Kernel: Initialize threading and process management earlier

This re-arranges the order of how things are initialized so that we
try to initialize process and thread management earlier. This is
neccessary because a lot of the code uses the Lock class, which really
needs to have a running scheduler in place so that we can properly
preempt.

This also enables us to potentially initialize some things in parallel.

Kernel/Process.cpp

@@ -133,8 +133,10 @@ void Process::register_new(Process& process)
 {
     // Note: this is essentially the same like process->ref()
     RefPtr<Process> new_process = process;
-    ScopedSpinLock lock(g_processes_lock);
-    g_processes->prepend(process);
+    {
+        ScopedSpinLock lock(g_processes_lock);
+        g_processes->prepend(process);
+    }
     ProcFSComponentRegistry::the().register_new_process(process);
 }
 
@@ -180,7 +182,7 @@ RefPtr<Process> Process::create_user_process(RefPtr<Thread>& first_thread, const
     return process;
 }
 
-RefPtr<Process> Process::create_kernel_process(RefPtr<Thread>& first_thread, String&& name, void (*entry)(void*), void* entry_data, u32 affinity)
+RefPtr<Process> Process::create_kernel_process(RefPtr<Thread>& first_thread, String&& name, void (*entry)(void*), void* entry_data, u32 affinity, RegisterProcess do_register)
 {
     auto process = Process::create(first_thread, move(name), (uid_t)0, (gid_t)0, ProcessID(0), true);
     if (!first_thread || !process)
@@ -193,9 +195,8 @@ RefPtr<Process> Process::create_kernel_process(RefPtr<Thread>& first_thread, Str
     first_thread->regs().rdi = FlatPtr(entry_data); // entry function argument is expected to be in regs.rdi
 #endif
 
-    if (process->pid() != 0) {
+    if (do_register == RegisterProcess::Yes)
         register_new(*process);
-    }
 
     ScopedSpinLock lock(g_scheduler_lock);
     first_thread->set_affinity(affinity);

Kernel/Process.h

@@ -163,14 +163,19 @@ public:
         delete func;
     }
 
+    enum class RegisterProcess {
+        No,
+        Yes
+    };
+
     template<typename EntryFunction>
-    static RefPtr<Process> create_kernel_process(RefPtr<Thread>& first_thread, String&& name, EntryFunction entry, u32 affinity = THREAD_AFFINITY_DEFAULT)
+    static RefPtr<Process> create_kernel_process(RefPtr<Thread>& first_thread, String&& name, EntryFunction entry, u32 affinity = THREAD_AFFINITY_DEFAULT, RegisterProcess do_register = RegisterProcess::Yes)
     {
         auto* entry_func = new EntryFunction(move(entry));
-        return create_kernel_process(first_thread, move(name), &Process::kernel_process_trampoline<EntryFunction>, entry_func, affinity);
+        return create_kernel_process(first_thread, move(name), &Process::kernel_process_trampoline<EntryFunction>, entry_func, affinity, do_register);
     }
 
-    static RefPtr<Process> create_kernel_process(RefPtr<Thread>& first_thread, String&& name, void (*entry)(void*), void* entry_data = nullptr, u32 affinity = THREAD_AFFINITY_DEFAULT);
+    static RefPtr<Process> create_kernel_process(RefPtr<Thread>& first_thread, String&& name, void (*entry)(void*), void* entry_data = nullptr, u32 affinity = THREAD_AFFINITY_DEFAULT, RegisterProcess do_register = RegisterProcess::Yes);
     static RefPtr<Process> create_user_process(RefPtr<Thread>& first_thread, const String& path, uid_t, gid_t, ProcessID ppid, int& error, Vector<String>&& arguments = Vector<String>(), Vector<String>&& environment = Vector<String>(), TTY* = nullptr);
     static void register_new(Process&);
     ~Process();

