kasan: apply write-only mode in kasan kunit testcases

kasan: apply write-only mode in kasan kunit testcases

When KASAN is configured in write-only mode, fetch/load operations do not
trigger tag check faults.

As a result, the outcome of some test cases may differ compared to when
KASAN is configured without write-only mode.

Therefore, by modifying pre-exist testcases check the write only makes tag
check fault (TCF) where writing is perform in "allocated memory" but tag
is invalid (i.e) redzone write in atomic_set() testcases.  Otherwise check
the invalid fetch/read doesn't generate TCF.

Also, skip some testcases affected by initial value (i.e) atomic_cmpxchg()
testcase maybe successd if it passes valid atomic_t address and invalid
oldaval address.  In this case, if invalid atomic_t doesn't have the same
oldval, it won't trigger write operation so the test will pass.

Link: https://lkml.kernel.org/r/20250916222755.466009-3-yeoreum.yun@arm.com
Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Reviewed-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Breno Leitao <leitao@debian.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: D Scott Phillips <scott@os.amperecomputing.com>
Cc: Hardevsinh Palaniya <hardevsinh.palaniya@siliconsignals.io>
Cc: James Morse <james.morse@arm.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Cc: Pankaj Gupta <pankaj.gupta@amd.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>