tests/functional: Convert reverse_debugging tests to the functional framework

These tests are using the gdb-related library functions from the
Avocado framework which we don't have in the functional framework
yet. So for the time being, keep those imports and skip the test
if the Avocado framework is not installed on the host.

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-ID: <20250414113031.151105-4-thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

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()