FROMGIT: kasan: speed up mte_set_mem_tag_range

Use DC GVA / DC GZVA to speed up KASan memory tagging in HW tags mode.

The first cacheline is always tagged using STG/STZG even if the address is
cacheline-aligned, as benchmarks show it is faster than a conditional
branch.

Signed-off-by: Evgenii Stepanov <eugenis@google.com>
Co-developed-by: Peter Collingbourne <pcc@google.com>
Signed-off-by: Peter Collingbourne <pcc@google.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210521010023.3244784-1-eugenis@google.com


Signed-off-by: Will Deacon <will@kernel.org>

Bug: 186467733
Test: Treehugger
(cherry picked from commit 3d0cca0b
 https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git

 for-next/mte)
Signed-off-by: Evgenii Stepanov <eugenis@google.com>
Change-Id: I17dd9d163aed53e4b5fe97ac6610dfdea20cf000