GDT finally works

kernel/bootinfo/bootinfo.h

@@ -0,0 +1,33 @@
+#ifndef BOOTINFO_BOOTINFO_H_
+#define BOOTINFO_BOOTINFO_H_
+
+#include <stdint.h>
+#include <stddef.h>
+#include <limine.h>
+
+extern uint64_t kernel_text_start, kernel_text_end,
+       kernel_rodata_start, kernel_rodata_end,
+       kernel_data_start, kernel_data_end,
+       kernel_start, kernel_end;
+
+typedef struct {
+  // Higher Half Direct Map: https://github.com/dreamportdev/Osdev-Notes/blob/master/01_Build_Process/02_Boot_Protocols.md#limine-protocol
+  size_t hhdm_off;
+  size_t kern_virtbase;
+  size_t kern_physbase;
+  size_t rsdp;
+  size_t memmap_total;
+  uint64_t memmap_entrycount;
+  LIMINE_PTR(struct limine_memmap_entry **) memmap_entries;
+  LIMINE_PTR(struct limine_smp_response *) smp;
+  uint64_t smp_bspindex;
+} BootInfo;
+
+extern BootInfo BOOT_INFO;
+
+#define IS_IN_HHDM(a) ((size_t)a >= BOOT_INFO.hhdm_off \
+    && (size_t)a <= BOOT_INFO.hhdm_off + BOOT_INFO.memmap_total)
+
+void bootinfo_init(void);
+
+#endif // BOOTINFO_BOOTINFO_H_