Clang may replace stackdepot_memcmp() with a call to instrumented bcmp(),
which is exactly what we wanted to avoid creating stackdepot_memcmp().
Add a compiler barrier() to prevent optimizations.
Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
To: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
---
Change-Id: I4495b617b15c0ab003a61c1f0d54d0026fa8b144
---
lib/stackdepot.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index 0d00d2ac0c4b..785839298e08 100644
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -163,6 +163,11 @@ int stackdepot_memcmp(const unsigned long *u1, const unsigned long *u2,
unsigned int n)
{
for ( ; n-- ; u1++, u2++) {
+ /*
+ * Prevent Clang from replacing this function with a bcmp()
+ * call.
+ */
+ barrier();
if (*u1 != *u2)
return 1;
}
--
2.23.0.866.gb869b98d4c-goog
