[Mesa-dev] [PATCH v2] nvc0/ir: clamp the UBO index for compute on Kepler

[Ilia Mirkin]

On Mon, Jun 13, 2016 at 11:13 AM, Samuel Pitoiset
<samuel.pitoiset at gmail.com> wrote:
> We already check that the address is not "too far", but we should also
> clamp the UBO index in order to avoid looking at the wrong place in the
> driver cb. This is a pretty rare situation though.
>
> v2: clamp the file index too
>
> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
> Cc: "12.0" <mesa-stable at lists.freedesktop.org>
> ---
>  src/gallium/drivers/nouveau/codegen/nv50_ir_lowering_nvc0.cpp | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/src/gallium/drivers/nouveau/codegen/nv50_ir_lowering_nvc0.cpp b/src/gallium/drivers/nouveau/codegen/nv50_ir_lowering_nvc0.cpp
> index cb82216..52cb438 100644
> --- a/src/gallium/drivers/nouveau/codegen/nv50_ir_lowering_nvc0.cpp
> +++ b/src/gallium/drivers/nouveau/codegen/nv50_ir_lowering_nvc0.cpp
> @@ -2183,7 +2183,15 @@ NVC0LoweringPass::handleLDST(Instruction *i)
>           int8_t fileIndex = i->getSrc(0)->reg.fileIndex - 1;
>           Value *ind = i->getIndirect(0, 1);
>
> -         // TODO: clamp the offset to the maximum number of const buf.
> +         if (ind) {
> +            // Clamp the UBO index when an indirect access is used to avoid
> +            // loading information from the wrong place in the driver cb.
> +            ind = bld.mkOp2v(OP_MIN, TYPE_U32, ind,
> +                             bld.mkOp2v(OP_ADD, TYPE_U32, bld.getSSA(),
> +                                        bld.loadImm(NULL, fileIndex), ind),

Let's do the optimizer a favor and flip the order of these args - the
immediate should always be the second arg. The optimizer will do the
flip optionally, but might as well not make it work for it. With that
minor change,

Reviewed-by: Ilia Mirkin <imirkin at alum.mit.edu>

> +                             bld.loadImm(NULL, 12));
> +         }
> +
>           if (i->src(0).isIndirect(1)) {
>              Value *offset = bld.loadImm(NULL, i->getSrc(0)->reg.data.offset + typeSizeof(i->sType));
>              Value *ptr = loadUboInfo64(ind, fileIndex * 16);
> --
> 2.8.3
>
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