GDT finally works

kernel/bootinfo/bootinfo.c

@@ -0,0 +1,82 @@
+#include <stdint.h>
+#include <stddef.h>
+#include <limine.h>
+#include "bootinfo.h"
+#include "hal/hal.h"
+
+BootInfo BOOT_INFO;
+
+static volatile struct limine_paging_mode_request PAGING_REQ = {
+  .id = LIMINE_PAGING_MODE_REQUEST,
+  .revision = 0,
+#if defined(__x86_64__)
+  .mode = LIMINE_PAGING_MODE_X86_64_4LVL,
+#else
+# error "Paging mode is unknown for this architecture"
+#endif
+};
+
+static volatile struct limine_kernel_address_request KERN_ADDR_REQ = {
+  .id = LIMINE_KERNEL_ADDRESS_REQUEST, .revision = 0,
+};
+
+static volatile struct limine_hhdm_request HHDM_REQ = {
+  .id = LIMINE_HHDM_REQUEST, .revision = 0,
+};
+
+static volatile struct limine_memmap_request MEMMAP_REQ = {
+  .id = LIMINE_MEMMAP_REQUEST, .revision = 0,
+};
+
+static volatile struct limine_smp_request SMP_REQ = {
+  .id = LIMINE_SMP_REQUEST, .revision = 0,
+};
+
+static volatile struct limine_rsdp_request RSDP_REQ = {
+  .id = LIMINE_RSDP_REQUEST, .revision = 0,
+};
+
+void bootinfo_init(void) {
+  struct limine_paging_mode_response *pagingres = PAGING_REQ.response;
+#if defined(__x86_64__)
+  if (pagingres->mode != LIMINE_PAGING_MODE_X86_64_4LVL) {
+#endif
+    hal_hang();
+  }
+
+  struct limine_hhdm_response *hhdmres = HHDM_REQ.response;
+  BOOT_INFO.hhdm_off = hhdmres->offset;
+
+  struct limine_kernel_address_response *kernaddrres = KERN_ADDR_REQ.response;
+  BOOT_INFO.kern_virtbase = kernaddrres->virtual_base;
+  BOOT_INFO.kern_physbase = kernaddrres->physical_base;
+
+  struct limine_memmap_response *memmapres = MEMMAP_REQ.response;
+  BOOT_INFO.memmap_entries = memmapres->entries;
+  BOOT_INFO.memmap_entrycount = memmapres->entry_count;
+
+  BOOT_INFO.memmap_total = 0;
+  for (size_t i = 0; i < memmapres->entry_count; i++) {
+    struct limine_memmap_entry *entry = memmapres->entries[i];
+    if (entry->type != LIMINE_MEMMAP_RESERVED) {
+      BOOT_INFO.memmap_total += entry->length;
+    }
+  }
+
+  struct limine_smp_response *smpres = SMP_REQ.response;
+  BOOT_INFO.smp = smpres;
+
+  BOOT_INFO.smp_bspindex = (uint64_t)(-1);
+  for (size_t i = 0; i < smpres->cpu_count; i++) {
+    struct limine_smp_info *entry = smpres->cpus[i];
+    if (entry->lapic_id == smpres->bsp_lapic_id) {
+      BOOT_INFO.smp_bspindex = i;
+    }
+  }
+  if (BOOT_INFO.smp_bspindex == (uint64_t)-1) {
+    hal_hang();
+  }
+
+  struct limine_rsdp_response *rsdpres = RSDP_REQ.response;
+  BOOT_INFO.rsdp = (size_t)rsdpres->address - BOOT_INFO.hhdm_off;
+}

kernel/bootinfo/bootinfo.h

@@ -0,0 +1,33 @@
+#ifndef BOOTINFO_BOOTINFO_H_
+#define BOOTINFO_BOOTINFO_H_
+
+#include <stdint.h>
+#include <stddef.h>
+#include <limine.h>
+
+extern uint64_t kernel_text_start, kernel_text_end,
+       kernel_rodata_start, kernel_rodata_end,
+       kernel_data_start, kernel_data_end,
+       kernel_start, kernel_end;
+
+typedef struct {
+  // Higher Half Direct Map: https://github.com/dreamportdev/Osdev-Notes/blob/master/01_Build_Process/02_Boot_Protocols.md#limine-protocol
+  size_t hhdm_off;
+  size_t kern_virtbase;
+  size_t kern_physbase;
+  size_t rsdp;
+  size_t memmap_total;
+  uint64_t memmap_entrycount;
+  LIMINE_PTR(struct limine_memmap_entry **) memmap_entries;
+  LIMINE_PTR(struct limine_smp_response *) smp;
+  uint64_t smp_bspindex;
+} BootInfo;
+
+extern BootInfo BOOT_INFO;
+
+#define IS_IN_HHDM(a) ((size_t)a >= BOOT_INFO.hhdm_off \
+    && (size_t)a <= BOOT_INFO.hhdm_off + BOOT_INFO.memmap_total)
+
+void bootinfo_init(void);
+
+#endif // BOOTINFO_BOOTINFO_H_