From 114cc434d2d2e3105385d57f591ba727353b1a3b Mon Sep 17 00:00:00 2001
From: "Chloe M." <chloe@mensia.org>
Date: Tue, 23 Jun 2026 22:01:52 +0000
Subject: [PATCH] stos/amd64: intr: Add IRQL management

Signed-off-by: Chloe M. <chloe@mensia.org>
---
 paw/stos/arch/amd64/cpu/intr.c | 57 ++++++++++++++++++++++++++++++++++
 paw/stos/head/hal/intr.h       | 23 ++++++++++++++
 paw/stos/head/ke/knot.h        |  6 +++-
 paw/stos/ke/knot.c             |  4 ++-
 4 files changed, 88 insertions(+), 2 deletions(-)

diff --git a/paw/stos/arch/amd64/cpu/intr.c b/paw/stos/arch/amd64/cpu/intr.c
index 7028e77..4f599f6 100644
--- a/paw/stos/arch/amd64/cpu/intr.c
+++ b/paw/stos/arch/amd64/cpu/intr.c
@@ -8,6 +8,7 @@
 
 #include <hal/intr.h>
 #include <machine/idt.h>
+#include <ke/knot.h>
 #include <stdef.h>
 
 /* Interrupt priority level shift */
@@ -16,6 +17,20 @@
 /* Globals */
 static INTR_HANDLER Handlers[256];
 
+/*
+ * Set a new IRQL
+ */
+static inline VOID
+SetIrql(IRQL Irql)
+{
+    ASMV(
+        "mov %0, %%cr8"
+        :
+        : "r" ((UQUAD)Irql)
+        : "memory"
+    );
+}
+
 ST_STATUS
 HalRegisterIntr(const INTR_HANDLER *Handler, BOOLEAN IsUser)
 {
@@ -74,3 +89,45 @@ HalRegisterIntr(const INTR_HANDLER *Handler, BOOLEAN IsUser)
     /* No entry found */
     return STATUS_NOT_FOUND;
 }
+
+IRQL
+HalGetIrql(VOID)
+{
+    UQUAD CurrentIrql;
+
+    ASMV(
+        "mov %%cr8, %0"
+        : "=r" (CurrentIrql)
+        :
+        : "memory"
+    );
+
+    return (IRQL)CurrentIrql;
+}
+
+IRQL
+HalRaiseIrql(IRQL Irql)
+{
+    IRQL CurrentIrql;
+
+    CurrentIrql = HalGetIrql();
+    if (Irql < CurrentIrql) {
+        KeKnot(IRQL_NOT_GTE, "got bad irql\n");
+    }
+
+    SetIrql(Irql);
+    return CurrentIrql;
+}
+
+IRQL
+HalLowerIrql(IRQL Irql)
+{
+    IRQL CurrentIrql;
+
+    CurrentIrql = HalGetIrql();
+    if (Irql > CurrentIrql) {
+        KeKnot(IRQL_NOT_LTE, "got bad irql\n");
+    }
+
+    return CurrentIrql;
+}
diff --git a/paw/stos/head/hal/intr.h b/paw/stos/head/hal/intr.h
index 1818a31..d000020 100644
--- a/paw/stos/head/hal/intr.h
+++ b/paw/stos/head/hal/intr.h
@@ -69,4 +69,27 @@ typedef struct {
  */
 ST_STATUS HalRegisterIntr(const INTR_HANDLER *Handler, BOOLEAN IsUser);
 
+/*
+ * Returns the current IRQL
+ */
+IRQL HalGetIrql(VOID);
+
+/*
+ * Raise the IRQL level to a higher level
+ *
+ * @Irql: IRQL to raise to
+ *
+ * Returns the previous IRQL
+ */
+IRQL HalRaiseIrql(IRQL Irql);
+
+/*
+ * Lower the IRQL level to a lower level
+ *
+ * @Irql: IRQL to lower to
+ *
+ * Returns the previous IRQL
+ */
+IRQL HalLowerIrql(IRQL Irql);
+
 #endif  /* !_HAL_INTR_H_ */
diff --git a/paw/stos/head/ke/knot.h b/paw/stos/head/ke/knot.h
index 3d47316..91502d3 100644
--- a/paw/stos/head/ke/knot.h
+++ b/paw/stos/head/ke/knot.h
@@ -19,13 +19,17 @@
  * @KNOT_BAD_BOOT_PROTO:    Bad boot protocol
  * @KNOT_OOM:               Fatal out of memory
  * @KNOT_EXCEPTION:         Fatal exception
+ * @IRQL_NOT_LTE:           IRQL not less than or equal
+ * @IRQL_NOT_GTE:           IRQL not greater than or equal
  */
 typedef enum {
     KNOT_MISC,
     KNOT_UNBOUND_RSRC,
     KNOT_BAD_BOOT_PROTO,
     KNOT_OOM,
-    KNOT_EXCEPTION
+    KNOT_EXCEPTION,
+    IRQL_NOT_LTE,
+    IRQL_NOT_GTE
 } KNOT_REASON;
 
 /*
diff --git a/paw/stos/ke/knot.c b/paw/stos/ke/knot.c
index ca5513f..ea5831d 100644
--- a/paw/stos/ke/knot.c
+++ b/paw/stos/ke/knot.c
@@ -22,7 +22,9 @@ static const CHAR *ReasonTable[] = {
     [KNOT_UNBOUND_RSRC] = "unbounded resource",
     [KNOT_BAD_BOOT_PROTO] = "bad boot protocol",
     [KNOT_OOM] = "out of memory",
-    [KNOT_EXCEPTION] = "fatal exception"
+    [KNOT_EXCEPTION] = "fatal exception",
+    [IRQL_NOT_LTE] = "irql not less than or equal",
+    [IRQL_NOT_GTE] = "irql not greater than or equal"
 };
 
 /* Globals */