Index: sys/arm/include/gdb_machdep.h
===================================================================
--- sys/arm/include/gdb_machdep.h	(revision 368108)
+++ sys/arm/include/gdb_machdep.h	(working copy)
@@ -33,6 +33,8 @@
 
 #define	GDB_BUFSZ	400
 #define	GDB_NREGS	26
+#define GDB_REG_SP	13
+#define GDB_REG_LR	14
 #define	GDB_REG_PC	15
 
 static __inline size_t
Index: sys/arm/arm/gdb_machdep.c
===================================================================
--- sys/arm/arm/gdb_machdep.c	(revision 368108)
+++ sys/arm/arm/gdb_machdep.c	(working copy)
@@ -97,11 +97,28 @@
 void
 gdb_cpu_setreg(int regnum, void *val)
 {
-
 	switch (regnum) {
 	case GDB_REG_PC:
-		if (kdb_thread  == curthread)
+		if (kdb_thread == curthread) {
 			kdb_frame->tf_pc = *(register_t *)val;
+		}
+		break;
+	case GDB_REG_SP:
+		if (kdb_thread == curthread) {
+			kdb_frame->tf_svc_sp = *(register_t *)val;
+		}
+		break;
+	case GDB_REG_LR:
+		if (kdb_thread == curthread) {
+			kdb_frame->tf_svc_lr = *(register_t *)val;
+		}
+		break;
+	default:
+		/* Write to the general purpose registers r0-r12. */
+		if (kdb_thread == curthread && regnum >= 0 && regnum <= 12) {
+			*(&kdb_frame->tf_r0 + regnum) = *(register_t *)val;
+		}
+		break;
 	}
 }