リカバリに入るには、キーの組み合わせでリカバリに入る方法と、アプリケーションの上部設定でインストール/リセット/キャッシュクリアなどの操作を行ってリカバリを行う方法があります。このドキュメントでは主に、上位層のアプリケーションがどのようにリカバリに入るのかについて説明します。この記事では、Qualcomm プラットフォームを例として取り上げます。
1. アプリはインストール/リセット/キャッシュのクリア操作を実行して、コード ファイルFrameworks/base/core/java/android/os/RecoverySystem.java を呼び出します。
操作ごとに異なる方法が使用されます。
アップグレードパッケージをインストールします -------- installPackage
ユーザーデータのクリア ------ rebootWipeUserData
キャッシュのクリア ----------- rebootWipeCache
上記の操作はすべて、/cache/recovery/command ファイルにさまざまなコマンドを書き込むことです。リカバリ (recovery.cpp) に入ってコマンドのキーワードを判断し、対応する操作を実行した後、以下で詳しく説明します。簡単に言及します。
bootable/recovery/recovery.app
static const struct option OPTIONS[] = {
{ "send_intent", required_argument, NULL, 'i' },
{ "update_package", required_argument, NULL, 'u' },
#ifdef TARGET_USE_REDBEND_FOTA
{ "omadm_package", required_argument, NULL, 'o' },
#endif
{ "wipe_data", no_argument, NULL, 'w' },
{ "wipe_cache", no_argument, NULL, 'c' },
{ "show_text", no_argument, NULL, 't' },
{ "sideload", no_argument, NULL, 's' },
{ "sideload_auto_reboot", no_argument, NULL, 'a' },
{ "just_exit", no_argument, NULL, 'x' },
{ "locale", required_argument, NULL, 'l' },
{ "stages", required_argument, NULL, 'g' },
{ "shutdown_after", no_argument, NULL, 'p' },
{ "reason", required_argument, NULL, 'r' },
{ NULL, 0, NULL, 0 },
};
..................
int
main(int argc, char **argv) {
....
get_args(&argc, &argv); //提取cache/recovery/command中的信息
....
while ((arg = getopt_long(argc, argv, "", OPTIONS, NULL)) != -1) { //解析cache/recovery/command文件中的信息
printf("***** xiaolei 2\n");
switch (arg) {
case 'i': send_intent = optarg; break;
case 'u': update_package = optarg; break;
case 'w': should_wipe_data = true; break;
case 'c': should_wipe_cache = true; break;
case 't': show_text = true; break;
case 's': sideload = true; break;
case 'a': sideload = true; sideload_auto_reboot = true; break;
case 'x': just_exit = true; break;
case 'l': locale = optarg; break;
case 'g': {
if (stage == NULL || *stage == '\0') {
char buffer[20] = "1/";
strncat(buffer, optarg, sizeof(buffer)-3);
stage = strdup(buffer);
}
break;
}
case 'p': shutdown_after = true; break;
case 'r': reason = optarg; break;
case '?':
LOGE("Invalid command argument\n");
continue;
}
}
}
この記事では、installPackage を例として取り上げます。
frameworks/base/core/java/android/os/RecoverySystem.java
public static void installPackage(Context context, File packageFile)
throws IOException {
String filename = packageFile.getCanonicalPath(); //获取升级包路径
String internalPath = Environment.maybeTranslateEmulatedPathToInternal(new File(filename)).getPath();
FileWriter uncryptFile = new FileWriter(UNCRYPT_FILE);
try {
uncryptFile.write(internalPath + "\n");
} finally {
uncryptFile.close();
}
Log.w(TAG, "!!! REBOOTING TO INSTALL " + filename + " !!!");
Log.w(TAG, "!!! REBOOTING TO INSTALL REALPATH " + internalPath + " !!!");
// If the package is on the /data partition, write the block map file
// If the package is on internal storage sdcard,write the block map file
// into COMMAND_FILE instead.
