1# Copyright (C) 2016-2023 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 unwinder never does any unwinding. It'll (pretend to) "sniff" 17# the frame and ultimately return None, indicating that actual unwinding 18# should be performed by some other unwinder. 19# 20# But, prior to returning None, it will attempt to obtain the value 21# associated with a symbol via a call to gdb.parse_and_eval(). In 22# the course of doing this evaluation, GDB will potentially access 23# some frames, leading to the possibility of a recursive invocation of 24# this unwinder. If that should happen, code contained herein detects 25# that and prints a message which will cause some of the associated 26# tests to FAIL. 27 28import gdb 29from gdb.unwinder import Unwinder 30 31 32class TestUnwinder(Unwinder): 33 34 count = 0 35 36 @classmethod 37 def reset_count(cls): 38 cls.count = 0 39 40 @classmethod 41 def inc_count(cls): 42 cls.count += 1 43 44 test = "check_undefined_symbol" 45 46 @classmethod 47 def set_test(cls, test): 48 cls.test = test 49 50 def __init__(self): 51 Unwinder.__init__(self, "test unwinder") 52 self.recurse_level = 0 53 54 def __call__(self, pending_frame): 55 56 if self.recurse_level > 0: 57 gdb.write("TestUnwinder: Recursion detected - returning early.\n") 58 return None 59 60 self.recurse_level += 1 61 TestUnwinder.inc_count() 62 63 if TestUnwinder.test == "check_user_reg_pc": 64 65 pc = pending_frame.read_register("pc") 66 pc_as_int = int(pc.cast(gdb.lookup_type("int"))) 67 # gdb.write("In unwinder: pc=%x\n" % pc_as_int) 68 69 elif TestUnwinder.test == "check_pae_pc": 70 71 pc = gdb.parse_and_eval("$pc") 72 pc_as_int = int(pc.cast(gdb.lookup_type("int"))) 73 # gdb.write("In unwinder: pc=%x\n" % pc_as_int) 74 75 elif TestUnwinder.test == "check_undefined_symbol": 76 77 try: 78 val = gdb.parse_and_eval("undefined_symbol") 79 80 except Exception as arg: 81 pass 82 83 self.recurse_level -= 1 84 85 return None 86 87 88gdb.unwinder.register_unwinder(None, TestUnwinder(), True) 89gdb.write("Python script imported\n") 90