have a measurable impact.

Restore x20 to x27 when returning from an SDEI event handler. This will
free up those GPRs for usage in __sdei_asm_handler() prior to return.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Muhammad Usama Anjum <usama.anjum@arm.com>
Cc: Ada Couprie Diaz <ada.coupriediaz@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Jinjie Ruan <ruanjinjie@huawei.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Vladimir Murzin <vladimir.murzin@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

0 files changed, 0 insertions, 0 deletions