Kernel/Scheduler.cpp

@@ -404,7 +404,7 @@ UNMAP_AFTER_INIT void Scheduler::initialize()
     g_ready_queues = new ThreadReadyQueue[g_ready_queue_buckets];
 
     g_finalizer_has_work.store(false, AK::MemoryOrder::memory_order_release);
-    s_colonel_process = Process::create_kernel_process(idle_thread, "colonel", idle_loop, nullptr, 1).leak_ref();
+    s_colonel_process = Process::create_kernel_process(idle_thread, "colonel", idle_loop, nullptr, 1, Process::RegisterProcess::No).leak_ref();
     VERIFY(s_colonel_process);
     VERIFY(idle_thread);
     idle_thread->set_priority(THREAD_PRIORITY_MIN);

Kernel/init.cpp

@@ -142,39 +142,21 @@ extern "C" [[noreturn]] UNMAP_AFTER_INIT void init()
     InterruptManagement::initialize();
     ACPI::initialize();
 
-    // Initialize the PCI Bus as early as possible, for early boot (PCI based) serial logging
-    SysFSComponentRegistry::initialize();
+    __stack_chk_guard = get_fast_random<u32>();
+
     ProcFSComponentRegistry::initialize();
-    PCI::initialize();
-    PCISerialDevice::detect();
-
-    VirtualFileSystem::initialize();
-
-    dmesgln("Starting SerenityOS...");
+    Thread::initialize();
+    Process::initialize();
 
     TimeManagement::initialize(0);
 
-    __stack_chk_guard = get_fast_random<u32>();
-
-    NullDevice::initialize();
-    if (!get_serial_debug())
-        (void)SerialDevice::must_create(0).leak_ref();
-    (void)SerialDevice::must_create(1).leak_ref();
-    (void)SerialDevice::must_create(2).leak_ref();
-    (void)SerialDevice::must_create(3).leak_ref();
-
-    VMWareBackdoor::the(); // don't wait until first mouse packet
-    HIDManagement::initialize();
-
-    Thread::initialize();
-    Process::initialize();
     Scheduler::initialize();
 
-    WorkQueue::initialize();
+    dmesgln("Starting SerenityOS...");
 
     {
         RefPtr<Thread> init_stage2_thread;
-        Process::create_kernel_process(init_stage2_thread, "init_stage2", init_stage2, nullptr);
+        Process::create_kernel_process(init_stage2_thread, "init_stage2", init_stage2, nullptr, THREAD_AFFINITY_DEFAULT, Process::RegisterProcess::No);
         // We need to make sure we drop the reference for init_stage2_thread
         // before calling into Scheduler::start, otherwise we will have a
         // dangling Thread that never gets cleaned up
@@ -218,6 +200,13 @@ extern "C" UNMAP_AFTER_INIT void init_finished(u32 cpu)
 
 void init_stage2(void*)
 {
+    // This is a little bit of a hack. We can't register our process at the time we're
+    // creating it, but we need to be registered otherwise finalization won't be happy.
+    // The colonel process gets away without having to do this because it never exits.
+    Process::register_new(*Process::current());
+
+    WorkQueue::initialize();
+
     if (APIC::initialized() && APIC::the().enabled_processor_count() > 1) {
         // We can't start the APs until we have a scheduler up and running.
         // We need to be able to process ICI messages, otherwise another
@@ -226,6 +215,23 @@ void init_stage2(void*)
         APIC::the().boot_aps();
     }
 
+    // Initialize the PCI Bus as early as possible, for early boot (PCI based) serial logging
+    SysFSComponentRegistry::initialize();
+    PCI::initialize();
+    PCISerialDevice::detect();
+
+    VirtualFileSystem::initialize();
+
+    NullDevice::initialize();
+    if (!get_serial_debug())
+        (void)SerialDevice::must_create(0).leak_ref();
+    (void)SerialDevice::must_create(1).leak_ref();
+    (void)SerialDevice::must_create(2).leak_ref();
+    (void)SerialDevice::must_create(3).leak_ref();
+
+    VMWareBackdoor::the(); // don't wait until first mouse packet
+    HIDManagement::initialize();
+
     GraphicsManagement::the().initialize();
     ConsoleManagement::the().initialize();