[threads] Remove mono_threads_suspend_needs_abort_syscall (#4450)

[mono.git] / mono / utils / mono-threads-windows.c

diff --git a/mono/utils/mono-threads-windows.c b/mono/utils/mono-threads-windows.c
index f3f160b30c93e2a0146638caff40639a338b45f7..91ce0f6ea4942b68469d657111245c025499675e 100644 (file)
--- a/mono/utils/mono-threads-windows.c
+++ b/mono/utils/mono-threads-windows.c
@@ -94,12 +94,6 @@ mono_threads_suspend_abort_syscall (MonoThreadInfo *info)
        CloseHandle (handle);
 }
 
-gboolean
-mono_threads_suspend_needs_abort_syscall (void)
-{
-       return TRUE;
-}
-
 gboolean
 mono_threads_suspend_begin_async_resume (MonoThreadInfo *info)
 {
@@ -289,6 +283,56 @@ mono_threads_platform_get_stack_bounds (guint8 **staddr, size_t *stsize)
 
 }
 
+#if SIZEOF_VOID_P == 4 && G_HAVE_API_SUPPORT(HAVE_CLASSIC_WINAPI_SUPPORT)
+typedef BOOL (WINAPI *LPFN_ISWOW64PROCESS) (HANDLE, PBOOL);
+static gboolean is_wow64 = FALSE;
+#endif
+
+/* We do this at init time to avoid potential races with module opening */
+void
+mono_threads_platform_init (void)
+{
+#if SIZEOF_VOID_P == 4 && G_HAVE_API_SUPPORT(HAVE_CLASSIC_WINAPI_SUPPORT)
+       LPFN_ISWOW64PROCESS is_wow64_func = (LPFN_ISWOW64PROCESS) GetProcAddress (GetModuleHandle (TEXT ("kernel32")), "IsWow64Process");
+       if (is_wow64_func)
+               is_wow64_func (GetCurrentProcess (), &is_wow64);
+#endif
+}
+
+/*
+ * When running x86 process under x64 system syscalls are done through WoW64. This
+ * needs to do a transition from x86 mode to x64 so it can syscall into the x64 system.
+ * Apparently this transition invalidates the ESP that we would get from calling
+ * GetThreadContext, so we would fail to scan parts of the thread stack. We attempt
+ * to query whether the thread is in such a transition so we try to restart it later.
+ * We check CONTEXT_EXCEPTION_ACTIVE for this, which is highly undocumented.
+ */
+gboolean
+mono_threads_platform_in_critical_region (MonoNativeThreadId tid)
+{
+       gboolean ret = FALSE;
+#if SIZEOF_VOID_P == 4 && G_HAVE_API_SUPPORT(HAVE_CLASSIC_WINAPI_SUPPORT)
+/* FIXME On cygwin these are not defined */
+#if defined(CONTEXT_EXCEPTION_REQUEST) && defined(CONTEXT_EXCEPTION_REPORTING) && defined(CONTEXT_EXCEPTION_ACTIVE)
+       if (is_wow64) {
+               HANDLE handle = OpenThread (THREAD_ALL_ACCESS, FALSE, tid);
+               if (handle) {
+                       CONTEXT context;
+                       ZeroMemory (&context, sizeof (CONTEXT));
+                       context.ContextFlags = CONTEXT_EXCEPTION_REQUEST;
+                       if (GetThreadContext (handle, &context)) {
+                               if ((context.ContextFlags & CONTEXT_EXCEPTION_REPORTING) &&
+                                               (context.ContextFlags & CONTEXT_EXCEPTION_ACTIVE))
+                                       ret = TRUE;
+                       }
+                       CloseHandle (handle);
+               }
+       }
+#endif
+#endif
+       return ret;
+}
+
 gboolean
 mono_threads_platform_yield (void)
 {