1# Copyright (C) 2016-2024 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 count = 0 34 35 @classmethod 36 def reset_count(cls): 37 cls.count = 0 38 39 @classmethod 40 def inc_count(cls): 41 cls.count += 1 42 43 test = "check_undefined_symbol" 44 45 @classmethod 46 def set_test(cls, test): 47 cls.test = test 48 49 def __init__(self): 50 Unwinder.__init__(self, "test unwinder") 51 self.recurse_level = 0 52 53 def __call__(self, pending_frame): 54 if self.recurse_level > 0: 55 gdb.write("TestUnwinder: Recursion detected - returning early.\n") 56 return None 57 58 self.recurse_level += 1 59 TestUnwinder.inc_count() 60 61 if TestUnwinder.test == "check_user_reg_pc": 62 pc = pending_frame.read_register("pc") 63 pc_as_int = int(pc.cast(gdb.lookup_type("int"))) 64 # gdb.write("In unwinder: pc=%x\n" % pc_as_int) 65 66 elif TestUnwinder.test == "check_pae_pc": 67 pc = gdb.parse_and_eval("$pc") 68 pc_as_int = int(pc.cast(gdb.lookup_type("int"))) 69 # gdb.write("In unwinder: pc=%x\n" % pc_as_int) 70 71 elif TestUnwinder.test == "check_undefined_symbol": 72 try: 73 val = gdb.parse_and_eval("undefined_symbol") 74 75 except Exception as arg: 76 pass 77 78 self.recurse_level -= 1 79 80 return None 81 82 83gdb.unwinder.register_unwinder(None, TestUnwinder(), True) 84gdb.write("Python script imported\n") 85