arm64: kasan: mte: remove redundant mte_report_once logic

We have special logic to suppress MTE tag check fault reporting, based
on a global `mte_report_once` and `reported` variables. These can be
used to suppress calling kasan_report() when taking a tag check fault,
but do not prevent taking the fault in the first place, nor does they
affect the way we disable tag checks upon taking a fault.

The core KASAN code already defaults to reporting a single fault, and
has a `multi_shot` control to permit reporting multiple faults. The only
place we transiently alter `mte_report_once` is in lib/test_kasan.c,
where we also the `multi_shot` state as the same time. Thus
`mte_report_once` and `reported` are redundant, and can be removed.

When a tag check fault is taken, tag checking will be disabled by
`do_tag_recovery` and must be explicitly re-enabled if desired. The test
code does this by calling kasan_enable_tagging_sync().

This patch removes the redundant mte_report_once() logic and associated
variables.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Will Deacon <will@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Tested-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20210714143843.56537-4-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 0 insertions, 2 deletions

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 8f7b0b2f6e11..8be9d4b3b259 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -53,7 +53,6 @@ static int kasan_test_init(struct kunit *test)
 	}
 
 	multishot = kasan_save_enable_multi_shot();
-	kasan_set_tagging_report_once(false);
 	fail_data.report_found = false;
 	kunit_add_named_resource(test, NULL, NULL, &resource,
 					"kasan_data", &fail_data);
@@ -62,7 +61,6 @@ static int kasan_test_init(struct kunit *test)
 
 static void kasan_test_exit(struct kunit *test)
 {
-	kasan_set_tagging_report_once(true);
 	kasan_restore_multi_shot(multishot);
 	KUNIT_EXPECT_FALSE(test, fail_data.report_found);
 }