2 files changed, 78 insertions, 9 deletions
diff --git a/src/utils/gdt.c b/src/utils/gdt.c
index e82ebe4..fd86f5f 100644
--- a/src/utils/gdt.c
+++ b/src/utils/gdt.c
@@ -2,11 +2,14 @@
 #include "mem.h"
 
 struct GDT_REGISTER GDTR = { 0, 0 };
+GDT_TSS TSS;
 
 void gdt_memcpy(){
-  GDTR.limit=8*4; // Each entry is 8 bytes and 4 entries
+  GDTR.limit=8*8; // Each entry is 8 bytes and 8 entries
   GDTR.base=0x800;
-  
+  gdt_write_entry((GDT_ENTRY){0,0,0,0},0); // First one must be null
+
+  // ----- Kernel Segments
   GDT_ENTRY cs_desc;
   cs_desc.base=0;
   cs_desc.limit=0xFFFFF;
@@ -26,13 +29,50 @@ void gdt_memcpy(){
   ss_desc.access=GDT_PR|GDT_PRVL_0|GDT_S|GDT_RW|GDT_DC;
   
   // Write GDT descriptors into memory
-  gdt_write_entry((GDT_ENTRY){0,0,0,0},GDTR.base); // First one must be null
-  gdt_write_entry(cs_desc, GDTR.base+8); // Each entry is 64 bits (8 bytes)
-  gdt_write_entry(ds_desc, GDTR.base+8*2);
-  gdt_write_entry(ss_desc, GDTR.base+8*3);
+  gdt_write_entry(cs_desc, 1);
+  gdt_write_entry(ds_desc, 2);
+  gdt_write_entry(ss_desc, 3);
+
+  // ----- User Segments
+  GDT_ENTRY ucs_desc;
+  ucs_desc.base=0x300000;
+  ucs_desc.limit=0xFFFFF;
+  ucs_desc.flags=GDT_SZ|GDT_GR;
+  ucs_desc.access=GDT_PR|GDT_PRVL_3|GDT_S|GDT_EXEC|GDT_RW|GDT_DC;
+  
+  GDT_ENTRY uds_desc;
+  uds_desc.base=0x300000;
+  uds_desc.limit=0xFFFFF;
+  uds_desc.flags=GDT_SZ|GDT_GR;
+  uds_desc.access=GDT_PR|GDT_PRVL_3|GDT_S|GDT_RW;
+  
+  GDT_ENTRY uss_desc;
+  uss_desc.base=0; // Not used in stack descriptor
+  uss_desc.limit=0x64;  // Define how much entry it can contains
+  uss_desc.flags=GDT_SZ|GDT_GR;
+  uss_desc.access=GDT_PR|GDT_PRVL_3|GDT_S|GDT_RW|GDT_DC;
+  
+  // Write GDT descriptors into memory
+  gdt_write_entry(ucs_desc, 4); // Each entry is 64 bits (8 bytes)
+  gdt_write_entry(uds_desc, 5);
+  gdt_write_entry(uss_desc, 6);
+
+  // Init TSS segment
+  TSS.t_reserved=0;
+  TSS.io_map=0;
+  TSS.ss0=0x18;
+  TSS.esp0=0x50000;
+
+  GDT_ENTRY tss_desc;
+  tss_desc.base=(u32)&TSS; // Not used in stack descriptor
+  tss_desc.limit=0x68;  // Define how much entry it can contains
+  tss_desc.flags=0;
+  tss_desc.access=0x89 | GDT_PRVL_3; // Note that 0x89 is specific to TSS!
+  gdt_write_entry(tss_desc, 7);
+
 }
 
-void gdt_write_entry(GDT_ENTRY entry, u32 addr){
+void gdt_write_entry(GDT_ENTRY entry, u32 id){
   int descriptor[2];
 
   // First row of the descriptor
@@ -47,5 +87,5 @@ void gdt_write_entry(GDT_ENTRY entry, u32 addr){
   descriptor[1]=base|access<<8|limit<<16|flags<<20|base2<<24;
 
   // Copy descriptor into memory
-  memcpy(descriptor,(void*)addr,8);
+  memcpy(descriptor,(void*)GDTR.base+8*id,8); // Each entry is 64 bits (8 bytes)
 }
diff --git a/src/utils/gdt.h b/src/utils/gdt.h
index 85a75aa..01a01bf 100644
--- a/src/utils/gdt.h
+++ b/src/utils/gdt.h
@@ -31,6 +31,35 @@ struct GDT_REGISTER {
   u32 base;
 } __attribute__((packed));
 
+typedef struct GDT_TSS {
+  u16 previous_task,previous_task_unused;
+  u32 esp0;
+  u16 ss0, ss0_unused;
+  u32 esp1;
+  u16 ss1, ss1_unused;
+  u32 esp2;
+  u16 ss2, ss2_unused;
+  u32 cr3;
+  u32 eip;
+  u32 eflags;
+  u32 eax;
+  u32 ecx;
+  u32 edx;
+  u32 ebx;
+  u32 esp;
+  u32 ebp;
+  u32 esi;
+  u32 edi;
+  u16 es, es_reserved;
+  u16 cs, cs_reserved;
+  u16 ss, ss_reserved;
+  u16 ds, ds_reserved;
+  u16 fs, fs_reserved;
+  u16 gs, gs_reserved;
+  u16 ldtss, ldtss_reserved;
+  u16 t_reserved, io_map;
+} __attribute__((packed)) GDT_TSS;
+
 /**
  * Copy GDT in memory
  */
@@ -39,6 +68,6 @@ void gdt_memcpy();
 /**
  * Write a GDT entry at address addr
  */
-void gdt_write_entry(GDT_ENTRY entry, u32 addr);
+void gdt_write_entry(GDT_ENTRY entry, u32 id);
 
 #endif