Implement __gnu_Unwind_Find_exidx/__cxa_type_match

Leaving these unimplemented causes linker to have 2 weak undefined
symbols which in turn results in 3 unwanted relocations for arm arch.
Implementing them removes unwanted relocations from resulted dynamic
object

Test: make && readelf --dyn-sym linker
Test: linker-unit-tests && bionic-unit-tests --gtest_filter=dl*:Dl*
Test: flash and boot angler
Change-Id: I10120271936c770659239898aaf852d31c5483c2
diff --git a/linker/Android.bp b/linker/Android.bp
index fda7eb5..6a4e2b9 100644
--- a/linker/Android.bp
+++ b/linker/Android.bp
@@ -39,7 +39,10 @@
 
     arch: {
         arm: {
-            srcs: ["arch/arm/begin.S"],
+            srcs: [
+                "arch/arm/begin.S",
+                "linker_exidx_static.c",
+            ],
 
             cflags: ["-D__work_around_b_24465209__"],
         },
diff --git a/linker/linker_exidx_static.c b/linker/linker_exidx_static.c
new file mode 100644
index 0000000..b38ef17
--- /dev/null
+++ b/linker/linker_exidx_static.c
@@ -0,0 +1,46 @@
+/*
+ * 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 <link.h>
+
+/* Find the .ARM.exidx section (which in the case of a static executable
+ * can be identified through its start and end symbols), and return its
+ * beginning and numbe of entries to the caller.  Note that for static
+ * executables we do not need to use the value of the PC to find the
+ * EXIDX section.
+ */
+
+extern unsigned __exidx_end;
+extern unsigned __exidx_start;
+
+_Unwind_Ptr __gnu_Unwind_Find_exidx(_Unwind_Ptr pc __unused,
+                                    int* pcount)
+{
+  *pcount = (__exidx_end-__exidx_start)/8;
+  return __exidx_start;
+}
diff --git a/linker/linker_libcxx_support.cpp b/linker/linker_libcxx_support.cpp
index 11e0f40..41ed8bc 100644
--- a/linker/linker_libcxx_support.cpp
+++ b/linker/linker_libcxx_support.cpp
@@ -31,3 +31,7 @@
 void* __find_icu_symbol(const char* symbol_name __attribute__((__unused__))) {
   async_safe_fatal("__find_icu_symbol should not be called in the linker");
 }
+
+extern "C" int __cxa_type_match() {
+  async_safe_fatal("__cxa_type_match is not implemented in the linker");
+}