arm64/sve: Make kernel FPU protection RT friendly

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Non RT kernels need to protect FPU against preemption and bottom half
processing. This is achieved by disabling bottom halves via
local_bh_disable() which implictly disables preemption.

On RT kernels this protection mechanism is not sufficient because
local_bh_disable() does not disable preemption. It serializes bottom half
related processing via a CPU local lock.

As bottom halves are running always in thread context on RT kernels
disabling preemption is the proper choice as it implicitly prevents bottom
half processing.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220505163207.85751-3-bigeasy@linutronix.de
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

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Sebastian Andrzej Siewior 2022-05-05 18:32:06 +02:00 • committed by Catalin Marinas

parent a1259dd807

commit 696207d425

1 changed files with 14 additions and 2 deletions

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arch/arm64/kernel/fpsimd.c

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