From 1db37ebecf5af55215ace3801f8dbb8b10c5305e Mon Sep 17 00:00:00 2001 From: Kenneth Graunke Date: Thu, 9 Jun 2016 18:13:26 -0700 Subject: [PATCH] i965: Assert that the scratch spaces are in range. I don't know that anything actually guarantees this, but if we exceed the limits, we may end up overflowing and trashing random buffers that happen to be nearby in the VMA space, leading to rendering corruption, hangs, or worse. We should really fix this properly. However, the pitfall has existed for ages, so for now we should at least detect it. Cc: "12.0" Signed-off-by: Kenneth Graunke Reviewed-by: Francisco Jerez Reviewed-by: Jordan Justen --- src/mesa/drivers/dri/i965/brw_fs.cpp | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp index f1a1c87be5a..104c20b3549 100644 --- a/src/mesa/drivers/dri/i965/brw_fs.cpp +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp @@ -6001,7 +6001,21 @@ fs_visitor::allocate_registers(bool allow_spilling) * size linearly with a range of [1kB, 12kB] and 1kB granularity. */ prog_data->total_scratch = ALIGN(last_scratch, 1024); + + assert(prog_data->total_scratch < 12 * 1024); } + + /* We currently only support up to 2MB of scratch space. If we + * need to support more eventually, the documentation suggests + * that we could allocate a larger buffer, and partition it out + * ourselves. We'd just have to undo the hardware's address + * calculation by subtracting (FFTID * Per Thread Scratch Space) + * and then add FFTID * (Larger Per Thread Scratch Space). + * + * See 3D-Media-GPGPU Engine > Media GPGPU Pipeline > + * Thread Group Tracking > Local Memory/Scratch Space. + */ + assert(prog_data->total_scratch < 2 * 1024 * 1024); } } -- 2.30.2