[PATCH] Cygwin: main exception handler (64-bit): continue GCC exceptions
Ken Brown
kbrown@cornell.edu
Mon Aug 17 20:44:36 GMT 2020
This is necessary in order to be consistent with the following comment
in the definition of _Unwind_RaiseException() in the GCC source file
libgcc/unwind-seh.c:
The exception handler installed in crt0 will continue any GCC
exception that reaches there (and isn't marked non-continuable).
Previously we failed to do this and, as a consequence, the C++ runtime
didn't call std::terminate after an unhandled exception.
This fixes the problem reported here:
https://sourceware.org/pipermail/cygwin/2020-August/245897.html
---
winsup/cygwin/exceptions.cc | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/winsup/cygwin/exceptions.cc b/winsup/cygwin/exceptions.cc
index 0d9e8f70e..f8da7529b 100644
--- a/winsup/cygwin/exceptions.cc
+++ b/winsup/cygwin/exceptions.cc
@@ -647,6 +647,17 @@ exception::handle (EXCEPTION_RECORD *e, exception_list *frame, CONTEXT *in,
if (exit_state || e->ExceptionFlags)
return ExceptionContinueSearch;
+/* From the GCC source file libgcc/unwind-seh.c. */
+#ifdef __x86_64__
+#define STATUS_USER_DEFINED (1U << 29)
+#define GCC_MAGIC (('G' << 16) | ('C' << 8) | 'C')
+#define GCC_EXCEPTION(TYPE) \
+ (STATUS_USER_DEFINED | ((TYPE) << 24) | GCC_MAGIC)
+#define STATUS_GCC_THROW GCC_EXCEPTION (0)
+#define STATUS_GCC_UNWIND GCC_EXCEPTION (1)
+#define STATUS_GCC_FORCED GCC_EXCEPTION (2)
+#endif
+
siginfo_t si = {};
si.si_code = SI_KERNEL;
/* Coerce win32 value to posix value. */
@@ -762,6 +773,16 @@ exception::handle (EXCEPTION_RECORD *e, exception_list *frame, CONTEXT *in,
handling. */
return ExceptionContinueExecution;
+#ifdef __x86_64__
+ /* According to a comment in the GCC function
+ _Unwind_RaiseException(), GCC expects us to continue all the
+ (continuable) GCC exceptions that reach us. */
+ case STATUS_GCC_THROW:
+ case STATUS_GCC_UNWIND:
+ case STATUS_GCC_FORCED:
+ return ExceptionContinueExecution;
+#endif
+
default:
/* If we don't recognize the exception, we have to assume that
we are doing structured exception handling, and we let
--
2.28.0
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