work on tss descriptor

kernel/arch/gdt.cc

@@ -1,6 +1,7 @@
 #include "gdt.h"
 
 #include "core.h"
+#include "tss.h"
 
 namespace GDT {
 
@@ -30,6 +31,11 @@ alignas(16) constinit SegmentDescriptor long_mode[] = {
 	// Global data segment
 	SegmentDescriptor::Segment64(false, 0),
 
+	SegmentDescriptor::Segment64(true , 3),
+	SegmentDescriptor::Segment64(false, 3),
+
+	//SegmentDescriptor::TSSLow(),
+	//SegmentDescriptor::TSSHigh(),
 };
 extern "C" constexpr Pointer gdt_long_mode_pointer(long_mode);
 

kernel/arch/gdt.h

@@ -5,6 +5,7 @@
 
 #pragma once
 #include "../types.h"
+#include "./tss.h"
 
 /*! \brief Abstracts the GDT that, primarily, contains descriptors to memory
  * segments.
@@ -142,6 +143,28 @@ union SegmentDescriptor {
 		return SegmentDescriptor::Segment(0, 0, code, ring, Size::Bit64);
 	}
 
+    static SegmentDescriptor TSSLow (const TSS::Entry &tss){
+        return SegmentDescriptor{
+            .limit_low = sizeof(tss) & 0xFFFF,
+            .base_low=(uint64_t)(&tss) & 0xFFFFFF,
+            .type=0b1001, // dont set busy flag, is this even needed?
+			.descriptor_type = DescriptorType::System, // TSS descriptor needs this set to 0
+			.privilege_level = 0, // ring 0
+			.present = true,
+            .limit_high = 0,   // should not be greater than 2^16 - 1 anyways
+			.available = false,
+            .custom=0,
+            .granularity = Granularity::Bytes,
+            .base_high = ((uint64_t)(&tss) >> 24)&0xFF,
+        };
+    }
+
+    static SegmentDescriptor TSSHigh (const TSS::Entry &tss){
+        return SegmentDescriptor{
+            .value = ((uint64_t)(&tss) >> 32) & 0xFFFFFFFF,
+        };;
+    }
+
 } __attribute__((packed));
 
 static_assert(sizeof(SegmentDescriptor) == 8,