GDT finally works

kernel/hal/hal.h

@@ -0,0 +1,19 @@
+#ifndef KERNEL_HAL_HAL_H_
+#define KERNEL_HAL_HAL_H_
+
+#include <stdint.h>
+
+#include "util.h"
+
+__attribute__((noreturn)) void hal_hang(void);
+
+void hal_init(void);
+void hal_intr_disable(void);
+void hal_intr_enable(void);
+void hal_memset(void *mem, uint8_t v, uint32_t size);
+
+#if defined(__x86_64__)
+# define HAL_PAGE_SIZE 0x1000
+#endif
+
+#endif // KERNEL_HAL_HAL_H_

kernel/hal/util.c

@@ -0,0 +1,9 @@
+#include <stdint.h>
+#include "hal.h"
+
+void hal_memset(void *mem, uint8_t v, uint32_t size) {
+  uint8_t *mem1 = mem;
+  for (uint32_t i = 0; i < size; i++) {
+    mem1[i] = v;
+  }
+}

kernel/hal/util.h

@@ -0,0 +1,6 @@
+#ifndef HAL_UTIL_H_
+#define HAL_UTIL_H_
+
+#define HAL_MEMSET(m, v, n) hal_memset((void *)(m), (v), (n))
+
+#endif // HAL_UTIL_H_

kernel/hal/x86_64/gdt.c

@@ -0,0 +1,94 @@
+#include <stdint.h>
+#include <stddef.h>
+#include "compiler/attr.h"
+#include "hal/hal.h"
+
+#define GDT_SIZE 5
+
+typedef struct {
+  uint16_t limitlow;
+  uint16_t baselow;
+  uint8_t basemid;
+  uint8_t access;
+  uint8_t gran;
+  uint8_t basehigh;
+} PACKED GdtEntry;
+
+typedef struct {
+  uint16_t limit;
+  uint64_t base;
+} PACKED GdtPtr;
+
+typedef struct {
+  GdtEntry old[5];
+  GdtEntry tsslow;
+  GdtEntry tsshigh;
+} PACKED ExtendedGdt;
+
+typedef struct {
+  uint32_t resv0;
+  uint64_t rsp0;
+  uint64_t rsp1;
+  uint64_t rsp2;
+  uint64_t resv1;
+  uint64_t ist[7];
+  uint64_t resv2;
+  uint16_t resv3;
+  uint16_t iopb_off;
+} PACKED Tss;
+
+static Tss tss = {0};
+static ExtendedGdt *curgdt = NULL;
+
+#define KCODE 0x08
+#define KDATA 0x10
+#define UCODE 0x18
+#define UDATA 0x20
+#define TSS   0x28
+
+#define GDT_PRESENT 0x80
+#define GDT_TSS     0x89
+
+static uint64_t gdt_curretbase(void) {
+  GdtPtr gdtr;
+  asm volatile("sgdt %0" : "=m"(gdtr));
+  return gdtr.base;
+}
+
+void gdt_setenty(GdtEntry *entry, uint32_t base, uint32_t limit, uint8_t access, uint8_t gran) {
+  entry->baselow = base & 0xffff;
+  entry->basemid = (base >> 16) & 0xff;
+  entry->basehigh = (base >> 24) & 0xff;
+  entry->limitlow = limit & 0xffff;
+  entry->gran = (limit >> 16) & 0x0f | (gran & 0xf0);
+  entry->access = access;
+}
+
+void gdt_init(void) {
+  uint64_t base = gdt_curretbase();
+  curgdt = (ExtendedGdt *)base;
+
+  HAL_MEMSET(&tss, 0, sizeof(tss));
+  tss.iopb_off = sizeof(tss);
+
+  uint64_t tss_base = (uint64_t)&tss;
+  uint32_t tss_limit = sizeof(tss) - 1;
+
+  gdt_setenty(&curgdt->tsslow, tss_base & 0xFFFFFFFF, tss_limit, GDT_PRESENT | GDT_TSS, 0x0);
+  
+  GdtEntry *tsshigh = &curgdt->tsshigh;
+  tsshigh->baselow = (tss_base >> 32) & 0xffff;
+  tsshigh->basemid = (tss_base >> 48) & 0xff;
+  tsshigh->basehigh = (tss_base >> 56) & 0xff;
+  tsshigh->access = 0;
+  tsshigh->gran = 0;
+  tsshigh->limitlow = 0;
+
+  GdtPtr gdtr;
+  asm volatile("sgdt %0" : "=m"(gdtr));
+  gdtr.limit = sizeof(ExtendedGdt) - 1;
+  asm volatile("lgdt %0" :: "m"(gdtr));
+
+  asm volatile("ltr %0" :: "r"((uint16_t)0x28));
+}
+