if (filename.startsWith("/data/") //加密处理，block.map是解密的映射文件
||filename.startsWith("/storage/emulated/0/")) {
filename = "@/cache/recovery/block.map";
}
final String filenameArg = "--update_package=" + filename; //把“--update_package=path” 通过bootCommand方法写入到cache/recovery/command文件中
final String localeArg = "--locale=" + Locale.getDefault().toString(); //recovery显示语言
bootCommand(context, filenameArg, localeArg);
}
installPackage方法会嗲用bootCommand()方法，此时参数为（context,向cache/recovery/command文件中写入的信息，语言信息）
private static void bootCommand(Context context, String... args) throws IOException {
RECOVERY_DIR.mkdirs(); // In case we need it
COMMAND_FILE.delete(); // In case it's not writable
LOG_FILE.delete();
FileWriter command = new FileWriter(COMMAND_FILE); //向/cache/recovery/command中写入--update_package=path
try {
for (String arg : args) {
if (!TextUtils.isEmpty(arg)) {
command.write(arg);
command.write("\n");
}
}
} finally {
command.close();
}
// Having written the command file, go ahead and reboot
PowerManager pm = (PowerManager) context.getSystemService(Context.POWER_SERVICE);
pm.reboot(PowerManager.REBOOT_RECOVERY); //PowerManager.REBOOT_RECOVERY的值为字符串"recovery"
throw new IOException("Reboot failed (no permissions?)");
}pm.reboot(PowerManager.REBOOT_RECOVERY); 参数为字符串("recovery")
frameworks/base/core/java/android/os/PowerMangager.java
public void reboot(String reason) {
try {
mService.reboot(false, reason, true);
} catch (RemoteException e) {
}
} mService.reboot(false, reason, true); 参数为(false,"recovery",true)frameworks/base/services/core/java/com/android/server/power/PowerManagerService.java
public void reboot(boolean confirm, String reason, boolean wait) {
mContext.enforceCallingOrSelfPermission(android.Manifest.permission.REBOOT, null);
if (PowerManager.REBOOT_RECOVERY.equals(reason)) {
mContext.enforceCallingOrSelfPermission(android.Manifest.permission.RECOVERY, null);
}
final long ident = Binder.clearCallingIdentity();
try {
shutdownOrRebootInternal(false, confirm, reason, wait);
} finally {
Binder.restoreCallingIdentity(ident);
}
}shutdownOrRebootInternal(false, confirm, reason, wait); 参数为(false,false,"recovery",true)frameworks/base/services/core/java/com/android/server/power/PowerManagerService.java
private void shutdownOrRebootInternal(final boolean shutdown, final boolean confirm,
final String reason, boolean wait) {
if (mHandler == null || !mSystemReady) {
throw new IllegalStateException("Too early to call shutdown() or reboot()");
}
Runnable runnable = new Runnable() {
@Override
public void run() {
synchronized (this) {
if (shutdown) { //此处shutdown=false
ShutdownThread.shutdown(mContext, confirm);
} else {
ShutdownThread.reboot(mContext, reason, confirm); //执行此处代码
}
}
}
};
// ShutdownThread must run on a looper capable of displaying the UI.
Message msg = Message.obtain(mHandler, runnable);
msg.setAsynchronous(true);
mHandler.sendMessage(msg);
// PowerManager.reboot() is documented not to return so just wait for the inevitable.
if (wait) {
synchronized (runnable) {
while (true) {
try {
runnable.wait();
} catch (InterruptedException e) {
}
}
}
}
}ShutdownThread.reboot(mContext, reason, confirm); 参数为(mContex,"recovery",false)
此处开了一个线程处理rebootframeworks/base/services/core/java/com/android/server/power/ShutdownThread.java
public static void reboot(final Context context, String reason, boolean confirm) { //方法中的变量为全局变量
mReboot = true;
mRebootSafeMode = false;
mRebootUpdate = false;
mRebootReason = reason;
shutdownInner(context, confirm); //此方法是在手机界面上弹出一个确认框，是否重启，此处的代码不再追了
}
//程序一定会执行run()方法
/***********************
mReboot = true;
mRebootSafeMode = false;
mRebootUpdate = false; mRebootReason = "recovery";
***********************/
public void run() {
BroadcastReceiver br = new BroadcastReceiver() {
@Override public void onReceive(Context context, Intent intent) {
// We don't allow apps to cancel this, so ignore the result.
actionDone();
}
};
/*
* Write a system property in case the system_server reboots before we
* get to the actual hardware restart. If that happens, we'll retry at
* the beginning of the SystemServer startup.
