From 7f92690f84e6f4220430fb30267f44ec19ce9a97 Mon Sep 17 00:00:00 2001
From: fef <owo@fef.moe>
Date: Sun, 21 Nov 2021 06:57:24 +0100
Subject: [PATCH] panic: print stack trace when panicking

---
 arch/x86/sys/amd64/CMakeLists.txt |  1 +
 arch/x86/sys/amd64/ktrace.c       | 18 ++++++++++++++++++
 include/gay/ktrace.h              |  6 ++++++
 include/gay/systm.h               |  3 ++-
 kernel/panic.c                    |  3 +++
 5 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 arch/x86/sys/amd64/ktrace.c
 create mode 100644 include/gay/ktrace.h

diff --git a/arch/x86/sys/amd64/CMakeLists.txt b/arch/x86/sys/amd64/CMakeLists.txt
index 0ee3c06..9068a0e 100644
--- a/arch/x86/sys/amd64/CMakeLists.txt
+++ b/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
diff --git a/arch/x86/sys/amd64/ktrace.c b/arch/x86/sys/amd64/ktrace.c
new file mode 100644
index 0000000..42e5c13
--- /dev/null
+++ b/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;
+	}
+}
diff --git a/include/gay/ktrace.h b/include/gay/ktrace.h
new file mode 100644
index 0000000..2c4778c
--- /dev/null
+++ b/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);
diff --git a/include/gay/systm.h b/include/gay/systm.h
index d4b91f9..139017f 100644
--- a/include/gay/systm.h
+++ b/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;
 }
diff --git a/kernel/panic.c b/kernel/panic.c
index 18a09ba..3ddc0a3 100644
--- a/kernel/panic.c
+++ b/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 */