Mine

Index: libc/arm/gen/_set_tp.c
===================================================================
--- libc/arm/gen/_set_tp.c      (revision 232878)
+++ libc/arm/gen/_set_tp.c      (working copy)
@@ -29,7 +29,10 @@
 #include <string.h>
 #include <stdint.h>

+#include <machine/sysarch.h>
+
 void
 _set_tp(void *tp)
 {
+       *((struct tcb **)ARM_TP_ADDRESS) = tp;
 }