*/
{
String reason = (mReboot ? "1" : "0") + (mRebootReason != null ? mRebootReason : ""); //reason的值为"recovery"
SystemProperties.set(SHUTDOWN_ACTION_PROPERTY, reason); //设置系统属性sys.shutdown.requested = "recovery"
}
/*
* If we are rebooting into safe mode, write a system property
* indicating so.
*/
if (mRebootSafeMode) {
SystemProperties.set(REBOOT_SAFEMODE_PROPERTY, "1");
}
Log.i(TAG, "Sending shutdown broadcast...");
setBootValue("silent_mode",mAudioManager.isSilentMode() ? "1" : "0");
if(checkAnimationFileExist() && mContext.getResources().
getBoolean(com.android.internal.R.bool.feature_tctfw_shutdown_animation_on) &&
!mRebootUpdate) {
lockDevice();
showShutdownAnimation();
}
// First send the high-level shut down broadcast.
mActionDone = false;
Intent intent = new Intent(Intent.ACTION_SHUTDOWN);
intent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND);
mContext.sendOrderedBroadcastAsUser(intent,
UserHandle.ALL, null, br, mHandler, 0, null, null);
final long endTime = SystemClock.elapsedRealtime() + MAX_BROADCAST_TIME;
synchronized (mActionDoneSync) {
while (!mActionDone) {
long delay = endTime - SystemClock.elapsedRealtime();
if (delay <= 0) {
Log.w(TAG, "Shutdown broadcast timed out");
break;
} else if (mRebootUpdate) {
int status = (int)((MAX_BROADCAST_TIME - delay) * 1.0 *
BROADCAST_STOP_PERCENT / MAX_BROADCAST_TIME);
sInstance.setRebootProgress(status, null);
}
try {
mActionDoneSync.wait(Math.min(delay, PHONE_STATE_POLL_SLEEP_MSEC));
} catch (InterruptedException e) {
}
}
}
if (mRebootUpdate) {
sInstance.setRebootProgress(BROADCAST_STOP_PERCENT, null);
}
Log.i(TAG, "Shutting down activity manager...");
final IActivityManager am =
ActivityManagerNative.asInterface(ServiceManager.checkService("activity"));
if (am != null) {
try {
am.shutdown(MAX_BROADCAST_TIME);
} catch (RemoteException e) {
}
}
if (mRebootUpdate) {
sInstance.setRebootProgress(ACTIVITY_MANAGER_STOP_PERCENT, null);
}
Log.i(TAG, "Shutting down package manager...");
final PackageManagerService pm = (PackageManagerService)
ServiceManager.getService("package");
if (pm != null) {
pm.shutdown();
}
if (mRebootUpdate) {
sInstance.setRebootProgress(PACKAGE_MANAGER_STOP_PERCENT, null);
}
// Shutdown radios.
shutdownRadios(MAX_RADIO_WAIT_TIME);
if (mRebootUpdate) {
sInstance.setRebootProgress(RADIO_STOP_PERCENT, null);
}
// Mod-by-yanxi.liu, for sdcard upgrade uncrypt, Defect-1357392
if (mRebootUpdate) {
sInstance.setRebootProgress(MOUNT_SERVICE_STOP_PERCENT, null);
// If it's to reboot to install update, invoke uncrypt via init service.
