The included patch makes code comments match code and documentation (man 
page).

Index: sys/platform/pc32/i386/tls.c
===================================================================
--- sys/platform/pc32/i386/tls.c    (revision 27)
+++ sys/platform/pc32/i386/tls.c    (working copy)
@@ -62,7 +62,7 @@
  * Returns the value userland needs to load into %gs representing the
  * TLS descriptor or -1 on error.
  *
- * (struct tls_info *info, int infosize, int which)
+ * (int which, struct tls_info *info, size_t infosize)
  */
 int
 sys_set_tls_area(struct set_tls_area_args *uap)
@@ -154,7 +154,7 @@
  * Returns the value userland needs to load into %gs representing the
  * TLS descriptor or -1 on error.
  *
- * (struct tls_info *info, int infosize, int which)
+ * (int which, struct tls_info *info, size_t infosize)
  */
 int
 sys_get_tls_area(struct get_tls_area_args *uap)
Index: sys/platform/pc64/amd64/tls.c
===================================================================
--- sys/platform/pc64/amd64/tls.c    (revision 27)
+++ sys/platform/pc64/amd64/tls.c    (working copy)
@@ -61,7 +61,7 @@
  * Returns the value userland needs to load into %gs representing the
  * TLS descriptor or -1 on error.
  *
- * (struct tls_info *info, int infosize, int which)
+ * (int which, struct tls_info *info, size_t infosize)
  */
 int
 sys_set_tls_area(struct set_tls_area_args *uap)
@@ -153,7 +153,7 @@
  * Returns the value userland needs to load into %gs representing the
  * TLS descriptor or -1 on error.
  *
- * (struct tls_info *info, int infosize, int which)
+ * (int which, struct tls_info *info, size_t infosize)
  */
 int
 sys_get_tls_area(struct get_tls_area_args *uap)