1 files changed, 81 insertions, 0 deletions
diff --git a/arch/x86_64/hal/gdt.c b/arch/x86_64/hal/gdt.c
new file mode 100644
index 0000000..a64bdc1
--- /dev/null
+++ b/arch/x86_64/hal/gdt.c
@@ -0,0 +1,81 @@
+#include "gdt.h"
+#include "smp.h"
+#include "lib/string.h"
+
+static struct gdt_entry _gdt[GDT_TSS_HI+1] = 
+{
+    [GDT_KERNEL_NULL] = { 0 },
+    [GDT_KERNEL_CODE] = (struct gdt_entry) {
+        .limit_0_15 = 0xFFFF,
+        .base_0_15 = 0x0,
+        .base_16_23 = 0x0,
+        .type_flg = 0b10011010,
+        .limit_flg = 0b10101111,
+        .base_24_31 = 0x0
+    },
+    [GDT_KERNEL_DATA] = (struct gdt_entry) {
+        .limit_0_15 = 0xFFFF,
+        .base_0_15 = 0x0,
+        .base_16_23 = 0x0,
+        .type_flg = 0b10010010,
+        .limit_flg = 0b10101111,
+        .base_24_31 = 0x0
+    },
+    [GDT_USER_NULL] = { 0 },
+    [GDT_USER_DATA] = (struct gdt_entry) {
+        .limit_0_15 = 0xFFFF,
+        .base_0_15 = 0x0,
+        .base_16_23 = 0x0,
+        .type_flg = 0b11110010,
+        .limit_flg = 0b10101111,
+        .base_24_31 = 0x0
+    },
+    [GDT_USER_CODE] = (struct gdt_entry) {
+        .limit_0_15 = 0xFFFF,
+        .base_0_15 = 0x0,
+        .base_16_23 = 0x0,
+        .type_flg = 0b11111010,
+        .limit_flg = 0b10101111,
+        .base_24_31 = 0x0
+    },
+    [GDT_TSS_LO] = (struct gdt_entry) {
+        .limit_0_15 = 0x0,
+        .base_0_15 = 0x0,
+        .base_16_23 = 0x0,
+        .type_flg = 0x89,
+        .limit_flg = 0x0,
+        .base_24_31 = 0x0       
+    },
+    [GDT_TSS_HI] = { 0 }
+};
+
+void
+gdt_setup(processor_t *processor)
+{
+    memcpy(processor->gdt, _gdt, sizeof(struct gdt_entry) * (GDT_TSS_HI+1));
+
+    struct gdt_descriptor gdtr;
+    gdtr.base = (uintptr_t)&processor->gdt;
+    gdtr.limit = sizeof(struct gdt_entry) * (GDT_TSS_HI+1) - 1;
+
+    extern void load_gdt(struct gdt_descriptor *gdtr);
+    load_gdt(&gdtr);
+
+    uintptr_t tss_base = (uintptr_t)&processor->tss;
+    size_t tss_limit = sizeof(struct tss);
+
+    struct gdt_entry *tss_lo = &processor->gdt[GDT_TSS_LO];
+    struct gdt_entry *tss_hi = &processor->gdt[GDT_TSS_HI];
+
+    tss_lo->base_0_15 = (uint16_t)(tss_base & 0xFFFF);
+    tss_lo->base_16_23 = (uint8_t)((tss_base >> 16) & 0xFF);
+    tss_lo->base_24_31 = (uint8_t)((tss_base >> 24) & 0xFF);
+    tss_hi->limit_0_15 = (uint16_t)((tss_base >> 32) & 0xFFFF);
+    tss_hi->base_0_15 = (uint16_t)((tss_base >> 48) & 0xFFFF);
+
+    tss_lo->limit_0_15 = (uint16_t)(tss_limit & 0xFFFF);
+    tss_lo->limit_flg |= (uint8_t)((tss_limit >> 16) & 0xF);
+
+    extern void load_tss(void);
+    load_tss();
+}