uncrypt();
}
// Mod-by-yanxi.liu, for sdcard upgrade uncrypt, Defect-1357392
// Shutdown MountService to ensure media is in a safe state
IMountShutdownObserver observer = new IMountShutdownObserver.Stub() {
public void onShutDownComplete(int statusCode) throws RemoteException {
Log.w(TAG, "Result code " + statusCode + " from MountService.shutdown");
actionDone();
}
};
Log.i(TAG, "Shutting down MountService");
// Set initial variables and time out time.
mActionDone = false;
final long endShutTime = SystemClock.elapsedRealtime() + MAX_SHUTDOWN_WAIT_TIME;
synchronized (mActionDoneSync) {
try {
final IMountService mount = IMountService.Stub.asInterface(
ServiceManager.checkService("mount"));
if (mount != null) {
mount.shutdown(observer);
} else {
Log.w(TAG, "MountService unavailable for shutdown");
}
} catch (Exception e) {
Log.e(TAG, "Exception during MountService shutdown", e);
}
while (!mActionDone) {
long delay = endShutTime - SystemClock.elapsedRealtime();
if (delay <= 0) {
Log.w(TAG, "Shutdown wait timed out");
break;
} else if (mRebootUpdate) {
int status = (int)((MAX_SHUTDOWN_WAIT_TIME - delay) * 1.0 *
(MOUNT_SERVICE_STOP_PERCENT - RADIO_STOP_PERCENT) /
MAX_SHUTDOWN_WAIT_TIME);
status += RADIO_STOP_PERCENT;
sInstance.setRebootProgress(status, null);
}
try {
mActionDoneSync.wait(Math.min(delay, PHONE_STATE_POLL_SLEEP_MSEC));
} catch (InterruptedException e) {
}
}
}
// add by feikuang for defect 1453123 start
isVibrate = mContext.getResources().getBoolean(com.android.internal.R.bool.config_isVibrate);
Log.i(TAG,"isVibrate " + isVibrate);
// add by feikuang for defect 1453123 end
waitShutDownAnimationCompleted();
rebootOrShutdown(mContext, mReboot, mRebootReason); //程序执行到这里
}
rebootOrShutdown(mContext, mReboot, mRebootReason); 参数为(mContext,true,"recovery")frameworks/base/services/core/java/com/android/server/power/ShutdownThread.java
public static void rebootOrShutdown(final Context context, boolean reboot, String reason) {
deviceRebootOrShutdown(reboot, reason);
//[FEATURE]-Add-BEGIN by TSNJ.shu.wang,11/06/2015,TASK-871146
String bootAlarms = SystemProperties.get("sys.boot.alarm");
boolean isBootAlarms = bootAlarms != null && bootAlarms.equals("1");
if (reboot) {
Log.i(TAG, "Rebooting, reason: " + reason);
PowerManagerService.lowLevelReboot(reason); //程序执行到这里
Log.e(TAG, "Reboot failed, will attempt shutdown instead");
} else if (SHUTDOWN_VIBRATE_MS > 0 && context != null && !isBootAlarms && isVibrate) {
//[FEATURE]-Add-END by TSNJ.shu.wang,11/06/2015,TASK-871146
// vibrate before shutting down
Vibrator vibrator = new SystemVibrator(context);
try {
vibrator.vibrate(SHUTDOWN_VIBRATE_MS, VIBRATION_ATTRIBUTES);
} catch (Exception e) {
// Failure to vibrate shouldn't interrupt shutdown. Just log it.
Log.w(TAG, "Failed to vibrate during shutdown.", e);
}
// vibrator is asynchronous so we need to wait to avoid shutting down too soon.
try {
Thread.sleep(SHUTDOWN_VIBRATE_MS);
} catch (InterruptedException unused) {
}
}
// Shutdown power
Log.i(TAG, "Performing low-level shutdown...");
PowerManagerService.lowLevelShutdown();
}PowerManagerService.lowLevelReboot(reason); 参数为"recovery"frameworks/base/services/core/java/com/android/server/power/PowerManagerService.java
public static void lowLevelReboot(String reason) {
if (reason == null) {
reason = "";
}
if (reason.equals(PowerManager.REBOOT_RECOVERY)) {
// If we are rebooting to go into recovery, instead of
// setting sys.powerctl directly we'll start the
// pre-recovery service which will do some preparation for
// recovery and then reboot for us.
