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>
This isn't used yet, it's just a first step toward loop validation.
During the main parsing of instructions, we need to know when we hit a
new basic block so that we can reset validated state.
v2: Fix a stray semicolon after an if block. (caught by kbuild test).
Signed-off-by: Eric Anholt <eric@anholt.net>
Reduces the argument count for some of the functions, and will be used
more with the upcoming looping support.
Signed-off-by: Eric Anholt <eric@anholt.net>
Since we have no MMU, the kernel needs to validate that the submitted
shader code won't make any accesses to memory that the user doesn't
control, which involves banning some operations (general purpose DMA
writes), and tracking where we need to write out pointers for other
operations (texture sampling). Once it's validated, we return a GEM
BO containing the shader, which doesn't allow mapping for write or
exporting to other subsystems.
v2: Use __u32-style types.
Signed-off-by: Eric Anholt <eric@anholt.net>
