Kernel: Don't check that interrupts are enabled during early boot

The interrupts enabled check in the Kernel mutex is there so that we
don't lock mutexes within a spinlock, because mutexes reenable
interrupts and that will mess up the spinlock in more ways than one if
the thread moves processors. This check is guarded behind a debug flag
because it's too hard to fix all the problems at once, but we regressed
and weren't even getting to init stage 2 with it enabled. With this
commit, we get to stage 2 again. In early boot, there are no interrupts
enabled and spinlocks used, so we can sort of kind of safely ignore the
interrupt state. There might be a better solution with another boot
state flag that checks whether APs are up (because they have interrupts
enabled from the start) but that seems overkill.

Kernel/Locking/Mutex.cpp

@@ -12,6 +12,8 @@
 #include <Kernel/Locking/Spinlock.h>
 #include <Kernel/Thread.h>
 
+extern bool g_in_early_boot;
+
 namespace Kernel {
 
 void Mutex::lock(Mode mode, [[maybe_unused]] LockLocation const& location)
@@ -19,8 +21,11 @@ void Mutex::lock(Mode mode, [[maybe_unused]] LockLocation const& location)
     // NOTE: This may be called from an interrupt handler (not an IRQ handler)
     // and also from within critical sections!
     VERIFY(!Processor::current_in_irq());
-    if constexpr (LOCK_IN_CRITICAL_DEBUG)
-        VERIFY_INTERRUPTS_ENABLED();
+    if constexpr (LOCK_IN_CRITICAL_DEBUG) {
+        // There are no interrupts enabled in early boot.
+        if (!g_in_early_boot)
+            VERIFY_INTERRUPTS_ENABLED();
+    }
     VERIFY(mode != Mode::Unlocked);
     auto* current_thread = Thread::current();
 
@@ -147,9 +152,12 @@ void Mutex::unlock()
 {
     // NOTE: This may be called from an interrupt handler (not an IRQ handler)
     // and also from within critical sections!
-    if constexpr (LOCK_IN_CRITICAL_DEBUG)
-        VERIFY_INTERRUPTS_ENABLED();
     VERIFY(!Processor::current_in_irq());
+    if constexpr (LOCK_IN_CRITICAL_DEBUG) {
+        // There are no interrupts enabled in early boot.
+        if (!g_in_early_boot)
+            VERIFY_INTERRUPTS_ENABLED();
+    }
     auto* current_thread = Thread::current();
     SpinlockLocker lock(m_lock);
     Mode current_mode = m_mode;
@@ -205,8 +213,11 @@ void Mutex::unlock()
 
 void Mutex::block(Thread& current_thread, Mode mode, SpinlockLocker<Spinlock>& lock, u32 requested_locks)
 {
-    if constexpr (LOCK_IN_CRITICAL_DEBUG)
-        VERIFY_INTERRUPTS_ENABLED();
+    if constexpr (LOCK_IN_CRITICAL_DEBUG) {
+        // There are no interrupts enabled in early boot.
+        if (!g_in_early_boot)
+            VERIFY_INTERRUPTS_ENABLED();
+    }
     m_blocked_thread_lists.with([&](auto& lists) {
         auto append_to_list = [&]<typename L>(L& list) {
             VERIFY(!list.contains(current_thread));