tee: new ioctl to a register tee_shm from a dmabuf file descriptor

This change allows userland to create a tee_shm object that refers
to a dmabuf reference.

Userland provides a dmabuf file descriptor as buffer reference.
The created tee_shm object exported as a brand new dmabuf reference
used to provide a clean fd to userland. Userland shall closed this new
fd to release the tee_shm object resources. The initial dmabuf resources
are tracked independently through original dmabuf file descriptor.

Once the buffer is registered and until it is released, TEE driver
keeps a refcount on the registered dmabuf structure.

This change only support dmabuf references that relates to physically
contiguous memory buffers.

New tee_shm flag to identify tee_shm objects built from a registered
dmabuf: TEE_SHM_EXT_DMA_BUF. Such tee_shm structures are flagged both
TEE_SHM_DMA_BUF and TEE_SHM_EXT_DMA_BUF.

Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
From: https://github.com/linaro-swg/linux.git
(cherry picked from commit 41e21e5c405530590dc2dd10b2a8dbe64589840f)

1 files changed, 29 insertions, 0 deletions

diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h
index 688782e90140..81ee3ffbbac4 100644
--- a/include/uapi/linux/tee.h
+++ b/include/uapi/linux/tee.h
@@ -117,6 +117,35 @@ struct tee_ioctl_shm_alloc_data {
 				     struct tee_ioctl_shm_alloc_data)
 
 /**
+ * struct tee_ioctl_shm_register_fd_data - Shared memory registering argument
+ * @fd:		[in] file descriptor identifying the shared memory
+ * @size:	[out] Size of shared memory to allocate
+ * @flags:	[in] Flags to/from allocation.
+ * @id:		[out] Identifier of the shared memory
+ *
+ * The flags field should currently be zero as input. Updated by the call
+ * with actual flags as defined by TEE_IOCTL_SHM_* above.
+ * This structure is used as argument for TEE_IOC_SHM_ALLOC below.
+ */
+struct tee_ioctl_shm_register_fd_data {
+	__s64 fd;
+	__u64 size;
+	__u32 flags;
+	__s32 id;
+} __aligned(8);
+
+/**
+ * TEE_IOC_SHM_REGISTER_FD - register a shared memory from a file descriptor
+ *
+ * Returns a file descriptor on success or < 0 on failure
+ *
+ * The returned file descriptor refers to the shared memory object in kernel
+ * land. The shared memory is freed when the descriptor is closed.
+ */
+#define TEE_IOC_SHM_REGISTER_FD	_IOWR(TEE_IOC_MAGIC, TEE_IOC_BASE + 8, \
+				     struct tee_ioctl_shm_register_fd_data)
+
+/**
  * struct tee_ioctl_buf_data - Variable sized buffer
  * @buf_ptr:	[in] A __user pointer to a buffer
  * @buf_len:	[in] Length of the buffer above