5362 invalid conversion when using asm/thread.h in c++ code

*** 20,29 ****
--- 20,30 ----
   * CDDL HEADER END
   */
  /*
   * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
+  * Copyright 2014 Nexenta Systems, Inc.  All rights reserved.
   */
  
  #ifndef _ASM_THREAD_H
  #define _ASM_THREAD_H
  
*** 46,56 ****
   */
  
  extern __GNU_INLINE struct _kthread
  *threadp(void)
  {
!         void *__value;
  
  #if defined(__amd64)
          __asm__ __volatile__(
              "movq %%gs:0x18,%0"         /* CPU_THREAD */
              : "=r" (__value));
--- 47,57 ----
   */
  
  extern __GNU_INLINE struct _kthread
  *threadp(void)
  {
!         struct _kthread *__value;
  
  #if defined(__amd64)
          __asm__ __volatile__(
              "movq %%gs:0x18,%0"         /* CPU_THREAD */
              : "=r" (__value));