Logger and working GDT

2019-04-27 23:35:28 +01:00
parent bda171256f
commit 6be1414484
15 changed files with 236 additions and 19 deletions
--- a/kernel/gdt.cpp
+++ b/kernel/gdt.cpp
@@ -0,0 +1,50 @@
+#include "gdt.h"
+
+#include <kernel/kernio.h>
+#include <lib/std/memory.h>
+
+struct SegmentDescriptor_t {
+    uint16_t limit_0;
+    uint16_t base_0;
+    uint8_t base_1;
+    uint8_t access;
+    uint8_t limit_1:4;
+    uint8_t flags:4;
+    uint8_t base_2;
+} __attribute__((packed));
+
+SegmentDescriptor_t _GDT[256];
+
+void lgdt(void* GDT, uint16_t size) {
+    struct {
+        uint16_t size;
+        void*    GDT;
+    } __attribute__((packed)) GDTR = { size, GDT };
+ 
+    asm ( "lgdt %0" : : "m"(GDTR) );
+}
+
+void initGDT() {
+    memset(&_GDT, 0, sizeof(_GDT));
+
+    // Leave 0 blank for null segment
+    // Code   Base 0      limit 32    Access EXEC + RW
+    setGDT(1, 0x00000000, 0xFFFFFFFF, GDT_ACCESS_PRESENT | GDT_ACCESS_EXEC | GDT_ACCESS_RW,  GDT_FLAG_GR_PAGE | GDT_FLAG_SZ_32B);
+    // Data   Base 0      Limit 32    Access RW
+    setGDT(2, 0x00000000, 0xFFFFFFFF, GDT_ACCESS_PRESENT | GDT_ACCESS_RW,                    GDT_FLAG_GR_PAGE | GDT_FLAG_SZ_32B);
+
+    lgdt(&_GDT, sizeof(_GDT));
+    SEGMENTS_RELOAD();
+}
+
+void setGDT(uint32_t index, uint32_t baseAddr, uint32_t limitAddr, uint8_t accessLvl, uint8_t flags) {
+    if (index > 256) return;
+    _GDT[index].base_0 = (baseAddr >> 0) & 0xFFFF;
+    _GDT[index].base_1 = (baseAddr >> 16) & 0xFF;
+    _GDT[index].base_2 = (baseAddr>> 24) & 0xFF;
+    _GDT[index].limit_0 = (limitAddr >> 0) & 0xFFFF;
+    _GDT[index].limit_1 = (limitAddr >> 16) & 0x0F;
+    _GDT[index].access = accessLvl;
+    _GDT[index].flags = flags & 0x0F;
+}
+