1# Copyright (C) 2021-2023 Free Software Foundation, Inc.
2
3# This program is free software; you can redistribute it and/or modify
4# it under the terms of the GNU General Public License as published by
5# the Free Software Foundation; either version 3 of the License, or
6# (at your option) any later version.
7#
8# This program is distributed in the hope that it will be useful,
9# but WITHOUT ANY WARRANTY; without even the implied warranty of
10# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11# GNU General Public License for more details.
12#
13# You should have received a copy of the GNU General Public License
14# along with this program.  If not, see <http://www.gnu.org/licenses/>.
15
16# This dummy unwinder will break GDB's backtrce at the function called
17# 'break_bt_here'.
18
19import gdb
20from gdb.unwinder import Unwinder
21
22
23class FrameId(object):
24    def __init__(self, sp, pc):
25        self._sp = sp
26        self._pc = pc
27
28    @property
29    def sp(self):
30        return self._sp
31
32    @property
33    def pc(self):
34        return self._pc
35
36
37class TestUnwinder(Unwinder):
38    def __init__(self):
39        Unwinder.__init__(self, "break unwinding")
40
41    def __call__(self, pending_frame):
42        pc_desc = pending_frame.architecture().registers().find("pc")
43        pc = pending_frame.read_register(pc_desc)
44
45        sp_desc = pending_frame.architecture().registers().find("sp")
46        sp = pending_frame.read_register(sp_desc)
47
48        block = gdb.block_for_pc(int(pc))
49        if block is None:
50            return None
51        func = block.function
52        if func is None:
53            return None
54        if str(func) != "break_bt_here":
55            return None
56        fid = FrameId(pc, sp)
57        return pending_frame.create_unwind_info(fid)
58
59
60gdb.unwinder.register_unwinder(None, TestUnwinder(), True)
61