[PATCH v2 5/8] dma-buf: heaps: secure_heap: Add dma_ops

[Yong Wu]

Add the dma_ops for this secure heap.
a) For secure buffer, cache_ops/mmap are not allowed, thus return
EPERM for them.
b) The secure buffer can't be accessed in kernel, thus it doesn't
have va/dma_address for it. Use the dma_address property to save the
"secure handle".

Signed-off-by: Yong Wu <yong.wu at mediatek.com>
---
 drivers/dma-buf/heaps/secure_heap.c | 120 ++++++++++++++++++++++++++++
 1 file changed, 120 insertions(+)

diff --git a/drivers/dma-buf/heaps/secure_heap.c b/drivers/dma-buf/heaps/secure_heap.c
index 05062c14e7c7..25cc95442c56 100644
--- a/drivers/dma-buf/heaps/secure_heap.c
+++ b/drivers/dma-buf/heaps/secure_heap.c
@@ -9,6 +9,7 @@
 #include <linux/dma-heap.h>
 #include <linux/err.h>
 #include <linux/module.h>
+#include <linux/scatterlist.h>
 #include <linux/slab.h>
 #include <linux/tee_drv.h>
 #include <linux/uuid.h>
@@ -87,6 +88,10 @@ struct secure_heap {
 	const struct secure_heap_prv_data *data;
 };
 
+struct secure_heap_attachment {
+	struct sg_table			*table;
+};
+
 static int tee_ctx_match(struct tee_ioctl_version_data *ver, const void *data)
 {
 	const struct secure_heap_prv_data *d = data;
@@ -238,6 +243,120 @@ static void secure_heap_secure_memory_free(struct secure_heap *sec_heap,
 		data->memory_free(sec_heap, sec_buf);
 }
 
+static int secure_heap_attach(struct dma_buf *dmabuf, struct dma_buf_attachment *attachment)
+{
+	struct secure_buffer *sec_buf = dmabuf->priv;
+	struct secure_heap_attachment *a;
+	struct sg_table *table;
+	int ret;
+
+	a = kzalloc(sizeof(*a), GFP_KERNEL);
+	if (!a)
+		return -ENOMEM;
+
+	table = kzalloc(sizeof(*table), GFP_KERNEL);
+	if (!table) {
+		ret = -ENOMEM;
+		goto err_free_attach;
+	}
+
+	ret = sg_alloc_table(table, 1, GFP_KERNEL);
+	if (ret)
+		goto err_free_sgt;
+	sg_set_page(table->sgl, 0, sec_buf->size, 0);
+
+	a->table = table;
+	attachment->priv = a;
+
+	return 0;
+
+err_free_sgt:
+	kfree(table);
+err_free_attach:
+	kfree(a);
+	return ret;
+}
+
+static void secure_heap_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attachment)
+{
+	struct secure_heap_attachment *a = attachment->priv;
+
+	sg_free_table(a->table);
+	kfree(a->table);
+	kfree(a);
+}
+
+static struct sg_table *
+secure_heap_map_dma_buf(struct dma_buf_attachment *attachment, enum dma_data_direction direction)
+{
+	struct secure_heap_attachment *a = attachment->priv;
+	struct dma_buf *dmabuf = attachment->dmabuf;
+	struct secure_buffer *sec_buf = dmabuf->priv;
+	struct sg_table *table = a->table;
+
+	/*
+	 * Technically dma_address refers to the address used by HW, But for secure buffer
+	 * we don't know its dma_address in kernel, Instead, we only know its "secure handle".
+	 * Thus use this property to save the "secure handle", and the user will use it to
+	 * obtain the real address in secure world.
+	 *
+	 * Note: CONFIG_DMA_API_DEBUG requires it to be aligned with PAGE_SIZE.
+	 */
+	if (sec_buf->sec_handle) {
+		sg_dma_address(table->sgl) = sec_buf->sec_handle;
+		sg_dma_len(table->sgl) = sec_buf->size;
+	}
+	return table;
+}
+
+static void
+secure_heap_unmap_dma_buf(struct dma_buf_attachment *attachment, struct sg_table *table,
+			  enum dma_data_direction direction)
+{
+	struct secure_heap_attachment *a = attachment->priv;
+
+	WARN_ON(a->table != table);
+	sg_dma_address(table->sgl) = 0;
+	sg_dma_len(table->sgl) = 0;
+}
+
+static int
+secure_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, enum dma_data_direction direction)
+{
+	return -EPERM;
+}
+
+static int
+secure_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf, enum dma_data_direction direction)
+{
+	return -EPERM;
+}
+
+static int secure_heap_dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma)
+{
+	return -EPERM;
+}
+
+static void secure_heap_free(struct dma_buf *dmabuf)
+{
+	struct secure_buffer *sec_buf = dmabuf->priv;
+	struct secure_heap *sec_heap = dma_heap_get_drvdata(sec_buf->heap);
+
+	secure_heap_secure_memory_free(sec_heap, sec_buf);
+	kfree(sec_buf);
+}
+
+static const struct dma_buf_ops sec_heap_buf_ops = {
+	.attach		= secure_heap_attach,
+	.detach		= secure_heap_detach,
+	.map_dma_buf	= secure_heap_map_dma_buf,
+	.unmap_dma_buf	= secure_heap_unmap_dma_buf,
+	.begin_cpu_access = secure_heap_dma_buf_begin_cpu_access,
+	.end_cpu_access	= secure_heap_dma_buf_end_cpu_access,
+	.mmap		= secure_heap_dma_buf_mmap,
+	.release	= secure_heap_free,
+};
+
 static struct dma_buf *
 secure_heap_allocate(struct dma_heap *heap, unsigned long size,
 		     unsigned long fd_flags, unsigned long heap_flags)
@@ -271,6 +390,7 @@ secure_heap_allocate(struct dma_heap *heap, unsigned long size,
 	if (ret)
 		goto err_free_buf;
 	exp_info.exp_name = dma_heap_get_name(heap);
+	exp_info.ops = &sec_heap_buf_ops;
 	exp_info.size = sec_buf->size;
 	exp_info.flags = fd_flags;
 	exp_info.priv = sec_buf;
-- 
2.25.1