linux-kernel - [PATCH mm 11/11] kasan: speed up match_all_mem_tag test for SW

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Date: Thu, 21 Dec 2023 21:04:53 +0100
From: andrey.konovalov@...ux.dev
To: Marco Elver <elver@...gle.com>
Cc: Andrey Konovalov <andreyknvl@...il.com>,
	Alexander Potapenko <glider@...gle.com>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Andrey Ryabinin <ryabinin.a.a@...il.com>,
	kasan-dev@...glegroups.com,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH mm 11/11] kasan: speed up match_all_mem_tag test for SW_TAGS

From: Andrey Konovalov <andreyknvl@...gle.com>

Checking all 256 possible tag values in the match_all_mem_tag KASAN test
is slow and produces 256 reports. Instead, just check the first 8 and the
last 8.

Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
---
 mm/kasan/kasan_test.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/mm/kasan/kasan_test.c b/mm/kasan/kasan_test.c
index 798df4983858..9c3a1aaab21b 100644
--- a/mm/kasan/kasan_test.c
+++ b/mm/kasan/kasan_test.c
@@ -1785,6 +1785,14 @@ static void match_all_mem_tag(struct kunit *test)
 
 	/* For each possible tag value not matching the pointer tag. */
 	for (tag = KASAN_TAG_MIN; tag <= KASAN_TAG_KERNEL; tag++) {
+		/*
+		 * For Software Tag-Based KASAN, skip the majority of tag
+		 * values to avoid the test printing too many reports.
+		 */
+		if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) &&
+		    tag >= KASAN_TAG_MIN + 8 && tag <= KASAN_TAG_KERNEL - 8)
+			continue;
+
 		if (tag == get_tag(ptr))
 			continue;
 
-- 
2.25.1