Support for GDT has been written + add makefile debug mode

12 files changed, 276 insertions, 18 deletions

diff --git a/README.md b/README.md
index b7d31cf..9736ee0 100644
--- a/README.md
+++ b/README.md
@@ -11,15 +11,21 @@ sudo apt update -y
 sudo apt -y install build-essential binutils nasm xorriso grub-common qemu-system-i386 mtools
 ```
 
+Need build GCC cross compiler for i686 architecture to compile project sources.
+Refer to GCC documentation for detailed information - <https://gcc.gnu.org/install/>
+
 ## Build and run
 
 #### Ubuntu
 
+Build and run release version
+```sh
+make all
+```
+
+Build and run debug version
 ```sh
-# Build and create iso image
-make install  
-# Run emulator
-make run
+make DEBUG=true all
 ```
 
 ## Docs
diff --git a/arch/x86/gdt/Gdt.cpp b/arch/x86/gdt/Gdt.cpp
new file mode 100755
index 0000000..63c70ef
--- /dev/null
+++ b/arch/x86/gdt/Gdt.cpp
@@ -0,0 +1,100 @@
+#include "Gdt.h"
+
+
+DescSeg32::DescSeg32(uint32 base, uint32 limit, uint8 access, uint8 flags)
+{
+    this->baseLow = base & 0x0000FFFF;
+    this->baseMiddle = (base & 0x00FF0000) >> 16;
+    this->baseHight = (base & 0xFF000000) >> 24;
+
+    this->limitLow = limit & 0x0000FFFF;
+    this->limitMiddle = (limit & 0x000F0000) >> 16;
+
+    this->access = access;
+    this->flags = flags & 0x000E;
+};
+
+uint64 DescSeg32::getDescriptor()
+{
+    uint64 descriptor = 0;
+
+    descriptor |= (uint64)limitLow;
+    descriptor |= (uint64)baseLow << 16;
+    descriptor |= (uint64)baseMiddle << 32;
+    descriptor |= (uint64)access << 40;
+    descriptor |= (uint64)limitMiddle << 48;
+    descriptor |= (uint64)flags << 52;
+    descriptor |= (uint64)baseHight << 56;
+
+    return descriptor;
+};
+
+uint64 DescSeg32::flatCodeKernel()
+{
+    return DescSeg32(0, 0xFFFFF, CODE_ER | PRESENT | NSYSTEMSEG
+                                    , PAGEGRAN | HIGHSIZE).getDescriptor();    
+};
+
+uint64 DescSeg32::flatDataKernel()
+{
+    return DescSeg32(0, 0xFFFFF, DATA_RW | PRESENT | NSYSTEMSEG
+                                    , PAGEGRAN | HIGHSIZE).getDescriptor();    
+}
+
+uint64 DescSeg32::flatCodeUser()
+{
+
+    return DescSeg32(0, 0xFFFFF, CODE_ER | PRESENT | NSYSTEMSEG | USER
+                                    , PAGEGRAN | HIGHSIZE).getDescriptor();    
+};
+
+uint64 DescSeg32::flatDataUser()
+{
+
+    return DescSeg32(0, 0xFFFFF, DATA_RW | PRESENT | NSYSTEMSEG | USER
+                                    , PAGEGRAN | HIGHSIZE).getDescriptor();    
+};
+
+MngGdt::MngGdt()
+{
+    this->gdt[0] = 0;
+    currIdx = 1;
+    isGdtLoaded = 0;
+};
+
+bool MngGdt::addDescriptor(uint64 desc)
+{
+    if(currIdx >= size || currIdx == 0)
+    {
+        return false;
+    }
+
+    this->gdt[currIdx++] = desc;
+    return true;
+};
+
+bool MngGdt::loadGdt()
+{
+    if(isGdtLoaded)
+    {
+        return false;
+    }
+
+    uint64 pointer = 0;
+    uint16 size = sizeof(uint64) * this->size - 1;
+    uint16 offset = (uint32)((void *)(&gdt));
+
+    pointer |= offset;
+    pointer <<= 16;
+    pointer |= size;
+
+    GOTOGDTMEMSEG(pointer);
+
+    isGdtLoaded = 1;
+    return true;
+};
+
+bool MngGdt::getIsGdtLoaded()
+{
+    return isGdtLoaded;
+};
diff --git a/arch/x86/gdt/Gdt.h b/arch/x86/gdt/Gdt.h
new file mode 100755
index 0000000..e3d48a3
--- /dev/null
+++ b/arch/x86/gdt/Gdt.h
@@ -0,0 +1,82 @@
+#ifndef GDT_H
+#define GDT_H
+
+#include "../inc/types.h"
+
+
+// Define access options
+#define PRESENT (1 << 7)        // Present bit
+#define USER (3 << 5)           // Descriptor privelege level
+#define NSYSTEMSEG (1 << 4)     // Descriptor type
+#define EXEC (1 << 3)           // Executable bit
