[PATCH v2] drm/amdgpu: Fix UBSAN shift-out-of-bounds for gfx v9_0

[Candice Li]

Check shift number to avoid doing a shift operation when the number
of bits shifted equal to or greater than number of bits in the operand.

v2: Only calculate shift number for non-zero data and fix build warning.

Signed-off-by: Candice Li <candice.li at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
index 7f187558220e9a..c398c21d906069 100644
--- a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
@@ -2495,6 +2495,7 @@ static void gfx_v9_0_setup_rb(struct amdgpu_device *adev)
 {
 	int i, j;
 	u32 data;
+	int shift_num = 0;
 	u32 active_rbs = 0;
 	u32 rb_bitmap_width_per_sh = adev->gfx.config.max_backends_per_se /
 					adev->gfx.config.max_sh_per_se;
@@ -2504,8 +2505,11 @@ static void gfx_v9_0_setup_rb(struct amdgpu_device *adev)
 		for (j = 0; j < adev->gfx.config.max_sh_per_se; j++) {
 			gfx_v9_0_select_se_sh(adev, i, j, 0xffffffff);
 			data = gfx_v9_0_get_rb_active_bitmap(adev);
-			active_rbs |= data << ((i * adev->gfx.config.max_sh_per_se + j) *
-					       rb_bitmap_width_per_sh);
+			if (data) {
+				shift_num = MIN(((i * adev->gfx.config.max_sh_per_se + j) *
+						  rb_bitmap_width_per_sh), __builtin_clz(data));
+				active_rbs |= data << shift_num;
+			}
 		}
 	}
 	gfx_v9_0_select_se_sh(adev, 0xffffffff, 0xffffffff, 0xffffffff);
-- 
2.17.1