进入 recovery有两种方式，一种是通过组合键进入 recovery，另一种是上层应用设置中执行安装 /重置 /清除缓存等操作进行 recovery。这篇文档主要讲解上层应用是如何进入到 recovery的。本文以高通平台为例。
1.app执行安装/重置/清楚缓存操作调用代码文件frameworks/base/core/java/android/os/RecoverySystem.java
不同的操作使用不同的方法：
安装升级包 -------- installPackage
清除用户数据------ rebootWipeUserData
清楚缓存 ----------- rebootWipeCache
上面的所有操作都是往/cache/recovery/command文件中写入不同的命令，在进入recovery后（recovery.cpp）对command的关键字进行判断，执行相应的操作，下文会详细讲解，这里先简单提及。
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;
}
}
}
本文以installPackage为例：
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被映射到sys_reboot上,会执行SYSCALL_DEFINE4(),为什么会这么执行还不清楚。
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); 参数为("recovery")
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;
}
.....
---------------------
作者：JKjiang123
来源：优快云
原文：https://blog.youkuaiyun.com/JKjiang123/article/details/77193402
版权声明：本文为作者原创文章，转载请附上博文链接！
内容解析By：优快云,CNBLOG博客文章一键转载插件
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