thermosphere: implement reading and writing guest memory

thermosphere/src/execute_function.c

@@ -25,7 +25,7 @@ void executeFunctionOnCores(ExecutedFunction fun, void *args, bool sync, u32 cor
     currentCoreCtx->executedFunction = fun;
     currentCoreCtx->executedFunctionArgs = args;
     currentCoreCtx->executedFunctionSync = sync;
-
+    __compiler_barrier();
     generateSgiForList(ThermosphereSgi_ExecuteFunction, coreList);
 }
 
@@ -46,4 +46,4 @@ void executeFunctionInterruptHandler(u32 srcCore)
     if (ctx->executedFunctionSync) {
         barrierWait(&ctx->executedFunctionBarrier);
     }
-}
+}