josh/hos
1
0
Fork 0
Code Issues 1 Pull Requests Projects Releases Wiki Activity

Add hulk.gdt module and create our own GDT

Browse Source
This commit is contained in:
Josh Holtrop 2022-09-01 15:43:00 -04:00
parent 16143a727a
commit 66bd51ffb0
2 changed files with 60 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

58
src/hulk/gdt.d Normal file
View File

@ -0,0 +1,58 @@
/**
* GDT (Global Descriptor Table) functionality.
*/
module hulk.gdt;
import ldc.llvmasm;
struct gdt
{
struct gdtr_t
{
ushort limit;
align(2) ulong offset;
}
static assert(gdtr_t.sizeof == 10u);
private enum size_t SELECTOR_NULL = 0x00u;
private enum size_t SELECTOR_KERNEL_CODE = 0x08u;
private enum size_t SELECTOR_KERNEL_DATA = 0x10u;
private enum size_t SELECTOR_COUNT = 3u;
static __gshared ulong[SELECTOR_COUNT] gdt;
static __gshared gdtr_t gdtr;
public static void initialize()
{
gdt[SELECTOR_KERNEL_CODE / ulong.sizeof] = 0x00_A_F_9A_000000_0000u;
gdt[SELECTOR_KERNEL_DATA / ulong.sizeof] = 0x00_C_F_92_000000_0000u;
gdtr.limit = gdt.sizeof - 1u;
gdtr.offset = cast(ulong)&gdt;
lgdt(&gdtr);
load_data_selectors(SELECTOR_KERNEL_DATA);
load_code_selector(SELECTOR_KERNEL_CODE);
}
private static void lgdt(gdtr_t * gdtr)
{
__asm("lgdt $0", "*m", gdtr);
}
private static void load_data_selectors(ulong selector)
{
__asm(`mov %ax, %ds
mov %ax, %es
mov %ax, %fs
mov %ax, %gs
mov %ax, %ss`, "{rax}", selector);
}
private static void load_code_selector(ulong selector)
{
__asm(`push %rax
movabs $$1f, %rax
push %rax
lretq
1:`, "{rax}", selector);
}
}

2
src/hulk/hulk.d
View File

@ -13,6 +13,7 @@ import hulk.klog;
import hulk.hurl;
import hulk.hippo;
import hulk.pci;
import hulk.gdt;
extern extern(C) __gshared ubyte _hulk_total_size;
@ -31,6 +32,7 @@ private __gshared HulkHeader hulk_header = {
*/
void hulk_start()
{
gdt.initialize();
fb.initialize(cast(uint *)HULK_VIRTUAL_FRAMEBUFFER_ADDRESS, hulk_header.bootinfo.fb.width, hulk_header.bootinfo.fb.height, hulk_header.bootinfo.fb.stride);
console.initialize();
console.clear();