arm64: kasan: mte: move GCR_EL1 switch to task switch when KASAN disabled

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It is not necessary to write to GCR_EL1 on every kernel entry and
exit when HW tag-based KASAN is disabled because the kernel will not
execute any IRG instructions in that mode. Since accessing GCR_EL1
can be expensive on some microarchitectures, avoid doing so by moving
the access to task switch when HW tag-based KASAN is disabled.

Signed-off-by: Peter Collingbourne <pcc@google.com>
Acked-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://linux-review.googlesource.com/id/I78e90d60612a94c24344526f476ac4ff216e10d2
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210924010655.2886918-1-pcc@google.com
Signed-off-by: Will Deacon <will@kernel.org>

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Peter Collingbourne 2021-09-23 18:06:55 -07:00 • committed by Will Deacon

parent 5816b3e657

commit e5af50a5df

3 changed files with 38 additions and 7 deletions

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10

arch/arm64/kernel/entry.S

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26

arch/arm64/kernel/mte.c

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9

include/linux/kasan.h

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