xref: /linux-6.15/scripts/gdb/linux/utils.py (revision b24e2d21) 
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 <[email protected]>
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
69ContainerOf()
70
71
72BIG_ENDIAN = 0
73LITTLE_ENDIAN = 1
74target_endianness = None
75
76
77def get_target_endianness():
78    global target_endianness
79    if target_endianness is None:
80        endian = gdb.execute("show endian", to_string=True)
81        if "little endian" in endian:
82            target_endianness = LITTLE_ENDIAN
83        elif "big endian" in endian:
84            target_endianness = BIG_ENDIAN
85        else:
86            raise gdb.GdgError("unknown endianness '{0}'".format(endian))
87    return target_endianness
88
89
90def read_u16(buffer):
91    if get_target_endianness() == LITTLE_ENDIAN:
92        return ord(buffer[0]) + (ord(buffer[1]) << 8)
93    else:
94        return ord(buffer[1]) + (ord(buffer[0]) << 8)
95
96
97def read_u32(buffer):
98    if get_target_endianness() == LITTLE_ENDIAN:
99        return read_u16(buffer[0:2]) + (read_u16(buffer[2:4]) << 16)
100    else:
101        return read_u16(buffer[2:4]) + (read_u16(buffer[0:2]) << 16)
102
103
104def read_u64(buffer):
105    if get_target_endianness() == LITTLE_ENDIAN:
106        return read_u32(buffer[0:4]) + (read_u32(buffer[4:8]) << 32)
107    else:
108        return read_u32(buffer[4:8]) + (read_u32(buffer[0:4]) << 32)
109
110
111target_arch = None
112
113
114def is_target_arch(arch):
115    if hasattr(gdb.Frame, 'architecture'):
116        return arch in gdb.newest_frame().architecture().name()
117    else:
118        global target_arch
119        if target_arch is None:
120            target_arch = gdb.execute("show architecture", to_string=True)
121        return arch in target_arch
122