[PATCH v2 14/19] accel: ethosu: Reject reserved command encodings

[Rob Herring (Arm)]

The command stream contains a 10-bit opcode and a two-bit command
control field. Reject reserved opcode and control encodings in the
switch default case so they cannot be interpreted differently by the
validator and hardware.

Fixes: 5a5e9c0228e6 ("accel: Add Arm Ethos-U NPU driver")
Cc: stable@xxxxxxxxxxxxxxx
Assisted-by: LLM
Signed-off-by: Rob Herring (Arm) <robh@xxxxxxxxxx>
---
v2:
 - new patch
---
 drivers/accel/ethosu/ethosu_device.h |  3 +++
 drivers/accel/ethosu/ethosu_gem.c    | 12 +++++++-----
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/accel/ethosu/ethosu_device.h b/drivers/accel/ethosu/ethosu_device.h
index 8e23fdbf7f8a..68e2969b6f79 100644
--- a/drivers/accel/ethosu/ethosu_device.h
+++ b/drivers/accel/ethosu/ethosu_device.h
@@ -91,6 +91,9 @@ struct gen_pool;
 #define NPU_KERNEL_DILATION_X		BIT(3)
 #define NPU_KERNEL_DILATION_Y		BIT(4)
 
+#define NPU_CMD_CTRL_CMD1		BIT(14)
+#define NPU_CMD_RESERVED_MASK		(BIT(15) | GENMASK(13, 10))
+
 enum ethosu_cmds {
 	NPU_OP_STOP = 0x0,
 	NPU_OP_IRQ = 0x1,
diff --git a/drivers/accel/ethosu/ethosu_gem.c b/drivers/accel/ethosu/ethosu_gem.c
index 63dd07791f31..d5c3a2c530dc 100644
--- a/drivers/accel/ethosu/ethosu_gem.c
+++ b/drivers/accel/ethosu/ethosu_gem.c
@@ -160,9 +160,9 @@ static void cmd_state_init(struct cmd_state *st)
 
 static void cmd_state_set_reg(struct cmd_state *st, u16 cmd)
 {
-	u16 reg = cmd & ~BIT(14);
+	u16 reg = cmd & ~NPU_CMD_CTRL_CMD1;
 
-	if (cmd & BIT(14)) {
+	if (cmd & NPU_CMD_CTRL_CMD1) {
 		if (reg < NPU_CMD1_REGS)
 			__set_bit(reg, st->cmd1);
 	} else if (reg < NPU_CMD0_REGS) {
@@ -172,9 +172,9 @@ static void cmd_state_set_reg(struct cmd_state *st, u16 cmd)
 
 static bool cmd_state_reg_is_set(struct cmd_state *st, u16 cmd)
 {
-	u16 reg = cmd & ~BIT(14);
+	u16 reg = cmd & ~NPU_CMD_CTRL_CMD1;
 
-	if (cmd & BIT(14))
+	if (cmd & NPU_CMD_CTRL_CMD1)
 		return reg < NPU_CMD1_REGS && test_bit(reg, st->cmd1);
 
 	return reg < NPU_CMD0_REGS && test_bit(reg, st->cmd0);
@@ -702,7 +702,7 @@ static int ethosu_gem_cmdstream_copy_and_validate(struct drm_device *ddev,
 		cmd = cmds[0];
 		param = cmds[0] >> 16;
 
-		if (cmd & 0x4000) {
+		if (cmd & NPU_CMD_CTRL_CMD1) {
 			if (get_user(cmds[1], ucmds++))
 				return -EFAULT;
 
@@ -1023,6 +1023,8 @@ static int ethosu_gem_cmdstream_copy_and_validate(struct drm_device *ddev,
 			st.dma.src.len = st.dma.dst.len = addr;
 			break;
 		default:
+			if (cmd & NPU_CMD_RESERVED_MASK)
+				return -EINVAL;
 			break;
 		}
 	}

-- 
2.53.0