0395b19438
Currently the test randomly fails if you are using a shared machine due to contention on the well known port 1234. We can ameliorate this a bit by picking a random non-ephemeral port although it doesn't totally avoid the problem. While we could use a totally unique socket address for debugging it is fiddly to probe for gdb support. While gdb socket debugging is not yet ubiquitous this a sub-optimal but workable option. Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Thomas Huth <thuth@redhat.com> Reviewed-by: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Message-Id: <20201021163136.27324-7-alex.bennee@linaro.org> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
211 lines
7.1 KiB
Python
211 lines
7.1 KiB
Python
# Reverse debugging test
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#
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# Copyright (c) 2020 ISP RAS
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#
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# Author:
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# Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
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#
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# This work is licensed under the terms of the GNU GPL, version 2 or
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# later. See the COPYING file in the top-level directory.
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import os
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import logging
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from avocado import skipIf
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from avocado_qemu import BUILD_DIR
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from avocado.utils import gdb
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from avocado.utils import process
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from avocado.utils.network.ports import find_free_port
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from avocado.utils.path import find_command
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from boot_linux_console import LinuxKernelTest
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class ReverseDebugging(LinuxKernelTest):
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"""
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Test GDB reverse debugging commands: reverse step and reverse continue.
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Recording saves the execution of some instructions and makes an initial
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VM snapshot to allow reverse execution.
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Replay saves the order of the first instructions and then checks that they
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are executed backwards in the correct order.
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After that the execution is replayed to the end, and reverse continue
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command is checked by setting several breakpoints, and asserting
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that the execution is stopped at the last of them.
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"""
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timeout = 10
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STEPS = 10
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endian_is_le = True
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def run_vm(self, record, shift, args, replay_path, image_path, port):
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logger = logging.getLogger('replay')
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vm = self.get_vm()
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vm.set_console()
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if record:
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logger.info('recording the execution...')
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mode = 'record'
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else:
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logger.info('replaying the execution...')
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mode = 'replay'
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vm.add_args('-gdb', 'tcp::%d' % port, '-S')
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vm.add_args('-icount', 'shift=%s,rr=%s,rrfile=%s,rrsnapshot=init' %
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(shift, mode, replay_path),
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'-net', 'none')
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vm.add_args('-drive', 'file=%s,if=none' % image_path)
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if args:
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vm.add_args(*args)
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vm.launch()
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return vm
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@staticmethod
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def get_reg_le(g, reg):
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res = g.cmd(b'p%x' % reg)
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num = 0
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for i in range(len(res))[-2::-2]:
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num = 0x100 * num + int(res[i:i + 2], 16)
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return num
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@staticmethod
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def get_reg_be(g, reg):
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res = g.cmd(b'p%x' % reg)
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return int(res, 16)
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def get_reg(self, g, reg):
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# value may be encoded in BE or LE order
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if self.endian_is_le:
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return self.get_reg_le(g, reg)
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else:
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return self.get_reg_be(g, reg)
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def get_pc(self, g):
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return self.get_reg(g, self.REG_PC)
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def check_pc(self, g, addr):
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pc = self.get_pc(g)
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if pc != addr:
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self.fail('Invalid PC (read %x instead of %x)' % (pc, addr))
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@staticmethod
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def gdb_step(g):
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g.cmd(b's', b'T05thread:01;')
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@staticmethod
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def gdb_bstep(g):
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g.cmd(b'bs', b'T05thread:01;')
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@staticmethod
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def vm_get_icount(vm):
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return vm.qmp('query-replay')['return']['icount']
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def reverse_debugging(self, shift=7, args=None):
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logger = logging.getLogger('replay')
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# create qcow2 for snapshots
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logger.info('creating qcow2 image for VM snapshots')
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image_path = os.path.join(self.workdir, 'disk.qcow2')
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qemu_img = os.path.join(BUILD_DIR, 'qemu-img')
