| # Reverse debugging test |
| # |
| # 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 avocado import skipIf |
| from avocado_qemu import BUILD_DIR |
| from avocado.utils import datadrainer |
| from avocado.utils import gdb |
| from avocado.utils import process |
| from avocado.utils.network.ports import find_free_port |
| from avocado.utils.path import find_command |
| from boot_linux_console import LinuxKernelTest |
| |
| 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): |
| logger = logging.getLogger('replay') |
| vm = self.get_vm() |
| 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): |
| 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 = os.path.join(BUILD_DIR, 'qemu-img') |
| if not os.path.exists(qemu_img): |
| qemu_img = find_command('qemu-img', False) |
| if qemu_img is False: |
| self.cancel('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') |
| port = find_free_port() |
| |
| # record the log |
| vm = self.run_vm(True, shift, args, replay_path, image_path, port) |
| 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 |
| 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('exitting gdb and qemu') |
| vm.shutdown() |
| |
| class ReverseDebugging_X86_64(ReverseDebugging): |
| """ |
| :avocado: tags=accel:tcg |
| """ |
| |
| REG_PC = 0x10 |
| REG_CS = 0x12 |
| def get_pc(self, g): |
| return self.get_reg_le(g, self.REG_PC) \ |
| + self.get_reg_le(g, self.REG_CS) * 0x10 |
| |
| # unidentified gitlab timeout problem |
| @skipIf(os.getenv('GITLAB_CI'), 'Running on GitLab') |
| def test_x86_64_pc(self): |
| """ |
| :avocado: tags=arch:x86_64 |
| :avocado: tags=machine:pc |
| """ |
| # start with BIOS only |
| self.reverse_debugging() |
| |
| class ReverseDebugging_AArch64(ReverseDebugging): |
| """ |
| :avocado: tags=accel:tcg |
| """ |
| |
| REG_PC = 32 |
| |
| # unidentified gitlab timeout problem |
| @skipIf(os.getenv('GITLAB_CI'), 'Running on GitLab') |
| def test_aarch64_virt(self): |
| """ |
| :avocado: tags=arch:aarch64 |
| :avocado: tags=machine:virt |
| :avocado: tags=cpu:cortex-a53 |
| """ |
| kernel_url = ('https://archives.fedoraproject.org/pub/archive/fedora' |
| '/linux/releases/29/Everything/aarch64/os/images/pxeboot' |
| '/vmlinuz') |
| kernel_hash = '8c73e469fc6ea06a58dc83a628fc695b693b8493' |
| kernel_path = self.fetch_asset(kernel_url, asset_hash=kernel_hash) |
| |
| self.reverse_debugging( |
| args=('-kernel', kernel_path)) |
| |
| class ReverseDebugging_ppc64(ReverseDebugging): |
| """ |
| :avocado: tags=accel:tcg |
| """ |
| |
| REG_PC = 0x40 |
| |
| # unidentified gitlab timeout problem |
| @skipIf(os.getenv('GITLAB_CI'), 'Running on GitLab') |
| def test_ppc64_pseries(self): |
| """ |
| :avocado: tags=arch:ppc64 |
| :avocado: tags=machine:pseries |
| """ |
| # SLOF branches back to its entry point, which causes this test |
| # to take the 'hit a breakpoint again' path. That's not a problem, |
| # just slightly different than the other machines. |
| self.endian_is_le = False |
| self.reverse_debugging() |
| |
| # See https://gitlab.com/qemu-project/qemu/-/issues/1992 |
| @skipIf(os.getenv('GITLAB_CI'), 'Running on GitLab') |
| def test_ppc64_powernv(self): |
| """ |
| :avocado: tags=arch:ppc64 |
| :avocado: tags=machine:powernv |
| """ |
| self.endian_is_le = False |
| self.reverse_debugging() |
