xref: /linux/scripts/gdb/linux/utils.py (revision e5a52fd2b8cdb700b3c07b030e050a49ef3156b9) 
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
126target_arch = None
127
128
129def is_target_arch(arch):
130    if hasattr(gdb.Frame, 'architecture'):
131        return arch in gdb.newest_frame().architecture().name()
132    else:
133        global target_arch
134        if target_arch is None:
135            target_arch = gdb.execute("show architecture", to_string=True)
136        return arch in target_arch
137
138
139GDBSERVER_QEMU = 0
140GDBSERVER_KGDB = 1
141gdbserver_type = None
142
143
144def get_gdbserver_type():
145    def exit_handler(event):
146        global gdbserver_type
147        gdbserver_type = None
148        gdb.events.exited.disconnect(exit_handler)
149
150    def probe_qemu():
151        try:
152            return gdb.execute("monitor info version", to_string=True) != ""
153        except gdb.error:
154            return False
155
156    def probe_kgdb():
157        try:
158            thread_info = gdb.execute("info thread 2", to_string=True)
159            return "shadowCPU0" in thread_info
160        except gdb.error:
161            return False
162
163    global gdbserver_type
164    if gdbserver_type is None:
165        if probe_qemu():
166            gdbserver_type = GDBSERVER_QEMU
167        elif probe_kgdb():
168            gdbserver_type = GDBSERVER_KGDB
169        if gdbserver_type is not None and hasattr(gdb, 'events'):
170            gdb.events.exited.connect(exit_handler)
171    return gdbserver_type
172
173
174def gdb_eval_or_none(expresssion):
175    try:
176        return gdb.parse_and_eval(expresssion)
177    except gdb.error:
178        return None
179
180
181def dentry_name(d):
182    parent = d['d_parent']
183    if parent == d or parent == 0:
184        return ""
185    p = dentry_name(d['d_parent']) + "/"
186    return p + d['d_iname'].string()
187