stos/amd64: cpu: Add exception handling groundwork

Signed-off-by: Chloe M. <chloe@mensia.org>

paw/stos/head/arch/amd64/idt.h

@@ -13,4 +13,21 @@
 #define IDT_TRAP_GATE   0x8F
 #define IDT_USER_GATE   0xEE
 
+#ifndef __ASSEMBLER__
+/*
+ * Set an IDT entry
+ *
+ * @Vector:  Interrupt vector to set
+ * @IsrBase: ISR base to set
+ * @Type:    Gate type
+ * @Ist:     Interrupt stack table index
+ */
+VOID MdIdtSetEntry(UCHAR Vector, UPTR IsrBase, UCHAR Type, UCHAR Ist);
+
+/*
+ * Load the IDT
+ */
+VOID MdIdtLoad(VOID);
+
+#endif  /* !__ASSEMBLER__ */
 #endif  /* !_MACHINE_IDT_H_ */

paw/stos/head/arch/amd64/trap.h

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: Trap handling
+ * Author:      Chloe M.
+ */
+
+#ifndef _MACHINE_TRAP_H_
+#define _MACHINE_TRAP_H_ 1
+
+#include <stdef.h>
+#include <machine/frame.h>
+
+#define TRAP_DIVERR     0x00        /* Divide error */
+#define TRAP_DBG        0x01        /* Debug exception */
+#define TRAP_NMI        0x02        /* Non-maskable interrupt */
+#define TRAP_BP         0x03        /* Breakpoint */
+#define TRAP_OF         0x04        /* Overflow */
+#define TRAP_BR         0x05        /* BOUND range exceeded */
+#define TRAP_UD         0x06        /* Undefined opcode */
+#define TRAP_NM         0x07        /* No math coprocessor */
+#define TRAP_DF         0x08        /* Double fault */
+#define TRAP_CPR        0x09        /* Reserved */
+#define TRAP_TS         0x0A        /* Invalid TSS */
+#define TRAP_NP         0x0B        /* Segment not present */
+#define TRAP_SS         0x0C        /* Stack segment fault */
+#define TRAP_GP         0x0D        /* General protection fault */
+#define TRAP_PF         0x0E        /* Page fault */
+
+/*
+ * Used for dispatching traps
+ *
+ * @Frame: Trap-frame associated with trap
+ */
+VOID MdTrapDispatch(TRAP_FRAME *Frame);
+
+#endif  /* !_MACHINE_TRAP_H_ */

paw/stos/head/ke/knot.h

@@ -18,12 +18,14 @@
  * @KNOT_UNBOUND_RSRC:      Unbounded resource
  * @KNOT_BAD_BOOT_PROTO:    Bad boot protocol
  * @KNOT_OOM:               Fatal out of memory
+ * @KNOT_EXCEPTION:         Fatal exception
  */
 typedef enum {
     KNOT_MISC,
     KNOT_UNBOUND_RSRC,
     KNOT_BAD_BOOT_PROTO,
-    KNOT_OOM
+    KNOT_OOM,
+    KNOT_EXCEPTION
 } KNOT_REASON;
 
 /*