diff options
Diffstat (limited to 'scripts/gdb/linux/symbols.py')
| -rw-r--r-- | scripts/gdb/linux/symbols.py | 338 |
1 files changed, 338 insertions, 0 deletions
diff --git a/scripts/gdb/linux/symbols.py b/scripts/gdb/linux/symbols.py new file mode 100644 index 000000000000..d4308b726183 --- /dev/null +++ b/scripts/gdb/linux/symbols.py @@ -0,0 +1,338 @@ +# +# gdb helper commands and functions for Linux kernel debugging +# +# load kernel and module symbols +# +# Copyright (c) Siemens AG, 2011-2013 +# +# Authors: +# Jan Kiszka <jan.kiszka@siemens.com> +# +# This work is licensed under the terms of the GNU GPL version 2. +# + +import atexit +import gdb +import os +import re +import struct + +from itertools import count +from linux import bpf, constants, modules, utils + + +if hasattr(gdb, 'Breakpoint'): + class LoadModuleBreakpoint(gdb.Breakpoint): + def __init__(self, spec, gdb_command): + super(LoadModuleBreakpoint, self).__init__(spec, internal=True) + self.silent = True + self.gdb_command = gdb_command + + def stop(self): + module = gdb.parse_and_eval("mod") + module_name = module['name'].string() + cmd = self.gdb_command + + # enforce update if object file is not found + cmd.module_files_updated = False + + # Disable pagination while reporting symbol (re-)loading. + # The console input is blocked in this context so that we would + # get stuck waiting for the user to acknowledge paged output. + with utils.pagination_off(): + if module_name in cmd.loaded_modules: + gdb.write("refreshing all symbols to reload module " + "'{0}'\n".format(module_name)) + cmd.load_all_symbols() + else: + cmd.load_module_symbols(module) + + return False + + +def get_vmcore_s390(): + with utils.qemu_phy_mem_mode(): + vmcore_info = 0x0e0c + paddr_vmcoreinfo_note = gdb.parse_and_eval("*(unsigned long long *)" + + hex(vmcore_info)) + if paddr_vmcoreinfo_note == 0 or paddr_vmcoreinfo_note & 1: + # In the early boot case, extract vm_layout.kaslr_offset from the + # vmlinux image in physical memory. + if paddr_vmcoreinfo_note == 0: + kaslr_offset_phys = 0 + else: + kaslr_offset_phys = paddr_vmcoreinfo_note - 1 + with utils.pagination_off(): + gdb.execute("symbol-file {0} -o {1}".format( + utils.get_vmlinux(), hex(kaslr_offset_phys))) + kaslr_offset = gdb.parse_and_eval("vm_layout.kaslr_offset") + return "KERNELOFFSET=" + hex(kaslr_offset)[2:] + inferior = gdb.selected_inferior() + elf_note = inferior.read_memory(paddr_vmcoreinfo_note, 12) + n_namesz, n_descsz, n_type = struct.unpack(">III", elf_note) + desc_paddr = paddr_vmcoreinfo_note + len(elf_note) + n_namesz + 1 + return gdb.parse_and_eval("(char *)" + hex(desc_paddr)).string() + + +def get_kerneloffset(): + if utils.is_target_arch('s390'): + try: + vmcore_str = get_vmcore_s390() + except gdb.error as e: + gdb.write("{}\n".format(e)) + return None + return utils.parse_vmcore(vmcore_str).kerneloffset + return None + + +def is_in_s390_decompressor(): + # DAT is always off in decompressor. Use this as an indicator. + # Note that in the kernel, DAT can be off during kexec() or restart. + # Accept this imprecision in order to avoid complicating things. + # It is unlikely that someone will run lx-symbols at these points. + pswm = int(gdb.parse_and_eval("$pswm")) + return (pswm & 0x0400000000000000) == 0 + + +def skip_decompressor(): + if utils.is_target_arch("s390"): + if is_in_s390_decompressor(): + # The address of the jump_to_kernel function is statically placed + # into svc_old_psw.addr (see ipl_data.c); read it from there. DAT + # is off, so we do not need to care about lowcore relocation. + svc_old_pswa = 0x148 + jump_to_kernel = int(gdb.parse_and_eval("*(unsigned long long *)" + + hex(svc_old_pswa))) + gdb.execute("tbreak *" + hex(jump_to_kernel)) + gdb.execute("continue") + while is_in_s390_decompressor(): + gdb.execute("stepi") + + +class LxSymbols(gdb.Command): + """(Re-)load symbols of Linux kernel and currently loaded modules. + +The kernel (vmlinux) is taken from the current working directly. Modules (.ko) +are scanned recursively, starting in the same directory. Optionally, the module +search path can be extended by a space separated list of paths passed to the +lx-symbols command. + +When the -bpf flag is specified, symbols from the currently loaded BPF programs +are loaded as well.""" + + module_paths = [] + module_files = [] + module_files_updated = False + loaded_modules = [] + breakpoint = None + bpf_prog_monitor = None + bpf_ksym_monitor = None + bpf_progs = {} + # The remove-symbol-file command, even when invoked with -a, requires the + # respective object file to exist, so keep them around. + bpf_debug_objs = {} + + def __init__(self): + super(LxSymbols, self).__init__("lx-symbols", gdb.COMMAND_FILES, + gdb.COMPLETE_FILENAME) + atexit.register(self.cleanup_bpf) + + def _update_module_files(self): + self.module_files = [] + for path in self.module_paths: + gdb.write("scanning for modules in {0}\n".format(path)) + for root, dirs, files in os.walk(path): + for name in files: + if name.endswith(".ko") or name.endswith(".ko.debug"): + self.module_files.append(root + "/" + name) + self.module_files_updated = True + + def _get_module_file(self, module_name): + module_pattern = r".*/{0}\.ko(?:.debug)?$".format( + module_name.replace("_", r"[_\-]")) + for name in self.module_files: + if re.match(module_pattern, name) and os.path.exists(name): + return name + return None + + def _section_arguments(self, module, module_addr): + try: + sect_attrs = module['sect_attrs'].dereference() + except gdb.error: + return str(module_addr) + + section_name_to_address = {} + for i in count(): + # this is a NULL terminated array + if sect_attrs['grp']['bin_attrs'][i] == 0x0: + break + + attr = sect_attrs['grp']['bin_attrs'][i].dereference() + section_name_to_address[attr['attr']['name'].string()] = attr['private'] + + textaddr = section_name_to_address.get(".text", module_addr) + args = [] + for section_name in [".data", ".data..read_mostly", ".rodata", ".bss", + ".text.hot", ".text.unlikely"]: + address = section_name_to_address.get(section_name) + if address: + args.append(" -s {name} {addr}".format( + name=section_name, addr=str(address))) + return "{textaddr} {sections}".format( + textaddr=textaddr, sections="".join(args)) + + def load_module_symbols(self, module): + module_name = module['name'].string() + module_addr = str(module['mem'][constants.LX_MOD_TEXT]['base']).split()[0] + + module_file = self._get_module_file(module_name) + if not module_file and not self.module_files_updated: + self._update_module_files() + module_file = self._get_module_file(module_name) + + if module_file: + if utils.is_target_arch('s390'): + # Module text is preceded by PLT stubs on s390. + module_arch = module['arch'] + plt_offset = int(module_arch['plt_offset']) + plt_size = int(module_arch['plt_size']) + module_addr = hex(int(module_addr, 0) + plt_offset + plt_size) + gdb.write("loading @{addr}: {filename}\n".format( + addr=module_addr, filename=module_file)) + cmdline = "add-symbol-file {filename} {sections}".format( + filename=module_file, + sections=self._section_arguments(module, module_addr)) + gdb.execute(cmdline, to_string=True) + if module_name not in self.loaded_modules: + self.loaded_modules.append(module_name) + else: + gdb.write("no module object found for '{0}'\n".format(module_name)) + + def