stubdom/grub: avoid relying on start_info definition

The kexec() function of grub-pv is relying on the exact definition of
start_info from Mini-OS by having an "#undef start_info" and a few
lines later a copy of the Mini-OS definition again.

This is bad practice by making all attempts of Mini-OS to change that
definition impossible.

Avoid that dependency by moving the code fragment in question to the
very end of the source file, allowing to drop the copy of the
definition.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>

stubdom/grub/kexec.c

@@ -209,6 +209,8 @@ static void tpm_hash2pcr(struct xc_dom_image *dom, char *cmdline)
 	shutdown_tpmfront(tpm);
 }
 
+static void call_start_info_hook(struct xc_dom_image *dom);
+
 void kexec(void *kernel, long kernel_size, void *module, long module_size, char *cmdline, unsigned long flags)
 {
     struct xc_dom_image *dom;
@@ -330,10 +332,7 @@ void kexec(void *kernel, long kernel_size, void *module, long module_size, char
         }
 
     /* start info page */
-#undef start_info
-    if ( dom->arch_hooks->start_info )
-        dom->arch_hooks->start_info(dom);
-#define start_info (start_info_union.start_info)
+    call_start_info_hook(dom);
 
     xc_dom_log_memory_footprint(dom);
 
@@ -432,3 +431,11 @@ out:
     allocated = 0;
     xc_interface_close(xc_handle );
 }
+
+/* No references to start_info of Mini-OS after this function. */
+static void call_start_info_hook(struct xc_dom_image *dom)
+{
+#undef start_info
+    if ( dom->arch_hooks->start_info )
+        dom->arch_hooks->start_info(dom);
+}