[igt-dev] [PATCH i-g-t] lib/igt_dummyload: Fix undefined behavior in bitshift

[Zbigniew Kempczyński]

As a part of rewriting tests to use no-reloc I was a little bit
surprised addr calculation on my SKL box lead to some strange
offsets which finally use relocations instead. At first glance
I wasn't able to spot it, debugging reveals:

	if (addr >> 31)
		addr = 1 << 31;

gives addr == ffffffff80000000

what is not address we want to use as an argument to modulo.

Signed-off-by: Zbigniew Kempczyński <zbigniew.kempczynski at intel.com>
Cc: Petri Latvala <petri.latvala at intel.com>
Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
---
 lib/igt_dummyload.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/igt_dummyload.c b/lib/igt_dummyload.c
index 82459e524..fc55be15b 100644
--- a/lib/igt_dummyload.c
+++ b/lib/igt_dummyload.c
@@ -119,7 +119,7 @@ emit_recursive_batch(igt_spin_t *spin,
 	 */
 	addr = gem_aperture_size(fd) / 2;
 	if (addr >> 31)
-		addr = 1 << 31;
+		addr = 1ULL << 31;
 	addr += random() % addr / 2;
 	addr &= -4096;
 
-- 
2.26.0