powerpc/powernv: Use common code for the symbol_map export

Long before we had a generic way for firmware to export memory ranges of
interest we added a special case for the skiboot symbol map. The code is
pretty much identical to the generic export so re-use the code.
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191101062611.32610-2-oohall@gmail.com

arch/powerpc/platforms/powernv/opal.c

@@ -790,42 +790,6 @@ static int opal_sysfs_init(void)
 	return 0;
 }
 
-static ssize_t symbol_map_read(struct file *fp, struct kobject *kobj,
-			       struct bin_attribute *bin_attr,
-			       char *buf, loff_t off, size_t count)
-{
-	return memory_read_from_buffer(buf, count, &off, bin_attr->private,
-				       bin_attr->size);
-}
-
-static struct bin_attribute symbol_map_attr = {
-	.attr = {.name = "symbol_map", .mode = 0400},
-	.read = symbol_map_read
-};
-
-static void opal_export_symmap(void)
-{
-	const __be64 *syms;
-	unsigned int size;
-	struct device_node *fw;
-	int rc;
-
-	fw = of_find_node_by_path("/ibm,opal/firmware");
-	if (!fw)
-		return;
-	syms = of_get_property(fw, "symbol-map", &size);
-	if (!syms || size != 2 * sizeof(__be64))
-		return;
-
-	/* Setup attributes */
-	symbol_map_attr.private = __va(be64_to_cpu(syms[0]));
-	symbol_map_attr.size = be64_to_cpu(syms[1]);
-
-	rc = sysfs_create_bin_file(opal_kobj, &symbol_map_attr);
-	if (rc)
-		pr_warn("Error %d creating OPAL symbols file\n", rc);
-}
-
 static ssize_t export_attr_read(struct file *fp, struct kobject *kobj,
 				struct bin_attribute *bin_attr, char *buf,
 				loff_t off, size_t count)
@@ -914,6 +878,7 @@ static void opal_export_attrs(void)
 {
 	struct device_node *np;
 	struct kobject *kobj;
+	int rc;
 
 	np = of_find_node_by_path("/ibm,opal/firmware/exports");
 	if (!np)
@@ -928,6 +893,15 @@ static void opal_export_attrs(void)
 
 	opal_add_exported_attrs(np, kobj);
 
+	/*
+	 * NB: symbol_map existed before the generic export interface so it
+	 * lives under the top level opal_kobj.
+	 */
+	rc = opal_add_one_export(opal_kobj, "symbol_map",
+				 np->parent, "symbol-map");
+	if (rc)
+		pr_warn("Error %d creating OPAL symbols file\n", rc);
+
 	of_node_put(np);
 }
 
@@ -1073,8 +1047,6 @@ static int __init opal_init(void)
 	/* Create "opal" kobject under /sys/firmware */
 	rc = opal_sysfs_init();
 	if (rc == 0) {
-		/* Export symbol map to userspace */
-		opal_export_symmap();
 		/* Setup dump region interface */
 		opal_dump_region_init();
 		/* Setup error log interface */