3 files changed, 89 insertions, 0 deletions
diff --git a/mos/sys/inc/arch/x86_64/gdt.h b/mos/sys/inc/arch/x86_64/gdt.h
new file mode 100644
index 0000000..35081b3
--- /dev/null
+++ b/mos/sys/inc/arch/x86_64/gdt.h
@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2025, Ian Moffett.
+ * Provided under the BSD-3 clause.
+ */
+
+#ifndef _MACHINE_GDT_H_
+#define _MACHINE_GDT_H_ 1
+
+#ifndef __ASSEMBLER__
+#include <sdk/types.h>
+#include <sdk/defs.h>
+#endif  /* __ASSEMBLER__ */
+
+/* Kernel code/data */
+#define GDT_KCODE  0x08
+#define GDT_KDATA  0x10
+
+/* User code/data */
+#define GDT_UCODE  0x18
+#define GDT_UDATA  0x20
+
+/* Task state segment */
+#define GDT_TSS    0x28
+#define GDT_TSS_INDEX 0x05
+
+#ifndef __ASSEMBLER__
+typedef struct {
+    USHORT limit;
+    USHORT base_low;
+    UBYTE base_mid;
+    UBYTE access;
+    UBYTE granularity;
+    UBYTE base_hi;
+} PACKED GDT_ENTRY;
+
+typedef struct {
+    USHORT limit;
+    UPTR offset;
+} PACKED GDTR;
+
+#endif  /* !__ASSEMBLER__ */
+#endif  /* !_MACHINE_GDT_H_ */
diff --git a/mos/sys/inc/kern/panic.h b/mos/sys/inc/kern/panic.h
new file mode 100644
index 0000000..a7aac0e
--- /dev/null
+++ b/mos/sys/inc/kern/panic.h
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2025, Ian Moffett.
+ * Provided under the BSD-3 clause.
+ */
+
+#ifndef _KERN_PANIC_H_
+#define _KERN_PANIC_H_ 1
+
+#include <sdk/types.h>
+#include <sdk/stdarg.h>
+
+/*
+ * Signal to the operator that a severe error has
+ * occurred and the system has been halted.
+ */
+void panic(const char *fmt, ...);
+
+#endif  /* !_KERN_PANIC_H_ */
diff --git a/mos/sys/kern/kern_panic.c b/mos/sys/kern/kern_panic.c
new file mode 100644
index 0000000..8f03e6a
--- /dev/null
+++ b/mos/sys/kern/kern_panic.c
@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2025, Ian Moffett.
+ * Provided under the BSD-3 clause.
+ */
+
+#include <sdk/string.h>
+#include <kern/panic.h>
+#include <kern/spinlock.h>
+#include <kern/trace.h>
+#include <mu/cpu.h>
+
+static SPINLOCK panic_sync;
+static char panic_buf[256];
+static va_list ap;
+
+void
+panic(const char *fmt, ...)
+{
+    spinlock_acquire(&panic_sync, SPINLOCK_IRQMUT);
+    va_start(ap, fmt);
+
+    vsnprintf(panic_buf, sizeof(panic_buf), fmt, ap);
+    trace("panic: ");
+    trace(panic_buf);
+
+    for (;;) {
+        mu_cpu_halt();
+    }
+}