Start TSS

Ratakor · Sep 25, 2023 · a9beac5 · a9beac5
1 parent 31db461
commit a9beac5
Showing 1 changed file with 39 additions and 5 deletions.
diff --git a/kernel/gdt.zig b/kernel/gdt.zig
@@ -15,7 +15,7 @@ const GDTEntry = packed struct {
     base_high: u8 = 0,
 };
 
-const TSS = packed struct {
+const TSSDescriptor = packed struct {
     length: u16,
     base_low: u16,
     base_mid: u8,
@@ -26,21 +26,35 @@ const TSS = packed struct {
     reserved: u32,
 };
 
+const TSS = extern struct {
+    reserved0: u32 align(1) = 0,
+    rsp: [3]u64 align(1),
+    reserved1: u64 align(1) = 0,
+    ist: [7]u64 align(1),
+    reserved2: u80 align(1) = 0,
+    reserved3: u16 align(1) = 0,
+    iopb: u16 align(1),
+};
+
 const GDT = extern struct {
     null_entry: GDTEntry align(8),
     kernel_code: GDTEntry align(8),
     kernel_data: GDTEntry align(8),
     user_code: GDTEntry align(8),
     user_data: GDTEntry align(8),
-    // tss: TSS align(8),
+    // tss: TSSDescriptor align(8),
 };
 
 const GDTDescriptor = extern struct {
     limit: u16 align(1),
     base: u64 align(1),
 };
 
-var gdtr: GDTDescriptor = undefined;
+var gdtr: GDTDescriptor = .{
+    .limit = @sizeOf(GDT) - 1,
+    .base = undefined,
+};
+
 var gdt: GDT = .{
     .null_entry = .{},
     .kernel_code = .{
@@ -70,8 +84,13 @@ var gdt: GDT = .{
     // .tss = undefined,
 };
 
+var tss: TSS = .{
+    .rsp = undefined,
+    .ist = undefined,
+    .iopb = undefined,
+};
+
 pub fn init() void {
-    gdtr.limit = @sizeOf(GDT) - 1;
     gdtr.base = @intFromPtr(&gdt);
 
     reloadGDT();
@@ -94,7 +113,22 @@ fn reloadGDT() void {
         \\mov %%ax, %%gs
         \\mov %%ax, %%ss
         :
-        : [gdtr] "r" (&gdtr),
+        : [gdtr] "r" (&gdtr)
         : "rax", "memory"
     );
 }
+
+// pub fn loadTss(tss: *TSS) void {
+//     // TODO: create lock
+//     // TODO: lock defer unlock
+
+//     gdt.tss.base_low = @intFromPtr(tss);
+//     gdt.tss.base_mid = @truncate(@intFromPtr(tss) >> 16);
+//     gdt.tss.flags1 = 0b10001001;
+//     gdt.tss.flags2 = 0;
+//     gdt.tss.base_high = @truncate(@intFromPtr(tss) >> 24);
+//     gdt.tss.base_upper = @truncate(@intFromPtr(tss) >> 32);
+//     gdt.tss.reserved = 0;
+
+//     asm volatile ("ltr %[tss]" : : [tss] "r" (0x28) : "memory");
+// }