kernel: fix stack size check in k_thread_create

The pointer arithmetic used didn't account for ARC
supervisor mode stacks, which are allocated at the
end of the stack object. Use the new macro to know
exactly how much space is reserved.

Signed-off-by: Andrew Boie <[email protected]>

Author: Andrew Boie

kernel/thread.c

@@ -451,9 +451,7 @@ Z_SYSCALL_HANDLER(k_thread_create,
 	int prio;
 	u32_t options, delay;
 	u32_t total_size;
-#ifndef CONFIG_MPU_REQUIRES_POWER_OF_TWO_ALIGNMENT
-	u32_t guard_size;
-#endif
+
 	struct _k_object *stack_object;
 	struct k_thread *new_thread = (struct k_thread *)new_thread_p;
 	volatile struct _syscall_10_args *margs =
@@ -468,23 +466,15 @@ Z_SYSCALL_HANDLER(k_thread_create,
 						_OBJ_INIT_FALSE) == 0,
 				    "bad stack object"));
 
-#ifndef CONFIG_MPU_REQUIRES_POWER_OF_TWO_ALIGNMENT
 	/* Verify that the stack size passed in is OK by computing the total
 	 * size and comparing it with the size value in the object metadata
-	 *
-	 * We skip this check for SoCs which utilize MPUs with power of two
-	 * alignment requirements as the guard is allocated out of the stack
-	 * size and not allocated in addition to the stack size
 	 */
-	guard_size = (u32_t)K_THREAD_STACK_BUFFER(stack) - (u32_t)stack;
-	Z_OOPS(Z_SYSCALL_VERIFY_MSG(!__builtin_uadd_overflow(guard_size,
+	Z_OOPS(Z_SYSCALL_VERIFY_MSG(!__builtin_uadd_overflow(K_THREAD_STACK_RESERVED,
 							     stack_size,
 							     &total_size),
 				    "stack size overflow (%u+%u)", stack_size,
-				    guard_size));
-#else
-	total_size = stack_size;
-#endif
+				    K_THREAD_STACK_RESERVED));
+
 	/* They really ought to be equal, make this more strict? */
 	Z_OOPS(Z_SYSCALL_VERIFY_MSG(total_size <= stack_object->data,
 				    "stack size %u is too big, max is %u",