一、last_log中确认recovery模式的原因

参考日志如下： [    0.264872] stage is [] [    0.264891] reason is [ RescueParty] [    0.268536]        installing_text: en_US (304 x 38 @ 1446) [    0.277906] Command : "/system/bin/recovery" "--prompt_and_wipe_data" " --reason=RescueParty" " --locale=en_US" [    0.277925] 如上日志，可以基本判断是由于系统异常出发了救援程序，救援程序与Android8.0后引入默认开启；  

二、RescueParty 简单介绍：

在 Android 8.0 中，救援程序默认处于启用状态，其实现位于  /services/core/java/com/android/server/RescueParty.java  中。在出现以下情况时，救援程序会收到有关启动和崩溃事件的信息，然后即会启动：

• system_server 在 5 分钟内重启 5 次以上。
• 永久性系统应用在 30 秒内崩溃 5 次以上。

当检测到上述某种情况时，救援程序会将其上报给下一救援级别、处理与该级别相关联的任务，并让设备继续运行，看看能否恢复。清除或重置内容的程度随级别而增加。*别会提示用户将设备恢复出厂设置。 无需特别的硬件支持即可为救援程序提供支持。实现后，设备的恢复系统必须响应  --prompt_and_wipe_data  命令，且设备必须先提供一种方法，让用户确认用户数据是否有任何损坏，然后再继续运行。此外，恢复系统还应为用户提供有关尝试再次启动设备的选项。 由于每个救援级别都会使设备再次变为可运行状态的时间延后（可能长达 5 分钟），因此设备制造商不应添加自定义救援级别。设备处于不可运行的状态的时间越长，用户发出支持请求或保修咨询，而不是自行恢复其设备的可能性就越大。 验证： 当设备具有有效的 USB 数据连接时，系统会停止所有救援事件，因为这是一个较强的信号，表示有人正在调试设备。 如需停止此类抑制行为，请运行以下命令： adb shell setprop persist.sys.enable_rescue 1 在此处，您可以触发系统或界面崩溃循环。 如需触发低级  system_server  崩溃循环，请运行以下命令： adb shell setprop debug.crash_system 1 如需触发中级 SystemUI 崩溃循环，请运行以下命令： adb shell setprop debug.crash_sysui 1 这两个崩溃循环都会启动救援逻辑。所有的救援操作也都会记录到存储在  /data/system/uiderrors.txt  中的永久性 PackageManager 日志中，以供日后进行检查和调试。此外，“软件包警告消息”部分下的每个错误报告中也会包含这些永久性的日志。

三、android 常规日志确认救援程序触发重启进入recovery模式

  由于是自动化测试，测试工程师无法准确记录问题发生的时间点，这个找log的过程比较通过，那么改善方式则是在recoverysystem重启进入recovery时写misc分区添加一个--date的参数，传递一个年月日时分秒的值，方便定位时间点。接着说，logcat的main buffer log中确认uncrypt接收到了相关指令，如下： 04-13 08:32:44.075 18774 18774 I /system/bin/uncrypt:   received command: [--prompt_and_wipe_data 04-13 08:32:44.075 18774 18774 I /system/bin/uncrypt: --reason=RescueParty 04-13 08:32:44.075 18774 18774 I /system/bin/uncrypt: --locale=en_US 04-13 08:32:44.075 18774 18774 I /system/bin/uncrypt: ] (59) 04-13 08:32:44.075 18774 18774 I /system/bin/uncrypt: [libfs_mgr]dt_fstab: Skip disabled entry for partition vendor   结合system buffer的日志分析，参考日志：     行 342: 04-13 08:32:40.717  1539  3552 I ActivityTaskManager: START u0 {act=android.intent.action.SEND_MULTIPLE typ=application/zip flg=0x10000001 clip={text/plain U: content://com.android.systemui.fileprovider/leak/hprof-1618273957401.zip} (has extras)} from uid 10033     行 356: 04-13 08:32:40.835  1539  1615 D ConnectivityService: ConnectivityService NetworkRequestInfo binderDied(NetworkRequest [ TRACK_DEFAULT id=15, [ Capabilities: INTERNET&NOT_RESTRICTED&TRUSTED Uid: 10033] ], android.os.BinderProxy@f13cf33)     行 360: 04-13 08:32:40.836  1539  2111 D ConnectivityService: releasing NetworkRequest [ TRACK_DEFAULT id=15, [ Capabilities: INTERNET&NOT_RESTRICTED&TRUSTED Uid: 10033] ] (release request)     行 493: 04-13 08:32:41.051  1539  2569 W RescueParty: Noticed 2 events for UID 10033 in last 0 sec     行 508: 04-13 08:32:41.180  1539  4649 W RescueParty: Noticed 3 events for UID 10033 in last 0 sec     行 519: 04-13 08:32:41.311  1539  5186 W RescueParty: Noticed 4 events for UID 10033 in last 0 sec     行 529: 04-13 08:32:41.463  1539  5186 W RescueParty: Noticed 5 events for UID 10033 in last 0 sec     行 532: 04-13 08:32:41.473  1539  5186 W RescueParty: Attempting rescue level RESET_SETTINGS_UNTRUSTED_DEFAULTS     行 552: 04-13 08:32:41.745  1539  4482 W RescueParty: Noticed 2 events for UID 10033 in last 0 sec     行 564: 04-13 08:32:41.851  1539  4482 W RescueParty: Noticed 3 events for UID 10033 in last 0 sec     行 573: 04-13 08:32:41.950  1539  5186 W RescueParty: Noticed 4 events for UID 10033 in last 0 sec     行 582: 04-13 08:32:42.050  1539  4649 W RescueParty: Noticed 5 events for UID 10033 in last 0 sec     行 584: 04-13 08:32:42.052  1539  4649 W RescueParty: Attempting rescue level RESET_SETTINGS_UNTRUSTED_CHANGES     行 607: 04-13 08:32:42.259  1539  5186 W RescueParty: Noticed 2 events for UID 10033 in last 0 sec     行 616: 04-13 08:32:42.355  1539 17630 W RescueParty: Noticed 3 events for UID 10033 in last 0 sec     行 625: 04-13 08:32:42.454  1539  1615 W RescueParty: Noticed 4 events for UID 10033 in last 0 sec     行 634: 04-13 08:32:42.551  1539  2083 W RescueParty: Noticed 5 events for UID 10033 in last 0 sec     行 636: 04-13 08:32:42.553  1539  2083 W RescueParty: Attempting rescue level RESET_SETTINGS_TRUSTED_DEFAULTS     行 659: 04-13 08:32:42.764  1539  5550 W RescueParty: Noticed 2 events for UID 10033 in last 0 sec     行 668: 04-13 08:32:42.867  1539  2798 W RescueParty: Noticed 3 events for UID 10033 in last 0 sec     行 677: 04-13 08:32:42.967  1539  4848 W RescueParty: Noticed 4 events for UID 10033 in last 0 sec     行 686: 04-13 08:32:43.065  1539  4848 W RescueParty: Noticed 5 events for UID 10033 in last 0 sec     行 688: 04-13 08:32:43.066  1539  4848 W RescueParty: Attempting rescue level FACTORY_RESET 触发了救援程序的*别的任务，即 提示用户将设备恢复出厂设置。 行 691: 04-13 08:32:44.087  1539  4848 I RecoverySystemService: uncrypt setup bcb successfully finished. 紧接着，rss触发重启。

