auto import from //depot/cupcake/@135843
diff --git a/libc/arch-arm/bionic/atomics_arm.S b/libc/arch-arm/bionic/atomics_arm.S
new file mode 100644
index 0000000..b2da09f
--- /dev/null
+++ b/libc/arch-arm/bionic/atomics_arm.S
@@ -0,0 +1,178 @@
+/*
+ * Copyright (C) 2008 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 <sys/linux-syscalls.h>
+
+.global __atomic_cmpxchg
+.global __atomic_swap
+.global __atomic_dec
+.global __atomic_inc
+.global __futex_wait
+.global __futex_wake
+
+#define FUTEX_WAIT 0
+#define FUTEX_WAKE 1
+
+#if 1
+ .equ kernel_cmpxchg, 0xFFFF0FC0
+ .equ kernel_atomic_base, 0xFFFF0FFF
+__atomic_dec:
+ stmdb sp!, {r4, lr}
+ mov r2, r0
+1: @ atomic_dec
+ ldr r0, [r2]
+ mov r3, #kernel_atomic_base
+ add lr, pc, #4
+ sub r1, r0, #1
+ add pc, r3, #(kernel_cmpxchg - kernel_atomic_base)
+ bcc 1b
+ add r0, r1, #1
+ ldmia sp!, {r4, lr}
+ bx lr
+
+__atomic_inc:
+ stmdb sp!, {r4, lr}
+ mov r2, r0
+1: @ atomic_inc
+ ldr r0, [r2]
+ mov r3, #kernel_atomic_base
+ add lr, pc, #4
+ add r1, r0, #1
+ add pc, r3, #(kernel_cmpxchg - kernel_atomic_base)
+ bcc 1b
+ sub r0, r1, #1
+ ldmia sp!, {r4, lr}
+ bx lr
+
+/* r0(old) r1(new) r2(addr) -> r0(zero_if_succeeded) */
+__atomic_cmpxchg:
+ stmdb sp!, {r4, lr}
+ mov r4, r0 /* r4 = save oldvalue */
+1: @ atomic_cmpxchg
+ mov r3, #kernel_atomic_base
+ add lr, pc, #4
+ mov r0, r4 /* r0 = oldvalue */
+ add pc, r3, #(kernel_cmpxchg - kernel_atomic_base)
+ bcs 2f /* swap was made. we're good, return. */
+ ldr r3, [r2] /* swap not made, see if it's because *ptr!=oldvalue */
+ cmp r3, r4
+ beq 1b
+2: @ atomic_cmpxchg
+ ldmia sp!, {r4, lr}
+ bx lr
+#else
+#define KUSER_CMPXCHG 0xffffffc0
+
+/* r0(old) r1(new) r2(addr) -> r0(zero_if_succeeded) */
+__atomic_cmpxchg:
+ stmdb sp!, {r4, lr}
+ mov r4, r0 /* r4 = save oldvalue */
+1: add lr, pc, #4
+ mov r0, r4 /* r0 = oldvalue */
+ mov pc, #KUSER_CMPXCHG
+ bcs 2f /* swap was made. we're good, return. */
+ ldr r3, [r2] /* swap not made, see if it's because *ptr!=oldvalue */
+ cmp r3, r4
+ beq 1b
+2: ldmia sp!, {r4, lr}
+ bx lr
+
+/* r0(addr) -> r0(old) */
+__atomic_dec:
+ stmdb sp!, {r4, lr}
+ mov r2, r0 /* address */
+1: ldr r0, [r2] /* oldvalue */
+ add lr, pc, #4
+ sub r1, r0, #1 /* newvalue = oldvalue - 1 */
+ mov pc, #KUSER_CMPXCHG
+ bcc 1b /* no swap, try again until we get it right */
+ mov r0, ip /* swapped, return the old value */
+ ldmia sp!, {r4, lr}
+ bx lr
+
+/* r0(addr) -> r0(old) */
+__atomic_inc:
+ stmdb sp!, {r4, lr}
+ mov r2, r0 /* address */
+1: ldr r0, [r2] /* oldvalue */
+ add lr, pc, #4
+ add r1, r0, #1 /* newvalue = oldvalue + 1 */
+ mov pc, #KUSER_CMPXCHG
+ bcc 1b /* no swap, try again until we get it right */
+ mov r0, ip /* swapped, return the old value */
+ ldmia sp!, {r4, lr}
+ bx lr
+#endif
+
+/* r0(new) r1(addr) -> r0(old) */
+__atomic_swap:
+ swp r0, r0, [r1]
+ bx lr
+
+/* __futex_wait(*ftx, val, *timespec) */
+/* __futex_syscall(*ftx, op, val, *timespec, *addr2, val3) */
+
+#if __ARM_EABI__
+
+__futex_wait:
+ .fnstart
+ stmdb sp!, {r4, r7}
+ .save {r4, r7}
+ mov r3, r2
+ mov r2, r1
+ mov r1, #FUTEX_WAIT
+ ldr r7, =__NR_futex
+ swi #0
+ ldmia sp!, {r4, r7}
+ bx lr
+ .fnend
+
+__futex_wake:
+ stmdb sp!, {r4, r7}
+ mov r2, r1
+ mov r1, #FUTEX_WAKE
+ ldr r7, =__NR_futex
+ swi #0
+ ldmia sp!, {r4, r7}
+ bx lr
+
+#else
+
+__futex_wait:
+ mov r3, r2
+ mov r2, r1
+ mov r1, #FUTEX_WAIT
+ swi #__NR_futex
+ bx lr
+
+__futex_wake:
+ mov r2, r1
+ mov r1, #FUTEX_WAKE
+ swi #__NR_futex
+ bx lr
+
+#endif