panic: print stack trace when panicking

arch/x86/sys/amd64/CMakeLists.txt

@@ -3,6 +3,7 @@
 target_sources(gay_arch PRIVATE
     idt.S
     irq.S
+    ktrace.c
     switch.S
     systm.c
     trap.S

arch/x86/sys/amd64/ktrace.c

@@ -0,0 +1,18 @@
+/* Copyright (C) 2021 fef <owo@fef.moe>.  All rights reserved. */
+
+#include <arch/vmparam.h>
+
+#include <gay/kprintf.h>
+#include <gay/ktrace.h>
+
+void ktrace_print(void)
+{
+	void **rbp;
+	__asm__ volatile("movq (%%rbp), %0" : "=r"(rbp));
+
+	kprintf("Stack trace:\n");
+	while (rbp >= (void **)KERNBASE) {
+		kprintf("  %p\n", rbp[1]);
+		rbp = *rbp;
+	}
+}

include/gay/ktrace.h

@@ -0,0 +1,6 @@
+/* Copyright (C) 2021 fef <owo@fef.moe>.  All rights reserved. */
+
+#pragma once
+
+/** @brief Print a full stack trace to the kernel log, starting from the caller. */
+void ktrace_print(void);

include/gay/systm.h

@@ -2,6 +2,7 @@
 
 #pragma once
 
+#include <arch/cpufunc.h>
 #include <arch/trap.h>
 
 #include <gay/cdefs.h>
@@ -72,7 +73,7 @@ static inline void critical_leave(void)
 
 static inline bool in_critical(void)
 {
-	if (in_irq())
+	if (in_irq() || !intr_enabled())
 		return true;
 	return current->critnest > 0;
 }

kernel/panic.c

@@ -5,6 +5,7 @@
 #include <gay/cdefs.h>
 #include <gay/config.h>
 #include <gay/kprintf.h>
+#include <gay/ktrace.h>
 
 #include <stdarg.h>
 
@@ -22,6 +23,8 @@ void panic(const char *fmt, ...)
 	else
 		kvprintf(fmt, args);
 
+	ktrace_print();
+
 	kprintf("\nKernel version: %s\nSystem halted", GAY_VERSION_STR);
 
 	/* no need for va_end() here i guess */