gdb/testsuite/gdb.python/py-unwind.py

   1 # Copyright (C) 2015-2024 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 import gdb
  17 from gdb.unwinder import Unwinder, FrameId
  18
  19
  20 # These are set to test whether invalid register names cause an error.
  21 add_saved_register_errors = {}
  22 read_register_error = False
  23
  24
  25 class TestUnwinder(Unwinder):
  26     AMD64_RBP = 6
  27     AMD64_RSP = 7
  28     AMD64_RIP = None
  29
  30     def __init__(self):
  31         Unwinder.__init__(self, "test unwinder")
  32         self.char_ptr_t = gdb.lookup_type("unsigned char").pointer()
  33         self.char_ptr_ptr_t = self.char_ptr_t.pointer()
  34         self._last_arch = None
  35
  36     # Update the register descriptor AMD64_RIP based on ARCH.
  37     def _update_register_descriptors(self, arch):
  38         if self._last_arch != arch:
  39             TestUnwinder.AMD64_RIP = arch.registers().find("rip")
  40             self._last_arch = arch
  41
  42     def _read_word(self, address):
  43         return address.cast(self.char_ptr_ptr_t).dereference()
  44
  45     def __call__(self, pending_frame):
  46         """Test unwinder written in Python.
  47
  48         This unwinder can unwind the frames that have been deliberately
  49         corrupted in a specific way (functions in the accompanying
  50         py-unwind.c file do that.)
  51         This code is only on AMD64.
  52         On AMD64 $RBP points to the innermost frame (unless the code
  53         was compiled with -fomit-frame-pointer), which contains the
  54         address of the previous frame at offset 0. The functions
  55         deliberately corrupt their frames as follows:
  56                      Before                 After
  57                    Corruption:           Corruption:
  58                 +--------------+       +--------------+
  59         RBP-8   |              |       | Previous RBP |
  60                 +--------------+       +--------------+
  61         RBP     + Previous RBP |       |    RBP       |
  62                 +--------------+       +--------------+
  63         RBP+8   | Return RIP   |       | Return  RIP  |
  64                 +--------------+       +--------------+
  65         Old SP  |              |       |              |
  66
  67         This unwinder recognizes the corrupt frames by checking that
  68         *RBP == RBP, and restores previous RBP from the word above it.
  69         """
  70
  71         # Check that we can access the architecture of the pending
  72         # frame, and that this is the same architecture as for the
  73         # currently selected inferior.
  74         inf_arch = gdb.selected_inferior().architecture()
  75         frame_arch = pending_frame.architecture()
  76         if inf_arch != frame_arch:
  77             raise gdb.GdbError("architecture mismatch")
  78
  79         self._update_register_descriptors(frame_arch)
  80
  81         try:
  82             # NOTE: the registers in Unwinder API can be referenced
  83             # either by name or by number. The code below uses both
  84             # to achieve more coverage.
  85             bp = pending_frame.read_register("rbp").cast(self.char_ptr_t)
  86             if self._read_word(bp) != bp:
  87                 return None
  88             # Found the frame that the test program has corrupted for us.
  89             # The correct BP for the outer frame has been saved one word
  90             # above, previous IP and SP are at the expected places.
  91             previous_bp = self._read_word(bp - 8)
  92             previous_ip = self._read_word(bp + 8)
  93             previous_sp = bp + 16
  94
  95             try:
  96                 pending_frame.read_register("nosuchregister")
  97             except ValueError as ve:
  98                 global read_register_error
  99                 read_register_error = str(ve)
 100
 101             frame_id = FrameId(
 102                 pending_frame.read_register(register=TestUnwinder.AMD64_RSP),
 103                 pending_frame.read_register(TestUnwinder.AMD64_RIP),
 104             )
 105             unwind_info = pending_frame.create_unwind_info(frame_id)
 106             unwind_info.add_saved_register(TestUnwinder.AMD64_RBP, previous_bp)
 107             unwind_info.add_saved_register(value=previous_ip, register="rip")
 108             unwind_info.add_saved_register(register="rsp", value=previous_sp)
 109
 110             global add_saved_register_errors
 111             try:
 112                 unwind_info.add_saved_register("nosuchregister", previous_sp)
 113             except ValueError as ve:
 114                 add_saved_register_errors["unknown_name"] = str(ve)
 115
 116             try:
 117                 unwind_info.add_saved_register(999, previous_sp)
 118             except ValueError as ve:
 119                 add_saved_register_errors["unknown_number"] = str(ve)
 120
 121             try:
 122                 unwind_info.add_saved_register("rsp", 1234)
 123             except TypeError as ve:
 124                 add_saved_register_errors["bad_value"] = str(ve)
 125
 126             return unwind_info
 127         except (gdb.error, RuntimeError):
 128             return None
 129
 130
 131 global_test_unwinder = TestUnwinder()
 132 gdb.unwinder.register_unwinder(None, global_test_unwinder, True)
 133
 134 # These are filled in by the simple_unwinder class.