+#define GROWDOWN (1 << 2)       // Direction bit
+#define WRITABLE (1 << 1)       // Readable/Writable bit
+#define ACCESSED 1              // Accessed bit
+
+// Define flags byte
+#define PAGEGRAN (1 << 3)       // Granularity flag
+#define HIGHSIZE (1 << 2)       // Size flag
+#define LONGMODEON (1 << 1)     // Long-mode flag
+
+// Set of segment descriptors assign acesses bits
+#define DATA_RO         0x00        // data seg, grows up, read only, not accessed
+#define DATA_ROA        0x01        // data seg, grows up, read only, accessed
+#define DATA_RW         0x02        // data seg, grows up, read/write, not accessed
+#define DATA_RWA        0x03        // data seg, grows up, read/write, accessed
+#define DATA_ROD        0x04        // data seg, grows down, read only, not accessed
+#define DATA_RODGA      0x05        // data seg, grows down, read only, accessed
+#define DATA_RWD        0x06        // data seg, grows down, read/write, not accessed
+#define DATA_RWDA       0x07        // data seg, grows down, read/write, accessed
+#define CODE_EO         0x08        // code seg, conforming, execute only, not accessed
+#define CODE_EOA        0x09        // code seg, conforming, execute only, accessed
+#define CODE_ER         0x0A        // code seg, conforming, execute/read, not accessed
+#define CODE_ERA        0x0B        // code seg, conforming, execute/read, accessed
+#define CODE_EONC       0x0C        // code seg, not conforming, execute only, not accessed
+#define CODE_EONCA      0x0D        // code seg, not conforming, execute only, accessed
+#define CODE_ERNC       0x0E        // code seg, not conforming, execute/read, not accessed
+#define CODE_ERNCA      0x0F        // code seg, not conforming, execute/read, accessed
+
+class DescSeg32                     // Segment descriptor
+{
+    private:
+        uint16 limitLow;
+        uint16 baseLow;
+        uint8 baseMiddle;
+        uint8 access;
+        uint8 limitMiddle; // one word limit value 19:16
+        uint8 flags;       // one word located 55:52 bits in descriptor
+        uint8 baseHight;
+    public:
+        DescSeg32(uint32 base, uint32 limit, uint8 access, uint8 flags);
+        void setDescriptor(uint32 base, uint32 limit, uint8 access, uint8 flags);
+        uint64 getDescriptor();
+        static uint64 flatCodeKernel();
+        static uint64 flatDataKernel();
+        static uint64 flatCodeUser();
+        static uint64 flatDataUser();
+} __attribute__((packed));
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+extern void GOTOGDTMEMSEG(uint64 pointer);
+#ifdef __cplusplus
+};
+#endif
+
+class MngGdt
+{
+    private:
+       const static uint8 size = 10;
+       static uint64 gdt[size]; 
+       uint8 currIdx;
+       bool isGdtLoaded;
+
+    public:
+       MngGdt();
+       bool addDescriptor(uint64 desc);  // 0 - not set descriptor, 1 - set
+       bool loadGdt();      // 0 - if GDT is not loaded, 1 - loaded
+       bool getIsGdtLoaded();
+};
+
+#endif
diff --git a/arch/x86/gdt/GlobalObj.cpp b/arch/x86/gdt/GlobalObj.cpp
new file mode 100644
index 0000000..5832c11
--- /dev/null
+++ b/arch/x86/gdt/GlobalObj.cpp
@@ -0,0 +1,14 @@
+#include "GlobalObj.h"
+
+
+uint64 MngGdt::gdt[MngGdt::size];
+
+MngGdt mngGdt;
+
+void mngGdtInit()
+{
+    if(!mngGdt.getIsGdtLoaded())
+    {
+        mngGdt = MngGdt();
+    }
+};
diff --git a/arch/x86/gdt/GlobalObj.h b/arch/x86/gdt/GlobalObj.h
new file mode 100644
index 0000000..563a2a9
--- /dev/null
+++ b/arch/x86/gdt/GlobalObj.h
@@ -0,0 +1,10 @@
+#ifndef GDTGLOBALOBJ_H
+#define GDTGLOBALOBJ_H
+#include "../inc/types.h"
+#include "Gdt.h"
+
+extern MngGdt mngGdt;
+
+void mngGdtInit();
