merge branch memory-shit into higher-half

src/kernel/gdt.c

@@ -2,6 +2,8 @@
 #include "../include/string.h"
 #include "../include/paging.h"
 
+struct tss_entry_struct tss;
+
 void bss_init()
 {
 	memset((void *)((int)_edata), 0, KERNEL_BSS_SIZE);
@@ -29,6 +31,16 @@ void load_gdt(uint32_t gdt_ptr) {
     );
 }
 
+void flush_tss(void) {
+    asm volatile (
+        "mov %0, %%ax\n\t"
+        "ltr %%ax\n\t"
+        :
+        : "i" (0x28)
+        : "ax"
+    );
+}
+
 static void gdt_set_entry(int num, uint32_t base_addr, uint32_t limit, char loflags, char hiflags)
 {
 	num /= sizeof(struct seg_desc);
@@ -44,6 +56,17 @@ void gdt_init(void)
 {
 	uint8_t loflags;
 
+	memset(&tss, 0, sizeof(tss));
+    tss.ss0 = KERNEL_DS;
+	tss.iomap_base = 0xFFFF; // Disable I/O bitmap
+	tss.esp0 = 0xC0010000; /* kernel stack address (firstly defined in boot.asm)*/
+	tss.cs = KERNEL_CS;
+	tss.ds = KERNEL_DS;
+	tss.es = KERNEL_DS;
+	tss.fs = KERNEL_DS;
+	tss.gs = KERNEL_DS;
+	tss.ss = KERNEL_DS;
+
 	gdt_set_entry(0, 0, 0, 0, 0);	/* null descriptor */
 
 	loflags = SD_CODE | SD_CD | SD_DPL0 | SD_PRESENT;
@@ -56,8 +79,9 @@ void gdt_init(void)
 	loflags = SD_DATA | SD_CD | SD_DPL3 | SD_PRESENT;
 	gdt_set_entry(USER_DS, 0, 0xFFFFFFFF, loflags, SD_OPSIZE32 | SD_PAGE4KB);
 
-	loflags = SD_TSSPRESENT;
-	gdt_set_entry(TSS, 0, sizeof(struct tss_entry_struct), loflags, SD_OPSIZE32);
+	loflags = 0x89; // P=1, DPL=0, S=0 (system), Type=0x9 (32-bit TSS)
+    gdt_set_entry(TSS, (uint32_t)&tss, sizeof(struct tss_entry_struct) - 1, SD_PRESENT | SD_DPL0 | SD_TSSPRESENT, 0);
 
 	load_gdt((uint32_t)&gdtr);
+	flush_tss();
 }