runtime: support SetUnhandledExceptionFilter on Windows

The Windows unhandled exception mechanism fails to call the callback
set in SetUnhandledExceptionFilter if the stack can't be correctly
unwound.

Some cgo glue code was not properly chaining the frame pointer, making
the stack unwind to fail in case of an exception inside a cgo call.
This CL fix that and adds a test case to avoid regressions.

Fixes #50951

Change-Id: Ic782b5257fe90b05e3def8dbf0bb8d4ed37a190b
Reviewed-on: https://go-review.googlesource.com/c/go/+/525475
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Quim Muntal <quimmuntal@gmail.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

1 files changed, 19 insertions, 1 deletions

diff --git a/src/runtime/testdata/testwinlib/main.c b/src/runtime/testdata/testwinlib/main.c
index 55ee6571d7..e9b5946a31 100644
--- a/src/runtime/testdata/testwinlib/main.c
+++ b/src/runtime/testdata/testwinlib/main.c
@@ -4,6 +4,8 @@
 
 int exceptionCount;
 int continueCount;
+int unhandledCount;
+
 LONG WINAPI customExceptionHandlder(struct _EXCEPTION_POINTERS *ExceptionInfo)
 {
     if (ExceptionInfo->ExceptionRecord->ExceptionCode == EXCEPTION_BREAKPOINT)
@@ -20,7 +22,10 @@ LONG WINAPI customExceptionHandlder(struct _EXCEPTION_POINTERS *ExceptionInfo)
 #else
         c->Pc = c->Lr;
 #endif
+#ifdef _ARM64_
+        // TODO: remove when windows/arm64 supports SEH stack unwinding.
         return EXCEPTION_CONTINUE_EXECUTION;
+#endif
     }
     return EXCEPTION_CONTINUE_SEARCH;
 }
@@ -29,6 +34,14 @@ LONG WINAPI customContinueHandlder(struct _EXCEPTION_POINTERS *ExceptionInfo)
     if (ExceptionInfo->ExceptionRecord->ExceptionCode == EXCEPTION_BREAKPOINT)
     {
         continueCount++;
+    }
+    return EXCEPTION_CONTINUE_SEARCH;
+}
+
+LONG WINAPI unhandledExceptionHandler(struct _EXCEPTION_POINTERS *ExceptionInfo) {
+    if (ExceptionInfo->ExceptionRecord->ExceptionCode == EXCEPTION_BREAKPOINT)
+    {
+        unhandledCount++;
         return EXCEPTION_CONTINUE_EXECUTION;
     }
     return EXCEPTION_CONTINUE_SEARCH;
@@ -58,10 +71,15 @@ int main()
         fflush(stdout);
         return 2;
     }
+    void *prevUnhandledHandler = SetUnhandledExceptionFilter(unhandledExceptionHandler);
     CallMeBack(throwFromC);
     RemoveVectoredContinueHandler(continueHandlerHandle);
     RemoveVectoredExceptionHandler(exceptionHandlerHandle);
-    printf("exceptionCount: %d\ncontinueCount: %d\n", exceptionCount, continueCount);
+    if (prevUnhandledHandler != NULL)
+    {
+        SetUnhandledExceptionFilter(prevUnhandledHandler);
+    }
+    printf("exceptionCount: %d\ncontinueCount: %d\nunhandledCount: %d\n", exceptionCount, continueCount, unhandledCount);
     fflush(stdout);
     return 0;
 }