+
+#endif
diff --git a/arch/x86/gdt/GoToGdtMemSeg.s b/arch/x86/gdt/GoToGdtMemSeg.s
new file mode 100644
index 0000000..2b5dd62
--- /dev/null
+++ b/arch/x86/gdt/GoToGdtMemSeg.s
@@ -0,0 +1,13 @@
+global GOTOGDTMEMSEG
+GOTOGDTMEMSEG:
+        lgdt [esp + 4]
+        jmp 0x08:.reloadCS
+.reloadCS:
+        mov ax, 0x10
+        mov ds, ax
+        mov es, ax
+        mov fs, ax
+        mov gs, ax
+        mov ss, ax
+        ret
+.end:
diff --git a/arch/x86/inc/types.h b/arch/x86/inc/types.h
index d688a35..1ec71f3 100644
--- a/arch/x86/inc/types.h
+++ b/arch/x86/inc/types.h
@@ -1,3 +1,5 @@
+#define NULL 0
+
 
 typedef unsigned char uint8;
 typedef unsigned int uint16;
diff --git a/kernel/GlobalConstruct.cpp b/kernel/GlobalConstruct.cpp
new file mode 100755
index 0000000..dc0a83a
--- /dev/null
+++ b/kernel/GlobalConstruct.cpp
@@ -0,0 +1,14 @@
+#include "GlobalConstruct.h"
+
+void GlobalConstruct::terminalInit()
+{
+    display = VGADisplay();
+};
+
+void GlobalConstruct::gdtInit()
+{
+    mngGdtInit();
+    mngGdt.addDescriptor(DescSeg32::flatCodeKernel());
+    mngGdt.addDescriptor(DescSeg32::flatDataKernel()); 
+    mngGdt.loadGdt();
+};
diff --git a/kernel/GlobalConstruct.h b/kernel/GlobalConstruct.h
new file mode 100755
index 0000000..2b0a675
--- /dev/null
+++ b/kernel/GlobalConstruct.h
@@ -0,0 +1,14 @@
+#ifndef GLOBALCONSTRUCT_H
+#define GLOBALCONSTRUCT_H
+
+#include "../arch/x86/io/GlobalObj.h"
+#include "../arch/x86/gdt/GlobalObj.h"
+
+class GlobalConstruct
+{
+    public:
+        static void terminalInit();
+        static void gdtInit();
+};
+
+#endif
diff --git a/kernel/kernel.c b/kernel/kernel.c
index 9a901b1..59caf0a 100644
--- a/kernel/kernel.c
+++ b/kernel/kernel.c
@@ -1,22 +1,13 @@
-#ifdef __cplusplus
-extern "C" {
-#endif
-
+#include "GlobalConstruct.h"
 #include "../arch/x86/io/GlobalObj.h"
 #include "../arch/x86/inc/TypeConverter.h"
 
 void main()
 {
-    VGADisplay d;
-    IntConverter conv;
+    GlobalConstruct::terminalInit();
+    GlobalConstruct::gdtInit();
 
-    unsigned int i = 124;
+    display << "Hello, World!";
 
-    d << conv.intToChar(i);
-    d << "Hello, world!\tHello, world!";
-    for(int i = 0; i < 10; i++)d << "\tHello!";
 };
 
-#ifdef __cplusplus
-};
-#endif
diff --git a/kernel/linker.ld b/kernel/linker.ld
index d5ee742..ae4d98d 100644
--- a/kernel/linker.ld
+++ b/kernel/linker.ld
@@ -12,6 +12,7 @@ SECTIONS
     {
         *(.text)
         *(.eh_frame)
+        *(.ctors)
     }
 
     .rodata BLOCK(4K) : ALIGN(4k)
diff --git a/makefile b/makefile
index 71a7a6c..ab744ff 100644
--- a/makefile
+++ b/makefile
@@ -5,6 +5,7 @@ ASM = nasm
 CFLAGS = -c -m32 -Wall -ffreestanding -nostdinc -nostdlib -lgcc
 AFLAGS = -f elf32
 LDFLAGS = -m elf_i386
+QEMUFLAGS =
 
 CFILES = $(shell find ./ -type f \( -name \*.cpp -o -name \*.c \))
 AFILES = $(shell find ./ -type f \( -iname \*.s -o -name \*.asm \))
@@ -12,12 +13,20 @@ LDFILE = $(shell find ./ -type f -name *.ld)
 SOURCE_FILES = $(CFILES) $(AFILES)
 OBJ_FILES = $(addprefix $(BDIR)/, $(addsuffix .o, $(basename $(SOURCE_FILES))))
 
+ifeq ($(DEBUG), true)
+	CFLAGS := -g3 $(CFLAGS)
+	AFLAGS := -g $(AFLAGS)
+	QEMUFLAGS := -s -S $(QEMUFLAGS)
+endif
+
 OS_BINARY = $(BDIR)/kernel.bin
 BDIR = ./build
 
 .PHONY: install $(SOURCE_FILES)
 
 build: startbuild $(SOURCE_FILES)
+	echo $(AFLAGS)
+	echo $(CFLAGS)
 	@echo "Link object files..."
 	$(LD) $(LDFLAGS) -o $(OS_BINARY) -T $(LDFILE) $(OBJ_FILES)
 	@echo "Project was built"
@@ -45,4 +54,6 @@ clean:
 	rm -rf ./iso/os/kernel.bin
 
 run:
-	 qemu-system-i386 -cdrom ./$(BDIR)/kernel.iso
+	 qemu-system-i386 $(QEMUFLAGS) -cdrom ./$(BDIR)/kernel.iso
+
+all: clean build install run