[PATCH 03/11] accel: ethosu: Ensure cmd stream ends with a stop op

[Rob Herring (Arm)]

While the QSIZE register setting should prevent an out of bounds access
of the command stream, it is not clear whether the h/w generates an
interrupt in this case as is required (to prevent a timeout). As a stop op
is expected end of the command stream, let's just ensure it is present. A
stop op in the middle of the command stream also makes no sense.

Fixes: 5a5e9c0228e6 ("accel: Add Arm Ethos-U NPU driver")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Rob Herring (Arm) <robh@xxxxxxxxxx>
---
 drivers/accel/ethosu/ethosu_device.h | 1 +
 drivers/accel/ethosu/ethosu_gem.c    | 9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/drivers/accel/ethosu/ethosu_device.h b/drivers/accel/ethosu/ethosu_device.h
index d4458eac8447..1eca8590e68d 100644
--- a/drivers/accel/ethosu/ethosu_device.h
+++ b/drivers/accel/ethosu/ethosu_device.h
@@ -87,6 +87,7 @@ struct gen_pool;
 #define PMU_EV_TYPE_IDLE	0x20
 
 enum ethosu_cmds {
+	NPU_OP_STOP = 0x0,
 	NPU_OP_CONV = 0x2,
 	NPU_OP_DEPTHWISE = 0x3,
 	NPU_OP_POOL = 0x5,
diff --git a/drivers/accel/ethosu/ethosu_gem.c b/drivers/accel/ethosu/ethosu_gem.c
index d50fed64d4d9..eda9f42239be 100644
--- a/drivers/accel/ethosu/ethosu_gem.c
+++ b/drivers/accel/ethosu/ethosu_gem.c
@@ -390,6 +390,7 @@ static int ethosu_gem_cmdstream_copy_and_validate(struct drm_device *ddev,
 	struct ethosu_validated_cmdstream_info __free(kfree) *info = kzalloc_obj(*info);
 	struct ethosu_device *edev = to_ethosu_device(ddev);
 	u32 *bocmds = bo->base.vaddr;
+	bool ends_with_stop = false;
 	struct cmd_state st;
 	int i, ret;
 
@@ -426,6 +427,11 @@ static int ethosu_gem_cmdstream_copy_and_validate(struct drm_device *ddev,
 		}
 
 		switch (cmd) {
+		case NPU_OP_STOP:
+			if (i != size / 4 - 1)
+				return -EINVAL;
+			ends_with_stop = true;
+			break;
 		case NPU_OP_DMA_START:
 			srclen = dma_length(info, &st.dma, &st.dma.src);
 			dstlen = dma_length(info, &st.dma, &st.dma.dst);
@@ -688,6 +694,9 @@ static int ethosu_gem_cmdstream_copy_and_validate(struct drm_device *ddev,
 		}
 	}
 
+	if (!ends_with_stop)
+		return -EINVAL;
+
 	for (i = 0; i < NPU_BASEP_REGION_MAX; i++) {
 		if (!info->region_size[i])
 			continue;

-- 
2.53.0