Initial commit

14 files changed, 309 insertions, 0 deletions

diff --git a/kernel/bootloader.o b/kernel/bootloader.o
new file mode 100644
index 0000000..96a1d55
--- /dev/null
+++ b/kernel/bootloader.o
diff --git a/kernel/bootloader.s b/kernel/bootloader.s
new file mode 100644
index 0000000..36d516f
--- /dev/null
+++ b/kernel/bootloader.s
@@ -0,0 +1,57 @@
+global entrypoint  ; the entry point symbol defined in kernel.ld
+extern mainKernel ; indique la fonction ne se trouve pas dans ce fichier
+
+; Values for the multiboot header
+MULTIBOOT_HEADER_MAGIC     equ 0x1BADB002
+MULTIBOOT_HEADER_FLAGS     equ 0x0
+; magic + checksum + flags must equal 0
+MULTIBOOT_HEADER_CHECKSUM  equ -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS)
+STACK_SIZE equ 256000
+;---------------------------------------------------------------------------------------------------
+; bootloader section
+; This section must be located at the very beginning of the kernel image.
+
+section .bootloader
+align 4    ; section aligned to a 4 bytes boundary
+
+; Minimum multiboot header
+dd MULTIBOOT_HEADER_MAGIC
+dd MULTIBOOT_HEADER_FLAGS
+dd MULTIBOOT_HEADER_CHECKSUM
+
+entrypoint:
+	; Bootloader code starts executing here
+	cli  ; disable hardware interrupts
+
+	; TODO : initialiser le pointeur de pile ainsi qu'EBP (à la même valeur)
+    ; Rappel : la pile "grandi" en descendant !
+	; ...
+	mov esp, stack ; l'adresse de la pile est defini par le label 'stack'
+	add esp, STACK_SIZE ; on deplace le pointeur de pile a la fin de la pile
+	mov ebp, esp
+	
+
+	; TODO : appeler la fonction principale du kernel (code C)
+	 ; Celle-ci doit etre visible par le linker
+	; ...
+	
+	call mainKernel
+
+	; infinite loop (should never get here)
+.forever:
+	hlt
+	jmp .forever
+
+;---------------------------------------------------------------------------------------------------
+; stack section
+
+; TODO : ajouter une section pour la pile kernel dans laquelle
+
+
+; reserver au moins 256KB grace a la directive "resb".
+; Cette section devra etre alignee sur 4 bytes.
+; ...
+section .stack
+
+stack:
+	resb STACK_SIZE
diff --git a/kernel/const.inc b/kernel/const.inc
new file mode 100644
index 0000000..17d17d0
--- /dev/null
+++ b/kernel/const.inc
@@ -0,0 +1,3 @@
+; Must match the values of the same constants in gdt.h!
+GDT_KERNEL_CODE_SELECTOR  equ     0x08
+GDT_KERNEL_DATA_SELECTOR  equ     0x10
diff --git a/kernel/gdt.c b/kernel/gdt.c
new file mode 100644
index 0000000..0a7cfdc
--- /dev/null
+++ b/kernel/gdt.c
@@ -0,0 +1,57 @@
+#include "../common/types.h"
+#include "gdt.h"
+#include "x86.h"
+
+// TODO: déclarer la table GDT
+// Pointeur sur la table GDT
+static gdt_ptr_t   gdt_ptr;
+
+// Build and return a GDT entry given the various arguments (see Intel manuals).
+static gdt_entry_t build_entry(uint32_t base, uint32_t limit, uint8_t type, uint8_t s, uint8_t db, uint8_t granularity, uint8_t dpl) {
+	gdt_entry_t entry;
+    // For a TSS and LDT, base is the addresse of the TSS/LDT structure
+    // and limit is the size of the structure.
+    entry.lim15_0 = limit & 0xffff;
+    entry.base15_0 = base & 0xffff;
+    entry.base23_16 = (base >> 16) & 0xff;
+    entry.type = type;  // See TYPE_xxx flags
+    entry.s = s;        // 1 for segments; 0 for system (TSS, LDT, gates)
+    entry.dpl = dpl;    // privilege level
+    entry.present = 1;  // present in memory
+    entry.lim19_16 = (limit >> 16) & 0xf;
+    entry.avl = 0;      // available for use
+    entry.l = 0;        // should be 0 (64-bit code segment)
+    entry.db = db;      // 1 for 32-bit code and data segments; 0 for system (TSS, LDT, gate)
+    entry.granularity = granularity;  // granularity of the limit value: 0 = 1 byte; 1 = 4096 bytes
+    entry.base31_24 = (base >> 24) & 0xff;
+	return entry;
+}
+
+// Return a NULL entry.
