lib/stackdepot.c: use a non-instrumented version of memcmp() (a571b272) · Commits · 戴 / test

stackdepot used to call memcmp(), which compiler tools normally instrument, therefore every lookup used to unnecessarily call instrumented code. This is somewhat ok in the case of KASAN, but under KMSAN a lot of time was spent in the instrumentation. Link: http://lkml.kernel.org/r/20171117172149.69562-1-glider@google.com Signed-off-by:

Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Dmitry Vyukov <dvyukov@google.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

lib/stackdepot.c

+16 −3

Original line number	Diff line number	Diff line
		@@ -163,6 +163,21 @@ static inline u32 hash_stack(unsigned long *entries, unsigned int size)
		STACK_HASH_SEED);
		}

		/* Use our own, non-instrumented version of memcmp().
		*
		* We actually don't care about the order, just the equality.
		*/
		static inline
		int stackdepot_memcmp(const unsigned long u1, const unsigned long u2,
		unsigned int n)
		{
		for ( ; n-- ; u1++, u2++) {
		if (u1 != u2)
		return 1;
		}
		return 0;
		}

		/* Find a stack that is equal to the one stored in entries in the hash */
		static inline struct stack_record find_stack(struct stack_record bucket,
		unsigned long *entries, int size,
		@@ -173,11 +188,9 @@ static inline struct stack_record find_stack(struct stack_record bucket,
		for (found = bucket; found; found = found->next) {
		if (found->hash == hash &&
		found->size == size &&
		!memcmp(entries, found->entries,
		size * sizeof(unsigned long))) {
		!stackdepot_memcmp(entries, found->entries, size))
		return found;
		}
		}
		return NULL;
		}

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