tee: qcom: add primordial object

After booting, the kernel provides a static object known as the
primordial object. This object is utilized by QTEE for native
kernel services such as yield or privileged operations.

Acked-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org>
Tested-by: Harshal Dev <quic_hdev@quicinc.com>
Signed-off-by: Amirreza Zarrabi <amirreza.zarrabi@oss.qualcomm.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

Author: qc-azarrabi

drivers/tee/qcomtee/Makefile

@@ -3,5 +3,6 @@ obj-$(CONFIG_QCOMTEE) += qcomtee.o
 qcomtee-objs += async.o
 qcomtee-objs += call.o
 qcomtee-objs += core.o
+qcomtee-objs += primordial_obj.o
 qcomtee-objs += shm.o
 qcomtee-objs += user_obj.o

drivers/tee/qcomtee/core.c

@@ -31,10 +31,12 @@ int qcomtee_next_arg_type(struct qcomtee_arg *u, int i,
 }
 
 /*
- * QTEE expects IDs with the QCOMTEE_MSG_OBJECT_NS_BIT set for objects
- * of the QCOMTEE_OBJECT_TYPE_CB type.
+ * QTEE expects IDs with QCOMTEE_MSG_OBJECT_NS_BIT set for objects of
+ * QCOMTEE_OBJECT_TYPE_CB type. The first ID with QCOMTEE_MSG_OBJECT_NS_BIT
+ * set is reserved for the primordial object.
  */
-#define QCOMTEE_OBJECT_ID_START (QCOMTEE_MSG_OBJECT_NS_BIT + 1)
+#define QCOMTEE_OBJECT_PRIMORDIAL (QCOMTEE_MSG_OBJECT_NS_BIT)
+#define QCOMTEE_OBJECT_ID_START (QCOMTEE_OBJECT_PRIMORDIAL + 1)
 #define QCOMTEE_OBJECT_ID_END (U32_MAX)
 
 #define QCOMTEE_OBJECT_SET(p, type, ...) \
@@ -157,7 +159,9 @@ static void qcomtee_object_release(struct kref *refcount)
  */
 int qcomtee_object_get(struct qcomtee_object *object)
 {
-	if (object != NULL_QCOMTEE_OBJECT && object != ROOT_QCOMTEE_OBJECT)
+	if (object != &qcomtee_primordial_object &&
+	    object != NULL_QCOMTEE_OBJECT &&
+	    object != ROOT_QCOMTEE_OBJECT)
 		return kref_get_unless_zero(&object->refcount);
 
 	return 0;
@@ -169,7 +173,9 @@ int qcomtee_object_get(struct qcomtee_object *object)
  */
 void qcomtee_object_put(struct qcomtee_object *object)
 {
-	if (object != NULL_QCOMTEE_OBJECT && object != ROOT_QCOMTEE_OBJECT)
+	if (object != &qcomtee_primordial_object &&
+	    object != NULL_QCOMTEE_OBJECT &&
+	    object != ROOT_QCOMTEE_OBJECT)
 		kref_put(&object->refcount, qcomtee_object_release);
 }
 
@@ -261,6 +267,9 @@ qcomtee_local_object_get(struct qcomtee_object_invoke_ctx *oic,
 	struct qcomtee *qcomtee = tee_get_drvdata(oic->ctx->teedev);
 	struct qcomtee_object *object;
 
+	if (object_id == QCOMTEE_OBJECT_PRIMORDIAL)
+		return &qcomtee_primordial_object;
+
 	guard(rcu)();
 	object = xa_load(&qcomtee->xa_local_objects, object_id);
 	/* It already checks for %NULL_QCOMTEE_OBJECT. */

drivers/tee/qcomtee/primordial_obj.c

@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
+ */
+
+#include <linux/delay.h>
+#include "qcomtee.h"
+
+/**
+ * DOC: Primordial Object
+ *
+ * After boot, the kernel provides a static object of type
+ * %QCOMTEE_OBJECT_TYPE_CB called the primordial object. This object is used
+ * for native kernel services or privileged operations.
+ *
+ * We support:
+ *  - %QCOMTEE_OBJECT_OP_YIELD to yield by the thread running in QTEE.
+ *  - %QCOMTEE_OBJECT_OP_SLEEP to wait for a period of time.
+ */
+
+#define QCOMTEE_OBJECT_OP_YIELD 1
+#define QCOMTEE_OBJECT_OP_SLEEP 2
+
+static int
+qcomtee_primordial_obj_dispatch(struct qcomtee_object_invoke_ctx *oic,
+				struct qcomtee_object *primordial_object_unused,
+				u32 op, struct qcomtee_arg *args)
+{
+	int err = 0;
+
+	switch (op) {
+	case QCOMTEE_OBJECT_OP_YIELD:
+		cond_resched();
+		/* No output object. */
+		oic->data = NULL;
+		break;
+	case QCOMTEE_OBJECT_OP_SLEEP:
+		/* Check message format matched QCOMTEE_OBJECT_OP_SLEEP op. */
+		if (qcomtee_args_len(args) != 1 ||
+		    args[0].type != QCOMTEE_ARG_TYPE_IB ||
+		    args[0].b.size < sizeof(u32))
+			return -EINVAL;
+
+		msleep(*(u32 *)(args[0].b.addr));
+		/* No output object. */
+		oic->data = NULL;
+		break;
+	default:
+		err = -EINVAL;
+	}
+
+	return err;
+}
+
+static struct qcomtee_object_operations qcomtee_primordial_obj_ops = {
+	.dispatch = qcomtee_primordial_obj_dispatch,
+};
+
+struct qcomtee_object qcomtee_primordial_object = {
+	.name = "primordial",
+	.object_type = QCOMTEE_OBJECT_TYPE_CB,
+	.ops = &qcomtee_primordial_obj_ops
+};

drivers/tee/qcomtee/qcomtee.h

@@ -140,4 +140,7 @@ int qcomtee_user_object_submit(struct tee_context *ctx,
 			       struct tee_param *params, int num_params,
 			       int req_id, int errno);
 
+/* (2) Primordial Object. */
+extern struct qcomtee_object qcomtee_primordial_object;
+
 #endif /* QCOMTEE_H */