Initial commit: SUB-OS 64-Bit Production Monolithic Operating System with LazyBox userland suite

include/arch/x86_64/gdt.h

@@ -0,0 +1,47 @@
+#ifndef _ARCH_X86_64_GDT_H
+#define _ARCH_X86_64_GDT_H
+
+#include <stdint.h>
+
+#define GDT_KERNEL_CODE 0x08
+#define GDT_KERNEL_DATA 0x10
+#define GDT_USER_CODE   0x18
+#define GDT_USER_DATA   0x20
+#define GDT_TSS         0x28
+
+typedef struct {
+    uint16_t limit_low;
+    uint16_t base_low;
+    uint8_t  base_middle;
+    uint8_t  access;
+    uint8_t  granularity;
+    uint8_t  base_high;
+} __attribute__((packed)) gdt_entry_t;
+
+typedef struct {
+    uint16_t limit;
+    uint64_t base;
+} __attribute__((packed)) gdt_ptr_t;
+
+typedef struct {
+    uint32_t reserved0;
+    uint64_t rsp0;
+    uint64_t rsp1;
+    uint64_t rsp2;
+    uint64_t reserved1;
+    uint64_t ist1;
+    uint64_t ist2;
+    uint64_t ist3;
+    uint64_t ist4;
+    uint64_t ist5;
+    uint64_t ist6;
+    uint64_t ist7;
+    uint64_t reserved2;
+    uint16_t reserved3;
+    uint16_t iomap_base;
+} __attribute__((packed)) tss_entry_t;
+
+void gdt_init(void);
+void gdt_set_kernel_stack(uint64_t stack);
+
+#endif // _ARCH_X86_64_GDT_H