Add KvmHypTracer class
We will soon need to interact with the hypervisor tracing subsystem, so
introduce a new helper class to make this simpler.
Bug: 229975925
Test: atest AVFHostTestCase#testHypervisorLongSections
Change-Id: I3b4ca804c8759e53c3feea30d2669b4bd169f1bb
diff --git a/tests/hostside/helper/java/com/android/microdroid/test/host/KvmHypTracer.java b/tests/hostside/helper/java/com/android/microdroid/test/host/KvmHypTracer.java
new file mode 100644
index 0000000..0d8ee96
--- /dev/null
+++ b/tests/hostside/helper/java/com/android/microdroid/test/host/KvmHypTracer.java
@@ -0,0 +1,181 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.microdroid.test.host;
+
+import static com.google.common.truth.Truth.assertWithMessage;
+import static org.junit.Assert.assertNotNull;
+
+import com.android.microdroid.test.host.CommandRunner;
+import com.android.tradefed.device.ITestDevice;
+import com.android.tradefed.log.LogUtil.CLog;
+import com.android.tradefed.util.SimpleStats;
+
+import java.io.File;
+import java.io.FileReader;
+import java.io.BufferedReader;
+import java.text.ParseException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import javax.annotation.Nonnull;
+
+/** This class provides utilities to interact with the hyp tracing subsystem */
+public final class KvmHypTracer {
+
+ private static final String HYP_TRACING_ROOT = "/sys/kernel/tracing/hyp/";
+ private static final String HYP_EVENTS[] = { "hyp_enter", "hyp_exit" };
+ private static final int DEFAULT_BUF_SIZE_KB = 4 * 1024;
+ private static final Pattern LOST_EVENT_PATTERN = Pattern.compile(
+ "^CPU:[0-9]* \\[LOST ([0-9]*) EVENTS\\]");
+ private static final Pattern EVENT_PATTERN = Pattern.compile(
+ "^\\[([0-9]*)\\][ \t]*([0-9]*\\.[0-9]*): (" + String.join("|", HYP_EVENTS) + ") (.*)");
+
+ private final CommandRunner mRunner;
+ private final ITestDevice mDevice;
+ private final int mNrCpus;
+
+ private final ArrayList<File> mTraces;
+
+ private void setNode(String node, int val) throws Exception {
+ mRunner.run("echo " + val + " > " + HYP_TRACING_ROOT + node);
+ }
+
+ private static String eventDir(String event) {
+ return "events/hyp/" + event + "/";
+ }
+
+ public static boolean isSupported(ITestDevice device) throws Exception {
+ for (String event: HYP_EVENTS) {
+ if (!device.doesFileExist(HYP_TRACING_ROOT + eventDir(event) + "/enable"))
+ return false;
+ }
+ return true;
+ }
+
+ public KvmHypTracer(@Nonnull ITestDevice device) throws Exception {
+ assertWithMessage("Hypervisor tracing not supported")
+ .that(isSupported(device)).isTrue();
+
+ mDevice = device;
+ mRunner = new CommandRunner(mDevice);
+ mTraces = new ArrayList<File>();
+ mNrCpus = Integer.parseInt(mRunner.run("nproc"));
+ }
+
+ public String run(String payload_cmd) throws Exception {
+ mTraces.clear();
+
+ setNode("tracing_on", 0);
+ mRunner.run("echo 0 | tee " + HYP_TRACING_ROOT + "events/*/*/enable");
+ setNode("buffer_size_kb", DEFAULT_BUF_SIZE_KB);
+ for (String event: HYP_EVENTS)
+ setNode(eventDir(event) + "/enable", 1);
+ setNode("trace", 0);
+
+ /* Cat each per-cpu trace_pipe in its own tmp file in the background */
+ String cmd = "cd " + HYP_TRACING_ROOT + ";";
+ String trace_pipes[] = new String[mNrCpus];
+ for (int i = 0; i < mNrCpus; i++) {
+ trace_pipes[i] = mRunner.run("mktemp -t trace_pipe.cpu" + i + ".XXXXXXXXXX");
+ cmd += "cat per_cpu/cpu" + i + "/trace_pipe > " + trace_pipes[i] + " &";
+ cmd += "CPU" + i + "_TRACE_PIPE_PID=$!;";
+ }
+
+ /* Run the payload with tracing enabled */
+ cmd += "echo 1 > tracing_on;";
+ String cmd_stdout = mRunner.run("mktemp -t cmd_stdout.XXXXXXXXXX");
+ cmd += payload_cmd + " > " + cmd_stdout + ";";
+ cmd += "echo 0 > tracing_on;";
+
+ /* Actively kill the cat subprocesses as trace_pipe is blocking */
+ for (int i = 0; i < mNrCpus; i++)
+ cmd += "kill -9 $CPU" + i + "_TRACE_PIPE_PID;";
+ cmd += "wait";
+
+ /*
+ * The whole thing runs in a single command for simplicity as `adb
+ * shell` doesn't play well with subprocesses outliving their parent,
+ * and cat-ing a trace_pipe is blocking, so doing so from separate Java
+ * threads wouldn't be much easier as we would need to actively kill
+ * them too.
+ */
+ mRunner.run(cmd);
+
+ for (String t: trace_pipes) {
+ File trace = mDevice.pullFile(t);
+ assertNotNull(trace);
+ mTraces.add(trace);
+ mRunner.run("rm -f " + t);
+ }
+
+ String res = mRunner.run("cat " + cmd_stdout);
+ mRunner.run("rm -f " + cmd_stdout);
+ return res;
+ }
+
+ public SimpleStats getDurationStats() throws Exception {
+ SimpleStats stats = new SimpleStats();
+
+ for (File trace: mTraces) {
+ BufferedReader br = new BufferedReader(new FileReader(trace));
+ double last = 0.0, hyp_enter = 0.0;
+ String l, prev_event = "";
+ while ((l = br.readLine()) != null) {
+ Matcher matcher = LOST_EVENT_PATTERN.matcher(l);
+ if (matcher.find())
+ throw new OutOfMemoryError("Lost " + matcher.group(1) + " events");
+
+ matcher = EVENT_PATTERN.matcher(l);
+ if (!matcher.find()) {
+ CLog.w("Failed to parse hyp event: " + l);
+ continue;
+ }
+
+ int cpu = Integer.parseInt(matcher.group(1));
+ if (cpu < 0 || cpu >= mNrCpus)
+ throw new ParseException("Incorrect CPU number: " + cpu, 0);
+
+ double cur = Double.parseDouble(matcher.group(2));
+ if (cur < last)
+ throw new ParseException("Time must not go backward: " + cur, 0);
+ last = cur;
+
+ String event = matcher.group(3);
+ if (event.equals(prev_event)) {
+ throw new ParseException("Hyp event found twice in a row: " + trace + " - " + l,
+ 0);
+ }
+
+ switch (event) {
+ case "hyp_exit":
+ if (prev_event.equals("hyp_enter"))
+ stats.add(cur - hyp_enter);
+ break;
+ case "hyp_enter":
+ hyp_enter = cur;
+ break;
+ default:
+ throw new ParseException("Unexpected line in trace" + l, 0);
+ }
+ prev_event = event;
+ }
+ }
+
+ return stats;
+ }
+}