From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759901AbdKQR03 (ORCPT ); Fri, 17 Nov 2017 12:26:29 -0500 Received: from mail-wm0-f68.google.com ([74.125.82.68]:41491 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752508AbdKQR0U (ORCPT ); Fri, 17 Nov 2017 12:26:20 -0500 X-Google-Smtp-Source: AGs4zMYuT/xM+fMFw3b2UF+BtfDv4bfcuZOsXkUdSfXD3iPxTwUE1BfHWlPHIk+a1eth28W2XxVBPQ== From: Alexander Potapenko To: aryabinin@virtuozzo.com, dvyukov@google.com, akpm@linux-foundation.org Cc: kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v2] lib/stackdepot: use a non-instrumented version of memcmp() Date: Fri, 17 Nov 2017 18:21:49 +0100 Message-Id: <20171117172149.69562-1-glider@google.com> X-Mailer: git-send-email 2.15.0.448.gf294e3d99a-goog Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Signed-off-by: Alexander Potapenko --- v2: As requested by Andrey Ryabinin, made the parameters unsigned long * --- lib/stackdepot.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index f87d138e9672..e513459a5601 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -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, @@ -173,10 +188,8 @@ 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; } -- 2.15.0.448.gf294e3d99a-goog