Non-SFI NaCl: Fix browser_tests based on libc_free.c

chrome/test/data/nacl/nonsfi/libc_free.c

Index: chrome/test/data/nacl/nonsfi/libc_free.c
diff --git a/chrome/test/data/nacl/nonsfi/libc_free.c b/chrome/test/data/nacl/nonsfi/libc_free.c
index ff3aef032a3e10a55bccddc65b00d5bee4b359af..cc8eb839ab039e564b8046bf45244000743b782c 100644
--- a/chrome/test/data/nacl/nonsfi/libc_free.c
+++ b/chrome/test/data/nacl/nonsfi/libc_free.c
@@ -221,24 +221,17 @@ void _start(uintptr_t info[]) {
 
   /* This is local as a workaround to avoid having to apply
    * relocations to global variables. */
-  struct PP_StartFunctions start_funcs = {
-    MyPPP_InitializeModule,
-    MyPPP_ShutdownModule,
-    MyPPP_GetInterface,
-  };
-  /* Similarly, initialise some global variables, avoiding relocations. */
-  struct PPP_Instance_1_0 local_ppp_instance = {
-    DidCreate,
-    DidDestroy,
-    DidChangeView,
-    DidChangeFocus,
-    HandleDocumentLoad,
-  };
-  ppp_instance = local_ppp_instance;
-  struct PPP_Messaging_1_0 local_ppp_messaging = {
-    HandleMessage,
-  };
-  ppp_messaging = local_ppp_messaging;
+  struct PP_StartFunctions start_funcs;

[hamaji, 2014/07/10 11:32:24]

The initialization of this structure is OK with -Wl,-z,norelro, but I felt it
would be slightly safer to stick with the simplest code.

[Mark Seaborn, 2014/07/10 17:17:45]

I don't think that's right.  I don't think "norelro" can remove the relocations
that the compiler produces.  I think the change to libc_free.c is the part of
the workaround that's effective.

FYI, LLVM's optimiser might still turn this back into the original code.  To be
safer against future compiler changes, you'd need to either:
 * disable optimisations -- less robust
 * make these assignments 'volatile' -- more robust, but not fully
compiler-proof, because the compiler could still feel free to introduce globals
containing relocs.

That's just FYI, so no change to libc_free.c is required.

[hamaji, 2014/07/11 05:16:48]

Acknowledged.

+  start_funcs.PPP_InitializeModule = MyPPP_InitializeModule;
+  start_funcs.PPP_ShutdownModule = MyPPP_ShutdownModule;
+  start_funcs.PPP_GetInterface = MyPPP_GetInterface;
+  /* Similarly, initialize some global variables, avoiding relocations. */
+  ppp_instance.DidCreate = DidCreate;
+  ppp_instance.DidDestroy = DidDestroy;
+  ppp_instance.DidChangeView = DidChangeView;
+  ppp_instance.DidChangeFocus = DidChangeFocus;
+  ppp_instance.HandleDocumentLoad = HandleDocumentLoad;
+  ppp_messaging.HandleMessage = HandleMessage;
 
   ppapihook.ppapi_start(&start_funcs);