Enable paging

src/Makefile

@@ -8,11 +8,12 @@ LD_SCRIPT := linker.ld
 BOOT_OBJ := $(addsuffix .o,$(basename $(shell find ./boot -name "*.[c|S]" ! -name "boot.S")))
 UTILS_OBJ := $(addsuffix .o,$(basename $(shell find ./utils -name "*.[c|S]")))
 LIBC_OBJ := $(addsuffix .o,$(basename $(shell find ./libc -name "*.[c|S]")))
+INT_OBJ := $(addsuffix .o,$(basename $(shell find ./int -name "*.[c|S]")))
 
 
 all: $(EXEC)
 
-$(EXEC): boot/boot.o $(BOOT_OBJ) $(UTILS_OBJ) $(LIBC_OBJ) bringelle.o
+$(EXEC): boot/boot.o $(BOOT_OBJ) $(UTILS_OBJ) $(LIBC_OBJ) $(INT_OBJ) bringelle.o
 	ld -n -T $(LD_SCRIPT) -nostdlib -o bringelle $^ 
 
 %.o: %.S

src/boot/boot.S

@@ -4,7 +4,7 @@
 .extern gdt_memcpy
 .extern mb_load_fb_tag
 
-.set STACK_LOCATION, 0x50000
+.set STACK_LOCATION, 0x1FFFFF
 
 .section .multiboot
 

src/bringelle.c

@@ -1,8 +1,10 @@
 #include "libc/stdio.h"
-#include "utils/pic.h"
+#include "int/pic.h"
 #include "boot/multiboot.h"
 #include "utils/mem.h"
 #include "utils/gdt.h"
+#include "utils/paging.h"
+
 
 char show_tics=0;
 
@@ -21,11 +23,14 @@ void bringelle(){
   // Kernel boot sequence
   pic_enable_interrupt();
   print("Interrupts enabled\n");
-  print("Kernel started !\n");
 
+  paging_enable();
+  print("Paging enable!\n");
+  print("Kernel started !");
+
+  show_tics=1;
   // Utask
   print("Launch user task ");
-  show_tics=1;
   memcpy((void*)utask,(void*)0x300000, 100); // 100 bytes seems reasonable to load utask
   asm (
     "cli                      \n\t" // Ensure we do not get interrupted
@@ -33,20 +38,22 @@ void bringelle(){
     "movl %%eax, %0           \n\t" // Save kernel ss segment into the TSS
     "movl %%esp, %1           \n\t" // Save kernel esp into the TSS BEFORE setting up the stack
     "pushl $0x33              \n\t" // Push task ss which is 0x30 along with prlv which is 0x3
-    "pushl $0x400000          \n\t" // Push task esp
+    "pushl $0x30FFFF          \n\t" // Push task esp
     "pushfl                   \n\t" // Retrieve flags
     "popl %%eax               \n\t"
     "orl $0x200, %%eax        \n\t" // Enable interrupt for the user task
     "and $0xffffbfff, %%eax   \n\t" // Clear the NT flags
     "push %%eax               \n\t" // Push task flags
     "push $0x23               \n\t" // Push task cs which is 0x20 along with prlv which is 0x3
-    "push $0                  \n\t" // Push task entry point
+    "push $0x300000           \n\t" // Push task entry point
     "mov $0x2B, %%eax         \n\t" // GDT entry 0x28 along with prlv which is 0x3
     "mov %%eax, %%ds          \n\t" // Setting up user data segment
     "iret                     \n\t" // Launch user task
     : "=m" (TSS.ss0), "=m" (TSS.esp0)
   );
 
+
+
   while(1);
 }
 
@@ -63,3 +70,7 @@ void clock(){
 }
 
 
+void page_fault(){
+  print("Page fault!");
+}
+

src/int/8042.c

@@ -1,6 +1,6 @@
 #include "8042.h"
-#include "framebuffer.h"
-#include "asm.h"
+#include "utils/framebuffer.h"
+#include "utils/asm.h"
 
 DEFINE_AZERTY;
 

src/int/8042.h

@@ -1,7 +1,7 @@
 #ifndef _8042_H
 #define _8042_H
 
-#include "types.h"
+#include "utils/types.h"
 
 void _8042_keypress();
 

src/int/pic.c

@@ -1,7 +1,7 @@
 #include "pic.h"
-#include "asm.h"
-#include "mem.h"
-#include "syscall.h"
+#include "utils/asm.h"
+#include "utils/mem.h"
+#include "utils/syscall.h"
 
 struct IDT_REGISTER IDTR={
     200*8,
@@ -55,14 +55,24 @@ asm (
     "outb %al, $0x20      \n\t"
     "RESTORE_REGS         \n\t"
     "iret                 \n\t"
+"INT_PAGE_FAULT:          \n\t"
+    "SAVE_REGS            \n\t"
+    "call page_fault      \n\t"
+    "hlt                  \n\t"
+    "movb $0x20, %al      \n\t"
+    "outb %al, $0x20      \n\t"
+    "RESTORE_REGS         \n\t"
+    "iret                 \n\t"
 );
 
