- Don't try to allocate mappings of less than a PAGE_SIZE in MGA DMA code.

- Comment out the "is this mapping/bufs in allocated AGP" bits in BSD
    because they break mga (which uses AGP allocation that doesn't track
    entries). It's not a security issue when we still have the related
    ioctls marked root-only.
- Apply some power-of-two alignment restrictions to hopefully avoid some
    panicing in bad cases of drm_pci_alloc() on FreeBSD.
- Add verbosity to some error handling that I found useful while debugging.

1 files changed, 7 insertions, 0 deletions

diff --git a/bsd-core/drm_pci.c b/bsd-core/drm_pci.c
index 0f431dd6..a33f5f9c 100644
--- a/bsd-core/drm_pci.c
+++ b/bsd-core/drm_pci.c
@@ -58,6 +58,13 @@ drm_pci_alloc(drm_device_t *dev, size_t size, size_t align, dma_addr_t maxaddr)
 	drm_dma_handle_t *dmah;
 	int ret;
 
+	/* Need power-of-two alignment, so fail the allocation if it isn't. */
+	if ((align & (align - 1)) != 0) {
+		DRM_ERROR("drm_pci_alloc with non-power-of-two alignment %d\n",
+		    (int)align);
+		return NULL;
+	}
+
 	dmah = malloc(sizeof(drm_dma_handle_t), M_DRM, M_ZERO | M_NOWAIT);
 	if (dmah == NULL)
 		return NULL;