gdb tools: mount command

support mount command in gdb, print mount information
test result:
/bin type binfs
/data type hostfs
/etc type romfs
/proc type procfs
/resource type hostfs
/tmp type tmpfs

Signed-off-by: zhengyu9 <zhengyu9@xiaomi.com>

tools/gdb/fs.py

@@ -0,0 +1,59 @@
+############################################################################
+# tools/gdb/fs.py
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.  The
+# ASF licenses this file to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance with the
+# License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+############################################################################
+
+import gdb
+import utils
+
+FSNODEFLAG_TYPE_MASK = utils.get_symbol_value("FSNODEFLAG_TYPE_MASK")
+FSNODEFLAG_TYPE_MOUNTPT = utils.get_symbol_value("FSNODEFLAG_TYPE_MOUNTPT")
+
+
+def get_inode_name(inode):
+    ptr = inode["i_name"].cast(gdb.lookup_type("char").pointer())
+    return ptr.string()
+
+
+def foreach_inode(handler, root=None, path=""):
+    node = root if root else gdb.parse_and_eval("g_root_inode")["i_child"]
+    while node:
+        newpath = path + "/" + get_inode_name(node)
+        handler(node, newpath)
+        if node["i_child"]:
+            foreach_inode(handler, node["i_child"], newpath)
+        node = node["i_peer"]
+
+
+class Mount(gdb.Command):
+    def __init__(self):
+        super(Mount, self).__init__("mount", gdb.COMMAND_USER)
+
+    def mountpt_filter(self, node, path):
+        if node["i_flags"] & FSNODEFLAG_TYPE_MASK == FSNODEFLAG_TYPE_MOUNTPT:
+            statfs = node["u"]["i_mops"]["statfs"]
+            funcname = gdb.block_for_pc(int(statfs)).function.print_name
+            fstype = funcname.split("_")[0]
+            gdb.write("  %s type %s\n" % (path, fstype))
+
+    def invoke(self, args, from_tty):
+        foreach_inode(self.mountpt_filter)
+
+
+if not utils.get_symbol_value("CONFIG_DISABLE_MOUNTPOINT"):
+    Mount()