tests: Add switcheroo.py to fs configs directory

There was another missing file in the configs for the fs tests,
so this should allow the switcheroo tests to pass.

Change-Id: Ic4e26cceeb9209f176158b80eaaba88b47968c39

tests/gem5/fs/linux/arm/configs/switcheroo.py

@@ -0,0 +1,148 @@
+# Copyright (c) 2012 ARM Limited
+# All rights reserved.
+#
+# The license below extends only to copyright in the software and shall
+# not be construed as granting a license to any other intellectual
+# property including but not limited to intellectual property relating
+# to a hardware implementation of the functionality of the software
+# licensed hereunder.  You may use the software subject to the license
+# terms below provided that you ensure that this notice is replicated
+# unmodified and in its entirety in all distributions of the software,
+# modified or unmodified, in source code or in binary form.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met: redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer;
+# redistributions in binary form must reproduce the above copyright
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution;
+# neither the name of the copyright holders nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+import m5
+import _m5
+from m5.objects import *
+
+m5.util.addToPath("../configs/")
+from base_caches import *
+
+
+class Sequential:
+    """Sequential CPU switcher.
+
+    The sequential CPU switches between all CPUs in a system in
+    order. The CPUs in the system must have been prepared for
+    switching, which in practice means that only one CPU is switched
+    in. base_config.BaseFSSwitcheroo can be used to create such a
+    system.
+    """
+
+    def __init__(self, cpus):
+        self.first_cpu = None
+        for (cpuno, cpu) in enumerate(cpus):
+            if not cpu.switched_out:
+                if self.first_cpu != None:
+                    fatal("More than one CPU is switched in")
+                self.first_cpu = cpuno
+
+        if self.first_cpu == None:
+            fatal("The system contains no switched in CPUs")
+
+        self.cur_cpu = self.first_cpu
+        self.cpus = cpus
+
+    def next(self):
+        self.cur_cpu = (self.cur_cpu + 1) % len(self.cpus)
+        return self.cpus[self.cur_cpu]
+
+    def first(self):
+        return self.cpus[self.first_cpu]
+
+
+def run_test(root, switcher=None, freq=1000, verbose=False):
+    """Test runner for CPU switcheroo tests.
+
+    The switcheroo test runner is used to switch CPUs in a system that
+    has been prepared for CPU switching. Such systems should have
+    multiple CPUs when they are instantiated, but only one should be
+    switched in. Such configurations can be created using the
+    base_config.BaseFSSwitcheroo class.
+
+    A CPU switcher object is used to control switching. The default
+    switcher sequentially switches between all CPUs in a system,
+    starting with the CPU that is currently switched in.
+
+    Unlike most other test runners, this one automatically configures
+    the memory mode of the system based on the first CPU the switcher
+    reports.
+
+    Keyword Arguments:
+      switcher -- CPU switcher implementation. See Sequential for
+                  an example implementation.
+      period -- Switching frequency in Hz.
+      verbose -- Enable output at each switch (suppressed by default).
+    """
+
+    if switcher == None:
+        switcher = Sequential(root.system.cpu)
+
+    current_cpu = switcher.first()
+    system = root.system
+    system.mem_mode = type(current_cpu).memory_mode()
+
+    # Suppress "Entering event queue" messages since we get tons of them.
+    # Worse yet, they include the timestamp, which makes them highly
+    # variable and unsuitable for comparing as test outputs.
+    if not verbose:
+        _m5.core.setLogLevel(_m5.core.LogLevel.WARN)
+
+    # instantiate configuration
+    m5.instantiate()
+
+    # Determine the switching period, this has to be done after
+    # instantiating the system since the time base must be fixed.
+    period = m5.ticks.fromSeconds(1.0 / freq)
+    while True:
+        exit_event = m5.simulate(period)
+        exit_cause = exit_event.getCause()
+
+        if exit_cause == "simulate() limit reached":
+            next_cpu = switcher.next()
+
+            if verbose:
+                print("Switching CPUs...")
+                print(f"Next CPU: {type(next_cpu)}")
+            m5.drain()
+            if current_cpu != next_cpu:
+                m5.switchCpus(
+                    system, [(current_cpu, next_cpu)], verbose=verbose
+                )
+            else:
+                print(
+                    "Source CPU and destination CPU are the same,"
+                    " skipping..."
+                )
+            current_cpu = next_cpu
+        elif (
+            exit_cause == "target called exit()"
+            or exit_cause == "m5_exit instruction encountered"
+        ):
+
+            sys.exit(0)
+        else:
+            print(f"Test failed: Unknown exit cause: {exit_cause}")
+            sys.exit(1)