drm/vc4: Add support for branching in shader validation.
authorEric Anholt <eric@anholt.net>
Sat, 2 Jul 2016 19:17:10 +0000 (12:17 -0700)
committerEric Anholt <eric@anholt.net>
Fri, 15 Jul 2016 22:19:50 +0000 (15:19 -0700)
commit6d45c81d229d71da54d374143e7d6abad4c0cf31
tree13a537d8fc387d061cdf2d28f0b6599a80aa3237
parent93aa9ae3e5523e49e4e5abacd4dbee0e4ab2d931
drm/vc4: Add support for branching in shader validation.

We're already checking that branch instructions are between the start
of the shader and the proper PROG_END sequence.  The other thing we
need to make branching safe is to verify that the shader doesn't read
past the end of the uniforms stream.

To do that, we require that at any basic block reading uniforms have
the following instructions:

load_imm temp, <next offset within uniform stream>
add unif_addr, temp, unif

The instructions are generated by userspace, and the kernel verifies
that the load_imm is of the expected offset, and that the add adds it
to a uniform.  We track which uniform in the stream that is, and at
draw call time fix up the uniform stream to have the address of the
start of the shader's uniforms at that location.

Signed-off-by: Eric Anholt <eric@anholt.net>
drivers/gpu/drm/vc4/vc4_drv.h
drivers/gpu/drm/vc4/vc4_qpu_defines.h
drivers/gpu/drm/vc4/vc4_validate.c
drivers/gpu/drm/vc4/vc4_validate_shaders.c