+static gdt_entry_t null_segment() {
+	gdt_entry_t entry;
+    //memset(&entry, 0, sizeof(gdt_entry_t));
+	return entry;
+}
+
+// Return a code segment specified by the base, limit and privilege level passed in arguments.
+static gdt_entry_t code_segment(uint32_t base, uint32_t limit, uint8_t dpl) {
+    return build_entry(base, limit, TYPE_CODE_EXECREAD, S_CODE_OR_DATA, DB_SEG, 1, dpl);
+}
+
+// Return a data segment specified by the base, limit and privilege level passed in arguments.
+static gdt_entry_t data_segment(uint32_t base, uint32_t limit, uint8_t dpl) {
+    return build_entry(base, limit, TYPE_DATA_READWRITE, S_CODE_OR_DATA, DB_SEG, 1, dpl);
+}
+
+// Initialize the GDT
+void gdt_init() {
+	// TODO: fixer la limite de gdt_ptr, puis la faire pointer sur la GDT
+
+	// TODO: initialisation des trois descripteurs de segment: NULL, segment code, segment data
+	// Les descripteurs de code et data doivent avoir un DPL de 0.
+
+    // Load the GDT
+    gdt_flush(&gdt_ptr);
+}
+
diff --git a/kernel/gdt.h b/kernel/gdt.h
new file mode 100644
index 0000000..03f575e
--- /dev/null
+++ b/kernel/gdt.h
@@ -0,0 +1,36 @@
+#ifndef _GDT_H_
+#define _GDT_H_
+
+// Structure of a GDT descriptor. There are 2 types of descriptors: segments and TSS.
+// Section 3.4.5 of Intel 64 & IA32 architectures software developer's manual describes
+// segment descriptors while section 6.2.2 describes TSS descriptors.
+typedef struct gdt_entry_st {
+    uint16_t lim15_0;
+    uint16_t base15_0;
+    uint8_t base23_16;
+
+    uint8_t type : 4;
+    uint8_t s : 1;
+    uint8_t dpl : 2;
+    uint8_t present : 1;
+
+    uint8_t lim19_16 : 4;
+    uint8_t avl : 1;
+    uint8_t l : 1;
+    uint8_t db : 1;
+    uint8_t granularity : 1;
+
+    uint8_t base31_24;
+} __attribute__((packed)) gdt_entry_t;
+
+// Structure describing a pointer to the GDT descriptor table.
+// This format is required by the lgdt instruction.
+typedef struct gdt_ptr_st {
+    uint16_t limit;    // Limit of the table (ie. its size)
+    uint32_t base;     // Address of the first entry
+} __attribute__((packed)) gdt_ptr_t;
+
+extern void gdt_init();
+extern void gdt_flush(gdt_ptr_t *gdt_ptr);
+
+#endif
diff --git a/kernel/gdt.o b/kernel/gdt.o
new file mode 100644
index 0000000..da9ac7d
--- /dev/null
+++ b/kernel/gdt.o
diff --git a/kernel/gdt_asm.o b/kernel/gdt_asm.o
new file mode 100644
index 0000000..f6e32e2
--- /dev/null
+++ b/kernel/gdt_asm.o
diff --git a/kernel/gdt_asm.s b/kernel/gdt_asm.s
new file mode 100644
index 0000000..9e59544
--- /dev/null
+++ b/kernel/gdt_asm.s
@@ -0,0 +1,19 @@
+%include "const.inc"
+
+global gdt_flush
+
+section .text:           ; start of the text (code) section
+align 4                  ; the code must be 4 byte aligned
+
+gdt_flush:
+    mov     eax,[esp+4]  ; Get the pointer to the GDT, passed as a parameter.
