Fix reentrant exception handling.

Store handled status in local that is passed into
handler rather than a single thread local value
which can be overwritten in case of reentrance.

Author: joncham

mono/mini/exceptions-amd64.c

@@ -58,7 +58,7 @@ LPTOP_LEVEL_EXCEPTION_FILTER mono_old_win_toplevel_exception_filter;
 void *mono_win_vectored_exception_handle;
 
 #define W32_SEH_HANDLE_EX(_ex) \
-	if (_ex##_handler) _ex##_handler(0, ep, ctx)
+	if (_ex##_handler) _ex##_handler(er->ExceptionCode, &info, ctx)
 
 static LONG CALLBACK seh_unhandled_exception_filter(EXCEPTION_POINTERS* ep)
 {
@@ -137,12 +137,12 @@ LONG CALLBACK seh_vectored_exception_handler(EXCEPTION_POINTERS* ep)
 	LONG res;
 	MonoJitTlsData *jit_tls = mono_tls_get_jit_tls ();
 	MonoDomain* domain = mono_domain_get ();
+	MonoWindowsSigHandlerInfo info = { TRUE, ep };
 
 	/* If the thread is not managed by the runtime return early */
 	if (!jit_tls)
 		return EXCEPTION_CONTINUE_SEARCH;
 
-	jit_tls->mono_win_chained_exception_needs_run = FALSE;
 	res = EXCEPTION_CONTINUE_EXECUTION;
 
 	er = ep->ExceptionRecord;
@@ -159,7 +159,7 @@ LONG CALLBACK seh_vectored_exception_handler(EXCEPTION_POINTERS* ep)
 				ctx->Rip = (guint64)restore_stack;
 			}
 		} else {
-			jit_tls->mono_win_chained_exception_needs_run = TRUE;
+			info.handled = FALSE;
 		}
 		break;
 	case EXCEPTION_ACCESS_VIOLATION:
@@ -177,11 +177,11 @@ LONG CALLBACK seh_vectored_exception_handler(EXCEPTION_POINTERS* ep)
 		W32_SEH_HANDLE_EX(fpe);
 		break;
 	default:
-		jit_tls->mono_win_chained_exception_needs_run = TRUE;
+		info.handled = FALSE;
 		break;
 	}
 
-	if (jit_tls->mono_win_chained_exception_needs_run) {
+	if (!info.handled) {
 		/* Don't copy context back if we chained exception
 		* as the handler may have modfied the EXCEPTION_POINTERS
 		* directly. We don't pass sigcontext to chained handlers.

mono/mini/exceptions-x86.c

@@ -55,7 +55,7 @@ extern int (*gUnhandledExceptionHandler)(EXCEPTION_POINTERS*);
 #endif
 
 #define W32_SEH_HANDLE_EX(_ex) \
-	if (_ex##_handler) _ex##_handler(0, ep, ctx)
+	if (_ex##_handler) _ex##_handler(er->ExceptionCode, &info, ctx)
 
 LONG CALLBACK seh_unhandled_exception_filter(EXCEPTION_POINTERS* ep)
 {
@@ -198,12 +198,12 @@ LONG CALLBACK seh_vectored_exception_handler(EXCEPTION_POINTERS* ep)
 	CONTEXT* ctx;
 	LONG res;
 	MonoJitTlsData *jit_tls = mono_tls_get_jit_tls ();
+	MonoWindowsSigHandlerInfo info = { TRUE, ep };
 
 	/* If the thread is not managed by the runtime return early */
 	if (!jit_tls)
 		return EXCEPTION_CONTINUE_SEARCH;
 
-	jit_tls->mono_win_chained_exception_needs_run = FALSE;
 	res = EXCEPTION_CONTINUE_EXECUTION;
 
 	er = ep->ExceptionRecord;
@@ -228,11 +228,11 @@ LONG CALLBACK seh_vectored_exception_handler(EXCEPTION_POINTERS* ep)
 		W32_SEH_HANDLE_EX(fpe);
 		break;
 	default:
-		jit_tls->mono_win_chained_exception_needs_run = TRUE;
+		info.handled = FALSE;
 		break;
 	}
 
-	if (jit_tls->mono_win_chained_exception_needs_run) {
+	if (!info.handled) {
 		/* Don't copy context back if we chained exception
 		* as the handler may have modfied the EXCEPTION_POINTERS
 		* directly. We don't pass sigcontext to chained handlers.

