Allow the unwind functions int libgcc_s to interact correctly with libthr.

_Unwind_ForcedUnwind in libgcc_s takes as one of it's parameters a stop
function to tell it when to stop unwinding. One of the stop function's
parameters is a _Unwind_Exception_Class. On most architectures this is an
int64_t, however on ARM EABI the gcc developers have made this a char array
with 8 items. While both of these take the same space they are passed into
the stop function differently, an int64_t is passed in in registers r2 and
r3, while the char[8] is passed in as a pointer to the first item in
register r2.

Because libthr expects the value to be an int64_t we would get incorrect
results when it passes a function that take an int64_t but libgcc passes in
a pointer to a char array including crashing.

The fix is to update libgcc_s to make it pass an int64_t to the stop
function and to libstdc++ as it expects _Unwind_Exception_Class to be an
array.

1 files changed, 11 insertions, 9 deletions

diff --git a/contrib/libstdc++/libsupc++/unwind-cxx.h b/contrib/libstdc++/libsupc++/unwind-cxx.h
index c5636556..523c054 100644
--- a/contrib/libstdc++/libsupc++/unwind-cxx.h
+++ b/contrib/libstdc++/libsupc++/unwind-cxx.h
@@ -173,7 +173,7 @@ __get_exception_header_from_ue (_Unwind_Exception *exc)
   return reinterpret_cast<__cxa_exception *>(exc + 1) - 1;
 }
 
-#ifdef __ARM_EABI_UNWINDER__
+#if defined(__ARM_EABI_UNWINDER__) && !defined(__FreeBSD__)
 static inline bool
 __is_gxx_exception_class(_Unwind_Exception_Class c)
 {
@@ -200,13 +200,7 @@ __GXX_INIT_EXCEPTION_CLASS(_Unwind_Exception_Class c)
   c[6] = '+';
   c[7] = '\0';
 }
-
-static inline void*
-__gxx_caught_object(_Unwind_Exception* eo)
-{
-  return (void*)eo->barrier_cache.bitpattern[0];
-}
-#else // !__ARM_EABI_UNWINDER__
+#else // !__ARM_EABI_UNWINDER__ || __FreeBSD__
 // This is the exception class we report -- "GNUCC++\0".
 const _Unwind_Exception_Class __gxx_exception_class
 = ((((((((_Unwind_Exception_Class) 'G' 
@@ -223,8 +217,16 @@ __is_gxx_exception_class(_Unwind_Exception_Class c)
 {
   return c == __gxx_exception_class;
 }
-
 #define __GXX_INIT_EXCEPTION_CLASS(c) c = __gxx_exception_class
+#endif
+
+#ifdef __ARM_EABI_UNWINDER__
+static inline void*
+__gxx_caught_object(_Unwind_Exception* eo)
+{
+  return (void*)eo->barrier_cache.bitpattern[0];
+}
+#else // !__ARM_EABI_UNWINDER__
 
 // GNU C++ personality routine, Version 0.
 extern "C" _Unwind_Reason_Code __gxx_personality_v0