arm64: vdso: Avoid ISB after reading from cntvct_el0

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commit 77ec462536 upstream.

We can avoid the expensive ISB instruction after reading the counter in
the vDSO gettime functions by creating a fake address hazard against a
dummy stack read, just like we do inside the kernel.

Signed-off-by: Will Deacon <will@kernel.org>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lore.kernel.org/r/20210318170738.7756-5-will@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Chanho Park <chanho61.park@samsung.com>

...

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Will Deacon 2021-03-18 17:07:37 +00:00 • committed by Greg Kroah-Hartman

parent 7a2b5bb00f

commit 37cbd27ef4

3 changed files with 20 additions and 26 deletions

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21

arch/arm64/include/asm/arch_timer.h

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19

arch/arm64/include/asm/barrier.h

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6

arch/arm64/include/asm/vdso/gettimeofday.h

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