utils.py (5151B)
1# 2# gdb helper commands and functions for Linux kernel debugging 3# 4# common utilities 5# 6# Copyright (c) Siemens AG, 2011-2013 7# 8# Authors: 9# Jan Kiszka <jan.kiszka@siemens.com> 10# 11# This work is licensed under the terms of the GNU GPL version 2. 12# 13 14import gdb 15 16 17class CachedType: 18 def __init__(self, name): 19 self._type = None 20 self._name = name 21 22 def _new_objfile_handler(self, event): 23 self._type = None 24 gdb.events.new_objfile.disconnect(self._new_objfile_handler) 25 26 def get_type(self): 27 if self._type is None: 28 self._type = gdb.lookup_type(self._name) 29 if self._type is None: 30 raise gdb.GdbError( 31 "cannot resolve type '{0}'".format(self._name)) 32 if hasattr(gdb, 'events') and hasattr(gdb.events, 'new_objfile'): 33 gdb.events.new_objfile.connect(self._new_objfile_handler) 34 return self._type 35 36 37long_type = CachedType("long") 38 39 40def get_long_type(): 41 global long_type 42 return long_type.get_type() 43 44 45def offset_of(typeobj, field): 46 element = gdb.Value(0).cast(typeobj) 47 return int(str(element[field].address).split()[0], 16) 48 49 50def container_of(ptr, typeobj, member): 51 return (ptr.cast(get_long_type()) - 52 offset_of(typeobj, member)).cast(typeobj) 53 54 55class ContainerOf(gdb.Function): 56 """Return pointer to containing data structure. 57 58$container_of(PTR, "TYPE", "ELEMENT"): Given PTR, return a pointer to the 59data structure of the type TYPE in which PTR is the address of ELEMENT. 60Note that TYPE and ELEMENT have to be quoted as strings.""" 61 62 def __init__(self): 63 super(ContainerOf, self).__init__("container_of") 64 65 def invoke(self, ptr, typename, elementname): 66 return container_of(ptr, gdb.lookup_type(typename.string()).pointer(), 67 elementname.string()) 68 69 70ContainerOf() 71 72 73BIG_ENDIAN = 0 74LITTLE_ENDIAN = 1 75target_endianness = None 76 77 78def get_target_endianness(): 79 global target_endianness 80 if target_endianness is None: 81 endian = gdb.execute("show endian", to_string=True) 82 if "little endian" in endian: 83 target_endianness = LITTLE_ENDIAN 84 elif "big endian" in endian: 85 target_endianness = BIG_ENDIAN 86 else: 87 raise gdb.GdbError("unknown endianness '{0}'".format(str(endian))) 88 return target_endianness 89 90 91def read_memoryview(inf, start, length): 92 return memoryview(inf.read_memory(start, length)) 93 94 95def read_u16(buffer, offset): 96 buffer_val = buffer[offset:offset + 2] 97 value = [0, 0] 98 99 if type(buffer_val[0]) is str: 100 value[0] = ord(buffer_val[0]) 101 value[1] = ord(buffer_val[1]) 102 else: 103 value[0] = buffer_val[0] 104 value[1] = buffer_val[1] 105 106 if get_target_endianness() == LITTLE_ENDIAN: 107 return value[0] + (value[1] << 8) 108 else: 109 return value[1] + (value[0] << 8) 110 111 112def read_u32(buffer, offset): 113 if get_target_endianness() == LITTLE_ENDIAN: 114 return read_u16(buffer, offset) + (read_u16(buffer, offset + 2) << 16) 115 else: 116 return read_u16(buffer, offset + 2) + (read_u16(buffer, offset) << 16) 117 118 119def read_u64(buffer, offset): 120 if get_target_endianness() == LITTLE_ENDIAN: 121 return read_u32(buffer, offset) + (read_u32(buffer, offset + 4) << 32) 122 else: 123 return read_u32(buffer, offset + 4) + (read_u32(buffer, offset) << 32) 124 125 126def read_ulong(buffer, offset): 127 if get_long_type().sizeof == 8: 128 return read_u64(buffer, offset) 129 else: 130 return read_u32(buffer, offset) 131 132 133target_arch = None 134 135 136def is_target_arch(arch): 137 if hasattr(gdb.Frame, 'architecture'): 138 return arch in gdb.newest_frame().architecture().name() 139 else: 140 global target_arch 141 if target_arch is None: 142 target_arch = gdb.execute("show architecture", to_string=True) 143 return arch in target_arch 144 145 146GDBSERVER_QEMU = 0 147GDBSERVER_KGDB = 1 148gdbserver_type = None 149 150 151def get_gdbserver_type(): 152 def exit_handler(event): 153 global gdbserver_type 154 gdbserver_type = None 155 gdb.events.exited.disconnect(exit_handler) 156 157 def probe_qemu(): 158 try: 159 return gdb.execute("monitor info version", to_string=True) != "" 160 except gdb.error: 161 return False 162 163 def probe_kgdb(): 164 try: 165 thread_info = gdb.execute("info thread 2", to_string=True) 166 return "shadowCPU0" in thread_info 167 except gdb.error: 168 return False 169 170 global gdbserver_type 171 if gdbserver_type is None: 172 if probe_qemu(): 173 gdbserver_type = GDBSERVER_QEMU 174 elif probe_kgdb(): 175 gdbserver_type = GDBSERVER_KGDB 176 if gdbserver_type is not None and hasattr(gdb, 'events'): 177 gdb.events.exited.connect(exit_handler) 178 return gdbserver_type 179 180 181def gdb_eval_or_none(expresssion): 182 try: 183 return gdb.parse_and_eval(expresssion) 184 except gdb.error: 185 return None 186 187 188def dentry_name(d): 189 parent = d['d_parent'] 190 if parent == d or parent == 0: 191 return "" 192 p = dentry_name(d['d_parent']) + "/" 193 return p + d['d_iname'].string()