mono/mini/mini-amd64.h

@@ -7,6 +7,7 @@
 
 #include <mono/arch/amd64/amd64-codegen.h>
 #include <mono/utils/mono-sigcontext.h>
+#include <mono/utils/mono-signal-handler.h>
 #include <mono/utils/mono-context.h>
 #include <glib.h>
 
@@ -32,7 +33,7 @@ struct sigcontext {
 };
 #endif
 
-typedef void (* MonoW32ExceptionHandler) (int _dummy, EXCEPTION_POINTERS *info, void *context);
+typedef void MONO_SIG_HANDLER_SIGNATURE ((*MonoW32ExceptionHandler));
 void win32_seh_init(void);
 void win32_seh_cleanup(void);
 void win32_seh_set_handler(int type, MonoW32ExceptionHandler handler);

mono/mini/mini-runtime.h

@@ -101,11 +101,6 @@ struct MonoJitTlsData {
 	MonoContext orig_ex_ctx;
 	gboolean orig_ex_ctx_set;
 
-	/* 
-	 * Stores if we need to run a chained exception in Windows.
-	 */
-	gboolean mono_win_chained_exception_needs_run;
-
 	/* 
 	 * The current exception in flight
 	 */

mono/mini/mini-windows.c

@@ -255,8 +255,8 @@ mono_runtime_cleanup_handlers (void)
 gboolean
 MONO_SIG_HANDLER_SIGNATURE (mono_chain_signal)
 {
-	MonoJitTlsData *jit_tls = mono_tls_get_jit_tls ();
-	jit_tls->mono_win_chained_exception_needs_run = TRUE;
+	/* Set to FALSE to indicate that vectored exception handling should continue to look for handler */
+	MONO_SIG_HANDLER_GET_INFO ()->handled = FALSE;
 	return TRUE;
 }
 

mono/mini/mini-x86.h

@@ -16,7 +16,7 @@
 #include <signal.h>
 #endif
 
-typedef void (* MonoW32ExceptionHandler) (int _dummy, EXCEPTION_POINTERS *info, void *context);
+typedef void MONO_SIG_HANDLER_SIGNATURE ((*MonoW32ExceptionHandler));
 
 void win32_seh_init(void);
 void win32_seh_cleanup(void);

mono/utils/mono-signal-handler.h

@@ -78,12 +78,20 @@
  */
 
 #ifdef HOST_WIN32
-#define MONO_SIG_HANDLER_SIGNATURE(ftn) ftn (int _dummy, EXCEPTION_POINTERS *_info, void *context)
-#define MONO_SIG_HANDLER_FUNC(access, ftn) MONO_SIGNAL_HANDLER_FUNC (access, ftn, (int _dummy, EXCEPTION_POINTERS *_info, void *context))
+#define MONO_SIG_HANDLER_SIGNATURE(ftn) ftn (int _dummy, MonoWindowsSigHandlerInfo *_info, void *context)
+#define MONO_SIG_HANDLER_FUNC(access, ftn) MONO_SIGNAL_HANDLER_FUNC (access, ftn, (int _dummy, MonoWindowsSigHandlerInfo *_info, void *context))
 #define MONO_SIG_HANDLER_PARAMS _dummy, _info, context
-#define MONO_SIG_HANDLER_GET_SIGNO() (_dummy)
+#define MONO_SIG_HANDLER_GET_SIGNO() (0)
 #define MONO_SIG_HANDLER_GET_INFO() (_info)
-#define MONO_SIG_HANDLER_INFO_TYPE EXCEPTION_POINTERS
+#define MONO_SIG_HANDLER_INFO_TYPE MonoWindowsSigHandlerInfo
+typedef struct {
+	/* Set to FALSE to indicate chained signal handler needs run.
+	 * With vectored exceptions Windows does that for us by returning
+	 * EXCEPTION_CONTINUE_SEARCH from handler */
+	gboolean handled;
+	EXCEPTION_POINTERS* ep;
+} MonoWindowsSigHandlerInfo;
+
 /* seh_vectored_exception_handler () passes in a CONTEXT* */
 #define MONO_SIG_HANDLER_GET_CONTEXT \
     void *ctx = context;