IDT: Initialize IDT with a very basic exception handler that does nothing

2 files changed, 63 insertions, 7 deletions

diff --git a/kernel/include/boot/gdt.h b/kernel/include/boot/gdt.h
index ff87981..237628c 100644
--- a/kernel/include/boot/gdt.h
+++ b/kernel/include/boot/gdt.h
@@ -78,13 +78,12 @@
 
 #define GDT_ENTRY(base, limit, access_flags, flags)                           \
   {                                                                           \
-    (limit & 0xffff),          /* limit_low */                                \
-        (base & 0xffff),       /* base_low */                                 \
-        ((base >> 16) & 0xff), /* base_mid */                                 \
-        access_flags,          /* access_flags */                             \
-        FLAGS_LIMIT_HIGH(flags,                                               \
-                         ((limit >> 16) & 0xff)), /* flags_limit_high */      \
-        ((base >> 24) & 0xff)                     /* base_high */             \
+    (limit & 0xffff),                                /* limit_low */          \
+    (base & 0xffff),                                 /* base_low */           \
+    ((base >> 16) & 0xff),                           /* base_mid */           \
+    access_flags,                                    /* access_flags */       \
+    FLAGS_LIMIT_HIGH(flags, ((limit >> 16) & 0xff)), /* flags_limit_high */   \
+    ((base >> 24) & 0xff)                            /* base_high */          \
   }
 
 namespace GDT
@@ -105,6 +104,8 @@ typedef struct {
 } PACKED descriptor_t;
 
 extern "C" void _GDT_flush(descriptor_t *descriptor);
+
+void initialize(void);
 void load(void);
 
 }
diff --git a/kernel/include/boot/idt.h b/kernel/include/boot/idt.h
new file mode 100644
index 0000000..2eda86c
--- /dev/null
+++ b/kernel/include/boot/idt.h
@@ -0,0 +1,55 @@
+/*
+ * bubbl
+ * Copyright (C) 2024-2025  Raghuram Subramani <raghus2247@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __boot_idt_h
+#define __boot_idt_h
+
+#include <common.h>
+#include <stdint.h>
+
+#define IDT_ENTRY(isr, attributes)                                            \
+  {                                                                           \
+    (isr & 0xffff), /* isr_low */                                             \
+    0,              /* segment_selector */                                    \
+    0,              /* reserved */                                            \
+    attributes,     /* attributes */                                          \
+    (isr >> 16)     /* isr_high */                                            \
+  }
+
+namespace IDT
+{
+
+typedef struct {
+  uint16_t isr_low;
+  uint16_t segment_selector;
+  uint8_t reserved;
+  uint8_t attributes;
+  uint16_t isr_high;
+} PACKED entry_t;
+
+typedef struct {
+  uint16_t limit; /* sizeof(IDT) - 1 */
+  entry_t *ptr;   /* Address of IDT */
+} PACKED descriptor_t;
+
+void load(void);
+extern "C" NORETURN void exception_handler(void);
+
+}
+
+#endif