| Message ID | 159903463379.28509.561479052940546124.stgit@pasha-ThinkPad-X280 (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Reverse debugging | expand |
Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru> writes: > From: Pavel Dovgalyuk <Pavel.Dovgaluk@gmail.com> > > This is a test for GDB reverse debugging commands: reverse step and reverse continue. > Every test in this suite consists of two phases: record and replay. > 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. > > Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru> > --- > MAINTAINERS | 1 > tests/acceptance/reverse_debugging.py | 203 +++++++++++++++++++++++++++++++++ > 2 files changed, 204 insertions(+) > create mode 100644 tests/acceptance/reverse_debugging.py > > diff --git a/MAINTAINERS b/MAINTAINERS > index e49af700c9..76450f1bdf 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -2644,6 +2644,7 @@ F: include/sysemu/replay.h > F: docs/replay.txt > F: stubs/replay.c > F: tests/acceptance/replay_kernel.py > +F: tests/acceptance/reverse_debugging.py > F: qapi/replay.json > > IOVA Tree > diff --git a/tests/acceptance/reverse_debugging.py b/tests/acceptance/reverse_debugging.py > new file mode 100644 > index 0000000000..dda42e1c1a > --- /dev/null > +++ b/tests/acceptance/reverse_debugging.py > @@ -0,0 +1,203 @@ > +# 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_qemu import BUILD_DIR > +from avocado.utils import gdb > +from avocado.utils import process > +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): > + 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('-s', '-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() > + 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) These seem a little hacky. Can't we issue normal gdb commands. In the SVE tests I use: frame = gdb.selected_frame() for i in range(0, 32): rname = "z%d" % (i) zreg = frame.read_register(rname) which works with the symbolic name and doesn't need endian tricks to sort it out. > + > + 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;') Hmm so these are packet commands? Can't we access via the python API? Clebber? > + > + @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') > + > + # record the log > + vm = self.run_vm(True, shift, args, replay_path, image_path) > + 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) > + logger.info('connecting to gdbstub') > + g = gdb.GDBRemote('127.0.0.1', 1234, 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) > + > + logger.info('seeking to the end (icount %s)' % (last_icount - 1)) > + vm.qmp('replay-break', icount=last_icount - 1) > + # continue - will return after pausing > + g.cmd(b'c', b'T02thread:01;') > + > + logger.info('setting breakpoints') > + for addr in steps: > + # hardware breakpoint at addr with len=1 > + g.cmd(b'Z1,%x,1' % addr, b'OK') > + > + 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): > + 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 > + > + 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): > + REG_PC = 32 > + > + 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, '-cpu', 'cortex-a53')) Quibbles aside it's excellent to have a test that exercises the functionality.
diff --git a/MAINTAINERS b/MAINTAINERS index e49af700c9..76450f1bdf 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -2644,6 +2644,7 @@ F: include/sysemu/replay.h F: docs/replay.txt F: stubs/replay.c F: tests/acceptance/replay_kernel.py +F: tests/acceptance/reverse_debugging.py F: qapi/replay.json IOVA Tree diff --git a/tests/acceptance/reverse_debugging.py b/tests/acceptance/reverse_debugging.py new file mode 100644 index 0000000000..dda42e1c1a --- /dev/null +++ b/tests/acceptance/reverse_debugging.py @@ -0,0 +1,203 @@ +# 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_qemu import BUILD_DIR +from avocado.utils import gdb +from avocado.utils import process +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): + 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('-s', '-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() + 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') + + # record the log + vm = self.run_vm(True, shift, args, replay_path, image_path) + 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) + logger.info('connecting to gdbstub') + g = gdb.GDBRemote('127.0.0.1', 1234, 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) + + logger.info('seeking to the end (icount %s)' % (last_icount - 1)) + vm.qmp('replay-break', icount=last_icount - 1) + # continue - will return after pausing + g.cmd(b'c', b'T02thread:01;') + + logger.info('setting breakpoints') + for addr in steps: + # hardware breakpoint at addr with len=1 + g.cmd(b'Z1,%x,1' % addr, b'OK') + + 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): + 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 + + 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): + REG_PC = 32 + + 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, '-cpu', 'cortex-a53'))