-extern u32 PIC_IRQ_DEFAULT,PIC_IRQ_PRINT,PIC_IRQ_CLOCK, PIC_IRQ_SYSCALL;
+extern u32 PIC_IRQ_DEFAULT,PIC_IRQ_PRINT,PIC_IRQ_CLOCK, PIC_IRQ_SYSCALL,INT_PAGE_FAULT;
 
 void pic_enable_interrupt(){
     // Map first default 32 entries 
     for(int i=0;i<200;i++){
         pic_add_idt_entry((IDT_ENTRY){0x08,(u32)&PIC_IRQ_DEFAULT,IDT_INT_GATE},i);
+        if(i==14)
+            pic_add_idt_entry((IDT_ENTRY){0x08,(u32)&INT_PAGE_FAULT,IDT_INT_GATE},i);
         if(i==32)
             pic_add_idt_entry((IDT_ENTRY){0x08,(u32)&PIC_IRQ_CLOCK,IDT_INT_GATE},i);
         if(i==33)

src/int/pic.h

@@ -1,7 +1,7 @@
 #ifndef PIC_H
 #define PIC_H
 
-#include "types.h"
+#include "utils/types.h"
 
 #define IDT_INT_GATE 0x8E00
 #define IDT_TRAP_GATE 0xEF00

src/utils/gdt.c

@@ -35,13 +35,13 @@ void gdt_memcpy(){
 
   // ----- User Segments
   GDT_ENTRY ucs_desc;
-  ucs_desc.base=0x300000;
+  ucs_desc.base=0; // With paging will take care of allocating the right address for each task
   ucs_desc.limit=0xFFFFF;
   ucs_desc.flags=GDT_SZ|GDT_GR;
   ucs_desc.access=GDT_PR|GDT_PRVL_3|GDT_S|GDT_EXEC|GDT_RW|GDT_DC;
   
   GDT_ENTRY uds_desc;
-  uds_desc.base=0x300000;
+  uds_desc.base=0;
   uds_desc.limit=0xFFFFF;
   uds_desc.flags=GDT_SZ|GDT_GR;
   uds_desc.access=GDT_PR|GDT_PRVL_3|GDT_S|GDT_RW;

src/utils/paging.c

@@ -0,0 +1,31 @@
+#include "paging.h"
+
+void paging_enable(){
+    int *page_dir=(int*)PAGING_DIR_LOCATION;
+    int *page_table=(int*)PAGING_TABLE_LOCATION;
+
+    // Init page directory
+    for(int i=0;i<1024;i++)
+        page_dir[i]=0;
+    page_dir[0]=(int)page_table;
+    page_dir[0] |=7; // Permissions
+
+    // Init page table 0
+    int addr_offset=0;
+    for(int i=0;i<1024;i++){
+        page_table[i]=addr_offset;
+        page_table[i]|=7; // Permission
+        addr_offset+=4096; // 4Ko pages
+    }
+
+    // Turns on paging
+    asm(
+        "movl %0, %%eax       \n\t"
+        "movl %%eax, %%cr3    \n\t" // Configure page table location
+        "movl %%cr0, %%eax    \n\t"
+        "orl %1, %%eax        \n\t"
+        "movl %%eax, %%cr0    \n\t" // Turn on paging
+        :: "i" (PAGING_DIR_LOCATION), "i" (PAGING_CR0_BIT)
+    );
+
+}

src/utils/paging.h

@@ -0,0 +1,10 @@
+#ifndef PAGING_H
+#define PAGING_H
+
+#define PAGING_CR0_BIT 0x80000000
+#define PAGING_DIR_LOCATION 0x1000
+#define PAGING_TABLE_LOCATION 0x5000
+
+void paging_enable();
+
+#endif

src/utils/syscall.c

@@ -5,11 +5,10 @@
 void syscall(){
     int call_number;
     asm("movl %%eax, %0":"=m"(call_number));
-    int user_ds=gdt_user_ds_base();
     if(call_number==1){
         int msg_addr;
         asm("movl %%ebx, %0":"=m"(msg_addr));
-        char *msg=(char*)user_ds+msg_addr;
+        char *msg=(char*)msg_addr;
         print(msg);
     }
     else{