AArch64: Add initial support for AArch64

This is the first patch out of a series of patches that add support for
AArch64, the new 64bit execution state of the ARMv8 Architecture. The
patches add support for LP64 programming model.

The patch adds:
* "arch-aarch64" to the architecture directories.
* "arch-aarch64/include" - headers used by libc
* "arch-aarch64/bionic":
    - crtbegin, crtend support;
    - aarch64 specific syscall stubs;
    - setjmp, clone, vfork assembly files.

Change-Id: If72b859f81928d03ad05d4ccfcb54c2f5dbf99a5
Signed-off-by: Serban Constantinescu <serban.constantinescu@arm.com>
diff --git a/libc/arch-aarch64/bionic/futex_aarch64.S b/libc/arch-aarch64/bionic/futex_aarch64.S
new file mode 100644
index 0000000..c25d2dd
--- /dev/null
+++ b/libc/arch-aarch64/bionic/futex_aarch64.S
@@ -0,0 +1,129 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ * All rights reserved
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <asm/unistd.h>
+#include <linux/err.h>
+#include <machine/asm.h>
+
+#define FUTEX_WAIT 0
+#define FUTEX_WAKE 1
+
+/*
+ * Syscall interface for fast userspace locks
+ *
+ * int __futex_wait(volatile void *ftx, int val, const struct timespec *timeout);
+ * int __futex_wake(volatile void *ftx, int count);
+ * int __futex_syscall3(volatile void *ftx, int op, int val);
+ * int __futex_syscall4(volatile void *ftx, int op, int val, const struct timespec *timeout);
+ */
+
+ENTRY(__futex_syscall4)
+    /* create AArch64 PCS frame pointer */
+    stp    x29, x30, [sp, #-16]!
+    mov    x29,  sp
+
+    /* store x8 */
+    str    x8,       [sp, #-16]!
+
+    /* syscall No. in x8 */
+    mov     x8, __NR_futex
+    svc     #0
+
+    /* restore x8 */
+    ldr     x8,       [sp], #16
+    ldp     x29, x30, [sp], #16
+
+    /* check if syscall returned successfully */
+    cmn     x0, #(MAX_ERRNO + 1)
+    cneg    x0, x0, hi
+    b.hi    __set_errno
+
+    ret
+END(__futex_syscall4)
+
+ENTRY(__futex_syscall3)
+    /* __futex_syscall4 but with fewer arguments */
+    b __futex_syscall4
+END(__futex_syscall3)
+
+ENTRY(__futex_wait)
+    /* create AArch64 PCS frame pointer */
+    stp    x29, x30, [sp, #-16]!
+    mov    x29,  sp
+
+    /* store x8 */
+    str    x8,       [sp, #-16]!
+
+    /* arange arguments as expected in the kernel side */
+    mov x3, x2
+    mov w2, w1
+    mov w1, #FUTEX_WAIT
+
+    /* syscall No. in X8 */
+    mov     x8, __NR_futex
+    svc     #0
+
+    /* restore x8 */
+    ldr     x8,       [sp], #16
+    ldp     x29, x30, [sp], #16
+
+    /* check if syscall returned successfully */
+    cmn     x0, #(MAX_ERRNO + 1)
+    cneg    x0, x0, hi
+    b.hi    __set_errno
+
+    ret
+END(__futex_wait)
+
+ENTRY(__futex_wake)
+    /* create AArch64 PCS frame pointer */
+    stp    x29, x30, [sp, #-16]!
+    mov    x29,  sp
+
+    /* store x8 */
+    str    x8,       [sp, #-16]!
+
+    /* arange arguments as expected in the kernel side */
+    mov w2, w1
+    mov w1, #FUTEX_WAIT
+
+    /* syscall No. in X8 */
+    mov     x8, __NR_futex
+    svc     #0
+
+    /* restore x8 */
+    ldr     x8,       [sp], #16
+    ldp     x29, x30, [sp], #16
+
+    /* check if syscall returned successfully */
+    cmn     x0, #(MAX_ERRNO + 1)
+    cneg    x0, x0, hi
+    b.hi    __set_errno
+
+    ret
+END(__futex_wake)