diff options
Diffstat (limited to 'tests/functional/reverse_debugging.py')
| -rw-r--r-- | tests/functional/reverse_debugging.py | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/tests/functional/reverse_debugging.py b/tests/functional/reverse_debugging.py new file mode 100644 index 0000000..f9a1d39 --- /dev/null +++ b/tests/functional/reverse_debugging.py @@ -0,0 +1,196 @@ +# Reverse debugging test +# +# SPDX-License-Identifier: GPL-2.0-or-later +# +# Copyright (c) 2020 ISP RAS +# +# Author: +# Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru> +# +# This work is licensed under the terms of the GNU GPL, version 2 or +# later. See the COPYING file in the top-level directory. +import os +import logging + +from qemu_test import LinuxKernelTest, get_qemu_img +from qemu_test.ports import Ports + + +class ReverseDebugging(LinuxKernelTest): + """ + Test GDB reverse debugging commands: reverse step and reverse continue. + Recording saves the execution of some instructions and makes an initial + VM snapshot to allow reverse execution. + Replay saves the order of the first instructions and then checks that they + are executed backwards in the correct order. + After that the execution is replayed to the end, and reverse continue + command is checked by setting several breakpoints, and asserting + that the execution is stopped at the last of them. + """ + + timeout = 10 + STEPS = 10 + endian_is_le = True + + def run_vm(self, record, shift, args, replay_path, image_path, port): + from avocado.utils import datadrainer + + logger = logging.getLogger('replay') + vm = self.get_vm(name='record' if record else 'replay') + vm.set_console() + if record: + logger.info('recording the execution...') + mode = 'record' + else: + logger.info('replaying the execution...') + mode = 'replay' + vm.add_args('-gdb', 'tcp::%d' % port, '-S') + vm.add_args('-icount', 'shift=%s,rr=%s,rrfile=%s,rrsnapshot=init' % + (shift, mode, replay_path), + '-net', 'none') + vm.add_args('-drive', 'file=%s,if=none' % image_path) + if args: + vm.add_args(*args) + vm.launch() + console_drainer = datadrainer.LineLogger(vm.console_socket.fileno(), + logger=self.log.getChild('console'), + stop_check=(lambda : not vm.is_running())) + console_drainer.start() + return vm + + @staticmethod + def get_reg_le(g, reg): + res = g.cmd(b'p%x' % reg) + num = 0 + for i in range(len(res))[-2::-2]: + num = 0x100 * num + int(res[i:i + 2], 16) + return num + + @staticmethod + def get_reg_be(g, reg): + res = g.cmd(b'p%x' % reg) + return int(res, 16) + + def get_reg(self, g, reg): + # value may be encoded in BE or LE order + if self.endian_is_le: + return self.get_reg_le(g, reg) + else: + return self.get_reg_be(g, reg) + + def get_pc(self, g): + return self.get_reg(g, self.REG_PC) + + def check_pc(self, g, addr): + pc = self.get_pc(g) + if pc != addr: + self.fail('Invalid PC (read %x instead of %x)' % (pc, addr)) + + @staticmethod + def gdb_step(g): + g.cmd(b's', b'T05thread:01;') + + @staticmethod + def gdb_bstep(g): + g.cmd(b'bs', b'T05thread:01;') + + @staticmethod + def vm_get_icount(vm): + return vm.qmp('query-replay')['return']['icount'] + + def reverse_debugging(self, shift=7, args=None): + from avocado.utils import gdb + from avocado.utils import process + + logger = logging.getLogger('replay') + + # create qcow2 for snapshots + logger.info('creating qcow2 image for VM snapshots') + image_path = os.path.join(self.workdir, 'disk.qcow2') + qemu_img = get_qemu_img(self) + if qemu_img is None: + self.skipTest('Could not find "qemu-img", which is required to ' + 'create the temporary qcow2 image') + cmd = '%s create -f qcow2 %s 128M' % (qemu_img, image_path) + process.run(cmd) + + replay_path = os.path.join(self.workdir, 'replay.bin') + + # record the log + vm = self.run_vm(True, shift, args, replay_path, image_path, -1) + while self.vm_get_icount(vm) <= self.STEPS: + pass + last_icount = self.vm_get_icount(vm) + vm.shutdown() + + logger.info("recorded log with %s+ steps" % last_icount) + + # replay and run debug commands + with Ports() as ports: + port = ports.find_free_port() + vm = self.run_vm(False, shift, args, replay_path, image_path, port) + logger.info('connecting to gdbstub') + g = gdb.GDBRemote('127.0.0.1', port, False, False) + g.connect() + r = g.cmd(b'qSupported') + if b'qXfer:features:read+' in r: + g.cmd(b'qXfer:features:read:target.xml:0,ffb') + if b'ReverseStep+' not in r: + self.fail('Reverse step is not supported by QEMU') + if b'ReverseContinue+' not in r: + self.fail('Reverse continue is not supported by QEMU') + + logger.info('stepping forward') + steps = [] + # record first instruction addresses + for _ in range(self.STEPS): + pc = self.get_pc(g) + logger.info('saving position %x' % pc) + steps.append(pc) + self.gdb_step(g) + + # visit the recorded instruction in reverse order + logger.info('stepping backward') + for addr in steps[::-1]: + self.gdb_bstep(g) + self.check_pc(g, addr) + logger.info('found position %x' % addr) + + # visit the recorded instruction in forward order + logger.info('stepping forward') + for addr in steps: + self.check_pc(g, addr) + self.gdb_step(g) + logger.info('found position %x' % addr) + + # set breakpoints for the instructions just stepped over + logger.info('setting breakpoints') + for addr in steps: + # hardware breakpoint at addr with len=1 + g.cmd(b'Z1,%x,1' % addr, b'OK') + + # this may hit a breakpoint if first instructions are executed + # again + logger.info('continuing execution') + vm.qmp('replay-break', icount=last_icount - 1) + # continue - will return after pausing + # This could stop at the end and get a T02 return, or by + # re-executing one of the breakpoints and get a T05 return. + g.cmd(b'c') + if self.vm_get_icount(vm) == last_icount - 1: + logger.info('reached the end (icount %s)' % (last_icount - 1)) + else: + logger.info('hit a breakpoint again at %x (icount %s)' % + (self.get_pc(g), self.vm_get_icount(vm))) + + logger.info('running reverse continue to reach %x' % steps[-1]) + # reverse continue - will return after stopping at the breakpoint + g.cmd(b'bc', b'T05thread:01;') + + # assume that none of the first instructions is executed again + # breaking the order of the breakpoints + self.check_pc(g, steps[-1]) + logger.info('successfully reached %x' % steps[-1]) + + logger.info('exiting gdb and qemu') + vm.shutdown() |