 135 captured_pending_frame = None
 136 captured_pending_frame_repr = None
 137 captured_unwind_info = None
 138 captured_unwind_info_repr = None
 139
 140
 141 class simple_unwinder(Unwinder):
 142     def __init__(self, name, sp=0x123, pc=0x456):
 143         super().__init__(name)
 144         self._sp = sp
 145         self._pc = pc
 146
 147     def __call__(self, pending_frame):
 148         global captured_pending_frame
 149         global captured_pending_frame_repr
 150         global captured_unwind_info
 151         global captured_unwind_info_repr
 152
 153         assert pending_frame.is_valid()
 154
 155         if captured_pending_frame is None:
 156             captured_pending_frame = pending_frame
 157             captured_pending_frame_repr = repr(pending_frame)
 158             fid = FrameId(self._sp, self._pc)
 159             uw = pending_frame.create_unwind_info(frame_id=fid)
 160             uw.add_saved_register("rip", gdb.Value(0x123))
 161             uw.add_saved_register("rbp", gdb.Value(0x456))
 162             uw.add_saved_register("rsp", gdb.Value(0x789))
 163             captured_unwind_info = uw
 164             captured_unwind_info_repr = repr(uw)
 165         return None
 166
 167
 168 # Return a dictionary of information about FRAME.
 169 def capture_frame_information(frame):
 170     name = frame.name()
 171     level = frame.level()
 172     language = frame.language()
 173     function = frame.function()
 174     architecture = frame.architecture()
 175     pc = frame.pc()
 176     sal = frame.find_sal()
 177     try:
 178         block = frame.block()
 179         assert isinstance(block, gdb.Block)
 180     except RuntimeError as rte:
 181         assert str(rte) == "Cannot locate block for frame."
 182         block = "RuntimeError: " + str(rte)
 183
 184     return {
 185         "name": name,
 186         "level": level,
 187         "language": language,
 188         "function": function,
 189         "architecture": architecture,
 190         "pc": pc,
 191         "sal": sal,
 192         "block": block,
 193     }
 194
 195
 196 # List of information about each frame.  The index into this list is
 197 # the frame level.  This is populated by
 198 # capture_all_frame_information.
 199 all_frame_information = []
 200
 201
 202 # Fill in the global ALL_FRAME_INFORMATION list.
 203 def capture_all_frame_information():
 204     global all_frame_information
 205
 206     all_frame_information = []
 207
 208     gdb.newest_frame().select()
 209     frame = gdb.selected_frame()
 210     count = 0
 211
 212     while frame is not None:
 213         frame.select()
 214         info = capture_frame_information(frame)
 215         level = info["level"]
 216         info["matched"] = False
 217
 218         while len(all_frame_information) <= level:
 219             all_frame_information.append(None)
 220
 221         assert all_frame_information[level] is None
 222         all_frame_information[level] = info
 223
 224         if frame.name == "main" or count > 10:
 225             break
 226
 227         count += 1
 228         frame = frame.older()
 229
 230
 231 # Assert that every entry in the global ALL_FRAME_INFORMATION list was
 232 # matched by the validating_unwinder.
 233 def check_all_frame_information_matched():
 234     global all_frame_information
 235     for entry in all_frame_information:
 236         assert entry["matched"]
 237
 238
 239 # An unwinder that doesn't match any frames.  What it does do is
 240 # lookup information from the PendingFrame object and compare it
 241 # against information stored in the global ALL_FRAME_INFORMATION list.
 242 class validating_unwinder(Unwinder):
 243     def __init__(self):
 244         super().__init__("validating_unwinder")
 245
 246     def __call__(self, pending_frame):
 247         info = capture_frame_information(pending_frame)
 248         level = info["level"]
 249
 250         global all_frame_information
 251         old_info = all_frame_information[level]
 252
 253         assert old_info is not None
 254         assert not old_info["matched"]
 255
 256         for key, value in info.items():
 257             assert key in old_info, key + " not in old_info"
 258             assert type(value) == type(old_info[key])
 259             if isinstance(value, gdb.Block):
 260                 assert value.start == old_info[key].start
 261                 assert value.end == old_info[key].end
 262                 assert value.is_static == old_info[key].is_static
 263                 assert value.is_global == old_info[key].is_global
 264             else:
 265                 assert str(value) == str(old_info[key])
 266
 267         old_info["matched"] = True
 268         return None
 269
 270
 271 print("Python script imported")