From 26ee6f23a9aec6b1f392baa0e3f1f2c62c038a57 Mon Sep 17 00:00:00 2001 From: Kenneth Graunke Date: Sun, 14 Sep 2014 22:38:14 -0700 Subject: mesa: Delete VAO _MaxElement code and index buffer bounds checking. Fredrik's implementation of ARB_vertex_attrib_binding introduced new gl_vertex_attrib_array and gl_vertex_buffer_binding structures, and converted Mesa's older gl_client_array to be derived state. Ultimately, we'd like to drop gl_client_array and use those structures directly. One hitch is that gl_client_array::_MaxElement doesn't correspond to either structure (unlike every other field), so we'd have to figure out where to store it. The _MaxElement computation uses values from both structures, so it doesn't really belong in either place. We could put it in the VAO, but we'd have to pass it around everywhere. It turns out that it's only used when ctx->Const.CheckArrayBounds is set, which is only set by the (rarely used) classic swrast driver. It appears that drivers/x11 used to set it as well, which was intended to avoid segmentation faults on out-of-bounds memory access in the X server (probably for indirect GLX clients). However, ajax deleted that code in 2010 (commit 1ccef926be46dce3b6b5c76e812e2fae4e205ce7). The bounds checking apparently doesn't actually work, either. Non-VBO attributes arbitrarily set _MaxElement to 2 * 1000 * 1000 * 1000. vbo_save_draw and vbo_exec_draw remark /* ??? */ when setting it, and the i965 code contains a comment noting that _MaxElement is often bogus. Given that the code is complex, rarely used, and dubiously functional, it doesn't seem worth maintaining going forward. This patch drops it. This will probably mean the classic swrast driver may begin crashing on out of bounds vertex buffer access in some cases, but I believe that is allowed by OpenGL (and probably happened for non-VBO accesses anyway). There do not appear to be any Piglit regressions, either. Signed-off-by: Kenneth Graunke Reviewed-by: Brian Paul Reviewed-by: Eric Anholt Acked-by: Roland Scheidegger --- src/mesa/drivers/dri/i965/brw_draw_upload.c | 5 +---- src/mesa/drivers/dri/swrast/swrast.c | 3 --- 2 files changed, 1 insertion(+), 7 deletions(-) (limited to 'src/mesa/drivers/dri') diff --git a/src/mesa/drivers/dri/i965/brw_draw_upload.c b/src/mesa/drivers/dri/i965/brw_draw_upload.c index 2162624cede..5a12439e8f3 100644 --- a/src/mesa/drivers/dri/i965/brw_draw_upload.c +++ b/src/mesa/drivers/dri/i965/brw_draw_upload.c @@ -502,10 +502,7 @@ brw_prepare_vertices(struct brw_context *brw) /* This is a common place to reach if the user mistakenly supplies * a pointer in place of a VBO offset. If we just let it go through, * we may end up dereferencing a pointer beyond the bounds of the - * GTT. We would hope that the VBO's max_index would save us, but - * Mesa appears to hand us min/max values not clipped to the - * array object's _MaxElement, and _MaxElement frequently appears - * to be wrong anyway. + * GTT. * * The VBO spec allows application termination in this case, and it's * probably a service to the poor programmer to do so rather than diff --git a/src/mesa/drivers/dri/swrast/swrast.c b/src/mesa/drivers/dri/swrast/swrast.c index e28991b0cb6..e8a2c12d71c 100644 --- a/src/mesa/drivers/dri/swrast/swrast.c +++ b/src/mesa/drivers/dri/swrast/swrast.c @@ -772,9 +772,6 @@ dri_create_context(gl_api api, driContextSetFlags(mesaCtx, flags); - /* do bounds checking to prevent segfaults and server crashes! */ - mesaCtx->Const.CheckArrayBounds = GL_TRUE; - /* create module contexts */ _swrast_CreateContext( mesaCtx ); _vbo_CreateContext( mesaCtx ); -- cgit v1.2.3