On Thu, 18 Dec 2014, Daniel Vetter <daniel@xxxxxxxx> wrote:
> On Thu, Dec 18, 2014 at 09:51:26AM -0800, Bob Paauwe wrote:
>> When creating a fence for a tiled object, only fence the area that
>> makes up the actual tiles. The object may be larger than the tiled
>> area and if we allow those extra addresses to be fenced, they'll
>> get converted to addresses beyond where the object is mapped. This
>> opens up the possiblity of writes beyond the end of object.
>>
>> To prevent this, we adjust the size of the fence to only encompass
>> the area that makes up the actual tiles. The extra space is considered
>> un-tiled and now behaves as if it was a linear object.
>>
>> Testcase: igt/gem_tiled_fence_overflow
>> Reported-by: Dan Hettena <danh@xxxxxxx>
>> Signed-off-by: Bob Paauwe <bob.j.paauwe@xxxxxxxxx>
>
> Presuming this indeed blows up (I didn't try your test) this is one for
> Jani.
>
> Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
Pushed to drm-intel-fixes, thanks for the patch and review.
BR,
Jani.
>
> Thanks, Daniel
>
>> ---
>> drivers/gpu/drm/i915/i915_gem.c | 7 +++++++
>> 1 file changed, 7 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
>> index 67550ac..c9acbfa 100644
>> --- a/drivers/gpu/drm/i915/i915_gem.c
>> +++ b/drivers/gpu/drm/i915/i915_gem.c
>> @@ -3173,6 +3173,13 @@ static void i965_write_fence_reg(struct drm_device *dev, int reg,
>> u32 size = i915_gem_obj_ggtt_size(obj);
>> uint64_t val;
>>
>> + /* Adjust fence size to match tiled area */
>> + if (obj->tiling_mode != I915_TILING_NONE) {
>> + uint32_t row_size = obj->stride *
>> + (obj->tiling_mode == I915_TILING_Y ? 32 : 8);
>> + size = (size / row_size) * row_size;
>> + }
>> +
>> val = (uint64_t)((i915_gem_obj_ggtt_offset(obj) + size - 4096) &
>> 0xfffff000) << 32;
>> val |= i915_gem_obj_ggtt_offset(obj) & 0xfffff000;
>> --
>> 2.1.0
>>
>> _______________________________________________
>> Intel-gfx mailing list
>> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
>> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch
--
Jani Nikula, Intel Open Source Technology Center
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