190 lines
6.9 KiB
Python
190 lines
6.9 KiB
Python
#
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# gdb helper commands and functions for Linux kernel debugging
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#
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# load kernel and module symbols
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#
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# Copyright (c) Siemens AG, 2011-2013
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#
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# Authors:
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# Jan Kiszka <jan.kiszka@siemens.com>
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#
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# This work is licensed under the terms of the GNU GPL version 2.
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#
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import gdb
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import os
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import re
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from linux import modules, utils
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if hasattr(gdb, 'Breakpoint'):
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class LoadModuleBreakpoint(gdb.Breakpoint):
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def __init__(self, spec, gdb_command):
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super(LoadModuleBreakpoint, self).__init__(spec, internal=True)
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self.silent = True
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self.gdb_command = gdb_command
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def stop(self):
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module = gdb.parse_and_eval("mod")
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module_name = module['name'].string()
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cmd = self.gdb_command
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# enforce update if object file is not found
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cmd.module_files_updated = False
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# Disable pagination while reporting symbol (re-)loading.
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# The console input is blocked in this context so that we would
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# get stuck waiting for the user to acknowledge paged output.
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show_pagination = gdb.execute("show pagination", to_string=True)
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pagination = show_pagination.endswith("on.\n")
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gdb.execute("set pagination off")
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if module_name in cmd.loaded_modules:
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gdb.write("refreshing all symbols to reload module "
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"'{0}'\n".format(module_name))
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cmd.load_all_symbols()
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else:
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cmd.load_module_symbols(module)
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# restore pagination state
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gdb.execute("set pagination %s" % ("on" if pagination else "off"))
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return False
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class LxSymbols(gdb.Command):
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"""(Re-)load symbols of Linux kernel and currently loaded modules.
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The kernel (vmlinux) is taken from the current working directly. Modules (.ko)
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are scanned recursively, starting in the same directory. Optionally, the module
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search path can be extended by a space separated list of paths passed to the
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lx-symbols command."""
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module_paths = []
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module_files = []
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module_files_updated = False
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loaded_modules = []
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breakpoint = None
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def __init__(self):
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super(LxSymbols, self).__init__("lx-symbols", gdb.COMMAND_FILES,
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gdb.COMPLETE_FILENAME)
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def _update_module_files(self):
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self.module_files = []
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for path in self.module_paths:
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gdb.write("scanning for modules in {0}\n".format(path))
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for root, dirs, files in os.walk(path):
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for name in files:
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if name.endswith(".ko") or name.endswith(".ko.debug"):
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self.module_files.append(root + "/" + name)
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self.module_files_updated = True
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def _get_module_file(self, module_name):
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module_pattern = ".*/{0}\.ko(?:.debug)?$".format(
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module_name.replace("_", r"[_\-]"))
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for name in self.module_files:
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if re.match(module_pattern, name) and os.path.exists(name):
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return name
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return None
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def _section_arguments(self, module):
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try:
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sect_attrs = module['sect_attrs'].dereference()
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except gdb.error:
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return ""
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attrs = sect_attrs['attrs']
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section_name_to_address = {
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attrs[n]['battr']['attr']['name'].string(): attrs[n]['address']
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for n in range(int(sect_attrs['nsections']))}
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args = []
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for section_name in [".data", ".data..read_mostly", ".rodata", ".bss",
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".text", ".text.hot", ".text.unlikely"]:
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address = section_name_to_address.get(section_name)
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if address:
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args.append(" -s {name} {addr}".format(
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name=section_name, addr=str(address)))
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return "".join(args)
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def load_module_symbols(self, module):
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module_name = module['name'].string()
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module_addr = str(module['core_layout']['base']).split()[0]
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module_file = self._get_module_file(module_name)
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if not module_file and not self.module_files_updated:
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self._update_module_files()
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module_file = self._get_module_file(module_name)
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if module_file:
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if utils.is_target_arch('s390'):
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# Module text is preceded by PLT stubs on s390.
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module_arch = module['arch']
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plt_offset = int(module_arch['plt_offset'])
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plt_size = int(module_arch['plt_size'])
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module_addr = hex(int(module_addr, 0) + plt_offset + plt_size)
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gdb.write("loading @{addr}: {filename}\n".format(
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addr=module_addr, filename=module_file))
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cmdline = "add-symbol-file {filename} {addr}{sections}".format(
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filename=module_file,
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addr=module_addr,
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sections=self._section_arguments(module))
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gdb.execute(cmdline, to_string=True)
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if module_name not in self.loaded_modules:
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self.loaded_modules.append(module_name)
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else:
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gdb.write("no module object found for '{0}'\n".format(module_name))
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def load_all_symbols(self):
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gdb.write("loading vmlinux\n")
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# Dropping symbols will disable all breakpoints. So save their states
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# and restore them afterward.
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saved_states = []
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if hasattr(gdb, 'breakpoints') and not gdb.breakpoints() is None:
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for bp in gdb.breakpoints():
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saved_states.append({'breakpoint': bp, 'enabled': bp.enabled})
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# drop all current symbols and reload vmlinux
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orig_vmlinux = 'vmlinux'
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for obj in gdb.objfiles():
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if (obj.filename.endswith('vmlinux') or
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obj.filename.endswith('vmlinux.debug')):
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orig_vmlinux = obj.filename
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gdb.execute("symbol-file", to_string=True)
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gdb.execute("symbol-file {0}".format(orig_vmlinux))
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self.loaded_modules = []
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module_list = modules.module_list()
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if not module_list:
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gdb.write("no modules found\n")
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else:
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[self.load_module_symbols(module) for module in module_list]
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for saved_state in saved_states:
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saved_state['breakpoint'].enabled = saved_state['enabled']
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def invoke(self, arg, from_tty):
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self.module_paths = [os.path.abspath(os.path.expanduser(p))
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for p in arg.split()]
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self.module_paths.append(os.getcwd())
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# enforce update
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self.module_files = []
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self.module_files_updated = False
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self.load_all_symbols()
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if hasattr(gdb, 'Breakpoint'):
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if self.breakpoint is not None:
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self.breakpoint.delete()
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self.breakpoint = None
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self.breakpoint = LoadModuleBreakpoint(
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"kernel/module/main.c:do_init_module", self)
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else:
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gdb.write("Note: symbol update on module loading not supported "
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"with this gdb version\n")
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LxSymbols()
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