Implement lock IRQ nesting via stack variables/contexts

kernel/amd64/debug.c

@@ -35,6 +35,8 @@ static void amd64_debug_serial_write (char x) {
  * Formatted printing to serial. serial_lock ensures that all prints are atomic.
  */
 void debugprintf (const char* fmt, ...) {
+  spin_lock_ctx_t ctxdbgp;
+
   if (!debug_init)
     return;
 
@@ -50,14 +52,14 @@ void debugprintf (const char* fmt, ...) {
 
   const char* p = buffer;
 
-  spin_lock (&serial_lock);
+  spin_lock (&serial_lock, &ctxdbgp);
 
   while (*p) {
     amd64_debug_serial_write (*p);
     p++;
   }
 
-  spin_unlock (&serial_lock);
+  spin_unlock (&serial_lock, &ctxdbgp);
 }
 
 /* Initialize serial */