add_bpf_prog(self, prog): + if prog["jited"]: + self.bpf_progs[int(prog["bpf_func"])] = prog + + def remove_bpf_prog(self, prog): + self.bpf_progs.pop(int(prog["bpf_func"]), None) + + def add_bpf_ksym(self, ksym): + addr = int(ksym["start"]) + name = bpf.get_ksym_name(ksym) + with utils.pagination_off(): + gdb.write("loading @{addr}: {name}\n".format( + addr=hex(addr), name=name)) + debug_obj = bpf.generate_debug_obj(ksym, self.bpf_progs.get(addr)) + if debug_obj is None: + return + try: + cmdline = "add-symbol-file {obj} {addr}".format( + obj=debug_obj.name, addr=hex(addr)) + gdb.execute(cmdline, to_string=True) + except: + debug_obj.close() + raise + self.bpf_debug_objs[addr] = debug_obj + + def remove_bpf_ksym(self, ksym): + addr = int(ksym["start"]) + debug_obj = self.bpf_debug_objs.pop(addr, None) + if debug_obj is None: + return + try: + name = bpf.get_ksym_name(ksym) + gdb.write("unloading @{addr}: {name}\n".format( + addr=hex(addr), name=name)) + cmdline = "remove-symbol-file {path}".format(path=debug_obj.name) + gdb.execute(cmdline, to_string=True) + finally: + debug_obj.close() + + def cleanup_bpf(self): + self.bpf_progs = {} + while len(self.bpf_debug_objs) > 0: + self.bpf_debug_objs.popitem()[1].close() + + + def load_all_symbols(self): + gdb.write("loading vmlinux\n") + + # Dropping symbols will disable all breakpoints. So save their states + # and restore them afterward. + saved_states = [] + if hasattr(gdb, 'breakpoints') and not gdb.breakpoints() is None: + for bp in gdb.breakpoints(): + saved_states.append({'breakpoint': bp, 'enabled': bp.enabled}) + + # drop all current symbols and reload vmlinux + orig_vmlinux = utils.get_vmlinux() + gdb.execute("symbol-file", to_string=True) + kerneloffset = get_kerneloffset() + if kerneloffset is None: + offset_arg = "" + else: + offset_arg = " -o " + hex(kerneloffset) + gdb.execute("symbol-file {0}{1}".format(orig_vmlinux, offset_arg)) + + self.loaded_modules = [] + module_list = modules.module_list() + if not module_list: + gdb.write("no modules found\n") + else: + [self.load_module_symbols(module) for module in module_list] + + self.cleanup_bpf() + if self.bpf_prog_monitor is not None: + self.bpf_prog_monitor.notify_initial() + if self.bpf_ksym_monitor is not None: + self.bpf_ksym_monitor.notify_initial() + + for saved_state in saved_states: + saved_state['breakpoint'].enabled = saved_state['enabled'] + + def invoke(self, arg, from_tty): + skip_decompressor() + + monitor_bpf = False + self.module_paths = [] + for p in arg.split(): + if p == "-bpf": + monitor_bpf = True + else: + p.append(os.path.abspath(os.path.expanduser(p))) + self.module_paths.append(os.getcwd()) + + if self.breakpoint is not None: + self.breakpoint.delete() + self.breakpoint = None + if self.bpf_prog_monitor is not None: + self.bpf_prog_monitor.delete() + self.bpf_prog_monitor = None + if self.bpf_ksym_monitor is not None: + self.bpf_ksym_monitor.delete() + self.bpf_ksym_monitor = None + + # enforce update + self.module_files = [] + self.module_files_updated = False + + self.load_all_symbols() + + if not hasattr(gdb, 'Breakpoint'): + gdb.write("Note: symbol update on module and BPF loading not " + "supported with this gdb version\n") + return + + if modules.has_modules(): + self.breakpoint = LoadModuleBreakpoint( + "kernel/module/main.c:do_init_module", self) + + if monitor_bpf: + if constants.LX_CONFIG_BPF_SYSCALL: + self.bpf_prog_monitor = bpf.ProgMonitor(self.add_bpf_prog, + self.remove_bpf_prog) + if constants.LX_CONFIG_BPF and constants.LX_CONFIG_BPF_JIT: + self.bpf_ksym_monitor = bpf.KsymMonitor(self.add_bpf_ksym, + self.remove_bpf_ksym) + + +LxSymbols() |