diff -u -r /home/fornwall/lib/android-ndk/platforms/android-21/arch-arm64/usr/include/sys/user.h ./usr/include/sys/user.h
--- /home/fornwall/lib/android-ndk/platforms/android-21/arch-arm64/usr/include/sys/user.h	2014-12-08 21:59:41.000000000 -0500
+++ ./usr/include/sys/user.h	2016-01-08 20:08:08.327228220 -0500
@@ -99,6 +99,13 @@
   int u_debugreg[8];
 };
 
+/* Needed by binutils on x86 */
+/* http://osxr.org/android/source/bionic/libc/kernel/arch-x86/asm/user_32.h#0089 */
+#define NBPG PAGE_SIZE
+#define UPAGES 1
+#define HOST_TEXT_START_ADDR (u.start_code)
+#define HOST_STACK_END_ADDR (u.start_stack + u.u_ssize * NBPG)
+
 #elif defined(__x86_64__)
 
 struct user_fpregs_struct {
@@ -234,7 +240,18 @@
 
 #elif defined(__aarch64__)
 
-// There are no user structures for 64 bit arm.
+/* From https://codereview.chromium.org/1291983003 */
+struct user_regs_struct {
+  __u64 regs[31];
+  __u64 sp;
+  __u64 pc;
+  __u64 pstate;
+};
+struct user_fpsimd_struct {
+  __uint128_t vregs[32];
+  __u32 fpsr;
+  __u32 fpcr;
+};
 
 #else