[PATCH 2/2] tee: optee: don't enumerate services if there ain't any

[Etienne Carriere]

Change optee driver service enumeration to not enumerate (and
allocate a zero sized shared memory buffer) when OP-TEE
reports that there is no service to enumerate.

This change fixes an existing issue that occurs when the such zero
sized shared memory buffer allocated from malloc() has a physical
address of offset 0 of a physical 4kB page. In such case, OP-TEE
secure world refuses to register the zero-sized shared memory
area and makes U-Boot optee service enumeration to fail.

Fixes: 94ccfb78a4d6 ("drivers: tee: optee: discover OP-TEE services")
Signed-off-by: Etienne Carriere <etienne.carriere at foss.st.com>
---
 drivers/tee/optee/core.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c
index 5308dd58ce..47f845cffe 100644
--- a/drivers/tee/optee/core.c
+++ b/drivers/tee/optee/core.c
@@ -139,6 +139,11 @@ static int enum_services(struct udevice *dev, struct tee_shm **shm, size_t *coun
 	if (ret)
 		return ret;
 
+	if (!shm_size) {
+		*count = 0;
+		return 0;
+	}
+
 	ret = tee_shm_alloc(dev, shm_size, 0, shm);
 	if (ret) {
 		dev_err(dev, "Failed to allocated shared memory: %d\n", ret);
@@ -185,14 +190,15 @@ static int bind_service_drivers(struct udevice *dev)
 
 	ret = enum_services(dev, &service_list, &service_count, tee_sess,
 			    PTA_CMD_GET_DEVICES);
-	if (!ret)
+	if (!ret && service_count)
 		ret = bind_service_list(dev, service_list, service_count);
 
 	tee_shm_free(service_list);
+	service_list = NULL;
 
 	ret2 = enum_services(dev, &service_list, &service_count, tee_sess,
 			     PTA_CMD_GET_DEVICES_SUPP);
-	if (!ret2)
+	if (!ret2 && service_count)
 		ret2 = bind_service_list(dev, service_list, service_count);
 
 	tee_shm_free(service_list);
-- 
2.25.1