arm64: add MTE supported check to thread switching and syscall entry/exit

This lets us avoid doing unnecessary work on hardware that does not
support MTE, and will allow us to freely use MTE instructions in the
code called by mte_thread_switch().

Since this would mean that we do a redundant check in
mte_check_tfsr_el1(), remove it and add two checks now required in its
callers. This also avoids an unnecessary DSB+ISB sequence on the syscall
exit path for hardware not supporting MTE.

Fixes: 65812c6921cc ("arm64: mte: Enable async tag check fault")
Cc: <[email protected]> # 5.13.x
Signed-off-by: Peter Collingbourne <[email protected]>
Link: https://linux-review.googlesource.com/id/I02fd000d1ef2c86c7d2952a7f099b254ec227a5d
Link: https://lore.kernel.org/r/[email protected]
[[email protected]: adjust the commit log slightly]
Signed-off-by: Catalin Marinas <[email protected]>

0 files changed, 0 insertions, 0 deletions