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if not os.path.exists(qemu_img):
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qemu_img = find_command('qemu-img', False)
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if qemu_img is False:
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self.cancel('Could not find "qemu-img", which is required to '
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'create the temporary qcow2 image')
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cmd = '%s create -f qcow2 %s 128M' % (qemu_img, image_path)
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process.run(cmd)
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replay_path = os.path.join(self.workdir, 'replay.bin')
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port = find_free_port()
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# record the log
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vm = self.run_vm(True, shift, args, replay_path, image_path, port)
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while self.vm_get_icount(vm) <= self.STEPS:
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pass
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last_icount = self.vm_get_icount(vm)
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vm.shutdown()
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logger.info("recorded log with %s+ steps" % last_icount)
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# replay and run debug commands
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vm = self.run_vm(False, shift, args, replay_path, image_path, port)
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logger.info('connecting to gdbstub')
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g = gdb.GDBRemote('127.0.0.1', port, False, False)
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g.connect()
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r = g.cmd(b'qSupported')
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if b'qXfer:features:read+' in r:
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g.cmd(b'qXfer:features:read:target.xml:0,ffb')
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if b'ReverseStep+' not in r:
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self.fail('Reverse step is not supported by QEMU')
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if b'ReverseContinue+' not in r:
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self.fail('Reverse continue is not supported by QEMU')
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logger.info('stepping forward')
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steps = []
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# record first instruction addresses
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for _ in range(self.STEPS):
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pc = self.get_pc(g)
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logger.info('saving position %x' % pc)
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steps.append(pc)
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self.gdb_step(g)
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# visit the recorded instruction in reverse order
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logger.info('stepping backward')
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for addr in steps[::-1]:
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self.gdb_bstep(g)
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self.check_pc(g, addr)
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logger.info('found position %x' % addr)
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logger.info('seeking to the end (icount %s)' % (last_icount - 1))
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vm.qmp('replay-break', icount=last_icount - 1)
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# continue - will return after pausing
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g.cmd(b'c', b'T02thread:01;')
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logger.info('setting breakpoints')
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for addr in steps:
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# hardware breakpoint at addr with len=1
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g.cmd(b'Z1,%x,1' % addr, b'OK')
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logger.info('running reverse continue to reach %x' % steps[-1])
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# reverse continue - will return after stopping at the breakpoint
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g.cmd(b'bc', b'T05thread:01;')
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# assume that none of the first instructions is executed again
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# breaking the order of the breakpoints
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self.check_pc(g, steps[-1])
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logger.info('successfully reached %x' % steps[-1])
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logger.info('exitting gdb and qemu')
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vm.shutdown()
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class ReverseDebugging_X86_64(ReverseDebugging):
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REG_PC = 0x10
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REG_CS = 0x12
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def get_pc(self, g):
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return self.get_reg_le(g, self.REG_PC) \
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+ self.get_reg_le(g, self.REG_CS) * 0x10
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# unidentified gitlab timeout problem
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@skipIf(os.getenv('GITLAB_CI'), 'Running on GitLab')
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def test_x86_64_pc(self):
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"""
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:avocado: tags=arch:x86_64
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:avocado: tags=machine:pc
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"""
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# start with BIOS only
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self.reverse_debugging()
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class ReverseDebugging_AArch64(ReverseDebugging):
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REG_PC = 32
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# unidentified gitlab timeout problem
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@skipIf(os.getenv('GITLAB_CI'), 'Running on GitLab')
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def test_aarch64_virt(self):
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"""
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:avocado: tags=arch:aarch64
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:avocado: tags=machine:virt
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:avocado: tags=cpu:cortex-a53
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"""
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kernel_url = ('https://archives.fedoraproject.org/pub/archive/fedora'
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'/linux/releases/29/Everything/aarch64/os/images/pxeboot'
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'/vmlinuz')
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kernel_hash = '8c73e469fc6ea06a58dc83a628fc695b693b8493'
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kernel_path = self.fetch_asset(kernel_url, asset_hash=kernel_hash)
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self.reverse_debugging(
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args=('-kernel', kernel_path, '-cpu', 'cortex-a53'))
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