staging: android: ion: do not clear dma_address of unmapped heap

Since commit 54ef5b9 (staging: android: ion: Initialize dma_address
of new sg list") (Linux v4.17), the helper function dup_sg_table() called
by ion_dma_buf_attach() does not preserve the dma_address from the
original SG list. It is a problem for the unmapped heap, because
dma_buf_attach() followed by dma_buf_map_attachment() now returns a SG
table with NULL dma_address, which breaks tee_shm_register_fd().

This commit avoids the dma_address reset for the unmapped heap.

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>

drivers/staging/android/ion/ion.c

@@ -163,7 +163,8 @@ static void ion_buffer_kmap_put(struct ion_buffer *buffer)
  }
 }
 
-static struct sg_table *dup_sg_table(struct sg_table *table)
+static struct sg_table *dup_sg_table(struct sg_table *table,
+ bool preserve_dma_address)
 {
  struct sg_table *new_table;
  int ret, i;
@@ -182,7 +183,8 @@ static struct sg_table *dup_sg_table(struct sg_table *table)
  new_sg = new_table->sgl;
  for_each_sg(table->sgl, sg, table->nents, i) {
  memcpy(new_sg, sg, sizeof(*sg));
- new_sg->dma_address = 0;
+ if (!preserve_dma_address)
+ new_sg->dma_address = 0;
  new_sg = sg_next(new_sg);
  }
 
@@ -213,15 +215,15 @@ static int ion_dma_buf_attach(struct dma_buf *dmabuf, struct device *dev,
  if (!a)
  return -ENOMEM;
 
- table = dup_sg_table(buffer->sg_table);
+ if (buffer->heap->type == ION_HEAP_TYPE_UNMAPPED)
+ a->no_map = true;
+
+ table = dup_sg_table(buffer->sg_table, a->no_map);
  if (IS_ERR(table)) {
  kfree(a);
  return -ENOMEM;
  }
 
- if (buffer->heap->type == ION_HEAP_TYPE_UNMAPPED)
- a->no_map = true;
-
  a->table = table;
  a->dev = dev;
  INIT_LIST_HEAD(&a->list);