SystemProperties.set("ctl.start", "pre-recovery"); //到这里可以知道，一个新的进程会被enable
} else {
SystemProperties.set("sys.powerctl", "reboot," + reason);
}
try {
Thread.sleep(20 * 1000L);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
Slog.wtf(TAG, "Unexpected return from lowLevelReboot!");
}SystemProperties.set("ctl.start", "pre-recovery"); //到这里可以知道，一个新的进程会被enable
system/core/rootdir/init.rc
service pre-recovery /system/bin/uncrypt --reboot
class main
disabled
oneshotservice pre-recovery /system/bin/uncrypt --reboot system/bin/uncrypt 这个程序会被执行，传入的参数是--reboot
uncrypt的源码位于bootable/recovery/uncrypt/uncrypt.cpp，下面对uncrypt进行分析bootable/recovery/uncrypt/uncrypt.cpp
int main(int argc, char** argv) { //此处argc为2 argv[1]="--reboot"
const char* input_path;
const char* map_file;
if (argc != 3 && argc != 1 && (argc == 2 && strcmp(argv[1], "--reboot") != 0)) {
fprintf(stderr, "usage: %s [--reboot] [<transform_path> <map_file>]\n", argv[0]);
return 2;
}
// When uncrypt is started with "--reboot", it wipes misc and reboots.
// Otherwise it uncrypts the package and writes the block map.
if (argc == 2) { //程序执行到此处
if (read_fstab() == NULL) {
return 1;
}
wipe_misc(); //擦出misc分区内容
reboot_to_recovery(); //重启到recovery
} else {
// The pipe has been created by the system server.
int status_fd = open(status_file.c_str(), O_WRONLY | O_CREAT | O_SYNC, S_IRUSR | S_IWUSR);
if (status_fd == -1) {
ALOGE("failed to open pipe \"%s\": %s\n", status_file.c_str(), strerror(errno));
return 1;
}
std::string package;
if (argc == 3) {
// when command-line args are given this binary is being used
// for debugging.
input_path = argv[1];
map_file = argv[2];
} else {
if (!find_uncrypt_package(package)) {
android::base::WriteStringToFd("-1\n", status_fd);
close(status_fd);
return 1;
}
input_path = package.c_str();
map_file = cache_block_map.c_str();
}
int status = uncrypt(input_path, map_file, status_fd);
if (status != 0) {
android::base::WriteStringToFd("-1\n", status_fd);
close(status_fd);
return 1;
}
android::base::WriteStringToFd("100\n", status_fd);
close(status_fd);
}
return 0;
}bootable/recovery/uncrpty/uncrpty.cpp
static void reboot_to_recovery() {
ALOGI("rebooting to recovery");
property_set("sys.powerctl", "reboot,recovery");
sleep(10);
ALOGE("reboot didn't succeed?");
}property_set("sys.powerctl", "reboot,recovery"); sys.powerctl属性出发开关在init.rc中system/core/rootdir/init.rc
on property:sys.powerctl=*
powerctl ${sys.powerctl}system/core/init/keywords.h
KEYWORD(powerctl, COMMAND, 1, do_powerctlsystem/core/init/builtins.cpp
int do_powerctl(int nargs, char **args) //传入的参数为字符串"reboot,recovery"
{
char command[PROP_VALUE_MAX];
int res;
int len = 0;
int cmd = 0;
const char *reboot_target;
res = expand_props(command, args[1], sizeof(command));
