Implement the "abort" stub in assembly for ARM.
So that we can always get the full stack trace regardless of gcc's handling
of the "noreturn" attribute associated with abort().
BUG:6455193
Change-Id: Id264a5167e7cabbf11515fbc48f5469c527e34d4
diff --git a/libc/arch-arm/bionic/abort_arm.S b/libc/arch-arm/bionic/abort_arm.S
new file mode 100644
index 0000000..51b0871
--- /dev/null
+++ b/libc/arch-arm/bionic/abort_arm.S
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2012 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 <machine/asm.h>
+
+/*
+ * Coding the abort function in assembly so that registers are guaranteed to
+ * be preserved properly regardless of GCC's assumption on the "noreturn"
+ * attribute. When the registers are not properly preserved we won't be able
+ * to unwind the stack all the way to the bottom to fully reveal the call
+ * sequence when the crash happens.
+ */
+ENTRY(abort)
+ .save {r3, r14}
+ stmfd sp!, {r3, r14}
+ blx PIC_SYM(_C_LABEL(__libc_android_abort), PLT)
+END(abort)