kernel: userspace: Add k_object_alloc_size

Add a new API to dynamically allocate kernel objects that allow
passing an arbitrary size. This new API allows to allocate dynamic
thread stack.

Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>

include/zephyr/sys/kobject.h

@@ -248,7 +248,8 @@ static inline void k_object_access_all_grant(const void *object)
  * state, with the calling thread being granted permission on it. The memory
  * for the object will be allocated out of the calling thread's resource pool.
  *
- * Currently, allocation of thread stacks is not supported.
+ * @note Thread stack object has to use k_object_alloc_size() since stacks may
+ * have different sizes.
  *
  * @param otype Requested kernel object type
  * @return A pointer to the allocated kernel object, or NULL if memory wasn't
@@ -256,6 +257,24 @@ static inline void k_object_access_all_grant(const void *object)
  */
 __syscall void *k_object_alloc(enum k_objects otype);
 
+/**
+ * Allocate a kernel object of a designated type and a given size
+ *
+ * This will instantiate at runtime a kernel object of the specified type,
+ * returning a pointer to it. The object will be returned in an uninitialized
+ * state, with the calling thread being granted permission on it. The memory
+ * for the object will be allocated out of the calling thread's resource pool.
+ *
+ * This function is specially helpful for thread stack objects because
+ * their sizes can vary. Other objects should probably look k_object_alloc().
+ *
+ * @param otype Requested kernel object type
+ * @param size Requested kernel object size
+ * @return A pointer to the allocated kernel object, or NULL if memory wasn't
+ * available
+ */
+__syscall void *k_object_alloc_size(enum k_objects otype, size_t size);
+
 /**
  * Allocate memory and install as a generic kernel object
  *
@@ -322,6 +341,15 @@ static inline void *z_impl_k_object_alloc(enum k_objects otype)
 	return NULL;
 }
 
+static inline void *z_impl_k_object_alloc_size(enum k_objects otype,
+					size_t size)
+{
+	ARG_UNUSED(otype);
+	ARG_UNUSED(size);
+
+	return NULL;
+}
+
 static inline struct z_object *z_dynamic_object_aligned_create(size_t align,
 							       size_t size)
 {

kernel/userspace.c

@@ -328,7 +328,7 @@ struct z_object *z_dynamic_object_aligned_create(size_t align, size_t size)
 	return &dyn->kobj;
 }
 
-void *z_impl_k_object_alloc(enum k_objects otype)
+static void *z_object_alloc(enum k_objects otype, size_t object_size)
 {
 	struct z_object *zo;
 	uintptr_t tidx = 0;
@@ -348,7 +348,8 @@ void *z_impl_k_object_alloc(enum k_objects otype)
 	/* The following are currently not allowed at all */
 	case K_OBJ_FUTEX:			/* Lives in user memory */
 	case K_OBJ_SYS_MUTEX:			/* Lives in user memory */
-	case K_OBJ_THREAD_STACK_ELEMENT:	/* No aligned allocator */
+	case K_OBJ_THREAD_STACK_ELEMENT:
+		break;
 	case K_OBJ_NET_SOCKET:			/* Indeterminate size */
 		LOG_ERR("forbidden object type '%s' requested",
 			otype_to_str(otype));
@@ -359,7 +360,7 @@ void *z_impl_k_object_alloc(enum k_objects otype)
 	}
 
 	zo = z_dynamic_object_aligned_create(obj_align_get(otype),
-					     obj_size_get(otype));
+					     object_size);
 	if (zo == NULL) {
 		if (otype == K_OBJ_THREAD) {
 			thread_idx_free(tidx);
@@ -385,6 +386,16 @@ void *z_impl_k_object_alloc(enum k_objects otype)
 	return zo->name;
 }
 
+void *z_impl_k_object_alloc(enum k_objects otype)
+{
+	return z_object_alloc(otype, obj_size_get(otype));
+}
+
+void *z_impl_k_object_alloc_size(enum k_objects otype, size_t size)
+{
+	return z_object_alloc(otype, size);
+}
+
 void k_object_free(void *obj)
 {
 	struct dyn_obj *dyn;

kernel/userspace_handler.c

@@ -65,3 +65,9 @@ static inline void *z_vrfy_k_object_alloc(enum k_objects otype)
 	return z_impl_k_object_alloc(otype);
 }
 #include <syscalls/k_object_alloc_mrsh.c>
+
+static inline void *z_vrfy_k_object_alloc_size(enum k_objects otype, size_t size)
+{
+	return z_impl_k_object_alloc_size(otype, size);
+}
+#include <syscalls/k_object_alloc_size_mrsh.c>