if (res) {
ERROR("powerctl: cannot expand '%s'\n", args[1]);
return -EINVAL;
}
if (strncmp(command, "shutdown", 8) == 0) {
cmd = ANDROID_RB_POWEROFF;
len = 8;
} else if (strncmp(command, "reboot", 6) == 0) { //程序走到这，cmd=ANDROID_RB_RESTART2
cmd = ANDROID_RB_RESTART2;
len = 6;
} else {
ERROR("powerctl: unrecognized command '%s'\n", command);
return -EINVAL;
}
if (command[len] == ',') {
char prop_value[PROP_VALUE_MAX] = {0};
reboot_target = &command[len + 1]; //设置reboot_target = recovery
if ((property_get("init.svc.recovery", prop_value) == 0) &&
(strncmp(reboot_target, "keys", 4) == 0)) {
ERROR("powerctl: permission denied\n");
return -EINVAL;
}
} else if (command[len] == '\0') {
reboot_target = "";
} else {
ERROR("powerctl: unrecognized reboot target '%s'\n", &command[len]);
return -EINVAL;
}
return android_reboot(cmd, 0, reboot_target);
}android_reboot(cmd, 0, reboot_target); 参数为(ANDROID_RB_RESTART2, 0, "recovery")system/core/libcutils/android_reboot.c
int android_reboot(int cmd, int flags UNUSED, const char *arg)
{
int ret;
sync();
remount_ro();
switch (cmd) {
case ANDROID_RB_RESTART:
ret = reboot(RB_AUTOBOOT);
break;
case ANDROID_RB_POWEROFF:
ret = reboot(RB_POWER_OFF);
break;
case ANDROID_RB_RESTART2: //程序跑到这里其中arg="recovery"
ret = syscall(__NR_reboot, LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,
LINUX_REBOOT_CMD_RESTART2, arg);
break;
default:
ret = -1;
}
return ret;
}ret = syscall(__NR_reboot, LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,
LINUX_REBOOT_CMD_RESTART2, arg);kernel/include/uapi/asm-generic/unistd.h
#define __NR_reboot 142
__SYSCALL(__NR_reboot, sys_reboot）__NR_reboot が sys_reboot にマッピングされ、SYSCALL_DEFINE4() が実行されることになりますが、なぜこのように実行されるのかは不明です。
kernel/kernel/sys.c
SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
void __user *, arg) //对应LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2, LINUX_REBOOT_CMD_RESTART2, "recovery"
{
struct pid_namespace *pid_ns = task_active_pid_ns(current);
char buffer[256];
int ret = 0;
/* We only trust the superuser with rebooting the system. */
if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT))
return -EPERM;
/* For safety, we require "magic" arguments. */
if (magic1 != LINUX_REBOOT_MAGIC1 ||
(magic2 != LINUX_REBOOT_MAGIC2 &&
magic2 != LINUX_REBOOT_MAGIC2A &&
magic2 != LINUX_REBOOT_MAGIC2B &&
magic2 != LINUX_REBOOT_MAGIC2C))
return -EINVAL;
/*
* If pid namespaces are enabled and the current task is in a child
* pid_namespace, the command is handled by reboot_pid_ns() which will
* call do_exit().
*/
ret = reboot_pid_ns(pid_ns, cmd);
if (ret)
return ret;
/* Instead of trying to make the power_off code look like
* halt when pm_power_off is not set do it the easy way.
