arm64: mte: optimize GCR_EL1 modification on kernel entry/exit

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Accessing GCR_EL1 and issuing an ISB can be expensive on some
microarchitectures. Although we must write to GCR_EL1, we can
restructure the code to avoid reading from it because the new value
can be derived entirely from the exclusion mask, which is already in
a GPR. Do so.

Signed-off-by: Peter Collingbourne <pcc@google.com>
Link: https://linux-review.googlesource.com/id/I560a190a74176ca4cc5191dad08f77f6b1577c75
Link: https://lore.kernel.org/r/20210714013638.3995315-1-pcc@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

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Peter Collingbourne 2021-07-13 18:36:38 -07:00 • committed by Catalin Marinas

parent 80c7c36fb3

commit afdfd93a53

1 changed files with 4 additions and 8 deletions

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arch/arm64/kernel/entry.S

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