Don't generate erroneous fixups from reference to path

The dtb overlay format only permits (non local) fixups to reference labels,
not paths.  That's because the fixup target goes into the property name in
the overlay, and property names aren't permitted to include '/' characters.

Stop erroneously generating such fixups, because we didn't check for this
case.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

livetree.c

@@ -919,6 +919,12 @@ static void add_fixup_entry(struct dt_info *dti, struct node *fn,
 	/* m->ref can only be a REF_PHANDLE, but check anyway */
 	assert(m->type == REF_PHANDLE);
 
+	/* The format only permits fixups for references to label, not
+	 * references to path */
+	if (strchr(m->ref, '/'))
+		die("Can't generate fixup for reference to path &{%s}\n",
+		    m->ref);
+
 	/* there shouldn't be any ':' in the arguments */
 	if (strchr(node->fullpath, ':') || strchr(prop->name, ':'))
 		die("arguments should not contain ':'\n");

tests/fixup-ref-to-path.dts

@@ -0,0 +1,6 @@
+/dts-v1/;
+/plugin/;
+
+/ {
+	prop = < &{/path/to/node} >;
+};

tests/run_tests.sh

@@ -271,6 +271,7 @@ libfdt_overlay_tests () {
 	run_dtc_test -I dts -O dtb -o $tree.test.dtb "$SRCDIR/$tree.dts"
 	run_test overlay_bad_fixup overlay_base_no_symbols.test.dtb $tree.test.dtb
     done
+    run_sh_test "$SRCDIR/dtc-fatal.sh" -I dts -O dtb -o /dev/null fixup-ref-to-path.dts
 }
 
 # Tests to exercise dtc's overlay generation support