 

四、系统异常原因分析

  如上log确认为systemui crash导致异常的发生，那么从crash log中再次确认异常原因： 04-13 08:32:41.459 18431 18431 E AndroidRuntime: FATAL EXCEPTION: main 04-13 08:32:41.459 18431 18431 E AndroidRuntime: Process: com.android.systemui, PID: 18431 04-13 08:32:41.459 18431 18431 E AndroidRuntime: java.lang.RuntimeException: Unable to get provider com.android.systemui.keyguard.KeyguardSliceProvider: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.telephony.UiccSlotInfo.getLogicalSlotIdx()' on a null object reference 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at android.app.ActivityThread.installProvider(ActivityThread.java:7207) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at android.app.ActivityThread.installContentProviders(ActivityThread.java:6747) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at android.app.ActivityThread.handleBindApplication(ActivityThread.java:6658) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at android.app.ActivityThread.access$1400(ActivityThread.java:233) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1995) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:107) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at android.os.Looper.loop(Looper.java:241) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:7582) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at java.lang.reflect.Method.invoke(Native Method) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:941) 04-13 08:32:41.459 18431 18431 E AndroidRuntime: Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.telephony.UiccSlotInfo.getLogicalSlotIdx()' on a null object reference 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at com.android.keyguard.KeyguardUpdateMonitor.isEsim(KeyguardUpdateMonitor.java:3053) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at com.android.keyguard.KeyguardUpdateMonitor.<init>(KeyguardUpdateMonitor.java:2129) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at com.android.keyguard.KeyguardUpdateMonitor.getInstance(KeyguardUpdateMonitor.java:1915) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at com.android.systemui.keyguard.KeyguardSliceProvider.getKeyguardUpdateMonitor(KeyguardSliceProvider.java:461) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at com.android.systemui.keyguard.KeyguardSliceProvider.registerClockUpdate(KeyguardSliceProvider.java:406) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at com.android.systemui.keyguard.KeyguardSliceProvider.onCreateSliceProvider(KeyguardSliceProvider.java:327) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at androidx.slice.SliceProvider.onCreate(SliceProvider.java:208) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at android.content.ContentProvider.attachInfo(ContentProvider.java:2092) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at android.content.ContentProvider.attachInfo(ContentProvider.java:2066) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at androidx.slice.compat.SliceProviderWrapperContainer$SliceProviderWrapper.attachInfo(SliceProviderWrapperContainer.java:77) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     at android.app.ActivityThread.installProvider(ActivityThread.java:7202) 04-13 08:32:41.459 18431 18431 E AndroidRuntime:     ... 10 more 最终解决掉systemui空指针问题即可。