From: Alexander Potapenko <glider@xxxxxxxxxx> Subject: lib/stackdepot.c: use a non-instrumented version of memcmp() 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@xxxxxxxxxx Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- lib/stackdepot.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff -puN lib/stackdepot.c~lib-stackdepot-use-a-non-instrumented-version-of-memcmp lib/stackdepot.c --- a/lib/stackdepot.c~lib-stackdepot-use-a-non-instrumented-version-of-memcmp +++ a/lib/stackdepot.c @@ -163,6 +163,21 @@ static inline u32 hash_stack(unsigned lo 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_ 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; } _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
