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authorAlexander Potapenko <[email protected]>2018-02-06 15:38:24 -0800
committerLinus Torvalds <[email protected]>2018-02-06 18:32:44 -0800
commita571b272ab0f82399e8b2ede8c95d153d76a3534 (patch)
tree49405f84b2e7787235f1ddd1e4b3e9ed5d8779a1
parent334cfa48d38f5416c125a71a57f72d6cf634d797 (diff)
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/[email protected] Signed-off-by: Alexander Potapenko <[email protected]> Cc: Andrey Ryabinin <[email protected]> Cc: Dmitry Vyukov <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
-rw-r--r--lib/stackdepot.c19
1 files 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;
}