On Sun, Jan 28, 2024 at 02:12:22AM +0000, Ricardo Ribalda wrote: > Building with LLVM=1 throws the following warning: > drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c:38:32: warning: cast from 'mtk_vcodec_ipi_handler' (aka 'void (*)(void *, unsigned int, void *)') to 'ipi_handler_t' (aka 'void (*)(const void *, unsigned int, void *)') converts to incompatible function type [-Wcast-function-type-strict] > > Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx> I am not positive because I don't have any hardware to test this driver but I suspect this patch is just hiding the warning without actually addressing the issue that it is pointing out. If handler is called through vpu_ipi_register() indirectly (which it obviously is if it is being passed down), there will be a CFI failure because the type of mtk_vcodec_ipi_handler is not the same as ipi_handler_t, as the comment mentions. Has this seen testing on real hardware with kCFI? > --- > drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c b/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c > index 9f6e4b59455d..781a0359afdc 100644 > --- a/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c > +++ b/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c > @@ -33,9 +33,11 @@ static int mtk_vcodec_vpu_set_ipi_register(struct mtk_vcodec_fw *fw, int id, > * The handler we receive takes a void * as its first argument. We > * cannot change this because it needs to be passed down to the rproc > * subsystem when SCP is used. VPU takes a const argument, which is > - * more constrained, so the conversion below is safe. > + * more constrained, so the conversion below is safe. We use the void > + * casting, to convince clang with -Wcast-function-type-sctrict that > + * this is safe. > */ > - ipi_handler_t handler_const = (ipi_handler_t)handler; > + ipi_handler_t handler_const = (ipi_handler_t)((void *)handler); > > return vpu_ipi_register(fw->pdev, id, handler_const, name, priv); > } > > -- > 2.43.0.429.g432eaa2c6b-goog >
