On Fri Oct 18 15:14:42 2024 +0000, Arnd Bergmann wrote:
> With KASAN enabled, clang fails to optimize the inline version of
> vdec_vp9_slice_map_counts_eob_coef() properly, leading to kilobytes
> of temporary values spilled to the stack:
>
> drivers/media/platform/mediatek/vcodec/decoder/vdec/vdec_vp9_req_lat_if.c:1526:12:
> error: stack frame size (2160) exceeds limit (2048) in
> 'vdec_vp9_slice_update_prob' [-Werror,-Wframe-larger-than]
>
> This seems to affect all versions of clang including the latest (clang-20),
> but the degree of stack overhead is different per release.
>
> Marking the function as noinline_for_stack is harmless here and avoids
> the problem completely.
>
> Signed-off-by: Arnd Bergmann <a...@arndb.de>
> Reviewed-by: Nathan Chancellor <nat...@kernel.org>
> Signed-off-by: Sebastian Fricke <sebastian.fri...@collabora.com>
> Signed-off-by: Mauro Carvalho Chehab <mchehab+hua...@kernel.org>
Patch committed.
Thanks,
Mauro Carvalho Chehab
.../media/platform/mediatek/vcodec/decoder/vdec/vdec_vp9_req_lat_if.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git
a/drivers/media/platform/mediatek/vcodec/decoder/vdec/vdec_vp9_req_lat_if.c
b/drivers/media/platform/mediatek/vcodec/decoder/vdec/vdec_vp9_req_lat_if.c
index eea709d93820..47c302745c1d 100644
--- a/drivers/media/platform/mediatek/vcodec/decoder/vdec/vdec_vp9_req_lat_if.c
+++ b/drivers/media/platform/mediatek/vcodec/decoder/vdec/vdec_vp9_req_lat_if.c
@@ -1188,7 +1188,8 @@ err:
return ret;
}
-static
+/* clang stack usage explodes if this is inlined */
+static noinline_for_stack
void vdec_vp9_slice_map_counts_eob_coef(unsigned int i, unsigned int j,
unsigned int k,
struct vdec_vp9_slice_frame_counts
*counts,
struct v4l2_vp9_frame_symbol_counts
*counts_helper)
