drm/nv50: align size of buffer object to the right boundaries.
- In the current situation the padding that is added is dangerous to write
to, userspace could potentially overwrite parts of another bo.
- Depth and stencil buffers are supposed to be large enough in general so
the waste of memory should be acceptable.
- Alternatives are hiding the padding from users or splitting vram into 2
zones.
Signed-off-by: Maarten Maathuis <madman2003@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c b/drivers/gpu/drm/nouveau/nouveau_bo.c
index db0ed4c..028719f 100644
--- a/drivers/gpu/drm/nouveau/nouveau_bo.c
+++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
@@ -65,8 +65,10 @@
/*
* Some of the tile_flags have a periodic structure of N*4096 bytes,
- * align to to that as well as the page size. Overallocate memory to
- * avoid corruption of other buffer objects.
+ * align to to that as well as the page size. Align the size to the
+ * appropriate boundaries. This does imply that sizes are rounded up
+ * 3-7 pages, so be aware of this and do not waste memory by allocating
+ * many small buffers.
*/
if (dev_priv->card_type == NV_50) {
uint32_t block_size = nouveau_mem_fb_amount(dev) >> 15;
@@ -77,22 +79,20 @@
case 0x2800:
case 0x4800:
case 0x7a00:
- *size = roundup(*size, block_size);
if (is_power_of_2(block_size)) {
- *size += 3 * block_size;
for (i = 1; i < 10; i++) {
*align = 12 * i * block_size;
if (!(*align % 65536))
break;
}
} else {
- *size += 6 * block_size;
for (i = 1; i < 10; i++) {
*align = 8 * i * block_size;
if (!(*align % 65536))
break;
}
}
+ *size = roundup(*size, *align);
break;
default:
break;