Kernel: Add magic key combo (Alt+Shift+F12) to dump scheduler state

Pressing this combo will dump a list of all threads and their state
to the debug console.

This might be useful to figure out why the system is not responding.

Kernel/Devices/HID/PS2KeyboardDevice.cpp

@@ -53,6 +53,11 @@ void PS2KeyboardDevice::irq_handle_byte_read(u8 byte)
         return;
     }
 
+    if (m_modifiers == (Mod_Alt | Mod_Shift) && byte == 0x58) {
+        // Alt+Shift+F12 pressed, dump some kernel state to the debug console.
+        Scheduler::dump_scheduler_state();
+    }
+
     dbgln_if(KEYBOARD_DEBUG, "Keyboard::irq_handle_byte_read: {:#02x} {}", ch, (pressed ? "down" : "up"));
     switch (ch) {
     case 0x38:

Kernel/Scheduler.cpp

@@ -79,6 +79,7 @@ static SpinLock<u8> g_ready_queues_lock;
 static u32 g_ready_queues_mask;
 static constexpr u32 g_ready_queue_buckets = sizeof(g_ready_queues_mask) * 8;
 READONLY_AFTER_INIT static ThreadReadyQueue* g_ready_queues; // g_ready_queue_buckets entries
+static void dump_thread_list();
 
 static inline u32 thread_priority_to_priority_index(u32 thread_priority)
 {
@@ -235,29 +236,7 @@ bool Scheduler::pick_next()
     }
 
     if constexpr (SCHEDULER_RUNNABLE_DEBUG) {
-        dbgln("Scheduler thread list for processor {}:", Processor::id());
+        dump_thread_list();
-        Thread::for_each([&](Thread& thread) -> IterationDecision {
-            switch (thread.state()) {
-            case Thread::Dying:
-                dbgln("  {:12} {} @ {:04x}:{:08x} Finalizable: {}",
-                    thread.state_string(),
-                    thread,
-                    thread.tss().cs,
-                    thread.tss().eip,
-                    thread.is_finalizable());
-                break;
-            default:
-                dbgln("  {:12} Pr:{:2} {} @ {:04x}:{:08x}",
-                    thread.state_string(),
-                    thread.priority(),
-                    thread,
-                    thread.tss().cs,
-                    thread.tss().eip);
-                break;
-            }
-
-            return IterationDecision::Continue;
-        });
     }
 
     auto pending_beneficiary = scheduler_data.m_pending_beneficiary.strong_ref();
@@ -633,4 +612,51 @@ void Scheduler::idle_loop(void*)
     }
 }
 
+void Scheduler::dump_scheduler_state()
+{
+    dump_thread_list();
+}
+
+void dump_thread_list()
+{
+    dbgln("Scheduler thread list for processor {}:", Processor::id());
+
+    auto get_cs = [](Thread& thread) -> u16 {
+        if (!thread.current_trap())
+            return thread.tss().cs;
+        return thread.get_register_dump_from_stack().cs;
+    };
+
+    auto get_eip = [](Thread& thread) -> u32 {
+        if (!thread.current_trap())
+            return thread.tss().eip;
+        return thread.get_register_dump_from_stack().eip;
+    };
+
+    Thread::for_each([&](Thread& thread) -> IterationDecision {
+        switch (thread.state()) {
+        case Thread::Dying:
+            dbgln("  {:14} {:30} @ {:04x}:{:08x} Finalizable: {}, (nsched: {})",
+                thread.state_string(),
+                thread,
+                get_cs(thread),
+                get_eip(thread),
+                thread.is_finalizable(),
+                thread.times_scheduled());
+            break;
+        default:
+            dbgln("  {:14} Pr:{:2} {:30} @ {:04x}:{:08x} (nsched: {})",
+                thread.state_string(),
+                thread.priority(),
+                thread,
+                get_cs(thread),
+                get_eip(thread),
+                thread.times_scheduled());
+            break;
+        }
+
+        return IterationDecision::Continue;
+    });
+}
+
 }

Kernel/Scheduler.h

@@ -70,6 +70,7 @@ public:
     static Thread& pull_next_runnable_thread();
     static bool dequeue_runnable_thread(Thread&, bool = false);
     static void queue_runnable_thread(Thread&);
+    static void dump_scheduler_state();
 };
 
 }