4a94e36819
This commit brings all the changes made by running gdb/copyright.py as per GDB's Start of New Year Procedure. For the avoidance of doubt, all changes in this commits were performed by the script.
118 lines
4.5 KiB
Python
118 lines
4.5 KiB
Python
# Copyright (C) 2015-2022 Free Software Foundation, Inc.
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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import gdb
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from gdb.unwinder import Unwinder
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class FrameId(object):
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def __init__(self, sp, pc):
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self._sp = sp
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self._pc = pc
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@property
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def sp(self):
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return self._sp
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@property
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def pc(self):
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return self._pc
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class TestUnwinder(Unwinder):
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AMD64_RBP = 6
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AMD64_RSP = 7
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AMD64_RIP = None
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def __init__(self):
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Unwinder.__init__(self, "test unwinder")
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self.char_ptr_t = gdb.lookup_type("unsigned char").pointer()
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self.char_ptr_ptr_t = self.char_ptr_t.pointer()
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self._last_arch = None
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# Update the register descriptor AMD64_RIP based on ARCH.
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def _update_register_descriptors(self, arch):
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if self._last_arch != arch:
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TestUnwinder.AMD64_RIP = arch.registers().find("rip")
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self._last_arch = arch
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def _read_word(self, address):
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return address.cast(self.char_ptr_ptr_t).dereference()
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def __call__(self, pending_frame):
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"""Test unwinder written in Python.
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This unwinder can unwind the frames that have been deliberately
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corrupted in a specific way (functions in the accompanying
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py-unwind.c file do that.)
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This code is only on AMD64.
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On AMD64 $RBP points to the innermost frame (unless the code
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was compiled with -fomit-frame-pointer), which contains the
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address of the previous frame at offset 0. The functions
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deliberately corrupt their frames as follows:
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Before After
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Corruption: Corruption:
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+--------------+ +--------------+
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RBP-8 | | | Previous RBP |
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+--------------+ +--------------+
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RBP + Previous RBP | | RBP |
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+--------------+ +--------------+
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RBP+8 | Return RIP | | Return RIP |
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+--------------+ +--------------+
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Old SP | | | |
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This unwinder recognizes the corrupt frames by checking that
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*RBP == RBP, and restores previous RBP from the word above it.
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"""
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# Check that we can access the architecture of the pending
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# frame, and that this is the same architecture as for the
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# currently selected inferior.
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inf_arch = gdb.selected_inferior().architecture()
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frame_arch = pending_frame.architecture()
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if inf_arch != frame_arch:
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raise gdb.GdbError("architecture mismatch")
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self._update_register_descriptors(frame_arch)
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try:
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# NOTE: the registers in Unwinder API can be referenced
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# either by name or by number. The code below uses both
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# to achieve more coverage.
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bp = pending_frame.read_register("rbp").cast(self.char_ptr_t)
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if self._read_word(bp) != bp:
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return None
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# Found the frame that the test program has corrupted for us.
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# The correct BP for the outer frame has been saved one word
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# above, previous IP and SP are at the expected places.
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previous_bp = self._read_word(bp - 8)
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previous_ip = self._read_word(bp + 8)
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previous_sp = bp + 16
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frame_id = FrameId(
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pending_frame.read_register(TestUnwinder.AMD64_RSP),
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pending_frame.read_register(TestUnwinder.AMD64_RIP),
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)
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unwind_info = pending_frame.create_unwind_info(frame_id)
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unwind_info.add_saved_register(TestUnwinder.AMD64_RBP, previous_bp)
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unwind_info.add_saved_register("rip", previous_ip)
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unwind_info.add_saved_register("rsp", previous_sp)
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return unwind_info
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except (gdb.error, RuntimeError):
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return None
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gdb.unwinder.register_unwinder(None, TestUnwinder(), True)
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print("Python script imported")
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