kernel/hal/x86_64/gdt.h

@@ -0,0 +1,6 @@
+#ifndef HAL_GDT_H_
+#define HAL_GDT_H_
+
+void gdt_init(void);
+
+#endif // HAL_GDT_H_

kernel/hal/x86_64/hal.c

@@ -0,0 +1,21 @@
+#include <stdint.h>
+#include <stdbool.h>
+#include "hal/hal.h"
+#include "kprintf.h"
+#include "serial.h"
+#include "gdt.h"
+
+void hal_init(void) {
+  if (!serial_init()) {
+    hal_hang(); // going further makes no sense
+  }
+  LOG("hal", "serial init\n");
+  gdt_init();
+}
+
+__attribute__((noreturn)) void hal_hang(void) {
+  for(;;) {
+    asm("hlt");
+  }
+}
+

kernel/hal/x86_64/intr.S

@@ -0,0 +1,9 @@
+.global hal_intr_enable
+hal_intr_enable:
+  sti
+  ret
+
+.global hal_intr_disable
+hal_intr_disable:
+  cli
+  ret

kernel/hal/x86_64/serial.c

@@ -0,0 +1,50 @@
+#include <stdint.h>
+#include <stdbool.h>
+
+#define SERIAL_PORT 0x3f8
+
+extern uint8_t serial_inb(uint16_t port);
+extern void serial_outb(uint16_t port, uint8_t value);
+
+static int serial_received(void) {
+  return serial_inb(SERIAL_PORT + 5) & 1;
+}
+
+static uint8_t serial_read(void) {
+  while (serial_received() == 0);
+  return serial_inb(SERIAL_PORT);
+}
+
+static int serial_trans_empty(void) {
+  return serial_inb(SERIAL_PORT + 5) & 0x20;
+}
+
+static void serial_write(uint8_t value) {
+  while (!serial_trans_empty());
+  serial_outb(SERIAL_PORT, value);
+}
+
+// REFERENCE: https://wiki.osdev.org/Serial_Ports
+bool serial_init(void) {
+  serial_outb(SERIAL_PORT + 1, 0x00); 
+  serial_outb(SERIAL_PORT + 3, 0x80); 
+  serial_outb(SERIAL_PORT + 0, 0x03);
+  serial_outb(SERIAL_PORT + 1, 0x00);
+  serial_outb(SERIAL_PORT + 3, 0x03);
+  serial_outb(SERIAL_PORT + 2, 0xc7);
+  serial_outb(SERIAL_PORT + 4, 0x0b);
+  serial_outb(SERIAL_PORT + 4, 0x1e);
+  serial_outb(SERIAL_PORT + 0, 0xae);
+
+  if (serial_inb(SERIAL_PORT + 0) != 0xae) {
+    return false;
+  }
+
+  serial_outb(SERIAL_PORT + 4, 0x0f);
+  return true;
+}
+
+// For printf library
+void putchar_(char c) {
+  serial_write(c);
+}

kernel/hal/x86_64/serial.h

@@ -0,0 +1,8 @@
+#ifndef HAL_SERIAL_H_
+#define HAL_SERIAL_H_
+
+#include <stdbool.h>
+
+bool serial_init(void);
+
+#endif // HAL_SERIAL_H_

kernel/hal/x86_64/serial1.S

@@ -0,0 +1,13 @@
+.global serial_outb
+serial_outb:
+  mov %di, %dx
+  mov %sil, %al
+  out %al, %dx
+  ret
+
+.global serial_inb
+serial_inb:
+  mov %di, %dx
+  in %dx, %al
+  movzx %al, %rax
+  ret