*/
if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off)
cmd = LINUX_REBOOT_CMD_HALT;
mutex_lock(&reboot_mutex);
switch (cmd) {
case LINUX_REBOOT_CMD_RESTART:
kernel_restart(NULL);
break;
case LINUX_REBOOT_CMD_CAD_ON:
C_A_D = 1;
break;
case LINUX_REBOOT_CMD_CAD_OFF:
C_A_D = 0;
break;
case LINUX_REBOOT_CMD_HALT:
kernel_halt();
do_exit(0);
panic("cannot halt");
case LINUX_REBOOT_CMD_POWER_OFF:
kernel_power_off();
do_exit(0);
break;
case LINUX_REBOOT_CMD_RESTART2:
if (strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1) < 0) {
ret = -EFAULT;
break;
}
buffer[sizeof(buffer) - 1] = '\0';
kernel_restart(buffer); //程序会跑到这里
break;
#ifdef CONFIG_KEXEC
case LINUX_REBOOT_CMD_KEXEC:
ret = kernel_kexec();
break;
#endif
#ifdef CONFIG_HIBERNATION
case LINUX_REBOOT_CMD_SW_SUSPEND:
ret = hibernate();
break;
#endif
default:
ret = -EINVAL;
break;
}
mutex_unlock(&reboot_mutex);
return ret;
}kernel_restart(buffer); 参数为("recovery")kernel/kernel/sys.c
void kernel_restart(char *cmd)
{
kernel_restart_prepare(cmd);
migrate_to_reboot_cpu();
syscore_shutdown();
if (!cmd)
printk(KERN_EMERG "Restarting system.\n");
else
printk(KERN_EMERG "Restarting system with command '%s'.\n", cmd);
kmsg_dump(KMSG_DUMP_RESTART);
machine_restart(cmd);
}machine_restart(cmd); パラメータは ("recovery") です。
kernel/arch/arm/kernel/process.c
void machine_restart(char *cmd)
{
preempt_disable();
smp_send_stop();
/* Flush the console to make sure all the relevant messages make it
* out to the console drivers */
arm_machine_flush_console();
arm_pm_restart(reboot_mode, cmd);
/* Give a grace period for failure to restart of 1s */
mdelay(1000);
/* Whoops - the platform was unable to reboot. Tell the user! */
printk("Reboot failed -- System halted\n");
local_irq_disable();
while (1);
}arm_pm_restart(reboot_mode, cmd);
kernel/drivers/power/reset/msm-poweroff.c
static int msm_restart_probe(struct platform_device *pdev)
{
.....
arm_pm_restart = do_msm_restart;
.....
}kernel/drivers/power/reset/msm-poweroff.c
static void do_msm_restart(enum reboot_mode reboot_mode, const char *cmd)
{
int ret;
struct scm_desc desc = {
.args[0] = 1,
.args[1] = 0,
.arginfo = SCM_ARGS(2),
};
pr_notice("Going down for restart now\n");
msm_restart_prepare(cmd); //程序走到这里
#ifdef CONFIG_MSM_DLOAD_MODE
/*
* Trigger a watchdog bite here and if this fails,
* device will take the usual restart path.
*/
if (WDOG_BITE_ON_PANIC && in_panic)
msm_trigger_wdog_bite();
#endif
/* Needed to bypass debug image on some chips */
if (!is_scm_armv8())
ret = scm_call_atomic2(SCM_SVC_BOOT,
SCM_WDOG_DEBUG_BOOT_PART, 1, 0);
else
ret = scm_call2_atomic(SCM_SIP_FNID(SCM_SVC_BOOT,
SCM_WDOG_DEBUG_BOOT_PART), &desc);
if (ret)
pr_err("Failed to disable secure wdog debug: %d\n", ret);
halt_spmi_pmic_arbiter();
deassert_ps_hold();
mdelay(10000);
}msm_restart_prepare(cmd); 参数为("recovery")kernel/drivers/power/reset/msm-poweroff.c
static void msm_restart_prepare(const char *cmd)
{
#ifdef CONFIG_MSM_SUBSYSTEM_RESTART
extern char panic_subsystem[];
#endif /* CONFIG_MSM_SUBSYSTEM_RESTART */
bool need_warm_reset = false;
#ifdef CONFIG_MSM_DLOAD_MODE
/* Write download mode flags if we're panic'ing
* Write download mode flags if restart_mode says so
* Kill download mode if master-kill switch is set
*/
set_dload_mode(download_mode &&
(in_panic || restart_mode == RESTART_DLOAD));
#endif
if (qpnp_pon_check_hard_reset_stored()) {
/* Set warm reset as true when device is in dload mode
* or device doesn't boot up into recovery, bootloader or rtc.
