server: Only update the modified parts of the context on thread suspend.

dlls/ntdll/exception.c

@@ -110,6 +110,7 @@ void wait_suspend( CONTEXT *context )
     LARGE_INTEGER timeout;
     int saved_errno = errno;
     context_t server_context;
+    DWORD flags = context->ContextFlags;
 
     context_to_server( &server_context, context );
 
@@ -130,10 +131,14 @@ void wait_suspend( CONTEXT *context )
     {
         wine_server_set_reply( req, &server_context, sizeof(server_context) );
         wine_server_call( req );
+        if (wine_server_reply_size( reply ))
+        {
+            context_from_server( context, &server_context );
+            context->ContextFlags |= flags;  /* unchanged registers are still available */
+        }
     }
     SERVER_END_REQ;
 
-    context_from_server( context, &server_context );
     errno = saved_errno;
 }
 

include/wine/server_protocol.h

@@ -6496,6 +6496,6 @@ union generic_reply
     struct terminate_job_reply terminate_job_reply;
 };
 
-#define SERVER_PROTOCOL_VERSION 547
+#define SERVER_PROTOCOL_VERSION 548
 
 #endif /* __WINE_WINE_SERVER_PROTOCOL_H */

server/thread.c

@@ -1715,7 +1715,10 @@ DECL_HANDLER(get_suspend_context)
 
     if (current->suspend_context)
     {
-        set_reply_data_ptr( current->suspend_context, sizeof(context_t) );
+        if (current->suspend_context->flags)
+            set_reply_data_ptr( current->suspend_context, sizeof(context_t) );
+        else
+            free( current->suspend_context );
         if (current->context == current->suspend_context)
         {
             current->context = NULL;
@@ -1745,6 +1748,7 @@ DECL_HANDLER(set_suspend_context)
     else if ((current->suspend_context = mem_alloc( sizeof(context_t) )))
     {
         memcpy( current->suspend_context, get_req_data(), sizeof(context_t) );
+        current->suspend_context->flags = 0;  /* to keep track of what is modified */
         current->context = current->suspend_context;
         if (current->debug_break) break_thread( current );
     }