scripts: support multiple objects in running image

Since we're loading multiple objects, we need to load symbol tables for all
of them.  The base addresses are no longer static (esp. after we started
loading mulitple payloads, so we need to read them from the image).

A new command is added for this: 'osv syms'.  It will try to locate symbol
tables for anything that has been loaded at this stage.

scripts/loader.py

@@ -2,30 +2,39 @@
 
 import gdb
 import re
-import os
+import os, os.path
 
-args = ''
-text_addr = '?'
-libjvm = '/usr/lib/jvm/java-1.7.0-openjdk.x86_64/jre/lib/amd64/server/libjvm.so'
-unwanted_sections = ['.text',
-                     '.note.stapsdt',
-                     '.gnu_debuglink',
-                     '.gnu_debugdata',
-                     '.shstrtab',
-                     ]
-for line in os.popen('readelf -WS ' + libjvm):
-    m = re.match(r'\s*\[ *\d+\]\s+([\.\w\d_]+)\s+\w+\s+([0-9a-f]+).*', line)
-    if m:
-        section = m.group(1)
-        if section == 'NULL':
-            continue
-        addr = hex(int(m.group(2), 16) + 0x100000000000)
-        if section == '.text':
-            text_addr = addr
-        if section not in unwanted_sections:
-            args += ' -s %s %s' % (section, addr)
+def load_elf(path, base):
+    args = ''
+    text_addr = '?'
+    unwanted_sections = ['.text',
+                         '.note.stapsdt',
+                         '.gnu_debuglink',
+                         '.gnu_debugdata',
+                         '.shstrtab',
+                         ]
+    for line in os.popen('readelf -WS ' + path):
+        m = re.match(r'\s*\[ *\d+\]\s+([\.\w\d_]+)\s+\w+\s+([0-9a-f]+).*', line)
+        if m:
+            section = m.group(1)
+            if section == 'NULL':
+                continue
+            addr = hex(int(m.group(2), 16) + base)
+            if section == '.text':
+                text_addr = addr
+            if section not in unwanted_sections:
+                args += ' -s %s %s' % (section, addr)
 
-gdb.execute('add-symbol-file %s %s %s' % (libjvm, text_addr, args))
+    gdb.execute('add-symbol-file %s %s %s' % (path, text_addr, args))
+
+def translate(path):
+    '''given a path, try to find it on the host OS'''
+    name = os.path.basename(path)
+    for top in ['build/debug', 'external', '/usr']:
+        for root, dirs, files in os.walk(top):
+            if name in files:
+                return os.path.join(root, name)
+    return None
 
 class Connect(gdb.Command):
     '''Connect to a local kvm instance at port :1234'''
@@ -62,5 +71,22 @@ class osv_heap(gdb.Command):
         print page_range, page_range['size']
         self.show(node['right_'])
 
+class osv_syms(gdb.Command):
+    def __init__(self):
+        gdb.Command.__init__(self, 'osv syms',
+                             gdb.COMMAND_USER, gdb.COMPLETE_NONE)
+    def invoke(self, arg, from_tty):
+        p = gdb.lookup_global_symbol('elf::program::s_objs').value()
+        p = p.dereference().address
+        while long(p.dereference()):
+            obj = p.dereference().dereference()
+            base = long(obj['_base'])
+            path = obj['_pathname']['_M_dataplus']['_M_p'].string()
+            path = translate(path)
+            print path, hex(base)
+            load_elf(path, base)
+            p += 1
+
 osv()
 osv_heap()
+osv_syms()