+    lgdt    [eax]        ; Load the new GDT pointer
+    mov     ax,GDT_KERNEL_DATA_SELECTOR   ; offset in the GDT of the kernel data segment
+    mov     ds,ax        ; Load all data segment selectors
+    mov     es,ax
+    mov     fs,ax
+    mov     gs,ax
+    mov     ss,ax
+    jmp     GDT_KERNEL_CODE_SELECTOR:.flush  ; far jump [selector:offset]
+.flush:
+ret
diff --git a/kernel/kernel.c b/kernel/kernel.c
new file mode 100644
index 0000000..d01eada
--- /dev/null
+++ b/kernel/kernel.c
@@ -0,0 +1,15 @@
+extern void smiley();
+
+void mainKernel(){
+	
+	#ifdef TEST
+		// MODE TEST
+		smiley();			
+	
+	#else
+		//MODE NORMAL
+	#endif
+	
+	
+	while(1);
+}
diff --git a/kernel/kernel.ld b/kernel/kernel.ld
new file mode 100644
index 0000000..da9e019
--- /dev/null
+++ b/kernel/kernel.ld
@@ -0,0 +1,36 @@
+ENTRY(entrypoint)            /* the entry point */
+
+SECTIONS {
+    . = 0x100000;            /* all sections located above 1MB */
+
+    .bootloader ALIGN(4K):   /* multiboot header first (needs to reside within the first 8KB) */
+    {
+        *(.bootloader)
+    }
+
+    .stack ALIGN(4K):        /* kernel stack */
+    {
+        *(.stack)
+    }
+
+    .text ALIGN(4K) :        /* code */
+    {
+        *(.text*)            
+    }
+
+    .rodata ALIGN(4K) :      /* read-only data */
+    {
+        *(.rodata*)          
+    }
+
+    .data ALIGN(4K) :        /* initialized data */
+    {
+        *(.data*)
+    }
+
+    .bss ALIGN(4K) :         /* unitialized data */
+    {
+        *(COMMON)
+        *(.bss*)
+    }
+}
diff --git a/kernel/kernel.o b/kernel/kernel.o
new file mode 100644
index 0000000..b000856
--- /dev/null
+++ b/kernel/kernel.o
diff --git a/kernel/kernel_asm.s b/kernel/kernel_asm.s
new file mode 100644
index 0000000..6005121
--- /dev/null
+++ b/kernel/kernel_asm.s
@@ -0,0 +1,7 @@
+global smiley
+
+section .text
+
+smiley:
+	mov eax,0xB8000
+	mov word [eax],0x0E01
diff --git a/kernel/makefile b/kernel/makefile
new file mode 100644
index 0000000..0173172
--- /dev/null
+++ b/kernel/makefile
@@ -0,0 +1,24 @@
+all: run
+
+run : ld
+
+ld: kernel.o bootloader.o gdt.o gdt_asm.o
+	ld -Tkernel.ld -melf_i386 gdt_asm.o bootloader.o kernel.o gdt.o -o kernel.elf
+
+kernel.o: kernel.c kernel_asm.o
+	gcc -DTEST -std=gnu99 -m32 -fno-builtin -ffreestanding -Wall -Wextra -c kernel.c
+
+kernel_asm.o: kernel_asm.s
+	nasm -f elf32 $<
+
+bootloader.o: bootloader.s  	
+	nasm -f elf32 bootloader.s
+
+gdt.o: gdt.c gdt.h 
+	gcc -std=gnu99 -m32 -fno-builtin -ffreestanding -Wall -Wextra -c gdt.c
+
+gdt_asm.o: gdt_asm.s
+	nasm -f elf32 $<
+
+clean:
+	rm -f *.o 
\ No newline at end of file
diff --git a/kernel/x86.h b/kernel/x86.h
new file mode 100644
index 0000000..716cb6c
--- /dev/null
+++ b/kernel/x86.h
@@ -0,0 +1,55 @@
+#ifndef _X86_H_
+#define _X86_H_
+
+// Privilege levels
+#define DPL_USER    0x3
+#define DPL_KERNEL  0x0
+
+// Selectors
+#define LDT_SELECTOR    0x4
+
+// Descriptor types for code and data segments
+#define TYPE_DATA_READONLY     1
+#define TYPE_DATA_READWRITE    3
+#define TYPE_CODE_EXECONLY     9
+#define TYPE_CODE_EXECREAD    11
+
+// Descriptor types for system segments and gates
+#define TYPE_LDT               2
+#define TYPE_TASK_GATE         5
+#define TYPE_TSS               9
+#define TYPE_CALL_GATE         12
+#define TYPE_TRAP_GATE         15
+#define TYPE_INTERRUPT_GATE    14
+
+// Descriptor system bit (S)
+// For code or data segments
+#define S_CODE_OR_DATA   1
+// For TSS segment, LDT, call gate, interrupt gate, trap gate, task gate
+#define S_SYSTEM   0
+
+// D/B bit
+#define DB_SEG  1
+#define DB_SYS  0
+
+// kernel code and data selectors in the GDT
+#define GDT_KERNEL_CODE_SELECTOR  0x08
+#define GDT_KERNEL_DATA_SELECTOR  0x10
+
+// Disable hardware interrupts.
+static inline void cli() {
+    asm volatile("cli");
+}
+
+// Enable hardware interrupts.
+static inline void sti() {
+    asm volatile("sti");
+}
+
+// Halt the processor.
+// External interrupts wake up the CPU, hence the cli instruction.
+static inline void halt() {
+	while (1) asm volatile("cli\nhlt");
+}
+
+#endif