*/
if (get_dload_mode() ||
((cmd != NULL && cmd[0] != '\0') &&
strcmp(cmd, "recovery") &&
strcmp(cmd, "bootloader") &&
strcmp(cmd, "rtc")))
need_warm_reset = true;
} else {
need_warm_reset = (get_dload_mode() ||
(cmd != NULL && cmd[0] != '\0'));
}
/* Hard reset the PMIC unless memory contents must be maintained. */
if (need_warm_reset || restart_mode == RESTART_DLOAD) {// MODIFIED by xin.peng, 2016-03-21, BUG-1761259
qpnp_pon_system_pwr_off(PON_POWER_OFF_WARM_RESET);
} else {
qpnp_pon_system_pwr_off(PON_POWER_OFF_HARD_RESET);
}
if (cmd != NULL) {
if (!strncmp(cmd, "bootloader", 10)) {
qpnp_pon_set_restart_reason(
PON_RESTART_REASON_BOOTLOADER);
__raw_writel(0x77665500, restart_reason);
} else if (!strncmp(cmd, "recovery", 8)) {
qpnp_pon_set_restart_reason(
PON_RESTART_REASON_RECOVERY);
__raw_writel(0x77665502, restart_reason); //********************
else if (!strcmp(cmd, "rtc")) {
qpnp_pon_set_restart_reason(
PON_RESTART_REASON_RTC);
__raw_writel(0x77665503, restart_reason);
} else if (!strncmp(cmd, "oem-", 4)) {
unsigned long code;
int ret;
ret = kstrtoul(cmd + 4, 16, &code);
if (!ret)
__raw_writel(0x6f656d00 | (code & 0xff),
restart_reason);
if (download_mode && (code & 0xff) == 0x3a)
set_dload_mode(1);
} else if (!strncmp(cmd, "edl", 3)) {
enable_emergency_dload_mode();
} else {
__raw_writel(0x77665501, restart_reason);
}
}
#ifdef CONFIG_MSM_SUBSYSTEM_RESTART
if (in_panic) {
printk(KERN_ERR "subsystem %s crash\n", panic_subsystem);
if (!memcmp(panic_subsystem, "modem", 5)) {
__raw_writel(0x6f656dc1, restart_reason);
} else if (!memcmp(panic_subsystem, "wcnss", 5)) {
__raw_writel(0x6f656dc2, restart_reason);
} else if (!memcmp(panic_subsystem, "adsp", 4) || !memcmp(panic_subsystem, "ADSP", 4)) {
__raw_writel(0x6f656dc3, restart_reason);
} else if (!memcmp(panic_subsystem, "venus", 5)) {
__raw_writel(0x6f656dc4, restart_reason);
} else {
__raw_writel(0x6f656dc0, restart_reason);
}
if (download_mode)
set_dload_mode(1);
}
#endif /* CONFIG_MSM_SUBSYSTEM_RESTART */
//add begin by liping.gao,Powering on mode switch to 9008 mode,task:665748
if (restart_mode == RESTART_DLOAD) {
enable_emergency_dload_mode();
}
//add end by liping.gao
flush_cache_all();
/*outer_flush_all is not supported by 64bit kernel*/
#ifndef CONFIG_ARM64
outer_flush_all();
#endif
}__raw_writel(0x77665502, restart_reason); //在地址上0x77665502写入"recovery"
应用执行升级/清缓存/重置等操作导致底层在地址0x77665502写入"recovery"
当开机以后，在lk阶段会判断这个地址的值，如果是recovery，会设置boot_into_recovery=1,然后读取recovery.img镜像，把recovery.img的地址和ramdisk等信息作为参数启动kernel，从而进入recovery模式，下面进行简单的分析。
lk阶段：bootable/bootloader/lk/app/aboot/aboot.c
......
#define RECOVERY_MODE 0x77665502
......
reboot_mode = check_reboot_mode();
hard_reboot_mode = check_hard_reboot_mode();
if (reboot_mode == RECOVERY_MODE ||
hard_reboot_mode == RECOVERY_HARD_RESET_MODE) {
boot_into_recovery = 1;
}
.....
----------
著者：JKjiang123
出典：CSDN
原文：https://blog.csdn.net/JKjiang123/article/details/77193402
著作権表示：これ記事 著者のオリジナル記事。転載する場合はブログ投稿のリンクを添付してください。
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