mirror of
https://gitlab.freedesktop.org/mesa/mesa.git
synced 2026-05-19 00:38:06 +02:00
252904f3d1
The DDMADT instruction of PDS has out-of-bound test capability, which is
used for implementation of robust vertex input fetch.
According to the pseudocode in the comment block before the "LAST DDMAD"
mark in pvr_pipeline_pds.c, the check is between
`calculated_source_address + (burst_size << 2)` and `base_address +
buffer_size`, in which the `burst_size` seems to correspond to the BSIZE
field set in the low 32-bit of DDMAD(T) src3 and the `buffer_size`
corresponds to the MSIZE field set in the DDMADT-specific high 32-bit of
src3. As the calculated source address is just the base address adds the
multiplication result (the offset), the base address could be eliminated
from the check, results in the check between `offset + (BSIZE * 4)` and
`MSIZE` .
Naturally it's expected to just set the MSIZE field to the buffer size.
In addition, as the Vulkan spec says "Reads from a vertex input MAY
instead be bounds checked against a range rounded down to the nearest
multiple of the stride of its binding", the driver rounds down the
accessible buffer size before setting MSIZE to it.
However when running OpenGL ES 2.0 CTS, two problems are exhibited about
the setting of the size to check:
- dEQP-GLES2.functional.buffer.write.basic.array_stream_draw sets up a
VBO with 3 bytes per vertex (RGB colors and 1B per color) and 340
vertices (results in a buffer size of 1020 = 0x3fc). However as the
DMA request size, which is specified by BSIZE, is counted by dwords,
3 bytes are rounded up to 1 dword (which is 4 bytes). When the bound
check of the last vertex happens, the vertex's DMA start offset is
0x3f9, so the DDMADT check happens between 0x3fd (0x3f9 + 1 * 4) and
0x3fc, and indicates a check failure. This prevents the last vertex,
which is perfectly in-bound, from being properly fetched; this is
against the Vulkan specification, and needs to be fixed.
- dEQP-GLES2.functional.vertex_arrays.single_attribute.strides.
buffer_0_32_float2_vec4_dynamic_draw_quads_1 sets up a VBO with a size
of 168 bytes, and tries to draw 6 vertices (each vertex consumes 2
floats (thus 8 bytes) of attribute) with a stride of 32 bytes using
this VBO. Zink then translates the VBO to a Vulkan vertex buffer bound
with size = 168B, stride = 32B. Here the optional rule about rounding
down buffer size happens in the current PowerVR driver, and the
checked bound is rounded down to 160B, which prevented the last
vertex's 8B attributes to be fetched. It looks like this kind of
situation is considered in the codepath without DDMADT, but omitted
for the codepath utilizing DDMADT for bound check.
So this patch tries to mimic the behavior of DDMADT when setting the
MSIZE field of it to prevent false out-of-bounds. It first calculates
the offset of the last valid vertex DMA, then adds the DMA request size
to it to form the final MSIZE value. With the code calculating the last
valid DMA offset considering the situation of fetching the attribute
from the space after the last whole multiple of stride, both problems
mentioned above are solved by this rework.
There're 99 GLES CTS testcases fixed by this change, and Vulkan CTS
shows no regression on `dEQP-VK.robustness.robustness1_vertex_access.*`
tests.
Fixes:
|
||
|---|---|---|
| .. | ||
| ci | ||
| common | ||
| csbgen | ||
| drm-shim | ||
| include | ||
| pco | ||
| vulkan | ||
| .clang-format | ||
| .dir-locals.el | ||
| .editorconfig | ||
| meson.build | ||